Comparison of genetic behaviour of the transposable element Tam3 at two unlinked pigment loci in Antirrhinum majus

Summary In Antirrhinum majus the transposable element Tam3 has been described at two unlinked loci pallida and nivea, both of which are required for the production of anthocyanin pigment in flowers. In each case the element is inserted in the promoter region and gives a variegated phenotype. We show that the rate of Tam3 excision at both loci is greatly affected by temperature, being approximately 1000-fold higher at 15°C compared with 25°C. Tam3 is also controlled by an unlinked gene Stabiliser, which considerably reduces excision rate. We show that the high degree of sensitivity to temperature and Stabiliser is an intrinsic property of Tam3 which is not shared by an unrelated element, Tam1. The Tam3 insertion at nivea gives rise to a series of alleles which confer reduced pigmentation, novel spatial patterns and changed instability. These are probably a result of imprecise excision and rearrangements of the Tam3 element.     

HLA class II SNP interactions and the association with type 1 diabetes mellitus in Bengali speaking patients of Eastern India

Background

Several studies have demonstrated a fundamental role for the HLA in the susceptibility of, or protection to, type 1 diabetes mellitus (T1DM). However, this has not been adequately studied in Asian Indian populations. To assess the frequency of HLA class II (DPA1, DPB1, DQA1, DQB1 and DRB1) associated to susceptibility or protection toT1DM in a Bengali population of India with diabetes.

Results

Single nucleotide polymorphism study. The HLA genotyping was performed by a polymerase chain reaction followed by their HLA-DP, DQ, and DRB1 genotypes and haplotypes by sequencing method. The results are studied by Plink software. The χ² tests were used for the inferential statistics. To our knowledge, this study is the first of a kind which has attempted to check the HLA association with T1DM by SNPs analysis. The study recruited 151 patients with T1DM and same number of ethno-linguistic, sex matched non-diabetic controls. The present study found a significant SNP rs7990 of HLA-DQA1 (p = 0.009) negative correlation, again indicating that risk from HLA is considerably more with T1DM.

Conclusions

This study demonstrates that the HLA class-II alleles play a major role in genetic basis of T1DM.     

曲马多代谢相关基因多态性研究进展

盐酸曲马多是临床中常用的弱阿片类药物,用于治疗中度疼痛,其镇痛效果介于弱罂粟碱和吗啡之间,临床中用于术后疼痛、牙痛、和其他疼痛,镇痛效果明显,安全性好。但是由于曲马多各基因型对其药物代谢行为的影响,在临床使用中,曲马多的镇痛效果和不良反应个体差异大。为了研究对比不同种族之间曲马多代谢等位基因的分布情况,作者通过检索,对不同的人种CYP2D6的不同活性,不同人种决定该酶活性的等位基因频率,不同基因型对曲马多代谢行为的影响进行综述。     

p53基因多态性和脑外伤预后及临床意义

目的：研究颅脑外伤患者中P53等位基因与基因型的频率分布,探讨其与脑损伤预后的关联性,为脑损伤患者预后提供部分参数依据。方法：选择各型颅脑损伤患者141例,正常对照者144人,患者按GCS格拉斯哥评分法进行分类;采用PCR基因型检测法检测P53等位基因,基因计数法计算等位基因频率;统计学分析等位基因和基因型在脑外伤组与正常对照组、预后良好组与预后不良组的频率分布的差异,并综合分析患者年龄、性别、GCS以及P53各等位基因等因素对脑外伤患者预后的影响。结果：在颅脑外伤患者和正常对照者中P53等位基因和基因型的频率分布,差异均无统计学意义（P〉0.05）;等位基因Arg相对于Pro的OR为1.140,基因型Arg/Pro、Arg/Arg相对于Pro/Pro的OR分别为0.890和1.170。在重型脑外伤患者（3≤GCS≤8分）86例中,预后良好31例,预后不良55例,基因型对预后不良的影响：非Pro/Pro相对于Pro/Pro的OR为0.417,非Arg/Pro相对于Arg/Pro的OR为0.419,非Arg/Arg相对于Arg/Arg的OR为3.667。在所有脑外伤患者中,预后良好组和预后不良组的患者年龄、性别差异均无统计学意义（P〉0.05）;GCS、P53等位基因差异具有显著统计学意义（P〈0.01）。结论：在重型颅脑患者中,基因型Arg/Arg有增加预后不良的风险;脑外伤预后与患者的年龄、性别无关联,与GCS、P53基因密切相关。     

The molecular bases for resistance to acetyl co-enzyme A carboxylase (ACCase) inhibiting herbicides in two target-based resistant biotypes of annual ryegrass (Lolium rigidum)

Acetyl-CoA carboxylase (ACCase) (EC.6.4.1.2) is an essential enzyme in fatty acid biosynthesis and, in world agriculture, commercial herbicides target this enzyme in plant species. In nearly all grass species the plastidic ACCase is strongly inhibited by commercial ACCase inhibiting herbicides [aryloxyphenoxypropionate (APP) and cyclohexanedione (CHD) herbicide chemicals]. Many ACCase herbicide resistant biotypes (populations) of L. rigidum have evolved, especially in Australia. In many cases, resistance to ACCase inhibiting herbicides is due to a resistant ACCase enzyme. Two ACCase herbicide resistant L. rigidum biotypes were studied to identify the molecular basis of ACCase inhibiting herbicide resistance. The carboxyl-transferase (CT) domain of the plastidic ACCase gene was amplified by PCR and sequenced. Amino acid substitutions in the CT domain were identified by comparison of sequences from resistant and susceptible plants. The amino acid residues Gln-102 (CAG codon) and Ile-127 (ATA codon) were substituted with a Glu residue (GAG codon) and Leu residue (TTA codon), respectively, in both resistant biotypes. Amino acid positions 102 and 127 within the fragment sequenced from L. rigidum corresponded to amino acid residues 1756 and 1781, respectively, in the A. myosuroides full ACCase sequence. Allele-specific PCR results further confirmed the mutations linked with resistance in these populations. The Ile-to-Leu substitution at position 1781 has been identified in other resistant grass species as endowing resistance to APP and CHD herbicides. The Gln-to-Glu substitution at position 1756 has not previously been reported and its role in herbicide resistance remains to be established.     

