桑蚕几项数量性状的遗传力和选择的研究

用杂交群体对亲本回交法估计桑蚕几项性状的狭义遗传力表明,遗传力的大小因性状而异,茧层率、茧丝量及茧丝长有较高的遗传力,而全茧量及茧层量的遗传力较低。 选择试验表明,桑蚕各性状之间有高度的相关性,对某一性状的直接选择亦等于对另一些性状的间接选择。选育夏秋用蚕品种,应将茧层率控制在一定的范围内,向经过短、全茧量偏小的方向选择比较妥当;春用蚕品种的选育应控制全茧量,在提高茧层率的同时,大力向经过短的方向选择为宜。     

家蚕二化性杂交品种部分数量性状遗传参数的初步评估

采用完全随机设计法根据10头老熟幼虫体重、全茧重、茧层量、茧层率（%）、存活率、万蚕茧层量和茧丝长等指标,对两对二化性家蚕Bombyx mori L. 杂交品系（SH6×NB₄D₂和CSR₂×CSR₄）杂交一代的22个子代个体进行了遗传参数估算,以缩小优质蚕品种的候选范围,并且计算出直接筛选的参数,如遗传力和遗传进度等,使这些信息可用于以筛选高产新品种为目的的育种和选择过程中。杂交子代2, 4, 5, 6, 7, 10, 14, 16, 19和20号个体在这几个指标中表现出显著的优越性。全茧重、万蚕茧层量和茧丝长的遗传力和遗传进度较大,可以简单地从表现型的差异对这些性状进行选择并取得遗传性状改良。其他几个指标(10头老熟幼虫体重、茧层量、茧层率(%)和存活率)的遗传力和遗传进度较低,对这些性状进行直接选择来改良品种的效果较差。     

家蚕油蚕oc突变体突变基因的精细定位

【目的】油蚕oc突变体是家蚕Bombyx mori油蚕突变体的一种,经典遗传学连锁图谱已经将oc突变基因定位在5号染色体40.8 c M座位。本研究旨在对oc突变体候选基因进行精细定位并克隆,探究oc性状形成的分子机制。【方法】以油蚕oc突变品系和野生型家蚕品系大造(Dz)为亲本,其杂交产生的F1代雄性个体与oc突变的雌性个体进行回交得到的1 397头BC_1代个体为定位材料,以家蚕已经报道的基因组序列为参考设计markers,通过亲本及F1代个体筛选多态性markers,并利用多态性markers和BC_1代个体对oc突变基因进行精细定位。通过半定量RT-PCR和实时荧光定量PCR(q PCR)筛选oc紧密连锁区间内的候选基因,确定目标候选基因,继而克隆和测序该基因,分析油蚕oc突变的原因。【结果】利用1 397头BC_1代个体和11对有效的多态性markers将oc突变基因定位在M10与M11两个markers之间,物理图谱距离大约为234 kb。通过家蚕基因组数据库对oc连锁区域内的基因进行检索发现该区域有5个预测基因。对这5个预测基因在10个家蚕品系中进行的表达分析发现,只有BGIBMGA003572基因在oc突变个体体壁的表达量明显比正常个体中的低。通过基因的同源分析发现该基因编码的蛋白和人类单羧酸转运蛋白9(可能的尿酸转运蛋白)是同源蛋白,推测其为oc突变的候选基因。对BGIBMGA003572进行的克隆和测序结果显示其编码序列有5个氨基酸在oc突变体中发生了突变。【结论】通过定位克隆,本研究将oc突变基因定位在了234 kb的紧密连锁区间,其中编码单羧酸转运蛋白9的BGIBMGA003572可能和oc突变体的表型有关。     

家蚕Z→W染色体易位的诱导及其基因组成的分析

用4,000 R的X射线照射雌蚕蛹,从40,495头处理后代中获得目的易位型——Z染色体片段易位于W染色体的雌蚕,并用它育成蚁蚕体色限性系统(雌为黑蚁,雄为赤蚁)。经测定,易位片段不含有os(0.0)、c(36.4)、od(49.6)等座位,仅包含+~sch(21.5)座位附近很有限的区域,从而给出易位染色体基因组成的模式图。进一步比较了新限性系统和其他限性系统雌蚕的数量性状表现度,结果表明所有供试限性系统雌蚕都不同程度地受到易位染色体带来的生理障碍,特别是茧重、茧层重等数量性状表现明显。新限性系统雌蚕表现生理障碍较轻,可能是易位片段较小的缘故。     

