bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organic acid (or anion) and organic base (or cation) transport by renal tubules of nonmammalian vertebrates
Authors: Dantzler William H. 
Published: June 2005

AbstractOrganic acids (or anions) and organic bases (or cations) are transported by the renal tubules of nonmammalian vertebrates, but until recently the details of the transport processes have been poorly studied. Work with isolated perfused and nonperfused renal tubules and with membrane vesicles has now begun to supply information on the transepithelial transport processes and the transport steps at the individual cell membranes. The current information is reviewed for organic acids (or anions) as a general group, for urate (which generally appears to be transported by a separate system from that for other organic anions), and for organic bases (or cations) as a general group. Tentative cellular models for the transepithelial transport of each of these general categories of compounds are suggested.
Cytophysiology of growth pulsations in hydroid polyps
Authors: Beloussov L. V. , Labas J. A. , Kazakova N. I. , Zaraisky A. G. 
Published: June 2005

AbstractCell orientation and intercellular changes accompanying growth pulsations (GP) have been studied in the marine hydroids Obelia longissima, O. loveni, and Dynamena pumila with the use of time‐lapse filming, mechanography, optical microscopy, and electron microscopy. The extension phase of the GP was correlated with an increase in cell volume and the rotation of cells to a transverse orientation. Tip cells return to an oblique orientation during the retraction phase via a rapid (about 1 μm/second) distalward sliding of external cell poles. In most samples, a proximodistal wave of transversad cell rotations was observed within a period of 30–90 μm/minutes. In contrast, return to the oblique orientation is almost synchronous. The extension GP phase is correlated with extensive cell vacuolization and the retraction phase with fusion of these vacuoles into elongated channels opening into external space.The extension phase was stabilized in hypotonic medium, isotonic medium with increased NaCl concentration, and by ionic transport inhibitors (which increase cytoplasmic concentration of Na+ and Cl−). GP are arrested in the retraction phase in hypertonic medium, isotonic medium with decreased Na+ and Cl− concentration, and by inhibitors whose decreasing cytoplasmic concentrations of Na+ and Cl− arrest GP in the retraction phase. These data point out the participation of osmotic mechanisms in the regulation of GP.
Reevaluation of the effects of growth hormone and prolactin on anuran tadpole growth and development
Authors: Delidow Beverly C. 
Published: June 2005

AbstractThe effects of ovine prolactin (oPRL) and ovine (o) or porcine (p) growth hormone (GH) on growth of anuran larvae were compared. In grass frog tadpoles (Rana pipiens), injections of oPRL (10 μg/gm/day) increased tail growth and body weight but had no effect on hindlimb growth or development. The same dose of oGH did not significantly affect the tail or body weight but it caused a striking increase in limb length and development. In bullfrog tadpoles (Rana catesbeiana) given an ergot drug (bromocryptine) to induce metamorphic changes, significant tail regression and loss of body weight occurred. Treatment with oPRL reversed these effects but had no effect on hindlimb growth or development. The pGH was much less effective than the oPRL in blocking tail regression and body weight loss but it significantly increased limb growth and development. These results show that GH and PRL can differentially regulate growth and development of structures in larval anurans. The effects of GH on limb growth and development can not be explained simply by a thyrotropic effect.
In vivo cellular reactions and clearance of bacteria from the coelomic fluid of the marine annelid, Arenicola marina L. (polychaeta)
Authors: Fitzgerald S. W. , Ratcliffe N. A. 
Published: June 2005

AbstractThe coelomocyte reactions of the polychaeta Arenicola marina L. in reponse to experimental infection and the fate of the injected bacteria have been investigated utilizing unlabelled and radiolabelled bacteria. In A. marina, 60–75% of the inoculum is cleared from the coelomic fluid within the first 10 min and this increases to over 95% by 3 h postinjection. These changes appear to be correlated with a reduction of freely circulating coelomocytes and the appearance of cellular aggregates. These clumps serve to contain the bacteria and many are eventually incorporated into “brown bodies” which become necrotic and melanised. Coelomocytes enclosing ingested bacteria also migrate into many of the surrounding tissues. Nephridia too are involved in the removal of bacteria from the coelom either by filtration from the coelomic fluid or, to a lesser extent, by the phagocytotic activity of the cells of the nephridial walls.Lack of appreciable amounts of free radiolabel in the coelomic fluid indicates that humoral bacteriolysins do not play a major role in the clearance process.
Sites of zona pellucida shedding by mouse embryo other than muran trophectoderm
Authors: Yamazaki Kimie , Kato Yoshihiro 
Published: June 2005

