bluuebunny/crossref_metadata_2025_split huggingface dataset:
Steroidogenesis in Fundulus heteroclitus. IV. Dichotomous effects of a phorbol ester on ovarian steroid production and oocyte maturation
Authors: Petrino Teresa R. , Lin Yu‐Wai P. , Wallace Robin A. 
Published: June 2005

AbstractThe possible role of protein kinase C (PKC) activation in mediating the stimulatory actions of a Fundulus pituitary extract (FPE) on ovarian steroidogenesis and oocyte maturation was investigated. The phorbol ester, phorbol 12‐myristate 13‐acetate (PMA), alone slightly increased basal 17α‐hydroxy, 20β‐dihydroprogesterone (DHP) and 17β‐estradiol (E2) synthesis and significantly stimulated germinal vesicle breakdown (GVBD). Addition of FPE promoted synthesis of DHP, testosterone (T), and E2, and initiated GVBD. Phorbol ester inhibited FPE‐induced steroidogenesis but increased the number of oocytes that underwent GVBD. Phorbol ester also markedly impeded induction of steroidogenesis by dibutyryl cAMP and differentially affected the conversion of 25‐hydroxycholesterol, pregnenolone, or progesterone to DHP, T, and E2: DHP production was not affected; T production diminished; and E2 synthesis increased (T aromatization also increased). These results suggest an inhibitory role for the PKC pathway on FPE‐induced ovarian steroid production, with PMA appearing to affect various steroidogenic steps. The stimulatory action of PMA on oocyte maturation seems to be independent of follicular steroid production since aminoglutethimide, an inhibitor of steroidogenesis, did not block PMA‐induced GVBD. Moreover, PMA had a marked stimulatory effect on GVBD in denuded oocytes. Thus, in contrast to the inhibitory role found for the PKC pathway on ovarian follicular steroidogenesis, activation of PKC in the oocyte may serve as a signal‐transducing mechanism leading to GVBD. © 1992 Wiley‐Liss, Inc.
In vivo effects of the steroid analogue RU486 on some aspects of intermediary and thyroid metabolism of brook charr, Salvelinus fontinalis
Authors: Vijayan M. M. , Leatherland J. F. 
Published: June 2005

AbstractThe glucocorticoid analogue RU486 was administered by intraperitoneal injection to brook charr (Salvelinus fontinalis) to further explore the role of cortisol on aspects of intermediary and thyroid hormone metabolism of the species.RU486 significantly elevated the hepatosomatic index, hepatic G3PDH activity, and hepatic glycogen content, but was without effect on hepatic protein content, hepatic FPBase activity, or plasma glucose concentration. However, the stressor‐related increase in plasma glucose concentration that was evident in brook charr 24 h following handling and injection was suppressed in RU486‐treated groups.The distribution volume, turnover rates, and metabolic clearance rates of [3H]cortisol were similar in RU486‐ and vehicle‐treated groups.Plasma T3 and T4 concentrations were similar in RU486‐ and vehicle‐treated groups, but hepatic T3 production and hepatic T3 content were lower in RU486‐treated fish; TSH had no effect on hepatic T3 content of vehicle‐treated brook charr but significantly increased T3 content in the RU486‐treated group. These observations support the concept of a role of cortisol in the control of peripheral monodeiodination of T4 in salmonid fish and suggest that RU486 may be a useful drug for evaluating the role of cortisol in fish in vivo. © 1992 Wiley‐Liss, Inc.
CHox‐cad locus may influence quantitative traits in chickens
Authors: Iraqi Fuad , Khatib Hasan , Shani Gilat , Davarsi Ariel , Frumkin Ayala , Zeitlin Gadi , Soller Morris , Fainsod Abraham , Gruenbaum Yosef 
Published: June 2005

AbstractRestriction fragment length polymorphism analysis of BamHI digested chicken DNA with a chicken CHox‐cad homeobox gene probe uncovered two CHox‐cad RFLP alleles. The relation between the RFLP alleles and several quantitative traits was analyzed in two chicken populations having widely different genetic backgrounds: a broiler line and a layer cross. Allelic frequency differed significantly in the broiler line as compared to the egg layer cross. Significant RFLP‐associated effects were found for age at first egg in the layer cross, and for mature body weight and percentage egg production in the broiler cross. © 1992 Wiley‐Liss, Inc.
Protamines, not histones, are the predominant basic proteins in sperm nuclei of solitary ascidian tunicates
Authors: Chiva M. , Lafargue F. , Rosenberg E. , Kasinsky H. E. 
Published: June 2005

