bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metabolic fates of lactate during recovery from activity in an anuran amphibian, Bufo americanus
Authors: Withers Philip C. , Lea Malcolm , Solberg Thomas C. , Baustian Mark , Hedrick Michael 
Published: June 2005

AbstractThe aerobic metabolism of Bufo americanus is 0.56 ± S.E. 0.12 ml O2 g−1 h−1; lactate accumulates to 0.63 ± S.E. 0.06 mg lactate g−1, during a 10‐min bout of enforced activity. About 20% of the energy expended during activity is derived from anaerobic metabolism and 80% from aerobic metabolism. Aerobic metabolic rate decreases rapidly after the cessation of activity and reaches resting levels by 1 hr post‐activity. Whole body lactate content declines more slowly and in a linear fashion, reaching resting levels about 1 hr post‐activity. About 7% or less of the 14C‐lactate administered after activity was estimated to have been eliminated by aerobic metabolism of the lactate; the remaining 14C activity was recovered in body tissues and urine or was excreted across the skin. Most tissues examined (liver, skin, ventricle, lungs, stomach, intestine) had similar 14C activities per gram of tissue, but skeletal muscle had a higher 14C activity per gram. Considerable fractions of the tissue 14C content were isolated as glycogen (22–39%), lower fractions as protein (1–24%), and little as lipid (2–4%). There are some differences in the distribution of 14C label, depending on whether 14C‐lactate or 14C‐glucose were administered at rest, or after activity, but little of the 14C label was aerobically metabolised for either substrate. The observed fraction of lactate oxidised by aerobic metabolism (<10% of total 14C lactate) is less than the theoretical value for the most energetically economical metabolism of lactate (17%: a Meyerhof quotient of 5) and considerably less than the fraction of lactate oxidised by mammals (20–90%).
Metabolic responses to cold acclimation in the swimming musculature of lake whitefish, Coregonus clupeaformis
Authors: Blier Pierre , Guderley Helga 
Published: June 2005

AbstractTo evaluate the acclimatory capacity of juvenile lake whitefish (Coregonus clupeaformis), a species which is extensively distributed in northern latitudes and which experiences a fairly wide range of temperatures, we assessed the effect of acclimation at 5 and 18°C on the glycolytic and aerobic capacity of swimming muscle. Cold acclimation during six months does not increase the proportion of red muscle in the swimming musculature or the levels of cytochrome oxidase and citrate synthase, indicating a lack of thermal compensation of the aerobic capacity of the swimming muscles. By contrast, the glycolytic potential of the swimming musculature, as assessed by the activities of hexokinase and phosphofructokinase, displayed positive thermal compensation. This may facilitate the conservation of locomotory capacity at low temperatures.
Surface behavior in artificially constricted sand dollar eggs and egg fragments
Authors: Rappaport R. 
Published: June 2005

AbstractIn mathematical and computer models of cytokinesis in animal cells, it is sometimes assumed that the nature of the surface is such that it will develop furrowing behavior independently of the mitotic apparatus in response to folding and distortion. Similarly, it has been postulated that after the dividing cell has achieved a moderate degree of constriction, the process is completed with little or no additional energy or preorganized structure. The purpose of these experiments was to test those assumptions by artificially constricting the surface of Echinarachnius parma eggs with a pair of hooks at the time of cytokinesis.When the surface of unnucleated egg fragments or those containing single asters were constricted to 27–30 μm in diameter, no furrowing occurred in the constriction plane, and the fragments immediately rounded up when the hooks were removed. When fragments containing a single aster were reshaped into cylinders, the surface developed astral constrictions. When intact cells were constricted so that the constriction plane did not coincide with the plane of an astral center, no furrowing occurred. When the constriction plane and that of the astral center coincided or when they were very close, furrowing activity developed and then regressed.These results indicate that the sand dollar egg surface does not tend to develop furrowing activity in response to imposed folds and distortion independently of the mitotic apparatus. They also suggest that single asters can elicit contractile activity in nearby surface.
In vitro fusion of newt macrophages
Authors: Płytycz Barbara , Potter Sandra W. , Cohen Nicholas , Bayne Christopher J. 
Published: June 2005

