bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isolation of Raja erinacea basolateral liver plasma membranes: Characterization of lipid composition and fluidity
Authors: Smith Daniel J. , Ploch Stephen A. 
Published: June 2005

AbstractDeveloping a method for isolating skate (Raja erinacea) basolateral liver plasma membranes, as well as characterizing the lipid composition and fluidity of these membranes, was the primary purpose of this study. Membranes were isolated using self‐generating Percoll gradients. Marker enzyme studies indicate that this preparation is highly enriched in the basolateral domain of the liver plasma membrane and largely free of contamination by intracellular organelles or canalicular membranes. Further, these membranes contain the agency responsible for Na+‐dependent alanine transport. This finding indicates that this membrane prepration will be useful for the study of skate liver plasma membrane transport processes.The lipid composition and fluidity (as assessed by the fluorescence anisotropy of 1,6‐diphenyl‐1,3,5‐hexatriene) of the skate basolateral liver plasma membrane shows little variation among preparations. Further, DPH anisotropy plotted as a function of temperature yields a straight line (r = 0.99) which indicates that there is no lipid phase change in these membranes from 4° to 37°C. The membrane preparation does contain substantial phospholipase A2 activity. The function of this enzyme is, in part, to modify membrane lipid composition and fluidity in response to temperature variations; therefore, this finding suggests that in situ lipid metabolizing enzymes may play a central role in the adaptation of skate basolateral liver plasma membranes to changes in the ambient temperature.
Linkage analysis of the murine Hyal‐1 locus on chromosome 9
Authors: De Maeyer‐Guignard Jaqueline , Cachard‐Thomas Annie , De Maeyer Edward 
Published: June 2005

AbstractWe have recently described a new locus, Hyal‐1, which determines hyaluronidase variants in mouse serum. On the basis of segregation in recombinant inbred and congeric strains, Hyal‐1 was tentatively assigned to chromosome 9 (Fiszer‐Szafarz and De Maeyer, '89). In the present study we have performed a linkage analysis of Hyal‐1 using 156 backcross progeny of an interspecies cross of laboratory mice and Mus Spretus. Linkage was tested to two anchor loci on chromosome 9: d (dilute, a coat color locus) and Bgl‐s (a locus controlling β‐galactosidase activity). The gene order (from centromere) with intervening percentage recombination is d‐16.6 ( ± 2.9)‐Hyal‐1‐10.9 ( ± 2.4)‐Bgl‐s, indicating close linkage to H‐7 and Fv‐2.
Granulosa cell–oocyte interactions: The phosphorylation of specific proteins in mouse oocytes at the germinal vesicle stage is dependent upon the differentiative state of companion somatic cells
Authors: Cecconi S. , Tatone C. , Buccione R. , Mangia F. , Colonna R. 
Published: June 2005

AbstractThe role of granulosa cells in the regulation of mouse ovarian oocyte metabolism was investigated. Fully grown antral oocytes, isolated from surrounding cumulus cells, were cultured on monolayers of preantral granulosa cells in the presence of dbcAMP to prevent the resumption of meiosis. Under these conditions metabolic cooperativity was established between the two cell types as early as 1 hr after seeding. Moreover, cocultured oocytes phosphorylated two polypeptides of 74 and 21 kDa which are normally phosphorylated in follicle‐enclosed growing oocytes but not in cumulus cell‐enclosed fully grown oocytes at the germinal vesicle stage. When cocultured oocytes were allowed to resume meiosis, the 74 and 21 kDa proteins were synthesized but no longer phosphorylated even though intercellular coupling between the two cell types was maintained during radiolabeling. It appears therefore: a) that the different protein kinase activity of growing and fully grown germinal vesicle‐stage mouse oocytes is related to the differentiative state of granulosa cells, and b) that the regulation of oocyte protein phosphorylation activity by granulosa cells is dependent on the meiotic stage of the oocyte.
Partial purification of Xenopus laevis egg extract factor(s) that induce swelling in permeabilized human sperm
Authors: Brown David B. , Miskimins W. Keith , Ruddle Frank H. 
Published: June 2005

