A comparison of in vitro flowers to in vivo flowers of haploid and diploidNicotiana tabacum L.

Thin cell layers (TCLs) were cultured from inflorescences of diploid (2n=4x=48) and haploid (2n=2x=24)Nicotiana tabacum L. "Samsun" and the subsequent flowers formed in vitro were then compared to in vivo flowers. Plants derived from TCLs possessed flowers that were typical of their seed or androgenetically-derived counterparts, whereas de novo flowers from TCLs were abnormal when compared to their counterparts. The TCLs of haploid plants produced more flower buds than diploid TCLs, and did so in a shorter period of time. In vitro flowers and anthers at both ploidy levels were considerably smaller than the in vivo flowers; in vitro flowers also had variable numbers of anthers and pistils. The embryogenic capacity of anthers taken from in vivo diploid flowers was 5 times greater than that of in vitro diploid or haploid anthers. In vivo haploid anthers produced no embryoids, whereas in vitro haploid anthers did produce embryoids. Observations of mitotic cells in root tips of plants derived from anther cultures of in vitro haploid flowers revealed a mixoploid nature. Diploid meiosis was regular and haploid meiosis was irregular regardless of the origin (in vitro or in vivo) of the flowers.Supported by state Hatch funds.     

Analysis of ploidy in a planarian by flow cytometry

Flow cytometry (flow microfluorimetry) provides a quick means for analysis of ploidy in planarians. Nuclei from homogenized tissues of the freshwater planarian Dugesia japonica japonica Ichikawa et Kawakatsu were stained with propidium iodide and measured with an argon-laser flow cytometer to produce histograms of DNA content. Tissues from sexually mature individuals produced histograms with a 1n (haploid) peak but no 3n peak (triploid peak), whereas those from asexual individuals showed a 2n peak or a 3n peak or both, but no 1n peak. Thus, the 1n peak distinguished sexual individuals. Mixoploid individuals, i.e., mosaics with both diploid and triploid tissues, were identified by the presence of both a 2n peak and a 3n peak. The ratios of the heights of the 2n and 3n peaks from tissues in different parts of a single mixoploid individual were similar, suggesting that the diploid and triploid cells are homogeneously distributed.     

Chromosomal Variation in Lotus alpinus (Fabaceae)

Abstract An accession of Lotus alpinus Schleich. (2n=2x=12) from Turkey in which B chromosomes have been found was studied morphologically and karyologically. Chromosome numbers were observed in 519 cells from nine plants which all exhibited mixoploidy (2n=11, 12, 12 + 1B, 12 + 2B and over 20). Keel tip color, stem pubescence, and inflorescence size differed from a collection of this species from Switzerland. While the percentage of total lengths of the chromosome complements and the relative chromosome lengths in the two accessions were very similar, the total complement lengths differed considerably (23.14μm Turkey vs. 29.46μm Switzerland). This karyological difference is not considered to be the result of the presence of B chromosomes, but probably the result of hybridization between different genotypes. Aborted seed pods were observed which lent credibility to this hypothesis. Plants of this accession may have arisen as a result of hybridization between Lotus corniculatus and/or L. alpinus as both diploid and tetraploid cytotypes are reported in the Turkey collection for these species. The data would lend support for their hybrid origin.     

Studies on the speciation of Japanese freshwater planarian Polycelis auriculata based on the analysis of its karyotypes and constitutive proteins

Various kinds of chromosomal polymorphisms or karyotypic variations are found in the Japanese freshwater planarian Polycelis auriculata. Within this species, there are found worms whose chromosome numbers are 2n = 6, 10, 11, 12 and others, and 3x = 6 and 9. There are some which have cells with triploidy and tetraploidy complements (3x = 6 & 4x = 8), and others which have cells with triploidy and hexaploidy complements (3x = 6 & 6x = 12). These worms with such varied karyotypes are usually found in separate habitats, though occasionally they occur together. Electrophoretic analysis of the proteins extracted from the karyotipically different worms which belong to three different local populations shows some dissimilarity in the constitutive proteins according to their karyotypic differences. The results obtained suggest that this species is still in the process of speciation or chromosomal evolution.     

