https://dspace.ctu.edu.vn/jspui/handle/123456789/6402 Viện Khoa học và Công nghệ Việt Nam Tue, 21 Apr 2026 02:04:51 GMT 2026-04-21T02:04:51Z http://localhost:8080/jspui/retrieve/8639873b-f388-4f9b-9698-0b93486c1b35/50002.jpg https://dspace.ctu.edu.vn/jspui/handle/123456789/6402 https://dspace.ctu.edu.vn/jspui/handle/123456789/107814 Title: Bias distribution of Pristionchus nematodes found in Cat Tien and Cuc Phuong National Parks, Vietnam Authors: Le, Tho Son; Nguyen, Nhu Ngoc; Do, Quang Trung Abstract: The Pristionchus nematodes are distributed in many places worldwide, so they should be diverse in many aspects of biology. The most updated species, P. pacificus, has many differences from and similarities to the standard model organism, Caenorhabditis elegans, and become a parallel but complementary laboratory model for research in genetics, diversity, and evolution. It therefore acquires the demonstration of wild-type isolates of the Pristionchus species in various habitats. In the survey of the soil nematodes, we collected vegetation samples from forests and used them to isolate nematodes. The nematodes were raised in the laboratory to determine their species. In this research, we report the finding of numerous strains within the genus Pristionchus. By comparing the 18S rDNA sequences as an advanced barcode for the classification of free-living nematodes, we identified them in two different species (P. pacificus and P. chinensis) and predicted one new Pristionchus species. Of them, P. pacificus strains are dominant, more in the north and less in the south of Vietnam, and they likely evolved independently over time. The P. chinensis and new Pristionchus sp. were less distributed and probably found by chance. This result extends the global diversity of the nematode genus Pristionchus, facilitating future studies of evolutionary nematodes. Sun, 01 Jan 2023 00:00:00 GMT https://dspace.ctu.edu.vn/jspui/handle/123456789/107814 2023-01-01T00:00:00Z https://dspace.ctu.edu.vn/jspui/handle/123456789/107813 Title: Three rare dioecious Caenorhabditis nematode species (C. Tribulationis, C. Yunquensis, and C. Zanzibari) do not live in the same habitats Authors: Le, Tho Son; Nguyen, Thi Thu Hang; Nguyen, Thi Thu Abstract: The Caenorhabditis nematodes are among the best model systems for studies verifying the molecular-to-phenomenon consequences at different magnitudes. Hundreds of strains within nearly 60 species have been found in the wild and used for studies of evolution. However, the insights of evolution could be uncovered deeper when more Caenorhabditis isolates are gained and accessible. Unfortunately, the effort to isolate wild-type strains is not efficient in the habitats where the Caenorhabditis nematodes do not naturally distribute. In contrast, we surveyed many samples in various locations and revealed the presence of Caenorhabditis nematodes, which had already been seen globally. This suggests that rarer nematode decedents may live in the same habitats. In this research, we report the current isolations and the identifications of three Caenorhabditis species (C. tribulationis, C. yunquensis, and C. zanzibari) with low frequencies of discovery in the wild. Molecularly, they are highly similar to a few previous relatives from other territories. Sun, 01 Jan 2023 00:00:00 GMT https://dspace.ctu.edu.vn/jspui/handle/123456789/107813 2023-01-01T00:00:00Z https://dspace.ctu.edu.vn/jspui/handle/123456789/107812 Title: Metagenomic characterization of archaeal and bacterial communities associated with coral, sediment, and seawater in a coral reef ecosystem of Phu Quoc island, Vietnam Authors: Nguyen, Thi Phuong Thao; Vu, Minh Ngoc; Pham, Van Tra; Bui, Van Ngoc Abstract: Recent advancements in metagenomics, particularly in the studies of conservative 16S rRNA sequences, have significantly accelerated our understanding of the relationship between corals and their associated microbial communities. While bacteria are known to be closely linked with corals, there is limited understanding of the connections between archaea and corals. Unlike previous 16S rRNA studies conducted in similar tropical coral reef ecosystems, we analyzed both the archaeal and bacterial communities associated with Acropora sp. and Lobophyllia sp. corals, as well as the surrounding sediment and water columns in Phu Quoc Island, Kien Giang Province, Vietnam. The data collected were sequenced using the 16S rRNA sequencing method and further analyzed using bioinformatics tools in the R programming language, employing DADA2 and phyloseq pipelines. We examined the compositions and diversity of bacteria and archaea in coral, sediment, and water column samples to establish potential connections between these two domains. The results revealed that archaea constituted a small percentage of all samples, averaging 3.18% in coral mucus and reaching an average of 7.49% in sediment samples. Among the most abundant archaeal taxa were Crenarchaeota and Nanoarchaeota, alongside bacterial taxa Gammabacteria, Cyanobacteria, and Desulfobacteria, which are associated with important metabolic processes within coral hosts. Alpha and beta diversity analyses confirmed the highest archaeal diversity in sediment samples and the distinct existence of microbial communities in each biotope. These findings complement our knowledge of archaea’s presence and potential roles in the coral-associated microbiome. Sun, 01 Jan 2023 00:00:00 GMT https://dspace.ctu.edu.vn/jspui/handle/123456789/107812 2023-01-01T00:00:00Z https://dspace.ctu.edu.vn/jspui/handle/123456789/107811 Title: Codon optimization, expression and purification of recombinant Pwo DNA polymerase in E. coli. Authors: Nguyen, Van Sang; Nguyen, Thi Thu Huyen Abstract: Pwo DNA polymerase is an enzyme that is widely used in PCR due to its thermal stability and proofreading activity (3′-5′ exonuclease activity) with high accuracy. Optimizing the expression and purification of the protein is crucial to reducing the cost of production for this important enzyme. In this study, the higher expression level of the gene encoding Pwo DNA polymerase in bacteria strain E. coli BL21(DE3) was achieved by optimizing codon usage. The parameters of the gene encoding Pwo DNA polymerase obtained from the optimization: Number of Codons (ENc) = 28; Codon Adaptation Index (CAI) = 0.94; %GC = 48.4%. The codon-optimized gene was cloned into a pET-M expression vector and successfully expressed the Pwo DNA polymerase protein with a 6xHis-tag in E. coli BL21(DE3) cells. The recombinant protein was purified through a simple and rapid process involving two steps: cell lysis at high temperature combined with affinity chromatography using a Nickel column. The amount of Pwo DNA polymerase enzyme obtained from 1 liter of cell culture reached 32 mg. The protein yield in this study is higher than that of previous research while maintaining activity comparable to commercial enzymes. The activity of the Pwo DNA polymerase enzyme was tested at concentrations ranging ffrom Promega. This result actively contributes to the production of the Pwo DNA polymerase enzyme and throm 60-150 µg/ml which showed to be equivalent or better than the commercially available Taq DNA polymerase e study of its variants in the future. Sun, 01 Jan 2023 00:00:00 GMT https://dspace.ctu.edu.vn/jspui/handle/123456789/107811 2023-01-01T00:00:00Z