bluuebunny/crossref_metadata_2025_split huggingface dataset:
Budding inHydra attenuata:Bud stages and fate map
Authors: Otto Joann J. , Campbell Richard D. 
Published: June 2005

AbstractTen bud stages are defined and their profiles illustrated. A fate map of the developing bud ofHydra attenuatawas made using vital intracellular marking. Marks made at increasing distances from the young bud tip end up in increasingly more proximal regions of the bud. There is no major difference between the recruitment patterns of cells from above, below and lateral to the bud tip. The angular positions of cells on the parent is directly correlated with their final angular positions on the bud axis. Therefore, tissue is recruited in concentric rings around the young bud tip and is distorted directly outward into the bud column. At the youngest bud stages, the fate map of the bud extends about 180° around the parent.Tissue recruitment from the parent ends at the time that tentacle rudiments appear on the bud. Thus, tissue recruitment and hydranth morphogenesis are separate processes.
Liver regeneration in normal and alloxan‐induced diabetic rats
Authors: Barra Rosemary , Hall James C. 
Published: June 2005

AbstractThe effects of alloxan‐induced diabetes on liver regeneration were investigated. Normal and diabetic rats were sacrificed at eight time periods between 16 hours and 4 weeks following two‐thirds partial hepatectomy or sham operation. The results indicate that alloxan‐induced diabetes delays but does not prevent liver regeneration following partial hepatectomy. This delay is indicated by a depressed synthesis of RNA, DNA and protein during the first post‐operative day and a lack of mitotic figures in the 24‐hour sample. In addition, the synthesis of these three cellular constituents did not return to control levels as rapidly in the diabetics. Compared with the sham operated animals, the concentrations of total serum protein remained depressed longer in the diabetic hepatectomized animals. The data indicate that the metabolic alterations associated with alloxan diabetes delay the onset of the regenerative process and prolong the recovery period.
Inhibition of maturation and metabolism in rat oocytes by cyclic AMP
Authors: Magnusson Claes , Hillensjö Torbjörn 
Published: June 2005

AbstractIt is known that dibutyryl cyclic AMP (dbcAMP) and theophylline inhibit the spontaneous maturation of isolated mouse oocytes. The present study demonstrates that dbcAMP (0.01 – 1.0 mM) as well as cyclic AMP (cAMP, 10 mM) and a phosphodiesterase inhibitor (IBMX, 0.01 – 1.0 mM) prevent spontaneous maturation of isolated rat oocytes. As reported earlier an increase in oxygen consumption by the oocyte was found following maturation. When the oocytes were cultured in the presence of dbcAMP or cAMP no change in respiration occurred during culture.These results argue against the theory that cAMP acts as a direct mediator of the action of luteinizing hormone (LH) on oocyte maturation. Furthermore they suggest that changes in oocyte energy metabolism are closely related to the maturation process.
Zooxanthellae‐produced O2 promotes sea anemone expansion and eliminates oxygen debt under environmental hypoxia
Authors: Malcolm J. Malcolm , Brown Warren I. 
Published: June 2005

AbstractDuring exposure to hypoxic conditions in darkness, Anthopleura elegantissima remains contracted and incurs a physiological oxygen debt. Both of these phenomena are eliminated by maintaining anemones in the light, but not if photosynthesis by their endosymbiotic zooxanthellae is chemically inhibited, suggesting that the intracellular production of O2 stimulates expansion and enables aerobic metabolism to continue.
The ultrastructure and the hormonal control of product synthesis in the hedonic glands of the red‐spotted newt Notopthalmus viridescens
Authors: Pool Thomas B. , Dent James Norman 
Published: June 2005

