bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intercellular junctions in the Xenopus embryo prior to gastrulation
Authors: Sanders E. J. , Dicaprio R. A. 
Published: June 2005

AbstractA freeze‐fracture study of Xenopus embryos at the eight‐cell stage revealed the presence of tight junctions and small aggregations of 120 Å diameter intramembranous particles. These aggregations consited of up to ten particles and resembled forming gap junctions. Examination of early blastulae showed that fully developed gap junctions were present, apparently occuring very infrequently. These results support the contention that specialized junctions mediate electrical coupling during early amphibian development.
A scanning electron microscopic and flame spectrometry study on the role of Ca2+ in amphibian neurulation using papaverine inhibition and ionophore induction of morphogenetic movement
Authors: Moran Denis J. 
Published: June 2005

AbstractSEM observations reveal that papaverine, which interferes with Ca2+ flux, inhibits neural fold formation causing a flattening of the cellular surface and a broadening of cellular junctions. Ionophore A23187 and EGTA both counter this effect promoting a rapid cellular constriction which results in the formation of neural ridges and folds as individual cells become uplifted and ruffled. Flame spectrometry data indicate that as Ambystoma maculatum or mexicanum embryos neurulate Ca2+ is released to the medium, a condition which is impeded by papaverine. Ionophore A23187 induces Ca2+ influx whereas EGTA induces an efflux. Since both agents affect similar morphological changes it is suggested that the availability of free Ca2+ is crucial in controlling the morphogenetic movements of neurulation. It is now apparent that neuro‐axial development in the urodele is accompanied by a Ca2+ efflux, but the mechanism(s) responsible for the ion's release is unknown.
A sexual aggregating pheromone system in the zebrafish, Brachydanio rerio (hamilton‐buchanan)
Authors: Bloom Herbert D. , Perlmutter Alfred 
Published: June 2005

AbstractZebrafish, Brachydanio rerio, when placed in a T‐maze demonstrated preference for, or avoidance of, donor water produced when specified numbers of conspecifics of either sex were kept in holding systems for specific lengths of time. Inter‐ and intrasexual attractions were found to occur in different ranges of concentration of the attractant material(s). Insufficient or excessive concentrations of the attractant(s) failed to elicit the attractant response. The proposed pheromone attractant was shown to be removable from the aquatic environment. Its possible role in the behavioral aspects of schooling and spawning is discussed.
An autoradiographic evaluation of the regeneration of corneal epithelium in Bufo marinus
Authors: Grillo R. S. , Knowles B. A. , Cooperstein D. F. 
Published: June 2005

AbstractEpithelial regeneration following scraping of a central portion of corneal epithelium of the toad, Bufo marinus, was studied. Wound closure occurred by migration of a single layer of epithelial cells from adjacent noninjured areas. Autoradiography indicated that following wound closure at two days after scraping, DNA synthesis began in these epithelial cells covering the former scraped area, and was even more pronounced three days after scraping. At four days the former denuded area was covered by an epithelium two to four cells thick and by the fifth day regeneration was complete. These studies also indicated that mitotic time in this organism is rapid.
Localization of mouse Pgk‐2 gene at the D end of the H‐2 complex
Authors: Vandeberg John L. , Klein Jan 
Published: June 2005

AbstractA survey of the Pgk‐2 alleles carried by H‐2 congenic lines of mice has established that the Pgk‐2 locus is near the D end of the H‐2 complex on chromosome 17. A comparison among inbred strains of the alleles for Pgk‐2, H‐2, and two other genes in this vicinity, Tla and Ce‐2, has revealed a remarkable correlation suggestive of strong linkage disequilibrium in the wild mice from which the inbred strains were derived.
Ultrastructural localization of adenyl cyclase activity in neoblasts of turbellarian Dugesia lugubris (O. schmidt)
Authors: Moraczewski Jerzy , Duma Anna 
Published: June 2005

AbstractAC was localized cytochemically for the first time in tissues of lower Metazoa. Qualitative differences were found in the distribution of AC in the neoblasts of non‐regenerating and regenerating turbellarians. Changes were observed in AC activity during the course of regeneration.
Strain differences in the immune response of mice to homologous sperm‐specific lactate dehydrogenase (LDH‐C4)
Authors: Kille John W. , Wheat Thomas E. , Mitchell Graham , Goldberg Erwin 
Published: June 2005

