bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differences in motor output and fiber composition of the opener muscle in lobster dimorphic claws
Authors: Govind C. K. , Stephens Philip J. , Trinkaus‐Randall V. 
Published: June 2005

AbstractThe structural and biochemical properties of the opener muscle and the impulse pattern of its single excitatory motoneuron differed between the paired cutter and crusher claws in the lobster, Homarus americanus. The soma of the opener excitor (OE) motoneuron was physiologically identified in an isolated claw‐ganglion preparation and its responsiveness to sensory stimulation of the first and second nerve roots monitored. The OE soma to the crusher claw had a higher spike frequency and burst duration than its counterpart to the cutter claw. The OE axon to the cutter claw fatigues much more readily than that to the crusher claw at 50 and 100 Hz stimulation in isolated claws. The mean sarcomere length of 8 and 10μm, in fibers of the cutter and crusher opener muscles was significantly different. The electrophoretic pattern of myosin extracted from the cutter opener muscle revealed four bands not found in the crusher opener muscle and a single band in the crusher not seen in the cutter. Thus properties of the opener muscle and its motoneuron differ on the two sides in keeping with the dimorphic nature of the claws.
Metabolic responses of striped bass (Morone saxatilis) to temperature acclimation. I. Alterations in carbon sources for hepatic energy metabolism
Authors: Stone Benjamin B. , Sidell Bruce D. 
Published: June 2005

AbstractThe relative contribution of carbohydrate and lipid to energy metabolism in liver tissue of temperature‐acclimated striped bass was examined in vitro. Respirometry experiments were conducted to assess the role of various endogenous foodstuffs in providing reduced two‐carbon fragments for aerobic metabolism. Liver composition was measured as a reflection of foodstuff flux and storage. Catabolism of 14C‐labeled substrates to 14CO2 was monitored to estimate the tissue capacity for utilization of various classes of compounds. When measured at the temperature of acclimation, oxygen uptake (V̇O2 by liver slices shows near perfect compensation between 15 and 25° C, whereas a 2.75‐fold increase is found between 5 and 15°C. Respiratory quotients (R.Q.) near unity are found at 5° C and decrease to 0.85 and 0.82 at 15 and 25° C, respectively. Inhibition of V̇O2 by iodoacetic acid, a glycolytic inhibitor, is near 60% at 5° C and decreases to 30–40% at 15 and 25° C. Evolution of 14CO2 from 14C‐labeled glucoses and palmitate confirms a conservation of liver tissue capacity for carbohydrate utilization between acclimation temperatures of 5 and 15° C, and an increasing capacity for utilization of fatty acids as temperature increases. Ratios of 14CO2 from 14C‐6‐and 14C‐1‐labeled glucoses indicate a relative increase in the participation of the pentose shunt in carbohydrate metabolism with cold acclimation. The results are consistent with an increasing reliance on carbohydrates for energy metabolism in the cold, whereas lipid substrates are utilized more at warm temperatures. These changes may be adaptive in partitioning energy reserves for seasonal activities of migration and reproduction.
Active immunization of mice with porcine zonae pellucidae: Immune response and effect on fertility
Authors: Sacco Anthony G. , Subramanian Marappa G. , Yurewicz Edward C. 
Published: June 2005

AbstractFemale mice were heteroimmunized with varying dosages of intact and heat‐solubilized porcine zonae. Mouse immune response was monitored by radioimmunoassay and the effect on mouse fertility of circulating antibodies to pig zonae was observed.Porcine zonae were a potent heteroimmunogen in the mouse and, for all dosages studied, the immune response was characterized by a rapid rise in titer, culminating in a peak which was followed by a plateau period of extended duration and of significantly high anti‐zona activity. Maximum immune response was achieved using a dosage of 4000 heat‐solubilized zonae per mouse. Studies involving alteration of immunization regimes, but use of a constant zonae dosage, indicated that maximal response to this antigenic target was obtained using intact zonae applied over a series of injections rather than in a single application.In vitro studies involving proteolytic lysis of or sperm attachment to mouse zonae pretreated with either antibodies to mouse zonae (homologous system) or pig zonae (heterologous system) demonstrated that zona antibodies are considerably more biologically effective in the homologous system.Immunization of mice with pig zonae had no significant effect upon altering mouse fertility. The significance of these fertility results is discussed with respect to the information obtained from the in vitro studies and in respect to the continued consideration of the zona as an immunocontraceptive antigenic target.
Cold lability of mouse sperm binding to zona pellucida
Authors: Heffner Linda J. , Storey Bayard T. 
Published: June 2005

