Molecular cloning and characterization of an actindepolymerizing factor gene in Hevea brasiliensis

Actin-depolymerizing factor (ADF) plays important roles in regulating actin dynamics by maintaining the optimum equilibrium between unpolymerized actin molecules and assembled actin filaments in different cellular processes. In this study, the first ADF gene in Hevea brasiliensis designated as HbADF, was isolated. The HbADF contained an open reading frame (ORF) encoding 139 amino acids. The deduced HbADF showed high identities to plants ADF proteins. Besides a conserved ADF domain, HbADF also contained putative actin and specific F-actin binding sites, phosphorylation site and possible CAM (calmodulin) combining region. The phylogenetic analysis indicated that HbADF was clustered in the subclass I. Being consistent with  phylogenetic result, the expression of HbADF was constitutive. The HbADF transcripts were upregulated by ethephon and wounding treatments; whereas, HbADF was firstly induced, and then gradually downregulated by jasmonic acid. The expression profiles and characterizations of HbADF suggested that HbADF might be  associated with latex regeneration and flow in H. brasiliensis.Key words: Actin cytoskeleton, actin-depolymerizing factor, expression analysis, Hevea brasiliensis, semiquantitative reverse-transcription polymerase chain reaction

Identification and characterization of genes associated with tapping panel dryness from Hevea brasiliensis latex using suppression subtractive hybridization

<p>Abstract</p> <p>Background</p> <p>Tapping panel dryness (TPD) is one of the most serious threats to natural rubber production. Although a great deal of effort has been made to study TPD in rubber tree, the molecular mechanisms underlying TPD remain poorly understood. Identification and systematical analyses of the genes associated with TPD are the prerequisites for elucidating the molecular mechanisms involved in TPD. The present study is undertaken to generate information about the genes related to TPD in rubber tree.</p> <p>Results</p> <p>To identify the genes related to TPD in rubber tree, forward and reverse cDNA libraries from the latex of healthy and TPD trees were constructed using suppression subtractive hybridization (SSH) method. Among the 1106 clones obtained from the two cDNA libraries, 822 clones showed differential expression in two libraries by reverse Northern blot analyses. Sequence analyses indicated that the 822 clones represented 237 unique genes; and most of them have not been reported to be associated with TPD in rubber tree. The expression patterns of 20 differentially expressed genes were further investigated to validate the SSH data by reverse transcription PCR (RT-PCR) and real-time PCR analysis. According to the Gene Ontology convention, 237 unique genes were classified into 10 functional groups, such as stress/defense response, protein metabolism, transcription and post-transcription, rubber biosynthesis, etc. Among the genes with known function, the genes preferentially expressed were associated with stress/defense response in the reverse library, whereas metabolism and energy in the forward one.</p> <p>Conclusions</p> <p>The genes associated with TPD were identified by SSH method in this research. Systematic analyses of the genes related to TPD suggest that the production and scavenging of reactive oxygen species (ROS), ubiquitin proteasome pathway, programmed cell death and rubber biosynthesis might play important roles in TPD. Therefore, our results not only enrich information about the genes related to TPD, but also provide new insights into understanding the TPD process in rubber tree.</p

A revisit to the impact of land use changes on the human well-being via altering the ecosystem provisioning services,”

It is widely acknowledged that land use changes (LUC) associated with climate variations are affecting the human wellbeing. This paper conducted a revisit to relevant researches on the impacts of LUC on human wellbeing via specifically altering the ecosystem provisioning services. First, the explorations on the influences of LUC on ecosystem provisioning services were reviewed, including the researches on the influences of LUC on agroecosystem services and forest and/or grassland ecosystem services. Then the quantitative identification of the impacts of LUC on ecosystem provisioning services was commented on. In the light of enhanced observation and valuation methods, several approaches to ecosystem services and improved models for assessing those ecosystem services were assessed. The major indicators used to uncover the influences of LUC on human wellbeing were summarized including the increase of inputs and the reduction of outputs in production and the augmented health risk induced by the irrational land uses. Finally, this paper uncovered the research gaps and proposed several research directions to address these gaps

A Revisit to the Impacts of Land Use Changes on the Human Wellbeing via Altering the Ecosystem Provisioning Services

