世界蚜虫分类研究进展

本文综述了世界蚜虫分类研究进展。内容包括形态分类、细胞分类、生物化学分类以及化石研究等,并以M.L.Sharma的文献目录为基础,对世界蚜虫分类研究报告篇数进行统计。结果表明:世界各国蚜虫分类研究进展极不平衡,美国、加拿大、日本及欧洲的一些国家包括荷兰、丹麦、瑞典、捷克、波兰、德国等其α分类任务基本完成,印度也进展较快,离完成α分类任务为期不远。苏联欧洲部分也已基本完成,亚洲部分和中国尚有大量α级分类工作有待完成。     

Third chromosome suppressor of position-effect variegation loci in Drosophila melanogaster

Summary As a result of a genetic analysis of 63 third chromosome suppressor mutations of position-effect variegation 12 different loci showing dominant suppression have been identified and their map positions determined. A compilcation of the genetic data available for each suppressor locus is given. The strong suppressor effects of the mutations have been quantified by measurements of white variegation inw ^m4h /w ^m4h ,w ^m4h /Y andw ^m4h /O flies. Mutant alleles of three loci were found in these studies to dominate over the strong enhancer effect of complete loss of the Y chromosome. Most of the identified loci suppressing position-effect variegation represent essential genetic funtions; only three loci represent nonessential functions. Mutations of two loci display recessive butyrate sensitivity and lethal interaction with the heterochromatic Y chromosome suggesting that these genes affect chromosomal condensation. Studies with deficiencies and triploids revealed that most of the loci represent haplo-abnormal suppressor functions. The use of the isolated mutant material for genetic, developmental and molecular studies of processes connected with gene inactivation in position-effect variegation is discussed.Dedicated to Prof. H.J. Becker on the occasion of his 6th birthday     

The influence of temperature on chromosome elimination during embryo development in crosses involving Hordeum spp., wheat (Triticum aestivum L.) and rye (Secale cereale L.)

Summary Several interspecific and intergeneric crosses involving five Hordeum species, Triticum aestivum and Secale cereale were carried out to investigate the influence of two contrasting temperatures on chromosome elimination during embryo development. In four of the interspecific Hordeum crosses, chromosome elimination was significantly increased at the higher of the two temperatures, resulting in greater proportions of haploid plant progenies. However, there was no significant effect of temperature in the other interspecific cross between H. lechleri x H. bulbosum nor in the two intergeneric crosses between H. vulgare x S. cereale and T. aestivum x H. bulbosum whose progeny were exclusively hybrid and haploid, respectively.     

Cytological studies of triploids and their progeny from male-sterile (ms1) soybean

Summary Triploids (2n=3X=60) were obtained from genetic male-sterile (ms1 ms1) soybean [Glycine max (L.) Merr.] plants. Meiosis, pollen fertility, and chromosome number of their progeny were studied. Studies of meiosis in fertile and sterile triploids revealed no distinguishable differences in chromosome associations. Male-sterile plants formed coenocytic microspores characteristic of the ms1 mutant. Restitution of some dyad and tetrad nuclei were observed in male-sterile plants. Chromosomes of the triploids tended to occur in trivalents during diakinesis and metaphase I (MI), but multivalents, bivalents, and univalents also were observed. Average types and frequencies of chromosome associations per cell in diakinesis and MI from 542 pollen mother cells were 0.004 IX + 0.06 VI + 0.002 V + 0.005 IV + 16.99 III + 1.79 II + 5.03 I. Some secondary associations, nonhomologous pairing, and aberrant nucleolar distributions occasionally were observed. Such behavior support the hypothesis of duplicated genomes and the polyploid origin of soybean. Pollen fertility in male-fertile triploid plants (Ms1 ms1 ms1) varied from 57% to 82%, with an average of about 71%. Chromosome numbers of progenies obtained from these fertile triploids varied from 2n=40 to 2n=71, and exhibited a near-random distribution, with the majority (about 60%) being between 56 and 65. Progenies of the fertile triploids gave segregation ratios for the ms1 allele, which confirmed the Ms1 ms1 ms1 genotype.Joint contribution: Agricultural Research Service, U.S. Department of Agriculture, and Journal Paper No. J-11672 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA 50011, USA, Project 2471     

