Dendroclimatic potential of dendroanatomy in temperature-sensitive Pinus sylvestris

The most frequently and successfully used tree-ring parameters for the study of temperature variations are ring width and maximum latewood density (MXD). MXD is preferred over ring width due to a more prominent association with temperature. In this study we explore the dendroclimate potential of dendroanatomy based on the first truly well replicated dataset. Twenty-nine mature living Pinus sylvestris trees were sampled in North-eastern Finland at the cool and moist boreal forest zone, close to the latitudinal tree line, where ring width, X-ray MXD as well as the blue intensity counterpart MXBI were compared with dendroanatomical parameters. Maximum radial cell wall thickness as well as anatomical MXD and latewood density appeared to be the most promising parameters for temperature reconstruction. In fact, these parameters compare favorably to MXD derived from X-ray techniques as well as MXBI, in terms of shared variation and temperature correlations across frequencies and over time. The reasons for these results are thought to be the unprecedentedly high measurement resolution of the anatomical technique, which provide the optimal resolution – the cell – whereas X-ray techniques have a slightly lower resolution and BI techniques even lower. While the results of this study are encouraging, further tests on longer and multigenerational chronologies are required to more generally and fully assess the dendroclimate potential of anatomical parameters.     

Colonization history of Galapagos giant tortoises: Insights from mitogenomes support the progression rule

Galapagos giant tortoises (Chelonoidis spp.) are a group of large, long-lived reptiles that includes 14 species, 11 of which are extant and threatened by human activities and introductions of non-native species. Here, we evaluated the phylogenetic relationships of all extant and two extinct species (Chelonoidis abingdonii from the island of Pinta and Chelonoidis niger from the island of Floreana) using Bayesian and maximum likelihood analysis of complete or nearly complete mitochondrial genomes. We also provide an updated phylogeographic scenario of their colonization of the Galapagos Islands using chrono-phylogenetic and biogeographic approaches. The resulting phylogenetic trees show three major groups of species: one from the southern, central, and western Galapagos Islands; the second from the northwestern islands; and the third group from the northern, central, and eastern Galapagos Islands. The time-calibrated phylogenetic and ancestral area reconstructions generally align with the geologic ages of the islands. The divergence of the Galapagos giant tortoises from their South American ancestor likely occurred in the upper Miocene. Their diversification on the Galapagos adheres to the island progression rule, starting in the Pleistocene with the dispersal of the ancestral form from the two oldest islands (San Cristóbal and Española) to Santa Cruz, Santiago, and Pinta, followed by multiple colonizations from different sources within the archipelago. Our work provides an example of how to reconstruct the history of endangered taxa in spite of extinctions and human-mediated dispersal events and provides a framework for evaluating the contribution of colonization and in situ speciation to the diversity of other Galapagos lineages.     

Model‐assisted identification of metabolic engineering strategies for Jatropha curcas lipid pathways

Efficient approaches to increase plant lipid production are necessary to meet current industrial demands for this important resource. While Jatropha curcas cell culture can be used for in vitro lipid production, scaling up the system for industrial applications requires an understanding of how growth conditions affect lipid metabolism and yield. Here we present a bottom‐up metabolic reconstruction of J. curcas supported with labeling experiments and biomass characterization under three growth conditions. We show that the metabolic model can accurately predict growth and distribution of fluxes in cell cultures and use these findings to pinpoint energy expenditures that affect lipid biosynthesis and metabolism. In addition, by using constraint‐based modeling approaches we identify network reactions whose joint manipulation optimizes lipid production. The proposed model and computational analyses provide a stepping stone for future rational optimization of other agronomically relevant traits in J. curcas.     

Developments,applications, and prospects of cryo‐electron microscopy

Cryo‐electron microscopy (cryo‐EM) is a structural biological method that is used to determine the 3D structures of biomacromolecules. After years of development, cryo‐EM has made great achievements, which has led to a revolution in structural biology. In this article, the principle, characteristics, history, current situation, workflow, and common problems of cryo‐EM are systematically reviewed. In addition, the new development direction of cryo‐EM—cryo‐electron tomography (cryo‐ET), is discussed in detail. Also, cryo‐EM is prospected from the following aspects: the structural analysis of small proteins, the improvement of resolution and efficiency, and the relationship between cryo‐EM and drug development. This review is dedicated to giving readers a comprehensive understanding of the development and application of cryo‐EM, and to bringing them new insights.     

资阳人头骨化石的内部解剖结构

资阳人头骨化石,是新中国成立后首次发现的保存较为完整的人类化石,曾经引起学术界的广泛关注。由于其出土的具体位点和层位不是很清楚,对其年代目前还存有争议。长期以来,对资阳人的研究局限于传统的头骨外部形态的描述和测量。本文利用高分辨率工业CT（Computed tomography）扫描资阳人头骨,并对其内部解剖结构 (包括骨壁结构、额窦、骨内耳迷路、颞骨乳突小房、颅内模) 进行3D虚拟复原和研究,以期获得更多的形态信息。CT断层图显示资阳人头骨的骨壁板障层较厚,远大于外板层和内板层,支持以往研究认为的该头骨属于50岁以上个体的鉴定结果。额窦呈叶形,局限于两侧眼眶的内上方;左、右侧额窦的表面积分别为1780mm²和2910mm²。骨性内耳迷路半规管的大小及其比例,与尼安德特人不同,而位于晚更新世和全新世现代人变异范围之间。颞骨乳突小房为气化型,几乎占据了整个乳突部。根据复原的颅内模,资阳人的颅容量约为1250mL。颅内模的各项测量数值虽然都偏小,但脑的绝大多数形态特征、宽-高指数、顶叶-脑长指数都位于现代人的变异范围之内,而与直立人和更新世古老型人类不同。资阳人头骨内部解剖结构保留有少量原始特征,包括枕叶向后突显著、大脑窝比小脑窝大而深,这些特征不同于全新世人类,更类似于晚更新世早期现代人。     

