Academia Journal of Biology

New record and redescription of Microcotyle helotes Sandars, 1944 (Monogenea: Microcotylidae) in Vietnam

2024-01-07T19:48:53+07:00

Twenty-seven specimens of the fish species Terapon jarbua and 4 specimens of the fish species Terapon theraps were collected from the Cat Ba Archipelago marine area, and examined for parasite infection. Among these, 4 specimens of T. jarbua and 1 specimen of T. theraps were infected with a total of 42 monogeneans. The intensity of infection ranged from 1 to 16 worms per fish. Four monogenean species were identified, three of which belong to the Protogyrodactylidae: Protogyrodactylus gussevi (14 specimens) and Protogyrodactylus perforatus (12 specimens) were found on T. jarbua, while Protogyrodactylus solidus (1 specimen) was identified on T. theraps. The species Microcotyle helotes (17 specimens) was recorded for the first time in Vietnam, found in two individuals of the new host T. jarbua. Additionally, a redescription of M. helotes was provided.

Combining morphological and molecular data to identify Padina seaweed samples collected from Hon Thom, Phu Quoc in Vietnam

2024-04-16T06:16:22+07:00

The Padina genus has 75 species of which 54 species are classification recognized. The Padina genus has been used as nutritional food that supplies vitamins, proteins, and carotenoids by humans for a long time. Recently, several drugs and dietary supplements containing active components extracted from Padina have been commercially developed. Species of the Padina genus are quietly morphologically similar. Almost all previous studies of the Padina genus used the morphological identification method. This study presents the results of correlation analysis between morphological characteristics and the rbcL marker in the identification of Padina seaweed samples collected at Hon Thom, Phu Quoc, Kien Giang province (HTO), Vietnam. The phylogenetic tree and genetic distance between HTO with references showed the samples belonging to Padina australis. Thus, identification methods based on genetic markers and morphology on HTO seaweed samples were consistent.

Discrimination of Vietnamese species of the genus Rhynocoris (Hemiptera: Heteroptera: Reduviidae) with the utilization of integrative taxonomy

2024-04-09T11:51:16+07:00

The genus Rhynocoris Hahn, 1834 is one of the largest genera of the subfamily Harpactorinae. This genus consists of 144 described species widely distributed in the Afrotropical, Palearctic, Sino-Japanese, Oriental, and Nearctic Realms. There are three species, Rhynocoris fuscipes (Fabricius, 1787), Rhynocoris marginellus (Fabricius, 1803), Rhynocoris mendicus (Stål, 1867) recorded in Vietnam. In this study, we attempted to re-examine the Rhynocoris species collected from Vietnam based on external morphology, genital morphology, and COI phylogeny to reveal the species delimitation of this genus in Vietnam. As a result, the independence of the three Rhynocoris species from Vietnam was confirmed. Moreover, R. mendicus was revealed as being a polymorphic species with two intraspecific morphological phenotypes.

New distribution and host record of Stenarella insidiator (Smith, 1859) (Hymenoptera: Ichneumonidae: Cryptinae) from Vietnam

2024-01-24T11:19:42+07:00

The ichneumonid parasitoid Stenarella insidiator (Smith, 1859) is recorded for the first time from Vietnam based on the specimens collected from Tam Dao National Park in Vinh Phuc province, Na Hang district in Tuyen Quang province, and Bidoup-Nui Ba National Park in Lam Dong province. In addition, the wasp Orancistrocerus aterrimus (de Saussure, 1852) (Hymenoptera: Vespidae) is reported as a new host of this parasitoid. The parasitoid is described based on Vietnamese material with information of its overwintering in the wasp nest.

