bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ontogenetic changes in erythrocytic organic phosphates in the bullfrog, Rana catesbeiana
Authors: Hazard E. Starr , Hutchison Victor H. 
Published: June 2005

AbstractThe metamorphosis of anuran tadpoles includes adjustments to different respiratory media and involves changes in all components of the respiratory system. Increased concentrations of erythrocytic organic phosphates decrease blood oxygen affinity in vertebrates. Nucleoside triphosphates (NTP), 2,3 diphosphoglycerate (DPG), inositol polyphosphate (I‐poly‐P) and total phosphate were measured in different stages of tadpoles, juveniles and adults. The concentrations of NTP, DPG, and I‐poly‐P were, respectively: 4.35, 1.90 and 1.12 μmol ml−1 RBC in tadpoles, and 1.80, 1.10 and 0.393 μmol ml−1 RBC in juveniles and adults. Molar ratios also decreased at metamorphosis: NTP/Hb from 1.83 to 0.49, DPG/Hb from 0.814 to 0.296, and I‐poly‐P/Hb from 0.483 to 0.061. The decrease in NTP occurs simultaneously with the transition from tadpole to adult hemoglobin type. The decrease in DPG parallels the decline in blood pH during metamorphosic climax. Levels of I‐poly‐P were not correlated with developmental changes of the respiratory system. The developmental stages of the decrease in red cell organic phosphate concentrations coincide with the suite of adaptive adjustments which lead to aerial respiration in metamorphosing bullfrogs.
Wing pattern formation in Lepidoptera: A model
Authors: Nijhout H. Frederik 
Published: June 2005

AbstractA formal model is presented that demonstrates how the color patterns of the wings of butterflies and moths can be analysed in terms of current concepts of pattern formation. A review of pertinent literature on this little‐known developmental system is provided. Crucial to the understanding of color pattern formation in lepidopteran wings is the realization that the wing pattern is a mosaic. The pattern in each wing cell (i.e., the area bordered by wing veins) is determined independently from the pattern in other cells. Within a cell, pigments are deposited in a definite relation to a central focus. A focus always lies on the cell midline and is often visible as a small pigmented dot. In the simplest condition the color pattern is laid down around a focus as a system of perfect concentric circles (eyespots). More often these circles are considerably distorted and have an axis of bilateral symmetry that parallels the wing veins. The nature and extent of these distortions from circularity account, to a large degree, for the species‐specific character of the wing pattern. The determination of such patterns is most readily explained if it is assumed that a focus represents the reference point with respect to which positional information (for pigment deposition) is specified. Circular patterns are thus obtained if all points equidistant from a focus undergo identical differentiation. Deviations from circularity of the pattern around a focus indicate that either the specification or interpretation of positional information is not the same in all areas around a focus. This phenomenon is most conveniently described as an “interpretation landscape”: a gradient system whose value at any point in a morphogenetic field is a measure of how positional information is to be interpreted at that location. Examples are provided of how species‐specific wing patterns can be generated by modest alterations in the shape of the interpretation landscape. As a rule the field of a focus is limited by the margins of the wing cell in which it is centered except in cases where no focus is present in an adjacent cell. Under those circumstances one focus can determine the pattern in several adjoining wing cells.
Renal alterations induced by osmotic stress and metabolic acidosis in Xenopus laevis
Authors: Stetson David L. 
Published: June 2005

AbstractXenopus has unusual flask cells within the intermediate segment of the renal nephron. These cells respond to osmotic stress by losing the glycosaminoglycan (GAG) contents from their central cavities. Because of this it has been argued that flask cells participate in osmoregulation. The present work was designed to investigate changes in morphology of the flask cells and to determine whether such changes could be related to simultaneous changes in nitrogen excretion rather than osmotic stress.In animals exposed to 21 days of osmotic stress, total nitrogen excretion doubled relative to controls and urea comprised 85% of waste nitrogen. The activity of phosphate dependent glutaminase (PDG), a renal ammonia‐producing enzyme, did not decrease even though ammonia excretion decreased by more than 50% in experimental animals. Structurally, flask cells had shrunken and contained little GAG. The average number of distended flask cells within profiles of intermediate segments dropped from about 2 in control animals to 0.60 in animals stressed for 14 days.Acidosis was induced in Xenopus by injecting a single dose of 2.5 mM HCl per kg body weight. In these animals, ammonia excretion increased 160% over controls and PDG activity increased 30%. The number of flask cells in intermediate segment profiles increased from 2.02 in controls to 4.16 in experimental animals.These results demonstrate that the number of distended flask cells and their morphology are altered by conditions which change patterns of nitrogen excretion; therefore, the flask cells may be directly involved with ammonia excretion.
Aminoethylphosphonic acid‐containing glycoproteins: The acid mucopolysaccharide‐like components in mucus from Metridium senile (L.)
Authors: Bunde Terry A. , Dearlove George E. , Bishop Stephen H. 
Published: June 2005