AbstractEpididymal spermatozoa were maintained at 4°C during and after release from the epididymis to assess the effect of membrane fluidity on acquisition by the sperm of the ability to bind to zonae pellucidae of mouse eggs. The hypothesis to be tested was: If membrane fluidity is necessary for acquisition of the ability to bind, then exposure of sperm to 4°C to reduce fluidity markedly should lead to a characteristic delay time in acquiring the ability to bind to zonae. This result was not observed; instead, the relative extent of binding measured at 37°C was decreased relative to control by preincubation at 4°C. The relative extent of binding was reduced to 43% of control after 15 min and to 20% of control after a 60‐min preincubation at 4°C. The loss of binding ability was not reversed by subsequent exposure to 37°C in the insemination mixture for up to 60 min if fresh sperm were dispersed directly from epididymides into the cold medium. Dispersal of sperm into medium at 37°C followed by a 15‐min preincubation at this temperature, during which time sperm acquire the ability to bind to zonae, conferred full protection against cold‐induced loss of binding ability. This loss could not be attributed to motility effects: Mouse sperm are completely immotile if cooled to 4°C, but fully regain their original motility upon warming to 37°C, the temperature of the insemination medium. The binding sites on the sperm plasma membrane for the zona pellucida appear to lose irreversibly their binding ability at 4°C with a half‐time of about 15 min. These results suggest the hypothesis that rearrangement of binding site subunits is involved in the acquisition of the ability to bind to zonae, rather than long‐range interaction of plasma membrane proteins.
Blood oxygen transport of hypoxic Salmo gairdneri
Authors: Nikinmaa Mikko , Soivio Antti 
Published: June 2005

AbstractThe in vivo blood oxygen binding properties of rainbow trout were studied in normoxia and hypoxia (P 55–60 mmHg). Owing to hypoxia the in vivo oxygen dissociation curve of blood was shifted to the left; the P50 value decreased from 37 mmHg in normoxia to 27 mmHg in hypoxia. Hypoxia also caused an increase in the erythrocytic volume, a decrease in the concentrations of ATP and hemoglobin inside the cell, and an increase in the intraerythrocytic pH. All these responses are interrelated. The swelling of the erythrocytes decreased the concentrations of ATP and Hb in the cell. This decrease changed the Donnan distribution of protons across the red cell membrane, thus increasing the intraerythrocytic pH. The increase in the intraerythrocytic pH was the main cause of the increase in the blood oxygen affinity. Owing to the increased blood oxygen affinity the oxygen transport from gills to tissues in hypoxia was only slightly decreased from that in normoxia. However, as the venous oxygen tension decreased in hypoxia, the diffusion of oxygen from tissue capillaries to the cells was probably slowed down in hypoxia when compared to normoxia.
Cellular basis of epiboly of the enveloping layer in the embryo of the medaka, Oryzias latipes. II. Evidence for cell rearrangement
Authors: Kageyama Tetsuo 
Published: June 2005

AbstractThe cell boundaries in the enveloping layer of Oryzias latipes embryos were stained with silver nitrate, and quantitative analyses were made of shape and arrangement of the individual cells at successive stages of epiboly. This provided evidence that extension of the marginal zone of the enveloping layer is accomplished mainly by rearrangement of the component cells throughout the course of epiboly, but during the latter half of epiboly longitudinal elongation of cells was also noted in the marginal zone of the enveloping layer.
Site of gene action of the white allele (Miwh) of the microphthalmia locus: A dermal‐epidermal recombination study
Authors: Pratt Bruce M. 
Published: June 2005

