bluuebunny/crossref_metadata_2025_split huggingface dataset:
The expression of nuclear lamin A and C epitopes is regulated by the developmental stage of the cytoplasm in mouse oocytes or embryos
Authors: Prather R. S. , Kubiak J. , Maul G. G. , First N. L. , Schatten G. 
Published: June 2005

AbstractThe cytoplasmic regulation of changes of nuclear lamin antigens was examined by transferring 16‐cell stage blastomeres into mouse oocytes. Sixteen‐cell stage blastomeres were transferred to either pronuclear eggs, enucleated pronuclear eggs or metaphase II oocytes, which were subsequently activated. Pronuclei react with a monoclonal antibody to A/C lamins (J9), whereas nuclei from 16‐cell stage blastomeres do not react with J9. However, after transfer of 16‐cell stage nuclei to activated metaphase II oocytes, the transferred nuclei acquire the antigen. This is in contrast to 16‐cell nuclei that were transferred to intact or enucleated pronuclear eggs; i.e., the nuclei only faintly acquired the A/C epitope. These results suggest that the developmental stage of the cytoplasm regulates the exposure of nuclear lamina epitopes, perhaps by limiting the supply of lamin A/C in the oocyte or because nuclear lamina assembly can only occur at the telophase transition. Furthermore, it appears that there is some exchange of the A/C epitope between (pro)nuclei within the same cell but that the majority of the A/C lamin epitope can be removed from a cell with (pro)nuclear removal.
Drosophila alcohol dehydrogenase: A novel reporter gene for use in mammalian embryos
Authors: Nielsen Loretta L. , Pedersen Roger A. 
Published: June 2005

AbstractA reporter gene construct containing the Drosophila alcohol dehydrogenase (ADH) gene under regulation of the Rous sarcoma virus long terminal repeat (RSV LTR) was microinjected into mouse zygote pronuclei. ADH activity after injection of the RSV‐ADH construct was visualized in cultured embryos by means of a simple histochemical enzyme assay. The RSV LTR was an efficient promoter that led to abundant ADH activity at all stages of preimplantation development. There was a high incidence of mosaicism among stained embryos.
Haemolymph protein as a source for free amino acid accumulation in the pulmonate Helisoma trivolvis during hypertonic stress
Authors: Matsushima Osamu , Khan Hamid R. , Saleuddin A. S. M. 
Published: June 2005

AbstractThe metabolic origin of hypertonically induced intracellular free amino acid (FAA) accumulation in the freshwater pulmonate snail, Helisoma trivolvis was examined. The changes in FAA patterns in response to hypertonic stress were common in haemolymph and tissues; but FAA concentrations were much lower in the former. Transport experiments with 3H‐glycine and detection by high‐performance liquid chromatography (HPLC) showed that isolated kidneys in vitro took up FAA against a concentration gradient. Fluorography demonstrated that injected 14C‐amino acids were incorporated into haemolymph protein significantly less in hypertonically stressed snails than in control snails. These results suggest that, in H. trivolvis, reduction in synthesis of haemolymph protein and FAA transport from haemolymph into cells contribute to intracellular FAA increase during the initial stage of hypertonic stress.
Energy consumption in the perfused gills of the euryhaline crab Eriocheir sinensis [H. Miln. Edw. ] adapted to freshwater
Authors: Welcomme L. , Devos P. 
Published: June 2005

AbstractThe euryhaline crab Eriocheir sinensis adapted to freshwater shows an ion transporting‐type epithelium in the three posterior gills and a respiratory‐type epithelium in the three anterior gills. When they are perfused in freshwater conditions, there is an increased transport of ions principally in the posterior gills.We also measure an increased degradation of the branchial glycogen. This polysaccharide is present in an extraepithelial lamina located in the hemal space of the lamellae. Its localization outside the ion‐transporting epithelium and its higher consumption by the posterior gills submitted to hypo‐osmotic conditions suggest a well‐suited glucose transport mechanism through their epithelial membrane. Accordingly, the uptake of glucose by the epithelial cells is slightly higher in the posterior gills as compared with the anterior.
Response of hepatic thyroxine 5′‐deiodinase of rainbow trout, Oncorhynchus mykiss, to chronic ingestion of 3,5,3′‐triiodo‐L‐thyronine
Authors: Eales J. G. , Finnson K. R. 
Published: June 2005

