基于16S rRNA基因测序技术分析原发性胆汁性胆管炎伴抑郁小鼠粪便样本中肠道菌群的变化

背景:肠道菌群失调或紊乱与脑和肝脏疾病之间存在联系,肠道菌群可能通过肠⁃肝⁃脑轴影响原发性胆汁性胆管炎(PBC)和抑郁的发生和发展。目的:应用16S rRNA基因测序技术分析PBC伴抑郁小鼠的肠道菌群情况。方法:将12只雌性小鼠随机分为对照组、胆汁淤积组、胆汁淤积+抑郁组和治疗组。对照组小鼠给予正常饲料和水喂养;胆汁淤积组小鼠采用含0.1%DDC的饲料连续喂养2周构建胆汁淤积模型;胆汁淤积+抑郁组小鼠先采用慢性温和不可预期应激方式刺激2周,再以含0.1%DDC的饲料喂养2周构建胆汁淤积+抑郁模型;治疗组小鼠在构建胆汁淤积+抑郁模型的基础上,腹腔注射盐酸氯米帕明(7.5 mg·kg^(-1)·d^(-1))2周。造模期间观察小鼠的行为学变化。造模结束后各组小鼠称重,行负重游泳试验、强迫游泳试验、悬尾试验和肝组织HE染色;采集新鲜粪便,基于16S rRNA基因测序技术分析小鼠肠道菌群的变化。结果:与对照组相比,胆汁淤积组和胆汁淤积+抑郁组小鼠体质量明显减轻(P<0.05),抑郁样行为明显加重(P<0.05);与胆汁淤积+抑郁组相比,治疗组小鼠体质量明显升高(P<0.05),抑郁样行为明显减轻(P<0.05)。胆汁淤积组、胆汁淤积+抑郁组和治疗组小鼠肝组织出现不同程度的胆汁淤积性损伤;与胆汁淤积+抑郁组相比,治疗组肝脏病理损伤明显减轻。小鼠粪便样本经测序抽平处理后获得个5491个操作分类单元(OTU),4组共有的OTU为162个。对照组与胆汁淤积组、胆汁淤积+抑郁组和治疗组小鼠粪便中微生物多样性和群落组成存在较大差异。在门水平上,胆汁淤积组厚壁菌门(Firmicutes)丰度明显升高;胆汁淤积+抑郁组变形菌门(Proteobacteria)丰度明显升高;治疗组厚壁菌门和变形菌门丰度均明显升高,拟杆菌门(Bacteroidetes)丰度明显下降。对组间差异显著的物种行LEfSe分析发现,LDA值>4的微生物类群有38个。结论:PBC伴抑郁小鼠的肠道菌群结构和多样性均发生显著变化,抗抑郁治疗能改善肠道菌群的丰度和多样性,通过调节肠道菌群治疗PBC伴抑郁有可能成为一种新的治疗策略。

16S-rRNA测序技术分析早产儿肠道细菌基因组指导新生儿坏死性小肠结肠炎手术时机选择的研究

目的探讨16S-rRNA测序技术分析早产儿肠道细菌基因组指导新生儿坏死性小肠结肠炎(NEC)手术时机选择。方法前瞻性选择2021年1月至2022年6月百色市人民医院需要手术治疗的NEC患儿30例为观察组,选择同期内科保守治疗的Ⅰ期15例和Ⅱa期15例患者为对照组。采用HiSeq测序平台,借助双端测序模式进行高通量二代测序,比较两组多样性指数、优势均属丰度及不同优势菌比值等;绘制受试者操作特征(ROC)曲线,分析16S-rRNA测序技术的指导价值。结果60例患者60份样本中共获得细菌84个,且两组样品均为副杆状菌属最高,其次为Ruminococcus、Blautia、Aeromonas和Fusobacterium;两组肠道菌群上述菌门丰度存在差异(P<0.05);从粪便标本中共获得有效序列7347481条,人均130857条,测序平均覆盖度为(92.15±5.61)%;观察组手术治疗的NEC患儿中香农-维纳(Shannon)及辛普森多样性(Simpson)指数低于对照组内科保守治疗患儿,差异有统计学意义(P<0.05);ROC曲线结果表明,16S-rRNA测序技术在NEC患儿手术时机选择中的指导AUC为0.846,指导灵敏度为87.51%,特异度为83.16%。结论NEC患儿常伴有肠道细菌基因组改变,且菌群结构的变化与患儿病情严重程度有关,通过16S-rRNA测序技术能指导NEC患儿手术治疗时机。