AbstractIn this work we study the protein content in sperm nuclei from 10 species of ascidian tunicates. The 7 species that we have investigated cytochemically show type 3 intermediate sperm basic proteins, as observed previously for the solitary tunicate Styela montereyensis (Chiva, Rosenberg, and Kasinsky, J. Exp. Zool., 253:7–19, 1990). We have focused this study on two specific points: the presence of protamines and the presence of somatic histones. In 4 species belonging to the suborder Phlebobranchiata, sperm nuclei contain only a protein more basic than histones (protamine). This protamine has an electrophoretic mobility similar to core histone H4. The nuclei of sperm in the species belonging to the suborder Phlebobranchiata are also characterized by their complete lack of somatic histones. In 5 species from the suborder Stolidobranchiata, sperm nuclei contain a similar protamine. However, 2 species from the genus Styela contain additionally other protamines with different electrophoretic mobilities. For all species belonging to the suborder Stolidobranchiata, we also have found very small quantities of residual somatic histones. We conclude that during the process of spermiogenesis in ascidian tunicates protamines replace histones either completely (Phlebobranchiata) or almost completely (Stolidobranchiata). In this respect spermiogenesis in tunicates (class Ascidiacea) is similar to that in vertebrates which, in general, also display the substitution of somatic histones by protamines. On the other hand, this model is different from that in echinoderms, where the protein content of sperm nuclei consists mainly of somatic histones and sperm‐specific variants of histones. © 1992 Wiley‐Liss, Inc.
Mouse limb bud cells respond to retinoic acid in vitro with reduced growth
Authors: Gardiner D. M. , Gaudier C. , Bryant S. V. 
Published: June 2005

AbstractRetinoic acid (RA) has dramatic effects on the pattern of developing and regenerating vertebrate limbs. These effects are considered to result from RA‐induced changes in the positional identity of limb cells, and involve the formation of extra structures. Whether the growth required to form the supernumerary parts of the pattern is a primary effect of RA treatment or a secondary effect that follows after a change in positional identity is not at present known. In this paper we have investigated the effects of RA treatment on the growth of cells from anterior and posterior halves of mouse limb buds in vitro. We observed that under our culture conditions, limb bud cells treated with 1 nM to 1 μM RA (0.3 ng/ml to 300 ng/ml) continue to grow but do so at a significantly slower rate than control cultures. There is a maximum inhibition of growth (50% of controls) between 10 nM and 100 nM RA, which corresponds to the measured range of concentrations of RA in vivo. Our observation of a significant decrease in growth rate over a wide range of RA concentrations is consistent with comparable reports of growth inhibition for a large number of other cell types in vitro as well as with the observation that exogenous RA inhibits blastemal growth in amphibians during the period of exposure to RA. We propose that the effects of RA on growth, either enhancement in vivo or reduction in vitro, can be seen as consequences of the ability of RA to alter positional identity. Hence, when RA is administered to limb cells in vitro, it is likely that the non‐posterior cells in both anterior and posterior cultures are converted to posterior identity. The resulting decrease in growth can be interpreted as a consequence of the increased uniformity of positional information in vitro. © 1992 Wiley‐Liss, Inc.
Retinoic acid respecifies limb bud cells in vitro
Authors: Hayamizu Terry F. , Bryant Susan V. 
Published: June 2005

AbstractRetinoic acid (RA) is known to have dramatic effects on limb pattern formation and has been shown to exert its effects on limbs by converting anterior limb bud cells into cells with posterior positional properties. In this study we find that dissociated posterior limb bud cells from chick and mouse embryos cultured at high density (micromass cultures) are able to stimulate the formation of supernumerary digits when grafted into developing wing buds and that the positional identity of both chick and mouse limb bud cells can be maintained for finite periods of time in vitro. Furthermore, using this assay system we have tested whether anterior cells from mouse and chick limb buds can be converted into cells with posterior identity by exposure to RA in vitro. We find that anterior limb bud cells acquire posterior properties after culture in the presence of RA. © 1992 Wiley‐Liss, Inc.
Physiological responses to carbon dioxide in embryonic red‐eared slider turtles, Trachemys scripta
Authors: Etchberger Cory R. , Ewert Michael A. , Phillips John B. , Nelson Craig E. , Prange Henry D. 
Published: June 2005

