3S技术在有蹄类动物栖息地监测中的应用

3S技术是以遥感(RS)、地理信息系统(GIS)、全球定位系统(GPS)为基础,与其他高新技术有机地整合而形成一项新的有蹄类栖息地监测综合方法。全球定位系统(GPS)数据可以显著地提高RS识别地物的能力,为GIS提供数据源。应用地理信息系统(GIS)可以对有蹄类动物栖息地的状况进行评估,自动绘制有蹄类动物的分布图等。遥感(RS)是GIS数据库的数据源。3S技术在将来的野生动物栖息地监测研究中会有更大的发展潜力。     

Choice of shrinkage parameter and prediction of genomic breeding values in elite maize breeding populations

Genomic selection (GS) is a promising alternative to marker‐assisted selection particularly for quantitative traits. In this study, we examined the prediction accuracy of genomic breeding values by using ridge regression best linear unbiased prediction in combination with fivefold cross‐validation based on empirical data of a commercial maize breeding programme. The empirical data is composed of 930 testcross progenies derived from 11 segregating families evaluated at six environments for grain yield and grain moisture. Accuracy to predict genomic breeding values was affected by the choice of the shrinkage parameter λ², by unbalanced family size, by size of the training population and to a lower extent by the number of markers. Accuracy of genomic breeding values was high suggesting that the selection gain can be improved implementing GS in elite maize breeding programmes.     

Three Dimensional Numerical Investigation of the Influence of Basement Excavation on Underlying Tunnels

Rapid urban development in cities often requires construction activities close to existing tunnels, including basement excavation directly above the tunnels. Based on three dimensional finite element method, the influence of basement excavation on the underlying tunnels was studied. In the numerical model, A tunnel was located under a rectangular excavation with its axes parallel to the long side of the rectangle. The results of numerical analyses indicate that for the tunnel located underneath the centerline of the excavation, overlying excavation will cause the shortening of horizontal diameter and the lengthening of vertical diameter of the tunnel lining. For the tunnel located close to the diaphragm wall, maximum diameter changes often take place in a sub-vertical direction due to the rotation of the tunnel lining during excavation. The spatial effect of the excavation also has an obvious influence on the displacement and distortion of the tunnel cross section.     

Research on Mechanical Characteristics of the Cemented Sandstone Based on 3Dimensional PFC Numerical Model

Sandstone is sediment rock composed of many cemented sand particles, and corresponding particle constraint and force bearing capacity are greatly controlled by the cemented property. In order to better reflect the cemented property influencing on the mechanical characteristics of the sandstone, take the oil sandstone reservoir for instance, a numerical model based on 3Dimensional Particle Flow Code (PFC3D) considering the parallel bond model was brought forward to simulate the failure mechanism during shearing process. The sandstone cemented property is modeled based on random mathematics and advanced development of Particle Flow Code (PFC), and the relation of the stress ratio, volume strain, coordination number and bond-broken number and the axial strain is analyzed in detail, especially the contact network evolution indicated the force chain is important to transfer the external force, which verifies the feasibility of the numerical model. Based on the above PFC3D model, a series of researches on changing the cemented radius ratio, parallel bond stiffness and cemented volume of the particles have been done to clearly illuminate the importance of cemented property for the bearing capacity of the sandstone structure, which provides a scientific base for research on the failure mechanism of the sandstone under special conditions. Therefore, the above numerical method is more efficient and applicable for comparatively large scale and complex experiments, and the obtained research results can bring a new thought for the real cemented sandstone to research on its macro-micromechanical response and the structure failure mechanism, and also is significant for the sand production mechanism, sand volume prediction and sand control measures for the sandstone reservoir.     

Ultrastructure of Fusion Product between Protoplasts from C3 and C4 Species of Amaranthaceae

Summary

This paper describes the ultrastructure of the electric field-induced fusion products of C₃ and C₄ species of Amaranthaceae at the early developmental stage. Protoplasts of C₃ species were isolated from a Ceiosia cristata L. cell suspension and, those of C₄ species were isolated from an Amaranthus tricolor L. cotyledon. Incompatibility occurred in the C₃/C₄ hybrid. The incompatibility reactions were detected in the newly formed hybrid cells accompanied with significant changes in the nucleolus (segregation of nucleolar components) and plastids (cup-like shape or amoeboid plastid enclosing cytoplasmic materials) of C₃ species parent. The structural changes in the organelles of the C₄ partner were less marked. After 5 days of culture, most organelles showed high cellular activity, and a normal dedifferentiation process of mesophyll chloroplasts was observed. At this stage nucleolar segregation was not detected and the C₃ species plastids were difficult to distinguish from the proplastids formed from mesophyll chloroplasts. In addition, some mitochondria showed bursting-like structure. However, under the culture condition used these somatic incompatibility did not seem to impair further growth of fusion products since they were still proliferating well resulting in callus formation.     

