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Summary: The plateau pika (Ochotona curzoniae) is native to the Qinghai-Tibet Plateau. In this study, the gene that encodes a heme-binding protein in the pulmonary surfactant (PS) of the pika is identified. The protein is a homotetrameric hemoglobin (δ4) encoded by HBD (δ). HBD is expressed in alveolar epithelial type II (ATII) and type I (ATI) cells, upregulated by hypoxia. δ4 is secreted into alveolar cavities through osmiophilic multilamellar bodies. HBD expression is downregulated by RNAi, which significantly increases hypoxia-inducible factor 1α expression in lung tissue and red blood cells and hemoglobin and blood lactate concentrations but significantly decreases arterial partial pressure of oxygen (PaO2). Our results indicate that plateau pikas physiologically show hypoxemia when HBD expression is downregulated. Therefore, specific HBD expression in the lungs helps plateau pikas to obtain oxygen under hypoxia by maintaining higher PaO2. These findings provide insights into the adaptive mechanisms of plateau pikas to withstand high-altitude environments.

Abstract Background Poa L. is a large genus of grass in Gramineae, among which P. pratensis is widely cultivated as turf and forage. Satellite DNA is the main components of the plant genome. Information of satellites will helpful for dissection the genome composition and definition of the phylogeny relationship of these species. However, the knowledge about the satellites in genus Poa is still limited. Results Four satellite DNAs were identified using the Repeat Explorer pipeline in HiSeq Illumina reads from diploid plants in P. malaca (2n = 26). Two satellites showed high similarity with the previously identified PpTr-1 and PpTr-3, whereas two others are newly identified with the monomer of 326 bp (Poa-326) and 353 bp (Poa-353) respectively. The clone DNAs of PpTr-1 and PpTr-3, and oligonucleotides designed representing satellites Poa-326 and Poa-353 were probed to test on chromosomes across 13 Poa speceis with different polyploidy level by fluorescent in situ hybridization (FISH). PpTr-1, PpTr-3, and Poa-362 were stably positioned in the subtelomeric regions in nearly all species with the variation of hybridization sites number. However, Poa-353 showed different FISH patterns of multiple regions with the variation of hybridization intensity and distribution sites across species. In addition, 5S rDNA and 45S rDNA were used to characterize the genome of the Poa species. Four rDNA FISH patterns were revealed in the tested species. Conclusion Four identified satellite were high conservable across Poa species. Genome distribution of these satellites can be characterized by FISH. The variation of satellite DNAs and rDNA chromosomal distributions between species provide useful information for phylogenetic analysis in genus Poa.

The plateau zokor (Myospalax baileyi) is a native species to the Qinghai-Tibetan Plateau, inhabiting hypoxia and hypercapnia sealed subterranean burrows that pose several unique physiological challenges. In this study, we observed a novel heme-containing protein in the pulmonary surfactant (PS) of plateau zokor, identified the encoding gene of the protein, predicted its origination and structure, verified its expression in alveolar epithelial cells, and determined the protein’s affinity to oxygen and its effect on the oxygen-dissolving capability in the PS of plateau zokors. The protein is an unusual homotetramer hemoglobin consisting of four γ-like subunits, and the subunit is encoded by a paralog gene of γ, that is γ-like. The divergence time of γ-like from γ is estimated by the molecular clock to be about 2.45 Mya. The generation of γ-like in plateau zokors might well relate to long-time stress of the high land hypoxia. Unlike γ, the γ-like has a hypoxia response element (HRE) and a lung tissue-specific enhancer in its upstream region, and it is expressed specifically in lung tissues and up-regulated by hypoxia. The protein is named as γ4-like which is expressed specifically in Alveolar epithelial type II (ATII) cells and secreted into the alveolar cavities through the osmiophilic multilamellar body (LBs). The γ4-like has a higher affinity to oxygen, and that increases significantly oxygen-dissolving capability in the PS of plateau zokors by its oxygenation function, which might be beneficial for the plateau zokors to obtain oxygen from the severe hypoxia environments by facilitating oxygen diffusion from alveoli to blood.

Vitamin D3 (D3) is produced endogenously from 7-dehydrocholesterol by irradiation and is an important secosteroid for the absorption of calcium and phosphate. Lithocholic acid (LCA) increases intestinal paracellular calcium absorption in a vitamin D receptor-dependent manner in vitamin D-deficient rats. The plateau zokor (Myospalax baileyi), a strictly subterranean species, and plateau pika are endemic to the Qinghai-Tibet Plateau. To verify whether the zokors were deficient in D3 and reveal the effects of hypoxia on D3 metabolism in the zokors and pikas, we measured the levels of 25(OH)D3, calcium, and LCA, and quantified the expression levels of D3 metabolism-related genes. The results showed an undetectable serum level of 25(OH)D3 and a significantly higher concentration of LCA in the serum of plateau zokor, but its calcium concentration was within the normal range compared with that of plateau pika and Sprague-Dawley rats. With increasing altitude, the serum 25(OH)D3 levels in plateau pika decreased significantly, and the mRNA and protein levels of CYP2R1 (in the liver) and CYP27B1 (in the kidney) in plateau pika decreased significantly. Our results indicate that plateau zokors were deficient in D3 and abundant in LCA, which might be a substitution of D3 in the zokor. Furthermore, hypoxia suppresses the metabolism of D3 by down-regulating the expression of CYP2R1 and CYP27B1 in plateau pika.

Human activity, combined with climate change, has led to severe degradation of natural grasslands all over the world. As such, artificial grasslands created with species suited to the geographical area present a popular alternative. However, species that are both native and suitable for creating artificial grasslands are rare, especially in the Qinghai-Tibetan Plateau of China. In this study, we performed two experiments respectively with varied temperature and water potential, to evaluate the cold and drought resistance of 13 local Poa L. species in the Qinghai Province of China. Within the range of 0–20 °C, our results showed that increase in temperature increased the germination indices of all 13 species, with some species germinating even at 5 °C, demonstrating relatively cold-resistant species in our study. Similarly, decrease in moisture levels decreased the germination percentages of all species in this experiment, with several species germinating at even −1.2 MPa, which were considered as relatively higher drought-resistant species in this study. Among the 13 species, P. malaca, P. paucifolia, and P. sphondylodes exhibited relatively strong cold-resistance, while P. poophagorum, P. pratensis var. anceps Gaud. cv. Qinghai, and P. pratensis cv. Qinghai showed relatively high drought resistance. Overall, the results indicated that all the 13 native grass species evaluated in the study were suitable for planting and cultivation on the Qinghai-Tibetan Plateau. This study could provide insights into identifying suitable species for plant breeding in Qinghai-Tibetan plateau and establish a protocol for germplasm evaluation of local Poa L. species. Further, these findings can help evaluate and identify more native species suited for the restoration of degraded grasslands, especially under the scenario of climate change.

This study provides a chloroplast genome of Poa pratensis L. cv. Qinghai. The complete genome is 135,606 bp in length with a G + C content of 38.28%, which contains 32 tRNA genes, and 8 rRNA genes. The phylogenetic analysis indicated that P. pratensis L. cv. Qinghai is closely related to Festuca arundinacea cultivar KY-31. These results contribute to explore the genetic evidence for adaptation to the Qinghai-Tibet Plateau.

This study provides a chloroplast genome of Poa poophagorum. The complete cp genome was135,664 bp in length with typical quadripartite structure, containing a pair of inverted repeats (IR) of 21,552 bp each, a large single-copy (LSC) region of 79,790 bp, and a small single-copy (SSC) region of 12,770 bp. The overall G + C content of the cp genome was 38.30%, which encompassed 119 genes including 79 protein-coding genes,8 rRNA genes, and 32 tRNA genes. The phylogenetic analysis indicated that P. poophagorum was closely related to Festuca arundinacea cultivar KY-31in Gramineae. This study would contribute to enrich the Poa L. cp genome resource and promote biological research.

This paper deals with the stability of switched systems with time-varying delay. The time-varying system parameters are assumed to be norm-bounded. Based on a novel switched time-varying Lyapunov functional method, some new LMI-based sufficient conditions have been obtained to ensure the exponential stability for the uncertain switched delays systems. Finally, the proposed method is applied to a numerical example and the simulative results are also given.

To acquire non-ferrous metals related news from different countries' internet, we proposed a cross-lingual non-ferrous metals related news recognition method based on CNN with a limited bilingual dictionary. Firstly, considering the lack of related language resources of non-ferrous metals, we use a limited bilingual dictionary and CCA to learn cross-lingual word vector and to represent news in different languages uniformly. Then, to improve the effect of recognition, we use a variant of the CNN to learn recognition features and construct the recognition model. The experimental results show that our proposed method acquires better results. [ABSTRACT FROM AUTHOR]

Testis-specific lactate dehydrogenase (LDH-C4) is one of the lactate dehydrogenase (LDH) isozymes that catalyze the terminal reaction of pyruvate to lactate in the glycolytic pathway. LDH-C4 in mammals was previously thought to be expressed only in spermatozoa and testis and not in other tissues. Plateau pika (Ochotona curzoniae) belongs to the genus Ochotona of the Ochotonidea family. It is a hypoxia-tolerant species living in remote mountain areas at altitudes of 3000-5000 m above sea level on the Qinghai-Tibet Plateau. Surprisingly, Ldh-c is expressed not only in its testis and sperm, but also in somatic tissues of plateau pika. To shed light on the function of LDH-C4 in somatic cells, Ldh-a, Ldh-b, and Ldh-c of plateau pika were subcloned into bacterial expression vectors. The pure enzymes of Lactate Dehydrogenase A4 (LDH-A4), Lactate Dehydrogenase B4 (LDH-B4), and LDH-C4 were prepared by a series of expression and purification processes, and the three enzymes were identified by the method of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and native polyacrylamide gel electrophoresis (PAGE). The enzymatic kinetics properties of these enzymes were studied by Lineweaver-Burk double-reciprocal plots. The results showed the Michaelis constant (Km) of LDH-C4 for pyruvate and lactate was 0.052 and 4.934 mmol/L, respectively, with an approximate 90 times higher affinity of LDH-C4 for pyruvate than for lactate. At relatively high concentrations of lactate, the inhibition constant (Ki) of the LDH isoenzymes varied: LDH-A4 (Ki = 26.900 mmol/L), LDH-B4 (Ki = 23.800 mmol/L), and LDH-C4 (Ki = 65.500 mmol/L). These data suggest that inhibition of lactate by LDH-A4 and LDH-B4 were stronger than LDH-C4. In light of the enzymatic kinetics properties, we suggest that the plateau pika can reduce reliance on oxygen supply and enhance its adaptation to the hypoxic environments due to increased anaerobic glycolysis by LDH-C4. [ABSTRACT FROM AUTHOR]

Cascade movement of mobile sensors are useful when the leaving of mobile sensors may create new coverage holes if the network does not have sufficient redundant mobile sensor or the coverage holes are located beyond the maximum moving distance of their nearest mobile sensors in a hybrid wireless sensor network. We first analyze the sensor network where cascade movement of mobile sensors may appear and introduce vacancies to transform the network. Then we propose a distributed algorithm that permits cascade movement of mobile sensors and outputs at least 1/5 of the optimal maximum total residual energy of all scheduled mobile sensors for the movement. Simulation result shows that when the coefficient of mobile sensor's maximum moving distance is low mobile sensors significantly retaining more total remaining energy by cascade movement. And the algorithm permits cascade movement always provides higher coverage hole healing ratio than the algorithm does not. [ABSTRACT FROM AUTHOR]