Avaliação da eficiência do tratamento de esgoto doméstico pelo teste do micronúcleo em Oreochromis niloticus (Cichlidae) / Evaluation of the domestic wastewater treatment efficiency by micronucleus test on Oreochromis niloticus (Cichlidae)

RESUMO Este estudo teve por objetivo avaliar a eficiência no tratamento do esgoto doméstico de uma cidade do interior paulista, pela análise de micronúcleos e anormalidades nucleares nos eritrócitos de tilápias expostas ao efluente bruto e ao tratado. Duas coletas foram realizadas: uma na estação chuvosa e outra na estação seca. Foram utilizados três aquários de 20 L nos experimentos, com cinco peixes cada. No primeiro, os animais foram expostos à água de poço artesiano (controle negativo); no segundo, ao esgoto bruto diluído; no terceiro, ao esgoto após tratamento. Decorrido o tempo de exposição (72 h), coletou-se o sangue desses animais para obtenção de lâminas de esfregaço. Os resultados obtidos mostraram efeitos genotóxicos e mutagênicos do efluente bruto, em ambas as coletas; porém, esses efeitos não foram significativos após o tratamento do esgoto, o que mostra que o processo utilizado no tratamento foi eficiente para minimizar tais efeitos.

ABSTRACT This study aimed at evaluating the efficiency in the domestic wastewater treatment from a city of Sao Paulo State (Brazil), by micronuclei and nuclear abnormalities analysis in erythrocytes of tilapias exposed to raw and treated wastewater. Two samples were collected. Three aquariums of 20 L, with five fish each, were used in the bioassays. In the first, the animals were exposed to the artesian water (negative control); in the second, to the diluted raw wastewater; and in the third, to after wastewater treatment. After the exposure time (72 h), the blood was collected for preparing the smear slides. The results showed genotoxic and mutagenic effects of the raw wastewater in both samples, showing that the process used was efficient to minimize these effects.

Effectiveness of estradiol valerate on sex reversion in Astyanax altiparanae (Characiformes, Characidae)

The objective of this study was to evaluate the effectiveness of estradiol valerate in an attempt to feminize the male Astyanax altiparanae. One thousand newly-hatched larvae were randomly distributed in four incubators. During a period of 30 days, estradiol valerate was administered in different dosages (20, 40, and 80 mg/kg of diet); the control group did not receive hormone in the diet. After 161 days of hatching, biometry was performed on 50 fishes per treatment group, and the gonads were analyzed. The hormone treatments were effective in feminizing A. altiparanae, achieving 70-76% of the desired sex, while the control treatment had 44% females. The hormone did not affect the growth of fish.

Mineralized bodies in the fat body of rhinocricus padbergi (Diplopoda)

The fat body is a loosely packed tissue distributed throughout the body cavities of millipedes. The mainfunction of this tissue is the storage of lipids, glycogen, proteins and uric acid and also serves as a site forthe permanent storage for excretion products. In this work, we examined the ultrastructure of the mineralizedbodies found in the fat body of the millipede Rhinocricus padbergi. The mineralized bodies were sphericalbodies that varied in structural organization within a single cell: some consisted of several concentric layers ofamorphous material while others were surrounded by a layer of electron-dense material intimately associatedwith the surrounding membrane. The histochemical and ultrastructural results suggested that these mineralizedbodies are involved in the accumulation of calcium and uric acid. The large number of these structures foundin the fat body of millipedes may be a consequence of these animals´ diet since they overturn soil rich in largeamounts and/or variety of minerals. As in other organisms, uric acid probably accumulates as the metabolicproduct of the degradation of nucleic acids derived from autophagy of the rough endoplasmic reticulum duean earlier massive protein synthesis, but may also be extracted from the hemolymph.

Surface morphology of Mytella falcata gill filaments from three regions of the santos estuary

Bivalves have been extensively used to monitor aquatic habitats because their sedentary filter feeding habit results in the accumulation of elements from the environment. The genus Mytella is of special interest because its habit of burrowing in sediments can provide information about the substrate conditions in estuaries. Gill filaments have a large surface that is in constant contact with the water and therefore are used to monitor aquatic environments. In this study, we used scanning electron microscopy (SEM) to investigate the morphology of Mytella falcata gill filaments and to compare the gill structure in specimens from three sites (A, B and C) of the Santos estuary in southeastern Brazil. Site A presents low levels of pollutants, whereas sites C and B were directly affected by industrial discharges and harbor pollutants. The gill filaments of M. falcata have three types of cilia, namely, lateral cilia, eu-latero-frontal cirri and frontal cilia. Structures joining the inner and outer lamellae were found on the abfrontal surface, in addition to the presence of composite and simple cilia. A comparison of the filaments of bivalves from the three sites revealed no morphological alterations, but there was an accumulation of mucus on the frontal surface of the gill filaments of specimens collected at site B. This mucus may function as a protective barrier against pollutants. Bivalves from site C showed no such alteration, even though this site had the highest levels of pollutants. This lack of alterations may reflect the fact that these specimens were collected from concrete pillars where there would be less contact with pollutants. Our findings may reflect a long-term adaptation of these mollusks to chronic exposure to pollutants.

Ovarian morphology in two species of Pseudonannolene (Diplopoda, Arthropoda)

The anatomy of the gametes and reproductive system of millipedes is important in establishing the phylogenetic relationshisps of this group with other arthropods. The genus Pseudonannolene (Spirostreptida) has the most derivedmale reproductive system among millipedes. In contrast, little is known about the female reproductive system. In this study, we describe the ovarian morphology of two species of Pseudonannolene. In both species, the ovaries consisted of a single tube in which oocystes in different developmental stages were observed. These oocytes were randomly distributed throughout the gonad. A region similar to a germarium was present at the anterior extremity of the tube, which suggested the presence of a single apical germination center. Since the pairing of ovarian structures is considered a primitive character, the two species examined here showed the most derived model of ovarian structure described so far among millipedes. This conclusion agrees with similar observations for the male reproductive system of this genus.

Ultrastructural features of the fat body and oenocytes of Rhinocricus padbergi Verhoeff (Diplopoda, Spirobolida)

The fat body of the diplopod Rhinocricus padbergi is located in two preferential areas of its body: a) immediately below the tegument, denominated parietal, and b) filling the body cavity, close to the viscera, mainly the ovaries and alimentary canal, denominated perivisceral. Ultrastructurally, its cells, the adipocytes, presented varied morphology and contained organelles indicating that they are cells that mainly produce and store lipids and proteins. The presence of cells similar to the oenocytes found in insects was observed for the first time in diplopods, associated to the fat body of R. padbergi. Our observations suggest that this tissue probably maintains activity cycles, since the presence of cells undergoing apoptosis was detected.

Meiotic prophase in diplopoda

Poucos dados sobre os cromossomos de Diplopoda estäo disponíveis. Aproximadamente 70 espécies têm sido investigadas de um total de 8000 conhecidas no mundo. A maior parte destes estudos foi feita com espécies da India (Regiäo Zoogeográfica Oriental) e o numero diplóide das espécies é bem variável. O atual estudo mostra pela primeira vez a sequência provável das espécies de Diplopoda baseado em dados obtidos com espécies brasileiras, comparando-se com dados da literatura