AbstractThe ultrastructure and the hormonal regulation of hedonic glands in male and in female red‐spotted newts have been studied throughout the year and under various experimental conditions. Hedonic glands are simple, alveolar, merocrine glands that contain a single layer of secretory epithelial cells surrounded by a discontinuous layer of myoepithelial cells. Although hedonic glands from both sexes are alike in form, females have only about a third as many as do males. While newts are in breeding conformation during the fall, winter, and spring, large quantities of a glycoproteinaceous product are sequestered within the lumina of their hedonic glands. During those seasons the secretory cells are cuboidal and contain abundant rough endoplasmic reticulum with dilated cisternae and active Golgi complexes. Secretory granules are numerous in the apical cytoplasm and appear to be attached to microfilaments and microtubules. During the summer months, secretory cells are quiescent and assume a columnar configuration, reducing the lumen to negligible proportions. Rough endoplasmic reticulum is sparse, residual secretory granules contain small vacuities, and lipid droplets and glycogen aggregates occur. Hedonic glands of newts in breeding conformation regress to the summer state within three to four weeks under laboratory conditions. In laboratory‐conditioned, gonadectomized male newts hedonic glands remain unchanged after treatment with saline, prolactin, or testosterone but are transformed to the breeding state by treatment with prolactin and testosterone in combination. Hedonic glands from ovariectomized females respond similarly to prolactin in combination with testosterone, but fail to respond to prolactin with estradiol.
Neural regulation of product discharge from the hedonic glands of the red‐spotted newt, Notopthalmus viridescens
Authors: Pool Thomas B. , Dent James Norman , Kemphues Kenneth 
Published: June 2005

AbstractThe mechanism whereby secretory product is extruded from the lumina of hedonic glands in the red‐spotted newt has been investigated and the chemical nature of that product has been examined. The ultrastructure of the myoepithelium has been studied. Endings of unmyelinated axons, containing both clear and dense‐cored synaptic vesicles, were seen to lie between the myoepithelium and the secretory epithelium, occasionally touching on the myoepithelial cells. Mean luminal diameters of hedonic glands in explants incubated in solutions of acetyl choline decreased by 58% of control values while those of explants incubated in solutions of epinephrine remained the same. Preincubation in the muscarinic blocking agent atropine sulfate, but not in nicotinic blocking agent d‐tubocurarine chloride, prevented the cholinergic response. Two PAS (+) bands were present in polyacrylamide gels prepared from secretions discharged by hedonic glands after treatment of male newts in breeding conformation with pilocarpine HCL and also in gels from skin samples containing mucous glands, but were absent from hedonic secretions of laboratory conditioned males. A smaller but similar band from hedonic glands of breeding females correlated with one of the two. Since hedonic glands, but not mucous glands, from breeding newts of both sexes incorporated 35SO4 into their product, bands from hedonic glands could be distinguished from those of mucous glands in gels. It is concluded that the product of hedonic glands is a sulfated mucin that is discharged in response to cholinergic stimulation of muscarinic receptors in myoepithelial cells.
A scanning electron microscopic comparison of the development of embryonic and regenerating limbs in the axolotl
Authors: Tank Patrick W. , Carlson Bruce M. , Connelly Thomas G. 
Published: June 2005

AbstractA comparison between the surface features of embryonic limb development and limb regeneration was made in the axolotl. Scanning electron microscopy revealed an overall similarity between embryonic and regenerating limbs. A notable feature was the lack of a morphologically discrete apical epidermal specialization on the surface of any of the limbs. Histological preparations revealed no thickening of the apical epidermis in embryonic limbs. There is a definite thickening of the apical epidermis in regenerating limbs during the stages of dedifferentiation and the early blastemal phases, but the thickening projects into the underlying tissues rather than altering the smooth surface contours of the blastema. Minor differences in epidermal specializations (ciliated cells scattered over the entire body and very irregularly shaped cells with knoblike projections at the tips of digits in embryos) may be attributable to differences in overall activity of the animals at various stages in their life history.
In vitro fertilization of hamster eggs by ejaculated or epididymal spermatozoa in the presence of male accessory secretions
Authors: Tsunoda Y. , Chang M. C. 
Published: June 2005

AbstractIn vitro fertilization of hamster eggs by ejaculated or epididymal spermatozoa in the presence of seminal plasma or male accessory gland secretions was examined. There was no difference in the penetration rates, the time of sperm penetration and the optimal sperm concentration between ejaculated and epididymal spermatozoa. The swelling of the zona pellucida, a high incidence of polyspermy, distortion of the vitellus and the degeneration of eggs were observed after incubation of ejaculated or epididymal spermatozoa in the presence of seminal plasma or accessory gland secretions. Using ejaculated spermatozoa, the fertilization rates of eggs with or without follicular cells were similar but fertilization by epididymal spermatozoa was inhibited by secretion of the seminal vesicle or ventral prostrate gland but not by that of the coagulating gland or the dorsal prostrate.
The alkaline proteases of Argiope and their possible role in web digestion
Authors: Tillinghast E. K. , Kavanagh E. J. 
Published: June 2005

