Gene cloning and sequence analysis of the cold-adapted chaperones DnaK and DnaJ from deep-sea psychrotrophic bacterium Pseudoalteromonas sp. SM9913

Pseudoalteromonas sp. SM9913 is a phychrotmphic bacterium isolated from the deep-sea sediment. The genes encoding chaperones DnaJ and DnaK of P. sp. SM9913 were cloned by normal PCR and TAIL - PCR （GenBank accession Nos DQ640312, DQ504163 ）. The chaperones DnaJ and DnaK from the strain SM9913 contain such conserved domains as those of many other bacteria, and show some cold-adapted characteristics in their structures when compared with those from psychro-, meso-and themophilic bacteria. It is indicated that chaperones DnaJ and DnaK of P. sp. SM9913 may be adapted to low temperature in deep-sea and function well in assisting folding, assembling and translocation of proteins at low temperature. This research lays a foundation for the further study on the cold-adapted mechanism of chaperones DnaJ and DnaK of cold-adapted microorganisms.

Molecular Cloning and cDNA Sequence Analysis of Two New Lepidopteran OR83b Orthologue Chemoreceptors

The aim of this study was to isolate the full-length cDNA sequences of an unusually highly conserved olfactory receptor （orthologue to the Drosophila melanogaster DOR83b） from the antennae of Spodoptera exigua and S. litura by using reverse transcription-polymerase chain reaction （RT-PCR） and rapid amplification of cDNA ends （RACE） methods. Bioinformatics methods were used to further analyze the cDNA sequences and putative amino acid sequences. The two full-length cDNA sequences from olfactory receptor （OR） of male S. exigua and S. litura were named as SexiOR2 and SlitOR2, respectively. SexiOR2 and SlitOR2 consisted of nucleotide sequence of 1 906 and 2 483 bp, respectively, and both with deduced amino acid sequences of 473 residues. The sequence analysis indicated that the deduced amino acid sequences of the cDNA shared the high homologies with OR83b orthologue chemoreceptor sequences from previously reported moths, implying that the cDNA sequences were of OR83b orthologue chemoreceptor genes.

Telomerase activity, TRAP, DNA sequence analysis

Telomeric repeat amplification protocol (TRAP) is now a conventional assay for detecting telomerase activity. However, this method presents problems owing to tedious quantitation, radioisotopic handling. In order to alleviate these inconveniences, a novel telomerase DNA sequencing assay together with TRAP to detect human telomerase activity was developed. It was used to detect telomerase activity in Hela, HLF, MCF, K562, SMMC 7721 cells, Leukocytes and RNase pretreated or heat treated cells as control. Telomerase activity assayed by this method was positive when the number of K562 cells examined was 102,103, and 104. The telomerase activity depended on the number of K562 cells used in the assay. Telomerase activity of Rnase pretreated cells or heat treated cells, and human normal peripheral blood leukocyte(Leu) were negative. The result of this method was available within a few hours and was handled without radioisotope. Further studies should be taken to detect telomerase activity in quantitation.

Sequence analysis of the ITS region and 5.8S rDNA of Porphyra haitanensis

The sequences of the ITS(internal transcribed spacer) and 5.8S rDNA of three cultivated strains of Porphyra haitanensis thalli(NB,PT and ST) were amplified,sequenced and analyzed.In addition,the phylogenic relationships of the sequences identified in this study with those of other Porphyra retrieved from GenBank were evaluated.The results are as follows:the sequences of the ITS and 5.8S rDNA were essentially identical among the three strains.The sequences of ITS1 were 331 bp to 334 bp,while those of the 5.8S rDNA were 158 bp and the sequences of ITS2 ranged from 673 bp to 681 bp.The sequences of the ITS had a high level of homology(up to 99.5%) with that of P.haitanensis(DQ662228) retrieved from GenBank,but were only approximately 50% homologous with those of other species of Porphyra.The results obtained when a phylogenetic tree was constructed coincided with the results of the homology analysis.These results suggest that the three cultivated strains of P.haitanensis evolved conservatively and that the ITS showed evolutionary consistency.However,the sequences of the ITS and 5.8S rDNA of different Porphyra species showed great variations.Therefore,the relationship of Porphyra interspecies phyletic evolution could be judged,which provides the proof for Porphyra identification study.However,proper classifications of the subspecies and the populations of Porphyra should be determined through the use of other molecular techniques to determine the genetic variability and rational phylogenetic relationships.