AbstractThe white allele Miwh of the microphthalmia locus, when homozygous, causes a complete absence of neural crest‐derived melanocytes in skin and internal organs. The site(s) of gene action of Miwh on melanoblast differentiation were examined by making dermal‐epidermal recombinant grafts with skin from 13–14‐day embryos of the following genotypes: normal (+/+), heterozygous white (Miwh/+), homozygous white (Miwh/Miwh), and dominant spotting (W/W). Based on results from these grafts, the following conclusions were reached: Miwh/Miwh epidermis is as effective as W/W epidermis in supporting the differentiation of +/+ follicular melanocytes. Miwh/Miwh dermis is completely permissive to in situ differentiation of +/+ follicular melanocytes. Thirteen‐fourteen‐day embryonic Miwh/Miwh skin, both epidermis and dermis, alters or blocks the differentiation of +/+ melanoblasts into dermal melanocytes. By 13 days of development, melanoblasts from both Miwh/+ and Miwh/Miwh skin, even when presented with a permissive W/W environment, are irreversibly redirected into abnormal developmental pathways resulting in either a reduction in follicular pigmentation (Miwh/+) or a complete absence of follicular melanocytes (Miwh/Miwh).
Inhibition of lens regeneration in larval Xenopus laevis
Authors: Cioni Carla , Filoni Sergio , Bosco Luigi 
Published: June 2005

AbstractThe present research aims at showing the role played by the lens in inhibiting lens‐forming transformations of the outer cornea of Xenopus laevis tadpoles. Two types of experiment were carried out: 1) lentectomy and insertion of a Millipore filter disk at the side of the lens, and 2) lentectomy and insertion of a Millipore disk with a central hole. Results indicate that when the lens is replaced by a mechanical obstacle capable of preventing direct communication between vitreous and anterior chambers, definite inhibition of the lens‐forming transformations of the outer cornea occurs. These data strongly suggest that the inhibition exerted by the lens on lens‐forming transformations of the outer cornea in Xenopus laevis eyes is mechanical rather than chemical in nature.
Development of early somitic mouse embryos in static culture in vitro
Authors: Wan Yu‐Jui , Wu Tsung‐Chieh , Damjanov Ivan 
Published: June 2005

AbstractWe have compared the in vitro development of 8.5‐day early somitic mouse embryos cultured in static organ culture dishes in human cord serum or rat serum with the development of embryos of the same age cultured in rotating tubes or developing in vivo. The growth of embryos cultured in rat serum in organ culture dishes was comparable during the first 24 hours, with the growth achieved in rotating tubes and paralleled the embryonic growth in vivo. The morphogenesis of embryos in static organ culture was delayed in comparison with the normal embryogenesis in vivo, but was not statistically different from embryos developing in rotating tube cultures. Embryos cultured for 36 hours continued to grow but were almost all lagging in development behind the embryos developing in utero or in rotating tubes. Our data show that 24‐hour culture of somitic mouse embryos in rat serum may be used to evaluate the growth of explanted embryos, and to study the in vitro development and function of certain embryonic structures, such as somite number, yolk sac circulation, heart function, and development of allantois. Static culture is inadequate for the study or evaluation of neural fold closure, branchial arch formation, anterior limb bud formation, and axial turning of the explanted embryos. Embryo cultures in rat serum yield better results than do cultures in human cord serum.
Biochemical studies of mammalian oogenesis: Possible existence of a ribosomal and poly(A)‐containing RNA‐protein supramolecular complex in mouse oocytes
Authors: Brower Peter T. , Schultz Richard M. 
Published: June 2005

AbstractMouse follicles were labeled with [3H]uridine and then cultured in vitro for 3 days. When oocytes were disrupted, about 40% of the total radiolabeled RNA could be sedimented at 9,000g. Fractionation of this RNA on poly(U)‐Sepharose revealed that about 30% and 60% of the total amount of radiolabeled poly(A)− and poly(A)+ RNA, respectively, were in the pellet fraction. Treatments that disrupt protein structure reduced the amount of 9,000g sedimentable RNA and affected to the same extent the distribution of poly(A)− and poly(A)+ RNA in the pellet and supernatant fractions. CsCl centrifugation of formaldehyde‐fixed pellets revealed that virtually all of the radiolabeled RNA had a density significantly lower than that of ribosomes. The sedimentable RNA appeared not to be polysomal, membrane bound or associated with a cytoskeleton. Agarose gel electrophoresis after poly(U)‐Sepharose fractionation of either the pellet or supernatant revealed the presence of 28S, 18S, 5S + 4S, and heterodisperse poly(A)+ RNA. The size distribution of poly(A)+ RNA in the pellet and supernatant fractions was fairly similar. Pulse‐chase experiments revealed that the stability of poly(A)− RNA in the pellet and supernatant fractions was the same within the experimental error and a similar situation was found for poly(A)+ RNA. RNA in the pellet translated in vitro coded for discrete size classes of protein. Since the relative band intensities were similar for both total and pellet RNA translated in vitro there seemed to be no major partitioning of specific size classes of mRNA into the pellet fraction. These results are discussed in terms of a possible composition of the lattice structures that accumulate during mouse oocyte growth and have been postulated to be a storage form for ribosomes (Burkholder et al., '71).
Genetic control of the hypothalamo‐pituitary axis and the effect of hybridization on sexual maturation (Xiphophorus, Pisces, Poeciliidae)
Authors: Bao Isaac Y. , Kallman Klaus D. 
Published: June 2005

