鳄龟科和平胸龟科线粒体控制区序列分析和结构比较

本文参照龟类近缘种的线粒体DNA(mitochondrial DNA,mtDNA)控制区(control region,CR)及邻接序列,设计了二对特异引物,采用PCR和测序技术,获得了大鳄龟(Macroclemys temminckii)、小鳄龟(Chelydra serpentina)和平胸龟(Platysternon megacephalum)mtDNA CR区序列,其长度分别为1062bp、1124bp和1119bp;A T的含量分别为68.93%、69.34%和69.44%。序列分析显示,三种龟CR区3'末端均存在丰富的微卫星序列,其中大鳄龟和小鳄龟各有一段2bp的TA序列分别重复20和15次;小鳄龟另有一段5bp的TATAT序列重复13次;平胸龟则是一段10bp的AGTATGTTAT序列重复4次和一段17bp的GTTGTTATATAACATAT序列重复13次。本文还结合GenBank中已发表的其他6种龟鳖类动物的控制区序列,探讨了龟鳖类动物微卫星序列的类型及分布,结果表明:9种龟鳖类动物都存在丰富的微卫星序列,且微卫星所在位置及序列存在很大差异。     

鸮形目两种鸟类线粒体基因组全序列测定与比较研究

利用Long-PCR和Primer Walking结合克隆测序法对短耳鸮和长耳鸮线粒体基因组进行了全序列测定. 结果表明: 短耳鸮mtDNA序列全长为18858 bp, 长耳鸮mtDNA全长为18493 bp, 其中短耳鸮mtDNA是目前已知最长的鸟类线粒体基因组. 两种鸮类的基因组结构和基因排列顺序与家鸡相同, 无假控制区, 在ND3基因174位点都存在一个额外插入的胞苷酸(C). 控制区序列异常增大是造成这两种鸟类mtDNA增大的主要原因, 短耳鸮控制区长度为3288 bp, 长耳鸮为2926 bp, 这是目前已知的脊椎动物线粒体基因组中仅次于盲鳗的最大的控制区. 在其控制区3′端存在大量的串联重复序列, 分析发现这两种鸮类的重复序列和Mt5调控元件有较高的序列相似性, 且能形成多重的茎环二级结构, 这表明该重复序列可能具有一定的生理功能, 影响线粒体基因组的复制或转录表达, 从而使相应物种具有更大的选择优势, 以适应环境和生存竞争.     

基于线粒体COⅠ和16S rRNA基因序列比较分析东海带鱼群体遗传多样性

测定了东海带鱼(Trichiurus lepturus Linnaeus)三个群体(命名为A: 122°32′E 29°55′N、B: 123°30′E 26°75N; C: 124°24′E 27°26′N)72个个体的线粒体DNA16S rRNA和COⅠ基因序列,通过单基因序列和联合序列分析, 研究了东海带鱼群体的遗传变异情况。分别得到1130 bp的COⅠ基因序列片段和554 bp的16S rRNA序列片段, 其中COⅠ基因片段的T、C、A、G含量分别为29.0%、28.9%、24.4%和17.7%; 16S rRNA基因片段的T、C、A、G含量分别为22.7%、27.6%、28.0%和21.7%。基于线粒体16S rRNA、COⅠ和16S+COⅠ基因序列分析, 72个个体中分别确定43个, 8个和49个单倍型, 存在单倍型共享现象。群体的单倍型多样性指数为0.9766—0.9992, 显示了群体内的单倍型较为丰富。3个群体间各序列平均核苷酸差异数(K)在5.111—9.024和0.0045—0.0076, 核苷酸多样性指数(π)为0.0048—0.0084, 显示不同带鱼群体遗传多态性丰富。使用邻接法构建的分子进化树揭示同一群体内大部分个体聚在一起。分析结果表明, 群体A遗传背景比群体B、群体C较为丰富, 群体内部个体差异大于群体间差异, 群体间基因交流频率较高, 遗传分化不明显, 初步判定东海带鱼3个群体的遗传多样性偏低。     

