Beasley

ABSTRACT -This paper records for the first time the presence of Corbicula fluminea (Philipi, 1844) in the Brazilian Amazon Basin. This exotic bivalve was found in localities on the Amazonas, Pará and Tocantins rivers. Density and population size structure were measured in some localities. Mean density is between 6.66 and 7.3 individuals m -2 . Population size structure and the dates of the first records suggest that the introductions may have occurred between 1997 and 1998. The introductions may have been mediated by ocean-going vessels visiting the ports of Manaus and Belém. The potential impact of the invasion on native freshwater bivalves is discussed along with the need for monitoring and prevention of further introductions of non-indigenous bivalves in Brazil

Polimorfismos bioquímicos e o relacionamento genético entre raças suínas brasileiras e estrangeiras criadas no Brasil

The genetic variability of 14 protein systems encoded by 15 structural loci was investigated in blood samples of Piau and Caruncho pig breeds. The results were compared with those obtained previously for samples of Landrace, Large White, Duroc and Mouro. The degree of genetic variability obtained for Piau (He=0.114) was similar to that estimated for other breeds reared in Brazil (Landrace, He=0.116; Large White, He=0.119; Duroc, 0.095; Mouro, He= 0.130). Caruncho showed the lowest variability (He= 0.056). The gene frequencies at the polymorphic loci were used to evaluate the usefulness of these systems for paternity testing and the combined probabilities of paternity exclusion were estimated at 58% for the Piau and 36% for the Caruncho breed. Analysis of genetic distances revealed that the greatest similarity observed was between Piau and Landrace (D=0.042). Caruncho showed the greatest divergence among all breeds compared and the distances between this breed and others range from 0.107 (with Landrace) to 0.176 (with Duroc). The tree constructed by UPGMA and Rogers Distance gave a topology in which Piau and Mouro joined with the European breeds (Landrace and Large White) whereas Caruncho was separated from all the other breeds. The results of the analysis of the Caruncho samples should be interpreted with caution since the number of animals studied was small.Foi investigada a variabilidade genética de 14 sistemas protéicos codificados por 15 locos estruturais em amostras de sangue de suínos das raças Piau e Caruncho. Os resultados foram comparados com àqueles obtidos previamente para amostras de Landrace, Large White, Duroc e Mouro. O grau de variabilidade genética obtida para Piau (He=0,114) foi similar àquelas estimadas para outras raças criadas no Brasil (Landrace, He=0,116; Large White, He=0,119; Duroc, 0,095; Mouro, He= 0,130). Caruncho apresentou a menor variabilidade (He= 0,056). A partir das freqüências gênicas dos locos polimórficos, foi calculada a eficiência de cada sistema para testes de paternidade e as probabilidades combinadas de exclusão de paternidade foram estimadas em 58% para Piau e 36% para Caruncho. Análises das distâncias genéticas revelaram que a raça mais próxima da Piau foi a Landrace (D=0,042). Caruncho apresentou as maiores divergências em relação a todas as raças comparadas, que variaram de 0,107 (com Landrace) a 0,176 (com Duroc). A árvore construída através de UPGMA e Distância de Rogers mostrou uma topologia na qual Piau e Mouro se uniram as raças Européias (Landrace e Large White), e Caruncho está separado de todas as demais raças. Os resultados das análises das amostras de Caruncho devem ser interpretados com cautela, uma vez que o número de animais estudados foi pequeno

Detection of mitochondrial DNA heteroplasmy suggests a doubly uniparental inheritance pattern in the mussel Mytella charruana

The unusual type of mitochondrial DNA (mtDNA) transmission in which females pass on their mtDNA F to both sons and daughters, and males pass on their mtDNA M to their sons, is termed Doubly Uniparental Inheritance (DUI) and has been observed in several bivalve mollusk families, including the Mytilidae. The present study found mitochondrial heteroplasmy in Mytella charruana, a tropical estuarine mytilid, which is most likely due to the occurrence of DUI. Cytochrome oxidase c subunit I (COI) sequences provide evidence for the presence of mtDNA M in the gonad and adductor muscle of male M. charruana. Intraspecific COI mtDNA F and mtDNA M mitotype divergence (p-distances) in M. charruana ranged from 20.5% to 20.8%. COI phylogenetic trees suggest that mtDNA M arose before M. charruana, Perna perna and Mytella guyanensis split, though independently of the DUI event that occurred in the genera Mytilus and Brachidontes. The comparison of COI gene products of mtDNA M among M. charruana and other bivalves, including mytilids, has shown that they all have important differences, suggesting independent evolutionary changes in their male COI lineages.(Detecção de heteroplasmia no DNA mitocondrial sugere um padrão de herança dupla uniparental em mexilhões Mytella charruana). Um tipo de transmissão não usual de herança do DNA mitocondrial (mtDNA), na qual as fêmeas passam os seus mtDNA F aos filhos e às filhas e os machos passam os seus mtDNA M para os seus filhos machos, é conhecido por herança dupla-uniparental e tem sido observada em várias famílias de moluscos bivalves, incluindo a Mytilidae. O presente estudo mostrou a ocorrência de heteroplasmia mitocondrial em Mytella charruana, um mitilídeo estuarino tropical, provavelmente devido a herança dupla uniparental. Sequências da citocromo oxidase c subunidade I (COI) mostraram que o mtDNA M está presente nas gônadas e nos músculos adutores dos machos de M. charruana. As divergências intraespecíficas (distância-p) entre as sequências de COI dos mitótipos mitocondriais mtDNA F e mtDNA M em M. charruana variaram de 20.5% a 20.8%. As árvores filogenéticas baseadas em COI sugerem que o mtDNA M surgiu antes da separação das espécies M. charruana, Perna perna e Mytella guyanensis, independentemente do evento DUI que ocorreu nos gêneros Mytilus e Brachidontes. A comparação dos produtos do gene mtDNA M de M. charruana e de outros bivalves, incluindo mitilídeos, mostrou que eles têm importantes diferenças, sugerindo mudanças evolucionárias independentes em suas linhagens masculinas de COI

