| development of the cerebellum in the platypus (ornithorhynchus anatinus) and short-beaked echidna (tachyglossus aculeatus). | the monotremes are a unique group of mammals whose young are incubated in a leathery-shelled egg and fed with milk from teatless areolae after hatching. as soon as they hatch, monotreme young must be able to maneuver around the nest or maternal pouch to locate the areolae and stimulate milk ejection. in the present study, the embryological collections at the museum für naturkunde, berlin, have been used to follow the development of the monotreme cerebellum through incubation and lactational phas ... | 2012 | 22572119 |
| erythrocyte phosphates and hemoglobin function in monotremes and some marsupials. | hematologic values, red blood cell (rbc) organic phosphate composition, hemoglobin function, and hemoglobin composition have been determined on blood from the monotremes, the duckbill platypus and the echidna, and three species of marsupials, the tasmanian devil, the wallaby, and the brush-tail possum. blood from the platypus had a rbc count of 8.63 x 10(6)/mm3, a mean corpuscular volume of 49.1 millemicron3, and a white blood cell count of 26.0 x 10(3)/mm3. the rbcs from the monotremes and the ... | 1984 | 6696146 |
| development of the spinal cord and peripheral nervous system in platypus (ornithorhynchus anatinus) and short-beaked echidna (tachyglossus aculeatus). | the modern monotremes (platypus and echidnas) are characterized by development of their young in a leathery egg that is laid into a nest or abdominal pouch. at hatching, the young are externally immature, with forelimbs capable of digitopalmar prehension, but hindlimbs little advanced beyond limb buds. the embryological collections at the museum für naturkunde in berlin were used to examine the development of the spinal cord and early peripheral nervous system in developing monotremes and to cor ... | 2012 | 22401666 |
| evidence for an endogenous papillomavirus-like element in the platypus genome. | papillomaviruses (pvs) infect a wide range of vertebrates and have diversified into multiple genetic types, some of which have serious consequences for human health. although pvs have to date only been characterized as exogenous viral forms, here we report the observation of an endogenous viral element (epvloa) in the genome of the platypus (ornithorhynchus anatinus) that is related to pvs. further data mining for endogenous pv-like elements is therefore warranted. | 2012 | 22422067 |
| novel genotypes of trypanosoma binneyi from wild platypuses (ornithorhynchus anatinus) and identification of a leech as a potential vector. | little is known about the prevalence and pathogenesis of trypanosomes in australian monotremes, and few genetic characterisation studies have been conducted with these haemoparasites. during the present investigation, molecular and microscopic methods were used to screen peripheral blood (n=28) and ectoparasites (n=10 adult ticks; n=5 tick nymphs; n=1 leech; and n>500 tick eggs) collected from wild tasmanian platypuses (ornithorhynchus anatinus), for the presence of trypanosomatid-specific dna a ... | 2014 | 25045852 |
| phylogenetic relationships of trypanosoma chelodina and trypanosoma binneyi from australian tortoises and platypuses inferred from small subunit rrna analyses. | trypanosome infections are often difficult to detect by conventional microscopy and their pleomorphy often confounds differential diagnosis. molecular techniques are now being used to diagnose infections and to determine phylogenetic relationships between species. complete small subunit rrna gene sequences were determined for isolates of trypanosoma chelodina from the brisbane river tortoise (emydura signata), the saw-shelled tortoise (elseya latisternum), and the eastern snake-necked tortoise ( ... | 2001 | 11719959 |
| haematological, serum biochemical and serological features of platypuses with and without mycotic granulomatous dermatitis. | to determine whether there are haematological, serum biochemical and serological differences between platypuses (ornithorhynchus anatinus) with and without granulomatous dermatitis due to mucor amphibiorum infection. an additional objective was to establish reference haematological and serum biochemical ranges for the species in tasmania. | 1999 | 10685184 |
| molecular evolution of the neurohypophysial hormone precursors in mammals: comparative genomics reveals novel mammalian oxytocin and vasopressin analogues. | among vertebrates the neurohypophysial hormones show considerable variation. however, in eutherian mammals they have been considered rather conserved, with arginine vasopressin (avp) and oxytocin (ot) in all species except pig and some relatives, where lysine vasopressin replaces avp. the availability of genomic data for a wide range of mammals makes it possible to assess whether these peptides and their precursors may be more variable in eutheria than previously suspected. a survey of these dat ... | 2012 | 22995712 |
| lung development of monotremes: evidence for the mammalian morphotype. | the reproductive strategies and the extent of development of neonates differ markedly between the three extant mammalian groups: the monotremata, marsupialia, and eutheria. monotremes and marsupials produce highly altricial offspring whereas the neonates of eutherian mammals range from altricial to precocial. the ability of the newborn mammal to leave the environment in which it developed depends highly on the degree of maturation of the cardio-respiratory system at the time of birth. the lung s ... | 2009 | 19051249 |
| characterisation of monotreme caseins reveals lineage-specific expansion of an ancestral casein locus in mammals. | using a milk-cell cdna sequencing approach we characterised milk-protein sequences from two monotreme species, platypus (ornithorhynchus anatinus) and echidna (tachyglossus aculeatus) and found a full set of caseins and casein variants. the genomic organisation of the platypus casein locus is compared with other mammalian genomes, including the marsupial opossum and several eutherians. physical linkage of casein genes has been seen in the casein loci of all mammalian genomes examined and we conf ... | 2009 | 19874726 |
| deep-sequencing to resolve complex diversity of apicomplexan parasites in platypuses and echidnas: proof of principle for wildlife disease investigation. | the short-beaked echidna (tachyglossus aculeatus) and the platypus (ornithorhynchus anatinus) are iconic egg-laying monotremes (mammalia: monotremata) from australasia. the aim of this study was to demonstrate the utility of diversity profiles in disease investigations of monotremes. using small subunit (18s) rdna amplicon deep-sequencing we demonstrated the presence of apicomplexan parasites and confirmed by direct and cloned amplicon gene sequencing theileria ornithorhynchi, theileria tachyglo ... | 2017 | 28919547 |
| mitogen-induced responses in lymphocytes from platypus, the tasmanian devil and the eastern barred bandicoot. | as the platypus (ornithorhynchus anatinus), the tasmanian devil (sarcophilus harrisi) and the eastern barred bandicoot (perameles gunni) are currently at risk of serious population decline or extinction from fatal diseases in tasmania, the goal of the present study was to describe the normal immune response of these species to challenge using the lymphocyte proliferation assay, to give a solid basis for further studies. | 2008 | 18826514 |
