Analysis Of Molecular Data Research Articles

Phylotranscriptomics of Theaceae: generic-level relationships, reticulation and whole-genome duplication.

Theaceae, with three tribes, nine genera and more than 200 species, are of great economic and ecological importance. Recent phylogenetic analyses based on plastomic data resolved the relationships among the three tribes and the intergeneric relationships within two of those tribes. However, generic-level relationships within the largest tribe, Theeae, were not fully resolved. The role of putative whole-genome duplication (WGD) events in the family and possible hybridization events among genera within Theeae also remain to be tested further. Transcriptomes or low-depth whole-genome sequencing of 57 species of Theaceae, as well as additional plastome sequence data, were generated. Using a dataset of low-copy nuclear genes, we reconstructed phylogenetic relationships using concatenated, species tree and phylogenetic network approaches. We further conducted molecular dating analyses and inferred possible WGD events by examining the distribution of the number of synonymous substitutions per synonymous site (Ks) for paralogues in each species. For plastid protein-coding sequences , phylogenies were reconstructed for comparison with the results obtained from analysis of the nuclear dataset. Based on the 610 low-copy nuclear genes (858 606 bp in length) investigated, Stewartieae was resolved as sister to the other two tribes. Within Theeae, the Apterosperma-Laplacea clade grouped with Pyrenaria, leaving Camellia and Polyspora as sister. The estimated ages within Theaceae were largely consistent with previous studies based mainly on plastome data. Two reticulation events within Camellia and one between the common ancestor of Gordonia and Schima were found. All members of the tea family shared two WGD events, an older At-γ and a recent Ad-β; both events were also shared with the outgroups (Diapensiaceae, Pentaphylacaceae, Styracaceae and Symplocaceae). Our analyses using low-copy nuclear genes improved understanding of phylogenetic relationships at the tribal and generic levels previously proposed based on plastome data, but the phylogenetic position of the Apterosperma-Laplacea clade needs more attention. There is no evidence for extensive intergeneric hybridization within Theeae or for a Theaceae-specific WGD event. Land bridges (e.g. the Bering land bridge) during the Late Oligocene may have permitted the intercontinental plant movements that facilitated the putative ancient introgression between the common ancestor of Gordonia and Schima.

An integrative taxonomic revision of slug-eating snakes (Squamata: Pareidae: Pareineae) reveals unprecedented diversity in Indochina.

Slug-eating snakes of the subfamily Pareinae are an insufficiently studied group of snakes specialized in feeding on terrestrial mollusks. Currently Pareinae encompass three genera with 34 species distributed across the Oriental biogeographic region. Despite the recent significant progress in understanding of Pareinae diversity, the subfamily remains taxonomically challenging. Here we present an updated phylogeny of the subfamily with a comprehensive taxon sampling including 30 currently recognized Pareinae species and several previously unknown candidate species and lineages. Phylogenetic analyses of mtDNA and nuDNA data supported the monophyly of the three genera Asthenodipsas, Aplopeltura, and Pareas. Within both Asthenodipsas and Pareas our analyses recovered deep differentiation with each genus being represented by two morphologically diagnosable clades, which we treat as subgenera. We further apply an integrative taxonomic approach, including analyses of molecular and morphological data, along with examination of available type materials, to address the longstanding taxonomic questions of the subgenus Pareas, and reveal the high level of hidden diversity of these snakes in Indochina. We restrict the distribution of P. carinatus to southern Southeast Asia, and recognize two subspecies within it, including one new subspecies proposed for the populations from Thailand and Myanmar. We further revalidate P. berdmorei, synonymize P. menglaensis with P. berdmorei, and recognize three subspecies within this taxon, including the new subspecies erected for the populations from Laos and Vietnam. Furthermore, we describe two new species of Pareas from Vietnam: one belonging to the P. carinatus group from southern Vietnam, and a new member of the P. nuchalis group from the central Vietnam. We provide new data on P. temporalis, and report on a significant range extension for P. nuchalis. Our phylogeny, along with molecular clock and ancestral area analyses, reveal a complex diversification pattern of Pareinae involving a high degree of sympatry of widespread and endemic species. Our analyses support the “upstream” colonization hypothesis and, thus, the Pareinae appears to have originated in Sundaland during the middle Eocene and then colonized mainland Asia in early Oligocene. Sundaland and Eastern Indochina appear to have played the key roles as the centers of Pareinae diversification. Our results reveal that both vicariance and dispersal are responsible for current distribution patterns of Pareinae, with tectonic movements, orogeny and paleoclimatic shifts being the probable drivers of diversification. Our study brings the total number of Pareidae species to 41 and further highlights the importance of comprehensive taxonomic revisions not only for the better understanding of biodiversity and its evolution, but also for the elaboration of adequate conservation actions.

