虾夷马粪海胆(Strongylocentrotus intermedius)Vasa基因的克隆与表达

Vasa基因是DEAD-box家族成员中的一种ATP依赖的RNA解旋酶编码基因,在生殖系分化过程中发挥重要作用。采用同源克隆和cDNA末端快速扩增技术(RACE),从虾夷马粪海胆精巢中克隆得到Vasa基因3′端cDNA序列。该3′末端cDNA长1057bp,与太平洋牡蛎、紫球海胆、非洲爪蟾、小鼠及虹鳟经同源进行比对,其中与紫球海胆的同源率最高达到95%,并确定其为DEAD-box家族的Vasa亚家族成员。利用实时定量RT-PCR检测Vasa mRNA在虾夷马粪海胆组织和胚胎发育期的表达情况,研究结果表明Vasa基因在生殖腺表达量最高,雌、雄个体生殖腺中转录水平上的表达差异明显,雄性高于雌性,差异显著(P<0.05),在肠、体腔液、肌肉、围口膜、管足中表达量低,其中体腔液表达量最低。胚胎发育期检测发现Vasa基因在16细胞期时表达量最高,16细胞期后表达量呈下降趋势,囊胚期表达量最低。试验结果为虾夷马粪海胆生殖系统起源、分化研究提供科学依据。对于虾夷马粪海胆生殖系分化途径来讲,Vasa可作为一种有利的研究工具,追溯其生殖系的起源和分化。     

马粪海胆对环境变化的耐受性与选择性研究

对采自青岛近岸的马粪海胆进行温度、盐度、光强与底质等因子的耐受及选择实验。结果表明,青岛近岸马粪海胆的适温范围约在8-22℃,对温度的选择受驯养水温的影响;属窄盐性种类,适盐范围约在30-35;喜好弱光环境,饥饿状态的选择光强（8-25lx）较非饥饿状态（10-35lx）低;对粗沙砾底质具明显的正选择,而对细沙性底质呈明显的负选择。     

青岛近岸海域马粪海胆摄食的实验生态学研究

对采自青岛近岸海域的马粪海胆从其对各种饵料的选择和摄食吸收、温度与自身湿重对其摄食率的影响以及摄食活动特征等方面进行实验生态学研究。结果表明 ,马粪海胆在多种海藻并存的情况下 ,对海带及裙带菜等褐藻具明显的选择性 ,对石花菜及孔石莼等藻类的喜好性较差 ,但在食物匮乏条件下 ,马粪海胆的食谱则变得相当广泛。马粪海胆对裙带菜及海带的摄食率均明显高于孔石莼 ,但其对孔石莼的饵料吸收率则高于海带及裙带菜。马粪海胆的摄食受温度条件及自身湿重的影响 ,温度偏离适宜范围对摄食有抑制作用 ,日摄食率与湿重呈显著的指数下降关系 ,摄食率与湿重、温度因子可建立具较高可靠性的指数回归模型。马粪海胆对食物的口面吸附与对其摄食密切相关 ,其摄食活动与湿重呈显著的指数下降关系 ,而与排便活动呈显著的正相关 ,随湿重增加排便活动虽呈下降趋势 ,但未达显著水平。自然光照条件下马粪海胆的夜间摄食强度通常高于日间 ,但在全遮盖的无光照条件下这种昼夜摄食差异则变得不显著 ;对摄食活动的连续观测表明马粪海胆的摄食活动受光强变化的影响 ,其摄食活动的高峰出现在光强减弱的早间及傍晚 ,而日间的强光照环境会抑制其摄食活动     

虾夷扇贝的多态性微卫星座位

虾夷扇贝(Patinopectenyessoensis),为冷水性贝类,是世界最重要的养殖经济贝类之一。原产于俄罗斯千岛群岛的南部水域,日本北海道及本洲北部。中国80年代初从日本引种,并开始养殖,目前已经在黄海北部形成规模化和产业化养殖,其中以大连长海养殖规模最大,近10年来创造出了数十亿     

虾夷扇贝精子的超微结构

用扫描和透射电镜研究了虾夷扇贝(Patinopecten yessoensis)精子的超微结构.虾夷扇贝精子为典型的原生型,全长50μm左右,头部长约3 μm.精子主要由头部、中段和尾部三部分组成.头部顶体突出,呈倒"V"形;顶体下方为精核,电子密度较高且占头部大部分,具有核前窝(anterior nuclear fossa)、核后窝(posterior nuclear fossa)和植入窝(implantation fossa);4～5个近圆形的线粒体围绕着中心粒复合体形成精子的中段.尾部细长,尾部鞭毛横切面为典型的"9 2"结构.     