油菜（Brassica napus）油酸性状的遗传规律研究

以高油酸油菜品系04-863(油酸含量80.5%)与低油酸油菜品系湘油15号自交系04-1020(油酸含量62.7%)为材料,通过杂交获f1、F2代和回交一代,研究了油菜油酸性状的遗传规律.结果表明:1)油菜油酸性状属数量性状.呈连续变异.很难明确分组;2)杂种一代表现为两亲本的中间类型,但受母本的影响较大,当以高油酸品系04-863为母本时,F1代的油酸含量(X=73.41)分布倾向高油酸亲本,相反,若以低油酸湘油15号自交系04-1020为母本,F1代油酸含量(X=67.75)分布则倾向低油酸亲本;3)对环境条件变化比较敏感,亲代(P1、P2)或F1代都存在着由于环境条件差异而引起的表型差异.F2代广泛分离既有基因型分离的差异,又有环境引起的表型差异.度量这种差异分别以方差和标准差来表示离开平均数的变异程度,在各世代中以F2的方差和标准差最大,分别为V=52.81,S=7.28;4)各代变异的次数分布大体上符合正态分布,即极端类型个体少,中间类型多;5)支配油菜油酸性状的基因数为一对主基因符合孟德尔的3:1分离规律,其回交比例为1:1,油酸性状的遗传力为69%～71%,是由于遗传差异引起的,另31%～29%则是由于环境差异引起的.说明数量性状与质量性状的区分是相对的.     

新桑树品种——川826的育成

经多年观察比较,新桑品种“川826”表现出遗传性状稳定、优质、高产、抗性较好等优点,2000年正式列为“十五”省农作物育种攻关项目“优质、高产桑、蚕新品种选育”中桑主攻品种,并进一步进行区域性比较试验。经过2002年至2005年在四川省乐山、三台、蚕研所等三点的比较试验和在四川篷安生产示范点的示范繁殖,“川826”与对照品种“湖32”相比,其产叶量高13.95%,万头产茧量高8.88%,万头产茧层量高8.8%,五龄担桑产茧量高13.51%,667 m2(亩)桑产茧量高28.2%,桑产茧层量高27.6%。特别是用“川826”桑叶养蚕后产卵制种成绩尤为突出,单蛾产卵量比对照高6.87%以上,单蛾正常卵粒数比对照高5.63%以上。2006年4月被四川省农作物品种审定委员会审定为合格品种。     

家蚕茧质性状的性别效应预测

研究采用混合线性模型,对家蚕全茧量、茧层量、茧层率和蛹体重等性状的性别效应进行理论估算：全茧量、茧层量、茧层率和蛹体重等4性状的性别随机效应的方差的概率和性别随机效应的预测值概率都达到极显著水平,证明全茧量、茧层量、茧层率和蛹体重等四性状的性别效应极显著,这完全符合实际情况。全茧量、茧层量、茧层率和蛹体重等4性状的性别效应预测值雌（雄）分别为0.248g（-0.247g）、2.423cg(-2.394)cg、-1.976%(1.992%)和0.224g(-0.223g)。性别效应调整后各性状均呈单峰正态分布,符合QTL分析对数量性状连续正态分布的要求。     

激光诱发家蚕孤雌生殖的研究：Ⅲ单性一号及单性二号性状表现

采用CO_2激光扩束辐照诱发家蚕孤雌生殖,从获得的单性蚕中,选择出单性一号和单性二号两个类型,单性一号由血色限性突变为斑纹限性,体质强健好养,单性二号仍保持亲本的血色限性,但茧丝质有了提高。     

家蚕近交系遗传纯度的RAPD检测

目的分析家蚕近交系IS-c108A的遗传纯度,为家蚕实验动物化的培育工作提供指导。方法应用经过筛选的20条随机引物对家蚕近交系IS-c108A(F10)的3个蛾区各30个个体和该近交系的亲本系统c108、对照实用化品种871各30个个体的基因组DNA进行RAPD扩增,计算个体间和蛾区间的相似系数及遗传距离。结果家蚕近交系IS-c108A(F10)的3个蛾区内的多态性带频率分别为1.807%、1.841%、1.841%,平均为1.830%;起点亲本c108个体间多态性带频率为7.207%,对照品种871个体间的多态性带频率为7.08%;而近交系IS-c108A与c108之间的多态性带频率为49.20%,c108和871品种之间的多态性带频率为58.33%。家蚕近交系IS-c108A10的3个蛾区内个体之间遗传相似系数的平均值分别为0.99581、0.99555、0.99551,总平均为0.99562。结论家蚕近交系IS-c108A(F10)已具有较高的遗传纯合度,家蚕具有易于获得高纯的有利条件。     

