论Paracarinachitids

研究证明Paracarinachitids的外骨骼都不是由8个骨板组成,骨片具有清楚的微层构造,表明它们是由叠覆的生长层组成,每个生长节上有一个小刺,在顶端下侧面前端都有肾形缺凹。同一标本上存在顶端部的融合和远顶端部的分节彼此递交的现象表明这种表象上的差异是后期次生磷灰石包裹或腐蚀的结果;其下侧缘融合和下侧面无缝隙的现象说明将Paracarinachites spinus的骨片分成头板、中间板和尾板是没有根据的。骨片表面存在的针状体是成岩作用的产物,它是粘土矿物和磷酸盐针状结晶体而不是多板纲的骨针。凡此强有力地说明Yangtzechiton是Paracarinachites的晚出同义名。根据形态功能、组织结构,特别是叠覆状排列的骨片和孤立的生长节等特征,paracarinachitids 可能与zhijinitids有密切关系,但两者是否同源尚缺少进一步的证据、据此,笔者认为将paracarinachitids 暂置于分类位置未定的具骨片后生动物较妥。     

外显子与内含子序列分维的双碱基研究

引入碱基间的关联,研究了外显子和内含子序列以双碱基为单位的分维,我们发现在这种情况下,外显子和内显子序列在短程和中程存在自相似性并分别定义了这两个区域的分维。结果表明,短程的分维值Ｄｇ一般比中程的Ｄｍ大,外显子的两个分维值比内含子大。我们改变双联体的位相而分维却不变,这反映出在双联体基础上,外显子的不规则性大于内含子,短程的不规则性大于中程,外显子和内含子序列对以２为周期的结构没有位相的特异性。     

Comparative bioinformatics analysis and abiotic stress responses of expansin proteins in Cucurbitaceae members: watermelon and melon

Protoplasma - Watermelon and melon are members of the Cucurbitaceae family including economically significant crops in the world. The expansin protein family, which is one of the members of the...     

Vegetable biology and breeding in the genomics era

Vegetable crops provide a rich source of essential nutrients for humanity and represent critical economic values to global rural societies. However, genetic studies of vegetable crops have lagged behind major food crops, such as rice, wheat and maize, thereby limiting the application of molecular breeding. In the past decades, genome sequencing technologies have been increasingly applied in genetic studies and breeding of vegetables. In this review, we recapitulate recent progress on reference genome construction, population genomics and the exploitation of multi-omics datasets in vegetable crops. These advances have enabled an in-depth understanding of their domestication and evolution, and facilitated the genetic dissection of numerous agronomic traits, which jointly expedites the exploitation of state-of-the-art biotechnologies in vegetable breeding. We further provide perspectives of further directions for vegetable genomics and indicate how the ever-increasing omics data could accelerate genetic, biological studies and breeding in vegetable crops.

     

EFFECTS OF HELPER PROTEINS ENCODED BY p19 AND orf1-orf2 GENES ON Cyt1Aa PROTEIN EXPRESSION IN ACRYSTALLIFEROUS STRAIN OF BACILLUS THURINGIENSIS

A series of plasmids were constructed to examine the effects of p19 and orf1‐orf2 genes from Bacillus thuringiensis on Cyt1Aa synthesis and inclusion formation. The plasmids expressed the cyt1Aa gene along with either p19 or orf1‐orf2, or each of them coordinatively with p20 in the acrystalliferous strain of B. thuringiensis subsp. israelensis 4Q7. No effect on the expression of Cyt1Aa protein was found when P19 or Orf1‐Orf2 co‐expressed with Cyt1Aa. However, when including p20 gene, the constructs with p19 or orf1‐orf2 gene produced lower yield of Cyt1Aa proteins than without p19 or orf1‐orf2 gene. Electron microscopy observation and bioassay showed that P19 and Orf1‐Orf2 have no influence on the crystal size and toxicity of Cyt1Aa protein. It is presumed that P19 and Orf1‐Orf2 might have negative effects on Cyt1Aa synthesis in B. thuringiensis.     

海甘蓝种子成熟过程中脂肪酸含量以及脱落酸和山梨醇的效应

海甘蓝种子在成熟过程中,棕榈酸、硬脂酸和亚麻酸的含量不断下降,而二十碳烯酸和芥酸的含量呈上升趋势。选用开花后２５～２７ｄ的海甘蓝幼胚分别在含不同浓度的ＡＢＡ或高渗透剂的培养基中培养１～３ｄ,发现其各种脂肪酸的变化趋势和种子自然成熟过程中脂肪酸的变化相似,说明ＡＢＡ或高渗透剂可能是种子成熟过程中各种脂肪酸合成和相互转化所需的条件。     

大麦G－带变动性以及与染色粒的一致性分析

以大麦为材料,进行了Ｇ－带带纹变动性分析以及Ｇ－带与减数分裂粗线期染色粒的比较。有丝分裂早中期至中期两个不同时期Ｇ－带带纹总数减少３６％,染色体组的绝对长度缩短２５％,带数减少的幅度大于染色体长度缩短的幅度。染色体组中每条染色体之间带纹减少的比例不尽相同,变幅在０．２９－０．５０之间。不同染色体绝对长度减少的幅度在０．２７－３．７０μ之间。从早中期至中期,每单位染色体绝对长度带数具相对减少的趋势。选择第６染色体进行的比较显示,减数分裂的染色粒与有丝分裂的Ｇ－带带纹之间具有很好的对应关系,Ｇ－带带纹和染色粒间的数目、位置和着色程度上都具一致性。对Ｇ－带性质和植物中Ｇ－带的应用等问题进行了讨论。     

An efficient synthesis of methyl tetra-o-hexyl gentiooctaoside, an octaosyl analogue of ANP receptor antagonist HS-142-1

Methyl

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, a 3-O hexyl analogue of the octaosyl component of fungal lipooligosaccharide HS-142-1, was stereo- and regioselectively synthesized as a potent antagonist for the tetrameric atrial natriuretic peptide (ANP) receptors.