AbstractThe sites at which a mouse embryo sheds the zona pellucida in preparation for its hatching were investigated in vitro. Of all cases examined, 24% shedding occurred at the mural site, 24% at the inner cell mass site, 17% at the equatorial site, and 35% at other sites. It thus appears reasonable to conclude that there is no particular site destined for shedding and the site at which it does take place in vitro is irrelevant to that at which the uterus later becomes attached. Expressing its frequency in terms of a unit of area indicated shedding to occur markedly at the axis penetrating the inner cell mass and mural trophectoderm. The ratio of hatching frequency along this axis to that at other areas was determined as 7:1.
Nosema kingi: Effects on fecundity, fertility, and longevity of Drosophila melanogaster
Authors: Armstrong Earlene , Bass Linda K. 
Published: June 2005

AbstractThe effects of Nosema kingi on the fecundity, fertility, and longevity of Drosophila melanogaster were investigated. These studies revealed that parasitized D. melanogaster lay significantly fewer eggs and produce fewer offspring than nonparasitized flies. Although males tended to live longer than females, the life span of both sexes of infected D. melanogaster was significantly reduced.
Activation of fat body glycogen phosphorylase in the eastern lubber grasshopper (Romalea microptera) by the endogenous neuropeptides Ro I and Ro II
Authors: Gäde Gerd , Spring Jeffrey H. 
Published: June 2005

AbstractRomalea corpus cardiacum (CC) contains large quantities of two neuropeptides, named Ro I and Ro II, that are capable of eliciting strong hyperlipemic (locusts) and hypertrehalosemic (cockroaches) responses in test species (Spring and Gäde: Journal of Experimental Zoology 241:41–50, 1987). Although clearly members of the locust adipokinetic hormone/crustacean red pigment‐concentrating hormone (AKH/RPCH) family of peptides (Gäde: Zeitschrift für Naturforschung, Section C 41:315–320, 1986), these neuropeptides have no discernible effect on hemolymph lipids or carbohydrates in Romalea itself, and neither do large doses of synthetic locust AKH I (1,000 pmol) nor stick insect hypertrehalosemic factor II (HTF II: 500 pmol). Injections of its own CC are capable of stimulating Romalea fat body glycogen phosphorylase in a dose‐dependent manner, and this effect can be mimicked by Ro I and Ro II. Neither extracts of pars intercerebralis nor subesophageal ganglion have any significant effect on phosphorylase activation. Using synthetic peptides, we determined dose‐response curves for phosphorylase activation. Ro I is the more effective in stimulating phosphorylase, with a maximum activation of 70%, compared to 50% for Ro II. Ro II is more potent, however, producing a significant activation with 0.1 pmol, compared to 0.5 pmol of Ro I. Although these peptides are powerful activators of endogenous fat body glycogen phosphorylase in Romalea, this function does not explain the enormous quantities of neuropeptide (2,800 pmol Ro I; 650 pmol Ro II) found in the CC. Glycogen phosphorylase is also activated by starvation, and this effect is reversed by feeding. It is not clear at present whether the starvation‐induced activation is hormonally controlled.
Thyroid hormones in trout reproduction: Enhancement of gonadotropin‐releasing hormone analogue and partially purified salmon gonadotropin‐induced ovarian maturation in vivo and in vitro
Authors: Sullivan Craig V. , Bernard Melinda G. , Hara Akihiko , Dickhoff Walton W. 
Published: June 2005