Molecular Cloning and Sequence Analysis of the Toc33 cDNA in Brassica napus Line Cr3529

Two primers, designed according to the Arabidoposis thaliana Toc33 sequence, were used to amplify the full coding region of the Toc33 cDNAs in leaves of a chlorophyll-reduced (Cr) mutant Cr3529 and its wild type 3529, Brassica napus, by RT-PCR technique. The RT-PCR results showed that the fragment homologous to Toc33 was expressed in Cr3529 as well as 3529 seedlings. PCR fragments were inserted into the pMD18-T vector and transferred into E. coli, then two cDNA clones, BnToc33-c and BnToc33, were obtained. Sequence analysis showed that the two sequences were 894 bp and the nucleotide and the deduced amino acid sequences were highly homologous to those of A. thaliana. There were three diverged nucleotides between the Cr3529 and the 3529 Toc33 cDNAs, i.e., GGT/AGT, TTG/TTT, AGG/AGT, all of which belonged to missense mutation. The amino acid replacement ((Leu/Phe) caused by TTG/TTT mutation located in the membrane anchor domain may result in chlorophyll-reduced character in Cr3529.

Cloning and Sequence Analysis of cDNA Encoding MRJP3 of Apis cerana cerana

By screening the worker （Apis cerana cerana） heads cDNA library using a fragment of the mrjp3 gene of Apis cerana as probe, 120 positive clones were obtained. The clone containing A. cerana cerana MRJP3 （AccMRJP3） cDNA was selected. Based on the sequencing of the inserts of the positive clone, a sequence of AccMRJP3 cDNA which is 1 887 bp long including a poly （A） tail was obtained. The AccMRJP3 cDNA encompassed an open-reading frame （ORF） with 1 779 bp encoding 593 amino acids. The un-translated regions （UTR） of the 5′ end and 3′end are 46 bp and 160 bp in length, respectively. Similar to AmMRJP3 and AdMRJP3, the putative AccMRJP3 also has a repetitive region. The comparison of the repetitive region of AccMRJP3, AmMRJP3 and AdMRJP3 shows some differences between them.

A hybrid swarm population of Pinus densiflora × P. sylvestris inferred from sequence analysis of chloroplast DNA and morphological characters

To confirm a hybrid swarm population of Pinus densiflora × P. sylvestris in Jilin, China, we used needles and seeds from P. densiflora, P. sylvestris, and P. densiflora × P. sylvestris collected from natural stands or experimental stations to study whether shoot apex morphology of 4-year old seedlings can be correlated with the sequence of a chloroplast DNA simple sequence repeat marker （cpDNA SSRs）. Total genomic DNA was extracted and subjected to sequence analysis of the pine cpDNA SSR marker Pt15169. Results show that morphological characters from 4-year old seedlings did not correlate with sequence variants of this marker. Marker haplotypes from all P. sylvestris trees had a CTAT element that was absent from all sampled P. densiflora trees. However, both haplotype classes involving this insertion/deletion element were found in a P. densiflora × P. sylvestris population and its seedling progeny. It was concluded that the P. densiflora × P. sylvestris accessions sampled from Jilin, China resulted from bi-directional crosses, as evidenced by both species’ cpDNA haplotypes within the hybrid swarm population.

