Dynamic Distribution of Glycoconjugates During Oogenesis of Atractomorpha sinensis
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Abstract
The dynamic distribution of three different glycoconjugates in oocytes and follicle cells during the oogenesis of Atractomorpha sinensis were detected using biotinlabeled Peanut Agglutinin (PNA), Soy Bean Agglutinin (SBA) and Ulex Europaeus Agglutinin I (UEA-I) lectins. The results showed that during oogenesis there was no distribution of the UEA-I receptor. The receptors of PNA and SBA were found to be dependent on developmental stage and present different distribution patterns accordingly. The binding sites of the two lectins indicated the presence of different sugars (PNA for Galβ1,3GalNAc and SBA for GalNAc) and showed considerable variation during oogenesis. PNA and SBA receptors first appeared at the oocyte growth phase, the PNA receptors then disappeared gradually and the SBA receptors exhibited the greatest expression. At the early phase of yolk formation, PNA and SBA receptors were located just at the brim of ooplasm, which was the region of vitellin formation. However at the later phase of yolk formation, neither of the two receptors was detected. In the mature egg, PNA and SBA receptors were distributed again on the vitellin membrane and the eggshell. The two receptors were also widely distributed in the follicular cells, showing similar distribution variation to the oocytes. The results indicate that the change and modification of the two receptors may be greatly related to the growth of oocytes, the preparation for yolk formation, the differentiation of follicular cells and the maturation of oocytes. The glycoconjugates on the vitellin membrane probably play important roles in sperm and egg recognition. The two lectins bound moderately or strongly to the eggshell, which indicates that the eggshell of A. sinensis contains the GalNAc and Galβ1,3GalNAc glycoproteins.
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