bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlated structural and contractile properties in specialized fibers of a woodlouse Armadillidium vulgare (Latr.)
Authors: Daniela Candia Carnevali M. , Saita Abele 
Published: September 2005

AbstractIn order to define the ultrastructural differences between slow‐contracting (tonic) muscles with differing abilities to develop tension, observaticns were made on Armadillidium vulgare, comparing muscle structure and function. The latero‐ventral muscles, by means of which the animal holds itself rolled up in a tight ball, were compared with the dorsal intersegmental muscles. which pull it back to a normal stance. The morphological differences found are easily interpreted in the light of the different functions of the two types of muscle. Where the muscles are more powerful, and have to hold considerable tension, the contractile system is stronger (myosin filaments are 7 μm long and 200 Å thick; the ratio of thin to thick filaments is 6 or 7: 1; there is a thick filament density of 610 filaments per μm2). In the dorsal intersegmental muscles, which have less resistance, the system is simpler: myosin filaments are 4 μm long and 150 Å thick; the ratio of thin to thick filaments is 4: 1; and the thick filament density is lower — 510 filaments per μm2.
Inhibition of pigment migration in tail fin melanophores of Xenopus tadpoles in oxygen‐free media
Authors: Iga Tetsuro , Bagnara Joseph T. 
Published: September 2005

AbstractThe dispersion of melanosomes in the darkness‐induced darkening of Xenopus tailfin melanophores does not occur in an oxygen‐free medium. When such tails are restored to lighted conditions in the presence of oxygen, dispersion takes place as an “after effect” indicating that light reception and melanosome dispersion are two separate components of the tail‐darkening reaction. Aggregation of tailfin melanosomes is also inhibited by the absence of oxygen.
Male haploidy in rotifers: Relative DNA content of nuclei from male and female asplanchna
Authors: Jones Philip A. , Gilbert John J. 
Published: September 2005

AbstractIn A. sieboldi mitotic nuclei of males had one‐half the nuclear DNA content of those of females. Spermatocytes from testes had lc DNA contents. These observations indicate that the male is haploid and that spermatogenesis is atypical and involves no reductional divisions.
Effects of pupal diapause on the metamorphosis of the nervous system inPieris brassicaeL.
Authors: Puiroux Jacques , Moreau Robert , Lavenseau Lucien 
Published: September 2005

AbstractThe structural evolution of nervous tissues during the postembryonic development ofPieris brassicaehas already been described in same detail but the effects of diapause on this process have not been examined. In this report, we demonstrate that the nervous system of a diapausing insect is characterized by a typical pattern of morphogenesis, which includes the arrest of the differentiation of the brain and the ventral nerve cord. This arrest occurs at a specific phase of pupation (third day of diapause) and persists throughout diapause, being independent of the storage temperture. No sign of progressive adult differentiation, referred to in other insect species as “diapause development,” is apparent. Rapid breakdown of this arrest occurred when diapausing pupae were exposed to summer conditions after an initial 2 month period at 4°C. Resumption of the morphogenesis of the nervous system was evident within 4 to 5 days in most experimental batches, with resultant differentiation to the adult state. © 1993 Wiley‐Liss, Inc.
Effects of an antiandrogen treatment on morphological characters and physiological functions of male fallow deer (Dama dama L.)
Authors: Kolle Renate , Kierdorf Uwe , Fischer Klaus 
Published: September 2005

AbstractFrom mid‐April to late November, i.e., during antler growth phase and main breeding season, a group of four (later three) male fallow deer was treated with increasing doses of the antiandrogen cyproterone acetate (CA). Throughout the treatment period, plasma testosterone levels of the bucks were either undetectable or only slightly above the detection limit of 0.1 ng/ml. In marked contrast to controls, testicular volumes and neck girths of the CA treated bucks were basal during the application period, proving the strong antigonadotropic effect of CA (testicular volume) and the absence of androgen action at the normal target organs (neck girths), respectively. Antler growth in the CA treated bucks occurred during the normal time span for fallow deer and the antlers produced were of species specific shape. From this it is concluded that in fallow deer, onset, duration, and termination of antler growth are independent of androgen action. Velvet shedding in the CA treated bucks however did not occur at the normal time (late August/early September), but was postponed until late December/early January, i.e., about 5 weeks after the termination of CA application. Activity of alkaline phosphatase in the experimental animals increased during the antler growth phase, but was markedly lower than in controls. Maximum body weight in the CA treated bucks was reached already in June, i.e., about 3 months prior to controls. Furthermore, the rut associated, drastic decline in body weight observed in controls did not occur in the experimental animals. © 1993 Wiley‐Liss, Inc.
Mechanisms of arm regeneration in the feather star Antedon mediterranea: Healing of wound and early stages of development
Authors: Carnevali M. Daniela Candia , Lucca Elisa , Bonasoro Francesco 
Published: September 2005

