bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of embryonic diapause in Artemia: Environmental and physiological signals
Authors: Drinkwater Laurie E. , Crowe John H. 
Published: June 2005

AbstractEnvironmental cues terminating embryonic diapause and a potential regulatory mechanism involving depressed pH were investigated in the encysted embroyos of the brine shrimp, Artemia. Two species, Artemia franciscana and Artemia monica, were used for this comparative study. To determine if alteration of intracellular pH (pHi) can terminate diapause, the pHi of diapause cysts was manipulated by exposure to NH3 and CO2. Alkalinization did not result in activation of cysts from either species but acidification activated A. franciscana cysts. A. monica did not respond to acidification. The pHi of aerobic diapausing embryos was determined using 31P nuclear magnetic resonance spectroscopy. During diapause, embryos from both species had pHi's similar to those reported for activated (nondiapause) embryos, indicating that diapause is not imposed by depressed pHi, as is the case during suppression of metabolism under anaerobic conditions. Diapause embryos were exposed to varying conditions of temperature, salinity, and oxygen to determine what conditions are necessary to break diapause. A. franciscana cysts were activated by cold temperature or salinites above 2.0 M NaCl, while A. monica cysts only responded to cold temperature. The availability of oxygen did not influence either population's ability to terminate diapause. The results are discussed with respect to each population's environment and potential mechanisms of diapause regulation.
Protein synthesis during imaginal disc pattern regulation
Authors: Greenberg Robert M. , Adler Paul N. 
Published: June 2005

AbstractWe have examined the pattern of protein synthesis during wing disc pattern regulation. Although in vivo culture dramatically alters the pattern of abundant protein synthesis in wing discs, only one protein—RG38—changes specifically in response to pattern regulation. This polypeptide, previously identified as being nonuniformly distributed in wing and haltere discs, is synthesized in a graded distribution across the wing disc. During wing disc pattern regulation, it acts as a molecular marker for regeneration of particular wing disc regions. Thus, the rate of RG38 synthesis increases during regeneration (by fragments with initial low levels) with kinetics that parallel those for regeneration as scored by the presence of adult cuticular structures.
Pacemaker region in a rhythmically contracting embryonic epithelium, the enveloping layer of Oryzias latipes, a teleost
Authors: Barber B. , da Cruz M. J. B. , DeLeon J. , Fluck R. A. , Hasenfeld M. P. , Unis L. A. 
Published: June 2005

AbstractThe primary objectives of this study were (1) to determine the embryonic stage at which the Oryzias latipes enveloping layer (EVL) begins to contract rhythmically, and (2) to determine where these contractions arise within the EVL. Using time‐lapse video recording, we showed that the contractions begin at stage 14 (the stage of the embryonic shield) and arise in the ventral region of the EVL, which is centered at 180° longitude from the embryonic shield. We have called this the pacemaker region for the contractions. Using fluorescein diacetate as a vital stain, we showed that the ventral region of the EVL continues to act as a pacemaker even after the EVL is detached from the rest of the egg.Rhythmic contractile activity ceased when we removed a group of about 130 cells — 10% of the total EVL— from the pacemaker region; comparably large wounds elsewhere had no effect on the contractions. When we cut detached EVLs into ten pieces, only 2.4 ± 1.8 (X ± SD, N = 11) of them contracted rhythmically, even though a considerably larger proportion of the EVL cells participate in the contractions in undisturbed blastoderms. We conclude that the pacemaker cells are necessary for rhythmic contractile activity and that cells outside this region do not contract spontaneously.The contractile waves are propagated at a velocity of 14–54 μm sec−1. This value, which is two to three orders of magnitude slower than the propagation of epithelial action potentials, is similar to the rate of propagation of waves of increased cytosolic Ca2+ in other systems.We propose that the medaka EVL is a good system in which to study certain aspects of epithelial morphogenesis.
Electrophoretic characterization of soluble proteins from dental tissues (polyphyodonts and diphyodonts species)
Authors: Lemus David , Illanes Julio , Fuenzalida Marcela , Repetto Yolanda , De La Vega Yolanda Paz , Blańquez Maria José 
Published: June 2005

