中国东北地区黑腹果蝇（Drosophila melanogaster）P因子分布和来源

真核生物的转座因子(transposable elements)特别是果蝇P因子在研究生物进化上有重要的意义。以我国东北地区13个地方及毗邻的北京、烟台和呼和浩特三个地方共130个黑腹果蝇(D.melanogaster)单雌系为材料,对P因子序列的ORF2-ORF3区段进行PCR扩增,统计不同地方黑腹果蝇群体的P因子在此区段的缺失频率,再从整个地区来分析P因子缺失的分布规律,以推导东北地区黑腹果蝇中P因子的传递和扩散途径。结果显示P因子缺失频率由边境地区向内地逐渐递减,群体相对隔离的地方也较低,推断我国东北地区黑腹果蝇中P因子由朝鲜和俄罗斯向中国边境入侵后,逐步向中国内地扩散。     

我国东北地区黑腹果蝇P-M品系分布及P因子的入侵途径

对我国东北地区及毗邻的北京、呼和浩特和烟台地区近两年收集的黑腹果蝇（Drosophila melanogaster)自然群体进行了有关P－M杂种劣育的研究。用两类标准诊断杂交的方法测定了15个地方108个单雌系的P因子活性和细胞调控能力。结果表明,在15个地方自然群体中,大连、烟台、延吉、长白及哈尔滨5个地区为Q型,其余的均为M′型,没有P型。同时,这些自然群体的杂交A^*的不育率也存在着地理性差异：东南部地区,特别是沿渤海和中朝边境地区的品系以Q型为主,而中部和北部扩大地区则以M′型为主。据此推断我国境内的P因子是由朝鲜半岛和日本分两路侵入：一路从日本、朝鲜半岛经海路传递到沿海的烟台和大连地区,再由此向东北和南部地区入侵和扩散;另一路由朝鲜半岛侵入中朝边境的长白和延吉地区后,再向东北地区及内地入侵。两条路线在哈尔滨地区会合,使该地区品系的杂交A^*的不育率升高。     

中国黑腹果蝇中分离变相因子[Segregation Distorter(SD)]的初步研究

黑腹果蝇（Ｄｒｏｓｏｐｈｉｌａ ｍｅｌａｎｏｇａｓｔｅｒ）中的分离变相因子「Ｓｅｇｒｅｇａｔｉｏｎ Ｄｉｓｔｏｒｔｅｒ（ＳＤ）」是一种非常典型的具有减数分裂驱动性质的特殊遗传因子，ＳＤ在世界不同地区的黑腹果蝇群体中广泛存在，通过杂交的方法测得其频率在１％－５％范围之内。首次在中国北京，青岛采集大量野生黑腹果蝇样本，对ＳＤ进行频率测定，发现ＳＤ在中国野生黑腹果蝇群体中也广泛存在，且频率与世界其他地区     

黑腹果蝇P转座因子研究 Ⅰ.我国黑腹果蝇的P-M测定及其地理分布

采用性腺败育(GD不育)作为标准检定方法。对我国20个地方的黑腹果蝇的P因子活性和细胞型进行了测定。结果表明我国北部沿海城市为Q型;南部沿海和内地皆为M型。各地的M品系所产生的GD不育能力各不相同,但表现出与地理位置相关的梯度变化。这一变化规律为研究我国黑腹果蝇的P因子起源及P和M品系的形成提供了重要的理论依据。     

