Enhanced terrestrial carbon uptake in the Northern High Latitudes in the 21st century from the Coupled Carbon Cycle Climate Model Intercomparison Project model projections

The ongoing and projected warming in the northern high latitudes (NHL; poleward of 60 °N) may lead to dramatic changes in the terrestrial carbon cycle. On the one hand, warming and increasing atmospheric CO₂ concentration stimulate vegetation productivity, taking up CO₂. On the other hand, warming accelerates the decomposition of soil organic matter (SOM), releasing carbon into the atmosphere. Here, the NHL terrestrial carbon storage is investigated based on 10 models from the Coupled Carbon Cycle Climate Model Intercomparison Project. Our analysis suggests that the NHL will be a carbon sink of 0.3 ± 0.3 Pg C yr^?1 by 2100. The cumulative land organic carbon storage is modeled to increase by 38 ± 20 Pg C over 1901 levels, of which 17 ± 8 Pg C comes from vegetation (43%) and 21 ± 16 Pg C from the soil (8%). Both CO₂ fertilization and warming enhance vegetation growth in the NHL. Although the intense warming there enhances SOM decomposition, soil organic carbon (SOC) storage continues to increase in the 21st century. This is because higher vegetation productivity leads to more turnover (litterfall) into the soil, a process that has received relatively little attention. However, the projected growth rate of SOC begins to level off after 2060 when SOM decomposition accelerates at high temperature and then catches up with the increasing input from vegetation turnover. Such competing mechanisms may lead to a switch of the NHL SOC pool from a sink to a source after 2100 under more intense warming, but large uncertainty exists due to our incomplete understanding of processes such as the strength of the CO₂ fertilization effect, permafrost, and the role of soil moisture. Unlike the CO₂ fertilization effect that enhances vegetation productivity across the world, global warming increases the productivity at high latitudes but tends to reduce it in the tropics and mid‐latitudes. These effects are further enhanced as a result of positive carbon cycle–climate feedbacks due to additional CO₂ and warming.     

Cucumis属3种不同倍性种间杂交后代的同工酶分析

以3种不同倍性的Cucum is属种间杂交后代[异源四倍体C.hy tivus(2n=4x=38,HHCC)、异源三倍体(2n=3x=26,HCC)和正反交种间杂种F1(2n=2x=19,HC/CH)]及其双亲为试材,比较研究了过氧化物酶(POD)和酯酶(EST)同工酶在不同器官中的酶谱表达特性.结果表明,花蕾中的POD和EST同工酶谱带都比叶片中的丰富,表现出明显的组织特异性.在相同器官的同一酶系统中,3种不同倍性种间杂交后代的酶谱基本一致,主要表现为互补双亲的酶带,同时出现了双亲所没有的酶带(POD4c和EST3b等),表明远缘杂交扩大了黄瓜的遗传基础.此外,在幼叶和花蕾的POD同工酶中,大部分酶带活性随染色体倍性增加而减弱,表明基因剂量与POD同工酶酶谱的表达呈负相关.     

野黄瓜(Cucumis hystrix Chakr.)与3种不同基因型栽培黄瓜(C.sativus L)

野黄瓜(Cucum is hystrix,2n=24)为短日照植物,因其与栽培黄瓜(C.sativus,2n=14)花期不遇等杂交障碍的存在而使种间杂交难以顺利进行。对野黄瓜短光照处理40 d以上,使得两者花期相遇,成功地进行了野黄瓜与3种不同基因型栽培黄瓜(“二早子”、“长春密刺”和“NC4406”)的正反杂交,从中获得了3种杂交组合的幼胚。采用改良的方法对这3种基因型杂种胚进行胚胎拯救,再生频率达80%以上,其杂种的真实性通过植物学性状观察、体细胞染色体计数和天冬氨酸转氨酶(AAT)同工酶分析得到了证实。研究中还发现不同基因型杂种F1的育性存在明显差异,其中以C.hystrixדNC4406”育性最高,花粉可染率达23.3%,是在二倍体水平上进行育种利用的良好材料。     

天目山柳杉树轮δ13C年序列差异

对天目山3株柳杉树轮δ¹³C年序列分别进行了测定,分析了柳杉树轮δ¹³C年序列变化的异同及其原因.结果表明,在1837～1982年的共同时段,3个树轮δ¹³C年序列彼此间相关系数为：r₁₂=0.47,r₁₃=0.65,r₂₃=0.52 (n=146),都通过了显著性水平α=0.001的信度检验.用多项式拟合法去除原δ¹³C年序列中的高频变化后,所得3个低频序列间高度正相关;原δ¹³C年序列与拟合序列的差值序列即高频序列间也显著正相关,相关系数均达到0.79～0.99,说明气候因素引起树轮δ¹³C年序列的高频变化及大气CO₂浓度引起的低频变化对不同的柳杉个体是共同的.3株树轮δ¹³C年序列间的差异主要是树木立地处局部环境条件的不同所造成的,但是局部环境条件所引起的树轮δ¹³C年序列间的个性差异对其共性变化影响较小.所以,3个树轮δ¹³C年序列间的个性差异,并不影响树轮δ¹³C年作为气候变化研究代用资料的适宜性及重建历史气候结果的可靠性与一致性.     

Morphine treatment enhances extracellular ATP enzymolysis and adenosine generation in rat astrocytes

Recent studies have shown that astrocytes play important roles in ATP degradation and adenosine (a well known analgesic molecule) generation, which are closely related to pain signaling pathway. The aim of this study was to investigate whether morphine, a well known analgesic drug, could affect the speeds of ATP enzymolysis and adenosine generation in rat astrocytes. Intracellular calcium concentration ([Ca(2+)](i)) of astrocyte was measured by flow cytometry, and the time points that morphine exerted notable effects were determined for subsequent experiments. Cultured astrocytes were pre-incubated with morphine (1 μmol/L) and then were incubated with substrates, ATP and AMP, for 30 min. The speeds of ATP enzymolysis and adenosine generation were measured by high performance liquid chromatography (HPLC). The results showed that both 1.5 and 48 h of morphine pre-incubation induced maximal ATP enzymolysis speed in astrocytes among all the time points, and there was no statistical difference of ATP enzymolysis speed between morphine treatments for 1.5 and 48 h. As to adenosine, morphine pre-incubation for 1.5 h statistically increased adenosine generation, which was degraded from AMP, in cultured astrocytes compared with control group. However, no difference of adenosine generation was observed after 48 h of morphine pre-incubation. These results indicate that treatment of morphine in vitro dynamically changes the concentrations of ATP and adenosine in extracellular milieu of astrocytic cells. In addition, astrocyte can be regarded as at least one of the target cells of morphine to induce changes of ATP and adenosine levels in central nervous system.     

植物UV-B生理效应的分子机制研究进展

中波紫外线UV-B（280～320nm）是植物必需的太阳光线的组成部分,具有明显的双重效应：一方面UV-B在强度较高时,就触发产生大量活性氧对DNA、蛋白质以及生物膜等造成伤害,同时植物通过抗氧化系统对其作出防御反应以减轻伤害;另一方面,低强度的UV-B是植物生长发育的光信号因子之一,经由UVR8等光受体介导中、低、极低强度的UV-B信号,可能通过几个分子途径控制相关基因的表达,分别对植物的UV-B保护基因表达、形态建成、昼夜节律、生长发育等进行调控。目前对UVR8介导的低强度UV-B信号转导的分子机制研究相对深入。在本文中,将对UV-B生理效应分子机制的最新研究进展作一个比较全面的介绍。     

鳜早期发育阶段骨骼肌纤维的增生与肥大生长

骨骼肌是鱼体的主要组成部分,也是衡量鱼体生长发育的重要指标.为了解鳜(Siniperca chuatsi)早期发育阶段骨骼肌纤维的生长发育特征,通过制作孵化后1 ～41日龄个体骨骼肌背右侧第一肌节石蜡切片,利用图像分析软件统计该肌节中肌纤维的数目和面积,分析了鳜骨骼肌纤维的增生和肥大生长特征.结果表明,鳜早期发育阶段骨...     

北美冬青‘奥斯特’的组织培养和快速繁殖

以北美冬青‘奥斯特’(‘Oosterwijk’)成年雌性优良单株半木质化茎段为材料,建立了组织培养快速繁殖体系。结果表明,WPM+6-BA 0.50 mg·L-1+NAA 0.05 mg·L-1可作为启动培养基,最佳的继代增殖培养基为WPM+6-BA 1.00 mg·L-1+NAA0.10 mg·L-1+蔗糖20 g·L-1,25 d的增殖系数为6.1;生根培养基为1/2WPM+IBA 0.20 mg·L-1+NAA 0.40 mg·L-1,生根率达95.2%,每株平均生根5.7条。经生根培养30 d和日光温室炼苗10 d后,试管苗移入泥炭和珍珠岩(1:1,V/V)混合基质中,移栽后的成活率达98%。该体系的建立为北美冬青规模化生产提供了技术平台。     

温度对桃离体花药散粉及花粉萌发的影响

以目前生产栽培较多的‘湖景蜜露’、‘霞晖6号’和‘白凤’3个桃品种为试材,连续2年调查了不同温度处理下花药失水率、花药散粉时间以及花粉离体萌发特性等变化。结果表明：桃花药于相对低温条件下散粉失水率较低,随散粉温度升高失水率相应上升;花药开裂所需时间与处理温度呈相反趋势;3个品种花粉离体萌发率随散粉温度的升高而下降。离体花药在超过30℃的温度条件下散出的花粉在萌发过程中出现花粉管变短、花粉瘪小的概率增多的现象,表明高温促使花药脱水和散粉加快,但降低了花粉活力。在桃树花期以及制备花粉时外界环境温度应控制在30℃以下。