A 14 bp indel polymorphism in the promoter region is associated with different responses to porcine circovirus type 2 infection by regulating MRC1 transcription.

Mannose receptor, C type 1 (MRC1) is a key factor in regulating the body's immune response to resist pathogen invasions. In this study, mRNA expressions of MRC1 gene in nine porcine organs/tissues were compared between Laiwu (LW) and Yorkshire × Landrace crossbred (YL) pigs prior to and post PCV2 infection. We found that, for pigs uninfected with PCV2, MRC1 mRNA expressions in the lung, spleen, large intestine, small intestine and mesenteric lymph node tissues of LW were significantly higher than those of YL pigs (P < 0.05). After PCV2 infection, MRC1 mRNA levels in the liver, kidney and mesenteric lymph node were significantly increased in LW pigs (P < 0.05); while, significantly decreased in the heart and lung tissues of YL pigs (P < 0.05). The transcriptional activity of porcine MRC1 promoter was further analyzed to investigate the molecular mechanism underlying these expressional differences in response to PCV2 infection. Luciferase assay indicated that a 14 bp indel polymorphism "GTTTTTTTTTTTTT" at the site -864 of MRC1 promoter contributed to the transcriptional activity. The frequency of 14 bp insertion in LW and Dapulian pigs, generally resistant to PCV2 infection, was higher than that in Duroc, Landrace and Yorkshire pigs, which were sensitive to PCV2 infection. The promoter with 14 bp insertion displayed higher MRC1 transcription level both prior to and post PCV2 infection compared with that carrying no insertion in PK15 cells (P < 0.01). The results suggest that this 14 bp indel polymorphism is associated with different responses to PCV2 infection by regulating MRC1 transcription.

Molecular Cloning and Functional Characterization of Mannose Receptor in Zebra Fish (Danio rerio) during Infection with Aeromonas sobria.

Mannose receptor (MR) is a member of pattern-recognition receptors (PRRs), which plays a significant role in immunity responses. Much work on MR has been done in mammals and birds while little in fish. In this report, a MR gene (designated as zfMR) was cloned from zebra fish (Danio rerio), which is an attractive model for the studies of animal diseases. The full-length cDNA of zfMR contains 6248 bp encoding a putative protein of 1428 amino acids. The predicted amino acid sequences showed that zfMR contained a cysteine-rich domain, a single fibronectin type II (FN II) domain, eight C-type lectin-like domains (CTLDs), a transmembrane domain and a short C-terminal cytoplasmic domain, sharing highly conserved structures with MRs from the other species. The MR mRNA could be detected in all examined tissues with highest level in kidney. The temporal expression patterns of MR, IL-1ß and TNF-α mRNAs were analyzed in the liver, spleen, kidney and intestine post of infection with Aeromonas sobria. By immunohistochemistry assay, slight enhancement of MR protein was also observed in the spleen and intestine of the infected zebra fish. The established zebra fish-A. sobria infection model will be valuable for elucidating the role of MR in fish immune responses to infection.

The role of physicochemical interactions and FLO genes expression in the immobilization of industrially important yeasts by adhesion.

One of the industrially important qualities of yeast is their ability to provide the cell-cell and cell-support interactions. This feature of yeast is responsible for technologically significant phenomena such as flocculation (brewing) and yeast biofilm formation (immobilization to supports), whereas these phenomena are time, environment, and strain dependent. Therefore, the goal of this work was to verify the possibility to predict and subsequently select yeast strains capable to colonize solid supports by using physicochemical adhesion models. Three different industrial yeast strains (Saccharomyces cerevisiae) were tested for their adhesion onto spent grain particles in the continuous gas-lift reactor. The cell adhesion energies were calculated, based on physicochemical characteristics of surfaces involved, according to three adhesion models (DLVO theory, thermodynamic approach, and extended DLVO theory). The role of physicochemical surface properties in the cell-cell and cell-support interactions was evaluated by comparing the computed predictions with experimental results. The best agreement between forecast and observation of the yeast adhesion to spent grains was achieved with the extended DLVO (XDLVO) theory, the most complex adhesion model applied in this study. Despite its relative comprehensiveness, the XDLVO theory does not take into account specific biochemical interactions. Consequently, additional understanding of the yeast adhesion mechanism was obtained by means of quantifying the expression of selected FLO genes. The presented approach provides tools to select the appropriately adhesive yeast strains and match them with solid supports of convenient surface properties in order to design immobilized biocatalysts exploitable in biotechnological processes.

Analysis of the sugar-binding specificity of mannose-binding-type Jacalin-related lectins by frontal affinity chromatography--an approach to functional classification.

The Jacalin-related lectin (JRL) family comprises galactose-binding-type (gJRLs) and mannose-binding-type (mJRLs) lectins. Although the documented occurrence of gJRLs is confined to the family Moraceae, mJRLs are widespread in the plant kingdom. A detailed comparison of sugar-binding specificity was made by frontal affinity chromatography to corroborate the structure-function relationships of the extended mJRL subfamily. Eight mJRLs covering a broad taxonomic range were used: Artocarpin from Artocarpus integrifolia (jackfruit, Moraceae), BanLec from Musa acuminata (banana, Musaceae), Calsepa from Calystegia sepium (hedge bindweed, Convolvulaceae), CCA from Castanea crenata (Japanese chestnut, Fagaceae), Conarva from Convolvulus arvensis (bindweed, Convolvulaceae), CRLL from Cycas revoluta (King Sago palm tree, Cycadaceae), Heltuba from Helianthus tuberosus (Jerusalem artichoke, Asteraceae) and MornigaM from Morus nigra (black mulberry, Moraceae). The result using 103 pyridylaminated glycans clearly divided the mJRLs into two major groups, each of which was further divided into two subgroups based on the preference for high-mannose-type N-glycans. This criterion also applied to the binding preference for complex-type N-glycans. Notably, the result of cluster analysis of the amino acid sequences clearly corresponded to the above specificity classification. Thus, marked correlation between the sugar-binding specificity of mJRLs and their phylogeny should shed light on the functional significance of JRLs.

Extended and bent conformations of the mannose receptor family.

In mammals, the mannose receptor family consists of four members, Endo180, DEC-205, phospholipase A2 receptor and the mannose receptor. The extracellular domains of all these receptors contain a similar arrangement of domains in which an N-terminal cysteine-rich domain is followed by a single fibronectin type II domain and eight or ten C-type lectin-like domains. This review focuses on the three-dimensional structure of the receptors in the mannose receptor family and its functional implication. Recent research has revealed that several members of this family can exist in at least two configurations: an extended conformation with the N-terminal cysteine-rich domain pointing outwards from the cell membrane and a bent conformation where the N-terminal domains fold back to interact with C-type lectin-like domains at the middle of the structure. Conformational transitions between these two states seem to regulate the interaction of these receptors with ligands and their oligomerization.