bluuebunny/crossref_metadata_2025_split huggingface dataset:
An in vitro culture system for studying vitellogenin uptake into ovarian follicles of the rainbow trout, Salmo gairdneri
Authors: Tyler C. R. , Sumpter J. P. , Bromage N. R. 
Published: June 2005

AbstractThe development of a short‐term culture system to study vitellogenin (VTG) sequestration in vitro into vitellogenic follicles of the rainbow trout, Salmo gairdneri, is described. The outer epithelial cell layer of the trout follicle restricted VTG uptake considerably and its removal was a prerequisite to study VTG uptake in vitro. Vitellogenic follicles divested of the surface epithelium sequestered VTG at rates of up to 170 ng·mm2 follicle surface−1·h−1 (ng·mm−2·h−1). Uptake of VTG over an 8 h period of incubation was linear.Increasing the titre of VTG in the culture medium induced greater rates of sequestration in a dose‐dependent manner; follicles cultured in medium containing 45 mg VTG·ml−1 sequestered 170 ± 9ng·mm−2·h−1 whereas those follicles cultured in medium containing 2 mg·ml−1 only incorporated 6 ± 0.5 ng·mm−2·h−1.Uptake of VTG was temperature dependent with higher temperatures inducing higher levels of incorporation. Sequestration of VTG persisted at temperatures below 5°C, showing that the uptake mechanisms are adapted to low temperatures in this species.Size of follicles also had a considerable bearing on the rate of VTG sequestration; follicles of less than 1 mm diameter (pre‐vitellogenic follicles) did not sequester VTG in amounts that were detectable. All follicles measuring 1 mm or greater in diameter sequestered VTG. As the follicles increased in size between approximately 1 and 3 mm in diameter there was an increase in both the total amount of VTG sequestered and the rate of uptake of VTG relative to surface area. Limited data suggested that in follicles closely approaching ovulation the rate of VTG sequestration was considerably reduced.
Purification and some properties of alkaline phosphatase from the hepatopancreas of the shrimp Penaeus japonicus (Crustacea: Decapoda)
Authors: Chuang Nin‐Nin , Shih Su‐Ling 
Published: June 2005

AbstractAlkaline phosphatase purified from the hepatopancreas of Penaeus japonicus is stable to heating at 65°C for 5 min. The specific activity of the purified enzyme is 25,000 units/mg of protein. After polyacrylamide gel electrophoresis under denaturing conditions, the purified alkaline phosphatase from shrimp was found to consist of deglycosylated monomers of Mr 40,000 and to retain the attachment sites for both sialic acid and phosphatidylinositol. The alkaline phosphatase from shrimp has an isoelectric point (pI) of 7.6 and becomes more alkaline after the removal of either sialic acid or phosphatidylinositol residues.
Regulation of mouse preimplantation development: Inhibitory effect of genistein, an inhibitor of tyrosine protein phosphorylation, on cleavage of one‐cell embryos
Authors: Besterman Brian , Schultz Richard M. 
Published: June 2005

AbstractWe investigated the effects of genistein, an inhibitor of tyrosine protein phosphorylation, on mouse 1‐cell embryos, since in response to mitogenic stimuli tyrosine protein phosphorylation in somatic cells is implicated in initiation of DNA synthesis. Genistein inhibits cleavage of 1‐cell embryos in a concentration‐dependent and reversible manner; biochanin A, which is a less potent inhibitor of tyrosine protein phosphorylation, is a less potent inhibitor of cell cleavage. Genistein does not inhibit [35S]methionine incorporation, but does inhibit [3H]thymidine incorporation. Consistent with genistein's ability to inhibit cleavage by inhibiting DNA synthesis is that the loss of genistein's ability to inhibit cleavage corresponds with exit of the 1‐cell embryos from S phase. Genistein is likely to inhibit tyrosine protein phosphorylation in situ, since it reduces by 80% the relative amount of [32P]phosphotyrosine present in 1‐cell embryos; genistein does not inhibit either [32P]orthophosphate uptake or incorporation. As anticipated, genistein has little effect on inhibiting changes in the pattern of phosphoprotein synthesis during the first cell cycle, since tyrosine protein phosphorylation constitutes a small percentage of total protein phosphorylation. Alkalai treatment of [32P]radiolabeled phosphoproteins transferred to Immobilon reveals a base‐resistant set of phosphoproteins of Mr = 32,000 that displays cell‐cycle changes in phosphorylation. Although these properties suggest that these phosphoproteins may be related to the p34cdc2 protein kinase, phosphoamino acid analysis of [32P]radiolabeled phosphoproteins reveals that they are not enriched for phosphotyrosine; the inactive form p34cdc2 protein kinase contains a high level of phosphotyrosine. Results of these experiments suggest that tyrosine protein phosphorylation in response to the fertilizing sperm may be involved in initiating DNA synthesis in the 1‐cell embryo, as well as converting a meiotic cell cycle to a mitotic one.
Polarization of blastomeres in the cleaving rabbit embryo
Authors: Ziomek Carol A. , Chatot Clare L. , Manes Cole 
Published: June 2005

