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Egg Envelope (egg + envelope)
Selected AbstractsMolecular cloning and sequence analysis of an ascidian egg ,-N-acetylhexosaminidase with a potential role in fertilizationDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 3 2003Ryo Koyanagi ,-N-Acetylhexosaminidase, which is found almost ubiquitously in sperm of invertebrates and vertebrates, supposedly mediates a carbohydrate-based transient sperm,egg coat binding. In ascidians and mammals, ,-hexosaminidase released at fertilization from eggs has been proposed to modify sperm receptor glycoproteins of the egg envelope, thus setting up a block to polyspermy. Previously, it was shown that in potential sperm receptor glycoproteins of the ascidian Phallusia mammillata, N-acetylglucosamine is the prevailing glycoside residue and that the egg harbors three active molecular forms of ,-hexosaminidase. In the present study, P. mammillata,-hexosaminidase cDNA was isolated from an ovarian cDNA library and characterized. The deduced amino acid sequence showed a high similarity with other known ,-hexosaminidases; however, P. mammillata,-hexosaminidase had a unique potential N-glycosylation site. A phylogenetic analysis suggested that P. mammillata,-hexosaminidase developed independently after having branched off from the common ancestor gene of the chordate enzyme before two isoforms of the mammalian enzyme appeared. In situ hybridization revealed stage-specific expression of ,-hexosaminidase mRNA during oogenesis in the oocyte and in the accessory test and follicle cells. This suggests that the three egg ,-hexosaminidase forms are specific for the oocyte, test cells and follicle cells. [source] Incorporation of ZP1 into perivitelline membrane after in vivo treatment with exogenous ZP1 in Japanese quail (Coturnix japonica)FEBS JOURNAL, Issue 14 2008Mihoko Kinoshita In birds, the egg envelope surrounding the oocyte prior to ovulation is called the perivitelline membrane and it plays important roles in fertilization. In a previous study we demonstrated that one of the components of the perivitelline membrane, ZP3, which is secreted from the ovarian granulosa cells, specifically interacts with ZP1, another constituent that is synthesized in the liver of Japanese quail. In the present study, we investigated whether ZP1 injected exogenously into the blood possesses the ability to reconstruct the perivitelline membrane of Japanese quail. When ZP1 purified from the serum of laying quail was injected into other female birds, the signal of this exogenous ZP1 was detected in the perivitelline membrane. In addition, we revealed, by means of ligand blot analysis, that serum ZP1 interacts with both ZP1 and ZP3 of the perivitelline membrane. By contrast, when ZP1 derived from the perivitelline membrane was administered, it failed to become incorporated into the perivitelline membrane. Interestingly, serum ZP1 recovered from other Galliformes, including chicken and guinea fowl, could be incorporated into the quail perivitelline membrane, but the degree of interaction between quail ZP3 and ZP1 of the vitelline membrane of laid eggs from chicken and guinea fowl appeared to be weak. These results demonstrate that exogenous ZP1 purified from the serum, but not ZP1 from the perivitelline membrane, can become incorporated into the perivitelline membrane upon injection into other types of female birds. To our knowledge, this is the first demonstration that the egg envelope component, when exogenously administered to animals, can reconstruct the egg envelope in vivo. [source] Crystallization and preliminary X-ray analysis of ZHE1, a hatching enzyme from the zebrafish Danio rerioACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 10 2009Akitoshi Okada The hatching enzyme of the zebrafish, ZHE1 (29.3,kDa), is a zinc metalloprotease that catalyzes digestion of the egg envelope (chorion). ZHE1 was heterologously expressed in Escherichia coli, purified and crystallized by the hanging-drop vapour-diffusion method using PEG 3350 as the precipitant. Two diffraction data sets with resolution ranges 50.0,1.80 and 50.0,1.14,Å were independently collected from two crystals and were merged to give a highly complete data set over the full resolution range 50.0,1.14,Å. The space group was assigned as primitive orthorhombic P212121, with unit-cell parameters a = 32.9, b = 62.5, c = 87.4,Å. The crystal contained one ZHE1 molecule in the asymmetric unit. [source] Egg incubation time and hatching success in tench Tinca tinca (L.) related to the procedure of egg stickiness eliminationJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2003D. Gela Summary The experiment showed different results after a short (2 min) enzyme alcalase Merck EC 3.4.21.14 (5.0 ml L,1 concentration) treatment of tench eggs in contrast to the traditional methods of eliminating egg stickiness involving milk solution (50 g L,1) treatment for 70 min followed by the addition of a talc suspension (33 g L,1) for 10 min or treatment by fine clay suspension (20 g L,1) for 60 min or talc suspension (33 g L,1) for 80 min. The alcalase enzyme treatment resulted in decreased egg stickiness compared with the conventional milk/clay/talc treatments, indicated by lower duration of egg incubation and higher hatching rates (anova for hatching rate, P < 0.0084). The highest hatching rate (93.2%) was achieved using the enzyme; the lowest (31.3%) was using a talc suspension (control hatching rate was 86.2%). Duration of egg incubation at degree-days (D°) after enzyme treatment (58.6 D°) was about 4,5 h shorter than the classical method using milk solution and talc suspension (63,65 D°). Prolongation in the latter classical method may also be explained by a hardening of the egg envelopes. [source] Effects of tributyltin(IV) chloride on fertilization of Styela plicata (Ascidiacea: Tunicata): II.APPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2003Scanning, transmission electron microscopy studies Abstract The morphological aspects of Styela plicata fertilization after treatment with tributyltin(IV) chloride are described by means of scanning and transmission electron microscopy investigations. Alterations have been shown both on female and male gametes; spermatozoa, all the egg envelopes and the mitochondria of the egg cortical cytoplasm are modified in relation to incubation time. As a consequence, the damage to gametes blocks sperm,egg interaction and fertilization does not occur. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||