Athiê Jorge Guerra Santos

Crescimento e sobrevivência da tilápia chitralada submetida a diferentes fotoperíodos

The objective of this work was to assess the effect of photoperiod in the growth and survival of tilapia chitralada, Oreochromis niloticus, during and after the sexual reversion. The work was carried out in 2006 and 2007, and divided into two experiments. In the first experiment, post-larvae of 0.031±0.0058 g and 1.24±0.096 cm were used, at the density of 1.5 post-larva L-1. The post-larvae were submitted to the following photoperiods: 0, 8, 12, 16, 24 hours of light and 12.5 hours of natural light, during 28 days. The fishes were fed with 45% crude protein balanced food, containing androgen hormone, at 20% of the total biomass, divided into four meals. Sampling was done at the beginning and at the end of the experiment. In the second experiment, sex reverted fingerlings of 0.38±0.16 g and 2.81±0.40 cm were used. The experiment protocols were the same as in the former experiment, except for the stock density (0.33 fish L-1), food ratio (10% of the total biomass) and the experimental period (46 days). Sampling was done every fifteen days. The photoperiod interfered more intensively in the survival of the tilapia post-larvae, and the natural light was the recommended photoperiod during the sexual reversion. The best survival rate of the fingerlings occurred in the 0-hour light group; regarding fingerling growth, however, better results in bodyweight and length were found in the other photoperiod groups. It seems that the photoperiod responses to survival and growth are related to fish age.

Seasonality Influence on Biochemical and Hematological Indicators of Stress and Growth of Pirarucu (Arapaima gigas), an Amazonian Air-Breathing Fish

Environmental factors such as seasonal cycles are the main chronic stress cause in fish increasing incidence of disease and mortality and affecting productive performance. Arapaima gigas (pirarucu) is an Amazonian air-breathing and largest freshwater fish with scales in the world. The captivity development of pirarucu is expanding since it can fatten up over 1 kg per month reaching 10 kg body mass in the first year of fattening. This work was conducted in three periods (April to July 2010, August to November 2010, and December 2010 to March 2011) defined according to rainfall and medium temperatures. Seasonality effect analysis was performed on biochemical (lectin activity, lactate dehydrogenase, and alkaline phosphatase activities) and hematological (total count of red blood cells, hematocrit, hemoglobin, and hematimetric Wintrobe indexes) stress indicators, as well as on growth and wellbeing degree expressed by pirarucu condition factor developed in captivity. All biochemical and hematological stress indicators showed seasonal variations. However, the fish growth was allometrically positive; condition factor high values indicated good state of healthiness in cultivation. These results reinforce the robust feature of pirarucu and represent a starting point for understanding stress physiology and environmental changes during cultivation enabling identification and prevention of fish adverse health conditions.

Rachycentron canadum (cobia) Lectin Promoted Mitogenic Response in Mice BALB/c Splenocytes

The mitogenic lectins are invaluable tools to study the biochemical changes associated with lymphocyte activation and proliferation of various immune cells. Rachycentron canadum lectin (RcaL) was detected and purified from serum of cobia fish. The aim of this study was to evaluate the proliferative response and cytokine production in splenocytes of mice in vitro stimulated with RcaL lectin; Canavalia ensiformis lectin (Con A) was used as positive control. A high proliferation index was induced by RcaL in relation to control cells. Furthermore, RcaL induced higher IL‐2 and IL‐6 production in relation to control. The cell viability was 90% in splenocytes treated with RcaL lectin, but RcaL promoted significant late apoptosis after 24 and 48 h in relation to control. RcaL induced proliferative responses suggesting that this lectin can be used as a mitogenic agent in immunostimulatory assays.

Desenvolvimento ovariano de Plagioscion squamosissimus (Heckel, 1840) (Actinopterygii, Perciformes), no reservatório de Pedra, Rio de Contas, Bahia

This study aimed to characterize oocyte organization and maturation stages of Plagioscion squamosissimus ovary. Samples were collected bimonthly in Pedra reservoir, Contas River (BA), between November 2004 and September 2006. Microscopic analyses were made on histological cuts stained with hematoxylin - eosin - phloxine and Gomori trichromic mixture. Five maturation stages were identified through macro and microscopic analysis. Gonad coloration varied according to maturation stages. Six phases of oocyte development were identified: oogonia and perinucleolar, vitellogenic and early lipidic, vitellogenic and intermediate lipidic, vitellogenic and advanced lipidic, and pre-ovulation. Cell structures were similar to those found among marine species, such as oil droplets fusion at later developmental stages and pre-ovulatory hydration. Such features may be explained by the marine origin of Sciaenidae, thus suggesting the need of more detailed studies for understanding the origin, development and function of these structures along oocyte developmental stages.

Desova induzida de curimatã-pacu submetido a dois protocolos de hipofisação

The objective of this work was to compare two hypophysation protocols in the spawning induction of curimata-pacu. The application of a single dose or two doses of crude carp pituitary extract was tested. That there was no significant difference among the protocols for the rate of females that have spawned, fertilization and deformed larvae. A single dose application resulted in higher degree-hour values until the oocyte extrusion than two doses. The application of a single dose represented a lower consumption of water, energy, and handling time. A single dose protocol can be used as an alternative for inducing the curimata-pacu spawning.