摘要:

Ecdysteroid content in ovaries ofBombyxlarvae was determined every 12 h through the feeding period in the fifth instar. The content was less than 5 pg/ovary pair on day 0 to day 2, but more than 20 pg/ovary pair on day 3. It then returned to the original level 12 h later and remained at a low level until day 6. This increase in the ecdysteroid content found on day 3 was entirely suppressed by an application of juvenile hormone analogue. Cultured ovaries did not release ecdysteroids into the culture medium, and neither crude brain extract nor PTTH elevated ecdysteroid content in ovaries isolated from day 2 larvae. Ecdysteroids in the ovaries of day 3 larvae were tentatively identified as ecdysone, 3-dehydroecdysone, 20-hydroxyecdysone and other ecdysteroids by the combination of high performance liquid chromatography and radioimmunoassay. Growth of the ovaries in the fifth instar commenced on day 4. Ecdysteroids found on day 3, when the haemolymph ecdysteroid titre remains at a low level, may trigger further development of ovaries in the fifth instar.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672213

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Ecdysteroids in non-reproductive, reproductive, and post-reproductive specimens of two nemerteans,Paranemertes peregrinaandPantinonemertes californiensis, were studied using radioimmunoassay (RIA). Ecdysteroid concentrations increased during the reproductive season in females of both species. These data suggest the possibility that ecdysteroids are involved in reproduction. Study of ecdysteroid profiles using reverse phase high-performance liquid chromatography (RP-HPLC) followed by RIA showed that the types and relative amounts of different ecdysteroid metabolites were similar between mature male and femalePan. californiensis.In addition, [3H]-ecdysone was injected into mature male and femalePan. californiensis.The resulting RP-HPLC profiles indicated that both sexes metabolized [3H]-ecdysone to similar products. Both sexes produced polar and apolar ecdysteroid conjugates as the major metabolites of [3H]-ecdysone, with only traces of [3H]-20-hydroxyecdysone.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672214

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Insect defensin A is an inducible antibacterial peptide of the fleshflyPhormia terra-novaeand has been recently characterized as a 40 residue basic peptide with six cysteines engaged in three intramolecular disulfide bridges. We report the expression of this peptide inSaccharomyces cerevisiaeas a fusion protein carrying at its N-terminus leader sequences which are derived from the precursor of the yeast pheromone mating factor α (MFαl). These sequences allow the biologically active peptide to be secreted at high levels in a correctly processed form. Thus heterologous production of defensin A circumvents laborious purification of minute amounts of the peptide from its natural source. The insect defensin pro peptide can substitute for theMFαlpro peptide, indicating that yeast can process an insect pro sequence.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672215

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The burrowing hermaphroditic anemone,Ceriantheopsis americanus, lives in a mucus-lined tube in sandy bottomed grass-flat areas of Tampa Bay. In this hermaphroditic species ova and sperm cysts are interspersed throughout the coupled mesenteries. The gonads occur in every other coupled mesentery beginning with the third couple. A mesentery consists of two layers of flagellated gastrodermis separated by a layer of mesoglea.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672216

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The possible role of arachidonic acid and its metabolites in sea urchin egg activation was examined using inhibitors of arachidonic acid release and metabolism. Quinacrine, a phospholipase A2inhibitor, blocked the cortical granule reaction and inhibited pronuclear migration and cleavage in fertilized eggs. Indomethacin and eicosatetrayenoic acid, blockers of arachidonic acid metabolism, had no affect on these processes. These findings suggest that phospholipase A2activation may be important in mediating events involving cortical granule exocytosis, pronuclear morphogenesis and mitosis in fertilized sea urchin eggs, perhaps by releasing free arachidonic acid. Subsequent metabolism of arachidonic acid does not seem to be involved in processes of egg activation as inhibitors of arachidonic acid metabolism had no demonstrable effects on fertilization events following egg activation and the cortical granule reaction.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672217

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Serotonin receptors were identified inSpisulasperm membranes by radioligand binding assay. Sperm membranes were prepared by nitrogen cavitation and by density gradient ultracentrifugation. Specific binding of [3H]5-HT to the receptors of isolated sperm membranes was determined. The dissociation constant was 2.7 nM and the maximum binding capacity was 11.25 pmoles/mg of protein. The order of decreasing potency of 5-HT agonists in blocking [3H]5-HT binding to the sperm membrane was as follows: 2-methyl 5-HT> 8-OH-DPAT> 5-HT> 5-CT> α-methyl-5-HT; and that of 5-HT antagonists was: ICS-205-930> BMY-7379> mianserin> methysergide. These findings suggest that the 5-HT receptors inSpisulasperm membranes contain sites that interact with 5-HT3and 5-HT1analogs.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672218

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In newly hatched larvae ofBacillus rossius(Insecta Phasmatodea) viewed with light and electron microscopes, ovarioles appear as bag-like structures; during the first instar they initially assume a bell-shaped appearance. Afterwards, they begin to elongate and their vitellarium essentially consists of a row of oocytes with a clear growth gradient. This typical ovariole morphology becomes more evident in the subsequent instars up to the fourth.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672219

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The marine acoel flatwormChildia groenlandica(phylum Platyhelminthes, order Acoela) has been examined by electron microscopy in order to elucidate the interactions that occur between developing oocytes and their associated somatic cells during oogenesis. In mature worms the female germ cells form an elongated mass on either side of the body. Previtellogenic oocytes at the anterior end of each germinal mass measure 10–20 μm in diameter and lack a complete sheath of enveloping somatic cells. More posteriorly, oocytes begin to produce yolk granules and become fully covered by somatic cells.

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672220

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672221

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0792-4259    

DOI:10.1080/07924259.1992.9672212

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor