Phylogenetic insights of Avena genus based on genomic analysis of 45S rDNA molecular organization

Tese de mestrado. Biologia (Biologia Molecular e Genética). Universidade de Lisboa, Faculdade de Ciências, 2014

Chromosomal location of heterochromatin and 45S rDNA sites in four South American triatomines (Heteroptera: Reduviidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evolutionary dynamics of 5S rDNA location in acridid grasshoppers and its relationship with H3 histone gene and 45S rDNA location

We analyze the chromosomal location of 5S rDNA clusters in 29 species of grasshoppers belonging to the family Acrididae. There was extensive variation among species for the number and location of 5S rDNA sites. Out of 148 sites detected, 75% were proximally located, 21.6% were interstitial, and only 3.4% were distal. The number of 5S rDNA sites per species varied from a single chromosome pair (in six species) to all chromosome pairs (in five species), with a range of intermediate situations. Thirteen chromosomes from eight species carried two 5S rDNA clusters. At intraspecific level, differences among populations were detected in Eyprepocnemis plorans, and some heteromorphisms have also been observed in some species. Double FISH for 5S rDNA and H3 histone gene DNA, performed on 17 of these 29 species, revealed that both markers are sometimes placed in a same chromosome but at different location, whereas they appeared to co-localize in five species (Calliptamus barbarus, Heteracris adpersa, Aiolopus strepens, Oedipoda charpentieri and O. coerulescens). Double fiber-FISH in A. strepens and O. coerulescens showed that the two DNAs are closely interspersed with variable relative amounts of both classes of DNA. Finally, no correlation was observed between the number of 5S and 45S rDNA clusters in 23 species where this information was available. These results are discussed in the light of possible mechanisms of spread that led to the extensive variation in the number of clusters observed for both rDNA types in acridid grasshoppers. © 2011 Springer Science+Business Media B.V.

Distribution of 45S and 5S rDNA sites in 23 species of Eleocharis (Cyperaceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Karyotype characterization reveals an up and down of 45S and 5S rDNA sites in Crotalaria (Leguminosae-Papilionoideae) species of the section Hedriocarpae subsection Macrostachyae

The genus Crotalaria is one of the largest within the family Leguminosae-Papilionoideae, with more than 600 species. However, few karyotypes have been described. In the present paper, five species belonging to the section Hedriocarpae were studied (subsection Machrostachyae), in order to better understand chromosomal evolution in Crotalaria. The results reveals that all species presented 2n = 2x = 16 with symmetrical karyotypes, and slight differences in the chromosome morphology. A secondary constriction was identified at short arm of the pair 1. The 45S rDNA was mapped in the secondary constriction and adjacent heterochromatin (NOR-heterochromatin) and a minor site was identified in C. ochroleuca. The 5S rDNA was mapped linked to 45S rDNA at chromosome 1 short arm in all species. Additional sites for 5S rDNA were identified in C. pallida, C. striata and C. mucronata. Heterochromatin blocks around the centromeres are not CMA(+) neither DAPI(+). The karyotypes of the subsection Macrostachyae are characterized by an inversion at chromosome pair one in relation to previous specialized floral species analyzed. Additional sites of 45S and 5S rDNA were assumed to be a result of transposition events by different ways. The results suggest heterochromatin differentiation and the position of ribosomal genes indicates chromosomal rearrangements during evolution. Karyotype characteristics corroborate the morphological infrageneric classification.

Two 5S rDNA arrays in Neotropical fish species: is it a general rule for fishes ?

In this paper we describe Southern blot hybridization results probed with 5S rRNA genes for several Neotropical fish species representing different taxonomic groups. All the studied species showed a general trend with the 5S rDNA tandem repeats organized in two distinct size-classes. At the same time, data on 5S rDNA organization in fish genome were summarized. Previous information on the organization and evolution of 5S rRNA gene arrays in the genome of this vertebrate group are in agreement with the Southern results here presented. Sequences obtained for several fish species have revealed the occurrence of two distinct 5S rDNA classes characterized by distinct non-transcribed spacer sequences, which are clustered in different chromosomes in some species. Moreover, the 5S rDNA loci are generally distributed in an interstitial position in the chromosomes and they are usually not syntenic to the 45S rDNA. The presence of two classes of 5S rDNA in several non-related fish species suggests that this could be a common condition for the 5S rRNA gene organization in the fish genome.

Localization of rDNA sites in holocentric chromosomes of three species of triatomines (Heteroptera, Triatominae).

