Phan Van Ngan

Biomonitoring of the genotoxic potential (micronucleus and erythrocyte nuclear abnormalities assay) of the Admiralty Bay water surrounding the Brazilian Antarctic Research Station “Comandante Ferraz,” King George Island

The micronucleus (Mn) and other kinds of erythrocyte nuclear abnormality (ENA) assays were used to assess the genotoxic potential of the seawater in front of the Brazilian Antarctic Research Station “Comandante Ferraz” (King George Island). In two consecutive summers, the fish Trematomus newnesi was exposed to the seawater in front of the fuel storage tanks and the sewage discharge outlet of the Station in laboratory bioassays and in situ caging assays. After the exposure, frequencies of ENA and Mn were scored on blood smears. Significantly higher Mn and ENA frequencies in relation to those of the controls were observed in fish exposed to both types of water, in both types of experiment. Seawater in front of the fuel tanks and sewage discharge outlet at the Station was found to induce the formation of micronuclei and other ENAs, indicators of genotoxicity. The need for further investigation and the suitability of the methods for screening mutagenic pollution in polar waters are discussed.

EROD activity and genotoxicity in the seabob shrimp Xiphopenaeus kroyeri exposed to benzo[a]pyrene (BaP) concentrations

Seabob shrimp Xiphopenaeus kroyeri is a marine species that lives in shallow waters of coastal environments, often impacted by polycyclic aromatic hydrocarbons (PAH) pollution. In the present study, seabob shrimp were exposed for 96 h to benzo[a]pyrene (BaP) at the nominal concentrations of 100, 200, 400 and 800 microg-L(-1). Animals of the control groups were exposed either to clean water or to the BaP-carrier (DMSO). At the end of the exposures, muscle tissues were sampled for BaP uptake assessment and hepatopancreas and hemolymph for EROD enzyme activity and hemocytes DNA damage, respectively. EROD activity and DNA damage increased significantly as a function of BaP exposure concentrations. Significant correlations between BaP uptake and both EROD activity and DNA damage suggest that they can be used as suitable tools for integrated levels of study on the biomarkers of PAH exposure.

The effect of salinity on the osmo-ionic regulation of Macrobrachium carcinus (Linnaeus)

1. 1. The effects of salinity (0, 7, 14, 21, 28 and 35‰) on haemolymph osmotic, Ca2+, K+ and Na+ regulation in Macrobrachium carcinus were investigated. 2. 2. M. carcinus is a strong hyperosmotic regulator in fresh or low salinities (0–21‰), while at high salinities (28–35‰) it is a hypoconformer. 3. 3. Na+ haemolymph concentrations stayed fairly constant in salinities from 0 to 14‰ and increased slightly with the increase in the external sodium ion concentration. 4. 4. K+ haemolymph concentrations increased slightly from 0 to 21‰ and sharply in salinities beyond this range. 5. 5. Ca+ haemolymph concentrations were hyperionic to those of the media in all salinities. 6. 6. These results are compared with those of the Malaysian prawn, M. rosenbergii.

Preliminary study on chromosomes of Antarctic krill, Euphausia superba Dana

SummaryMeiotic chromosomes of antarctic krill, Euphausia superba Dana, collected at Admiralty Bay, are described and the method used to obtain this genetic material is reported. Forty seven dividing meiotic nuclei at diakinesis and metaphase I from seminal glands of four males were examined, all with n= 17 bivalents. The results were compared with those obtained by other workers using krill specimens from the opposite side of the Antarctic continent and apparent differences in chromosome numbers were observed. Possible reasons for these differences and the potential for using cytogenetic techniques to study populations of krill are discussed.

Estudos cariotípicos de peixes da família Sciaenidae (Teleostei, Perciformes) da região de Cananéia, SP, Brasil: 2. Sobre o cariótipo de Menticirrhus americanus (Linnaeus, 1758)

Estudou-se o cariotipo de Menticirrhus americanus (Linnaeus, 1758), peixes teleosteos da familia Sciaenidae, coletados na regiao estuarino-lagunar de Cananeia, SP, Brasil. Foram realizadas preparacoes de cromossomos mitoticos e meioticos e ensaios de bandeamentos C e G. O numero diploide encontrado para a especie foi de 2n = 48 cromossomos, tipo t cujos tamanhos variaram entre 3,18 µm e 1,47 µm, em media, do maior para o menor par. O primeiro par de homologos apresenta uma constriccao secundaria no terco superior dos cromossomos. O numero haploide encontrado foi n = 24. O conteudo diploide de DNA foi de 1,57 ± 0,03 picogramas por celula. Nao se obteve padrao nitido de bandas G, mas a aplicacao da tecnica facilitou a identificacao de alguns pares adjacentes e a visualizacao da constriccao secundaria. Bandas C localizam-se, principalmente, nas regioes pericentrometricas.