High-throughput sequencing of 16S r RNA amplicons characterizes gut microbiota shift of juvenile sea cucumber Apostichopus japonicus feeding with three antibiotics

Sea cucumber Apostichopus japonicus is an important marine economic species in Asian countries due to its profound nutritional and medicinal value. So far, with the rapid development of intensifi ed artifi cial aquaculture of sea cucumbers, the use of antibiotics is still an inexpensive and dispensable way to treat pathogenic infections, especially during the nursery phase. However, there is little information on the eff ects of antibiotics on the intestinal microbiota of sea cucumber. Therefore an Illumina based sequencing method was used to examine the intestinal bacterial composition of juvenile A . japonicas following diets with three typical antibiotics (tetracycline, erythromycin, and norfl oxacin) under 15, 30, and 45 d. The fi ndings reveal that diff erent antibiotics have distinct eff ects on the growth performance of juvenile sea cucumbers. However, the richness and diversity of microbiota were barely aff ected by antibiotics but the community composition alterations indicated that the three antibiotics exhibited their respective patterns of reshaping the intestinal bacteria of juvenile sea cucumbers. In common, the abundance of some sensitive genera with helpful functions, such as Thalassotalea , Shewanella , Sulfi tobacter , and Halomonas decreased signifi cantly with exposure to antibiotics and the abundance of multiple potential pathogenic- and suspected antibiotic-resistant microorganisms like Arcobacter , Leucothrix , and Clostridium_sensu_stricto_1 was found increased signifi cantly in the antibiotic groups. These results suggest that low doses of antibiotics could aff ect the composition of the intestinal microbiota of sea cucumbers and might increase the risk of infection of the hosts. This study could help us to explore how antibacterial compounds modify the gut microbiota of sea cucumbers and provide theoretical guidance in hatchery management by scientifi c antibiotic use in sea cucumber mariculture.

Fecal microbiota of three bactrian camels(Camelus ferus and Camelus bactrianus) in China by high throughput sequencing of the V3-V4 region of the 16S rRNA gene

This study aimed to reveal the microbial diversity in the fecal samples of bactrian camels using the 16 S r RNA sequencing analysis on the Illumina Mi Seq platform. Three fecal samples were collected from two geographical regions in China. Operational taxonomic unit（OTU） clustering was performed by identifying an OTU at 97% sequence identity. The alpha and beta diversities were applied to estimate the differences in microbial diversity among the three fecal samples. Totally, 4409, 3151 and 4075 OTUs in the fecal samples were identified in the Lop Nor wild camel（Camelus ferus）, the domestic camel（C. bactrianus） and Dunhuang wild camel（C. ferus）, respectively. The majority of bactreria were affiliated with phylum Firmicutes and Bacteroidetes in the three samples. The wild camels had higher gastrointestinal tract microbial diversity than the domestic one, while the microbial composition of the Lop Nor wild camel shared higher similarity with domestic camel at the genus and family levels than that of the Dunhuang wild camel did. Our results may provide a theoretical basis for assessing their health conditions and may thus be useful for protecting the critically endangered species of C. ferus.

