大蒜种植密度对烟蚜生长发育历期、后代数和繁殖率的影响

为探究大蒜种植密度对烟蚜生长发育和繁殖的影响,通过测定大蒜不同种植密度下烟蚜若蚜发育历期、成蚜寿命及其后代数,结果表明,受不同密度大蒜影响后,烟蚜各龄的发育历期、后代数和繁殖率与对照相比有一定影响。特别是烟蚜2~4龄若蚜的总发育历期,随大蒜种植密度的增加而显著延长(P<0.05)。当大蒜种植密度为5株·盆^(-1)时,对2~4龄若蚜发育历期的影响最大,比对照的延长了48.00 h,延长46.15%;当密度为3株·盆^(-1)时,对2~4龄若蚜发育历期的影响居中,比对照延长了29.33 h,延长28.20%;当密度为1株·盆^(-1)时,对2~4龄若蚜发育历期的影响最小,比对照缩短了2.67 h,缩短2.57%。烟蚜1龄、2龄、3龄若蚜发育历期和成蚜寿命与大蒜种植密度间相关性不显著(P>0.05)。但4龄若蚜和2~4龄若蚜发育历期与大蒜种植密度间具显著正相关(P<0.05)。因此,大蒜种植密度能延长烟蚜2~4龄若蚜发育历期,这可能是大田中大蒜能够控制烟蚜的关键原因之一,起到推迟成蚜产蚜起始时间及减少当代烟蚜对作物的危害。研究结果将为利用大蒜防控烟蚜提供科学依据。

广义生灭分支过程存活后代数的分布

考虑一个生物种群生灭分支过程,其中个体繁衍后代的出生率与死亡率均为依赖时间的函数.在通常的(条件)独立性假设条件下,用生成函数方法给出了任意个体在给定时刻仍存活或已死亡条件下其存活后代数的分布,进而给出了个体在已知其"生卒时刻",任意时刻存活后代数的分布.

含两类质体的细胞随分裂而质体纯化的特征

本文先通过转移概率给出了刻划杂合状态起始细胞可纯化，单向纯化，双向纯化的特征，然后引入了临界平均后代数概念，并用此概念刻划了单向纯化、双向纯化的实质．

Quality Analysis of Dairy Herd Improvement Data from Henan Province

The dairy herd improvement data from Henan Province were analyzed statistically to establish screening criteria for relevant data, thereby laying a foundation for genetic evaluation of dairy cows. With the 2 152 451 test-day records about 155 893 Chinese Holstein dairy cows collected by the Henan Dairy Herd Improvement Center from January 2008 to April 2016, the dynamics of test times during a complete lactation, test interval during a complete lactation, days in milk （DIM） of first test-day record, daughter descendant number and herd number of bull, age at first calving and pedigree integrity rate among different years and different herd sizes were analyzed by MEANS order of SAS 9.4. In addition, the data that were applicable to genetic evaluation were screened by SQL program. The results showed that during 2008-2015, the number of cow individuals participating in DHI in Henan Province increased from 7 379 to 93 706; the test-day milk yield increased from 19.91 to 24.05 kg; the somatic cell count reduced from 411.09×10^3 to 277.08×10^3 cells/ml; the percentage of cows with DIM ranging from 5-305 d reached 70.92%; the average test times increased from 3.20 to 6.31 times; the test interval decreased from 70.22 to 33.83 d; the dairy cows with age at first calving of 25 months were dominant, accounting for 12.57%; the bulls whose daughter descendant number was 20 or more and the daughters were distributed in 10 or more farms accounted for 6.05%; the one-generation pedigree integrity rate was 82.54%; the percentage of data that could be used for genetic evaluation was screened as 20.67%, which was lower than the results of other similar studies.

Variation in chromosome number in the seedling progeny of a somaclone of Paspalum dilatatum

The somaclone, C39, derived by tissue culture from the obligate apomict Paspalum dilatatum cv Raki (2n=50), had 50 chromosomes and a karyotype apparently identical to Raki.SC2 seedlings of C39 showed a high degree of phenotypic variation which was of ten associated with increased chromosome numbers, but some of the variant seedlings were karyotypically indistinguishable from Raki or C39. Plants with increased chromosome numbers exhibited a high degree of intraplant chromosome variation (aneusomaty). In one of the SC2seedlings, the chromosome number of root tip cells varied from 58 to 82 and in several other seedlings the range was more than 10. The results suggested that the ability to form seed apomictically was much reduced in C39 and that this plant showed some capacity for sexual reproduction and the resulting seedlings, with a chromosome number of about 70, were genetically unstable. Of 11 SC2 seedlings examined cytolog ically, 6 did not produce any viable seed. Seedlings grown from seed of the remaining 5 plants showed that aneusomaty persisted in the SC3 generation. SC3 seedlings which were phenotypically similar to their maternal parent showed a similar range of chromosome numbers to that parent. Some of the SC3 seedlings exhibited an even wider range of chromosome numbers (e.g.56-136), and these plants were all dwarfs.

A New Descent Algebra for Weyl Groups of Type An

In this paper we define an equivalence relation on the set of all xj in order to form a basis for a new descent algebra of Weyl groups of type A,. By means of this, we construct a new commutative and semi-simple descent algebra for Weyl groups of type An generated by equivalence classes arising from this equivalence relation.

Hv-SEMIGROUP STRUCTURE ON F2-OFFSPRING OF A GENE POOL

Mendel, the father of genetics took the first steps in defining ＂contrasting characters, genotypes in F1 and F2... and setting different laws＂. The genotypes of F2 is dependent on the type of its parents genotype and it follows certain roles. Purpose of this paper is to analyze the second generation genotypes of monohybrid and a dihybrid with a mathematical structure. We use the concept of Hv-semigroup structure in the F2-genotypes with cross oper- ation and prove that this is an Hv-semigroup. We determine the kinds of number of the Hv-subsemigroups of F2-genotypes.

A LINEAR PROGRAMMING MODEL BASED ON NETWORK FLOW FOR PATHWAY INFERENCE

Signal transduction pathways play important roles in various biological processes such as cell cycle, apoptosis, proliferation, differentiation and responses to the external stimuli. Efficient computational methods are of great demands to map signaling pathways systematically based on the interactome and microarray data in the post-genome era. This paper proposes a novel approach to infer the pathways based on the network flow well studied in the operation research. The authors define a potentiality variable for each protein to denote the extent to which it contributes to the objective pathway. And the capacity on each edge is not a constant but a function of the potentiality variables of the corresponding two proteins. The total potentiality of all proteins is given an upper bound. The approach is formulated to a linear programming model and solved by the simplex method. Experiments on the yeast sporulation data suggest this novel approach recreats successfully the backbone of the MAPK signaling pathway with a low upper bound of the total potentiality. By increasing the upper bound, the approach successfully predicts all the members of the Mitogen-activated protein kinases （MAPK） pathway responding to the pheromone. This simple but effective approach can also be used to infer the genetic information processing pathways underlying the expression quantitative trait loci （eQTL） associations, illustrated by the second example.