bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hormone‐independent GVBD induces cytoplasmic maturity in the starfish oocyte
Authors: Guerrier P. , Meijer L. , Moreau M. , Longo F. J. 
Published: June 2005

AbstractIn the absence of hormone (1‐methyl adenine, 1‐Ma) oocytes from three different species of starfish have been induced to undergo cytoplasmic maturation, including polar body extrusion, sperm aster differentiation, and pronuclear development by mechanical disruption of the germinal vesicle. The factors responsible for aster and pronuclear differentiation appear to develop independently of protein synthesis as observed following an incubation in cycloheximide. The effect of the drug diamide suggests, however, that phosphorylation of preexisting proteins might be involved in this process. While 1‐Ma applied to fertilized, enucleated oocyte fragments is only able to induce sperm aster differentiation without male pronuclear development, both processes occur under the influence of nucleoplasm, without previous hormone treatment. These results suggest that substances originating in the germinal vesicle induce cytoplasmic maturation, i.e., the development of polar bodies, sperm asters, and pronuclei, and question whether there is a direct role of the maturation promoting factor in these processes.
Functional capacity of sex‐reversed (XX, Sxr/ +) mouse germ cells as shown by progeny derived from XX, Sxr/ + oocytes of a female chimera
Authors: Bradbury Michael W. 
Published: June 2005

AbstractMice of the genotype X/X, Sxr/ + (Sex‐reversed) are sterile phenotypic males. Testis size is reduced and there is a failure of spermatoge‐nesis during meiosis I. A female chimeric mouse has been produced whose germ line is entirely composed of X/X, Sxr/ + germ cells. The progeny of this chimera included several XX, Sxr/ + males. The finding that X/X, Sxr/ + germ cells can produce fully functional oocytes has implications for the function of the Sex‐reversed gene, the control of germ cell differentiation, and the role of germ cells in primary sex determination.
Postlarval changes in the external morphology of dactyl setae in the kelp crab, Pugettia producta (randall)
Authors: Hamilton K. A. 
Published: June 2005

AbstractMorphological changes, which include growth, encrustation, and abrasion, occur in the sensory setae and nonsensory denticles located on the dactyls of the walking legs during the postlarval development of the kelp crab, Pugettia producta (Randall). The growth of the denticles is isometric (slope ∼ 1), while the growth of the setae is negatively allometric (slope < 1), relative to the growth of the dactyls. The increase in the sizes of the setae, but not of the denticles, appears to slow before growth stops at maturation, when molting ceases. The most striking morphological changes in the setae occur after maturation. While the setae of all but recently molted juvenile crabs are heavily encrusted by epibionts, the dactyls of most mature crabs are clean, and both the setae and denticles are so abraded that only their bases remain. The consequences of these morphological changes are discussed in relation to the sensory capabilities of a long‐lived, nonmolting majid crab.
Oogenesis in Fundulus heteroclitus. III. Vitellogenesis
Authors: Selman Kelly , Wallace Robin A. 
Published: June 2005

AbstractSeveral physiological parameters associated with oocyte growth (vitellogenesis) in the killifish, Fundulus heteroclitus, are defined. Hepatocytes from females and estrogen‐treated males are highly synthetic cells, whereas those from males are relatively quiescent. A 200,000‐molecular weight phosphoprotein (vitellogenin) has been identified by sodium dodecyl sulfate (SDS)‐gel electrophoresis in the plasma of females and estrogen‐treated males and isolated chromatographically using a potassium phosphate gradient system on DEAE‐cellulose. To inhibit proteolysis, the nontoxic inhibitor, aprotinin, was injected into fish prior to bleeding. The structure of vitellogenic follicles and the process of oocyte growth are described. Once follicles reach a diameter of 0.5 mm, their oocytes incorporate exogenous materials by micropinocytosis and sequestered material is immediately translocated to yolk spheres in the oocyte cortex. This process has been followed by using the tracer horseradish peroxidase. Exogenous proteins appear to leave the perifollicular capillaries via an intercellular route and pass through intercellular channels within the follicular epithelium and patent pore canals of the vitelline envelope before reaching the oocyte surface. [32P]Vitellogenin isolated from F. heteroclitus, [3H]vitellogenin isolated from X. laevis, and the dye trypan blue have been used to determine which sized follicles are vitellogenic (i.e., incorporate exogenous materials into growing oocytes). Morphological and autora‐diographic studies are presented to confirm that sequestered macromolecules are incorporated into yolk spheres in the growing oocyte. Follicles appear to grow from 0.5 to 1.3 mm in diameter due to vitellogenesis and subsequently undergo an additional increase in size, which is primarily due to hydration, during oocyte maturation (Wallace and Selman, '78).
Influence of the hydric environment on sexual differentiation of turtles
Authors: Gutzke William H. N. , Paukstis Gary L. 
Published: June 2005

