Efficiency of bunch-planted and single-planted seedlings for selecting superior families in sugarcane

Summary The efficiency of family selection in bunch-planted sugareane seedlings was investigated by planting 40 families (20 proven and 20 experimental) as bunches and as single seedlings in adjoining replicated trials. A replicated trial planted the following year. using stem cuttings from random seedlings of each family. provided an independant estimate of the value of each family.Five methods were used to compare bunch and single planting, namely theoretical and realized gains from selection, correlations between the seedling and evaluation trials, discrimination based on proven cross classes, and discrimination based on production of advanced selections. Overall, bunch planting was inferior to single planting for family selection. It was promising for only one method of evaluation (proven cross classes) but this, combined with the relatively small area required for bunch-planted seedlings, indicates that family selection may be possible in such plantings. The use of a number of methods of evaluation showed that incorrect conclusions were likely if only one method were used, and revealed deficiencies in methods which would otherwise be considered satisfactory. The project provided a basis for the design of more critical experiments.The components of weight of cane, namely number of stalks and weight per stalk, are negatively correlated, and showed different relationships with yield in the seedling and evaluation trials. Weight per stalk was an important component in seedling trials, with number of stalks by far the main component in the evaluation trial which was planted by the commerical method using stem cuttings.Family selection based on number of stalks and sugar content, preceding mass selection, is likely to provide a better selection system than the usual mass selection in bunch-planted seedlings.Families do not express their full genetic potential in original seedlings. whether bunch or single planted: trials planted from stem cuttings give more effective family selection. Furthermore, family selection for the most important characters (net merit grade and weight of sugar) was much more effective in ratoon than in plant crops. These results have important implications for the practical selection program, further experimental work being necessary to specify the most efficient system.     

普通小麦体细胞无性系R2代变异发生特点

小麦Ｒ２代体细胞无性系变异存在４种发生方式，即合株性稳定谱异，全株分离变异，穗系嵌合稳定变异，穗系嵌合分离变异，其中稳定变异相当普遍、红占总变异的１／３。发生阶段较全株性变异于发生较迟的穗系嵌合变异。不同的变异性状有不同折发生方式。株型、穗型、芒型和叶色变异多为分离变异，熟期为稳定变异，株高，腊质等兼有稳定及分离变异，其中某性状是显性突变的结果，多数分离性状的分离均属简单分离，且箐少见到基因突变的     

中国粮食生产类家庭农场的适度经营规模研究

当前中国超小规模的农业生产方式导致农户农业收入低下,严重阻碍了农业的可持续发展,发展适度规模的家庭农场已是大势所趋。土地适度规模受到社会平均收入、粮食生产收益等多重因素的综合影响,是一个动态数值。该研究基于收入均等化测算法,以打工农户的收入水平为衡量标准,研究了中国地级市尺度的土地适度经营规模。研究表明,2016—2017年中国粮食类家庭农场的适度规模在13～14 hm~2左右,相当于全国户均耕地面积的30倍左右。依据各市农业适度经营规模,参考区域耕地资源禀赋、经营规模形成的难易程度将全国划分为9个一级大区、38个二级亚区。东北地区大区与内蒙古高原大区适度经营规模在15～17 hm~2范围,华北平原大区在10 hm~2左右,长江下游大区与东南沿海大区在7～9 hm~2范围,西南山地大区为6 hm~2,黄土高原大区为18 hm~2,西北干旱大区为25 hm~2,青藏高原大区的适度经营规模为全国最高,达到30 hm~2。从适度经营规模与户均耕地面积的比值来看,内蒙古高原大区为8倍,华北平原大区、长江下游平原大区为35倍左右。中国实现规模经营整体难度较大,区域上呈现从东南沿海向西北内陆难度依次降低的规律性带状分布。建议将适度经营规模标准提升至15～20倍范围,同时制度创新,消减高昂的土地流转交易成本。     

Bactrian camel (Camelus bactrianus) integrins αvβ3 and αvβ6 as FMDV receptors: Molecular cloning, sequence analysis and comparison with other species

Integrins are heterodimeric adhesion receptors that participate in a variety of cell–cell and cell–extracellular matrix protein interactions. Many integrins recognize RGD sequences displayed on extracellular matrix proteins and the exposed loops of viral capsid proteins. Four members of the αv integrin family of cellular receptors, αvβ3, αvβ6, αvβ1 and αvβ8, have been identified as receptors for foot-and-mouth disease virus (FMDV) in vitro, and integrins are believed to be the receptors used to target epithelial cells in the infected animals. To analyse the roles of the αv integrins from a susceptible species as viral receptors, we have cloned Bactrian camel αv, β3 and β6 integrin cDNAs and compared them to those of other species. The coding sequences for Bactrian camel integrin αv, β3 and β6 were found to be 3165, 2289 and 2367 nucleotides in length, encoding 1054, 762 and 788 amino acids, respectively. The Bactrian camel αv, β3 and β6 subunits share many structural features with homologues of other species, including the ligand binding domain and cysteine-rich region. Phylogenetic trees and similarity analyses showed the close relationships of integrin genes from Bactrian camels, pigs and cattle, which are each susceptible to FMDV infection, that were distinct from the orders Rodentia, Primates, Perissodactyla, Carnivora, Galliformes and Xenopus. We postulate that host tropism of FMDV may in part be related to the divergence in integrin subunits among different species.     

