bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of the thermodilution technique for measuring cardiac output and assessing cardiac stroke volume in crabs
Authors: Burnett Louis E. , de Fur Peter L. , Jorgensen Darwin D.
Published: June 2005

A thermodilution technique is used to measure the flow of hemolymph through the heart of crabs. The technique consists of injecting a small volume of cold filtered sea water into the ventricle and monitoring temperature changes with time in an artery immediately downstream from the heart using a surgically implanted thermocouple. An experimental evaluation of the method affirms that it is a direct measure of the bulk flow of hemolymph through the heart. Values of cardiac output determined in this manner fall within the range of Fick estimates of hemolymph flow made on animals treated similarly. Since measurement of cardiac output by thermodilution can be achieved in a matter of seconds, simultaneous monitoring of heart rate permits the calculation of cardiac stroke volume. In two species of crabs examined, much of the variation in cardiac output is accounted for by changes in stroke volume rather than changes in heart rate.
Metabolism and ultrastructure of dormant podocysts of Chrysaora quinquecirrha (scyphozoa)
Authors: Black Robert E.
Published: June 2005

Oxygen uptake by the podocyst of the scyphozoan, Chrysaora quinquecirrha, is about one‐fourth that of the scyphistoma, based on total protein, but is nearly equal to that of the scyphistoma when calculated on the basis of total DNA. Opening the podocyst cuticle causes a two to threefold increase in oxygen consumption within the first hour.

Podocysts held for 11–13 months at 25°C retain viability, even though more than half of the DNA, one‐third of the protein, and one‐fifth of the lipid are lost. Ultrastructural observations indicate that the cyst contains a population of active cells, with numbers of mitochondria and microvilli, and a mass of internal yolkfilled cells, some of which are lysed and/or phagocytized during dormancy. The active cells acquire many phagocytic vacuoles containing large particles. This may represent a unique mechanism for prolonged survival in the dormant condition.
Effects of ammonia on liver lysosomal functionality in Salmo gairdneri rich
Authors: Arillo A. , Margiocco C. , Melodia F. , Mensi P.
Published: June 2005

Salmo gairdneri specimens were exposed for 4–48 hours to three different concentrations of un‐ionized ammonia (UIA). An increase in lysosomal sensitivity to osmotic shock and in total proteolytic activity occurs in the liver. The amount of this increase depends upon the exposure time or upon environmental and tissue ammonia levels. On the other hand ammonia does not affect lysosome hydrolases activity in vitro.
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

The 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

The 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

Female 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

Epididymal 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

The 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

The 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

The 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

The 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

We 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

Mouse 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

The 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

A 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

Mature 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

Univalent 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

The 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

Hemocyanin 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

H‐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.
Mouse mammary gland DNA synthesis during pregnancy
Authors: Borst David W. , Mahoney William B.
Published: June 2005

Mammary explants from virgin and pregnant Balb/c mice were incubated with 3H‐thymidine, and its incorporation into TCA‐precipitable material was determined. In addition, the labeling index of alveolar and ductal epithelial cells was determined by autoradiography. Incorporation of precursor into mammary tissue from pregnant animals was elevated above that of virgin animals on each day of pregnancy. During pregnancy, there were three periods of peak incorporation (on days 3, 7, and 11‐15). The labeling index of epithelial cells also increased during this period. Ductal cells had a peak labeling index on day 3 (3%), which dropped thereafter to comparatively low levels (3‐6%) for the rest of pregnancy. With the exception of days 1 and 3, the labeling index of ductal cells showed no difference between midnight and noon. Alveolar structures were first observed in histological preparations on day 5 of pregnancy. The labeling index of alveolar cells was higher than that of ductal cells during the rest of pregnancy, and on most days showed a diurnal fluctuation, being greater at midnight than at noon. The labeling index of alveolar cells had peak values at midnight on days 7 (23%) and 11‐13 (20%). This daily fluctuation in DNA synthesis by alveolar cells is a circadian rhythm; pregnant animals continued to show this rhythm after 13 days in constant darkness, and animals maintained on a reversed light schedule had a reversed rhythm. Mammary tissue shows a complex pattern of DNA synthesis during pregnancy, reflecting the different characteristics of ductal and alveolar epithelial cells.
Structural and biosynthetic studies on the two molecular forms of the (Na+ + K+)‐activated adenosine triphosphatase large subunit in Artemia salina nauplii
Authors: Peterson Gary L. , Churchill Lynn , Fisher James A. , Hokin Lowell E.
Published: June 2005

