bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of diet on growth and reproduction in gray short‐tailed opossums (Monodelphis domestica)
Authors: Cothran E. Gus , Aivaliotis M. J. , Vandeberg J. L. 
Published: June 2005

AbstractIn order to develop standard conditions for rearing the gray short‐tailed opossum, Monodelphis domestica, as a potentially useful experimental laboratory animal, the effects of four different diets on growth and reproduction were assessed. One diet was a meat‐based diet prepared in the laboratory. The other three diets were commercially produced fox foods designated Reproduction diet, Lactation diet, and Growing and Furring diet. All pairs of M. domestica fed the Reproduction diet produced at least one litter, but only two‐thirds or fewer of the pairs fed any of the other three diets reproduced. There were no significant differences in the number of young born per litter or the number of young weaned per litter among the diets. Weight at weaning was significantly lower for individuals on the meat‐based diet compared to those on the fox food diets. Young on the meat‐based diet suffered 50% mortality within 6 weeks after weaning, whereas none of the animals fed the fox food diets died within the same 6‐week period.Age‐weight data were described using the Bertalanffy growth function. In terms of growth and overall reproductive performance, the fox food diets were clearly superior to the meat‐based diet, and the Reproduction diet was judged to be the best of the fox food diets tested. Growth curves, from birth to 550 days of age, of individuals fed the Reproduction diet were developed and can be used as standards for the species under laboratory conditions. The maximal weights attained by animals fed the fox food diets were similar to the weights of the wild‐caught founders of the laboratory population, indicating that the fox food diets provide adequate nutrition for normal growth. An additional observation was that females housed singly past the normal age of sexual maturity attained significantly lower adult weights than did females that were paired with males at 6 months of age.
Effects of environmental salinity on intercellular organization and junctional structure of chloride cells in early stages of teleost development
Authors: Hwang Pung Pung , Hirano Reijiro 
Published: June 2005

AbstractMorphology of chloride cells was studied in embryos, larvae and juveniles of ayu (Plecoglossus altivelis), carp (Cyprinus carpio) and flounder (Kareius bicoloratus). Chloride cells of seawater‐adapted fishes interdigitated to neighboring cells and linked each other with leaky junctions. No such interdigitation or a leaky junction was found in those of freshwater fishes. Larval ayu were able to tolerate direct transfer from fresh water to seawater even immediately after hatching. Juvenile flounder reared in seawater for 60 days were able to adapt to fresh water. Their chloride cells started developing or degenerating interdigitations and leaky junctions within 3 h after the transfer. Juvenile ayu of landlocked form caught in Lake Biwa survived in seawater for no longer than 6 h. Juvenile carp died within 12 h after transfer to 15%. seawater. Newly hatched flounder did not survive in fresh water for longer than 48 h. Their chloride cells did not show any morphological change, although the epithelial cells were severely damaged. Thus, the ability of chloride cells to modify their intercellular organization and junctional structure appears to play a critical role in salinity adaptation.
Action of polyvalent cations on sodium transport across skin of larval and adult Rana catesbeiana
Authors: Alvarado Ronald H. , Cox Thomas C. 
Published: June 2005

AbstractThe actions of alkaline earth (AE) and transition element (TE) cations on Na+ transport across skin of larval and adult Rana catesbeiana were compared. Bathed on the outside by Ca+2‐free Ringer's, both larval and adult skins maintained a stable short‐circuit current (3–4 μAmps cm−2 for larval skin and 20–30 μAmps cm−2 for adult skin). Addition of Ca+2 to the external bath reduced the SCC; maximal inhibition was about 36% for larval skin and 22% for adult skin. Other AE divalent cations were also inhibitory. The order of effectiveness was: Ba+2 = Ca+2 > Sr+2 > Mg+2 for larval skin and Ba+2 > Ca+2 = Mg+2 for adult skin. Sodium influx was markedly elevated when Ca+2 was removed from the external medium. Current‐voltage analysis indicated that Ca+2 increases the resistance of the active pathway without affecting the shunt resistance or the electromotive force of Na+ transport (ENa) in larval and adult skins.The SCC across adult skin was stimulated by TE cations (Co+2, Cd+2, La+3). These ions were inhibitory on larval skin. The transition in the response occurred at stage XXI. The inhibitory effect of TE on larvel skin resembles that seen in response to AE cations and we postulate a common mechanism. Since larval skin lacks the selective Na+ channels found in apical membranes of adult skin, we infer that the mechanism of inhibition by AE cations is not on these channels. A more general phenomenon such as change in surface charge at the apical membrane seems more reasonable. The stimulatory action of TE cations in adult skin is discussed in terms of interference with the Na+‐self‐inhibition response. Apparently, larval skin lacks some component of the molecular mechanism underlying this response.
The Limulus sperm motility‐initiating peptide initiates acrosome reactions in sea water lacking potassium
Authors: Clapper David L. , Epel David 
Published: June 2005