Notes on the taxonomy of species of Sciomyzini with a predominantly setulose anepisternum (Diptera, Sciomyzidae)

The present paper was conceived originally as a straightforward, simple description of a new African taxon. It grew substantially as more research was conducted. It now consists of four parts. In Part I, we discuss the taxonomy of five species of Sciomyzini with a predominantly setulose anepisternum: Atrichomelina pubera, Ditaeniella grisescens, D. trivittata, Pherbellia pilosa, and Ph. shatalkini. In Parts II and III, we consider the three taxa initially included in the genus Ditaeniella sensu Rozkošný (1987) (D. grisescens, D. parallela, and D. patagonensis) and the taxon described herein, D. milleri sp. nov., analysing this group by use of both the classical morphological approach (Part II) as well as by analysis of molecular data from available DNA barcodes (Part III). In Part IV, we provide a key to the taxa of Sciomyzini worldwide that have a predominantly setulose anepisternum. We also provide a list of specimens examined, the data from which significantly supplement the information previously available regarding the distribution of several Palaearctic species.

Population differentiation and gene flow of Glaucium flavum (Papaveraceae)

Yellow hornpoppy (Glaucium flavum Crantz.) is a herbaceous plant with gray-green leaves in coastal sands, rocky areas, and heavily eroded soils up to 500 meters above sea level. Glaucium flavum is native to Northern Africa, temperate zones in Western Asia and Europe, and is indigenous to Iran. The plant has been widely recognized for its aporphine-type isoquinoline alkaloids, which are pharmacologically active. Thus, we conducted a combination of morphological and molecular data analysis on such species because of the plant species' relevance. One hundred seven randomly collected plants from 14 natural populations in 5 provinces were evaluated using ISSR markers and morphological traits. The evaluation of molecular variance (AMOVA) demonstrated significant genetic divergence between the examined populations. It indicated that 25% of overall genetic variability was related to intra-population variety, whereas 75% was due to inter-population genetic differentiation. ISSR primers discovered 156 bands, 139 (83 %) of which have been polymorphic, each primer containing an average of 13 bands. The Polymorphic Bands (PPB) Percentage (ISSR-6) varied from 50% to 100%. (ISSR-1, ISSR-4, and ISSR-5). The average polymorphic information content (PIC), Shannon's information indexes (I), and several effective alleles (Ne) were correspondingly 0.39, 0.26, and 1.2.

Extracting physical characteristics of higher-order chromatin structures from 3D image data

Higher-order chromatin structures have functional impacts on gene regulation and cell identity determination. Using high-throughput sequencing (HTS)-based methods like Hi-C, active or inactive compartments and open or closed topologically associating domain (TAD) structures can be identified on a cell population level. Recently developed high-resolution three-dimensional (3D) molecular imaging techniques such as 3D electron microscopy with in situ hybridization (3D-EMSIH) and 3D structured illumination microscopy (3D-SIM) enable direct detection of physical representations of chromatin structures in a single cell. However, computational analysis of 3D image data with explainability and interpretability on functional characteristics of chromatin structures is still challenging. We developed Extracting Physical-Characteristics from Images of Chromatin Structures (EPICS), a machine-learning based computational method for processing high-resolution chromatin 3D image data. Using EPICS on images produced by 3D-EMISH or 3D-SIM techniques, we generated more direct 3D representations of higher-order chromatin structures, identified major chromatin domains, and determined the open or closed status of each domain. We identified several high-contributing features from the model as the major physical characteristics that define the open or closed chromatin domains, demonstrating the explainability and interpretability of EPICS. EPICS can be applied to the analysis of other high-resolution 3D molecular imaging data for spatial genomics studies. The R and Python codes of EPICS are available athttps://github.com/zang-lab/epics.