AbstractRainbow trout held at 6.5°C were fed food supplemented with 12 ppm T3 (3,5,3′‐triiodo‐L‐thyronine). By 2 weeks, plasma T3 had increased from 3.7 ng/ml (controls) to 12 ng/ml and stayed at that level for 12 weeks with minor change in plasma L‐thyroxine (T4). The hepatic microsomal 5′‐deiodinase (5′‐D) activity (Vmax fell to 25% of control values by 2 weeks and by 12 weeks was undetectable. Trout were also fed the T3‐supplemented food for 6 weeks and then reverted to control food (0 ppm T3) for 6 weeks. After 2 weeks reversion, plasma T3 was 48% lower and 5′‐D Vmax 78% lower than for control fish fed 0 ppm T3 throughout; after 6 weeks reversion, plasma T3 had recovered, but 5′‐D had regained only 58% of control values. These data confirm that exogenous T3 suppresses endogenous T3 production and suggest extrathyroidal autoregulation of T3 production. Furthermore, even 6 weeks after T3 treatment had ceased, hepatic 5′‐D was subnormal, indicating development of T3 dependency.
Phosphoenolpyruvate carboxykinase from ribbed mussel gill tissue: Reactivity with metal ions, kinetics, and action of 3‐mercaptopicolinic acid
Authors: Harlocker Susan L. , Kapper Martin A. , Greenwalt Dale E. , Bishop Stephen H. 
Published: June 2005

AbstractPhosphoenolpyruvate carboxykinase (E.C. 4.1.32) from ribbed mussel gill cytosol exists as a monomer with Mr 70,000. Low levels of Mn2+ or Zn2+ were required for activity when assayed at high physiological Mg2+ levels. Mg2+ alone would not activate the enzyme. Optimal activity was observed at pH 6.6. The apparent Kms for phosphoenolpyruvate (PEP) and NaHCO3 were 396 μM and 13 mM, respectively, when assayed at pH 6.8 in the presence of 1 mM Mn2+, 1 mM Mg2+, and 1.5 mM IDP. GDP (Kmapp 24 μM) and IDP (Kmapp 46 μM) were both reactive; other nucleoside diphosphates were not. Under standard assay conditions at pH 6.8, the reaction was freely reversible with the rate of PEP carboxylation two to three times the rate of OAA decarboxylation. When assayed in the PEP synthesizing direction at pH 6.8 with 2 mM Mn2+ and Mg2+, the apparent Kms for GTP and OAA were 55 μM and 24 μM, respectively. Chloride ion was inhibitory (I50 120 mM); 3‐mercaptopicolinic acid (MPA) and 3‐aminopicolinic acid (APA) were competitive inhibitors with respect to PEP and noncompetitive with respect to IDP. MPA was a more effective inhibitor (Kiapp 8–34 μM) than APA (Kiapp 250–500 μM). Aminooxyacetate and N‐butylmalonate (BMA) were not inhibitory and hydroxymalonate was slightly inhibitory (Kiapp 15 mM). ATP showed mixed competitive inhibition with respect to PEP (Kiapp 0.54 mM); inhibition by ATP was not reversed by L‐alanine. Experiments employing BMA and MPA with gill tissue pieces subjected to hyperosmotic stress indicated that the PEPCK reaction in gill tissue was not significantly involved in the regulation of carbon flow for the synthesis of L‐alanine as an intracellular osmotic buffer.
Regulation of parthenogenetic activation of metaphase II mouse oocytes by pyruvate
Authors: Kim Haekwon , Schuetz Allen W. 
Published: June 2005

AbstractWe report that parthenogenetic activation (pronuclear formation) is induced during in vitro culture of recently ovulated (13–14 hr post‐hCG) mouse oocytes in pyruvate deficient medium. Pronuclear formation occurred when oocytes were cultured in medium containing 1/10X (Pyr−) or lower concentrations of pyruvate but failed to occur either in oocytes cultured in the presence of 0.47 mM (1X, Pyr+) or 1/2X pyruvate or in oocytes cultured in the absence of pyruvate but with cumulus cells. Pronuclear formation was evident within 8 hr of culture and completed by 16 hr and remained intact during continuous culture in Pyr− medium. Transfer of pronuclear oocytes to Pyr+ medium resulted in pronuclear membrane disassembly and further parthenogenetic development. A similar incidence of parthenogenetic activation occurred when recently ovulated oocytes were cultured in the presence of cycloheximide but not following ethanol or hyaluronidase treatment. However, both ethanol and hyaluronidase induced pronuclear formation in in vivo aged oocytes. Results suggest that the type of activation induced varies with the age of the oocyte and the nature of the stimulus. Amino acid uptake ([35S]methionine) by oocytes was unaffected by Pyr− culture whereas incorporation into protein was markedly inhibited. Gel electrophoretic analysis of labeled egg extracts revealed a marked inhibition of egg protein synthesis after 4 hr of culture in Pyr−. The occurrence of a cortical reaction was monitored by binding of fluorescent labeled lectin to the oocyte surface. A cortical reaction occurred in response to ethanol treatment of freshly ovulated and in vivo aged oocytes cultured in Pyr+ medium but not in pronucleate oocytes induced by Pyr− culture. Suppression of ethanol‐induced cortical reaction by Pyr− culture was restored following transfer of oocytes to Pyr+ medium. Results demonstrate that nuclear events as well as plasma membrane events can be simply regulated by controlling the amount of energy substrate available to the germ cell. Effects of Pyr− culture in inducing pronuclear formation appear to be mediated in a large part via inhibition of protein synthesis.
Growth of mouse embryos implanted in the subcutaneous tissue of recipient mice
Authors: Bevilacqua Estela Maris A. F. , Abrahamsohn Paulo A. 
Published: June 2005