家兔BMP7基因的克隆及其生物信息学分析

在对已知部分编码序列(CDS)进行分析的基础上, 采用RT-PCR分步扩增以及RACE方法, 对家兔BMP7基因3′和5′末端未知序列进行了克隆与生物信息学分析。测序结果综合分析表明, 所获序列共计1 654 bp, 包括家兔BMP7近全长前肽、全长成熟肽CDS及3′非翻译序列(3′UTR), 将已有的序列向5′和3′端分别延伸了395 bp和628 bp。序列对比表明, 克隆的家兔BMP7 CDS部分与人、小鼠的对应序列的同源性分别为91.89%和89.32%, 预测的氨基酸序列同源性分别为96.51%和96.01%。家兔BMP7 3′UTR长446 bp, 与人、小鼠对应序列同源性分别为57.38%和45.57%; 具有2个转录终止信号位点。推测家兔BMP7成熟蛋白有BMPs特有的7个位置固定的半胱氨酸残基和TGF-β家族指纹。家兔BMP7 3′UTR区转录终止信号的可选择性可能与基因转录后调控有关。     

中华鲟(Acipenser sinensis)间的长度变异与个体内的长度异质性

用PCR技术扩增中华鲟（Acipensersinensis）线粒体DNA（mtDNA）控制区（D－loop）时,发现中华鲟天然群体内存在个体间和个体内的mtDNA长度变异现象。DNA测序表明,长度变异发生在mtDNAryloop靠近tRANpro的位置,由长约82碱基对（bp）的重复序列串联形成的。由个体内mtDNA长度变异造成的异质性个体比例为57.4％,非异质性（同质性）个体的比例为426％。非异质性个体间的mtDNA的大小也不一样,存在长度变异。在非异质性个体中,有2、3、4、5个串联重复序列形成的4种分子类型的情况,其重复序列出现的频率从高到低的循序是3→2→4→5。在异质性个体中,同一个体由2种不同分子组合的异质体最普通,占77.78％3种不同分子组合的频率次之,占18.520。4种不同分子组合的异质体比例最少,占3．70％。没有发现由5种不同分子组合的异质体。对所有异质体混合分析表明,各种类型的重复序列出现的比例与非异质体的类似,即分子大小（含重复序列数）从高到低的顺序为3→2→4→5→1。对47尾中华鲟的个体内和个体间的遗传多样性指数分析发现,有65．3％遗传变异表现在群体内的个体间,有347％的遗传变异表现在个体内。由mtDNA长度异质性造成的个体内的多样性是中华鳍物种遗传多样性的另一途径。     

茶树肌动蛋白基因（CsActin1）全长cDNA克隆与生物信息学分析

以茶树（Camellia sinensis）萌动芽为材料,根据茶树萌动芽芽抑制消减杂交文库中分离得到的肌动蛋白（actin）基因的5′-片段设计引物,利用3′-RACE技术克隆了其cDNA全长序列,该基因cDNA全长1 470 bp,命名为CsActin1（GenBank登录号HQ235647）。序列分析表明,CsActin1开放阅读框长1 134 bp,编码377个氨基酸,5′非编码区100 bp,3′非编码区236 bp。推测的蛋白质分子量为41.70 kD,等电点约为5.31,具有肌动蛋白家族的特征信号序列（YVGDEAQs.KRG和WIAKaEYDE）和肌动蛋白相关蛋白的特征信号序列（LLTEApLNPkaNR）。CsActin1与GenBank中注册的其它植物肌动蛋白核苷酸序列的相似性在80%以上,氨基酸序列相似性在95%以上。与其它植物肌动蛋白的进化树分析结果表明,茶树肌动蛋白与杨树的两个肌动蛋白间的亲缘关系最为密切。并对推导的蛋白结构进行了分析。     

中国蒙古马与国外纯血马mtDNA D-Loop高变区序列比较

比较分析了4匹中国蒙古马和4匹国外纯血马的线立体DNA（mtDNA）D-Loop高变区400bp核苷酸序列的变异情况。结果发现,4匹中国蒙古马mtDNA D-Loop高变区的平均核苷酸变异率为3.69%,而纯血马的为4.00%,其核苷酸变异类型均包括转换、颠换和缺失3种形式,其中以转换最为常见。核苷酸变异基因座多,并且存在长度变异,不同变异在个体之间差异也很大,因此说明中国蒙古马和国外纯血马的mtDNA D-Loop高变区都具有丰富的多态性。Abstract：Mitochondrial DNA D-Loop varied region 400bp sequence variations in 4 Chinese Mongolian horses and 4 External Thoroughbred horses were analyzed in this experiment. The results showed that the average nucleotide mutational rate of mtDNA D-Loop varied region in 4 Chinese Mongolian horses was 3.69%,while External Thoroughbred horses were 4.00%. Three types of mutations including transition,transversion and deletion were all found in the investigated mtDNA D-Loop regions,of which transition was the most frequent. Nucleotide mutational loci were abundant,length mutations were found and great differences were all observed among the 8 horses. It showed there existed much polymorphism in the mitochondrial DNA D-Loop varied region of Chinese Mongolian horses and External Thoroughbred horses.     