Chemical composition and larvicidal activity of essential oil from leaves of Eucalyptus robusta

2023-12-12T15:16:53+07:00

Essential oil (EO) from leaves of Eucalyptus robusta was extracted by hydrodistillation, and analyzed the chemical composition using gas chromatography- Flame ionization detector (GC-FID), and gas chromatography/mass spectrometry (GC/MS). Thirty constituents from leaf EO were identified accounting for 97.48% of the total composition of EO. Monoterpene hydrocarbons were the major chemical classes (83.34%) in which 1,8-cineole (29.23%), α-pinene (18.58%), α-phellandrene (14.05%) and β-pinene (6.40%) were the main components. The larvicidal activity test against Culex quinquefasciatus showed that the essential oil from the leaves of E. robusta strongly inhibited this southern house mosquito with LC₅₀ values at 24 h and 48h to be 30.34 µg/mL and 28.77 µg/mL, respectively.

Comparison between scot and CBDP techniques in assessment genetic diversity and variation of two populations of bigfin reef squid (Sepioteuthis lessoniana d’Orbigny) in Con Dao and Phu Quoc islands, Vietnam

2023-10-31T09:46:00+07:00

The Start Codon Targeted Polymorphism (SCoT) and CAAT box-derived polymorphism (CBDP) techniques were used to analyze the genetic diversity and variation of two bigfin reef squid populations in waters surrounding the Con Dao and Phu Quoc islands of Vietnam for technical comparison. The two used techniques reflected different levels of pairwise genetic similarity among individuals depended on the investigated population. Gene differentiation (G_ST) between the two investigated populations was 0.0767 and 0.0373 leaded to the genetic distance between them was 0.0381 and 0.0228, and the gene flow was Nm = 6.0195 and 12.9061 migrants per generation between the populations based on SCoT and CBDP techniques, respectively. Genetic variation within individuals of both populations (WP) played the key role in the total genetic variation of whole species in surveyed geographic regions with the distribution of 91.44% based on SCoT data and 93.76% based on CBDP data, the distribution of genetic variation among populations (AP) was small. For whole species in the surveyed region, the CBDP markers showed higher genetic diversity, while the SCoT markers reflected the differentiation and genetic distance between the two investigated populations better. Overall, the abilities to detect polymorphisms and the number of revealed loci using SCoT markers were better than using CBDP markers, while the ability to distinguish samples and the primer combination to detect the differences among investigated samples using CBDP markers were better than using SCoT markers, and the overall utility was comparable between these two marker systems. The results from this study prove that the CBDP technique can also be used in studies of animal population genetics.

Profile of the gut microbial composition in Apis mellifera larvae collected in Ha Noi

2024-02-21T13:32:55+07:00

The gut microbiota plays a crucial role in food digestion, enhances the host's immune system, and against pathogens. Numerous studies have been conducted on the microbiota of insects in general and honeybees in particular. However, studies have primarily focused on adult honeybees, with fewer studies dedicated to larvae. Despite being within the hive, honeybee larvae still possess their distinct microbiota. To gain a deeper understanding of the microbiota in the larvae of Apis mellifera honeybees, the larva from honeybee colonies collected in Ha Noi, Vietnam was investigated. Next-generation sequencing (NGS) targeting the 16S rRNA gene was employed for microbiome analysis. Results revealed the presence of 5 phyla including Proteobacteria (70.43%), Actinobacteria (1.16%), Firmicutes (20.87%), Bacteroidetes (2.72%), and Chloroflexi (2%). Representative genera included Bombella (29.97%), Lactobacillus (14.91%), Gilliamella (9.59%), Frischella (4.69%), Snodgrassella (3.85%), and Marinobacter (1.21%). Further characterized species composition in the sample we identified the prevalence of Bifidobacterium intestini (29.96%), Gilliamella apicola (8.08%), Frischella perrara (4.55%), Lactobacillus kimbladii (2.85%), Lactobacillus plantarum (2.80%), Snodgrassella alvi (2.77%), Lactobacillus mellis (2.59%), Lactobacillus_uc (unclassified or not yet classified to species, 2.19%), Lactobacillus kunkeei (1.43%), and Lactobacillus melliventris (1.31%). Understanding these microbial dynamics is crucial for developing strategies to support honeybee health and mitigate the challenges posed by factors, such as pesticides, environmental pollution, and honeybee diseases.