AbstractCrinoids have remarkable regenerative capacities. After traumatic or self‐induced amputation they can replace one or several arms through a complex sequence of morphogenetic events which lead quickly to the complete reconstruction of the lost part. These phenomena are well known in their general aspects and a comprehensive description of arm regeneration was previously provided (Candia Carnevali et al., Recent Trends in Regeneration Research. Plenum Press, New York, '89). However, there is a considerable gap in knowledge of the early regenerative phases which are particularly significant for the following development. The aim of the present work is to describe and interpret the different aspects of these early stages of arm regeneration in Antedon mediterranea. According to our results the regenerative development of Antedon arm seems to consist of an epimorphic process which essentially implies the involvement of proliferating undifferentiated cells. The early stages of this process can be distinguished in a first repair phase, which includes the overall 24 hr post‐amputation period and is characterized mainly by the processes of wound healing and tissue repair, and in a second regenerative phase, which includes the 24–72 hr post‐amputation period and is characterized by the first regenerative events. The different arm components involved in the amputation/regeneration phenomena seem to play different and specific roles in these initial phases. © 1993 Wiley‐Liss, Inc.
Energy metabolism of the trophectoderm and inner cell mass of the mouse blastocyst
Authors: Hewitson Laura C. , Leese Henry J. 
Published: September 2005

AbstractThe two cell populations of the day 5 mouse blastocyst–the inner cell mass (ICM) and trophectoderm (TE)–were isolated by immunosurgery and TE biopsy. The uptake of glucose and pyruvate and the production of lactate were measured in the isolated cell populations and in single day 5 blastocysts, using a non‐invasive ultramicrofluorescence technique. The number of cells in isolated ICMs, TE vesicles, and intact blastocysts were counted after differential labeling with fluorochromes. The uptake of glucose and the formation of lactate were approximately three and five times greater, respectively, in the ICM cells compared with the TE cells. All the glucose consumed by the ICM could be accounted for by lactate formation, whereas the value for TE was 55%. The uptake of pyruvate was low in both cell types. The results are consistent with the proposition that the TE acts as a transporting epithelium, sparing nutrients for metabolism by the ICM. © 1993 Wiley‐Liss, Inc.
β‐Hydroxybutyrate dehydrogenase in teleost fish
Authors: Leblanc P. J. , Ballantyne J. S. 
Published: September 2005

AbstractWe have demonstrated the presence of β‐hydroxybutyrate dehydrogenase (β‐HBDH) in tissues of a variety of freshwater and marine teleosts. This enzyme was previously thought to be absent in teleost fish. β‐HBDH activity was examined in four freshwater teleosts: goldfish, Carassius auratus, northern brown bullhead, Ictalurus nebulosus, northern pike, Esox lucius, and black crappie, Pomoxis nigromaculatus, and three marine teleosts; alewife, Alosa pseudoharengus, smelt, Osmerus mordax, and mummichog, Fundulus heteroclitus. Enzyme activity was observed in all fish examined. Highest activity was in the kidney and liver of fresh water teleosts and in the brain and liver of the marine teleosts. © 1993 Wiley‐Liss, Inc.
Stretch sensory ovarian‐preoptic pathway in the teleost, Clarias batrachus (Linn.): Transection studies
Authors: Deshmukh Makrand K. , Subhedar Nishikant 
Published: September 2005