AbstractMaturing female rainbow trout were injected two times with gonadotropin‐releasing hormone analogue (GnRHa) or once with triiodothyronine (T3) alone or in combination. GnRHa treatment caused ovulation within 10 days after the second injection. T3 treatment caused a severalfold increase in blood plasma T3 concentrations and increased the ovulatory response to GnRHa. Ninety percent of the fish injected with both T3 and GnRHa ovulated within 3 days after the second GnRHa injection, as opposed to 50% of the fish injected only with GnRHa, or 25% of the controls. In all groups total androgen (TA) and 17α‐20β‐dihydroxy‐4‐pregnen‐3‐one (DHP) levels increased and estradiol (E2) levels decreased between the time of the first injection and the time of spawning. GnRHa decreased TA levels and increased thyroxine and T3 levels, but did not affect either E2 or DHP concentration in the blood plasma of the fish at the time of spawning. To investigate the mechanism of action of T3 on trout maturation, oocytes within intact follicles were cultured in the presence of various concentrations (0.1 to 1,000 ng/ml) of partially purified salmon gonadotropin (SG‐G100) with or without various concentrations (0.5 to 500 ng/ml) of T3. The lower concentrations of T3 (0.5 to 50 ng/ml) potentiated oocyte maturation (germinal vesicle breakdown [GVBD]) in response to SG‐G100. The highest concentration of T3 inhibited GVBD. T3 was effective in increasing GVBD only at the lowest concentration of SG‐G100 (10 ng/ml) that was effective in stimulating GVBD. The percentage of oocytes that had undergone GVBD was positively correlated with the concentration of DHP in the culture medium. These results suggest that thyroid hormones may influence final maturation of trout by potentiating the steroidogenic responses of the ovary to gonadotropin.
Determination of cell death in the developmental process of anuran larval skin
Authors: Kinoshita Tsutomu , Takahama Hideki , Sasaki Fumie , Watanabe Kyozo 
Published: June 2005

AbstractIn metamorphosis of anuran tadpoles, tail skin degenerates concomitantly with tail resorption, whereas back skin develops from larval to adult type. Such a difference in developmental fate of the tadpole skin is called regional specificity. To examine when cell death of tail skin is determined during development, prospective skins of embryos or larval skins were reciprocally transplanted between back and tail of the same animal at various developmental stages. Operated animals were reared until the end of metamorphosis, when the phenotypic expression of the grafts was examined. Regional specificity could not be observed in most of the tadpoles that were operated at the neurula stage. However, specificity‐positive cases were found among the animals operated during a period from late neurula to tail‐bud stage. This period corresponded to the developmental stage prior to the appearance of basal lamina and collagen fibers of the skin. When skins were grafted at larval stages after hatching, almost all of the operated tadpoles showed the regional specificity in graft areas of both tail and back. In order to determine the cell type that is responsible for the developmental fate of skin, cell blocks dissected from ectoderm or dermatome of mesoderm were reciprocally transplanted between presumptive regions of back and tail at the tail‐bud stage. The developmental fate of the skin in the operated areas was significantly altered by mesodermal but not by ectodermal transplantation. These results suggest that the developmental fate of anuran larval skin, especially cell death of tail skin, is determined by factors contained within the dermatome at embryonic stage preceding tail‐bud formation.
Changing localizations of site‐specific sperm surface antigens during sea urchin fertilization
Authors: Nishioka David , Gorman Elizabeth A. , Ward Rita D. 
Published: June 2005

AbstractIndirect immunofluorescence studies show that monoclonal antibody (mAb) J18/2 binds site‐specifically to surface antigens localized over the acrosome and tail regions of mature Strongylocentrotus purpuratus spermatozoa. Within 5 min after induction of the acrosome reaction by exposure to egg jelly or ionophore A23187, these surface antigens become detectable over the lateral region of the head so that the entire surface of the spermatozoon is labeled. Polyspermically fertilized S. purpuratus eggs fixed at varying times after insemination and exposed to mAb J18/2 reveal that these surface antigens are quickly incorporated into the egg plasma membrane and begin to disperse as early as 1.5 min after insemination. At subsequent times, they undergo further dispersal so that by 45 min they are distributed over the entire surface of the egg. These results suggest that the sperm surface components recognized by mAb J18/2 gain the ability to disperse laterally during the acrosome reaction and proceed to do so in the egg plasma membrane after fertilization.
Energy transport and cell polarity: Relationship of phosphagen kinase activity to sperm function
Authors: Tombes Robert M. , Shapiro Bennett M. 
Published: June 2005