| diversity at the major histocompatibility complex class ii in the platypus, ornithorhynchus anatinus. | the platypus (ornithorhynchus anatinus) is the sole survivor of a previously widely distributed and diverse lineage of ornithorhynchid monotremes. its dependence on healthy water systems imposes an inherent sensitivity to habitat degradation and climate change. here, we compare genetic diversity at the major histocompatibility complex (mhc) class ii-dzb gene and 3 mhc-associated microsatellite markers with diversity at 6 neutral microsatellite markers in 70 platypuses from across their range, in ... | 2012 | 22563128 |
| development of the hypothalamus and pituitary in platypus (ornithorhynchus anatinus) and short-beaked echidna (tachyglossus aculeatus). | the living monotremes (platypus and echidnas) are distinguished by the development of their young in a leathery-shelled egg, a low and variable body temperature and a primitive teat-less mammary gland. their young are hatched in an immature state and must deal with the external environment, with all its challenges of hypothermia and stress, as well as sourcing nutrients from the maternal mammary gland. the hill and hubrecht embryological collections have been used to follow the structural develo ... | 2012 | 22512474 |
| the prime minister and the platypus: a paradox goes to war. | in february 1943, in the midst of the second world war, prime minister winston churchill demanded that a live duck-billed platypus be sent from australia to britain. a vigorous male was shipped off but died shortly before arrival in britain. this request can only be understood if placed in the context of churchill's passion for exotic pets as well as the rich history of aristocratic menageries and live diplomatic gifts. obtaining an animal hitherto unseen alive in europe would have been a great ... | 2012 | 22326098 |
| ten polymorphic microsatellite dna markers for the platypus, ornithorhynchus anatinus. | we identified and optimized 10 microsatellite loci for the platypus, ornithorhynchus anatinus (monotremata: ornithorhynchidae), and screened 21 individuals from the southern tablelands area of new south wales, australia. each polymorphic locus possessed between two and 12 alleles with observed heterozygosities between 0.118 and 0.950. the intent of this effort was to provide informative loci for studies on the population genetics of this species. | 2008 | 21585993 |
| a model for the evolution of the mammalian t-cell receptor α/δ and μ loci based on evidence from the duckbill platypus. | the specific recognition of antigen by t cells is critical to the generation of adaptive immune responses in vertebrates. t cells recognize antigen using a somatically diversified t-cell receptor (tcr). all jawed vertebrates use four tcr chains called α, β, γ, and δ, which are expressed as either a αβ or γδ heterodimer. nonplacental mammals (monotremes and marsupials) are unusual in that their genomes encode a fifth tcr chain, called tcrµ, whose function is not known but is also somatically dive ... | 2012 | 22593227 |
| structural characterization of a novel monotreme-specific protein with antimicrobial activity from the milk of the platypus. | monotreme lactation protein (mlp) is a recently identified protein with antimicrobial activity. it is present in the milk of monotremes and is unique to this lineage. to characterize mlp and to gain insight into the potential role of this protein in the evolution of lactation, the crystal structure of duck-billed platypus (ornithorhynchus anatinus) mlp was determined at 1.82 å resolution. this is the first structure to be reported for this novel, mammalian antibacterial protein. mlp was expresse ... | 2018 | 29372906 |
| distinct development of peripheral trigeminal pathways in the platypus (ornithorhynchus anatinus) and short-beaked echidna (tachyglossus aculeatus). | the extant monotremes (platypus and echidnas) are believed to all be capable of electroreception in the trigeminal pathways, although they differ significantly in the number and distribution of electroreceptors. it has been argued by some authors that electroreception was first developed in an aquatic environment and that echidnas are descended from a platypus-like ancestor that invaded an available terrestrial habitat. if this were the case, one would expect the developmental trajectories of th ... | 2012 | 22179203 |
| development of the dorsal and ventral thalamus in platypus (ornithorhynchus anatinus) and short-beaked echidna (tachyglossus aculeatus). | the living monotremes (platypus and echidnas) are distinguished from therians as well as each other in part by the unusual structure of the thalamus in each. in particular, the platypus has an enlarged ventral posterior (vp) nucleus reflecting the great behavioural importance of trigeminosensation and electroreception. the embryological collections of the museum für naturkunde in berlin were used to analyse the development of the dorsal thalamus and ventral thalamus (prethalamus) in both species ... | 2012 | 22113857 |
| description of a cranial endocast from a fossil platypus, obdurodon dicksoni (monotremata, ornithorhynchidae), and the relevance of endocranial characters to monotreme monophyly. | a digital cranial endocast of the miocene platypus obdurodon dicksoni was extracted from high-resolution x-ray computed tomography scans. this endocast represents the oldest from an unequivocal member of either extant monotreme lineage and is therefore important for inferring character support for monotremata, a clade that is not well diagnosed. we describe the obdurodon endocast with reference to endocasts extracted from skulls of the three species of extant monotremes, particularly ornithorhyn ... | 2006 | 16710845 |
| platypus tcrμ provides insight into the origins and evolution of a uniquely mammalian tcr locus. | tcrμ is an unconventional tcr that was first discovered in marsupials and appears to be absent from placental mammals and nonmammals. in this study, we show that tcrμ is also present in the duckbill platypus, an egg-laying monotreme, consistent with tcrμ being ancient and present in the last common ancestor of all extant mammals. as in marsupials, platypus tcrμ is expressed in a form containing double v domains. these v domains more closely resemble ab v than that of conventional tcr. platypus t ... | 2011 | 21976776 |
| more sex chromosomes than autosomes in the amazonian frog leptodactylus pentadactylus. | heteromorphic sex chromosomes are common in eukaryotes and largely ubiquitous in birds and mammals. the largest number of multiple sex chromosomes in vertebrates known today is found in the monotreme platypus (ornithorhynchus anatinus, 2n = 52) which exhibits precisely 10 sex chromosomes. interestingly, fish, amphibians, and reptiles have sex determination mechanisms that do or do not involve morphologically differentiated sex chromosomes. relatively few amphibian species carry heteromorphic sex ... | 2018 | 29372309 |
| hematologic, plasma biochemical, and other indicators of the health of tasmanian platypuses (ornithorhynchus anatinus): predictors of mucormycosis. | the fungal disease mucormycosis has affected tasmanian platypuses for nearly three decades. we investigated the influences of mucormycosis on the hematologic, plasma biochemical, and other indicators of health in free-living platypuses across 18 tasmanian river catchments. live trapping enabled sampling of 161 (apparently) healthy and six ulcerated, mucormycosis-affected platypuses in 75 rivers and streams between january 2008 and june 2009. there were no obvious differences in any hematologic o ... | 2011 | 21719813 |
