Spatiotemporal Developmental Trajectories in the Arabidopsis Root Revealed Using High-Throughput Single-Cell RNA Sequencing

1. Download high-res image (327KB)
2. Download full-size image

     

Underestimated ecosystem carbon turnover time and sequestration under the steady state assumption: A perspective from long‐term data assimilation

It is critical to accurately estimate carbon (C) turnover time as it dominates the uncertainty in ecosystem C sinks and their response to future climate change. In the absence of direct observations of ecosystem C losses, C turnover times are commonly estimated under the steady state assumption (SSA), which has been applied across a large range of temporal and spatial scales including many at which the validity of the assumption is likely to be violated. However, the errors associated with improperly applying SSA to estimate C turnover time and its covariance with climate as well as ecosystem C sequestrations have yet to be fully quantified. Here, we developed a novel model‐data fusion framework and systematically analyzed the SSA‐induced biases using time‐series data collected from 10 permanent forest plots in the eastern China monsoon region. The results showed that (a) the SSA significantly underestimated mean turnover times (MTTs) by 29%, thereby leading to a 4.83‐fold underestimation of the net ecosystem productivity (NEP) in these forest ecosystems, a major C sink globally; (b) the SSA‐induced bias in MTT and NEP correlates negatively with forest age, which provides a significant caveat for applying the SSA to young‐aged ecosystems; and (c) the sensitivity of MTT to temperature and precipitation was 22% and 42% lower, respectively, under the SSA. Thus, under the expected climate change, spatiotemporal changes in MTT are likely to be underestimated, thereby resulting in large errors in the variability of predicted global NEP. With the development of observation technology and the accumulation of spatiotemporal data, we suggest estimating MTTs at the disequilibrium state via long‐term data assimilation, thereby effectively reducing the uncertainty in ecosystem C sequestration estimations and providing a better understanding of regional or global C cycle dynamics and C‐climate feedback.     

旅游干扰对张家界大鲵生境及水质的影响

为探明旅游干扰对中国大鲵生境及水质的影响,本研究实地调查了湖南省张家界市2014—2016年间不同旅游强度下的干扰情况,测定了大鲵栖息生境特点、水体理化及微生物指标.结果表明: 重度旅游干扰(每年>50万人次)显著增加了噪音、减少了大鲵洞穴数,降低了水中溶解氧含量,增加了总氮、总磷含量及微生物数量,尤其是大肠杆菌数量,导致大鲵栖息生境质量下降.但重度干扰区的水质仍然能够达到大鲵生长要求.根据国家地表Ⅱ类水大肠杆菌标准最高值(2000个·L^-1),计算得出游客数量理论临界值为每年2604.71万人次.通过控制游客数量与旅游设施面积,可降低旅游干扰强度,保护大鲵栖息生境,促进旅游开发与大鲵保护的协调发展.     

利用红外相机公里网格调查钱江源国家公园的兽类及鸟类多样性

2014年5月至2019年4月, 作者采用红外相机技术调查了浙江省钱江源国家公园的兽类及鸟类多样性。将整个国家公园划分为267个1 km × 1 km的调查网格, 每个网格内设置3个固定调查位点, 使用1台红外相机定期在同一网格内的位点之间进行轮换。其中, 古田山片区在5年内共完成14轮次调查, 古田山以外的区域自2018年7月纳入调查范围, 何田、长虹片区完成2次轮换, 齐溪片区完成1次轮换。在253个网格内的741个有效位点上共获得140,413个相机工作日的数据, 采集兽类和鸟类的照片和视频268,833份, 有效探测数74,368次, 鉴定出21种野生兽类, 72种野生鸟类, 5种家畜及家禽。包括国家一级重点保护野生动物2种, 即黑麂(Muntiacus crinifrons)、白颈长尾雉(Syrmaticus ellioti); 国家二级重点保护野生动物17种, 合计占野生物种总数的20.4%。被IUCN物种红色名录评估为易危(VU)的5种, 近危(NT)的4种, 合计占物种总数的9.7%。被中国脊椎动物红色名录评估为濒危(EN)的1种, 易危(VU)的9种, 近危(NT)的10种, 合计占物种总数的21.5%。相对多度指数最高的大中型兽类为小麂(Muntiacus reevesi), 鸟类为白鹇(Lophura nycthemera)。本次调查获得了国家公园内兽类和鸟类的多样性组成、空间分布和相对多度, 为长期科研监测和科学管理提供了基础数据。     

