两种鲤鲫杂交回交子代染色体核型分析及比较

采用PHA和秋水仙素体内注射制备两种鲤鲫杂交回交子代鱼（鲤鲫杂交♀×德国镜鲤♂;鲤鲫杂交♀×鲤♂）的染色体。结果表明：两种鲤鲫杂交回交子代染色体组由150条染色体组成,按着丝粒位置染色体组型可分为四组,每个染色体小组均由三条同源染色体组成。其中鲤鲫杂交♀×鲤♂回交的染色体数目为3n=150,染色体臂数NF=234,其核型公式为：3n=60m＋24sin＋36st＋30t;鲤鲫杂交♀×德国镜鲤♂回交染色体数目为3n=150,染色体臂数NF=258,其核型公式为：3n=63m＋45sin＋12st＋30t。     

Selection of a new scallop strain,QN‐2, from the backcross of Peruvian scallop × bay scallop F1 hybrids with bay scallops

Cross‐breeding has been successfully applied in agriculture and aquaculture industries to improve important production traits. In our previous studies, we produced the F₁ hybrids with high heterosis in growth by crossing the bay scallops with the Peruvian scallops and selected a new strain, Bohai Red, from the F₁ hybrids. In this study, we selected another new strain from the backcross (BC₁) of the F₁ hybrids with bay scallops. The base cohort (G₀) was size‐selected from the BC₁, and the G₁, G₂, G₃ and G₄ cohorts were produced with size‐selected brood stocks from the G₀, G₁, G₂ and G₃ cohorts respectively. Our results showed that average shell height, shell length, shell width and whole body weight of the G₄ cohort were increased by 16.8%, 16.8%, 11.5% and 43.6%, respectively, compared with the unselected control group of bay scallop. This new strain has now become one of the major cultured Argopecten scallops in northern China waters and was later named QN‐2.     

Marker-Assisted Pyramiding of Genes Conferring Resistance Against Bacterial Blight and Blast Diseases into Indian Rice Variety MTU1010

Two major bacterial blight(BB) resistance genes(Xa21 and xa13) and a major gene for blast resistance(Pi54) were introgressed into an Indian rice variety MTU1010 through marker-assisted backcross breeding. Improved Samba Mahsuri(possessing Xa21 and xa13) and NLR145(possessing Pi54) were used as donor parents. Marker-assisted backcrossing was continued till BC2 generation wherein PCR based functional markers specific for the resistance genes were used for foreground selection and a set of parental polymorphic microsatellite markers were used for background selection at each stage of backcrossing. Selected BC2F1 plants from both crosses, having the highest recoveries of MTU1010 genome(90% and 92%, respectively), were intercrossed to obtain intercross F1(ICF1) plants, which were then selfed to generate 880 ICF2 plants possessing different combinations of the BB and blast resistance genes. Among the ICF2 plants, seven triple homozygous plants(xa13xa13Xa21Xa21Pi54Pi54) with recurrent parent genome recovery ranging from 82% to 92% were identified. All the seven ICF2 plants showed high resistance against the bacterial blight disease with a lesion lengths of only 0.53–2.28 cm, 1%–5% disease leaf areas and disease scoring values of ‘1' or ‘3'. The seven ICF2 plants were selfed to generate ICF3, which were then screened for blast resistance, and all were observed to be highly resistant to the diseases. Several ICF3 lines possessing high level of resistance against BB and blast, coupled with yield, grain quality and plant type on par with MTU1010 were identified and advanced for further selection and evaluation.     

Effect of allelic variation at the Glu-3/Gli-1 loci on breadmaking quality parameters in hexaploid wheat (Triticum aestivum L.)