| a need for dynamic hematology and serum biochemistry reference tools: novel use of sine wave functions to produce seasonally varying reference curves in platypuses (ornithorhynchus anatinus). | seasonal changes in hematology and serum biochemistry results, described by separate reference intervals for different seasons, have been reported in many animals. we developed a novel method to investigate seasonal variation in values and a reference tool (the reference curve) based on sine wave functions that, for suitable variables, represents data more appropriately than a fixed reference interval. we applied these techniques to values observed in blood samples from 126 adult wild platypuses ... | 2017 | 28139954 |
| investigation into individual health and exposure to infectious agents of platypuses (ornithorhynchus anatinus) in two river catchments in northwest tasmania. | changes in the health of individuals within wildlife populations can be a cause or effect of population declines in wildlife species. aspects of individual platypus ( ornithorhynchus anatinus ) health have been reported. however, holistic studies investigating potential synergistic effects of both pathogens and environmental factors are needed to expand understanding of platypus individual health. we collected baseline data on the health of platypuses in two tasmanian river catchments (including ... | 2017 | 28118556 |
| inner ear labyrinth anatomy of monotremes and implications for mammalian inner ear evolution. | the monophyletic clade monotremata branches early from the rest of the mammalian crown group in the jurassic and members of this clade retain many ancestral mammalian traits. thus, accurate and detailed anatomical descriptions of this group can offer unique insight into the early evolutionary history of mammalia. in this study, we examine the inner ear anatomy of two extant monotremes, ornithorhynchus anatinus and tachyglossus aculeatus, with the primary goals of elucidating the ancestral mammal ... | 2017 | 27889918 |
| comparative cranial morphology in living and extinct platypuses: feeding behavior, electroreception, and loss of teeth. | the modern platypus,ornithorhynchus anatinus, has an eye structure similar to aquatic mammals; however, platypuses also have a "sixth sense" associated with the bill electro- and mechanoreception that they use without opening their eyes underwater. we hypothesize thatornithorhynchusand the miocene taxonobdurodonhave different sensory capacities, which may have resulted from differences in foraging behavior. to estimate differences in foraging, sensory systems, and anatomical divergence between t ... | 2016 | 27757425 |
| the platypus in edinburgh: robert jameson, robert knox and the place of the ornithorhynchus in nature, 1821-24. | the duck-billed platypus, or ornithorhynchus, was the subject of an intense debate among natural historians in the late eighteenth and early nineteenth centuries. its paradoxical mixture of mammalian, avian and reptilian characteristics made it something of a taxonomic conundrum. in the early 1820s robert jameson (1774-1854), the professor of natural history at the university of edinburgh and the curator of the university's natural history museum, was able to acquire three valuable specimens of ... | 2016 | 27671001 |
| life history and dynamics of a platypus (ornithorhynchus anatinus) population: four decades of mark-recapture surveys. | knowledge of the life-history and population dynamics of australia's iconic and evolutionarily distinct platypus (ornithorhynchus anatinus) remains poor. we marked-recaptured 812 unique platypuses (total 1,622 captures), over four decades (1973-2014) in the shoalhaven river, australia. strong sex-age differences were observed in life-history, including morphology and longevity. apparent survival of adult females (φ = 0.76) were higher than adult males (φ = 0.57), as in juveniles: females φ = 0.2 ... | 2015 | 26536832 |
| a peculiar lamin in a peculiar mammal: expression of lamin liii in platypus (ornithorhynchus anatinus). | platypus (ornithorhynchus anatinus) holds a unique phylogenetic position at the base of the mammalian lineage due to an amalgamation of mammalian and sauropsid-like features. here we describe the set of four lamin genes for platypus. lamins are major components of the nuclear lamina, which constitutes a main component of the nucleoskeleton and is involved in a wide range of nuclear functions. vertebrate evolution was accompanied by an increase in the number of lamin genes from a single gene in t ... | 2015 | 26213206 |
| a spur to atavism: placing platypus poison. | for over two centuries, the platypus (ornithorhynchus anatinus) has been constructed and categorized in multiple ways. an unprecedented mélange of anatomical features and physiological functions, it long remained a systematic quandary. nevertheless, since 1797, naturalists and biologists have pursued two recurring obsessions. investigations into platypus reproduction and lactation have focused attention largely upon females of the species. despite its apparent admixture of avian, reptilian and m ... | 2015 | 25964144 |
| immunohistochemical analysis of pancreatic islets of platypus (ornithorhynchus anatinus) and echidna (tachyglossus aculeatus ssp.). | monotremes have undergone remarkable changes to their digestive and metabolic control system; however, the monotreme pancreas remains poorly characterized. previous work in echidna demonstrated the presence of pancreatic islets, but no information is available for platypus and the fine structure has not been described for either monotreme. based on our recent finding that monotremes lack the ghrelin gene, which is expressed in mouse and human pancreatic islets, we investigated the structure of m ... | 2015 | 25682842 |
| 4-o-acetyl-sialic acid (neu4,5ac2) in acidic milk oligosaccharides of the platypus (ornithorhynchus anatinus) and its evolutionary significance. | monotremes (echidnas and platypus) retain an ancestral form of reproduction: egg-laying followed by secretion of milk onto skin and hair in a mammary patch, in the absence of nipples. offspring are highly immature at hatching and depend on oligosaccharide-rich milk for many months. the primary saccharide in long-beaked echidna milk is an acidic trisaccharide neu4,5ac2(α2-3)gal(β1-4)glc (4-o-acetyl 3'-sialyllactose), but acidic oligosaccharides have not been characterized in platypus milk. in thi ... | 2015 | 25601457 |
| investigation into the characteristics, triggers and mechanism of apnoea and bradycardia in the anaesthetized platypus (ornithorhynchus anatinus). | health and conservation research on platypuses (ornithorhynchus anatinus) may require anaesthesia to reduce stress and the risk of injury to both the animal and the researcher, as well as to facilitate examination and sample collection. platypus anaesthesia can be difficult to manage, with reports of periods of apnoea and bradycardia described. this study investigated the conditions around sudden-onset apnoea and bradycardia in 163 field-anaesthetized platypuses as part of a health study. anaest ... | 2014 | 27293674 |
| small population size and extremely low levels of genetic diversity in island populations of the platypus, ornithorhynchus anatinus. | genetic diversity generally underpins population resilience and persistence. reductions in population size and absence of gene flow can lead to reductions in genetic diversity, reproductive fitness, and a limited ability to adapt to environmental change increasing the risk of extinction. island populations are typically small and isolated, and as a result, inbreeding and reduced genetic diversity elevate their extinction risk. two island populations of the platypus, ornithorhynchus anatinus, exi ... | 2012 | 22837830 |