基于AFLP技术对中国虾夷扇贝群体种质资源的研究

利用AFLP技术对国内较具代表性的5个群体与日本群体虾夷扇贝相比照进行遗传多样性的分析.采用6对引物组合对6个群体178个个体进行扩增,共得到308个位点,6个群体的多态位点比例为62.66% ～69.81%,其中日本群体最高,小长山群体最低,且呈显著性差异;香农氏指数为0.337 ～0.374,其中日本群体最高,小长山群体最低.凌水桥群体与旅顺群体间遗传相似性最高(0.9810),小长山群体与凌水桥群体间遗传相似性最低(0.9641);相对的遗传距离的计算结果与遗传相似性结果一致.数据分析表明养殖方式对虾夷扇贝遗传多样性影响不大.本试验结果为我国虾夷扇贝种质遗传多样性维持、保护和可持续利用提供参考.     

虾夷扇贝遗传连锁图谱的初步构建

用AFLP标记首次构建了虾夷扇贝遗传连锁图谱。用56对引物组合对父母本和52个F^₁代个体进行遗传连锁分析, 共得到1 855个标记, 其中多态位点为598(32.2%)个, 而354个符合孟德尔1: 1分离比。用这些标记和23个偏分离标记(0.01相似文献   

虾夷扇贝遗传结构及微卫星标记与经济性状相关分析

选用30个多态性微卫星分子标记对大连大长山(96个)、大连獐子岛(96个)及日本青森县陆奥湾(96个)3个地区虾夷扇贝养殖群体(Patinopecten yessoensis)进行遗传多样性分析。结果显示,30个基因座共检测到198个等位基因(Na),平均等位基因数为6.63个,每个座位检测到的等位基因数为3-12,有效等位基因数(Ne)每个位点平均为4.70个,观测杂合度(Ho)平均值0.58,期望杂合度(He)的平均值为0.75,30个位点的平均多态信息含量为0.703,说明3个地区虾夷扇贝群体遗传多样性水平较高。运用统计软件SPSS11.5对30个微卫星标记与大长山群体生长性状相关性进行了分析。结果表明,位点DQ221714和FJ262378与壳长、壳高、壳宽和鲜重显著相关(P0.05)位点;位点FJ262372与壳宽、软体部重和闭壳肌重显著相关;位点FJ262369与软体部重及闭壳肌重显著相关。对差异显著的位点进行不同基因型间的多重比较,找到了与虾夷扇贝生长性状相关的基因型,进一步将所得显著性标记对大长山虾夷扇贝个体最大的17个和个体最小的13个基因组DNA进行检测,验证其准确性。结果表明,位点DQ221714在两组虾夷扇贝中存在特异性条带,可作为QTL定位候选标记。     

虾夷扇贝铜锌超氧化物歧化酶基因的克隆与转录表达特性分析

利用RACE和克隆等方法得到了虾夷扇贝铜锌超氧化物歧化酶(Cu/Zn-SOD)基因全长cDNA序列,该序列全长1 064 bp,5′和3′非编码区(UTR)分别为61 bp和541 bp,开放阅读框(ORF)462 bp,编码153个氨基酸和一个终止密码子.分析发现,此氨基酸序列含有形成二硫键的两个半胱氨酸残基以及4个铜结合位点、4个锌结合位点,与已知的Cu/Zn-SOD结构相似,与其它物种同源性较高.进行虾夷扇贝组织分布及发育过程中不同时期的实时荧光定量监测,发现鳃中Cu/Zn-SOD基因mRNA相对表达量最高,肾次之,血淋巴中最低;不同发育阶段Cu/Zn-SOD表达量变化明显,其中受精卵和早期D形幼体两个时期表达量相对较高.     

虾夷扇贝（Patinopecten yessoensis）5个群体的遗传多样性

虾夷扇贝为20世纪80年代初从日本引入我国并逐渐开展养殖的双壳贝类,目前已在我国北方地区大面积养殖。实验采用微卫星分子遗传标记技术对大连獐子岛底播增殖放流群体（CC）、黄海北部海区采集的野生群体（HQ）、日本青森养殖群体（JX）、俄罗斯远东日本海沿岸养殖群体（RX）及大连大长山岛养殖上壳白化群体（ZB）等5个虾夷扇贝群体的遗传多样性进行研究。其中HQ群体为本课题组2005年在黄海北部采集的野生群体,本研究筛选出一个该群体的特异性遗传标记。用8个微卫星位点进行扩增,共获得45个等位基因,每个位点的等位基因数处于3—9之间,大小为100—340bp,平均有效等位基因数为3．1535,基因型数为3—21个,PIC（PolymorphismInformationContent）值处于0．0322-0．5944之间。5个群体的平均观测杂合度分别为0．3292、0．3048、0．3167、0．2708、0．3042,平均期望杂合度分别为0．4595、0．4002、0．3838、0．3620、0．3885,群体间的多态性差异不显著。根据群体间遗传相似性系数、遗传距离及UPGMA聚类分析发现,CC和HQ群体亲缘关系最近,JX和RX群体的亲缘关系较近,ZB群体与JX和RX群体的亲缘关系较近。通过Hardy—Weinberg平衡及F-检验发现,5个群体都不同程度的偏离平衡,表明各群体基因频率和基因型频率的稳定性较低,且5个群体均处于不同程度的杂合子缺失状态,群体间的遗传分化程度较高,但遗传变异主要来自群体内的个体间。     

