数量性状位点的相对选择效率

从理论上采用蒙特卡罗（Monte Carlo）模拟的方法研究了不同遗传力条件下数量性状位点的直接选择（DSQ）和以表型为基础的选择（TBS）在10个不重叠世代中的选择反应以及DSQ相对于TBS的优势。结果表明，在10个世代中DSQ的选择进展在几乎总是大于TBS的选择进展，说明DSQ较TBS具有优越性；但DSQ的相对选择效率（RSE）会随着世代数的增加而呈现较迅速下降的趋势，单个性状情况下RSE则呈直线下降的趋势。随着选择代数的增加，DSQ将失去其优越性，TBS在遗传进展上将超过DSQ。     

主效基因位点的相对选择效率

利用单个已识别主效基因位点加微效多基因的混合遗传模型,在二性状育种目标下探讨基因型选择[Direct Selection of Quantitative Trait Loci(QTL),DSQ]的相对选择效率(Relative Selection Efficiency,RSE),并考察主效基因方差贡献、性状遗传力和遗传相关对RSE的影响,以期找出控制RSE实际应用中的主要影响因素,并最大限度地发挥已识别主效QTL位点在育种中的作用。结果表明,只要主效基因位点的信息合理纳入选择方案,即可从选择方案中主效基因位点的应用中获得较大益处;从RSE来看,DSQ可带来额外程度不同的选择进展;几个因素对RSE的影响程度各不相同,使RSE增长或降低模式彼此不同;主效基因位点的加性遗传方差比例、遗传力和遗传相关对RSE均有较大影响。     

数字

正20.25亿亩8月10日上午,从国土资源部召开的2015年度全国土地变更调查新闻发布会上了解到,截至2015年年底,全国31个省(区、市)耕地面积继续维持在20.25亿亩,与2014年底相比,耕地净减少89.2万亩,建设用地净增加713.5万亩,较上年皆呈下降趋势。     

云南都龙锡锌多金属矿床矽卡岩矿物学和矿物化学特征及其地质意义

都龙锡锌多金属矿床位于华夏地块西缘,是中国最大的锡石硫化物矿床之一。矿体主要呈层状、似层状产于晚白垩纪花岗岩体上覆新元古代新寨岩组的矽卡岩带内。矽卡岩蚀变矿化可划分为5个阶段:石榴子石-辉石阶段、阳起石-绿泥石阶段、磁铁矿-锡石阶段、锡石-磁黄铁矿-闪锌矿阶段、闪锌矿-黄铜矿阶段。以都龙矿床中的矽卡岩为研究对象,在识别矿物组合与结构的基础上,采用电子探针与LA-ICP-MS技术对矽卡岩中的石榴子石、辉石进行了主量、微量元素分析。结果表明:都龙矿床矽卡岩中的石榴子石可分为3类,且具有一定的世代特征。GrtⅠ世代为早阶段形成的钙铁榴石(And_(95～99)Gr_(1～5)),多位于核部,呈残余状,与透辉石共生;GrtⅡ世代为形成时间稍晚的钙铁-钙铝榴石(And_(50～80)Gr_(20～50)),多围绕GrtⅠ世代形成,与钙铁辉石共生;GrtⅢ世代为最晚阶段形成的细粒钙铝榴石(And_(30～40)Gr_(60～70)),量少,多呈不规则状。石榴子石与辉石的矿物组合变化暗示流体氧化性具有逐渐降低趋势。微量元素特征显示GrtⅠ世代呈轻稀土元素富集、重稀土元素亏损的右倾型特征,GrtⅡ世代呈重稀土元素富集、轻稀土元素亏损的左倾型特征,表明稀土元素分配可能受石榴子石晶体化学结构和固溶体端元组分共同影响。不同世代石榴子石成矿元素In和Sn含量差异也较大。GrtⅠ世代In和Sn含量分别为(63.0～264.0)×10~(-6)(平均值为159.0×10~(-6))和(2 790～13 100)×10~(-6)(平均值为7 441×10~(-6));GrtⅡ世代In和Sn含量分别为(1.6～81.0)×10~(-6)(平均值为20.0×10~(-6))和(436～4 740)×10~(-6)(平均值为2 518×10~(-6))。石榴子石中In与Sn含量的正相关关系暗示了两者的同时性、同源性,并且在矽卡岩形成早期已经具有一定的选择性富集趋势。因此,系统地研究矽卡岩中的矿物化学特征对有效约束成矿流体在矽卡岩蚀变与矿化过程的演化具有重要意义。     

