Distribution and identification of Mycobacterium tuberculosis lineage in Kashgar prefecture.

OBJECTIVES: Kashgar prefecture is an important transportation and trade hub with a high incidence of tuberculosis. The following study analyzed the composition and differences in Mycobacterium tuberculosis (M.tb) lineage and specific tags to distinguish the lineage of the M.tb in Kashgar prefecture, thus providing a basis for the classification and diagnosis of tuberculosis in this area. METHODS: Whole-genome sequencing (WGS) of 161 M.tb clinical strains was performed. The phylogenetic tree was constructed using Maximum Likelihood (ML) based on single nucleotide polymorphisms (SNPs) and verified through principal component analysis (PCA). The composition structure of M.tb in different regions was analyzed by combining geographic information. RESULTS: M.tb clinical strains were composed of lineage 2 (73/161, 45.34%), lineage 3 (52/161, 32.30%) and lineage 4 (36/161, 22.36%). Moreover, the 3 lineages were subdivided into 11 sublineages, among which lineage 2 included lineage 2.2.2/Asia Ancestral 1 (9/73, 12.33%), lineage 2.2.1-Asia Ancestral 2 (9/73, 12.33%), lineage 2.2.1-Asia Ancestral 3 (18/73, 24.66%), and lineage 2.2.1-Modern Beijing (39/73, 53.42%). Lineage 3 included lineage 3.2 (14/52, 26.92%) and lineage 3.3 (38/52, 73.08%), while lineage 4 included lineage 4.1 (3/36, 8.33%), lineage 4.2 (2/36, 5.66%), lineage 4.4.2 (1/36, 2.78%), lineage 4.5 (28/36, 77.78%) and lineage 4.8 (2/36, 5.66%), all of which were consistent with the PCA results. One hundred thirty-six markers were proposed for discriminating known circulating strains. Reconstruction of a phylogenetic tree using the 136 SNPs resulted in a tree with the same number of delineated clades. Based on geographical location analysis, the composition of Lineage 2 in Kashgar prefecture (45.34%) was lower compared to other regions in China (54.35%-90.27%), while the composition of Lineage 3 (32.30%) was much higher than in other regions of China (0.92%-2.01%), but lower compared to the bordering Pakistan (70.40%). CONCLUSION: Three lineages were identified in M.tb clinical strains from Kashgar prefecture, with 136 branch-specific SNP. Kashgar borders with countries that have a high incidence of tuberculosis, such as Pakistan and India, which results in a large difference between the M.tb lineage and sublineage distribution in this region and other provinces of China.

Pleistocene sea level fluctuation and host plant habitat requirement influenced the historical phylogeography of the invasive species Amphiareus obscuriceps (Hemiptera: Anthocoridae) in its native range.

BACKGROUND: On account of repeated exposure and submergence of the East China Sea (ECS) land bridge, sea level fluctuation played an important role in shaping the population structure of many temperate species across the ECS during the glacial period. The flower bug Amphiareus obscuriceps (Poppius, 1909) (Hemiptera: Anthocoridae) is an invasive species native to the Sino-Japanese Region (SJR) of East Asia. We tested the hypothesis of the ECS land bridge acting as a dispersal corridor or filter for A. obscuriceps during the glacial period. Specifically, we tested whether and the extent to which dispersal ability and host plant habitat requirement influenced the genetic structure of A. obscuriceps during the exposure of the ECS land bridge. RESULTS: Phylogenetic and network analyses indicated that A. obscuriceps is composed of two major lineages, i.e., China and Japan. Divergence time on both sides of the ECS was estimated to be approximately 1.07 (0.79-1.32) Ma, which was about the same period that the sea level increased. No significant Isolation by Distance (IBD) relationship was found between Фst and Euclidean distances in the Mantel tests, which is consistent with the hypothesis that this species has a good dispersal ability. Our Last Glacial Maximum (LGM) niche modeling of plants that constitute preferred habitats for A. obscuriceps exhibited a similar habitat gap on the exposed ECS continental shelf between China and Japan, but showed a continuous distribution across the Taiwan Strait. CONCLUSION: Our results suggest that ecological properties (habitat requirement and dispersal ability), together with sea level fluctuation during the Pleistocene across the ECS, have shaped the genetic structure and demographic history of A. obscuriceps in its native area. The host plant habitat requirement could also be a key to the colonization of the A. obscuriceps species during the exposure of the ECS land bridge. Our findings will shed light on the potential role of habitat requirement in the process of biological invasion in future studies.