A mixed strategy model for the emergence and intensification of social learning in a periodically changing natural environment

Based on a population genetic model of mixed strategies determined by alleles of small effect, we derive conditions for the evolution of social learning in an infinite-state environment that changes periodically over time. Each mixed strategy is defined by the probabilities that an organism will commit itself to individual learning, social learning, or innate behavior. We identify the convergent stable strategies (CSS) by a numerical adaptive dynamics method and then check the evolutionary stability (ESS) of these strategies. A strategy that is simultaneously a CSS and an ESS is called an attractive ESS (AESS). For certain parameter sets, a bifurcation diagram shows that the pure individual learning strategy is the unique AESS for short periods of environmental change, a mixed learning strategy is the unique AESS for intermediate periods, and a mixed learning strategy (with a relatively large social learning component) and the pure innate strategy are both AESS's for long periods. This result entails that, once social learning emerges during a transient era of intermediate environmental periodicity, a subsequent elongation of the period may result in the intensification of social learning, rather than a return to innate behavior.     

Linkage disequilibrium between alleles at highly polymorphic mini- and micro-satellite loci of Theileria parva isolated from cattle in three regions of Kenya

Theileria parva schizont-infected lymphocyte culture isolates from western, central and coastal Kenya were analysed for size polymorphism at 30 T. parva-specific variable number tandem repeat (VNTR) loci using a panel of mini- and micro-satellite markers. The mean number of alleles ranged from 3 to 11 at individual loci and 183 distinct alleles were observed in total, indicating high genetic diversity within the T. parva gene pool in Kenyan cattle. The frequency distribution of the length variation of specific alleles among isolates ranged from normal to markedly discontinuous. Genetic relationships between isolates were analysed using standard indices of genetic distance. Genetic distances and dendrograms derived from these using neighbour-joining algorithms did not indicate significant clustering on a geographical basis. Analysis of molecular variance demonstrated that the genetic variation between individual isolates was 72%, but only 2.3% when isolates from different regions were pooled. Both these observations suggest minimal genetic sub-structuring relative to geographical origin. Linkage disequilibrium was observed between pairs of loci within populations, as in certain Ugandan T. parva populations. A novel observation was that disequilibrium was also detected between alleles at three individual pairs of VNTR loci when isolates from the three regional meta-populations were pooled for analysis.     

云南肺癌易感性与HLA-A，HLA-B，DRB1，DQB1等位基因频率的相关性研究

目的:测定云南肺癌患者人类白细胞抗原(human leukocyte antigen,HLA)-A、B、DRB1、DQB1等位基因出现频率,探讨HLA各等位基因位点与云南省肺癌发病易感性的相关性。方法:采用病例-对照相关分析方法,选取云南籍肺癌患者和健康个体各30例,应用序列特异性引物聚合酶链反应(polymerase chain reaction-sequence specific primer,PCR-SSP)对HLA-A、HLA-B、HLA-DRB1及HLA-DQB1等位基因频率进行测定,与正常组对比测算相对危险因子(relative risk,RR)。结果:肺癌组的HLA-A~*02频率为90.0%(A~*0201为主),B~*46频率为40.0%,DRB1~*15频率为40.0%,较对照组的43.30%、0%、10.0%明显升高(Pc0.05,RR1)。肺癌组的HLA-A~*31频率为3.30%,A~*33频率为6.70%,B~*27频率为3.30%,B~*52频率为6.70%,DRB1~*03频率为0%,DRB3~*01频率为60.0%,DQB1~*02频率为0%,DQB1~*06频率为0%,较对照组的23.30%、26.70%、26.70%、26.70%、23.30%、86.70%、23.30%、26.70%降低明显,(RR1,Pc0.05)。结论:云南肺癌易感性可能与HLA-A~*02的频率(90%)具有相关性;而HLA-A~*31、HLA-A~*33、HLA-B~*52、HLA-B~*27、HLA-DRB1-~*03、HLA-DRB3~*01、HLA-DQB1~*02及HLA-DQB1~*06在肺癌患者中的频率较低,在云南肺癌发病中可能具有遗传拮抗作用。     

Sequence and evolution of the gene for the monomeric globin I and its linkage to genes coding for dimeric globins in the insect Chironomus thummi

We isolated genomic clones containing sequences encoding globins I and IA from a Chironomus thummi thummi genomic library. Three clones contain globin IA (ctt-1A) genes, while one contains a globin I (ctt-1) gene. The coding regions of the four genes are identical except for the single base substitution accounting for the globin I/IA polymorphism. The noncoding DNA flanking the coding region is more than 98% similar, confirming a previous hypothesis that the globin ctt-1 and ctt-1A genes are alleles. Hemoglobins I and IA are monomeric in the insect hemolymph. Earlier in situ hybridization studies suggested that monomeric and dimeric globin genes are clustered at different chromosomal loci. In situ hybridization of ctt-1 DNA to polytene salivary gland chromosomes places the ctt-1 gene on the same band as genes for the dimeric globins II and VIIB, forcing revision of the earlier hypothesis that genes for monomeric and dimeric globin genes are at different loci. The evolution of the ctt-1 and ctt-1A alleles and of the two globin gene loci are discussed. Correspondence to: G. Bergtrom