AbstractPhenotypic sex of hatchling painted turtles (Chrysemys picta), a species known to exhibit temperature dependent sex determination, is influenced by the hydric environment to which developing embryos are subjected. Hatchling sex ratios vary significantly over the range of 26.5 to 28.5°C due to effects of the hydric environment.
A comparative study of tentacle regeneration and number in symbiotic and aposymbiotic Hydra viridis: Effect of zoochlorellae
Authors: Rahat Menachem , Reich Vanda 
Published: June 2005

AbstractThe effect of symbiotic zoochlorellae on tentacle number and budding in Swiss and Israeli strains of Hydra viridis in the light and in the dark, in normally grown and in regenerating specimens has been studied. The mean tentacle number in symbiotic and aposymbiotic hydra was 8.65 ± 1.05 and 7.48 ± 0.86 in the Swiss strain, and 8.62 ± 1.29 and 6.66 ± 0.72 in the Israeli strain. In aposymbiotic hydra reinfected with zoochlorellae isolated from either strain, the number of tentacles increased to that of symbiotic hydra. Decapitated symbiotic hydra regenerated more tentacles than aposymbionts, and regenerating Swiss symbionts also formed more buds than their respective aposymbiotic hydra. The algal enhancing effect was found in the light and in the dark. Regeneration rate was initially higher in the symbiotic hydra, and the ratio between the number of tentacles formed by the regenerating symbiotic and aposymbiotic hydra varied daily during the experimental period of 7 days. We conclude that in H. viridis the endosymbiotic zoochlorellae exert a significant stimulatory and morphogenic effect in the light and in the dark. We do not know yet how the algal effect is mediated to their host. We suggest that a distinction should be made between the stimulatory effect on regeneration rate and the morphogenic effect on the final number of tentacles or buds.
Developmental physiology of corpora allata and accessory sex glands in the cecropia silkmoth
Authors: Shirk Paul D. , Bhaskaran Govindan , Röller Herbert 
Published: June 2005

AbstractThe storage of large quantities of juvenile hormone (JH) in adult male Cecropia silkmoths is dependent upon the combined activities of two organs: secretion by the corpora allata (CA) and accumulation by the accessory sex gland (ASG). We describe here some aspects of CA‐ASG development and physiology which lead to JH storage.The ASG were found to have completed development and had secreted the luminal materials before eclosion. After day 16 of adult development, the ASG were able to convert JH‐I acid to JH‐I and store the JH‐I. When incubated in vitro, the ASG showed a specificity for the uptake and storage of the three JH acids in the following order : JH‐I > JH‐II ≫ JH‐III. The CA of male and female larvae secreted JH‐I and JH‐II when incubated in vitro, whereas adult male CA secreted JH‐I acid and JH‐II acid. The total equivalent synthetic productivity of adult male CA was found to be considerably greater than that of adult female CA. When cultured in vivo during metamorphosis to the adult in hosts of the opposite sex, the male and female CA maintained their respective pattern of secretory activity. Thus, the CA appear to be programmed to express the sexually dimorphic activity prior to the initiation of adult development.
Polyspermy inhibition in the oyster, Crassostrea virginica
Authors: Alliegro Mark C. , Wright David A. 
Published: June 2005

