First report of four rare strongylid species infecting endangered Przewalski's horses (Equus ferus przewalskii) in Xinjiang, China.

BACKGROUND: The Przewalski's horse (Equus ferus przewalskii) is the only surviving wild horse species in the world. A significant population of Przewalski's horses resides in Xinjiang, China. Parasitosis poses a considerable threat to the conservation of this endangered species. Yet, there is limited information on the nematode parasites that infect these species. To deepen our understanding of parasitic fauna affecting wild horses, we identified the intestinal nematodes of Przewalski's horses in Xinjiang and added new barcode sequences to a public database. METHODS: Between 2018 and 2021, nematodes were collected from 104 dewormed Przewalski's horses in Xinjiang. Each nematode was morphologically identified to the species level, and selected species underwent DNA extraction. The extracted DNA was used for molecular identification through the internal transcribed spacer 2 (ITS2) genetic marker. RESULTS: A total of 3758 strongylids were identified. To the best of our knowledge, this is the first study to identify four specific parasitic nematodes (Oesophagodontus robustus, Bidentostomum ivashkini, Skrjabinodentus caragandicus, Petrovinema skrjabini) and to obtain the ITS2 genetic marker for P. skrjabini. CONCLUSIONS: The ITS2 genetic marker for P. skrjabini enriches our understanding of the genetic characteristics of this species and expands the body of knowledge on parasitic nematodes. Our findings extend the known host range of four strongylid species, thereby improving our understanding of the relationship between Przewalski's horses and strongylids. This, in turn, aids in the enhanced conservation of this endangered species. This study introduces new instances of parasitic infections in wild animals and offers the DNA sequence of P. skrjabini as a valuable resource for molecular techniques in nematode diagnosis among wildlife.

Effects of cadmium stress on fruits germination and growth of two herbage species.

Cadmium (Cd) pollution is a global environmental problem. It is of great significance to find a kind of pasture that can grow normally in a cadmium environment, especially in the Tibetan Plateau. We studied the fruit germination and fruit growth of Elymus sinsubmuticus S.L. Chen and Elymus tangutorum (Nevski), native plants of the Tibetan Plateau, in different cadmium environments. The results showed that with increased cadmium stress, the fruit germination rate, final germination rate, fruit-vigor, average germination time, and germination-speed index for the two grass species gradually decreased, and the 50% germination time for the seed gradually increased. Root length, biomass, and the number of leaves decreased in both species. We quantified the fruit germination and growth of plants in the cadmium environment and found that E. sinosubmuticus S.L. Chen had better fruit germination and fruit growth, and it had the development potential of cadmium pollution control.

Effects of Cd treatment on morphology, chlorophyll content and antioxidant enzyme activity of Elymus nutans Griseb., a native plant in Qinghai-Tibet Plateau.

Cd pollution is a global environmental problem. However, the response mechanism of the alpine plant Pelagia under Cd stress remains unclear. Therefore, in this study, a native plant(Elymus nutans Griseb.) of the Qinghai-Tibet Plateau was used as the material to quantify plant height, leaf number, length of leaf, crown width, root number, biomass, Dry weight malondialdehyde (MDA), free proline, superoxide dismutase (SOD), ascorbate enzyme (APX), catalase (CAT) and chlorophyll contents under different Cd concentrations. The results showed that the growth of Elymus nutans Griseb. was a phenomenon of "low concentration promotes growth, high concentration inhibited growth" under Cd treatment. It meant that 10 mg·L-1 Cd promoted the growth of leaf number, plant height, crown width and tiller number, while 40 mg·L-1 Cd inhibited the growth of root number and biomass of Elymus nutans Griseb. compare with the control. The MDA content, free proline content, SOD activity, APX activity and CAT activity of Elymus nutans Griseb. was increased with the increase of Cd treatment concentration to resist the oxidative damage caused by Cd to the body. At the same time, the accumulation of chlorophyll A, chlorophyll B and chlorophyll AB was decreased with the increase of Cd stress concentration. In addition, the carotenoid content did not change much between the control group and the treatment group, indicating that Cd treatment had little effect on it. The results could provide a reference for the mechanism of heavy metal resistance and the selection and improvement of Cd -resistant varieties of Elymus nutans Griseb.

Gut microbial community structure and function of Przewalski's horses varied across reintroduced sites in China.

Host-associated microbiota can significantly impact host fitness. Therefore, naturally occurring variations in microbiota may influence the health and persistence of their hosts. This finding is particularly important in reintroduced animals, as they typically experience habitat changes during translocations. However, little is known about how microbiomes are altered in response to conservation translocation. Here, we accessed the gut microbiome of Przewalski's horse (Equus przewalskii) populations in China from three nature reserves (i.e. Xinjiang Kalamaili Nature Reserve, KNR; Dunhuang Xihu National Nature Reserve, DXNNR; and Anxi Extreme-arid Desert Nature Reserve, AENR) using 16s rRNA gene and metagenome sequencing. The results showed that the microbial composition and function differed significantly across locations, while a subset of core taxa was consistently present in most of the samples. The abundance of genes encoding microbe-produced enzymes involved in the metabolism of carbohydrates, especially for glycoside hydrolases, was significantly higher in open-spaced KNR populations than in more confined AENR individuals. This study offers detailed and significant differential characters related to the microbial community and metabolic pathways in various reintroduced sites of Przewalski's horse, which might provide a basis for future microecological and conservation research on endangered reintroduced animals.

Ecological Niche and Interspecific Association of Plant Communities in Alpine Desertification Grasslands: A Case Study of Qinghai Lake Basin.

The study of niche and interspecific relationships is one of the classical ecological theories. We set up four desertification gradients. The "Levins" and "Pianka" method were used to calculate the species' niche breadth and niche overlap. Interspecies associations were analyzed by the ratio of variance (VR), Chi-square test, association coefficient (AC) and Ochiai index (OI). The results showed that in grasslands with different degrees of desertification, Stellera chromosome (3.90), Thermopsis lanceolate (3.52) and Aster almanacs (3.99) had larger niche widths, which were wide-area species of plant communities in the desertification area. The ecological niches of the same species in different habitats or different species in the same habitat were multi-dimensional. Niche differentiation measured by niche overlap can occur at any community succession stage. Niche width and niche overlap were not always consistent with environmental changes. Moreover, there was no linear relationship between them. The interspecific connection coefficient fluctuated greatly with the environment. The results can provide a reference for the study of plant community competition mechanism and desertification control in desertification land of the study area. We still do not know the mechanism of how the plants were preserved and how the retained plants adapted to the new environment during the desertification process. We can further study these questions in the next step.

Wild and Captive Environments Drive the Convergence of Gut Microbiota and Impact Health in Threatened Equids.

To explore how the living environment influences the establishment of gut microbiota in different species, as well as the extent to which changes in the living environment caused by captive breeding affect wildlife's gut microbiota and health, we used 16S rRNA gene amplicon sequencing and shotgun metagenomic sequencing to compare the gut microbiome of two species of threatened equids, the Przewalski's Horse and the Asian wild ass, in the wild and captivity. The results revealed that different species of Equidae living in the same environment showed remarkable convergence of gut microflora. At the same time, captive populations exhibited significantly "unhealthy" microbiota, such as low Alpha diversity, high levels of potentially pathogenic bacteria and biomarkers of physical or psychological disease, and enrichment of microbial functions associated with exogenous exposure and susceptibility, implying that the artificial environment created by captivity may adversely impact the health of wildlife to some extent. Our findings demonstrate the importance of the environmental factors for the establishment of gut microbiota and host health and provide new insights into the conservation of wildlife in captivity from the perspective of the microbiome.

Comparative Analysis of Microbiome Metagenomics in Reintroduced Wild Horses and Resident Asiatic Wild Asses in the Gobi Desert Steppe.

The gut microbiome offers important ecological benefits to the host; however, our understanding of the functional microbiome in relation to wildlife adaptation, especially for translocated endangered species, is lagging. In this study, we adopted a comparative metagenomics approach to test whether the microbiome diverges for translocated and resident species with different adaptive potentials. The composition and function of the microbiome of sympatric Przewalski's horses and Asiatic wild asses in desert steppe were compared for the first time using the metagenomic shotgun sequencing approach. We identified a significant difference in microbiome composition regarding the microbes present and their relative abundances, while the diversity of microbe species was similar. Furthermore, the functional profile seemed to converge between the two hosts, with genes related to core metabolism function tending to be more abundant in wild asses. Our results indicate that sympatric wild equids differ in their microbial composition while harboring a stable microbial functional core, which may enable them to survive in challenging habitats. A higher abundance of beneficial taxa, such as Akkermansia, and genes related to metabolism pathways and enzymes, such as lignin degradation, may contribute to more diverse diet choices and larger home ranges of wild asses.

Poly(1,4-phenylene vinylene) Derivatives with Ether Substituents to Improve Polymer Solubility for Use in Organic Light-Emitting Diode Devices.

New ether-substituted poly(1,4-phenylene vinylene) (PPV) derivatives were synthesized via Horner-Emmons coupling. The structures of the monomers and the resultant oligomers were confirmed by 1H and 13C NMR spectroscopies. The molecular weights of the oligomers were characterized by gel permeation chromatography, giving the number-average and weight-average molecular weights and the corresponding polydispersity indices. Measurements of UV-vis absorption and fluorescence were used to characterize the optical properties of the oligomers. Estimation of the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels and other electrochemical characteristics of the oligomers were investigated by cyclic voltammetry. Dialkyl and dialkoxy PPV oligomers were also prepared and characterized following the same instrumental methods used for the ether-substituted oligomers, providing a known reference system to judge the performance of the new conjugated oligomers. Devices were fabricated to analyze the electroluminescent characteristics of the oligomers in organic light-emitting diodes.

5-HTT, BMPR2, EDN1, ENG, KCNA5 gene polymorphisms and susceptibility to pulmonary arterial hypertension: A meta-analysis.

BACKGROUND: The influence of 5-HTT, BMPR2, EDN1, ENG, KCNA5 genes polymorphisms on susceptibility of pulmonary arterial hypertension remains uncertain. This meta-analysis is conducted for further study. METHODS: We conducted a literature search on PubMed and ISI web of science databases for searching relevant articles until November 2017. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. A total of 17 articles with 2631 PAH subjects and 5139 controls were included in the final meta-analysis. Statistical software Stata13.0 was used for data-analysis. RESULTS: A significant relationship was found between the 5-HTT L/S polymorphism and PAH in all the genetic models [LL vs. SS: OR = 1.60, 95% CI, 1.11-2.32; LS vs. SS: OR = 1.55, 95% CI, 1.10-2.21; (LS + LL) vs. SS: OR = 1.56, 95% CI, 1.13-2.17; L vs. S: OR = 1.32, 95% CI, 1.08-1.62]. There were also associations of the SERT L/S polymorphism with IPAH and PAH in COPD [IPAH L/S: OR = 1.26, 95% CI, 1.01-1.57; PAH in COPD L/S: OR = 1.42, 95% CI, 1.04-1.94]. In addition, the results showed a statistically significant association between EDN1 rs5370 polymorphism and the risk of PAH in all the genetic models [TT vs. GG: OR = 3.32, 95% CI, 1.30-8.51; TG vs. GG: OR = 2.68, 95% CI, 1.54-4.66; (TG + TT) vs. GG: OR = 2.82, 95% CI, 1.69-4.71; T vs. G: OR = 2.43, 95% CI, 1.60-3.68]. However, the significant association was not found between BMPR2 rs1061157, KCNA5 rs10744676, ENG rs3739817 polymorphisms and the risk of PAH (all p > 0.05). CONCLUSIONS: 5-HTT L/S polymorphism and END1 rs5370 polymorphism were correlated with significantly increased risk of PAH. Moreover, L allele in 5-HTT gene increased susceptibility to IPAH and PAH in COPD.

Theoretical and experimental study on anamorphosis correction of Czerny-Turner imaging spectrometers.

The structure of an astigmatism-corrected Czerny-Turner imaging spectrometer will produce the focal length difference between sagittal rays and tangential rays, which contributes to the magnification difference in the spectral and spatial dimensions of the images. In this paper, the common characteristics of two optical path structures based on the Czerny-Turner imaging spectrometer to correct astigmatism (using a cylindrical and a toroidal mirror) are discussed. The magnification differences in the spectral and spatial dimensions of the image when the gratings are at zero-order and first-order diffraction and the influence of image magnification of different wavelengths are analyzed. The correction formula, methods of anamorphosis, and their common characteristics are given as well. The validity of the correction formula of anamorphosis is verified with theoretical calculation, ray tracing simulation, and experimental measurements with the imaging spectrometers. Meanwhile, this method is useful for the anamorphosis correction of an off-axis dispersion imaging spectrometer in other operating conditions of collimated light.

A non-doped phosphorescent organic light-emitting device with above 31% external quantum efficiency.

The demonstrated square-planar Pt(II)-complex has reduced triplet-triplet quenching and therefore a near unity quantum yield in the neat thin film. A non-doped phosphorescent organic light-emitting diode (PhOLED) based on this emitter achieves (31.1 ± 0.1)% external quantum efficiency without any out-coupling, which shows that a non-doped PhOLED can be comparable in efficiency to the best doped devices with very complicated device structures.

Molecular and electronic structure of cyclic trinuclear gold(I) carbeniate complexes: insights for structure/luminescence/conductivity relationships.

An experimental and computational study of correlations between solid-state structure and optical/electronic properties of cyclotrimeric gold(I) carbeniates, [Au3(RN═COR')3] (R, R' = H, Me, (n)Bu, or (c)Pe), is reported. Synthesis and structural and photophysical characterization of novel complexes [Au3(MeN═CO(n)Bu)3], [Au3((n)BuN═COMe)3], [Au3((n)BuN═CO(n)Bu)3], and [Au3((c)PeN═COMe)3] are presented. Changes in R and R' lead to distinctive variations in solid-state stacking, luminescence spectra, and conductive properties. Solid-state emission and excitation spectra for each complex display a remarkable dependence on the solid-state packing of the cyclotrimers. The electronic structure of [Au3(RN═COR')3] was investigated via molecular and solid-state simulations. Calculations on [Au3(HN═COH)3] models indicate that the infinitely extended chain of eclipsed structures with equidistant Au--Au intertrimer aurophilic bonding can have lower band gaps, smaller Stokes shifts, and reduced reorganization energies (λ). The action of one cyclotrimer as a molecular nanowire is demonstrated via fabrication of an organic field effect transistor and shown to produce a p-type field effect. Hole transport for the same cyclotrimer-doped within a poly(9-vinylcarbazole) host-produced a colossal increase in current density from ∼1 to ∼1000 mA/cm(2). Computations and experiments thus delineate the complex relationships between solid-state morphologies, electronic structures, and optoelectronic properties of gold(I) carbeniates.