AbstractDuring fertilization in Limulus, the spermatozoa first attach to the egg and then undergo an acrosomal reaction. In this reaction, the acrosomal vesicle exocytoses, and a long, preformed acrosomal filament is extruded (and subsequently penetrates the egg chorion). The egg surface component that triggers the acrosome reaction has not yet been solubilized; therefore, previous studies have examined either spontaneous acrosome reactions or acrosome reactions that were triggered by eggs (or insoluble egg fragments), elevated extracellular Ca2+, or Ca2+ ionophores. In this study, we report a new method for initiating acrosome reactions in Limulus sperm. When the Limulus sperm motility‐initiating peptide (SMI) is added to sperm in K+‐free sea water, greater than 90% acrosome reactions are initiated within 5 min. However, less than 5% acrosome reactions occur either in K+‐free sea water lacking SMI or when SMI is added to sperm in either normal sea water or K+‐and Ca2+‐free sea water. Experiments with K+ ionophores (nigericin and valinomycin), a K+ channel blocking agent (tetraethyl ammonium), an Na+ ionophore (monensin), and reagents that increase the intracellular pH (monensin, nigericin, and NH4Cl) indicate that changes in intracellular K+, Na+, or H+ do not mediate SMI‐initiated acrosome reactions. The K+/Ca2+ ratio determines whether or not SMI will initiate acrosome reactions, with > 50% acrosome reactions being initiated when this ratio is below 0.3. In that K+ movement does not appear to be the critical event, possibly the K+/Ca2+ ratio either determines the rate of Ca2+ entry or controls the conformation of sperm surface molecules to allow SMI to initiate acrosome reactions in low K+.
The production of cloned fish in the medaka (Oryzias latipes)
Authors: Naruse K. , Ijiri K. , Shima A. , Egami N. 
Published: June 2005

AbstractThe measurement of cellular DNA content by DNA microfluorometry revealed that medaka embryos that were fertilized with normal sperm and exposed to heat shock (41°C for 3 min) or hydrostatic pressure (700 kg/cm2 for 10 min) at 85–95 min after insemination were tetraploid. Embryos fertilized with normal sperm and exposed to heat shock (41°C for 2 min at 2–3 min after insemination) were triploid. These results suggest that heat shock or hydrostatic pressure at 85–95 min after insemination arrests the first cleavage, while heat shock at 2–3 min after insemination arrests the second meiotic division.Medaka clones have been produced by the following method: Eggs from orange‐red or variegated variety were activated by UV‐irradiated, genetically impotent sperm of wild‐type fish (UV sperm). The haploid eggs obtained were diploidized by preventing the first cleavage with heat shock or hydrostatic pressure to produce homozygous females. Each of the two homozygous females was mated with vasectomized male in isotonic balanced salt solution to collect unfertilized eggs. The collected eggs were activated with UV sperm and converted from haploid to diploid by arrest of the second meiotic division with heat shock. Hatched fry of each homozygous diploid (all females) were fed with a methyltestosterone‐containing diet (40 μg/gm diet) to produce sex‐reversed males, which were mated with brood females, and thus two cloned lines were obtained.
Fsh‐induced gonadal development in juvenile lizards, Eumeces obsoletus
Authors: Masson Greg R. , Guillette Louis J. 
Published: June 2005

