PcLys-i3, an invertebrate lysozyme, is involved in the antibacterial immunity of the red swamp crayfish, Procambarus clarkii.

Antimicrobial peptides (AMPs) play important roles in innate immunity against pathogens and lysozymes are a particularly type of AMP. Lysozymes are hydrolytic enzymes that are characterized by their ability to cleave the beta-(1,4)-glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycan, which is the major bacterial cell wall polymer. In this work, a lysozyme was identified from Procambarus clarkii and designated PcLys-i3. Quantitative RT-PCR was used to analyze the tissue distribution and expression profiles of PcLys-i3. PcLys-i3 was present in all tested tissues and had high expression levels in gills, stomach and intestine. The expression levels of PcLys-i3 were up-regulated in gills and intestine after challenge with Vibrio parahaemolyticus, Staphylococcus aureus and Aeromonas hydrophila. PcLys-i3 and PcFer proteins can enhance the bacterial elimination in crayfish, whereas the bacterial elimination was weakened when the expression level of PcLys-i3 or PcFer RNAs was suppressed by RNAi. Recombinant PcLys-i3 and PcFer significantly reduced the mortality of crayfish with bacterial infections. Further study found that PcLys-i3 could interact with PcFer in vitro. Finally, the PcLys-i3 and PcFer proteins could bind to bacteria and inhibit bacterial replication. These results suggest that both PcLys-i3 and PcFer play important roles in the antibacterial immunity of red swamp crayfish.

Involvement of aurantiactinomyxon in the life cycle of Thelohanellus testudineus (Cnidaria: Myxosporea) from allogynogenetic gibel carp Carassius auratus gibelio, with morphological, ultrastructural, and molecular analysis.

During the investigation of actinosporean fauna diversity from commercial fish ponds in Hubei Province, China, a novel aurantiactinomyxon type was found from Branchiura sowerbyi. Spore body of the aurantiactinomyxon was ellipsoidal in side view and triangular in apical view, 15.5 ± 0.5 (14.5-16.4) µm in diameter; three leaf-like caudal processes were approximately equal, measuring 13.2 ± 0.9 (11.5-16.2) µm long and 7.4 ± 0.4 (6.7-8.0) µm wide at the base; three polar capsules were located at the apex of spore body, globular in apical view, 2.2 ± 0.1 (2.0-2.3) µm in diameter, and pyriform in side view, 2.5 ± 0.2 (2.3-2.9) µm in length and 2.0 ± 0.2 (1.8-2.4) µm in width; a total of 32 germ cells were observed within the sporoplasm. Ultrastructural analysis showed that the development was asynchronous between pansporocysts but synchronous within a pansporocyst. The formation of sporoblast and the development of sporogonic stage were also described and discussed. The 18S ribosomal DNA sequences of the current aurantiactinomyxon type corresponded to that of a previously reported Thelohanellus testudineus, suggesting that the newly identified aurantiactinomyxon type is the actinosporean stage in the life cycle of T. testudineus.

Synopsis of the species of Thelohanellus Kudo, 1933 (Myxozoa: Myxosporea: Bivalvulida).

A synopsis of the species of Thelohanellus Kudo, 1933 (Myxozoa: Myxosporea: Myxobolidae) is presented. It includes a total of 108 nominal species. For each species, the most relevant morphological and morphometric characteristics are provided, together with data on the type-host and locality, the site of infection within the host and the original references.