AbstractThe sperm‐specific isozyme of murine lactate dehydrogenase (LDH‐C4 was injected into female mice of various strains. Two regulatory phenotypes characterize the resultant immunity to LDH‐C4: one is manifested by high, intermediate or low levels of response, the other by the immediate or delayed maturation of peak titer. The response of several strains can be classified as high (SWR, SJL, BABL/c, C3H/He) and intermediate to low (A, CBA, DBA/2, DBA/1, C57BL/6) according to the level of antibody production and cell mediated immunity. BALB/c, SJL and SWR strains are immediate responders while and C3H/He mice are clearly delayed responders. Maturation and magnitude of response do not appear to be related. Both the antibody and cell mediated responses are T‐dependent, but are not obviously associated with Ig allotype or H‐2 regulation.
The influence of acclimation temperature on the fatty acid composition of an aquatic Crustacean (Carcinus maenas)
Authors: Chapelle Serge 
Published: June 2005

AbstractCrabs (Carcinus maenas) were acclimated to temperatures of 7, 14 and 27°C and the fatty acid pattern of lipids from muscle, gills and hepatopancreas were determined. There was an overall tendency for the degree of unsaturation of fatty acids to decrease with an increase in acclimation temperatures. The greatest differences was observed in the relative content of C16:0, C16:1, C18:0, C18:1, C20:5 and C22:6 fatty acids. It is suggested that acclimation involves the ability to control the degree of unsaturation of cellular lipids in order to maintain a specific liquid‐crystalline state of biomembranes and to check the activity of certain enzymes implicated into lipoproteins of the cellular membranes. A significant enhancement of degree of unsaturation of the phosphatidylethanolamine and of the phosphatidylcholine was noted at lower temperatures. No or less pronounced changes occurred in triglycerides, phosphatidylserine and phosphatidylinositol. It is suggested that the acyltransferases, catalysing the conversion of lysophospholipid into phospholipid have an important regulatory role in the maintenance of a specific fatty‐acid pattern of principal phospholipids.
Selective incorporation of selenium‐75 into a polypeptide of the rat sperm tail
Authors: Calvin Harold I. 
Published: June 2005

AbstractSelenium is necessary for normal sperm tail development in the rat. The biochemical locus of this requirement was investigated by intratesticular administration of (75Se)Se03−2. Sperm were labeled primarily in tail keratin, a disulfide‐stabilized fraction obtained by extracting isolated tails with sodium dodecyl sulfate (SDS). By incubation in 1% SDS−0.2 mM dithiothreitol, followed by sonication and centrifugation, the 75Se was separated from a residue rich in S and Zn, composed of dense fibers and connecting pieces. The extracted 75Se‐labeled material was non‐dialyzable, sensitive to pronase, retained most of its bound isotope following carboxymethylation, and displayed only one radioactive component, of 17,000 daltons, during SDS‐polyacrylamide gel electrophoresis. It is suggested that the labeled moiety is a selenopolypeptide whose function is critical for normal assembly of the sperm tail.
Enhanced identification of lethal yellow (Ay/Ay) mouse embryos by means of delayed development of four‐cell stages
Authors: Granholm Nels H. , Johnson Phyllis M. 
Published: June 2005

AbstractAt present, experimental studies on the primary genetic lesion in Ay/Ay embryos are restricted by the absence of techniques designed to identify Ay homozygotes prior to the onset of secondary defects. This paper describes a methodology to enrich the yields of Ay homozygotes in experimental populations by taking advantage of an early homozygous Ay expression‐lagging development in 4‐cell embryos.
Effects of hydrostatic pressure on (Na+ + K+)‐ATPase and Mg2+‐ATPase in gills of marine teleost fish
Authors: Pfeiler Edward 
Published: June 2005