AbstractThe onset of sexual maturity in fishes of the genus Xiphophorus depends upon a multiple allelic series at the P locus. X. helleri of genotype PhPh initiate sexual maturity at 10.4 weeks and X. maculatus of genotypes P3P3 or P4P4 at 8.7 or 20 weeks, respectively. Hybrids between the two species of genotype PhPh and possessing some autosomes of X. maculatus in homozygous condition exhibit precocious maturation at 5.3 weeks and are correspondingly small. PhPh hybrids of the backcross generations to X. helleri mature at the same age and size as X. helleri. The P3Ph and P4Ph backcross hybrids, however, exhibit greatly delayed maturation, and the delay becomes more severe as the number of X. helleri autosomes increases. The phenotype results from the interaction of the P locus with a system of regulatory genes. Both the P factors and the regulatory systems are species‐specific.Synthetic luteinizing hormone‐releasing hormone (LH‐RH) was effective in inducing proliferation and functional activity in the gonadotrops and ultimately sexual maturity in all genotypes, including PhP3 hybrids. Whereas the response of different genotypes to gonadotropin was essentially the same, their response to LH‐RH was significantly different. A positive correlation exists between the rapidity of the response to LH‐RH and the genetically determined age at which spontaneous maturation takes place. The maturity induced by LH‐RH was not permanent. After cessation of LH‐RH administration the gonadotrops became inactive and regressed. These observations suggest that the P locus is not concerned with the production of LH‐RH. Rather, the P locus appears to control the physiological function or the fate of LH‐RH.
Stage dependency of forelimb regeneration on nerves in postmetamorphic froglets of Xenopus laevis
Authors: Korneluk Robert G. , Anderson Meri‐Jo , Liversage Richard A. 
Published: June 2005

AbstractA morphological and histological analysis of the response of forelimb regenerates of Xenopus laevis to denervation is presented. Following forelimb amputation, young Xenopus froglets (3 months postmetamorphosis) consistently regenerated cartilagenous, heteromorphic spikes under conditions of normal innervation. Denervation of forelimbs at 1 or 2 weeks prior to amputation had little effect on the progress of regeneration. Denervation of regenerates at various weekly stages resulted in the inhibition or delay of further regenerative responses and in the regression of any regenerate tissues present at the time of the ablation. Specifically, the formation of the blastema, the initiation of differentiation, and the maintenance of the differentiated state in Xenopus forelimb regeneration were found to require nerves. Following reinnervation some of the denervated forelimb regenerates subsequently reinitiated regeneration, whereas others remained stumped. Stumping was observed histologically to be a function of dermis intervention. These results with Xenopus are discussed and contrasted with previous well‐documented observations of the influence of nerves on appendage regeneration in urodeles.
Temperature, pH, and photoperiod effects upon gemmule hatching in the freshwater sponge, Ephydatia mülleri (Porifera, Spongillidae)
Authors: Benfey Tillmann J. , Reiswig Henry M. 
Published: June 2005

