Genome analysis and gene nblA identification of Microcystis aeruginosa myovirus (MaMV-DC) reveal the evidence for horizontal gene transfer events between cyanomyovirus and host.

The genome sequence, genetic characterization and nblA gene function of Microcystis aeruginosa myovirus isolated from Lake Dianchi in China (MaMV-DC) have been analysed. The genome DNA is 169 223 bp long, with 170 predicted protein-coding genes (001L­170L) and a tRNA gene. About one-sixth of these genes have homologues in the host cyanobacteria M. aeruginosa. The genome carries a gene homologous to host nblA, which encodes a protein involved in the degradation of cyanobacterial phycobilisome. Its expression during MaMV-DC infection was confirmed by reverse transcriptase PCR and Western blot detection and abundant expression was companied by the significant decline of phycocyanin content and massive release of progeny MaMV-DC. In addition, expressing MaMV-DC nblA reduced the phycocyanin peak and the phycocyanin to chlorophyll ratio in model cyanobacteria. These results confirm that horizontal gene transfer events have occurred between cyanobacterial host and cyanomyovirus and suggest that MaMV-DC carrying host-derived genes (such as 005L, that codes for NblA) is responsible for more efficient expression of cyanophage genes and release of progeny cyanophage. This study provides novel insight into the horizontal gene transfer in cyanophage and the interactions between cyanophage and their host.

[Influence of temperature on spermatogenesis-related genes in spermatogonia cultured in vitro].

OBJECTIVE: To investigate the influence of temperature on the expressions of c-kit and PI3K in spermatogonia cultured in vitro at 32 degrees C and 37 degrees C, and provide basic scientific data for the mechanism of spermatogenic impairment due to body temperature (37 degrees C). METHODS: Isolated spermatogenic cells were cultured in vitro at 32 degrees C and 37 degrees C, and their adherence, proliferation and morphologic changes were observed and recorded under the inverted phase contrast microscope. At 8 days, the spermatogonia were separated by Percoll density gradient centrifugation and the differential adhesion method. The expressions of c-kit and PI3K mRNA and proteins in the separated cells were detected by real time polymerase chain reaction and Western blot, respectively. The c-kit gene was sequenced to identify the occurrence of mutations. RESULTS: Adherence, division and proliferation of the cells were observed in both the 32 degrees C and 37 degrees C groups. The expressions of c-kit and PI3K mRNA and proteins in the spermatogonia were significantly higher in the 32 degrees C group than in the 37 degrees C group (P < 0.05). The 32 degrees C group showed no mutation of c-kit in exon 9, 11 and 13; the 37 degrees C group exhibited no mutation in exon 11 and 13, but possible insertion or deletion mutations in exon 9. CONCLUSION: Culturing in vitro at 37 degrees C could inhibit the expression of proliferation- and differentiation-related genes in spermatogenic cells and lead to the mutation of the c-kit gene.

[Synthesis and characterization of chitosan-imine-palladacycle].

Chitosan was grafted with salicylaldehyde to obtain Schiff base. The Schiff base reacted with Li2 PdCl4 in methanol to synthesize chitosan-imine-palladacycle. The structure of chitosan, schiffbase and chitosan-imine-palladacycle was characterized by IR, XRD, DTA-TG, fluorescence and XPS. According to the results of analysis, the structure of Schiff base and chitosanimine-palladacycle can be inferred.

[Partial biological characteristics and algicidal activity of an algicidal bacterium].

An algicidal bacterium was isolated from freshwater (Lake Donghu in Wuhan) and coded as A01. The morphology of the algicidal bacterium was observed using optical microscope and electron microscopes, the results showed that A01 was rod-shaped, approximately 1.5 microm in length and 0.45 microm in width and with no flagella structure. A01 was Gram-negative and belongs to the family Acinetobacter sp. though identification by Gram's staining and 16S rDNA gene analysis. A01 exhibited strong algicidal activity on the bloom-forming cyanobacterium Anabaena eucompacta under laboratory conditions. The removal rate of chlorophyll a after 7-day incubation with the culture supernatant of A01 and thalli were 77% and 61%, respectively. Microscopic observation showed that almost all cyanobacterial cells were destroyed within 3 d of co-incubation with the supernatant of algicidal bacterium, but a mass of the cyanobacterial cell lysis was observed only after 5 d of co-incubation with the thalli of algicidal bacterium. These results indicated that the main algicidal component of A01 was in its culture supernatant. In other words, the strain A01 could secrete algicidal component against Anabaena eucompacta.