Objective
Snails secrete different types of mucus that serve several functions, and are increasingly being exploited for medical and cosmetic applications. In this study, we explored the protein pattern and compared the biological properties of the mucus secreted from the mantle collar and foot of two snail species, Lissachatina fulica and Hemiplecta distincta.
Result
Protein profile showed a different pattern between the two species and between the two secretory parts. The mantle-specific protein bands were further characterized and among them was an antibacterial protein, achacin. Accordingly, the mucus from the mantle exhibited the higher antibacterial activity than that from the foot in both snail species. The mucus from H. distincta, first reported here, also showed antibacterial properties, but with a lower activity compared to that for L. fulica. Snail mucus also exhibited anti-tyrosinase activity and antioxidant activity but with no significant difference between the foot and mantle mucus. These results indicate some different protein compositions and biological activities of snail slime from the mantle and foot, which might be associated with their specific functions in the animal and are useful for medical applications.
Using two advanced sequencing approaches, Illumina and PacBio, we derive the entire Dscam gene from an M2 assembly of the complete Penaeus monodon genome. The P. monodon Dscam (PmDscam) gene is ~266 kbp, with a total of 44 exons, 5 of which are subject to alternative splicing. PmDscam has a conserved architectural structure consisting of an extracellular region with hypervariable Ig domains, a transmembrane domain, and a cytoplasmic tail. We show that, contrary to a previous report, there are in fact 26, 81 and 26 alternative exons in N-terminal Ig2, N-terminal Ig3 and the entirety of Ig7, respectively. We also identified two alternatively spliced exons in the cytoplasmic tail, with transmembrane domains in exon variants 32.1 and 32.2, and stop codons in exon variants 44.1 and 44.2. This means that alternative splicing is involved in the selection of the stop codon. There are also 7 non-constitutive cytoplasmic tail exons that can either be included or skipped. Alternative splicing and the non-constitutive exons together produce more than 21 million isoform combinations from one PmDscam locus in the P. monodon gene. A public-facing database that allows BLAST searches of all 175 exons in the PmDscam gene has been established at http://pmdscam.dbbs.ncku.edu.tw/.
The viral responsive protein, PmHHAP, plays an important role in the control of hemocyte homeostasis in shrimps during viral infection. In this study, we further investigate the role of PmHHAP in the regulation of hemocyte apoptosis. RNA interference (RNAi) mediated gene silencing was used to suppress the PmHHAP expression and the change in hemocyte apoptosis was determined in the knockdown shrimp. Within circulating hemocytes, PmHHAP knockdown increased the number of annexin V-positive apoptotic cells and the combined caspase-3/-7 activity and induced the characteristic apoptotic DNA ladder. Furthermore, PmHHAP down-regulation was accompanied by significantly altered expression of apoptosis-related proteins including the effector caspases, PmCaspase and PmCasp. Yeast two-hybrid and co-immunoprecipitation assays showed that PmHHAP binds to the p20 domain of PmCasp. Moreover, the recombinant PmHHAP protein was able to reduce the caspase activity in the actinomycin D-treated hemocyte cells and rPmCasp-treated hemocyte cells. Taken together, our data indicate that PmHHAP regulates hemocyte homeostasis by inhibits apoptotic cell death through caspase activation.
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