AbstractThe sea anemone, Metridium senile, is covered with a sticky mucus which facilitates the trapping of plankton from the sea water. Histochemical procedures indicate that this acid mucopolysaccharide‐like (AMPS‐like) mucus is secreted by the columnar epithelial cells of the body surface. High Pressure Liquid Chromatography resolves the mucus into two high molecular weight acidic glycoproteins, neither of which contains any of the typical AMPS substituents of higher organisms (sulfate esters, glucuronic acid and sialic acid). Both of these glycoprotein fractions do, however, contain 2‐aminoethylphosphonic acid (AEP). Histochemical procedures carried out in conjunction with wet chemical analyses indicate that these AEP‐glycoprotein complexes not only account for the AMPS‐like staining material on the surface (mucus) of these animals, but also may have some function in the intracellular matrix.
Cyclic AMP and ouabain‐binding sites in the rectal gland of the dogfish Scyliorhinus canicula
Authors: Shuttleworth T. J. , Thompson J. L. 
Published: June 2005

AbstractA technique for measuring the binding of 3H ouabain to tissue from the elasmobranch rectal gland is described. Concentrations of dibutyryl cAMP and theophylline that have previously been shown to stimulate secretion from the perfused gland produce a large increase in the degree of ouabain binding and the implications of this in the possible control of secretion rate are discussed.
Rate of egg penetration in vitro accelerated by T/t locus in the mouse
Authors: Olds‐Clarke P. , Carey J. E. 
Published: June 2005

AbstractSpermatozoa from fertile mice heterozygous for tw32, a recessive lethal allele of the T/t locus, were compared to normal spermatozoa in a fertilization in vitro system. The rate of egg penetration following insemination in vitro was determined for epididymal spermatozoa from C57BL/6‐tw32 + mice and for epididymal spermatozoa from C57BL/6‐ + / + mice. At one hour after insemination, the mean of penetration ± standard deviation for spermatozoa from BL/6‐tw32 + mice was 20% ± 2.1 (109 eggs observed, 5 experiments), while the mean for spermatozoa from BL/6‐ +/+ mice was 1% ± 1.5 (107 eggs observed, 4 experiments). By five hours post‐insemination, the levels of egg penetration were not significantly different. These results suggest that tw32 increases the initial rate of egg penetration. Preliminary observations of spermmotility and sperm‐egg association at one hour post‐insemination in vitro do not support the hypothesis that this earlier penetration is due to improved sperm progress to the egg. Rather, the earlier penetration may be a result of changes in the timing of capacitation, the acrosome reaction, or sperm‐egg fusion. It is possible that the earlier penetration may play a role in the distortion of the transmission ratio of tw32.
Cytogenetics of the South American akodont rodents (Cricetidae). IV. Interspecific crosses between Akodon dolores × Akodon molinae
Authors: Merani Susana , Lizarralde Martha , Oliveira Daniel , Bianchi Nestor 
Published: June 2005

AbstractInterspecific hybridization of Akodon molinae × Akodon dolores was obtained by crossing animals from our laboratory breeding colony. Sixteen pregnant females which produced a total of 86 Akodon hybrids were obtained from a total of 40 matings. The sex ratio in the hybrids was 2.58 males for each female. No clear explanation for this abnormal ratio can at the present time be given; however it cannot be ascribed to a phenomenon of intrauterine selection between sexes. The presence of natural hybrids has not been detected; therefore, the appearance of Akodon molinae × Akodon dolores hybrids is up to this moment a laboratory phenomenon.
Studies on oocyte maturation of the medaka, Oryzias latipes. VI. Relationship between the circadian cycle of oocyte maturation and activity of the pituitary gland
Authors: Iwamatsu T. 
Published: June 2005

