A diatom-based reconstruction of Early Holocene hydrographic and climatic change in a southwest Greenland fjord

A diatom-based reconstruction of surface-water paleoclimatic and paleoceanographic changes in Ameralik Fjord, southwest Greenland, is presented for the Holocene interval 8800 to 3600 cal yrs B.P. A minor episode of cold surface-water conditions is found at ca. 8000–7800 cal yrs B.P. This may be due to the local conditions in the fjord and linked to the culmination of a strong melt-water outflow rather than reflecting the widespread North Atlantic (8.2 ka) cooling event. Warming of surface-water condition from 7800 to 7100 cal yrs B.P., probably corresponding to the early and warmest part of the Holocene Thermal Maximum (HTM) in this region, is reflected in the diatom assemblages and supported by other proxies. The West Greenland Current (WGC) influences the fjord strongly during this interval, indicating enhanced advection of Atlantic water-masses derived from the Irminger Current (IC). A major sedimentary change with a hiatus between 6800 and 4400 cal yrs B.P. prevents a reconstruction of mid-Holocene paleoceanograpy. The final and less prominent part of the HTM is found after 4400 cal yrs B.P. Previous studies from the same site have shown this final stage of the HTM to end at 3200 cal yrs B.P. with the onset of the ‘Neoglaciation’. Our study provides further evidence that the marine sedimentary record from West Greenland fjords yields paleoenvironmental information reflecting a significant link between local and large scale North Atlantic oceanographic and climatic changes.     

Molecular cloning and sequence analysis of stearoyl-CoA desaturase in milkfish, Chanos chanos

Stearoyl-CoA desaturase (EC 1.14.99.5) is a key enzyme in the biosynthesis of polyunsaturated fatty acids and the maintenance of the homeoviscous fluidity of biological membranes. The stearoyl-CoA desaturase cDNA in milkfish (Chanos chanos) was cloned by RT-PCR and RACE, and it was compared with the stearoyl-CoA desaturase in cold-tolerant teleosts, common carp and grass carp. Nucleotide sequence analysis revealed that the cDNA clone has a 972-bp open reading frame encoding 323 amino acid residues. Alignments of the deduced amino acid sequence showed that the milkfish stearoyl-CoA desaturase shares 79% and 75% identity with common carp and grass carp, and 63%–64% with other vertebrates such as sheep, hamsters, rats, mice, and humans. Like common carp and grass carp, the deduced amino acid sequence in milkfish well conserves three histidine cluster motifs (one HXXXXH and two HXXHH) that are essential for catalysis of stearoyl-CoA desaturase activity. However, RT-PCR analysis showed that stearoyl-CoA desaturase expression in milkfish is detected in the tissues of liver, muscle, kidney, brain, and gill, and more expression sites were found in milkfish than in common carp and grass carp. Phylogenic relationships among the deduced stearoyl-CoA desaturase amino acid sequence in milkfish and those in other vertebrates showed that the milkfish stearoyl-CoA desaturase amino acid sequence is phylogenetically closer to those of common carp and grass carp than to other higher vertebrates.     

Simple Sequence Repeat Analysis of Genetic Diversity in Primary Core Collection of Peach （Prunus persica）

In this study, the genetic diversity of 51 cultivars in the primary core collection of peach （Prunus persica （L.） Batsch） was evaluated by using simple sequence repeats （SSRs）. The phylogenetic relationships and the evolutionary history among different cultivars were determined on the basis of SSR data. Twenty-two polymorphic SSR primer pairs were selected, and a total of 111 alleles were identified in the 51 cultivars, with an average of 5 alleles per locus. According to traditional Chinese classification of peach cultivars, the 51 cultivars in the peach primary core collection belong to six variety groups. The SSR analysis revealed that the levels of the genetic diversity within each variety group were ranked as Sweet peach 〉 Crisp peach 〉 Flat peach 〉 Nectarine 〉 Honey Peach 〉 Yellow fleshed peach. The genetic diversity among the Chinese cultivars was higher than that among the introduced cultivars. Cluster analysis by the unweighted pair group method with arithmetic averaging （UPGMA） placed the 51 cultivars into five linkage clusters. Cultivar members from the same variety group were distributed in different UPGMA clusters and some members from different variety groups were placed under the same cluster. Different variety groups could not be differentiated in accordance with SSR markers. The SSR analysis revealed rich genetic diversity in the peach primary core collection, representative of genetic resources of peach.     