小麦早熟性遗传与选育方法的初步研究

研究证明,早熟性是由不同的亚性状组成的多基因控制的数量性状,遗传行为比较复杂。而且在不同生态类型间存在遗传差异。F_1的两个亚性状表现为反向遗传,即前显后隐,或前隐后显。全生育期的显性表现和前期基本一致,说明前期亚性状的遗传效应大于后期,成熟期与抽穗期密切相关(r=0.524)。小麦普遍存在杂种优势。不过不同品系的同一性状或同一品系的不同性状显示的优势差异很大。前期负向优势以奥尔生最强(-0.50%),后期则最弱(2.62%)。而且,同一品系在不同遗传背景下的优势也不同。F_2群体平均值,三个性状的顺序同F_1。超早亲的频率和幅度,同亲本的关系最密切。绝对超早的频率和幅度更有实际育种意义。早熟性遗传力值较高(抽穗期为51.9%,成熟期为43.9%)。可在早代选择,提高早熟育种效率。亲本的两个亚性状,在杂交后代中可以结合成各种构型的全生育期,规律是:两短难结合,超早频率低;两长易结合,超早频率高。说明前短和后短的不同亲本基因,很难在杂交后代中进行重组,形成全生育期最短的新基因型。但是某些品系的杂交,也会打破这种连锁,出现有利的基因重组。如前期较短的69-2(189.50天)与后期较短的奥尔生(38.99天)杂交,F_2出现17.2%的植株比理论全生育期还短,确是一个好组合。     

家蚕对马尾松毛虫质型多角体病毒的敏感性

用虫体克隆技术,对马尾松毛虫质型多角体病毒湖南株（DpCPV-HN）进行了分离纯化,鉴定为质型多角体病毒1型。以家蚕春蕾×镇珠杂种F₁代及自交的F₂代4或5日龄幼虫进行毒力测定,以纯化的家蚕质型多角体病毒对F₁代幼虫的毒力测定为对照。结果表明：家蚕品种春蕾×镇珠对家蚕质型多角体病毒敏感,马尾松毛虫质型多角体病毒湖南株能引起其感染发病;马尾松毛虫质型多角体病毒湖南株感染家蚕品种春蕾×镇珠F₁代幼虫和F₂代幼虫28天后的半致死剂量（LD₅₀）分别为885个和18个CPB(质多角体),前者为后者的49倍。马尾松毛虫质型多角体病毒湖南株感染后的家蚕,其结茧率、化蛹率、羽化率、全茧量、茧层量和单蛾产卵数均有所下降,全茧量、茧层量、茧层率和单蛾产卵数与病毒感染剂量之间无显著关联。     

Cytogenetic analysis shows that the unusually large chromosome in the sex-limited pB silkworm (Bombyx mori) strain consists of three chromosomes

We have discovered an inordinately large chromosome pair at the pachytene stage in the oocyte of the sex-limited pB (black larval marking) silkworm (Bombyx mori) strain (TWPB). We have analyzed the composition and arrangement of this large chromosome. A genetic linkage analysis shows that the large chromosome is made up of the W chromosome, the second chromosome fragment (pB fragment), and the fifth chromosome (linkage group) containing at least the region from map position 0.0 to 40.8. We also observed a sex heterochromatin body (SB) that we deduced to be made up of condensed W chromosomes. The number of SBs in each female nucleus among the sucking stomach cells of the TWPB strain was variable. Evidently, the W chromosome of the TWPB strain is attached to another chromosome. The composition of the W chromosome, the second chromosome fragment, and the fifth chromosome was studied through linkage analysis for these three chromosomes. We used two strains derived from the TWPB strain, the sex-limited pM (moricaud larval marking)-like (TWPML) and the autosomal pM-like (T5PML). The results show that the TWPML strain originates through a detachment of the fifth chromosome from the large chromosome of the TWPB strain, and the T5PML strain originates through a detachment of the W chromosome from that. Accordingly, the large chromosome of the TWPB strain is arranged in the order W chromosome--second chromosome fragment--fifth chromosome.     