AbstractThe relationship between pituitary activity and oocyte maturation was examined in Oryzias latipes (medaka), which has a circadian cycle of oviposition. Throughout the circadian cycle of oviposition, females possessed a population of large oocytes more than 800 μm in diameter that could mature in the presence of gonadotropin. Oocyte maturation was observed in vitro in females hypophysectomized between three and ten hours after the beginning of the light period with the number of maturing oocytes increasing as hypophysectomy was delayed. Although in vivo oocyte maturation was blocked by hypophysectomy within two hours after the beginning of the light period, it was restored by a single injection of synthetic or mammalian pituitary hormones (gonadotropic, corticotropic and thyrotropic hormones) within ten hours after hypophysectomy. Of these pituitary hormones, FSH, LH and TSH could induce in vitro maturation of isolated oocytes. Oocytes matured in vitro in the absence of exogeneous hormones if they were isolated nine or more hours after the onset of light. The present study indicates that the circadian cycle of maturation of Oryzias oocytes is controlled by the release of pituitary hormone between three and nine hours after the beginning of the light period.
Indirect nervous control of luminescence in the polynoid worm Harmothoe lunulata
Authors: Nicolas Marie‐ThèRèSe , Moreau Marc , Guerrier Pierre 
Published: June 2005

AbstractLight responses were recorded in vitro from isolated elytra of Harmothoë lunulata following field or intraganglionic stimulation. Similar responses were evoked through bath application or microinjection of acetylcholine (ACh) at the level of the ganglion. Antimuscarinic but not antinicotinic inhibitors reversibly blocked these responses. In these conditions, when the nervous system is blocked, the preparation no longer respond to K+ ions depolarization nor to electrical field stimulation (depolarizing or hyperpolarizing currents). These new data strongly suggest that a cholinergic nervous system controls light production through muscarinic receptors which are not localized at the level of the photocyte and definitively rules out the possibility that propagation of the stimulus involves epithelial conduction. We propose that the activation occurs through relaying structures different from the epithelium. Calcium may be involved in the transmission process since inhibitors of its movements also block light response.
Alanine biosynthesis during starvation in skeletal muscle of the spiny dogfish, Squalus acanthias
Authors: Leech Anthony R. , Goldstein Leon , Cha Chung‐Ja , Goldstein Jonathan M. 
Published: June 2005

AbstractThe release of alanine by dogfish (Squalus acanthias) skeletal muscle was assayed in vivo and alanine biosynthesis was characterized in vitro. Amino acid analyses of blood drawn from dorsal aorta and caudal vein indicated that after one day of starvation only alanine was released by tail muscle in statistically significant amounts. Alanine continued to be released for the following two weeks of starvation but fell significantly after that. Pelvic‐findepressor muscles incubated in a physiological medium synthesized significant amounts of alanine. This synthesis was dependent on a source of added isoleucine (or leucine) but not glucose. Addition to the incubation medium of 3‐mercaptopicolinic acid, an inhibitor of phosphoenolpyruvate carboxykinase had no effect on alanie biosynthesis. Thus, release of alanine by dogfish skeletal muscle is similar to that in mammals, but factors regulating biosynthesis may be different in the two groups.
Analysis of the physical forces that influence the shape of chick somites
Authors: Packard David S. , Jacobson Antone G. 
Published: June 2005

AbstractWith experiments and measurements we support the hypothesis that chick somites are shaped by packing forces produced by increases in somite volumes. Volume measurements show that somites expand considerably during the period from initial segmentation to acquisition of the mature rectangular shape (as viewed from above). Anterior somites begin as roundish objects. Somite expansion flattens the intersomitic faces. Posterior somites emerge from a compressed segmental plate with the interface between somite and segmental plate already planar. In all somites, subsequent increase in volume causes expansion dorsally, ventrally and laterally. The dorso‐ventral expansion accompanies the increase in height of the neural tube. When a single somite is excised, neighboring somites or segmental plate fill in the available space. The bulging of somites into vacated spaces suggests the presence of compression which could be the product of previous increase in somite volumes. The pliability of somites is demonstrated with experiments that bend the trunk of the embryo to the left and right reversibly changing the shapes of the somites. Carbon marks placed in pairs in somites and in adjacent neural tube stay together; this suggests that somites do not move relative to the neural tube in response to the compressive forces. Segmental plates isolated without neural tube or notochord form long oval somites. In order to be shaped properly, somites must be in intimate association with, and probably bound to, the neural tube and also most likely the notochord.
α‐Ecdysone does not induce ovarian development in adult Aedes aegypti
Authors: Fuchs M. S. , Schlaeger D. A. , Shroyer C. 
Published: June 2005

