RELATIONSHIP BETWEEN THE PRESENCE OF ENDOGENOUS NICKS AND SPERM CHROMATIN PACKAGING IN MATURING AND FERTILIZING MOUSE SPERMATOZOA
RELATIONSHIP BETWEEN THE PRESENCE OF ENDOGENOUS NICKS AND SPERM CHROMATIN PACKAGING IN MATURING AND FERTILIZING MOUSE SPERMATOZOA
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DOI：
10.1095/biolreprod52.5.1149
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发表时间：
1995-05-01
影响因子：
3.6
通讯作者：
BIANCHI, U
中科院分区：
文献类型：
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作者：
SAKKAS, D;MANICARDI, G;BIANCHI, U
哺乳动物精子发生涉及组蛋白被鱼精蛋白取代，导致高度致密的染色质。受精后，相反的过程发生。我们先前已经证明色霉素A（3）（CMA（3））荧光染料是检测精子中鱼精蛋白缺乏的有用工具。在这项研究中，我们调查CMA（3）荧光染料的可及性和存在的内源性缺口在成熟和不育小鼠精子。1-7期和8-14期睾丸精子细胞对CMA（3）的阳性率较高（> 96%），15-16期精子细胞的阳性率降至63%。15-16期精子细胞的原位污染抑制了CMA（3）的可接近性。在输出管中只有8%的成熟精子呈CMA（3）阳性;在附睾头中这一值降至0%。在受精时，CMA（3）荧光在去致密化的精子中重新出现。异硫氰酸荧光素（FITC）荧光，识别内源性缺口，在6%的1-7期精子细胞中是明显的，在8-14期精子细胞中增加到22%，在15-16期精子细胞中消失。在受精过程中，内源性切口未观察到在decondensing spermatozo.We建议，1）在小鼠睾丸精子细胞中的切口的存在表明，DNA切割和连接发生在完成前污染和2）在受精过程中没有切口表明，decondensation是不简单的初始染色质包装过程的逆转。
Mammalian spermiogenesis involves the replacement of histones by protamines, resulting in a highly compacted chromatin. Upon fertilization, the reverse process occurs. We have previously shown that the chromomycin A(3) (CMA(3)) fluorochrome represents a useful tool for detecting protamine deficiency in spermatozoa. In this study we investigated CMA(3) fluorochrome accessibility and the presence of endogenous nicks in maturing and fertilizing mouse sperm. Testicular sperm of stages 1-7 and 8-14 showed high positivity (> 96%) to CMA(3), decreasing to 63% in stage 15-16 spermatids. In situ protamination of stage 15-16 spermatids saw an inhibition of CMA(3) accessibility. Only 8% of the mature spermatozoa in the efferent ducts were CMA(3)- positive; this value decreased to 0% in the caput epididymidis. At fertilization, CMA(3) fluorescence reappears in decondensing sperm. Fluorescein isothiocyanate (FITC) fluorescence, identifying endogenous nicks, was evident in 6% of stage 1-7 spermatids, increased to 22% in stage 8-14 spermatids, and disappeared in stage 15-16 spermatids. During fertilization, endogenous nicks were not observed in decondensing sperm.We propose that 1) the presence of nicks in mouse testicular spermatids suggests that DNA cutting and ligating occurs prior to completion of protamination and 2) the absence of nicks during fertilization indicates that decondensation is not simply the reversal of the initial chromatin packaging process.