Research review on methods of grassland health assessment.

Grassland health refers to the degree to which the integrity of soil and ecological processes is maintained, which primarily reflects the health status and productivity of grasslands. Evaluating the degree of grassland health is vital for the sustainable develop of grasslands. There are many methods for evaluating grassland health, with advantages and disadvantages for each one. However, there is still a lack of systematic literature offering an overview of methods of grassland health assessment and their applicability. We summarized 10 methods of grassland health assessment, including vigor-organization-resilience (VOR) index evaluation model, condition-vigor-organization-resilience (CVOR) index evaluation model, principal component analysis method, analytic hierarchy process, cluster analysis method, grey relational analysis, pressure-state-response evaluation model, fuzzy comprehensive evaluation method, comprehensive evaluation model of grassland health, and evaluation model using remote sensing technology. The advantages, disadvantages, and applicability of these methods were discussed, aiming to provide scientific basis for selecting more suitable methods of grassland health assessment for different scenarios in the future.

Comparative transcriptome and DNA methylation analysis in temperature-sensitive genic male sterile wheat BS366.

BACKGROUND: Known as the prerequisite component for the heterosis breeding system, the male sterile line determines the hybrid yield and seed purity. Therefore, a deep understanding of the mechanism and gene network that leads to male sterility is crucial. BS366, a temperature-sensitive genic male sterile (TGMS) line, is male sterile under cold conditions (12 °C with 12 h of daylight) but fertile under normal temperature (20 °C with 12 h of daylight). RESULTS: During meiosis, BS366 was defective in forming tetrads and dyads due to the abnormal cell plate. During pollen development, unusual vacuolated pollen that could not accumulate starch grains at the binucleate stage was also observed. Transcriptome analysis revealed that genes involved in the meiotic process, such as sister chromatid segregation and microtubule-based movement, were repressed, while genes involved in DNA and histone methylation were induced in BS366 under cold conditions. MethylRAD was used for reduced DNA methylation sequencing of BS366 spikes under both cold and control conditions. The differentially methylated sites (DMSs) located in the gene region were mainly involved in carbohydrate and fatty acid metabolism, lipid metabolism, and transport. Differentially expressed and methylated genes were mainly involved in cell division. CONCLUSIONS: These results indicated that the methylation of genes involved in carbon metabolism or fatty acid metabolism might contribute to male sterility in BS366 spikes, providing novel insight into the molecular mechanism of wheat male sterility.

Genome-wide identification and transcriptional characterization of DNA methyltransferases conferring temperature-sensitive male sterility in wheat.

BACKGROUND: DNA methyltransferase (DMT) genes contribute to plant stress responses and development by de novo establishment and subsequent maintenance of DNA methylation during replication. The photoperiod and/or temperature-sensitive genic male sterile (P/TGMS) lines play an important role in hybrid seed production of wheat. However, only a few studies have reported on the effect of DMT genes on temperature-sensitive male sterility of wheat. Although DMT genes have been investigated in some plant species, the identification and analysis of DMT genes in wheat (Triticum aestivum L.) based on genome-wide levels have not been reported. RESULTS: In this study, a detailed overview of phylogeny of 52 wheat DMT (TaDMT) genes was presented. Homoeolog retention for TaDMT genes was significantly above the average retention rate for whole-wheat genes, indicating the functional importance of many DMT homoeologs. We found that the strikingly high number of TaDMT genes resulted mainly from the significant expansion of the TaDRM subfamily. Intriguingly, all 5 paralogs belonged to the wheat DRM subfamily, and we speculated that tandem duplications might play a crucial role in the TaDRM subfamily expansion. Through the transcriptional analysis of TaDMT genes in a TGMS line BS366 and its hybrids with the other six fertile lines under sterile and fertile conditions, we concluded that TaCMT-D2, TaMET1-B1, and TaDRM-U6 might be involved in male sterility in BS366. Furthermore, a correlation analysis showed that TaMET1-B1 might negatively regulate the expression of TaRAFTIN1A, an important gene for pollen development, so we speculated regarding an epigenetic regulatory mechanism underlying the male sterility of BS366 via the interaction between TaMET1-B1 and TaRAFTIN1A. CONCLUSIONS: Our findings presented a detailed phylogenic overview of the DMT genes and could provide novel insights into the effects of DMT genes on TGMS wheat.

Bemisia tabaci (Hemiptera: Aleyrodidae) Insecticide Resistance in Shandong Province, China.

The Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) complex comprises important pests and virus vectors in agricultural crops worldwide. In China, B. tabaci has spread to more than 20 provinces and caused severe losses of vegetables, fruits, and ornamental plants. However, B. tabaci has developed resistance to many insecticidal classes in Shandong Province, eastern China. In this study, we investigated the cryptic species, insecticide resistance and detoxifying enzymes of B. tabaci from six representative locations exhibiting severe damage in Shandong. At four of the six locations, B. tabaci Mediterranean (MED) comprised 100% of the samples collected. In a further two locations, species composition was predominantly (>94%) MED with B. tabaci Middle East-Asia Minor 1 (MEAM1), comprising a low proportion (<6%) of the samples collected. For all field populations, avermectin was the most effective insecticide against adult B. tabaci, pyriproxyfen had a significant effect on B. tabaci eggs and field populations were susceptible to pymetrozine. Six field populations of B. tabaci have developed low-to-moderate resistance to neonicotinoids. The detoxifying enzyme activity of carboxylesterase, glutathione S-transferase, and multifunctional oxidase were quantified. Multifunctional oxidase and glutathione S-transferase activity were positively correlated with insecticide resistance in several B. tabaci populations.

Stress Ratio and Notch Effects on the Very High Cycle Fatigue Properties of a Near-Alpha Titanium Alloy.

Ultrasonic fatigue tests up to 1010 cycles were performed on a turbine engine titanium alloy (Ti-8Al-1Mo-1V) at the stress ratio (R) of -1 with smooth specimens and at R = -1, 0.1 and 0.5 with notched specimens. As a result, with increase of fatigue life, the source of reduced fatigue life caused by multi-point surface crack initiation changes from crack propagation stage to crack initiation stage in the high cycle fatigue regime. Notch effect further promotes the degeneration of high cycle and very high cycle fatigue strength at R > -1. The bilinear model, extended from the Goodman method, can better estimate the mean stress sensitivity of this titanium alloy. The fatigue mean stress sensitivity and fatigue-creep mean stress sensitivity of this material increased with the increase of fatigue life. The new model, based on the Murakami model, can provide more appropriate predictions for notch fatigue strength.

Chiral phosphoric acid-catalyzed direct asymmetric mannich reaction of cyclic C-acylimines with simple ketones: facile access to C2-quaternary indolin-3-ones.

A chiral Brønsted acid-catalyzed direct asymmetric Mannich reaction of simple ketones with cyclic C-acylimines has been established for the synthesis of C2-quaternary indolin-3-ones. In the presence of 5-10 mol% chiral phosphoric acid, a series of 2-(2-oxo-2-phenylethyl)-2-arylindolin-3-ones were obtained in good to high yield with up to 99% ee. The adducts obtained could be readily converted into indolines, tricyclic indolin-3-ones, and tetracyclic tetrahydro-indolo[1,2-a]quinolines by simple modifications.

Organocatalytic Asymmetric Decarboxylative Mannich Reaction of ß-Keto Acids with Cyclic α-Ketiminophosphonates: Access to Quaternary α-Aminophosphonates.

An organocatalytic asymmetric decarboxylative Mannich reaction of ß-keto acids with cyclic α-ketiminophosphonates has been developed. By using saccharide-derived bifunctional amine-thiourea catalysts bearing an axial chiral binaphthyl scaffold, a wide range of quaternary α-amino-γ-oxophosphonates were obtained in up to 93% yield and >99% ee. Furthermore, two interesting α-aminophosphonate derivatives were synthesized from the corresponding decarboxylative Mannich product via simple transformations.

Transcriptome analysis of wheat seedling and spike tissues in the hybrid Jingmai 8 uncovered genes involved in heterosis.

MAIN CONCLUSION: Transcriptome analysis was carried out for wheat seedlings and spikes from hybrid Jingmai 8 and both inbred lines to unravel mechanisms underlying heterosis. Heterosis, known as one of the most successful strategies for increasing crop yield, has been widely exploited in plant breeding systems. Despite its great importance, the molecular mechanism underlying heterosis remains elusive. In the present study, RNA sequencing (RNA-seq) was performed on the seedling and spike tissues of the wheat (Triticum aestivum) hybrid Jingmai 8 (JM8) and its homozygous parents to unravel the underlying mechanisms of wheat heterosis. In total, 1686 and 2334 genes were identified as differentially expressed genes (DEGs) between the hybrid and the two inbred lines in seedling and spike tissues, respectively. Gene Ontology analysis revealed that DEGs from seedling tissues were significantly enriched in processes involved in photosynthesis and carbon fixation, and the majority of these DEGs expressed at a higher level in JM8 compared to both inbred lines. In addition, cell wall biogenesis and protein biosynthesis-related pathways were also significantly represented. These results confirmed that a combination of different pathways could contribute to heterosis. The DEGs between the hybrid and the two inbred progenitors from the spike tissues were significantly enriched in biological processes related to transcription, RNA biosynthesis and molecular function categories related to transcription factor activities. Furthermore, transcription factors such as NAC, ERF, and TIF-IIA were highly expressed in the hybrid JM8. These results may provide valuable insights into the molecular mechanisms underlying wheat heterosis.

Nematic superconducting state in iron pnictide superconductors.

Nematic order often breaks the tetragonal symmetry of iron-based superconductors. It arises from regular structural transition or electronic instability in the normal phase. Here, we report the observation of a nematic superconducting state, by measuring the angular dependence of the in-plane and out-of-plane magnetoresistivity of Ba0.5K0.5Fe2As2 single crystals. We find large twofold oscillations in the vicinity of the superconducting transition, when the direction of applied magnetic field is rotated within the basal plane. To avoid the influences from sample geometry or current flow direction, the sample was designed as Corbino-shape for in-plane and mesa-shape for out-of-plane measurements. Theoretical analysis shows that the nematic superconductivity arises from the weak mixture of the quasi-degenerate s-wave and d-wave components of the superconducting condensate, most probably induced by a weak anisotropy of stresses inherent to single crystals.

Catalytic Asymmetric Mukaiyama-Mannich Reaction of Cyclic C-Acylimines with Difluoroenoxysilanes: Access to Difluoroalkylated Indolin-3-ones.

A catalytic enantioselective Mukaiyama-Mannich reaction of cyclic C-acylimines with difluoroenoxysilanes is reported. (S)-TRIP enables the enantioselective synthesis of a series of novel difluoroalkylated indolin-3-ones bearing a quaternary stereocenter in up to 97% yield and 98% ee. The synthetic utility of this protocol is highlighted by efficient conversion of the products to the corresponding indolin-3-one derivatives without any erosion of the enantiopurity.

Classification of a Hypervirulent Aeromonas hydrophila Pathotype Responsible for Epidemic Outbreaks in Warm-Water Fishes.

Lineages of hypervirulent Aeromonas hydrophila (vAh) are the cause of persistent outbreaks of motile Aeromonas septicemia in warm-water fishes worldwide. Over the last decade, this virulent lineage of A. hydrophila has resulted in annual losses of millions of tons of farmed carp and catfish in the People's Republic of China and the United States (US). Multiple lines of evidence indicate US catfish and Asian carp isolates of A. hydrophila affiliated with sequence type 251 (ST251) share a recent common ancestor. To address the genomic context for the putative intercontinental transfer and subsequent geographic spread of this pathogen, we conducted a core genome phylogenetic analysis on 61 Aeromonas spp. genomes, of which 40 were affiliated with A. hydrophila, with 26 identified as epidemic strains. Phylogenetic analyses indicate all ST251 strains form a coherent lineage affiliated with A. hydrophila. Within this lineage, conserved genetic loci unique to A. hydrophila were identified, with some genes present in consistently higher copy numbers than in non-epidemic A. hydrophila isolates. In addition, results from analyses of representative ST251 isolates support the conclusion that multiple lineages are present within US vAh isolated from Mississippi, whereas vAh isolated from Alabama appear clonal. This is the first report of genomic heterogeneity within US vAh isolates, with some Mississippi isolates showing closer affiliation with the Asian grass carp isolate ZC1 than other vAh isolated in the US. To evaluate the biological significance of the identified heterogeneity, comparative disease challenges were conducted with representatives of different vAh genotypes. These studies revealed that isolate ZC1 yielded significantly lower mortality in channel catfish, relative to Alabama and Mississippi vAh isolates. Like other Asian vAh isolates, the ZC1 lineage contains all core genes for a complete type VI secretion system (T6SS). In contrast, more virulent US isolates retain only remnants of the T6SS (clpB, hcp, vgrG, and vasH) which may have functional implications. Collectively, these results characterize a hypervirulent A. hydrophila pathotype that affects farmed fish on multiple continents.

[Resistance risk, cross-resistance and biochemical resistance mechanism of Laodelphax striatellus to buprofezin].