AbstractThe developmental processes related to odontogenesis are similar in all vertebrates and they occur during embryogenesis. The dental papilla can exercises directive morphogenetic role on epithelia of different phylogenetic origin. In our laboratory we have previously shown that cultured heterologous tissue recombinations between adult lizards dental papillae and quail epithelia were capable of producing odontogenesis and amelogenesis. Employing sodium dodecyl‐sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) according to Laemmli ('70, Nature, 227:680–685.) and two‐dimensional polyacrylamide gel electrophoresis (2‐D PAGE) (O'Farrell, '75, J. Biol. Chem., 250:4007–4021.), we have examined the distribution of soluble proteins with respect to isoelectric point and molecular weight of dental papillae isolated from tooth germs at bell stage of adult lizard Liolaemus tenuis tenuis (polyphyodont species) and dog fetuses Canis familiaris (diphyodont species). A comparison was also made with dental pulps from adult dogs. Some dental papillae from lizard tooth at bell stage were recombined with quail ectoderm and cultured in explant for 8 days. Furthermore, the histological analysis of dental papillae from lizard and dog fetus showed that dental papillae from both species contain preodontoblast cells, scarce extracellular matrix, and some blood vessels. Dental pulp from adult dogs is composed of odontoblast and fibroblast cells, extracellular matrix, collagen, blood vessels, etc. The control heterologous recombinants after the culture period differentiated chimeric tooth structures, showing that the dental papillae were capable of producing developmental instructions. The electrophoretic study of the supernatants showed differences and similarities. Under SDS‐PAGE the presence of one band of an approximate molecular weight of 49.000 daltons was disclosed, which seems to be unique to dental papilla from adult lizards and dog fetuses. Under 2‐D PAGE protein patterns from adult lizard and dog fetuses disclosed also two protein spots with an approximate molecular weight of 49.000 daltons and isoelectric point of pH ranges between 6 and 7.5. Apparently these spots are unique to both patterns and would have some significance in odontogenesis.
Ferritin in mantle pore cells and its role in reproduction of Helisoma duryi (mollusca: Pulmonata)
Authors: Miksys S. L. , Saleuddin A. S. M. 
Published: June 2005

AbstractThis study was undertaken to investigate the ferritin content of pore cells in the mantle of Helisoma duryi and the possibility of these cells being a source of vitellogenic ferritin. Ultrastructurally pore cells in the mantle resemble those previously studied in the heart/kidney region, except that their plasma membrane is less elaborate. The presence of iron is demonstrated in the cells by the Prussian blue reaction, and in the ferritinlike contents of cytoplasmic vesicles by energy dispersive X‐ray analysis. Egg‐laying activity begins 2 days after virgin snails are allowed to mate. By means of radioimmunoassay it is found that mantle (containing pore cells) ferritin content increases rapidly at the onset of egg‐laying, then declines to reproductive levels. As it declines, the blood ferritin content increases to reproductive levels. Ovotestis and digestive gland ferritin contents drop at the onset of egg‐laying, then rapidly return to reproductive levels. The relationships between the ferritin contents of these four tissues at the onset of and subsequent to egg‐laying are discussed. The ferritin contents of various tissues are determined by radioimmunoassay (RIA) after the removal of endocrine dorsal bodies from reproducing snails. The ferritin levels remain unchanged in the blood and digestive gland, increase in the mantle, and decrease in the ovotestis. A possible influence of dorsal body hormone on ferritin uptake by vitellogenic oocytes is discussed.
Ca2+ ionophore and phorbol ester stimulate taurine efflux from skate erythrocytes
Authors: Leite Margarette V. , Goldstein Leon 
Published: June 2005

AbstractHypotonic (approximately 1/3) medium stimulated efflux of taurine from skate (Raja erinacea) RBC approximately twofold at 30 and 60 min incubation. Both Ca2+ ionophore (A23187, 10−7 M) and phorbol ester (phorbol 12‐myristate 13‐acetate, 10−7 M) mimicked the effects of hypotonicity on taurine efflux. Calmodulin was probably not involved in the responses to hypotonicity and Ca2+ ionophore, since calmodulin inhibitors did not block either basal taurine release or hypotonic‐induced stimulation of taurine release. These results suggest that cell Ca2+ and protein kinase C may both play a role in modulating taurine efflux.
A comparison of aromatase, 5α‐, and 5β‐ reductase activities in the brain and pituitary of male and female quail (C. c. japonica)
Authors: Schlinger Barney A. , Callard Gloria V. 
Published: June 2005