A retrospective analysis of serological & molecular testing data on dengue fever in Kolkata & adjacent districts during 2016-2019.

Regional Virus Research and Diagnostic Laboratory established at ICMR-National Institute of Cholera and Enteric Diseases (NICED) regularly receives samples for dengue screening and serotyping from patients of acute febrile illness (AFI) from Kolkata and adjacent districts. In this study, data over a three year period (August 2016-July 2019) was retrospectively analyzed to provide insight into the epidemiological trends of dengue fever in this region. Serological screening of dengue was performed by detection of NS1 antigen and/or immunoglobulin M (IgM) antibody. Dengue serotyping was done by conventional or real-time reverse transcriptase-PCR. The data were analyzed to describe the distribution of dengue with respect to age of patient, duration of fever on the day of blood collection and month of the year. Zip codes were used for spatial plotting. Out of the 24,474 samples received from Kolkata and its adjacent districts (Hooghly, Howrah, North and South 24 Parganas), 38.3 per cent (95% confidence interval: 37.7-38.9%) samples were screened positive for dengue. The correlation between age and dengue positivity was found to be weak. A combination of dengue NS1 antigen and dengue IgM antibody detection may be a better option for detecting dengue positivity compared to a single test. Most AFI cases were tested from August to November during the study period, with maximum dengue positivity noted during September (45.9%). The predominant serotype of 2016, dengue virus serotype 1 (DENV-1), was almost entirely replaced by DENV-2 in 2017 and 2018. Dengue continues to be an important cause of AFI in the region and round-the-year preventive measures are required for its control. Serotype switching is alarming and should be monitored routinely.

15. Standard procedure for the curation and maintenance of cancer-specific gene lists

The efficient analysis and interpretation of high throughput molecular genomics data are contingent upon reliable and current evidence-based resources. Gene lists to identify regions of diagnostic, prognostic, or therapeutic importance have become integral in the analysis of many clinical genomic tests, including chromosomal/SNP microarrays, NGS (Next Generation Sequencing) panels, and targeted whole exome/genome sequencing. Two Cancer Genomics Consortium (CGC) working groups in collaboration with the Mayo Clinic Genomics of Oncology Annotation Team (GOAT) have curated myeloid neoplasms and breast cancer gene lists with vetted annotation.

A Computational Protocol for Dating the Evolution of Cyanobacteria.

Cyanobacteria are known to play important roles in driving biological and geochemical innovations in ancient Earth. The origin of Cyanobacteria is the key to understanding these evolutionary events and thus has gained much interest to biologists and geobiologists. Recent development of the molecular dating approaches provides us an opportunity to assess the timeline of Cyanobacteria evolution based on relaxed clock models. The implementation of Bayesian phylogenetic approaches accommodates the uncertainties from different sources, such as fossil calibrations and topological structure of the phylogenomic tree, and provides us converged estimates of posterior mean ages. In this chapter, by taking Cyanobacteria as an example, we introduce a refined strategy to perform molecular dating analysis, as well as a practical method to evaluate the precision of dating analysis.

Genetic diversity and inter-relationship among Stellaria L. (Caryophyllaceae) species by ISSR markers

Stellaria L. (Caryophyllaceae, Alsinoideae) comprises ca. 150-200 species across the world. Stellaria species are common herbs, preferred humid mountainously slopes, but some grew in desert. Main center of diversification for Stellaria is Eurasia, with a center of distribution in the mountains of E. central Asia. Therefore, due to the importance of these plant species, we performed a molecular data analysis for this genus. For this study, we used 65 randomly collected plants from six species in six provinces. Amplification of genomic DNA using 5 primers produced 70 bands, of which 62 were polymorphic (84.00%). The obtained high average PIC and MI values revealed high capacity of ISSR primers to detect polymorphic loci among Stellaria species. The genetic similarities of six collections were estimated from 0.69 to 0.85. According to Inter-Simple sequence repeats (ISSR) markers analysis, S. pallida and S. graminea had the lowest similarity and the species of S. media and S. pallida had the highest similarity. The aims of present study are: 1) can ISSR markers identify Stellaria species, 2) what is the genetic structure of these taxa in Iran, and 3) to investigate the species inter-relationship? The present study revealed that ISSR markers can identify the species.