It is widely acknowledged that land use changes (LUC) associated with climate variations are affecting the human wellbeing. This paper conducted a revisit to relevant researches on the impacts of LUC on human wellbeing via specifically altering the ecosystem provisioning services. First, the explorations on the influences of LUC on ecosystem provisioning services were reviewed, including the researches on the influences of LUC on agroecosystem services and forest and/or grassland ecosystem services. Then the quantitative identification of the impacts of LUC on ecosystem provisioning services was commented on. In the light of enhanced observation and valuation methods, several approaches to ecosystem services and improved models for assessing those ecosystem services were assessed. The major indicators used to uncover the influences of LUC on human wellbeing were summarized including the increase of inputs and the reduction of outputs in production and the augmented health risk induced by the irrational land uses. Finally, this paper uncovered the research gaps and proposed several research directions to address these gaps

Soil microbiome manipulation triggers direct and possible indirect suppression against <i>Ralstonia solanacearum</i> and <i>Fusarium oxysporum</i>

Soil microbiome manipulation can potentially reduce the use of pesticides by improving the ability of soils to resist or recover from pathogen infestation, thus generating natural suppressiveness. We simulated disturbance through soil fumigation and investigated how the subsequent application of bio-organic and organic amendments reshapes the taxonomic and functional potential of the soil microbiome to suppress the pathogens Ralstonia solanacearum and Fusarium oxysporum in tomato monocultures. The use of organic amendment alone generated smaller shifts in bacterial and fungal community composition and no suppressiveness. Fumigation directly decreased F. oxysporum and induced drastic changes in the soil microbiome. This was further converted from a disease conducive to a suppressive soil microbiome due to the application of organic amendment, which affected the way the bacterial and fungal communities were reassembled. These direct and possibly indirect effects resulted in a highly efficient disease control rate, providing a promising strategy for the control of the diseases caused by multiple pathogens

Two-dimensional germanium islands with Dirac signature on Ag2Ge surface alloy

Two-dimensional (2D) Dirac materials have attracted intense research efforts due to their promise for applications ranging from field-effect transistors and low-power electronics to fault-tolerant quantum computation. One key challenge is to fabricate 2D Dirac materials hosting Dirac electrons. Here, monolayer germanene is successfully fabricated on a Ag2Ge surface alloy. Scanning tunneling spectroscopy measurements revealed a linear energy dispersion relation. The latter was supported by density functional theory calculations. These results demonstrate that monolayer germanene can be realistically fabricated on a Ag2Ge surface alloy. The finding opens the door to exploration and study of 2D Dirac material physics and device applications

Analysis of pncA gene expression in pyrazinamide-resistant and multidrug-resistant <i>Mycobacterium tuberculosis</i>

Objective To compare the expression levels of pncA gene in pyrazinamide （PZA）-resistant and multidrug-resistant Mycobacterium tuberculosis before and after PZA drug stimulation， and to explore the relationship between PZA-resistant Mycobacterium tuberculosis and pncA gene expression. Methods PZA-resistant and multidrug-resistant Mycobacterium tuberculosis was cultured， and the minimal inhibitory concentration （MIC） of rifampicin and PZA was detected. The strains were cultured in medium containing 0 and 50 μg/mL PZA， and the expression level of pncA was detected by real-time fluorescence quantitative PCR. Results The MIC of PZA of 21 strains of Mycobacterium tuberculosis was ≥ 1 600 μg/mL，400-800 μg/mL for 12 strains， and 100-200 μg/mL in 5 strains，and their corresponding PZA resistance levels were defined as high，medium and low，respectively. The median MIC of rifampicin was 128， 128 and 64μg/mL， respectively. Chi-square test showed that there was no significant difference between any two groups （all P &gt; 0.05）. According to the relative quantitative 2-ΔΔCt method， the expression levels of pncA in the high，medium and low levels of PZA drug-resistant Mycobacterium tuberculosis was 0.904（0.202， 2.653）， 1.157（0.658， 1.511） and 1.147（0.372， 1.347）， and 1.544（0.611， 3.191）， 0.846（0.421， 1.237） and 0.726 （0.225， 3.017） in the 50 μg/mL treatment group，respectively. There was no significant difference in pncA gene expression between the control and PZA drug-containing culture groups（P &gt; 0.05）. Conclusion No significant changes are observed in the expression levels of pncA in multidrug-resistant and PZA-resistant Mycobacterium tuberculosis before and after PZA drug stimulation