trnL内含子及trnL—trnF间隔区序列在木兰科系统发育研究中的应用

通过木兰科29个种的trnL基因内含子的525个碱基序列及21个种的trnL-trnF基因间隔区的370个碱基序列测定和分析,构建的严格一致性树建议：（1）含笑属为相对一致的单系类型;（2）玉兰亚属的几个种形成一个单系类群,与木兰亚属的几个种无共衍位点;（3）木莲属为一个相对保守的类群,种间碱基差异很小。碱基位点差异分析表明：含笑和野含笑的trnL序列相对鹅掌揪有3个位点的变异和一个简单重复序列的插入;鹅掌揪的trnL-trnF序列与GenBank(AF040679)中已注册的序列有3个位点的差异。两个严格一致性树的CI值高达0．978和0．913,说明trnL内含子和trnL-trnF间隔区序列的平行演化在木兰冬这几个属间发生频率非常氏,只适于木兰科高等级的（属以上）的系统研究     

Phylogeny of subsect. Meleuphorbia (A. Berger) Pax & Hoffm. (Euphorbia L.) reflects the climatic regime in South Africa

The nuclear ITS region and four noncoding cpDNA regions were directly sequenced to reconstruct the phylogeny of subsect. Meleuphorbia (Euphorbia L.), which is endemic to South Africa. Sequence polymorphism within cpDNA regions was too low to permit phylogenetic analyses. Large deletions including the ctp2-atpB proximal promoter in the atpB-rbcL IGS were found in two individuals. Phylogeny of subsect. Meleuphorbia was reconstructed using nrITS sequence data. The two resulting major clades are consistent with the geographic distribution of the investigated taxa. Plants distributed in the winter rainfall area in the Little Karoo form one clade, plants growing in the Great Karoo with predominant summer rainfall form the other. Subsect. Meleuphorbia is not monophyletic, because members of subsect. Anthacantha are clustered within the meleuphorbias. Both share functional unisexuality, form angled stems and the key character of Anthacantha (inflorescence spines) occurs as a transitional stage in form of persistent peduncles in Meleuphorbia.     

PCR amplification of intergenic spacers in the ribosomal DNA of Drosophila melanogaster reveals high levels of turnover in length and copy-number of spacers in geographically separated populations

A recently described PCR-based method for the analysis of intergenic spacer (IGS) length variation in the ribosomal (r) DNA of Drosophila melanogaster was used to analyse the distribution of IGS length variants in the rDNA of a number of recently collected D. melanogaster populations. One group of populations, from Europe and North Africa, was shown to have low intrapopulation IGS length variation following maintenance of massed populations in the laboratory for an extended period. However, a greater degree of IGS profile variability was detected at a number of levels in the majority of laboratory-maintained isofemale lines from two of these populations plus a second group of populations which were collected more recently from the eastern coast of Australia; all of which were immediately divided into isofemale lines following collection. Interestingly, PCR analysis of pooled DNA extracts from 30 individuals of either sex showed almost identical PCR profiles from each of the Australian populations. These preliminary results are discussed with regard to the possible combinations of forces (natural selection, neutral drift and genomic molecular drive) on the patterns of IGS length variation.     

Complete genome sequencing and analysis of an anti-tumor Newcastle disease virus strain

HBNU/LSRC/F3, a Newcastle disease virus (NDV) strain stored in our lab, exhibited an anti-tumor ability in our previous studies. Nonetheless, very little is known about its genome sequence, which is vital for further study. Here, the complete HBNU/LSRC/F3 genome was fully sequenced and compared with other NDV sequences. Its genome contained 15,192 nucleotides (nt) consisting of two termini and six genes in the following order: 3′-Le-NP-P-M-F-HN-L-Tr-5′. Phylogenetic analysis indicated that this NDV strain belonged to the Class II genotype IX group. A multibasic amino acid (aa) sequence was found at the cleavage site (¹¹²RRQRR↓F¹¹⁷) within the fusion (F) protein, and a 6 nt insertion was present in the 5′ non-coding region of the NP gene. The whole genome sequence was highly similar to other genotype IX NDV genomes reported in China. Overall, this study provides insight into the sequence characteristics of genotype IX NDVs, which will be useful for subsequent investigations.     