The responses of microbial temperature relationships to seasonal change and winter warming in a temperate grassland

Microorganisms dominate the decomposition of organic matter and their activities are strongly influenced by temperature. As the carbon (C) flux from soil to the atmosphere due to microbial activity is substantial, understanding temperature relationships of microbial processes is critical. It has been shown that microbial temperature relationships in soil correlate with the climate, and microorganisms in field experiments become more warm‐tolerant in response to chronic warming. It is also known that microbial temperature relationships reflect the seasons in aquatic ecosystems, but to date this has not been investigated in soil. Although climate change predictions suggest that temperatures will be mostly affected during winter in temperate ecosystems, no assessments exist of the responses of microbial temperature relationships to winter warming. We investigated the responses of the temperature relationships of bacterial growth, fungal growth, and respiration in a temperate grassland to seasonal change, and to 2 years’ winter warming. The warming treatments increased winter soil temperatures by 5–6°C, corresponding to 3°C warming of the mean annual temperature. Microbial temperature relationships and temperature sensitivities (Q₁₀) could be accurately established, but did not respond to winter warming or to seasonal temperature change, despite significant shifts in the microbial community structure. The lack of response to winter warming that we demonstrate, and the strong response to chronic warming treatments previously shown, together suggest that it is the peak annual soil temperature that influences the microbial temperature relationships, and that temperatures during colder seasons will have little impact. Thus, mean annual temperatures are poor predictors for microbial temperature relationships. Instead, the intensity of summer heat‐spells in temperate systems is likely to shape the microbial temperature relationships that govern the soil‐atmosphere C exchange.     

Production rate estimation of mycosporine‐like amino acids in two Arctic melt ponds by stable isotope probing with NAH13CO3

The net carbon uptake rate and net production rate of mycosporine‐like amino acids (MAAs) were measured in phytoplankton from 2 different melt ponds (MPs; closed and open type pond) in the western Arctic Ocean using a ¹³C stable isotope tracer technique. The Research Vessel Araon visited ice‐covered western‐central basins situated at 82°N and 173°E in the summer of 2012, when Arctic sea ice declined to a record minimum. The average net carbon uptake rate of the phytoplankton in polycarbonate (PC) bottles in the closed MP was 3.24 mg C · m^?3 · h^?1 (SD = ±1.12 mg C · m^?3 · h^?1), while that in the open MP was 1.3 mg C · m^?3 · h^?1 (SD = ±0.05 mg C · m^?3 · h^?1). The net production rate of total MAAs in incubated PC bottles was highest (1.44 (SD = ±0.24) ng C · L^?1 · h^?1) in the open MP and lowest (0.05 (SD = ±0.003) ng C · L^?1 · h^?1) in the closed MP. The net production rate of shinorine and palythine in incubated PC bottles at the open MP presented significantly high values 0.76 (SD = ±0.12) ng C · L^?1 · h^?1and 0.53 (SD = ±0.06) ng C · L^?1 · h^?1. Our results showed that high net production rate of MAAs in the open MP was enhanced by a combination of osmotic and UVR stress and that in situ net production rates of individual MAA can be determined using ¹³C tracer in MPs in Arctic sea ice.     

