Identification of zebrafish GIGYF2 presents in egg/embryo as an antibacterial protein.

Previous studies have shown that GIGYF2 plays multiple roles, but its overall biological function remains poor-defined. Here we clearly demonstrated that zebrafish (Danio rerio) GIGYF2 has GYF domain and gigyf2 mainly expressed in caudal fin, brain, eyes and testis in a tissue specific manner, and was most abundant in brain and testis. GYF domain of GIGYF2 was a peptidoglycan (PGN), lipopolysaccharide (LPS)- and lipoteichoic acid (LTA)- binding protein abundantly stored in the testis/embryos of zebrafish, acting not only as a pattern recognition receptor, but also as an effector molecule, capable of inhibiting the growth of gram-positive and -negative bacteria. Furthermore, we reveal that the residues of GIGYF2 positioned at 582-601 and 848-865 were indispensable for GIGYF2 antibacterial activity. Additionally, site-directed mutation could improve antibacterial activities. Collectively, our results indicate that zebrafish GYF domain of GIGYF2 recognize bacterial characteristic molecules PGN, LPS and LTA, and directly kill bacteria as an antibacterial effector. This work also provides another angle for understanding the biological roles of GIGYF2.

Seasonal and spatial variation of Deuteromycetes population in polluted cost of Kiaochow Bay.

Objective: To reveal the relationship between Deuteromycetes community and the environmental in Kiaochow Bay of the Yellow Sea. Methods: Using recorded pollution survey, we used molecular methods to study seasonal and spatial variation of Deuteromycetes community diversity in different polluted waters of Kiaochow Bay of the Yellow Sea, China. Results: Denaturing gradient gel electrophoresis fingerprints varied obviously among different sites of similar level of pollution. Moreover, sequence analysis of recovered dominant bands exhibited the existence of plenty of uncultivable fungi, among which Penicillium was the dominant genus. Furthermore, in heavily polluted estuary, there were abundant animal pathogens such as amoeba and Pythium as well as Deuteromycetes. These discoveries demonstrate that the Deuteromycetes community structure is closely related to marine environment, and are indicative of different level of marine contamination. Conclusion: The relationship between Deuteromycetes community and different level of pollution and seasons varied were closely related.

Extraction of Chitin From Shrimp Shell by Successive Two-Step Fermentation of Exiguobacterium profundum and Lactobacillus acidophilus.

As an environmentally friendly and efficient method, successive two-step fermentation has been applied for extracting chitin from shrimp shells. To screen out the microorganisms for fermentation, a protease-producing strain, Exiguobacterium profundum, and a lactic acid-producing strain, Lactobacillus acidophilus, were isolated from the traditional fermented shrimp paste. Chitin was extracted by successive two-step fermentation with these two strains, and 85.9 ± 1.2% of protein and 95 ± 3% of minerals were removed. The recovery and yield of chitin were 47.82 and 16.32%, respectively. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy (SEM) were used to characterize the chitin. The crystallinity index was 54.37%, and the degree of deacetylation was 3.67%, which was lower than that of chitin extracted by the chemical method. These results indicated that successive two-step fermentation using these two bacterial strains could be applied to extract chitin. This work provides a suitable strategy for developing an effective method to extract chitin by microbial fermentation.

[Antifungal mechanism of Bacillus marinus B-9987].

OBJECTIVE: We studied the antifungal effect of the metabolite BMME-1 from Bacillus marinus B-9987, to reveal its antifungal mechanism. METHODS: The permeability of the Alternaria solani was tested by spectrophotometer after the treating the crude extracts of B-9987. The composition of cell wall and the sterol components of the fungal plasmalemma of Alternaria solani were analyzed with Infrared Spectrum and GC-MS, respectively. RESULTS: We found that the metabolites of B-9987 had strong antifungal activity with MIC50 and MFC value being 6.2mg/L and 50mg/L. The absorbance in extracellular fluid detection showed that the tegument of the fungi was impaired. The detection of glucan and chitin indicated the change in the structure of the cell wall. The absorption peak of the carbon-hydrogen bond, beta-glucosidic bond, carbon--oxygen bond was attenuated but the hydroxyl, carbonyl absorption was enhanced on the contrary. There were only one peak change in chitin chromatogram on the absorption of amide linkage comparing to the control. These changes on the structure may affect the stability of the fungal cell wall. Ergosterol was the predominant component of sterol with the proportion of 62.52 +/- 3.31% in control cells, but showed a decline during treatment with BMME-1 at a concentration of 56.36 +/- 2.52%. Accumulation of coprostanol, the precursor of ergosterol, was found in the test. CONCLUSION: From the result we can conclude that the antifungal mechanism of the crude extracts was interfering of ergosterol synthesis resulting in the change on permeability, and also mainly changed the structure of the cell wall, mainly acting on the glucan synthesis.

Purification and characterization of hatching enzyme from flounder Paralichthys olivaceus.

Using chorion of Paralichthys as a specific substrate, hatching enzyme (HE) from Paralichthys olivaceus (PHE) was purified by gel-filtration and ion-exchange chromatography, and characterized in terms of its molecular weight and enzymatic properties in this study. It was found that the molecular size of PHE is about 34.8 kDa in SDS-PAGE. The PHE had obvious choriolytic activity, which was optimal at pH 7.0 and temperature of 35 degrees C, respectively. The Km value of the PHE for casein was 4.28 mg ml(-). The PHE was very sensitive to trypsin-specific inhibitors, especially serine protease-specific inhibitors, such as LBTI, SBTI, bestatin and p-APMSF, leupeptin, ovomucoid, PMSF, pepstatin A and TLCK, indicates that it is a trypsin-type serine protease. The PHE was also extremely sensitive to Cu(2+) and Ca(2+), combined with the results that it was inhibited by EDTA in a dose-dependent manner, indicates this PHE is also a kind of metalloprotease.

Nitrosporeusines A and B, unprecedented thioester-bearing alkaloids from the Arctic Streptomyces nitrosporeus.

Chemical examination of an arctic actinomycete Streptomyces nitrosporeus resulted in the isolation of two new alkaloids named nitrosporeusines A (1) and B (2), an unprecedented skeleton containing benzenecarbothioc cyclopenta[c]pyrrole-1,3-dione. Their structures were determined through extensive spectroscopic analyses in association with X-ray single crystal diffraction. Both 1 and 2 exhibited inhibitory activities against the H1N1 virus in MDCK cells.

Purification and characterization of hatching enzyme from shrimp Penaeus chinensis.

By using Penaeus chorion as a specific substrate, the hatching enzyme (HE) from Penaeus chinensis was purified by gel-filtration and ion-exchange chromatography, and characterized in terms of its molecular weight and enzymatic properties in this study. It was found that the molecular weight of Penaeus HE is about 43.0 kDa in SDS-PAGE. The Penaeus HE had obvious choriolytic activity, which was optimal at pH 6.0 and temperature of 40 degrees C, respectively. The Km value of the HE for casein was 7.47 mg ml(-1). The HE activity was almost completely inhibited by SBTI, p-APMSF, bestatin, and NEM, greatly inhibited by ovomucoid, TLCK, IAM, chymostatin, and PMSF, and slightly inhibited by pepstatin A, TPCK, LBTI, and leupeptin. These results indicate that the HE is most probably a trypsin-type serine protease. Besides of these, the HE was extremely sensitive to EDTA, Zn2+, Ca2+, Mg2+, and Cu2+. Combined with the results that the EDTA-pretreated HE activity could be perfectly recovered by Zn2+, it is indicated that shrimp HE is most probably a kind of Zn-metalloprotease.