Correlation analysis of breast fibroadenoma and the intestinal flora based on 16S rRNA sequencing

Objective To analyze the characteristics of the intestinal microflora in patients with breast fibroadenoma using 16S ribosomal RNA(rRNA)high-throughput sequencing.Methods Fecal samples from 20 patients with breast fibroadenoma and 36 healthy subjects were randomly collected and analyzed using high-throughput sequencing technology for 16S rRNA V4 region sequencing,and the alpha diversity(Chao index,Shannon index)was calculated using Mothur(v.1.39.5)software.Beta diversity was analyzed using QIIME(v1.80).SPSS software(version 23.0)and the t-test of two independent samples were used to analyze differences in the abundance of bacteria between the two groups.Results Compared with that in the healthy control group,theαdiversity of the intestinal microflora in breast fibroadenoma patients increased,but the difference was not statistically significant(P>0.05).At the phylum level,significant differences were observed between the two groups.The abundance of Firmicutes was higher in the breast fibroadenoma group(P<0.05),whereas the abundance of Synergistetes was higher in the healthy control group(P<0.005).A total of five bacterial genera showed significant differences between the two groups:the breast fibroadenoma group showed higher levels of Bautia(P<0.005),Coprococcus(P<0.005),Roseburia(P<0.05),and Ruminococcus(P<0.005),whereas Sutterella was more abundant in the healthy control group than in the breast fibroadenoma group(P<0.05).Conclusion The diversity and abundance of the intestinal flora in patients with breast fibroadenoma are significantly different from those in healthy subjects,suggesting that an imbalance in the intestinal flora is correlated with the occurrence of breast fibroadenoma.

Cloning and Sequence Analysis of 16S rRNA and COI Gene in Mitochondrial DNA of Scortum barcoo

[Objective] The aim was to provide molecular biological basis for the researches on the genetic resources,genetic relationship among species and phyletic evolution of S.barcoo.[Method] PCR amplification and sequencing were used to study the 16S rRNA and COI gene fragments.[Result] As for 16S rRNA gene fragments,nucleotide sequences of 791 bp were obtained,and the A,T,G and C contents in this fragment were 31.6%,21.4%,20.4% and 26.7%respectively.As for the COI gene fragments,the size was 631 bp and the A,T,G And C contents were 27.7%,23.6%,29.8% and 18.9% respectively.Among these two gene fragments,the content of GC was lower than AT,and AT/GC of these two fragments was 1.13 and 1.05 respectively.[Conclusion] The genetic characteristics of gene fragments of 16S rRNA and COI of S.barcoo suggested that the variation in the same species was relatively low.The sequences of 16S rRNA gene in three samples the same,while the sequences of COI gene was also the same,indicating that these two gene of S.barcoo were conservative.

16S rRNA Technology Approach to Explore Mechanism of Qishen Decoction in Improving Nonalcoholic Fatty Liver Fibrosis

Objective: To explore the mechanism of Qishen Decoction in the treatment of nonalcoholicfatty liver fibrosis (NAFLF) by 16S rRNA technology. Methods: NAFLF rat model was established by intraperitoneal injection of carbon tetrachloride combined with high fat diet. During the modeling period, each group was given corresponding drug intervention treatment for 8 weeks. The changes of liver histopathology, serum liver function, lipid and liver fibrosis were analyzed and compared after treatment in each group. The contents of cecum end were collected and the intestinal flora was sequenced by Illumina Miseq platform. Results: Compared with the model group, Qishen Decoction could significantly improve the pathological changes of liver tissue in NALFL rats, and reduce the NAS score, oil red staining area, collagen staining area, ALT, AST, TC, TG, HA, LN, PIIINP and C-IV levels, with significant differences (P<0.05). In addition, compared with the control group, the intestinal flora abundance and diversity of the rats in the model group were significantly reduced (P<0.05), Qishen decoction could significantly increase the abundance and diversity of the intestinal flora of NAFLF rats (P<0.05), and upregulated the abundance of Bacteroidales_S24-7_group_unclassified, Bifidobacterium, Lactobacillu s, Turicibacter, Parabacteroides, Phascolarctobacterium, Lachnospiraceae_NK4A136_group, Coriobacteriaceae_UCG-002, Parasutterella, Odoribacter, Anaerostipes, Ruminococcaceae_unclassified, Allobaculum, Romboutsia, Holdemanella, and Haem ophilus, the difference was statistically significant (P<0.05). Conclusion: Qishen Decoction inhibits liver fibrosis in NAFLF rats by restore the diversity of intestinal flora and increase the abundance of probiotics in intestinal tract.

