First insight of genetic diversity, phylogeographic relationships and population structure of marine sponge Chondrosia reniformis from the eastern and western Mediterranean coasts of Tunisia

The cytochrome oxidase subunit I (COI) gene was amplified and analyzed for 70 Mediterranean Chondrosia reniformis, collected from eight localities in Tunisia. Polymorphism results revealed high values of haplotype diversity (Hd) and very low nucleotide diversity (π). Thus, these results suggest that our sponge populations of C. reniformis may have undergone a bottleneck followed by rapid demographic expansion. This suggestion is strongly confirmed by the results of neutrality tests and “mismatch distribution”. The important number of haplotypes between localities and the high genetic differentiation (Fst ranged from 0.590 to 0.788) of the current C. reniformis populations could be maintained by the limited gene flow Nm (0.10 - 0.18). Both haplotype Network and the biogeographic analysis showed a structured distribution according to the geographic origin. C. reniformis populations are subdivided into two major clades: Western and Eastern Mediterranean. This pattern seems to be associated with the well-known discontinuous biogeographic area: the Siculo-Tunisian Strait, which separates two water bodies circulating with different hydrological, physical, and chemical characteristics. The short dispersal of pelagic larvae of C. reniformis and the marine bio-geographic barrier created high differentiation among populations. Additionally, it is noteworthy to mention that the “Mahres / Kerkennah” group diverged from Eastern groups in a single sub-clade. This result was expected, the region Mahres / Kerkennah, presented a particular marine environment.

Dynamics of Genetic Diversity Among Indian Sugarcane Bacilliform Virus Species and Implications of Associated Recombination Events in the Virus

Sugarcane bacilliform virus (SCBV), a plant pararetrovirus causing leaf fleck disease in sugarcane across the globe. Since the virus occurs throughout the sugarcane growing areas and germplasm in India, we have assessed the genetic divergences among the virus isolates from 104 isolates infecting germplasm and Saccharum hybrid varieties. With the evidence gathered from phylogenetic analysis and sequence demarcation tool, five novel genotypes are being proposed: SCBV-U, SCBV-V, SCBV-W, SCBV-X and SCBV-Y. SCBV-W: CBJ 46, due to the divergence in the nucleotide and protein sequence with existing isolates, established itself as a novel candidate in SCBV species. In comparison with the existing database of SCBV and conclusion from the present study, SCBV isolates from India exhibited maximum diversity in comparison with other regions. SCBV-U, SCBV-W, SCBV-X which turned out as potent recombinants along with other six recombinants in the study, directs at the plausible heterogeneity and genetic exchange happened within SCBV species over time which lead to the evolution of new variants. Neutrality tests indicate the existence of low-frequency polymorphism and Selection pressure of < 1 pointed out at purifying selection. Codon usage bias acted as an efficient tool for identifying patterns in SCBV, in which non-randomness in mutational events might lead to the over expression of codon AGA. The current study on characterization and evidence of nucleotidal variation within SCBV species will lead to devising robust diagnostics of the virus in quarantine and improving the knowledge on the evolutionary changes in SCBV species.

Genetic Diversity Analysis of Surface-Related Antigen (SRA) in Plasmodium falciparum Imported From Africa to China

Plasmodium falciparum surface-related antigen (SRA) is located on the surfaces of gametocyte and merozoite and has the structural and functional characteristics of potential targets for multistage vaccine development. However, little information is available regarding the genetic polymorphism of pfsra. To determine the extent of genetic variation about P. falciparum by characterizing the sra sequence, 74 P. falciparum samples were collected from migrant workers who returned to China from 12 countries of Africa between 2015 and 2019. The full length of the sra gene was amplified and sequenced. The average pairwise nucleotide diversities (π) of P. falciparum sra gene was 0.00132, and the haplotype diversity (Hd) was 0.770. The average number of nucleotide differences (k) for pfsra was 3.049. The ratio of non-synonymous (dN) to synonymous (dS) substitutions across sites (dN/dS) was 1.365. Amino acid substitutions of P. falciparum SRA could be categorized into 35 unique amino acid variants. Neutrality tests showed that the polymorphism of PfSRA was maintained by positive diversifying selection, which indicated its role as a potential target of protective immune responses and a vaccine candidate. Overall, the ability of the N-terminal of PfSRA antibodies to evoke inhibition of merozoite invasion of erythrocytes and conserved amino acid at low genetic diversity suggest that the N-terminal of PfSRA could be evaluated as a vaccine candidate against P. falciparum infection.

