| cellular ultrastructure of amphiuma distal nephron: effects of exposure to potassium. | the cellular ultrastructure of the renal distal nephron of the salamander, amphiuma means, was examined by electron-microscopic and stereological techniques before and after exposure to potassium in the ambient environment. the distal nephron of amphiuma is composed of three ultrastructurally distinct segments: early distal (or diluting segment), late distal, and collecting tubule. the early distal tubule structurally resembles the mammalian thick ascending limb of henle's loop. large renin-like ... | 1984 | 6476108 |
| the structure and ultrastructure of the renal tubule of the urodele amphibian, amphiuma means. | the renal corpuscle and segments of the renal tubule of the urodele amphibian amphiuma means have been described and studied by light and electron microscopy as a background for investigations on the effects of hormones, drugs, toxins and carcinogens on cell structure and function in long-term organ cultures of kidney explants. notable features of the a. means kidney include the number and variety of cytoplasmic inclusions in the cells of the proximal segment, the comparatively thick glomerular ... | 1978 | 217859 |
| effect of calcium ionophore br-x537a on renin synthesis and release in amphiuma means kidney culture. | | 1978 | 563980 |
| patterns of interdisk connections within the lamellar domains of retinal rod outer segment disks: observations relevant to the axial propagation of incisures. | in rod outer segments (ross) of the congo eel salamander (amphiuma), we have observed a system of cytoplasmic filaments that interconnect the lamellar domains of adjacent disks. in longitudinal sections, these filaments occur in pairs, spaced 18-20 nm apart. each filament is 9-11 nm in length, and perpendicular to the disk membrane. such filament pairs display extended axial alignment through the lamellar domains of successive disks, indicating the involvement of trans-membranous elements. in cr ... | 1987 | 3428404 |
| juxtaglomerular interstitial hypertonicity in amphiuma: tubular origin-tgf signal. | one of the mechanisms mediating renal vascular autoregulation in mammals senses tubular flow rate-dependent changes in luminal nacl concentrations and signals renal arterioles to change diameter. a similar mechanism operates in the salamander, amphiuma means. to trace the signal, we measured chloride activity in juxtaglomerular interstitial spaces in amphiuma during perfusion of the early distal tubule belonging to the same nephron. interstitial cl- activity exceeded systemic levels and increase ... | 1988 | 3348420 |
| metabolic oxygen regulation and conformity during submergence in the salamanderssiren lacertina, amphiuma means, andamphiuma tridactylum, and a comparison with other giant salamanders. | the giant salamanders of north america include 4 genera, all of which are aquatic. we have compared the efficacy of aquatic o2 uptake among them by measuring thevo2 while submerged and determining the responses to progressive hypoxia at 10-240 mmhg at 20° c. both species ofamphiuma were metabolic o2 conformers over the entire range ofpo2. about half ofsiren lacertina were conformers over this range, and half were regulators with an average critical o2 tension of 92 mmhg. there were no short-term ... | 1990 | 28312769 |
| sialic acid, electrophoretic mobility and transmembrane potentials of the amphiuma red cell. | red cells from the giant salamander amphiuma means are shown to contain sialic acid. the amount removed by the action of neuraminidase is equal to that released by acid hydrolysis, indicating that all of the sialic acid is present on the outer surface of the plasma membrane. these cells have a negative electrophoretic mobility and 100% enzymatic removal of sialic acid results in a 40% reduction in the mobility, suggesting that either a fraction of the sialic acid carboxyl groups are unavailable ... | 1975 | 241417 |
| three-dimensional membrane crystals in amphibian cone outer segments: 2. crystal type associated with the saddle point regions of cone disks. | in light-adapted, perfusion fixed retinas of the congo eel salamander, amphiuma, we have observed distinctive 3-d crystalline domains within the axial array of cone outer segment disks. these crystalline domains, each involving 2-12 disks, have been observed in the distal half of cone outer segment, and are associated with saddle point regions and immediately adjacent segments of the cone disk perimeter. in longitudinal sections, the crystals typically display an axially oriented array of cytopl ... | 1995 | 7556497 |