Identification of Bacterial Fish Pathogens in Brazil by Direct Colony PCR and 16S rRNA Gene Sequencing

Intensive fish farming systems in Brazil have increased the disease incidence, mainly of bacterial origin, due to higher stocking density, high organic matter levels and poor quality of the aquatic environment that causes high mortality rates during outbreaks. The identification of pathogenic species using a fast and reliable method of diagnosis is essential for successful epidemiological studies and disease control. The present study evaluated the use of direct colony PCR in combination with 16S rRNA gene sequencing to diagnose fish bacterial diseases, with the goal of reducing the costs and time necessary for bacterial identification. The method was successful for all 178 isolates tested and produced bands with the same intensity as the standard PCR performed using pure DNA. In conclusion, the genetics methods allowed detecting the most common and important pathogens in Aquaculture, including 12 species of occurrence in Brazilian fish farms. The results of the present study constitute an advance in the available diagnostic methods for bacterial pathogens in fish farms.

基于16S rRNA测序探讨银屑病1号方对银屑病患者皮肤微生态的影响

[目的]采用16S rRNA基因测序技术,观察银屑病1号方对银屑病患者治疗前后皮肤微生态的影响。[方法]选取在杭州市第三人民医院接受治疗的30例寻常型银屑病患者,口服银屑病1号方治疗后,取治疗前后皮肤样本,同时选取健康对照组30例,采用16S rRNA基因测序技术,分析治疗前后菌群多样性及菌群分布差异。[结果]银屑病1号方治疗后患者组操作分类单元(operational taxonomic units,OTUs)数目较治疗前患者组显著减少(P<0.05)。在门水平上,治疗后患者厚壁菌门、放线菌门增加,变形菌门、拟杆菌门含量减少;在属水平上,治疗后患者痤疮丙酸杆菌属、葡萄球菌属、棒状杆菌属丰度增加,链球菌属丰度下降。秩和检验显示,治疗前患者组中相对丰度较高(>1%)的差异物种有厚壁菌门、变形菌门、拟杆菌门、葡萄球菌属、金黄杆菌属、鞘氨醇单胞菌属。功能预测分析,患者组的皮肤微生态功能与糖代谢、辅因子及维生素代谢和氨基酸生物合成的相关基因通路与健康对照组比较差异有统计学意义(P<0.01)。[结论]银屑病1号方可通过改善皮肤微生态治疗银屑病。

16S rRNA Gene-Based Metagenomic Analysis of Soil Bacterial Diversity in Brazzaville, Republic of the Congo

Soil contains a great diversity of microorganisms, among which are bacteria. This study aimed to explore bacterial diversity in soil samples in Brazzaville in the Republic of the Congo. Environmental DNA was extracted. The illumina MiSeq sequencing was held and the diversity indices have been computed. Illumina MiSeq sequencing revealed 21 Phyla, four of which were abundant: Proteobacteria, Acidobacteria, Actinobacteria and Bacteroidetes. Soil microbial communities in the studied samples were phylogenetically diverse but with a stable community structure. 17 classes are represented with relative abundances of Rihzobiales, Bacillales, Actinomycetales and Acidobacteriales. 40 families, the Alphaproteobacteria, the Bacilli and the 12 Actinobacteria. 83 orders among which the Rhizobiales are the most abundant followed by Bacillales and the least abundant followed by the Flavobacteriaceae. Of the 28 genera listed, the Bradyrhizobium is the most dominant in Mw3 and Mw4. 25 listed species, Bradyrhizobium, Bacillus, Actinoplanes, and Candidatu coribacter Acidobacterium are the most abundant species. The Shannon indices of Mw3 and Mw4 are equal, the H’max of Mw4 is greater than the H’max of Mw3. The Simpson index of Mw4 is equal to the Simpson index of Mw3, and the Pielou index (J) of Mw4 is less than the R of Mw3, but very close. This study opens interesting perspectives on the knowledge and exploitation of telluric bacteria in several areas of life.