| replication asynchrony and differential condensation of x chromosomes in female platypus (ornithorhynchus anatinus). | a common theme in the evolution of sex chromosomes is the massive loss of genes on the sex-specific chromosome (y or w), leading to a gene imbalance between males (xy) and females (xx) in a male heterogametic species, or between zz and zw in a female heterogametic species. different mechanisms have evolved to compensate for this difference in dosage of x-borne genes between sexes. in therian mammals, one of the x chromosomes is inactivated, whereas bird dosage compensation is partial and gene-sp ... | 2009 | 19874719 |
| ornithorhynchus anatinus (platypus) links the evolution of immunoglobulin genes in eutherian mammals and nonmammalian tetrapods. | the evolutionary origins of mammalian immunoglobulin h chain isotypes (igm, igd, igg, ige, and iga) are still incompletely understood as these isotypes differ considerably in structure and number from their counterparts in nonmammalian tetrapods. we report in this study that the platypus (ornithorhynchus anatinus) ig h chain constant region gene locus contains eight ig encoding genes, which are arranged in an mu-delta-omicron-gamma2-gamma1-alpha1-epsilon-alpha2 order, spanning a total of approxi ... | 2009 | 19675164 |
| genome analysis of the platypus reveals unique signatures of evolution. | we present a draft genome sequence of the platypus, ornithorhynchus anatinus. this monotreme exhibits a fascinating combination of reptilian and mammalian characters. for example, platypuses have a coat of fur adapted to an aquatic lifestyle; platypus females lactate, yet lay eggs; and males are equipped with venom similar to that of reptiles. analysis of the first monotreme genome aligned these features with genetic innovations. we find that reptile and platypus venom proteins have been co-opte ... | 2008 | 18464734 |
| defensins and the convergent evolution of platypus and reptile venom genes. | when the platypus (ornithorhynchus anatinus) was first discovered, it was thought to be a taxidermist's hoax, as it has a blend of mammalian and reptilian features. it is a most remarkable mammal, not only because it lays eggs but also because it is venomous. rather than delivering venom through a bite, as do snakes and shrews, male platypuses have venomous spurs on each hind leg. the platypus genome sequence provides a unique opportunity to unravel the evolutionary history of many of these inte ... | 2008 | 18463304 |
| characterizing the chromosomes of the platypus (ornithorhynchus anatinus). | like the unique platypus itself, the platypus genome is extraordinary because of its complex sex chromosome system, and is controversial because of difficulties in identification of small autosomes and sex chromosomes. a 6-fold shotgun sequence of the platypus genome is now available and is being assembled with the help of physical mapping. it is therefore essential to characterize the chromosomes and resolve the ambiguities and inconsistencies in identifying autosomes and sex chromosomes. we ha ... | 2007 | 18185982 |
| the hypothalamic supraoptic and paraventricular nuclei of the echidna and platypus. | the monotremes are an intriguing group of mammals that have major differences in their reproductive physiology and lactation from therian mammals. monotreme young hatch from leathery skinned eggs and are nourished by milk secreted onto areolae rather than through nipples. parturition and lactation are in part controlled through the paraventricular and supraoptic nuclei of the hypothalamus. we have used nissl staining, enzyme histochemistry, immunohistochemistry for tyrosine hydroxylase, calbindi ... | 2006 | 16809908 |
| tcr gamma chain diversity in the spleen of the duckbill platypus (ornithorhynchus anatinus). | tcr gamma (trg) chain diversity in splenic gammadelta t cells was determined for an egg-laying mammal (or monotreme), the duckbill platypus. three distinct v subgroups were found in the expressed trg chains and these three subgroups are members of a clade not found so far in eutherian mammals or birds. each subgroup contains approximately five v gene segments, and their overall divergence is much less than is found in eutherians and birds, consistent with their recent evolution from an ancestral ... | 2006 | 16303181 |
| chromosome chains and platypus sex: kinky connections. | mammal sex determination depends on an xy chromosome system, a gene for testis development and a means of activating the x chromosome. the duckbill platypus challenges these dogmas.(1,2) gutzner et al.(1) find no recognizable sry sequence and question whether the mammalian x was even the original sex chromosome in the platypus. instead they suggest that the original platypus sex chromosomes were derived from the zw chromosome system of birds and reptiles. unraveling the puzzles of sex determinat ... | 2005 | 15954092 |
| the complexity of expressed kappa light chains in egg-laying mammals. | complementary dnas encoding immunoglobulin light chains were isolated from two monotreme species, ornithorhynchus anatinus (duckbill platypus) and tachyglossus aculeatus (echidna). the sequences of both the variable and constant regions of these clones had greater similarity to igk than to other light chain classes and phylogenetic analyses place them squarely within the mammalian igk group, establishing them as monotreme igk homologues. the constant region sequences of all clones were essential ... | 2004 | 15448942 |
| new proteins identified in epididymal fluid from the platypus (ornithorhynchus anatinus). | the platypus epididymal proteome is being studied because epididymal proteins are essential for male fertility in mammals and it is considered that knowledge of the epididymal proteome in an early mammal would be informative in assessing the convergence and divergence of proteins that are important in the function of the mammalian epididymis. few of the epididymal proteins that have been identified in eutherian mammals were found in platypus caudal epididymal fluid, and the major epididymal prot ... | 2009 | 19874724 |
| platypus chain reaction: directional and ordered meiotic pairing of the multiple sex chromosome chain in ornithorhynchus anatinus. | monotremes are phylogenetically and phenotypically unique animals with an unusually complex sex chromosome system that is composed of ten chromosomes in platypus and nine in echidna. these chromosomes are alternately linked (x1y1, x2y2, ...) at meiosis via pseudoautosomal regions and segregate to form spermatozoa containing either x or y chromosomes. the physical and epigenetic mechanisms involved in pairing and assembly of the complex sex chromosome chain in early meiotic prophase i are complet ... | 2009 | 19874721 |
| analysis of sine and line repeat content of y chromosomes in the platypus, ornithorhynchus anatinus. | monotremes feature an extraordinary sex-chromosome system that consists of five x and five y chromosomes in males. these sex chromosomes share homology with bird sex chromosomes but no homology with the therian x. the genome of a female platypus was recently completed, providing unique insights into sequence and gene content of autosomes and x chromosomes, but no y-specific sequence has so far been analysed. here we report the isolation, sequencing and analysis of approximately 700 kb of sequenc ... | 2009 | 19874720 |
| energetics of foraging and locomotion in the platypus ornithorhynchus anatinus. | we measured the energy requirements of platypuses foraging, diving and resting in a swim tank using flow-through respirometry. also, walking metabolic rates were obtained from platypuses walking on a conventional treadmill. energy requirements while foraging were found to depend on water temperature, body weight and dive duration and averaged 8.48 w kg(-1). rates for subsurface swimming averaged 6.71 w kg(-1). minimal cost of transport for subsurface swimming platypuses was 1.85 j n(-1)m(-1) at ... | 2001 | 11585262 |
| the claustrum is not missing from all monotreme brains. | many authors have reported that the claustrum, which comprises the insular claustrum and the endopiriform nucleus, is missing from the monotreme forebrain. we used nissl and myelin staining in conjunction with enzyme histochemistry for acetylcholinesterase and immunohistochemistry for parvalbumin, calbindin, calretinin and tyrosine hydroxylase to examine the brains of two monotremes, the short-beaked echidna (tachyglossus aculeatus) and the platypus (ornithorhynchus anatinus). we found that alth ... | 2004 | 15319553 |
| plasma glucocorticoid concentrations in free-ranging platypuses (ornithorhynchus anatinus): response to capture and patterns in relation to reproduction. | energy demands in the platypus are likely to increase in the breeding season, which occurs from winter to early spring. glucocorticoids, which play a major role in energy mobilisation, were measured in consecutive blood samples from free-ranging adults at approximately monthly intervals throughout the year. glucose and free fatty acids were also measured in some samples. plasma concentrations of glucocorticoids rose significantly during the first 30 min after capture, accompanied by a rise in fr ... | 2003 | 14667852 |
| tactile neural mechanisms in monotremes. | monotremes, perhaps more than any other order of mammals, display an enormous behavioural reliance upon the tactile senses. in the platypus, ornithorhynchus anatinus, this is manifest most strikingly in the special importance of the bill as a peripheral sensory organ, an importance confirmed by electrophysiological mapping that reveals a vast area of the cerebral cortex allocated to the processing of tactile inputs from the bill. although behavioural evidence in the echidna, tachyglossus aculeat ... | 2003 | 14667851 |
| the monotreme genome: a patchwork of reptile, mammal and unique features? | the first specimen of platypus (ornithorhynchus anatinus) that reached britain in the late 18th century was regarded a scientific hoax. over decades the anatomical characteristics of these unique mammals, such as egg laying and the existence of mammary glands, were hotly debated before they were accepted. within the last 40 years, more and more details of monotreme physiology, histology, reproduction and genetics have been revealed. some show similarities with birds or reptiles, some with theria ... | 2003 | 14667850 |
| immunoglobulin genetics of ornithorhynchus anatinus (platypus) and tachyglossus aculeatus (short-beaked echidna). | in this paper, we review data on the monotreme immune system focusing on the characterisation of lymphoid tissue and of antibody responses, as well the recent cloning of immunoglobulin genes. it is now known that monotremes utilise immunoglobulin isotypes that are structurally identical to those found in marsupials and eutherians, but which differ to those found in birds and reptiles. monotremes utilise igm, igg, iga and ige. they do not use igy. their igg and iga constant regions contain three ... | 2003 | 14667846 |
| diving behaviour, dive cycles and aerobic dive limit in the platypus ornithorhynchus anatinus. | we investigated the diving behaviour, the time allocation of the dive cycle and the behavioural aerobic dive limit (adl) of platypuses (ornithorhynchus anatinus) living at a sub-alpine tasmanian lake. individual platypuses were equipped with combined data logger-transmitter packages measuring dive depth. mean dive duration was 31.3 s with 72% of all dives lasting between 18 and 40 s. mean surface duration was 10.1 s. mean dive depth was 1.28 m with a maximum of 8.77 m. platypuses performed up to ... | 2003 | 14667845 |
| lactate dehydrogenase a as a highly abundant eye lens protein in platypus (ornithorhynchus anatinus): upsilon (upsilon)-crystallin. | vertebrate eye lenses mostly contain two abundant types of proteins, the alpha-crystallins and the beta/gamma-crystallins. in addition, certain housekeeping enzymes are highly expressed as crystallins in various taxa. we now observed an unusual approximately 41-kd protein that makes up 16% to 18% of the total protein in the platypus eye lens. its cdna sequence was determined, which identified the protein as muscle-type lactate dehydrogenase a (ldh-a). it is the first observation of ldh-a as a cr ... | 2003 | 12716980 |
| characterization of beta(2)-microglobulin coding sequence from three non-placental mammals: the duckbill platypus, the short-beaked echidna, and the grey short-tailed opossum. | to further characterize genes of immunological importance from non-placental mammals, cdnas encoding beta(2)-microglobulin (beta(2)m) were isolated from two prototherians, the platypus and an echidna, and one metatherian, a grey short-tailed opossum. in addition, a second allele of beta(2)m was identified in another metatherian species, the brushtail possum. analysis of the deduced translations revealed conservation of key residues in these molecules over a long evolutionary history. the types o ... | 2003 | 12590975 |
| the distribution and morphological characteristics of catecholaminergic cells in the brain of monotremes as revealed by tyrosine hydroxylase immunohistochemistry. | the present study describes the distribution and cellular morphology of catecholaminergic neurons in the cns of two species of monotreme, the platypus (ornithorhynchus anatinus) and the short-beaked echidna (tachyglossus aculeatus). tyrosine hydroxylase immunohistochemistry was used to visualize these neurons. the standard a1-a17, c1-c3 nomenclature was used for expediency, but the neuroanatomical names of the various nuclei have also been given. monotremes exhibit catecholaminergic neurons in t ... | 2002 | 12476055 |
| the distribution and morphological characteristics of cholinergic cells in the brain of monotremes as revealed by chat immunohistochemistry. | the present study employs choline acetyltransferase (chat) immunohistochemistry to identify the cholinergic neuronal population in the central nervous system of the monotremes. two of the three extant species of monotreme were studied: the platypus (ornithorhynchus anatinus) and the short-beaked echidna (tachyglossus aculeatus). the distribution of cholinergic cells in the brain of these two species was virtually identical. distinct groups of cholinergic cells were observed in the striatum, basa ... | 2002 | 12476054 |
| accumulation of persistent organic pollutants in tasmanian platypus (ornithorhynchus anatinus). | tailfat samples were collected from 56 platypuses, 38 male and 18 female in tasmania. no statistically significant, nor apparent, differences between the sexes were found for tailfat lipid levels and ddt and its metabolites. lindane and pcb concentrations in tailfat lipid. apparently--but not statistically--significantly different levels of ddt and its metabolites. lindane and pcb concentrations were found in animals from different geographic regions of the state. higher concentrations of ddt an ... | 2002 | 12395834 |
| d-amino acid residue in the c-type natriuretic peptide from the venom of the mammal, ornithorhynchus anatinus, the australian platypus. | the c-type natriuretic peptide from the platypus venom (ovcnp) exists in two forms, ovcnpa and ovcnpb, whose amino acid sequences are identical. through the use of nuclear magnetic resonance, mass spectrometry, and peptidase digestion studies, we discovered that ovcnpb incorporates a d-amino acid at position 2 in the primary structure. peptides containing a d-amino acid have been found in lower forms of organism, but this report is the first for a d-amino acid in a biologically active peptide fr ... | 2002 | 12135762 |