Low molecular weight glutenin subunits (LMW-GS) encoded by the Glu-3 loci are known to contribute to wheat breadmaking quality. However, the specific effect of individual Glu-3 alleles is not well understood due to their complex protein banding patterns in SDS-PAGE and tight linkage with gliadins at the Gli-1 locus. Using DNA markers and a backcross program, we developed a set of nine near isogenic lines (NILs) including different Glu-A3/Gli-A1 or Glu-B3/Gli-B1 alleles in the genetic background of the Argentine variety ProINTA Imperial. The nine NILs and the control were evaluated in three different field trials in Argentina. Significant genotype-by-environment interactions were detected for most quality parameters indicating that the effects of the Glu-3/Gli-1 alleles are modulated by environmental differences. None of the NILs showed differences in total flour protein content, but relative changes in the abundance of particular classes of proteins cannot be ruled out. On average, the Glu-A3f, Glu-B3b, Glu-B3g and Glu-B3i_Man alleles were associated with the highest values in gluten strength-related parameters, while Glu-A3e, Glu-B3a and Glu-B3i_Chu were consistently associated with weak gluten and low quality values. The value of different Glu-3/Gli-1 allele combinations to improve breadmaking quality is discussed.     

尼罗罗非鱼与萨罗罗非鱼回交一代与回交二代群体遗传特征的微卫星分析

利用尼罗罗非鱼(Oreochromis niloticus)第二代遗传连锁图谱中微卫星标记,对尼罗罗非鱼♀与萨罗罗非鱼(Sarotherodon melanotheron)回交一代(BC1)和回交二代(BC2)群体遗传特征进行了分析。结果表明,从28个微卫星位点中筛选出9个在尼萨回交一代和回交二代中存在差异的扩增位点,这些多态性位点可作为尼萨回交一代和回交二代群体遗传鉴别的重要依据。尼萨回交一代群体的平均观测杂合度为0.670,多态信息含量为0.423;回交二代群体的平均观测杂合度为0.460,多态信息含量为0.365,回交二代群体的遗传多态性低于回交一代群体。与回交一代相比,尼萨回交二代群体的平均有效等位基因数较为一致(BC1:Ne=2.17,BC2:Ne=2.20),基因型数较为一致,但纯合基因型比例、优势等位基因频率均有明显提高,表明连续回交导致后代遗传同质性提高。     

Do Horses Prefer Certain Substrates for Rolling in Grazing Pasture?

We assessed whether rolling damage by grazing horses could be reduced by constructing areas assigned for rolling. A group of horses were enclosed in a paddock with and without rolling areas made of dry soil, sand, and straw. Their behavior was recorded for 1 week in the paddock without any treatment (control paddock). Then the horses were moved to another paddock with the rolling areas (rolling paddock). After a 3-week familiarization period, horses were observed for 1 week. In the rolling paddock, the frequency and time spent rolling were significantly greater in rolling areas than in nonrolling areas. Horses significantly preferred the soil rolling area than sand and straw (P < .05). Although rolling was considered the most relevant body care behavioral element, the effects of the substrate in rolling areas on other body care behavioral activities, such as mutual and self-grooming, also were investigated. The frequency and duration of mutual grooming and the duration of self-grooming decreased significantly in the rolling paddock compared with the control paddock (P < .05). Hence, offering a rolling area encourages horses to roll in these areas and keeps the pasture in good condition; therefore, grazing time can be increased, with less reliance on supplementary feed.     

利用野生稻高代回交群体分析水稻农艺性状QTL

本研究用来源于马来西亚的普通野生稻(IRGC-105491)与珍汕97B杂交并回交构建148个株系的高代回交群体(BC_2F_4),用152个均匀分布的SSR标记构建了分子遗传连锁图,其图谱长为1 342.1 cM,相邻标记间距为8.8 cM.利用该群体检测定位到影响株高、生育期、穗数、穗长及千粒重、粒长、粒宽等农艺性状的27个QTL;在这些QTL中约有59%有利基因来源于野生稻.野生稻中有利基因的发掘和利用将为分子标记辅助培育水稻新品种奠定基础.     

