Isolation, structure elucidation and antibacterial activity of methyl-4,8-dimethylundecanate from the marine actinobacterium Streptomyces albogriseolus ECR64.

Around 120 actinobacterial colonies were isolated from various regions of marine East coast region of Tamil Nadu, India. Among them, 33 were morphologically distinct and they were preliminarily screened for their antibacterial activity against Pseudomonas fluorescens, Vibrio cholerae, V. parahaemolyticus, V. alginolyticus, and Aeromonas hydrophila by cross-streak plate technique. Among the isolated, the isolate ECR64 exhibited maximum zone of inhibition against fish pathogenic bacteria. The crude bioactive compounds were extracted from the isolate ECR64 using different organic solvents which exhibited maximum antibacterial activity. Separation and purification of the bioactive compounds were made by column chromatography which yielded 27 fractions and were re-chromatographed to obtain the active compound. Ultra violet (UV), Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectral studies were used to predict the structure of the active compound which was identified as methyl-4,8-dimethylundecanate. The potential isolate ECR64 was identified as Streptomyces albogriseolus by phylogenetic, phenotypic and genotypic (16S rRNA gene sequence) analyses. The identified compound methyl-4,8-dimethylundecanate can be used as potential and alternative drug in disease management of aquaculture.

DNA barcoding and molecular evolution of mosquito vectors of medical and veterinary importance.

Mosquitoes (Diptera: Culicidae) are a key threat for millions of people worldwide, since they act as vectors for devastating pathogens and parasites. The standard method of utilisation of morphological characters becomes challenging due to various factors such as phenotypical variations. We explored the complementary approach of CO1 gene-based identification, analysing ten species of mosquito vectors belonging to three genera, Aedes, Culex and Anopheles from India. Analysed nucleotide sequences were found without pseudo genes and indels; they match with high similarity in nucleotide Basic Local Alignment Search Tool (BLASTn) search. The partial CO1 sequence of Anopheles niligricus was the first time record submitted to National Center for Biotechnology Information (NCBI). Mean intra- and interspecies divergence was found to be 1.30 and 3.83 %, respectively. The congeneric divergence was three times higher than the conspecifics. Deep intraspecific divergence was noted in three of the species, and the reason could be explained more accurately in the future by improving the sample size across different locations. The transitional and transversional substitutions were tested individually. Ts and Tv substitutions in all the 1st, 2nd and 3rd codons were estimated to be (0.44, 99.51), (40.35, 59.66) and (59.16, 40.84), respectively. Saturation of the sequences was resolved, since both the Ts and Tv exhibited a linear relationship suggesting that the sequences were not saturated. NJ and ML tree analysis showed that the individuals of the same species clustered together based on the CO1 sequence similarity, regardless of their collection site and geographic location. Overall, this study adds basic knowledge to molecular evolution of mosquito vectors of medical and veterinary importance and may be useful to improve biotechnological tools employed in Culicidae control programmes.

Genetic deviation in geographically close populations of the dengue vector Aedes aegypti (Diptera: Culicidae): influence of environmental barriers in South India.

Mosquitoes are vectors of devastating pathogens and parasites, causing millions of deaths every year. Dengue is a mosquito-borne viral infection found in tropical and subtropical regions around the world. Recently, dengue transmission has strongly increased in urban and semiurban areas, becoming a major international public health concern. Aedes aegypti (Diptera: Culicidae) is a primary vector of dengue. Shedding light on genetic deviation in A. aegypti populations is of crucial importance to fully understand their molecular ecology and evolution. In this research, haplotype and genetic analyses were conducted using individuals of A. aegypti from 31 localities in the north, southeast, northeast and central regions of Tamil Nadu (South India). The mitochondrial DNA region of cytochrome c oxidase 1 (CO1) gene was used as marker for the analyses. Thirty-one haplotypes sequences were submitted to GenBank and authenticated. The complete haplotype set included 64 haplotypes from various geographical regions clustered into three groups (lineages) separated by three fixed mutational steps, suggesting that the South Indian Ae. aegypti populations were pooled and are linked with West Africa, Columbian and Southeast Asian lineages. The genetic and haplotype diversity was low, indicating reduced gene flow among close populations of the vector, due to geographical barriers such as water bodies. Lastly, the negative values for neutrality tests indicated a bottle-neck effect and supported for low frequency of polymorphism among the haplotypes. Overall, our results add basic knowledge to molecular ecology of the dengue vector A. aegypti, providing the first evidence for multiple introductions of Ae. aegypti populations from Columbia and West Africa in South India.