Chromatin organization in the holocentric chromosomes of three triatomines species was cytologically studied by fluorescent in situ hybridization with a 45S rDNA probe of Drosophila melanogaster to localize ribosomal genes. In Triatoma tibiamaculata, metaphases I showed telomeric highlights in a single, larger bivalent. In T. protacta, hybridization was detected in one of the telomeres of an autosomal chromosome. In T. platensis, there were highlights in a single, smaller chromosome (X chromosome). The results obtained did not agree with the expected localization of rDNA genes in the sex chromosomes of triatomines, as demonstrated by silver impregnation, and suggest that the chromosome reorganization that occurred in this group during evolution may be a more important mechanism involved in rDNA distribution.

The conservation of number and location of 18S sites indicates the relative stability of rDNA in species of Pentatomomorpha (Heteroptera)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Location of 45S Ribosomal Genes in Mitotic and Meiotic Chromosomes of Buthid Scorpions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

稻属系统学若干问题的探讨

稻属（OryzaL．）是禾本科稻族(Oryzeae)中最大，也是分布最广的属，由于其包括亚洲栽培稻这一世界第一大粮食作物，对该属各方面的研究都相当多，系统与进化植物学研究也是如此。然而，由于该属分布跨及亚、非、美、澳各洲热带、亚热带地区，材料不易得到，故研究常缺乏系统性，属和属内一些种的界限仍然存在争议，属下组间特别是几个孤立类群间的系统发育关系也一直不很清楚，稻属与近缘类群间系统发育关系研究也很有限。为此，本文在以前学者研究的基础上，综合评述了目前稻属各分类系统，指出了目前普遍接受的观点和存在分歧，同时对稻属系统作了一些必要的修订;通过l7种野生稻的核型分析和通过原位杂交技术在稻属尝试性的应用，从染色体水平探讨了稻属与近缘类群间的关系以及稻属内物种间的关系;通过对lO个属28种稻族植物cp DNA上的trnK基因的限制性内切酶位点的分析，并综合其它证据，对稻属与近缘属间关系进行初步的探讨。主要的结论如下： 一、 17种野生稻核型研究表明： 1）所有种的间期核属染色中心型(chromocentertype)，染色中心较少或多，形状规则或不规则，散布于全核;前期染色体固缩特性属于近基型(proximal type)，2）Sect.Oryza所有种的核型很相似，均为n=5m+5sm+2t，其中第四对和第十对为st染色体，第十对为随体染色体，Sect. Brachyantha和SeCt. Padia的核型与前者有一定的差异，表现在随体染色体的位置和染色体的大小。0. brachyantha的核型特点并不支持将该种置于Sect. Oryza的观点。 对携带BC和CD基因组的四个种的核型分析表明，其染色体组成并非是二倍体染色体组成的叠加，说明其形成后发生了二倍化的分化，综合各方面证据， 我们支持携带BC基因组的两个四倍体种属双系起源， 而携带CD基因组的四倍体之起源与亚洲携带C基因组的物种有关的观点。3）对国内8个居群的药用野生稻（0．officinalis）核型研究表明，所有居群均为二倍体，未发现以前学者所报道的四倍体类型。药用野生稻为一多型种，通过初步的形态学比较分析，我们认为斯里兰卡分布的根茎野生稻O.rhizomatis很可能是药用野生稻这一多型种适应于季节性干旱环境的一个生态型。4）以前学者认为稻属可能源于x一5的次级多倍化，我们不支持这一观点，从整个稻族所有属以及近缘的稻亚科其它三族的染色体基数来考虑，我们认为其祖先类群更可能的染色体基数为x-6。 二、原位杂交结果：1）确定了13个种的45s rDNA的位点数，其中所有携带A基因组的物种除亚洲栽培稻和O_ rufipogon之位点数有1和2的分化外，其余种皆为一个位点;B基因组也含一个位点，C基因组的两个种各含3个位点， BC基因组的两个种均具三个位点，E基因组含二个位点，携带CD基因组的稻种分别携带3和5个位点，其中位点有大小之分;2)利用C基因组作探针，B基因组作封阻DNA，在四倍体CD（O.latifolia）的染色体制片中确立了带C基因组的染色体。 三、用PCR-RFLP技术对稻族lO个属28个种的trnK基因的酶切位点变异进行了分析，发现：(1) trnK基因PCR扩增产物长度约为2575bp，没有明显的长度变异，l7种内切酶处理，共得到72个酶切位点，占整个trnk基因全长的13.98%，72个酶切位点中52个为突变位点，33个为信息位点，利用52个突变位点，构建了28个种的树系图。(2)分支分析表明，稻族的lO个属共分为两组，一组为O.ryza和Porteresia，一组为其余的8个属;该结果明显不同于经典的族内划分。根据稻族各属现在的分布格局，认为稻族是禾本科早期分化过程中产生的类群，由于生境的相似，趋同演化和网状进化事件可能比较频繁，稻族的亚族划分可能存在一些不合理的成分。Porteresia coarctata, Rhynchoryza subulata，Leersia perieri三种以前曾被置于稻属，根据分支图，后两种位于分枝图的第二支，与稻属各种分化较大，而P．coarctata与稻属聚在一起，说明两者在锻汰基因的变异式样是相似的。综合各方面资料，我们认为P. coarctata可能是稻属适应于海滩耐盐环境的一个特化的类群。 (3)稻属的Sect. Oryza所包括的两个系Ser.Oryza与Ser.Latifolia仅在一个酶切位点上有差异，说明其间关系非常密切，Sect. Padia中的两个系Ser. Meyerianae和Ser.Ridleyianae与Sect.Oryza所包括的两个系Ser. Oryza与Ser. Latifolia有明显分化，两个孤立类群O brachytrntha f770．scl71echteri与Ser. Ridleyi聚在一起。 这一结果与Vaughan(1994)将两孤立种和O.ridteyi复合体同置于其系统中的Sect. Ridleyanae是吻合的。