AbstractA combination of adsorption (protamine‐agarose) and gel filtration (Sephacryl S‐300) chromatography was used to enrich for factor(s) in Xenopus laevis frog egg extract that induce nuclear swelling‐chromatin decondensation in permeabilized human sperm. It was determined that a 70‐fold purification of the factor(s) that induce human sperm nuclear swelling has resulted from the purification scheme. The reduced, active factor(s) have a Kav of 0.12 and an approximate molecular weight of 290,000 daltons. The extract nuclear swelling activity is sensitive to temmperaturs of 50°C and above, as well as proteolytic treatment. RNase and cycloheximide treatments of the extracts have no effect on the nuclear swelling activity. These data suggest that the egg extract factor(s) that induce nuclear swelling in permeabilized human sperm are protein(s) that are present in the unfertilized frog egg.
Changes in intercellular contacts, motility, and adhesiveness of the presumptive mesodermal cells of Bufo vulgaris embryos before and during gastrulation
Authors: Komazaki Shinji 
Published: June 2005

AbstractThe morphology and adhesiveness of the presumptive mesodermal cells (PMCs) of Bufo vulgaris embryos were examined before and during gastrulation. Before the late‐blastula stage, the PMCs were in close contact with one another and were polyhedral in shape. Intercellular contacts became loose and cells were round in shape at the late‐blastula stage. At the initial stage of gastrulation, the PMCs began to form hyaline blebs. The blebbing cells appeared to crowd in one region (the bleb‐forming region [BFR]), located in the deep marginal mesoderm: The blebbing cells decreased in number and changed into filopodia‐ and lamellipodia‐forming cells with the start of the migration of PMCs at the early‐gastrula stage.Cells in the BFR and in the presumptive BFR were isolated, and adhesiveness of cells to fibronectin was examined. The results showed that the BFR cells begin to adhere to fibronectin at the early‐gastrula stage when the PMCs start to migrate along the inner surface of the blastocoelic wall.A series of changes (i.e., loosening of intercellular contacts, the formation of hyaline blebs, and the development of the ability to adhere to fibronectin) is thus evident in the PMCs before and during gastrulation. These serial changes are discussed within the context of the way in which PMCs start to migrate at the early‐gastrula stage.
Expression of epidermal growth factor (EGF) and the EGF receptor in human tissues
Authors: Fukuyama Ryuichi , Shimizu Nobuyoshi 
Published: June 2005

AbstractThe EGF‐EGF receptor system has been widely examined for signal transduction, control of cell growth and differentiation, and in vivo physiological function and carcinogenesis. The localization of EGF receptors in vivo led to the idea that the system is operative in proliferation and differentiation of cells and tissues. However, a consensus for its distribution and function in human tissues has not yet been determined because of discrepancies in the reported results. Using a highly specific monoclonal antibody against the EGF receptor, we examined various tissues of an infant and adults as well as embryonal carcinoma. We observed restricted localization of EGF receptors in basal cells of epithelial tissues and duct cells of secretory tissues. Fibroblasts express a high level of EGF receptors when they are rapidly growing. Using the monoclonal anti‐EGF antibodies, we observed that EGF is localized to differential cells rather than to stem cells such as glandular tissues. We also observed that some cells express both EGF and the EGF receptor. All histochemical results indicated that in epidermis and various glandular tissues, EGF may be expressed in differentiating cells derived from the stem cells expressing EGF receptors.
Effects of oxygen concentration and clutch on sex determination and physiology in red‐eared slider turtles (Trachemys scripta)
Authors: Etchberger Cory R. , Phillips John B. , Ewert Michael A. , Nelson Craig E. , Prange Henry D. 
Published: June 2005

AbstractIn many species of reptiles, sex is determined by the incubation temperature of the egg. In the red‐eared slider turtle (Trachemys scripta), warm incubation temperatures produce females, cool ones produce males, and a narrow range of intermediate temperatures produces both sexes. The mechanism of sex determination has not been established. Some investigators have postulated that both total incubation time and developmental rate during the first third of development are better predictors of sex than is incubation temperature. Here we consider whether various oxygen concentrations might influence sex determination by altering total incubation time. We incubated T. Scripta eggs at various oxygen concentrations, and found that while total incubation times were significantly influenced by oxygen, sex ratios were not. Very low oxygen concentrations inhibited survival to hatching, In addition, total incubation time and the number of days to internalize the yolk after hatching were significantly lengthened by lowered oxygen concentrations. There were also strong effects of clutch on sex determination and physiology, but these effects were apparently not mediated by an effect on total incubation time.
Purification and characterization of an acidic β‐galactosidase from the hepatopancreas of the shrimp Penaeus japonicus (Crustacea: Decapoda)
Authors: Chuang Nin‐Nin , Yang Bei‐Chia , Yeh Che‐Chung 
Published: June 2005

