Predicting the responses of forest distribution and aboveground biomass to climate change under RCP scenarios in southern China

In the past three decades, our global climate has been experiencing unprecedented warming. This warming has and will continue to significantly influence the structure and function of forest ecosystems. While studies have been conducted to explore the possible responses of forest landscapes to future climate change, the representative concentration pathways (RCPs) scenarios under the framework of the Coupled Model Intercomparison Project Phase 5 (CMIP5) have not been widely used in quantitative modeling research of forest landscapes. We used LANDIS‐II, a forest dynamic landscape model, coupled with a forest ecosystem process model (PnET‐II), to simulate spatial interactions and ecological succession processes under RCP scenarios, RCP2.6, RCP4.5 and RCP8.5, respectively. We also modeled a control scenario of extrapolating current climate conditions to examine changes in distribution and aboveground biomass (AGB) among five different forest types for the period of 2010–2100 in Taihe County in southern China, where subtropical coniferous plantations dominate. The results of the simulation show that climate change will significantly influence forest distribution and AGB. (i) Evergreen broad‐leaved forests will expand into Chinese fir and Chinese weeping cypress forests. The area percentages of evergreen broad‐leaved forests under RCP2.6, RCP4.5, RCP8.5 and the control scenarios account for 18.25%, 18.71%, 18.85% and 17.46% of total forest area, respectively. (ii) The total AGB under RCP4.5 will reach its highest level by the year 2100. Compared with the control scenarios, the total AGB under RCP2.6, RCP4.5 and RCP8.5 increases by 24.1%, 64.2% and 29.8%, respectively. (iii) The forest total AGB increases rapidly at first and then decreases slowly on the temporal dimension. (iv) Even though the fluctuation patterns of total AGB will remain consistent under various future climatic scenarios, there will be certain responsive differences among various forest types.     

稀土-落叶松单宁配合物的合成及抗真菌活性研究

以稀土(Re~(3+))和落叶松单宁(LT)为原料,采用液相合成法合成了5种廉价的稀土-落叶松单宁(Re~(3+)-LT)配合物,并通过红外光谱、X射线光电子能谱、紫外光谱以及配位数测定确定了配合物的结构.采用牛津杯法、琼脂稀释法测定配合物对黑曲霉、红曲霉、白腐菌、毛霉4种真菌的抑制作用.在抑菌方面,5种配合物对上述4种真菌均具有较强的抑制作用,其抑菌活性大小顺序为Ce~(3+)-LTGd~(3+)-LTLa~(3+)-LTNd~(3+)-LTYb~(3+)-LT,其中Ce~(3+)-LT对4种真菌的最小抑菌浓度分别为:1.6、1.6、0.8和1.6 g·L~(-1);Yb~(3+)-LT对4种真菌的最小抑菌浓度分别为:3.2、1.6、3.2和3.2 g·L~(-1).在杀菌方面,Yb~(3+)-LT的杀菌活性最强,其对4种真菌的最小杀菌浓度分别为:6.4、3.2、3.2和6.4 g·L~(-1).此外,尽管Nd~(3+)-LT和Gd~(3+)-LT具有较强的抑菌活性,但对黑曲霉和毛霉的杀菌作用较弱.     