AbstractJuvenile lizards (Eumeces obsoletus) treated with FSH exhibited germ cell proliferation. However, only the first stages of oogenesis or spermatogenesis were elicited. No difference in spermatogenic stage was observed between treatment groups. Vitellogenesis was not observed in treated females although the primary (largest) follicles exhibited a granulosa composed of a single cell type indicative of a follicle just prior to yolking. In addition to gonadal effects, accessory structures which are steroid dependent exhibited changes. Oviductal weight increased significantly with FSH treatment. Histological examination revealed that both oviductal glands and oviductal epithelium increased in size as did epididymal cell heights in males. These structures are steroid dependent in adults. These data suggest that juvenile gonads respond to gonadotropin although not in a typical adult manner. Sexual maturation is not only dependent on gonadal responsiveness but on the maturation of the hypothalamohypophysial axis and thus, on gonadotropin secretion as well. In addition, a critical amount of lipid storage may be required for vitellogenesis and gonadal function.
Seasonal variations in body growth rates and circulating levels of growth hormone in the goldfish, Carassius auratus
Authors: Marchant Tracy A. , Peter Richard E. 
Published: June 2005

AbstractSeveral times throughout the year, changes in serum growth hormone (GH) levels over a 24‐h period were determined in goldfish maintained under photoperiods and temperatures simulating natural (Edmonton) environmental conditions. In the goldfish a reproducible daily rhythm in circulating GH levels was not present at any time of the year. The average serum GH level over the daily sampling period and the instantaneous relative growth rate in goldfish sampled at the various times of the year were also determined. The highest mean daily serum GH levels were found in March and June, whereas the lowest level was found in goldfish sampled in November. Changes in mean daily serum GH levels were closely correlated to seasonal changes in daylength. The highest growth rate was found in goldfish sampled in July, whereas the lowest growth rates were found in February and March. Female goldfish exhibited a faster growth rate than male goldfish at certain times of the year, but sexual differences in growth rate were correlated with sexual differences in serum GH levels only in November when female goldfish had a higher serum GH level than male goldfish.
Sperm duct contractions mediate centrally evoked sperm release in goldfish
Authors: Dulka Joseph G. , Demski Leo S. 
Published: June 2005

AbstractIn order to determine the peripheral mechanisms underlying sperm release (SR) in goldfish, the contractile activity of the sperm ducts (SD) and testes were monitored during SR responses evoked by electrical stimulation of the brain. Electrical stimulation of the brain triggered testicular and SD contractions, and SR, while electrical stimulation of the genital nerve branch to the SD evoked only SD contractions and SR. Centrally activated SD contractions and SR were blocked by sectioning the SD genital nerve, while testicular contractions were unaffected. Testicular contractions do not appear necessary for centrally evoked SR since the response can be elicited from preparations in which the testes were separated from the SD. The results indicate that SR in goldfish is primarily mediated by the SD and not the testes. Testicular contractions may, however, serve to load the SD with milt. The functional significance of the central pathway(s) associated with SD and testicular contractions are discussed.
Development of pronuclei from human spermatozoa injected microsurgically into frog (Xenopus) eggs
Authors: Ohsumi Keita , Katagiri Chiaki , Yanagimachi Ryuzo 
Published: June 2005

AbstractHuman spermatozoa were demembranated with Triton X‐100 (TX) and injected into the mature eggs of Xenopus laevis. The nuclei of these spermatozoa decondensed and developed into pronuclei. Chromosomes did not appear in the eggs until the end of a 5‐hr incubation period. When the demembranated human spermatozoa were further treated with dithiothreitol (DTT) before they were injected into the eggs, the sperm nuclear decondensation and pronuclear development took place considerably faster than in spermatozoa treated with the detergent alone. By the end of the 5‐hr incubation period, decondensed chromatin threads or chromosome‐like structures appeared, but none of the eggs cleaved. When human spermatozoa were injected into fullgrown ovarian oocytes with intact germinal vesicle (GV) or oocytes which had matured without GV, the nuclei of a proportion of TX‐treated and all TX‐DTT‐treated sperm decondensed but showed no sign of developing into pronuclei. Sperm nuclei injected into maturing oocytes formed condensed chromatin fragments as long as the oocytes were not activated, but they transformed into pronuclei when the oocytes were stimulated with electric shock. These results indicate that the cytoplasmic factors responsible for the decondensation of human sperm nuclei are present in egg cytoplasm independent of GV‐materials. We also suggest that the factors controlling development of decondensed sperm nuclei into pronuclei are dependent on GV materials.
Cortical granule exocytosis is coupled with membrane retrieval in the egg of Brachydanio
Authors: Donovan Michael J. , Hart Nathan H. 
Published: June 2005