Identification of genome organization in the unusual allotetraploid form of Carassius auratus gibelio

The unusual allotetraploid form with unequal contribution of chromosome sets was discovered from the gynogenetic offspring of Carassius auratus gibelio stimulated by red common carp sperm. In this study, genomic in situ hybridization (GISH) and fluorescent in situ hybridization (FISH) with 45S rDNA probe are used. The GISH results lead to the identification of species-specific chromosomes, which permits to demonstrate the origin and genome organization in the allotetraploid form. Moreover, chromosome localization of 45S rDNA and co-localizations of 45S rDNA and Cyprinus carpio genomic DNA further confirm that one extra 45S rDNA positive chromosome in the allotetraploid form originates from the paternal haploid genome of C carpio, and other 5 45S rDNA-containing chromosomes are from the maternal genome of Carassius auratus gibelio. And, the correlation between 45 rDNA and the nucleolar organizer regions (NORs) is confirmed by silver nitrate staining. The data provide direct experiment evidence that the allotetraploid actually contains three chromosome sets of Carassius auratus gibelio and one chromosome set of C carpio, and will be a useful genetic material for both basic research and breeding practice. (c) 2006 Elsevier B.V. All rights reserved.

Karyotype characterization of Mugil incilis Hancock, 1830 (Mugiliformes: Mugilidae), including a description of an unusual co-localization of major and minor ribosomal genes in the family

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chromosomal organization of the 18S and 5S rRNAs and histone H3 genes in Scarabaeinae coleopterans: insights into the evolutionary dynamics of multigene families and heterochromatin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytogenetic characterization reveals differences in nuclear organization of cystic cells among Brazilian species of Triatoma (Heteroptera, Reduviidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytogenetical and cytotaxonomical analysis of some Brazilian species of Eleocharis (Cyperaceae)

Karyotype analysis of 21 samples of 11 species of Eleocharis ( Cyperaceae) from 10 localities in Brazil, showed the presence of chromosomes without primary constrictions and parallel movement of chromatids at metaphase-anaphase transition. Only the terminal nucleolar constrictions ( satellites) were visualised. The chromosome numbers varied from 2n=6 in E. subarticulata to 2n=54 in E. acutangula, but the chromosome basic number x=5 was confirmed. Generally, C-CMA(3)(+) bands appear mostly in the extremities of the chromosomes, associated to NOR, and interstitial C-CMA(3) bands were found only in E. geniculata and E. acutangula. C-DAPI(+) bands were not found. Fluorescence in situ hybridisation ( FISH) with the 45S rDNA probe was performed in five species. The results showed from four to eight hybridisation signals, always terminal. The analysed species include representatives of the following three subgenera of Eleocharis that occur in Brazil: Limnochloa, Scirpidium and Eleocharis. Species from the subgenus Limnochloa have small and numerous chromosomes. The remaining species, belonging to subgenera Eleocharis and Scirpidium, possess fewer and larger chromosomes. In subgenus Eleocharis, karyotypes of the section Eleocharis were differentiated by symploidy, agmatoploidy and polyploidy, whereas species of the section Eleogenus were all polyploids. Polyploidy seems to be the most frequent event in the karyotype differentiation in Eleocharis, but changes in the chromosome size and repetitive DNA sites were also observed.