AbstractInhibition of polyspermy is a critical response during fertilization which ensures that only one sperm nucleus will fuse with the female pronucleus to restore the diploid state. Oyster (Crassostrea virginica) eggs prevent polyspermy by a process occurring at the cell surface. However, 5 min after fertilization, there are still functional sperm receptor sites available for penetration by supernumerary sperm. Reinsemination experiments indicate that there is no decrease in the number of penetration sites during this interval. Yet, the number of sperm entering eggs is restricted to one per fertilized egg at a sperm:egg ratio of 1000:1. At a sperm:egg ratio of 105:l, an average of only six sperm were able to penetrate each egg. Gamete binding experiments indicate that there is a gradual decrease in the number of sperm bound to eggs starting at approximately 75 sec and continuing until all sperm are detached. Since eggs are fertilized within seconds of insemination and this process takes at least 12 min, it is considered an unlikely mechanism for the polyspermy block. There are no ultrastructural correlates to the polyspermy block nor to the unbinding of sperm, such as secretion of cortical granules or fertilization envelope formation. Based on reinsemination experiments, kinetic data, and ultrastructural observations, we suggest a physiological block to polyspermy which prevents fusion of gamete plasma membranes, and is mediated by an inhibitory effect directly upon the sperm.
Detection of differences in surface carbohydrates of unfertilized and fertilized golden hamster eggs using potato agglutinin
Authors: Oikawa Taneaki , Maruyama Yuko 
Published: June 2005

AbstractChanges in the surface carbohydrate moieties of zonae pellucidae and naked vitelli isolated from unfertilized and fertilized hamster eggs were examined through potato agglutinin (STA)‐mediated agglutination and binding of FITC‐STA as a marker. The results indicated that the stereochemical properties of the saccharide residues within STA‐binding sites on the outer surface of the zona pellucida, inner region of the zona pellucida, and the surface of the ooplasmic membrane were different in unfertilized and fertilized eggs, that part of the differences between the two kinds of eggs could be visualized with FITC‐STA and that, on the basis of these data, if we use STA as a probe to analyze the surface change following fertilization, we may be able to analyze these changes to a substantial degree.
Ascidian one‐half embryos can develop into functional adult ascidians
Authors: Nakauchi Mitsuaki , Takeshita Toshikazu 
Published: June 2005

AbstractAlthough adult ascidians have remarkable regenerative potency, the ascidian egg is considered a typical “mosaic” egg. A single blastomere isolated at the two‐cell stage develops into a half tadpole with minor or major defects, and this rigidity of ascidian development is known to depend on the localization of cytoplasmic determinants. Between the egg and adult, the ascidian larva has a dual nature consisting of differentiated cells for larval activities and undifferentiated cells that later become differentiated and function in the adult. Although ascidian larvae derived from a hemiembryo are deficient, no one has yet investigated the possibility that the adult might have regulative powers not present in the embryo and might be able to form an entire adult ascidian. Using Styela plicata, we have approached this problem. We report here for the first time that ascidian half embryos can form tadpoles that have the potency to hatch, metamorphose, and develop into functional ascidians.
The incorporation of unsaturated fatty acids of the n‐9, n‐6, and n‐3 families into individual phospholipids by isolated hepatocytes of thermally‐acclimated rainbow trout, Salmo gairdneri
Authors: Hazel Jeffrey R. 
Published: June 2005

