摘要:

AbstractNeuronal release of norepinephrine (NE) in the sea pansyRenilla koellikeriwas investigated by searching for evidence 1) of neuronal localization of endogenous NE and 2) of synaptic‐like release of exogenously supplied NE in sea pansy tissues. Measurements of endogenous NE by high‐performance liquid chromatography with electrochemical detection corresponded with the visualization of specific NE immunoreactivity in six individual colonies thus sampled. Peroxidase‐antiperoxidase immunohistochemistry with antisera against NE‐aldehyde‐protein conjugates revealed that cellular NE immunostaining was predominantly associated with neurons and amoebocytes constituting the mesogleal nerve net. Transient increases of tritium outflow above background levels were evoked by field electrical stimulation of colonial (rachis) tissues pre‐loaded with 1 μM [3H]NE, under conditions that elicited nerve net‐mediated bioluminescence. This evoked release was largely reduced or abolished in a reversible manner by substituting high‐magnesium or calcium‐free seawater to normal seawater perfusate. Evoked release was significantly enhanced by exogenous norepinephrine (50 μM) and reduced in half or less by the α‐adrenergic blockers phentolamine and yohimbine (10 μM), thus providing support for the existence of an autoregulatory mechanism associated with release. These results suggest that neuronal, synaptic‐like release of NE occurs in the nerve‐net of the sea pansy, a representative of the phylum (Cnidaria) in which the first nervous systems of multicellular organisms are believed to have origina

ISSN:0022-104X    

DOI:10.1002/jez.1402720102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe abdomen of the lobsterHomarus americanushas four pairs of segmental appendages, the swimmerets, whose rhythmic beating functions in swimming, righting responses, creating water currents, and aerating eggs. There are 24 separate muscles in each swimmeret and 21 of these are fast, based on their relatively short (4 μm) sarcomeres and six thin filaments orbiting a single thick filament. Three of the 24 muscles are slow with relatively long (7–12 μm) sarcomeres and 8–11 thin filaments surrounding a thick filament. Of the eight functional groups amongst which the 24 muscles are distributed, six groups have only fast muscles, one group has a mixture of fast and slow muscles, and one group only slow muscles. Thus the number and distribution of fast muscles in the swimmeret makes it a predominantly fast system. Motor innervation of two fast muscles in the power‐stroke group reveals numerous excitatory nerve terminals (recognized by circular synaptic vesicles) with well‐defined synaptic contacts and presynaptic dense bars or active zones. Synaptic contacts appear in the P‐face of the fractured nerve membrane as circular plateaus with sparsely distributed particles and one or two small aggregations of large intramembranous particles (putative calcium channels) representing active zones. In the complementary E‐face, synapses assume spherical outlines and active zones appear as shallow depressions. Attachment sites of synaptic vesicles appear as large pits in P‐face or protuberances in E‐face leaflets along the edge of the active zones. The surface features of excitatory synapses of fast swimmeret muscles are similar to those on other crustacean fast and slow muscles. The packing density of large intramembranous particles in the active zones also resembles that in other crustacean muscles thereby suggesting an optimal packing density for these ion channels. © 19