| variations in residues of persistent organic pollutants in a platypus (ornythorhynchus anatinus) at consecutive samplings. | | 2002 | 12074313 |
| energetics of terrestrial locomotion of the platypus ornithorhynchus anatinus. | the platypus ornithorhynchus anatinus shaw displays specializations in its limb structure for swimming that could negatively affect its terrestrial locomotion. platypuses walked on a treadmill at speeds of 0.19-1.08 m x s(-1). video recordings were used for gait analysis, and the metabolic rate of terrestrial locomotion was studied by measuring oxygen consumption. platypuses used walking gaits (duty factor >0.50) with a sprawled stance. to limit any potential interference from the extensive webb ... | 2001 | 11171362 |
| spermiogenesis and spermiation in a monotreme mammal, the platypus, ornithorhynchus anatinus. | spermatogenesis in the platypus (ornithorhynchus anatinus) is of considerable biological interest as the structure of its gametes more closely resemble that of reptiles and birds than marsupial or eutherian mammals. the ultrastructure of 16 steps of spermatid development is described and provides a basis for determining the kinetics of spermatogenesis. steps 1-3 correspond to the golgi phase of spermatid development, steps 4-8 correspond to the cap phase, steps 9-12 are the acrosomal phase, and ... | 2000 | 10739018 |
| maxillary deformity in a wild platypus (ornithorhynchus anatinus). | | 1999 | 10685173 |
| a component of platypus (ornithorhynchus anatinus) venom forms slow-kinetic cation channels. | the lipid bilayer technique is used to examine the biophysical properties of anion and cation channels frequently formed by platypus (ornithorhynchus anatinus) venom (oav). the oav-formed anion channel in 250/50 mm kcl cis/trans has a maximum conductance of 857 +/- 23 ps (n = 5) in 250/50 mm kcl cis/trans. the current-voltage relationship of this channel shows strong inward rectification. the channel activity undergoes time-dependent inactivation that can be removed by depolarizing voltage steps ... | 1999 | 10552012 |
| histological and immunohistological investigation of lymphoid tissue in the platypus (ornithorhynchus anatinus). | the gross and histological appearance and the distribution of t and b lymphocytes and plasma cells are described for lymphoid tissues obtained from 15 platypuses. the spleen was bilobed and surrounded by a thick capsule of collagen, elastic fibres and little smooth muscle. white pulp was prominent and included germinal centres and periarterial lymphoid sheaths. red pulp contained haematopoietic tissue. a thin lobulated thymus was located within the mediastinum overlying the heart. the cortex of ... | 1999 | 10529053 |
| the development of the electroreceptors of the platypus (ornithorhynchus anatinus). | a series of developmental stages of the platypus were examined to obtain an anatomical description of the development of the periphery of the electroreceptive system. putative electroreceptors, composed of modified mucous glands, were observed to appear at 10 days post hatching (p.h.). the typical striped arrangement of peripheral electroreceptors in the platypus was seen at 12 days p.h. the arrangement of the stripes was modified during development with a range of additions and divisions of str ... | 1998 | 9720113 |
| fatty acids of the milk and food of the platypus (ornithorhynchus anatinus). | platypus milk fat contains 98.5% triglyceride. polyunsaturates (c18∶2-c22∶5) account for 29% of the triglyceride fatty acids in the milk fat and 32% of the total fatty acids in the lipid of the food of the platypus. linoleate and arachidonate are the major ω6 polyunsaturates of both food and milk lipids. however, while the ω3 polyunsaturates linolenate and eicosapentaenoate are present in both food and milk, docosapentaenoate is present in meaningful amounts in milk only. it is suggested that wi ... | 1988 | 27520014 |
| splenic hemopoiesis of the platypus (ornithorhynchus anatinus): evidence of primary hemopoiesis in the spleen of a primitive mammal. | the generation of blood cells has been observed in the spleen and in the bone marrow of the platypus. hemopoiesis was found to be far more active in the spleen than in the bone marrow judging by the number of proliferating hemopoietic elements within a unit area of tissue from each organ. granulocytes, erythroblasts, and megakaryocytes, with the related immature forms for each cell line, were noted in the spleen. in contrast, there were very few examples of immature forms of these cell lines and ... | 1988 | 3389307 |
| intestinal mucosa and intra-abdominal lymphoid tissues of the platypus, ornithorhynchus anatinus. | the morphological features of the intestinal mucosa and intra-abdominal lymphoid tissues of the platypus were examined. the mucosal surface of the intestine was characterized by the formation of large folds instead of the finger-like villi found in placental mammals. the lamina propria of the mucosal fold was well developed and contained numerous lymphocytes, expressing the lymphoid nature which is characteristic of the lamina propria of mammalian intestines. although numerous well-developed pey ... | 1991 | 2062481 |
| some monotreme milk "whey" and blood proteins. | 1. electrophoretic studies are made of mature phase milk "whey" proteins and blood serum proteins of echidna (tachyglossus aculeatus) and platypus (ornithorhynchus anatinus). the echidna milk bands are designated a-m, those of platypus a-g. some of the proteins are isolated and characterized. 2. echidna band a protein has some similarity to high cystine "whey" proteins. band e protein (apparent mr 21,000) may be a beta-lactoglobulin-like protein. band m is lysozyme. band c is serum albumin. band ... | 1991 | 1959333 |
| the anatomy and fine structure of the echidna tachyglossus aculeatus snout with respect to its different trigeminal sensory receptors including the electroreceptors. | the gross anatomy and nerve supply of the bill of echidna (tachyglossus aculeatus) is described in relation to its function as an outstanding sensory organ. the sensory innervation of the skin of the echidna snout was investigated by means of frontal serial sections, after decalcification of the specimens. a comprehensive light and electron microscopic description of the location and fine structure of cutaneous sensory receptors of the trigeminal system was made by this means. the encapsulated a ... | 1991 | 1952110 |
| iron(iii) binding proteins of echidna (tachyglossus aculeatus) and platypus (ornithorhynchus anatinus). | iron (iii) binding proteins are isolated from echidna (tachyglossus aculeatus multiaculeatus) and platypus (ornithorhynchus anatinus) milk and blood. on the basis of several criteria it is shown that the milk proteins are not lactoferrins, but are transferrins similar to the corresponding transferrins from the blood. the heterogeneity of the proteins, particularly the echidna milk transferrin, is, at least in part, due to different levels of sialic acid. their n-terminal sequences (30 residues) ... | 1990 | 2090097 |