AbstractRates of incorporation of 1‐14C‐oleic (18:1n9), ‐linoleic (18:2n6), and ‐linolenic (18:3n3) acids into individual phosphatides were determined in isolated hepatocytes from cold (5°C)‐ and warm (20°C)‐acclimated rainbow trout, Salmo gairdneri. Fatty acid incorporation into phosphatidylcholine (PC) exceeded that into all other phospholipids, but at assay and acclimation temperatures of 5°C, incorporation into phosphatidylethanolamine (PE) was generally intermediate between that of PC and the remaining phosphatides. Specific radioactivities (ratios of percentage isotope incorporation‐to‐mole percentage of phosphatide) were consistently less than one for both PC and PE, and greater than one for phosphatidic acid (PA), lysophosphatidylcholine (LPC), phosphatidylserine (PS), and cardiolipin (CL). For PS, specific radioactivities were greater in cold‐ than warm‐acclimated trout, and greater at 5°C than 20°C. Rates of oleate incorporation were generally higher, and rates of incorporation of 18:2 and 18:3 lower in cold‐ than warm‐acclimated trout. Most phospholipids demonstrated a clear preference for the incorporation of 18:2 when assayed at 20°C; however, at 5°C the incorporation of 18:2 was reduced and 18:3 was generally the preferred substrate A reduction in assay temperature from 20°C to 5°C also shifted the incorporation of 18:2 away from PC into PS and PA. These data were interpreted to indicate 1) a cold‐induced activation of PS metabolism, possibly resulting in elevated levels of PE; 2) lower rates of general acyl group turnover in animals acclimated to 5°C than 20°C; 3) a specificity to the acclimation response that favors the incorporation at cold temperatures of polyunsaturated fatty acids, but not the parent acids from which they are derived; and 4) the participation of a deacylation‐reacylation cycle in the metabolism of phospholipids, particularly at cold temperatures.
Calcium concretions in the gills of a freshwater mussel serve as a calcium reservoir during periods of hypoxia
Authors: Silverman H. , Steffens W. L. , Dietz T. H. 
Published: June 2005

AbstractThe gill of the freshwater mussel, Ligumia subrostrata, is composed of 25% calcium concretions on a dry weight basis. These concretions are located extracellularly in the connective tissue of the gill. The concretions have a lamellar structure and occur singly, multiply, and in clumps. The concretions are composed primarily of calcium phosphate and an organic matrix. The concretions are more numerous toward the base of the gill and less frequent in the tip of the gill. The average size of the concretions is 2–3 μm. The concretions are not solubilized in animals exposed to prolonged hypoxic conditions. Instead, as calcium increases in the blood under hypoxic conditions the percentage of the gill dry weight attributed to concretion material increases and the calcium content of the concretion material is elevated. The calcium content of the concretions also is inversely correlated with blood pH. This study indicated that the concretion material in the gills was not mobilized under hypoxic conditions, but served as a calcium reservoir during periods in which the animal was liberating calcium from other sites.
The relationship between motility and the FITC‐BSA binding properties of mouse epididymal spermatozoa
Authors: Stanger J. D. , Quinn P. 
Published: June 2005

AbstractMouse epididymal spermatozoa exposed to fluorescein isothio‐cyanate‐conjugated bovine serum albumin (FITC‐BSA) immediately following dilution or after a 2‐hour incubation period under fertilization conditions, were assessed by fluorescence microscopy for albumin adsorption. Motile spermatozoa exhibited light fluorescence in the midpiece and tail but not in the head. In contrast the majority of nonmotile spermatozoa displayed a strong and characteristic fluorescence in the post acrosomal region of the sperm head as well as the midpiece. Spermatozoa immobilised by short‐term heat stress exhibited fluorescence in the post acrosomal region and midpiece as before but also in the acrosomal cap. The equatorial region failed to fluoresce. The significance of these observations on the involvement of albumin in capacitation is discussed.
Effect of hypoxia and body size on the energy metabolism of lungless tadpoles, Bufo woodhousei, and air‐breathing anuran larvae
Authors: Feder Martin E. 
Published: June 2005

