| gonadotropin-releasing hormone (gnrh) in bony fish that are phylogenetically ancient: reedfish (calamoichthys calabaricus), sturgeon (acipenser transmontanus), and alligator gar (lepisosteus spatula). | three species of fish that are phylogenetically older than other members of the bony fish lineage were selected to determine if gonadotropin-releasing hormone (gnrh) is present in their brains. brain extracts were prepared from each species and found to contain immunoreactive (ir) gnrh. to further characterize the molecular forms of gnrh in each species, the extracts were injected into a high pressure liquid chromatograph (hplc). the elution time of each gnrh-like form was compared to those of t ... | 1991 | 1778410 |
| isolation and structures of alligator gar (lepisosteus spatula) insulin and pancreatic polypeptide. | insulin and a 36-residue peptide with homology to pancreatic polypeptide (pp) were isolated from the endocrine pancreas of the alligator gar (lepisosteus spatula), a ganoid fish, by gel filtration and hplc. heterologous radioimmunoassays were used to detect insulin-like and pp-like immunoreactivities during purification of the two peptides. the sequence of the 36-amino acid peptide containing a c-terminal tyrosinamide was identical at 31 of 36 positions to porcine neuropeptide y (npy). the amino ... | 1987 | 3311873 |
| [comparison of the genome of the alligator gar with the genomes of several other fish]. | hybridization of alligator gar (lepisosteus osseus, lepisosteiformes, ganoidomorpha) [125i]- or [3h]dna fractions with dnas of more or less phylogenetically related fishes was studied. almost all of the repeated and unique sequences of alligator gar dna and dna of the spotted gar (from the same genus) are highly homologous (1-2% of nucleotide substitutions). the degrees of homology between repeated and unique sequences of alligator gar dna and dnas of the representatives of acipenseriformes (the ... | 2006 | 6855763 |
| [formation of the genome of the alligator gar lepisosteus osseus (ganoidomorpha) genome]. | genome structure of the alligator gar was studied by means of a comparison of reassociation kinetics of short and long dna fragments, an estimation of hyperchromicity of reassociated repetitive dna as a function of fragments length, and length estimation of s1-resistant duplexes by gel filtration. it was shown that most of the repeated sequences in the alligator gar dna are no less than 2000 b.p. long and weakly divergent. little or no interspersion of unique and short repeated sequences were ob ... | 2006 | 6855762 |
| the cardiotoxic effects of alligator gar (lepisosteus spatula) roe on the isolated turtle heart. | | 1980 | 7210035 |
| experimental verification of the metacercarial stage of rhipidocotyle lepisostei (trematoda: bucephalidae) with notes on the natural occurrence of its adult stage in gars in texas and virginia. | bucephalid metacercariae found encysted in the caudal fin rays of striped mullet (mugil cephalus) were fed to bucephalid-free spotted gars (lepisosteus oculatus) in the laboratory. gravid specimens of rhipidocotyle lepisostei were recovered from the intestinal tracts of 2 of 3 gars from 7 to 28 days later. further attempts to complete the entire life cycle were unsuccessful. natural infections of adult r. lepisostei were found in the type host, the alligator gar lepisosteus spatula, from galvest ... | 1990 | 2319436 |
| serum fluoride level and fluoride content of enameloid. | we investigated diverse groups of fish species to determine whether the fluorine (f) contents of the dental hard tissues were related to baseline serum f levels. serum samples, enameloid, dentin, ganoid/enamel, and bone were analyzed for f by either electron microprobe or wet chemistry. species were categorized into two groups based on the f content of the enameloid. one group contained greater than 2.6 wt% f in enameloid, whereas the other group had less than 0.45 wt% f in enameloid. the dentin ... | 1991 | 1918576 |
| comparative and developmental functional morphology of the jaws of living and fossil gars (actinopterygii: lepisosteidae). | the feeding mechanism of gars (ginglymodi : lepisosteidae) is characterized by cranial elevation and lower jaw rotation but minimal cranial kinesis. gar jaws have numerous, sharply pointed, elongate teeth for capture of evasive prey. their mandibles range from relatively short to extremely long depending on the species. jaw length and lever dimensions were hypothesized to affect the biomechanics of force and motion during feeding, according to simple mechanical models of muscles exerting force t ... | 2006 | 15593308 |