Performance of polyvoltine silkworm Bombyx mori L. on different mulberry plant varieties

Five cultivated mulberry plant varieties, BSRM‐34, BSRM‐56, BSRM‐57, BSRM‐58 and BSRM‐59, were used to evaluate the effects of plant variety on larval and cocoon characteristics of mulberry silkworm Bombyx mori L. Silkworm larvae undergo their entire larval periods on leaves of mulberry varieties. Different larval characteristics of larval weight, larval length and larval breadth were measured in different growth stages. After rearing, the fifth instar larvae were transferred into a mountage (Chandraki) structure for cocoon rearing for spinning and cocoon production. The cocoons were then harvested and different cocoon characteristics like cocoon weight, shell weight and shell percentage; and other characters like pupal weight and effective rate of rearing were measured. The results showed statistically significant differences among different varieties on larval and cocoon characteristics. The highest performance was observed by feeding the variety BSRM‐34 in respect of the average weight of 10 mature larvae (40.5 g), single mature larval length (7.6 cm) and breadth (1.0 cm), single cocoon weight (1.4 g), shell weight (0.2 g) and pupal weight (1.2 g) while the average performance was recorded by feeding varieties BSRM‐57 and BSRM‐59. The poorest performance was showed by feeding the variety BSRM‐56 (in case of larval characters) and BSRM‐58 (in case of cocoon characteristics). These two varieties also showed the poorest performance for silk yield. Through comparing all the above parameters it was concluded that BSRM‐34 is the best mulberry variety and it is recommended that Bangladeshi farmers adopt that variety for better yield of silk.     

Comparison of phenotypic and genetic performance of local silkworm groups and two commercial lines

Five Iranian native silkworm groups: Baghdad, Khorasan Orange, Guilan Orange, Khorasan Pink, Khorasan Lemon, and 107 and 110 commercial lines (12 families from each breed) were randomly selected and reared during 2003-2005 (five generations in spring and autumn). In each family, 30 male and 30 female cocoons were individually recorded for weight, shell weight and shell ratio. From among the native groups, the highest average in all three traits belonged to Baghdad and Khorasan Pink, and the lowest to Khorasan Orange and Khorasan Lemon. From among the commercial lines, the highest average in all three traits belonged to 107. In comparing heritability for cocoon weight in native groups, the highest heritability belonged to Guilan Orange (0.5147) and Khorasan Orange (0.5036) and the lowest heritability belonged to Khorasan Pink (0.0967). In the two other traits, the highest heritability belonged to Khorasan Orange and Baghdad and the lowest to Khorasan Pink. In the commercial lines, line110 had higher heritability than line107 for cocoon weight and cocoon shell weight. In all the groups, genetic correlations between cocoon weight and cocoon shell weight were high, expect for the Baghdad group. There was medium or low genetic correlation among cocoon weight, cocoon shell weight and cocoon shell ratio.     

Identification of quantitative trait loci associated with egg quality, egg production, and body weight in an F2 resource population of chickens

Egg production and egg quality are complex sex-limited traits that may benefit from the implementation of marker-assisted selection. The primary objective of the current study was to identify quantitative trait loci (QTL) associated with egg traits, egg production, and body weight in a chicken resource population. Layer (White Leghorn hens) and broiler (Cobb-Cobb roosters) lines were crossed to generate an F2 population of 508 hens over seven hatches. Phenotypes for 29 traits (weekly body weight from hatch to 6 weeks, egg traits including egg, albumen, yolk, and shell weight, shell thickness, shell puncture score, percentage of shell, and egg shell colour at 35 and 55 weeks of age, as well as egg production between 16 and 55 weeks of age) were measured in hens of the resource population. Genotypes of 120 microsatellite markers on 28 autosomal groups were determined, and interval mapping was conducted to identify putative QTL. Eleven QTL tests representing two regions on chromosomes 2 and 4 surpassed the 5% genome-wise significance threshold. These QTL influenced egg colour, egg and albumen weight, percent shell, body weight, and egg production. The chromosome 4 QTL region is consistent with multiple QTL studies that define chromosome 4 as a critical region significantly associated with a variety of traits across multiple resource populations. An additional 64 QTL tests surpassed the 5% chromosome-wise significance threshold.     

