孢粉、炭屑揭示的黔西高原MIS3b期间古植被、古气候演变

将孢粉与炭屑结合应用于贵州盘县坪地晚更新世剖面,对比高分辨率的NGRIPδ18O、石笋记录分析,用以揭示黔西高原MIS3b期古植被、古气候演变。结果显示:45.16—44.44 ka BP期间,孢粉缺失,炭屑少,说明此时植被稀少,气候寒冷,可能指示H5事件。44.44—44.04 ka BP期间,以禾本科、百合科为主的草本及喜冷湿的蕨类占优势,乔、灌木稀少。炭屑浓度低,但末期出现峰值,说明气候开始由冷湿向温干过渡。44.04—42.5 ka BP期间,禾本科草类继续增加,成为草原植物的主要成分;乔木种类增加,但含量不高。炭屑浓度高,峰值频繁出现,指示气侯温干。42.5—41.29 ka BP期间,草原萎缩,森林面积扩展。针叶、常绿及落叶阔叶林迅速扩展。炭屑浓度总体偏低稳定,指示该时期气候温凉湿润。总之,MIS3b整体较冷,干湿交替出现。     

全新世以来长白山区孤山屯泥炭地炭屑记录与古火演化历史

长白山拥有亚洲目前保存较为完好的温带山地森林生态系统,由于近年来无火事件发生而积累了大量可燃物,火灾隐患逐年增加,重建古火历史找出火事件发生规律有助于现代火灾的有效防控。本文以长白山区孤山屯泥炭剖面的68个样品为研究载体,选取炭屑作为主要指标反演了长白山全新世以来的火事件演化历史;并结合前人利用孢粉、植硅体等代用指标重建的古环境、古气候特征,分析了火事件的成因机制。在11 686-10 883 cal aBP、7 336-2 624 cal aBP、2 624-1 189 cal aBP,炭屑浓度较高,古火事件发生频繁,强度较大;在10 883-7 336 cal aBP、1 189 cal aBP至今,炭屑浓度较低,古火事件发生频率较小,强度相对较弱。气候和植被对于火事件的影响贯穿了整个全新世时期,火事件多发生在寒冷干燥气候时期且以区域性火事件为主;近千年以来,人类活动与火山喷发对火事件的影响显著,局域性火事件比例逐渐增多。     

RhoGDI2与PI3K/Akt/mTOR信号通路在肺癌细胞中的相关性研究

目的探讨肿瘤转移相关因子RhoGDI2与PI3K/Akt/mTOR信号通路在肺癌侵袭转移过程中的作用及相关机制。方法利用PI3K/Akt/mTOR信号通路上特异性的抑制剂,采用MTT法,伤口愈合实验及侵袭实验观察不同浓度药物对肺癌95D细胞生长侵袭转移能力的影响,通过Western Blot方法观察RhoGDI2蛋白水平的变化。结果PI3K抑制剂LY294002及mTOR抑制剂Rapamycin都能抑制肺癌细胞95D的侵袭转移能力,联合应用抑制作用更强。PI3K抑制剂LY294002处理组RhoGDI2蛋白的表达量增加,且随浓度增加RhoGDI2蛋白表达也增加。mTOR抑制剂Rapamycin组,在低浓度时增加RhoGDI2蛋白的表达,但增大Rapamycin的浓度,RhoGDI2蛋白的表达反而降低。低浓度LY294002组和Rapa-mycin组联合应用可以明显增加RhoGDI2蛋白的表达。结论PI3K/Akt/mTOR信号通路中Akt的活化与RhoGDI2密切相关,RhoGDI2可能直接或间接通过与Akt的相互作用参与调节肺癌的侵袭转移的过程。     

