21世纪桑蚕生产的技术革命—专养雄蚕

浙江省农科院夏建国教授主持的课题组培育成功了“雄蚕新组合”蚕种。该小组从1996年起,在引进俄罗斯蚕性别控制系列品种及全部技术资料的基础上,经过2年努力,6个世代的基因转移和定向选择,研究出让雌性卵全部死去的基因。探索出使雌雄卵分别按不同颜色来选出雄卵的方法。

Comparative studies on in vitro sperm decondensation and pronucleus formation in egg extracts between gynogenetic and bisexual fish

A cell-free system based upon the egg extracts from gynogenetic gibel carp (Carassius auratus gibelio)or bisexual red common carp (Cyprinus carpio red variety) was developed to investigate developmentalbehaviors of the demembranated sperm nuclei. Both red common carp and gibel carp sperm nuclei coulddecondense fully and form pronuclei in the red common carp egg extracts. Gibel carp sperm nuclei couldalso decondense fully and form pronuclei in the gibel carp egg extracts, but red common carp sperm nucleicould not decondense sufficiently in the same extracts. The significant differences of morphological changeswere further confirmed by ultrastructural observation of transmission electron microscopy. The data furtheroffer cytological evidence for gonochoristic reproduction in the gynogenetically reproducing gibel carp. Inaddition, the sperm nuclei in vitro decondensation is dependent on the pH in the extracts, and the decon-densed efficiency is optimal at pH 7. However, no DNA replication was observed in the two kinds of eggextracts during the incubation period of the sperm nuclei. It is suggested that the egg extracts preparedfrom the gynogenetic gibel carp should be a valid in vitro system for studying molecular mechanism ongynogenesis and reproduction mode diversity in fish.

Comparative investigation on spindle behavior and MPF activity changes during oocyte maturation between gynogenetic and amphimictic crucian carp

The spindle behavior and MPF activity changes in the progression of oocyte maturation were investigated and compared with cytological observation and kinase assay between gynogenetic silver crucian carp and amphimictic colored crucian carp. MPF activity was measured by using histone H1 as phosphorylation substrate. There were two similar oscillatory MPF kinase activity changes during oocyte maturation in two kinds of fishes with different reproductive modes, but there existed some subtle difference between them. The subtle difference was that the first peak of MPF kinase activity was kept to a longerlasting time in the gynogenetic silver crucian carp than in the amphimictic colored crucian carp. It was suggested that the difference may be related to the spindle behavior changes, such as tripolar spindle formation and spindle rearrangement in the gynogenetic crucian carp.

Stimulation of Brain Tubulin Synthesis by Estrogen in Ovariectomized Mice and Intact Female Mice

The effect of sex hormones on the biogenesis of brain tubulin has been studied in the ovariectomized middle-aged and ovary-intact old-aged female mouse.The results show the much stronger role estrogen plays in stimulating tubulin synthesis than testosterone. Estradiol increased the contents of brain tubulin by 15%-41%. Estradiol and progesterone together can produce a 23%-49% increase. Maybe this experiment revealed a kind of new action of estrogen, i.e., stimulates brain tubulin syntheses in adult mouse.It is important that the effect of estrogen on stimulating tubulin synthesis takes place after the critical period of brain development. All of these mean that estrogen still plays its role in stimulating tubulin synthesis wile thyroid hormones can't play this kind of role during this time.

Prognostic Significance of Hormonal Receptor Status of Malignant Ovarian Tumors

The objective of this study is to investigate hormonal receptor status of MOT （malignant ovarian tumor） and to evaluate its clinical and prognostic significance. Retrospective analysis of the case reports of 284 patients with MOT of different histogenesis, stages I-IV, and immunohistochemical study of paraffin-embedded tissues were performed. Hormonal receptor status of tumors with different morphology genesis was studied and hormonal receptor phenotype of serous OC （ovarian cancer） was determined. The analysis of correlation between the expression of steroid hormone receptors （receptors to estrogens （ER）, progesterone （PR） and testosterone （TR）） in ovarian tumors, histological type of tumors and clinical morphological parameters were performed. Overall and relapse-free survival rates of the patients with serous OC depending on the hormonal receptor phenotype of the tumor were assessed. Presence of positive expression of steroid hormone receptors in serous OC （ER-66.4%, PR^53.4%, TR-53.0%）, mucinous OC （ER-88.0%, PR-84.0%, TR-60.0%） and in sex cord stromal tumors （ER-74.1%, PR and TR-77.8%） is proved by correlation of all steroid receptors expression with morphology type of ovarian tumors （ER - r = 0.4; PR - r = 0.4; TR - r = 0.3; p 〈 0.05）. Direct correlation between hormonal receptor phenotype of serous OC and the age period of the patients was established （r = 0.5; p = 0.002）： postmenopausal women patients reported the most increased frequency of serous OC with positive hormonal receptor tumor phenotypes （52.4%）, in particular during their late post-menopausal period （39.0%）. Significantly low overall survival among the patients with positive hormonal receptor phenotype of serous OC was recorded （29.5±3.4%） in comparison with the same score in the patients with negative phenotype of tumors （44.5±3.7%） （p 〈 0.05）. Multifactor analysis of Cox-regression model has defined that positive hormonal receptor phenotype of serous OC increases the risk of disease relapse （HR 1.4; 95.0% CI 1.1-1.7）, significantly decreases overall survival rates in the patients （HR 1.4; 95.0% CI 1.1-1.8）. Positive hormonal receptor status of MOT is an independent factor of unfavorable clinical progress of tumor process which can be regarded as the criterion for development of the methods of hormonal therapy application in complex treatment of the patients, and demands further large-scale multi-center studies in that direction.