The large subunit of (Na+ + K+)‐activated ATPase from brine shrimp, Artemia salina, migrates as two bands in sodium dodecyl sulfate‐polyacrylamide gels. The slower migrating band, as observed in neutral or alkaline gel systems, is designated α1 and the faster, α2. Structural and biosynthetic studies have been performed to determine if these two bands represent independent molecular forms or precursor products. Peptide mapping of partial proteolytic digests of α1 and α2 showed no distinguishable difference between them, whereas this technique produced very distinct differences in the large subunit derived from three different species. The two large subunit bands also behaved identically when cross linked with cupric phenanthroline either in the presence or absence of digitonin, whereas other proteins in these preparations were unaffected. The peptide mapping and cross‐linking experiments demonstrate that α1 and α2 have identical or nearly identical primary and probably higher order structure. Their different mobilities may be due to post‐translational modification leading, for example, to different oligosaccharide composition. During development of the brine shrimp nauplius, α1 increases in relative abundance while α2 decreases. NaH14CO3 incorporation and pulse‐chase experiments indicate that α1 and α2, as well as the small subunit of the brine shrimp (Na+ + K+)‐activated ATPase, are synthesized at the same time during development and that all changes in the rates of synthesis of these subunits occur at the same time. The apparent rates of degradation of the subunits are also similar. These results are inconsistent with a precursor‐product relationship between α1 and α2.
The developmental potential of mouse 16‐cell blastomeres
Authors: Ziomek C. A. , Johnson M. H. , Handyside A. H.
Published: June 2005

Based on the criteria of relative size and cell surface polarization, subpopulations of outer (larger, polar) and inner (smaller, apolar) blastomeres have been isolated from mouse 16‐cell morulae and reaggregated in groups of 16 cells, and the developmental potential of the aggregates has been assessed both in vitro and in vivo. Aggregates of outer, inner, or mixed groups of cells all formed blastocysts which outgrew and contained both characteristic trophectoderm and alkaline phosphatase positive inner cell masses in vitro. However, significant differences were observed in the timing of blastocyst formation, depending on cell type. Aggregates of outer cells recompacted more slowly, commenced fluid accumulation earlier, and contained more cells at the blastocyst stage than did inner cell aggregates. Aggregates containing both outer and inner cells were intermediate. Postimplantation development of blastocysts derived from aggregates of outer or inner cells, after transfer to pseudopregnant recipients, was normal and comparable to zona‐intact control embryos. This relationship between the expression of different morphological and behavioural properties by the precursor cells of the trophectoderm and inner cell mass and the existence of totipotent cells in both outer and inner subpopulations is discussed.
Changes in mouse oocyte membrane potential and permeability during meiotic maturation
Authors: Douglas Powers R.
Published: June 2005

Mouse oocytes spontaneously undergo meiotic maturation when removed from the ovary and cultured in vitro. This paper describes the changes in cell surface membrane potential from the germinal vesicle (GV) stage (− 46 mV, inside negative), through germinal vesicle breakdown (GVBD) (− 31 mV), to the polar body (PB) stage (− 17 mV). Radioisotope tracer flux experiments established the total exchangeable internal K at the GV stage in 190 mM, the K efflux rate coefficient as 6.7 × 10−5 sec−1 and the K permeability as 46.7 × 10−8 cm sec−1. In comparison with previous results with PB stage oocytes, this suggests that the membrane potential depolarization is caused largely by a decrease in K permeability. When GVBD is blocked with 0.11 mM dibutyryl cyclic AMP, the membrane potential does not depolarize. This suggests a linkage between depolarization and GVBD. However, incubation in 80 mM K medium, which depolarizes the oocyte, does not trigger GVBD. It is concluded that membrane depolarization by itself is not sufficient to cause GVBD.
Hemocyanin‐oxygen affinity in hermit crab blood is temperature independent
Authors: Jokumsen Alfred , Weber Roy E.
Published: June 2005

The oxygen affinity of the blood of the hermit crab Pagurus bernhardus is temperature independent at constant physiological pH (7.8 to 8.0) reflecting zero overall heat of oxygenation under these conditions. Combined with the absence of an indirect temperature effect (via changed in vivo pH), this represents a unique situation compared with previously investigated hemocyanins, and reflects adaptations to stabilize hemocyanin O2 loading in the thermolabile natural environments.
Bovine serum albumin, sperm motility, and the “dilution effect”
Authors: Harrison R. A. P. , Dott H. M. , Foster G. C.
Published: June 2005

Epididymal spermatozoa from rabbit and ram were washed either once or twice using an efficient washing procedure and were then diluted in various media to a final concentration of approximately 1.4 × 107 cells/ml and incubated at 30°C for up to 12 hours. Bovine serum albumin (BSA), either untreated or defatted, was found to be better than polyvinylpyrrolidone, ovalbumin, or α‐lactalbumin, both at stimulating and maintaining motility levels and at reducing the tendency of the washed spermatozoa to stick to glass. BSA was effective in all media tested, being independent of Ca2+, PO43−, HCO3−, and ionic strength.