MHR、UACR、25（OH）D3与2型糖尿病患者下肢动脉病变的关系研究

摘要 目的：探讨单核细胞/高密度脂蛋白胆固醇（HDL-C）比值（MHR）、尿白蛋白/尿肌酐比值（UACR）、25-羟维生素D3[25（OH）D3]与2型糖尿病（T2DM）患者下肢动脉病变（LEAD）的关系。方法：选择2017年1月至2021年6月延边大学附属医院西区医院收治的195例T2DM患者,根据LEAD检查结果将患者分为LEAD组（104例）和非LEAD组（91例）。检测单核细胞、HDL-C、尿白蛋白、尿肌酐、25（OH）D3水平,计算MHR、UACR。比较两组MHR、UACR、25（OH）D3差异,单因素及多因素Logistic回归分析影响T2DM患者发生LEAD的危险因素,受试者工作特征（ROC）曲线分析MHR、UACR、25（OH）D3预测T2DM患者发生LEAD的价值。结果：LEAD组年龄、体质量指数大于非LEAD组,吸烟史、高血压比例高于非LEAD组,T2DM病程长于非LEAD组,总胆固醇（TC）、低密度脂蛋白胆固醇（LDL-C）、空腹血糖（FPG）高于非LEAD组,高密度脂蛋白胆固醇（HDL-C）低于非LEAD组（均P＜0.05）。LEAD组MHR、UACR高于非LEAD组,25（OH）D3水平低于非LEAD组（P＜0.05）。多因素Logistic回归分析显示,年龄过大、T2DM病程过长、高MHR、高UACR是T2DM患者发生LEAD的危险因素（P＜0.05）,高25（OH）D3是其保护因素（P＜0.05）。MHR、UACR、25（OH）D3预测T2DM患者发生LEAD的曲线下面积分别为0.728、0.755、0.759,联合三项指标后预测T2DM患者发生LEAD的曲线下面积为0.888,高于单独指标预测。结论：MHR、UACR增高和25（OH）D3水平降低与T2DM患者发生LEAD有关,联合三项指标在预测T2DM患者并发LEAD方面具有较高的价值。     

草地贪夜蛾Sf9细胞系Arp2/3-p40/ARPC1亚基基因的克隆与功能研究

杆状病毒感染诱导的昆虫宿主细胞肌动蛋白聚合主要由病毒编码的Wiskott Aldrich综合征蛋白(Wiskott Aldrichsyndrome Protein,WASP)同源蛋白P78/83激活宿主细胞内的Arp2/3复合物,进而引起肌动蛋白单体(G-actin)聚合成为纤维状肌动蛋白(F-actin)。为了研究Arp2/3复合物在病毒感染过程中所发挥的作用,我们克隆了昆虫Sf9细胞的Arp2/3复合体P40亚基基因,并对其预期产物进行了生物信息学与功能分析。我们发现在病毒感染过程中,P40亚基由细胞质转移到核膜的内缘,与本实验室过去报道的病毒感染后期核内F-actin的分布相吻合,提示P40可以很好地用于研究Arp2/3复合体的亚细胞定位情况;通过免疫共沉淀(Co-IP)实验,还证实病毒感染可以促进P40和P78/83的相互作用,提示某些未知病毒因素参与调控了由P78/83和Arp2/3复合体介导的肌动蛋白聚合过程。     

A modern pollen–climate calibration set based on lake sediments from the Tibetan Plateau and its application to a Late Quaternary pollen record from the Qilian Mountains

Aim Fossil pollen spectra from lake sediments on the Tibetan Plateau have been used for qualitative climate reconstruction, but no modern pollen–climate calibration set based on lake sediments is available to infer past climate quantitatively. This study aims to develop such a dataset and apply it to fossil data. Location The Tibetan Plateau, between 30 and 40° N and 87 and 103° E. Methods We collected surface sediments from 112 lakes and analysed them palynologically. The lakes span a wide range of mean annual precipitation (P_ann; 31–1022 mm), mean annual temperature (T_ann; −6.5 to 1 °C), and mean July temperature (T_July; 2.6–19.7 °C). Redundancy analysis showed that the modern pollen spectra are characteristic of their respective vegetation types and local climate. Transfer functions for P_ann, T_ann and T_July were developed with weighted averaging partial least squares. Model performance was assessed by leave-one-out cross-validation. Results The root mean square errors of prediction (RMSEP) were 104 mm (P_ann), 1.18 °C (T_ann) and 1.17 °C (T_July). The RMSEPs, when expressed as percentages of the gradient sampled, were 10.6% (P_ann), 15.7% (T_ann) and 11.9% (T_July). These low values indicate the good performance of our models. An application of the models to fossil pollen spectra covering the last c. 50 kyr yielded realistic results for Luanhaizi Lake in the Qilian Mountains on the north-eastern Tibetan Plateau (modern P_ann 480 mm; T_ann−1 °C). T_ann and P_ann values similar to present ones were reconstructed for late Marine Isotope Stage 3, with minimum values for the Last Glacial Maximum (c. 300 mm and 2 °C below present), and maximum values for the early Holocene (c. 70 mm and 0.5 °C greater than present). Main conclusions The modern pollen–climate calibration set will potentially be useful for quantitative climate reconstructions from lake-sediment pollen spectra from the Tibetan Plateau, an area of considerable climatic and biogeographical importance.     