AbstractThe digestive fluid of Argiope was assayed for its proteolytic activity with selected natural and synthetic substrates.
Peak proteolytic activity was observed at pH 7.8. This was coincident with the pH of the digestive fluid.
Elastolytic and weak chymotryptic activities were detected. Limited activity toward collagen was also observed. Activity toward substrates for trypsin, leucine aminopeptidase and carpboxypeptidase A and B was absent.
Evidence demonstrating the in vitro digestion of web fibroin was obtained. The viscid spiral was susceptible to a variety of proteases; the radial fibers to the spider enzyme alone.
Of a series of inhibitors studied, EDTA had the greatest effect upon the spider proteases. This effect was temperature dependent.
Glutamate dehydrogenases from tissues of the ribbed mussel Modiolus demissus: ADP activation and possible physiological significance
Authors: Reiss Paul M. , Pierce Sidney K. , Bishop Stephen H. 
Published: June 2005

AbstractGlutamate dehydrogenase (E.C. 14.1.3) was localized in the mitochondria from heart, gill, mantle and hepatopancreas of this euryhaline bivalve mollusc. Activity levels were low (0.1‐0.4 μmoles/min/g wet weight) in all tissues when assayed in the glutamate forming direction. Partially purified gill mitochondrial GDH was most active at pH 8.5. The rate in the glutamate deaminating direction was 10‐20% of the rate in the glutamate forming direction. ADP at apparent Ka concentrations of 90 μM (glutamate formation) and 170 μM (glutamate deamination) enhanced GDH activity, 8‐ and 4‐fold respectively. GDH, in vivo, is probably in the activated form and appears to function in glutamate synthesis rather than ammonia formation. However, based on the low activities obtained, the role of GDH in salinity induced amino acid synthesis seems minimal.
In vitro culture of growing mouse oocytes
Authors: Baran Madelyn M. , Bachvarova Rosemary 
Published: June 2005

AbstractA method is described for in vitro culture of naked growing mouse oocytes for at least four days. Tests for metabolic function indicate that the oocytes increase in volume, accumulate glucose‐6‐phosphate dehydrogenase, and maintain a steady level of 3H‐uridine and 3H‐leucine incorporation.
An analysis of reproductive isolation between Rana magnaocularis and Rana berlandieri forreri (Rana pipiens complex)
Authors: Frost John S. , Bagnara Joseph T. 
Published: June 2005

AbstractThe leopard frogs (Rana pipiens complex) are presently known to include several distinct species, the geographic distributions of which involve numerous sympatries. Very little information has been reported concerning the methods through which such sympatric species maintain their distinctness in suture zones. Therefore, the object of this research was to describe the reproductive nature of the sympatric relationship existing between Rana magnaocularis and Rana berlandieri forreri in western Mexico. Observations were made of seasonal changes in ovarian development and in reproductive behavior between the two species. Genetic compatibility was assessed in numerous interspecific crosses and in backcrosses with laboratory‐produced interspecific hybrids. The breeding period of R. magnaocularis was established as early October through mid‐March and that of R. b. forreri as mid‐March through early September, but limited interspecific overlap in breeding does occur. Females of both species apparently oviposit several times during a single breeding season. Pronounced unidirectional genetic incompatibility was demonstrated in interspecific crosses and most laboratory reared hybrids were found to be sterile. Therefore, breeding season differences and genetic incompatibility (an unusual type) represent major reproductive isolating mechanisms between the two species. Several ethological traits also appear to favor conspecific reproduction, but recent habitat alterations seem to have reduced their effectiveness in the contact zone.
Uptake of amino acids by the mussel Modiolus demissus
Authors: Crowe John H. , Dickson K. A. , Otto J. L. , Colón Rita D. , Farley K. K. 
Published: June 2005

AbstractUnidirectional and net fluxes of amino acids into isolated gills and intact specimens of the mussel Modiolus demissus were studied. Influx follows Michaelis‐Menten type kinetics, with Kt = 19 and 21 μM, and Vmax = 47 and 107 μmoles/g‐hr for cycloleucine and glycine, respectively. The transport mechanism is specific for neutral amino acids, although other transport systems apparently exist for acidic and basic amino acids. Measurements of primary amines in interstitial waters from the sediments where the animals were found showed that variations in the concentration are found with depth in the sediment, with a maximal concentration of 110 μM. The major primary amines were identified as amino acids. Isolated gills were shown to deplete the medium of the naturally occurring primary amines.
An allelic variant of the sperm‐specific lactate dehydrogenase C4(LDH‐X) isozyme in humans
Authors: Wheat Thomas E. , Goldberg Erwin 
Published: June 2005

