Toward Male Individualization with Rapidly Mutating Y-Chromosomal Short Tandem Repeats

Peer reviewe

Taxonomic status of two South American sympatric squat lobsters, Munida gregaria and Munida subrugosa (Crustacea: Decapoda: Galatheidae), challenged by DNA sequence information

We investigated the taxonomic status of two sympatric morphospecies of squat lobsters from southern South America (Beagle Channel, Strait of Magellan, and Burdwood Bank), Munida gregaria and Munida subrugosa, by DNA sequence analysis of three mitochondrial (mt)DNA gene fragments [416 bp of 16S rDNA(165), 566 bp of cytochrome c oxidase subunit I(COI) and 418 bp of NADH dehydrogenase subunit 1 (ND1)]; and the nuclear rDNA internal transcribed spacer (ITS) 1 (883-952 bp). We obtained a total of 79 sequences from 32 individuals. The 16S sequences of all M. gregaria and M. subrugosa were invariant and identical, whereas COI and ND1 showed 12 and 15 variable sites, respectively. These polymorphisms were shared between morphospecies. Interspecific Tamura-Nei distances for COI and ND1 sequences were 0.0024 and 0.0032, respectively, and were not significantly different from intraspecific distances (Kruskal-Wallis tests: P = 0.58 and P = 0.69, for COI and ND1, respectively). Similar to the results obtained from the mtDNA sequences, no relationship was found between the ITS1 maximum parsimony tree topology and the morphologic classification of specimens in M. gregaria and M. subrugosa. We conclude that M. gregaria and M. subrugosa from southern South America may either represent a case of a dimorphic species, or a case of incomplete lineage sorting. The fact that these two morphospecies did not show fixed differences over a total of 1947 bp analysed reinforces the hypothesis of a single dimorphic species. © 2008 The Linnean Society of London.Articl

Taxonomic status of two South American sympatric squat lobsters, Munida gregaria and Munida subrugosa (Crustacea: Decapoda: Galatheidae), challenged by DNA sequence information

We investigated the taxonomic status of two sympatric morphospecies of squat lobsters from southern South America (Beagle Channel, Strait of Magellan, and Burdwood Bank), Munida gregaria and Munida subrugosa, by DNA sequence analysis of three mitochondrial (mt)DNA gene fragments [416 bp of 16S rDNA(165), 566 bp of cytochrome c oxidase subunit I(COI) and 418 bp of NADH dehydrogenase subunit 1 (ND1)]; and the nuclear rDNA internal transcribed spacer (ITS) 1 (883-952 bp). We obtained a total of 79 sequences from 32 individuals. The 16S sequences of all M. gregaria and M. subrugosa were invariant and identical, whereas COI and ND1 showed 12 and 15 variable sites, respectively. These polymorphisms were shared between morphospecies. Interspecific Tamura-Nei distances for COI and ND1 sequences were 0.0024 and 0.0032, respectively, and were not significantly different from intraspecific distances (Kruskal-Wallis tests: P = 0.58 and P = 0.69, for COI and ND1, respectively). Similar to the results obtained from the mtDNA sequences, no relationship was found between the ITS1 maximum parsimony tree topology and the morphologic classification of specimens in M. gregaria and M. subrugosa. We conclude that M. gregaria and M. subrugosa from southern South America may either represent a case of a dimorphic species, or a case of incomplete lineage sorting. The fact that these two morphospecies did not show fixed differences over a total of 1947 bp analysed reinforces the hypothesis of a single dimorphic species. © 2008 The Linnean Society of London.Fil:Pérez-Barros, P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Guzmán, N.V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Lovrich, G.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Molecular phylogeny of South African abalone, its origin and evolution as revealed by two genes

The marine family Haliotidae (Mollusca: Gastropoda) includes approximately 56 extant abalone species found worldwide. None of these species are globally distributed while four areas of endemism (temperate Australia, South Africa, New Zealand and North Pacific) have been recognized. Phylogenetic relationships of 18 abalone species including five South African species were reconstructed using a combined data set containing sequence data of the mitochondrial NADH-dehydrogenase subunit 1 (ND1) gene and the nuclear hemocyanin gene. The molecular topologies confirmed former findings of two major abalone lineages with Northern and Southern Pacific distribution within the Haliotidae family. The phylogeny revealed all five South African species as a monophyletic group with a sister relationship to the Australian endemics clade. It further suggested a relatively recent radiation of the South African species and places it within the same evolutionary context as the Mediterranean/Atlantic and Australasian clades. Molecular phylogeny also revealed a split within the South African group as well as further speciation within one of the two subclades. Possible place of origin for South African abalone are discussed and ecological specialization, e.g. differential adaptation to environmental conditions, is proposed as the most likely scenario describing divergence within the South African clade. © 2012 Copyright Taylor and Francis Group, LLC

Microphotometrical image analysis of the subtelomeric region of T-banded endoreduplicated chromosomes of Chinese hamster ovary cells

Microphotometrical scanning and computer graphic image analysis were carried out to detect the distribution of chromatin densities in subtelomeric segments of T-banded endoreduplicated chromosomes of Chinese hamster ovary (CHO) cells. Chromatin density patterns detected with this method were similar to those previously found in CHO and normal human chromosomes. The highest chromatin densities were considered as marker segments which led to the detection of reciprocal changes of position in endoreduplicated chromosomes during cell spreading on the slide. The problem of the subtelomeric T-banding density patterns found in the endoreduplicated chromosomes and their relation to the structure and molecular composition of this region is briefly discussed.<br>Empregaram-se técnicas de escaneamento microfotométrico e análise de imagem gráfica computadorizada para detectar a distribuição de densidades de cromatina em segmentos subteloméricos de cromossomos endo-reduplicados com bandeamento T de células do ovário do hamster chinês (CHO). Os padrões de densidade de cromatina detectados com este método foram similares aos previamente encontrados em CHO e cromossomos humanos normais. As densidades de cromatina mais elevadas foram consideradas como segmentos marcadores que levaram à detecção de alterações recíprocas de posição de cromossomos endo-reduplicados durante o espalhamento das células na lâmina. O problema dos padrões de densidade de bandeamento T subteloméricos encontrados nos cromossomos endo-reduplicados e sua relação com a estrutura e a composição molecular desta região é discutido brevemente