基于核密度估算的路网格局与景观破碎化分析

道路网络的发展是导致区域景观破碎化程度加剧的重要因素,如何定量表征道路网络特征及其破碎化效应是道路生态学的一个关键科学问题。本研究以珠江三角洲核心区为案例,采用核密度估算(KDE)结合道路密度指数方法,探讨了区域路网格局及其对景观破碎化的影响。结果表明:KDE法能有效识别和提取高密度路网热点区域;道路密度指数分析显示,道路密度与景观破碎化之间存在较强的相关性;道路密度与KDE法结合能突破传统基于行政边界计算道路密度的局限,为研究路网特征及其景观破碎化程度提供了一个很好的量化工具。     

Robust estimation of local genetic ancestry in admixed populations using a nonparametric bayesian approach

We present a new haplotype-based approach for inferring local genetic ancestry of individuals in an admixed population. Most existing approaches for local ancestry estimation ignore the latent genetic relatedness between ancestral populations and treat them as independent. In this article, we exploit such information by building an inheritance model that describes both the ancestral populations and the admixed population jointly in a unified framework. Based on an assumption that the common hypothetical founder haplotypes give rise to both the ancestral and the admixed population haplotypes, we employ an infinite hidden Markov model to characterize each ancestral population and further extend it to generate the admixed population. Through an effective utilization of the population structural information under a principled nonparametric Bayesian framework, the resulting model is significantly less sensitive to the choice and the amount of training data for ancestral populations than state-of-the-art algorithms. We also improve the robustness under deviation from common modeling assumptions by incorporating population-specific scale parameters that allow variable recombination rates in different populations. Our method is applicable to an admixed population from an arbitrary number of ancestral populations and also performs competitively in terms of spurious ancestry proportions under a general multiway admixture assumption. We validate the proposed method by simulation under various admixing scenarios and present empirical analysis results from a worldwide-distributed dataset from the Human Genome Diversity Project.     

Phylogenetic estimation of Sciaenidae in the East China Sea inferred from nuclear EPIC DNA sequence variation

Here we describe a phylogenetic analysis of sciaenids of the East China Sea based on nuclear exon-primed intron-crossing genes (EPIC markers) and a mitochondrial gene (CO1). Separate analyses of the two data partitions resulted in mostly congruent trees. Although there were some differences in the classification of these species, the main difference between trees obtained by the mitochondrial gene (CO1) and nuclear DNA sequences was the position of Miichthys miiuy and Johnius belangerii. In the mitochondrial phylogeny, Johnius belangerii was placed at the most basal position forming an individual clade, while other species formed another large cluster. Miichthys miiuy formed an independent basal sub-clade grouped with Larimichthys and Collichthys. Collichthys lucidus was grouped with Larimichthys crocea and Larimichthys polyactis. Trees based on the nuclear genes differed somewhat from those based on the CO1 mitochondrial gene. In this analysis, two groups resulted, the Larimichthys and Collichthys clade, and another clade including a total of five species: Johnius belangerii, Nibea albiflora, Pennahia argentata, Sciaenops ocellatus, and Argyrosomus japonicus; Johnius belangerii clustered with Nibea albiflora. Miichthys miiuy was placed at the basal position of the other cluster because it was an independent basal sub-clade grouped with Johnius belangerii, Nibea albiflora, Pennahia argentata, Sciaenops ocellatus, and Argyrosomus japonicus. Many aspects of the phylogeny of the Sciaenidae remain unresolved, and further analysis based on more molecular information and extensive taxon sampling is necessary to elucidate the phylogenetic relationships among the major lineages within Sciaenidae.     

Distribution of 222Rn in groundwater and estimation of resulting radiation dose to different age groups: A case study from Bangalore City

Ingesting waters holding high levels of natural occurring radioactive element like Radon would contribute to increase in the effective dose received by people followed by an increased prevalence of cancer. The current study is an attempt to describe the extent of contribution of ²²²Rn to natural background radiation and the resultant effective dose to public of different age groups. In order to do so, 65 groundwater samples from selected parts of Bangalore city were collected and analyzed for radon activity using RAD7 radon monitor coupled with RAD H₂O accessories. The radon activity was in the range of 3.05–696 Bq/L (mean: 91.39 Bq/L) and 92.31% of the groundwater samples recorded elevated radon concentration above the United States environmental protection agency (USEPA's) Maximum Contaminant Level (MCL) value of 300 pCi/L, corresponding to 11.1 Bq/L. The mean annual effective dose contribution of people falling under different age groups (viz., infants, children, teens: males and females, adults: males and females, pregnant and lactating women) due to ingestion of water-borne ²²²Rn ranged from 0.082 to 0.444 mSv/y and was found to be higher in all the age groups of males compared to respective female age groups, but well within the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and World Health Organization (WHO) proposed limit of 1 mSv/y.     