BSA has a reversible stimulatory effect on motility. If BSA was added to sperm suspensions 3½ hours after they had been washed and diluted in protein‐free medium, motility was stimulated to levels not significantly lower than those observed in samples that had been washed and diluted in the presence of BSA. However, samples washed into BSA and then washed free of it behaved essentially as though they had never been in contact with the protein.

The motility, survival, and response to BSA of twice‐washed spermatozoa were the same as those of once‐washed spermatozoa, showing that epididymal plasma factors are not required for survival in vitro. It was concluded that dilution is not essentially detrimental to rabbit and ram spermatozoa. However, severe dilution of semen may result in levels of male reproductive tract fluids insufficient either to stimulate motility or to prevent sticking of motile cells to container surfaces. Few motile spermatozoa are recovered from samples of such diluted semen.
Infertility in bitches induced by active immunization with porcine zonae pellucidae
Authors: Mahi‐Brown Cherrie Ann , Huang Thomas T. F. , Yanagimachi Ryuzo
Published: June 2005

In a study designed to evaluate the contraceptive potential of anti‐egg zona pellucida immunization, bitches were injected with isolated and solubilized zonae pellucidae of either the pig or the dog in saline and Freund's adjuvant or with saline and adjuvant alone (controls). They were boosted monthly, and serum samples were collected before the first injection and 10 days after each injection. The titers of anti‐zona pellucida antibodies in each serum sample were measured by treating fresh canine oocytes with the serum, then evaluating antibody binding as indicated by indirect immunofluorescence, precipitation of the zona surface, and penetrability of the zonae by spermatozoa in vitro. The bitches were bred when they came into estrus.

All three bitches immunized with porcine zonae developed high titers (1:10,000 or more by indirect immunofluorescence) of antibodies that cross‐reacted with canine zonae to cause precipitation of the zona surface both in vivo and in vitro and that completely inhibited penetration of the zonae by spermatozoa in vitro. The two bitches immunized with canine zonae developed only low titers, and their sera had little or no effect on treated zonae. The two control bitches did not develop anti‐zona antibody. None of the bitches immunized against porcine zonae became pregnant when bred, but one bitch immunized against canine zonae and one control did become pregnant. The bitches immunized with porcine zonae had somewhat abnormal cycles for unknown reasons. Thus, we could not establish with certainty whether the infertility resulted from specific interference with fertilization, as in vitro, or from alterations in ovarian function, or both.
Changes in temperature tolerance during the development of Xenopus laevis embryos
Authors: Nelson Lennart , Mild Kjell Hansson , Løvtrup Søren
Published: June 2005

Determinations of the temperature tolerance of embryos of Xenopus laevis during the course of development show that the lower limit of the tolerance range declines from 11 °C to 6 °C as the embryo undergoes gastrulation; subsequently no further changes occur. The mechanism involved is unknown; possibly an increase in the proportion of unsaturated fatty acids in the lipids of the cell membrances is responsible.
Cytochemical demonstration that acrosin is unavailable in intact ejaculated boar and bull spermatozoa
Authors: Berruti Giovanna , Martegani Enzo
Published: June 2005

The cytochemical localization of acrosin (EC 3.4.21.10) was investigated using a fluorescent technique, based on the use of fluorogenic substrates, derivatives of 4‐methoxy‐β‐naphthylamine, which liberate a fluorescent tag that, if coupled to 5‐nitrosalicylaldehyde, generates an insoluble, fluorescent product. From the data obtained from boar and bull spermatozoa that had been subjected to different treatments, we have found that the acrosomal, trypsinlike proteinase is practically inaccessible in intact, freshly ejaculated spermatozoa. Acrosin activity was detected after subjecting the spermatozoa to a treatment that simulates the process they undergo at the moment of fertilization, showing a particulate localization in the acrosome of some of the spermatozoa.
The role of androgens in follicular development in the ovary. I. A quantitative analysis of oocyte ovulation
Authors: Ware Vassie C.
Published: June 2005