Molecular Cloning and Sequence Analysis of Chitin Synthase cDNA from Mamestra brassicae (L.) (Lepidoptera: Noctuidae) Cuticle

Chitin is the most widespread amino polysaccharide in nature. Chitin synthase （CHS） plays an important role in chitin formation in the cuticle and the peritrophic membrane （PM） lining the midgut. Total RNA was isolated from the cuticle of Mamestra brassicae （L.） fourth instar larva, cDNA sequence was cloned by RT-PCR and Rapid Amplification of cDNA Ends （RACE）. cDNA 5 220 bp in length, contained an open reading frame of 4 704 bp coding for a polypeptide of 1 567 amino acid residues with a predicted molecular weight of 178.3 ku and its pI was 6.42. The deduced amino acid sequence from Mi brassicae （L.） shared the high level of identity with chitin synthase sequences from other insects, especially lepidopteran insects, cDNA sequence has been deposited with GenBank under accession No. GQ281761

Intraspecific Phylogenetic Relationships of Caryopteris incana in the Tsushima Islands, Japan, Using DNA Sequence Analysis

Caryopteris incana is a perennial shrub distributed in the temperate zone of the East Asia. It is found in West Kyushu in Japan, where it is designated as an endangered species. Tsushima, Nagasaki, which experienced repeated connection and fragmentation between the Korean Peninsula and Japan, is an island on the route along which C. incana moved to Japan from continental Asia. We conducted field work and confirmed the genetic structure of populations using DNA sequence analysis to construct a detailed distribution map and clarify the intraspecific phylogenetic relationships of C. incana in Tsushima Island. We confirmed 72 populations in Tsushima. Using the leaves of individuals cultivated from seeds collected from each natural population, we analyzed the chloroplast and nuclear DNA sequence variations. Among the populations, sequence variations were confirmed in six regions of chloroplast DNA, and six haplotypes, including base substitutions, were distinguished. Two haplotypes were mainly divided at the border of the northern part of the southern island in Tsushima. One population in the northwestern part of the north island showed a haplotype derived from the southern part. This finding revealed that the distribution of C. incana had been artificially influenced. Several haplotypes were confirmed by sequence variations in the northern populations, but only one haplotype in the southern populations, suggesting that C. incana on the north island had separated early from the south island in Tsushima.

A New Numerical Method for DNA Sequence Analysis Based on 8-Dimensional Vector Representation

Background: The multiple sequence alignment (MSA) algorithms are the traditional ways to compare and analyze DNA sequences. However, for large DNA sequences, these algorithms require a long time computationally. Objective: Here we will propose a new numerical method to characterize and compare DNA sequences quickly. Method: Based on a new 2-dimensional (2D) graphical representation of DNA sequences, we can obtain an 8-dimensional vector using two basic concepts of probability, the mean and the variance. Results: We perform similarity/dissimilarity analyses among two real DNA data sets, the coding sequences of the first exon of beta-globin gene of 11 species and 31 mammalian mitochondrial genomes, respectively. Conclusion: Our results are in agreement with the existing analyses in our literatures. We also compare our approach with other methods and find that ours is more effective.

Mitochondrial DNA sequence analysis of two mouse hepatocaranoma cell lines

AIM: To study genetic difference of mitochondrial DNA (mtDNA)between two hepatocarcinoma cell lines (Hca-F and Hca-P)with diverse metastatic characteristics and the relationship between mtDNA changes in cancer cells and their oncogenic phenotype.METHODS: Mitochondrial DNA D-loop, tRNAMet+Glu+Ile and ND3gene fragments from the hepatocarcinoma cell lines with 1100, 1126 and 534 bp in length respectively were analysed by PCR amplification and restriction fragment length polymorphism techniques. The D-loop 3' end sequence of the hepatocarcinoma cell lines was determined by sequencing.RESULTS: No amplification fragment length polymorphism and restriction fragment length polymorphism were observed in tRNAMet+Glu+Ile,ND3 and D-loop of mitochondrial DNA of the hepatocarcinoma cells. Sequence differences between Hca-F and Hca-P were found in mtDNA D-loop.CONCLUSION: Deletion mutations of mitochondrial DNA restriction fragment may not play a significant role in carcinogenesis. Genetic difference of mtDNA D-loop between Hca-F and Hca-P, which may reflect the environmental and genetic influences during tumor progression, could be linked to their tumorigenic phenotypes.