AbstractIn the red‐eared slider turtle, Trachemys scripta, sex is determined by the incubation temperature of the egg: warm temperatures produce females, cool ones produce males, and a narrow range of intermediate temperatures produce both sexes. We asked whether the influence of temperature is modified by the effects of carbon dioxide. Under one current hypothesis, sex is more closely linked to total incubation time and than to temperature. Higher levels of carbon dioxide should lengthen total incubation time and thus mimic the longer incubation times produced by low incubation temperatures. By this hypothesis longer incubation times should increase the tendency to produce males. Trachemys scripta eggs were incubated in atmospheres containing various concentrations of carbon dioxide. While total incubation times were significantly lengthened with elevated carbon dioxide (as if mimicking cool temperatures), sex ratios were altered in favor of females (as if mimicking warm temperatures). This result is compatible with a hypothesis that pH changes affect sex in turtles with TSD. Turtles incubated at elevated levels of carbon dioxide absorbed less yolk, and had more residual yolk, and were somewhat smaller than turtles incubated at lower of carbon dioxide. In some cases, clutches were heterogeneous in their responses to the various levels of carbon dioxide. © 1992 Wiley‐Liss, Inc.
An attempt to determine the mechanisms of Cl−‐exit across the basolateral membrane of eel intestine: Use of different cl−‐transport pathway inhibitors
Authors: Trischitta F. , Denaro M. G. , Faggio C. , Schettino T. 
Published: June 2005

AbstractThe possible mechanisms of Cl−‐exit across the basolateral membrane of the enterocyte in sea water (SW) and freshwater (FW) eel intestine were investigated by observing the response of the short‐circuit current, Isc, equivalent to net Cl−‐absorption, and transepithelial voltage, Vt, to specific or relatively specific inhibitors of different Cl−‐transport pathways. Serosal NPPB [5‐nitro‐2(3 phenylpropylamino)‐benzoate] (10−4 M), the potent blocker of Cl−‐channels in different epithelia, produced a negligible effect on Isc and Vt either in presence or in absence of HCO3− in the bathing solutions. In the presence of HCO3− serosal bumetanide, better than furosemide and torasemide, at a concentration of 10−4 M inhibited Isc and Vt by ∼90% within 15–30 min without changing the transepithelial resistance, Rt. In HCO3−‐free solutions the drug completely collapsed Isc and Vt. The results were similar in both SW and FW eels. In SW fishes serosal SITS (2.5 × 10−4 M) reduced Isc and Vt by ∼50% when HCO3− was present in the solutions. In absence of HCO3− SITS inhibited Isc and Vt by ∼35%, a finding consistent with the presence of a Cl−‐conductance in the basolateral membrane. Under these conditions SITS inhibition disappeared after bumetanide pretreatment. There is little evidence for the presence of a basolateral K+‐conductance since serosal Ba2+ (1 mM) elicited variable effects on Isc and Vt.The results are interpreted as evidence for the presence of bumetanide‐ and SITS‐sensitive Cl−‐ conductance channels in the basolateral membrane of SW and FW eel intestine which would contribute at least 35% of the net Cl−‐absorption. An HCO3−‐dependent Cl−‐transport was also identified since Isc and Vt were reduced by ∼50% when tissues were perfused with HCO3−‐free salines. © 1992 Wiley‐Liss, Inc.
Effects of an augmented nerve supply on forelimb regeneration in the adult mud frog, Rana rugosa
Authors: Kurabuchi Shingo 
Published: June 2005

AbstractForelimbs of the adult mud frog Rana rugosa, when amputated midway through the zeugopodium, regenerate heteromorphically. The resulting regenerative outgrowths were mostly rod shaped and consisted of a cartlaginous core, in which the base was ossified, and muscle elongated distally along the cartilage, the whole being covered by connective tissue and skin. The tip of the regenerating muscle reached a point distally about one third of the length of the regenerative outgrowths. When the innervation of forelimb stumps was augmented by surgical diversion of the ipsilateral sciatic nerve, the amputated limbs regenerated mostly as spatula‐shaped outgrowths, which were longer those of normally innervated forelimbs. Such hyperinnervated regenerates exhibited less ossification of cartilage, or sometimes none at all. However, the regeneration of muscle was more extensive. That is, it reached more than half way along the regenerative outgrowth. Furthermore, denervation resulted in the absence of regeneration in all cases examined. Theses results clearly indicate that limb regeneration in Rana rugosa is dependent upon the degree of innervation, not only for the early stages of regeneration, but also for the growth and differentiation of the regenerative outgrowth. © 1992 Wiley‐Liss, Inc.
Gynogenetic mechanisms in polyploid hybrid salamanders
Authors: Elinson Richard P. , Bogart James P. , Licht Lawrence E. , Lowcock Leslie A. 
Published: June 2005