都柳江鲤、鲫和草鱼种群mtDNA控制区及遗传多样性分析

采用PCR和DNA测序技术对贵州都柳江鲤(Cyprinus carpio)、鲫(Carassius auratus)和草鱼(Ctenopharyngodon idellus)种群的mtDNA控制区序列及遗传多样性进行了研究。获得了都柳江鲤、鲫和草鱼mtDNA控制区长度分别为899~901 bp、787 bp和901~905 bp的序列。该3种鱼类控制区碱基A、T含量较高,G含量最低。识别了该3种鱼类mtDNA控制区终止序列区、中央保守区和保守序列区等保守序列。其中,除CSB-2和CSB-3碱基组成相同外,其余核心序列碱基组成存在着差异。都柳江鲤、鲫和草鱼种群mtDNA控制区分别有24、24和11个多态位点,分属12、17和8个单倍型。都柳江鲤、鲫种群遗传多样性较高,草鱼种群遗传多样性较低。因此,有必要开展都柳江草鱼种群遗传多样性的保护。     

中华鳖vasa基因克隆及在卵母细胞中的表达分析

研究利用中华鳖为研究模型进行爬行类生殖细胞发育分化成熟等生物学研究,克隆了中华鳖vasa基因的cDNA序列,全长3865 bp,包括5'端非编码区90 bp,3'端非编码区1699 bp,开放阅读框长2076 bp,共编码691个氨基酸。中华鳖Vasa氨基酸序列包含DEAD-box家族蛋白8个保守保守功能域,在N末端有4个RGG重复序列和2个GG富集区,与小鼠Vasa蛋白的同源性较高（72%）。荧光定量PCR的结果表明,中华鳖vasa mRNA主要精巢和卵巢中表达,其他体组织中均难检测到表达。卵巢冰冻切片原位杂交结果显示:中华鳖vasa mRNA在生殖细胞中特异表达;在卵子发生过程中的不同发育期卵母细胞中呈现动态的变化。即vasa mRNA在初级卵母细胞及生长期卵母细胞中表达最强,且均匀分布在细胞质中,随着卵母细胞的逐渐增大,信号逐渐减弱,直至在成熟的卵母细胞中几乎检测不到表达信号,说明vasa可能在中华鳖早期卵母细胞发育中起重要作用。同时,vasa基因可作为中华鳖生殖细胞分子标记物,根据其mRNA的表达水平来鉴别不同发育时期的卵母细胞。研究结果为进一步开展中华鳖胚胎生殖细胞发育及配子生成,特别是研究中华鳖,乃至爬行类原始生殖细胞（Primordial Germ Cells,PGCs）的起源、迁移、分化等研究奠定了基础。     

应用线粒体DNA D—loop区遗传多样性分析云南4个少数民族的遗传关系

对傣,佤,拉祜和藏族4个群体的99名个体mtDNA非编码区(D-loop)高变区I 16048－16569及I－41的563bp片优进行序列分析,计算了核酸多态度,并用Neighbro-Joining法构建系统进化树,在进化树中,99个mtDNA序列分别聚在4个群中,所有在COII／tRAN^Lys基因间序列存在9bp 缺失的个体均聚在C1如中,C2群由1个佤族个体和4个藏族个体组成,C3群中除2个藏族个体外均为其他3个民族个体,4个群体的大部分个体聚在C4群,根据核酸多态度计算的净遗传距离重建的进化树显示,傣族,佤族和拉祜族的亲缘关系较接近,与藏族距离较远,结果表明遗传距离与他们的地理分布是非常一致的,而拉枯族与相传同为氐羌后裔并有相近语言的藏族遗传距离却较远,这一结果提示这两个民族可能具有不同的起源。     

The mitochondrial DNA control region comparison studies of four hinged turtles and its phylogentic significance of the genusCuora sensu lato (Testudinata: Geoemydidae)

