Satellite-Detected Contrasting Responses of Canopy Structure and Leaf Physiology to Drought

Disentangling drought impacts on plant photosynthesis is crucial for projecting future terrestrial carbon dynamics. We examined the separate responses of canopy structure and leaf physiology to an extreme summer drought that occurred in 2011 over Southwest China, where the weather was humid and radiation was the main growth-limiting factor. Canopy structure and leaf physiology were, respectively, represented by near-infrared reflectance of vegetation (NIRv) derived from MODIS data and leaf scale fluorescence yield (Φf) derived from both continuous SIF (CSIF) and global OCO-2 SIF (GOSIF). We detected contrasting responses of canopy structure and leaf physiology to drought with a 14.0% increase in NIRv, compared with 12.6 or 19.3% decreases in Φf from CSIF and GOSIF, respectively. The increase in structure resulted in a slight carbon change, due to water deficit-induced physiological constraints. The net ecosystem effect was a 7.5% (CSIF), 1.2% (GOSIF), and-2.96% (EC-LUE GPP) change in photosynthesis. Our study improves understanding of complex vegetation responses of plant photosynthesis to drought and may contribute to the reconciliation of contrasting observed directions in plant responses to drought in cloudy regions via remote sensing

MicroRNA-275 and its target vitellogenin-2 are crucial in ovary development and blood digestion of Haemaphysalis longicornis

Background: The hard tick Haemaphysalis longicornis is widely distributed in eastern Asia, New Zealand and Australia and is considered the major vector of Theileria and Babesia, harmful parasites to humans and animals. Female ticks need successful blood meals to complete the life-cycle. Therefore, elucidation of the underlying molecular mechanisms of H. longicornis development and reproduction is considered important for developing control strategies against the tick and tick-borne pathogens. Methods: Luciferase assays were used to identify the targets of micro RNA miR-275 in vitro. RNAi of Vitellogenin (Vg) was used in phenotype rescue experiments of ticks with miR-275 inhibition, and these analyses were used to identify the authentic target of miR-275 in vivo. The expression of miR-275 in different tissues and developmental stages of ticks was assessed by real-time PCR. To elucidate the functions of miR-275 in female ticks, we injected a miR-275 antagomir into female ticks and observed the phenotypic changes. Statistical analyses were performed with GraphPad5 using Student’s t-test. Results: In this study, we identified Vg-2 as an authentic target of miR-275 both in vitro and in vivo by luciferase assays and phenotype rescue experiments. miR-275 plays the regulatory role in a tissue-specific manner and differentially in developmental stages. Silencing of miR-275 resulted in blood digestion problems, substantially impaired ovary development and significantly reduced egg mass (P < 0.0001). Furthermore, RNAi silencing of Vg-2 not only impacted the blood meal uptake (P < 0.05) but also the egg mass (P < 0.05). Significant rescue was observed in miR-275 knockout ticks when RNAi was applied to Vg-2. Conclusion: To our knowledge, this study is the first demonstration that miR-275 targets Vg-2 in H. longicornis and regulates the functions of blood digestion and ovary development. These findings improve the molecular understanding of tick development and reproduction

Detection and differentiation of Borrelia burgdorferi sensu lato in ticks collected from sheep and cattle in China

<p>Abstract</p> <p>Background</p> <p>Lyme disease caused by <it>Borrelia burgdorferi </it>sensu lato complex is an important endemic zoonosis whose distribution is closely related to the main ixodid tick vectors. In China, isolated cases of Lyme disease infection of humans have been reported in 29 provinces. Ticks, especially ixodid ticks are abundant and a wide arrange of <it>Borrelia </it>natural reservoirs are present. In this study, we developed a reverse line blot (RLB) to identify <it>Borrelia </it>spp. in ticks collected from sheep and cattle in 7 Provinces covering the main extensive livestock regions in China.</p> <p>Results</p> <p>Four species-specific RLB oligonucleotide probes were deduced from the spacer region between the 5S-23S rRNA gene, along with an oligonucleotide probe which was common to all. The species specific probes were shown to discriminate between four genomic groups of <it>B. burgdorferi </it>sensu lato i.e. <it>B. burgdorferi </it>sensu stricto, <it>B. garinii, B. afzelii</it>, and <it>B. valaisiana</it>, and to bind only to their respective target sequences, with no cross reaction to non target DNA. Furthermore, the RLB could detect between 0.1 pg and 1 pg of <it>Borrelia </it>DNA.</p> <p>A total of 723 tick samples (<it>Haemaphysalis, Boophilus, Rhipicephalus </it>and <it>Dermacentor</it>) from sheep and cattle were examined with RLB, and a subset of 667 corresponding samples were examined with PCR as a comparison. The overall infection rate detected with RLB was higher than that of the PCR test.</p> <p>The infection rate of <it>B. burgdoreri </it>sensu stricto was 40% in south areas; while the <it>B. garinii infection rate </it>was 40% in north areas. The highest detection rates of <it>B. afzelii </it>and <it>B. valaisiana </it>were 28% and 22%, respectively. Mixed infections were also found in 7% of the ticks analyzed, mainly in the North. The proportion of <it>B. garinii </it>genotype in ticks was overall highest at 34% in the whole investigation area.</p> <p>Conclusion</p> <p>In this study, the RLB assay was used to detect <it>B. burgdorferi </it>sensu lato in ticks collected from sheep and cattle in China. The results showed that <it>B. burdorferi senso stricto </it>and <it>B. afzelii </it>were mainly distributed in the South; while <it>B. garinii </it>and <it>B. valaisiana </it>were dominant in the North. <it>Borrelia </it>spirochaetes were detected in <it>Rhipicephalus </it>spp for the first time. It is suggested that the <it>Rhipicephalus </it>spps might play a role in transmitting <it>Borrelia </it>spirochaetes.</p