AbstractPolyploid hybrid salamanders of the genus Ambystoma tend to produce unreduced eggs. At higher temperatures (15°C), the sperm often contributes genetically, leading to tetraploid offspring from triploid mothers and pentaploid offspring from tetraploid mothers. At lower temperatures (5°C), the sperm nucleus usually is lost, and the eggs develop gynogenetically. We examined the cytology of fertilization at 5°C in order to determine the nature of the temperature‐dependent nuclear loss. As in other urodeles, fertilization is polyspermic. The sperm nuclei decondense to form pronuclei, and one sperm pronucleus associates with the egg pronucleus. At metaphase, a clump of chromatin appears along with the chromosomes at the metaphase plate. This chromatin clump fails to segregate at anaphase and is left at the site of the cleavage furrow. The chromatin clump is likely the discarded sperm pronucleus, so its loss is due to its failure to condense properly into chromosomes. © 1992 Wiley‐Liss, Inc.
Vitellogenin diversity in the perciformes
Authors: Lee K. B. H. , Lim E. H. , Lam T. J. , Ding J. L. 
Published: June 2005

AbstractVitellogenin variation was studied in 11 species of Perciformes encompassing the families Cichlidae, Serranidae, Lutjanidae, Centropomidae, and Eleotrididae. Despite the enormous morphological and ecological diversity that characterizes this order of teleosts, northern blot analysis revealed that the Oreochromis aureus vitellogenin gene probe will recognize estradiol‐induced vitellogenin messenger RNA of distant percoid relatives under stringent conditions of hybridization, suggesting that the vitellogenin gene is well conserved at least within the suborder Percoidei. Multiple vitellogenin gene transcripts were detected in the Cichlidae and these are correlated with the finding of multiple vitellogenin protein monomers in this family. In other families of non‐cichlid percoids, only one vitellogenin transcript, and, correspondingly, a single vitellogenin monomer was observed. No cross hybridization was, however, observed with a representative of the suborder Gobioidei. The pattern of protein bands seen in SDS‐PAGE also differed. The main features of vitellogenin protein diversity in the Perciformes are interfamily variability in size and subunit number. © 1992 Wiley‐Liss, Inc.
Spontaneous ovarian contractions in Fundulus heteroclitus
Authors: Bartley Susan M. , Kippax Jill B. , Taylor Malcolm H. 
Published: June 2005

AbstractSpontaneous contractions of Fundulus heteroclitus ovaries were observed and quantified using 2 methods. Contractions were measured as increases in intraovarian pressure in ovaries retained in the fish and as tension changes in ovaries removed from the fish, suspended in a smooth muscle bath, and connected to a force transducer. Spontaneous contractions were observed in approximately one‐half the ovaries tested, using both methods. The occurrence of spontaneous contractions was dependent on the reproductive stage of the fish, with more sexually mature fish exhibiting a greater incidence of spontaneous activity. The rate of contraction increased linearly with temperature over the range 20–35°C. Although the physiological significance of ovarian contractions in F. heteroclitus is unclear, possible functions include the facilitation of ovulation, egg release during spawning, and the movement of eggs or fluid within the ovary. © 1992 Wiley‐Liss, Inc.
Microfilaments, cell shape changes, and the formation of primary mesenchyme in sea urchin embryos
Authors: Anstrom John A. 
Published: June 2005

AbstractPrimary mesenchyme formation in sea urchin embryos occurs when a subset of epithelial cells of the blastula move from the epithelial layer into the blastocoel. The role of microfilaments in producing the cell shape changes that characterize this process, referred to as ingression, was investigated in this study. f‐Actin was localized by confocal microscopy using labeled phalloidin. The distribution of f‐actin was observed before, during, and after ingression and was correlated with cellular movements. Prior to the onset of ingression, staining became intense in the apical region of putative primary mesenchyme and disappeared following the completion of mesenchyme formation. The apical end of these cells constricted coincidentally with the appearance of the intensified staining, indicating that f‐actin may be involved in this constriction. In addition, papaverine, a smooth muscle cell relaxant that interferes with microfilament‐based contraction, and that was shown in this study to inhibit cytokinesis, diminished apical constriction and delayed ingression. Despite this interference with apical constriction, the basal surface of ingressing cells protruded into the blastocoel. It is suggested that apical constriction, while not necessary for ingression, does contribute to the efficient production of mesenchyme and that protrusion of the basal surface results from changes that occur independent of apical constriction. © 1992 Wiley‐Liss, Inc.
Fat body ovarian relationship in the garden lizard, Calotes versicolor (Daud.)
Authors: Shanbhag Bhagyashri A. , Prasad B. S. Krishna 
Published: June 2005