piggyBac转座子AgoPLE1.1在黑腹果蝇种系 转化中的应用

【目的】通过检测黑腹果蝇Drosophila melanogaster中piggyBac (PB)转座子AgoPLE1.1的转化活性,明确AgoPLE1.1开发为昆虫转基因载体的潜力。【方法】构建AgoPLE1.1转座酶辅助质粒pAgoHsp和带有红色荧光标记的供体质粒pXLAgo-PUbDsRed,辅助质粒和供体质粒以170 ng/μL∶400 ng/μL, 90 ng/μL∶200 ng/μL和90 ng/μL∶100 ng/μL 3种不同的比例混合后分别注射新鲜的W¹¹¹⁸ 黑腹果蝇胚胎,筛选注射后代中的转基因黑腹果蝇个体;利用Southern杂交验证转基因黑腹果蝇中AgoPLE1.1转座子的插入拷贝数;利用染色体步移技术克隆AgoPLE1.1插入位点旁侧序列,明确AgoPLE1.1转座子的转座特征。【结果】AgoPLE1.1转座子在黑腹果蝇中具有转化活性,转基因频率为1.32%~1.94%。Southern杂交结果显示,AgoPLE1.1转座子在黑腹果蝇中至少有6个插入位点。染色体步移法克隆了其中4个位点,分别位于黑腹果蝇的3R, 3L, 2L和X染色体,并且AgoPLE1.1转座子在黑腹果蝇染色体中的整合带有供体质粒的骨架。【结论】PB转座子AgoPLE1.1仅可以在黑腹果蝇中以较低的频率进行非精确的剪切和转座,不具有开发为新型昆虫转基因载体的潜力。     

虫草素对微波辐射黑腹果蝇的保护作用

为了研究虫草素对微波辐射黑腹果蝇Drosophila melanogaster的保护作用,以梯度浓度的虫草素培养基饲养微波辐射的黑腹果蝇,观察统计其生殖力及子代生长发育特征。研究发现,微波辐射后的黑腹果蝇生殖力极显著下降(P0.01),虫草素能提高其生殖力,其中0.4%质量分数的虫草素培养基极显著提高成蛹数和成蝇数(P0.01);微波辐射后黑腹果蝇子代的性比降低、体长减少、飞翔率极显著降低(P0.01)、畸变率极显著升高(P0.01),4个梯度浓度的虫草素均能提高子代的性比,使其接近于1,而且均能降低畸变率,差异具有高度统计学意义(P0.01)。由此可见,虫草素能够修复黑腹果蝇的辐射损伤,对机体起到抗辐射的保护作用。     

樱桃新害虫黑腹果蝇的生物学特性

果蝇是近几年发现危害樱桃果实的一类重要害虫,在国内外樱桃产区均有发生。天水地区危害甜樱桃的果蝇有3个种,分别是黑腹果蝇Drosophila melanogaster Meigen、铃木氏果蝇Drosophila suzukii(Matsumura)和海德氏果蝇Drosophila hydei(Sturtevant),黑腹果蝇为优势种。作者记述黑腹果蝇对甜樱桃果实的危害情况、寄主范围及其生活史、生活习性、发育历期与温度的关系等,调查发现蚂蚁是樱桃果蝇的天敌之一。     

中国银额果蝇自然群体B染色体的分布

经对我国银额果蝇自然群体Ｂ染色体（Ｂｓ）的分布进行多年广泛地调查,共作过２４个群体,５７２个单雌系,６７３８只个体的观察。从细胞和群体水平研究Ｂｓ的地理分布。结果发现,中国（除台湾省外）银额果蝇自然群体中普遍存在Ｂｓ。结合前人报道得出。Ｂｓ的地理分布出现了由东向西和由南向北的规律性的依次升高趋势。这种跨越不同地理环境的区域性梯度变异与其宿主向大陆内地扩散的推论相符。Ｂｓ频率最高（８７．７％）的是海     

以黑腹果蝇为寄主的蝇蛹金小蜂生长发育、繁殖及功能反应研究

蝇蛹金小蜂是铃木氏果蝇和黑腹果蝇的重要天敌,本研究以黑腹果蝇为寄主,测定了蝇蛹金小蜂云南种群的生长发育、繁殖及寿命。并在6个寄主密度梯度条件下研究了其寄生功能反应。结果显示蝇蛹金小蜂从卵到雌、雄成蜂的平均发育历期分别为16.10 d和14.67 d,雌蜂平均寿命为49.76 d,平均产子代数为93.28头/雌,子代雌性比为55.76%。在黑腹果蝇蛹为5、10、15、20、25和30头的密度梯度下,蝇蛹金小蜂的寄生功能反应符合Holling Ⅱ模型,其方程为Na=0.6261 No/(1+0.0632 No)。理论最高寄生量为N_a_(max)=9.0171,实际最高寄生量为7.00头(寄主密度为20头),蝇蛹金小蜂的寄生搜寻效应随寄主密度的增加而降低。综上结果,采自杨梅的蝇蛹金小蜂以黑腹果蝇作为寄主时具有较高繁殖力,较强的寄主适合度,是铃木氏果蝇和黑腹果蝇有效的生物防治作用因子。     

