Characterization of Neoschoengastia gallinarum from subtropical China by rDNA and identification of two genotypes based on mitochondrial cox1.

Genetic variations in the 18S ribosomal DNA (18S), 28S ribosomal DNA (28S), second internal transcribed spacer of ribosomal DNA (ITS2), and mitochondrial cytochrome c oxidase subunit 1 (cox1) of Neoschoengastia gallinarum collected from subtropical China were examined. First, a portion of the 18S (p18S), a portion of the 28S (p28S), and the complete ITS2 were separately amplified from individual mites and sequenced. The lengths of the sequences of p18S, p28S, and ITS2 were found to be 1379 bp, 3465~3468 bp, and 200 bp, respectively. The intraspecific sequence variation was 0~0.1% for p28S and 0~1.6% for ITS2, though no variation was observed for p18S, suggesting conservation of rDNA sequences. Second, a portion of the mitochondrial cox1 gene (pcox1) of N. gallinarum was analyzed. The length of the pcox1 sequence is 460 bp, and two distinct groups were observed in N. gallinarum. All pcox1 sequences in group I were identical, and there was only one nucleotide transition observed in group II; however, 7.0~7.2% variations between the two groups were observed, suggesting that two genotypes of N. gallinarum: genotype I and genotype II. Phylogenetic analyses based on pcox1 sequences indicated that N. gallinarum isolates (genotype I or genotype II) clustered into one branch; according to cox1 sequence analysis of Trombiculidae, Walchia hayashii is the closest species. The present study shows that ITS2 rDNA sequence can act as marker for the identification of N. gallinarum samples. Furthermore, analysis of the mitochondrial pcox1 sequence suggests the existence of two genotypes, which has implications for further studies of the ecology and population genetic structures of N. gallinarum.

Pathogenicity and genetic characterization of a duck Tembusu virus associated with egg-dropping in Muscovy ducks.

Duck Tembusu virus (DTMUV) has spread to the major duck-farming region in China, causing acute egg-production drop in Chinese duck population. In this study, we characterized a DTMUV strain (named GD2014) isolated from an egg-production drop duck farm in Guangdong province, South China. The virus was pathogenic to Muscovy duck embryos and caused severe egg production drop for laying Muscovy ducks. The genome sequence of GD2014 shared 97-99% homologies with other waterfowl-origin Tembusu viruses, and shared 89% identities with MM1775 strain isolated from mosquito. Phylogenetic analysis of entire open reading frame (ORF), E gene and NS5 gene indicated that GD2014 belonged to Ntaya group. These results have implications for understanding the orgin, emergence and pathogenicity of DTMUV as well as for the development of vaccines and diagnostics based on epidemiological data.

[Changes of schistosomiasis endemic situation and water body security in Changsha City section of Xiangjiang River].

OBJECTIVE: To understand the changes of schistosomiasis endemic situation and water body security in the Changsha City section of the Xiangjiang River. METHODS: The prevention and control measures of schistosomiasis, the status of Oncomelania hupensis snails in the marshlands, and the schistosome infection rates of residents on the both sides of the river and boat fishermen were investigated from 2003 to 2012. The schistosome infectivity of the water body was investigate by the method of sentry mice. RESULTS: The snail area decreased from 471 hm(2) in 2003 to 28.81 hm(2) in 2012 with the decline rate of 93.88%. Through the environmental modification, no living snails were found in 9 marshlands among the 11 marshlands, and the density of snails was below 0.006/0.1 m(2) in the other 2 marshlands, but no infected snails were found for 7 years. The original snail habitats of Juzhou scenic area were completely modified and no living snails were found from 2008. In the area, no domestic animals were pastured and the schistosome infectivity of the water body was negative with the sentry mouse method for 10 years. In 2003, the schistosome infection rate was 3.63% in the residents, but no new infections were found in original residents after 2010. CONCLUSION: The endemic situation of schistosomiasis of the Changsha City section of the Xiangjiang River has reached the standards of schistosomiasis transmission controlled and the water body of Juzhou scenic area is safe.

[Effect of cultivation for snail control on schistosomiasis in Changsha urban section of Xiangjiang River].

OBJECTIVE: To study a reliable, friendly environmental and sustainable Oncomelania snail control method in marshlands of the Xiangjiang River. METHODS: According to the special characteristics of the marshlands of the Xiangjiang River, smoothing and cultivating in beaches were applied for snail control. In sections with scarce distribution of snails, lowering parts of 4.4 beaches and raising other parts were added. RESULTS: Since 2003, the project has been practiced for 8 years. The average snail density declined by 99.83% with the simple smoothing beaches and then cultivation there. The average snail density declined by 100% with lowering parts of beaches and raising other parts and then cultivation. The schistosome infection rate was 0.31% with a declined rate of 93.84% in residents in 2006. The schistosome infection rate was 1.03% in 2010. The test result of water contamination was negative. CONCLUSIONS: The method of simple smoothing beaches and then cultivation can control the density of snails in marshlands and the method of lowering parts of beaches and raising other parts and then cultivation is more effective.