AbstractApplication of intraovarian pressure (IOP), coupled with placement of discrete lesions, has been employed to study the organization of the pressure excitable ovarian‐preoptic pathway in a teleost, Clarias batrachus. While bilateral administration of the IOP triggered stimulatory changes in the nucleus preopticus (NPO), they were abolished if the IOP administration was preceded by the bilateral transection at the level of (1) foramen magnum, (2) spinal cord at the level of 13th vertebra, (3) dorsal spinal nerve roots between the levels of 13th and 21st vertebrae, and (4) at the junction between the common oviduct and the body wall. On the other hand, bilateral sectioning of the anterior mesovarium, the vagi, or the spinal cord at the level of 21st vertebra had no effect. Unilateral administration of the IOP triggered bilateral changes in the NPO. It seems that the stretch receptors in the ovarian wall give rise to processes that proceed along the margin of the oviduct and enter the spinal cord via the dorsal nerve roots between 13th and 21st vertebrae. Thereafter, the pathway seems to ascend over the spinal cord and impinge on the ipsilateral as well as contralateral NPO. © 1993 Wiley‐Liss, Inc.
At high dietary levels ethanol alters the structure of mid‐ and hindgut epithelial cells of Drosophila melanogaster larvae
Authors: Hartman Jennifer R. , Dybas Linda K. , Geer Billy W. 
Published: September 2005

AbstractThe midgut of Drosophila melanogaster is a site of alcohol dehydrogenase (ADH) activity, the enzyme that catalyzes the first step in the major pathway for ethanol degradation. The effects of different levels of dietary ethanol on the ultrastructures of the guts of larvae of the Canton‐S wild‐type strain and the ADH‐deficient, Adhn2, strain were ascertained. In wild‐type larvae fed an ethanol‐free, defined medium, the foregut epithelium was characterized by few glycogen rosettes and sparse microvilli that protruded into the gut's thick lumen lining. The midgut epithelium was typical of cells involved in absorption and active transport with abundant microvilli on the apical surface and membrane infolding on the basal surface. In place of microvilli, the apical surface of the hindgut had membrane infoldings. The apical surfaces of both the mid‐ and hindgut epithelium were covered by a thick, electron‐dense peritrophic membrane consisting of chitin. In both strains the subcellular damage that was correlated with ethanol levels in the diet was confined to the midgut and hindgut regions. Damage to gut cells in the form of disrupted mitochondria, dilated rough endoplasmic reticulum, low densities of glycogen rosettes and protein granules, high numbers of autophagic vacuoles, and the presence of myelin whirls was extensive in Canton‐S strain larvae fed a high ethanol diet. A low dietary concentration of ethanol induced changes in gut ultrastructure of Adhn2 larvae similar to the changes that were observed in wild‐type larvae fed the higher ethanol concentrations, but the basal infoldings were more dilated in the Adhn2 larvae. At high dietary concentrations the disruption of mid‐ and hindgut cells by ethanol appeared great enough to interfere with the digestion and absorption of nutrients. © 1993 wiley‐Liss, Inc.
Calcium control of metamorphosis in polychaete larvae
Authors: Ilan Micha , Jensen Rebecca A. , Morse Daniel E. 
Published: September 2005

AbstractThe importance of Ca2+ in the control of metamorphosis of a marine invertebrate larva was investigated. An excess of [Ca2+] in the external medium induced metamorphosis of Phragmatopoma californica (polychaete) larvae in a concentration‐dependent manner. This effect is specific for calcium, and not simply the result of osmotic changes, as an excess of Mg2+ did not induce metamorphosis. Consistent with this finding, the calcium ionophore, A23187, also induced metamorphosis in a concentration‐dependent manner. Paradoxically, however, the aromatic compounds diltiazem, verapamil, D600, and nifedipine, known to block Ca2+ channels in other systems, also induced metamorphosis. When exposed to diltiazem for only 20 h and subsequently washed free of this compound, 95% of the larvae metamorphosed and developed normally. Previous studies have demonstrated that the induction of metamorphosis in Phragmatopoma californica is controlled by chemosensory recognition of an exogenous morphogen and mediated by an excitatory pathway that involves adenyl cyclase and cyclic AMP. Because cellular excitation and cyclic AMP‐dependent signal transduction generally involve the participation of calcium ion, the most parsimonious explanation for the results reported here include (1) direct control of the morphogenetic pathway by calcium ion, and (2) complexities of the calcium regulation of this process, or a functional similarity between the structurally related aromatic effectors tested and the natural inducer of metamorphosis. © 1993 wiley‐Liss, Inc.
Locations of the ectodermal and nonectodermal subdivisions of the epiblast at stages 3 and 4 of avian gastrulation and neurulation
Authors: Garcia‐Martinez Virginio , Alvarez Ignacio S. , Schoenwolf Gary C. 
Published: September 2005