The complete sequences of the mitochondrial DNA (mtDNA) control region (CR) ofCistoclemmys flavomarginata, Cistoclemmys galbinifrons, Cuora aurocapitata andCyclemys atripons were amplified by long-polymerase chain reaction (Long-PCR). The lengths were 1207 bp, 1722 bp, 1379 bp and 980 bp, respectively. Combining with the CR sequence ofPyxidea mouhotii (DQ659152), we compared the CR structure, and identified three functional domains (TAS, CD and CSB) in which the conservation sequences (TAS, CSB-F, CSB-1, CSB-2 and CSB-3) were also successfully identified according to their homology to those of other turtles. These 5 turtles have the identical CSB-2 and CSB-3 sequences, and 4 of them have the same CSB-1 sequence while there is one base transversion (T → A) inCy. atripons. We analyzed the variable number of tandem repeat (VNTR) sequences or microsatellites at the 3′ end of CR. The motifs of tandem repeats (7 types) are made up of 2–8 nucleotides, and the copy numbers are from 4 to 48. All of the 5 turtles exceptCy. atripons have the “TATTATAT” repeats and are ended by TA. The results of CR structure analysis displayed that theCuora, Cistoclemmys, andPyxidea have many similarities, but differ fromCyclemys. WithIndotestudo elongate (DQ080043) andIndotestudo forstenii (DQ080044) as outgroups, using the CR sequences (1123bp) excluded the microsatellites at the 3′ end of CR, we constructed the molecular phylogenetic trees using the MP, ML and BI methods. The results showed that there was a strong support to the monophyly of theCuora group consisting ofCuora,Cistoclemmys andPyxidea, which has a close relationship withMauremys andChinemys but far fromCyclemys, which are consistent with the analysis of the CR structure of the 5 turtles.     

Comparison research and phylogenetic implications of mitochondrial control regions in four soft-shelled turtles of Trionychia (Reptilia, Testudinata)

The mitochondrial control regions (CRs) and flanking sequences of Pelodiscus sinensis, Apalone ferox, Palea steindachneri and Carettochelys insculpta were obtained using Long-PCR with gene-specific primers. The CR lengths of the four species were 1843 bp, 1356 bp, 1725 bp, and 969 bp. The base composition percentages of A+T were 60.5%, 60.7%, 65.7%, 64.7%, respectively. Combined with CR sequences of other three soft-shelled turtles published in GenBank (Pelodiscus sinensis, Korea, AY962573; Dogania subplana, AF366350; Lissemys punctata, EF050073), we compared the CR structures and identified three functional domains (TAS, CD and CSB) in which conserved sequence blocks (TAS, CSB -F, CSB-1, CSB-2 and CSB-3) were also successfully identified according to their sequence similarities to those of other turtles. The variable numbers of tandem repeats (VNTRs 1) with 50–52 bp motif were identified at 5′-end of CR among the five soft-shelled turtles P. sinensis (China), P. sinensis (Korea), A. ferox, P. steindachneri, D. subplana. The copy number of the VNTRs varied from 5 to 15. VNTRs 2 with 2–11 bp motif were identified in the 3′- end of CR among all of the six soft-shelled turtles with variable number of motifs from 4 to 29. Moreover, VNTRs 3 with 6 bp motif were identified between CSB-1 and CSB-2 of CR both in P. sinensis (China) and P. sinensis (Korea), in which the number of motifs varied from 19 to 29. The types and distribution of VNTRs of the six soft-shelled turtles were also discussed. With Alligator mississippiensis as an outgroup, combined with the CR sequences (excluding VNTRs) of other five turtles which were published in GenBank, the molecular phylogenetic trees were constructed using PAUP 4.0b10 and MrBayes ver. 3.0. The results strongly supported the monophyly of Carretochelyidae and Carettochelyidae as sister group to an assemblage of Cryptodira. Our research suggested that the earliest phylogenetic tree splits into three separated basal branches; the Pelomedusidira (Pelomedusa subrufa), the Carettochelyidae (C. insculpta), and an assemblage of Cryptodira and the C. insculpta that might be a representation of distinctive suborder.     