Population Genetic Structure and Contribution of Philippine Chickens to the Pacific Chicken Diversity Inferred From Mitochondrial DNA

The Philippines is considered one of the biodiversity hotspots for animal genetic resources. In spite of this, population genetic structure, genetic diversity, and past population history of Philippine chickens are not well studied. In this study, phylogeny reconstruction and estimation of population genetic structure were based on 107 newly generated mitochondrial DNA (mtDNA) complete D-loop sequences and 37 previously published sequences of Philippine chickens, consisting of 34 haplotypes. Philippine chickens showed high haplotypic diversity (Hd = 0.915 ± 0.011) across Southeast Asia and Oceania. The phylogenetic analysis and median-joining (MJ) network revealed predominant maternal lineage haplogroup D classified throughout the population, while support for Philippine–Pacific subclade was evident, suggesting a Philippine origin of Pacific chickens. Here, we observed Philippine red junglefowls (RJFs) at the basal position of the tree within haplogroup D indicating an earlier introduction into the Philippines potentially via mainland Southeast Asia (MSEA). Another observation was the significantly low genetic differentiation and high rate of gene flow of Philippine chickens into Pacific chicken population. The negative Tajima’s D and Fu’s Fs neutrality tests revealed that Philippine chickens exhibited an expansion signal. The analyses of mismatch distribution and neutrality tests were consistent with the presence of weak phylogeographic structuring and evident population growth of Philippine chickens (haplogroup D) in the islands of Southeast Asia (ISEA). Furthermore, the Bayesian skyline plot (BSP) analysis showed an increase in the effective population size of Philippine chickens, relating with human settlement, and expansion events. The high level of genetic variability of Philippine chickens demonstrates conservation significance, thus, must be explored in the future.

Dynamics of genetic diversity among Indian Sugarcane bacilliform virus species and implications of associated recombination events in the virus

Sugarcane bacilliform virus (SCBV), a plant pararetrovirus causing leaf fleck disease in sugarcane across the globe. Since the virus occurs throughout the sugarcane growing areas and germplasm in India, we have assessed the genetic divergences among the virus isolates from 104 isolates infecting germplasm and Saccharum hybrid varieties. With the evidence gathered from phylogenetic analysis and sequence demarcation tool, five novel genotypes are being proposed: SCBV-U, SCBV-V, SCBV-W, SCBV-X and SCBV-Y. SCBV-W: CBJ 46, due to the divergence in the nucleotide and protein sequence with existing isolates, established itself as a novel candidate in SCBV species. In comparison with the existing database of SCBV and conclusion from the present study, SCBV isolates from India exhibited maximum diversity in comparison with other regions. SCBV-U, SCBV-W, SCBV-X which turned out as potent recombinants along with other six recombinants in the study, directs at the plausible heterogeneity and genetic exchange happened within SCBV species over time which lead to the evolution of new variants. Neutrality tests indicate the existence of low-frequency polymorphism and Selection pressure of < 1 pointed out at purifying selection. Codon usage bias acted as an efficient tool for identifying patterns in SCBV, in which non-randomness in mutational events might lead to the over expression of codon AGA. The current study on characterization and evidence of nucleotidal variation within SCBV species will lead to devising robust diagnostics of the virus in quarantine and improving the knowledge on the evolutionary changes in SCBV species.

Phylogenetic and diversity analyses of Garlic common latent virus based on the TGB and CP gene sequence

Garlic common latent virus (GarCLV, Carlavirus), in co-infection, often worsens the severity of other Allium viruses on the garlic (Allium sativum Linnaeus). The nucleotide (nt) and amino acid (aa) sequences of the TGB and CP genes were analysed to get the first deep insight into the genomic variations and population structure of GarCLV. Global recombinant-free isolates were clustered into three clades in both the nt-based phylogenetic trees of TGB and CP. The clade 3 isolates shared low similarity percentages among themselves, as well as to the clade 1 and 2 isolates. Most major aa changes in the CP were observed on its 5' and 3' ends. Clade 2 obtained the lowest S, η, k, and π values for both the TGB and CP, which indicated low variations among its isolates. Both TGB and CP have undergone a negative selection, with CP being under stronger negative pressure than TGB. Neutrality tests estimated the non-significant negative values to all clades for TGB and CP, except Tajima's D for clade 2 of the TGB. The results of the K_s*, K_st*, Z*, and Snn tests suggested that all three phylogroups were divergent to each other for both TGB and CP. The high F_st on all the clade comparisons for both TGB and CP showed a large gene flow among three clades.

