人工诱导栉孔扇贝雄核发育早期的荧光显微镜观察

Observation on early development of artificially induced androgenesis in Chlamys farreri

利用荧光显微镜观察栉孔扇贝(Chlamysfarreri)正常卵子与雄核发育卵子在减数分裂、受精过程和卵裂早期中的核相变化。雄核发育单倍体是将强度为2.8mW/(cm2·s)的紫外线照射20s的卵子与正常精子受精后得到的。结果表明,尽管紫外线照射并没有影响卵子的成熟分裂及雌性、雄性原核的形成,但它们的发生过程滞后。在第1卵裂中期,雄核发育卵子中雌性原核并不像雄性原核一样形成染色体,而是形成1个浓缩的染色质小体(DCB)。第1卵裂后期,DCB不参与核分裂。第1卵裂结束时,DCB位于2个分裂球其中之一的细胞质内或在赤道板处被分割成两部分。实验结果首次提供了栉孔扇贝雄核发育的细胞学证据。

Nuclear changes in normal and androgenetic eggs of Chlamys farreri (body height 6.67 cm, body length 6.20 cm) were examined under a fluorescence microscope during their meiosis, fertilization and early development. The haploid androgenesis was induced by the eggs which were ultraviolet (UV)irradiated for 20 s at an intensity of 2.8 mW/(cm2·s). Although UV irradiation did not impact either meiotic maturation or formation of the male and female pronuclei, their developmental progress was delayed. At metaphase of the first cleavage, the female pronucleus in UV-irradiated eggs inseminated with the normal sperm did not form chromosome, unlike the male pronucleus, but became a dense chromatin body (DCB), which did not participate in the karyokinesis at anaphase of the first cleavage. At completion of cytokinesis of the first cleavage, the DCB was seen either in the cytoplasm of one of the two blastomeres or on the equatorial plate as two partitional parts. The cytological evidence of the induction of androgenesis in Chlamys farreri was demonstrated.