夏眠对刺参(Apostichopus japonicus (Selenka))能量收支的影响

夏眠是刺参最重要的生理特征;水温升高是其夏眠的主要诱发因子,而夏眠的临界温度与刺参体重密切相关。为揭示刺参夏眠对其能量利用对策的影响,测定了2种体重规格(134.0±13.5)g和(73.6±2.2)g刺参在10、15、20、25℃和30℃5个温度梯度下的能量收支。结果表明,温度和体重及其交互作用对刺参能量的摄入均有显著影响;而温度是影响其摄食能分配的主要因素。研究发现,刺参在非夏眠期、夏眠临界期和完全夏眠期的能量利用对策有所不同:在非夏眠期,刺参摄食能支出的最大组分是粪便能,占摄食能的比例超过50%,其次为呼吸耗能,占19.8%～39.4%,而生长能和排泄能占的比例较小,分别为5.7%～10.7%和2.9%～3.7%;在夏眠临界温度下,呼吸和排泄耗能占摄食能的比例均显著增大(分别为88.3%和13.6%),而生长能所占比例降为负值(-55.3%),刺参表现为负生长;而在夏眠期,刺参的摄食能和排粪能为零,为维持其基本生理活动,不得不动用以往贮存于体内的能量,消耗于呼吸和排泄等生理过程,供维持生命之用。总之,从能量生物学的角度看,夏眠的主要生态学意义在于刺参长时间处于相对高温环境,进而导致摄食受阻条件下的一种能量节约方式。     

柑橘凤蝶蛹发声器的显微结构及防御作用(英文)

【目的】动物界存在多种用于对抗捕食者的防御机制。一些鳞翅目昆虫的蛹在受到机械刺激时会发出蠕动的声音。【方法】在扫描电镜下对柑橘凤蝶Papilio xuthus蛹的发声器形态特征进行观察,并使用Audacity软件对捕获的声音进行特征分析。【结果】柑橘凤蝶蛹在腹部第4-5节和第5-6节之间的节间膜上存在发声器,有规律地发出嘶嘶声。发声器由多层甲壳素构成的刮器和板组成,刮器和板上有 50~90个突起。当蛹的腹部被寄生蜂触角刺激30 s以上时,刮器和板会迅速相互摩擦,腹部反复摆动发出声音。蛹发出的声音是由一系列每2 000~3 000 ms发生3次的短脉冲组成的。频带很宽,主要分布在5~20kHz范围内。新鲜蛹和越冬蛹的活性不同,声强也不同。【结论】本研究首先描述了柑橘蝴蝶蛹发声器的结构,结果支持了一些蝴蝶蛹对寄生生物进化出一种特殊的防御机制(声学防御)的假说。此外,通过比较两种生境的柑橘凤蝶蛹的声波特征,我们提出了同一物种在不同地理区域可以产生方言的假说。 关键词:     

Characterization of the mammalian miRNA turnover landscape

Steady state cellular microRNA (miRNA) levels represent the balance between miRNA biogenesis and turnover. The kinetics and sequence determinants of mammalian miRNA turnover during and after miRNA maturation are not fully understood. Through a large-scale study on mammalian miRNA turnover, we report the co-existence of multiple cellular miRNA pools with distinct turnover kinetics and biogenesis properties and reveal previously unrecognized sequence features for fast turnover miRNAs. We measured miRNA turnover rates in eight mammalian cell types with a combination of expression profiling and deep sequencing. While most miRNAs are stable, a subset of miRNAs, mostly miRNA*s, turnovers quickly, many of which display a two-step turnover kinetics. Moreover, different sequence isoforms of the same miRNA can possess vastly different turnover rates. Fast turnover miRNA isoforms are enriched for 5′ nucleotide bias against Argonaute-(AGO)-loading, but also additional 3′ and central sequence features. Modeling based on two fast turnover miRNA*s miR-222-5p and miR-125b-1-3p, we unexpectedly found that while both miRNA*s are associated with AGO, they strongly differ in HSP90 association and sensitivity to HSP90 inhibition. Our data characterize the landscape of genome-wide miRNA turnover in cultured mammalian cells and reveal differential HSP90 requirements for different miRNA*s. Our findings also implicate rules for designing stable small RNAs, such as siRNAs.     

A comprehensive analysis of root morphological changes and nitrogen allocation in maize in response to low nitrogen stress

The plasticity of root architecture is crucial for plants to acclimate to unfavourable environments including low nitrogen (LN) stress. How maize roots coordinate the growth of axile roots and lateral roots (LRs), as well as longitudinal and radial cell behaviours in response to LN stress, remains unclear. Maize plants were cultivated hydroponically under control (4 mm nitrate) and LN (40 μm ) conditions. Temporal and spatial samples were taken to analyse changes in the morphology, anatomical structure and carbon/nitrogen (C/N) ratio in the axile root and LRs. LN stress increased axile root elongation, reduced the number of crown roots and decreased LR density and length. LN stress extended cell elongation zones and increased the mature cell length in the roots. LN stress reduced the cell diameter and total area of vessels and increased the amount of aerenchyma, but the number of cell layers in the crown root cortex was unchanged. The C/N ratio was higher in the axile roots than in the LRs. Maize roots acclimate to LN stress by optimizing the anatomical structure and N allocation. As a result, axile root elongation is favoured to efficiently find available N in the soil.     

