bluuebunny/crossref_metadata_2025_split huggingface dataset:
ATP‐γ‐S (adenosine 5′‐0(3‐thiotriphosphate)) blocks progesterone‐induced maturation of the Xenopus oocyte
Authors: Bellé R. , Boyer Jeanne , Ozon R. 
Published: June 2005

AbstractATP‐γ‐S microinjection into Xenopus oocyte prevents progesterone induced maturation. Inhibition is time and dose dependent; 50% inhibition occurs when 50 nl of 0.5 mM ATP‐γ‐S solution are microinjected/oocyte 1 hr prior to the hormonal trigger. ATP‐γ‐S inhibited oocytes can be induced to mature (100%) following microinjection of extracts containing maturation promoting factor (MPF). Our results suggest that the maturation protein(s) has been stabilized in ovo by ATP‐γ‐S microinjection, in its phosphorylated inhibitory form.
Partial characterization of the cytosolic and mitochondrial aspartate aminotransferase from ribbed mussel gill tissue
Authors: Paynter Kennedy T. , Hoffmann Richard J. , Ellis Lehman L. , Bishop Stephen H. 
Published: June 2005

AbstractThe cytosolic (cAAT) and mitochondrial (mAAT) aspartate aminotransferases were partially purified from gill tissue of the ribbed mussel, Modiolus demissus, and individually characterized with respect to heat stability, electrophoretic mobility, pH optimum, Km for substrates, rates in the forward vs. the reverse direction, and reactivity with aminooxyacetic acid (AOA). Isozyme analysis for this population of ribbed mussels indicated three alleles for the cAAT and a single all ele for the mAAT. The mAAT was a single isozymic form with a broad pH optimum and relatively low Kms for aspartate, oxaloacetate, and 2‐oxoglutarate and high Km for glutamate substrates. The cAAT used for the kinetic studies was a single (homozygous) isozymic form, showed great variation in Km and Vmax with pH, and had high Kms for the amino acid substrates and low Kms for the ketoacid substrates. Both enzymes were inhibited to the same degree by AOA. It is hypothesized that the cAAT is involved more with aspartate synthesis and the mAAT with aspartate catabolism.
Influence of osmolytes, thin filaments, and solubility state on elasmobranch phosphofructokinase in vitro
Authors: Hand Steven C. , Somero George N. 
Published: June 2005

AbstractSkeletal muscle phosphofructokinase (PFK) purified from the thornback ray is rapidly inactivated by urea concentrations as low as 50 mM at pH values below 7.0. Urea‐induced loss of PFK activity is not offset by trimethylamine‐N‐oxide. Protection against urea‐inactivation in vivo, where urea concentration may approach 0.5 M, may be due to two effects. Filamentous (F) actin and muscle thin filaments moderately reduce the urea‐induced loss of PFK activity. The binding of PFK to F‐actin and to thin filaments is shown by ultracentrifugation experiments. PFK activity in vivo also may be stabilized in this species by the formation of a particulate enzyme form which is totally resistant to inactivation by physiological concentrations of urea.
Corticotropin‐releasing factor (CRF) stimulates locomotor activity in intact and hypophysectomized newts (amphibia)
Authors: Moore Frank L. , Roberts John , Bevers Jeb 
Published: June 2005

AbstractLocomotor activity of rough‐skinned newts (Taricha granulosa) was significantly higher in intact and hypophysectomized males injected intracranially with 100 ng CRF (ovine corticotropin‐releasing factor) than in those injected with 10 ng CRF or saline. In addition, an injection of corticosterone or dexamethasone failed to stimulate newt locomotor activity. These results provide evidence that CRF can act independently of pituitary hormones to stimulate locomotor activity in a nonmammalian vertebrate.
Pinocytosis in fertilized sea urchin (Arbacia punctulata) eggs
Authors: Carron Christopher P. , Longo Frank J. 
Published: June 2005