AbstractThe energy required for motility of sea urchin sperm is transported from the mitochondrion to the flagellum by a phosphocreatine shuttle involving diffusion of phosphocreatine (PCr) between isozymes of creatine kinase (CrK) localized at the two sites (Tombes and Shapiro, Cell, 41:325, '85; Tombes et al., Biophys. J., 52:75, '87). The present studies demonstrate that high sperm CrK (various echinoderms; sea squirt, bristle worm, salmon) or arginine kinase (mollusc, barnacle, moth) activity is seen in several species with sperm of a primitive morphology (mitochondrion at the base of the head, relatively long flagellum). In contrast, CrK activity is 10–100‐fold less abundant in sperm of other species (frog, mouse, rooster, rabbit, bull, and human) that either possess a modified morphology (mitochondria that extend along the flagellum) and/or utilize glycolytic metabolism. We interpret these findings as support for the use of phosphagen kinase‐dependent energy transport in cells in which the production of adenosine triphosphate (ATP) by the mitochondrion is distant from its utilization, leading to a form of metabolic polarization. Two other cell types, frog photoreceptors and rabbit oviduct cells, whose morphology and function also suggest that they exhibit metabolic polarization, contain relatively high CrK activity. The presence of high phosphagen kinase activity in metabolically polarized gametes and somatic cells further substantiates the role of such enzymes in facilitating energy transport.
Free amino acids and cell volume regulation in the euryhaline ciliate Paramecium calkinsi
Authors: Cronkite D. L. , Pierce S. K. 
Published: June 2005

AbstractParamecium calkinsi was isolated from a tidal marsh in which the salinity fluctuated widely on a daily basis. In the laboratory, this ciliate survived for days in sea water ranging in osmotic strength from 10 to 2,000 mOsm and divided in nutritive media of 1,000 mOsm or less. When transferred from 750 to 250 mOsm, cells swelled but regained 78% of the original volume within 60 min and the original volume within 1 day. Cells acclimated to 250 mOsm and transferred to 750 mOsm shrank, regained 40% of the original volume in 60 min, and regained little more volume during the next 24 hr. Free amino acids (FAA), principally proline and alanine, are osmo‐lytes in P. calkinsi. In cells that have been acclimated for more than 1 month Pro is undetectable at 10 mOsm but at 250 mOsm is present in substantial amounts and is still higher at 750 mOsm. Ala is found in cells at all three salinities and increases dramatically with increasing salinity. A complex pattern of amino acid changes occurs during the 4 hr following a transfer from 250 to 750 mOsm, resulting in a marked increase in Ala but no change in Pro. Thus the metabolic changes that lead to the increased FAA levels of acclimated cells are apparently long‐term and complex. After transfer of cells from 750 to 250 mOsm there is a rapid and selective loss of Pro and Ala from the cells to the medium.
Cryoprotective capacity of end products of anaerobic metabolism
Authors: Loomis S. H. , Carpenter J. F. , Anchordoguy T. J. , Crowe John H. , Branchini B. R. 
Published: June 2005

AbstractThe cryoprotective capacity of end products of anaerobic metabolism was measured using resonance energy transfer studies and stabilization of freeze‐labile enzymes during freeze‐thaw. The most effective end products of anaerobic metabolism at preventing fusion of small unilamellar vesicles during freezing were alanopine, alanine, proprionate, acetate, and lactate. Octopine and strombine were less effective, and ethanol resulted in fusion. Lactate dehydrogenase or phosphofructokinase were protected during freeze‐thaw by all of the end products tested. The possible mechanisms of protection of lipid bilayers and enzymes as well as the implications of these results for the survival of intertidal bivalve molluscs during winter are discussed.
Cellular contribution to symmetrical forelimbs from triploid‐marked “polarizing region” in the embryo of the axolotl, Ambystoma mexicanum
Authors: Tank Patrick W. 
Published: June 2005

