Genetic structure of three Oryza AA genome species (O. rufipogon, O. nivara and O. sativa) as assessed by SSR analysis on the Vientiane Plain of Laos

Microsatellite (SSR) markers can reveal a high level of polymorphic loci, and are increasingly being used in population genetic structure studies. On the Vientiane plain of Laos all components of the rice crop complex exist, wild annual (O. nivara), wild perennial (O. rufipogon) and weedy relatives of rice as well as rice itself. To understand gene flow in the rice complex, the genetic structures of O. rufipogon (10 populations), O. nivara (10 populations) and O. sativa (24 samples) from across the Vientiane Plain, Laos, were compared. Higher genetic differentiation was detected among O. nivara populations (G _ST = 0.77, R _ST = 0.71) than O. rufipogon populations (G _ST = 0.29, R _ST = 0.28), whereas genetic diversity for all populations of these two wild species showed similar values (H _T = 0.77 and 0.64 in O. rufipogon and O. nivara, respectively). Based on neighbor-joining tree constructed on the basis of genetic distance (D _A), three genetic clusters were detected, corresponding to (1) O. sativa samples, (2) O. nivara populations and (3) O. rufipogon populations. Pairwise tests confirmed the genetic differentiation of the three species. Although none of the wild rice individuals used in this study had any cultivated-specific phenotypic traits, genetic admixture analysis detected more than 10% O. sativa membership in three O. rufipogon and one O. nivara populations, indicating that O. sativa alleles may cryptically persist in natural populations of O. rufipogon and O. nivara on the Vientiane Plain.     

The sporadic occurrence of a group I intron-like element in the mtDNA rnl gene of Ophiostoma novo-ulmi subsp. americana

The presence of group I intron-like elements within the U7 region of the mtDNA large ribosomal subunit RNA gene (rnl) was investigated in strains of Ophiostoma novo-ulmi subsp. americana from Canada, Europe and Eurasia, and in selected strains of O. ips, O. minus, O. piceae, O. ulmi, and O. himal-ulmi. This insertion is of interest as it has been linked previously to the generation of plasmid-like mtDNA elements in diseased strains of O. novo-ulmi. Among 197 O. novo-ulmi subsp. americana strains tested, 61 contained a 1.6 kb insertion within the rnl-U7 region and DNA sequence analysis suggests the presence of a group I intron (IA1 type) that encodes a potential double motif LAGLIDADG homing endonuclease-like gene (HEG). Phylogenetic analysis of rnl-U7 intron encoded HEG-like elements supports the view that double motif HEGs originated from a duplication event of a single-motif HEG followed by a fusion event that combined the two copies into one open reading frame (ORF). The data also show that rnl-U7 intron encoded ORFs belong to a clade that includes ORFs inserted into different types of group I introns, e.g. IB, ID, IC3, IA1, present within a variety of different mtDNA genes, such as the small ribosomal subunit RNA gene (rns), apo-cytochrome b gene (cob), NADH dehydrogenase subunit 5 (nad5), cytochrome oxidase subunit 1 gene (coxI), and ATPase subunit 9 gene (atp9).

We also compared the occurrence of the rnl-U7 intron in our collection of 227 strains with the presence of the rnl-U11 group I intron and concluded that the U7 intron appears to be an optional element and the U11 intron is probably essential among the strains tested.     

Biochemical systematics of two sibling species of polychaete annelids: Ophelia bicornis and O. radiata

Biochemical analysis of polychaete annelids from the English Channel and the Atlantic Coast has shown that they represent two genetically isolated species, Ophelia bicomis and O. radiata, characterized by different alleles at four loci and a mean number of 15 and 14 pairs of gills, respectively. Sampling of Mediterranean annelids was insufficient to determine whether or not the population studied belongs to the O. radiata species.     

崖壁植物太行菊与长裂太行菊全基因组大小及特征分析北大核心CSCD

太行菊(Opisthopappus taihangensis)、长裂太行菊(O.longilobus),为太行山特有多年生崖壁草本植物,菊科(Compositae)重要野生资源,具有较高的经济与生态价值。为确定适合两物种的全基因组测序策略,该研究利用流式细胞法和高通量测序技术,分析两物种基因组大小、杂合率、重复序列及GC含量等信息。结果表明:(1)流式细胞法估算太行菊基因组大小约为2.1 Gb,长裂太行菊基因组大小约为2.4 Gb。(2)高通量测序修正后太行菊基因组大小为3.13 Gb,重复序列比例为84.35%,杂合度为0.99%,GC含量为36.56%;长裂太行菊基因组为3.18 Gb,重复序列比例为83.83%,杂合度为1.17%,GC含量为36.62%。(3)初步组装后GC含量分布及平均深度存在异常,出现分层现象,可能是两物种基因组杂合率较高所致。综上结果表明,太行菊、长裂太行菊均属于高重复、高杂合、大基因组的复杂基因组,建议使用Illumina+PacBio测序组装策略,进行全基因组测序分析。     

