The influence of temperature on chromosome elimination during embryo development in crosses involving Hordeum spp., wheat (Triticum aestivum L.) and rye (Secale cereale L.)

Summary Several interspecific and intergeneric crosses involving five Hordeum species, Triticum aestivum and Secale cereale were carried out to investigate the influence of two contrasting temperatures on chromosome elimination during embryo development. In four of the interspecific Hordeum crosses, chromosome elimination was significantly increased at the higher of the two temperatures, resulting in greater proportions of haploid plant progenies. However, there was no significant effect of temperature in the other interspecific cross between H. lechleri x H. bulbosum nor in the two intergeneric crosses between H. vulgare x S. cereale and T. aestivum x H. bulbosum whose progeny were exclusively hybrid and haploid, respectively.     

SDF-1 在乳腺癌患者血清中表达水平及临床意义

目的:分析SDF-1在乳腺癌患者外周血中的表达水平,探讨其临床意义。方法:Elisa法检测乳腺癌患者术前及术后血清SDF-1水平,分析其与乳腺癌临床病理特征的关系。结果:乳腺癌患者术前(69例)血清SDF-1水平明显高于正常对照组(20例)(6406.7±1302.5 pg/m L vs 5217.4±1225.7 pg/m L),有明显统计学差异(P<0.01),发生远处转移的乳腺癌患者(11例)血清SDF-1水平明显高于未发生转移者(58例)(7656.4±784.1 pg/m L vs 6169.7±1364.6 pg/m L),差异具有明显统计学意义(P<0.01)。ER及Her-2表达阳性乳腺癌的患者SDF-1水平较ER及Her-2表达阴性者低,差异亦有统计学意义(P<0.05)。结论:SDF-1可能是预测乳腺癌发生及远处转移的重要标志物。     

新选育饲草玉米品系饲用营养价值初步研究

对利用一年生大刍草和四倍体多年生大刍草分别与玉米杂交选育出的一年生饲草玉米(SC1)和多年生饲草玉米(SC3)生物产量和饲用营养成分进行分析,结果表明:SC1和SC3鲜草年产量分别达115 620kg/hm2、174 045kg/hm2,是普通玉米的4～6倍;SC3的粗蛋白质(CP)和无氮浸出物(NFE)含量最高,分别为17.57%、48.73%,粗纤维(CF)含量最低,为21.65%,其粗脂肪(EE)和灰分(CA)含量分别为4.30%和7.75%;SC1的营养成分含量分别为:(CP)14.73%、(CF)26.09%、(NFE)45.29%、(EE)4.78%和(CA)9.11%;化学营养类型分析表明SC1与SC3分别属NC型和N型,都是高产高饲用价值的新型饲草.     

转导引起基因重组的教学分析

转导引起基因重组的教学分析张霞朱开平（新疆石河子大学师范学院生化系,石河子８３２００３）ＡｎａｌｙｓｉｓｏｆＧｅｎｅｔｉｃＲｅｃｏｍｂｉｎａｔｉｏｎＴｈｒｏｕｇｈＴｒａｎｓｄｕｃｔｉｏｎＺｈａｎｇＸｉａＺｈｕＫａｉｐｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＢ...     

药物诱导玉米远缘杂种孤雌生殖获得异源种质纯系及其育种研究

药物诱导玉米远缘杂种（自３３０×ＤＰ）ＢＣ１孤雌生殖,可在早代（Ｐａ２）克服远缘杂种疯狂分离、遗传性不稳定问题。在２～３年内选育出优良的异源种质纯系５４０,并组配出优良杂交种遗单６号（５００３×５４０）。它的主要特点：大穗、高产、优质、抗病、抗倒伏、成熟后茎叶持绿。细胞学鉴定指出,纯系５４０的第２对同源染色体的一条染色体长臂和第５对同源染色体的长臂均显示异染色质末端带,这是二倍体多年生类玉米的带型特征,从而证明,５４０是具有二倍体多年生类玉米种质的纯系。药物诱导孤雌生殖技术为玉米远缘杂交育种开辟了广阔的前景     