Robust detection of natural selection using a probabilistic model of tree imbalance

Neutrality tests such as Tajima's D and Fay and Wu's H are standard implements in the population genetics toolbox. One of their most common uses is to scan the genome for signals of natural selection. However, it is well understood that deviance measures like D and H are confounded by other evolutionary forces---in particular, population expansion---that may be unrelated to selection. Because they are not model-based, it is not clear how to deconfound these statistics in a principled way. In this paper we derive new likelihood-based methods for detecting natural selection which are robust to confounding by fluctuations in effective population size. At the core of our method is a novel probabilistic model of tree imbalance, which generalizes Kingman's coalescent to allow certain aberrant tree topologies to arise more frequently than is expected under neutrality. We derive a frequency spectrum-based estimator which can be used in place of D, and also extend to the case where genealogies are first estimated. We benchmark our methods on real and simulated data, and provide an open source software implementation.

Mitochondrial Phylogeny and Population Structure of Pakistani Dromedary Camel (Camelus dromedarius)

Dromedary camels (Camelus dromedarius) are one of the most important livestock species mainly used for milk and meat production in semi-arid and hot-desert expanses of the Arabian-Peninsula, Africa, and Southwest Asia. This study investigated the genetic diversity and population structure within and between eight dromedary camel breeds (n = 210) inhabiting Balochistan province, Pakistan, by mitochondrial cytochrome b (Cyt b). Sequences (1140 bp) analysis showed a total of 18 variable sites resulting in 16 haplotypes. The average haplotype and nucleotide diversities were Hd = 0.484 ± 0.051 and π = 0.00272 respectively. Phylogenetic analysis showed different clusters for camelids. The neutrality tests did not support the population demographic expansion for these camel breeds. Based on these results, we suggest that an imperative genetic management and breeding strategies are required for the effective conservation of this species. © 2021 Friends Science Publishers

Diversity of the BoLA-DRB3 Gene in Cattle Breeds From Tropical and Subtropical Regions of South America

Background Bovine leukocyte antigens (BoLA) are widely used as markers of disease and immunological traits in cattle because of their primary function in the recognition of pathogens by the immune system. To date, however, the characterization of BoLA gene polymorphisms in Latin American Zebu and mixed zebuine breeds is scarce. By a sequence-based typing method, here we sequenced exon 2 of BoLA class II DRB3 gene of 264 animals from the five breeds (Creole, Brahman, Braford, Brangus and Nellore) most commonly used in northern Argentina. Results The taurine and zebuine breeds contained 61 previously reported alleles. Genetic diversity was high at allelic and molecular levels, particularly in the mixed breeds. Neutrality tests revealed that none of the breeds shows the even gene frequency distribution expected under a balanced selection scenario. The FST index shows significant differences across all populations (FST=0.052, P < 0.001), indicating a substantial differentiation between breeds. UPGMA trees and Metric multidimensional scaling (MDS) analysis show that, as expected, Creole is distantlyrelated to the other zebuinebreeds. Among them, Brahman, Braford and Brangus cluster closer together than with Nellore. These data are consistent with the historical and geographical origin of these breeds. A peptide binding region sequence analysis at the aminoacid level revealed that, despite the nucleotide diversity among the breeds, the key aminoacids involved in peptide recognition are greatly conserved. Conclusions This is the first report of BoLA-DRB3 diversity in pure and mixed zebuine cattle breeds from Argentina. Knowledge ofBoLA-DRB3 variability in breeds adapted to tropical and subtropical environments contributes not only to ongoing efforts to catalog bovine MHC allele frequencies by breed and location but also to the design of peptide-based vaccines.

The new Coronavirus (SARS-CoV-2) in Central America: Demographic-spatial simulations, Analyses of Molecular Variance (AMOVA) and Neutrality Tests in complete genomes from Belize, Guatemala, Cuba, Jamaica and Puerto Rico

In this work, we evaluated the levels of genetic diversity in 38 complete genomes of SARS-CoV-2 from five Central American countries (Belize, Guatemala, Cuba, Jamaica and Puerto Rico) with 04, 10, 2, 8 and 14 haplotypes, respectively, with an extension of up to 29,885 bp. All sequences were publicly available on the National Biotechnology Information Center (NCBI) platform. Using specific methodologies for paired FST, AMOVA, mismatch, demographic-spatial expansion, molecular diversity and for the time of evolutionary divergence, it was possible to notice that only 79 sites remained conserved and that the high number of polymorphisms found helped to establish a clear pattern of genetic non-structuring, based on the time of divergence between the groups. The analyses also showed that significant evolutionary divergences within and between the five countries corroborate the fact that possible rapid and silent mutations are responsible for the increase in genetic variability of the Virus, a fact that would hinder the work with molecular targets for vaccines and medications in general.