AbstractCellular polarization is believed to be a crucial event in the differentiative divergence of the two cell lineages leading to the blastocyst in rodent embryos. This study was undertaken to determine if rabbit embryos exhibited cellular polarization prior to blastocyst formation and to define the embryonic stage at which polarization was first apparent. Polarity was assayed by observation of the pattern of binding of FITC‐Con A to dissociated blastomeres from three stages of rabbit embryos. Scanning electron microscopy on the dissociated cells confirmed the fluorescence results. Fifty‐one percent of blastomeres in 38‐ to 66‐cell rabbit embryos exhibited an intense pole of FITC‐Con A binding and a single pole of microvilli. Only 2% of blastomeres at the 17‐ to 34‐cell stage were similarly polarized and none were polarized at the 8‐ to 16‐cell stage. In addition, during attempts to remove the mucin coat and zona pellucida from the rabbit embryos prior to their dissociation, it was found that the protease sensitivity of these coats also changed at the 38‐ to 66‐cell stage. Prior to this time, although the mucin coat disappeared after 30 min in 0.5% pronase, the zona required approximately 1.5–2.5 hr in pronase for even partial removal. At the 38‐ to 66‐cell stage, pronase dissolved the mucin coat within 10 min and the zona pellucida within 20 min. The zona was resistant to 0.1% proteinase K at all stages examined.
Sex‐specific embryonic mortality during concurrent pregnancy and lactation in house mice
Authors: Krackow Sven 
Published: June 2005

AbstractTo evaluate the importance of lactational stress for sex ratio manipulation in postpartum inseminated house mice, 163 sexually inexperienced male and female BALB/c ABom inbred mice were mated and stud males were removed the day following the initial parturition. Randomly chosen dams were allowed to suckle their young for either one or 14 or 21 days. The results showed that two weeks of lactation enhance the incidence of total abortion of the litter conceived postpartum. If lactation continued another week, dams which gave birth to a second litter lost relatively more embryos during uterine development and the percentage of lost embryos was increased by the number of pups suckled. Among these dams, the number of embryos lost in utero correlated positively with viable litter sex ratios (percentage male pups) at second parturition, indicating that lactational stress enhances embryonic mortality and that this additional mortality predominantly affects female embryos.
Anaerobiosis and the regulation of glycolytic enzymes in the sea anemone Metridium senile
Authors: Michaelidis Basile , Storey Kenneth B. 
Published: June 2005

AbstractThe regulation of glycolytic enzymes during anaerobiosis was examined in three tissues, muscular body wall, tentacles, and mesoglia, of the sea anemcme Metridium senile. Anoxia‐induced stable modifications of the activities or kinetic and regulatory properties of glycogen phosphorylase, phosphofructokinase (PFK), and pyruvate kinase (PK), were detected. In the two muscular tissues, anoxia had the greatest effect on the properties of PFK; for PFK in body wall So F6P decreased, Km ATP increased, I50 PEP increased, and Ka values for AMP and inorganic phosphate increased, compared to PFK in aerobic muscle. In addition, levels of the PFK activator fructose‐2,6‐bisphosphate decreased sharply after 21 hours of anoxia LO amounts 19, 48, and 39% of aerobic control values in body wall, tentacles, and mesoglia, respectively. Anoxia exposure had fewer effects on the properties of PK, and primary control of the enzyme in muscular tissues may reside with allosteric effectors, F1, 6P2 activation, and strong L‐alanine inhibition. PK in mesoglia, by contrast, was virtually unaffected by allosteric modifiers but shcwed a 4‐fold decrease in S0.5 PEP in anoxia. The results suggest that changes in glycolytic function during anaerobiosis in sea anemones are mediated by covalent modifications of the regulatory enzymes as well as changes in the levels of F2,6P2 and other metabolite effectors of the enzymes.
Chemical detection of predators by a lizard, the broad‐headed skink (Eumeces laticeps)
Authors: Cooper William E. 
Published: June 2005