AbstractSpontaneous formation of multinucleate giant cells is often observed in in vitro cultures of peritoneal adherent macrophages from the newts, Notophthalmus viridescens and Taricha granulosa (urodele amphibians). The frequency of such giant cells in these cultures is increased by the addition of phorbol myristic acetate at the initiation of the cultures. This high frequency of multinucleate cells permitted us to evaluate whether multinucleate giant cells arise by cell fusion and/or by repeated nuclear division without cytokinesis. Cell fusion is readily detectable by scanning electron microscopy. To determine whether nuclear division without cytokinesis also occurs, some cultures were treated with colchicine to arrest mitotic figures; others were pulsed with tritiated thymidine to detect DNA synthesis. Mitotic figures were not seen in acridine orange‐stained samples. In monolayers that were processed for autoradiography, only a few nuclei were marked with tritium. These observations suggest that nuclear division does not contribute significantly, if at all, to the formation of multinucleate giant cells from cultured newt peritoneal macrophages.
Appearance and regulation of an antigen associated with limb regeneration in Notophthalmus viridescens
Authors: Gordon Herman , Brockes Jeremy P. , Wilson Frank 
Published: June 2005

AbstractPrevious reports from this laboratory have documented a cellular antigen, 22/18, associated with regeneration of forelimbs in the newt Notophthalmus viridescens (Kintner and Brockes: Nature 308:67–69, 1984; Journal of Embryology and Experimental Morphology 89:37–55, 1985; Brockes: Science 225:1280–1287, 1984; Kintner et al.: Molecular Basis of Neural Development, 1985). The antigen is expressed at various stages of regeneration in several types of cells including Schwann cells and muscle cells. We report here that, in addition to the previous results, the expression of 22/18 occurs very early in the regeneration process and is initially confined to an apparently nonmuscle, non‐neural population of cells. The well‐defined context of the antigen's first appearance has allowed us to investigate the regulation of its expression. In particular, injury is sufficient to elicit the appearance of 22/18. It can appear prior to mitosis and despite denervation. In circumstances where regeneration is inhibited, expression of 22/18 can persist.
Localized heat‐shock induction in Drosophila melanogaster
Authors: Monsma Scott A. , Ard Robert , Lis John T. , Wolfner Mariana F. 
Published: June 2005

AbstractWe describe a technique for inducing localized expression of genes fused to heat‐shock gene promoters. We demonstrate that a localized heat‐shock response can be induced in Drosophila melanogaster at any developmental stage after formation of the cellular blastoderm by contacting a region of the animal with a heated needle. The size of the induced region can be altered by varying parameters such as the temperature and size of the needle tip. The test system utilized here is a D. melanogaster strain transformed with a fusion of the Drosophila hsp26 gene and the E. coli lacZ gene; the activity of this hybrid gene is monitored in whole animals by staining for β‐galactosidase activity. Induced β‐galactosidase activity is confined to the cells in the region of heating; the β‐galactosidase activity can still be detected 48 hr after the heat shock.Given the heat inducibility of Drosophila heat‐shock promoters in heterologous systems, we suggest that this technique will be useful for allowing spatially controlled induction of a gene of interest in any organism into which fusion genes can be introduced. Additional uses of the technique for following cell movements during development are discussed.
Diel metabolic and activity patterns of the lemon shark (Negaprion brevirostris)
Authors: Nixon Asa J. , Gruber Samuel H. 
Published: June 2005

AbstractComputation of the energy budget, average daily metabolic rate, and standard metabolism require information on hourly metabolic rates over a full 24‐hour period. This study provides such information for the lemon shark, a tropical predator. Simultaneous measurements of metabolism and activity in an annular respirometer demonstrated that oxygen consumption increased from a daytime level of 176 to 210 mgO2 kg−1h−1 at night. Activity increased concurrently from 0.17 to 0.33 bl s−1. The average daily metabolic rate was 16.2 k cal kg−1 at 0.26 bl s−1 and 23°C. Both activity and metabolic rate appear to have endogenous circadian components.
Effect of hyperoxia acclimation on catalase and glutathione peroxidase activities and in vivo peroxidation products in various tissues of the frog Rana ridibunda perezi
Authors: López‐Torres M. , Gil P. , de Quiroga G. Barja 
Published: June 2005