AbstractAn acidic β‐galactosidase was purified approximately 2,500‐fold to homogeneity from the shrimp Penaeus japonicus. with a final specific activity of 4,000 units/mg of protein. SDS‐polyacrylamide gel electrophoresis revealed the monomers of the acidic β‐galactosidase to have a relative mass of 66,000. Since the active acidic β‐galactosidase was found to have a relative mass of 140,000 by Ferguson plot analysis, the purified enzyme was concluded to be dimeric. No protective polypeptide was identified in the final preparation of purified β‐galactosidase. The shrimp enzyme was found to be thermolabile. Upon heating at 56°C for 10 min, the enzyme lost 50% of its activity. The acidic β‐galactosidase had an isoelectric point (pI) of 4.6 ± 0.1 and the enzyme was sialyated. The shrimp enzyme had a pH optimum of 5.5 and its Km was 43 μM with 4‐methylumbelliferyl‐β‐D‐galactoside as substrate. The enzyme was inhibited by both Mn++ and Zn++ ions.
Metabolism of progestogens during in vitro meiotic maturation of follicle‐enclosed oocytes of the goldfish (Carassius auratus)
Authors: Lessman Charles A. 
Published: June 2005

AbstractProgestogens are known to elicit meiotic maturation of fish oocytes in vitro. Exogenous 17α‐hydroxyprogesterone (HP), as assessed by radioimmunoassay (RIA), decreased exponentially to less than 10% of the initial level in media during a 48 hr incubation with large (i.e., 1 mm dia.) ovarian follicles of goldfish undergoing meiotic maturation in vitro. During follicle incubation, media, into which [3H]‐HP was introduced, showed exponential showed exponential reduction of [3H]‐HP with a concomitant increase in the number of [3H]‐HP metabolites. Analysis of follicle extracts revealed that small amounts of [3H]‐HP were taken up by the follicles early in the incubation (i.e., 3 hr) and converted to several metabolites; the major one of these, which accumulated in the follicle, comigrated with 17α, 20β dihydroxy 4‐pregnen 3‐one (DHP). Autoradiography of extracts run on TLC revealed an increasing number of metabolites with time, i.e., 9 major spots for media, 6 major spots for follicles incubated 24 hr with [3H]‐HP. Three of the more prominent metabolites, DHP, 3α, 17α‐dihydroxy5β‐pregnan 20‐one, and 5β‐pregnan3α, 17α, 20β‐triol, were identified tentatively by comigration with standards on TLC and crystallization to constant specific activity. HPLC of extracts revealed a selective accumulation of DHP in follicles over time i.e., this steroid was the major metabolite peak associated with follicles by 24 hr incubation. Nevertheless, the process of oocyte maturation had already been initiated before the peak level of DHP had been reached. By contrast, HP diminished with time in follicles despite the relatively high levels occurring in the media. This research indicates that a complex steroid milieu at the level of individual, fully grown, ovarian follicles is produced in vitro from exogenous HP; significant HP metabolism occurs by 6 hr incubation, well before the process of oocyte maturation (i.e., germinal vesicle migration and dissolution) has begun.
Identification and expression of boar sperm proteins in the reproductive tract that interact with antibodies in serum from an infertile woman
Authors: Haneji Tatsuji , Nagano Toshio , Koide S. S. 
Published: June 2005

AbstractSerum designated as IS obtained from a young healthy infertile woman induced a head‐to‐head agglutination of ejaculated boar sperm. The immunoglobulin G (IgG) prepared from IS localized to the acrosomal region of the sperm head obtained from the corpus and cauda epididymis as determined by an indirect immunofluorescent method. The IgG interacted with a boar sperm protein with an estimated molecular weight of 45‐kDa, determined by sodium dodecyl sulfate‐polyacrylamide gel electrophoretic (SDS‐PAGE) immunoblotting technique. However, the IgG did not interact with proteins extracted from sperm obtained from the testis and caput epididymis or from non‐gonadal tissues including liver, kidney, spleen, muscle and serum. The IgG interacted with additional proteins of about 75‐and 38‐kDa present in the corpus and cauda epididymal fluids but not those in the caput epidiymal fluid. The staining intensity of the 75‐kDa band was reduced and that of the 38‐kDa was nullified with ejaculated seminal plasma proteins. The interacting proteins were adsorbed when chromatographed on Concanavalin A Sepharose column, suggesting that they are glycoproteins.
Proteolytic activity in the fat body during the pupal‐adult metamorphosis of the silkworm, Bombyx mori
Authors: Yaginuma Toshinobu , Ushizima Miwa 
Published: June 2005

