System analysis of frost resistance in winter wheat and its use in breeding

Morphophysiological and physicochemical parameters of sets of winter wheat genotypes were measured. High correlations were found between survival percentage of the winter wheat check variety under freezing and electroconductivity tests, stem electrical resistance after electric shock, and intensity of delayed leaf fluorescence at low temperatures. These correlations decreased when the number of varieties was increased to 35-100. Complex attribute of frost resistance was divided into large components using factor analysis. Biological interpretation was achieved for the first six components. Quantitative values for each component of frost resistance in the various genotypes were determined. The determination coefficient of multiple regression equations, where function was a level of frost resistance and arguments were the component's value for each genotype, varied from 0.80-0.94 over 10 years. It was proposed that the received equations might serve as a model for frost resistance and indicate which component of frost resistance determines the survival of plants in particular ecological conditions. The component structure concept of frost resistance is suggested and possible applications of this concept are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

延迟PCI对急性ST段抬高型心肌梗死预后的影响

目的探讨延迟PCI对急性ST段抬高型心肌梗死（STEMI）预后的影响.方法 563例STEMI患者分为直接PCI组157例、延迟PCI组124例、溶栓组131例和药物组151例.随访4~88个月,平均随访（45±27）个月;观察主要心脏不良事件（MACE）、超声心动图指标变化及QRS计分评估梗死范围的变化.结果延迟PCI组MACE发生率显著少于溶栓组和药物治疗组（P〈0.05）,与直接PCI组比较无统计学意义（P〉0.05）;延迟PCI组的LVEF显著高于非PCI治疗组（P〈0.05）,而延迟PCI组的LAD和LVDd均显著小于非PCI组;延迟PCI组的心肌梗死范围回缩率显著大于药物治疗组（P〈0.05）.结论延迟PCI可减少MACE发生率,并改善左室功能,使心肌梗死面积缩小,改善STEMI患者的预后.     

Lin28B基因表达与绵羊初情期启动的关系研究

初情期是家畜从不能繁殖到获得繁殖能力的标志,是雌性动物发育过程中的一个关键阶段。研究以性早熟的多浪羊和性晚熟的和田羊为研究对象,对其Lin28B基因外显子3进行克隆,采用Real-time PCR技术分析Lin28B基因在多浪羊和和田羊幼年期、初情期下丘脑、卵巢中表达变化,结果显示多浪羊和和田羊Lin28B基因外显子3序列相同,多浪羊下丘脑和卵巢中Lin28B基因mRNA表达量在初情期时低于幼年期(P0.05);和田羊卵巢Lin28B基因mRNA表达量在初情期时低于幼年期(P0.05)。研究结果表明,Lin28B基因表达下调与初情期启动呈正相关,该研究对于揭示Lin28B基因在绵羊初情期启动中的作用及机制提供了科学依据。     

Number of ovulations in culled Landrace × Yorkshire gilts in the tropics associated with age,body weight and growth rate

The objective of the present study was to determine the number of ovulations in culled Landrace × Yorkshire (LY) crossbred gilts in the tropics associated with age, body weight and growth rate. The genital organs from 316 gilts were examined for gross abnormalities, and those with normal cyclic ovaries (n=155, 307 ± 4.1 days of age, 148 ± 1.6 kg body weight) were included in the analyses. Number of ovulations was defined by a count of the corpora lutea (CL) from both ovaries. On average, the number of ovulations in LY gilts was 15.9 ± 0.3 (range 4 to 27). The number of ovulations correlated with the body weight (r=0.31, P<0.001) and growth rate (r=0.20, P=0.015) of the gilts, but not with their age (P>0.05). Gilts with a body weight of 141 to 150 kg (17.0 CL, n=31) ovulated more than those with a body weight ≤130 kg (14.1 CL, P=0.014, n=23). In conclusion, both the body weight and growth rate of the gilts were significantly correlated with the number of ovulations. The maximum number of ovulations was found in gilts at a body weight of above 141 kg.     