AbstractActivation of the teleost (Brachydanio) fish egg includes the exocytosis of cortical granules, the construction of a mosaic surface consisting of the unfertilized egg plasma membrane and the limiting membranes of the cortical granules, and the appearance of coated and smooth vesicles in the cytoplasm (Donovan and Hart, '82). Unfertilized and activated eggs were incubated in selected extracellular tracers to (1) determine experimentally if cortical granule exocytosis was coupled with the endocytosis of membrane during the cortical reaction, and (2) establish the intracellular pathway(s) by which internalized vesicles were processed. Unfertilized eggs incubated in dechlorinated tap water or Fish Ringer's solution containing either horseradish peroxidase (HRP; 10 mg/ml), native ferritin (12.5 mg/ml), or cationized ferritin (12.5 mg/ml) were activated as judged by cortical granule breakdown and elevation of the chorion. Cells treated with HRP and native ferritin exhibited a delay in cortical granule exocytosis when compared with wateractivated eggs lacking the tracer. Each tracer was internalized through the formation of a coated vesicle from a coated pit. Since coated pits appeared to be topographically restricted to the perigranular membrane domain of the mosaic egg surface, their labeling, particularly with cationized ferritin, strongly suggested that the retrieved membrane was of cortical granule origin. Cationized ferritin and concanavalin A (Con A) coupled with either hemocyanin or ferritin labeled the surface of the unactivated egg and both domains of the mosaic egg surface. Transformation of the deep evacuated cortical granule crypt into later profiles of exocytosis was accompanied by increased Con A binding. Within activated egg cortices, HRP reaction product, native ferritin, and cationized ferritin were routinely localized in smooth vesicles, multivesicular bodies, and autophagic vacuoles. Occasionally, each tracer was found in small coated vesicles adjacent to the Golgi and within Golgi cisternae. The intracellular distribution of HRP, native ferritin, and cationized ferritin suggests that internalized membrane is primarily processed by organelles of the lysosomal compartment. A second and less significant pathway is the Golgi complex.
Regional differences in the histochemical localization of carbonic anhydrase in the midgut of tobacco hornworm (Manduca sexta)
Authors: Ridgway Richard L. , Moffett David F. 
Published: June 2005

AbstractCarbonic anhydrase (CA) activity was assayed by a histochemical method in mounted cryostat sections of larval midgut of Manduca sexta (Insecta: Sphingidae). In anterior and middle midgut most CA activity was associated with apical microvilli of goblet cells; with occasional patchy staining of the columnar cell brush border in anterior midgut. In contrast, in the posterior midgut, the apical microvilli of goblet cells showed no CA activity, but intense staining was associated with the brush border of columnar cells. Staining of mitochondria and nuclei was seen in all midgut regions. In addition, midguts from late fifth instar larvae showed intense staining of spherites (mineral concretions). Acetazolamide (10−5M) completely inhibited staining at all sites except nuclei and spherites. Thiocyanate (100 mM) completely inhibited staining at all sites except anterior and middle goblet cell microvilli, which remained partially reactive. These results suggest that the anteriormiddle and posterior regions play different roles in generating and managing the alkalinization of midgut contents characteristic of lepidopteran midgut. The different sensitivities of CA activity in anterior‐middle and posterior midgut to thiocyanate raises the possibility that more than one form of the enzyme may be involved.
Incorporation of 14C‐bicarbonate into the free amino acid pool during hyperosmotic stress in an intertidal copepod
Authors: Burton Ronald S. 
Published: June 2005