| analyzing the radiation of the melanocortins in amphibians: cloning of pomc cdnas from the pituitary of the urodele amphibians, amphiuma means and necturus maculosus. | proopiomelanocortin (pomc) cdnas were cloned and sequenced from brain extracts of two species of urodele amphibians: amphiuma means and necturus maculosus. although the two species of urodele amphibians belong to separate families, and do not share a direct common ancestor, the level of primary sequence identity for the open reading of the pomc cdnas was 90% at the amino acid level and 79% at the nucleotide level. it appears that the pomc gene in these urodele amphibians has been accumulating mu ... | 2005 | 16005111 |
| tracking the evolution of the proenkephalin gene in tetrapods. | in gnathostomes there is remarkable consistency in the organization of the proenkephalin gene. this opioid precursor encodes seven opioid (yggf) sequences: five pentapeptide sequences, a met-enkephalin-7 sequence and a met-enkephalin-8 sequence. yet, within vertebrate lineages there can be distinct sets of pentapeptide opioids (yggfm or yggfl). in the sarcopterygii, the sixth opioid position in lungfishes and anuran amphibian proenkephalin genes encodes a met-enkephalin (yggfm) sequence. however ... | 2007 | 17449037 |
| organ culture of amphiuma means liver: control of glycogen content. | | 1974 | 4156219 |
| osmoregulation in the aquatic urodeles amphiuma means (the congo eel) and siren lacertina (the mud eel). effects of vasotocin. | | 1973 | 4540625 |
| the long-term organ culture of tissues from adult amphiuma, the congo eel. | | 1972 | 4675179 |
| biomicroscopy of amphiuma means. | | 1969 | 5407394 |
| hepatic glycogen depletion in amphiuma during induced anoxia. | giant salamanders, amphiuma means, measuring 240 to 280 millimeters from snout to vent, tolerate induced anoxia for 6 hours. after 3 hours of anoxia, hepatic glycogen units are reduced in size and concentration; after 6 hours the glycogen units are almost completely depleted. greater development and changes in the density of the endoplasmic reticulum indicate that this structure participates in the mobilization of glycogen from the cell. | 1965 | 14263763 |
| peculiar feeding of amphiuma under conditions of enforced starvation. | two amphiuma means confined in aquaria with flowing artesian water for 3 years, with no known supply of food, increased in size. in the latter part of this period they were observed to shed a sheet of skin by a peculiar process and to devour it. this shed skin contained bacteria of the spirilla type, diatoms, and large amounts of unicellular algae, and possibly other organisms. similar behavior in unstarved specimens of cryptobranchus confined in an aquarium at the university of alabama has been ... | 1959 | 17812832 |
| on some habits of amphiuma means. | | 1892 | 17781596 |
| evolution of gigantism in amphiumid salamanders. | the amphiumidae contains three species of elongate, permanently aquatic salamanders with four diminutive limbs that append one, two, or three toes. two of the species, amphiuma means and a. tridactylum, are among the largest salamanders in the world, reaching lengths of more than one meter, whereas the third species (a. pholeter), extinct amphiumids, and closely related salamander families are relatively small. amphiuma means and a. tridactylum are widespread species and live in a wide range of ... | 2009 | 19461997 |
| dorsal laminectomy in a two-toed amphiuma (amphiuma means). | an adult male two-toed amphiuma (amphiuma means) was evaluated for kyphosis and a self-inflicted ulcerative dermal lesion at the site of a midbody spinal deformity. radiology revealed a proliferative bony lesion at the 39th vertebra. a dorsal laminectomy was performed to alleviate pressure on the spinal cord believed to be secondary to bone remodeling. resolution of the scoliosis occurred at the surgical site, and the ulcerative lesion of the body wall healed. three weeks postoperatively, the am ... | 2012 | 23272364 |
| the permeability of red blood cells to chloride, urea and water. | this study extends permeability (p) data on chloride, urea and water in red blood cells (rbc), and concludes that the urea transporter (ut-b) does not transport water. p of chick, duck, amphiuma means, dog and human rbc to (36)cl(-), (14)c-urea and (3)h2o was determined under self-exchange conditions. at 25°c and ph 7.2-7.5, pcl is 0.94 × 10(-4)-2.15 × 10(-4) cm s(-1) for all rbc species at [cl]=127-150 mmol l(-1). in chick and duck rbc, p(urea) is 0.84 × 10(-6) and 1.65 × 10(-6) cm s(-1), respe ... | 2013 | 23470663 |