Preliminary study on mitochondrial 16S rRNA gene sequences and phylogeny of flatfishes (Pleuronectiformes)

A 605 bp section of mitochondrial 16S rRNA gene from Paralichthys olivaceus, Pseudorhombus cinnamomeus, Psetta maxima and Kareius bicoloratus, which represent 3 families of Order Pleuronectiformes was amplified by PCR and sequenced to show the molecular systematics of Pleuronectiformes for comparison with related gene sequences of other 6 flatfish downloaded from GenBank. Phylogenetic analysis based on ge- netic distance from related gene sequences of 10 flatfish showed that this method was ideal to explore the rela- tionship between species, genera and families. Phylogenetic trees set-up is based on neighbor-joining, maximum parsimony and maximum likelihood methods that accords to the general rule of Pleuronectiformes evolution. But they also resulted in some confusion. Unlike data from morphological characters, P. olivaceus clustered with K. bicoloratus, but P. cinnamomeus did not cluster with P. olivaceus, which is worth further studying.

Genetic Diversity in Populations of Sepiella maindroni Using 16S rRNA Gene Sequence Analysis

Part of the 16S rRNA gene is amplified with PCR and sequenced for 5 populations of com-mon Chinese cuttlefish Sepiella maindroni: three from the South China Sea, one from East China Sea and one from Japan. The result shows that a total of 5 nucleotide positions are found to have gaps or insertions of base pairs among these individuals, and 13 positions are examined to be variable in all the sequences, which range from 494 to 509 base pairs. All of the individuals are grouped into 7 haplotypes (h1-h7). No marked genetic difference is observed among those populations. All of the individuals from Nagasaki belong to hl and the h3 haplotype is found only in the coastal waters of China. A(?)G transition in Nucleotide 255 is suggested to be taken as a kind of genetic marker to identify the populations distributed in East-South China Sea and the Nagasaki waters of Japan.

Relationship between hyperlipidemia and the gut microbiome of rats, characterized using high-throughput sequencing

Objective:To determine the effects of a high-fat diet(HFD)on the gut microbiome in rats,to explore the relationship between the intestinal flora and blood lipid profile.Methods:SpragueeDawley rats were fed an HFD for four weeks to induce hyperlipidemia,then 16S rRNA sequencing was used to compare the intestinal flora between hyperlipidemic and control diet-fed rats.Results:The microbiome of rats fed an HFD for four weeks differed from that of control diet-fed rats.Bacterial species that were less abundant were most affected by HFD feeding,among which were many pathogenic species,which became significantly more abundant.Eighteen genera were present in significantly different numbers in hyperlipidemic and control rats,more than half of which have been linked to infection and inflammation,or energy intake and obesity.The results indicated a type of stress response of the flora to a high-fat environment.In addition,the age of the rats tended to influence the gut microbial composition.Conclusion:These findings suggest that HFD may induce hyperlipidemia by affecting the gut microbial composition.Changes in the abundance of pro-inflammatory and pathogenic bacteria,and those that influence energy intake and obesity,may be important mediators of this.

