Preassembly and ligand-induced restructuring of the chains of the IFN-γ receptor complex： the roles of Jak kinases, Statl and the receptor chains

We previously demonstrated using noninvasive technologies that the interferon-gamma （IFN-γ） receptor complex is preassembled [ 1 ]. In this report we determined how the receptor complex is preassembled and how the ligand-mediated conformational changes occur. The interaction of Statl with IFN-γR1 results in a conformational change localized to IFN- γR1. Jakl but not Jak2 is required for the two chains of the IFN-γ receptor complex （IFN-γR1 and IFN-γR2） to interact; however, the presence of both Jakl and Jak2 is required to see any ligand-dependant conformational change. Two IFN- γR2 chains interact through species-specific determinants in their extracellular domains. Finally, these determinants also participate in the interaction of IFN-γR2 with IFN-γR1. These results agree with a detailed model of the IFN-γ receptor that requires the receptor chains to be pre-associated constitutively for the receptor to be active.

Analysis of the Abnormal Segregation of Pathogenicity in Magnaporthe grisea by Using a Genetic Cross of Oryza and Eleusine Isolates

A genetic cross between Oryza isolate Y93-164a-1 and Eleusine isolate SA98-4 was established, and the pathogenicity of 151 F1 progeny isolates was investigated on both host plants rice and finger millet. Results showed that the segregation of pathogenicity in this genetic cross was abnormal, i.e., most of the progeny isolates were nonpathogenic on both host plants. However, no abnormal segregation was observed when middle repetitive sequence MGR586 and 31 single-copy RFLP markers from all of the chromosomes were genetically analyzed. At the same time, comparison of the chromosomal organization among two pairs of parental isolates did not find any genomic abnormity. These results suggested that the ＂abnormal＂ inheritance of pathogenicity in this cross was most likely due to the reassortment of numerous host species specificity genes but not the biased segregation of the host species specificity genes. The host species specificities in M. grisea were likely to be multigenically controlled, at least in the genetic cross involving rice pathogen and the grasses pathogen other than rice.

Relationship between genotype and phenotype of flagellin C in Salmonella

AIM: To discover the relationship between the genotype and antigen serotype of flagellin C among Salmonella strains. METHODS: Fragment of Salmonella flagellin C in plasmid pLS408 was cloned, sequenced and compared with the corresponding sequence in other strains. Salmonella strains including two typhi strains, one paratyphoid strain, one enteritidis and one typhimurium strain were isolated from outpatients. Genome DNA was purified respectively from these clinical isolates, then the corresponding flagellin C fragment was amplified by polymerase chain reaction,and the amplification products were analyzed by agarose gel electrophoresis. RESULTS: The cloned fragment includes 582 nucleotides encoding the variable region and partial conservative region of Salmonella flagellin C in plasmid pLS408. With comparison to the corresponding sequences reported previously, there is only a little difference from other strains with the same flagellar serotype in both nucleotide and amino acid level. Specific PCR products were amplified in Salmonella strains with flagellar serotype H-1-d including S. muenchen, typhi and typhimurium, but not in S. paratyphoid C or S. enteritidis strains. CONCLUSION: In this experiment, the specificity of nucleotide sequence could be found in flagellin C central variable regions as it exists in flagellar serotypes in Salmonella. It may be helpful to developing a rapid, sensitive, accurate and PCR-based method to detect Salmonella strains with serotype H-1-d.

