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341.
Piero Andreuccetti Francesco Angelini Carlo Taddei 《Molecular reproduction and development》1984,10(1):67-76
In hibernating females of Pipistrellus kuhli, as well as in other bats previously described, the spermatozoa inseminated in autumn are stored in the uterus, both free and attached by their heads to the uterine epithelium, throughout winter. With the electron microscope the apical region of the attached sperm heads appears to be contained in plicae of the endometrial cells. Furthermore, a great number of microvilli protruding from the uterine epithelium participate in the interaction with spermatozoa. In the region of contact between the two cell types, their plasma membranes run parallel with a constant 12-nm gap. The sensitivity of these interactions to EDTA and hyaluronidase suggests an involvement of Ca++ and proteoglycans in these bindings, while their insensitivity to trypsin tends to exclude a role of proteins. In addition, evidence of exocytosis of dense granules just at the bottom of the plicae containing the spermatozoon suggests a transfer of material from the uterine epithelium to the intercellular space, thus supporting a physiological role of these interactions. 相似文献
342.
Summary Flux performance of a poly vinylidene di-fluoride (PVDF) microfiltration membrane duringSaccharomyces cerevisiae harvesting has been studied. The initial challenge to the membrane has been found to influence subsequent flux. The permeability of the membrane is closely dependent on the pH and membrane conditioning prior to microfiltration improves the flux by more than 70%. 相似文献
343.
344.
Maria G. Maurizii Valeria Cavaliere Chiara Gamberi Paul Lasko Giuseppe Gargiulo Carlo Taddei 《Development genes and evolution》2009,219(7):361-367
The vasa gene, first identified in Drosophila, is a key determinant for germline formation in eukaryotes. Homologs of vasa have been identified and linked to germline development, in many invertebrates and vertebrates. Here, we analyze the distribution
of Vasa in early germ cells (oogonia and oocytes) and previtellogenic ovarian follicles of the lizard Podarcis sicula. During most of its previtellogenic growth, the oocyte in this lizard species is structurally and functionally integrated
through intercellular bridges with special follicle cells called pyriform cells. The pyriform cells function similarly to
Drosophila nurse cells, but are somatic in origin. In the oogenesis of P. sicula, Vasa is initially highly detected in the oogonia, but its levels decrease in early stage oocytes before the onset of pyriform
cell differentiation. In the later stages of oogenesis, the high level of Vasa is related with the nurse function of the pyriform
follicle cells. These observations suggest that cells of somatic origin are engaged in the synthesis of Vasa in the oogenesis
of this lizard. 相似文献
345.
A biological screening of activity against Gram-positive and Gram-negative bacteria, yeasts, and fungi of crude extracts from Wedelia trilobata is reported. The n-hexane extract showed antibacterial activity against Bacillus subtilis, Mycobacterium smegmatis, Staphylococcus aureus, and Staphylococcus epidermidis (Gram-positive bacteria); along with Proteus vulgaris, Pseudomonas aeruginosa, Salmonella group C, Salmonella paratyphi, and Shigella sonnei (Gram-negative bacteria). The ethyl acetate extract was active only against Salmonella group C; and the aqueous extract was inactive against the tested bacteria. None of the tested extracts showed biological activity against the yeasts (Candida albicans, Candida tropicalis, Rhodotorula rubra) or the fungi (Aspergillus flavus, Aspergillus niger, Mucor sp., Trichophyton rubrum). 相似文献
346.
S Balzan L Di Luca L Taddei P Salvador U Montali 《Cellular and molecular biology, including cyto-enzymology》2001,47(2):281-284
3H-ouabain is useful to evaluate the tissue localization of Na,K-ATPase. In this work we determined the distribution of 3H-ouabain in rabbit tissue by digital radioautography. Using this method, we were able to obtain a comparison of various organs in a relatively short time (6.5 days), while with traditional radioautography, only the kidney was detectable after seven months of film exposure. The kidney has the highest intensity (concentration of 3H-ouabain), followed by the heart, liver, muscle, lung, spleen and finally brain, which was almost undetectable. In kidney the activity was higher in the cortex, while the other tissues displayed a more uniform intensity, suggesting that Na,K-ATPase was evenly distributed. 相似文献
347.
Ribosome arrangement during oogenesis of Lacerta sicula Raf 总被引:7,自引:0,他引:7
C Taddei 《Experimental cell research》1972,70(2):285-292
Ribosomal bodies (RB), constituted of crystalline sheets of ribosomes interposed between flat parallel cisternae, are present in the oocyte and follicular cells of Lacerta sicula during the winter rest. During spring, the RB undergo progressive transformation into rough endoplasmic reticulum and free ribosomes, so that these formations are completely lacking during summer. The mechanism underlying the formation of RB and the possible significance that they may have for protein synthesis during oogenesis are discussed. 相似文献
348.