AbstractEight‐days‐old mouse embryos were transferred to the subcutaneous tissue of the dorsal skin of host mice. A high rate of embryos developed into hemorrhagic (HN) or nonhemorrhagic nodules (NHN). The latter had trophoblastic cells as well as embryoblastic derivatives whereas HN contained almost only trophoblastic cells.At least two kinds of trophoblastic cells were present in NHN: small cells and large cells similar to trophoblastic giant cells. In HN most trophoblastic cells arranged themselves into a network whose meshes contained host blood. Although embryoblastic derivatives such as endoderm and Reichert's membrane were apposed to host connective tissue cells, trophoblastic cells were always surrounded by collagen fibrils or by a layer of an amorphous material.
Plasma levels of glucose, ketone bodies, lactate, and alanine in the vascular supply to and from the brain of the adult American bullfrog (Rana catesbeiana)
Authors: Gibbs Scott R. , deRoos Roger M. 
Published: June 2005

AbstractSerial, paired blood samples were collected via cannulae chronically placed in the common carotid artery (A) to and the internal jugular vein (V) from the brain of the fasted adult American bullfrog (Rana catesbeiana). Plasma glucose, β‐hydroxybutyrate, acetoacetate, lactate, and alanine levels were measured by standard enzymatic procedures. Cannula failure ended sampling after 1–2 days in most animals. The common carotid artery plasma metabolite levels were greatest at the time of surgery and subsequently declined to relatively stable levels. The summarized data indicated glucose uptake and alanine release by the brain, but no significant β‐hydroxybutyrate or lactate A‐V percentage changes. Initially, acetoacetate levels also were measured, but were discontinued in favor of continued β‐hydroxybutyrate determinations when no significant A‐V percentage changes occurred. Separate analysis of the metabolite levels during the surgery and recovery period (⩽ 24 hr) and the “normal” under the experimental conditions period (> 24 hr) revealed that summarizing the data masked important A‐V percentage changes during the two different physiological conditions. Glucose was the only metabolite extracted by the brain during the ⩽ 24 hr period of elevated and subsequently declining metabolite levels. In contrast, glucose uptake did not occur during the > 24 hr period of stable levels, but there was lactate release.If the bullfrog brain stores substantial glycogen as do the other ectothermic vertebrates studied, glucose uptake when plasma levels are elevated, for example after feeding, may serve both to fuel the brain and to replenish endogenous glycogen reserves that may be mobilized to provide glucose for the brain after plasma glucose levels return to normal. Assuming that mammalian and bullfrog metabolic pathways are the same, the release of lactate and alanine by the brain, possibly to remove excess pyruvate and to regenerate NAD+, is consistent with this hypothesis. It remains to be determined for how long endogenous energy sources alone can support the bullfrog brain, and if plasma glucose, ketones, and/or other energy sources are extracted as endogenous brain fuels become exhausted.
Subcellular localization of two glutamine‐dependent carbamoyl‐phosphate synthetases and related enzymes in liver of Micropterus salmoides (largemouth bass) and properties of isolated liver mitochondria: Comparative relationship with elasmobranchs
Authors: Cao Xueying , Kemp Jon R. , Anderson Paul M. 
Published: June 2005