AbstractAmong vertebrates, adult amphibians are known to be especially tolerant to exposure to high environmental oxygen tensions. To clarify the basis for this high O2 tolerance, adult Rana ridibunda perezi frogs were acclimated for 15 days to water‐air phases with either 149 mm Hg O2 (normoxia) or 710 mm Hg O2 (hyperoxia). At the end of the acclimation, various morphometric and biochemical paramaters related to oxidative stress were measured in seven organs and tissues. Hyperoxia acclimation did not change either the total weight of the animals or the total and relative wet weights of the organs studied, except for the brain, which showed weight increases in the hyperoxic group. In vivo tissue peroxidation increased in the kidney; decreased in the skeletal muscle and skin; and did not change in the liver, lung, brain, and heart after hyperoxic exposures. Whereas liver, lung, and skin showed glutathione peroxidase (GSH‐Px) activities with both cumene hydroperoxide (cumene‐OOH) and H2O2 as substrates, skeletal muscle only showed H2O2 GSH‐Px activity. Hyperoxia acclimation did not change either catalase (CAT) or GSH‐Px activities in any organ, except for the liver in which CAT activity was induced by hyperoxia. Thus hyperoxia tolerance in this species does not need the induction of H2O2‐detoxifying enzymes in the majority of the organs. It is suggested that the high O2 tolerance of this amphibian species is related to its comparatively high constitutive GSH‐Px activities.
Development of β‐amino acid transport in the kidney
Authors: Chesney Russell W. , Zelikovic Israel , Dabbagh Shermaine , Friedman Aaron , Lippincott Shirley 
Published: June 2005

AbstractThis study focuses on the maturation of the renal β‐amino acid transport system and uses dietary manipulation as a probe. The epithelial surface of the renal proximal tubule is responsible for the conservation of ions and organic solutes including β‐amino acids. This β‐amino acid transport system is stimulated during periods of reduced dietary intake and permits increased excretion following dietary excess. We have examined transport of the sulfur‐containing β‐amino acid, taurine, as a measure of this renal adaptive response to fluctuations in dietary sulfur amino acid intake and as a substrate for the β‐amino acid transport system.A precession of taurine uptake values by brush border membrane vesicles (BBMV) prepared from nursing rats from youngest to oldest was evidente. However, these membranes demonstrate the full renal adaptive response to altered sulfur amino acid intake after the first week of life. This adaptive response is expressed at the brush border surface by transport changes in both directions (“up regulation” and “down regulation”), through changes in the initial rate (15 sec) of Na+‐taurine cotransport. No alterations in the lipid microenvironment of the membrane, as detected by altered membrane fluidity, were uncovered. Although vesicles from 7‐day‐old pups demonstrate adaptation and accumulate taurine to a limited extent, the accumulation of Na+, which energizes uptake, may be altered, thereby preventing full expression of the adaptive response and of transport capacity at this age.
Stage‐specific response of preimplantation mouse embryos to W‐7, a calmodulin antagonist
Authors: Yamamura Hideki , Spindle Akiko 
Published: June 2005

AbstractInvolvement of calmodulin‐dependent processes in preimplantation development of mouse embryos was studied with the use of N‐(6‐aminohexyl)‐5‐chloro‐1‐naohthalenesulfonamide (W‐7), a specific antagonist of calmodulin. At 25 μM, W‐7 interfered with compaction of eight‐cell embryos, caused decompaction of compacted eight‐cell embryos, inhibited cavitation of late morulae, and caused collapse and degeneration of blastocysts. These effects of W‐7 appear to be due to specific inhibition of calmodulin‐dependent processes, because W‐5, a less active analogue of W‐7, was less effective in interfering with development; at 25 μM, W‐5 had only a slight effect on compaction and had no effect on blastocyst formation, maintenance of blastocoels, or post‐blastocyst development. In addition to the developmental effects just described, W‐7 inhibited cell proliferation in four‐cell embryos and reduced cell numbers of morulae after treatment at the two‐ to eight‐cell stages. There was a marked increase in embryos' sensitivity to W‐7 at the late morula stage, and the sensitivity increased further as embryos developed into blastocysts; the effects of W‐7 were largely reversible after treatment at the two‐cell through the compacted eight‐cell stages, but not after treatment at the late morula or blastocyst stage. At the blastocyst stage, inner cell mass cells appeared to be slightly more resistant to W‐7 than trophectoderm cells. This differential sensitivity became more pronounced at the late blastocyst stage: after 3.5–4‐h exposure of late blastocysts to 25 μM W‐7, all trophectoderm cells degenerated but most of the inner cell masses survived. From these results it appears that calmodulin‐dependent processes are involved in development of mouse embryos at all of the preimplantation stages examined.
Infertility in transgenic female mice with human growth hormone expression: Evidence for luteal failure
Authors: Bartke A. , Steger R. W. , Hodges S. L. , Parkening T. A. , Collins T. J. , Yun J. S. , Wagner T. E. 
Published: June 2005

