真核生物pre-mRNA剪接的研究进展

Pre-mRNA剪接,即把内含子去除并把外显子序列连接成为成熟的mRNA,是基因表达与调控的重要环节之一。本文在概述真核基因mRNA剪接反应机制的基础上,主要讨论pre-mRNA的剪接机器,剪接体如何催化pre-mRNA剪接反应和pre-mRNA选择性剪接等方面的研究进展。     

Development of semidwarf breeding line with shattering resistance and preharvest-sprouting resistant in buckwheat (Fagopyrum esculentum)

An important breeding issue in buckwheat is to increase its resistance to lodging, which can result in the loss of yield and quality of buckwheat foods. We developed the semidwarf buckwheat ‘Kyukei 50’, which has a short plant height and a strong lodging resistance. The internode length of ‘Kyukei 50’ was shorter than that of the summer-sown standard variety ‘HITACHIAKISOBA’. Progeny analysis revealed that the semidwarf trait was dominated by at least one recessive gene. Compared with ‘HITACHIAKISOBA’, in ‘Kyukei 50’, the time of maturation was earlier, and the pre-harvest sprouting resistance was the same, indicating that ‘Kyukei 50’ is suitable for sowing in both spring and summer. ‘Kyukei 50’ exhibits the ‘green flower type’ shattering resistance trait and, therefore, has a thick pedicel; breaking tensile strength is approximately two-fold stronger than that of ‘HITACHIAKISOBA’. The yield of ‘Kyukei 50’ is the same as that of ‘HITACHIAKISOBA’. In addition, the lowest seed height of ‘Kyukei 50’ was >17 cm. These results indicate that the ‘Kyukei 50’ is a promising breeding line for lodging resistance and loss of harvesting machinery.     

香菇完全亲和双-单杂交及其先导核的验证

选择香菇的野生株 （ Ｑ） 与栽培株苏香两种孢子单核体 （ Ａ１ Ｂ１, Ａ２ Ｂ２） 进行完全亲和双单杂交, 以拮抗试验辅以液体出菇试验初步鉴定双单杂交后代, 并以 Ｒ Ａ Ｐ Ｄ技术 （随机扩增的多态性 Ｄ Ｎ Ａ 技术） 对杂交后代进行检测。每个杂交组合只得到一个杂交后代, 说明在完全亲和双单杂交供体中存在先导核。运用原生质体单核化与交配型鉴定技术对杂交后代中来自供体的先导核进行了追踪研究。结果表明, 受体交配型不同时, 其先导核也不同。在 （ Ａ３ Ｂ３＋ Ａ４ Ｂ４） × Ａ１ Ｂ１双单杂交中先导核为 Ａ３ Ｂ３ 核, 在 （ Ａ３ Ｂ３＋ Ａ４ Ｂ４） × Ａ２ Ｂ２ 双单杂交中先导核为 Ａ４ Ｂ４ 核。     

热处理条件对真空包装甜玉米品质和储藏期影响的研究

研究了真空包装甜玉米加工过程中预热和杀菌条件对产品质量和储藏期的影响。结果表明,无论是预热还是杀菌阶段,高压热处理（１２０℃）都会使甜玉米的蔗糖含量显著下降,色泽变暗、变红。预热对甜玉米的品质影响最大,其次是杀菌。常压预热和杀菌的真空包装甜玉米在冷藏条件（４～６℃）下,其品质可在较长时间内（３～６个月）基本保持不变。     

针叶食叶害虫的无公害烟雾防治技术及效果分析

木兰林管局林业有害生物防治工作的重点是针叶食叶害虫。在近年森林食叶害虫防治工作中,林管局大力推行适合辖区林分特点的无公害烟雾防治技术。该技术在保证防治效果、维护生物多样性、保持林分抗性、促进森林健康方面起到了重要作用。对全局近年来针叶食叶害虫无公害烟雾防治工作的具体措施和防治效果进行了论述和分析。     