AbstractThe effects of hydrostatic pressure on branchial NaK‐ATPase and Mg‐ATPase activities were studied in two species of marine teleost fish: the relatively shallow water Scorpaena guttata, collected from a depth of 20 m, and the deeper living Anoplopoma fimbria, collected from a depth of 310 m. Specific activities in gill microsomes, measured at 18oC, were similar in both species, with the NaK‐ATPase usually comprising about 30–40% of the total ATPase activity. NaK‐ATPase activity of S. guttata was activated by low hydrostatic pressure (68 atm) but activity was inhibited at pressures above 136 atm. The NaK‐ATPase of A. fimbria showed a similar activation at low hydrostatic pressure but was less sensitive to a pressure of 340 atm than the enzymefrom S. guttata. At a pressure of 476 atm, the NaK‐ATPase activity of both species was inhibited to the same extent. The Mg‐ATPase of both species was activated by pressure (maximal activation occurred at 136 atm), but in contrast to the NaK‐ATPase, remained activated at all pressures tested. Solubilization of the enzymes from gill microsomes of A. fimbria with Lubrol WX did not significantly alter the pressure responses. Inhibition of NaK‐ATPase at high pressure was reversible upon release of pressure. Inhibition of branchial NaK‐ATPase in both species occurred at pressures higher than the fish normally experience in their environment.
Comparative study on horseshoe crab coagulogens
Authors: Shishikura F. , Sekiguchi K. 
Published: June 2005

AbstractCoagulogens prepared from four species of horseshoe crabs, Tachypleus tridentatus, Tachypleus gigas, Limulus polyphemus, and Carcinoscorpius rotundicauda, were comparatively studied on their biochemical and immunological characteristics. Each coagulogen had a molecular weight of about 20,000 by sodium dodecyl sulfate‐gel electrophoresis. The clotting enzyme of T. tridentatus could cause the gelation of the coagulogen not only from the species but also from other three species. Having analogous function in the clotting mechanism and the same value of molecular weight, only coagulogen of L. polyphemus was immunologically very different from that of others.
Role of subdermal current shunts in the failure of frogs to regenerate
Authors: Borgens Richard B. , Vanable Joseph W. , Jaffe Lionel F. 
Published: June 2005

AbstractLarge, uniform, skin‐driven currents (20–40 μamp/cm2) leave the ends of limb stumps of post‐metamorphic frogs (Rana pipiens) from about the first through the tenth day after amputation. However, right after amputation, while currents of comparable density may leave the periphery of the cut surface, current densities are greatly depressed in the center of this surface. We suggest that this depression is brought about by shunting through the subdermal lymph space (characteristic of anurans but not urodeles); continues in covert form after formation of a wound epithelium; and helps explain the ability of small, imposed currents to initiate frog limb regeneration.
The influence of acclimation temperature on the phospholipid metabolism of an aquatic crustacea (Carcinus maenas)
Authors: Chapelle Serge , Zwingelstein Georges , Meister Roger , Brichon Gérard 
Published: June 2005

AbstractIncorporation of 32P into phospholipids from gills, hepatopancreas and muscle isolated from the crab Carcinus maenas was analysed at acclimation temperatures of 7°C and 27°C. Velocity of total phospholipid labelling from inorganic phosphate (Pi) and acid‐soluble organic phosphate (PoAS) rose with an increase in environmental temperature. The velocity of biosynthesis of certain phosphatides was especially altered by thermal stress. The velocity of 32P incorporation into PA was increased at lower temperature (7°C), whereas the turn‐over of other phospholipids (particularly PC and SPH) was relatively low at the same temperature.In general, the warm acclimation produced, in all tissues, an increased rate of 32P incorporation into PC and SPH accompanied with a negligible modification of the label entry into PE. It is suggested that the activity of the 32Pi → 32PA → 32PI pathway is increased at high temperature in gills and hepatopancreas and that the activity of LPC ⇄ PC deacylation‐acylation reaction in hepatopancreas depends on the temperature of the exterior medium.
Separation of calcium effects on motility and zona binding ability in mouse spermatozoa
Authors: Heffner Linda J. , Sailing Patricia M. , Storey Bayard T. 
Published: June 2005