关于贯彻落实“建立以国家公园为主体的自然保护地体系”的六项建议

<正>自2013年11月十八届三中全会提出"建立国家公园体制"以来,中国在不到5年时间中,以国家公园体制建设为契机,在全面深化自然保护地体制改革方面取得了里程碑式的重大进展,为实现生态文明和美丽中国国家战略奠定了坚实基础。为了更好地贯彻落实十九大报告提出的"建立以国家公     

主要组织相容性复合体单倍型鸭抗原处理相关转运体单抗的制备

目的制备鸭抗原处理相关转运体(TAP)特异性单抗,为深入利用实验鸭开展免疫学研究提供实验材料。方法利用大肠埃希菌诱导表达主要组织相容性复合体(MHC)单倍型HBW-SPF鸭TAP蛋白肽结合区片段,表达产物经镍柱纯化后免疫BALB/c小鼠,采用ELISA技术筛选特异性单抗分泌杂交瘤细胞株。将阳性细胞株制备小鼠腹水,作为一抗,与多次截短表达TAP蛋白肽结合区进行蛋白免疫印迹试验,鉴定单抗针对的抗原表位。通过间接免疫荧光试验比较该单抗对实验鸭和鸡外周血淋巴细胞的反应性,利用免疫组织化学技术检测对SPF鸡、SPF鸭、鹌鹑、鹅和SPF猪的特异性。结果获得一株鸭TAP单抗1A6,抗原表位位于²⁹⁷NARHQMLQQAVLDATAGTGMVVQEAI³²²,对鸡和鸭外周血淋巴细胞具有免疫荧光反应性;在鸡和鸭的肠黏膜固有层检测到大量特异性信号,在猪、鹌鹑和鹅没有检测到信号。结论获得了一株具有鸡和鸭反应性的抗原转运相关体特异性的单抗,可运用于禽类实验动物在禽病学和禽免疫学方面的研究。     

野生矮牡丹高通量转录组测序分析

为探究野生稷山矮牡丹(Paeonia jishanensis)花青素等抗氧化活性物质生物合成的遗传基础,本文采用高通量测序技术Illumina NextSeqTM500对其幼嫩叶片、嫩茎和花芽混合池样本进行转录组测序分析。共获得39450个unigene,其中3563个unigene中有4106个SSR位点。在Swiss Prot数据库中注释到29420个unigene,其中11个与花青素生物合成过程相关,22个与类黄酮生物合成过程相关,15个与异黄酮生物合成过程相关;NR数据库中注释高达100%,有12个与类黄酮生物合成相关,7个与花青素生物合成相关;GO数据库中注释到24291个unigene,分为生物学过程、细胞组分及分子功能等三大类53个功能组,有21个unigene与黄酮、黄酮醇及异黄酮生物合成有关,4个unigene与花青素合成有关;eggNOG数据库中注释到38238个unigene,涉及植物生长发育过程绝大多数生命活动过程;KEGG数据库注释到5709个unigene,分别定位到6大类别42个代谢途径,其中25个unigene与花青素生物合成相关。研究表明,在稷山矮牡丹转录组序列中,共鉴定和发掘出多个涉及类黄酮化合物生物合成、花青素生物合成过程的相关基因序列及SSR位点,为下一步开展相关代谢合成途径研究奠定了基础。     

基于Shuttleworth-Wallace模型的科尔沁沙地流动半流动沙丘蒸散发模拟

陆面蒸散发在气候调节和维持区域水量平衡中起关键作用.量化蒸散发及其各组分项,对深刻揭示干旱半干旱地区的生态水文过程具有重要意义.本研究基于科尔沁沙地流动半流动沙丘2017年生长季气象监测系统的原位监测数据,利用Shuttleworth-Wallace(S-W)模型对沙丘蒸散发进行模拟,在此基础上,对蒸散各组分进行拆分,并利用涡度相关对模拟蒸散发值进行验证.结果表明: 整个生长季模型模拟蒸散发值为308 mm,涡度相关实测值为296 mm,偏差较小,证明S-W模型适用于该地区的蒸散发模拟.蒸散发整体呈生长旺盛期>生长后期>生长初期,分别为192、71和45 mm,分别占总量的62.3%、23.1%和14.6%.日尺度上模型模拟值与实测蒸散发值一致性较高,模型模拟精度大体表现为: 晴天>阴天>雨天,且阴雨天模型模拟值较涡度相关实测值偏低.经拆分,土壤蒸发和植被蒸腾分别为176和132 mm,分别占总量的57.1%和42.9%,表明沙地水分利用效率较低.持续干旱和降水后,蒸散发规律明显不同,且土壤蒸发对降水的敏感性强于植被蒸腾.     