AbstractFertilized and unfertilized Arbacia eggs were incubated with extracellular tracers in an effort to: (1) correlate the onset of pinocytosis with egg activation and its possible role in restructuring the zygote's surface and (2) determine the fate of internalized vesicles and their contents. Zygotes incubated with horseradish peroxidase (HRP), native ferritin, or cationized ferritin incorporated tracers within coated vesicles by 4–7 minutes postinsemination. In contrast, endocytosis by unfertilized eggs was not observed. Zygotes taken at intervals up to cleavage (60 minutes postinsemination) exhibited all three tracers within coated and uncoated vesicles and lysosomes. HRP reaction product was identified within Golgi cisternae in only a few zygotes; native and cationized ferritin were never observed within Golgi elements. The sequential appearance of tracers in pinocytotic vesicles and lysosomes of fertilized eggs suggests that surface‐related components are interiorized and then modified or degraded. Because the zygote surface undergoes a reduction in area, temporally correlated with the onset of pinocytosis, it is possible that endocytosis may be instrumental in the accommodation of the plasmalemma. The interiorization of surface membrane in fertilized eggs may represent a mechanism for the alteration of developmentally related cell surface components.
Regulation of the permeability of the medaka fish embryo chorion by exogeneous sodium and calcium ions
Authors: Cameron Ivan L. , Hunter Keithley E. 
Published: June 2005

AbstractWe questioned if the optically transparent noncellular chorion, or egg envelope, which encapsulates the entire medaka fish (Oryzias latipes) embryo might in some way constitute a permeability barrier to high concentrations of the diuretic called amiloride. More specifically, we questioned if removal of cations from the exogenous environment of the medaka embryo might make the chorion more permeable to amiloride and thereby make the fish embryos more sensitive to the inhibitory and lethal effects of this drug. To test this question, chorion‐encapsulated medaka embryos were exposed to: deionized‐distilled water, to Yamamoto‐Ringer's (Y‐R) solution, to Yamamoto‐Ringer's containing choline chloride as a substitute for NaCl, and to isotonic NaCl solution in the presence of and in the absence of amiloride. Briefly, the prediction that the medaka embryos would be most sensitive to amiloride's inhibitory effects in distilled water was confirmed. Further studies showed that the presence of Na+ or of Ca2+ alone in the culture solution gave partial protection against the lethal effects of the amiloride. Electron probe X‐ray microanalysis studies indicated that addition of Ca2+ and other cations to the culture solution caused the concentrations of cations to increase in the chorion, and that increase was correlated to a visible decrease in the permeability of the chorion to the amiloride. This decreased permeability of the chorion apparently protected the embryo from the amiloride. The decreased permeability of the chorion to amiloride, which occurred in the presence of the cations present in Y‐R solution, was found to be reversible once the cations were washed from the chorion.
Caudal movement of tissues ventral to the cervical somites and the development of the shoulder in the chick embryo
Authors: Searls Robert L. , Brown Joyce 
Published: June 2005

AbstractIt has been suggested that formation of the shoulder in the embryonic chick is caused by caudal movement of the pleural coelom (Yander and Searls, '80a,b; Searls, '83). The cells of the somatopleure over the pleural coelom move into the base of the wing causing a thickening at the cranial base of the wing (the shoulder). In the previous work cited what caused the pleural coelom to move in a caudal direction could not be determined.It has now been observed that part of this movement is due to increase in the cranial‐caudal width of the hyoid arch. The mandibular arch does not move relative to the base of the wing or the somites. The caudal margin of the hyoid arch on the surface of the neck moves caudally at a rate of four to six somites per day, overgrowing the cervical sinus in the process. The aortic arches move in the same direction at a rate of 2 to 3 somites per day. It is suggested that the more medial elements of the hyoid arch are increasing in size, displacing the cervical sinus in a caudal direction. Part of the caudal movement of the cranial margin of the pleural coelom is also due to increase in length of the trachea. The trachea branches from the larynx ventral to about the eighth somite from 4 to 7 days of development. The distance from the cranial end of the trachea to the bifurcation that produces the left and right bronchi increases so that the bronchi become medial to the shoulder at 5.5 days, and the distance from the cranial end of the trachea to the pleural coelom increases so that the pleural coelom becomes medial to the shoulder at 4.5 days.
Closure of the squid cornea: A muscular basis for embryonic tissue movement
Authors: Arnold John M. 
Published: June 2005

AbstractThe squid cornea is derived from epithelial tissue behind the eyeball. The future cornea is pulled over the developing eyeball by contraction of muscle cells which develop just behind the leading edge. Treatment with cytochalasin B or colchicine does not stop this embryonic tissue movement, suggesting that the muscle is the main motive force in corneal closure.
Limb regeneration in anuran tadpoles following repeated amputations
Authors: Kollros Jerry J. 
Published: June 2005