| cloning of the growth hormone cdna of alligator gar atractosteus spatula and its expression through larval development. | the alligator gar (atractosteus spatula) is the largest freshwater fish inhabiting rivers draining into the gulf of mexico. this primitive fish shows a fast growth rate since its early larval stages. this is attributed to the action of growth hormone (gh), an anterior pituitary gland hormone responsible for linear growth in vertebrates that can also be expressed in extrapituitary adult tissues and in fish embryos. the present research was aimed at obtaining the gh coding sequence of the alligato ... | 2005 | 15936701 |
| barrier cells in gills of the alligator gar. | studies of barrier cells in fishes are few and have been restricted primarily to salmonids. moreover, these studies revealed the presence of barrier cells only in hematopoietic and lymphoid organs. the alligator gar, lepisosteus spatula, possesses similar tissues within the gills which are readily accessible; therefore, they were the organs of choice. an electron microscopical analysis of the gills was undertaken to determine if barrier cells exist and if they possess an ultrastructural design c ... | 1999 | 18627869 |
| isolation and characterization of microsatellite loci for alligator gar (atractosteus spatula) and their variability in two other species (lepisosteus oculatus and l. osseus) of lepisosteidae. | we report on the isolation of 17 polymorphic microsatellite loci from alligator gar (atractosteus spatula), a large-bodied species that has experienced population declines across much of its range. these loci possessed 2-19 alleles and observed heterozygosities of 0-0.974. all loci conformed to hardy-weinberg equilibrium expectations, and none exhibited linkage disequilibrium. nine and eight of these loci were found to be polymorphic in the related species lepisosteus oculatus and l. osseus, res ... | 2009 | 21564806 |
| mechanical properties and structure of the biological multilayered material system, atractosteus spatula scales. | during recent decades, research on biological systems such as abalone shell and fish armor has revealed that these biological systems employ carefully arranged hierarchical multilayered structures to achieve properties of high strength, high ductility and light weight. knowledge of such structures may enable pathways to design bio-inspired materials for various applications. this study was conducted to investigate the spatial distribution of structure, chemical composition and mechanical propert ... | 2013 | 23149253 |
| structure and fracture resistance of alligator gar (atractosteus spatula) armored fish scales. | the alligator gar is a large fish with flexible armor consisting of ganoid scales. these scales contain a thin layer of ganoine (microhardness ~2.5 gpa) and a bony body (microhardness ~400 mpa), with jagged edges that provide effective protection against predators. we describe here the structure of both ganoine and bony foundation and characterize the mechanical properties and fracture mechanisms. the bony foundation is characterized by two components: a mineralized matrix and parallel arrays of ... | 2013 | 23274521 |
| effects of salinity on growth and ion regulation of juvenile alligator gar atractosteus spatula. | the alligator gar (atractosteus spatula) is a primitive euryhaline fish, found primarily in estuaries and freshwater drainages associated with the northern gulf of mexico. the extent of its hypo-osmotic regulatory abilities is not well understood. in order to determine how salinity affects growth rates and ionic and osmoregulation, juvenile alligator gar (330 days after hatch; 185 g) were exposed to 4 different salinities (0, 8, 16, and 24 ppt) for a 30-day period. specific growth rate, plasma o ... | 2014 | 24368134 |
| the effects of oil exposure on peripheral blood leukocytes and splenic melano-macrophage centers of gulf of mexico fishes. | in august and november 2010 we collected and examined peripheral blood and tissues from three species of gulf of mexico fish. findings were compared to non-exposed control fish. the leukocyte counts of exposed alligator gar were not significantly different from controls, while exposed gulf killifish and sea trout had significantly decreased lymphocyte counts. liver ethoxyresorufin-o-deethylase (erod) values from sea trout were significantly greater than control sea trout erod values, suggesting ... | 2014 | 24405733 |