In order to investigate the resistance development law and biochemical resistance mechanism of Laodelphax striatellus to buprofezin, spraying rice seedlings was used to continuously screen resistant strains of L. striatellus and dipping rice seedlings was applied to determine the toxicity and cross-resistance of L. striatellus to insecticides. After 32-generation screening with buprofezin, L. striatellus developed 168.49 folds resistance and its reality heritability (h2) was 0.11. If the killing rate was 80%-90%, L. striatellus was expected to develop 10-fold resistance to buprofezin only after 5 to 6 generations breeding. Because the actual reality heritability of field populations was usually lower than that of the resistant strains, the production of field populations increasing with 10-fold resistance would need much longer time. The results of cross-resistance showed that resistant strain had high level cross-resistance with thiamethoxam and imidacloprid, low level cross-resistance with acetamiprid, and no cross-resistance with pymetrozine and chlorpyrifos. The activity of detoxification enzymes of different strains and the syergism of synergist were measured. The results showed that cytochrome P450 monooxygenase played a major role in the resistance of L. striatellus to buprofezin, the esterase played a minor role and the GSH-S-transferase had no effect. Therefore, L. striatellus would have high risk to develop resistance to buprofezin when used in the field and might be delayed by using pymetrozine and chlorpyrifos.

Fatigue Property of Open-Hole Steel Plates Influenced by Bolted Clamp-up and Hole Fabrication Methods.

Steel plates with open holes are commonly used in structural assemblies. The fatigue properties of such details are influenced by bolted clamp-up and hole fabrication methods. The fracture surface, stiffness degradation and fatigue life of test specimens are investigated in detail and compared with the contemporary test data. The analysis results show that the presence of draglines greatly influences the fatigue crack initiation at the open-hole cut by laser. The bolted clamp-up condition greatly enhances the stiffness and the fatigue life of the open-hole details. A discussion is also made from a comparison with the referred fatigue life of hole fabrication details, such as the influence of plate thickness and plasma cutting, drilling and oxy-fuel gas cutting, with the details studied herein. This work could enhance the understanding of the fatigue property and design of such details.

Evaluation of Fatigue Strength Improvement by CFRP Laminates and Shot Peening onto the Tension Flanges Joining Corrugated SteelWebs.

Corrugated steel web with inherent high out-of-plane stiffness has a promising application in configuring large span highway bridge girders. Due to the irregularity of the configuration details, the local stress concentration poses a major fatigue problem for the welded flange plates of high strength low alloy structural steels. In this work, the methods of applying CFRP laminate and shot peening onto the surfaces of the tension flanges were employed with the purpose of improving the fatigue strength of such configuration details. The effectiveness of this method in the improvement of fatigue strength has been examined experimentally. Test results show that the shot peening significantly increases hardness and roughness in contrast to these without treatment. Also, it has beneficial effects on the fatigue strength enhancement when compared against the test data of the joints with CFRP strengthening. The stiffness degradation during the loading progress is compared with each treatment. Incorporating the stress acting on the constituent parts of the CFRP laminates, a discussion is made regarding the mechanism of the retrofit and related influencing factors such as corrosion and economic cost. This work could enhance the understanding of the CFRP and shot peening in repairing such welded details and shed light on the reinforcement design of welded joints between corrugated steel webs and flange plates.

DSTYK kinase domain ablation impaired the mice capabilities of learning and memory in water maze test.

DSTYK (Dual serine/threonine and tyrosine protein kinase) is a putative dual Ser/Thr and Tyr protein kinase with unique structural features. It is proposed that DSTYK may play important roles in brain because of its high expression in most brain areas. In the present study, a DSTYK knockout (KO) mouse line with the ablation of C-terminal of DSTYK including the kinase domain was generated to study the physiological function of DSTYK. The DSTYK KO mice are fertile and have no significant morphological defects revealed by Nissl staining compared with wildtype mice. Open field test and rotarod test showed there is no obvious difference in basic motor and balance capacity between the DSTYK homozygous KO mice and DSTYK heterozygous KO mice. In water maze test, however, the DSTYK homozygous KO mice show impaired capabilities of learning and memory compared with the DSTYK heterozygous KO mice.

[Evaluation of ecosystem service values of the forests of Shennongjia Nature Reserve].

As an ecological protected area for rare animals and plants in a subtropical forest zone, Shennongjia National Reserve plays an important role in the study of biodiversity in China. By using the market value, shade-price and opportunity-cost methods, the forest ecosystem service values of Shennongjia National Nature Reserve were evaluated, including forest production, recreation and culture, water conservation, soil conservation, gas regulation, environment purification, nutrient circulation and biodiversity conservation. The total value of the Shennongjia Nature Reserve was approximately 204.33 x 10(8) yuan RMB x a(-1). The values of the different functions were in order of biodiversity conservation (68.5%) > soil conservation (12.7%) > recreation and culture (4.9%) > gas regulation (4.8%) > forest production (4.2%) > water conservation (3.9%) > environment purification (0.7%) > nutrient circulation (0.3%). The values with respect to utility were in sequence of unused value (68.5%) > indirect value in use (22.4% ) > direct value in use (9.1%).