AbstractIn numerous vertebrate species including Japanese quail (Co‐turnix coturnix japonica), actions of testosterone (T) on neuroendocrine target tissues are mediated in part by conversion to estrogenic and androgenic metabolites. In order to assess which pathways were favored in each identified androgen target area in quail brain and whether there were discernible sex differences, we developed an assay for simultaneously quantifying aromatase, 5α‐, and 5β‐reductase. In addition, we made the first definitive identification of aromatase in quail pituitary and compared all three enzyme activities in the pituitary of males and females. Enzymes were measured in tissue homogenates by the conversion of [3H]androstenedione to [3H]estrone, [3H]5α‐androstanedione, and 5β‐androstanedione. Aromatase activity was restricted to limbic tissues (anterior hypothalamus > posterior hypothalamus > septum > archistriatum containing nucleus taenia) while hyperstriatum, cerebellum, and midbrain containing nucleus intercollicularis were aromatase‐negative. Quail pituitary aromatized androgen at rates equivalent to anterior hypothalamus pre‐optic area (aHPOA). 5α‐ and 5β‐reductase were present in all tissues tested. Aromatase was significantly higher in aHPOA and pituitary of males, whereas 5α‐reductase was significantly higher in female pituitary. These data suggest that a complex of androgen‐metabolizing enzymes controls the neuroanatomic (spatial) distribution of active hormone in neuroendocrine tissues and that quantitative differences between males and females may account for sex differences in behavior.
Penetration of mouse eggs at various intervals after insemination as influenced by concentration of sperm and strain of male
Authors: Robl J. M. , Dziuk P. J. 
Published: June 2005

AbstractThis study was conducted to determine the extent to which the percentage of mouse eggs that were penetrated by sperm at the end of the period of sperm penetration was due to the proportion of eggs penetrated per unit of time and to the span of time of sperm penetration. Female mice of ICR strain were inseminated 1.5 hr after ovulation with 5 × 106 sperm/50 μl from males of DBA/2N, CF1 or C57BL/6N strains to determine the effect of the male. To determine the effect of concentration of sperm ICR females were inseminated with 2, 4, 6, or 8 × 106 sperm/50 μl from CF1 males. Females were killed at various intervals after insemination and the eggs were recovered and examined for evidence of penetration by a sperm. The time intervals from both insemination to the onset of egg penetration and from insemination to cessation of penetration were similar for the three strains of males. Throughout the period of penetration of eggs a constant percentage of eggs was penetrated per hour for a particular strain of male. The relative percentage penetrated per hour very closely approximated the relative percentage of eggs finally penetrated for each strain of male. The percentage of eggs penetrated per hour was linearly positively related to the concentration of sperm inseminated. The final percentage of eggs penetrated depended primarily on the rate at which the eggs were penetrated during the period of sperm penetration and not on the length of the period of egg penetration which was constant.
Short‐term changes in levels of cyclic AMP, adenylate cyclase, and phosphodiesterase during the initiation of sperm motility in rainbow trout
Authors: Morisawa Masaaki , Ishida Katsumi 
Published: June 2005

AbstractIn order to clarify the role of the system that generates and degrades cyclic AMP during the initiation of motility of trout sperm, short term changes in levels of intraspermatozoal cyclic AMP, adenylate cyclase, and phosphodiesterase were measured. Levels of cyclic AMP and the activity of adenylate cyclase increased and reached a maximum level 1 sec after transfer of sperm to K+ ‐free medium, where they became motile, and then decreased rapidly. However, there were no changes in either parameter in sperm which remained immotile in K+ ‐rich medium. In addition, an increase in the activity of phosphodiesterase was observed 4 sec later than the increase in levels of cyclic AMP and adenylate cyclase. These findings suggest that a very rapid change in the level of intracellular cyclic AMP occurs within 1 sec, at the moment of spawning, by the activation of adenylate cyclase and phosphodiesterase, and regulates the initiation of trout sperm motility.
Differentiation of the accessory cells and structural regionalization of the oocyte in the ascidian Ciona savignyi during early oogenesis
Authors: Sugino Yasuo M. , Tominaga Akio , Takashima Yoichiro 
Published: June 2005