AbstractIntroduction of the human growth hormone (hGH) gene fused with mouse metallothionein I promoter into domestic mice leads to ectopic synthesis of hGH, marked stimulation of somatic growth, and female sterility. Transgenic females (produced by mating transgenic males to normal females) mated but failed to become pregnant or pseudopregnant as evidenced by the recurrence of vaginal plugs every 5–7 days. Daily injections of 1 mg progesterone, starting on day 1 postcoitum (p.c.), maintained pregnancy, suggesting that the sterility of these animals is due to inadequate luteal function. In ovariectomized female transgenic mice, median eminence (ME) turnover of dopamine (DA) was increased, and plasma prolactin (PRL) levels were reduced, presumably because of the known lactogenic activity of hGH in rodents. From these observations we suspected that either (1) the corpora lutea of these animals are unresponsive to lactogenic hormones, or (2) hGH by stimulating tuberoinfundibular dopaminergic (TIDA) neurons interferes with the increase in PRL release that normally follows mating and this, in turn, leads to luteal failure. To distinguish between these possibilities, transgenic females were treated with PRL‐secreting ectopic pituitary transplants from normal females of the same strain on day 1 p.c. Eight of ten treated females became pregnant and delivered litters. We conclude that infertility of transgenic female mice with hGH expression is due to activation of the TIDA system, suppression of endogenous PRL release, and luteal deficiency.
Influence of postovulatory aging on chromosome segregation during the second meiotic division in mouse oocytes: A parthenogenetic analysis
Authors: O'Neill G. T. , Kaufman M. H. 
Published: June 2005

AbstractA high incidence of parthenogenetic activation was observed when postovulatory aged mouse oocytes were exposed briefly to hyaluronidase in culture medium at 18–26 h after the human chorionic gonadotropin injection for inducing superovulation. The majority of the activated oocytes extruded a second polar body and developed a single haploid pronucleus. Cytogenetic analysis of this class of parthenogenone at metaphase of the first‐cleavage mitosis has clearly demonstrated that the completion of the second meiotic division in activated aged oocytes is not associated with a significant increase in the incidence of chromosome segregation errors. The increasing postovulatory age of oocytes prior to activation was observed to significantly decrease the capacity of activated oocytes to extrude the second polar body.
Localization of ecdysteroids in the eyestalk ganglia of the fiddler crab, Uca pugilator, during anecdysis and proecdysis
Authors: Hopkins Penny M. 
Published: June 2005

AbstractEcdysteroids have been found in eyestalk tissues of the fiddler crab, Uca pugilator. Throughout the molt cycle, ecdysteroids are present in much higher concentrations in the eyestalk tissues than can be accounted for by equilibrium diffusion from the hemolymph. The greatest eyestalk‐to‐hemolymph ratio is found during anecdysis, the nonmolting period when the highest levels of the molt‐inhibiting hormone are being produced and released from the eyestalks. RIA‐active ecdysteroids are localized primarily (but not exclusively) in the medulla terminalis (MT) and medulla interna (MI) portions of the eyestalk ganglia. Relative levels of ecdysteroids extracted from the MT and MI fluctuate during the molt cycle. Ecdysone was the predominant ecdysteroid present in the eyestalks. Histological examination of eyestalks revealed two areas of cell bodies in the MT and medulla externa (ME) that release colloidlike substances into the intraganglionic cortical glial spaces. The location of the MT cell bodies corresponds to the pars distalis‐X‐organ of other crustaceans, but no organ of Bellonci (which has been proposed as a source of ecdysteroidlike compounds in shrimp) was found.
Selectivity of protein sequestration by vitellogenic oocytes of the rainbow trout, Salmo gairdneri
Authors: Tyler Charles R. , Sumpter John P. , Bromage Niall R. 
Published: June 2005

