Characterization of Myxozoan Parasites Associated with Catfish Aquaculture in Mississippi with Notes on the Development of H. Ictaluri In Susceptible and Non-Susceptible Catfish Hosts

Myxozoans are cnidarian parasites of primarily freshwater and marine fish, with some being important pathogens of aquacultured fish species worldwide. Their life cycles have waterborne actinospores released from aquatic annelid definitive hosts and myxospore stages in fish intermediate hosts. In the southeastern United States, catfish aquaculture is burdened by annual losses to a myriad of infectious diseases. Henneguya ictaluri, the causative agent of proliferative gill disease in channel catfish Ictalurus punctatus and female channel catfish x male blue catfish Ictalurus furcatus hybrids, is the most commonly diagnosed parasitic disease of catfish in Mississippi. Other myxozoans infect these ictalurid fish, but their impact on catfish production is unknown. Surveys of actinospores from the oligochaete Dero digitata and myxospore stages from fish revealed an unexpected diversity for these production systems. Six genetically distinct actinospores representing four collective groups were observed from D. digitata. Herein, two novel Henneguya spp. are described from the gills and a novel Unicauda sp. is described from the intestinal tract of channel catfish. One Henneguya sp. was linked to its actinospore stage and represents the fourth known life-cycle in the genus. In addition to catfish, smallmouth buffalo Ictiobus bubalus polycultured with catfish were examined and two Myxobolus spp. were characterized from the gills. Phylogenetic analyses strongly support a clade of ictalurid Henneguya spp. and a clade of catostomid Myxobolus spp. Although diverse, H. ictaluri is the only myxozoan in catfish attributed to significant losses. With no feasible method of control or treatment, investigations into less susceptible fish were initiated and showed promise. Infectivity trials characterizing H. ictaluri development in channel, blue, and hybrid catfish were performed. Channel catfish were suitable hosts with myxospores developing in the gills by six weeks and persisting for at least 14 weeks. In hybrid catfish arrested or limited development was observed with no pseudocysts observed during Trial 1 and only two at 14 weeks during Trial 2. These results may suggest a possible way of decreasing losses attributed to PGD through hybrid catfish monoculture or fish crop rotation to reduce the number of infectious myxospores released into the pond

Utjecaj morfološkog tipa stanica na ekspresiju bcl-2, Ki-67 i p-53 u uvealnim melanomima

Uveal melanomas are known to be less aggressive malignant tumors compared with melanoma of other localizations but the same morphological characteristics. We hypothesized that immunohistochemical determination of expression of the known proliferation markers bcl-2 and ki-67, and p-53 as a suppressor gene marker, could better explain the biological behavior of uveal melanoma vs. melanoma of other localizations. Thirty cases of primary uveal melanoma of two levels of invasion were tested retrospectively for the presence of bcl-2, Ki-67 and p-53 proteins with the indirect peroxidase-antiperoxidase immunoenzyme method and three step ABC/AP method. The intensity of reaction was assessed by semiquantiative method.Usprkos morfološkoj građi sličnoj drugim melanomima, poznato je da uvealni melanomi imaju daleko bolju prognozu od melanoma drugih lokalizacija. Upravo stoga pretpostavili smo da bi određivanje ekspresije bcl-2, Ki-67 kao poznatih čimbenika proliferacije, te p-53 proteina u stanicama uvealnih melanoma moglo protumačiti ovakvo biološko ponašanje uvealnih melanoma. U tu svrhu ispitano je retrogradno 30 primarnih uvealnih melanoma stadija pT2 i pT3 na prisutnost bcl-2, Ki-67 i p-53 proteina indirektnom metodom peroksidaze-anti-peroksidaze i trofaznom metodom ABC/AP. Stupanj reaktivnosti određen je semikvantitativnom metodom