AbstractProteolytic activity with an optimum pH of 4.0 was found in fat bodies of 5 to 6 day‐old female pupae of the silkworm, Bombyx mori, using azocoll as a synthetic substrate. The activity was strongly inhibited by p‐chloromercuric benzoate at 0.5 mM, although inhibitory effect of several kinds of compounds on proteolytic activity was examined. Developmental changes in the activity were associated with two peaks of proteolytic activity related to the larval‐pupal and pupal‐adult transformation, the activity in the fat body of females was clearly higher than that of males. The profile of the proteolytic activity after chromatography on a column of Sephacryl S‐300 showed that, in the female fat body, the highest activity was in the fraction with a molecular weight of about 232,000 daltons while, in male fat body, the highest activity was in the fraction with a molecular weight of about 105,000 daltons. The storage proteins were digested when extracts from fat bodies, which contain storage proteins and proteases, were incubated and only when the pH of the extract was adjusted to 4.0. In the case of female fat body, storage protein 1 was degraded earlier than storage protein 2. Furthermore, the administration of 20‐hydroxyecdysone (5 μg/animal) to the isolated abdomens of female pupae (dauer‐pupae) induced the proteolytic activity in the fat body in parallel with ovarian development. These results suggest that the proteases in female and male fat bodies are responsible for the utilization of storage proteins during pupal‐adult development.
Comparative study of orb web hygroscopicity and adhesive spiral composition in three araneid spiders
Authors: Townley Mark A. , Bernstein David T. , Gallagher Kathleen S. , Tillinghast Edward K. 
Published: June 2005

AbstractOrb web hygroscopicity was examined in three species of araneid spiders, Argiope aurantia, Argiope trifasciata, and Araneus cavaticus. Both whole webs and fractions generated from them (water‐soluble and ‐insoluble fractions; ethanol‐soluble and ‐insoluble subfractions [Etsol and ‐insol]) were examined at various relative humidities. In general, the water‐soluble fraction, consisting of low molecular weight components (LMW) of the adhesive spiral cover, was more hygroscopic than the water‐insoluble (protein) fraction. As the Et‐sol of the water extract was typically more hygroscopic than the Et‐insol, it appears that organic LMW are more responsible for water adsorption by the adhesive spiral cover than inorgnic LMW. Hygroscopicity measurements made on individual synthetic or commercially obtained LMW compounds known to be in the web (both organic and inorganic) agree with this interpretation.As a first attempt toward correlating web hygroscopicity with composition, the water‐soluble web fractions from the three species were examined by proton nuclear magnetic resonance (1H‐NMR) spectroscopy and the molar percentages of the organic LMW were estimated. To accomplish this, it was necessary to identify the principal organic LMW in the web of A. trifasciata (since, unlike the situation in other araneids which have been studied, GABamide is not the principal organic LMW in A. trifasciata). Using 1H‐NMR and thin layer chromatography this compound was identified as N‐acetylputrescine. While considerable interspecific variation in the molar percentages of GABamide, N‐acetylputrescine, isethionic acid, and N‐acetyltaurine was observed, interspecific differences in Et‐sol hygroscopicities were not apparent.
Regulation of proline synthesis during osmotic stress in the copepod Tigriopus californicus
Authors: Burton Ronald S. 
Published: June 2005

AbstractThe marine copepod Tigriopus californicus shows rapid adjustment of intracellular proline and alanine pools in response to salinity stress. Small increases in salinity (on the order of 2 ppt or 50 mOsmoles) are sufficient to elicit proline synthesis in animals acclimated to 50% seawater. Increases in osmolarity achieved by adding organic solutes to a 50% seawater medium also elicited proline (but not alanine) synthesis. In constant 50% seawater, label from 14C‐(U)‐glucose is incorporated into the free alanine and glutamate (but not proline) pools; only the proline pool shows a monotonic increase in specific activity following transfer to 100% seawater. To demonstrate that glutamate is a proline precursor, 14C‐(U)‐glutamate was provided to animals maintained in 50% seawater (control) and animals transferred to 100% seawater; salinity change resulted in the rapid increase in alanine and proline concentrations, with proline (and not alanine) achieving specific activities similar to that of the glutamate pool. Taken together, these results indicate that small hyperosmotic stimuli result in the induction of proline synthesis from glutamate. The regulation of proline synthesis involves mechanisms discrete from those regulating the concentrations of other FAA functioning in osmotic response.
Regulation of phosphofructokinase in the foot muscle of Patella caerulea (L.) during exposure to air
Authors: Lazou Antigone 
Published: June 2005