AbstractTwo different glutamine‐dependent carbamoyl‐phosphate synthetase (CPSase) activities are preset in tissues of Squalus acanthias (spiny dogfish shark, a representative elasmobranch) (Anderson, Biochem. J. 261:523–529, 1989). CPSase III (acetylglutamate‐dependent) activity is present in liver mitochondria; the function of this enzyme is related to urea synthesis for the purpose of osmoregulation, and the properties are analogous to the classical ammonia and acetylglutamate‐dependent CPSase I in liver mitochondria of ureotelic species (except that the nitrogen‐donating substrate is glutamine). CPSase II activity is present in spleen and other extrahepatic tissues, but is apparently absent from liver; the function of this enzyme is related to pyrimidine nucleotide biosynthesis, and the properties are analogous to mammalian CPSase II activities (independent of acetylglutamate, inhibited by UTP, and activated by 5‐phosphoribosyl 1‐pyrophosphate). Glutamine synthetase in shark liver is localized in the mitochondria, but the spleen glutamine synthetase is localized in the cytosol. Liver of largemouth bass (Micropterus salmoides, a freshwater teleost) also has CPSase III activity; however, unlike shark, aspartate carbamoyltransferase activity is also present in bass liver. Consequently, a major objective of this study was to establish if two different glutamine‐dependent CPSase activities are present in a single tissue (liver). Two different glutamine‐dependent CPSase activites were found to be present in bass liver, a mitochondrial CPSase III and a cytosolic CPSase II. The CPSase II activity, in contrast to the shark spleen CPSase II, appears to be associated with aspartate carbamoyltransferase and dihydro‐orotase activities, as found in mammalian species. As in shark, ornithine carbamoyltransferase, arginase, and phosphoenolpyruvate carboxykinase activities in bass liver are localized in the mitochondria, but, in contrast to shark, glutamine synthetase activity is localized in the cytosol. The properties of isolated, actively respiring bass liver mitochondria were investigated for comparison with previously reported properties of shark liver mitochondria. Respiration of bass mitochondria is supported by succinate and glutamate plus malate, but not by β‐hydroxybutyrate, palmitoyl‐CoA, citrate, or glutamine, all of which serve as excellent substrates for dogfish shark liver mitochondria. In contrast to shark mitochondria, bass mitochondria are not capable of ketone body formation and, of particular interest, do not catalyze citrulline formation from glutamine. CPSase III activity was not present in two other species of teleost fishes closely related to largemouth bass. The occurrence and function of CPSase III in teleost fishes are discussed.
Development and DNA polymerase activities in cultured preimplantation mouse embryos: Comparison with embryos developed in vivo
Authors: Kiessling Ann A. , Davis Howard W. , Williams Catherine S. , Sauter Ronald W. , Harrison Linda W. 
Published: June 2005

AbstractEmbryos from supervulated female mice that developed in vitro from the twocell stage were compared with in vivo embryos with respect to yield of blastocysts, number and types of cells, morphology in histologic section, and DNA polymerase activities. Significantly more embryos developed into blastocysts in vitro (93%) than in vivo (18%). Inner cell mass (ICM) cells comprised approximately 30% of total cells in late morula/early blastocyst stage embryos developed either in vitro or in vivo. However, the in vitro embryos developed approximately half the number of total cells as in vivo embryos, did not develop endoderm, and did not develop abembryonic trophoblast cells with morphologic characteristics of late preimplantation in vivo embryos. DNA‐dependent DNA polymerase activities in in vitro embryos decreased in correspondence with the decrease in cell number resulting in per cell levels comparable to in vivo embryos. In contrast, the poly (A)·oligo(dT)‐dependent DNA polymerase activity was the same in embryos developing either in vitro or in vivo, indicating different regulatory mechanisms for the two enzyme activities. A variety of nutrients and growth factors in the culture medium did not increase cell numbers or DNA polymerase activities in embryos cultured for 3 days; extending the culture an additional 24 hours resulted in a loss of ICM cells and decreases in both DNA polymerase activities. These results show that the retarded growth of embryos in vitro is equally distributed between ICM and trophoblast, is not reversed by culture conditions that include serum growth factors, and is not due to decreased cellular levels of DNA polymerase activities.
Storage and release of neuropeptides from the corpus cardiacum of the Eastern lubber grasshopper, Romalea microptera
Authors: Spring Jeffrey H. , Gäde Gerd 
Published: June 2005