AbstractThe process of oogenesis in Ciona savignyi was studied at the ultrastructural level to understand the development of the accessory cells and the relationship of the oocyte and its accessory cells to the germinal epithelium. There are two kinds of small cells, dark cells and clear cells, adjacent to the oocyte in the germinal epithelium. The previtellogenic ovarian follicles can be classified into four stages on the basis of accessory cell differentiation and chorion formation. At stage 1, the oocyte is enclosed by the primary follicular cells and the outer follicular cells, which resemble the dark cells and the clear cells, respectively. Late in this stage, the chorion rudiment and microvilli‐like projections appear first at the area of the oocyte adjacent to the germinal epithelium. The chorion rudiment is distributed as patches on the oocyte surface and divides the primary follicular cells into inner and outer groups at stage 2. The rudiment covers the oocyte entirely, and the inner group of the primary follicular cells differentiates into the test cells, whereas the outer group becomes the inner follicular cells at stage 3. These cells contain much rough endoplasmic reticulum and electron‐dense granules. At stages 2 and 3, subsurface cisterns are frequently observed at the oocyte surface facing the primary follicular cells or the test cells. The dense granules of the test cells become larger, whereas those of the inner follicular cells appear to become vacuolated at stage 4.
Separation and functions of two acyl CoA transferases from Ascaris lumbricoides Mitochondria
Authors: Saz Howard J. , deBruyn Becky S. 
Published: June 2005

AbstractMany invertebrates accumulate propionate, or products derived from propionate, as products of fermentation. Evidence has been reported that the nematode, Ascaris suum, the cestode, Spirometra mansonoides, and the trematode, Fasciola hepatica, accumulate propionate by means of an adenosine triphosphate (ATP)‐generating decarboxylation of succinate. To generate energy, an acyl coenzyme A (CoA) transferase that would transfer CoA to succinate is required as one component of the sequence of reactions.Recently, an acyl CoA transferase was isolated from Ascaris mitochondria and purified to electrophoretic homogeneity. However, upon examination of the substrate specificities of this enzyme, it was found essentially to lack the ability to use succinate or succinyl CoA as an acceptor or donor of CoA, respectively. Therefore, this transferase could not serve to activate succinate.This article describes the isolation of an additional acyl CoA transferase from Ascaris mitochondria that appears to be unique in its substrate specificity and that could easily account not only for the activation of succinate but also for the regulation of succinate metabolism primarily in the direction of decarboxylation to propionate. This is in contrast with mammalian tissues, which act in the opposite direction by catalyzing the fixation of CO2 into propionate, thereby forming succinate and accounting for the glycogenic nature of dietary propionate. Possible functions of the two acyl CoA transferases are discussed.
Radioimmunoassay and characterization of renin‐angiotensin system in the fresh‐water turtle
Authors: Cho Kyung Woo , Kim Suhn Hee , Koh Gou Young 
Published: June 2005

AbstractWe developed a radioimmunoassay (RIA) for plasma renin concentration (PRC) and characterized the renin‐angiotensin system (RAS) in the fresh‐water turtle (Amyda japonica).Among three antisera to human angiotensin I (ANG I) had different specificities to ANG I analogues; the antiserum with the highest specificity was used to measure the PRC. The amount of ANG I generated from incubation of turtle renal extracts with turtle plasma was linear with respect to volume of renal extract and incubation time. Turtle renin cleaved heterologous substrates from nephrectomized rats and rabbits but had a higher affinity for renin substrate from rabbits. The generation of ANG I with heterologous substrate was temperature dependent (optimum‐37°C) and the pH optimum was at 5.0–5.5. Furosemide (5 mg/kg) did not affect PRC. Hemorrhage (1% and 3% of body weight) decreased blood pressure. The PRC did not change with the lower hemorrhage, but increased significantly with massive hemorrhage. Angiotensin II increased blood pressure with no effect in PRC. The PRC of fresh‐water turtles transferred to 4°C increased significantly.The RAS in the fresh‐water turtle seems to be involved in the adaptation of environmental temperature rather than in the acute control of blood pressure although the mechanism is not known.
Purification and identification of vitellogenin and its immunohistochemical detection in growing oocytes of the teleost, Oryzias latipes
Authors: Hamazaki Tatsuo S. , Iuchi Ichiro , Yamagami Kenjiro 
Published: June 2005

