Morphology of the midgut trunk in the penaeid shrimp,Sicyonia ingentis, highlighting novel nuclear pore particles and fixed hemocytes

Structural changes of Artemia parthenogenetica (Bowen and Sterling, 1978) (Branchiopoda-Anostraca) exposed to lead acetate

The cosmopolitan genus Artemia occurs both in saline or hypersaline waters and Artemia species are sensitive indicator organisms for environmental contamination. Scientists propose that the brine shrimp (Artemia) is a very suitable candidate for the development of identifying chemicals with adverse effects in aquatic ecosystems. In the present study, we investigated 24h the short-term toxicity of lead acetate on Artemia parthenogenetica by using electron microscopy techniques. The ultrastructural changes were studied control group and experimental group. Analysing cellular structure, structure of organelles and vacuolization were observed. The number of cells based on the toxic effects of lead acetate was increased compared with the control group.

Peritrophic membrane of the penaeid shrimp Sicyonia ingentis: structure, formation, and permeability

Peritrophic membranes (PTMs) are secreted acellular layers that separate ingested materials from the gut epithelium in a variety of invertebrates. In insects and crustaceans, PTMs are produced in the midgut trunk (MGT, or intestine), but the MGT in decapod crustaceans, unlike that of insects, is not involved with digestion or absorption of food. We demonstrate that the PTM in the penaeid shrimp Sicyonia ingentis is similar to that in other crustaceans that have been studied and is primarily composed of chitin. The lectin WGA binds only to the PTM and glycocalyx along the microvilli of the midgut cells, which is consistent with the suggestion that the chitin is synthesized along the microvilli. The PTM is only permeable to inert particles smaller than 20 nm. We also describe the secretion of granules, which fill the apices of the epithelial cells, into the ectoperitrophic space. Although their function is not clear, they do not contribute to the PTM.