AbstractThe scincid lizard Eumeces laticeps is shown experimentally 1) to be capable of detecting integumentary chemical stimuli from two congeneric species of snakes that are sympatric predators of lizards and 2) to discriminate these chemical stimuli from similar ones derived from a sympatric snake that does not eat lizards and from a common insect food species. The experimental technique employed in this study, i.e., presentation of odorants on cotton‐tipped applicators, allows rapid assessment of responses to predator odors and is suitable for a survey of these responses in a wide variety of lizards. The skinks showed significantly higher tongue‐flicking rates in response to odors of snake predators and food odors (cricket) than to odors of a snake that does not eat lizards and an odorless control. Tongue‐flick attack score, a measure of response strength to chemical stimuli from food, was much greater for cricket stimuli than for the predator stimuli. Significantly more lizards bit applicators bearing cricket stimuli than bit applicators bearing any of the other stimuli. After biting applicators bearing predator odors, the lizards quickly released. In contrast, they frequently maintained a grasp after biting applicators bearing cricket odors. A few preliminary speculations are made regarding ecological factors that may affect responsiveness by lizards to predator odors.
Rat renal papillary tissue explants survive and produce epithelial monolayers in culture media made hyperosmotic with sodium chloride and urea
Authors: Woolverton W. S. , Githens S. , O'Dell‐Smith R. , Bartell C. K. 
Published: June 2005

AbstractThe capacity of papillary cells to adapt to elevated osmotic concentrations is unusual among mammalian cells. This capacity was evaluated by using primary tissue culture. Viability and growth of cells in rat renal papillary tissue explants were assessed after culture in media adjusted with urea and sodium chloride to various osmotic concentrations between 300 and 1,500 mOsm/kg water. The survival of cells, including cells resembling those of the collecting ducts and the loop of Henle, was greatest in medium adjusted to 1,000 mOsm with equiosmolar amounts of the two solutes. At 1,500 mOsm only cuboidal tubular epithelium resembling collecting duct epithelial cells survived. In contrast, cells of cortical tissue survived and grew at 300 and 640 mOsm, but not at 1,000 mOsm or above. Epithelial monolayers appeared to proliferate from collecting ducts and spread over the surface of the explants as well as onto the glass surface in the culture dish. Epithelial growth of medullary tissue was most rapid at 300 mOsm and was slower at 700 and 1,000 mOsm. Monolayers did not form at 1,500 mOsm; however, epithelial overgrowth of explants did occur. Hydropenia in the donor animal did not significantly affect the viability or growth of cultured papillary tissue. Explants cultured for 5 days at 300 mOsm followed by a stepwise increase in medium osmolality to 1,100 or 1,500 mOsm and cultured for 3 more days showed low or no survival whereas explants cultured at 700 mOsm survived such increases. Explants cultured for 5 days at 1,500 mOsm survived and grew monolayers when lowered to 300 mOsm. Poor viability and no epithelial proliferation were observed in explants cultured in medium adjusted to 900 mOsm with either urea or sodium chloride alone, suggesting that a mixture of the two solutes in the extracellular space, as found in vivo, may be essential in achieving elevated osmolalities.
Ultrastructural evidence for an association between an oviductal glycoprotein and the zona pellucida of the golden hamster egg
Authors: Abe Hiroyuki , Oikawa Taneaki 
Published: June 2005

AbstractThe ultrastructural localization of an oviductal glycoprotein, designated ZP‐0 in golden hamster oviductal eggs, was investigated by immunolabeling methods using a monoclonal antibody (C11E8). Immunofluorescence staining showed that C11E8 specifically reacted with the zona pellucida of the oviductal egg but not the ovarian egg. In an immunoelectron microscopic study applying the protein‐A gold technique, gold particles were distributed throughout the zona pellucida of the oviductal eggs and were also associated with the perivitelline matrix. Structures within the eggs and cumulus cells did not react with C11E8. Quantitative evaluations of the degree of labeling demonstrated that a large number of gold particles was bound to the zone pellucida, especially in the middle layer. Moreover, in bovine testicular hyaluronidase‐treated eggs the density of labeling decreased only in the outer third of the zona pellucida. These results show that ZP‐0 was associated with the zona pellucida and perivitelline matrix of the golden hamster egg after ovulation and suggest that there are topographical differences in the binding activity of ZP‐0 to the zona pellucida. In addition, the decrease in labeling density of ZP‐0 induced by hyaluronidase appears to be related to changes in the properties of the outer layer of the zona pellucida.
Distribution of hyaluronidase activity in the tissues of the normal and the lens‐regenerating iris in the newt
Authors: Zalik Sara E. , Dimitrov Eva 
Published: June 2005

AbstractDuring lens regeneration in the newt the synthesis of hyaluronic acid increases as iris cells undergo dedifferentiation, and decreases during the redifferentiation phase. In contrast, the levels of hyaluronidase activity which are high in the normal iris remain constant during regeneration (Kulyk et al: Exp. Cell Res., 172:180–191, 1987). We determined whether differential changes in hyaluronidase activity occurred within discrete cell populations of the iris during lens regeneration. In the normal iris hyaluronidase activity was dominant in the iris epithelium, with low levels of enzyme activity being present in the iris stroma. Regionally within the iris, highest levels of enzyme activity were found in the ciliary iris, while lower levels were found in the pupillary iris. Results suggest that a circumferential gradient of hyaluronidase activity decreasing from the dorsal to the ventral regions is present within the iris; superimposed within this gradient, a meridional gradient of enzyme activity increasing from the pupillary to the ciliary region exists. The levels of hyaluronidase activity increase in the dorsal pupillary iris during redifferentiation stages. This activity could be involved in the removal of the hyaluronic acid that is produced during dedifferentiation of the regenerating iris.
Studies on the decondensation of human, mouse, and bull sperm nuclei by heparin and other polyanions
Authors: Jager S. , Wijchman J. , Kremer J. 
Published: June 2005

AbstractWe report heparin‐induced decondensation of human, mouse, and bull sperm nuclei. Decondensation did not occur if the spermatozoa were intact but only if the membranes were severely damaged by freezing and thawing or by treatment with a detergent. If a disulphide bond reducing agent (thiol) was absent, decondensation of human sperm nuclei was usually a relatively slow process, with large interindividual variation. Mouse and bull sperm nuclei did not decondense in the absence of a thiol. With a thiol relatively low concentrations of heparin induced a rapid decondensation of the sperm nuclei of all three species. The decondensation activity was not specific for heparin; other polyanions were also active, with heparin being the most effective compound.It is supposed that heparin and other polyanions induce sperm nuclear decondensation because they deplete protamines from the chromatin. Thus the negatively charged phosphate groups of the DNA are no longer opposed by positively charged protamines. Consequently the mutual repulsion of unopposed phosphate groups causes the DNA molecules to stretch, which results in an increase of the sperm nuclear volume. Since heparin and other polyanions induce decondensation under physiological pH and temperature, polyanions might also be active in the oocyte.
Release of metaphase arrest by partial inhibition of protein synthesis in blue mussel oocytes
Authors: Dubé Francois , Dufresne Louise 
Published: June 2005

AbstractIn the blue mussel Mytilus edulis, shed oocytes are arrested at metaphase I of meiosis until fertilization. In this study, the mechanisms involved for maintaining the oocytes in metaphase were investigated. Analysis of 35‐methionine‐labelled proteins separated by 1D SDS‐PAGE reveals that two protein bands of apparent MW of 50 and 54 kDa periodically appear and disappear during meiotic and mitotic cycles. Moreover, the 50 kDa protein band, clearly detected in unfertilized oocytes, is seen to disappear within 15 min after fertilization. Unfertilized or fertilized oocytes treated with emetine have a protein synthesis rate reduced to less than half the normal rate observed in the untreated cells. Addition of this protein synthesis inhibitor at various times after fertilization inhibits the normal progression through the cell cycles. However, emetine added to unfertilized oocytes induces the completion of first meiotic maturation, polar body extrusion, and the decondensation of chromosomes which form one or two large pronuclei. This process is accompanied by DNA synthesis, and is preceded by the early disappearance of the 50 kDa protein band, seen to cycle after fertilization. These results indicate that metaphase arrest, in mussel oocytes, requires the continuous synthesis of short‐lived proteins, the destruction of which is sufficient to induce meiosis resumption followed by DNA synthesis.
Sex‐determining potencies vary among female incubation temperatures in a turtle
Authors: Bull J. J. , Wibbels T. , Crews D. 
Published: June 2005

