Binding of the molecular chaperone αB-crystallin to Aβ amyloid fibrils inhibits fibril elongation.

The molecular chaperone αB-crystallin is a small heat-shock protein that is upregulated in response to a multitude of stress stimuli, and is found colocalized with Aβ amyloid fibrils in the extracellular plaques that are characteristic of Alzheimer's disease. We investigated whether this archetypical small heat-shock protein has the ability to interact with Aβ fibrils in vitro. We find that αB-crystallin binds to wild-type Aβ(42) fibrils with micromolar affinity, and also binds to fibrils formed from the E22G Arctic mutation of Aβ(42). Immunoelectron microscopy confirms that binding occurs along the entire length and ends of the fibrils. Investigations into the effect of αB-crystallin on the seeded growth of Aβ fibrils, both in solution and on the surface of a quartz crystal microbalance biosensor, reveal that the binding of αB-crystallin to seed fibrils strongly inhibits their elongation. Because the lag phase in sigmoidal fibril assembly kinetics is dominated by elongation and fragmentation rates, the chaperone mechanism identified here represents a highly effective means to inhibit fibril proliferation. Together with previous observations of αB-crystallin interaction with α-synuclein and insulin fibrils, the results suggest that this mechanism is a generic means of providing molecular chaperone protection against amyloid fibril formation.

光敏核不育水稻中光敏色素A mRNA的丰度分析及光敏色素A和B生物功能的分析

本文以光敏色素A (phyA)的特异性基因片段RPA3为探针，利用RNA斑点杂交的方法对光敏核不育水稻农垦58S及对照农垦58叶片中phyA mRNA的丰度进行了分析。结果显示：在育性转换敏感期，光周期处理O天时，农垦58S (NK 58S) phyA mR-NA的丰度比农垦58 (NK 58) phyA mRNA的高。光周期处理5天（雌雄蕊原基形成期）及10天（花粉母细胞形成期）时，短日照条件下(SD)，NK 58S phyA mRNA的丰度均比NK58高。进一步比较3天龄NK58S及NK58黄化苗中phyA基因表达的差异，发现NK58S phyA mRNA的丰度比NK58高，并且两品种均符合黄化苗中phyA对其mRNA丰度的负调控作用。这一结果进一步证实：甲基化水平低的NK58S phyA基因比NK58 phyA基因更活跃地表达，进而导致转录水平与翻译水平上的差异，最终参与调节NK 58S的育性转换。 另外，通过持续远红光和红光照射黄化水稻幼苗诱导叶绿素合成的实验，分析了NK58S与NK58之间光敏色素生物功能的差异。持续远红光高辐照度反应(FR-HIR)由phyA负责调节，持续红光高辐照度反应(R-HIR)由phyB负责调节。实验结果显示：持续FR使NK58S与NK58合成叶绿素的含量在12 h时达到最高，并且NK58中叶绿素合成的相对效应比NK585高。持续R使NK58S及NK58中叶绿素的含量在24小时连续处理下持续增加，而且在此时间进程中，NK58中叶绿素合成的相对效应也都比NK58S高。这些结果说明在NK58S和NK58中phyA和phyB均参与了叶绿素合成的调节，并且phyA，phyB在NK58S和NK58黄化苗转绿过程中的作用存在差异。