Advances in microfluidic-based DNA methylation analysis

DNA methylation has been extensively investigated in recent years,not least because of its known relationship with various diseases.Progress in analytical methods can greatly increase the relevance of DNA methylation studies to both clinical medicine and scientific research.Microflu-idic chips are excellent carriers for molecular analysis,and their use can provide improvements from multiple aspects.On-chip molecular analysis has received extensive attention owing to its advantages of portability,high throughput,low cost,and high efficiency.In recent years,the use of novel microfluidic chips for DNA methylation analysis has been widely reported and has shown obvious superiority to conventional methods.In this review,wefirst focus on DNA methylation and its applications.Then,we discuss advanced microfluidic-based methods for DNA methylation analysis and describe the great progress that has been made in recent years.Finally,we summarize the advantages that microfluidic technology brings to DNA methylation analysis and describe several challenges and perspectives for on-chip DNA methylation analysis.This review should help researchers improve their understanding and make progress in developing microfluidic-based methods for DNA methylation analysis.

Characterization of Fusarium Oxysporum Isolates Obtained from Wax Gourd and Chieh-qua in China by Pathogenicity, RAMs and Sequence Analysis of the rDNA Internal Transcribed Spacers (ITS1 and ITS2)

Wax gourd (Benincasa hispida Thumb. Cogn) is called white gourd, winter melon, Chinese preserving melon, Chinese squash, and don kwa. It has been cultivated in China for over 2 300 years. It probably

DNA存储技术:挑战与未来

随着全球数据呈现指数级增长,当前的信息存储技术面临维护成本高昂、存储寿命有限等多个缺陷,逐渐无法满足日益凸显的需求。因此,迫切需要引入新的信息存储方法来解决这一问题。DNA作为一种天然的遗传信息载体,具备高存储密度、潜在低维护成本和长寿命等优势,因此被视为一种有潜力的新型信息存储介质。该文对DNA数据存储技术的基本原理和流程进行了概述,并回顾了其历史发展。同时,对当前基于DNA存储的领域仍面临的挑战进行了总结,如缓慢的数据写入和读取速度等,以及应对这些挑战的一些潜在策略。最后,为了满足全球对新存储方法的需求,该文指出了DNA数据存储技术的未来发展方向。

DNA存储场景下的大小喷泉码模型设计

在DNA存储等应用场景中,传统喷泉码算法需要占用额外信道资源将源文件分组数目K传递给解码端。在实际应用中,虽然可以将K嵌入在每一个编码数据分组中进行传递,但这种做法会严重浪费信道的带宽。针对上述问题,提出了一种大小喷泉码模型,通过增加小喷泉码这一带外信道来优化关键参数的传递。小喷泉码将每个编码分组中有关参数K所占用空间的粒度降至1 bit,有效减少了带宽资源的消耗。此外,小喷泉码还能适应由于DNA存储介质不均匀所导致的编码序列不定长的限制条件,一定条件下甚至可以完全不占用额外信道带宽。

循环肿瘤DNA在膀胱癌中的研究进展及临床价值

随着生物技术的发展,液体活检技术在肿瘤方面的研究逐渐深入,循环肿瘤DNA(ctDNA)作为液体活检的主要方式之一,以其非侵入性、可重复性及可早期发现病变等特点备受关注。目前有研究表明ctDNA在膀胱癌(BCa)的早期诊断和分级、靶向治疗的选择和疗效分析、肿瘤的复发及进展等方面有一定的潜能,本文结合ctDNA的特点及其近年来在BCa中的研究进展和临床价值进行综述。ctDNA检测技术近年不断发展,人们在测序、突变测定技术发展及在增强其作为癌症检测生物标志物能力方面做出多项进展与尝试。对血浆样本中ctDNA的检测有助于在早期BCa的诊断中实现准确分类,但由于ctDNA含量低,需要更先进检测技术的支持;基于靶向测序的ctDNA分析是预测非肌层浸润性膀胱癌(NMIBC)患者疾病复发和侵袭性的一种有希望的方法。在晚期BCa患者中,可以应用ctDNA收集特有突变类型的特点,有针对性地指导用药、调整治疗及监测预后。尽管ctDNA在BCa的应用仍存在挑战,但已表现出广泛的应用前景。