Untangling the Lactifluus clarkeae - Lf. flocktoniae(Russulaceae) species complex in Australasia.

The Lactifluus clarkeae complex is a commonly observed, generally brightly coloured, group of mushrooms that are usually associated with Nothofagus or Myrtaceous hosts in Australia and New Zealand. For this study collections labelled as 'Lactarius clarkeae', 'Russula flocktoniae' and 'Lactarius subclarkeae' were examined morphologically and molecularly. Analyses of molecular data showed a high cryptic diversity, with sequences scattered across 11 clades in three subgenera within Lactifluus, and a single collection in Russula. We select epitypes to anchor the currently accepted concepts of Lf. clarkeae s.str. and Lf. flocktoniae s.str. The name Lf. subclarkeae could not be applied to any of the collections examined, as none had a lamprotrichoderm pileipellis. Lactifluus clarkeae var. aurantioruber is raised to species level, and six new species are described, three in subg. Lactifluus: Lf. jetiae, Lf. pagodicystidiatus, and Lf. rugulostipitatus, and three in subg. Gymnocarpi: Lf. albens, Lf. psammophilus, and Lf. pseudoflocktoniae. A new collection of Lf. russulisporus provides a significant range extension for the species. Untangling this complex will enable better identification of species and increase understanding of diversity and specific habitat associations of macrofungi. Citation: Lebel T, Douch J, Tegart L, et al. 2021. Untangling the Lactifluus clarkeae - Lf. flocktoniae (Russulaceae) species complex in Australasia. Persoonia 47: 1-44. https://doi.org/10.3767/persoonia.2021.47.01.

Molecular persistent spectral image (Mol-PSI) representation for machine learning models in drug design.

Artificial intelligence (AI)-based drug design has great promise to fundamentally change the landscape of the pharmaceutical industry. Even though there are great progress from handcrafted feature-based machine learning models, 3D convolutional neural networks (CNNs) and graph neural networks, effective and efficient representations that characterize the structural, physical, chemical and biological properties of molecular structures and interactions remain to be a great challenge. Here, we propose an equal-sized molecular 2D image representation, known as the molecular persistent spectral image (Mol-PSI), and combine it with CNN model for AI-based drug design. Mol-PSI provides a unique one-to-one image representation for molecular structures and interactions. In general, deep models are empowered to achieve better performance with systematically organized representations in image format. A well-designed parallel CNN architecture for adapting Mol-PSIs is developed for protein-ligand binding affinity prediction. Our results, for the three most commonly used databases, including PDBbind-v2007, PDBbind-v2013 and PDBbind-v2016, are better than all traditional machine learning models, as far as we know. Our Mol-PSI model provides a powerful molecular representation that can be widely used in AI-based drug design and molecular data analysis.

A taxonomic outline of the Poecilimon affinis complex (Orthoptera) using the geometric morphometric approach

The genus Poecilimon contains 145 species, widely distributed in the Palaearctic, among which the Poecilimon ornatus group has the greatest diversity in the Balkans. Despite several revisions of the genus, the systematics of the species group, and in particular, of the taxa associated with the species Poecilimon affinis, is still unsolved. Due to morphological similarity, P. affinis with its subspecies, P. nonveilleri and P. pseudornatus form the Poecilimon affinis complex. The aim of this study is to test the hypotheses of an outlined species complex, namely the P. affinis complex, within the P. ornatus group using morphological data. Geometric analysis was conducted to explore variation in the structure of the male tegmen, ovipositor, male cercus, and male pronotum. The number of teeth and stridulatory file measurements provided additional information on morphological variation within the complex. A phylogenetic tree based on the cytochrome c oxidase subunit I gene (COI) was used for comparison with the morphological data. Canonical variate analysis showed that male tegmen and male cercus are good morphostructures to distinguish the taxa belonging to the P. affinis complex from other species in the P. ornatus group. This may confirm our assumption for the designation of the P. affinis complex. The results of the principal component analysis of stridulatory file measurements, molecular data, and CVA of the ovipositor suggest adding two additional species to the complex: P. ornatus and P. hoelzeli.