小麦春化相关基因的克隆及其功能分析

一． 小麦相关基因ver203F cDNA全序列克隆与功能分析 　　根据本实验室通过差异筛选技术克隆到的与春化相关的基因cDNA verc203的序列，设计PCR 5’端PCR引物，利用RACE（rapid amplification of cDNA ends）克隆策略，得到春化相关基因ver203基因的同源基因ver203F cDNA的3’端序列，长度为1,197bp。Northern分析表明ver203F全长约为1.5 kb，且其表达具有春化处理的特异性。根据3’RACE克隆的ver203F 3 ’端核苷酸序列设计了3’端PCR引物，利用5’RACE克隆到该基因的5’端片段，经DNASIS核酸分析软件分析将5’45RACE和3’RACE DNA序列拼接合并，得到ver203F全长cDNA，从TdT加尾5’末端到poly A全长为1,561 bp，5’端起始密码子ATG上游非编码区－1～－192共了192bp，终止密码子TGA到poly A的非编码区有253bp，cDNA编码区全长1,119 bp，推测编码373氨基酸残基。国际基因序列数据库检索表明该基因序列（GenBank/EMBL/DDBJ：AB012013）与大麦茉莉酸诱导基因有部分同源性。因上推测该基因在调控开花过程中可能参与茉莉酸介导的信号传导途径，ver203F作用的发挥可能需要其它蛋白的参与，或ver203F本身就是一个受体蛋白。 　　为了研究ver203F基因的功能，将通过3’RACE克隆到的ver203F 3’端序到分别构建正义和反义植物表达载体，通过花粉管通道法、农杆菌介导的叶圆片法以及农杆菌介导的真空转化法分别转化小麦、烟草和拟南芥菜。获得转基因植株后，PCR、DNA Dob Blot、Southern Blot分析以及GUS活性检测证明外源基因已整合到转基因植株中，并得到表达。在获得的小麦、烟草和拟南芥菜转基因植株中，它们开花时间都相应地推迟，表明正常植物体内该基因在控制营养生长向生殖生长的转变中起作用。ver203F可以影响小麦和拟南茶菜花序的发育，首先无论正义还是反义都使得花序的发育受到抑制，在小麦中表现为顶部小穗退化，在拟南芥菜中表现为顶花。其次在转化正义基因的转基因拟南芥菜中，观察到产生的顶花为对称的两朵或以对称的两朵顶花基部为生长点长出丛生花，这种对称花的麦型小麦小穗中小花的表型相类似，说明ver203F基因可能在小麦小花的发育过程中也起着重要作用。 二． 春化相关基因ver17在开花过程中功能的分析 以春化处理冬小麦（京冬1号）幼苗cDNA为材料，通过减法杂交与差异筛选得到春化相关cDNA克隆verc17。为了研究该基因的功能，以包含CaMV 35S启动子的pBI221为载体，将ver17cDNA片段分别从两个方向插入pBI221的BamH I－Sma I, Xba I－BamH I间，构建正义和反义表达质粒：p17S和p17X，通过花粉管通道法转化小麦。对T0和T1两代转基因小麦的观察发现，在转化反义基因p17X的转基因小麦首先表现为抽穗推迟，其次穗的顶部和基部小穗严重退化，另外还发现转化反义基因的小麦败育现象严重（主要是花粉败育），因此推测ver17基困能可具有以下几方面的特点：a．春化诱导型表达;b．促进植物开花;c．促进穗顶端和基部花的发育，减少其退化;d．影响雄蕊的发育。

Descriptions of larval, prejuvenile, and juvenile finescale menhaden (Brevoortia gunteri) (family Clupeidae), and comparisons to gulf menhaden (B. patronus)

Larval and juvenile development of finescale menhaden (Brevoortia gunteri) is described for the first time by using wild-caught individuals from Nueces Bay, Texas, and is compared with larval and juvenile development of co-occurring gulf menhaden (B. patronus). Meristics, morphometrics, and pigmentation patterns were examined as development proceeded. An illustrated series of finescale menhaden is presented to show changes that occurred during development. For finescale menhaden, transformation to the juvenile stage was completed by 17−19 mm standard length (SL). By contrast, transformation to the juvenile stage for gulf menhaden was not complete until 23−25 mm SL. Characteristics useful for separating larval and juvenile finescale menhaden from gulf menhaden included 1) the presence or absence of pigment at the base of the insertion of the pelvic fins; 2) the standard length at which medial predorsal pigment occurs; 3) differences in the number of dorsal fin ray elements; and, 4) the number of vertebrae.

Age and growth of the blue shark (Prionace glauca) in the North Atlantic Ocean

Age and growth estimates for the blue shark (Prionace glauca) were derived from 411 vertebral centra and 43 tag-recaptured blue sharks collected in the North Atlantic, ranging in length from 49 to 312 cm fork length (FL). The vertebrae of two oxytetracycline-injected recaptured blue sharks support an annual spring deposition of growth bands in the vertebrae in sharks up to 192 cm FL. Males and females were aged to 16 and 15 years, respectively, and full maturity is attained by 5 years of age in both sexes. Both sexes grew similarly to age seven, when growth rates decreased in males and remained constant in females. Growth rates from tag-recaptured individuals agreed with those derived from vertebral annuli for smaller sharks but appeared overestimated for larger sharks. Von Bertalanffy growth parameters derived from vertebral length-at-age data are L∞ = 282 cm FL, K = 0.18, and t0 = –1.35 for males, and L∞ = 310 cm FL, K = 0.13, and t0 = −1.77 for females. The species grows faster and has a shorter life span than previously reported for these waters.