中华卵索线虫线粒体基因组多态性分析

为完善昆虫病原索科线虫线粒体基因组全序列数据库, 更系统地研究其基因组特征和系统演化规律, 进而为发挥该线虫生防潜力打下基础, 我们开展了中华卵索线虫Ovomermis sinensis线粒体全基因组的研究。该研究通过线粒体基因组滚环复制及酶切图谱, 揭示了中华卵索线虫线粒体基因组具有种内遗传多态性, 即群体中单体线虫具有独特的酶切条带, 且条带累加之和变化范围较大, 为16.5～24.5 kb。为进一步了解线粒体基因组多态性特征及产生的分子机制, 采用两步长PCR方法对2条代表性成虫线粒体基因组进行了测序及拼接, 得其全长分别为18 864和16 777 bp。对这2条序列的比对表明, 线粒体基因组中位于ND2和ND4之间的可变区域, 不仅基因排列顺序不同, 且存在ND3基因重复现象, 这是导致中华卵索线虫线粒体基因组呈现多态性的主要原因。通过对以上研究结果的分析及与GenBank中已有的6种索科线虫线粒体基因组序列进行比对, 概括出其线粒体基因组基本特点: ①线粒体基因排列顺序各不相同;②部分线虫线粒体基因存在重复现象, 且重复次数不同;③线粒体基因组大小存在很大差异。     

Recombination and Evolution of Duplicate Control Regions in the Mitochondrial Genome of the Asian Big-Headed Turtle,Platysternon megacephalum

Complete mitochondrial (mt) genome sequences with duplicate control regions (CRs) have been detected in various animal species. In Testudines, duplicate mtCRs have been reported in the mtDNA of the Asian big-headed turtle, Platysternon megacephalum, which has three living subspecies. However, the evolutionary pattern of these CRs remains unclear. In this study, we report the completed sequences of duplicate CRs from 20 individuals belonging to three subspecies of this turtle and discuss the micro-evolutionary analysis of the evolution of duplicate CRs. Genetic distances calculated with MEGA 4.1 using the complete duplicate CR sequences revealed that within turtle subspecies, genetic distances between orthologous copies from different individuals were 0.63% for CR1 and 1.2% for CR2app:addword:respectively, and the average distance between paralogous copies of CR1 and CR2 was 4.8%. Phylogenetic relationships were reconstructed from the CR sequences, excluding the variable number of tandem repeats (VNTRs) at the 3′ end using three methods: neighbor-joining, maximum likelihood algorithm, and Bayesian inference. These data show that any two CRs within individuals were more genetically distant from orthologous genes in different individuals within the same subspecies. This suggests independent evolution of the two mtCRs within each P. megacephalum subspecies. Reconstruction of separate phylogenetic trees using different CR components (TAS, CD, CSB, and VNTRs) suggested the role of recombination in the evolution of duplicate CRs. Consequently, recombination events were detected using RDP software with break points at ≈290 bp and ≈1,080 bp. Based on these results, we hypothesize that duplicate CRs in P. megacephalum originated from heterological ancestral recombination of mtDNA. Subsequent recombination could have resulted in homogenization during independent evolutionary events, thus maintaining the functions of duplicate CRs in the mtDNA of P. megacephalum.     

The complete mitochondrial genome of the Korean soft-shelled turtle Pelodiscus sinensis (Testudines, Trionychidae).

We isolated Korean soft-shelled turtle, Pelodiscus sinensis, mitochondrial DNA by long-polymerase chain reaction (long-PCR) with conserved primers and sequenced this mitochondrial genome (mitogenome) with primer walking using flanking sequences. The P. sinensis mitochondrial DNA has 17,042 bp and its structural organization is conserved compared to those of other reptiles and mammals. To unveil the phylogenetic relationship of the turtles, we used the NJ, MP, and ML analysis methods after inferring those sequences from the mitochondrial 16S rRNA gene. We also compared two P. sinensis variants from Korea and China using the mitochondrial genome. In this study, we report the basic characteristics of the P. sinensis mitochondrial genome, including structural organization and base composition of the rRNAs, tRNAs and protein-coding genes, as well as characteristics of tRNAs. These features are applicable for the study of phylogenetic relationships in turtles.     