AbstractThe ionic specificity of Ca+2 requirements for binding to the zona pellucida and maintenance of motility were studied in mouse gametes by comparing the effects of four cations: Ca+2, Sr+2, La+3, and spermine cation (Sp+4). Cumulus‐free mouse eggs were inseminated in vitro with sperm which had been preincubated for 60 min in Tris‐NaCl buffer containing one or more of the above cations. Motility was assessed microscopically and zona binding, by the stop‐fix technique, utilizing centrifugation through a discontinuous density gradient. The sperm were motile upon release from the epididymis, and all sperm maintained their motility in complete culture medium. Sperm incubated in Tris‐NaCl buffer differed in motility among samples as follows: The majority of sperm samples remained motile in Tris‐NaCl containing 1.7 mM Ca+2, but lost motility if Ca+2 was absent. The remaining samples could be divided into two populations: those which maintained motility in the absence of Ca+2. Support of Zona binding required Ca+2 in all samples examined. Equimolar Sr+2 could substitute for Ca+2 in maintaining motility but not in supporting binding. Sp+4and La+3 did not support motility. If Sr+2 were present to maintain motility, both Sp+4 and La+3 supported binding as well as Ca+2. Sr+2 did not complete with any of the other cations for support of zona binding. Ca+2 and Sp+4 together in the medium produced a synergism in the number of sperm bound. La+3 would substitute for Ca+2 in this synergism. These results demonstrate for the first time that mouse sperm have Ca+2 requirement for the motility maintenance and that binding to the zona and maintenance of motility are two different Ca+2‐dependent processes whose active sites can be distinguished by cation substitution.
Yolk proteins in developing follicles of the house cricket, Acheta domesticus (L.)
Authors: Nicolaro Mary‐Lou , Bradley James T. 
Published: June 2005

AbstractThe occurence of the two major yolk proteins in vitellogenic follicles at various stages of development in the house cricket, Acheta domesticus, was studied electrophoretically. Follicles were staged into size classes ranging from 0.75 mm (stage I) to ≥2.0 mm (stage IV) for unfertilized eggs (chorionated follicles) and the molar ratio of the two vitellins within follicles of each stage determined. The ratio of vitellin I to vitellin II during the early stages of vitellogenesis was found to be greater than that during later stages, suggesting the possibility of changing selectivity of vitellogenin uptake by follicles as they progress through the vitellogenic phases of oogensis. The relative distribution of vitellins I and II within the cytoplasm of unfertilized, chorionated follicles was studied by sectioning stage IV follicles into thirds and determining the molar ration of vitellin I to II in each third. It was found that a differential distribution of each vitellin is established during oogenesis such that vitellin I is present in greater quantities in the posterior region and vitellin II in greater quantities in the anterior region of the follicle.The molecular weights of the two vitellins were estimated using native polyacrylamide gels of varying percents acrylamide. The molecular weights of vitellins I and II were estimated at 352,000 and 327,000 daltons, respectively.
Regeneration of rabbit ear tissue
Authors: Williams‐Boyce Patsy K. , Daniel Joseph C. 
Published: June 2005

AbstractHoles punched in the ears of rabbits are repaired by regeneration of new tissues from blastemas found on the periphery of the wounds. The proportion which successfully regenerated was greater in males than in females (75% vs 20%), in pregnancy than during estrus or lactation (75% vs 25%), and in ovariectomized does given testosterone than in those given oil carrier alone (88% vs 50%), but the speed of closure did not differ in these groups. The steroid hormone influence postulated by other workers is confirmed.Closure was faster in younger animals and for second holes punched on the same site where earlier holes had been repaired, in both cases, by shortening of the initial seven to ten day delay period seen for primary holes in adult ears. The cartilage layer was also thicker after regeneration from secondary punches and the success rate greater (67% vs 29%). These observations suggest a “priming” effect on the tissue from the primary punch.Ear holes in the area proximal to the head were repaired faster and with more success (78% vs 12% ) than those punched distally. The relative thickness of the cartilage layer may be the critical factor. Tissues did not regenerate from semicircular wounds made on the edge of the pinna.Hair grown on regenerated ear skin reestablished the original color pattern. Skin regenerating for holes punched where skin from the back had been transplanted to ears had the characteristics of back skin, but no regeneration was detectable from transplanted toe tissue. Skin from other locations can regenerate in the environment provided by the ear but more complex tissue structure put into the same location apparently cannot. Skin cells involved in regeneration originate from the tissues bounding the wound.
A study of the catalytic properties of pyruvate kinase isozymes from salmon and an examination of their functional relationships
Authors: Guderley Helga , Cardenas Janet M. 
Published: June 2005