Serological and genetic analysis of a rare CisAB01/O01 blood group

The paper aims to analyze a rare blood sample in Ganzhou City Hospital with CisAB subtype and explore a feasible pattern for blood typing of rare blood type patients, so as to ensure clinical transfusion safety. The routine serological methods were used for ABO forward and reverse blood typing and the fluorescence real-time PCR technique was used for sample genotyping. A human ABO blood group 6-7 exon sequencing kit was used for sequence analysis. The nucleic acid sequence of the sample was compared with reference sequences. The forward typing results demonstrated that the sample was ABw, RhD positive. The sample exhibited 4+ agglutination with anti-H and anti-AB antibodies. Reverse typing by microcolumn gel method showed an AB result, but the serum sample demonstrated weak agglutination with B cell under room temperature, 4 °C and 37 °C in saline when tested with tube method respectively. The serological results matched with the A₂B₃ serotype. The fluorescent real-time PCR genotyping results displayed A/O01. The sequence analysis demonstrated deletion of guanine in 261-position 467C>T (heterozygote) and 803G>T (heterozygote) mutation respectively. The mutation caused the A glycosyltransferase peptide chain to change from proline to leucine (P156L) at 156 and from glutamate to alanine (G268A) at 268. The result demonstrated that the sample''s genotype was CisAB01/O01. The mutation of glycosyltransferase coding gene leads to an abnormal serological reaction pattern. Only by combining the results of genetic analysis can we get the true sample blood type and better ensure the safety of clinical blood transfusion.     

Characterization of a highly stable trypsin-like proteinase inhibitor from the seeds of Opuntia streptacantha (O. streptacantha Lemaire)

A trypsin inhibitor from Opuntia streptacantha Lemaire (Prickly pear) seeds was purified and characterized. Of several proteases tested, this inhibitor showed specificity to trypsin-like enzymes. The major inhibitor present in these seeds showed distinctive characteristics, most notably a low molecular weight of 4.19 kDa, as determined by MALDI TOF, and an unusually high thermal stability, retaining most of the activity after heating the sample 1 h to 120 °C with a pressure of 1 kg/cm². Its complete amino acid sequence was obtained through mass spectrometry, this establishing presence a blocked N-terminal region. When comparing its sequence in the MEROPS database for peptidases and peptidase inhibitors, it showed 34.48% identity with a serine-proteinase inhibitor from the I15 family.     

Widespread horizontal transfer of the cerato-ulmin gene between Ophiostoma novo-ulmi and Geosmithia species

Previous work had shown that a sequence homologous to the gene encoding class II hydrophobin cerato-ulmin from the fungus Ophiostoma novo-ulmi, the causal agent of Dutch Elm Disease (DED), was present in a strain of the unrelated species Geosmithia species 5 (Ascomycota: Hypocreales) isolated from Ulmus minor affected by DED. As both fungi occupy the same habitat, even if different ecological niches, the occurrence of horizontal gene transfer was proposed. In the present work we have analysed for the presence of the cerato-ulmin gene 70 Geosmithia strains representing 29 species, isolated from different host plants and geographic locations. The gene was found in 52.1 % of the strains derived from elm trees, while none of those isolated from nonelms possessed it. The expression of the gene in Geosmithia was also assessed by real time PCR in different growth conditions (liquid culture, solid culture, elm sawdust, dual culture with O. novo-ulmi), and was found to be extremely low in all conditions tested. On the basis of these results we propose that the cerato-ulmin gene is not functional in Geosmithia, but can be considered instead a marker of more extensive transfers of genetic material as shown in other fungi.     

帕米尔木灵藓和细齿木灵藓（木灵藓科）的形态特征及其在中国的新分布

该文报道了采自新疆的木灵藓属中国2个新记录种——帕米尔木灵藓(Orthotrichum pamiricum)和细齿木灵藓(O.scanicum)。帕米尔木灵藓的识别特征为:叶尖钝,气孔隐型,多着生于孢蒴下部,外齿层齿片8对,干燥时蒴齿背曲,内齿层蒴条16,上部内曲;细齿木灵藓的识别特征为:叶尖部具细齿,气孔半隐型,蒴帽具分散的透明毛,内齿层和外齿层均16片,具8条黄色细沟,干燥时中部以上具沟。对这2种藓类的形态特征、生境和地理分布及与其相似种的形态学进行了比较分析,并绘制了每种的形态结构墨线图。木灵藓属植物在中国的新分布记录进一步表明,新疆地区富含生物多样性,并与中亚植物区系存在密切关系。     

Flash flooding resistance of rice genotypes of Oryza sativa L., O. glaberrima Steud., and Interspecific hybridization progeny

In the costal area and inland valleys of Guinea, flash floods occur frequently following heavy rain during the rainy season. Young rice seedlings are particularly vulnerable to submergence stress due to insufficient height and carbohydrate reserves. In an attempt to characterize the physiological responses of young seedlings to flash flood, a wide genetic base including O. sativa, O. glaberrima, and interspecific hybridization progenies (IHP) was used.