AbstractLimbs were amputated through the thigh in stages from V onward in Rana pipiens, R. sylvatica, and Pseudacris nigrita tadpoles to establish regenerative capacity. Normal regenerates were produced through stages XII, XI, and XIII, respectively, for the three species. However, hypomorphic forms with reduced toe numbers or a single spikelike spur, or nonregeneration, could appear as early as stages VII or VIII, and increased in frequency thereafter. Pseudacris produced the largest fraction of hypomorphs and R. sylvatica the smallest. Regenerated limbs of various stages were reamputated just distad of the initial transection level and produced regenerates with almost the same frequency as did the initial amputees. In R. pipiens reamputation and regeneration was followed for up to six sequences, with but little change in frequency or quality of regeneration, even when the contralateral control limbs were in stages XIV–XVII, well beyond the possibility of regeneration after transection through the thigh. Clearly, the hormonal milieu did not limit regeneration, though rate of regeneration accelerated as metamorphic climax was approached. Foot sizes were measured in R. pipiens, and were seen in control animals to be correlated to both stage and to tadpole length. Regenerated feet tended to be slightly larger than control feet of the same stage, showed comparable relationships between length and width, but correlated more poorly with tadpole length.
Uniform cartilage differentiation in micromass cultures prepared from a relatively homogeneous population of chondrogenic progenitor cells of the chick limb bud: Effect of prostaglandins
Authors: Gay Steven W. , Kosher Robert A. 
Published: June 2005

AbstractEven at very early stages of development (i.e., stages 22–24), the embryonic chick limb bud consists of a heterogeneous mixture of chondrogenic, myogenic, and fibrogenic progenitor cells in various stages of differentiation. In contrast, the distal subridge region of a stage 25 wing bud appears to be a relatively homogeneous population of undifferentiated chondrogenic progenitor cells. In the present study, we confirm the results of a number of investigators that when the heterogeneous cells of whole stage 23/24 limb buds are subjected to high density cell culture (micromass culture) the cells in various discrete regions of the culture aggregate with one another and differentiate into cartilage nodules. The cartilage nodules in such cultures, however, are separated from one another by a considerable amount of nonchondrogenic tissue. In fact, nonchondrogenic tissue constitutes a relatively high proportion of the micromass cultures of whole stage 23/24 limb bud cells. In contrast, when stage 25 subridge mesenchymal cells are subjected to micromass culture, a virtually uniform sheet of cartilage is formed throughout the culture, and little, if any, nonchondrogenic tissue is detectable. The micromass culture of stage 25 subridge mesenchymal cells thus provides an excellent system in which a relatively homogeneous group of chondrogenic progenitor cells progressively and uniformly undergo chondrogenesis in a readily manipulable culture situation. Such a system is ideally suited for studies on the molecular regulation of cartilage differentiation.In the present study, we have also demonstrated that exogenous prostaglandin E2 (PGE2) elicits a dose‐dependent stimulation of chondrogenesis in micromass cultures of both stage 25 subridge mesenchymal cells and the cells of whole stage 23/24 limb buds. The stimulatory effect of PGE2 is greatly potentiated by the phosphodiesterase inhibitor theophylline, suggesting that its influence on chondrogenesis is mediated by its ability to increase cAMP levels. PGE1 is just as effective as PGE2 in stimulating chondrogenesis, whereas PGF1α, 6‐keto PGF1α and thromboxane B2 have no effect. On the basis of these observations and previous studies, the possibility that endogenous prostaglandins might regulate limb cartilage differentiation by acting as local mediators of cAMP accumulation is discussed.
Immunofluorescent localization of extracellular matrix components during muscle morphogenesis. I. In normal chick embryos
Authors: Kieny M. , Mauger A. 
Published: June 2005