Two proxy records revealing the late Holocene fire history at a site on the central coast of New South Wales,Australia

Abstract: The local fire history of a coastal swamp catchment in New South Wales was reconstructed using two proxy records of fire: sedimentary macroscopic charcoal and fire‐scar analyses of Xanthorrhoea johnsonii. The charcoal analysis provided a record of fire activity spanning the last 2800 years, while the Xanthorrhoea record covered the last approx. 300 years. The ability of each method to accurately record fire events was verified by cross referencing against the recent (post 1968) historic fire record. Fire history was then extrapolated beyond the historic record, to reveal an unprecedented level of fire activity in the last 35 years, which coincides with increased human activity in the area. In the prehistoric period charcoal and fire scars are comparatively rare, which is most parsimoniously ascribed to little fire activity, but perhaps represents skilful fire manipulation, as is often attributed to Aboriginal people. The comparatively minor fluctuations in macroscopic charcoal during the prehistoric period were approximately coeval with previous evidence of late Holocene environmental change in south‐eastern Australia, suggesting that fire frequency at the site responded to climatic variability. The longer temporal perspective of this palaeoenvironmental approach provides information for the contemporary management of fire in this conservation reserve.     

Pinus cembra L. (arolla pine), a common tree in the inner French Alps since the early Holocene and above the present tree line: a synthesis based on charcoal data from soils and travertines

Aim In this study, charcoal‐based data for Pinus cembra L. (arolla pine) were gathered from soil and travertine sequences in order to reconstruct its historical biogeography at the landscape level in the inner western Alps during the Holocene. Location The study sites are located between 1700 and 2990 m a.s.l., in the southern (Queyras Massif and Ubaye Valley) and the northern (Maurienne Valley) parts of the inner French Alps. Methods Charcoal fragments were extracted from sediments by water sieving, using meshes of 5, 2, 0.8 and 0.4 mm. The charcoal mass of P. cembra was determined in each charcoal assemblage. Accelerator mass spectrometry and conventional ¹⁴C measurements were used to date the fragments. Results Supported by 40 ¹⁴C datings, the fragments show that, over 2000 m a.s.l., P. cembra accounts for around 40% (mean value) of identified fragments. Data reveal that arolla pine once extended between 260 and 375 m above the present‐day local tree lines. It was established in the southern and the northern French Alps from at least c. 9000 and 6000 cal yr bp , respectively. Main conclusions While present‐day populations of P. cembra are very fragmented in the inner French Alps, charcoal records indicate large past occurrences of this tree since the early Holocene. Human disturbance since the Neolithic seems to be the main reason for the regression of the arolla pine woodlands. On the south‐facing slopes of the study sites, currently deforested, this species extended up to 2800 m a.s.l. In the northern areas, charcoal records of the P. cembra expansion are consistent with the regional pollen archives, but in the southern massifs charcoal records indicate its presence c. 2600 years earlier than other palaeobotanical studies suggest. This discrepancy highlights the necessity to crosscheck data using several different proxies in order to assess the validity of conclusions regarding tree development in space and time.     

Myogenesis defect due to Toca-1 knockdown can be suppressed by expression of N-WASP