16S rRNA Gene Sequence Analysis of Snow Leopard, Gray Wolf, Horse and Bactrian Camel in Mongolia

In this study, mitochondrial 16S rRNA sequences of snow leopard, gray wolf, domestic horse and Bactrian camel inhabited or domesticated in Mongolian territory were obtained by using polymerase chain reaction （PCR） based on universal primers for 16S rRNA （F-5＇-AACGAGCCTGGTGATA-3＇ and R-5＇-CTCCGGTCTGAACTCAGATCACGTA-3＇）. The 16S rRNA sequence was 1,048 bp to 1,086 bp in length, and each sequence was compared to other related species （Felidae, Camelidae, Equidae and Canidae） by using NCBI Basic Local Alignment Search Tool （BLAST）. Results showed that sequences were highly similar to sequences in GenBank database （93%-99%）. Then phylogenetic analysis was performed based on about 1,100 bp sequence of 16S rRNA for Panthera uncia, Canis lupus, Equus caballus, Camelus bactrianus and other related species. The result revealed that P. uncia and P. leo were sister species, C. bactrianus and C. ferus were more closely related species, and wolf and dog were the almost similar species. This finding could be important for designing species specific primers for PCR based analysis of animal species identification and forensic veterinary medicine.

Evaluation of Real-Time 16S rDNA PCR and Pyrosequencing for Routine Identification of Bacteria in Joint Fluid and Tissue Specimens

16S rDNA PCR and sequencing are powerful tools for bacterial detection and identification, although their routine use is not currently widespread in the field of clinical microbiology. The availability of pyrosequencing now makes 16S rDNA assays more accessible to routine diagnostic laboratories, but this approach has had limited evaluation in general diagnostic practice. In this study we evaluated a real-time 16S rDNA PCR and pyrosequencing assay for use in a routine microbiology laboratory, by retrospectively testing joint fluid and joint tissue specimens received for conventional culture. We found that use of the real-time 16S rDNA assay was clinically valuable in this specimen type because it enabled us to identify a small number of culture-negative infections. Although faster and less labour-intensive, we found that the utility of pyrosequencing for pathogen identification is still hampered by shorter read lengths compared to conventional (Sanger) sequencing. Combining results from both molecular and conventional culture methods, bacteria were only detected in 11.8% specimens in this study. However, the detection rate was increased to 18.6% if specimens were only included from patients with a documented clinical suspicion of infection. In conclusion, while pyrosequencing had significant advantages in speed and ease-of-use over conventional sequencing, multiple reactions will be required to deliver comparable species-level identification, thus negating many of the benefits of using the technique. We found that 16S rDNA PCR and sequencing should be rationally targeted on the basis of good clinical information in the routine diagnostic setting, and not used as a general screening test for the exclusion of bacterial infection in joint specimens.

Causal Relationship Between Gut Microbiota and Liver Cirrhosis:16S rRNA Sequencing and Mendelian Randomization Analyses

Background and Aims:Accumulating evidence highlights the association between the gut microbiota and liver cirrhosis.However,the role of the gut microbiota in liver cirrhosis remains unclear.Methods:We first assessed the differences in the composition of the bacterial community between CCl4-induced liver cirrhosis and control mice using 16S rRNA sequencing.We then performed a two-sample Mendelian randomization(MR)analysis to reveal the underlying causal relationship between the gut microbiota and liver cirrhosis.Causal relationships were analyzed using primary inverse variance weighting(IVW)and other supplemental MR methods.Furthermore,fecal samples from liver cirrhosis patients and healthy controls were collected to validate the results of the MR analysis.Results:Analysis of 16S rRNA sequencing indicated significant differences in gut microbiota composition between the cirrhosis and control groups.IVW analyses suggested that Alphaproteobacteria,Bacillales,NB1n,Rhodospirillales,Dorea,Lachnospiraceae,and Rhodospirillaceae were positively correlated with the risk of liver cirrhosis,whereas Butyricicoccus,Hungatella,Marvinbryantia,and Lactobacillaceae displayed the opposite effects.However,the weighted median and MR-PRESSO estimates further showed that only Butyricicoccus and Marvinbryantia presented stable negative associations with liver cirrhosis.No significant heterogeneity or horizontal pleiotropy was observed in the sensitivity analysis.Furthermore,the result of 16S rRNA sequencing also showed that healthy controls had a higher relative abundance of Butyricicoccus and Marvinbryantia than liver cirrhosis patients.Conclusions:Our study provides new causal evidence for the link between gut microbiota and liver cirrhosis,which may contribute to the discovery of novel strategies to prevent liver cirrhosis.