AbstractIn response to hyperosmotic stress, the harpacticoid copepod Tigriopus californicus rapidly accumulates high intracellular concentrations of free alanine and proline. Using 14C‐bicarbonate as a tracer, in vivo experiments were carried out to determine if pyruvate or phosphoenolpyruvate carboxylation function in the synthesis of carbon skeletons for free amino acid (FAA) synthesis. Label was incorporated into four FAA (aspartate, glutamate, proline, and alanine) during hyperosmotic stress. Relative specific activities of the FAA synthesized in vivo and in vitro enzyme activities suggest that malic enzyme (EC 1.1.1.40) carries out the carboxylation reaction. Incorporation of label into proline was extensive for at least 24 hr after transfer of adults acclimated to 50% seawater to 100% seawater; the proline pool showed relatively slow turnover following its accumulation (approximately 40% drop in specific activity in 48 hr) compared to the other FAA (complete loss of label in 24 hr). While bicarbonate fixation occurs in animals acclimated to both 50% and 100% seawater, label is observed in glutamate and aspartate but not proline. The results of these experiments suggest that the metabolic pathway by which bicarbonate label is incorporated into proline is activated by hyperosmotic stress and is effectively shut down following 24–48 hr of proline accumulation.
Lack of adrenergic control of dorsal aortic blood pressure in the resting eel, Anguilla australis
Authors: Hipkins Scott F. , Smith David G. , Evans Barbara K. 
Published: June 2005

AbstractDorsal aortic and cardinal venous blood pressures, dorsal aortic blood flow, and heart rate were measured in different combinations in conscious unrestrained eels (Anguilla australis). One group of animals was treated with either bretylium (10 mg.kg−1) or saline vehicle and dorsal aortic blood pressure and heart rate were monitored for the next 6 days. Two other groups were treated with phentolamine (5 mg.kg−1) and either dorsal aortic blood pressure and heart rate, or dorsal aortic blood flow and venous pressure monitored for 6 hr. In vivo treatment with either bretylium of phentolamine produced effective blockade of the α‐adrenoceptor‐mediated vasoconstriction of stimulated saline‐perfused trunk preparations; however, neither drug had no lasting effects on arterial blood pressure. In addition, phentolamine had no lasting effects on venous blood pressures or dorsal aortic blood flow. It is concluded that, in the resting eel, systemic vascular resistance is not normally under adrenergic control.
Biochemical responses to temperature in the contractile protein complex of striped bass Morone saxatilis
Authors: Moerland Timothy S. , Sidell Bruce D. 
Published: June 2005

AbstractThe effects of acute and long‐term changes in temprature upon catalytic and calcium regulatory function of red (slow oxidative) and white (fast glycolytic) muscle from striped bass (Morone saxatilis) were determined. Acclimation to 5°C or 25°C had no significant effect on catalytic function (ATPase activity) or regulatory sensitivity (Ca++‐activation) of myofibrils from either muscle type. Substantial differences between red and white muscle were found in the intrinsic thermal sensitivity of maximally‐activated Mg++‐Ca++ myofibrillar ATPase. Arrhenius plots of myofibrillar ATPase from white muscle show one significant breakpoint at 29°C, with activation energies (Ea) of 2.3 and 23.4 kcal mole−1 at temperatures above and below this transition, respectively. Arrhenius plots of myofibrillar ATPase from red muscle show two transitions occurring at 22 and 9°C, with Ea of 7.6 kcal mole−1 above 22°C and 18.3 kcal mole−1 between 9 and 22°C. Activation energies for myofibrils from red muscle increase substantially to approximately 107.3 kcal mole−1 below the 9°C breakpoint. Differences in the intrinsic thermal sensitivity of red and white muscle catalytic function are apparently due to interaction of actomyosins and calcium regulatory proteins which are specific to each muscle type. The results suggest that capacity for sustained swimming in striped bass, which is powered exclusively by red muscle, will be severly impaired at cold temperature unless compensations occur above the level of contractile proteins.