Skeletal muscle formation is a multistep process involving proliferation, differentiation, alignment and fusion of myoblasts to form myotubes which fuse with additional myoblast to form myofibers. Toca-1 (Transducer of Cdc42-dependent actin assembly), is an adaptor protein which activates N-WASP in conjunction with Cdc42 to facilitate membrane invagination, endocytosis and actin cytoskeleton remodeling. Expression of Toca-1 in mouse primary myoblasts and C2C12 myoblasts was up-regulated on day 1 of differentiation and subsequently down-regulated during differentiation. Knocking down Toca-1 expression in C2C12 cells (Toca-1^KD cells) resulted in a significant decrease in myotube formation and expression of shRNA-resistant Toca-1 in Toca-1^KD cells rescued the myogenic defect, suggesting that the knockdown was specific and Toca-1 is essential for myotube formation. Toca-1^KD cells exhibited elongated spindle-like morphology, expressed myogenic markers (MyoD and MyHC) and localized N-Cadherin at cell periphery similar to control cells suggesting that Toca-1 is not essential for morphological changes or expression of proteins critical for differentiation. Toca-1^KD cells displayed prominent actin fibers suggesting a defect in actin cytoskeleton turnover necessary for cell–cell fusion. Toca-1^KD cells migrated faster than control cells and had a reduced number of vinculin patches similar to N-WASP^KO MEF cells. Transfection of N-WASP-expressing plasmid into Toca-1^KD cells restored myotube formation of Toca-1^KD cells. Thus, our results suggest that Toca-1^KD cells have defects in formation of myotubes probably due to reduced activity of actin cytoskeleton regulators such as N-WASP. This is the first study to identify and characterize the role of Toca-1 in myogenesis.     

Fire and stone clearance in Iron Age agriculture: new insights inferred from the analysis of terrestrial macroscopic charcoal in clearance cairns in Hamneda,southern Sweden

Areas with ancient clearance cairns have been studied in Hamneda, Småland Uplands, southern Sweden, by archaeological and palaeoecological methods. Based on numerous radiocarbon dates and stratigraphical analyses, the local introduction of stone clearance is dated to the first century A.D. The clearance cairns reflect a system of semi-mobile cultivation that lasted until c. A.D. 900. Pollen and macrofossil analyses provide information on cereal growing and pastures in these clearance cairn areas, while charcoal analyses reveal details on the agrarian expansion dynamics and the use of fire in vegetation clearance. In the expansion phase, Quercus (oak) woodlands were cleared and transformed to open pastures and arable land, partly by the use of fire. A secondary succession of Betula (birch) and Corylus (hazel) was dealt with by fire clearances to keep pastures open and to prepare new arable plots. In the long run, Betula in particular was favoured by the land-use system. The mobility of the cultivation system is discussed together with the causes behind the introduction of stone clearance. A possible causal relationship with the introduction of hay mowing is also discussed.     

New data on the history of the plateau forest of Okomu, southern Nigeria: an insight into how human disturbance has shaped the African rain forest

The classic 1955 and 1956 papers by Eustace Jones describe vegetation pattern, process and history in Okomu Forest, south-western Nigeria. Jones and colleagues were puzzled to find an extensive layer of charcoal and pottery below mature mahogany forests. Based on an extensive review of historical documents and the estimated ages of dying emergent tree species, Jones suggested that the forest in Okomu had regenerated after a human population decline 200–300 years previously. We made radiocarbon measurements on samples from the layer of charcoal and pottery described by Jones. In addition, we obtained δ¹³C measures from a soil profile cutting through the charcoal layer. The charcoal dates to about 700–750 years BP whilst the δ¹³C profile showed no evidence of input of organic matter from C₄ grasses. These results are discussed in the light of other recent archaeological evidence of the impact of humans on the rain forests of Africa during the last 2000–3000 years. It seems that extensive archaeological remains are hidden beneath much of the African rain forest, suggesting that human disturbance has been one of the dominant factors affecting forest structure and composition in recent millennia.     

黔西南薏苡内生真菌多样性及其抗菌活性研究

为进一步了解贵州黔西南薏苡(Coix lacryma-Jobi)可培养内生真菌的多样性组成及其抗菌活性。通过组织块分离法,选取薏苡根、叶和种仁为分离对象,进行内生真菌分离,并通过形态学观察,分子生物学特征对所分离内生真菌进行鉴定。采用平板菌块对峙法对薏苡内生真菌进行抗菌活性筛选。从薏苡根、叶和种仁中共分离纯化获得76株薏苡内生真菌,根据形态和分子生物学特征,它们属于10个目、14个科、26个属和1个不明属以及未知菌;以大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphyloccocus aureus)、枯草芽胞杆菌(Bacillus subtilis)、酿酒酵母(Saccharomyces cerevisiae)为指示菌株,对薏苡内生真菌进行抗菌活性筛选。其中有25株对大肠杆菌具有抗菌活性,占分离菌株的比例为32. 9%;有34株对金黄色葡萄球菌具有抗菌活性,其比例为44. 7%;有24株对枯草芽胞杆菌具有抗菌活性,比例是31. 6%;有23株对酿酒酵母具有抗菌活性,占比例为30. 3%;对4种标准菌株都有抗菌活性的有13株,占总株数的17. 1%。薏苡的不同组织结构中存在丰富的内生真菌资源,部分内生真菌具有抑制其他微生物生长的活性,具有产生天然活性产物成分的潜力,为工业应用奠定了资源基础,具有进一步发掘和研究的价值。     