氨氮胁迫对马氏珠母贝免疫活性的影响

在实验室条件下探讨氨氮胁迫对马氏珠母贝(Pinctada martensii)血细胞密度、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、溶菌酶(LSZ)、酸性磷酸酶(ACP)活性的影响。结果表明:1)不同浓度氨氮(1.25~40 mg/L)胁迫3 d后,马氏珠母贝血细胞密度随氨氮浓度的增加呈下降趋势,当氨氮浓度超过5 mg/L时血细胞密度较对照组明显下降,差异极显著(P<0.01);2)血清SOD活性随实验氨氮浓度(1.25~40 mg/L)的增加而明显下降,在较低氨氮浓度(1.25~5 mg/L)时,SOD活性高于对照组,氨氮浓度超过10 mg/L时,SOD活性低于对照组,各实验组SOD活性与对照组均存在极显著差异(P<0.01);3)当氨氮浓度为1.25~20 mg/L时,马氏珠母贝血清CAT活性随氨氮浓度的增加而升高,除氨氮1.25 mg/L组外,其余各实验组血清CAT活性较对照组极显著升高(P<0.01),当氨氮浓度为30~40 mg/L时,血清CAT活性呈急剧下降趋势,且低于对照组(P<0.01);4)马氏珠母贝血清LSZ活性随实验氨氮浓度的增加而降低,当氨氮浓度为10 mg/L以下时,血清LSZ活性高于对照组,当氨氮浓度为20 mg/L以上时,血清LSZ活性较对照组极显著降低(P<0.01);5)氨氮浓度为1.25~10 mg/L时,马氏珠母贝血清ACP活性随氨氮浓度的增加而升高,且高于对照组(P<0.01),当氨氮浓度超高20 mg/L时,马氏珠母贝血清ACP活性随氨氮浓度的增加急剧降低,且低于对照组(P<0.01)。     

南方山地丘陵土地利用类型的地形影响GIS分析——以江西省为例

分布广泛的山地丘陵,地形复杂多样,生态环境脆弱,不合理的土地利用方式会造成生态环境的破坏,导致严重的水土流失。分析山地丘陵区土地利用的地形控制机制,对于山地丘陵区土地利用开发与水土保持等生态保护之间权衡提供科学依据而具有重要现实意义。因此,本文以南方山地丘陵分布较广泛的江西省为例,在SRTM数字高程模型(DEM)的支持下,利用中国资源环境数据中心基于Landsat遥感解译的2000年土地利用数据,分析了江西省土地利用结构与高程、坡度和坡向等地形因子的关系。结果表明地形因子是影响江西省土地利用方式的一个重要因素,具体表现在:(1)随着高程和坡度的增加,耕地面积及占土地总面积的比例都呈下降趋势,南坡耕地面积和比例都大于北坡的耕地面积和比例;(2)在低海拔区,林地面积占土地总面积比例随着海拔高程的增加而增加,当海拔高于400米时,基本稳定;(3)居民点和工矿用地受高程和坡度的影响较大,受坡向影响较小;(4)草地的面积随着海拔的增加呈下降趋势,但其面积比随着高程增加呈缓慢增加,受坡度和坡向的影响较小。     

坝基岩体岩石质量指标、波速和透水率的关系——以青海玛沁地区玛尔挡水电站为例

坝基岩体质量分级指标包括岩石质量指标(RQD,Q)、纵波波速(V)以及透水率(ω)等。他们相互之间存在一定关系,并随深度(h)的变化而变化。以青海玛沁地区玛尔挡水电站河床坝基6个钻孔的实测数据为基础,对上述指标随深度的变化规律及相互关系进行研究。结果表明:同一深度的岩石质量指标差异较大,但整体上随深度的增加呈线性带状增大,上、下限的线性关系分别为Q=0.488h+67.886与Q=0.309h+2.319;透水率与深度具有较好的相关性,随深度增大,透水率呈幂函数曲线下降趋势,即ω=1 329.192h-1.599;岩石质量指标、透水率和深度的拟合度较高;随着岩石质量指标的增加,纵波波速整体上呈线性带状增大的趋势,上、下限的线性关系分别为V=40.493Q+3 612.9和V=32.458Q+1 822.6,而透水率的几何平均值呈下降趋势,与岩石质量指标的算术平均值具有很好的相关性,即ω=6.378-3.708×10~(-7) Q~(3.832)。     