Molecular identification and genetic relationships among Alcea (Malvaceae) species by ISSR Markers: A high value medicinal plant

Alcea L. is one of the largest genera of Malvaceae family with nearly 70 species worldwide mainly distributed in SW Asia. According to the latest revision of the family, it is represented by 34 species in the Flora of Iran, among them, 15 species are endemic. It is tough to accurate germplasm/ plant recognition by using morphological characteristics because of its propagation, growing and using. We conducted a molecular data analysis on these plant species due to their importance. We examined 156 plants from 14 species in 16 regions that were selected randomly for this investigation. It has been 119 polymorphic bands (94.33%) were resulted from 128 bands of 10 primers in amplification of genomic DNA. ISSR primers have a great capacity to detect polymorphic loci among Alcea species, as evidenced by the high average PIC and MI values found. The genetic similarity of 14 species was calculated and ranged between 0.635 to 0.990. Inter-Simple sequence repeats (ISSR) markers research revealed that Alcea tarica Pakravan & Ghahreman and Alcea kopetdaghensis lljin had the least similarity, while Alcea semnanica Pakravan and Alcea mazandaranica Pakravan & Ghahreman had the most. The current study attempts to answer three questions: 1) can ISSR markers identify Alcea species? 2) what is the genetic structure of these taxa in Iran? and 3) what is the inter-relationship between these taxa? The current study discovered that ISSR markers can be used to identify species.

Integrative Analysis of Molecular and Physiological Data to Quantify Biological Aging

Development of reliable and valid measurements to quantify biological aging is a critical frontier geroscience. Originating in accumulations of molecular changes, biological aging undermines resilience within cellular networks and organ systems, driving disease, disability, and mortality. Measurements of biological aging have been proposed at several molecular and physiological levels of analysis. But agreement between measures implemented at different levels of analysis is low. The timing at which aging processes manifest at different levels of biological organization may vary, with the result that signs of aging manifest in one level of analysis are not yet observable in another. And different aging processes may be most apparent in different molecular levels of analysis. In midlife humans, aging-related changes are manifest at multiple molecular and physiological levels, making this population ideal for development of measurements that integrate information across levels of analysis to more precisely quantify the state and pace of biological aging.

A first insight into genetic diversity of Jerusalem artichoke accessions collected from different regions of Turkey assessed by ISSR markers

The study aimed to assess genetic diversity among Jerusalem artichoke (Helianthus tuberosus L.) accessions using ISSR (Inter Simple Sequence Repeat) markers. Twenty-five Jerusalem artichoke accessions collected from the different regions of Turkey have been used for molecular analysis. Nine primers used in the study produced a total of 62 bands. A total 57 of these are polymorphic. 57 of them resulted in polymorphic. Allele's average number was 6.33. Polymorphic information content (PIC) varied between 0.219 and 0.340. Examined accessions were classified into two main groups in a dendrogram. Genetic similarities varied from 0.001 to 0.815, with an average of 0.292. Also, Principal Coordinate Analysis (PCoA) of molecular data was conducted. These findings present valuable diversity data for recognizing the Jerusalem artichoke germplasm, preserving genetic richness, and determining parents for genetic enhancement.

Batch effect reduction of microarray data with dependent samples using an empirical Bayes approach (BRIDGE).