| acidification in the distal tubule of the amphiuma kidney. | the acidification of the urine within the distal tubule of amphiuma means was studied with micropuncture techniques. antimony microelectrodes calibrated in vivo were used for measuring the intratubular ph and samples were taken for the determination of na+- and cl- -concentrations and for determining buffer lines within the hco-3-co2 buffer system. the tf/p na+ was used as a relative length determinator and a significant acidification along the length of the tubule was found. the ph in the tubul ... | 1983 | 6880793 |
| multitubular bodies in intestinal cells of amphiuma means/tridactylum (urodela): ultrastructural characterization. | the jejunal absorptive cells of the salamander amphiuma, when examined using transmission electron microscopy, were found to possess a unique type of intracellular vacuole containing membranous tubules. these vacuoles, tentatively named multitubular bodies, were located in the cytoplasm between the nucleus and the brush-border membrane, and were seen with greatest frequency in the summer and fall. the vacuoles containing multitubular bodies had an average diameter of 0.6 microns, and the membran ... | 1990 | 2166623 |
| a comparative study of the deacetylation of paracetamol by urodele and anuran amphibian organ cultures. | 1. p-aminophenol is the major metabolite produced by urodele amphibian tissues in vitro. the deacetylation enzyme system involved is located in the liver microsomal fraction of amphiuma means. 2. paracetamol was deacetylated to p-aminophenol by organ cultures of liver, kidney, pancreas and stomach epithelium from adult a. means, by liver, stomach epithelium, bladder and lung cultures from neotenic larval ambystoma tigrinum, and by adult triturus cristatus carnifex in vivo. 3. liver cultures from ... | 1981 | 7293210 |
| aerial and aquatic respiration in the congo eel amphiuma means means (garden). | | 2015 | 4826748 |
| gfr regulation and flow-dependent electrophysiology of early distal tubule in amphiuma. | tubuloglomerular feedback (tgf) in mammals and amphibians senses flow-dependent concentration changes in tubular fluid of the distal tubule and signals to arterioles to initiate changes in glomerular filtration rate. the distal tubules and afferent arterioles are situated on the surface of the kidney of amphiuma means. micropuncture techniques were used to measure luminal and intracellular chloride concentrations and the associated electrical potential differences, while tubular perfusion rate w ... | 2013 | 3618789 |
| hormonal control of glucose production by amphiuma means liver in organ culture. | | 1995 | 177330 |
| ion transport proteins and aquaporin water channels in the kidney of amphibians from different habitats. | amphibians are known to spend part of their life on land and return to water to reproduce. however, some urodeles spend their entire life in water, while others succeed in completely avoiding water even during reproduction. osmoregulatory mechanisms must therefore be different in the diverse environmental conditions of their respective life histories. the architecture of the kidney is similar in all amphibians; as a consequence the ion-water equilibrium must be regulated in the different environ ... | 2003 | 14522594 |
| dynamics of glomerular ultrafiltration in amphiuma means. | to study renal function in amphiuma means, the hydrostatic pressures in vascular and tubular structures and the glomerular filtration rate were determined at different arterial blood pressures. in the arterial blood pressure range studied no evidence of autoregulation of the glomerular capillary pressure of the hydrostatic pressure gradient over the capillary membrane was found. the glomerular filtration ceases at an arterial blood pressure below 12 cm h2o. no significant difference between tubu ... | 1981 | 7290911 |
| morphological and physiological factors affecting oxygen uptake and release by red blood cells. | the kinetics of oxygen uptake and release by human, salamander (amphiuma means), and artificially constructed red cells were measured under a variety of physiological conditions using stopped-flow, rapid mixing techniques. the results were analyzed quantitatively using the generalized, three-dimensional disc model that was developed in two previous publications (vandegriff, k. d., and olson, j. s. (1984) biophys. j. 45, 825-835 and vandegriff, k. d., and olson, j. s. (1984) j. biol. chem. 259, 1 ... | 1984 | 6490634 |