三维技术对安徽白鹭洲战国墓M566墓主容貌的复原

2011年安徽白鹭洲发现战国时期保存完整的楚国贵族墓葬,因墓主人头发和发簪保存完好、墓主身份显赫而备受关注。该头骨保存完整,具有亚洲蒙古人种的特征,根据骨骼的形态推测其为女性,年龄为35-39岁。为展现该地区战国贵族妇女的容貌、丰富该地区考古多样性提供研究材料。本文首先使用高分辨率CT对该个体的头骨及下颌骨进行了扫描和重建,然后采用基于偏最小二乘回归的颅面复原方法实现生前容貌基本形态的复原。最后,结合考古资料,利用三维模型处理软件对面貌复原模型及其发饰进行了三维建模和纹理贴图等处理,提高了颅面复原模型的真实感,生动形象地再现战国贵族女性面部的形态特征。     

RAPTURE (RAD capture) panel facilitates analyses characterizing sea lamprey reproductive ecology and movement dynamics

Genomic tools are lacking for invasive and native populations of sea lamprey (Petromyzon marinus). Our objective was to discover single nucleotide polymorphism (SNP) loci to conduct pedigree analyses to quantify reproductive contributions of adult sea lampreys and dispersion of sibling larval sea lampreys of different ages in Great Lakes tributaries. Additional applications of data were explored using additional geographically expansive samples. We used restriction site‐associated DNA sequencing (RAD‐Seq) to discover genetic variation in Duffins Creek (DC), Ontario, Canada, and the St. Clair River (SCR), Michigan, USA. We subsequently developed RAD capture baits to genotype 3,446 RAD loci that contained 11,970 SNPs. Based on RAD capture assays, estimates of variance in SNP allele frequency among five Great Lakes tributary populations (mean F_ST 0.008; range 0.00–0.018) were concordant with previous microsatellite‐based studies; however, outlier loci were identified that contributed substantially to spatial population genetic structure. At finer scales within streams, simulations indicated that accuracy in genetic pedigree reconstruction was high when 200 or 500 independent loci were used, even in situations of high spawner abundance (e.g., 1,000 adults). Based on empirical collections of larval sea lamprey genotypes, we found that age‐1 and age‐2 families of full and half‐siblings were widely but nonrandomly distributed within stream reaches sampled. Using the genomic scale set of SNP loci developed in this study, biologists can rapidly genotype sea lamprey in non‐native and native ranges to investigate questions pertaining to population structuring and reproductive ecology at previously unattainable scales.     

Les sépultures italiennes du Paléolithique supérieur. Reconstitutions du régime alimentaire

The identification of dietary habits is increasingly seen as a fundamental aspect for studying the ancient human populations. Accordingly, several projects aiming to identify Paleolithic individuals’ dietary patterns were developed to analyze the organic component of bone tissue and identify isotopic markers to reconstruct the food typology. Bone fragments from six individuals were selected for carbon and nitrogen stable isotopes analysis. The interpretation of human isotopic data was framed through a dataset of twenty-one Italian Paleolithic individuals. The isotopic data generated for the Paleolithic individuals agree with the information already provided by the archaeological record concerning the Italian hunter and gatherer communities. Their subsistence economy was essentially grounded upon the exploitation of high protein foods, either from terrestrial fauna resources or inland lacustrine or riverine species.     

基于雪岭云杉树轮宽度重建过去339年天山中部巴音布鲁克地区夏季NDVI

归一化差异植被指数(NDVI)被广泛应用于植被研究的各个领域,但由于观测时长较短,难以满足长时间尺度的研究需要。基于巴音布鲁克地区雪岭云杉建立了树轮宽度年表(STD),计算年表和NDVI同气象观测数据的相关系数。结果表明:树轮宽度指数和NDVI均与同时段的气象数据具有显著相关。结合宽度年表与6—8月NDVI间的显著正相关(r=0.7,P＜0.01,n=38),使用回归模型重建了研究区过去339年的夏季(6—8月)NDVI变化序列,在1680—2018年,重建序列有4个高植被覆盖时段(1738—1765、1786—1798、1964—1973和2000—2018年)和5个低植被覆盖时段(1690—1714、1825—1834、1850—1880、1895—1920和1945—1955年)。重建结果也反映了天山中部水文气候。与周边重建的对比显示,当开都河径流量增加,且研究区处于较为潮湿的环境时,植被覆盖相对较高,反之植被覆盖偏低。重建序列的极值也捕捉了历史文献中一系列自然灾害。混合单粒子拉格朗日综合轨迹模型(HYSPLT)后向轨迹模型和风场分析表明,NDVI异常受到西风带来的降水影响。