预切种甘蔗勺链式排种器设计与试验

针对目前预切种式甘蔗排种器普遍存在充种效果差、合格指数低等问题,设计了一种预切种甘蔗勺链式排种器。基于最速降线理论分析和待充蔗种的充种状态分析,阐明了最速降线可提高充种性能的原理;利用EDEM软件进行了单因素仿真试验,分析了不同种勺倾角和种勺数量对充种性能的影响。仿真结果表明,当种勺倾角为30°、种勺数量为15个时,充种性能较好;通过台架单因素试验,对种层高度调节装置和隔离板倾角进行了分析,为充种过程提供了有利条件。以作业速度、排种器倾角、种层高度为试验因素,以合格指数、漏充指数、重充指数为试验指标,进行二次回归旋转正交组合试验,分析了各试验因素交互作用对合格指数的影响。结果表明,当种层高度为360mm、作业速度为1.45~2.37km/h、排种器倾角为9.53°~15.15°时,排种器平均合格指数为95.33%,平均漏充指数和平均重充指数分别为3.11%、1.56%,满足甘蔗种植要求。     

Body weight,meat quality and blood metabolite responses to carbohydrate administration in the drinking water during pre‐slaughter feed withdrawal in broilers

This study was conducted to determine weights of body (BW), carcass (CW), gastrointestinal tract (GTW), meat quality and some blood metabolite responses to corn starch, saccharose or glucose administration in the drinking water during pre‐slaughter feed withdrawal (FW) in broilers. On day 42 of age, 200 broilers (Ross 308) were allocated randomly to five treatments with four replicates. During a 10‐h FW, control broilers (C) were provided with non‐treated water and the standard finisher diet ad libitum, whereas fasted broilers provided with non‐treated (NFW) or treated water, 3 g glucose (G), saccharose (S) or corn starch (CS)/L. Eight birds (four males and four females) per treatment were slaughtered. Birds receiving non‐treated or treated water had lower BW and higher carcass yield than the full‐fed broilers. The full‐fed broilers had higher absolute and relative GTW than the fasted birds. Broilers consumed more readily treated water compared with non‐treated water. While the a* value of breast meat from CS birds was higher than that from NFW, the b* value of that was higher than S and C birds. The c* values of breast meat from S birds were lower compared with that from the CS treatment. The thigh meat from NFW broilers had higher h* value than that from C and G broilers. The thigh meats of C and CS broilers had higher c* value than that of G birds. The full‐fed broilers had higher plasma triglyceride concentration than NFW, S and G birds. The full‐fed broilers had higher plasma uric acid and uric acid nitrogen concentrations than S birds. These results show that carbohydrate administration in the drinking water cannot be a good alternative for the FW period before slaughter due to the fact that the carbohydrates do not reduce BW losses and do not lead to increases in meat quality.     

Reduced Burden of Salmonella enterica in Bovine Subiliac Lymph Nodes Associated with Administration of a Direct‐fed Microbial

Despite effective food safety interventions within abattoirs, Salmonella enterica remains a common contaminant of raw ground beef. Research has recently implicated peripheral lymph nodes (PLNs) as a potential route by which Salmonella contaminates ground beef. This study examined the efficacy of using Lactobacillus animalis (formerly designated Lactobacillus acidophilus; NP51) and Propionibacterium freudenreichii (NP24), at 10⁹ cfu/head/day, as a direct‐fed microbial (DFM) in feedlot cattle diets to control Salmonella within PLNs. Two studies were conducted in which cattle were randomly allocated into either control or DFM treatment groups. Diets of treated cattle were supplemented with 10⁹ cfu/head/day of the DFM, while control groups received no DFM supplementation. During slaughter at abattoirs, one subiliac lymph node (SLN) per carcass was collected from 627 carcasses from one study and 99 carcasses from the second study. Lymph nodes were cultured to estimate the presence and concentration of Salmonella. In the first study, effects of DFM supplementation varied across slaughter days. On the first and second slaughter days, prevalence was reduced by 50% (P = 0.0072) and 31% (P = 0.0093), respectively. No significant difference was observed on slaughter day three (P = 0.1766). In the second study, Salmonella was 82% less likely (P = 0.008) to be recovered from SLNs of treatment cattle. While a greater relative risk reduction was observed in the latter study, absolute risk reductions were similar across studies. A significant reduction in the concentration of Salmonella in SLNs (P < 0.0001) on a cfu/g and cfu/node basis was also observed in cattle administered NP51 and NP24 in the first study; in the second study, too few quantifiable SLNs were observed to facilitate meaningful comparisons. The results indicate that NP51 and NP24 supplementation may aid in reducing the prevalence and concentration of Salmonella in SLNs and, therefore, serve as an effective control measure to reduce Salmonella in ground beef products.