1,721,077 research outputs found
Regulation of oocyte and granulosa cell functions throughout mammalian oogenesis. In: “Sex Origin and Evolution”, R. Dallai, Ed., Selected Symposia and Monographs UZI 6 , 157-165 (1992)
No full text
Isolamento e caratterizzazione dei batteri del bulbo esofageo della mosca mediterranea della frutta Ceratitis capitata
No full textMicrotubule and microfilament distribution during the secretory activity of an insect gland
No full textThe distribution of microfilaments and microtubules was studied in the secretory cells of the accessory glands of the medfly (Ceratitis capitata) female reproductive system. Actin, demonstrated by rhodamine-phalloidin and heavy meromyosin decoration, is present around the extracellular cavity at the level of microvilli and the subapical cytoplasm of the cell. The size of such a cavity varies in relation to the secretory cycle of the cells and also the disctribution of microfilaments. In the early stage of activity microtubules detected using an antibody against alpha-tubulin are distributed at the periphery of the cell and around the extracellular cavity. During secretion they occupy the whole of the cytoplasm and disappear at the end of the secretory cycle. The mechanism of the discharge of the secretion from the extracellular cavity is discussed
The giant sperm axoneme of the gall-midge fly Asphondylia ruebsaameni Kertesz: fine structure and development
No full textThe accessory glands of the female reproductive system of Ceratitis capitata Wied. (Diptera): an updated review
No full textIn general, females of insects have two ectodermic organs connected with the genital chamber. One is the spermatheca, typically opening at the anterior of such a chamber and serving as storage for spermatozoa to be used for fertilizing eggs. The other organs are the accessory glands opening more posteriorly and serving for several functions in the different insect orders (DAVEY, 1985; GILLOT, 1996). In the medfly the accessory glands, which have been ultrastructurally studied in recent years (DALLAI et al., 1985; 1988), flow their secretions on the anterior dorsal region of the bursa copulatrix at the same site of the spermathecal duct openings. We summarize the results obtained on the fine structure of the accessory glands and on the biochemical and molecular characterization of the secretions produced by these organs. Particularly, ceratotoxins are antibacterial peptides identified in the Ceratitis accessory gland secretions (MARCHINI et al., 1993; 1995; ROSETTO et al., 1996; ROSETTO et al., 1997). As the maximum expression of such peptides overlaps the female sexual maturity, it was hypotesized that their presence in the female genital ducts might ensure the realization of the proper environmental conditions for fertilization avoiding bacterial infections which could interfere with the sperm-egg interaction. Moreover, the finding of this antimicrobial material on the chorion of laid eggs raises the possibility that these substances play some specific role in the oviposition site, possibly protecting the eggs and the young larvae from environmental injuries (MARCHINI et al., 1997)
Distribuzione di microtubuli e microfilamenti durante il ciclo di secrezione di una ghiandola esocrina di insetto
No full textLe ghiandole accessorie dell’apparato riproduttore maschile della mosca delle olive Bactrocera oleae (Diptera, Tephritidae)
No full textß-N-acetylhexosaminidases in the secretion of the female reproductive accessory glands of Ceratitis capitata (Diptera)
No full textThe analysis by isoelectric focusing of the secretion fluid (AGF) of the female accessory glands of Ceratitis capitata has shown the presence of seven major protein fractions and two β-N-acetylhexosaminidase isoenzymes, HEX 1 and HEX 2, focalizing at pH 4.75 and 5.25, respectively. The two isoenzymes have the same molecular weight (69 kDa) but a different hydrolytic activity against and galactopyranoside, and a pH optimum of 4 at 37°C. AGF β-N-acetylhexosaminidase activity is most stable at pH values between 5 and 8. At neutral pH a rapid loss of activity is observed at temperatures higher than 50°C. Preliminary assays, carried out using chitin as substrate, indicate the presence in the secretion of an endochitinase activity not bound to the β-N-acetylhexosaminidase isoenzymes. The enzymatic modifications of specific lectin binding sites on the surface of gametic cells is most probably one of the necessary steps preceding fertilization
Biologia
No full texttutti gli aspetti della biologia cellulare, genetica, evoluzione, diversità delle forme viventi, biologia animale, biologia vegetale, ecologia sono trattati in modo accurato e aggiornat
- …