AbstractAbdominal fat body mass of Calotes versicolor showed annual changes that were universal related to the changes in ovarian somatic (GSI) and hepatosomatic (HSI) indices. Fat bodies were absent in late breeding phase (June–August). Thirty day fatectomy (FBX) during prebreeding phase significantly reduced GSI, HSI, and total number of extrastromal follicles; also, recruitement of vitellogenic follicles was arrested and ateretic follicles increased. The FBX during postbreeding phase had no such effect, whereas in 30 day ovariectomised (OvX) lizards in prebreeding phase fat body mass significantly increased but HSI decreased. However, in lizards in prebreeding phase, E2 caused a significant decrease in fat body mass and an increase in HSI, while during the postbreeding phase there was a significant increase in HSI but the fat bodies were not affected.The above findings suggest that the development of the first clutch of vitellogenic follicles in the lizard utilises lipids stored in the fat bodies and that the growth of the subsequent clutches of vitellogenic follicles is met through the intake of food, which is abundant in the latter part of the breeding phase. The fat bodies are not needed for the growth of previtellogenic follicles. The fact that lipolytic action of E2 occurs only during the breeding phase suggests that responsiveness of the fat bodies to the steroid is related to the reproductive phase and that during postbreeding phase of the lizard they become refractory to E2. © 1992 Wiley‐Liss, Inc.
Influence of a capacitation period on human sperm acrosome loss
Authors: Holden Carol A. , Trounson Alan O. 
Published: June 2005

AbstractThe present study investigates whether a 5 hour capacitation period modifies the ability of human spermatozoa to undergo induced acrosomal loss. Human sperm acrosomal loss was induced by treatment with either the calcium ionophore A23187, low concentrations of the phospholipid dilauroylphosphatidylcholine (PC12), or 2 hours incubation in conditioned medium prepared from human cumulus cells (CM/CC). The use of a dual staining method (FITC‐ConA and Hoechst 33258) for simultaneous assessment of acrosomal status and viability demonstrated that induction of acrosomal loss with calcium ionophore was not dependent on a capacitation period. A short (5 hour) incubation period was not sufficient to induce acrosomal loss with CM/CC above spontaneous acrosome reaction rates in medium alone. A significant capacitation‐dependent increase (P < 0.05) in acrosomal loss was observed when human spermatozoa were incubated with PC12. Induction of acrosomal loss of capacitated human spermatozoa with PC12 therefore provides a simple assay for the simultaneous assessment of human sperm capacitation and the acrosome reaction in vitro. © 1992 Wiley‐Liss, Inc.
Structure of the vaginal plugs generated by normal rats and by rats with partially removed seminal vesicles
Authors: Carballada R. , Esponda P. 
Published: June 2005

AbstractNormal male rats generate vaginal plugs that appear to be firmly apposed to the vagino‐cervical junction and permit a large number of spermatozoa to reach the uterus. A few spermatozoa form entangled masses inside these plugs, as revealed by light microscopy. Males in which the seminal vesicles have been partially removed produce plugs that are smaller and softer than those generated by normal males, and the plugs display a cup‐like structure at the proximal end. The cup‐like structure is completely filled with spermatozoa that exhibit a characteristic arrangement in relation to the plug material. In this situation, the number of spermatozoa that reach the uterus is very much reduced. Experiments were also carried out to explore the restoration of sperm transport by addition of a vaginal plug. Such experiments involved successive matings of individual females with a seminal vesicle‐deprived male and with a vasectomized male (which generated the plug) and also the intravaginal injection of seminal vesicle secretions after mating with a seminal vesicle‐deprived male. In none of the experimental situations was transport of spermatozoa to the uterus restored, and the plug consisted of a large quantity of trapped spermatozoa inside a mass of coagulated proteins. The results suggest that the structure of the plug depends on the amount of seminal vesicle secretion present in the ejaculate and that the vaginal plug must be formed immediately after deposition of the sperm if spermatozoa are to reach the uterus. © 1993 Wiley‐Liss, Inc.