AbstractUnlike most anuran larvae, tadpoles of Bufo woodhousei (toads) lack lungs. To investigate the consequences of lunglessness and its interaction with the body size of larvae, resting and active tadpoles were exposed to hypoxia. In resting larvae, rates of O2 consumption (\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document}) were proportional to aquatic PO2, even though larvae increased buccopharyngeal ventilation considerably in hypoxia. Whole body lactate concentrations increased only in severe hypoxia. Hypoxia also depressed the \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} of active larvae, which accumulated lactate even in normoxic water. Air‐ and water‐breathing tadpoles (Rana berlandieri and Xenopus laevis) can maintain greater routine \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} in hypoxia than can Bufo tadpoles. However, Bufo tadpoles can extract more O2 from hypoxic water than can Rana and Xenopus tadpoles, when all are breathing only water.The critical Po2 of active larvae and the gill ventilatory frequency of resting larvae were proportional to body size. By contrast, large and small Bufo tadpoles were similar in routine \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} in hypoxia, the ration \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} max:\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^{\rm .} {\rm o}_{\rm 2} $\end{document} routine, and tolerance of hypoxia. Also, small tadpoles accumulated more lactate than large tadpoles when swimming at similar absolute velocities for the same times. Thus, lunglessness apparently does not limit the size of Bufo tadpoles by forcing reliance upon cutaneous gas exchange.
Current problems in human in vitro fertilization and embryo implantation
Authors: Nayudu P. L. , Lopata A. , Leung P. C. S. , Johnston W. I. H. 
Published: June 2005

AbstractRecently, in several centers, there have been striking in creases in the pregnancy rates from human in vitro fertilization (IVF). Some of the improvements are 1) refinement and individualization of ovulation induction with clomiphene citrate and human menopausal gonadotropin and timing of hCG administration, aided by monitoring of plasma estradiol, cervical mucus characteristics, and follicle size and number; 2) preincubation of oocytes before insemination; 3) improvements in embryo transfer procedures, including smaller diameter catheters, smaller fluid volume, and the inclusion of a high proportion of serum in the transfer medium.Although there are still unresolved problems at all stages it would be of significant assistance to the induction and culture if a noninvasive monitor of oocyte maturity and health were available. The appearance of the living oocyte under the light microscope has proved of limited diagnostic value.With this aim in mind, the microscopic appearance of cumulus cells and follicular fluid protein levels have been assessed with respect to their usefulness in indirect oocyte assessment. Follicular fluid proteins from patients who had become pregnant after the transfer of a single embryo have been separated by broad spectrum pH isoelectric focusing. The complex band profiles were quantitated by laser beam densitometry.Statistical analyses of the results, grouped according to the performance of the oocyte and resulting embryo following IVF, indicate that there are differences between the groups in which the oocytes fertilized, cleaved, and produced pregnancies and those which did not. Further studies are underway to assess the predictive value of the individual isoelectric focusing profiles. Also being investigated is their possible usefulness in monitoring ovulation induction regimens.
In vitro development of the mammalian embryo
Authors: Sanyal Mrinal K. , Naftolin Frederick 
Published: June 2005

AbstractNormal growth and differentiation of mammalian embryos in vitro during the preimplantation period appear to be dependent upon the availability of appropriate metabolic substrates. For preimplantation embryos, defined conditions of culture have been achieved only in a few laboratory species. There is now evidence that differentiation factors isolated from fetal calf serum and human placental cord serum may promote further development of blastocysts. Postimplantation rat and mouse embryos can be cultured during the organogenesis period with rat or human sera in roller bottles. The embryonic differentiation of the rat at this stage of development is progressively retarded in such cultures with male rat serum. The embryonic development is not improved, even in sera obtained from rats at different days of gestation (12, 15–16, and 20–21). Inability to grow placental tissues simultaneously with embryos, accumulation of unfavorable substances, and rapid depletion of nutrients contribute to the retardation of embryonic growth. To improve growth and differentiation of conceptuses, a continuous culture system with the possibility of infusion of increasing concentrations of oxygen in the roller bottle gas atmosphere has been developed. This improved method allows considerable continuous growth and differentiation from the neurula stage with development of numerous primary organs.Utilizing these in vitro culture methods during pre‐ and postimplantation periods, it is now possible to assess embryotoxic or teratogenic potential of drugs and chemical agents. The postimplantation culture procedure allows a more precise assessment of mechanisms associated with anomalous embryonic differentiation. Bioactivation of teratogens and effects of active toxic metabolites on organ primordium differentiation have been shown by combining embryo culture with a hepatic microsomal activating system. Microinjection of teratogens and cells into conceptus compartments is being used to elucidate specific anomalous differentiation processes.