陆海杂种高代回交自交系纤维细度性状相关性分析

 利用陆地棉34B与海岛棉Giza70杂交所得的稳定的高代回交自交系BC₂F_4:6 、BC₂F_4:7家系,开展了三个环境下纤维细度等品质性状的相关分析。结果表明：1)纺纱均匀指数与长度、整齐度、比强度呈极显著正相关,与伸长率呈极显著负相关。纤维长度和比强度间均存在极显著的正相关,与伸长率呈极显著负相关。2) HVI 900测定的麦克隆值与比强度和纺纱均匀指数呈极显著负相关;成熟度比率与麦克隆值呈显著或极显著正相关,与线密度呈极显著负相关,与其它性状间的相关性三个环境下都不一致;线密度与纺纱均匀指数呈极显著正相关,与长度、比强度均达到极显著或显著负相关,与整齐度不相关,与伸长率为负相关。相对而言,线密度与各性状的相关性要比HVI 900测定的麦克隆值和成熟度比率稳定,受环境影响小,有必要进一步加强对线密度的选择及深入研究。     

线纹尖塘鳢(♀)、云斑尖塘鳢(♂)及其杂交、回交子代遗传变异的微卫星分析

为选育出生长快、外形美、耐粗饲、易起捕的尖塘鳢属鱼类新品种。本研究用20对微卫星引物对线纹尖塘鳢(♀)、云斑尖塘鳢(♂)及其杂交、回交子代的遗传变异进行分析。结果表明：20对引物在4个群体中共检测出87个等位基因,平均等位基因数以线纹尖塘鳢最低(1.6087),杂交子代F1最高(2.9130);平均有效等位基因数依次为云斑尖塘鳢(2.2570)>杂交子代F1(2.1516)>回交子代F2(2.1061)>线纹尖塘鳢(1.5164);在4个群体中平均观测杂合度(Ho)、期望杂合度(He)、多态信息含量(PIC)和香农指数(I*)4个参数的变化范围分别为：0.4891~0.7767、0.2714~0.5193、0.3473~0.4458、0.3662~0.7993。其中,各参数均为线纹尖塘鳢群体最低,平均观测杂合度和香农指数杂交子代F1最高,平均期望杂合度回交子代F2最高,多态信息含量云斑尖塘鳢群体最高,且各群体的平均观测杂合度均高于平均期望杂合度;哈代-温伯格平衡的χ2检验结果表明：绝大多数位点发生了偏离(P<0.05);根据Nei’s遗传距离建立的UPGMA聚类图表明：杂交子代F1和回交子代F2聚为一支后再与线纹尖塘鳢聚为一支,而云斑尖塘鳢为另一支,并且无论是杂交还是回交均表现了一定的母本效应。     

两种模式酵母中可分解丙酮醛的GLO3的特性及鉴定

GLO3是一种不依赖辅助因子就可分解丙酮醛的酶,有研究表明大肠杆菌的EcHsp31和人的HsDJ 1均属于这种GLO3。丙酮醛是细胞糖酵解过程中产生的一种有毒的副产物,乙二醛酶Ⅰ(GLO1)和乙二醛酶Ⅱ(GLO2)在谷胱甘肽(GSH)的辅助下可以降解细胞内丙酮醛,乙二醛酶Ⅲ(GLO3)不需要GSH的辅助可以直接降解MG。研究真菌的GLO3降解丙酮醛的机制,对认识和研究因丙酮醛引起的疾病具有重要的指导意义。研究表明,真菌中GLO3同源蛋白十分复杂,Hsp31在真菌中广泛存在,DJ 1只在部分真菌中存在,进化树结果支持GLO3的同源蛋白Hsp31和DJ 1是一种趋同进化。对模式真菌酿酒酵母的ScHsp31和裂殖酵母SpDJ 1进行GLO3的酶活测定和HPLC产物检测表明,这两种蛋白均具有GLO3的特性。