Isolation and properties of endophytic bacteria and actinomycetes of Catharanthus roseus (L) G. Don grown in Nha Trang, Vietnam

2023-09-22T10:32:01+07:00

Endophytic microbes of medicinal plants are known to involve the synthesis of several bioactive compounds, which promote plant growth and resistance to diseases. In order to investigate endophytes in the important medicinal plant Catharanthus roseus, 16 endophytic microorganism strains were isolated from root samples of C. roseus var. roseus and C. roseus var. ocellatus naturally growing in coastal areas of Nha Trang, Vietnam. Based on morphological characteristics and 16S rDNA gene marker sequences, four actinomycetes of Streptomyces and Microbiospora genera and twelve bacterial strains belonging to Bacillus, Enterobacter, Pseudomonas, Panenibacillus and Rhizobium genera were identified. Analysis of the extracellular enzyme activities of actinomycetes strains indicated that Streptomyces strains produced proteases, cellulases, xylanases and amylases and Microbiospora strains exhibited protease and cellulase activities. The results demonstrated the diversity of endophytes in the roots of C. roseus plants and their potential extracellular enzyme activities for further application.

Screening of novel conopeptide for mosquitocidal activity against lethal mosquitoes (Anopheles stephensi, Aedes aegypti)

2024-02-01T21:50:58+07:00

Mosquitoes are carriers of various diseases that result in millions of human deaths annually. However, the use of chemical mosquitocides has led to significant concerns, such as adverse effects on the environment, human health, and insecticide resistance. As a result, there is a pressing need for eco-friendly alternatives. This study aimed to identify potential mosquitocidal conopeptides from cone snail venoms targeting two lethal mosquito species, Anopheles stephensi and Aedes aegypti. Eleven Conus species were collected from Nha Trang Bay and their crude venoms were dissected and collected. Through cell survival and toxicity assays on mosquito larvae, five crude venoms were identified to have inhibitory effects. Further investigations involved fractionating these five crude venoms and testing them for cell cytotoxic activity were conducted. Four fractions from Conus bandanus venom, named CB37, CB39, CB41, and CB43, showed significant cytotoxic activity against cell survival. Other fractions from different Conus venoms also exhibited some cytotoxic activity at high concentrations but were not prioritised for further investigation. Toxicity experiments on adult mosquitoes revealed that the CB41 fraction had the most potential, with an IC₅₀ of 30 μM. Additionally, this CB41 compound is a peptide in nature and was found to have a native mass of 3332.1 Da and three disulphide bridges. These results could deduce this long-chain peptide possessing a compact structure. To our knowledge, the conopeptide CB41 is reported first time to have mosquitocidal activity.

Analysis of genetic diversity of Ven dog breed based on microsatellite markers

2024-03-28T09:58:38+07:00

Microsatellite (MS) is a genetic marker widely used in the studies of pedigree, individual identification, gene mapping, and genetic diversity within and between populations. The genetic diversity of the indigenous Ven dog breed, along with two imported dog breeds, the Berger and Poodle dogs raised in Vietnam, was analyzed based on seven microsatellite markers. A total of 32 alleles, an average number of alleles/loci of 4.6 were observed across 80 samples of the three dog breeds. The overall polymorphic information content (PIC) was 0.67 representing the quality of selected MS markers. Genetic diversity indices (Ho, He, Fit, Fst) showed the phenomenon of inbreeding between individuals in the Ven dog population. The genetic similarity level and phylogenetic tree also reasonably reflect the genetic relationship between the three analyzed dog breeds, in which the Ven dog showed a higher genetic distance compared to two imported dog breeds.

Notes on genus Cybister Curtis, 1827 (Coleoptera: Dytiscidae) with the first records of Cybister danxiaensis Zhuo-Yin Jiang and Cybister convexus Sharp from Vietnam

2024-04-09T11:59:56+07:00

The genus Cybister Curtis, 1827 is reviewed for the fauna of Vietnam. The 5 species are diagnosed with illustrated habitus, leg, and male genitalia. Additional measurement data, and an updated identification key for all species are provided. Two species Cybister convexus Sharp, 1882, and Cybister danxiaensis Zhuo-Yin Jiang, 2023, are recorded for the first time in Vietnam.