柑桔始叶螨与柑桔全爪螨染色体制备方法与核型探讨

采用一种新的染色体制备方法,成功地制备和观察了柑桔始叶螨和柑桔全爪螨的中期染色体。柑桔始叶螨的核型n=4、2n=8,柑桔全爪螨的核型n=3、2n=6或n=4、2n=8。C显带与扫描电镜结果显示,柑桔始叶螨与柑桔全爪螨为全着丝粒染色体,并存在混倍性现象。     

昆虫细胞分类学的基本问题及染色体系统发育的重建方法

本文非昆虫细胞遗传学及细胞分类学原理与技术的全面评述;而是从细胞遗传学特征（或称染色体特征）在混虫分类学中的应用入手,重点提出与分析了昆虫细胞分类学中的种类鉴定,研究取材,染色体多态现象,多倍体及核型进化方向等基本问题,并着重总结了目前国际上细胞水平染色体数据的处理方法,即传统法,倒位法,数值法与支序法;最后,作者指出了正确看待细胞分类学重要性的态度。     

Karyotypes of 16 populations of eight species in the genus Polygonatum (Asparagaceae) from China

The karyotypes of 16 populations belonging to eight species of Polygonatum from China were analysed. The chromosome numbers and karyotypes of P. omeiense, P. adnatum and P. hirtellum and the diploidy of P. tessellatum are reported for the first time. The basic chromosome numbers were x = 11, 13, 14 and 15. Based on Stebbins' karyotypic classification, the four karyotypes were recognized as 2B, 3B, 2C and 3C. Considering the arm ratio and individual chromosome size, it was concluded that the possible evolutionary trend of the karyotypes in Polygonatum was from 2B to 3C. The results show that: (1) satellite heterozygosity occurs in many species of this genus; (2) mixoploidy and B chromosomes occur in some species; and (c) karyotypes are different in different species and even in different populations of the same species. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 245–254.     

浙江大罗山七倍体薤白的发现及其成因分析

该试验对浙江大罗山一个薤白种群的13个个体进行了染色体计数和核型分析,并对探讨七倍体薤白的可能形成机制进行了讨论。结果表明:(1)大罗山薤白种群为混倍种群,其中3个个体为七倍体,染色体组型是2n=7x=46m(2SAT)+10sm(2SAT),核型为2B型;10个个体为四倍体,染色体组型是2n=4x=26m(1SAT)+6sm(1SAT),核型为2B型。薤白种群的混倍性和七倍体均为首次报道。(2)对七倍体薤白的成因分析认为,七倍体是通过三倍体和四倍体未减数配子结合产生;随体染色体数目并不与植株的倍性相对应,而且并不都是出现于同源染色体上;薤白种内倍性增大与其物种进化的趋势一致,即倍性越大,种群越进化。     

Further survey of chromosomal polymorphisms in the freshwater planarian Polycelis auriculata

Although the chromosomal number of Polycelis (Seidlia) auriculata Ijima et Kaburaki is basically 2n = 6, this species shows remarkable chromosomal polymorphisms in different populations. Among worms collected at 30 stations in the central part of Japan's Main Island and in Hokkaido, we found five new karyotypes, considered to be variations of tetraploidy and diploidy: 4n?fis¹. + 1 = 3SM + 2A + 3T₁ + 2T₂ + 4M = 14, 4n?fis².(B) = 2SM + 2A + 4T₁ + 2T₂ + 4M + (0?2B) = 14 –16, 4n?fis². + 1 = 2SM + 2A + 4T₁ + 2T₂+5M= 15, 4n?fis².?2 = 2SM + 2A + 4T₁ + 4M = 12, and 2nM- = 2SM + 2A = 4 (where SM = submetacentric; A = acrocentric; T₁ and T₂ = telocentric; M = metacentric; B = B-chromosome; fis¹. and fis². = occurrence of one or two centric fissions, respectively; and M- = deletion of a metacentric chromosome). These karyotypes exist singly in one individual or as various mixoploids within the same individual. No individual having only karyotype 2nM- has yet been found. This brings the total number of known karyotypes in P. auriculata to 17; these can be arranged in an order that we believe reflects their evolution.     

Cytogenetic and Anatomic Features of the Weeping Birch in the 30-km Zone Surrounding the Novovoronezh Nuclear Power Plant

We studied the development of the vegetative and generative spheres in the weeping birch from the 30-km zone surrounding the Novovoronezh nuclear power plant. Being the most sensitive ontogenetic stages, the mitotic and meiotic processes are capable of responding to the effects of various factors, including unfavorable environmental factors. Studies were carried out from 1998 to 2000 in Novovoronezh under conditions of potential hazard for normal development (a possible joint effect of chronic ionizing irradiation at low doses from the Novovoronezh nuclear power plant and elevated concentrations of some chemical substances as side products of the plant activity) and in the ecologically pure territory of the Biological Station Venevitinovo of the Voronezh State University. Significant deviations from the normal course of mitotic and meiotic processes have been recorded in the experimental variant and specific types of disturbances have been described. A suggestion has been put forward concerning some mechanisms underlying the weeping birch adaptation to unfavorable environmental conditions. Specifically, it was shown that the trees studied were of a mixoploid nature. No such studies have ever been carried out in the region of this nuclear power plant, one of the oldest in Russia.