Evaluation of genetic variability in the collared peccary Pecari tajacu and the white-lipped peccary Tayassu pecari by microsatellite markers

In this study, the microsatellite technique was used to evaluate the genetic variability in populations of collared and white-lipped peccaries kept in captivity. Six primers developed for domestic pigs were used and amplified in both species. They revealed the presence of five polymorphic loci and one monomorphic locus. The polymorphic loci included 4 of the 16 alleles in collared peccaries, and 3 of the 10 alleles in the white-lipped peccaries. Polymorphic information content (PIC) in both species and all the loci was highly informative. The probability of paternity exclusion (PEC), if one of the parents is known, was almost as high in white-lipped peccaries (95.53%) as in the collared (99,48%). The Fst values for collared (0.042) and white-lipped (0.1387) peccaries showed that both populations are not structured. The Fis values for all loci, except ACTG2 in white-lipped peccaries (-0.0275) and in both species (0.1985 to 0.9284 in collared peccaries and 0.3621 to 0.4754 in the white-lipped), revealed a high level of homozygosis, probably caused by inbreeding. Data on heterologous amplification and genetic variability in collared and white-lipped peccaries are presented for the first time

Some Recent Discoveries Concerning the Behavior of Platinum-Iridium Wires

The remarkable elastic properties of a certain platinum-iridium wire containing 40 per cent of iridium were first announced by Guthe. In his experiments the wire was used as the suspension of a torsion pendulum. Although the amplitudes of vibration were less than 50 degrees, a marked increase both in the period and in the logarithmic decrement accompanied the increase in the amplitude. Cylinders of equal mass but of different moments of inertia were suspended from the wire, set in vibration, and timed, but as a result of these experiments no change was observed in the logarithmic decrement-amplitude curves. This absence of any effect led to the supposition that the damping was proportional to the amplitude, and independent of the velocity

Distribuição diferencial da heterocromatina constitutiva em duas espécies da aranha marrom: Loxosceles intermedia e L. laeta (Araneae, Sicariidae) da região metropolitana de Curitiba, PR (Brasil)

As aranhas do gênero Loxosceles são pequenas, apresentam distribuição cosmopolita, hábitos noturnos e não agressivos. Na região metropolitana de Curitiba, são encontradas duas espécies de aranha marrom: L. intermedia e L. laeta. A primeira é a mais abundante e responsável, nos últimos anos, por inúmeros acidentes denominados de Loxoscelismo. O presente trabalho tem como objetivo estudar citogeneticamente estas aranhas, através de técnicas de coloração comum (Giemsa) e de bandeamento C, em células prémeióticas, meióticas e embrionárias. Exemplares foram coletados em domicílios ou fornecidos pelo Laboratório Interdisciplinar de Pesquisa em Animais Peçonhentos (LIPAPE). As preparações citológicas foram obtidas a partir de testículos de aranhas adultas ou de células embrionárias. Os dados mostram que as duas espécies são cariotipicamente similares e caracterizam-se por apresentar um número diplóide diferenciado entre os sexos: 2n=23 nos machos e 24 nas fêmeas. Esta diferença é devida ao sistema cromossômico de determinação sexual múltiplo, do tipo X1X2Y (machos) e X1X1X2X2 (fêmeas). A aplicação da técnica de bandeamento C revelou que em L. intermedia poucos cromossomos apresentam banda pericentromérica, incluindo os sexuais, X1 e X2, ao passo que em L. laeta, diferentemente, todos os cromossomos do genoma apresentaram bandas pericentroméricas conspícuas. Em ambas as espécies, o cromossomo Y mostrou-se quase que totalmente heterocromático. Este tipo de bandeamento, além de ser inédito em Loxosceles, revelou ser uma importante característica na diferenciação cariotípica entre L. intermedia e L. laeta. ABSTRACT The genus Loxosceles includes cosmopolitan small spiders, which have nocturnal and non-agressive habits. Two species of brown spiders are found in the metropolitan area of Curitiba: L. intermedia and L. laeta. The first one is more abundant, and responsible for many accidents (Loxoscelism). The aim of this study is to analyze cytogenetically these spiders, through conventional (Giemsa) and c-banding techniques in pre-meiotic, meiotic and embrionary cells. The specimens were collected in houses or kindly provided by Laboratório Interdisciplinar de Pesquisa em Animais Peçonhentos (LIPAPE). Cytological preparations were obtained from embrionic cells or from testis of adult specimens. The data showed that both species are karyotipically similar, and had different diploid numbers in males and females (2n=23 and 2n=24, respectively). This difference is the result of a multiple sex chromosome system (X1X2Y/ X1X1X2X2). The use of c-banding technique revealed that a few chromosomes of L. intermedia showed pericentromeric blocks of constitutive heterochromatin, including gonosomes X1 and X2. On the other hand, all the chromosomes of L. laeta showed conspicuous pericentromeric C-positive segments. In both species, the Y chromosome revealed to be almost tottaly heterochromatic. This study described the result of the use of c-banding technique for the first time in Loxosceles, which revealed an important karyotypical distintion between L. intermedia and L. laeta. RÉSUMÉ Les araignées du genre Loxosceles sont petites, présentent une distribution cosmopolite, ont des habits nocturnes et ne sont pas agressives. Dans la region métropolitaine de Curitiba, on y trouve deux espèces de laraignée marron: L. intermedia et L. laeta. La premiere cest la plus abondante et responsable, dans les dernières années par des nombreux accidents connus sous le nom de loxoscelisme. Le but de cet article est celui détudier la cytogénétique de ces araignées, par moyen des colorants ordinaires dont le Giemsa et par le technique du bandage C en utilisant des cellules C, des cellules pré-meyotiques, meyotiques et embryonnaires. Des échantillons ont été soit obtenues dans des maisons particulières, soit fournies par le Laboratório Interdisciplinar de Pesquisa em Animais Peçonhentos (LIPAPE), et les préparations cytologiques obtenues des testicules des adultes ou des cellules embryonnaires. Les résultats montrent que les deux espèces sont similaires du point de vue caryotype et se caractérisent par avoir un numéro diploíde différencié entre les sexes : 2n=23 dans les mâles et 24 dans les femelles. Cette différence dans le numéro diploïde est due ao système chromosomique de détermination sexuelle multiple du type X1X2Y (mâles)/X1X1X2X2 (femelles). Lutilisation du bandage C a montré que chez L. intermedia pas beaucoup de chromosomes présentent la bande pericentrométrique, y compris les sexuels X1 et X2. Par contre, chez L. laeta, tous les chromosomes du génome présentent des bandes pericentrométriques visibles. Dans toutes les deux, le chromosome Y sest montré presque hétérochromatique. Cet type de bandage, en plus dinédite chez Loxosceles, sest montré aussi important dans la séparation caryotypique entre L. intermedia et L. laeta

