Laura I. Weber

Genetic variability and interpopulational differentiation of Artemia strains from South America

Seven Artemia samples from three South American countries (Chile, Brazil, Peru) were studied by starch electrophoresis with the aim of comparing levels of genetic variation and genetic similarity to representative populations of A. franciscana (San Francisco Bay, California, USA) and A. persimilis (Buenos Aires, Argentina), which are species endemic to the New World. Based on the analysis of 22 loci, parameters measuring genetic variability were, for some populations, found to be among the highest reported for Artemia so far. The percentage of polymorphic loci varied from 31.8% (Piura, Peru; Buenos Aires) to 50% (Los Vilos and Salar de Atacama, Chile), while the observed heterozygosity varied from 0.025 (Piura) to 0.165 (Los Vilos, Chile). A dendrogram based on Neis genetic distance (D) produced four major groups. The Argentinian form, A. persimilis; the San Francisco Bay strain together with samples from Brazil (Macau and Rio Grande do Norte) and Chile (Pichilemu and Salar de Atacama); two coastal populations from Chile (Los Vilos and Iquique) and the sample from Peru (Piura). These four groups have inter-group D values that are, in some cases, far above those normally associated with conspecific populations.

Microsatellite genotyping from faeces of Lontra longicaudis from southern Brazil

A lontra neotropical de rio Lontra longicaudis (Olfers, 1818), cujo estado de conservacao e ainda desconhecido, foi estudada geneticamente na Estacao Ecologica do Taim e nas margens do arroio Vargas, RS, sul do Brasil. Amostras de fezes foram coletadas e o DNA foi extraido por um metodo de silica-guanidina. Cinco locos de microsatelites foram amplificados por PCR utilizando primers heterologos previamente descritos para Lutra lutra (Linnaeus, 1758). Dezesseis amostras de fezes de um total de 29 coletadas no Taim e onze das 14 obtidas no arroio Vargas contiveram DNA suficiente para prosseguir com a analise genetica. Um total de 49 alelos foram obtidos, dos quais 18 foram exclusivos de individuos do Taim e 17 exclusivos dos individuos do arroio Vargas. Em tres locos (Lut715, Lut733 e Lut818) os individuos das duas localidades compartilharam o alelo mais comum. Foi encontrada uma alta diversidade genetica (NeTaim=4,1; HoTaim=0,299; HeTaim=0,681; NeVargas=4,9; HoVargas=0,355; HeVargas=0,724), sendo esta maior no arroio Vargas. Uma alta e significativa deficiencia de heterozigotos foi observada em quase todos os locos de acordo com o teste do χ2. O teste do χ2 de homogeneidade genetica (P<0,001) mostrou diferencas significativas entre as frequencias alelicas das duas localidades. A genotipagem para mais de um loco foi possivel em 81,5% das amostras, sendo que somente em 37% destes foi possivel a genotipagem para mais de tres locos. Foi encontrado um baixo grau de parentesco entre os individuos do Taim (R=0,055±0,310), sendo este ainda menor nos individuos do arroio Vargas (R=-0,285±0,440). O grau significativo de diferenciacao genetica (I=0,890; FST=0,059) entre os individuos do Taim e do arroio Vargas sugere a existencia de mais de uma populacao de lontras no extremo sul do Brasil, que provavelmente estejam associadas aos diferentes corpos de agua existentes nesta regiao: a Lagoa Mirim e o sistema de lagoas Cauiva/Flores/Mangueira. A alta diversidade genetica e o baixo grau de parentesco dos individuos do arroio Vargas nos leva a considerar a possibilidade que o arroio Vargas possa estar atuando como um corredor entre estes corpos de agua para a dispesao das lontras.

TESTING A SUBTYPE-SPECIFIC GP41 AMPLIFICATION METHOD FOR GENOTYPING INDIVIDUALS INFECTED BY HUMAN IMMUNODEFICIENCY VIRUS TYPE-1 IN THE BRAZILIAN POPULATION OF ITAJAÍ, SOUTH BRAZIL

The method used by YAGYU et al. for the subtype-specific polymerase chain reaction (PCR) amplification of the gp41 transmembrane region of the human immunodeficiency virus type-1 (HIV-1) env gene, was tested. HIV-1 proviral DNA from 100 infected individuals in Itajaí, South Brazil was used to analyze this method. Seventy individuals were determined according to this method as having PCR products at the expected size for subtypes B, C, D and F. Of these individuals, 26 (37.1%) were observed as having the expected amplification for subtype C, and 42 (60%) were observed as having the expected products for subtypes B and D. Of the subtype B and D amplicons, 16 (22.9%) were classified as subtype D, and 26 (37.1%) were classified as subtype B. Two individuals (2.9%) had amplicons that were observed after subtype F-specific amplification was performed. Sequencing and comparing the patient sequences to reference sequences confirmed the classification of sequences of subtypes C and B. However, sequences that were falsely determined as being D and F in the PCR assay were determined as being subtypes C and B, respectively, by sequence analysis. For those individuals from whom no amplified products were obtained, a low viral load that was indicated in their patient history may explain the difficulty in subtyping by PCR methods. This issue was demonstrated by the results of ANOVA when testing the effect of viral load on the success of PCR amplification. The alignment of the obtained sequences with HIV-1 reference sequences demonstrated that there is high intra-subtype diversity. This indicates that the subtype-specific primer binding sites were not conserved or representative of the subtypes that are observed in the Brazilian populations, and that they did not allow the correct classification of HIV-1 subtypes. Therefore, the proposed method by YAGYU et al. is not applicable for the classification of Brazilian HIV-1 subtypes.

Effects of water-soluble fraction of petroleum on growth and prey consumption of juvenile Hoplias aff. malabaricus (Osteichthyes: Erythrinidae)

The influence of the water-soluble fraction of petroleum (WSF) on prey consumption and growth of juvenile trahira Hoplias aff. malabaricus was investigated. Juveniles were submitted to either WSF or Control treatment over 28 days, and jewel tetra Hyphessobrycon eques adults were offered daily as prey for each predator. Total prey consumption ranged from 16 to 86 individuals. Despite the initially lower prey consumption under WSF exposure, there were no significant differences in overall feeding rates between the two treatments. Water-soluble fraction of petroleum had a negative effect on the growth in length of H. aff. malabaricus juveniles. Although unaffected, prey consumption suggested a relative resistance in H. aff. malabaricus to WSF exposition and the lower growth of individuals exposed to WSF than the Control possibly reflects metabolic costs. The implications of the main findings for the individual and the food chain are discussed, including behavioral aspects and the role played by this predator in shallow aquatic systems.