AbstractAn unusual pattern of LDH isozymes was observed by gel electrophoresis of an extract of a human testis. This isozyme composition is consistent with an allelic variant ofLdh‐c.
Development of the compound eyes of dragonflies (odonata). II. Development of the larval compound eyes
Authors: Sherk Truman E. 
Published: June 2005

AbstractThe development of the compound eye was analyzed by marking individual ommatidia and by studying naturally occurring pigment band patterns.New ommatidia are added to the eye along its anterior margin. This changes the directions of view of the older ommatidia with the greatest change occurring in the fovea. New ommatidia are added to the fovea medially, and old ones are removed laterally as their interommatidial angles and directions of view in the visual field change.Over one‐third of the aeshnid ommatidia are foveal during at least one of the early larval instars, and are then used for peripheral vision later in development.The design of each ommatidium is a compromise so that it is adapted for all stages of development, but sometimes better adapted for one instar than for others. Factors which are balanced for best vision are lens diameter, facet admission function, interommatidial angle, and inclination of the optic axis to the eye surface. Ommatidia are described in terms of these factors throughout their life history, from initial differentiation anteriorly, through passage through the fovea, to their final relatively posterior location.
Induction of supernumerary primordial germ cells by injecting vegetal pole cytoplasm into Xenopus eggs
Authors: Wakahara Masami 
Published: June 2005

AbstractA fraction, precipitated at 20,000 xG, from vegetal pole cytoplasm of Xenopus laevis eggs was able to induce supernumerary primordial germ cells (PGCs) when injected into subcortical cytoplasm near the vegetal pole of the fertilized egg. The ability to induce supernumerary PGCs was not abolished by digesting the fraction with pronase (Pronase E, 200 μg/ml, at 37° C for 30 min). The possible nature of the “germinal determinant” is discussed.
Triploid and gynogenetic diploid Xenopus laevis
Authors: Tompkins Robert 
Published: June 2005

AbstractTriploid and gynogenetic diploid Xenopus laevis frogs were produced using pressure to suppress the formation of the second polar body. Five to ten minutes after in vitro insemination, eggs were subjected to six minutes of hydrostatic pressure at 4,800 pounds per square inch. All of the surviving embryos tested were triploid. Application of the same pressure technique to eggs fertilized with ultraviolet irradiated sperm resulted in gynogenetic diploid embryos in every case where the sperm nucleus was inactivated. Triploid and gynogenetic diploid embryos developed normally through the larval period and metamorphosis.
Effects of α‐amanitin on RNA synthesis by mouse embryos in culture
Authors: Levey Irwin L. , Brinster R. L. 
Published: June 2005

AbstractInvestigations were conducted to test the effects of α‐amanitin on RNA synthesis in preimplantation mouse embryos. Exposure of embryos in culture to 1–100 μg/ml α‐amanitin produced a dose‐ and time‐dependent suppression of total RNA synthesis as measured by incorporation of [3H]uridine. Synthesis of polyadenylated RNA in blastocyst‐stage embryos was abolished by α‐amanitin‐treatment at concentrations and exposure times that suppressed total RNA synthesis by less than 15%.DNA‐dependent RNA polymerase activity was measured in lysates of embryos at several stages of preimplantation development. α‐Amanitin suppressed total polymerase activity assayed under ionic conditions favorable to the detection of RNA polymerase II.Electrophoretic analyses revealed that preincubation of blastocysts in 100 μg/ml α‐amanitin reduced labelling of cytoplasmic 28S and 18S RNA by inhibition of both synthesis and maturation of nucleolar 45S rRNA‐precursor. This action of α‐amanitin on nucleolar RNA synthesis cannot be correlated with the minimal suppression of nucleolar RNA polymerase activity and suggests that the synthesis and processing of rRNA may be under control of nucleoplasmic gene products.
Analysis of isolated sea urchin nuclei incubated in egg cytosol
Authors: Kunkle Mel , Magun Bruce E. , Longo Frank J. 
Published: June 2005

