The thylakoid protease Deg1 is involved in photosystem‐II assembly in Arabidopsis thaliana

DegP proteases have been shown to possess both chaperone and protease activities. The proteolytic activities of chloroplast DegP‐like proteases have been well documented. However, whether chloroplast Deg proteases also have chaperone activities has remained unknown. Here we show that chloroplast Deg1 also has chaperone activities, like its Escherichia coli ortholog DegP. Transgenic plants with reduced levels of Deg1 accumulated normal levels of different subunits of the major photosynthetic protein complexes, but their levels of photosystem‐II (PSII) dimers and supercomplexes were reduced. In vivo pulse‐chase protein labeling experiments showed that the assembly of newly synthesized proteins into PSII dimers and supercomplexes was impaired, although the synthesis rate of chloroplast proteins was unaffected in the transgenic lines. Protein overlay assays provided direct evidence that Deg1 interacts with the PSII reaction center protein D2. These results suggest that Deg1 assists the assembly of the PSII complex, probably through interaction with the PSII reaction center D2 protein.     

Isoform-selective inhibition of chrysin towards human cytochrome P450 1A2. Kinetics analysis,molecular docking,and molecular dynamics simulations

Our kinetics studies demonstrated that the nature product chrysin exhibited a high inhibitory affinity of 54 nM towards human cytochrome P450 1A2 and was comparable to α-naphthoflavone (49 nM), whereas it represented a moderate affinity of 5225 nM against human cytochrome P450 2C9. However, it remains unclear how this inhibitor selectively binds 1A2. To better understand the isoform selectivity of chrysin, molecular docking and molecular dynamics simulations were performed. Chrysin formed a strong H-bond with Asp313 of 1A2. The stacking interactions with Phe226 also contributed to its tight binding to 1A2. The larger and much more open active site architectures of 2C9 may explain the weaker inhibitory affinity of chrysin towards 2C9. The predicted binding free energies suggest that chrysin preferred 1A2 (ΔG_{bind, pred} = ?23.11 kcal/mol) to 2C9 (?20.41 kcal/mol). Additionally, the present work revealed that 7-hydroxy-flavone bound to 1A2 in a similar pattern as chrysin and represented a slightly less negative predicted binding free energy, which was further validated by our kinetics analysis (IC₅₀ = 240 nM). Results of the study can provide insight for designing novel isoform-selective 1A2 inhibitors.     

Nuclear migration: rock and roll facilitated by dynein and kinesin

The nucleus encounters other organelles as well as high cytoplasmic pressures during its migration within the cell. A new study describes how the action of kinesin and dynein motors is coordinated at the nuclear envelope to rock and roll the nucleus in Caenorhabditis elegans.     

Synthesis and SAR of (piperazin-1-yl-phenyl)-arylsulfonamides: A novel series of atypical antipsychotic agents

(Piperazin-1-yl-phenyl)-arylsulfonamides were synthesized and identified to show high affinities for both 5-HT_2C and 5-HT₆ receptors. Among them, naphthalene-2-sulfonic acid isopropyl-[3-(4-methyl-piperazin-1-yl)-phenyl]-amide (6b) exhibits the highest affinity towards both 5-HT_2C (IC₅₀ = 4 nM) and 5-HT₆ receptors (IC₅₀ = 3 nM) with good selectivity over other serotonin (5-HT_1A, 5-HT_2A, and 5-HT₇) and dopamine (D₂–D₄) receptor subtypes. In 5-HT_2C and 5-HT₆ receptor functional assays, this compound showed considerable antagonistic activity for both receptors.     

Discovery of tetrahydroisoquinoline (THIQ) derivatives as potent and orally bioavailable LFA-1/ICAM-1 antagonists

This letter describes the discovery of a novel series of tetrahydroisoquinoline (THIQ)-derived small molecules that potently inhibit both human T-cell migration and super-antigen induced T-cell activation through disruption of the binding of integrin LFA-1 to its receptor, ICAM-1. In addition to excellent in vitro potency, 6q shows good pharmacokinetic properties and its ethyl ester (6t) demonstrates good oral bioavailability in both mouse and rat. Either intravenous administration of 6q or oral administration of its ethyl ester (6t) produced a significant reduction of neutrophil migration in a thioglycollate-induced murine peritonitis model.     

酿酒酵母乙醇脱氢酶2(ADH2)基因的克隆表达及活性验证

为了从酿酒酵母Saccharomyces cerevisiae中克隆出乙醇脱氢酶2(Alcoholdehy drogenase2,ADH2)基因并使之在大肠杆菌中高效表达。以酿酒酵母细胞中提取的总RNA为模板,通过反转录获得酿酒酵母乙醇脱氢酶2基因,连接到表达载体pTAT上,得到重组表达质粒pTAT-ADH2,将此重组质粒转化到大肠杆菌BL21中,重组工程菌株经IPTG诱导表达得到ADH2蛋白。将该蛋白纯化后,在体外进行活性检测和小鼠体内进行毒理试验,检测ADH2的酶活性。测序结果表明克隆的基因与GenBank中所报道的adh2基因序列有90%的同源性,经SDS-PAGE电泳分析,目的蛋白得到了有效表达,蛋白条带扫描分析表明,表达量占总蛋白的50%左右,纯化得到的蛋白在小鼠体内进行毒理试验,显示出一定的活性。酿酒酵母adh2基因的克隆正确,不仅在大肠杆菌中进行了高效表达而且表现出了较好的酶活性。     

Determination of ethyl glucuronide in hair samples of Chinese people by protein precipitation (PPT) and large volume injection-gas chromatography-tandem mass spectrometry (LVI-GC/MS/MS)