| distribution of substance p in the enteric plexuses of the small intestine of the platypus, ornithorhynchus anatinus. | a study was made of substance p-like-immunoreactive nerves within the small intestine of platypus, an australian prototherian mammal. both immunoreactive nerve cell bodies and fibers were present. no immunoreactive fibers were found in mesenteric nerves or on intramural blood vessels, suggesting that extrinsic sensory neurons containing substance p do not innervate platypus ileum. this was further supported by the result of in vitro experiments. although applied substance p (10(-9) m-3 x 10(-8) ... | 1989 | 2468417 |
| calcium dependence of c-type natriuretic peptide-formed fast k(+) channel. | the lipid bilayer technique was used to characterize the ca(2+) dependence of a fast k(+) channel formed by a synthetic 17-amino acid segment [oacnp-39-(1-17)] of a 39-amino acid c-type natriuretic peptide (oacnp-39) found in platypus (ornithorhynchus anatinus) venom (oav). the oacnp-39-(1-17)-formed k(+) channel was reversibly dependent on 1,2-bis(2-aminophenoxy)ethane-n,n,n',n'-tetraacetic acid-buffered cis (cytoplasmic) ca(2+) concentration ([ca(2+)](cis)). the channel was fully active when [ ... | 1999 | 10409107 |
| characterization of a c-type natriuretic peptide (cnp-39)-formed cation-selective channel from platypus (ornithorhynchus anatinus) venom. | 1. the lipid bilayer technique is used to characterize the biophysical and pharmacological properties of a novel, fast, cation-selective channel formed by incorporating platypus (ornithorhynchus anatinus) venom (oav) into lipid membranes. 2. a synthetic c-type natriuretic peptide oacnp-39, which is identical to that present in platypus venom, mimics the conductance, kinetics, selectivity and pharmacological properties of the oav-formed fast cation-selective channel. the n-terminal fragment conta ... | 1999 | 10381585 |
| sleep in the platypus. | we have conducted the first study of sleep in the platypus ornithorhynchus anatinus. periods of quiet sleep, characterized by raised arousal thresholds, elevated electroencephalogram amplitude and motor and autonomic quiescence, occupied 6-8 h/day. the platypus also had rapid eye movement sleep as defined by atonia with rapid eye movements, twitching and the electrocardiogram pattern of rapid eye movement. however, this state occurred while the electroencephalogram was moderate or high in voltag ... | 1999 | 10336087 |
| distribution and putative function of autonomic nerve fibres in the bill skin of the platypus (ornithorhynchus anatinus). | the electroreceptors located in the bill skin of the platypus are modified secretory glands. the electroreceptive nerve terminals form bare endings in close proximity to the duct of these glands. in this study, we describe the autonomic innervation of the glands and a separate specialized autonomic innervation of the epidermal portion of the glandular duct. a range of immunohistochemical labels showed that the gland cells of the electroreceptors have a non-noradrenergic (putative parasympathetic ... | 1998 | 9720112 |
| the development of the external features of the platypus (ornithorhynchus anatinus). | the present study describes the post-hatching development of the external features of the platypus. specimens range in age from the day of hatching through to 6 months old, and provide the first comprehensive view of the developmental sequence of these features. various features, those specific to the platypus, those specific to monotremes and those shared with marsupials and eutherians, are described. features specific to the platypus, including the bill and webbing of the forefeet, are seen to ... | 1998 | 9720109 |
| new information about the skull and dentary of the miocene platypus obdurodon dicksoni, and a discussion of ornithorhynchid relationships. | a reconstruction of the skull, dentary and dentition of the middle miocene ornithorhynchid obdurodon dicksoni has been made possible by acquisition of nearly complete cranial and dental material. access to new anatomical work on the living platypus, ornithorhynchus anatinus, and the present comparative study of the cranial foramina of ob. dicksoni and or. anatinus have provided new insights into the evolution of the ornithorhynchid skull. the hypertrophied bill in ob. dicksoni is seen here as po ... | 1998 | 9720105 |
| occurrence of polychlorinated biphenyls and organochlorine pesticides in platypuses (ornithorhynchus anatinus) in tasmania. | | 1998 | 9578785 |
| energetics of swimming by the platypus ornithorhynchus anatinus: metabolic effort associated with rowing. | the metabolism of swimming in the platypus ornithorhynchus anatinus shaw was studied by measurement of oxygen consumption in a recirculating water flume. platypuses swam against a constant water current of 0.45-1.0 ms-1. animals used a rowing stroke and alternated bouts of surface and submerged swimming. metabolic rate remained constant over the range of swimming speeds tested. the cost of transport decreased with increasing velocity to a minimum of 0.51 at 1.0 ms-1. metabolic rate and cost of t ... | 1997 | 9359371 |
| on the morphology of the brachial plexus of the platypus (ornithorhynchus anatinus) and the echidna (tachyglossus aculeatus). | four forelimbs of 3 platypuses and 3 forelimbs of 2 echidnas were examined to study the precise form of the brachial plexus and to clarify the structural characteristics of the brachial plexus in phylogeny. the spinal components contributing to the plexus (c4-t2) and the formation patterns of the 3 trunks of the plexus were the same as those generally observed in mammals. in the cranial half of the brachial plexus from c4, 5 and 6 in monotremes, division into the ventral bundle (lateral cord) an ... | 1997 | 9147230 |
| ultrastructure, number, distribution and innervation of electroreceptors and mechanoreceptors in the bill skin of the platypus, ornithorhynchus anatinus. | the platypus is presently the only mammal demonstrated to use electroreception to obtain food. the electroreceptive system of the platypus is far more complex than that of its close relative the echidna. this paper presents an anatomical study of the basis of electroreception in the platypus. the innervation of the bill by the trigeminal nerve is described, as are three sensory structures, associated with food gathering, within the bill skin. there are 40,000 mucous gland electroreceptors found ... | 1996 | 8828862 |
| hematological changes in the platypus (ornithorhynchus anatinus) following capture. | blood samples were collected from the bill sinus of nine free-living platypuses (ornithorhynehus anatinus) within 12 min of capture of each and again after 1 to 12 hr, new south wales, australia, 1981 to 1988. in seven animals which were not anesthetized, there was a significant (p < 0.01) fall in lymphocyte count between the two samples. the reduction ranged from 10 to 58% of the initial lymphocyte count and caused a significant reduction in the total white cell count (p < 0.05). both the neutr ... | 1995 | 8592361 |
| nerve terminals of mucous gland electroreceptors in the platypus (ornithorhynchus anatinus). | platypus mucous gland electroreceptors differ from electroreceptors described for fish in that they lack an associated specialized sensory cell. thus a bare nerve terminal is used to detect electrical stimuli, and also to generate local and action potentials. previous studies have identified these terminals (an average of 16 per mucous gland), but had not shown whether the terminals have direct contact with the duct of the mucous gland. this poses the problem of how the electrical stimulus reach ... | 1995 | 7761482 |