极低频高压脉冲电场对萌发绿豆干旱伤害的缓解作用

采用峰值场强为100 kV·m^-1、脉宽80 ms、脉冲频率为1 Hz的极低频高压脉冲电场（ELF-PEF）处理-0.1 MPa的PEG-6000溶液中萌发的绿豆种子,研究了绿豆在萌发过程中鲜重、自发发光、延迟发光、丙二醛（MDA）含量和超氧化物歧化酶（SOD）活性的变化。结果表明,ELF-PEF对PEG胁迫下萌发的绿豆鲜重、自发发光和延迟发光积分强度促进作用分别达到了28.58%、78.35%和40.6%,说明ELF-PEF可以有效促进绿豆种子萌发过程中的生理代谢,缓解干旱胁迫对细胞的伤害作用。ELF-PEF通过提高PEG胁迫下萌发绿豆中SOD活性,降低MDA含量,缓解干旱胁迫对萌发绿豆的氧化损伤,ELF-PEF对细胞毛细吸水和代谢吸水的促进可能是其缓解干旱伤害的原因。     

Growth performance and puberty attainment in growing pigs fed dietary fumonisin B1

Twenty‐four male weaned piglets assigned to four diets containing 5.0, 10.0, 15.0 and 0.2 mg fumonisin B₁ (FB₁) /kg as diets 1, 2, 3 and control diet, respectively, were used to study the effect of dietary FB₁ on growth and puberty attainment in pigs in a 6‐month feeding trial. Lower feed intake during 0–4 months and a non‐significant (p > 0.05) but FB₁ concentration‐dependent decrease in live and DWGs in animals fed FB₁‐contaminated diets was observed at the end of the pubertal phase. The daily and the final live weight gains of animals fed diet 3 were 75.8% and 90.6%, respectively, of the control values. The mean ages at puberty by boars on diets 2 and 3 were significantly (p < 0.05) higher than those for animals on the control and diet 1. The animals on diet 3 attained puberty when mean live weight was 60.1 kg, some 30.3 days after the controls attained puberty, at 156.3 days, when the mean live weight was 46.9 kg. This study revealed that dietary FB₁ delays sexual maturity in growing pigs. Male weanling pigs for breeding should not be exposed to dietary FB₁ higher than 5 mg/kg for optimum growth and reproductive performance.     

A synthesis of the coast‐wide decline in survival of West Coast Chinook Salmon (Oncorhynchus tshawytscha,Salmonidae)

We collated smolt‐to‐adult return rate (SAR) data for Chinook salmon from all available regions of the Pacific coast of North America to examine the large‐scale patterns of salmon survival. For consistency, our analyses primarily used coded wire tag‐based (CWT) SAR estimates. Survival collapsed over the past half century by roughly a factor of three to ca. 1% for many regions. Within the Columbia River, the SARs of Snake River populations, often singled out as exemplars of poor survival, are unexceptional and in fact higher than estimates reported from many other regions of the west coast lacking dams. Given the seemingly congruent decline in SARs to similar levels, the notion that contemporary survival is driven primarily by broader oceanic factors rather than local factors should be considered. Ambitious Columbia River rebuilding targets may be unachievable because other regions with nearly pristine freshwater conditions, such as SE Alaska and northern BC, also largely fail to reach these levels. Passive integrated transponder (PIT) tag‐based SAR estimates available for Columbia River Basin populations are generally consistent with CWT findings; however, PIT tag‐based SARs are not adjusted for harvest which compromises their intended use because harvest rates are large and variable. More attention is needed on how SARs should be quantified and how rebuilding targets are defined. We call for a systematic review by funding agencies to assess consistency and comparability of the SAR data generated and to further assess the implications of survival falling to similar levels in most regions of the west coast.     

西葫芦秋延迟无公害栽培技术

西葫芦因其营养丰富,风味独特,在这里介绍一下利用大棚进行西葫芦秋延迟栽培,经济效益明显.     

气象条件与水稻产量的丰欠

对2002年夏季(6-8月)整季低温多雨,所引起的延迟型、障碍型等灾害对水稻减产的影响,并用实例对原因和结果进行分析。     

NaCl胁迫下玉米种子萌发过程中超弱光子辐射的变化

为了揭示盐胁迫下萌发种子超弱光子辐射的生物学意义,研究了NaCl胁迫下萌发玉米种子超弱光子辐射的变化规律。结果表明,在对照组的玉米种子萌发过程中,种子鲜质量和自发光子辐射逐渐增长,种子鲜质量和自发光子辐射的变化呈现正相关(相关系数r为0.9614);在50、100和150mmol/L的NaCl胁迫下萌发的玉米种子鲜质量与自发光子辐射也呈现正相关(相关系数r分别为0.9582、0.9406和0.9389),NaCl胁迫对萌发过程中种子鲜质量和自发光子辐射的增长都有抑制作用,NaCl浓度越大,抑制作用越强。研究还发现,NaCl胁迫会导致萌发过程中玉米种子延迟光子辐射中的初始光子数、相干时间和积分强度变小,并且呈现出强度效应。研究结果为揭示盐胁迫下萌发种子超弱光子辐射的生物学意义,开发基于作物耐盐性评价和种质资源鉴定等方面的活体无损检测新技术提供参考。