Occurrence,identification and phylogenetic analyses of cereal cyst nematodes(Heterodera spp.)in Turkey

Plant-parasitic nematodes are very common on cereal crops and cause economic losses via reduction in grain quality and quantity. During 2014, 83 soil samples were collected from wheat and barley fields in 21 districts of 13 provinces across five regions （CentralAnatolia, Marmara, Aegean, SoutheastAnatolia, and Black Sea Region） of Turkey. Cyst-forming nematodes were found in 66 samples （80%）, and the internal transcribed spacer （ITS） sequencing and species-specific PCR identified the species in 64 samples as Heterodera filipjevi, Heterodera latipons, and Heterodera avenae. The predominant patho- genic cereal cyst nematode was H. filipjevi, which was found in all five regions surveyed. H. avenae was only detected in Southeast Anatolia whereas H. latipons was detected in Southeast Anatolia and Central Anatolia. ITS-rDNA phylogenetic analyses showed that H. avenae isolates from China clustered with H. australis, and Turkish isolates were closely related to European and USA isolates of this species. H. filipjevi from Turkey and China were clustered closely with those from the UK, Germany, Russia, and the USA. The density of many of these populations exceeded 6r approached the maximum threshold level for economic loss. To our knowledge, this is the first report of H. filipjevi in Diyarbakir, Edirne, and Kutahya provinces, and the first report of H. avenae in DiyarbakJr Province. These results exhibit the most rigorous analysis to date on the occurrence and distribution of Heterodera spp. in Turkey＇s major wheat-producing areas, thus providing a basis for more specific resistance breeding, as well as other management practices.

Specific detection and effective inhibition of a single bacterial species in situ using peptide mineralized Au cluster probes

Increasingly serious microbial infections call for the development of new simpler methods for the precise diagnosis and specific inhibition of such pathogens. In this work, a peptide mineralized Au cluster probe was applied as a new simplified strategy to both recognize and inhibit a single bacteria species of Staphylococcus aureus(S. aureus) simultaneously. The probes are composed of peptides and Au clusters. Moreover, the peptides specifically target S. aureus cells and the Au clusters provide fluorescent imaging and have an antibacterial effect. These new probes enable the simultaneous specific detection and effective destruction S. aureus cells in situ.

The intraspecific difference of the triose phosphate isomerase (tim) gene from Giardia lamblia

OBJECTIVE: To investigate the intraspecific difference of the triose phosphate isomerase (tim) gene from Giardia lamblia (G. lamblia). METHODS: Total genomic DNA of G. lamblia was extracted and partial fragments of the triose phosphate isomerase (tim) gene were amplified by polymerase chain reaction (PCR). All nucleotide sequences were analyzed by using a phylogenetic analysis, which was constructed with parsimony and Neighbor-joining (N-J) methods. RESULTS: A total of 124 variable sites (23% of all sequences detected) was defined, most of which were found at the silent sites of codons. Two similar phylogenetic trees were constructed, subdividing 16 Giardia isolates into two groups. CONCLUSION: The genetic diversity of G. lamblia appeared to be little affected by factors of both host and geography, while natural-selection played an important role in DNA molecular evolution level of the tim gene. The tim gene may be considered a very useful genetic marker of the population genetic structure of G. lamblia.

Filamentation and inhibition of prokaryotic CTP synthase with ligands

Cytidine triphosphate synthase(CTPS)plays a pivotal role in the de novo synthesis of cytidine triphosphate(CTP),a fundamental building block for RNA and DNA that is essential for life.CTPS is capable of directly binding to all four nucleotide triphosphates:adenine triphosphate,uridine triphosphate,CTP,and guanidine triphosphate.Furthermore,CTPS can form cytoophidia in vivo and metabolic filaments in vitro,undergoing regulation at multiple levels.CTPS is considered a potential therapeutic target for combating invasions or infections by viral or prokaryotic pathogens.Utilizing cryo-electron microscopy,we determined the structure of Escherichia coli CTPS(ecCTPS)filament in complex with CTP,nicotinamide adenine dinucleotide(NADH),and the covalent inhibitor 6-diazo-5-oxo-L-norleucine(DON),achieving a resolution of 2.9A.We constructed a phylogenetic tree based on differences in filament-forming interfaces and designed a variant to validate our hypothesis,providing an evolutionary perspective on CTPS filament formation.Our computational analysis revealed a solvent-accessible ammonia tunnel upon DON binding.Through comparative structural analysis,we discern a distinct mode of CTP binding of ecCTPS that differs from eukaryotic counterparts.Combining biochemical assays and structural analysis,we determined and validated the synergistic inhibitory effects of CTP with NADH or adenine on CTPS.Our results expand our comprehension of the diverse regulatory aspects of CTPS and lay a foundation for the design of specific inhibitors targeting prokaryotic CTPS.