AbstractThe effects of 4 hours and 8 hours of exposure to air on the kinetic properties of phosphofructokinase (PFK) and the maximal activity of glycogen phosphorylase were studied in order to evaluate the role of these enzymes in glycolytic rate control and metabolic depression during air exposure of Patella caerulea foot muscle.Air exposure resulted in stable modifications of the kinetic properties of PFK including changes in S0.5 for fructose‐2,6‐phosphate (fructose‐6‐P), Hill coefficient, Ka values for adenosine monophosphate (AMP), fructose‐2,6‐biphosphate (fructose‐2,6‐P2), and I50 for adenosine triphosphate (ATP) and phosphoenolpyruvate (PEP), the direction of changes being generally consistent with the production of a less active form in the air exposed tissue. Air exposure did not affect maximal activity of glycogen phosphorylase nor the percentage of active α form. In contrast, changes in the tissue content of fructose‐2,6‐P2 were observed.Incubation of PFK preparations with protein kinase second messengers (cyclic adenosine mono‐phosphate [cAMP] and cyclic guanosine monophosphate [cGMP]) lead to an increase in the enzyme activity and affinity for the substrate whereas treatement with alkaline phosphatase reversed these effects. The data suggest that modification of PFK kinetics during air exposure is probably mediated via a phosphorylation‐dephosphorylation mechanism.
Protective effects of manganese, cobalt, nickel, and barium against a calcium paradox in the isolated frog heart
Authors: Touraki Maria , Beis Isidoros 
Published: June 2005

AbstractThe effect of inorganic slow channel blockers on the calcium paradox in the frog heart was examined. Addition of the divalent cations of manganese, cobalt, nickel, or barium during calicium depletion protected the frog heart against a calcium paradox. This protective effect was indicated by reduced protein release, maintenance of electrical activity, and recovery of mechanical activity during reperfusion.Tissue calcium determination results showed that in the control paradox in the absence of divalent cations, there is an efflux of calcium from myocardial cells during calcium depletion and a massive influx of calcium during the following reperfusion, leading to a calcium overload. Divalent cations protected frog myocardial cells, when present in the calcium‐free perfusion medium, by reducing both calcium efflux during calcium depletion and the massive calcium influx during reperfusion.The effectiveness of the added divalent cations showed a strong dependence upon their ionic radius. The most potent inhibitors of the calcium paradox in the frog heart were the divalent cations having an ionic radius closer to the ionic radius of calcium.These results are discussed in terms of the possible mechanism involved in the protective effect of manganese, cobalt, nickel, and barium.
Identification of a stretch‐activated monovalent cation channel from teleost urinary bladder cells
Authors: Chang Wenhan , Loretz Christopher A. 
Published: June 2005

AbstractThe urinary bladder of euryhaline teleosts is an important osmoregulatory organ which absorbs Na+, Cl−, and water from urine. Using patch clamp technique, single stretch‐activated channels, which were permeable to K+ and Na+ (PNa/PK ≈︁ 0.75) and had conductances of 55 and 116 pS, were studied. In excised, inside‐out patches which were voltage‐clamped in the physiological range of membrane potential, the single‐channel open probability (P0) was low (≈︁0.02), and increased to a maximum of 0.9 with applied pipette suction. Single‐channel conductance also increased with suction. The channels showed adaptation to applied suction and relaxed to a steady‐state activity about 20 seconds after application of suction. The P0 increased up to 0.9 with strong membrane depolarization (Vm = 0 to + 80 mV); however, there was little dependence of P0 on membrane potential in the physiological range. The kinetic data suggest that there is one conducting state and at least two non‐conducting states of the channel. The open‐time constant increased with suction but remained unchanged with membrane potential (Vm = −70 to + 60 mV). The mean closed‐time of the channel decreased with suction and membrane depolarization. These results demonstrate the presence of a non‐selective monovalent cation channel which may be involved in cell volume regulation in the goby urinary bladder. Additionally, this channel may function as an enhancer of Na+ influx and K+ efflux across the bladder cell as part of transepithelial ion transport if it is located in apical membrane.