江苏省土地资源禀赋度空间变化研究

本文从土地数量、质量、结构和效益等方面构建了土地资源禀赋度评价指标体系,并采用多边形综合指标法对江苏全省各市县土地资源禀赋现状及空间变化进行了研究。结果表明:①江苏省土地资源禀赋度差异显著,呈现由南向北先递减后递增的规律,总体上苏南好于苏北好于苏中;②1996—2006十年间各市县土地资源禀赋度总体有所下降;③今后应根据区域特点,采取针对措施,提高区域土地资源禀赋度。     

饲料企业家族化管理弊端分析与应对策略

饲料行业作为国民经济发展中的重要一环,对解决就业、促进区域经济增长、推动产业结构优化调整等起到重要作用。回顾饲料行业的发展历程,由于过去饲料行业门槛较低且呈现明显的地域分布规律,以家族管理模式创立的饲料企业数量较多。家族化管理一定程度上提升了企业的凝聚性,且具有执行效率高、管理成本低等优势。但随着行业竞争的进一步加剧,企业管理模式越来越多样、职能分工越来越明细,家族化管理所暴露出来的问题和短板不容忽视,甚至成为了制约企业进一步发展的阻碍。本文以饲料企业家族化管理为研究对象,通过了解其创立的背景及成因,分析家族的弊端,最后提出相应的应对策略,以期为饲料行业发展提供理论指导。     

Oxidative stress drives divergent evolution of the glutathione peroxidase (GPX) gene family in mammals

The molecular basis for adaptations to extreme environments can now be understood by interrogating the ever-increasing number of sequenced genomes. Mammals such as cetaceans, bats, and highland species can protect themselves from oxidative stress, a disruption in the balance of reactive oxygen species, which results in oxidative injury and cell damage. Here, we consider the evolution of the glutathione peroxidase (GPX) family of antioxidant enzymes by interrogating publicly available genome data from 70 mammalian species from all major clades. We identified 8 GPX subclasses ubiquitous to all mammalian groups. Mammalian GPX gene families resolved into the GPX4/7/8 and GPX1/2/3/5/6 groups and are characterized by several instances of gene duplication and loss, indicating a dynamic process of gene birth and death in mammals. Seven of the eight GPX subfamilies (all but GPX7) were under positive selection, with the residues under selection located at or close to active sites or at the dimer interface. We also reveal evidence of a correlation between ecological niches (e.g. high oxidative stress) and the divergent selection and gene copy number of GPX subclasses. Notably, a convergent expansion of GPX1 was observed in several independent lineages of mammals under oxidative stress and may be important for avoiding oxidative damage. Collectively, this study suggests that the GPX gene family has shaped the adaption of mammals to stressful environments.     

青海省海北州麝香资源及其开发利用和发展前景

麝香是由鹿科动物马麝和林麝成熟雄体香囊中的分泌物干燥而成,为我国特产的名贵药材和世界四大名香之一。介绍了马麝和林麝的动物形态特征以及麝香的采集加工方法、商品质量与鉴别方法及产销情况,并展望了麝香的发展前景。     

大麦 PHT1基因家族的鉴定及表达特性分析

植物磷转运蛋白1(phosphase transporter protein 1，PHT1)家族在植物磷吸收和转运中发挥着重要作用。为研究大麦 PHT1基因家族成员的特性，利用生物信息学方法在全基因组范围内对大麦 PHT1家族成员进行鉴定，结果共鉴定到14个大麦 PHT1（ HvPT1～ HvPT14）基因，分布在2H、4H、5H和7H染色体上。根据系统发育关系、基因结构和保守蛋白基序，可将14个大麦 PHT1基因分为3个亚群。基于RNA seq数据对大麦品种GN121(磷高效基因型)根和叶片中12个 PHT1基因的表达模式进行分析，发现在低磷胁迫处理下，根中 HvPT1、 HvPT7、 HvPT10和 HvPT12基因以及叶片中 HvPT13基因均上调表达。进一步利用荧光定量PCR技术对大麦品种GN121和GN42（磷低效基因型）根中10个 PHT1基因的表达模式进行分析，发现两个品种根中 HvPT7、 HvPT8、 HvPT10、 HvPT12和 HvPT14基因在磷恢复后第3 d的表达量均显著低于低磷处理第22 d的表达量，推测这5个基因在低磷胁迫下参与磷的吸收和转运；此外 HvPT5基因在磷恢复后第3 d的GN42根中表达量显著下降，而在GN121根中的表达量显著上升，说明 HvPT5基因的表达与品种类型有关。     

农村养老服务机构中五保老人之增权介入刍议

养老机构是提供养老服务的重要载体,在老龄化加速的今天,加快和完善养老服务机构的发展,是适应人口老龄化和社会发展的客观要求,也是构建和谐社会的体现。以河南省荥阳市五保供养幸福园为例,结合我国农村养老服务机构的现状进行分析,从增权视角出发,分析增权在农村养老服务机构问题解决中的有效应用和实施可能性。