Classification of protein quaternary structure by functional domain composition

Background  

The number and the arrangement of subunits that form a protein are referred to as quaternary structure. Quaternary structure is an important protein attribute that is closely related to its function. Proteins with quaternary structure are called oligomeric proteins. Oligomeric proteins are involved in various biological processes, such as metabolism, signal transduction, and chromosome replication. Thus, it is highly desirable to develop some computational methods to automatically classify the quaternary structure of proteins from their sequences.     

常染色体显性遗传非综合征性耳聋致病基因定位研究

耳聋具有高度的遗传异质性, 迄今已定位了51个常染色体显性遗传非综合征型耳聋(autosomal dominant non-syndromic sensorineural hearing loss, DFNA)基因位点, 20个DFNA相关基因被克隆。文章收集了一个DFNA巨大家系, 家系中有血缘关系的家族成员共170人, 对73名家族成员进行了详细的病史调查、全身检查和耳科学检查, 提示39人有不同程度的迟发性感音神经性听力下降, 未见前庭及其他系统的异常。应用ABI公司382个常染色体微卫星多态标记进行全基因组扫描连锁分析, 将该家系致聋基因定位于14q12-13处D14S1021-D14S70之间约7.6 cM (3.18 Mb)的区域, 最大LOD值为6.69 (D14S1040), 与已知DFNA9位点有4.7 cM (2.57 Mb)的重叠区, DFNA9致病基因COCH位于重叠区域内。下一步拟进行COCH基因的突变筛查, 以揭示该家系耳聋的分子致病机制。     

开花对两种杓兰光合作用和同化产物分配的影响

对同一生境下黄花杓兰（Cypripedium flavum）和西藏杓兰（Cypripedium tibeticum）开花株与非开花株的气体交换、光系统Ⅱ实际光化学效率（φPSⅡ）和^14C分配进行了测定,目的在于了解开花对杓兰光合作用以及同化产物分配的影响。结果表明这两种杓兰开花均能通过提高电子传递速率来提升植株的光合作用。相对于黄花杓兰,西藏杓兰开花显著提高植株的呼吸速率,以致其最大净光合速率（Amax）的提升不显著。两种杓兰的花和地下部分（包括根状茎和芽）在同化产物分配上存在竞争关系,因而开花减少了同化产物向植株地下部分的分配。     

中国虎耳草属(虎耳草科)二新种————班玛虎耳草和丁青虎耳草

记载了中国虎耳草属Saxifraga二新种, 即班玛虎耳草S. banmaensis J. T. Pan和丁青虎耳草S. dingqingensis J. T. Pan。其中, 班玛虎耳草仅见于青海班玛, 与小伞虎耳草S. umbellulata Hook. f. &; Thoms.近缘, 但其萼片先端具软骨质短尖头, 花瓣线形, 非提琴状长圆形至提琴形, 基部无爪, 可资区别。丁青虎耳草见于西藏丁青, 与近加拉虎耳草S. llonakhensis W. W. Smith相似, 但其萼片3脉, 于先端汇合成1疣点, 花瓣具8痂体和4-5脉, 基部截形或近耳形, 可以区别。此两种均系中国特有种, 隶属于莲座状亚组subsect. Rosulares Gornall。     

露蕊乌头(毛茛科)不同海拔居群的传粉生态学

对青藏高原东北部两个不同海拔地点（互助,2460m和海北,3200m）的露蕊乌头Aconitum gymnandrum的传粉生态学进行了比较研究。研究结果表明高海拔居群的单花花期、雄性期持续时间、雌性期持续时间比低海拔长。露蕊乌头不存在无融合生殖现象,尽管高度自交亲和,但产生种子必须依赖传粉媒介。熊蜂是露蕊乌头的主要传粉昆虫,两个居群均存在传粉限制。熊蜂取食花蜜为主,在同一个花序上的访问顺序以由下向上为主,但在互助居群和海北居群有3．9％和2．7％的访花是由上向下进行的。统计发现有37．7％和29．3％的访问行为发生在同一植株内;因此,同株异花传粉造成的自交在露蕊乌头中仍然不能避免。低海拔居群的熊蜂种类和访花频率均高于高海拔居群,但自然状态下两个居群的结实率并没有显著差异。高海拔露蕊乌头居群可能具有较长的柱头持续时间,从而补偿了由于访花频率低带来的结实率降低。     

Response of physiologic metabolism and cell structures in mango fruit to exogenous methyl salicylate under low-temperature stress

We explored the effects of exogenous methyl salicylate (MeSA) on the development of chilling injury symptom, and the structure and composition of the pericarp, in mango ( Mangifera indica L. cv. 'Red 6') fruit under low-temperature stress using histochemical analysis and scanning electron microscopy together with Fourier transform infrared (FTIR) analysis. The results indicated that chilling injury symptom was remarkably limited in the fruit treated with MeSA at 0.1 m M as compared to the 5°C control, demonstrating the positive effects of MeSA in reducing chilling injury of mango fruit in low-temperature storage. In MeSA-treated fruit, the pericarp wax surface showed many cracks, and exocarp cells exhibited normal separation. The cell wall of exocarp contained lower amounts of pectic substances, aliphatics and phenolics in MeSA-treated fruit. In addition, MeSA-treated fruit contained more esterified substances and less carboxylate and carboxyl substances. Our work revealed the importance of MeSA in enhancing fruit tolerance to low-temperature stress and suggested a contribution of cellular structure and composition to this effect, which has not been reported previously.     

