COVID-19 immune features revealed by a large-scale single-cell transcriptome atlas

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Microdensitometric records from humid subtropical China show distinct climate signals in earlywood and latewood

Blue intensity (BI) from tree rings is a technique that has been widely explored for temperature reconstruction purposes in middle and high latitudes. However, it is still rather untested at lower latitudes and in drier climates, particularly in subtropical areas. Here, we develop the first series of BI-based tree-ring parameters (earlywood BI, EWBI; latewood BI, LWBI and ΔBI, the difference between LWBI and EWBI) in humid subtropical China from the species Pinus massiniana. Although the BI parameters have weaker inter-series correlations than do ring widths, they are generally better correlated with climate parameters. Our study shows a positive temperature response in the EWBI parameter and negative responses in the LWBI and ΔBI parameters. Interestingly, the correlation pattern is almost the opposite of that observed at high latitudes, where there is a pronounced positive sensitivity of the LWBI/ΔBI/MXBI parameters to temperature.We find the EWBI to be the most robust parameter for reconstruction purposes. The positive March–May average temperature signal of EWBI is stable across frequencies and shows consistent interdecadal variations with other temperature proxy series from the region. The compilation of new tree-ring records using the BI technique will ultimately support our understanding of climate history. For this reason, we encourage similar attempts to push the boundaries of the BI technique even further.     

Water allocation and climate-impacted riparian forest dynamics in the Ejina Oasis,Northwest China

Riparian forests in natural desert oases are extremely vulnerable to water shortages; of late these shortages have been associated with climate change and with increased human-led water allocation. This study covers a hundred-year history (1876–2017) of riparian forest growth at the Ejina Oasis, which is located in the lower reaches of the Heihe River basin of northwestern China. We collected tree cores from Populus euphratica, which is the major tree species found in the Ejina riparian forests. These samples allowed us to chart variations in riparian forest growth and to examine correlations between tree growth and local precipitation, temperature, drought indices, groundwater depth, and runoff volume from the middle reaches of the river. We found that groundwater depth (groundwater being mainly recharged by runoff) is the major factor limiting tree-stem radial growth. We compared runoff reconstruction series from upper reaches and P. euphratica radial growth in the lower reaches. We found a period of greatly decreased growth (1942–1951); which seems to have been due to human water diversion. We note that mountain runoff increased after 2000, but that riparian forest growth didn’t increase in tandem; the water that would otherwise have supported the forests had been diverted. Our study provides a warning for future water resource planning and suggests the desirability of policies that will balance the needs of natural ecosystems (riparian forests) with the requirements of artificial ecosystems (croplands).     

细胞分裂素对吊兰根生长和负向光性的影响

为了研究细胞分裂素对吊兰根生长和负向光性的影响,采用水培法将吊兰培养在透明玻璃缸内,并向水培液中添加6-BA和对水培吊兰根系进行单侧照光的方法,研究结果表明:(1)6-BA对吊兰不定根和侧根的生长以及负向光性都有抑制作用,抑制程度随着浓度的增加而加剧;(2)10mg·L^-16-BA处理7d后和100mg·L^-16-BA5天后不定根停止生长;(3)10-100mg·L^-16-BA处理的吊兰侧根均不能伸长,只能够在不定根表明形成凸起的结构,但凸起的数量随着6-BA浓度的增加而增加;(4)吊兰根系在无6-BA处理时在单侧光下弯曲度可达到接近90°,100mg·L^-16-BA可使其弯曲度下降至15°左右.探讨了6-BA抑制吊兰根生长和负向光性的可能机理.     

Evaluation of new porous β-tri-calcium phosphate ceramic as bone substitute in goat model

The present study was carried out to evaluate the porous β-tri-calcium phosphate (TCP) (prepared by aqueous solution combustion technique) as bone substitute and compared with normal healing in 12 adult Black Bengal goats on the basis of clinical and radiographic findings, histological studies, oxytetracycline labeling, angiography studies (on day 90). Bone defects created in the diaphysis of radius were left unfilled in control animals (group I); while in treated (group II) animals the defects were filled with porous TCP blocks. The three months study showed no marked acute inflammatory reactions in all animals, wound healing was uneventful and the implants were clinically stable in the bone. Radiological studies showed presence of unabsorbed implants which acted as a scaffold for new bone growth across the defect whereas in control animals the defect was more or less same except that the newly formed bony tissue was less organized. Histological section showed moderately differentiated lamellar bone in the cortical part with presence of woven bone at peripheral cortex whereas control animals showed moderate fibro-collagenisation and good amount of marrow material, fat cells and blood vessels. Oxytetracycline labeling study showed crossing over of new bony trabeculae along with presence of resorption cavities within the new osteoid tissues whereas in group I, the process of new bone formation was active from both the ends; the defect site appeared as a homogenous non-fluorescent area. Angiogram of the animals in control showed uniform angiogenesis in the defect site with establishment of trans transplant angiogenesis, whereas in group II there was complete trans transplant shunting of blood vessels communication. The results of this study pointed out that the porous TCP promoted extensive bone formation over the entire extension of the defect in comparison to control group, thus conforming their biological osteoconductive property.     