AbstractType I collagen is the major collagenous component of embryonic and early postnatal musculature. It is found in tendons, muscle envelopes around individual myofibers (endomysium), around muscle bundles (perimysium), and around muscle bulks (epimysium), as well as in loose connective tissue of intermuscular spaces and perimuscular tunica.Type III collagen deposition follows with some delay that of type I collagen in all mentioned locations. This type of collagen, however, is not a permanent component of tendons, from which it disappears during the second half of the incubation.Fibronectin, at first ubiquitously present around connective tissue cells and myogenic cells, becomes progressively restricted to the basal lamina zone, so as to delineate each myofiber.Laminin at first surrounds groups of muscle cells as long as the latter have not reached the stage of myofiber. At that time, laminin becomes restricted to the immediate surrounding of each myofiber.
Immunofluorescent localization of extracellular matrix components during muscle morphogenesis. II. In chick embryos with hereditary muscular dysgenesis (cn/cn)
Authors: Mauger A. , Kieny M. , Goetinck P. F. 
Published: June 2005

AbstractThe immunofluorescent distribution of types I and III collagen, fibronectin, and laminin during muscle morphogenesis of the crooked neck dwarf mutant chick embryo differs from that of the normal chick. The drastic difference is related to the inability of the mutant embryo to maintain a harmonious muscle pattern. The first sign of the defect is the disaggregation of type I collagen fibers of the tendons and the disorganization of the intermuscular spaces. The organization of the connective tissue never proceeds beyond the appearance of an epimysial envelope, rich in types I and III collagen, which becomes disorganized shortly after. No perimysial envelopes displaying types I and III collagen fibers and fibronectin, nor endomysial sheaths develop. Only large spaces filled with types I and III collagen fibers subdivide groups of muscle cells irregularly. On the whole, type III collagen is less abundant than type I collagen. Fibronectin disappears from the periphery of the muscle cell. Laminin is more thickly deposited in the basal lamina around irregularly sized muscle cells than around the normal muscle cell. The results are discussed in terms of morphogenetic interactions between connective tissue cells and muscle cells, and in terms of fibrosis, which characterizes some muscle diseases.
Histogenesis in 11‐day mouse embryo limb buds explanted in organ culture
Authors: Milaire J. , Mulnard J. 
Published: June 2005

AbstractFore‐ and hindlimb buds from 11‐day mouse embryos with 40 to 52 somites (including the four occipital pairs) were explanted in organ culture and submitted to systematic histological analysis. Chondrogenesis occurs normally in culture in all preskeletal rudiments which were already represented by condensed blastemas before explantation. In the proximal territories, the progress of cartilage differentiation occurs according to the normal pattern and can be revealed histologically much earlier than in bulk preparations. In all explanted hindlimbs as well as in forelimbs from embryos with less than 50 somites, a primary coalescence occurs between the IId and IIId digital rays, leading to various fusions from soft tissue syndactyly to oligosyn‐dactyly. This is the result of two combined unfavorable effects of the culture conditions: the lack of simultaneous volumetric growth of the foot‐ or handplate, which normally would provide the necessary space for the laying down of a pentadactylous pattern, and a loss of cells resulting from abnormal cell death affecting selective mesodermal sites in the zeugopod and in the marginal subridge area, the latter being more severely affected in hindlimb buds. Several observations suggest that the preferential sensitivity of the marginal mesoderm might be related to early changes in the apical ectoderm, which itself becomes excessively necrotic and rapidly looses its pseudostratified configuration. The forelimb buds from embryos with 50 somites and more usually develop a pentadactylous pattern with a better individuation of digital structures. In all explants, the prospective mesoderm of digit I exhibits stronger regulatory tendencies.
Uptake and distribution of exogenous serum proteins in the cultured rat embryo
Authors: Rhinehardt Ann E. , Carey Sean W. , Young Marian F. , Klein Norman W. 
Published: June 2005

AbstractHead fold stage rat embryos were cultured on a medium consisting of adult rat serum for 48 hr. During the final 10 or 20 hr of culture [35S]‐methionine was added to the medium. Sera from visceral yolk sac blood vessels, exocoelomic cavity fluid, and amniotic sac fluid were analyzed by SDS‐polyacrylamide gel electrophoresis followed by Amido Black staining and fluorography. Amido Black staining showed bands in all three embryonic fluid compartments which migrated at rates comparable to transferrin, alpha‐feto‐protein, albumin, IgG, and hemoglobin. Fluorography, however, showed that radioactivity was restricted to alpha‐fetoprotein, IgG, and hemoglobin. This suggested that at least some transferrin and albumin were transferred intact from the exogenous medium to the embryonic fluid compartments.
Isolation and structural characterization of chicken hypothalamic luteinizing hormone releasing hormone
Authors: King J. A. , Millar R. P. 
Published: June 2005