AbstractPrevious findings have shown that vitellogenesis is initiated in non‐blood‐fed Aedes aegypti by injection of the insect steroid hormone ecdysterone. The precursor of ecdysterone, α‐ecdysone was assayed for its ability to induce ovarian development. Both the amount of vitellin deposited into ovarian follicles and the dopa decarboxylase activity were monitored. In contrast to ecdysterone, α‐ecdysone was negative with regard to both parameters. In addition, 22‐isoecdysone, previously reported to be active, was also shown to be ineffective. These findings suggest that the C20 hydroxylating mechanism necessary to convert α‐ecdysone to ecdysterone is absent in unfed females, but is activated by the blood‐meal.
Inhibition of estrous cyclicity in golden hamsters by melatonin administration on the day of proestrus
Authors: Andre Joel S. , Parrish John 
Published: June 2005

AbstractSingle injections of melatonin (25 micrograms) were administered to female hamsters, 15 minutes before lights‐out (14L:10D), during either the early diestrous (day 1) or proestrous (day 4) phase of the estrous cycle. Hamsters which received melatonin only on the evening of proestrus became anovulatory by three weeks of treatment, while those that were injected with melatonin during diestrus, or administered oil on either day 1 or 4, continued to exhibit normal estrous cycles. These results indicate that quartan injections of melatonin can suppress reproductive function in female hamsters, and that the effectiveness of the injections may be dependent upon the stage of the estrous cycle at which they are administered.
Comparative enzymology and physiological role of D‐lactate dehydrogenase from the foot muscle of two gastropod molluscs
Authors: Long George L. , Ellington W. Ross , Duda Timothy F. 
Published: June 2005

AbstractD‐Lactate dehydrogenases from the foot muscles of the black abalone, Haliotis cracherodii, and the pulmonate snail, Helix aspersa, have been characterized. The D‐lactate dehydrogenase from H. cracherodii, which is found as a single, isoenzymic form, was purified to homogeneity. The enzyme in H. aspersa foot muscle is found as two distinct fast and slow migrating electrophoretic complexes of isoenzymes. The most abundant isoenzyme in the slow electrophoretic complex of H. aspersa was purified to homogeneity. The purified enzymes from the two organisms have similar physical and catalytic properties to one another and to other D‐lactate dehydrogenases, suggesting a close evolutionary relationship. Purified D‐lactate dehydrogenases from H. cracherodii and H. aspersa have molecular weights of approximately 80,000, as judged by meniscus depletion sedimentation equilibrium experiments, which correspond to a dimeric subunit organization. Kinetic studies show that the apparent Michaelis constant for pyruvate is 0.2–0.3 mM for the two purified enzymes as well as the partially purified fast isoenzymic complex from snail. Km values for D‐lactate are about ten times higher. Km values for α‐ketobutyrate are 4–10 mM for all three enzymes and Vmax is approximately 40–80% of that seen with pyruvate, suggesting that the enzymes may be physiologically important in dealing with α‐ketoacids in general. Km'S for NADH are all 10–20 μM, and those for NAD+ about 10‐fold greater. The most notable catalytic difference between the two enzymes is the presence and absence of substrate inhibition by pyruvate of the abalone and snail enzymes, respectively. This difference may reflect different physiological roles for the enzyme in the two organisms.
Role of neural crest in determining the numbers of pigment cells in the melanoid mutant of Ambystoma mexicanum Shaw
Authors: Sawada Soledad Rivera , Dalton H. Clark 
Published: June 2005