一株感染家蚕的高致病性白僵菌的筛选及复合诱变

【背景】白僵蚕中的生物活性物质在医疗、保健品及化妆品行业有着广泛的应用。目前,许多人工养殖僵蚕基地在实际生产中使用的菌种多为未进行纯化优选的自然感病死亡僵蚕孢子粉且无固定的施用浓度,使得蚕的僵化死亡率难以保证。提高白僵菌菌株的致病力并筛选性状优良的高毒力菌株是工厂化生产白僵蚕研发的重要方向。【目的】利用紫外-微波复合诱变技术筛选高毒力菌株,为僵蚕工厂化生产提供优良菌株。【方法】利用孢子稀释法从山西省养殖农户中自然感染白僵菌的家蚕中分离获得一株原始白僵菌,运用紫外-微波复合的方式对该菌株进行诱变,并比较诱变前后菌株的产孢量及对家蚕的致病力。【结果】分离得到的原始菌株经鉴定为球孢白僵菌(Beauveria bassiana),命名为Beauveria bassiana Bb1003。通过对致死率和正突变率的考察,确定紫外-微波复合诱变的最佳诱变条件为紫外(功率为15 W)照射30 min,微波(功率为800 W、额定微波频率2 450 MHz)辐照60 s。筛选后得到6株复合诱变菌株(UMCM1、UMCM2、UMCM3、UMCM4、UMCM5和UMCM6)。菌株UMCM2对家蚕的僵化率高达...     

Identification of RAPD and SCAR markers associated with yield traits in the Indian tropical tasar silkworm Antheraea mylitta drury

The tropical tasar silkworm, Antheraea mylitta, is a semi-domesticated vanya silk-producing insect of high economic importance. To date, no molecular marker associated with cocoon and shell weights has been identified in this species. In this report, we identified a randomly amplified polymorphic DNA (RAPD) marker and examined its inheritance, and also developed a stable diagnostic sequence-characterized amplified region (SCAR) marker. Silkworms were divided into groups with high (HCSW) and low (LCSW) cocoon and shell weights, and the F₂ progeny of a cross between these two groups were obtained. DNA from these silkworms was screened by PCR using 34 random primers and the resulting RAPD fragments were used for cluster analysis and discriminant function analysis (DFA). The clustering pattern in a UPGMA-based dendogram and DFA clearly distinguished the HCSW and LCSW groups. Multiple regression analysis identified five markers associated with cocoon and shell weights. The marker OPW16_{905 bp} showed the most significant association with cocoon and shell weights, and its inheritance was confirmed in F₂ progeny. Cloning and sequencing of this 905 bp fragment showed 88% identity between its 134 nucleotides and the Bmc-1/Yamato-like retroposon of A. mylitta. This marker was further converted into a diagnostic SCAR marker (SCOPW 16_{826 bp}). The SCAR marker developed here may be useful in identifying the right parental stock of tasar silk-worms for high cocoon and shell weights in breeding programs designed to enhance the productivity of tasar silk.     

Contents of nutrients in ultra-fine powders of steamed and lyophilized mature silkworms generated by four silkworm varieties

Several health-promoting effects of mature silkworms, Bombyx mori, have recently been reported. Interestingly, those reports suggested that powders of steamed and lyophilized mature silkworms (SMSPs) generated from different varieties with unique cocoon colors may have additional and distinctive pharmacological activities. In our recent studies, “fine” SMSPs (fSMSPs) with an average particle size of 10 μm had higher contents of nutrients and enhanced their pharmacological activities, compared with “coarse” SMSPs (cSMSPs) with an average particle size of 120 μm. Recently, a new pulverizing method for SMSPs reducing their particle size to around 1.1 μm has been developed to generate “ultra-fine” SMSPs (ufSMSPs). In the present study, we analyzed and compared the contents of nutrients in the ufSMSPs generated by four different varieties with unique cocoon colors; white jade, yellow, pistachio, and red. The contents of almost all nutrients detected in the four ufSMSPs showed significant differences (p < .05) in at least one or more of the four varieties. The results of nutrient composition analyses in this study will be helpful for future studies to determine various unidentified functionalities of ufSMSPs in different varieties. We also examined the hair growth promoting activities of fSMSP and ufSMSP obtained from a pistachio cocoon strain to determine whether there is a correlation between contents of nutrients and pharmacological activity. Our data in the present study suggested that ufSMSPs might have enhanced and/or unique pharmacological effects due to their smaller particle size, although their contents of nutrients were comparable to or slightly lower than those in fSMSPs.