Alterações cromossômicas inesperadas em Tayassu tajacu (Artiodactyla: tayassuidae) de cativeiros

Wild animals have been used as bioindicators in situations in which the environment was exposed to chemical agents. In general, chemical agents may induce chromosomal aberrations, such as breaks and gaps. The peccary, Tayassu tajacu is a pig relative that exhibits a very stable karyotype with the only described alterations being of the form of the X chromosome. Chromosomal gaps and breaks were observed at high frequencies during cytogenetics analyses. These alterations were observed in the chromosomes autossomics. Reviews of the literature and of the data described herein suggests that an vermifuge, the ivermectin base, was the most likely cause of these chromosomal alterations.Os animais silvestres têm sido utilizados como bioindicadores quando o ambiente é exposto a estressores químicos. Em geral, os agentes químicos podem induzir às alterações cromossômicas dos tipos falhas e quebras. Tayassu tajacu, é uma espécie aparentada dos porcos verdadeiro e apresenta uma grande estabilidade cariotípica. As únicas alterações descritas são em relação a forma do cromossomo X. Foram observadas falhas e quebras cromossômicas durante as análise citogenética. Estas alterações foram detectadas em cromossomos autossômicos. Levantamentos realizados na literatura associados as dados observados nos exemplares estudados, indicam um vermífugo, a base de ivermectina, como o possível causador dessas alterações cromossômicas

Análises cromossômicas e filogenéticas em algumas espécies de roedores da região sul do Brasil

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Interrelationship between Ectoparasites and Wild Rodents from Tijucas do Sul, State of Paraná, Brazil

Sixteen species of ectoparasites were collected from 50 wild rodents, from August 1990 to August 1991, in an area of Araucaria augustifolia forest, in the municipality of Tijucas do Sul, State of Paraná, Brazil. Ectoparasites infested 98% of the rodents, with the highest indices of infestation found in the dry-cool season. Species that occurred in single or multiple infestations were recorded. Ectoparasite/host associations were significant (p<0.01) for Gigantolaelaps wolffsohni/Oryzomys nigripes, Polygenis pradoi/Oxymycterus sp. and Amblyopinus sp./Oxymycterus sp. The following represent new host records: Polygenis (Polygenis) tripus from Akodon serrensis and Hoplopleura sciuricola from Sciurus aestuans. New geographic records are given for two species of flea and one sucking lice

Description of the karyotype of Rhagomys rufescens Thomas, 1886 (Rodentia, Sigmodontinae) from Southern Brazil Atlantic forest

Rhagomys rufescens (Rodentia: Sigmodontinae) is an endemic species of the Atlantic forest from Southern and Southeastern Brazil. Some authors consider Rhagomys as part of the tribe Thomasomyini; but its phylogenetic relationships remain unclear. Chromosomal studies on eight specimens of Rhagomys rufescens revealed a diploid number of 2n = 36 and a number of autosome arms FN = 50. GTG, CBG and Ag-NOR banding and CMA3/DAPI staining were performed on metaphase chromosomes. Eight biarmed and nine acrocentric pairs were found in the karyotype of this species. The X and Y chromosomes were both acrocentric. Most of the autosomes and the sex chromosomes showed positive C-bands in the pericentromeric region. The X chromosome showed an additional heterochromatic block in the proximal region of the long arm. Nucleolus organizer regions (NORs) were located in the pericentromeric region of three biarmed autosomes (pairs 4, 6 and 8) and in the telomeric region of the short arm of three acrocentrics (pairs 10, 12 and 17). CMA3/DAPI staining produced fluorescent signals in many autosomes, especially in pairs 4, 6, and 8. This study presents cytogenetic data of Rhagomys rufescens for the first time