AbstractA prospective fate map of the avian epiblast at late gastrula and early neurula stages has been generated through the construction of quail/chick transplantation chimeras. This map shows the subdivisions of the prospective ectoderm, mesoderm, and endoderm, both within the epiblast prior to their ingression and within the primitive streak. The map demarcates the locations and extents of the prospective surface ectoderm, otic placodes, neural crest, and neural plate‐including its postnodal levels—in prospective ectoderm of the epiblast; prospective foregut, within the prospective endoderm of the epiblast and primitive streak; and prospective notochord, somites, intermediate mesoderm, lateral plate mesoderm, and extraembryonic mesoderm in the prospective mesoderm of the epiblast and/or primitive streak. Prospective cardiogenic cells are apparently absent from the primitive streak at these stages, and contributions of the epiblast to the heart are relatively scant and inconsistent with the expected timing and directions of migrations of prospective cardiogenic cells. Mapping of the primitive streak at earlier stages in another study (García‐Martinez and Schoenwolf: Developmental Biology, in press) reveals that the ingression of cardiogenic cells through the primitive streak occurs prior to late gastrula stages, suggesting that contributions of epiblast to the heart at later stages are artifactual. Tests of prospective potency, based on the projected locations of origin of various cell groups provided by the new prospective fate map, are underway. © 1993 wiley‐Liss, Inc.
Formation of distal structures from stumps of chick wing buds at stages 24–25 following the grafting of quail tissue from X‐irradiated distal limb buds
Authors: Watanabe A. , Ohsugi K. , Ide H. 
Published: September 2005

AbstractTo examine the regulatory activity of the proximal region of chick limb buds, distal halves of chick wing buds at stages 24–25 were removed, and the distal tips of X‐irradiated stage 21 quail limb buds with an apical ectodermal ridge (AER) were grafted onto the chick stumps. The host stumps formed only humerus after removal of the donor distal tips or with tip mesoderm alone. However, when distal tips with an AER were grafted onto the stumps, one or two cartilage elements of host origin were formed at the distal end of the humerus.To examine whether the stump cells have changed to cells of a more distal, progress zone (PZ) cells, the chick stumps with quail tips were immunostained with antibody against AV‐1, which reacts with the anterior PZ region of chick limb buds and is specific for an antigen that is expressed under the control of the AER. Within two days of grafting, cells positive for the antigen reapperaed in the stump tissues.These results suggest that the some of the stump cells may be converted to PZ cells and their positional values may change to those of more distal structures under the influence of the AER. © 1993 wiley‐Liss, Inc.
Tests of the ability of two‐cell mouse embryos to utilize selected precursors of phosphoenolpyruvic acid and pyruvic acid
Authors: Shirley Barbara 
Published: September 2005

AbstractPhosphoenolpyruvic acid and pyruvic acid are among the few compounds that two‐cell mouse embryos have been found capable of using as energy sources; most of the compounds in the glycolytic pathway and Krebs cycle that have been tested have been found unusable. Because 3‐phosphoglyceric acid of the compound converted most directly to phosphoenolpyruvic acid in glycolysis, one objective of this study was to examine whether it could support development of two‐cell embryos as phosphoenolpyruvic acid can. An additional objective was to examine whether alanine or serine, two amino acids that in later stages of development are converted to pyruvic acid for entry into the Krebs cycle, could support development of two‐cell embryos as pyruvate does. Two‐cell embryos were obtained from the oviducts of mice (C57BL × CBA) and were cultured in medium that contained 3‐phosphoglyceric acid, alanine, or serine in lieu of the pyruvate, lactate, and glucose usually contained in the medium. The embryos failed to undergo cleavage but this was not attributable to only a single energy source having been provided; embryos developed in a medium that provided only pyruvate. The results suggest that mouse embryos at the two‐cell stage of development are either unable to transport 3‐phosphoglyceric acid, alanine, and/or serine or are unable to convert the compounds to chemically similar ones; phosphoenolpyruvic acid or pyruvic acid, which can be metabolized by two‐cell mouse embryos. The results offer additional evidence that compounds more than one step removed from pyruvate in metabolic pathways are not used by two‐cell mouse embryos and, furthermore, suggest that the embryos cannot use alanine even though it is but a single step removed from pyruvate. © 1993 wiley‐Liss, Inc.
Production of viable haploid Oreochromis mossambicus gynogens using UV‐irradiated sperm
Authors: Varadaraj K. 
Published: September 2005