| characterization of multi-layered fish scales (atractosteus spatula) using nanoindentation, x-ray ct, ftir, and sem. | the hierarchical architecture of protective biological materials such as mineralized fish scales, gastropod shells, ram's horn, antlers, and turtle shells provides unique design principles with potentials for guiding the design of protective materials and systems in the future. understanding the structure-property relationships for these material systems at the microscale and nanoscale where failure initiates is essential. currently, experimental techniques such as nanoindentation, x-ray ct, and ... | 2014 | 25046233 |
| physiological response of alligator gar juveniles (atractosteus spatula) exposed to sub-lethal doses of pollutants. | alligator gar populations have declined because of overfishing, habitat loss and pollution. over time, the exposure to different pollutants have affected these fishes as a consequence of their high trophic level, bottom-dwelling habits and long life span. in order to evaluate the physiological effects of pollutants on alligator gar, juveniles (6, 12 and 24 months) were exposed to sub-lethal doses of diazinon, β-naphthoflavone (bnf) and 17 β-estradiol (e2) by intraperitoneal injection. after 2 da ... | 2015 | 25948055 |
| tissue pah, blood cell and tissue changes following exposure to water accommodated fractions of crude oil in alligator gar, atractosteus spatula. | alligator gar atractosteus spatula acclimated to brackish water (9 ppt) were exposed to water accommodated fraction oil loadings (surrogate to macondo deepwater horizon, northern gulf of mexico) of 0.5 and 4.0 gm oil/l tank water for 48 h. the surrogate oil was approximately 98% alkanes and alkynes and 2% petroleum aromatic hydrocarbons. the 2% petroleum aromatic hydrocarbons were predominately naphthalene. after 48 h, naphthalene levels in fish liver exposed to 0.5 or 4 gm oil/l were 547.79 and ... | 2015 | 25956543 |
| microstructural and geometric influences in the protective scales of atractosteus spatula. | atractosteus spatula has been described as a living fossil (having existed for 100 myr), retaining morphological characteristics of early ancestors such as the ability to breathe air and survive above water for hours. its highly effective armour consists of ganoid scales. we analyse the protective function of the scales and identify key features which lead to their resistance to failure. microstructural features include: a twisted cross-plied mineral arrangement that inhibits crack propagation i ... | 2016 | 27974575 |
| a representative volume element based micromechanical analysis of a bi-layered ganoid fish scale. | the mississippi alligator gar (atractosteus spatula) possesses a flexible exoskeleton armor consisting of overlapping ganoid scales used for predatory protection. each scale is a two-phase biomineralized composite containing bio-modified hydroxyapatite (hard) minerals and collagen (soft) fibers. the protective layer consists of a stiff outer ganoine layer, a characteristic "sawtooth" pattern at the interface with the compliant bone inner layer. the garfish scale exhibits a decreasing elastic mod ... | 2017 | 28189933 |
| chloride inhibition of nitrite uptake for non-teleost actinopterygiian fishes. | fish that transport environmental chloride with a gill uptake mechanism (gill epithelial cl(-)/hco(3)(-)cotransport exchange system), also transport nitrite into plasma through the same mechanism. because of the relationship between nitrite uptake and the gill chloride uptake mechanism, nitrite uptake can provide insight regarding the method of chloride uptake for fish. this study was designed to determine if non-teleost fishes concentrate nitrite in their plasma, and to determine if chloride in ... | 2007 | 17344081 |
| the origin of the mammalian form of gnrh in primitive fishes. | the presence of neuroendocrine hormones in extant agnathan fishes suggests that a method of control involving these hormones was operating 500-600 million years ago in emerging vertebrates. data on a limited number of species show that several members of the gnrh family of peptides may have arisen in non-teleost fishes. lamprey (petromyzon marinus) gnrh has a unique composition and has not been detected in other vertebrates. it is not yet clear whether the chicken ii gnrh-like molecule arose in ... | 1989 | 24221758 |
| isolation of alligator gar (lepisosteus spatula) glucagon, oxyntomodulin, and glucagon-like peptide: amino acid sequences of oxyntomodulin and glucagon-like peptide. | oxyntomodulin, glucagon, and a glucagon-like peptide (glp) have been isolated from the endocrine pancreas of the alligator gar (lepisosteus spatula), a ganoid fish. the three peptides were isolated by gel filtration and hplc and were identified by size, composition, and glucagon-like immunoreactivity. the amino acid sequences of the oxyntomodulin and glp were determined. the oxyntomodulin contains 36 amino acid residues and its sequence is h s q g t f t n d y s k y l d t r r a q d f v q w l m s ... | 2012 | 3282974 |