AbstractThe selectivity of protein sequestration by vitellogenic oocytes of the rainbow trout, Salmo gairdneri, was investigated by comparing the rates of uptake of radiolabelled vitellogenin (VTG) and bovine serum albumin (BSA). Fish were injected simultaneously with equal amounts of both 3H‐VTG and 14C‐BSA and sampled subsequently at varying time invervals to assess the rates of uptake of these proteins into the developing oocytes. Both labelled proteins were taken up rapidly into the blood after their injection into the peritoneal cavity. Once in the blood, they became available for sequestration by the vitellogenic oocytes. There was both rapid and selective uptake of 3H‐VTG; within 72 hours half of the 3H‐VTG injected was present within the ovary, whereas only 2.5% of the 14C‐BSA was similarly located. Once within the oocyte, 3H‐VTG was specifically and rapidly processed to yield its constituent yolk proteins, which included 3H‐lipovitellin. In contrast, after 72 hours 14C‐BSA was present in the oocyte as the native, intact protein. However, after 13 days, whereas the yolk proteins had undergone no further processing, remaining stable within the oocyte, much of the BSA within the ovary had been degraded to an array of smaller peptides. Furthermore, after 26 days, whereas all of the 3H‐VTG endocytosed remained within the oocytes as yolk protein, at least half of the BSA taken up initially had been exocytosed. Calculation suggested that 3H‐VTG was sequestered about 60 times more rapidly than 14C‐BSA. Other tissue did not incorporate 3H‐VTG to any significant degree. These results suggest that VTG was sequestered into vitellogenic oocytes by receptor‐mediated endocytosis, whereas BSA, along with other extraneous proteins, was taken up adventitiously.
Caffeine promotes in vitro fertilization of mouse ova within 15 minutes
Authors: Pomeroy K. O. , Dodds J. F. , Seidel G. E. 
Published: June 2005

AbstractEpididymal sperm were collected from C57B16/J × DBA2/J (B6D2) males and allowed to capacitate for 2 hr. When cumulus‐fre oocytes were exposed to sperm for 15 min in either the presence (6.0 mM) or absence of caffeine, fertilization did not occur. However, when cumulus cells were left intact, 23% of oocytes were fertilized in caffeine‐free medium and 62% in caffeine‐containing medium. When cumulus‐free oocytes were incubated with sperm for 30 min, none was fertilized in the absence of caffeine, but 33% were fertilized when 6.0 mM caffeine was present (P < .02). These effects of caffeine were on the sperm, as sperm exposed to caffeine and then coincubated with oocytes for 15 min in essentially caffeine‐free media fertilized a similar percent of oocytes (93%) as when sperm and oocytes were exposed to caffeine during the fertilization period (86%). When sperm were capacitated in caffeine‐containing medium, the percentage of ova fertilized was similar to capacitation without caffeine. We conclude that both cumulus cells and caffeine speed up the fertilization process with mouse gametes and that the effect of caffeine is on the sperm, but not due to more rapid capacitation.
Recent applications of fish cell culture to biomedical research
Authors: Hightower Lawrence E. , Renfro J. Larry 
Published: June 2005

AbstractTissues of the fishes are as amenable to the techniques of modern cell culture as mammalian tissues and organs, and yet this vast resource, comprising thousands of vertebrate species, remains largely unexplored. The model systems that have been developed demonstrate the utility of fish cells as sources of special adaptations and exaggerated physiological systems. In this review, we briefly describe several of the successful models along with recent developments in fish cell culture with the hope of stimulating increased interest in the lower vertebrates as useful complements to mammalian cell culture in biomedical research. The topics covered include epithelial ion transport, endocrinological studies, the cellular stress (heat shock) response, thermotolerance, cancer biology, and environmental toxicology.