AbstractDuring fertilization the condensed sperm chromatin rapidly disperses and forms the male pronucleus. The possibility exists that substances which are concerned with chromatin dispersion may be present in the egg prior to insemination. To test for the presence of factors that may induce chromatin decondensation within the egg cytoplasm, a cell‐free system was devised in which isolated sperm nuclei were incubated in egg cytosol. Isolated sperm nuclei incubated in egg cytosol underwent nuclear enlargement and spherulation, i.e., increased at least three times that of the original volume of the sperm nucleus. This effect was potentiated, i.e., relatively more protein became associated with sperm nuclei, when sperm nuclei were treated with 0.25 N HCl to extract basic proteins prior to incubation in egg cytosol. Incubation in cytosol from Physarum, transformed NRK cells or Novikoff cells had no effect on the morphology of isolated sperm nuclei. Analysis of the proteins which became associated with acid‐extracted sperm nuclei showed that many had the same apparent molecular weight as those associated with male and female pronuclei. Analysis of egg cytosol proteins also indicated that many polypeptides had an affinity for DNA and the same apparent molecular weight as those associated with male and female pronuclei and zygote nuclei.
Aldehyde oxidase distribution in Drosophila melanogaster mature imaginal discs, histoblasts and rings of imaginal cells
Authors: Kuhn David T. , Cunningham Glenn N. 
Published: June 2005

AbstractHistochemical staining characteristics for the enzyme aldehyde oxidase are reported for Drosophila melanogaster imaginal discs, histoblasts, and rings of imaginal cells. Aldehyde oxidase activity was observed in all discs except for the eye disc, was found in all imaginal cell groups except in the imaginal cells of the midgut and was found in the histoblasts. Differential aldehyde oxidase staining patterns were observed for the dorsal prothoracic disc, labial disc, antennal disc, for all leg discs (ventral pro‐, meso‐, and metathoracic discs), for the halere disc (dorsal metathoracic disc), for the wing disc (dorsal mesothoracic disc), and for the genital disc. Patterns observed in the various discs are quite repeatable. Enzyme distribution in the mature wing disc may provide an opportunity to visualize developmental compartments.
Experimental studies on hatching behavior in the chick. IV. Evidence for the role of a noradrenergic mechanism
Authors: Pittman Randall , Oppenheim Ronald , Ramakrishna T. 
Published: June 2005

AbstractIn the present experiments we have attempted to determine whether one or more of the biogenic amines are involved in the prehatching and hatching behavior of the chick. Injection of reserpine first induces a depression in ongoing spontaneous motility on day 16 of incubation. Prior to this, reserpine has no apparent effect on embryonic behavior. Reserpine injections on days 17–19 induce a similar behavioral depression that lasts for at least six hours; by 24 hours post‐injection the behavior of reserpine‐treated embryos is comparable to controls. Injection of reserpine on day 20 (post‐pip) delays hatching by about nine hours. Injection of reserpine into the yolk‐sac of eggs prior to incubation also delays hatching by eight to nine hours. It is unlikely that the well‐known car‐diovascular effects of reserpine are involved in the above behavioral results since spinal embryos also exhibit a behavioral depression following reserpine treatment.Biochemical estimation of norepinephrine (NE) in the brain of reserpinetreated embryos suggests that it is release, not depletion, of the catecholamines that is responsible for the behavioral effects. Additional support for this notion comes from experiments in which 16‐ or 18‐day old embryos were injected with NE, L‐dopa or amphetamine. In each case, a behavioral depression similar to that produced by reserpine resulted.Clonidine, a NE agonist induces a depression in certain aspects of embryonic behavior (Types 1 and 2), but also selectively enhances a coordinated motor pattern (Type 3 motility) involved in prehatching behavior (tucking). Clonidine first evokes this behavior pattern one to two days prior to its spontaneous appearance on day 16. After pipping on day 19 or 20 clonidine no longer activates Type 3 behavior, even if injected during the actual hatching process (climax). Since the alpha‐adrenergic blocking agent phenoxybenzamine blocks the effect of clonidine on Type 3 tucking behavior, whereas the beta‐adrenergic blocker propranolol does not, we suggest that tucking and the attainment of the hatching position are mediated by an alpha‐adrenergic mechanism in the brain and/or spinal cord. Furthermore, since clonidine affects the Type 3 behavior associated with tucking, but not the somewhat similar coordinated behavior involved in hatching and emergence from the shell (climax), we propose that this later behavior pattern be given a new name, Type 4 motility.