Antimicrobial and cytotoxic potential of endophytic actinomycetes isolated from Cinnamomum cassia Presl in Lai Chau Vietnam

2024-04-11T09:05:26+07:00

New antimicrobials are urgently needed to combat the threat of multidrug-resistant bacteria worldwide. Our study aimed to access the antimicrobial and cytotoxic profiles of endophytic actinomycetes associated with Cinnamomum cassia Presl taken from a mountainous region in the Northwest of Vietnam. The antimicrobial activity, capability for anthracycline-like compounds production and presence of secondary metabolite-biosynthetic genes were consequently determined. Finally, the cytotoxicity of antibiotic-producing actinomycetes was carried out towards various cancer cell lines. A total of 81 actinomycetes were recovered from different organs (roots, stems, leaves) of Cinnamomum cassia, of which 20/81 isolates exhibited antimicrobial activities against at least one of nine microbial strains. The analysis of 16S rRNA genes indicated that antibiotic-producing isolates were grouped into 4 genera Streptomyces, Micromonospora, Saccharothrix, and Microbacterium, among which Streptomyces was the most prevalent. The presence of biosynthetic genes pks-I, pks-II or nrps was detected in 17/20 of isolates. Five strains of Streptomyces griseorubens LCQ8, Streptomyces variabilis LCQ43, Streptomyces californicus LCQ44, Streptomyces fragilis LCQ75, and Streptomyces beijiangensis LCQ77 exhibited broad-spectrum antimicrobial activity against various pathogens with the MIC values ranging from 16 to 256 µg/mL. Furthermore, characterized strains showed considerable cytotoxicity against MCF-7 cell lines with a 50% inhibition concentration of crude culture extracts of less than 30 µg/mL. The findings demonstrated that Streptomyces species isolated from Cinnamomum cassia in mountainous regions hold the potential for growth inhibition of human disease agents.

Genomic insights into multidrug-resistance and virulence in a vancomycin-resistant Staphylococcus aureus strain VR480

2024-05-04T20:36:21+07:00

Vancomycin-resistant Staphylococcus aureus (VRSA), a “high priority antibiotic-resistant pathogen”, is emerging and threatening global health. Nevertheless, molecular mechanisms associated with virulence and multidrug resistance in VRSA are not fully investigated particularly in low- and middle-income countries. Here, for the first time, the complete genome of a VRSA strain VR480 isolated from a Vietnamese patient was generated by the combination of long- and short-read sequencing technologies. The VRSA strain VR480 was a multidrug-resistant phenotype with resistance to at least one antibiotic belonging to beta lactams, quinolones, lincomycin, oxazolidinones, tetracyclines, glycylcyclines, macrolide/lincosamide/streptogramin, nitrofurans, rifamycins, sulfonamides and glycopeptides. This strain was classified as vancomycin resistance (MIC ≥ 32 μg/mL). VRSA strain VR480 belonged to sequence type ST2779 and carried the SCCmec type II(2A). The VRSA strain VR480 genome contains five resistance mutations in genes. gyrA S84L, parC S80F, parE D432N, fusA L461K and glpT W355Stop, and eleven antibiotic resistant genes including mecA, mecR, mecI, tetM, tet38, mepA, lmrS, ant(9), ermA, fosB and catA. This strain possesses various virulence factors associated with adherence, biofilm formation, colonization, invasion, anti-phagocytosis and toxicity that promote the infection and pathogenesis. Protein interaction network analysis revealed five clusters consisting of known and putative virulence proteins. Furthermore, epimerase, EssC, IcaA, SplA and Ssl1 were the key proteins within each cluster. This study raises a warning about the circulation and dissemination of VRSA in Vietnam. The key proteins would be potential targets for the development of anti-virulent agents to combat the VRSA infection.