AbstractExperiments are reported testing whether the primary control of chromatophore development under the influence of the melanoid gene (m) in the axolotl is exerted by factors intrinsic or extrinsic to the chromatoblasts of the neural crest. Melanoid animals differ from the wild type in having more melanophores, fewer xanthophores and no iridophores. The total number of chromatophores remains unchanged. This is interpreted as evidence of a common stem cell derivation of melanophores and xanthophores in the axolotl. Hanging drop explants of melanoid neural crest duplicate the skin chromatophore ratios. Chromatophore counts from epidermal vesicles consisting of neural crest and somatopleure in different genotypic combinations provide the ratios expected according to the genotype of the neural crest component. In reciprocal homotopic transplantations of neural crest between melanoid and wild type embryos, donor type pigment patterns develop. These studies show that the effect of gene m is mediated by factors intrinsic to the neural crest cells prior to their migration.
CO2 exchange in the blue crab, Callinectes sapidus (Rathbun)
Authors: Aldridge James B. , Cameron James N. 
Published: June 2005

AbstractThis study represents a first attempt to describe the pattern of carbon dioxide excretion in the gills of the blue crab, Callinectes sapidus. A computer simulation model was constructed, based on measurements of gill morphometry and blood carbon dioxide concentrations. Results of the simulation indicated that, although carbonic anhydrase is available in the gill epithelium for dehydration of HCO3−, it is probably not significantly involved in CO2 excretion. This conclusion was further supported by the observation that injection of a carbonic anhydrase inhibitor had no detectable effect on blood concentrations of CO2. Disequilibrium of the CO2‐HCO3− system is proposed as a significant factor in accounting for CO2 excretion.
The effect of ouabain on blood NaCl in the osmoregulating clam Rangia cuneata
Authors: Mangum C. P. , Henry R. P. , Simpson D. M. 
Published: June 2005

AbstractExposure of R. cuneata to exogenous ouabain is not lethal for several days. In both hypo‐ and hypersaline media, O2 uptake is uninhibited for periods up to 17 hr. Blood NaCl changes significantly, both before and after O2 uptake finally ceases. Changes in blood osmolality, however, are closely related to blood CaHCO3 and normal aerobic respiration.
Anaerobic rat heart: Mitochondrial role in calcium uptake and contractility
Authors: Shertzer Howard G. , Cascarano Joseph 
Published: June 2005

AbstractIn order to evaluate the manner by which fumarate enhances contractility in the anaerobic heart, we examined Ca++ movements in isolated heart mitochondria and in the isolated perfused heart. Our experiments showed that in isolated antimycin A plus cyanide treated mitochondria: (a) Ca++ uptake was promoted by electron transport generated by fumarate‐dependent oxidation of NADH, (b) Ca++ stimulated fumarate‐dependent oxidation of NADH, (c) the ratio of Ca++ uptake:NADH oxidized was 1.7 and (d) the Ca++ sequestered is transiently highly mobile and is rapidly released upon collapse of the membrane potential. In anaerobic hearts perfused with glucose plus fumarate, malate and glutamate Ca++ levels were the same as those in oxygenated hearts while in anaerobic organs perfused with or without glucose Ca++ content was appreciably lower. Succinate production in anaerobic heart perfusions was related to: (a) an increased retention of Ca++ by the heart, (b) a diminution in peak aortic pressure generated by cardiac contractions and (c) an increase in heart rate. The information obtained indicates that mitochondria have a capability for Ca++ movement which might be used physiologically, particularly in fumarate perfused anaerobic hearts, to assist the mechanism for contraction and relaxation of the heart.
Aldehyde dehydrogenase of the Mongolian gerbil, Meriones unguiculatus
Authors: Simpson Ford , Lindahl Ronald 
Published: June 2005

AbstractThe aldehyde dehydrogenase (Aldehyde:NAD(P) oxidoreductase E.C. 1.2.1.3 and 1.2.1.5) phenotype in several tissues of the Mongolian gerbil, Meriones unguiculatus, has been established. The tissue distribution of gerbil aldehyde dehydrogenase is similar to that of the rat, with liver possessing the majority of the aldehyde dehydrogenase activity. Male kidney and testis possess significantly more activity than female kidney and ovary. The substrate and co‐enzyme specificity of gerbil liver aldehyde dehydrogenase is also similar to that of rat and mouse liver. Gel isoelectric focusing resolves one major gerbil liver aldehyde dehydrogenase isozyme at pI 5.3. Mouse liver is resolved into two major isozymes at pIs 5.3 and 5.6 and rat liver aldehyde dehydrogenase into one major isozyme at pI 5.4. Gerbil liver aldehyde dehydrogenase is functional over a broad pH range with an optima at pH 9.0. Rat and mouse liver aldehyde dehydrogenase possess sharp pH optima at pH 8.5.