Corrosion Behavior of CMT Cladding Layer of AZ91 Magnesium Alloy Subjected to Friction Stir Processing.

Friction stir processing (FSP) was performed on an AZ91 magnesium alloy cladding layer fabricated by a cold metal transfer (CMT) technique. Electrochemical properties and immersion corrosion behavior of the cladding layer before and after FSP in 3.5 wt.% NaCl solution were investigated. After applying the FSP, the corrosion potential and corrosion current density of the cladding layer increased from -1.455 V to -1.397 V and decreased from 4.135 µA/cm2 to 1.275 µA/cm2, respectively. The results of OM and SEM displayed the refinement of grains and the dispersion of ß-Mg17Al12 second phase in the friction stir processed (FSPed) cladding layer and more severe corrosion of the unprocessed sample. The corrosion rate of the FSPed cladding layer was lower, and a more compact corrosion product film was formed on the surface of the FSPed cladding layer. EDS results and XRD patterns showed that the corrosion products was mainly composed of Mg(OH)2. The increase in Al content in the α-Mg matrix, grain refinement, and fragmentation and dispersion of the ß-Mg17Al12 second phase induced by FSP were the main factors that led to the improvement in corrosion resistance of the cladding layer of the AZ91 magnesium alloy fabricated by CMT.

AZ91 Magnesium Alloy CMT Cladding Layer Processed Using Friction Stir Processing: Effect of Traverse Speed on Microstructure and Mechanical Properties.

Friction stir processing (FSP) is a solid-state treating method to enhance the mechanical properties of materials by altering their microstructure. In this study, FSP was applied to the AZ91 magnesium alloy cladding layer prepared using cold metal transition (CMT) technology, and the purpose was to investigate the effect of the traverse speed of the H13 steel stirring head under a constant rotation speed on the microstructure and mechanical properties of the cladding layer. The results demonstrated that FSP could effectively decrease the grain size of the cladding layer and lead to the dispersion and dissolution of the coarse ß-Mg17Al12 second phase into the α-Mg matrix. The mechanical characteristics of the processed cladding layer were significantly enhanced compared to the unprocessed cladding layer due to the grain refinement and second-phase strengthening induced by FSP. When the stirring head rotation speed was set at 300 r/min, the average microhardness and tensile properties of the specimens showed a tendency of initially increasing and then dropping as the traverse speed increased. The cladding layer, obtained at a traverse speed of 60 mm/min, displayed optimal mechanical properties with an average microhardness, tensile strength, and elongation of 85.6 HV0.1, 278.5 MPa, and 13.4%, respectively.

Microstructure and Mechanical Properties of Weaving Wire and Arc Additive Manufactured AZ91 Magnesium Alloy Based on Cold Metal Transfer Technique.

Based on the cold metal transfer (CMT) technique, a deposited wall of AZ91 magnesium alloy was fabricated by weaving wire and arc additive manufacturing (WAAM), the shaping, microstructure, and mechanical properties of the sample with the weaving arc were characterized and discussed by compared with the sample without the weaving arc, and the effects of the weaving arc on grain refinement and property enhancement of the AZ91 component by CMT-WAAM process were investigated. After introducing the weaving arc, the effective rate of the deposited wall could be increased from 84.2% to 91.0%, and the temperature gradient of the molten pool could be reduced with an increase in constitutional undercooling. The equiaxed α-Mg grains became more equiaxial due to the dendrite remelting, and the ß-Mg17Al12 phases distributed uniformly induced by the forced convection after introducing the weaving arc. Compared to the deposited component fabricated by the CMT-WAAM process without the weaving arc, the average ultimate tensile strength and elongation of the component by weaving the CMT-WAAM process both increased. The weaving CMT-WAAM component showed isotropy and has better performance than the traditional cast AZ91 alloy.

Effects of Mycobacterium tuberculosis lineages and regions of difference (RD) virulence gene variation on tuberculosis recurrence.