AbstractStudies on partially purified chicken hypothalamic luteinizing hormone releasing hormone (LHRH) utilizing chromatography, radioimmunoassay with region‐specific antisera, enzymic inactivation, and chemical modification established that the peptide is structurally different from mammalian hypothalamic LHRH. These studies demonstrated that arginine in position 8 is substituted by a neutral amino acid. On the basis of conformational criteria and evolutionary probability of amino acid interchange for arginine, the most likely substitution was glutamine. We therefore synthesized [Gln8]‐LHRH and established that it had identical chromatographic, immunologic, and biological properties to the natural chicken peptide. In concurrent studies, purification of 17 μg of an LHRH from 249,000 chicken hypothalami was achieved using acetic acid extraction, immuno‐affinity chromatography, and cation exchange and reverse phase high performance liquid chromatography. Amino acid composition and sequence analyses confirmed the structure of this form of chicken LHRH as pGlu‐His‐Trp‐Ser‐Tyr‐Gly‐Leu‐Gln‐Pro‐Gly‐NH2.
Avian gonadotropin receptors: A comparative view
Authors: Ishii Susumu , Kubokawa Kaoru 
Published: June 2005

AbstractAvian testicular receptors for gonadotropins show a species‐specificity similar to mammalian receptors for the binding affinity to gonadotropins of various origins. In the affinity‐capacity relationships, avian FSH receptors are classified in the same group with chelonians, that is, they exhibit relatively low affinity and high capacity. FSH receptors of the Japanese quail resemble the rat receptor with respect to the temperature‐dependence of affinity in the low‐temperature range, but also resemble reptilian or amphibian receptors with respect to binding affinities in the middle‐ to high‐temperature range. We conclude that avian gonadotropin receptors have some characteristics of homeothermic vertebrates, but still retain characteristics of poikilothermic groups.
Hormonal mediation of reproductive behavior
Authors: Ottinger M. A. , Adkins‐Regan E. , Buntin J. , Cheng M.‐F. , Devoogd T. , Harding C. , Opel H. 
Published: June 2005

AbstractReproductive capability requires synchronization of both endocrine and behavioral components of reproduction. The classic view of reproductive behavior was that there was simply direct stimulation of a behavioral response by the appropriate gonadal steroid. However, it has become clear with recent developments in the field of behavioral endocrinology that the relationship of hormonal and behavioral processes is complex. In addition to the complexity of the mechanisms involved, other factors, both social and environmental, influence both the endocrine and behavioral responses. This paper provides an overview of selected issues within the field of behavioral endocrinology which deal with mechanisms of hormonal induction of behavior at various stages of the life cycle and with factors that interact with these processes.
Endocrine control of the nasal salt glands in birds
Authors: Butler David G. 
Published: June 2005

AbstractIn birds, adrenocortical hormones probably sustain nasal salt gland (NSG) function, indirectly, through their influence on renal and cardiovascular function. Adrenalectomy blocks the response by duck NSG to hypertonic saline only if the ducks are maintained on freshwater. However, if adrenalectomized ducks are fed 0.9% NaCl ad libitum the NSG secrete fluid and osmolytes at the normal rate. Adrenalectomy did not prevent the significant functional hypertrophy of the NSG that always follows adaptation to saline. Mean arterial blood pressure was lower than normal two days after adrenalectomy. Stroke volume decreased by about 50% but there was a commensurate increase in cardiac frequency, so cardiac output was unchanged. There was no measurable change in total peripheral vascular resistance. There was at least a twentyfold increase in blood flow rate to the NSG when they were actively secreting fluid, but this increase was totally blocked after adrenalectomy. An inadequate supply of blood and not a corticosteriod deficiency in the secretory cells was the primary reason for NSG failure. Single intravenous injections of as little as 28 pm/kg bw of (Asp1, Val5)‐angiotensin II (AII) had no measurable effect on mean arterial blood pressure in conscious ducks but did shut off the NSG for about 4 min; then the NSG switched on again. NSG blood flow decreased after AII.