Herbage intake by cattle on tarchonanthus veld in the Northern Cape as affected by stocking rate and grazing system 1

Abstract

In a trial with young Bonsmara cattle, four different stocking rates (10, 7, 6 and 4 ha/large stock unit) were applied in both a rotational and continuous grazing system. Feed intake was estimated during spring, summer, autumn and winter for four consecutive years starting in 1977.

Irrespective of the grazing system, feed intake declined with an increase in stocking rate. On average the highest intake was recorded in January and reached the lowest levels in October and July.

Livemass gain was found to be closely related to feed intake.     

NH4NO3浓度对吊兰叶片形态和生理生化指标的影响

采用沙培的方式,使用NH4NO3对幼苗进行5种不同的氮素浓度（1 mmol/L,5 mmol/L,10 mmol/L,15 mmol/L,20 mmol/L）处理,每1种处理方式重复5次.通过对吊兰叶片叶长、叶宽、叶绿素含量,可溶性蛋白含量,SOD活性等一系列指标的测定,优选出最适合吊兰生长的氮素浓度.结果表明：5 mmol/L处理的吊兰叶片,其叶片长度、宽度、叶绿素以及蛋白质含量和SOD,POD活性都明显高于其它浓度.     

Effects of Ω-3 (n-3) Fatty Acid Supplementation on Insulin Sensitivity in Horses

The objective of this study was to examine the effects of dietary ω-3 fatty acid supplementation on insulin sensitivity (SI) in horses. Twenty-one mares were blocked by age, body weight (BW), and body condition score (BCS) and randomly assigned to one of three dietary treatments. Treatments consisted of (1) 38 g of n-3 fatty acids via fish and algae supplement and diet (MARINE), (2) 38 g of n-3 fatty acids via a flaxseed meal from the supplement and diet (FLAX), and (3) control (CON) no supplemental fatty acid. Treatments were supplemented for 90 days. Frequent sampling intravenous glucose tolerance tests were performed on days 0, 30, 60, and 90. Blood samples were analyzed for glucose and insulin. The minimal model was applied for the glucose and insulin curves using MinMod Millennium. SI increased 39% (P < .007) across all treatment groups. Acute insulin response to glucose decreased 22% (P < .006) between days 30 and 60 and increased (P = .040) again at day 90. Disposition index (combined SI and β pancreatic response) increased (P = .03) by 53% in the MARINE- and 48% in the FLAX-supplemented horses and did not change with time in the CON group. In insulin-resistant mares, MARINE- and FLAX-treated horses had an increase in SI (P = .09). It would be interesting to test this supplement in a larger group of insulin-resistant horses. If proven effective, supplementation with ω-3 fatty acids would help to reduce problems associated with insulin resistance in horses.     

玉米赤霉烯酮中毒大鼠卵巢组织Caspase-3和Caspase-8的表达

10周龄SD大鼠单剂量腹腔注射5 mg/kg玉米赤霉烯酮玉米油溶液,分别于3、6、12、24、48、72、96 h时剖杀取卵巢组织,检测不同时间卵巢组织Caspase-3和Caspase-8的表达.病理组织学观察发现,卵巢组织出现不同程度损伤,卵泡颗粒细胞发生凋亡.免疫组织化学超敏PV法结果表明,试验组与对照组卵巢组织中均有Caspase-3和Caspase-8的表达,并且随着时间的推进呈现动态变化.Caspase-3和Caspase-8试验组表达量均高于对照组.试验组卵巢组织中Caspase-3在3～96 h时表达量均比较高,与对照组相比较差异显著(P＜0.05),且3、6、12、24、48 h的表达量均高于72 h和96 h的表达量.6、12、72、96 h卵巢组织中Caspase-8表达量与对照组相比较差异显著(P＜0.05),3、24、48 h时与对照组相比差异不显著(P＞0.05),且3、6、12、24、48 h的表达量均高于72 h和96 h的表达量.结果表明,大鼠玉米赤霉烯酮中毒可引起卵巢组织的病变及颗粒细胞凋亡,且Caspase-3和Caspase-8在玉米赤霉烯酮中毒大鼠卵巢颗粒细胞凋亡中起着重要作用,进一步证明本试验中死亡受体途径的激活可能参与凋亡的发生.Caspase-8表达量在个别时间段与对照组差异不显著还有待于进一步深入研究.