Redox and metabolic strategies developed by anterior and posterior gills of the crab Neohelice granulata after short periods of hypo- or hyper-osmotic stress.

The aim of this study was to identify the response pattern of redox balance, Na+/K+ATPase activity and HSP70 expression in the posterior and anterior gills of the crab Neohelice granulata submitted to hypo- or hyper-osmotic stress for 1 h and 6 h. After 1 h of either type of osmotic stress, there was an increase in catalase activity, but a decrease in GSSG/GSH ratio (oxidized to reduced glutathione ratio) and Na+/K+ATPase activity in both gill sets. H2O2 levels decreased only in the posterior gills. H2O2 levels and Na+/K+ATPase activity remained reduced after 6 h of exposure to either type of osmotic stress in both gill sets. The GSSG/GSH ratio returned to initial levels after 6 h of hyper-osmotic stress, whereas it increased 10 times in both gill sets after hypo-osmotic stress. Furthermore, HSP70 protein expression increased in posterior gills after 6 h of hypo-osmotic stress. H2O2 levels in tank water decreased after hypo-osmotic challenge and increased after 6 h of hyper-osmotic stress, indicating increased H2O2 excretion. Therefore, N. granulata gills have redox, metabolic and molecular strategies to deal with rapid osmotic challenges, an important environmental parameter that influences juvenile and adult crab distribution and abundance within different populations.

Carbofuran-induced alterations in the energy metabolism and reproductive behaviors of Hyalella castroi (Crustacea, Amphipoda).

Continuous or pulse exposure to pesticides may have negative effects on non-target organisms, resulting in a number of pathological and disturbed biochemical processes, including changes in energy budgets. The objective of this investigation was to examine the potential effects of carbofuran on the biochemical composition (glycogen, proteins, total lipids, triglycerides and cholesterol), levels of lipoperoxidation, Na+/K+ATPase activity, and reproductive behaviors (number of reproductive pairs, ovigerous females, and number of eggs) in the amphipod Hyalella castroi. The amphipods were collected in spring 2007, in the southern Brazilian highlands. In the laboratory, the animals were kept in aquariums under controlled conditions for 7 days, and after this period were exposed to 1 or 10 microg/L of carbofuran for 7 days. After the period of exposure, the animals were immediately frozen for determination of glycogen, proteins, lipids, triglycerides, total cholesterol, levels of lipoperoxidation, and Na+/K+ATPase activity. During each day of culture, reproductive behaviors were observed. Carbofuran induced significant decreases in biochemical reserves (glycogen, proteins, lipids, triglycerides and cholesterol), a significant increase in lipoperoxidation levels, and a decrease in Na+/K+ATPase activity in both males and females. Studies of all the biochemical parameters seem to be quite promising, in order to assess and predict the effects of toxicants on non-target organisms. The results showed that reproductive behaviors may provide sensitive criteria for assessing ecotoxicological effects. H. castroi lives among rooted aquatic macrophytes, and we suggest that it is a sensitive species that could be used in monitoring studies.

Seasonal variations in the biochemical composition and lipoperoxidation of Hyalella curvispina (Crustacea, Amphipoda).

We assessed the effect of seasonal variations on the biochemical composition and lipoperoxidation of an amphipod crustacean, Hyalella curvispina, which inhabits the coastal plain of the state of Rio Grande do Sul, and correlated this with information on the biology of the species. The animals were collected monthly from September 2003 to August 2005, in Gentil Lagoon, Tramandaí, Rio Grande do Sul, Brazil. Glycogen levels, total proteins, total lipids, triglycerides, and lipoperoxidation were measured for each sex separately. The results suggest that these animals have seasonal storage and degradation of the energy substrates investigated. During summer, glycogen, total lipids, and triglycerides were stored, and were utilized especially during autumn and winter. Proteins were utilized differently in males and females. Females stored proteins especially in spring and used them in summer; whereas males stored proteins especially in spring and used them in winter. The levels of lipoperoxidation during the year differed between females and males. These variations may be related to biotic factors (e.g., reproduction period and others) and to abiotic factors (e.g., water temperature, salinity and others).

Seasonal variations in the biochemical composition of the crayfish Parastacus defossus (Crustacea, Decapoda) in its natural environment.

The crayfish Parastacus defossus occurs in Uruguay and the state of Rio Grande do Sul in Brazil. It lives in swamps and lakes, where it digs sloped subterranean tunnels that are used as burrows. Because there is little information about the biology, physiology and ecology of this species, the aim of this study was to identify the seasonal variations of its carbohydrate and lipid metabolism. Crayfish were collected monthly (from November 2002 to February 2004) in the Lami region, Porto Alegre municipality (30 degrees 11'41''S-51 degrees 06'00''W). Haemolymph samples, used for determination of glucose, total proteins, triglycerides, total cholesterol and total lipids, were collected in the field using potassium oxalate as an anti-clotting agent. The animals and haemolymph samples were immediately frozen in the field. In the laboratory, the hepatopancreas, gills and abdominal muscles were removed for determination of glycogen, triglycerides, total cholesterol and total lipids. The findings suggest that in P. defossus, lipids are an important reserve of energy used during reproduction in both males and females; whereas glycogen may be used during periods of intense activity or environmental stress.

Seasonal variations of the energy metabolism of two sympatric species of Hyalella (Crustacea, Amphipoda, Dogielinotidae) in the southern Brazilian highlands.

Aquatic organisms exist in a constantly fluctuating habitat, with changes in photoperiod, temperature, pH, dissolved organic content, dissolved oxygen and food supply. Organisms must alter past of their physiological and biochemical processes to cope with these changes. We compared the effect of seasonal variations in factors related to energy metabolism of two species of sympatric amphipods, Hyalella pleoacuta and Hyalella castroi. The animals were collected monthly from April 2004 through March 2006. Contents of glycogen, proteins, lipids, triglycerides and the levels of lipoperoxidation were determined in males and females throughout the year by using spectrophotometric methods. Observations revealed significant seasonal differences in biochemical composition, as well as differences among sexes and species. Environmental conditions (e.g., trophic conditions) and reproduction are supposed to be the main processes influencing the seasonal patterns of variation in biochemical composition. Both species of Hyalella show ecological and behavioral differences, especially by resources such as food, space and seasonal variations of energy metabolism, which might facilitate their coexistence in the same habitat.

Intermediate metabolism during the ontogenetic development of Anastrepha fraterculus (Diptera: Tephritidae).

The fruit fly Anastrepha fraterculus is a major pest of native and exotic fruit trees in South America. Changes in weight, water content and metabolism were observed during its ontogenetic development in standard conditions (25 degrees C, RH=60% and 14 h:10 h photoperiod). The metabolic variables glycogen, total proteins, triglycerides and total lipids were measured by means of spectrophotometric methods. The results were correlated with pupae metamorphosis, temporal pattern, and beginning of adult life. Pupae were observed daily, and a sub-sample of 10 individuals was collected and maintained at -20 degrees C. The same procedure was performed with adults at 4 days after adult eclosion. Levels of total lipids and triglycerides were constant during pupal development, peaking in 312-h-old pupae. In 0-h-old pupae, glycogen levels were high, and decreased progressively until the insects were 312 h old. The peak in total proteins coincides with the post-histolysis period of the larval tissue (96-120 h). These results indicated that glycogen and proteins may be the principal sources of energy for metamorphosis. Total lipid and triglyceride contents remained steady during metamorphosis, and these were consumed in the first 4 days of adult life.