猪雌激素受体(ESR)基因的多态性分析

母猪的产仔数是一个重要的经济性状 ,产仔数的提高将大大增加肉猪的产量 ,给养猪业带来巨大的经济效益 ,因此 ,有效地提高猪的产仔数一直是猪育种的主要目标之一。由于猪产仔数的遗传力很低 (约为 0 .1 ) ,并且要等到母猪产仔后才能度量 ,这种传统的选育方法其育种周期长、遗传进展小 ,因此开发和利用新的选育标记来提高猪的繁殖性就倍受重视。随着现代分子生物学和分子遗传学的发展 ,使得寻找多仔基因的遗传标记和标记辅助选择(Ｍａｒｋｅｒａｓｓｉｓｔｅｄｓｅｌｅｃｔｉｏｎ ,ＭＡＳ)成为可能。 1 994年Ｒｏｔｈｓｃｈｉｌｄ通过候选基…     

基于信阳台水管倾斜观测的载荷干扰分析

分析信阳地震台水管倾斜(DSQ)观测的3次异常后认为,距离为700 m、载荷变化量为50 000 t左右的干扰源对DSQ数据造成约300 ms的干扰变化。当干扰源距离DSQ减小到100 m、载荷变化只有11 000 t时,也产生了同样幅度的变化,干扰源距离和载荷之间呈现出定量化的反相关。由于台站山洞不均匀被覆,降雨时土壤吸收雨水使山体载荷发生变化,成为影响DSQ工作的最主要干扰类型。     

青藏高原东部土壤湿度变化及其与中国降水的关系

为进一步了解高原土壤湿度变化及其与中国降水的关系,利用青藏高原东部地区1991~2012年22个站10cm、20cm、50cm 3个层次的土壤相对湿度观测资料,分析高原东部地区土壤湿度的时空分布特征。同时利用全国1992~2012年的降水资料与1992~2011年的土壤相对湿度资料,采用求相关系数的方法分析高原东部土壤湿度与全国降水的关系。结果表明:(1)西藏东部土壤相对湿度由东至西呈递减趋势。(2)10cm土层较干,20cm土层的相对湿度是3层中最大的,50cm土壤的湿度变化较为平缓;表层土壤湿度变化较明显。21年来,各层土壤湿度呈不明显下降趋势。(3)高原东部地区土壤湿度与中国东部降水有显著关系,若东部高原春季土壤湿度偏湿(干),则江淮流域夏季降水偏少(多)。     

Selection for growth performance of tank-reared Pacific white shrimp, Litopenaeus vannamei

Seven growth-related traits were measured to assess the selection response and genetic parameters of the growth of Pacific white shrimp, Litopenaeus vannamei, which had been domesticated in tanks for more than four generations. Phenotypic and genetic parameters were evaluated and fitted to an animal model. Realized response was measured from the difference between the mean growth rates of selected and control families. Realized heritability was determined from the ratio of the selection responses and selection differentials. The animal model heritability estimate over generations was 0.44±0.09 for body weight (BW), and ranged from 0.21±0.08 to 0.37±0.06 for size traits. Genetic correlations of phenotypic traits were more variable (0.51–0.97), although correlations among various traits were high (>0.83). Across generations, BW and size traits increased, while selection response and heritability gradually decreased. Selection responses were 12.28%-23.35% for harvest weight and 3.58%–13.53% for size traits. Heritability estimates ranged from 0.34±0.09 to 0.48±0.15 for harvest weight and 0.17±0.01–0.38±0.11 for size traits. All phenotypic and genetic parameters differed between various treatments. To conclude, the results demonstrated a potential for mass selection of growth traits in L. vannamei. A breeding scheme could use this information to integrate the effectiveness constituent traits into an index to achieve genetic progress.     

