Differential gene expression pattern and plasma sex steroids during testicular development in Genyatremus luteus (Perciforme: Haemulidae) (Bloch, 1790).

The aim of the current study is to evaluate gene expression patterns of LH (lhr) and estrogen (er) receptors and plasma steroid levels during testicular development in Genyatremus luteus. Males were histologically classified as immature (n=7), maturing (n=7) and mature (n=7), based on the cellular structure of their testes. Plasma 11-KT concentration recorded peak at the final maturation stage. The highest plasma 17α-OHP concentrations were observed at the immature stage; they decreased at the maturation and mature stages. On the other hand, 17ß-estradiol (E2) recorded higher concentrations at the maturation stage. Er expression has significantly increased along the maturational development of animals' testes. The mRNA observed for the LH receptor has decreased from immature to maturing stage; it presented expression peak at the mature stage. There was high association between receptor gene expression and plasma steroid levels, mainly E2. The current study was the first to feature different reproductive maturation stages in male G. luteus specimens, based on cellular, endocrine and molecular aspects. In addition, it has shown that the gene expression profile for er and lhr receptors, as well as plasma 11-KT and E2 concentrations, are directly linked to testicular maturation, although they are not necessarily associated with the gonadosomatic index.

Biomarcadores histológicos em duas espécies de bagres estuarinos da Costa Maranhense, Brasil / Histology biomarkers in two estuarine catfish species from the Maranhense Coast, Brazil

Neste estudo objetivou-se validar lesões branquiais como biomarcadores em peixes de importância econômica (Sciades herzbergii e Bagre bagre) capturados pela pesca artesanal em dois locais diferenciados da Baía de São Marcos, MA, a fim de selecionar um táxon como bioindicador capaz de ser utilizado em programas de biomonitoramento. O primeiro ponto (S1) foi utilizado como uma área de referência - Ilha dos Caranguejos -, e o segundo ponto (S2) foi considerado potencialmente impactado - Complexo Portuário de São Luís, MA. Encontraram-se várias alterações histológicas para as duas espécies em S2, destacando-se: estreitamento lamelar, teleangectasia, fusão e descolamento do epitélio da lamela secundária. Lesões branquiais em B. bagre coletados em S1 também foram observadas, não sendo possível diferenciar os indivíduos das duas áreas analisadas. Os dados indicam que S. herzbergii é um bioindicador mais apropriado para análise de biomarcadores de contaminação aquática.

This study aimed to validate branchial lesions as a biomarker in fish (Sciades herzbergii and Bagre bagre) caught by traditional fishing in two different places at São Marcos Bay, MA, in order to select a bioindicator taxon which can be used in biomonitoring programs. The first point (S1) was used as a reference area - Caranguejos (Crab) Island and the second point (S2) was considered potentially impacted - Port Complex of São Luis, MA. Several histological changes were found for both species in S2, including: narrowing lamellar, teleangectasy, fusion and separation of secondary lamellar epithelium. Gill lesions in B. bagre collected were also observed in S1, it is not possible to differentiate between individuals of the two areas analyzed. The data indicate that S. herzbergii is more appropriate as a bioindicator for analysis of biomarkers of aquatic contamination.

Hábito alimentar do bagre sciades herzbergii (Siluriformes, Ariidae) da ilha dos caranguejos, Maranhão, Brasil / Feeding habits of the catfish sciades herzbergii (Siluriformes, Ariidae) in caranguejos island, Maranhão, Brazil

The article describes the feeding habits of the catfish Sciades herzbergii caught in the Crabs Island (Ilha dos Caranguejos), an important coastal area of the Maranhão state, Brazil. A total of 167 individuals were collected: 110 females and 57 males. All the stomach contents were identified to the closest taxonomic level. The frequency of occurrence, biomass, numerical frequency and index of relative importance (IRI) of food items were determined for both genders. Stomach repletion was predominant, demonstrating good feeding conditions for S. herzbergii. The main alimentary items in the diet of this catfish were crustaceans, fish, oligochaets and polychaets, and the decapods crustaceans were the most representative.