异色瓢虫捕食胁迫对黑腹果蝇繁殖与后代发育的影响水

以模式昆虫黑腹果蝇(Drosophila melanogaster)及捕食性天敌异色瓢虫(Harmonia axyridis)为研究系统,通过把异色瓢虫接入到有黑腹果蝇的指形管中,研究了黑腹果蝇雌、雄成虫单独或共同被异色瓢虫捕食胁迫后,其自身寿命、子代的生长发育、繁殖和适合度的变化。结果表明:当雄性黑腹果蝇受到异色瓢虫成虫胁迫时,其寿命明显延长,但胁迫与否对雌性黑腹果蝇的寿命无明显影响;当黑腹果蝇的雌雄成虫同时受到胁迫时,其子代幼虫的发育历期延长,雄性后代寿命也增加,而雌性或雄性黑腹果蝇单独受到胁迫,其子代幼虫发育进度没有明显改变;当初孵黑腹果蝇幼虫受到异色瓢虫成虫直接或间接捕食胁迫后,其后续幼虫的发育历期都会受到影响,其中1龄期受到的间接捕食胁迫作用的影响大于直接捕食胁迫作用,直接捕食胁迫1龄幼虫比间接捕食胁迫更能延长其将来雌性成虫的寿命。     

Mechanisms regulating the copy numbers of six LTR retrotransposons in the genome of Drosophila melanogaster

There has been debate over the mechanisms that control the copy number of transposable elements in the genome of Drosophila melanogaster. Target sites in D. melanogaster populations are occupied at low frequencies, suggesting that there is some form of selection acting against transposable elements. Three main theories have been proposed to explain how selection acts against transposable elements: insertions of a copy of a transposable element are selected against; chromosomal rearrangements caused by ectopic exchange between element copies are selected against; or the process of transposition itself is selected against. The three theories give different predictions for the pattern of transposable element insertions in the chromosomes of D. melanogaster. We analysed the abundance of six LTR (long terminal repeat) retrotransposons on the X and fourth chromosomes of multiple strains of D. melanogaster, which we compare with the predictions of each theory. The data suggest that no one theory can account for the insertion patterns of all six retrotransposons. Comparing our results with earlier work using these transposable element families, we find a significant correlation between studies in the particular model of copy number regulation supported by the proportion of elements on the X for the different transposable element families. This suggests that different retrotransposon families are regulated by different mechanisms.     

Intra- and interspecies variation among Bari-1 elements of the melanogaster species group.

We have investigated the distribution of sequences homologous to Bari-1, a Tc1-like transposable element first identified in Drosophila melanogaster, in 87 species of the Drosophila genus. We have also isolated and sequenced Bari-1 homologues from D. simulans, D. mauritiana, and D. sechellia, the species constituting with D. melanogaster the melanogaster complex, and from D. diplacantha and D. erecta, two phylogenetically more distant species of the melanogaster group. Within the melanogaster complex the Bari-1 elements are extremely similar to each other, showing nucleotide identity values of at least 99.3%. In contrast, Bari-1-like elements from D. diplacantha and D. erecta are on average only 70% similar to D. melanogaster Bari-1 and are usually defective due to nucleotide deletions and/or insertions in the ORFs encoding their transposases. In D. erecta the defective copies are all located in the chromocenter and on chromosome 4. Surprisingly, while D. melanogaster Bari-1 elements possess 26-bp inverted terminal repeats, their D. diplacantha and D. erecta homologues possess long inverted terminal repeats similar to the terminal structures observed in the S elements of D. melanogaster and in several other Tc1-like elements of different organisms. This finding, together with the nucleotide and amino acid identity level between D. diplacantha and D. erecta elements and Bari-1 of D. melanogaster, suggests a common evolutionary origin and a rapid diversification of the termini of these Drosophila Tc1-like elements.     

What is the impact of transposable elements on host genome variability?