In an attempt to understand more fully processes that control the selection or recruitment of follicles for ovulation, the superovulation paradigm in combination with the androgen, 5α‐dihydrotestosterone, or the antiandrogens, cyproterone or cyproterone acetate, was used in the immature mouse to alter the developmental potential of follicles destined to ovulate or to become atretic. Quantitative analysis of the numbers of eggs ovulated after one or more rounds of stimulation by pregnant mare's serum gonadotrophin followed by human chorionic gonadotrophin (PMSG‐hCG), revealed a dose‐dependent ovulation response to exogenous androgen and antiandrogen. Low dosages of androgen improved the ovulation response significantly. Large dosages of cyproterone and cyproterone acetate (100 mg/kg body weight) generally decreased the ovulation number in gonadotrophin‐injected mice, suggesting a role for androgen in preovulatory events that occur within the ripened follicle after the ovulatory stimulus (hCG) has been received. Low dosages of cyproterone, particularly 25 mg/kg, significantly enhanced the ovulatory response, a phenomenon not observed for cyproterone acetate at this dosage. Radioimmunoassays of serum LH suggested that the differential response of the ovary to the two antiandrogens was probably related to endogenous LH release. Experiments in which the time of administration of hCG± cyproterone was varied after PMSG priming suggested that cyproterone at a dosage of 25 mg/kg had a “rescuing” effect on follicles destined to become atretic for up to 96 hr after PMSG priming. Cyproterone at a dosage of 100 mg/kg had no such effect, and actually decreased the magnitude of the ovulatory response at all time points tested, suggesting that follicular atresia was accelerated by this treatment. Experiments in which the time of administration of cyproterone (100 mg/kg) was varied after hCG suggested that whatever the important androgen‐mediated events preceding ovulation, these events occur within 2 to 3 hr after the hCG signal. By quantitating the numbers of eggs over several superovulation cycles, it could be shown that hormonal treatment in one induced cycle could affect significantly the ovulation response in subsequent cycles, suggesting that androgens influence the development of classes of follicles other than preovulatory follicles. These studies suggest that the process through which follicles are selected for ovulation is extremely sensitive to the androgenic environment and that the developmental pathways leading to ovulation or preovulatory follicular atresia are closely linked.
Termination of seasonal breeding in the photoperiodic weaver bird
Authors: Chandola Asha , Chakravorty Krishna
Published: June 2005

Termination of seasonal breeding in the photoperiodic weaver bird does not occur as a result of photorefractoriness, and yet, in nature birds become refractory. Earlier studies indicated a seasonal variation in photosensitivity of this bird during the reproductive cycle and it was suggested that setting of the photoperiodic response threshold at a higher level might explain gonadal regression. Such a possibility was now examined by keeping birds in constant 13L/11D (the near maximal day length at Varanasi, India) and 15L/9D simultaneously for over 8 mo. While breeding in birds in 15L/9D continued, gonads regressed in 13L/11D indicating that the day length which was stimulatory in spring is no more sufficient to permit gonadal activity. Cyclicity in 13L (and in artificial 12L as well as natural daylength) may be explained on the basis that these schedules exceed the basic photoperiodic response threshold—hence the initiation of gonadal development. Once the gonads are developed due to decline in photosensitivity (caused perhaps by sex hormones) gonadal regression occurs, thus resulting in reproductive periodicity.
Mouse embryos and uterine epithelia show adhesive interactions in culture
Authors: Morris John E. , Potter Sandra W. , Buckley Patricia M.
Published: June 2005

To investigate the cellular mechanisms in preimplantation adhesion of the mammalian blastocyst to uterine epithelium, it is essential to avoid the complexities of the maternal environment but at the same time prevent the introduction of competing artificial surfaces, to which embryos preferentially adhere. We demonstrate here that sealed vesicles of isolated uterine epithelium cultured together with blastocysts in hanging drops provide an optimum system for encouraging and observing the adhesive interactions. The responses of the embryonic and maternal cells were identical to those known in vivo. Microvilli were seen on both surfaces, and in places the membranes were drawn into close apposition with some desmosomelike junctions. After blastocyst adhesion occurred trophoblast cells invaded the epithelium and showed phagocytic activity, closely resembling the invasion that follows adhesion during normal pregnancy in mice.
The truth about saturation deficiency—an historical perspective
Authors: Edney E. B.
Published: June 2005