[The effect of stress distribution and displacement by two kinds of different distract directions on mandibular body].

OBJECTIVE: To establish a three-dimensional finite element model of mandibular distraction osteogenesis (DO) in order to study the influence of distraction orientations to mandibular DO. METHODS: By using the two finite element models, Von Mises stress and the displacement under different loads were measured. RESULTS: The maximum stress in the distract equipment paralleled to the mandibular corpus was two times of that when the distract equipment paralleled to the sagittal axis. Von Mises stress concentration mainly occurred in the loading position and the condylar ante inferior. This phenomenon may lead to partial bone resorption, consequently lead to screw loose and affect the stability of distraction device. When the displacement increased in the model, the maximum stress and displacement showed linear relation. CONCLUSION: The counterforce produced by the device makes lateral displacement in tail. The reaction force could be reduced to a minimum degree when the traction device parallel to the sagittal axis. This study provides theoretical basis for the position of distract equipment and distraction orientations in clinical application.

Crystal structure of human dynein light chain Dnlc2A: structural insights into the interaction with IC74.

The human light chain of the motor protein dynein, Dnlc2A, is also a novel TGF-beta-signaling component, which is altered with high frequency in epithelial ovarian cancer. It is an important mediator of dynein and the development of cancer, owing to its ability to bind to the dynein intermediate light chain (DIC) IC74 and to regulate TGF-beta-dependent transcriptional events. Here we report the 2.1-A crystal structure of Dnlc2A using single anomalous diffraction. The proteins form a homodimer in solution and interact mainly through the helix alpha(2), strand beta(3), and the loop following this strand in each protein to generate a 10-stranded beta-sheet core. The surface of the beta-sheet core is mainly positively charged and predicted (by software PPI-Pred) to be the site that interacts with other partners. At the same time, the residues 79-82, 88, and 90 of each molecule formed two holes in the core. Residue 89 of each molecule, which is crucial for the DIC binding function of Dnlc2A, is within the holes. On the basis of these observations, we propose that the homodimer is the structural and functional unit maintained by hydrogen bonding interactions and hydrophobic packing, and that the patch of the surface of the beta-sheet core is the main area of interaction with other partners. Furthermore, the two holes would be the key sites to interact with IC74.

2.0 A crystal structure of human ARL5-GDP3'P, a novel member of the small GTP-binding proteins.

ARL5 is a member of ARLs, which is widespread in high eukaryotes and homologous between species. But no structure or biological function of this member is reported. We expressed, purified, and resolved the structure of human ARL5 with bound GDP3'P at 2.0 A resolution. A comparison with the known structures of ARFs shows that besides the typical features of ARFs, human ARL5 has specific features of its own. Bacterially expressed human ARL5 contains bound GDP3'P which is seldom seen in other structures. The hydrophobic tail of the introduced detergent Triton X-305 binds at the possible myristoylation site of Gly2, simulating the myristoylated state of N-terminal amphipathic helix in vivo. The structural features of the nucleotide binding motifs and the switch regions prove that ARL5 will undergo the typical GDP/GTP structural cycle as other members of ARLs, which is the basis of their biological functions.

Crystal structure of KD93, a novel protein expressed in human hematopoietic stem/progenitor cells.

The crystal structure of a novel hypothetical protein, KD93, expressed in human hematopoietic stem/progenitor cells, was determined at 1.9A resolution using the multiple-wavelength anomalous dispersion (MAD) method. The protein KD93, which is encoded by the open reading frame HSPC031, is a NIP7 homologue and belongs to the UPF0113 family. The structural and functional information for the group of homologues has not yet been determined. Crystallographic analysis revealed that the overall fold of KD93 consists of two interlinked alpha/beta domains. Structure-based homology analysis with DALI revealed that the C domain of KD93 matches the PUA domain of some RNA modification enzymes, especially that of archaeosine tRNA-ribosyltransferase (ArcTGT), which suggests that its possible molecular function is related to RNA binding. The difference between the RNA binding regions of KD93 and ArcTGT in amino acid constitution and surface electrostatic potential indicate that they may have different RNA binding modes. The N domain of KD93 is a unique structure with no obvious similarity to other proteins with known three-dimensional structures. The high-resolution structure of KD93 provides a first view of a member of the family of hypothetical proteins. And the structure provides a framework to deduce and assay the molecular function of other proteins of the UPF0113 family.