大口黑鲈选育群体遗传结构的微卫星分析

采用微卫星标记技术分析不同世代大口黑鲈选育群体的遗传结构。利用11对微卫星引物对大口黑鲈第2～4代选育群体及南水群体(对照)共120个个体进行PCR扩增,共得到28个等位基因。每个位点获得2～3个等位基因,平均等位基因为2.54。第2代(F_2)、第3代(F_3)、第4代(F_4)及南水群体(CG)的平均多态信息含量(PIC)值分别为:0.423、0.419、0.386、0.366。与F_2相比,F_4的遗传多样性减少8.76%,但与CG相比,F_4仍具有较高的遗传多样性,表明大口黑鲈选育群体的遗传基础逐步趋向纯化,且仍有较大选育潜力。此外,尽管F_2与F_4的遗传距离(0.022)比F_2与F_3的(0.011)大,但世代间的F_(st)值(0.006～0.009)均小于0.05,且世代群体总遗传分化指数为0.013,表明选育群体已出现遗传分化,但分化程度较低。     

Growth performance of larval and juvenile manila clam (<Emphasis Type="Italic">Ruditapes philippinarum</Emphasis>) from divergently selected individuals of a full-sib family

In this study, the method of divergent selection was employed to test the larval and juvenile growth performance within a full-sib family of Manila clam Ruditapes philippinarum. The 10% largest and 10% smallest clam individuals (on the basis of shell length) of a full-sib family were selected as parents for the fast and slow growing lines, respectively. The difference in shell length was significant among the three lines (fast, control, and slow) tested. The sequence of shell length were fast line > control line > slow line. The responses to selection, realized heritability, and genetic gain were 0.06%–0.81%, 0.04%–0.47% and 0.58%–18.89% in the fast direction, respectively; and were 0.14%–1.27%, 0.08%–0.73%, and 0.31%–49.03% in the slow direction, respectively. The results suggested that there was a large portion of additive genetic variance affecting the growth in the full-sib family. Selection in the fast direction within the full-sib family would greatly improve the growth of R. philippinarum.     

Mass Selection for Fast Growth in the Third Generation of the Orange Line of the Manila Clam Ruditapes philippinarum

The Manila clam Ruditapes philippinarum is natively distributed along the Pacific coast of Asia, where it is one of the most important bivalve species for local fisheries. This species has been intentionally introduced due to its high adaptability to various coastal environments and is currently widely cultivated in Europe and North America. We have initiated a selective breeding program to improve the growth rate of the Manila clam since 2007, and a full-sib family with orange shell color was selected. This family features high survival but slow growth. Thereafter, two generations of mass selection were conducted in this family by 10% upward selection for faster growth. In 2011, three types of lines were produced by selecting the breeder from the second-generation of selected lines. These lines are SS(subject to three generations of selection for growth in shell length), SC(selected for the second but not the third generation), and C(randomly sampled individuals from the national population). The genetic parameters of the shell length including hR2(realized heritability), SR(selection response), and GG(genetic gain) were analyzed. Results showed that the shell length of the SS line was significantly larger than those of the SC and C lines at all developmental stages(P 0.05). For the larval stage, the values of hR2, SR, and GG were 0.42, 0.73, and 6.66, respectively. For the juvenile stage, the values of hR2, SR, and GG were 0.40, 0.69, 21.76, respectively. For grow-out stage, the values of hR2, SR, and GG were 0.48, 0.83, and 18.22, respectively. The results of hR2 indicated the good potential of the SS line in selective breeding. The level of GG improvement was encouraging and consistent with the previous expectations. No inbreeding depressions in the shell length were observed in the SS and SC lines at all sampling days. All of the results indicate that maintaining selection pressure in successive generations may be effective in the selective breeding program of this family.     

MSE准则下岭-主成分组合估计与LS估计的比较与选择

研究了测量平差Gauss—Markov模型中岭-主成分组合估计与LS估计的比较与选择问题。首先在均方误差（MSE）准则下对岭-主成分组合估计与LS估计进行了比较,得到了岭-主成分组合估计优于LS估计的椭球条件;然后运用Monte Carlo方法对这些条件进行了假设检验;最后通过数值实验说明,在一定显著性水平下当原假设被接受时,可采用岭-主成分组合估计对LS估计做出比较有效的改进,当原假设被拒绝时,应该仍采用LS估计。     

Genetic variation assessed with microsatellites in mass selection lines of the Pacific oyster (<Emphasis Type="Italic">Crassostrea gigas</Emphasis>) in China