Aeromonas piscicola sp. nov., isolated from diseased fish

Four Aeromonas strains (S1.2^T, EO-0505, TC1 and TI 1.1) isolated from moribund fish in Spain showed a restriction fragment length polymorphism (RFLP) pattern related to strains of Aeromonas salmonicida and Aeromonas bestiarum but their specific taxonomic position was unclear. Multilocus sequence analysis (MLSA) of housekeeping genes rpoD, gyrB, recA and dnaJ confirmed the allocation of these isolates to an unknown genetic lineage within the genus Aeromonas with A. salmonicida, A. bestiarum and Aeromonas popoffii as the phylogenetically nearest neighbours. Furthermore, a strain biochemically labelled as Aeromonas hydrophila (AH-3), showing a pattern of A. bestiarum based on 16S rDNA-RFLP, also clustered with the unknown genetic lineage. The genes rpoD and gyrB proved to be the best phylogenetic markers for differentiating these isolates from their neighbouring species. Useful phenotypic features for differentiating the novel species from other known Aeromonas species included their ability to hydrolyze elastin, produce acid from l-arabinose and salicin, and their inability to produce acid from lactose and use l-lactate as a sole carbon source. A polyphasic approach using phenotypic characterization, phylogenetic analysis of the 16S rRNA gene and of four housekeeping genes, as well as DNA–DNA hybridization studies and an analysis of the protein profiles by MALDI-TOF-MS, showed that these strains represented a novel species for which the name Aeromonas piscicola sp. nov. is proposed with isolate S1.2^T (=CECT 7443^T, =LMG 24783^T) as the type strain.     

Similarity landscapes: A way to detect many structural and sequence motifs in both introns and exons

When investigators undertake searches of DNA databases, they normally discard large numbers of alignments that demonstrate very weak resemblances to each other, retaining only those that show statistically significant levels of resemblance. We show here that a great deal of information can be extracted from these weak alignments by examining them en masse. This is done by building three-dimensional similarity landscapes from the alignments, landscapes that reveal whether an unusual number of individually nonsignificant alignments tend to match up to a particular region of the query sequence being searched. The power of the search is increased by the use of libraries consisting entirely of introns or of exons. We show that (1) similarity landscapes with a variety of features can be generated from both intron and exon libraries, using introns or exons as query sequences; (2) the landscape features are real and not a statistical artifact; (3) well-known protein motifs used as query sequences can generate various landscape features; and (4) there is some evidence for resemblances between short regions of sequence carried by introns and exons. One possible interpretation of these results is that both introns and exons may have been built up during their evolution from short regions of sequence that as a result are now widely distributed throughout eukaryotic genomes. Such an interpretation would imply that these short regions have common ancestry. Alternatively, the wide sharing of short pieces of DNA may reflect regions with particular structural properties that have arisen through convergent evolution. The similarity-landscape approach can be used to detect such widespread structural motifs and sequence motifs in the genome that might be missed by less-global searches. It can also be used in conjunction with algorithms developed for detecting significant multiple alignments by isolating promising subsets of the databases that can be examined in more detail.Correspondence to: C. Wills     

Analysis of the large bowel microbiota of colitic mice using PCR/DGGE

AIM: To test combined polymerase chain reaction amplification of 16S rRNA gene sequences and denaturing gradient gel electrophoresis (PCR/DGGE) as an analytical method to investigate the composition of the large bowel microbiota of mice during the development of colitis. METHODS AND RESULTS: The colonic microbiota of formerly germfree interleukin 10 (IL-10)-deficient mice that had been exposed to the faecal microbiota of specific pathogen-free animals was screened using PCR/DGGE. The composition of the large bowel microbiota of IL-10-deficient mice changed as colitis progressed. DNA fragments originating from four bacterial populations ('Bacteroides sp.', Bifidobacterium animalis, Clostridium cocleatum, enterococci) were more apparent in PCR/DGGE profiles of colitic mice relative to non-colitic animals, whereas two populations were less apparent (Eubacterium ventriosum, Acidophilus group lactobacilli). Specific DNA:RNA dot blot analysis showed that bifidobacterial ribosomal RNA (rRNA) abundance increased as colitis developed. CONCLUSIONS: PCR/DGGE was shown to be an effective method to demonstrate changes in the composition of the large bowel microbiota of mice in relation to progression of inflammatory disease. The intensity of staining of DNA fragments in DGGE profiles reflected increased abundance of bifidobacterial rRNA in the microbiota of colitic animals. As bifidobacterial fragments in PCR/DGGE profiles generated from microbiota DNA showed increased intensity of fragment staining, an increase in bifidobacterial numbers in colitic mice was indicated. SIGNIFICANCE AND IMPACT OF THE STUDY: PCR/DGGE analysis demonstrated an altered composition of the large bowel microbiota of colitic mice. This work will allow specific groups of bacteria to be targeted in future research concerning the pathogenesis of colitis.