Identification of cardiac stem cells within mature cardiac myocytes

Cardiac stem cells are described in a number of mammalian species including humans. Cardiac stem cell clusters consisting of both lineage-negative and partially committed cells are generally identified between contracting cardiac myocytes. In the present study, c-kit⁺, Sca⁺, and Isl1⁺ stem cells were revealed to be located inside the sarcoplasm of cardiac myocytes in myocardial cell cultures derived from newborn, 20-, and 40-day-old rats. Intracellularly localized cardiac stem cells had a coating or capsule with a few pores that opened into the host cell sarcoplasm. The similar structures were also identified in the suspension of freshly isolated myocardial cells (ex vivo) of 20- and 40-day-old rats. The results from this study provide direct evidence for the replicative division of encapsulated stem cells, followed by their partial cardiomyogenic differentiation. The latter is substantiated by the release of multiple transient amplifying cells following the capsule rupture. In conclusion, functional cardiac stem cells can reside not only exterior to but also within cardiomyocytes.     

Analysis of conformational motions and related key residue interactions responsible for a specific function of proteins with elastic network model

Protein collective motions play a critical role in many biochemical processes. How to predict the functional motions and the related key residue interactions in proteins is important for our understanding in the mechanism of the biochemical processes. Normal mode analysis (NMA) of the elastic network model (ENM) is one of the effective approaches to investigate the structure-encoded motions in proteins. However, the motion modes revealed by the conventional NMA approach do not necessarily correspond to a specific function of protein. In the present work, a new analysis method was proposed to identify the motion modes responsible for a specific function of proteins and then predict the key residue interactions involved in the functional motions by using a perturbation approach. In our method, an internal coordinate that accounts for the specific function was introduced, and the Cartesian coordinate space was transformed into the internal/Cartesian space by using linear approximation, where the introduced internal coordinate serves as one of the axes of the coordinate space. NMA of ENM in this internal/Cartesian space was performed and the function-relevant motion modes were identified according to their contributions to the specific function of proteins. Then the key residue interactions important for the functional motions of the protein were predicted as the interactions whose perturbation largely influences the fluctuation along the internal coordinate. Using our proposed methods, the maltose transporter (MalFGK₂) from E. Coli was studied. The functional motions and the key residue interactions that are related to the channel-gating function of this protein were successfully identified.     

Synthesis and biological characterization of new aryloxyindole-4,9-diones as potent trypanosomicidal agents

A new indole-4,9-dione and their phenoxy derivatives were synthesized and evaluated in vitro against the epimastigote form of Trypanosoma cruzi, Y strain. All of these novel compounds were found to be extremely potent and selective that the standard drug nifurtimox. Interestingly, phenoxyindole-4,9-dione 9d displayed excellent nanomolar inhibitory activity, IC₅₀ = 20 nM, and high selectivity index, SI = 625. In silico studies using MOE program were performed to generate a preliminary pharmacophore model.     

Feral cat diet and impact on sooty terns at Juan de Nova Island, Mozambique Channel

Feral cat Felis catus predation on seabirds has been well documented; however, details regarding shifts in feral cat diet in relation to seabird availability, seabird predation rate and impact on seabird population dynamics are scarce. Here, we present data documenting a seasonal shift in feral cat diet at Juan de Nova Island, Mozambique Channel. We also quantify sooty tern Sterna fuscata predation by feral cats and examine the impact on sooty terns over both the short term (by removing individual cats from sub-colonies) and over the longer term by highlighting their influence on population growth rate ( λ ) using a deterministic matrix model. Cat diet shifted dramatically from insects, rats and mice outside the tern breeding season to primarily terns when terns were breeding. The predation rate of sooty terns at Juan de Nova was estimated at 5.94 terns cat⁻¹ day⁻¹, with a proportion of these (22%) being killed without being consumed ('surplus kills'). When only one cat was removed from each sub-colony, tern predation declined tenfold in the short term. From our matrix model, the annual growth rate for sooty terns was 1.01 in the absence of cat predation. It remained above one until a predation impact equivalent to approximately three times the estimated cat density (12.04 per km²) was incorporated. Our results demonstrate that cats preferentially predate and have an impact on breeding sooty terns at Juan de Nova, and that an increase in cat density could lead to negative effects on population growth, despite the large breeding tern population.     