Twelve day-old seedlings were submerged for 7 days, and plant height, dry matter accumulation (DMA), and lodging were measured. Upland rice (O. sativa) showed greater shoot elongation, larger reduction in DMA during submergence, and higher lodging, which lead to low flash flooding resistance (FFR). The physiological traits of most O. glaberrima and upland rice (O. sativa) to flash flood were opposite to those of submergence tolerant cultivars, as evidenced from the results of a principal component analysis. The physiological response of Saligbeli was different to other O. glaberrima genotypes in terms of FFR. Saligbeli exhibited enhanced shoot elongation with the increase in DMA during submergence. These features seemed to be a unique way to cope with submergence. Some IHP adapted to lowland cultivation showed traits similar to Saligbeli. The vigorous growth of Saligbeli and IHP underwater should be further investigated for improving FFR in rice.     

Functional interactions between the gene tetanic and the Shaker gene complex of Drosophila

Different phenotypes associated with the tetanic (tta) mutation such as appendage contraction, maternal effect and low viability and fertility are enhanced by one extra dose of the Shaker gene complex (ShC). The tta mutation is lethal with two extra doses of ShC. In addition, tta embryos have a defective nervous system. In this paper, I analyse the interaction between tta and ShC to gain insight into their relationship. Aneuploid analysis suggests that the lethality is due to an interaction of the tta mutation with the maternal effect (ME) region of this gene complex. Mutations in the ME region of ShC partially suppress this interaction. Trans-heterozygous combinations of MEI[l(1)305] and MEIII [l(1)459] mutations causes dominant lethality in a tta background. Trans-heterozygous combinations of an MEII [l(1)1359] mutation with the cited MEI and MEIII mutations are lethal in a tta background. Double mutant combinations and gene dosage experiments, suggest that tta also interacts with the viable (V) region of ShC. These specific genetic interactions indicate that tta and the ME and V regions of ShC are functionally related. These results, together with the previous electrophysiological, molecular and biochemical studies on these mutants suggest an interaction at the protein level. Thus, in the case of the V region, the tta gene product may modulate the activity of the K⁺ channels encoded in this region. Furthermore, the extreme dosage sensitivity of the interaction between tta and ShC suggests a stoichiometric requirement for the different gene products involved, which might be physically associated and form heteromultimers.     

Functional substitution of the recE gene of Bacillus subtilis by the recA gene of Proteus mirabilis

Summary Rec mutants of Bacillus subtilis have been tested for complementation by the recA gene of Proteus mirabilis (recApm) which was introduced into B. subtilis via the plasmid pHP334. In the recE4 mutant of B. subtilis the plasmid pHP334 restored significantly the defects in RecE functions tested: UV-sensitivity, homologous recombination (transduction and transformation) and prophage induction.Although serological methods to detect the presence of RecApm protein in B. subtilis have been unsuccessful, our results strongly indicate that the recE function of B. subtilis is analogous to the recA function of P. mirabilis.Abbreviations Cm^r resistance to chloramphenicol - Em^r resistance to erythromycin - Tc^r resistance to tetracycline - SDS sodium dodecyl sulfate - UV ultraviolet - AS ammonium sulfate     

核桃细菌性黑斑病菌rpfG基因的功能分析

[目的] 本研究旨在揭示核桃细菌性黑斑病菌（Xanthomonas arboricola pv.juglandis,Xaj） DW3F3中rpfG基因的生物学功能,从而为核桃细菌性黑斑病防治药剂的开发提供作用靶点。[方法] 以野油菜黄单胞菌（Xanthomonas campestris pv.campestris,Xcc）8004菌株以及水稻白叶枯病菌（Xanthomonas oryzae pv.oryzae,Xoo） PXO99^A的rpfG基因为模板序列,对Xaj野生型菌株DW3F3的基因组序列进行检索。利用同源重组技术,对Xaj中rpfG基因进行敲除,并用生物化学方法对基因缺失菌株的相关毒力因子、抗逆性进行检测。[结果] 通过同源比对,在XajDW3F3的基因组中发现了与XccrpfG、XoorpfG同源的基因,并成功获得rpfG的缺失突变株ΔrpfG。与野生型相比,突变株ΔrpfG的生物被膜形成能力仅为野生型XajDW3F3的44.58%;胞外多糖产量也由野生型的8.47 mg/mL降为5.23 mg/mL;ΔrpfG的絮凝活性增加,能使菌液变澄清;运动性实验显示ΔrpfG的运动直径比野生型增加了12.38%;胞外酶的分泌也发生了不同程度的改变,突变株分泌纤维素酶的能力极显著降低,淀粉酶活性有所提高,而分泌蛋白酶的能力未发生变化;此外rpfG缺失后,Xaj对逆境（盐、酸、SDS、硫酸铜）的耐受力降低。[结论] 结果表明rpfG基因能影响核桃细菌性黑斑病菌的致病相关性状,并赋予了细菌一定的抗逆性。