AbstractGrafts of posterior tissue placed anterior to the limb bud in the salamander embryo exert a polarizing influence. To explain this result, the idea that the anteroposterior axis of the developing forelimb is polarized by a diffusible morphogen has been proposed [J. Slack, (1977) J. Embryol. Exp. Morphol., 39:169–182]. An alternative hypothesis, and the working hypothesis of the present study, is that the polarization of the developing salamander forelimb is accomplished by short‐range cellular interactions resulting in intercalation rather than by the more global influence of a diffusible morphogen. One prediction of this intercalation hypothesis is that cells will be contributed to the limb from the “polarizing tissue”. To test this idea, grafts of triploid marked polarizing tissue were implanted anterior to the limb bud in 82 diploid axolotl embryos at stages 32–34 of development. A total of 27 (33%) of the limbs that resulted were symmetrical and ranged in complexity from one to seven digits. Histological analysis of a subgroup of the original symmetrical limbs revealed that mesodermally derived tissues in the anterior side of these limbs (the side which formed as a duplication in response to the influence of the graft) contained high percentages of trinucleolate cells (muscle, 12.1%; connective tissue, 12.5%; and cartilage, 13.4%) when compared to similar tissues in the posterior side of the same symmetrical limbs (muscle, 1.8%; connective tissue, 0.7%; and cartilage, 0.6%). When symmetrical limbs were amputated, 73% regenerated symmetrical limbs. When these regenerated limbs were again amputated, 63% formed symmetrical secondary regenerates. Histological analysis of the first generation of regenerated limbs revealed that the pattern of distribution of trinucleolate cells in each regenerate was similar to the pattern seen in the original symmetrical limb. These results indicate that there is considerable cellular contribution to the anterior side of the symmetrical forelimb from the mesoderm of grafted “polarizing tissue”. This result supports the idea that short‐range cellular interactions are sufficient for formation of symmetrical forelimbs in salamander embryos.
Spontaneous maturation of follicular oocytes in Rana dybowskii in vitro: Seasonal influences, progesterone production, and involvement of cAMP
Authors: Kwon Hyuk B. , Lim Young K. , Choi Mee J. , Ahn Ryun S. 
Published: June 2005

AbstractSeasonal and hormonal influences regulating oocyte maturation (germinal vesicle breakdown, GVBD) in ovarian follicles of Rana dybowskii were investigated. During the early winter (Dec.–Jan.) GVBD occurred at a low incidence following in vitro culture of intact follicles. Addition of progesterone or frog pituitary homogenate (FPH) to such follicles induced oocyte maturation, whereas IBMX or forskolin inhibited hormone‐induced oocyte maturation. The time course of spontaneous in vitro maturation varied markedly with the seasons and between animals. Follicles isolated from the ovaries in early February required 21–24 hours of culture to mature spontaneously, and addition of FPH or progesterone to the culture medium markedly accelerated the time course of GVBD. In contrast, follicles isolated in late February matured very rapidly (< 6 hours), and FPH or progesterone were ineffective in accelerating the time course of GVBD. IBMX and forskolin separately or in combination stimulated follicular progesterone production, which resembled that seen following FPH stimulation. FPH addition to such follicles shifted the steroid peak to the left (accelerated) and increased the absolute amount of hormone detected in latematuring follicles (50% GVBD, about 18 hours) but not in rapidly maturing follicles (50% GVBD, 3 hours). In contrast to other amphibians, a high incidence of spontaneous oocyte maturation occurred during in vitro culture. Essentially all animals exhibited spontaneous maturation during the normal breeding season, even those animals collected in the early winter and kept in artificial hibernation at 4°C for extended periods.
Reception of photoperiodic information by fetal siberian hamsters: Role of the mother's pineal gland
Authors: Elliott Jeffrey A. , Goldman Bruce D. 
Published: June 2005

AbstractThe rate of reproductive development in juvenile male Siberian hamstersis strongly influenced by daylength (photoperiod). Recent studies indicate that reception of photoperiodic cues begins during fetal life. The present experiments yielded a further demonstration that developing male Siberian hamsters receive information about the photoperiod to which their mother is exposed during pregnancy. The possibility that photoperiodic information is transmitted from mother to young after birth was investigated by cross‐fostering young gestated on 12L and 16L to mothers from the other photoperiod. Litters were cross‐fostered on the day of birth and then were transferred, along with their foster mothers, to 14L. We found no influence of the mother after birth, indicating that transmission of photoperiodic information from mother to young must occur during gestation. To determine if the pineal gland of the mother is required for this response, adult females were pinealectomized or sham‐operated and paired with intact males in 12L, 14L, or 16L. After parturition parents and offspring were exposed to 14L. The influence of prenatal photoperiod on postnatal testicular development in 14L was blocked by pinealectomy of the mother. Postnatal testicular development was retarded in offspring that experienced a photoperiod transfer from either 15L to 14L or 8L to 12L at birth. In contrast, the inhibitory effect of a transfer from 16L to 14L at birth was abolished when juvenile males were exposed to a single long photoperiod (16.3 h light) at age 17–21 days and then were returned to 14L.