| the evolution of root effect hemoglobins in the absence of intracellular ph protection of the red blood cell: insights from primitive fishes. | the root effect, a reduction in blood oxygen (o(2)) carrying capacity at low ph, is used by many fish species to maximize o(2) delivery to the eye and swimbladder. it is believed to have evolved in the basal actinopterygian lineage of fishes, species that lack the intracellular ph (ph(i)) protection mechanism of more derived species' red blood cells (i.e., adrenergically activated na(+)/h(+) exchangers; betanhe). these basal actinopterygians may consequently experience a reduction in blood o(2) ... | 2010 | 20213180 |
| the transition in hemoglobin proton-binding characteristics within the basal actinopterygian fishes. | carbon dioxide (co(2)) transport in the blood of fishes is aided by the proton-binding properties of hemoglobin (hb) through either a high-intrinsic buffer value and small oxylabile proton binding (haldane effect), or a low buffer value and large haldane effect. primitive species, such as elasmobranchs and sarcopterygians have been shown to rely on the former, while derived species, such as teleosts rely on the latter. both strategies are effective in the transport of co(2) in the blood. however ... | 2010 | 20044754 |
| macroderoides texanus n. sp. (digenea: macroderoididae) from alligator gar, atractosteus spatula in texas. | macroderoides texanus n. sp. is described based on 16 specimens collected from the intestine of the north american alligator gar, atractosteus spatula. of the five established species of macroderoides, the new species is morphologically most similar to macroderoides spiniferus and macroderoides trilobatus. m. texanus n. sp. differs from m. spiniferus by having the ovary situated immediately posterior to the cirrus sac rather than at mid-way between the cirrus sac and anterior testis, the ventral ... | 2008 | 18762983 |
| a new amino acid, 3-(2,5-ss-dicysteinyl-3,4-dihydroxyphenyl)alanine, from the tapetum lucidum of the gar (lepisosteidae) and its enzymic synthesis. | the tapetum lucidum of the alligator gar lepisosteus was shown by t.l.c. to contain a new phenolic amino acid, which is apparently a major constituent of the reflecting material. it was isolated in a yield of 0.5 mg/eye and its physical and chemical characteristics, especially reductive hydrolysis with hydriodic acid giving dopa (3,4-dihydroxyphenylalanine) and cysteine, suggested that it might to ss-dicysteinyldopa. tyrosinase oxidation of l-dopa in the presence of an excess of l-cysteine yield ... | 1977 | 403909 |
| natural flexible dermal armor. | fish, reptiles, and mammals can possess flexible dermal armor for protection. here we seek to find the means by which nature derives its protection by examining the scales from several fish (atractosteus spatula, arapaima gigas, polypterus senegalus, morone saxatilis, cyprinius carpio), and osteoderms from armadillos, alligators, and leatherback turtles. dermal armor has clearly been developed by convergent evolution in these different species. in general, it has a hierarchical structure with co ... | 2013 | 23161399 |
| finite element modeling of multilayered structures of fish scales. | the interlinked fish scales of atractosteus spatula (alligator gar) and polypterus senegalus (gray and albino bichir) are effective multilayered armor systems for protecting fish from threats such as aggressive conspecific interactions or predation. both types of fish scales have multi-layered structures with a harder and stiffer outer layer, and softer and more compliant inner layers. however, there are differences in relative layer thickness, property mismatch between layers, the property grad ... | 2014 | 25300062 |
| a comparative study of piscine defense: the scales of arapaima gigas, latimeria chalumnae and atractosteus spatula. | we compare the characteristics of the armored scales of three large fish, namely the arapaima gigas (arapaima), latimeria chalumnae (coelacanth), and atractosteus spatula (alligator gar), with specific focus on their unique structure-mechanical property relationships and their specialized ability to provide protection from predatory pressures, with the ultimate goal of providing bio-inspiration for manmade materials. the arapaima has flexible and overlapping cycloid scales which consist of a tou ... | 2016 | 27816416 |