不同病情乙型肝炎患者HBV-DNA定量、两对半检测结果差异

目的分析乙型肝炎患者乙型肝炎病毒(HBV)-DNA定量检测与两对半检测结果的相关性,并观察不同病情HBV-DNA阳性率和两对半检测结果差异。方法选取江苏省泰兴市人民医院2021年4月至2023年4月收治的375例乙型肝炎患者病例为研究资料。比较不同乙肝两对半检测[乙肝表面抗原(HBsAg)、乙肝表面抗体(HBsAb)、乙肝e抗原(HBeAg)、乙肝e抗体(HBeAb)、乙肝核心抗体(HBcAb)]结果患者HBV-DNA定量检测结果差异,将患者根据HBV-DNA定量检测结果分为阳性组和阴性组,比较乙肝两对半结果差异,使用Pearson相关性分析;将患者根据疾病类型分为肝炎组、肝硬化组和肝癌组,比较三组患者乙肝两对半和HBV-DNA定量检测结果差异。结果不同乙肝两对半类型患者HBV-DNA阳性率比较,差异有统计学意义(P<0.05);HBV-DNA阳性组患者HBsAg、HBeAg水平高于HBV-DNA阴性组,HBsAb、HBeAb、HBcAb水平低于HBV-DNA阴性组,差异有统计学意义(P<0.05);HBsAg、HBeAg水平与HBV-DNA呈正相关(P<0.05),HBsAb、HBeAb、HBcAb水平与HBV-DNA呈负相关(P<0.05);不同疾病类型患者乙肝两对半类型HBV-DNA阳性率比较,差异有统计学意义(P<0.05),不同疾病类型患者HBV-DNA定量检测结果比较,差异有统计学意义(P<0.05)。结论乙型肝炎患者HBV-DNA定量检测与两对半检测结果有相关性,不同乙肝两对半类型间及不同疾病类型间HBV-DNA均有差异,HBV-DNA定量检测联合两对半检测可较好地反映病毒复制和疾病进展情况,为临床治疗提供指导。

Cloning and Expression Analysis of Downy Mildew Resistance-Related cDNA Sequences in Melon

Melon downy mildew caused by Pseudoperonospora cubensis leads to significant losses in melon yields worldwide. Reverse-transcription Polymerase Chain Reaction （RT-PCR） was performed using cDNAs as templates from melon-Huangdanzi induced with fungus Pseudoperonospora cubensis, and degenerate primers designed based on the conserved amino acid sequences of known plant disease-resistance genes. A polymorphic cDNA fragment which we named rap-19 was cloned and sequenced. The Open Reading Frame （ORF） of this product comprised of 510 base pairs which encodes DNA or RNA-binding protein with 170 amino acids. The putative amino acid sequence of mp-19 appeared highly homologous with those of NBS-type resistant-genes isolated from other plants. Southern blot indicated that the melon genome contained more than 3 copies of rap-19. The obvious expression differences detected by semi-quantitative RT- PCR could be observed between resistant-line Huangdanzi and susceptible-line Jiashi after Pseudoperonospora cubensis infection, which implied that mp-19 gene may be related to the resistance of downy mildew in melon.