AbstractReptiles whose sex is determined by incubation temperature typically exhibit all‐male or all‐female sex ratios over a wide range of incubation temperatures. The question arises as to whether the various all‐female temperatures (or the various all‐male temperatures) are equivalent in their “potency,” or capacity to effect female determination. In map turtles, warm incubation temperatures produce all females and cool ones produce all males. We compared sex determining potencies of two all‐female temperatures, 31°C and 32.5°C, by incubating eggs first at a male‐producing temperature (26°C) and then shifting them to the warm temperatures. The resulting sex ratio was significantly more male biased in the 26°C→31°C shift than in the 26°C→32.5°C shift, indicating that 32.5°C has the greater female potency. These results point to the possibility that sex determination depends on a quantitative rather than qualitative level of gene expression.
Expression of the Axd (axial defects) mutation in the mouse is insensitive to retinoic acid at low dose
Authors: Haviland Martha B. , Essien Francine B. 
Published: June 2005

AbstractThe Axd mutation in the mouse acts by an unknown mechanism to cause lum‐bosacral open neural tube defects and a variety of tail anomalies. Retinoic acid (RA) plays a number of different physiological and developmental roles and has been shown to affect neurulation in mice and other species. Indeed, reports have shown that this biologically active compound (or its metabolites) at low dose can alter the incidence of neural tube defects (NTD) in curly‐tail (ct), splotch (Sp), and delayed splotch (Spd) mice, strains that are genetically predisposed to such abnormalities. The aim of the present study was to determine if RA administered under similar conditions would affect the penetrance or expression of the Axd mutation or survival of Axd homozygotes. Axd/+ and +/+ dams were exposed to RA intraperitoneally (5 mg/kg) on D9 postcoitus. No difference in incidence or extent of neural tube defects or other axial anomalies was detected among embryos of Axd/+ dams given RA compared with those administered vehicle only. This finding is consistent with the diversity of gene‐controlled steps required for neurulation and the differing sensitivities of specific mutants to rescue by extrinsic agents.
Stimulation of 35S‐sulfate uptake by mammalian insulin‐like growth factors I and II in cultured cartilages of the Japanese eel, Anguilla japonica
Authors: Duan Cunming , Hirano Tetsuya 
Published: June 2005

AbstractEffects of mammalian insulin‐like growth factors I and II (IGF‐I and II) on 35S‐sulfate uptake by the branchial cartilage of the eel were examined in vitro. Addition of bovine IGF‐I to the medium stimulated sulfate uptake by the cartilage from hypophysectomized eels in a dose‐dependent manner (10–1,000 ng/ml). The cartilages from intact eels responded to IGF‐I similarly. Rat IGF‐II was about 50 times less potent than bovine IGF‐I in stimulating the sulfate uptake by cartilages from intact eels. These results show that sulfate uptake by eel cartilage is stimulated by a mammalian IGF‐I‐like principle and raise the possibility of regulation by a similar principle in teleosts.
Enhancement of aster‐induced furrowing activity by a factor associated with the nucleus
Authors: Rappaport R. 
Published: June 2005

AbstractThe purpose of this investigation was to determine whether asters that develop in the absence of nuclear material have the normal ability to cause surface contraction and furrows. Experimental cells were confined in silicone rubber tubes with flattened lumens. The lumen roof was thin enough to permit deformation or perforation of the contained eggs by pressure with glass tools. When a flattened, elongate egg was perforated at its midpoint with a relatively large glass ball before nuclear membrane breakdown, the positions of the asters and nucleus were determined by chance. When the nucleus and asters were on the same side of the perforation, normal furrows developed. When the nucleus was separated from the aster pair, only ephemeral furrows developed. When the asters straddled the perforation so that only one of the asters was associated with the nucleus, ephemeral furrowing activity was most pronounced at the nucleated end of the cell.The asters of cells that were kneaded before insertion in the flattened capillary were often farther apart than normal, and the nucleus was more closely associated with one aster than the other. Constrictions developed in the planes of both asters, but only those associated with the aster closest to the nucleus persisted to produce two aster‐containing cells, only one of which contained a nucleus. In subsequent division cycles, asters reproduced and developed in both cells, but only the progeny of the nucleated cell formed permanent furrows. The normal furrow‐inducing capacity of the asters appears to depend in part on the presence of a factor associated with the nucleus.