| acid-base regulation in response to environmental hypercapnia in two aquatic salamanders, siren lacertina and amphiuma means. | the partial pressure of co2 (pco2) in certain areas of the aquatic habitat of the salamanders siren lacertina and amphiuma means frequently rises to values of up to 60 mm hg. this ambient hypercapnia occurs due to hindrance of gas exchange between water and air caused by dense water-surface vegetation. in order to investigate the acid-base regulation in response to the respiratory acidosis, which wound be expected to result from the high co2 conductance of the amphibian skin, specimens of both s ... | 1982 | 6815749 |
| chloride conductance of the amphiuma red cell membrane. | like most other red cells, the giant erythrocytes of amphiuma means possess a system for rapid exchange of chloride across the membrane. also, there are indications that the net transport of chloride in these cells is slow. the size of amphiuma erythrocytes allows direct measurements of membrane potential with microelectrodes. the present work exploits the possibility that such measurements can be used to give a quantitative estimate of the chloride conductance (gcl) of the amphiuma red cell mem ... | 1978 | 24748 |
| effect of calcium on the membrane potential of amphiuma red cells. | an increase in extracellular ca concentration causes the membrane of giant red cells of the salamander, amphiuma means, to undergo a marked, transient hyperpolarization. this hyperpolarization is caused by an increase in k permeability of the membrane as judged from the k sensitivity of the membrane potential and from the rate of k loss under influence of raised extracellular ca concentration. at constant external ph, the induction of hyperpolarization by increased extracellular ca has a relativ ... | 1976 | 3652 |
| transcription of complementary repeat sequences in amphibian oocytes. | repeat sequences are transcribed in the germinal vesicles of amphibian oocytes. in the hnrna population both complements of the repeats are found and can be readily detected because they form intermolecular duplex structures. the structure and formation of duplex regions have been studied in the hnrna of xenopus laevis, triturus cristatus, amphiuma means and necturus maculosus, a series of amphibians of increasing genome size (c-value). in t. cristatus, the duplex structures are mostly 600-1200 ... | 1982 | 6890891 |
| the existence of a tubulo-glomerular feedback mechanism in the amphiuma nephron. | a single nephron tubulo-glomerular feedback control of the glomerular filtration rate, which is known in mammalian animals, could be one way by which amphibians regulate the glomerular filtration rate (gfr). to investigate whether the amphiuma means shows any sign of a tubulo-glomerular feedback control, micropuncture experiments were carried out. six different series of experiments were performed. in the first series, tubular stop-flow pressure (sfp) was measured during distal tubular perfusion ... | 1981 | 7290910 |
| a single-cell technique for the measurement of membrane potential, membrane conductance, and the efflux of rapidly penetrating solutes in amphiuma erythrocytes. | we describe a single-cell technique for measuring membrane potential, membrane resistance, and the efflux of rapidly penetrating solutes such as cl and h2o. erythrocytes from amphiuma means were aspirated into a sylgard (dow corning corp.)-coated capillary. the aspirated cell separated a solution within the capillary from a solution in the bath. each of these two solutions was contiguous with approximately 5% of the total membrane surface. microelectrodes placed concentrically within the capilla ... | 1980 | 7441192 |
| the electrical properties and active ion transport across the urinary bladder of the urodele, amphiuma means. | 1. the electrical properties and the active transport processes of the isolated urinary bladder of the urodele, amphiuma means, were studied by mounting this tissue as a flat sheet between two halves of a lucite chamber. the mean transepithelial potential difference was 70-2 +/- 2-3 mv (serosa positive), the mean short-circuit current was 10-9 +/- 0-5 micriona/mg of dry weight and the mean transepithelial d.c. resistance was 6540 +/- 374 omega mg of dry weight. 2. the short-circuit current (isc) ... | 1977 | 850164 |
| effects of alanine, glycine and glutamic acid on nitrogenous excretion by amphiuma means liver in organ culture. | high concentrations (10 mm) of alanine, glycine, and glutamic acid in the culture medium had no effect on urea production in amphiuma means liver in organ culture. ammonia production was increased in media containing added alanine and glycine, but reduced in medium with added glutamic acid. | 1976 | 1269600 |
| the effects of phenformin on glucose, glycogen and lactate metabolism in amphiuma means liver organ cultures. | | 1975 | 3362 |