Ethyl glucuronide (EtG) has been shown to be a suitable marker of excessive alcohol consumption. Determination of EtG in hair samples may help to differentiate social drinkers from alcoholics, and this testing can be widely used in forensic science, treatment programs, workplaces, military bases as well as driving ability test to provide legal proof of drinking. A method for determination of EtG in hair samples using large volume injection-gas chromatography-tandem mass spectrometry (LVI-GC/MS/MS) was developed and validated. Hair samples (in 1 mL deionized water) were ultrasonicated for 1h and incubated overnight; these samples were then deproteinated to remove impurities and derivatisated with 15 μL of pyridine and 30 μL of BSTFA. EtG was detected using GC/MS/MS in multiple-reaction monitoring mode. This method exhibited good linearity: y=0.0036 x+0.0437, R2=0.9993, the limit of detection and the limit of quantification were 5 pg/mg and 10 pg/mg, respectively. The extraction recoveries were more than 60%, and the inter-day and intra-day relative standard deviations (RSD) were less than 15%. This method has been applied to the analysis of EtG in hair samples from 21 Chinese subjects. The results for samples obtained from all of those who were teetotallers were negative, and the results for the other 15 samples ranged from 10 to 78 pg/mg, except for one negative sample. These data are the basis for interpretation of alcohol abuse.     

Quantitative proteomic analysis of ribosomal protein L35b mutant of Saccharomyces cerevisiae

Recent studies have revealed that in higher eukaryotes, several ribosomal proteins are involved in some pathological events or developmental defects, indicating that ribosomal proteins perform unconventional functions other than protein biosynthesis. To obtain an insight into the novel roles of ribosomal proteins, we aimed to analyze the changes in proteome expression in ribosomal protein mutants by using Saccharomyces cerevisiae as a model system. We introduced the rpl35bΔ mutation into the 4159 green fluorescent protein (GFP)-tagged yeast strains by using the synthetic genetic array (SGA) method, and performed quantitative proteomic analysis by using a multilabel microplate reader and flow cytometer. We identified 22 upregulated and 20 downregulated proteins in the rpl35bΔ mutant. These proteins were primarily classified into the Gene Ontology (GO) categories of cellular biosynthetic process, translation, protein or nucleotide metabolic process, cell wall organization and biogenesis, and hyperosmotic response. We also investigated the correlation between the mRNA and protein levels of the identified proteins. Our results show that a ribosomal protein mutation can lead to perturbation in the expression of several proteins, including some other ribosomal proteins. Furthermore, our approach of combining a library of GFP-tagged yeast strains and the SGA method provides an effective and highly sensitive method for dynamic analysis of the effects of various mutations on proteome expression.     

Investigating phenological changes using MODIS vegetation indices in deciduous broadleaf forest over continental U.S. during 2000–2008

Vegetation phenology describing the seasonal cycle of plants is currently one of the main concerns in the study of climate change and carbon balance estimation in ecosystems. Remote sensing techniques which can capture canopy reflectance allow vegetation photosynthetic capacity to be assessed. In this study, the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI) and Leaf Area Index (LAI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) measurements were used to identify onset date of greenness in deciduous broadleaf forest (DBF) over the continental United States from year 2000 to 2008. Onset dates determined by these three indices were compared with North American First Leaf Lilac Phenology Data over the same time period. NDVI has a best agreement with the field data among the three vegetation indices. Spatial analysis was performed on the onset dates predicted with NDVI. Four major conclusions were drawn from this study are: 1) onset dates are not only dependent on latitude but also associated with ecoregions and altitudes; 2) onset of greenness moves northward gradually and the average change of onset dates along latitude is about 3 days per degree. Interannual variability of onset dates is greater at higher latitudes (> 43 °N) than at lower latitudes (≤ 43 °N); 3) at the same latitude, DBF in mountain area tends to green up latter and coastal forest tends to green up earlier than other ecoregions; and 4) the impact of altitude is more obvious when the range of elevation achieves more than 1000 m. These conclusions provide insight for assessing vegetation indices in determining onset date of greenness at regional scale, and can be exploited to analyze the impacts of climate change on terrestrial ecosystem.     

Estimating the regional evapotranspiration in Zhalong wetland with the Two-Source Energy Balance (TSEB) model and Landsat7/ETM+ images

This paper aims to integrate a numerical model, vegetation index, and regional evapotranspiration estimation to assess the water cycle in Zhalong wetland, China with the aid of remote sensing technologies. An interdisciplinary analysis was performed to study the eco-hydrological characteristics of the wetland ecosystem. In particular, a new solution for solving the Two-Source Energy Balance (TSEB) was developed and applied. This new solution method is based on a definition of the aerodynamic temperature in a two-layer ground surface structure. Following this new solution for TSEB, the outputs of the Surface Energy Balance Algorithm (SEBAL) may be used as the inputs for TSEB to avoid the complex calculations of the bulk boundary layer and soil surface resistance. The new solution method makes the implementation of TSEB much easier when bi-directional thermal infrared remote sensing images are not available. Daily evapotranspiration and vegetation index of the wetland were calculated from six scenes of Landsat7/ETM+ remote sensing images acquired during 2001 and 2002 in our case study. Spatial distribution of daily evapotranspiration was also provided to help realize the wetland condition. The seasonal changes of vegetation index and evapotranspiration for some typical wetland ground surfaces were analyzed and presented as well to explore the multitemporal variations of plant species holistically. Ultimately, such integrative analysis aids in understanding the general biological patterns associated with these wetland vegetation cover, while specific situations of the wetland ecosystem can be recognized.