Studies on the water relationships of arthropods originated from the needs of applied entomology early in this century. Saturation deficiency (S.D.) was hailed as a measure whereby the effects of temperature and humidity on transpiration, and thus on development and longevity, could be simply combined. Errors in curve fitting and lack of physiological knowledge led to early misconceptions, but S.D. helped to focus attention on the need for laboratory analysis of field data and played a part in the move toward a more scientific approach leading to a great expansion of the whole field. Application of the concept to arthropods has usually been controversial, and examples of this drawn from the literature on the bionomics of the plague fleas and on cuticular waterproofing are discussed. A controversy exists at present concerning S.D. and the physics of transpiration. The concept of S.D. has been most useful where it has stimulated research to find out how arthopods avoid its consequences.
Why don't tobacco hornworms (Manduca sexta) become dehydrated during larval‐pupal and pupal‐adult development
Authors: Jungreis Arthur M. , Ruhoy Michael , Cooper Paul D.
Published: June 2005

Studies of water loss during metamorphosis of insects have usually been confined to the pupal stage where both cuticular and respiratory control of transpiration have been reported. In Manduca sexta and other lepidopterans, preparation for pupation actually begins several days before pupation when the animals stop feeding and begin searching for an appropriate pupation site, a burrow for M. sexta. This study examines some aspects of water balance maintenance from the initial period of searching to the final time of eclosion. Behavior is important for reducing water loss, as animals which fail to find an appropriate pupation site continue to lose water at twice the rate of animals which are burrowed (10 vs. 5 mg H2O/g·h). Part of this is explained by exposure to light as unburrowed animals in constant dark are intermediate in water loss. The epicuticle during the pupal stage reduces water loss rate eight to tenfold, removal causing animals to lose water at 4 mg (g·h)−1. M. sexta does appear to be capable of storing water in preparation for metamorphosis, since individually raised animals consistently have water contents higher than animals reared in large groups. A drop in water loss during the larva‐pupal development is correlated with increased hemolymph ecdysone titer, although how is unknown. Pupal water loss can be divided into cuticular and respiratory pathways, with cuticular loss accounting for two‐thirds of 0.7 mg H2O (g·h)−1 loss rate. Finally, an increase in hemolymph osmotic pressure just prior to ecdysis may aid in reclamation of molting fluid.
Control of ion reabsorption in locust rectum: Implications for fluid transport
Authors: Phillips J. E. , Meredith J. , Spring J. , Chamberlin M.
Published: June 2005

Hormonal control of fluid reabsorption in the rectum is a major mechanism of water balance homeostasis in terrestrial insects. We report that steady‐state fluid transport in the absence of, or against, an osmotic gradient can be driven by absorption of Na+, K+, or Cl− from the lumen. Therefore chloride transport stimulating hormone (CTSH), a newly discovered hormone which stimulates KCl reabsorption by elevating tissue cAMP, might enhance fluid absorption indirectly by its action on transport of the major solute. This prediction was not confirmed and explanations are discussed. Rectal tissue volume increases considerably during the first hour in vitro and this epithelia only switches from slow transport of primarily NaCl to rapid absorption to predominantly KCI (the in vivo situation) after stimulation. Metabolic support of KCl transport depends largely on proline absorption from Malpighian tuble fluid entering the rectum. Since these specific requirements and properties of in vitro rectal preparations were not known during earlier investigations, most reports of putative diuretic and antidiuretic factors acting on rectal fluid transport in vitro require reexamination and confirmation.
Prolactin induces increase in the specific gravity of salamander, Hynobius retardatus, that raises adaptability to water
Authors: Moriya Tsuneo
Published: June 2005

The migration of the salamander, Hynobius retardatus, from land to water, which normally occurs in the breeding season, was induced by the injection of prolactin. The migration was accompanied by certain morphological changes (wider tail or swollen body); the observed morphological changes resembled those of salamanders collected from ponds during the breeding season. The prolactin‐treated salamanders sank to the bottom of the water. In contrast, the control salamanders that did not receive prolactin floated near the water surface. The specific gravity of the whole body of the prolactin‐treated animals was greater than unity. Prolactin injection induced a remarkable enlargement of the tissue between the skin and muscle, in which a considerable amount of mucopolysaccharide‐rich substance accumulated. Because of the hydrophilic nature of the mucopolysaccharides, the increased mucopolysaccharide may absorb more water, which, in turn, may result in an increase of the osmotic pressure of the serum. This may eventually cause the animals to migrate from land to water to quench the “thirst.” The absorption of water may make the specific, gravity greater, and this allows the animals to sink in water.