Lectin-binding receptors, Na+,K(+)-ATPase, and acetylcholinesterase on immunocyte plasma membrane of Limulus polyphemus

A comparative synthesis of transcriptomic analyses reveals major differences between WSSV-susceptible Litopenaeus vannamei and WSSV-refractory Macrobrachium rosenbergii

Since the 1990s White Spot Syndrome Virus (WSSV) has severely affected shrimp aquaculture worldwide causing a global pandemic of White Spot Disease (WSD) in penaeid culture. However, not all decapod species that can be infected by WSSV show the same susceptibility to the virus, thus raising interesting questions regarding the potential genetic traits that might confer resistance to WSSV. In order to shed light into the genetic markers of WSSV resistance, we employed a dual approach: i) we initially analysed the transcriptomes derived from the hepatopancreas of two species, the susceptible white shrimp Litopenaeus vannamei and the refractory fresh water prawn Macrobrachium rosenbergii, both infected with WSSV. We found a large number of differentially expressed genes (DEGs) belonging to the immune system (mostly anti-microbial peptides and haemolymph clotting components) that were generally up-regulated in M. rosenbergii and down-regulated in L. vannamei. Further, in both species we identified many up-regulated DEGs that were related to metabolism (suggesting a metabolic shift during the infection) and, interestingly, in L. vannamei only, we found several DEGs that were related to moult and suggested an inhibition of the moult cycle in this species following WSSV infection. ii) we then identified a limited number of genetic markers putatively linked with WSD tolerance by employing an ecological genomics approach in which we compared published reports with our own RNA-seq datasets for different decapod species infected with WSSV. Using this second comparative approach, we found nine candidate genes which are consistently down-regulated in susceptible species and up-regulated in refractory species and which have a role in immune response. Together our data offer novel insights into gene expression differences that can be found in susceptible and refractory decapod species infected with WSSV and provide a valuable resource towards our understanding of the potential genetic basis of tolerance to WSSV.

Cytochemical study of the germinal membrane of the Echinococcus granulosus cyst

The present cytochemical study was undertaken to provide more information on the localization of enzymatic and glycoconjugates in the germinal membrane of the Echinococcus granulosus cyst. The distinctive distribution of binding sites for two lectins (peanut agglutinin and Dilochos biflorus agglutinin) in the germinal membrane are described. An investigation is made of the distribution and specific activity of adenosine triphosphatase, alkaline phosphatase and acid phosphatase. The results suggest that cells located in the deeper layer of the germinal membrane are intrinsic in the cellular differentiation process. The dissimilarities detected in both the enzymatic activity and the lectin-binding receptors could be associated with metacestode development or degeneration.