Identification of anthracene degraders in leachate-contaminated aquifer using stable isotope probing

Polycyclic aromatic hydrocarbons (PAHs) are common contaminants in landfill leachate-contaminated aquifer. It is necessary to identify the microorganisms truly responsible for PAH degradation if bioremediation can be applied as an effective technology. DNA-based stable isotope probing (SIP) in combination with terminal restriction fragment length polymorphism (TRFLP) was used to identify the active anthracene degraders in the contaminated aquifer sediment. One kind of degrader was classified as Variovorax species within class ??-proteobacteria, but another belonged to unclassified bacteria. These findings also suggest novel microorganisms involved in PAH-degrading processes.     

Changes in the sequence content of albumin mRNA and in its translational activity in the rat liver with age

To investigate the regulation of age-related changes in albumin synthesis in the rat liver, total postnuclear RNA and polyribosomes, both membrane-bound and free, were prepared from livers of rats of different ages. By the use of a specific complementary DNA probe, the albumin mRNA sequence content was quantitated in these RNA fractions. These studies showed a specific increase in albumin mRNA sequence content in total postnuclear RNA and membrane-bound polyribosomes at between 12 and 24 months of age. Between 24 and 36 months of age, the increase in the amount of albumin mRNA in these two fractions was due only to an increase in liver weight. The increase in albumin mRNA sequence content was not found in the poly(A)⁺ fraction but in the RNA extracted from the void of oligo(dT)-cellulose column chromatography. The isolated polyribosomes were translated in a cell-free system to assess age-related changes in total protein and albumin synthesis due to translational control. No changes with age were found in the translational capacity of membrane-bound and free polyribosomes per RNA unit. Immunoprecipitation of the synthesized albumin in the translation products revealed that albumin synthesis in the cell-free system is not increased proportionally with the elevated albumin mRNA level between 12 and 24 months of age. This indicates that albumin mRNAs present in the livers of old rats are biologically less active than those found in younger animals.     

施用生物炭与硝化抑制剂对菜地综合温室效应的影响

采用静态暗箱-气相色谱法,研究施用生物炭与添加硝化抑制剂对菜地周年综合温室效应的影响.结果表明: 与不施用生物炭相比,施用生物炭处理N₂O和CH₄的综合温室效应增加8.7%~12.4%,蔬菜产量增加16.1%~52.5%,温室气体强度降低5.4%~28.7%.添加硝化抑制剂显著减少N₂O排放,不影响CH₄排放,综合温室效应减少17.5%~20.6%,蔬菜产量增加21.2%~40.1%,温室气体强度显著降低.混合施用生物炭与硝化抑制剂一方面增加蔬菜产量,另一方面显著增加综合温室效应(增幅为10.6%～11.2%).因此,在菜地添加硝化抑制剂,既能保证蔬菜产量又能减少温室气体排放,是合适的减排措施.     