Review on the Biogenesis of Platelets in Lungs and Its Alterations in SARS-CoV-2 Infection Patients.

Thrombocytes (platelets) are the type of blood cells that are involved in hemostasis, thrombosis, etc. For the conversion of megakaryocytes into thrombocytes, the thrombopoietin (TPO) protein is essential which is encoded by the TPO gene. TPO gene is present in the long arm of chromosome number 3 (3q26). This TPO protein interacts with the c-Mpl receptor, which is present on the outer surface of megakaryocytes. As a result, megakaryocyte breaks into the production of functional thrombocytes. Some of the evidence shows that the megakaryocytes, the precursor of thrombocytes, are seen in the lung's interstitium. This review focuses on the involvement of the lungs in the production of thrombocytes and their mechanism. A lot of findings show that viral diseases, which affect the lungs, cause thrombocytopenia in human beings. One of the notable viral diseases is COVID-19 or severe acute respiratory syndrome caused by SARS-associated coronavirus 2 (SARS-CoV-2). SARS-CoV-2 caused a worldwide alarm in 2019 and a lot of people suffered because of this disease. It mainly targets the lung cells for its replication. To enter the cells, these virus targets the angiotensin-converting enzyme-2 (ACE-2) receptors that are abundantly seen on the surface of the lung cells. Recent reports of COVID-19-affected patients reveal the important fact that these peoples develop thrombocytopenia as a post-COVID condition. This review elaborates on the biogenesis of platelets in the lungs and the alterations of thrombocytes during the COVID-19 infection.

Intra-species variation and geographic differentiation among the populations of the quarantine agricultural pest leucinoides orbonalis (lepidoptera: Crambidae) in the global assemblage - a prospective of DNA barcoding.

Leucinodes orbonalis Guenée is serious quarantine pest occurring globally, studies are needed to enlighten the genetic complexities associated with the species. India is considered to be the origin of the L. orbonalis, therefore availability of species records from this region enable to analyse the genetic differences and dispersal of the lineages. The results of the study reported 47 haplotypes in four clusters pertaining to their ancestral lineage. The transition/transversion bias (R) was observed to be higher with 1.238 and 1.312 in the first and third codon positions respectively. The overall intraspecies divergence was found to be 0.302. AMOVA revealed that the total variations were then as reported 67.15 among the south-east countries but our studies reported the total variation to be 77.25% (Germany, India, South east and Australia). FST and Mantel's test indicated that there was no correlation between the genetic variation and geographical distance. The overall haplotype diversity was 0.852, where the nucleotide diversity of H31 (0.00593) was highest and H1 (0.00087) was lowest. The genetic diversity indices Tajima D and Fu's Fs static for H1, H13 and H31 had negative values which possibly inferred for the bottle neck effect. The ML tree was constituted the branch length of 5.0157 with one out-group. The tree was formed with ten distinctive clades with the haplotypes congregated together based on similar genetic composition.

DNA barcoding of five Japanese encephalitis mosquito vectors (Culex fuscocephala, Culex gelidus, Culex tritaeniorhynchus, Culex pseudovishnui and Culex vishnui).