ISSN:0022-104X    

DOI:10.1002/jez.1402720103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractCytochrome P450c17 is a key steroidogenic enzyme for the production of sex steroids in gonadal tissue and for cortisol production in adrenal tissue. This protein possesses two enzymatic activities. The 17α‐hydroxylase activity results in the introduction of a hydroxyl group at the 17α‐position. The resultant 17α‐hydroxylated, C21 pregnene is converted to a C19 andro‐gen by the C17,20‐lyase activity. A cDNA library was constructed from poly(A)‐enriched mRNA isolated from spiny dogfish shark (Squalus acanthias) testis and ligated intoEcoRI‐cut lambda arms. The amplified library was screened using a bovine P450c17 cDNA probe and five positive clones were isolated. The described cDNA encompasses 23 bp of the 5′‐untranslated region, a 1,527 bp open reading frame, and 414 bp of the 3′‐untranslated region. A putative polyadenylation signal (AATAAA) is 18 bp from the poly(A) tail. Northern blot analysis showed a single transcript of 1.9 kb, thus indicating the isolated clone is a full‐length cDNA. The deduced amino acid sequence of the shark form of P450c17 is 59% and 57% identical to the rainbow trout and chicken forms, respectively. The shark form is 43% to 46% identical to mammalian forms (rat, human, mouse, bovine, and porcine). There are large regions of extremely high identity shared among all the forms. The deduced shark 17α‐hydroxylase protein is 509 residues in length with a predicted weight of 57.2 kDa. Non‐steroidogenic COS cells, transfected with the shark P450c17 cDNA, was capable of 17α‐hydroxylase and C17,20‐lyase activities using both pregnenolone and progesterone as initia

ISSN:0022-104X    

DOI:10.1002/jez.1402720104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractVitellogenin (Vg) and vitellogenin‐derived yolk proteins of growing oocytes and ovulated eggs were purified and characterized to evaluate structural changes of yolk proteins during oocyte growth and maturation in barfin flounder,Verasper moseri, a marine teleost which lays pelagic eggs. Native circulating vitellogenin, estimated to be a 520 kDa protein using Superose 6 column chromatography, cleaved into the 410 kDa major yolk protein, lipovitellin (Lv), in vitellogenic oocytes. An additional minor yolk protein at 19 kDa in native form, which was immunoreactive to an antiserum raised against Vg, and a highly phosphorylated 38 kDa band of phosvitin (Pv) in SDS‐PAGE with reduction were also identified in vitellogenic oocytes. Analysis of the amino acid composition of the 19 kDa yolk protein showed it to be similar to the β′‐component of egg yolk from salmonid fish. The 410 kDa Lv in vitellogenic oocytes was proteolytically cleaved into an 170 kDa major yolk protein during final oocyte maturation. The close similarity of amino acid composition between the two proteins combined with the results of lipid analysis suggested that the 410 kDa Lv cleaved into two homologous 170 kDa monomeric Lv. Both 19 kDa yolk protein (β′‐component) and Pv became undetectable after oocyte maturation. We propose that the three classes of yolk proteins (Lv, Pv, and β′‐component) are products of Vg cleavage, and that all of them undergo proteolysis again during oocyte maturation. © 1

ISSN:0022-104X    

DOI:10.1002/jez.1402720105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe length of time required to reject scale allografts was examined in groups of male gulf killifish (Fundulus grandis) treated daily with either 4‐h thermoperiods (daily intervals of 30°C during a 20°C continuum), single meal feedings, or net‐chasing disturbances at one of six different times after the onset of daily photoperiods (LD 12:12 or LD 14:10). Scale allograft survival varied by 30–60% in each timed stimulus experiment as a function of the time of day when the stimulus was provided. The phase relationship between two circadian neuroendocrine oscillations, previously proposed to regulate physiologic and behavioral conditions in gulf killifish, may have important influences on the immune system as well. The phase of one oscillation is thought to be set by the daily photoperiod, and the other is preferentially set by the nonphotic daily stimulus. © 1995 Wiley

ISSN:0022-104X    

DOI:10.1002/jez.1402720106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe ability of secretions from the bovine oviduct to maintain the viability and motility of bovine spermatozoa was investigated by incubating frozen‐thawed spermatozoa with oviductal flushings, uterine flushings, or the medium from cultures of oviductal epithelial cells and endothelial cells. The flushings obtained from both oviducts and uteri were effective for the maintenance of the viability and motility of spermatozoa, irrespective of the stage of the estrous cycle at which they had been collected. The flushings obtained from the ampullar region of oviducts at the follicular phase of the estrous cycle were most effective for the maintenance of viability and motile activity, for example, the forward motion of spermatozoa. Sperm viability and motility were also maintained by the medium from 6‐hour culture of epithelial cells obtained from oviducts at the follicular phase of the estrous cycle. In contrast, the medium derived from bovine fetal artery endothelial cells had no significant effect on sperm viability and motility. These results suggest that the fluids of the female reproductive tract, in particular, the oviductal fluids at the follicular stage, provide a suitable environment for the maintenance of the viability and motility of bovine spermatozoa. It is also suggested that secretory product(s) of oviductal epithelial cells may play an important role in sustaining both the viability and motility of spermatozoa. © 1995 Wiley‐Lis