亚热带人工和天然马尾松、杉木林生长对干旱的生态弹性差异

选取福建中西部地区相似气候条件下马尾松和杉木的天然林和人工林进行研究,利用年轮宽度、年轮宽度指数和断面积增量重建了4种林型共109株松树20年(1993—2012年)的年生长量,计算其对连续两次极端干旱事件(2003—2004年和2011年)的抵抗力、恢复力和弹性指数,分析人工林和天然林在抵抗力和弹性方面的差异。结果表明:马尾松和杉木对水分的需求在时间上存在差异,这解释了其对2003—2004年干旱事件的响应不一致。干旱压力极大地降低了马尾松和杉木的生长,但树木生长并未表现出干旱遗留效应。受干旱强度的影响,4种林型径向生长对2003—2004年干旱的响应强于2011年。干旱事件后马尾松比杉木具有更强的恢复能力;天然林比人工林对干旱的敏感性更高,同时弹性也更大。杉木人工林更容易受到频发的极端干旱事件的影响,在人工林抚育管理中应选择抗旱能力较强的遗传种源,以应对气候变暖导致的干旱频发。     

星斗山国家级自然保护区国家重点保护野生植物优先保护定量研究

在野外调查的基础上,运用濒危系数、遗传价值系数和物种价值系数对星斗山自然保护区33种国家保护植物的优先保护顺序进行定量分析。结果表明属一级保护的有银杏、水杉、伯乐树、珙桐、光叶珙桐、台湾杉和水青树共7种,占21%;属二级保护的有红豆杉、南方红豆杉、蓖子三尖杉、大果青杄、金钱松、黄杉、榧树、连香树、闽楠、楠木、花榈木、鹅掌楸、峨眉含笑、红椿、毛红椿和川黄檗共16种,占49%;属三级保护的有莼菜、金毛狗、红豆树、厚朴、凹叶厚朴、香果树和榉树7种,占21%;属四级保护的有樟树、野大豆和金荞麦共3种,占9%。并提出了加强重点保护野生植物的保护措施。     

银杏叶绿体petD基因的克隆与表达

根据黑松、云杉、菠菜与玉米叶绿体petD基因序列设计引物,以银杏叶绿体基因组DNA为模板,PCR扩增克隆了银杏叶绿体petD基因（GenBank登录号为DQ923066,命名为GbpetD）的序列。序列分析显示,GbpetD基因组DNA序列编码区长1243bp,含1个内含子和2个外显子,其外显子序列编码177个氨基酸。相似性比对显示,该基因编码区序列与云杉、台东苏铁、黑松、莴苣、木薯、北美落叶松的petD基因核苷酸同源性为84％-99％,氨基酸序列同源性为85％-93％。系统进化树分析结果表明GbpetD蛋白质与黑松、北美落叶松、云杉、苏铁等裸子植物的petD蛋白质聚类关系最近。半定量RT—PCR分析表明,GbpetD基因在银杏叶和茎中表达,在叶中表达量最大。     

Characteristics of a biopolymer flocculant produced by Bacillus sp. PY-90

A biopolymer flocculant-producing bacterium, strain PY-90, was isolated and considered to belong to Bacillus subtilis. For the production of biopolymer flocculant by strain PY-90, a medium containing 2 to 5% l-glutamic acid as a nitrogen source was suitable. The biopolymer flocculant was a homopolymer composed of glutamic acid residues and was presumed to be poly(γ-glutamic acid). In kaolin suspension, the highest flocculating activity was attained at the biopolymer flocculant concentration of 20 mg/l. The flocculating activity was increased by the addition of Ca²⁺, and the optimum concentration of which was about 2 to 8 mM. The flocculating activity was high in an acidic pH range of 3.0 to 5.0, and decreased upon heating at 100°C.     

云南省外来入侵植物的区系成分及多样性分析

【目的】弄清云南省外来入侵植物的区系成分及多样性成因,为减少外来入侵植物对云南省生物多样性的影响提供理论依据。【方法】在已知云南省外来入侵植物种类组成的基础上,对其科、属、种的分布区类型进行了分析,并从生态指标(种子植物数、气候类型数、地表水总量、年均最高温)及社会经济指标(10年总进口额,10年总入境游客数) 2方面,将云南省与其他入侵植物多样性最高的9个省市进行比较,以探讨外来入侵植物多样性的成因。【结果】在区系组成上,云南省外来入侵植物的热带成分占绝对优势,其比例在科、属、种水平上分别为50.85%、63.16%和63.39%。入侵种所在科、属,常广域分布,但入侵种原产地分布范围却不大,并倾向于集中在某些特定区域(如热带美洲、狭义地中海区)。入侵植物所在科的入侵种数与该科包含的世界种数存在显著性正相关。省市级行政区域内入侵植物种数与该省市国际贸易额、入境游客数等指标没有相关性,而与各省市的种子植物数、气候类型数存在显著性关系,与地表水总量和年均温度存在一定的关系。【结论】云南省的自然生境适宜外来入侵植物的生存和扩散。需要对具有热带性质,所在分类单元为大科、大属,且地理分布距离与云...