AbstractIn this study, we describe a method for the separation of AKH/RPCH‐family peptides using isocratic high performance liquid chromatography (HPLC). This improved method is simple, rapid, and sensitive and bypasses many of the difficulties associated with gradient HPLC. We have previously shown that the lubber grasshopper, Romalea, accumulates large quantities of the native peptides Ro I and Ro II (Spring and Gäde, Journal of Experimental Zoology 241:41–50, 1987). In the present study, we used isocratic HPLC to follow the changes in the amount of Ro I and Ro II during development. Overall the amount of neuropeptide found in the corpora cardiaca (CC) increases 34‐fold from larval instar III to late adult, with the greatest quantitative increase (3,000 pmol total in males) occurring during the 6 weeks of adult life. The Ro I: Ro II ratio also changes during development, from 5.4 in larval instar III to 2.0 in late instar V and finally to 4.0 in mature adults. Under physiological conditions these neuropeptides can be released from Romalea CC isolated in vitro, when the CC are depolarized with high‐potassium saline. This release is calcium‐dependent and 10% to 15% of the total peptide stores are mobilized during a 1‐hour treatment with high‐potassium, plus calcium, saline. More than one‐third of the mobilized peptide is released within the first 5 min. In locusts, release of the AKH peptides is reported to be mediated by the neurotransmitter octopamine, acting via the adenylate cyclase pathway. In Romalea, however, we find no evidence for either octopamine or cAMP‐mediated release of neuropeptide.
Neomycin, an inhibitor of phosphoinositide hydrolysis, inhibits the resumption of bovine oocyte spontaneous meiotic maturation
Authors: Homa Sheryl T. 
Published: June 2005

AbstractThe possibility that the intracellular signals generated upon phosphoinositide hydrolysis are involved in regulating bovine oocyte spontaneous meiotic resumption was investigated. Oocytes were mass‐harvested and cultured in 2A‐BMOC medium supplemented with 0.5% bovine serum albumin in the presence or absence of neomycin (an inhibitor of phosphoinositide hydrolysis) or phorbol myristate acetate (an activator of protein kinase C). The role of intracellular calcium was examined by preloading with BAPTA/AM (a calcium chelator) prior to culture. Meiotic maturation was scored cytogenetically. 1) Neomycin induces an irreversible inhibition of germinal vesicle breakdown which does not exceed 60% and is apparent at concentrations of 5 mM or above. Progression of meiosis past metaphase I is inhibited at concentrations of 2.5 mM or above. The full effect of neomycin is only apparent if it is presented to the oocytes within 3 h of follicular release, although germinal vesicle breakdown is not observed until 9 h culture under control conditions. 2) PMA alone has negligible effect on germinal vesicle breakdown, but it acts synergistically with 2 mM IBMX to inhibit this process. PMA has a dual effect on the progression of meiosis past metaphase I: 1 nM PMA has a stimulatory effect while 1 μM PMA blocks the ability of oocytes to reach anaphase I or beyond. These observations are not found with a non‐tumor‐promoting phorbol ester. 3) Spontaneous meiotic resumption is not significantly affected in the absence of added exogenous calcium. However, oocytes preloaded with BAPTA/AM exhibit a dose‐dependent inhibition of germinal vesicle breakdown, even in the presence of extracellular calcium. These results provide indirect evidence for a role for phosphoinositide metabolism in bovine oocyte maturation; it is suggested that intracellular calcium mobilization is prerequisite for meiotic resumption and protein kinase C may modulate cAMP‐dependent inhibition of this response.
Hydrodynamics of the feet of fish‐catching bats: Influence of the water surface on drag and morphological design
Authors: Fish Frank E. , Blood Brad R. , Clark Brian D. 
Published: June 2005

AbstractThe bats, Noctilio leporinus and Pizonyx vivesi, display similar hind foot morphologies specialized for their fish‐catching habits. The hydrodynamic drag force of isolated hind feet from fishing and closely related non‐fishing bats was measured in a water channel at velocities up to 0.74 ms−1. Drag force increased curvilinearly with increasing water velocity. The highest values of drag force for a given velocity were measured for the fishing bats, which have hind feet 1.8–3.9 times larger than related non‐fishing bats. However at high Froude Numbers, the dimensionless drag coefficient (CD) was 23–39% lower for fishing bats compared to non‐fishing bats. Cross‐sections of the laterally compressed toes of N. leporinus and P. vivesi conformed to hydrofoil designs with minimum drag capabilities, indicated by Fineness Ratio and shoulder position. Moveing at high Froude Numbers at the water surface results in the addition of spray drag to the other components of the total drag force (i.e., frictional, pressure, and wave). Spray drag is suppressed by a foil shape with a long pointed leading edge with a short rounded trailing edge. The configuration of the fishing bat toe with a sharp leading edge and relatively long forebody region compared to the maximum thickness provided a measurable drag reduction at the air‐water interface. It was concluded that hydrodynamic drag considerations at the water surface were important in the design of hind feed for fish‐catching bats.