短期增温对紫花针茅草原土壤微生物群落的影响

土壤微生物是生态系统碳循环的重要参与者和调控者。全球变暖可能对土壤微生物群落产生影响, 加速陆地生态系统向大气中释放碳, 进而引起陆地碳循环对气候变暖的正反馈。然而, 目前学术界对土壤微生物群落如何响应气候变暖等问题认识不足, 尤其是缺乏低温干旱条件下土壤微生物对增温响应的实验证据。为此, 该文依托青藏高原紫花针茅(Stipa purpurea)草原建立的增温实验平台, 基于磷脂脂肪酸(PLFA)方法测定了2015和2016年生长季表层(0-10 cm)土壤微生物各类群的生物量, 在此基础上揭示气候变暖对紫花针茅草原土壤微生物群落结构的影响。结果显示, 短期增温处理导致2015和2016年生长季(5-10月)的表层土壤温度均显著提高1.6 ℃, 同时也导致土壤含水量显著下降了3.4%和2.4% (体积分数), 但并没有显著改变土壤化学性质及归一化植被指数。增温处理下, 两年生长季旺期(8月)的微生物生物量碳(MBC)含量分别为749.0和844.3 mg·kg ^-1, 微生物生物量氮(MBN)含量为43.1和102.1 mg·kg ^-1, 微生物生物量碳氮比分别为17.9和8.4, 但实验期间MBC、MBN和微生物生物量碳氮比与对照没有差异。PLFA分析的结果显示细菌在微生物群落中占主导, 而丛枝菌根真菌含量最少, 增温处理并没有改变不同类群的微生物生物量以及群落结构。进一步的分析显示, 土壤温度和含水量是调控土壤微生物群落变异的主要因子, 并且增温导致的微生物生物量碳的变化量分别与土壤温度和含水量的变化量呈显著正相关关系。以上结果表明, 由于受水分的限制, 短期增温对紫花针茅草原土壤微生物群落没有显著影响。     

Mathematical modelling of the aerobic degradation of two-phase olive mill effluents in a batch reactor

A laboratory-scale study was conducted on the aerobic degradation of two-phase olive mill effluents (TPOME) made up of the mixture of the washwaters derived from the initial cleansing of the olives and those obtained in the washing and purification of virgin olive oil. The process was carried out in a 1-l working volume stirred tank reactor operating in batch mode at room temperature (25 °C). The reactor was operated at influent substrate concentrations of 2.80 g COD/l (TPOME 25%), 5.45 g COD/l (TPOME 50%), 8.18 g COD/l (TPOME 75%) and 10.90 g COD/l (TPOME 100%). After five days of operation time, total and soluble COD removal efficiencies of 64.3% and 66.6% were achieved respectively for the most concentrated influent used (TPOME 100%). A simplified kinetic model for studying the hydrolysis of insoluble organic matter, oxidation of soluble substrate and biomass production was proposed on the basis of the experimental results obtained. The following kinetic constants with their standard deviations were obtained for the above stages in the case of the most concentrated influent used (TPOME 100%): k₁ (kinetic constant for hydrolysis of suspended organic matter): 0.11 ± 0.01 l/(g VSS day); k₂ (kinetic constant for total consumption of soluble substrate): 0.30 ± 0.02 l/(g VSS day); k₃ (endogenous metabolism constant): 0.07 ± 0.01 per day). Finally, the biomass yield coefficient was found to be 0.30 g VSS/g COD_removed. The values of non-biodegradable total and soluble CODs obtained from the model were found to be 3 and 2 g/l, respectively. The kinetic constants obtained and the proposed equations were used to simulate the aerobic degradation process of TPOME and to obtain the theoretical values of non-soluble and soluble CODs and biomass concentration. The small deviations obtained (equal or lower than 10%) between the theoretical and experimental values suggest that the parameters obtained represent and predict the activity of the microorganisms involved in the overall aerobic degradation process of this wastewater.     

4龄中华鲟垂体的EST分析

表达序列标签 (Expressed sequence tag, EST) 是鉴定基因表达规律和发现新基因的一种有效的分子生物学手段。为了能在中华鲟(Acipenser sinensis Gray) 中发现与生长和生殖内分泌调控相关的基因,我们构建了中华鲟垂体的SMART cDNA质粒文库。垂体是调节生长和生殖内分泌的重要器官。在本研究中,通过测序筛选得到了944个EST克隆,将所得EST 与 GenBank 数据库中的序列进行比对, 结果表明,802 (84.96%) 个克隆可以找到同源序列,共代表461个基因, 其中含132个已知功能基因;而 142 (15.04%) 个克隆不能找到同源序列。研究发现,在所有基因中,阿黑皮素原基因 (Proopiomelanocortin, POMC) 是出现次数最高的基因,占总EST数的10.17%, 显示出其在垂体中的重要地位。我们还发现了7个未知功能的基因并重点研究了其在心脏、肝脏、脾脏、肾脏、肌肉、精巢、卵巢和垂体等组织中的表达特异性。结果发现,4个基因：EG009334、EG009337、EG009338 和 EG009340为垂体特异性表达或垂体和卵巢特异性表达。对这些基因进一步的功能研究将有利于我们更好地了解中华鲟生长和生殖内分泌调控的分子机制。     

