生物质多糖的高效降解与降解酶（系）的精确定制

自然界中多糖类生物质资源十分丰富,然而其复杂的抗降解屏障限制了生物转化的进程.近年来,随着生物质多糖结构的快速解析以及大量多糖降解酶的鉴定研究,针对不同底物结构或产物需求,仿制高效微生物多糖代谢途径,精确定制多糖降解酶系,促进生物质高效转化已成为可能.本文分析中性多糖(纤维素和木聚糖)、碱性多糖(几丁质和壳聚糖)以及酸性多糖(褐藻胶)的精细结构组成与基团性质,总结3类多糖主要降解酶的活性架构特征及其底物精确结合模式.文章还阐述蛋白质工程设计与定制策略,针对酶分子不同功能区的分析,可为酶分子的功能快速设计与改造提供靶点,以获得适宜于工业应用的高效酶分子,此外,根据微生物胞外降解酶系的降解次序与协同关系,可基于应用需求精确定制复杂多糖降解酶系,实现生物质的高效与高值降解转化.     

城市群生态安全格局构建:概念辨析与理论思考

城市群是城市发展到一定阶段通过城市间物流、人流和能流高度融合而形成的区域性复合生态系统，如何保障城市群生态安全与健康发展成为当前关注的热点问题。本研究系统分析了生态安全、城市生态安全与城市群生态安全的内涵。认为狭义上城市群生态安全侧重于城市群内部生态空间优化和生态系统服务功能提升，重点关注城市群地区生态用地空间优化与"三生空间"（生态、生活及生产空间）的合理布局。广义上的城市群生态安全不仅需要考虑城市群内部生态系统结构和功能协调及其生态系统服务的供需平衡，也需要从区域尺度考虑城市群与其他区域之间的协调关系。城市群生态安全格局构建的目的则是保障城市群内部区域一体化协调发展，满足人们日常生活的基本需求，实现城市群与区域之间物流、能流和人流的有序流通。在城市群生态安全格局构建时，除了遵循生态安全一般性原则外，还需要遵循以下原则：①生态系统服务供需平衡尺度效应；②生态安全保障的阈值效应；③生态安全格局的空间联动效应。最后文章提出了城市群生态安全格局构建的基本思路和技术路径。     

The role of YTH domain containing 2 in epigenetic modification and immune infiltration of pan-cancer

YTH domain containing 2 (YTHDC2) is the largest N6-Methyladenosine (m⁶A) binding protein of the YTH protein family and the only member containing ATP-dependent RNA helicase activity. For further analysing its biological role in epigenetic modification, we comprehensively explored YTHDC2 from gene expression, genetic alteration, protein-protein interaction (PPI) network, immune infiltration, diagnostic value and prognostic value in pan-cancer, using a series of databases and bioinformatic tools. We found that YTHDC2 with Missense mutation could cause a different prognosis in uterine corpus endometrial carcinoma (UCEC), and its different methylation level could lead to a totally various prognosis in adrenocortical carcinoma (ACC), cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), lung squamous cell carcinoma (LUSC) and UCEC. The main molecular mechanisms of YTHDC2 focused on catalytic activity, helicase activity, snRNA binding, spliceosome and mRNA surveillance. Additionally, YTHDC2 was notably correlated with tumour immune infiltration. Moreover, YTHDC2 had a high diagnostic value for seven cancer types and a prognostic value for brain lower grade glioma (LGG), rectum adenocarcinoma (READ) and skin cutaneous melanoma (SKCM). Collectively, YTHDC2 plays a significant role in epigenetic modification and immune infiltration and maybe a potential biomarker for diagnosis and prognosis in certain cancers.     

Vertebral Bomb Radiocarbon Suggests Extreme Longevity in White Sharks

Conservation and management efforts for white sharks (Carcharodon carcharias) remain hampered by a lack of basic demographic information including age and growth rates. Sharks are typically aged by counting growth bands sequentially deposited in their vertebrae, but the assumption of annual deposition of these band pairs requires testing. We compared radiocarbon (Δ¹⁴C) values in vertebrae from four female and four male white sharks from the northwestern Atlantic Ocean (NWA) with reference chronologies documenting the marine uptake of ¹⁴C produced by atmospheric testing of thermonuclear devices to generate the first radiocarbon age estimates for adult white sharks. Age estimates were up to 40 years old for the largest female (fork length [FL]: 526 cm) and 73 years old for the largest male (FL: 493 cm). Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies, hint at possible sexual dimorphism in growth rates, and raise concerns that white shark populations are considerably more sensitive to human-induced mortality than previously thought.     