Transgenic superroots of Lotus corniculatus can be regenerated from superroot-derived leaves following Agrobacterium-mediated transformation

Super-growing roots (superroots; SR), which have been established in the legume species Lotus corniculatus, are a fast-growing root culture that allows continuous root cloning, direct somatic embryogenesis and mass regeneration of plants under entirely growth regulator-free culture conditions. These features are unique for non-hairy root cultures, and they are now stably expressed since the culture was isolated more than 10 years ago (1997). Attempts to achieve direct and stable transformation of SR turned out to be unsuccessful. Making use of the supple regeneration plasticity of SR, we are reporting here an indirect transformation protocol. Leaf explants, derived from plants regenerated from SR, were inoculated with Agrobacterium tumefaciens strain LBA4404 harboring the binary vector pBI121, which contains the neomycin phosphotransferase II (NPTII) and beta-glucuronidase (GUS) genes as selectable and visual markers, respectively. After co-cultivation, the explants were selected on solidified MS medium with 0.5mg/L benzylamino purine (BAP), 100mg/L kanamycin and 250mg/L cefotaxime. Kanamycin-resistant calli were transferred to liquid rooting medium. The newly regenerated, kanamycin-resistant roots were harvested and SR cultures re-established, which exhibited all the characteristics of the original SR. Furthermore, kanamycin-resistant roots cultured onto solidified MS medium supplemented with 0.5mg/L BAP produced plants at the same rate as control SR. Six months after gene transfer, PCR analysis and histochemical locating indicated that the NPTII gene was integrated into the genome and that the GUS gene was regularly expressed in leaves, roots and nodules, respectively. The protocol makes it now possible to produce transformed SR and nodules as well as transgenic plants from transformed SR.     

Fire history influences on the spatial heterogeneity of soil nitrogen transformations in three adjacent stands in a dry tropical forest in Thailand

Spatial patterns of soil nitrogen (N) transformations were examined using geostatistical analysis in three adjacent stands with different fire history (0, 10 and 35 years since the latest fire, respectively) in a dry tropical forest in Thailand. A larger pool of total inorganic N and a faster rate of N mineralization were recorded in the stand with longer fire prevention. At the spatial scale analyzed, the proportion of spatially dependent variance to the total variance of N mineralization and nitrification increased from 0.39 to 0.73, and from 0.40 to 0.77, respectively, with the time since the latest fire. The spatial autocorrelation ranges of N mineralization and nitrification decreased from 9.0 to 3.28 m, and 9.0 to 2.77 m, respectively, with the time since the latest fire. These results suggested that fire history affected not only the level of available soil N, but also the spatial heterogeneity of soil N transformations, presumably due to the difference in plant influences on soil.     

A new contribution to the Holocene vegetation history of the West African Sahel: pollen from Oursi,Burkina Faso and charcoal from three sites in northeast Nigeria

A pollen diagram from Oursi in Burkina Faso is compared with anthracological (charcoal analysis) results from three sites in northeast Nigeria (Konduga, Gajiganna, Lantewa). The present-day vegetation at all four sites is Sahelian or Sahelo-Sudanian and under heavy human impact. At Oursi, a closed grassland with only few trees and almost no Sudanian elements can be reconstructed for the middle Holocene. At the Nigerian sites, on the other hand, Sudanian woody plants were present during this period. We assume that the Sahel was not a uniform zone during the middle Holocene but rather a mosaic of different vegetation types according to local site conditions. In the light of these results, a simple model of latitudinally shifting vegetation zones is not applicable. Around 3000 B.P. the closed grassland at Oursi was opened by agro-pastoral activities, and at Gajiganna, plants characteristic of pasture lands can be directly related with the presence of cattle. Human impact seems to have been the dominant factor in the vegetation history of the Sahel from 3000 B.P. until today, masking possible effects of climatic change.