Background: China ranks second in the incidence of tuberculosis (TB), and the virulence and infectivity of Mycobacterium tuberculosis (M.tb) in different lineages are different. The variation of virulence genes in the M.tb regions of difference (RD) may be the reason for differences in pathogenicity. Studying the relationship between virulence gene mutations in the RD region of clinical strains of M.tb and TB relapse can provide basic data for the study of TB prevention and control. Methods: A total of 155 M.tb clinical strains were collected in Kashgar Prefecture. Whole-genome sequencing (WGS) was conducted, and mutations in virulence genes in the M.tb RD region were analyzed. The maximum likelihood method was implemented using IQ-TREE software. Logistic regression was used to analyze the relationship between lineage, RD region virulence gene variation, and patient relapse. Results: The 155 strains of M.tb in Kashgar Prefecture belong to 3 M.tb lineages: L2 (45.80%), L3 (32.90%), and L4 (21.30%). In relapsed patients, L2 (70.83%, 17/24) was significantly higher than the other lineages (29.17%, 7/24; P<0.05). Relapse was significantly correlated with L2 [odds ratio (OR) =3.505; 95% confidence interval (CI): 1.341-9.158; P=0.011]. In the virulence genes of the RD region, g.4357804 (T→G, OR =4.278; 95% CI: 1.594-11.481; P=0.004), g.4359653 (C→T, OR =3.356; 95% CI: 1.303-8.644; P=0.012), and g.2627618 (C→A, OR =2.676; 95% CI: 1.101-6.502; P=0.030) mutations were significantly associated with patient relapse. The mutation frequencies of g.4357804, g.4359653, and g.2627618 in L2 were significantly higher than those in the non-L2 group (P<0.05). Conclusions: Patients infected with L2 are more prone to relapse, and RD region virulence gene variation is an important factor for the strong pathogenicity and easy relapse after infection associated with L2.

Out of Africa: Biogeography and diversification of the pantropical pond skater genus Limnogonus Stål, 1868 (Hemiptera: Gerridae).

Gondwanan vicariance, long-distance dispersal (LDD), and boreotropical migration have been proposed as alternative hypotheses explaining the pantropical distribution pattern of organisms. In this study, the historical biogeography of the pond skater genus Limnogonus was reconstructed to evaluate the impact of biogeographical scenarios in shaping their modern transoceanic disjunction. We sampled almost 65% of recognized Limnogonus species. Four DNA fragments including 69 sequences were used to reconstruct a phylogram. Divergence time was estimated using a Bayesian relaxed clock method and three fossil calibrations. Diversification dynamics and ancestral area reconstruction were investigated by using maximum likelihood and Bayesian approaches. Our results showed the crown group of Limnogonus originated and diversified in Africa in the early Eocene (49 Ma, HPD: 38-60 Ma), subsequently expanding into other regions via dispersal. The colonization of the New World originated from the Oriental Region probably via the Bering Land Bridge in the late Eocene. Two split events between the Old World and New World were identified: one between Neotropics and Oriental region around the middle Oligocene (30 Ma, HPD: 22-38 Ma), and the other between Neotropics and Africa during the middle Miocene (14 Ma, HPD: 8-21 Ma). The evolutionary history of Limnogonus involved two biogeographical processes. Gondwanan vicariance was not supported in our analyses. The diversification of Limnogonus among Africa, Oriental, and Neotropical regions corresponded with the age of land bridge connection and dispersed as a member associated with the broad boreotropical belt before local cooling (34 Ma). The current transoceanic disjunctions in Limnogonus could be better explained by the disruption of "mixed-mesophytic" forest belt; however, the direct transoceanic LDD between the Neotropics and Africa could not be ruled out. In addition, the "LDD" model coupled with island hopping could be a reasonable explanation for the diversification of the Oriental and Australian regions during the Oligocene.

Range wide molecular data and niche modeling revealed the Pleistocene history of a global invader (Halyomorpha halys).

Invasive species' Pleistocene history contains much information on its present population structure, dispersability and adaptability. In this study, the Pleistocene history of a global invasive pest (Brown Marmorated Stink Bug BMSB, Halyomorpha halys) was unveiled using the coupled approach of phylogeography and ecological niche modelling. Rangewide molecular data suggests that the Taiwan and other native populations had diverged in mid-Pleistocene. In mainland China, the native BMSB did not experience population contraction and divergence during last glacial, but persisted in interconnected populations. Combined Bayesian Skyline Plot (BSP) and niche modelling revealed a rapid expansion occurred during the transition of Last Inter Glacial (LIG) to Last Glacial Maximum (LGM). High genetic diversity and multi-reticular haplotypes network exist in the original sources populations of BMSB invasion in northern China. They were speculated to be colonized from the central China, with many derived haplotypes evolved to adapt the novel environment. The ENM future prediction suggest that BMSB may expand northward to higher latitudes in the US and Europe, because of its high invasive ability, together with the available suitable climate space there.