Henrique David Lavander

Artemia franciscana as a vector for infectious myonecrosis virus (IMNV) to Litopenaeus vannamei juvenile.

In 2004, the infectious myonecrosis virus (IMNV) was recognized as the main cause of Litopenaeusvannamei shrimp cultures drop in Brazil. In health animal control programs, in order to reduce virus prevalence in production units it is necessary to screen live feed used. Among live diets used in aquaculture, the brine shrimp Artemia sp. is essential in crustacean larviculture and maturation. The aim of the present study was to investigate the susceptibility of Artemiafranciscana to IMNV through an immersion challenge and virus-phytoplankton adhesion route and to elucidate its role as a vector for IMNV transmission to L.vannamei. A. franciscana adults were infected with IMNV through both routes, as demonstrated by PCR-positive reactions. However, infected A. franciscana showed no signs of infection. More than 40% of L. vannamei juveniles fed with IMNV-infected A. franciscana by virus-phytoplankton adhesion route were positive by real-time PCR, whereas only a 10% infection rate was found among shrimp fed with IMNV-infected brine shrimp using the immersion challenge. Significant differences were found in mean viral load between immersion and virus-phytoplankton adhesion shrimp treatments (p ⩽ 0.05). Moreover, the mean viral loads were 1.34 × 10(2) and 1.48 × 10(4) copies/μg(-1) of total RNA for virus-phytoplankton adhesion and IMNV-infected tissue treatments, respectively, and the difference was not significant (p ⩾ 0.05). The results indicated that A. franciscana act as a vector for IMNV transmission under the experimental conditions examined. Although no mass mortalities were detected in L. vannamei fed with IMNV-infected brine shrimp, these infected shrimp should not be disregarded as a source of IMNV in grow-out units.

Meiosis Maturation in the Marine Clam Anomalocardia brasiliana (Veneridae)

ABSTRACT Advances in oyster farming have been achieved with biotechnological applications, such as chromosome manipulations aimed at polyploidy. The bivalve Anomalocardia brasiliana is of considerable importance to artisanal fishing activities and is a potential organism for aquaculture in Brazil. The cytogenetic behavior of polar bodies during meiosis provides essential information for chromosome manipulation directed at the production of triploid organisms. The objective of the present study was to identify postfertilization times in which the polar bodies are expelled and determine the most frequent number of chromosomes in A. brasiliana. Individuals were caught on the coast of the state of Pernambuco, in northeast Brazil, and subsequently induced to release the gametes. Samples of the oocyte solution were taken before and every 2 min after fertilization. The material was fixed in Carnoys solution, stained with 4′,6-diamidino-2-phenylindole and photographed under an epifluorescence microscope. Among the 50 oocytes analyzed in metaphase I, 19 bivalents were found. The release of the first polar body was detected 10 min after fertilization among 70% of the eggs, whereas the second polar body was released at 16 min among 62% of the eggs. This work provides relevant information on the time of initiation of shock treatments for chromosome set manipulation, aiming triploids of this important marine fishery resource in Brazil.

Hatchery Rearing of the Venerid Clam Anomalocardia brasiliana (Gmelin, 1791)

ABSTRACT This study describes the larval development of the Venerid bivalve mollusc Anomalocardia brasiliana “berbigão” under laboratory conditions. The clams were collected at Mangue Seco beach (Pernambuco, northeastern Brazil) and transferred to the laboratory where their gametes were released spontaneously. Trochophore and D larvae were identified in the hatchery from 18 to 24 h afterward. Dlarvae had an average length (L) of 71.9 µm, remaining at this stage until the 5th day, when first umbo veligers appeared (L = 115.9 µm). Pediveliger larvae (L = 183.2 µm) were observed after the 9th day. Within 15 days larvae reached juvenile stage (L = 282.0 µm) with growth lines in the shells. Survival was 58.8%, 20%, 60%, and 100% for D larvae, umbo veligers, pediveligers, and juveniles, respectively. To our knowledge, this is the first report of the hatchery rearing for A. brasiliana and serves as a basis for future research and culture of this species.

DIFERENTES MÉTODOS DE INDUÇÃO A REPRODUÇÃO DA OSTRA NATIVA Crassostrea rhizophorae (GUILDING, 1828) EM LABORATÓRIO

Para o processo de producao de sementes das ostras ocorra continuamente, e necessario ter reprodutores maturos sexualmente e aptos a desovarem durante o ano inteiro. Devido a isso, esta pesquisa pretendeu analisar os diferentes metodos de obtencao de gametas da ostra nativa Crassostrea rhizophorae em laboratorio. Foram capturadas 240 ostras nos estuarios do rio Formoso e do rio Timbo, ambas situadas no litoral do Estado de Pernambuco. As do rio Timbo foram maturadas com dieta algal baseada em 5% do peso seco das ostras durante 35 dias, ja as do rio Formoso nao passaram por este processo. Os metodos de inducao a reproducao utilizados foram variacao de salinidade, “secomolhado” (exposicao ao ar com imersao) e variacao de temperatura. As ostras maturadas em laboratorio responderam positivamente, a todos os estimulos. E as ostras advindas diretamente do campo por outro lado nao apresentaram nenhum resposta, apresentando apenas espasmos. Palavras–chave: ostra nativa; Crassostrea rhizophorae; reproducao induzida