RESUMO
Two experimental modules with different stocking densities (M1 = 70 and M2 = 120 shrimp m-2) were examined weekly during 72-day culture cycle at low-salinity water (1.9 g L-1) and zero-water exchange to examine the effects of water quality deterioration on the antennal gland (AG) of shrimp. Results showed survival rates of 87.7% and 11.9% in M1 and M2, respectively. Water temperature, pH, dissolved oxygen, and chlorophyll a were not significantly different between modules but the concentrations of the nitrogen compounds were significantly different between modules with the exception of nitrite-N, showing a higher histological alteration index in M2 (32 ± 10) than M1 (22 ± 0) with a strong correlation with the nitrogen compounds. During the last weeks was evidenced in M1 inflammation and hemocytic and hemolymph infiltration, while in M2, melanization, hemocytic melanized nodules and cells with kariorrexis.
Assuntos
Nitritos/química , Compostos de Nitrogênio/química , Penaeidae/efeitos dos fármacos , Qualidade da Água/normas , Animais , Clorofila/metabolismo , Clorofila ARESUMO
The euryhaline shrimp Palaemonetes argentinus exemplifies an evolutionary transition from brackish to freshwater habitats that requires adequate osmoregulatory capacities. Hyperosmoregulation is functional at hatching and it likely begins during the embryonic phase allowing this species to develop entirely in fresh water. Here, we investigated the Na(+)/K(+)-ATPase α-subunit gene (nka-α) expression using quantitative real-time PCR and localized Na(+)/K(+)-ATPase (NKA) in ion-transporting epithelia through immunofluorescence microscopy. We reared shrimps from spawning to juvenile stages at two salinities (1, 15 ) and maintained adults for 3 weeks at three salinity treatments (1, 15, 25 ). nka-α gene expression was measured in: (1) embryos at an early (SI), intermediate (SII) and late (SIII) stage of embryonic development; (2) newly hatched larvae (Zoea I, ZI); and (3) isolated gill tissue of adults. The nka-α expression was low in SI and SII embryos and reached maximum levels prior to hatching (SIII), which were similar to expression levels detected in the ZI. The nka-α expression in SIII and ZI was highest at 15 , whereas salinity did not affect expression in earlier embryos. In SIII, in ZI and in a later zoeal stage ZIV, NKA was localized in epithelial cells of pleurae, in the inner-side epithelium of branchiostegite and in the antennal glands. Gills appeared in the ZIV but NKA immunolabeling of the cells of the gill shaft occurred in a subsequent developmental larval stage, the decapodid. Extrabranchial organs constitute the main site of osmoregulation in early ontogenetic stages of this freshwater shrimp.
Assuntos
Embrião não Mamífero/enzimologia , Água Doce , Palaemonidae/embriologia , Palaemonidae/enzimologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Regulação Enzimológica da Expressão Gênica , Brânquias/ultraestrutura , Larva/enzimologia , Osmorregulação , Palaemonidae/anatomia & histologia , Palaemonidae/ultraestrutura , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Salinidade , ATPase Trocadora de Sódio-Potássio/genéticaRESUMO
The objective of our study was to describe by histologic methods the structural organization of the antennal gland of M. potiuna as well as the location through histochemical methods of the neutral and sulfated polissacharides that exist in these regions. This study showed that the gland is composed of the a non-secretive tubular portion and a secretive portion which is formed by a cubic simple epithelium, sub-epithelium layer and cellular chains.