基于地表温度-植被指数关系的地表温度降尺度方法研究

地表温度(Land Surface Temperature, LST)在空间上和时间上均存在很大的差异性。而通过卫星遥感技术来监测地表温度存在着空间分辨率和时间分辨率上的矛盾:空间分辨率高的卫星时间分辨率低,反之亦然。为了解决这个矛盾,首先利用TsHARP (An algorithm for sharpening thermal imagery)温度降尺度方法将LST_MODIS,1km(1km MODIS(Moderate-resolution Imaging Spectroradiometer)地表温度)图像(2004年9月9日上午)降尺度为LST_MODIS,500m(500m MODIS地表温度)图像。为了对降尺度LST_MODIS,500m图像进行验证,对研究区内同一天(2004年9月9日上午)的ETM图像的第6波段的辐亮度值升尺度到500m后,再利用Sobrino ETM(Enhanced Thematic Mapper)温度反演方法反演得到LST_ETM,500m(500m ETM地表温度)图像,将LST_ETM,500m图像作为当日地表温度的实测值,对降尺度LST_MODIS,500m图像的降尺度效果进行验证。对比结果表明降尺度LST_MODIS,500m图像更加精细刻画LST_MODIS,1km图像在空间上的分布格局;定量对比3种降尺度LST_MODIS,500m和LST_ETM,500m的RMSE分别为0.786、1.002,0.754℃,降尺度结果达到预期效果。     

Investigation of bacterial community diversity in water of Zoige Alpine Wetland

Spatial isolation is currently thought to represent one of the major factors resulting in bacteria genetic variation and population abundance. The bacterial diversity in a distinct environment Zoige Alpine Wetland located in the northeast of the Qinghai-Tibetan Plateau with the altitude 3400 m on average aroused our great attention. This area belongs to Qinghai-Tibetan cold climate zone with the mean annual temperature about 1 °C. Although several studies on bacterial diversity in Qinghai-Tibetan Plateau had been reported, there is no report on wetland water in this area. In this work, six water samples were collected and the water qualities including COD_Cr, NH₄⁺-N, NO₃^--N, NO₂^--N, TN, TP, TOC were investigated, of which results indicated that more than 80% samples sorted as II–V class of surface water sources according to the National Water Quality Standard of China (GB3838-2002). Comparison of bacterial communities among the six samples was analyzed by DGGE of PCR-amplified 16S rDNA with universal bacterial primer sets. The profiles demonstrated that samples from the Flower Lake had more DNA bands than the Conservatory Station inferring higher diversity. In addition, the samples from the same environment shared similar compositions of bacterial communities. Bacterial community composition and predominant bacteria were analyzed by 16S rDNA clone library. The dominant group was Proteobacteria (51.6% of the total clones, which contained 24.2% alpha proteobacteria, 14.5% beta proteobacteria and 12.9% gamma proteobacteria). And the Bacteroidetes added to 17.7%, Verrucomicrobia to 4.8%. More than 24.2% of the total clones showed high similarity to uncultured bacteria. The above work provides some information on bacterial diversity for special site of spatial isolation.     

抗菌肽CM4基因克隆及其在毕赤酵母中的表达鉴定

为了在毕赤酵母中获得抗菌肽CM4表达,将抗菌肽CM4基因克隆入表达质粒pPIC9,SacⅠ线性化的重组表达质粒pPIC9-CM4电击转化P.pastorisGS115(his-),采用MM、MD板和PCR法筛选Mut 表型,甲醇诱导表达;抗菌活性检测、Tricine-SDS-PAGE及酸性活性电泳均表明抗菌肽CM4在毕赤酵母中成功地分泌表达;重组抗菌肽CM4对黑曲霉(Aspergillus niger)、绿色木霉(Trichoderma viride)都有很强的抑菌活性。     

Whole-genome sequences of four Mycobacterium bovis BCG vaccine strains

Mycobacterium bovis Bacille Calmette-Guérin (BCG) is the only vaccine available against tuberculosis (TB). A number of BCG strains are in use, and they exhibit biochemical and genetic differences. We report the genome sequences of four BCG strains representing different lineages, which will help to design more effective TB vaccines.     