Culex mosquitoes can act as vectors of several important diseases, including Japanese encephalitis, West Nile virus, St. Louis encephalitis and equine encephalitis. Besides the neurological sequelae caused in humans, Japanese encephalitis can lead to abortion in sows and encephalitis in horses. Effective vector control and early diagnosis, along with continuous serosurveillance in animals, are crucial to fight this arboviral disease. However, the success of vector control operations is linked with the fast and reliable identification of targeted species, and knowledge about their biology and ecology. Since the DNA barcoding of Culex vectors of Japanese encephalitis is scarcely explored, here we evaluated the efficacy of this tool to identify and analyze the variations among five overlooked Culex vectors of Japanese encephalitis, Culex fuscocephala, Culex gelidus, Culex tritaeniorhynchus, Culex pseudovishnui and Culex vishnui, relying to the analysis of mitochondrial CO1 gene. Variations in their base pair range were elucidated by the entropy Hx plot. The differences among individual conspecifics and on base pair range across the same were studied. The C (501-750 bp) region showed a moderate variation among all the selected species. C. tritaeniorhynchus exhibited the highest variation in all the ranges. The observed genetic divergence was partially non-discriminatory. i.e., the overall intra- and inter nucleotide divergence was 0.0920 (0.92%) and 0.125 (1.25%), respectively. However, 10X rule fits accurately intraspecies divergence <3% for the five selected Culex species. The analysis of individual scatter plots showed threshold values (10X) of 0.008 (0.08%), 0.005 (0.05%), 0.123 (1.23%), 0.033 (0.33%) and 0.019 (0.19%) for C. fuscocephala, C. gelidus, C. tritaeniorhynchus, C. pseudovishnui and C. vishnui, respectively. The C. tritaeniorhynchus haplotypes KU497604, KU497603, AB690847 and AB690854 exhibited the highest divergence range, i.e., from 0.465 -0.546. Comparatively, the intra-divergence among the other haplotypes of C. tritaeniorhynchus ranged from 0-0.056. The maximum parsimony tree was formed by distinctive conspecific clusters with appreciable branch values illustrating their close congruence and extensive genetic deviations. Overall, this study adds valuable knowledge to the molecular biology and systematics of five overlooked mosquito species acting as major vectors of Japanese encephalitis in Asian countries.

Exploring genetic variation in haplotypes of the filariasis vector Culex quinquefasciatus (Diptera: Culicidae) through DNA barcoding.

Culex quinquefasciatus (Diptera: Culicidae) is a vector of many pathogens and parasites of humans, as well as domestic and wild animals. In urban and semi-urban Asian countries, Cx. quinquefasciatus is a main vector of nematodes causing lymphatic filariasis. In the African region, it vectors the Rift Valley fever virus, while in the USA it transmits West Nile, St. Louis encephalitis and Western equine encephalitis virus. In this study, DNA barcoding was used to explore the genetic variation of Cx. quinquefasciatus populations from 88 geographical regions. We presented a comprehensive approach analyzing the effectiveness of two gene markers, i.e. CO1 and 16S rRNA. The high threshold genetic divergence of CO1 (0.47%) gene was reported as an ideal marker for molecular identification of this mosquito vector. Furthermore, null substitutions were lower in CO1 if compared to 16S rRNA, which influenced its differentiating potential among Indian haplotypes. NJ tree was well supported with high branch values for CO1 gene than 16S rRNA, indicating ideal genetic differentiation among haplotypes. TCS haplotype network revealed 14 distinct clusters. The intra- and inter-population polymorphism were calculated among the global and Indian Cx. quinquefasciatus lineages. The genetic diversity index Tajima' D showed negative values for all the 4 intra-population clusters (G2-4, G10). Fu's FS showed negative value for G10 cluster, which was significant and indicated recent population expansion. However, the G2-G4 (i.e. Indian lineages) had positive values, suggesting a bottleneck effect. Overall, our research firstly shed light on the genetic differences among the haplotypes of Cx. quinquefasciatus species complex, adding basic knowledge to the molecular ecology of this important mosquito vector.