Partial amino-acid sequence of ECP31, a carrot embryogenic-cell protein,and enhancement of its accumulation by abscisic acid in somatic embryos

ECP31, an embryogenic-cell protein from carrot (Daucus carota L.), was purified by sequential column-chromatographic steps and digested by V8 protease on a nitrocellulose membrane. The resultant peptides were separated by reverse-phased column chromatography and sequenced. The sequences obtained were 70–80% homologous to those of a late-embryogenesis-abundant protein (D34) from cotton (Baker et al, 1988, Plant Mol. Biol. 11, 227–291). The level of ECP31 in somatic embryos of carrot was increased by treatment of the embryos with 3.7 · 10^–6 M abscisic acid (ABA) for 48 h, and there was no change in this enhanced level for up to 192 h in the presence of ABA. No similar enhancing effect of ABA was observed on the level of ECP31 in embryogenic callus or segments of carrot hypocotyls. In an immunohistochemical analysis, ECP31 was found in epidermal tissue and in the vascular system of ABA-treated somatic embryos.Abbreviations ABA abscisic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - LEA protein late-embryogenesis-abundant protein To whom correspondence should be addressedThis work was supported in part by a grant-in-aid for Special Research in Priority Areas (Project No. 02242102) from the Ministry of Education, Science and Culture, Japan, and by Special Coordination Funds of the Science and Technology Agency of the Japanese Government.     

局部环境增温对根田鼠冬季种群的影响

通过建立开顶式增温小室模拟全球变暖的实验, 对海北高寒草甸地区实验增温样地及其对照样地内根田鼠的冬季种群进行调查, 旨在研究局部增温对根田鼠冬季种群的可能影响。结果表明, 在冬季, 实验增温草甸样地和灌丛样地内根田鼠的种群密度均显著高于其对照( P < 0.05) ; 实验增温灌丛样地与对照间性比的差异不显著( P > 0.05) ; 增温样地和对照之间、不同植被类型的增温样地之间、对照样地之间, 根田鼠留存率、平均体重及年龄结构的差异均不显著( P > 0.05) ; 有从对照样地向增温样地单方向迁移的记录。总之, 局部环境增温导致实验样地内根田鼠的冬季种群密度明显上升, 而其性比、存活率、种群平均体重以及年龄结构无明显变化; 在冬季, 根田鼠有从对照样地向增温样地扩散或迁移的趋势。     

儿童感染青霉素耐药肺炎链球菌的多位点序列分型

目的 对儿童感染的青霉素耐药肺炎链球菌进行多位点序列分型,了解厦门地区肺炎链球菌青霉素耐药菌株遗传背景。方法 采用多位点序列分型法对2012年1月至2014年12月期间分离的60株青霉素耐药肺炎链球菌进行分子分型。结果 60株青霉素耐药肺炎链球菌MLST法共检出24个ST型,其中发现6个新的ST型,分别被命名为ST10004、ST10005、ST10006、ST10007、ST10008和ST10009。存在一个优势型别ST271,占31.7%（19/60）,发现了4个克隆群和20种单一克隆,其中主要克隆群为国际流行耐药克隆群Taiwan19F-14,占41.7%（25/60）。结论 本地区分离的儿童青霉素耐药肺炎链球菌主要以ST271型为主,属国际流行耐药克隆群Taiwan19F-14,是引起儿童呼吸道感染肺炎链球菌多重耐药的主要原因。