Identification and expression of an uncharacterized Ly-6 gene cluster in zebrafish Danio rerio

The myxozoans Myxobolus cerebralis and Tetracapsuloides bryosalmonae modulate rainbow trout immune responses: quantitative shotgun proteomics at the portals of entry after single and co-infections

Introduction

Little is known about the proteomic changes at the portals of entry in rainbow trout after infection with the myxozoan parasites, Myxobolus cerebralis, and Tetracapsuloides bryosalmonae. Whirling disease (WD) is a severe disease of salmonids, caused by the myxosporean M. cerebralis, while, proliferative kidney disease (PKD) is caused by T. bryosalmonae, which instead belongs to the class Malacosporea. Climate change is providing more suitable conditions for myxozoan parasites lifecycle, posing a high risk to salmonid aquaculture and contributing to the decline of wild trout populations in North America and Europe. Therefore, the aim of this study was to provide the first proteomic profiles of the host in the search for evasion strategies during single and coinfection with M. cerebralis and T. bryosalmonae.

Methods

One group of fish was initially infected with M. cerebralis and another group with T. bryosalmonae. After 30 days, half of the fish in each group were co-infected with the other parasite. Using a quantitative proteomic approach, we investigated proteomic changes in the caudal fins and gills of rainbow trout before and after co-infection.

Results

In the caudal fins, 16 proteins were differentially regulated post exposure to M. cerebralis, whereas 27 proteins were differentially modulated in the gills of the infected rainbow trout post exposure to T. bryosalmonae. After co-infection, 4 proteins involved in parasite recognition and the regulation of host immune responses were differentially modulated between the groups in the caudal fin. In the gills, 11 proteins involved in parasite recognition and host immunity, including 4 myxozoan proteins predicted to be virulence factors, were differentially modulated.

Discussion

The results of this study increase our knowledge on rainbow trout co-infections by myxozoan parasites and rainbow trout immune responses against myxozoans at the portals of entry, supporting a better understanding of these host-parasite interactions.

Evolution and Medical Significance of LU Domain-Containing Proteins

Proteins containing Ly6/uPAR (LU) domains exhibit very diverse biological functions and have broad taxonomic distributions in eukaryotes. In general, they adopt a characteristic three-fingered folding topology with three long loops projecting from a disulfide-rich globular core. The majority of the members of this protein domain family contain only a single LU domain, which can be secreted, glycolipid anchored, or constitute the extracellular ligand binding domain of type-I membrane proteins. Nonetheless, a few proteins contain multiple LU domains, for example, the urokinase receptor uPAR, C4.4A, and Haldisin. In the current review, we will discuss evolutionary aspects of this protein domain family with special emphasis on variations in their consensus disulfide bond patterns. Furthermore, we will present selected cases where missense mutations in LU domain-containing proteins leads to dysfunctional proteins that are causally linked to genesis of human disease.

Involvement of Lypge in the formation of eye and pineal gland in zebrafish

The proteins of Ly-6 (lymphocyte antigen-6) family are involved in the regulation of immunoreaction, cell migration and adhesion, and neuronal excitability. However, little is known about the function of Ly-6 proteins in embryogenesis. Herein, we identified a GPI anchored Ly-6 member named ly6 expressed in pineal gland and eye (lypge). Dynamic expression pattern of lypge was revealed by whole mount in situ hybridization. It was strikingly expressed in the pineal gland and cone photoreceptor, and its expression was regulated by orthodenticle homolog 5 (otx5) which has been shown to control the expression of many pineal genes. In addition, we demonstrated that lypge was rhythmically expressed in larvae from 4dpf on. Moreover, knockdown of lypge resulted in small head and small eye formed in zebrafish embryos. These suggest that Lypge is involved in the formation of the eye and pineal gland in early development of zebrafish.

A comprehensive analysis of the chorion locus in silkmoth

Despite more than 40 years of intense study, essential features of the silkmoth chorion (eggshell) are still not fully understood. To determine the precise structure of the chorion locus, we performed extensive EST analysis, constructed a bacterial artificial chromosome (BAC) contig, and obtained a continuous genomic sequence of 871,711 base pairs. We annotated 127 chorion genes in two segments interrupted by a 164 kb region with 5 non-chorion genes, orthologs of which were on chorion bearing scaffolds in 4 ditrysian families. Detailed transcriptome analysis revealed expression throughout choriogenesis of most chorion genes originally categorized as “middle”, and evidence for diverse regulatory mechanisms including cis-elements, alternative splicing and promoter utilization, and antisense RNA. Phylogenetic analysis revealed multigene family associations and faster evolution of early chorion genes and transcriptionally active pseudogenes. Proteomics analysis identified 99 chorion proteins in the eggshell and micropyle localization of 1 early and 6 Hc chorion proteins.