ISSN:0022-104X    

DOI:10.1002/jez.1402720107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractTo clarify the target cells of GnRH in the ovary, in vivo expression of ovarian GnRH receptor mRNA was examined histologically by in situ hybridization in immature rats treated with PMSG only or in combination with hCG. Strong hybridization signals were observed in the granulosa cells of atretic follicles. However, no significant signals were found in the granulosa cells of healthy small, preantral, or early antral follicles. Healthy Graafian and preovulatory follicles also showed intense signals in their mural granulosa cells, but no signals were detected in the cumulus oophorus cells. Corpora lutea showed only weak signals, but luteinizing follicles probably after atresia exhibited signals of moderate intensity in their luteinized and remaining granulosa cells. No signals were detected in the theca cells and oocytes in all the follicles. Interstitial cells sometimes exhibited hybridization signals of moderate intensity, when the cells were eosinophilic. Pretreatment with different combinations of gonadotropins yielded different ovarian histology, but this had no influence on the localization of hybridization signals. These results, showing that the authentic GnRH receptor mRNA was expressed in a certain cell population in the rat ovary, suggest that the receptor is involved in the control of various ovarian functions including follicular development, atresia, ovulation, and luteinization after ovulation and follicular atresia. © 1995 Wiley‐Liss, I

ISSN:0022-104X    

DOI:10.1002/jez.1402720108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractMammalian P‐glycoprotein is a highly conserved 170‐kD integral plasma membrane protein functioning as an energy‐dependent efflux pump of exogenous and endogenous lipophilic aromatic compounds entering the cell by diffusion. In this study, the tissue specificities of one polyclonal (pAb) and three monoclonal (mAbs) antibodies to mammalian P‐glycoprotein were identified in paraffin‐embedded, parasagittal whole‐body sections of the guppyPoecilia reticulata. Polyclonal antibody mdr(Ab‐1) and mAbs C219, C494, and JSB‐1 demonstrated differential staining patterns in the following tissues: bile canaliculi in the liver, exocrine pancreas, lumenal surface of the intestinal epithelium, renal tubules, interrenal tissue, branchial blood vessels, gas gland, pseudobranch, and the gill transverse septa. Positive P‐glycoprotein expression inP. reticulatacorrelates well with published results for homologous mammalian tissues of secretory and excretory function. These data indicate that one or more highly conserved members of the P‐glycoprotein transporter family exist in a teleost species and can be detected using commercially available mammalian antibodies. © 1995 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the Un

ISSN:0022-104X    

DOI:10.1002/jez.1402720109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractLipid Transfer Protein I is recognized as a key component involved in high density lipoprotein metabolism. We have been studying lipid transfer in relation to sperm capacitation, a complex series of cell surface events required for the acrosome reaction and fertilization. We have previously shown that Lipid Transfer Protein I is present and active in the female reproductive tract. In the present study, we show that purified Lipid Transfer Protein I directly stimulates human sperm capacitation, but not the acrosome reaction, in the absence of other biological effectors. These results provide strong evidence for a novel role for Lipid Transfer Protein I and reveal, for the first time, a potent activator of capacitation, prior to the acrosome reaction. © 1995 Wiley‐Liss, I

ISSN:0022-104X    

DOI:10.1002/jez.1402720110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0022-104X    

DOI:10.1002/jez.1402720101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY