Substitution mapping and characterization of brown planthopper resistance genes from indica rice variety, ‘PTB33’ (Oryza sativa L.)

Rice (Oryza sativa L.) yield is severely reduced by the brown planthopper (BPH), Nilaparvata lugens Stål, in Asian countries. Increasing resistance in rice against BPH can mitigate yield loss. Previous reports indicated the presence of three BPH resistance genes, BPH2, BPH17-ptb, and BPH32, in durable resistant indica rice cultivar ‘PTB33’. However, several important questions remain unclear; the genetic locations of BPH resistance genes on rice chromosomes and how these genes confer resistance, especially with relationship to three major categories of resistance mechanisms; antibiosis, antixenosis or tolerance. In this study, locations of BPH2, BPH17-ptb, and BPH32 were delimited using chromosome segment substitution lines derived from crosses between ‘Taichung 65’ and near-isogenic lines for BPH2 (BPH2-NIL), BPH17-ptb (BPH17-ptb-NIL), and BPH32 (BPH32-NIL). BPH2 was delimited as approximately 247.5 kbp between RM28449 and ID-161-2 on chromosome 12. BPH17-ptb and BPH32 were located between RM1305 and RM6156 on chromosome 4 and RM508 and RM19341 on chromosome 6, respectively. The antibiosis, antixenosis, and tolerance were estimated by several tests using BPH2-NIL, BPH17-ptb-NIL, and BPH32-NIL. BPH2 and BPH17-ptb showed resistance to antibiosis and antixenosis, while BPH17-ptb and BPH32 showed tolerance. These results contribute to the development of durable BPH resistance lines using three resistance genes from ‘PTB33’.     

培养基和植物生长调节剂对青钱柳悬浮细胞三萜产量的影响

探讨培养基种类和植物生长调节剂配比对青钱柳悬浮细胞生长、总三萜和三萜单体含量及产量的影响。结果表明：MS＋1．0 mg／L NAA＋0．5 mg／L KT最适合青钱柳悬浮细胞生长,最终产量达到12．03 g／L;WPM＋0．5 mg／L 2,4－D ＋0．3 mg／L NAA显著提高了青钱柳悬浮细胞中总三萜的含量;青钱柳悬浮细胞中均能检出阿江榄仁酸、青钱柳酸B、齐墩果酸和熊果酸的存在,且阿江榄仁酸和青钱柳酸B含量较高,但基本培养基种类和不同植物生长调节剂组合对悬浮细胞中4种三萜单体含量无显著影响。青钱柳悬浮细胞中总三萜产量以MS＋0．5 mg／L 2,4－D＋0．3 mg／L NAA处理最高,而三萜单体产量均以MS＋1．0 mg／L NAA＋0．5 mg／L KT处理最高。     

Variation in the immune status of two Australian pig breeds

Objective To investigate the variation in immune competence of two Australian pig breeds.
Design A panel of immune tests were used to assess breed and sire differences in weaner piglets of Large White and Duroc breeds.
Procedure All piglets were immunised against porcine leptospirosis. Blood samples were taken for studies on lymphocyte phenotypes, mitogenic responses of blood cells and serological analysis.
Results Significantly larger blood leucocyte numbers were found in Large White piglets compared with Duroc piglets after vaccinations. No significant difference in concanavalin A induced blood cell proliferation was found between these two breeds before or after vaccinations. Some significant breed variation in blood lymphocyte phenotypes was found. While the age-related changes of lymphocyte phenotypes were similar for the two breeds, the Large White breed had significantly larger numbers of CD2+ and CD4+ cells than the Duroc breed after the two vaccinations. There were also significant sire effects on CD8+ cells within the Large White breed after the first vaccination. No significant breed difference was detectable in serum IgG concentrations but sire differences within each breed before the primary vaccination were found. The serum antibody response to vaccination against leptospirosis was generally small, and showed no variations due to either breed or sire. No gender effects were found during the entire study.
Conclusion The study demonstrated significant differences in some important immune components of the pig breeds studied. This may in turn indicate the variation in their immune competence or disease resistance. However, further investigation into the heritability and correlation with specific immune responses is required.     

不同基因型和营养对山羊生长性能、胴体品质及肉质的影响

【目的】探讨不同基因型和营养物质在改善老挝山羊的生长性能、胴体特征和肉质中的效果。【方法】采用2×2双因素试验,以本地山羊品种Lat为对照,对Lat与越南Bach Thao公山羊的杂交F1（BT×L）进行比较。从每个基因型中选择30头7月龄的成长公山羊并分成两组,其中一组采用传统饲喂方法即自由放牧,另一组采用改良饲喂方法,即放牧并任意采食木薯渣和矿物砖。试验期间测量山羊平均日增重（ADG）,在后期每组选择3只山羊宰杀并测定胴体特性（胴体组成和初分切肉）、肉质（剪切力、肉色、pH、滴水损失率和蒸煮损失率）。【结果】杂交山羊F1的平均日增重（60．02g／头）明显高于本地山羊（38．45g／头）,增幅为56．09％;饲喂补充木薯渣和矿物砖的山羊平均日增重（55．45g／头）则显著高于未添加对照组（43．02g,头）,增幅为28．89％。杂交繁育和饲喂补充物对山羊胴体品质如屠宰率、前肢百分率、后肢百分率及胸肌率没有显著影响,但杂交F1山羊的脖子极显著大于本地山羊,而其腰腹部切口极显著小于本地山羊。在两种不同饲喂管理条件下,Lat和杂交F1山羊的肉质特性没有显著差异。【结论】老挝本地山羊Lat与Bach Thao公山羊杂交及在饲料中补充木薯渣和矿物砖,可提高山羊肉产量且对其肉质无任何负作用。     

Population dynamics of shrimps in littoral marine waters of the Mekong Delta, south of Viet Nam

The population dynamics of eight commercial species of shrimp (Haliporoides sibogae, Harpiosquilla harpax, Metapenaeus affinis, Metapenaeus brevicornis, Metapenaeus tenuipes, Parapenaeopsis cultrirostris, Parapenaeopsis gracillima and Parapenaeus maxilipedo) distributed in littoral marine zone of the Mekong Delta were investigated. Length-based stock assessment using FiSAT II software package was used to assess the growth and mortality parameters: Asymptotic size (L8), growth coefficient (K), total (Z) and natural (M) mortality, exploitation rate (E), recruitment pattern, current probability of capture and selectivity of fishing gears. Yield-per-recruit analyses were carried out showing different levels of the exploitation. Results showed that the maximum sustainable yield would be reached for an exploitation rate higher than the current one for each population. However, the size of first capture should be increased for every population. The findings indicated that the current exploitations of shrimp populations distributed in littoral marine zone of the Mekong Delta are under exploitation level for maximum sustainable yield; however, all the shrimp populations are subject to growth over-exploitation.     

Drying and rewetting of forest floors: dynamics of soluble phosphorus,microbial biomass-phosphorus,and the composition of microbial communities

Drying and rewetting (D/W) of soils often leads to a pulse of total dissolved phosphorus (TDP) by lysis of sensitive microorganisms. The relevance of D/W on the P cycle in ecosystems depends on the duration of the TDP release. In forest soils, the forest floor represents a hotspot of microbial activity and is often prone to D/W. Here, we investigated the dynamics of TDP, the microbial P pool (Pmic), and the composition of microbial communities after D/W. Samples were taken from Oi and Oe layers of a European beech and a Norway spruce site and desiccated up to ??100 MPa (pF 6) at 20 °C, while controls were kept moist. TDP and Pmic were measured 0, 1, 3, 7, and 14 days after rewetting and the composition of microbial communities was analyzed by automated ribosomal intergenic spacer analysis after 14 days. After D/W, the largest TDP net release (D/W-control) was from Oe layers with 40–50 mg P kg^?1 and inorganic P as the dominant fraction. The TDP concentrations decreased strongly in Oi layers within 1 (beech) to 4 (spruce) days, while remaining stable in Oe layers. The TDP dynamics were linked to the decrease and recovery of Pmic after D/W. Pmic dynamics differed between layers and stand types, suggesting the influence of microbial communities with different D/W sensitivities. The composition of microbial communities varied strongly among sites and layers, while D/W only affected the composition of bacterial and fungal communities in the spruce Oe layer. D/W of forest floors increases the plant available P and affects the P cycle in forest ecosystems.     

Stiffness of normal, opposite, and tension poplar wood determined using micro-samples in the three material directions

Mechanical tests on micro-samples were performed in the three material directions in normal, opposite, and tension wood collected from a poplar tree. Two custom micro-devices were designed and built in the laboratory to test samples under pure tension in the transverse direction and under 4-point bending conditions in the longitudinal direction. Both devices were designed to handle samples with a small transverse section (a few square mm), which allowed to select zones with homogenous anatomical features. The results indicate a very high longitudinal stiffness in tension wood (up to 35 GPa compared to an average of 18 GPa for normal wood). Considering wood density, the value represents a specific modulus that is nearly 70 % crystalline cellulose. However, tension wood is slightly less stiff in the tangential and radial directions (1,150 vs. 1,500 MPa for normal wood in the radial direction and 430 vs. 530 MPa in the tangential direction).