Environmental Assessment of Admiralty Bay, King George Island, Antarctica

Monitoring has been developed by Antarctic Programmes such as Antarctic New Zealand (www.antarcticanz.govt.nz) and the US Antarctic Programme (USAP) (http://www.usap.gov) considering expansion of human activities and inevitable environmental.

Chromosomes of the Antarctic amphipod Waldeckia obesa Chevreux

Mitotic and meiotic chromosomes of the Antarctic lysianassoid amphipod Waldeckia obesa are described. The modal chromosome number is n = 25 and 2n = 50. The potential applications of cytogenetical studies in this group are discussed.

Assessment of trophic transfer of benzo(a)pyrene genotoxicity from the post-larval pink shrimp F. brasiliensis to the juvenile Florida pompano T. carolinus.

In the present study, the polycyclic aromatic hydrocarbon (PAH) genotoxicity was investigated in a one-step predator-prey relationship with the trophic-related marine species. Florida pompanos were fed for 5 and 10 days with pink shrimp post larvae previously exposed to benzo(a)pyrene (BaP) concentrations. Parent BaP body burden was measured in samples of Farfantepenaeus brasiliensis. BaP metabolites were determined in bile samples of Trachinotus carolinus and DNA damage was assessed through the comet and erythrocyte nuclear abnormalities (ENAs) assays in fish erythrocytes. BaP body burden increased significantly with the PAH concentration in pink shrimp PLs as well as the fish bile BaP metabolites. Both, comet and ENAs assays indicated significant increase on erythrocyte DNA damage of Florida pompanos fed with BaP-exposed pink shrimp on both feeding periods. The trophic route of BaP genotoxicity is discussed as well as the PAH biotransformation as the inducing mechanism for the DNA damages observed.

Effect of body size, temperature and starvation on oxygen consumption of antarctic krill Euphausia superba

O consumo de oxigenio de rotina de krll foi avaliado como uma forma de mensurar seu metabolismo e determinar os efeitos do tamanho, da temperatura e do jejum sobre o mesmo. Nao foram detectadas diferencas significativas no consumo total do animal apos 1, 3, 5 e 7 dias de jejum. As respostas do metabolismo de krill em funcao da variacao da temperatura demonstraram a existencia de uma faixa de independencia, de O°Ca 1°C, na qual a temperatura nao exerce nenhum efeito sobre o metabolismo. De 1°C a 4°C o metabolismo aumenta rapidamente em funcao da temperatura. Houve um aumento significativo no consumo de oxigenio em funcao do peso. A equacao que relaciona o consumo com o peso umido e dada pela formula Log Qoz = 2,061 + 0,987x LogW, com r=0,86. A declividade da regressao foi menor que a unidade (b= 0.987), indicando que o consumo de oxigenio por unidade de peso e maior em animais menores. A media da taxa metabolica de 164 krill a O°Ce 733,24 J- µlO2g (peso seco)-1 h-1. A taxa metabolica e de 1129,67 J- µlO2g (peso seco)-1 h-1 para animais pequenos (13 a 19 mg de peso seco) e 636,16 J- µlO2g (peso seco)-1 h-1 para animais maiores (160 a 169 mg de peso seco). Demonstrou-se que o metabolismo do krill esta relacionado ao periodo de adaptacao e ao tipo de respirometro. Periodos prolongados de adaptacao ocasionaram efeitos adversos sobre o metabolismo. A media do consumo de oxigenio foi cerca de 3 vezes mais elevada em respirometros com agitador do que em câmaras seladas simples.

Electrophoretic study on intraspecific variations and interspecific relationships of marine catfishes (Siluriformes, Ariidae) of Cananéia (São Paulo, Brazil): 1. General proteins of eye-lens and skeletic muscle

Cellulose acetate electrophoresis of eye-lens proteins and Polyacrylamide flat gel electrophoresis of skeletic muscle proteins of six species of marine catfishes were carried out. Genetic polymorphism only occured at one locus of the electropherograms of eye-lens of Cathorops spixii. Ontogenetic variations in the relative concentration of bands were found in the electropherograms of eye-lens and skeletic muscle proteins. The six species of catfishes can be identified by means of quantitative and qualitative differences in the electropherograms. Coefficients of similarity were determined by the band-counting method and UPGMA dendrograms were constructed to illustrate the interspecific relationships among the species.