2型糖尿病模型小鼠造模时间的选择

目的:分析不同时期的2型糖尿病小鼠血生化指标及心肌和肾脏的病理变化情况,为选择2型糖尿病模型小鼠造模时间提供依据。方法:32只健康雄性ICR小鼠高脂饲料喂养6周后,腹腔注射链脲佐菌素(STZ,30mg/kg),连续5d,制备糖尿病模型。9d后测空腹血糖(FBG),高于11.1mmol/L视为糖尿病模型。分别于成模后第4、6、8周处死一组小鼠。另取8只雄性ICR小鼠作为对照组,常规饲料喂养,于糖尿病组小鼠成模后第8周处死。分析小鼠生化及病理情况:①心脏、肾脏脏器系数计算;②血清乳酸脱氢酶(LDH)、肌酸激酶(CK)、肌酐(Cr)和尿素氮(BUN)含量测定;③HE染色观察心肌和肾脏组织病变的整体情况;Masson染色观察心肌组织纤维化情况;PAS染色观察肾脏组织病理变化。结果:与对照组小鼠进行比较,第4、6、8周的糖尿病小鼠心脏器系数升高,血清LDH、CK升高,病理组织学见心肌细胞肥大,纤维化;肾脏脏器系数升高,肾功能肌酐(Cr)、尿素氮(BUN)显著升高,病理组织学见肾小球肥大,肾小管基底膜增厚,管腔萎缩。结论:第6周糖尿病小鼠相关生化病理指标改变相对明显且饲养时间相对较短,故2型糖尿病模型小鼠造模后第6周是进行药物干预和病理、生理、生化等研究的最佳时间。     

Pharmacokinetic,metabolic stability,plasma protein binding and CYP450s inhibition/induction assessment studies of N-(2-pyridylmethyl)-2-hydroxiymethyl-1-pyrrolidinyl-4-(3-chloro-4-methoxy-benzylamino)-5-pyrimidine-carboxamide as potential type 5 phosphodiesterase inhibitors

N-(2-pyridylmethyl)-2-hydroxiymethyl-1-pyrrolidinyl-4-(3-chloro-4-methoxy-benzylamino)-5-pyrimidine-carboxamide (NHPPC) is a new potential of type 5 phosphodiesterase (PDE5) inhibitors, synthesized from the avanafil analogue for the treatment of erectile dysfunction. The targets of this article were to assess plasma protein binding, liver microsomal metabolic stability, inhibition and induction on cytochrome P450 isozymes and the pharmacokinetics of NHPPC. Equilibrium dialysis technique was applied to determine Plasma protein binding (PPB) and NHPPC was evaluated in male Sprague–Dawley rats and Beagle dogs in vivo pharmacokinetic. The NHPPC was highly bound to plasma proteins in rats, dogs and human tested and the mean values for PPB rate were 96.2%, 99.6% and 99.4%, respectively. After in vitro liver microsomes incubated for 60?min, the percent remaining of NHPPC was 42.8%, 0.8% and 42.0% in rats, dogs and human, respectively. In vitro intrinsic clearance was found to be 0.0233, 0.1204 and 0.0214 mL/min/mg protein in rat, dog and human liver microsomes of NHPPC, respectively. NHPPC showed no significant inhibitory effects on major CYP450 enzymes, and had no significant induction potential on CYP1A2 and CYP3A4. Following oral administration in rats and dogs, t_max was 6 and 0.5?h, respectively. The clearance for NHPPC was 1.19 and 1.46?L/h/kg in rats and dogs, respectively. And absolute bioavailability in rat and dog were approximately 34.5% and 53.1%, respectively. These results showed that NHPPC has a good development prospect.