Identification ofArmillaria species from hokkaido by analysis of the intergenic spacer (IGS) region of ribosomal DNA using PCR-RFLP

The intergenic spacer (IGS) region, which is located between the 3′ end of 26S ribosomal DNA (rDNA) and the 5′ end of 5S rDNA, of sixArmillaria species from Hokkaido was investigated using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP). Restriction with onlyAlu I could distinguishA. mellea subsp.nipponica from the other species. WithAlu I andDde I,A. ostoyae andA. gallica could be distinguished from the other species. Digestion withAlu I resulted in two patterns (types A and B) ofA. singula and three patterns (types A, B, and C) ofA. jezoensis. One pattern (type B) of the former species and two patterns (types B and C) of the latter species were each different from those of the other species.Armillaria sinapina gave only oneAlu I digestion pattern, which was identical to that ofA. jezoensis (type A) andA. singula (type A). However, by digestion withDde I,A. singula (type A) could be distinguished fromA. jezoensis (type A) andA. sinapina.     

Molecular structure of the Frankia spp. nifD—K intergenic spacer and design of Frankia genus compatible primer

The nifD—K intergenic spacer (IGS) of ArI3 and ACoN24d were found to have a length 265 and 199 nucleotides, respectively. They are markedly less conserved than the two neighbouring genes and have, in some instances, a repeated structure reminiscent of an insertion event The repeated sequence and the IGSs have no detectable homology with sequences in DNA databanks. The IGS has a stem-loop structure with a low folding energy, lower than that between nifH and nifD. No convincing alignment of IGS sequences could be obtained among Frankia strains. Only between ACoN24d and ArI3, which belong to the same genomic species, was the alignment good enough to permit detection of a doubly repeated structure. No promoter could be detected in the IGSs. The putative nifK open reading frame (ORF) in Frankia strain ArI3 has a length of 1587 nucleotides, starting with a GTG codon, preceded by a ribosome binding site of a structure similar to that of nifH (GGAGGN₇). The codon usage was similar to that of previously sequenced Frankia genes with a strong bias toward G- and C-ending codons except in the case of glycine where GGT is frequent. Alignment of the three Frankia nifK sequences (EUN1f; ArI3 and ACoN24d) with those of other nitrogen-fixing bacteria permitted detection of a sequence conserved among the three Frankia strains but absent in the other sequences. A primer targeted to that region in combination with FGPD807-85 amplified the nifD—K IGS sequences of all Frankia strains (except the non-nitrogen-fixing Frankia strains CN3 and AgB1-9) and yet failed to amplify DNA of all other nitrogen–fixing bacteria. Conversely, the failure of primer FGPK700′-92 to amplify Alnus-infective strains could be explained by point mutations in the 3′ part of the primer.     

Characterization of Fusarium circinatum from Pinus spp. in northern Spain

Pitch canker caused by Fusarium circinatum was recently reported on Pinus spp. in Spain. In this study, a collection of 157 isolates of F. circinatum obtained from different geographical origins and hosts in northern Spain were identified and characterized by cultural and morphological features, PCR-RFLPs of the histone H3 gene, IGS region, and the translation elongation factor 1-alpha gene (TEF). Mating types were determined by multiplex PCR and sexual compatibility was performed under laboratory conditions. Both mating types were present in Spain and were able to form the teleomorph Gibberella circinata. Morphological differences between mating types, not previously reported, were observed: MAT-1 isolates showed clear, coiled, sterile hyphae characteristic of F. circinatum, whereas MAT-2 isolates presented sterile hyphae but not coiled. Virulence of representative isolates was tested on seven to eight-month-old P. nigra, P. pinaster and P. sylvestris seedlings. All isolates tested were pathogenic to these pine species, MAT-1 isolates being more virulent than MAT-2 isolates.