Four successive mass selection lines of the Pacific oyster, Crassostrea gigas, selected for faster growth in breeding programs in China were examined at ten polymorphic microsatellite loci to assess the level of allelic diversity and estimate the effective population size. These data were compared with those of their base population. The results showed that the genetic variation of the four generations were maintained at high levels with an average allelic richness of 18.8–20.6, and a mean expected heterozygosity of 0.902–0.921. They were not reduced compared with those of their base population. Estimated effective population sizes based on temporal variances in microsatellite frequencies were smaller to that of sex ratio-corrected broodstock count estimates. Using a relatively large number of broodstock and keeping an equal sex ratio in the broodstock each generation may have contributed to retaining the original genetic diversity and maintaining relatively large effective population size. The results obtained in this study showed that the genetic variation was not affected greatly by mass selection progress and high genetic variation still existed in the mass selection lines, suggesting that there is still potential for increasing the gains in future generations of C. gigas. The present study provided important information for future genetic improvement by selective breeding, and for the design of suitable management guidelines for genetic breeding of C. gigas.     

Effects of rice straw on the cell viability,photosynthesis, and growth of Microcystis aeruginosa

Rice straw is supposed to be an environment-friendly biomaterial for inhibiting the growth of harmful blooms of the cyanobacterium Microcystis aeruginosa. However, its potential mechanism is not well known. To explore this mechanism, the growth, cell viability （esterase activity, membrane potential, and membrane integrity）, photosynthesis, and cell size ofM. aeruginosa were determined using flow cytometry and Phyto-PAM after exposure to rice straw extracts （RSE）. The results show that doses from 2.0 to 10.0 g/L of RSE efficiently inhibited the alga for 15 days, while the physiologic and morphologic responses of the cyanobacteria were time-dependent. RSE interfered with the cell membrane potential, cell size, and in vivo chlorophyll-a fluorescence on the first day. After 7 days of exposure, RSE was transported into the cytosol, which disrupted enzyme activity and photosynthesis. The cyanobacteria then started to repair its physiology （enzyme activity, photosynthesis） and remained viable, suggesting that rice straw act as an algistatic agent.     

Effects of Trawl Selectivity and Genetic Parameters on Fish Body Length Under Long-Term Trawling

Long-term fishing pressure affects the biological characteristics of exploited fish stocks. The biological characteristics of hairtail(Trichiurus lepturus) in the East China Sea are unable to recover because of long-term trawling. Fishing induces evolutionary effects on the fish's biological characteristics. Evidence of these changes includes small size at age, a shift to earlier age structure, and early maturation. Natural and artificial selection usually affect the fish's life history. Selection can induce different chances of reproduction, and individual fish can give a different genetic contribution to the next generation. In this study, analysis of time-dependent probability of significance and test of sensitivity were used to explore the effects of fish exploitation rate, mesh size, and heritability with long-term trawling. Results showed that fishing parameters were important drivers to exploited fish population. However, genetic traits altered by fishing were slow, and the changes in biological characteristics were weaker than those caused by fishing selection. Exploitation rate and mesh size exhibited similar evolutionary trend tendency under long-term fishing. The time-dependent probability of significance trend showed a gradual growth and tended to be stable. Therefore, the direction of fishing-induced evolution and successful management of fish species require considerable attention to contribute to sustainable fisheries in China.     

Genetic analysis of selected Sargassum fusiforme (Harvey) Setchell (Sargassaceae,Phaeophyta) strains with RAPD and ISSR markers

Since the 1980s, Sargassum fusiforme has been cultivated in Zhejiang, South China, and nowadays it becomes one of the important commercial seaweeds in China. With traditions of eating habits in the East Asian countries, this brown alga is used as food, because it contained functional oligo/polysaccharides and chemical components, and was regarded playing roles in antioxidant activities and regulating immunology. Through over 15 years' selection, breeding and cultivation, we obtained three strains with good traits and testified their characters during the production, which included the cultivars with high yield and other two good characters, either all the selected strains were applied in the Sargassum production. To avoid confusion during the selection and nursery, it was preferred to establish one fingerprint for distinguishing the Sargassum cultivars from different strains. Random amplified polymorphic DNA(RAPD) and inter-simple sequence repeat(ISSR) methods were adopted to analyze the genetic diversities of the selected S. fusiforme strains. With that, one fingerprint with RAPD markers was constructed, and one sequence characterized amplified region(SCAR) marker to S.fusiforme was obtained. It is indicated that the applied fingerprint could be valid in S. fusiforme genetic and germplasm justification, and will be positive to molecular marker assistance in its selection and cultivation.