Comparative analysis of microRNA profiles between wild and cultured Haemaphysalis longicornis (Acari, Ixodidae) ticks

The miRNA profiles of a Haemaphysalis longicornis wild-type (HLWS) and of a Haemaphysalis longicornis cultured population (HLCS) were sequenced using the Illumina Hiseq 4000 platform combined with bioinformatics analysis and real-time polymerase chain reaction (RT-PCR). A total of 15.63 and 15.48 million raw reads were acquired for HLWS and HLCS, respectively. The data identified 1517 and 1327 known conserved miRNAs, respectively, of which 342 were differentially expressed between the two libraries. Thirty-six novel candidate miRNAs were predicted. To explain the functions of these novel miRNAs, Gene Ontology (GO) analysis was performed. Target gene function prediction identified a significant set of genes related to salivary gland development, pathogen-host interaction and regulation of the defence response to pathogens expressed by wild H. longicornis ticks. Cellular component biogenesis, the immune system process, and responses to stimuli were represented at high percentages in the two tick libraries. GO enrichment analysis showed that the percentages of most predicted functions of the target genes of miRNA were similar, as were certain specific categories of functional enhancements, and that these genes had different numbers and specific functions (e.g., auxiliary transport protein and electron carrier functions). This study provides novel findings showing that miRNA regulation affects the expression of immune genes, indicating a considerable influence of environment-induced stressful stimulation on immune homeostasis. Differences in the living environments of ticks can lead to differences in miRNAs between ticks and provide a basis and a convenient means to screen for genes encoding immune factors in ticks

Molecular Evidence of Bartonella melophagi in Ticks in Border Areas of Xinjiang, China

Bartonella are gram-negative intracellular bacteria; certain species of Bartonella can cause diseases in mammals and humans. Ticks play a major role in the transmission of Bartonella. Xinjiang is the largest province in China according to land area and has one-third of the tick species in China; the infection rate of Bartonella in ticks in the Xinjiang border areas has not been studied in detail. Therefore, this study investigated tick infections by Bartonella in Xinjiang border areas, and the purpose of the study was to fill in gaps in information regarding the genetic diversity of tick infections by Bartonella in Xinjiang. We tested 1,549 tick samples from domestic animals (sheep and cattle) for Bartonella using ribC-PCR. Positive samples from the ribC-PCR assay for Bartonella spp. were further subjected to PCR assays targeting the ITS, rpoB and gltA genes followed by phylogenetic analyses. Bartonella DNA was detected in 2.19% (34/1,549) of tick samples, and the ITS, rpoB and gltA genes of ribC gene-positive samples were amplified to identify nine samples of Bartonella melophagi. In this study, molecular analysis was used to assess the presence and genetic diversity of B. melophagi in ticks collected from sheep and cattle from Xinjiang, China. This study provides new information on the presence and identity of B. melophagi in ticks from sheep and cattle

Aspect Matters : Unraveling Microclimate Impacts on Mountain Greenness and Greening

Altres ajuts: the Fundación Ramón Areces grant CIVP20A6621Mountains are vital ecosystems, yet predicting plant growth there is complex due to diverse microclimates on slopes. Equatorial-facing slopes (EFSs) are drier and warmer, and polar-facing slopes (PFSs) are wetter and colder, than their regional macroclimates. Analyzing Moderate Resolution Imaging Spectroradiometer normalized difference vegetation index from 2003 to 2021, we identified a clear geographic pattern of differences in greenness on the two opposite aspects: EFSs were greener than PFSs in cold areas and were browner in dry areas, mainly determined by the relative importance of limitations of temperature and water. PFSs had stronger greening trends than did EPSs, leading to a weakening difference in greenness between EPSs and PFSs in temperature-limited areas, and an intensifying difference in water-limited areas. This suggests the alleviation of temperature limitation and exacerbation of water limitation. Montane ecosystems constitute a "natural laboratory" for deepening our understanding of the temporal evolution of the climatic control of vegetation growth with a space-for-time substitution

Thermal Environment Control at Deep Intelligent Coal Mines in China Based on Human Factors

Mechanical cooling of the entire mining tunnel, widely used in deep coal mines, has a significant energy-intensive consumption, particularly for intelligent mining tunnels. Therefore, localized cooling would benefit the intelligent mining industry. Current studies on the temperature, relative humidity, and air velocity under localized cooling for working protection are still unclear. A modified predicted heat strain model that is appropriate for warm and humid conditions is presented in this article and calculated using MATLAB. Results reveal that air temperature was the primary factor affecting underground miners’ safety. Increasing air velocity would improve the working environment when the thermal humidity index is lower than 32. Reducing total working time and wet bulb temperature would benefit underground miners’ security. For the cooling of intelligent mining tunnels, the recommended air velocity would be 2 m/s, and the maximum wet bulb temperature would be 28 °C for the 6-h working period and 26 °C for the 8-h working period. Results would be beneficial to the cooling of intelligent mining in China