黑龙江和图们江流域菱属(Trapa L.)植物分布格局及形态多样性

菱属(Trapa L.)的系统分类一直存在较大分歧,至今还没有一个比较公认的分类系统。黑龙江和图们江流域是菱属物种多样性的重要分布区之一,为了揭示该流域菱属植物的地理分布格局和形态多样性,我们进行了大量实地调查和研究。结果显示,从该地区28个湖中共采集到菱属11个种及8个种内变异类型,表明它们具有丰富的形态多样性;结合查阅菱属354份标本资料,共获得92个分布地点数据;采集到的11个物种的地理分布格局呈不均衡性,其中细果野菱(Trapa maximowiczii Korsch.)分布最广,野菱(Trapa incisa Siebold et Zucc.)、兴凯菱(Trapa khankensis Pshennikova)和科热夫尼科夫菱(Trapa kozhevnikovirum Pshennikova)为狭域分布种;东部乌苏里江和图们江流域是菱属物种多样性的分布中心,可能是第四纪冰期避难所;菱属植物多数种间形态特性相对稳定,东北菱(Trapa manshurica Fler.)、耳菱(Trapa potaninii V.Vassil)、丘角菱(Trapa japonica Fler.)、西伯利亚菱(Trapa sibirica Fler.)和细果野菱共有8个种内形态变异类型;种群内多数分类性状稳定,种群间形态变异较明显;菱属植物分布格局不均衡和种内形态变异的形成可能与基因流的扩散限制有关。本研究结果为进一步澄清菱属分类混乱问题奠定了基础,进一步结合分子标记技术研究系统演化关系将对揭示菱属的进化历史具有重要意义。     

Dissolved oxygen and fish distribution in a Florida spring

This study examined the distribution and relative abundance of fishes along a dissolved oxygen gradient in Singing Springs, Florida. Over the 1-year study, dissolved oxygen concentration in the spring exhibited a strong gradient ranging from an average of 0.20 mg l^–2AM¹ at the boil to 1.81 mg l^–2AM¹ 110 meters downstream. Seasonal variation in dissolved oxygen was very low relative to the spatial variation along the spring gradient. Fish community composition was evaluated monthly at the boil of the spring, 45 m downstream just after the confluence of the spring and the main river, and 110 m downstream. The fish community in the spring was characterized by species generally considered to be tolerant of low oxygen. Gambusia holbrooki was the most abundant species at all sites comprising an average of 88.1% of the fish captured at the boil, 63.2% of the fish captured at 45 m, and 74.8% of the fish captured at 110 m downstream. The diversity of fishes (G. holbrooki, Heterandria formosa, Notropis harperi, Lucania goodei, and Poecilia latipinna) increased with distance from the boil. Although there were some seasonal differences in patterns of diversity and community structure, the inter-site differences were much more apparent throughout the study. It is likely that the pattern of variation in dissolved oxygen interacts with the respiratory abilities of the fishes to affect the distribution pattern and community composition along the gradient.     

内蒙古魏家窝铺遗址陶器内淀粉粒反映的古人类食谱及相关问题

魏家窝铺遗址位于内蒙古赤峰市红山区文钟镇魏家窝铺村,是一处大型的红山文化中期环壕聚落遗址。在2009-2011年发掘出土的陶器中,许多平底器类标本内壁表面都发现有细腻的黑色灰烬,我们对这些灰烬和几件不含灰烬的陶器标本进行了植物残留物提取和鉴定,从六份样品中观测到了植物淀粉粒,这些淀粉粒可根据形态分为四种类型,分别代表了禾本科、植物地下储藏器官、疑似坚果的植物种类和未知种类。大量的禾本科淀粉粒在形态上与粟类(小米)淀粉粒极为相似,加之遗址中出土的大量炭化粟,我们推测,这些陶罐中的黑色灰烬为内部盛装的粟炭化分解所致,这些陶器正是红山文化中的食物储藏器。存在的其他类型淀粉粒表明,尽管魏家窝铺遗址出土的植物遗存已显示了较为确凿的农业经济,但采集经济也仍占有重要地位。     

Structural basis for polyspecificity in the POT family of proton‐coupled oligopeptide transporters

An enigma in the field of peptide transport is the structural basis for ligand promiscuity, as exemplified by PepT1, the mammalian plasma membrane peptide transporter. Here, we present crystal structures of di‐ and tripeptide‐bound complexes of a bacterial homologue of PepT1, which reveal at least two mechanisms for peptide recognition that operate within a single, centrally located binding site. The dipeptide was orientated laterally in the binding site, whereas the tripeptide revealed an alternative vertical binding mode. The co‐crystal structures combined with functional studies reveal that biochemically distinct peptide‐binding sites likely operate within the POT/PTR family of proton‐coupled symporters and suggest that transport promiscuity has arisen in part through the ability of the binding site to accommodate peptides in multiple orientations for transport.     

Dose-dependent blockade to cardiomyocyte hypertrophy by histone deacetylase inhibitors

Postnatal cardiac myocytes respond to stress signals by hypertrophic growth and activation of a fetal gene program. Recently, we showed that class II histone deacetylases (HDACs) suppress cardiac hypertrophy, and mice lacking the class II HDAC, HDAC9, are sensitized to hypertrophic signals. To further define the roles of HDACs in cardiac hypertrophy, we analyzed the effects of HDAC inhibitors on the responsiveness of primary cardiomyocytes to hypertrophic agonists. Paradoxically, HDAC inhibitors imposed a dose-dependent blockade to hypertrophy and fetal gene activation. We conclude that distinct HDACs play positive or negative roles in the control of cardiomyocyte hypertrophy. HDAC inhibitors are currently being tested in clinical trials as anti-cancer agents. Our results suggest that these inhibitors may also hold promising clinical value as therapeutics for cardiac hypertrophy and heart failure.     

Molecular cloning and characterization of rat and human calpain-5

Until today, 14 isoforms of mammalian calpains have been identified, including calpain-5. The C. elegans calpain-5 homologue tra-3 is reported to be essential for necrotic neuronal cell death. In this study, we cloned and characterized rat calpain-5, which is highly homologous to human and mouse sequences. The nucleotide sequence is 87% and 93% identical with human and mouse calpain-5, respectively. The protein sequence is well conserved, showing 96% identity in mouse and 92% in human. RT-PCR analysis revealed strong expression of calpain-5 in rat lungs, kidneys, and brain while week expression in heart, whereas in rat brain regions it is ubiquitously expressed. The mRNA expression in different human tissues showed equal expression. However, in human brain regions calpain-5 was strongly expressed in hypothalamus, thalamus, cerebellum, and frontal lobe. Western blot analysis on human neuroblastoma SH-SY5Y cells demonstrated calcium-dependent processing of calpain-5, despite the absence of calmodulin-like domain.