中国对虾16SrRNA基因序列多态性的研究

利用PCR技术扩增获得中国对虾 (Penaeuschinensis)线粒体DNA的 16SrRNA基因片段 ,通过测定该基因片段的序列 ,分析了取自我国烟台、长岛、青岛近海和宁波养殖的 17只中国对虾遗传多态性。结果发现 ,不同地理种群存在丰富的DNA序列多态性 ,17只个体具有 17种基因型 ,在扩增的长为 5 2 3bp的基因片段中 ,共检测到 3 7个多态性核苷酸位点 ( 7 0 7% )。UPGMA法构建的分子系统树表明不同地理种群中国对虾存在一定程度的遗传分化 ,长岛群体与烟台群体遗传关系较近 ,宁波群体次之 ,青岛群体为相对独立的一支。

福建华溪蟹线粒体DNA COI和16S rRNA基因序列的遗传多样性

目的探讨福建华溪蟹(Sinopotamon fukienense)的遗传多样性。方法采用PCR结合DNA测序技术,测定S.fukienense的线粒体COI和16SrRNA基因序列的组成。经比对获得639bp长度的COI基因序列和526bp的16SrRNA基因序列,以对比分析S.fukienense的遗传多样性。结果 S.fukienense基于COI基因核苷酸多样性(Pi)为0.048 4,高于其基于16SrRNA基因核苷酸多样性(Pi)为0.021 6。同时,S.fukienense基于COI基因单倍型间的平均遗传距离(P)为0.048,大于其基于16SrRNA基因单倍型间的平均遗传距离(P)0.026。结论 COI序列在分析S.fukienense遗传异变时的作用更优于16SrRNA基因序列。

5种经济海胆线粒体16S rRNA基因片段的序列分析

对光棘球海胆、中间球海胆、马粪海胆,海刺猬和紫海胆线粒体DNA 16SrRNA基因片段进行了PCR扩增和测序,得到395 bp的可信片段。通过ClustalX 1.83和Mega 3.0软件对所得线粒体16SrRNA片段序列进行比较,共检测到118个碱基变异,其中简约信息位点为33个。应用Mega 3.0计算各种间的相对遗传距离,以糙海参为外类群,得到NJ系统树和MP系统树,系统树各分支的置信度由“Bootstrap”1000次循环检验。结果表明,马粪海胆与光棘球海胆的亲缘关系较近,其次为中间球海胆,而紫海胆、海刺猬与这3种海胆的关系相对较远。

两种大眼蟹线粒体16S rRNA基因序列分析

测定了宽身大眼蟹和日本大眼蟹线粒体16SrRNA基因部分片段的序列,其长度均为517bp。二者的核苷酸序列A,T,G,C的含量相似:宽身大眼蟹分别为33.3%,35.6%,19.9%,11.2%;日本大眼蟹分别为35.2%,35.4%,18.4%,11.0%。不包括6处插入/缺失位点,两序列间有63个变异位点,核苷酸差异率为12.26%,其中转换32个、颠换31个,转换与颠换比约为1.0。对国内外大眼蟹的24条长度为415bp的16SrRNA基因同源序列进行分析,A+T的平均含量为71.7%,明显高于G+C的平均含量,且存有变异位点171个,简约信息位点137个。中国和日本的日本大眼蟹之间的核苷酸差异率为4.42%,表明二者已有明显的遗传分化;中国的日本大眼蟹与日本的万岁大眼蟹之间的核苷酸差异率仅为0.21%,表明二者有可能为同一物种。上述结果得到了系统发生树拓扑结构的支持。