Meiotic pairing in hybrids between tetraploid Triticale and related species: new elements concerning the chromosome constitution of tetraploid Triticale

Summary Two F5 strains of tetraploid triticale (2n= 4x=28), obtained from 6x triticaleX2 rye progenies, were crossed with diploid and tetraploid rye, some durum and bread wheats, and various 8x and 6x triticale lines. Meiosis in the different hybrid combinations was studied. The results showed that the haploid complement of these triticales consists of seven chromosomes from rye and seven chromosomes from wheat. High frequencies of PMCs showing trivalents were observed in hybrids involving the reference genotypes of wheat and triticale. These findings proved that several chromosomes from the wheat component have chromosome segments coming from two parental wheat chromosomes. The origin of these heterogeneous chromosomes probably lies in homoeologous pairing occurring at meiosis in the 6x triticaleX2x rye hybrids from which 4x triticale lines were isolated. A comparison among different hybrids combinations indicated that the involvement of D-genome chromosomes in homoeologous pairing is quite limited. In contrast, meiotic patterns in 4x triticale X 2x rye hybrids showed a quite high pairing frequency between some R chromosomes and their A and B homoeologues.     

A new mechanism for altering chromosome number during karyotype evolution

Summary A new mechanism for changing chromosome numbers (preserving the fundamental number of long chromosome arms) during karyotype evolution is suggested. It includes: 1) Occurrence of individuals heterozygous for two interchanges between different arms of three chromosomes (a metacentric and two acrocentric ones). 2) Formation in heterokaryotypes of multivalents during meiosis between the chromosomes involved in the interchanges and their unchanged homologues. 3) Mis-segregation of chromosomes from these multivalents resulting in hypoploid (n-1) and hyperploid (n+1) simultaneously instead of euhaploid gametes. 4) Fusion of n-1 or n+1 gametes which gives rise to (zygotes and) individuals representing homokaryotypes with changed number of chromosomes (2n+2 or 2n-2), but preserves (as compared to the parental karyotypes) the number of long chromosome arms. Under definite conditions, chromosome numbers of the progeny may be changed by this process in both directions (upwards and downwards). The mechanism is free of the difficulties associated with the explanation for such changes by direct Robertsonian interchanges (see Discussion), which are usually considered to be responsible for such alterations in chromosome number. The above-mentioned process has been experimentally documented in Vicia faba and it probably also occurred naturally within the Vicia sativa group.     

水稻(Oryza sativa)核型分析

水稻(Oryza sativa)核型分析结果:在12对染色体中,具中部着丝点的有5对,近中部着丝点的有6对(包括随体染色体),1对近端部着丝点。本文还着重讨论了随体的数目及所在的染色体。     

新疆20种药用植物的染色体观察

本文对在新疆生长和引种栽培的10科20种药用植物染色体进行了计数和研究,其中5种进行了核型分析,6种为首次报道。     

四种猕猴桃属植物的染色体数目观察

本文报道了四种猕猴桃植物的染色体数目。结合其他作者的有关报道,讨论了猕猴桃属的染色体基数,性染色体,倍性,及其与地理分布之间的关系。     

亚洲棉与比克氏棉杂交的研究

观察分析了亚洲棉×比克氏棉杂种后代的形态表现及减数分裂行为。结果表明,野生比克氏棉的形态性状遗传传递力较强,F_1在中期Ⅰ的染色体构型为15.14Ⅰ+5.29Ⅱ,二价体的平均交叉数为1.07;F_2的染色体构型为2.55Ⅰ+24.5Ⅱ+0.15 Ⅲ,二价体交叉数为1.83。F_2的开花习性表现异常,完全自花受精将有利于后代性状的快速稳定。F_2中分离出无腺体的植株,为将“油腺延缓形成”特性转育到栽培种提供了可能。