Signalling of information that is neither cryptic nor private

It is commonly assumed that in order for animal signals to be advantageous, the information being signalled could not have been obtained otherwise, and is therefore ‘cryptic’ or ‘private’. Here, we suggest a scenario in which individuals can gain an advantage by signalling ‘public’ information that is neither cryptic nor private. In that scenario, signalling increases the efficiency with which that ‘public’ information is transmitted. We formalize our idea with a game in which offspring can signal their condition to their parents. Specifically, we consider a resource‐strapped parent who can only invest in one of its two offspring, and we allow offspring the chance to influence parental investment through a signal. A parent in the game seeks to invest in the higher‐quality offspring, which it could identify either through a publicly available cue, such as body size, or by relying on a signal provided by the offspring. We find that if the signal can convey information about offspring quality more efficiently than cues, then signalling of condition between offspring and parents can be favoured by selection, even though parents could potentially have acquired the same information from the cue. Our results suggest that the biological function of signals may be broader than currently considered, and provide a scenario where low cost signalling can be favoured. More generally, efficiency benefits could explain signalling across a range of biological and economic scenarios.     

2001-2010年疏勒河流域植被净初级生产力时空变化及其与气候因子的关系

通过改进的光能利用率CASA模型估算2001-2010年间疏勒河流域陆地生态系统的净第一性生产力（NPP），采用线性趋势分析、变异系数和Hurst指数等方法，分析了NPP的时空变化特征及其与气候因子的相关性。结果表明：①疏勒河流域NPP的空间分布具有明显差异，空间上呈现西北低、东南高的趋势，且具有较明显的经向"条带"分布特征，2001-2010年，NPP平均值为102.26 gC m^-2 a^-1。②2001-2010年，疏勒河流域NPP总体呈增长趋势，年际波动较大，NPP明显增加的区域占总面积25.15%，明显减小的区域约占11.93%。③Hurst指数分析显示，疏勒河流域NPP变化的同向特征强于反向特征，其中持续改善地区占总面积的78.3%，21.7%的区域将由改善转为退化。④在年尺度上，降水是植被NPP变化的主要影响因素，NPP与降水呈弱的正相关关系，与温度相关性不显著；在月尺度上，温度是NPP变化的主要控制因子。疏勒河流域NPP对气候因子不存在明显的时滞和累积效应。     

气候变化下中国八种梧桐属树种潜在适生区模拟

中国梧桐属（Firmiana）在世界梧桐属中占比较大，且除梧桐外其余种均为中国特有且分布范围狭窄的植物种，灭绝风险大，研究气候变化对中国梧桐属树种的影响对于维护生物多样性具有重要的意义。结合多时期第六次国际气候耦合模式比较计划（CMIP6）气候变量数据和中国八种梧桐属树种的分布数据，基于R语言kuenm程序包优化的最大熵（Maxent）模型模拟分析中国八种梧桐属树种在多尺度下的潜在适生区，得出梧桐属最适宜的模拟尺度、潜在适生区的面积变化和迁移方向、梧桐属多样性保护关键区域及保护空缺。结果表明：（1）梧桐属最适宜的模拟尺度为亚洲；（2） Maxent模型的接收者操作特征曲线下面积（AUC）值均大于0.9，表明模型对梧桐属潜在适生区预测结果具有较高准确度；（3）气候变化影响下除云南梧桐（Firmiana major）外其它树种的潜在适生区都将在未来有所扩大；（4）中国八种梧桐属树种潜在适生区迁移方向主要为东西向，南北向大跨度迁移较少，纬度变化不大；（5）丹霞梧桐（Firmiana danxiaensis）的稳定潜在适生区最小；（6）中国梧桐属多样性保护关键区域主要分布于广西壮族自治区及云南、广东、海南等省区；（7）中国梧桐属多样性保护空缺区域主要分布于广西壮族自治区中部及海南省北部；（8）梧桐属多样性保护关键区域正在为人造地表所侵蚀。研究分析气候变化对中国八种梧桐属树种的影响及其潜在适生区变化、中国梧桐属多样性保护状态，可为中国梧桐属建立多样性保护廊道提供相关建议，为制定多样性保护规划及相应措施提供参考。