Effects of traits,species identity and local environmental conditions on the assessment of interactions:insights from an alpine meadow community

Aims The prediction that facilitation is the dominant interaction in physically stressful conditions has been supported by many but not all field studies.In the present paper,we tested the effects of the identity of species,the local environmental conditions and the currencies of performance measurement on such variation.Methods Using contrasting two plots,six species,and up to five multiple traits,we comprehensively explored the effects of the above factors on the assessment of plant interactions in an alpine meadow of the QingHai Tibetan Plateau.Additionally,we attempted to figure out the possible mechanisms underlying the responses observed.The data were analysed by both standard ANOVAs and multivariate statistics.Important findings Our results demonstrated that the response to the removal of neighbours was both species and trait specific,and the effect of the ocal environmental conditions was dependent on the species involved.The contrast between plots had crucial influence on the net interactions of Kobresia macrantha,but little effect on Elymus nutans.Regarding the abiotic conditions,neighbours had significant impact on soil temperature,moist and solar radiation.The results contribute to advance our knowledge on the potential underlying factors influencing the assessment of facilitation.

Natural foci of tsutsugamushi disease in the Nan Peng Lie Islands in China

OBJECTIVE: To investigate natural foci of tsutsugamushi disease whose incidence has increased in the Nan Peng Lie Islands in China, an area where this disease has not been previously recorded. METHODS: We recorded the natural foci and isolated Orientia tsutsugamushi (O. tsutsugamushi) organism. We also studied prevention measures. RESULTS: These islands had the natural foci of a south subtropical zone. The main host and vector were Rattus norvegicus and Leptotrombidium deliens (L. deliens), respectively. The seasonal quantity trends of Rattus norvegicus and Leptotrombidium deliens were consistent with the incidence of human infection. Thirty-five strains of O. tsutsugamushi were isolated from Rattus norvegicus and L. deliense. The identification of 7 strains showed that most strains were Karp. Seroepidemiology showed a high prevalence of antibody against O. tsatsugamushi among local people. After prevention measures were used, the incidence was decreased. CONCLUSION: This was the first successful confirmation that the Nan Peng Lie Islands were natural foci of tsutsugamushi disease.

Deletions are easy detectable in cochlear mitochondrial DNA of Cu/Zn superoxide dismutase gene knockout mice

Abstract Objectives To investigate the tissue specificity of reactive oxygen species (ROS) damage to mitochondrial DNA (mtDNA) and to determine whether cochlear mtDNA is a sensitive target for ROS damage. Methods 10 Cu/ZnSOD gene (Cu/Zn superoxide dismutase gene, Sod1) knockout mice and 16 wild-type mice were analyzed by nested polymerase chain reaction (PCR).Results Three deletions were detected in various tissues of Sod1 knockout mice. MtDNA3867bp and mtDNA3726bp deletions were the most visible, and mtDNA4236bp deletion was barely detected in these tissues. There were obvious differences in the ratio of deleted mtDNA/total mtDNA in different tissue. Deleted mtDNA was most abundant in the liver and kidney and less in cochlea, heart and brain. The lowest was in spleen and skin. The ratio in various tissues was 3-20 times in Sod1 knockout mice over wild-type mice. In cochlea, the ratio was about 15. Conclusions Without the protection of Sod1, ROS can lead to mtDNA deletions in various tissues with significant tissue specificity. Cochlear mtDNA is a sensitive target for ROS damage.