Cytokinin affects circadian-clock oscillation in a phytochrome B- and Arabidopsis response regulator 4-dependent manner

In higher plants, many developmental processes, such as photomorphogenesis and flowering, are coregulated by light and the phytohormone cytokinin. Interactions between light and cytokinin pathways are presumably mediated by common signaling intermediates. However, the molecular mechanism of these interactions remains unclear. Here, we report that cytokinin specifically induces the expression of the Arabidopsis circadian oscillator genes LATE ELONGATED HYPOCOTYL ( LHY ) and CIRCADIAN CLOCK-ASSOCIATED 1 ( CCA1 ) but represses the expression of TIMING OF CAB EXPRESSION 1 in a light-dependent manner. Consistent with these observations, cytokinin causes a shifted phase of the circadian clock. Mutant studies showed that the altered clock oscillation modulated by cytokinin is dependent on phytochrome B ( PHYB ) and Arabidopsis RESPONSE REGULATOR 4 ( ARR4 ). Whereas overexpression of LHY or CCA1 renders plants slightly more sensitive to cytokinin, phyB and a lhy/cca1 double mutant are less sensitive to the hormone. These results suggest that cytokinin affects the circadian clock oscillation in a PHYB - and ARR4 -dependent manner and that cytokinin signaling is also regulated by light-signaling components, including PHYB , LHY and CCA1 . Therefore, phyB, ARR4 and the circadian oscillator may function as signaling intermediates to integrate light and cytokinin pathways.     

Molecular Evolution of Prolactin Gene Family in Rodents

In this study, we identified two novel members of prolactin gene family in rat by blast searches against the published genomic database. A further analysis showed that gene duplications leading to PRL gene family in rodents occurred after rodents diverged from other mammals. Major reorganization of the gene loci in rodents was largely completed before the split of rat and mouse. But PL-I and PL-II genes are the exceptions, which have clustered in a species-specific manner in the phylogenetic tree. By combining results from gene conversion testing, relative chromosomal location comparison and estimated time for gene duplication, we believe that rodent PL-I and PL-II genes are species-specific and are the results of serial duplications which occurred after the divergence of mouse and rat. Our analysis also reveals that continual gene duplication and divergence occurred during the evolution of rodent PRL gene family.     

江西九连山常绿阔叶林主要树种叶建成消耗的比较

叶建成消耗（或叶构建消耗）是指构建单位质量（面积）叶片所需要的葡萄糖当量,是植物碳收获过程中必要的成本投资．反映植物在叶片水平上的能量和碳分配策略。基于热值、灰份含量、叶氮含量和比叶面积的测定,估算了江西九连山常绿阔叶林16个主要树种的叶建成消耗,分析比较了不同树种、不同叶寿命、比叶面积和冠层不同部位对叶建成消耗的影响。结果表明,热值组分的变化对单位质量叶建成消耗的影响最大;树种间单位质量叶建成消耗的差异不大（变化率仅3％～6％）,但其单位面积叶建成消耗则存在显著差异（变化率达27％～28％）;热值和单位质量叶建成消耗与比叶面积密切相关,而比叶面积随取样高度呈显著的降低趋势,最终导致热值及单位质量和单位面积的叶建成消耗均随取样高度呈显著的增加趋势。研究结果指出：（1）较高的叶建成消耗是由于植物叶片内含有较高能量投资的化学组分;（2）叶建成消耗和比叶面积随取样高度的变化综合反映了植物对光照和水分资源垂直梯度变化的可塑性适应。     

温带半干旱地区一年生植物种子的萌发特性

在实验室条件下研究了中国温带半干旱地区科尔沁沙地的23种1年生植物的种子萌发特性（新采集种子、冷藏和干藏种子）.大籽蒿、虎尾草、冠芒草、沙蓬和地锦的新种子萌发率达90%左右,11种植物新种子萌发率均低于70%,说明这些植物的新种子具有或多或少的休眠属性.经过150d的冷干藏后,大籽蒿、虎尾草萌发率保持在90%以上,说明这两种植物完全没有休眠机制;冠芒草、沙蓬和地锦的种子萌发率下降较多,可能是储藏的环境条件导致的2次休眠现象;冷藏和干藏处理均能使绿珠藜、毛马唐、细叶益母草、雾冰藜、金狗尾草、苋菜、马齿苋、碱地肤和水稗草的种子在生长季开始时完成生理后熟,萌发率达到80%以上;干藏有利于促进毛马唐、细叶益母草、马齿苋和鹤虱的种子成熟,冷藏有利于促进绿珠藜和金狗尾草的种子成熟;黄蒿、灰绿藜、画眉草和烛台虫实在不同处理下的萌发率都比较低,说明种子内在生理休眠作用较强,具有减少种子一次性萌发数量的风险分摊策略.大多数1年生植物均能在较短时间内达到最终萌发率的90%,表现出迅速萌发的特性;黄蒿、灰绿藜、碱地肤和沙蓬种子则在不同处理中表现出延长萌发时间的策略来适应半干旱地区不确定的环境条件.最后,探讨了几种主要1年生植物的种子萌发对策与其对环境适应机制之间的关系.