Patterns and processes in the genetic differentiation of the Brachionus calyciflorus complex, a passively dispersing freshwater zooplankton

Elucidating the evolutionary patterns and processes of extant species is an important objective of any research program that seeks to understand population divergence and, ultimately, speciation. The island-like nature and temporal fluctuation of limnetic habitats create opportunities for genetic differentiation in rotifers through space and time. To gain further understanding of spatio-temporal patterns of genetic differentiation in rotifers other than the well-studied Brachionus plicatilis complex in brackish water, a total of 318 nrDNA ITS sequences from the B. calyciflorus complex in freshwater were analysed using phylogenetic and phylogeographic methods. DNA taxonomy conducted by both the sequence divergence and the GMYC model suggested the occurrence of six potential cryptic species, supported also by reproductive isolation among the tested lineages. The significant genetic differentiation and non-significant correlation between geographic and genetic distances existed in the most abundant cryptic species, BcI-W and Bc-SW. The large proportion of genetic variability for cryptic species Bc-SW was due to differences between sampling localities within seasons, rather than between different seasons. Nested Clade Analysis suggested allopatric or past fragmentation, contiguous range expansion and long-distance colonization possibly coupled with subsequent fragmentation as the probable main forces shaping the present-day phylogeographic structure of the B. calyciflorus species complex.     

The role of muscarinic receptors in the beneficial effects of adenosine against myocardial reperfusion injury in rats

Adenosine, a catabolite of ATP, displays a wide variety of effects in the heart including regulation of cardiac response to myocardial ischemia and reperfusion injury. Nonetheless, the precise mechanism of adenosine-induced cardioprotection is still elusive. Isolated Sprague-Dawley rat hearts underwent 30 min global ischemia and 120 min reperfusion using a Langendorff apparatus. Both adenosine and acetylcholine treatment recovered the post-reperfusion cardiac function associated with adenosine and muscarinic receptors activation. Simultaneous administration of adenosine and acetylcholine failed to exert any additive protective effect, suggesting a shared mechanism between the two. Our data further revealed a cross-talk between the adenosine and acetylcholine receptor signaling in reperfused rat hearts. Interestingly, the selective M(2) muscarinic acetylcholine receptor antagonist methoctramine significantly attenuated the cardioprotective effect of adenosine. In addition, treatment with adenosine upregulated the expression and the maximal binding capacity of muscarinic acetylcholine receptor, which were inhibited by the selective A(1) adenosine receptor antagonist 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX) and the nitric oxide synthase inhibitor N(ω)-nitro-L-arginine methyl ester (L-NAME). These data suggested a possible functional coupling between the adenosine and muscarinic receptors behind the observed cardioprotection. Furthermore, nitric oxide was found involved in triggering the response to each of the two receptor agonist. In summary, there may be a cross-talk between the adenosine and muscarinic receptors in ischemic/reperfused myocardium with nitric oxide synthase might serve as the distal converging point. In addition, adenosine contributes to the invigorating effect of adenosine on muscarinic receptor thereby prompting to regulation of cardiac function. These findings argue for a potentially novel mechanism behind the adenosine-mediated cardioprotection.     

A poised chromatin platform for TGF-β access to master regulators

Specific chromatin marks keep master regulators of differentiation silent yet poised for activation by extracellular signals. We report that nodal TGF-β signals use the poised histone mark H3K9me3 to trigger differentiation of mammalian embryonic stem cells. Nodal receptors induce the formation of companion Smad4-Smad2/3 and TRIM33-Smad2/3 complexes. The PHD-Bromo cassette of TRIM33 facilitates binding of TRIM33-Smad2/3 to H3K9me3 and H3K18ac on the promoters of mesendoderm regulators Gsc and Mixl1. The crystal structure of this cassette, bound to histone H3 peptides, illustrates that PHD recognizes K9me3, and Bromo binds an adjacent K18ac. The interaction between TRIM33-Smad2/3 and H3K9me3 displaces the chromatin-compacting factor HP1γ, making nodal response elements accessible to Smad4-Smad2/3 for Pol II recruitment. In turn, Smad4 increases K18 acetylation to augment TRIM33-Smad2/3 binding. Thus, nodal effectors use the H3K9me3 mark as a platform to switch master regulators of stem cell differentiation from the poised to the active state.