用米蛾卵饲养捕虱管蓟马

捕虱管蓟马(Aleurodothrips fasciapennis)是多种蚧壳虫、桔云翅粉虱,黑刺粉虱和桔全爪螨的有效捕食性天敌。用米蛾卵作为饲料饲养捕虱管蓟马,可完成个体发育并产卵繁殖。与用白轮蚧壳虫的爬虫作饲料在室内试验比较,在发育历期。死亡率、雌性比、产卵量,成虫寿命及体形大小等方面,均较理想。在室内条件下,米蛾卵更适于用作繁殖捕虱管蓟马的饲料。这对于研究捕虱管蓟马的生物学、生态学以至田间散放应用是有利的。     

Molecular marker-assisted selection for yield-enhancing genes in the progeny of “9311×<Emphasis Type="Italic">O. rufipogon</Emphasis>” using SSR

Oryza rufipogon (IRGC105491) is a wild relative of cultivated rice, it contains two favorable yield-enhancing genes (yld1.1 and yld2.1) on chromosomes 1 and 2, respectively, which are capable of improving the yield of hybrid rice by 18 and 17%, respectively. SSR markers RM9, RM24, RM5 and RM306 are flanking yld1.1, while RM166 and RM208 are mapped in the close region to yld2.1. These molecular markers tightly linked to the two yield-enhancing genes were used to screen the plants of backcross population between 9311 (one of the top-performing parental lines in super hybrid rice seed production in China) and O. rufipogon. The results were as follows: (1) in BC₂F₁ population, the percentage of the individuals which contain both of the O. rufipogon alleles at marker loci RM166 and RM9 was 16.8%; (2) 1.5% individuals of total BC₃F₁ population have all the six linked markers (RM166, RM9, RM5, RM208, RM24, RM306); (3) in BC₄F₁ population, the percentage of the individuals which contain both of the two O. rufipogon alleles at marker loci RM166 and RM9 was 18.0%. Based on marker genotypes, the individuals, that contain multiple O. rufipogon markers, were selected and used for further backcross and self cross. Many 9311-type lines with yield-enhancing genes and high yield potential were obtained. After three times self-crossing a stable improved 9311 line was obtained. The results indicated that these molecular markers are feasible for marker-assisted selection (MAS) to screen rice individuals with high yield potential.     

股薄肌的应用解剖学研究

讨论了方程u"+((n-1)/r)u′+rm(up-u)=0(r＞0,p＞1,m∈Z+)的初值问题u′(a)=0,u(a)=α(a＞0,α＞0).利用能量函数及比较原理,得到了该问题的正解随初值α的变化情况.     

Vitamin D3 supplementation of cull cows: effects on longissimus and semitendinosus muscle tenderness

Previous studies have shown that supplementation of vitamin D3 to cow diets for 4 to 10 d before slaughter lowers Warner-Bratzler shear force (WBSF) values and increases sensory tenderness scores in beef cuts. The present study was conducted to evaluate the effects of vitamin D3 supplementation on muscle calcium concentration, WBSF values, and sensory tenderness ratings of LM and semitendinosus (ST) muscles from cull, predominately Angus, cows (eight cows per treatment). Treatments included 0 (control), 5 million IU, or 7.5 million IU of vitamin D3 supplemented daily for 7 d preslaughter. Twenty-four hours after slaughter, 2.54-cm-thick LM and ST muscle steaks were cut; aged for either 0, 7, 14, or 21 d (ST steaks aged for 7 d only); and frozen at -20 degrees C for WBFS and sensory analysis. Mean values for LM calcium concentration tended to increase (P = 0.14) with vitamin D3 supplementation (154, 176, and 183 microig/g, fresh basis, for 0, 5, and 7.5 million IU/d, respectively). After 7 d of aging, LM steaks from cows fed 7.5 million IU had lower (P < 0.05) WBSF values than 7-d steaks from controls and cows fed 5.0 million IU/d aged 7 d; however, vitamin D3 supplementation had no (P > 0.05) effect on WBSF values of ST steaks aged 7 d. Vitamin D3 supplementation did not (P > 0.05) affect sensory tenderness ratings for either LM or ST steaks at any aging period. Aging, however, had a linear (P < 0.001) effect on tenderness, with an increase in tenderness as aging time increased from 0 to 21 d. Thus, results from the present study indicate that vitamin D3 supplementation, at these levels and duration before slaughter, provided little benefit to muscle tenderness of beef from cull cows.     

微卫星标记与动物遗传育种

微卫星标记具有数量多、在基因组中分布广、多态性丰富，呈孟德尔式共显性遗传、检测快速方便等优点，在动物遗传育种中显示出较好的发展前景。笔者综述了微卫星标记及其在动物遗传育种中的应用。     

早熟油桃品种‘双喜红’

 油桃‘双喜红’是以‘瑞光2号’×89-1-4-1-2通过胚培养方法获得的优良早熟品种。该品种果形圆整，全面着红色，不裂果，平均单果160 g，果肉黄色，硬溶质，风味浓甜，可溶性固形物12.5%，半离核；丰产；果实发育期85 d左右；需冷量650 h。     

pH值对猪卵母细胞体外成熟培养的影响

通过用不同pH值的培养观察分析对猪卵母细胞体外成熟培养的影响。结果表明：猪卵母细胞在培养液pH值低于6．5时几乎全部死亡，而pH值达到8，9时死亡率仅为31.7％，经分析，猪卵母细胞对碱性条件的耐受能力比对酸性条件的耐受能力要强。