| hepatocyte function in long-term organ culture of amphimuma means liver. | fragments of liver from the adult urodele amphiuma means, the congo eel, were maintained in organ culture for up to 70 days. the normal electrophoretic patterns of several enzymes were retained. the activities of ornithine transcarbamylase, arginase, glutamate oxalacetate transaminase and glutamate pyruvate transaminase, and urea production, glucose uptake and tissue glycogen content remained relatively constant throughout the culture period. histological organization and hepatocyte ultrastructu ... | 1975 | 1158982 |
| organ culture of adult amphiuma means kidney: effects of media and urea on ammonia production, glycogen content and cell proliferation. | | 1975 | 234345 |
| cutaneous respiration in the congo eel amphiuma means (amphibia: urodela). | | 1975 | 234040 |
| radiocesium (137cs) concentrations in the two-toed amphiuma (amphiuma means) and the lesser siren (siren intermedia). | this study sought to determine radiocesium (137cs) concentrations in two species of aquatic salamanders - the two-toed amphiuma (amphiuma means) and the lesser siren (siren intermedia) on the savannah river site. concentrations (137cs bq/g, dry wt) of the two species were similar at both 137cs-contaminated (a. means = 0.733 ± 0.242, n = 5; s. intermedia = 0.839 ± 0.722, n = 5) and reference sites (a. means = 0.028 ± 0.020, n = 5; s. intermedia = 0.042 ± 0.027, n = 11). salamanders captured in ar ... | 2020 | 31751801 |
| mercury concentrations in the two-toed amphiuma (amphiuma means) and the lesser siren (siren intermedia): validating non-lethal sampling methods in southeastern aquatic salamanders. | the global decline of amphibians is a major conservation issue. many stressors are recognized for this decline including exposure to environmental contaminants. mercury (hg) is an environmental contaminant that bioaccumulates in wildlife and can cause a variety of negative impacts across taxa, including amphibians. amphiuma and siren spp. can comprise a large portion of biomass within their respective ecosystems, and thus, likely serve as important predators or prey in wetland communities. howev ... | 2019 | 31350589 |
| amino acid sequences of lower vertebrate parvalbumins and their evolution: parvalbumins of boa, turtle, and salamander. | one major parvalbumin each was isolated from the skeletal muscle of two reptiles, a boa snake, boa constrictor, and a map turtle, graptemys geographica, while two parvalbumins were isolated from an amphibian, the salamander amphiuma means. the amino acid sequences of all four parvalbumins were determined from the sequences of their tryptic peptides, which were ordered partially by homology to other parvalbumins. phylogenetic study of these and 16 other parvalbumin sequences revealed that the tur ... | 1984 | 6599978 |
| effect of extracellular ca2+, k+ and oh- on erythrocyte membrane potential as monitored by the fluorescent probe 3,3'-dipropylthiodicarbocyanine. | changes in fluorescence intensity of thiodicarbocyanine, dis-c3(5), were correlated with direct microelectrode potential measurements in red blood cells from amphiuma means and applied qualitatively to evaluate the effects of extracellular ca2+, k+ and ph on the membrane potential of human red cells. increasing extracellular [ca2+] from 1.8 to 15 mm causes a k+-dependent hyperpolarization and decrease in fluorescence intensity in amphiuma red cells. both the hyperpolarization and fluorescence ch ... | 1982 | 7082665 |
| morphology of the advanced-stage larva of eustrongylides wenrichi canavan 1929, occurring encapsulated in the tissues of amphiuma in louisiana. | larval nematodes identified as eustrongylides wenrichi canavan 1929, from cysts in the tissues of amphiuma means tridactylum cuvier in louisana were redescribed. the extent of differentiation of the sex organs was found to be greater than that of 3rd-stage dioctophyma renale, or of the infective stage of trichinella spiralis, and comparable with the late 4th-stage larva of secernentean (phasmid) nematodes. | 1979 | 448605 |
| comparative and developmental patterns of amphibious auditory function in salamanders. | early amphibious tetrapods may have detected aquatic sound pressure using sound-induced lung vibrations, but their lack of tympanic middle ears would have restricted aerial sensitivity. sharing these characteristics, salamanders could be models for the carryover of auditory function across an aquatic-terrestrial boundary without tympanic middle ears. we measured amphibious auditory evoked potential audiograms in five phylogenetically and ecologically distinct salamanders (amphiuma means, notopht ... | 2016 | 27766381 |