Endoscopic ultrasound-guided fine-needle aspiration pancreatic adenocarcinoma samples yield adequate DNA for next-generation sequencing:A cohort analysis

BACKGROUND Genetic tests are increasingly performed for the management of unresectable pancreatic cancer.For genotyping aimed samples current guidelines recommend using core specimens,although based on moderate quality evidence.However,in clinical practice among the endoscopic ultrasound(EUS) guided tissue acquisition methods,fine needle aspiration(FNA) is the most widely performed.AIM To assess the adequacy for next generation sequencing(NGS) of the DNA yielded from EUS-FNA pancreatic adenocarcinoma(PDAC) samples.METHODS Between November 2018 and December 2021,105 patients with PDAC confirmed by EUS-FNA were included in the study at our tertiary gastroenterology center.Either 22 gauge(G) or 19G FNA needles were used.One pass was dedicated to DNA extraction.DNA concentration and purity(A260/280,A260/230) were assessed by spectrophotometry.We assessed the differences in DNA parameters according to needle size and tumor characteristics(size,location) and the adequacy of the extracted DNA for NGS(defined as A260/280 ≥ 1.7,and DNA yield:≥ 10 ng for amplicon based NGS,≥ 50 ng for whole exome sequencing [WES],≥ 100 ng for whole genome sequencing [WGS]) by analysis of variance and ttest respectively.Moreover,we compared DNA purity parameters across the different DNA yield categories.RESULTS Our cohort included 49% male patients,aged 67.02 ± 8.38 years.The 22G needle was used in 71%of the cases.The DNA parameters across our samples varied as follows:DNA yield:1289 ng(inter quartile range:534.75-3101),A260/280 = 1.85(1.79-1.86),A260/230 = 2.2(1.72-2.36).DNA yield was > 10 ng in all samples and > 100 ng in 93% of them(one sample < 50 ng).There were no significant differences in the concentration and A260/280 between samples by needle size.Needle size was the only independent predictor of A260/230 which was higher in the 22G samples(P =0.038).NGS adequacy rate was 90% for 19G samples regardless of NGS type,and for 22G samples it reached 89% for WGS adequacy and 91% for WES and amplicon based NGS.Samples with DNA yield > 100 ng had significantly higher A260/280(1.89 ± 0.32 vs 1.34 ± 0.42,P = 0.013).Tumor characteristics were not corelated with the DNA parameters.CONCLUSION EUS-FNA PDAC samples yield DNA adequate for subsequent NGS.DNA amount was similar between 22G and 19G FNA needles.DNA purity parameters may vary indirectly with needle size.

重症肌无力患者血浆染色体外环状DNA的分子特征

目的对重症肌无力(myasthenia gravis,MG)患者血浆染色体外环状DNA(extrachromosomal circular DNA,eccDNA)进行全长测序,分析eccDNA的分子特征及潜在功能,初步探索eccDNA在MG发病过程中的作用机制。方法收集2例MG患者及2例性别、年龄与之匹配的健康人血浆样本,基于滚环扩增和纳米孔测序全新技术平台,对血浆eccDNA进行全长测序,分析比较MG患者与健康人血浆eccDNA的长度分布、染色体来源、基因组元件分布及eccDNA相关差异基因功能富集情况。结果在MG患者和健康对照者中,长度为250~500 bp的eccDNA均分布最多,且MG患者在150~300 bp之间eccDNA呈现另一分布高峰,对照组则在此区间的eccDNA丰度极低。健康对照组eccDNA在1号染色体上分布最多,而MG患者组eccDNA在2号染色体上分布最多;MG患者eccDNA来源基因组元件在内含子、远端基因间区占比均高于健康对照者,而外显子区占比均低于健康对照者。相较于健康对照组,MG患者组eccDNA差异基因富集的通路多与氯离子通道活性、氯离子跨膜转运、钙离子结合及细胞信号传导有关。结论MG患者与健康人血浆eccDNA的分子特征(大小分布、染色体来源、基因组元件分布、eccDNA基因功能富集)存在差异,提示eccDNA可能通过基因表达调控、细胞信号传导、神经突触发育及免疫功能调节等潜在功能影响MG的发生发展,eccDNA可能成为MG早期诊断和疗效监测的新型生物标志物。