NAADP-induced intracellular calcium ion is mediated by the TPCs (two-pore channels) in hypoxia-induced pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a form of obstructive vascular disease. Chronic hypoxic exposure leads to excessive proliferation of pulmonary arterial smooth muscle cells and pulmonary arterial endothelial cells. This condition can potentially be aggravated by [Ca²⁺] _i mobilization. In the present study, hypoxia exposure of rat's model was established. Two-pore segment channels (TPCs) silencing was achieved in rats' models by injecting Lsh-TPC1 or Lsh-TPC2. The effects of TPC1/2 silencing on PAH were evaluated by H&E staining detecting pulmonary artery wall thickness and ELISA assay kit detecting NAADP concentrations in lung tissues. TPC1/2 silencing was achieved in PASMCs and PAECs, and cell proliferation was detected by MTT and BrdU incorporation assays. As the results shown, NAADP-activated [Ca²⁺]_i shows to be mediated via two-pore segment channels (TPCs) in PASMCs, with TPC1 being the dominant subtype. NAADP generation and TPC1/2 mRNA and protein levels were elevated in the hypoxia-induced rat PAH model; NAADP was positively correlated with TPC1 and TPC2 expression, respectively. In vivo, Lsh-TPC1 or Lsh-TPC2 infection significantly improved the mean pulmonary artery pressure and PAH morphology. In vitro, TPC1 silencing inhibited NAADP-AM-induced PASMC proliferation and [Ca²⁺]_i in PASMCs, whereas TPC2 silencing had minor effects during this process; TPC2 silencing attenuated NAADP-AM- induced [Ca²⁺]_i and ECM in endothelial cells, whereas TPC1 silencing barely ensued any physiological changes. In conclusion, TPC1/2 might provide a unifying mechanism within pulmonary arterial hypertension, which can potentially be regarded as a therapeutic target.     

基于野外观测检验动物廊道选址模型的准确性——以白头叶猴为例

廊道构建是减少栖息地破碎化负面影响的重要策略之一。目前，已经有许多模型用于动物廊道的选址，而"选址模型是否能准确预测动物迁移的实际发生位置"一直是保护生物学最为关注的问题。最小成本路径模型（LCP）和条件最小成本廊道模型（CMTC）是两种较为常用的廊道选址模型。以白头叶猴（Trachypithecus leucocephalus）为目标物种，分别运用LCP和CMTC模拟生成白头叶猴迁移廊道，将模拟结果与野外观测廊道进行对比，检验两种方法的准确性。结果表明：与野外观测实际廊道相比，LCP模型模拟结果的完全准确率为46.7%，部分准确率为20%，完全不准确率为33.3%；CMTC模型模拟结果的完全准确率为26.7%，其余73.3%为部分准确，无完全不准确的结果；总体上看，CMTC廊道的准确率较LCP高，因而CMTC模型模拟白头叶猴实际迁移廊道位置的准确性优于LCP模型。输入"源"要素类型、阻力面栅格尺度设定、栖息地土地利用类型变化以及动物迁移行为复杂性4个因素是影响该模拟结果准确性的主要原因。     

基于SBE法的广东省生态景观林带美景度评价

采用美景度评价法(SBE法)对广东省生态景观林带进行评价，分析影响生态景观林带景观水平的主要因子，探讨生态景观林带景观构成要素与景观质量的关系。结果表明，不同专业、性别、学历、年龄的人群在森林审美态度上具有一致性，其评判结果能够反映森林美景度的实际情况；对53张照片评价SBE值，最大为1.4454，最小为-1.6917；对美景度影响较大的4个因子，即色彩丰富度(X6)、色泽明度(X7)、生活型(X8)、生长状况(X9)，建立的多元线性回归模型是 Y=1.902-0.346X6-0.461X7+ 0.206X8-0.584X9。     

CONTROL OF PLASMODIAL FUSION IN A PANAMANIAN ISOLATE OF DIDYMIUM IRIDIS

Plasmodial fusion in a Panamanian isolate (Pan. 1) of Didymium iridis is controlled by at least six fusion loci. Only plasmodia with identical phenotypes for these six loci are capable of fusion. No evidence was obtained in this study to indicate that any one fusion locus more strongly affects the fusion process than any of the other loci. Control of plasmodial fusion in the Pan. 1 strain of D. iridis is similar to that found earlier for a Honduran strain (Hon. 1).