AbstractTwo major isozymes of pyruvate kinase that differ in electrophoretic and kinetic properties are found in salmon (Oncorhynchus kisutch). Type M occurs in cardiac and skeletal muscle, while type K is the main isozyme of the other tissues. We have been examining the structural and kinetic properties of the pyruvate kinase isozymes of salmon in an effort to assess their regulatory properties as well as their structural and functional relationships to the isozymes from “higher” vertebrates. We find that type K pyruvate kinase has hyperbolic kinetics with both phosphoenolpyruvate and ADP but that the apparent affinities for the two substrates are interdependent. That is, decreased affinities for phosphoenolpyruvate occur at higher concentrations of ADP and vice versa. In contrast, salmon type M pyruvate kinase has slightly sigmoidal kinetics with phosphoenolpyruvate, indicative of cooperative interactions among subunits of the latter isozyme. However, the affinity of this isozyme for each substrate is much less effected by the concentration of the other substrate. Salmon type K pyruvate kinase binds Mg++ cooperatively in the absence of fructose bisphosphate, where as type M binds Mg++ twice as tightly but in a non cooperative fashion. Both enzymes are inhibited to a similar extent by ATP, but they may differ in the nature of this inhibition. The salmon isozymes differ from avian and mammalian pyruvate kinase in that they are much less susceptible to inhibition by alanine and phenylalanine. The kinetic properties of salmon type K pyruvate kinase imply it to be more amenable to regulation that salmon type M, a situation that is also true for the corresponding isozymes from birds and mammals. Nevertheless, the two salmon isozymes appear to be more similar kinetically to each other than are types K and M pyruvate kinases from higher vertebrates, suggesting less evolutionary divergence for the salmon isozymes.
Genetic variability of alcohol dehydrogenase among Australian Drosophila species: Correlation of ADH biochemical phenotype with ethanol resource utilization
Authors: Holmes Roger S. , Moxon Leith N. , Parsons Peter A. 
Published: June 2005

AbstractAlcohol dehydrogenase (ADH) activities, electrophoretic phenotypes, and the extent of ethanol resource utilization are compared for three groups of species distinguishable on ecological criteria: 1) the cosmopolitan species D. melanogaster, a frequent inhabitant of wineries; 2) fruit‐baited species of the typically Australian subgenus Scaptodrosophila: D. lativittata, D. nitidithorax and D. howensis; and 3) Scaptodrosophila species not attracted to fermented‐fruit baits being collected by sweeping in temperate rain forests (D. inornata, D. collessi) or from Hibiscus flowers (D. hibisci). D. melanogaster showed the highest levels of ADH activity and an electrophoretic polymorphism with two active allelic forms, while group 2) species showed intermediate ADH activities and polymorphisms, which were consistent with “high activity” and “low activity” allelic forms in natural populations of these species, and group 3) species showed only “low activity” forms. Ethanol resource utilization follows the same sequence, being 1 > 2 > 3(D. howensis and D. collessi were not tested). Therefore the species considered shown an association of ADH biochemical phenotype, laboratory ethanol utilization, and resources utilized.
Effects of the gene Wh on reproduction in the Syrian hamster, Mesocricetus auratus
Authors: James Susan C. , Hooper Gary , Asher James H. 
Published: June 2005

AbstractThe gene Wh, causing anophthalmia in the Syrian hamster, Mesocricetus auratus, is a highly pleiotropic gene, which has profound effects upon eye development, pigmentation, and reproduction. Since male hamsters homozygous for this gene are usually sterile, the objective of this study was to determine whether the testes of mutant hamsters differed from the normal phenotype. Accordingly, the testicular tissue from ten normal, ten heterozygous, and ten homozygous mutant animals in the AN/As‐Wh strain were compared at the gross, light, and electron microscopic level. Testicular tissue from several mutant animals approached the normal phenotype, due to variable expression of the gene. However, most testes from homozygous mutant hamsters were hypoplastic and aspermic. Abnormalities were observed in Leydig cells, Sertoli cells, and in the developing germ cells. Seminiferous tubules contained germinal epithelium arrested in the early spermatid stage of spermiogenesis, possibly due to premature failure of the Golgi apparatus and a subsequent dysgenesis of the acrosome. Since the primary action of the gene is unknown, it was postulated that the gene either acts directly to alter pituitary function, or that the abnormalities in reproduction are due to a failure of eye development and subsequent lack of function of the visual pathway.