Identification and analysis of differential miRNAs in PK-15 cells after foot-and-mouth disease virus infection.

The alterations of MicroRNAs(miRNAs) in host cell after foot-and-mouth disease virus (FMDV) infection is still obscure. To increase our understanding of the pathogenesis of FMDV at the post-transcriptional regulation level, Solexa high-throu MicroRNAs (miRNAs) play an important role both in the post-transcriptional regulation of gene expression and host-virus interactions. Despite investigations of miRNA expression ghput sequencing and bioinformatic tools were used to identify differentially expressed miRNAs and analyze their functions during FMDV infection of PK-15 cells. Results indicated that 9,165,674 and 9,230,378 clean reads were obtained, with 172 known and 72 novel miRNAs differently expressed in infected and uninfected groups respectively. Some of differently expressed miRNAs were validated using stem-loop real-time quantitative RT-PCR. The GO annotation and KEGG pathway analysis for target genes revealed that differently expressed miRNAs were involved in immune response and cell death pathways.

Identification of genes preferentially expressed by highly virulent piscine Streptococcus agalactiae upon interaction with macrophages.

Streptococcus agalactiae, long recognized as a mammalian pathogen, is an emerging concern with regard to fish. In this study, we used a mouse model and in vitro cell infection to evaluate the pathogenetic characteristics of S. agalactiae GD201008-001, isolated from tilapia in China. This bacterium was found to be highly virulent and capable of inducing brain damage by migrating into the brain by crossing the blood-brain barrier (BBB). The phagocytosis assays indicated that this bacterium could be internalized by murine macrophages and survive intracellularly for more than 24 h, inducing injury to macrophages. Further, selective capture of transcribed sequences (SCOTS) was used to investigate microbial gene expression associated with intracellular survival. This positive cDNA selection technique identified 60 distinct genes that could be characterized into 6 functional categories. More than 50% of the differentially expressed genes were involved in metabolic adaptation. Some genes have previously been described as associated with virulence in other bacteria, and four showed no significant similarities to any other previously described genes. This study constitutes the first step in further gene expression analyses that will lead to a better understanding of the molecular mechanisms used by S. agalactiae to survive in macrophages and to cross the BBB.

High cycle fatigue behavior of implant Ti-6Al-4V in air and simulated body fluid.

Ti-6Al-4V implants that function as artificial joints are usually subjected to long-term cyclic loading. To study long-term fatigue behaviors of implant Ti-6Al-4V in vitro and in vivo conditions exceeding 107 cycles, constant stress amplitude fatigue experiments were carried out at ultrasonic frequency (20 kHz) with two different surface conditions (ground and polished) in ambient air and in a simulated body fluid. The initiation mechanisms of fatigue cracks were investigated with scanning electron microscopy. Improvement of fatigue strength is pronounced for polished specimens below 106 cycles in ambient air since fatigue cracks are initiated from surfaces of specimens. While the cycles exceed 106, surface conditions have no effect on fatigue behaviors because the defects located within the specimens become favorable sites for crack initiation. The endurance limit at 108 cycles of polished Ti-6Al-4V specimens decreases by 7% if it is cycled in simulated body fluid instead of ambient air. Fracture surfaces show that fatigue failure is initiated from surfaces in simulated body fluid. Surface improvement has a beneficial effect on fatigue behaviors of Ti-6Al-4V at high stress amplitudes. The fatigue properties of Ti-6Al-4V deteriorate and the mean endurance limits decrease significantly in simulated body fluid.

Inactivation of ß-catenin results in the reduction of postnatal body weight gain.

Arcuate nucleus of hypothalamus (ARH) is the core component in the regulation circuits of food intake and energy homeostasis. ARH projections to other parts of the hypothalamus and to extrahypothalamic areas are established in the postnatal two weeks, which is a pivotal stage for individual development. ß-Catenin, a cell adhesion protein and also the mediator of canonical Wnt signaling pathway, plays an important role in embryonic development and adult homeostasis. However, whether ß-catenin plays any roles in the development of hypothalamus is not clear. Here, we report that perinatal conditional knockout of ß-catenin by CamKIIα-Cre in forebrain reduces body weight gain from P8 and dramatically shortens life span. Quantitative PCR and in situ hybridization results showed the expression of NPY mRNA in the ARH of ß-catenin CKO mice at P15 is obviously increased compared with that of littermate controls, whereas the expression of POMC mRNA is significantly decreased, which suggested the reduction of postnatal body weight gain might be due to the deficiency of food intake. Together, ß-catenin might play an important role in the regulation of food intake and postnatal body weight gain probably through affecting the development of ARH circuits.