Molecular phylogeny of the genus Saguinus (Platyrrhini, Primates) based on the ND1 mitochondrial gene and implications for conservation

The systematics of the subfamily Callitrichinae (Platyrrhini, Primates), a group of small monkeys from South America and Panama, remains an area of considerable discussion despite many investigations, there being continuing controversy over subgeneric taxonomic classifications based on morphological characters. The purpose of our research was to help elucidate the phylogenetic relationships within the monkey genus Saguinus (Callitrichinae) using a molecular approach to discover whether or not the two different sections containing hairy-faced and bare-faced species are monophyletic, whether Saguinus midas midas and Saguinus bicolor are more closely related than are S. midas midas and Saguinus midas niger, and if Saguinus fuscicollis melanoleucus and Saguinus fuscicollis weddelli really are different species. We sequenced the 957 bp ND1 mitochondrial gene of 21 Saguinus monkeys (belonging to six species and nine morphotypes) and one Cebus monkey (the outgroup) and constructed phylogenetic trees using maximum parsimony, neighbor joining, and maximum likelihood methods. The phylogenetic trees obtained divided the genus Saguinus into two groups, one containing the small-bodied species S. fuscicollis and the other, the large-bodied species S. mystax, S. leucopus, S. oedipus, S. midas, S. bicolor. The most derived taxa, S. midas and S. bicolor, grouped together, while S. fuscicollis melanoleucus and S. f. weddelli showed divergence values that did not support the division of these morphotypes into subspecies. On the other hand, S. midas individuals showed divergence compatible with the existence of three subspecies, two of them with the same morphotype as the subspecies S. midas niger. The results of our study suggest that there is at least one Saguinus subspecies that has not yet been described and that the conservation status of Saguinus species and subspecies should be carefully revised using modern molecular approaches

Molecular identification, phylogeny and geographic distribution of Brazilian mangrove oysters (Crassostrea)

Oysters (Ostreidae) manifest a high degree of phenotypic plasticity, whereby morphology is of limited value for species identification and taxonomy. By using molecular data, the aim was to genetically characterize the species of Crassostrea occurring along the Brazilian coast, and phylogenetically relate these to other Crassostrea from different parts of the world. Sequencing of the partial cytochrome oxidase c subunit I gene (COI), revealed a total of three species of Crassostrea at 16 locations along the Brazilian coast. C. gasar was found from Curuçá (Pará state) to Santos (São Paulo state), and C. rhizophorae from Fortim (Ceará state) to Florianópolis (Santa Catarina state), although small individuals of the latter species were also found at Ajuruteua beach (municipality of Bragança, Pará state). An unidentified Crassostrea species was found only on Canela Island, Bragança. Crassostrea gasar and C. rhizophorae grouped with C. virginica, thereby forming a monophyletic Atlantic group, whereas Crassostrea sp. from Canela Island was shown to be more similar to Indo-Pacific oysters, and either arrived in the Atlantic Ocean before the convergence of the Isthmus of Panama or was accidentally brought to Brazil by ship

Significant genetic differentiation among populations of Anomalocardia brasiliana (Gmelin, 1791): A bivalve with planktonic larval dispersion

Four Brazilian populations of Anomalocardia brasiliana were tested for mutual genetic homogeneity, using data from 123 sequences of the mtDNA cytochrome oxidase c subunit I gene. A total of 36 haplotypes were identified, those shared being H3 (Canela Island, Prainha and Acupe) and both H5 and H9 (Prainha and Acupe). Haplotype diversity values were high, except for the Camurupim population, whereas nucleotide values were low in all the populations, except for that of Acupe. Only the Prainha population showed a deviation from neutrality and the SSD test did not reject the demographic expansion hypothesis. Fst values showed that the Prainha and Acupe populations represent a single stock, whereas in both the Canela Island and Camurupim stocks, population structures are different and independent. The observed structure at Canela Island may be due to the geographic distance between this population and the remainder. The Camurupim population does not share any haplotype with the remaining populations in northeastern Brazil. The apparent isolation could be due to the rocky barrier located facing the mouth of the Mamanguape River. The results highlight the importance of wide-scale studies to identify and conserve local genetic diversity, especially where migration is restricted

The occurrence of the Asian Clam Corbicula fluminea in the lowe amazon basin

This paper records for the first time the presence of Corbicula fluminea (Philipi, 1844) in the Brazilian Amazon Basin. This exotic bivalve was found in localities on the Amazonas, Pará and Tocantins rivers. Density and population size structure were measured in some localities. Mean density is between 6.66 and 7.3 individuals m-2. Population size structure and the dates of the first records suggest that the introductions may have occurred between 1997 and 1998. The introductions may have been mediated by ocean-going vessels visiting the ports of Manaus and Belém. The potential impact of the invasion on native freshwater bivalves is discussed along with the need for monitoring and prevention of further introductions of non-indigenous bivalves in Brazil