摘要
分别用遗传失活的散鳞镜鲤(Cyprinus carpio L.)、团头鲂(Megalobrama amblycephala)精子诱导日本白鲫(Carassius cuvieri)进行雌核发育。未经冷休克处理,用 UV 照射过的镜鲤的精子(其最佳 UV 照射剂量为 4 200 mJ/cm2)与日本白鲫卵子受精获得(32.4±3.3)%雌核发育单倍体和(0.7±0.3)%杂交二倍体,而照射过的团头鲂精子(其最佳UV照射剂量为3 600 mJ/cm2)与日本白鲫卵子受精得到了(33.8±1.4)%雌核发育单倍体和(0.5±0.3)%杂交二倍体。日本白鲫卵子分别经灭活的镜鲤、团头鲂的精子激活(精子经各自最佳UV剂量处理),施以冷休克处理(受精后2 min,0–4℃,40 min),其孵化率分别为(27.8±2.1)%和(29.4±3.3)%,发育到摄食期,其正常的雌核发育二倍体鱼苗分别为(15.7±3.4)%和(23.6±4.1)%,在镜鲤实验组中,其正常的雌核发育二倍体鱼苗占孵化鱼苗总数的56%,这比团头鲂实验组中正常雌核发育二倍体鱼苗的比率(达到80%)低,结果表明诱导日本白鲫雌核发育,与母本遗传关系远的团头鲂精子较镜鲤的更有效。从染色体数目、外形特征和性腺结构等方面证实雌核发育后代的生物学特性。雌核发育日本白鲫全为雌性,这表明其雌性是同配XX型。雌核发育日本白鲫在生产上将有着潜在的价值,如比普通日本白鲫长得更快,抗病能力强等。所有的雌核发育日本白鲫的染色体数目都是100,而所有的团头鲂与日本白鲫的杂交后代都是三倍体(3n=124),新三倍体鱼在鱼类养殖和理论研究中将存在潜在的价值。
Diploid gynogenesis was induced in Japanese crucian carp （Carassius cuvieri） eggs using UV-irradiated genetically inactive spermatozoa from mirror carp （Cyprinus carpio L.） or blunt snout bream （Megalobrama amblycephala）, with or without cold shock. The optimal radiation dosage was 4 200 mJ/cm^2 and 3 600 mJ/cm^2 for mirror carp and blunt snout bream sperm, respectively At this dosage and without cold shock, the yields were （32.4±3.3）% vs. （33.8±1.4）% gynogenetic haploids and （0.7±0.3）% vs. （0.5±0.3）% hybrid diploids, respectively. At the optimal UV dosage but with cold shock （2 min after fertilization, 0-4℃ for 40 min）, the hatching rates were （27.8±2.1）% and （29.4±3.3）%, respectively. From hatching to feeding, （15.7±3.4）% and （23.6±4.1）% normal gynogenetic diploids were recorded, respectively. Survival of normal gynogenetic diploids was 56% out of the hatched fry when using irradiated spermatozoa of mirror carp, which was lower than that （up to 80%） when using irradiated spermatozoa of blunt snout bream. This indicated that the sperm of blunt snout bream, with distant genetic relation to the maternal Japanese crucian carp, was more effective than that of mirror carp to induce diploid gynogenesis. The nature of the gynogenetic progeny was identified with external appearance, chromosome number and gonad structure. The presence of only females in gynogenetic progeny probably suggested XX genotype in the female Japanese crucian carp. The gynogenetic diploids have potential values such as faster growth and stronger disease resistance than the normal Japanese crucian carp. All gynogenetic progeny possessed 100 chromosomes whereas all J×B crosses were triploid with 124 chromosomes. The formation of the new triploid hybrids in J×B crosses may be useful in aquaculture.
基金
This work was supported by the National Natural Science Foundation of China (No. 30330480 and No. 30571444), the Key Project of Chinese National Programs for Fundamental Research and Development (No. 2001CB109006), and Training Project of Excel-lent Yong Research of the State Education Ministy of China (No. 200248).
关键词
雌核发育
杂交
三倍体
性别决定
gynogenesis
hybrids
triploids
sex determination