Abstract“Probable vitellogenin” [Hamazaki et al. (1985) J. Exp. Zool., 235:269–279] of the medaka, Oryzias latipes, was purified from the ascites of estrogen‐fed (EF) fish and was identified as the real vitellogenin by examining some of its biochemical characteristics. It has an amino acid composition and phosphorus content (0.8%) quite similar to those of the vitellogenin of rainbow trout and goldfish. The molecular weight (mw) in the native state was about 420,000, but sodium dodecyl sulfate denaturation produced a group of peptides that included a major peptide of about 200,000 mw with an isoelectric point of 3.8–4.0. Immunohistochemical observations with the use of the anti‐vitello‐genin antibody raised against the purified vitellogenin as a probe indicated that a considerable immunoreactivity appeared in some vesicles of the oocytes at the yolk‐vesicle stage (ca, 150–250 μm in diameter). However, yolk deposition in the oocytes seemed to occur at the later stage (vitellogenic stage, over 300 μm in diameter) as judged from histological examination of the the hematoxylin‐stained materials. Moreover, the immunofluorescence was observed in the intercellular spaces among the follicle cells of the vitellogenic oocyte. The observation indicates that the pathway of vitellogenin transportation through the follicle cell layer into the oocyte is present in the extracellular matrix of the follicular epithelium.
Follicle cell regulation of mammalian oocyte growth
Authors: Buccione Roberto , Cecconi Sandra , Tatone Carla , Mangia Franco , Colonna Rosella 
Published: June 2005

AbstractTo investigate mechanisms of follicle cell control on mammalian oocyte growth, preantral mouse oocytes free from surrounding follicle cells were individually cocultured with monolayers of different somatic cells competent to form gap junctions, and the rate of in vitro oocyte growth was directly correlated with the level of metabolic coupling on the same cells. The results indicate that 1) at a similar extent of metabolic coupling, mouse oocytes grew on follicle cells but not on 3T3 and Sertoli cell monolayers, and 2) the growth rate of oocytes cultured on follicle cells was dependent on the extent of metabolic coupling. It was concluded that gap‐junction‐mediated mutrition of ovarian mouse oocytes exerted by somatic cells is necessary but not sufficient to maitain oocyte growth. A specific regulatory role of follicle cells on mammalian oocyte growth is proposed.
Amino acid transport in bivalve mollusc mitochondria: The role of the proton motive force and monovalent cations in proline oxidation by oyster (Crassostrea virginica) gill mitochondria
Authors: Moyes Christopher D. , Ballantyne James S. 
Published: June 2005

AbstractThe role of the proton motive force (PMF) and significance of the common intracellular monovalent cations (Na+ and K+) in proline oxidation by oyster (Crassostrea virginica) gill mitochondria were examined. Proline was oxidized at moderate rates in the presence of ADP under isosmotic conditions. Oxidation of proline was inhibited by CCCP (carbonyl cyanide m‐chlorophenylhydrazone), an uncoupler of oxidative phosphorylation. Oxidation of pyruvate, but not succinate (each oxidized at moderate rates), was inhibited by CCCP, confirming that the PMF was at least partially dissipated. These data suggest that transport of proline is dependent on some component of the PMF, either the pH gradient or the membrane potential. Less inhibition of proline oxidation by CCCP was achieved at higher proline concentrations suggesting that diffusional penetration may become more important as proline concentrations increase. Oxidation of proline was not substantially affected by reducing concentrations of Na+ or K+ or both Na+ and K+ (Na+ < 9 mM; K+ < 1 mM), suggesting that proline transport does not require an inward chemical gradient of these monovalent cations. Monovalent cations stimulated proline oxidation in the order of the Hofmeister series (Na+ > K+ > choline+). The high rate of oxidation achieved using Na+ is unusual and is probably an adaptation related to the high intracellular Na+ concentrations found in many bivalve molluscs.