Characteristics of palindromic sequences in DNA of the sea urchin Strongylocentrotus intermedius

Some properties of the palindromic sequences in the sea urchin Strongylocentrotus intermedius nuclear DNA have been studied. It was shown that the amount of "foldback HAP bound DNA" and the S1 nuclease resistant DNA depends on renaturation temperature and Na+ concentration in solution. The authentic fraction of inverted repeats comprises 10-15% of the total DNA. The complexity of the palindromic fraction is approximately 8,2 X 10(7) nucleotide pairs and the average number of inverted repeats approximates 5 X 10(5) per haploid genome. The renaturation kinetics of inverted repeats with excess of total homologous DNA indicates that these sequences are enriched with unique DNA. The possible function of palindromic sequences is discussed.     

Cholinoreceptors of the dentis retractor muscle of the sea urchin Strongylocentrotus intermedius

Neostigmine increases and cholinergic blocking agents block contractions of Strongylocentrotus intermedius dentis retractor muscle caused by either acetylcholine or indirect stimulation. Both innervated and non-innervated parts of the muscle are sensitive to low acetylcholine concentration suggesting that there are both synaptic and extra-synaptic cholinoreceptors. Nicotinomimetics are more potent than muscarinomimetics. Both d-tubocurarine and atropine are weak blocking agents as compared to pentadecamethylene-bis-trimethylammonium or hexadecamethylene-bis-trimethylammonium, Kd being 1 X 10(-4) to 5 X 10(-5) and 5 X 10(-7) to 4 X 10(-7) M respectively. Disulphide bonds and carboxylic (or phosphate) groups were revealed in dentis retractor muscle cholinoreceptors using drugs modifying receptor structure. Cholinoreceptors of both nicotinic and muscarinic type were revealed in oesophagus longitudinal muscles of Strongylocentrotus intermedius.     

Calves' sex ratio in naturally and artificially bred cattle in central Ethiopia

A study was undertaken with the objective to identify some intrinsic (genotype of the cow, estrus time and parity) and extrinsic factors (service type, service time and estrus seasons) that affect calf sex ratio in naturally and artificially bred cattle in the central highlands of Ethiopia. A total of 4657 calving events were extracted from the long-term dairy cattle genetic improvement experiment at Holetta Agricultural Research Center. Factors that affect the logit of the probability of a female calf being born were obtained by using PROC GENMODE in Statistical Analysis System. Moreover, multivariate analysis was performed using PROC LOGISTIC procedure using forward selection procedure. Accordingly, genotype of the cow, parity, estrus season, and service type had considerable influences on calf sex ratio. However, estrus time and service time did not affect calf sex ratio (χ² = 0.83 and 0.79, respectively). In Ethiopia, smallholder dairy farmers often complain that artificial insemination (AI) skewed to producing more male calves. However, our study showed that AI did not alter female-to-male calf sex ratio. On the contrary, natural mating increases the probability of female calves born (odds ratio 1.38) over AI. Heifer/cows that showed estrus and bred during the harsh seasons of the years produced more female calves than those that bred during the good seasons of the year. This strongly agreed with Trivers and Willard sex allocation theory.     

Water-soluble Ca2+-calmodulin-binding proteins in embryo of the sea urchin Strongylocentrotus intermedius

• 1.1. About 0.3–0.4% of total water-soluble protein extracted from sea urchin embryos at the two-cell and early-gastrula stages was Ca²⁺-dependently bound to immobilized calmodulin.
• 2.2. SDS-PAGE of calmodulin-binding proteins revealed at least 20 polypeptides ranging from 200 to 15.5 kDa, and 70–80% of the protein belonged to a dozen major polypeptides. Polypeptides of 70, 55, 50, 45 and 18 kDa seemed to be the same as those that were detected earlier (Iwasa and Mohri, J. Biochem.94, 575–587, 1983).
• 3.3. The polypeptide spectrum of calmodulin target proteins changed significantly, e.g. the major polypeptides of 70 and 41 kDa increased, and the 200 and 43 kDa polypeptides decreased sharply during development from the two-cell to the early-gastrula stage.
• 4.4. According to our estimates, the molar concentrations of the calmodulin and targets were close enough, and therefore the Ca²⁺ signal should depend on the spatial-temporal distribution of free calmodulin in the cells.