AbstractHaploid and homozygous diploid mitotic gynogens of Oreochromis mossambicus were successfully produced using UV‐irradiated sperm. Optimum UV‐irradiation duration required for the production of 100% haploid was 10 min. Irradiation for more than 15 min caused loss of motility in sperm. Normal homozygous diploid mitotic gynogens were produced by heat shocking 70 min old activated haploid eggs. Haploids had 22 chromosomes, including a large subtelocentric chromosome; diploid mitotic gynogens had 44 chromosomes, including a pair of large subtelocentric chromosomes. Ratio of nuclear volume of haploid fish RBCs to diploid RBCs was 0.53:1, whereas that of relative DNA content was 0.4:1. Haploids were viable; however, they suffered from characteristic syndromes like poorly developed retina, twisted edematous body and curved tail. There was also a reduction in the number of vertebrae in the caudal region of haploids; only 4–5% eventually survived. These observations indicate that the syndrome characters and the lower rate of survival in haploid O. mossambicus may be more due to the absence of normal genes in pairs in homologous or heterologous chromosomes rather than due to the presence of lethal genes. © 1993 wiley‐Liss, Inc.
Tissue specificity of arthropod tropomyosin
Authors: Miyazaki Jun‐Ichi , Yahata Kensuke , Makioka Toshiki , Hirabayashi Tamio 
Published: September 2005

AbstractIn order to elucidate whether tropomyosin isoforms have different tissue‐specific functions, we examined tissue specificity of tropomyosin by two‐dimensional gel electrophoresis and immunoreplica tests using three arthropod species. These arthropods showed molecular heterogeneity and tissue specificity of tropomyosin in muscle and nonmuscle tissues. The beetle (Insecta) and centipede (Chilopoda) had three different isoforms. The scorpion (Arachnida) had six isoforms, two of which were nonmuscle‐specific. In addition to these isoforms, all the species contained nonmusclespecific isoforms of high electrophoretic mobilities and another isoform with a high electrophoretic mobility was found in the beetle heart and intestine. We summarized the results including the data from our previous studies on the horseshoe crab (Merostomata) and five crustaceans (Crustacea) and found that most isoforms were not shared by every tissue but detected in some particular tissues. In that sense, they were tissue specific, but each of them was not restricted to a single tissue. However, crustacean cardiac isoforms were contained exclusively in the hearts, and some of the nonmuscle isoforms were not found in other tissues; thus they were tissue specific in the strict sense. Considering our results and those on vertebrate tropomyosin together, we suggest that the existence of different isoforms alone does not imply straightforwardly different functions among the isoforms and that only strictly tissue‐specific isoforms can be assumed to have functions peculiar to their tissues. © 1993 wiley‐Liss, Inc.
Subcutaneous compliance and gravitational adaptation in snakes
Authors: Lillywhite Harvey B. 
Published: September 2005

AbstractPrevious studies have implicated morphological adaptations as important countermeasures to gravitational stresses on the circulatory systems of arboreal or climbing snakes. Such features include tight skin and relatively non‐compliant tissue compartments that oppose edema formation, but these traits have not been previously studied quantitatively. To provide information on this subject, interstitial fluid pressures were measured in eleven species of snakes using slit‐end catheters positioned in subcutaneous tissue located at the base of the tail. Interstitial pressures in all species were typically 0 to + 2 mm Hg in normally hydrated tissue, but varied widely when snakes were active or when the tail was curved at the site of measurement. Local compliance of the free fluid space was determined from measurements of pressure while saline was infused via the catheter tip. Such measurements varied from 0.18 μl/mm Hg inPhilodryas baroni, an arboreal species, to 2.3 μ/mm Hg inCrotalus adamanteus, a ground‐dwelling, terrestrial species. In general, compliance of the subcutaneous tissue space was greatest (P< 0.05) in non‐climbing and aquatic species of snakes that do not face problems of gravitational edema in dependent tissues. Presumably, the compliance measurements reflect adaptive structural differences related to requirements for counteracting gravitational stresses in the various species. © 1993 Wiley‐Liss, Inc.