Comparison of complete mitochondrial DNA control regions among five Asian freshwater turtle species and their phylogenetic relationships

The complete mitochondrial DNA (mtDNA) control regions (CR), cytochrome b (Cyt b), NADH dehydrogenase subunit 4 (ND4) and cytochrome coxidase subunit I (CO I) genes of four Asian freshwater turtles, Mauremys japonica, Ocadia sinensis, M. mutica, and Annamemys annamensis, were sequenced using universal PCR and long-PCR techniques. Combined with CR sequences of Chinemys reevesii, the composition and structure of CR of the five species were compared and analyzed. Three functional domains (TAS, CD and CSB) in CR and their conserved sequences (TAS, CSB-F, CSB-1, CSB-2, and CSB-3) were identified based on sequence similarity to those of other turtles. At the 3' end of CSB, six type motifs of variable number of tandem repeats (VNTRs) of five species were recognized, in which the TTATATTA motif may be the VNTR motif of the ancestral species of these five turtles. Comparison of nucleotide divergences among Cyt b, ND4, CO I, and CR of 11 turtle species using transitions + transversions and transversions-only methods supported the conclusion that CR evolved 2.6- to 5.7-fold faster than the other mtDNA genes. After excluding VNTRs of CR, molecular phylogenetic trees were constructed with maximum parsimony, maximum likelihood and Bayesian inference methods. The results supported an expanded clade of Mauremys, which included species formerly in Ocadia, Chinemys, Mauremys, and Annamemys; this was also reflected in the results of VNTR analysis.     

Multiple data sets, high homoplasy, and the phylogeny of softshell turtles (Testudines: Trionychidae)

We present a phylogenetic hypothesis and novel, rank-free classification for all extant species of softshell turtles (Testudines:Trionychidae). Our data set included DNA sequence data from two mitochondrial protein-coding genes and a approximately 1-kb nuclear intron for 23 of 26 recognized species, and 59 previously published morphological characters for a complimentary set of 24 species. The combined data set provided complete taxonomic coverage for this globally distributed clade of turtles, with incomplete data for a few taxa. Although our taxonomic sampling is complete, most of the modern taxa are representatives of old and very divergent lineages. Thus, due to biological realities, our sampling consists of one or a few representatives of several ancient lineages across a relatively deep phylogenetic tree. Our analyses of the combined data set converge on a set of well-supported relationships, which is in accord with many aspects of traditional softshell systematics including the monophyly of the Cyclanorbinae and Trionychinae. However, our results conflict with other aspects of current taxonomy and indicate that most of the currently recognized tribes are not monophyletic. We use this strong estimate of the phylogeny of softshell turtles for two purposes: (1) as the basis for a novel rank-free classification, and (2) to retrospectively examine strategies for analyzing highly homoplasious mtDNA data in deep phylogenetic problems where increased taxon sampling is not an option. Weeded and weighted parsimony, and model-based techniques, generally improved the phylogenetic performance of highly homoplasious mtDNA sequences, but no single strategy completely mitigated the problems of associated with these highly homoplasious data. Many deep nodes in the softshell turtle phylogeny were confidently recovered only after the addition of largely nonhomoplasious data from the nuclear intron.     

鸮形目4种鸟类线粒体调控区全序列的测定与比较研究

利用Long-PCR和Primer Walking的方法对鸮形目的短耳鸮、长耳鸮、纵纹腹小鸮、灰林鸮4种鸟类的线粒体调控区进行了全序列测定。结果表明：短耳鸮的调控区跃度为3290bp;长耳鸮为2848bp;纵纹腹小鸮为2444bp;灰林鸮为1771bp。短耳鸮的调控区长度是4种鸮中最大的,并且是目前已知最大的鸟类线粒体调控区。这4种鸮类调控区的基本结构和其他鸟类相似,按照碱基变化速率的不同可以分为3个区：碱基变化速率较快的外围区域Ⅰ、Ⅲ和保守的中间区域Ⅱ。这4种鸟类调控区的3’端均存在大量的串联重复序列,短耳鸮为126bp单元重复7次和78bp单元重复14次;长耳鸮为127bp单元重复8次和78bp单几重复6次;纵纹腹小鸮有3个重复单元,分别为89bp单元重复3次、77bp单元重复4次和71bp单元重复6次;灰林鸮仅有1个单元的串联重复为78bp重复5次。调控区中串联重复序列可能是由链的滑动错配产生,另外这些重复序列都能形成热力学稳定的多重茎环二级结构,而且在重复序列中还发现一些保守基序,这说明重复序列可能具有一定的生理功能,影响调控区的调重控功能从而影响线粒体基因组的复制和转录。