| cloning and characterization of the platypus mitochondrial genome. | the vertebrate mitochondrial genome is highly conserved in size and gene content. among the chordates there appears to be one basic gene arrangement, but rearrangements in the mitochondrial gene order of the avian lineages have indicated that the mitochondrial genome may be more variable than once thought. different gene orders in marsupials and eutherian mammals leave the ancestral mammalian order in some doubt. we have investigated the mitochondrial gene order in the platypus (ornithorhynchus ... | 1994 | 7932783 |
| evolution of the monotremes. the sequences of the protamine p1 genes of platypus and echidna. | the protamine p1 genes from two monotremes, platypus (ornithorhynchus anatinus) and echidna (tachyglossus aculeatus) were isolated after polymerase-chain-reaction amplification then cloned and sequenced. the two protamine p1 genes are of 290 bp and 311 bp for platypus and echidna, respectively, and are clearly orthologous to the published sequences of protamine p1 genes of eutherian mammals and birds. both genes contain an intron, like the mammals and marsupials and unlike the bird p1 genes that ... | 1993 | 8269934 |
| innervation of the monotreme gastrointestinal tract: a study of peptide and catecholamine distribution. | the distribution of neurons and endocrine cells containing various peptides or catecholamines was examined in the digestive tracts of the echidna (tachyglossus aculeatus) and the platypus (ornithorhynchus anatinus). comparisons were made with published studies in other species in order to obtain a broader view of the phylogenetic distribution and possible functions of gut peptides and catecholamines. further comparisons between the echidna and platypus were made in light of their different dieta ... | 1993 | 8103529 |
| parathyroids and ultimobranchial bodies in monotremes. | only scant information is available in the scientific literature on the parathyroids and ultimobranchial bodies in the primitive mammals, the echidna (tachyglossus aculeatus) and platypus (ornithorhynchus anatinus). the major aim of this paper is to describe the morphology of the monotreme parathyroid gland and to compare it with parathyroids in mammals and reptiles. the gross anatomy and light microscopic structure of the ultimobranchial body, thymus, and thyroid are also given. animals were di ... | 1999 | 9972812 |
| morphology of pyramidal neurones in cytochrome oxidase modules of the s-i bill representation of the platypus. | the primary somatosensory cortex of the platypus (ornithorhynchus anatinus) is characterized by a distinct array of functionally specific cytochrome oxidase (co) modules, forming alternate co-rich and co-poor bands. in the current study, we undertook to establish whether the cellular morphology of layer v pyramidal neurones reflects this modular organization. to this end, we injected neurones with lucifer yellow in 250 microm thick, flat-mounted cortical slices and processed the tissue to reveal ... | 1999 | 9933785 |
| sensory receptors in monotremes. | this is a summary of the current knowledge of sensory receptors in skin of the bill of the platypus, ornithorhynchus anatinus, and the snout of the echidna, tachyglossus aculeatus. brief mention is also made of the third living member of the monotremes, the long-nosed echidna, zaglossus bruijnii. the monotremes are the only group of mammals known to have evolved electroreception. the structures in the skin responsible for the electric sense have been identified as sensory mucous glands with an e ... | 1998 | 9720114 |
| the central projection of electrosensory information in the platypus. | 1. this is the first detailed description of the projection to the cerebral cortex of afferent information coming from electroreceptors in the bill of the platypus, ornithorhynchus anatinus. 2. in animals anaesthetized with chloralose, with the bill immersed in tap water, applying a potential difference between plate electrodes on either side of the bill produced large amplitude potentials from the surface of a postero-lateral region of cerebral cortex. response threshold was 300 microv cm-1, so ... | 1992 | 1593454 |
| the lamina cribrosa of ornithorhynchus (monotremata, mammalia). | a vestigial and transitory lamina cribrosa was found in nestling platypus (ornithorhynchus anatinus). the heads of two nest-young (180 and 333 mm length), one subadult and one adult ornithorhynchus were serially sectioned and studied with special reference to the development of the nasal region. in nest-young ornithorhynchus an irregularly shaped bar of cartilage develops at the foramen olfactorium advehens. in the subadult it is largely resorbed, and in the osseous skull of the adult it is comp ... | 1988 | 3223609 |
| scanning microscopy of platypus teeth. | anorganic unerupted developing teeth and air-dried erupted teeth of the platypus (ornithorhynchus anatinus) were examined in a scanning electron microscope and in a tandem scanning reflected light microscope. typically mammalian developing fronts of enamel and dentine were identified in the anorganic unerupted specimens. the developing teeth were particularly small and fragile and the enamel elusive and difficult to examine in the normal way for morphological detail. prepared fractured surfaces ... | 1986 | 3706773 |
| the neurohypophysial hormones of the egg-laying mammals: identification of arginine vasopressin in the platypus (ornithorhynchus anatinus). | two neurohypophysial peptides have been purified from acetone desiccated posterior pituitary glands of the platypus (ornithorhynchus anatinus) by molecular sieving and high-pressure liquid chromatography. a single pressor peptide, having an amino acid composition and a chromatographic retention time identical to those of arginine vasopressin, has been identified. a single oxytocic peptide has been isolated that ressembles oxytocin by its chromatographic retention time, but lack of material has p ... | 1985 | 3977923 |
| two monotreme cell lines, derived from female platypuses (ornithorhynchus anatinus; monotremata, mammalia). | two diploid platypus cell lines, designated oa-1f and oa-2f, have been derived from the toe webs of two females. the development and growth characteristics of the lines are described and g-banded karyotypes presented (the first reported for the platypus). the availability of these lines will greatly facilitate chromosome and gene mapping studies of the platypus and permit the extension of comparative studies of mammalian chromosome and genome evolution to the monotremes. | 1984 | 6715011 |
| a comparison of the positional distribution of fatty acids in milk triglycerides of the extant monotremes platypus (ornithorhynchus anatinus) and echidna (tachyglossus aculeatus). | milk triglycerides from the platypus were subjected to fatty acid and stereospecific analysis to determine the positional distribution of fatty acids in the triglycerides. of the major fatty acids, 12∶0 was preferentially esterified at thesn-3 position, 14∶0 and 16∶0 were selectively associated with thesn-2 position, and 18∶0 was located predominantly at thesn-1 position. the unsaturated fatty acids, 14∶1, 16∶1, 18∶1, 18∶2 and 18∶3, were preferentially esterified at thesn-3 position. the fatty a ... | 1983 | 27519991 |
| carbohydrates of the milk of the platypus. | twelve samples of milk of the platypus, ornithorhynchus anatinus, had a mean content of 3 x 3% hexose. of this, almost half was l-fucose. of the total monosaccharides present in acid hydrolysates of the water-soluble carbohydrates, l-fucose constituted 33%, d-galactose 29%, glucosamine 20%, d-glucose 11% and sialic acid 7%. free lactose was found in only trace amounts. in all samples, the major oligosaccharide was difucosyllactose, which represented 39-52% of the total hexose. five higher neutra ... | 1983 | 6626045 |