妊娠及哺乳期母鼠注射麻黄素对仔鼠肝组织TGF-β1和c-Fos表达的影响

为探讨妊娠及哺乳期小鼠(Mus musculus)注射麻黄素后对仔鼠肝组织TGF-β1及c-Fos表达的影响,将30例受孕小鼠随机分为对照组和麻黄素组。麻黄素组小鼠从受孕第3天开始连续腹腔注射6.0 g/L麻黄素溶液直到分娩后15天,每天注射2次,每次0.2 ml;对照组每天2次注射等量的生理盐水。称量检测仔鼠体重和肝重的变化,同时用免疫组织化学方法检测仔鼠肝组织中细胞生长因子TGF-β1和原癌基因c-Fos蛋白表达的变化。麻黄素组仔鼠体重与对照组相比显著降低(P0.05或P0.01),肝体比与对照组相比明显升高(P0.05或P0.01),仔鼠肝组织中TGF-β1和c-Fos蛋白阳性表达强度与对照组相比有不同程度的增强(P0.05或P0.01),表明妊娠及哺乳期小鼠注射麻黄素影响仔鼠肝的发育。     

岑溪药用野生稻高效内生固氮菌分离及促生特性

【目的】以广西岑溪市野生稻保护区的药用野生稻为材料,分离纯化内生细菌,筛选固氮酶活性较高和对作物促生效果较好的菌株。【方法】利用乙炔还原法检测固氮酶活性,采用SDS-PAGE全细胞蛋白电泳和IS-PCR指纹图谱技术对分离到的固氮菌进行聚类。利用16S rRNA基因和nifH基因确定其系统发育地位。采用钼锑抗比色法、Salkowski比色法和CAS检测法分别测定菌株溶磷性、生长素的分泌能力和产铁载体能力。通过平板和盆栽试验检测其对水稻的促生作用。【结果】共分离得到35株内生固氮菌,分为6个类群。其中CX24固氮酶活性最高,经鉴定属于Klebsiella variicola,其固氮酶活性为298.64 μmol/(L·h),为参比模式菌株DSM15968的9倍。另外该菌株还具有较高的溶磷性、分泌生长素和产铁载体能力,能够有效地促进水稻的萌发和生长。【结论】菌株CX24属于Klebsiella variicola,是一株高效内生固氮菌,具有很好的生产应用前景。     

葡萄半不育花粉粒形态和细胞学观察及相关基因表达分析

以葡萄品种‘魏可’(可育)及其自交后代单株‘魏可实生-3’和‘魏可实生-12’以及品种‘钟山红’(雄性不育)为材料,对花器官特征、花粉萌发率、花粉粒形态以及小孢子发育过程的细胞学特征进行观察,并对绒毡层发育相关基因(DYT1、TDF1和MYB4)的表达进行分析,以初步鉴定葡萄半不育单株的不育特征,揭示花粉败育与基因调控的关系。结果显示:(1)‘魏可实生-3’和‘魏可实生-12’的花粉萌发率均在10%左右,属于半不育花粉;其雄蕊主要特征为花丝卷曲,花丝短于花柱,花药内花粉量少,花药中既有正常长球形花粉粒也有异常近球形花粉粒。(2)‘魏可实生-3’、‘魏可实生-12’没有明显的药室壁结构,小孢子母细胞稀少、疏松;‘魏可实生-3’双核期绒毡层未完全降解,绒毡层细胞中的营养物质滞留没有及时供应小孢子的发育,致后期部分小孢子败育;‘魏可实生-12’绒毡层细胞在单核早期就大部分降解而导致营养供应异常,使部分小孢子败育。(3)在减数分裂期,‘魏可’的绒毡层发育相关基因DYT1和TDF1的表达均最高,MYB4最低,‘钟山红’的3个基因的表达与‘魏可’相反,‘魏可实生-3’和‘魏可实生-12’的表达水平均在‘魏可’与‘钟山红’之间;单核早期以后,3个基因在‘魏可’的表达一直均较低,钟山红’的DYT1基因表达一直最高,其余2个基因均在最低水平,而‘魏可实生-3’的TDF1、MYB4基因在单核早期表达量最高,‘魏可实生-12’的TDF1在双核期表达量最高。研究表明,‘魏可实生-3’的花粉败育发生在单核晚期至双核期,‘魏可实生-12’的花粉败育发生在单核早期;部分药室绒毡层的异常降解,小孢子发育营养供应不均衡可能是导致其花粉半不育发生的原因;‘魏可实生-3’的绒毡层延迟降解与减数分裂期DYT1基因的表达量不足、单核期TDF1基因的过量表达以及MYB4基因在单核期的异常表达有关,而‘魏可实生-12’的绒毡层提前降解与减数分裂期DYT1基因的表达量不足而MYB4基因过量表达,以及双核期TDF1基因过量表达有关。     

中国毛茛科翠雀属的分类学研究(八):短尾翠雀花的名实订正

发现近来根据云南西北部丽江标本描述的毛茛科短尾翠雀花(Delphinium brachyurum W. T. Wang)与此前根据该地标本描述的丽江翠雀花(D. likiangense Franch.)属于同一种植物,故将前者处理为后者的异名。