The spread of a transposable element family through a wild population may be of astonishing rapidity. At least three families of transposable genetic elements have recently invaded Drosophila melanogaster worldwide, including the P element. The mechanism has been a process of effectively replicative transposition, and, for the P element, has occurred notwithstanding the sterility induced by unrestricted movement. This element's invasion into D. melanogaster has been accompanied by the development of heterogeneity between P sequences, most of which now have internal deletions. Increasing evidence suggests that some deleted elements can repress P transposition, thereby protecting the host from the harmful effects of complete elements. Such repressing elements may rise to high frequencies in populations as a result of selection at the level of the host. We here investigate selective sweeps invoked by the spread of P sequences in D. melanogaster populations. Numerous high-frequency sites have been identified on the X chromosome, which differ in frequency between populations, and which are associated with repression of P-element transposition. Unexpectedly, sequences adjacent to high-frequency P-element sites do not show reduced levels of genetic diversity, and DNA variability is in linkage equilibrium with the presence or absence of a P element at the adjacent selected site. This might be explained by multiple insertions or through a selection for recombination analogous to that seen in 'hitchhiking'.     

Structure of circular copies of the 412 transposable element present in Drosophila melanogaster tissue culture cells, and isolation of a free 412 long terminal repeat

We have isolated, from Drosophila melanogaster tissue culture cells, extrachromosomal circular forms of the transposable element 412, and have cloned some of them in bacteriophage lambda. A total of 24 clones have been analysed in detail by restriction and heteroduplex mapping. Seventeen clones are virtually identical, and contain complete 412 elements with one copy of the long terminal direct repeat (LTR). The remaining seven clones are all different and contain various rearrangements. Four have deletions, two have some 412 sequence substituted by other DNA and one has both an inversion and a deletion. The clone containing the inversion has two LTRs in inverted orientation and separated by a few thousand bases of 412 DNA. The base sequences of the two LTRs in this clone, and of the LTR in one of the 17 clones containing complete elements are very similar to that of the 481 base-pair LTR of a genomic 412 element. We have found no evidence, in either cloned or uncloned material, for 412 elements with two LTRs as a tandem direct repeat. We have found that there are several "free" 412 LTRs in genomic DNA from D. melanogaster strains Canton S and Oregon R, and from D. melanogaster tissue culture cells. We have cloned and sequenced one of these free LTRs. It is 475 base-pairs long and is flanked by a direct repeat four base-pairs long. This sequence differs from that of the 481 base-pair repeat at 16 places including a ten base deletion.     

Structure and genomic organization of I elements involved in I-R hybrid dysgenesis in Drosophila melanogaster.

I-R hybrid dysgenesis in D. melanogaster is controlled by transposable elements known as I factors which terminate at their 3' ends by an A-rich sequence. Inducer strains contain active I factors. Both reactive and inducer stocks possess defective I elements. We have cloned various I elements from both categories of strains. The I elements having recently transposed in inducer strains have a structure closely related to that of active I factors. However we have isolated one such I element that is truncated at its 5' end. The I elements common to reactive and inducer strains are affected by various rearrangements and many point mutations. They do not appear to be simple derivatives of complete I factors.     

A New Basal Subfamily of mariner Elements in Ceratitis rosa and Other Tephritid Flies

Several copies of highly related transposable elements, Crmar2, Almar1, and Asmar1, are described from the genomes of Ceratitis rosa, Anastrepha ludens, and A. suspensa, respectively. One copy from C. rosa, Crmar2.5, contains a full-length, uninterrupted ORF. All the other copies, from the three species contain a long deletion within the putative ORF. The consensus Crmar2 element has features typical of the mariner/Tc1 superfamily of transposable elements. In particular, the Crmar2 consensus encodes a D,D41D motif, a variant of the D,D34D catalytic domain of mariner elements. Phylogenetic analysis of the relationships of these three elements and other members of the mariner/Tc1 superfamily, based on their encoded amino acid sequences, suggests that they form a new basal subfamily of mariner elements, the rosa subfamily. BLAST analyses identified sequences from other diptera, including Drosophila melanogaster, which appear to be members of the rosa subfamily of mariner elements. Analyses of their molecular evolution suggests that Crmar2 entered the genome of C. rosa in the recent past, a consequence of horizontal transfer.