AbstractMature gemmules were isolated from three individuals of the freshwater sponge, Ephydatia mülleri (Lieberkühn), collected near the termination of the Ottawa River near Montreal, Canada. Following a 4‐month period of vernalization, the gemmule populations were incubated to determine the effects of major environmental variables, temperature, pH, and, photoperiod upon hatching rate and hatchability. The three gemmule populations, each assumed to represent genetically identical clones, exhibited significant variation in hatching rate or hatchability under all incubation conditions, with the exception of total absence of hatching at 5°C. Under a 15L/9D photoperiod, individual differences in hatching rate were detected at all pH levels, and individuals were found to differ in the degree of inhibition of hatching (slowing) at low pH (5.3). Exposure to low pH (6.5‐5.8) at low temperature (5°C) for 1 week resulted in depressed hatching rate and hatchability for all three gemmule populations, with clear differences between populations. The shift of photoperiod to 9L/15D resulted in reduced hatching rate in one population and a slightly increased rate in another. These results demonstrate high genetic and physiological variation within a small local population of E. mülleri, and suggest that members of this population are differentially sensitive to environmental change‐particularly to relatively minor decrease of pH level.
Mechanism of univalent antisperm antibody inhibition of fertilization in the sea urchin, Arbacia punctulata
Authors: Saling Patricia M. , Eckberg William R. , Metz Charles B. 
Published: June 2005

AbstractUnivalent antisperm antibodies (IF ab) markedly inhibited the fertilizing capacity of sperm when tested on intact, dejellied, and “demembranated” Arbacia punctulata eggs. Sperm motility and egg jelly penetration were not affected by IFab. Antifertilizin was excluded as the essential sperm antigen involved in the fertilization‐inhibiting action. Sperm pretreated with IF ab did not bind to the surfaces of either dejellied or demembranated eggs, whereas control globulin (CF ab) and seawater‐pretreated sperm bound to such eggs in high numbers. Electron microscopy showed that IF ab‐treated sperm failed to undergo the acrosome reaction. This excluded “bindin” as the essential antigen. Inhibition of fertilization by IF ab was reversed or bypassed by artificial induction of the acrosome reaction with ionophore A23187. It is concluded that univalent antisperm antibody treatment inhibits the fertilizing capacity of sperm by preventing a sperm‐egg interaction that results in the acrosome reaction; consequently, attachment of the sperm to the egg is prevented.
The pale mutation in Bombina orientalis: Effects on melanophores and xanthophores
Authors: Frost Sally K. , Ellinger Mark S. , Murphy Judith A. 
Published: June 2005

AbstractThe pale defect in Bombina orientalis has been examined both biochemically (for pigment defects) and ultrastructurally (for cellular defects). Both xanthophores and melanophores (but not iridophores) are affected by this gene in a manner suggesting that the pigmentation process is inhibited prior to the formation of mature pigment organelles. Of interest is the presence of multivesicular structures in the organelles of mutant xanthophores and melanophores. It is proposed that this mutation acts at the level of a “primordial organelle” common to both pigment cell types.
Changes in the subunit structure of Cancer magister hemocyanin during larval development
Authors: Terwilliger Nora B. , Terwilliger Robert C. 
Published: June 2005

AbstractHemocyanin is present in the megalops and young juvenile stages of the Dungeness crab Cancer magister. The hemocyanin of these early developmental stages resembles that of the adult in molecular weight, appearance in the electron microscope, and copper content. The six subunits of megalops and early juvenile hemocyanins are similar in molecular weight to those of the adult (Mr = 67,000–82,000); however, the larval 25S hemocyanins and the adult 25S hemocyanin each contain one unique subunit. The five other 25S hemocyanin subunits are present in different relative amounts in the youngs crabs than in the adult. The subunit composition of adult 16S hemocyanin includes only five of the six adult 25S subunits. The 16S hemocyanin fractions of the megalops and juvenile crabs are different from adult 16S as well as adult, juvenile, and megalops 25S hemocyanins. This is the first ontogenic structural change in crustacean hemocyanins that has been documented.
Detection of H‐2 antigens on 8‐cell mouse embryos
Authors: Cozad Karen M. , Warner Carol M. 
Published: June 2005

AbstractH‐2 antigens were detected on 8‐cell mouse embryos of the b, k, and d haplotypes, but not on 8‐cell embryos of the a haplotype. the technique used for detection of H‐2 antigens on the embryos was a highly sensitive, automated, complement‐dependent cytotoxicity assay, based on the principle that live embryos will incorporate 3H‐thymidine into DNA, but embryos killed with antiserum and complement will not. The amount of H‐2 present on 8‐cell embryos is apparently less than that present on blastocysts. A possible function of H‐2 antigens in development is proposed.