Batch-effects present challenges in the analysis of high-throughput molecular data and are particularly problematic in longitudinal studies when interest lies in identifying genes/features whose expression changes over time, but time is confounded with batch. While many methods to correct for batch-effects exist, most assume independence across samples; an assumption that is unlikely to hold in longitudinal microarray studies. We propose Batch effect Reduction of mIcroarray data with Dependent samples usinGEmpirical Bayes (BRIDGE), a three-step parametric empirical Bayes approach that leverages technical replicate samples profiled at multiple timepoints/batches, so-called "bridge samples", to inform batch-effect reduction/attenuation in longitudinal microarray studies. Extensive simulation studies and an analysis of a real biological data set were conducted to benchmark the performance of BRIDGE against both ComBat and longitudinalComBat. Our results demonstrate that while all methods perform well in facilitating accurate estimates of time effects, BRIDGE outperforms both ComBat and longitudinal ComBat in the removal of batch-effects in data sets with bridging samples, and perhaps as a result, was observed to have improved statistical power for detecting genes with a time effect. BRIDGE demonstrated competitive performance in batch effect reduction of confounded longitudinal microarray studies, both in simulated and a real data sets, and may serve as a useful preprocessing method for researchers conducting longitudinal microarray studies that include bridging samples.

Revalidation of Mazama rufa (Illiger 1815) (Artiodactyla: Cervidae) as a Distinct Species out of the Complex Mazama americana (Erxleben 1777).

The red brocket deer Mazama americana Erxleben, 1777 is considered a polyphyletic complex of cryptic species with wide chromosomal divergence. Evidence indicates that the observed chromosomal divergences result in reproductive isolation. The description of a neotype for M. americana allowed its genetic characterization and represented a comparative basis to resolve the taxonomic uncertainties of the group. Thus, we designated a neotype for the synonym Mazama rufa Illiger, 1815 and tested its recognition as a distinct species from the M. americana complex with the analysis of morphological, cytogenetic and molecular data. We also evaluated its distribution by sampling fecal DNA in the wild. Morphological data from craniometry and body biometry indicated an overlap of quantitative measurements between M. rufa and the entire M. americana complex. The phylogenetic hypothesis obtained through mtDNA confirmed the reciprocal monophyly relationship between M. americana and M. rufa, and both were identified as distinct molecular operational taxonomic units by the General Mixed Yule Coalescent species delimitation analysis. Finally, classic cytogenetic data and fluorescence in situ hybridization with whole chromosome painting probes showed M. rufa with a karyotype of 2n = 52, FN = 56. Comparative analysis indicate that at least fifteen rearrangements separate M. rufa and M. americana (sensu stricto) karyotypes, which confirmed their substantial chromosomal divergence. This divergence should represent an important reproductive barrier and allow its characterization as a distinct and valid species. Genetic analysis of fecal samples demonstrated a wide distribution of M. rufa in the South American continent through the Atlantic Forest, Cerrado and south region of Amazon. Thus, we conclude for the revalidation of M. rufa as a distinct species under the concept of biological isolation, with its karyotype as the main diagnostic character. The present work serves as a basis for the taxonomic review of the M. americana complex, which should be mainly based on cytogenetic characterization and directed towards a better sampling of the Amazon region, the evaluation of available names in the species synonymy and a multi-locus phylogenetic analysis.

The dominant TP53 hotspot mutation in IDH -mutant astrocytoma, R273C, has distinctive pathologic features and sex-specific prognostic implications.

BackgroundInfiltrative astrocytic tumors with and without isocitrate dehydrogenase (IDH) mutation frequently contain mutations in the TP53 tumor suppressor gene. Disruption of normal p53 protein activity confers neoplastic cells with a number of oncogenic properties and is a common feature of aggressive malignancies. However, the high prevalence of TP53 mutation and its pathogenic role in IDH-mutant (IDHmut) astrocytoma is not well understood.MethodsWe performed a retrospective analysis of molecular and clinical data from patients with IDHmut astrocytoma at the University of Pittsburgh Medical Center between 2015 and 2019 as our initial cohort. We validated and expanded our findings using molecular and clinical data from The Cancer Genome Atlas.ResultsWe show that the TP53 mutational spectrum in IDHmut astrocytomas is dominated by a single hotspot mutation that codes for the R273C amino acid change. This mutation is not enriched in IDH-wildtype astrocytomas. The high prevalence of TP53R273C mutation is not readily explained by known mutagenic mechanisms, and TP53R273C mutant tumors have lower transcriptional levels of proliferation-related genes compared to IDHmut astrocytomas harboring other forms of mutant p53. Despite lower proliferation, TP53R273C mutant tumors tend to progress more quickly and have a shorter overall survival than those with other TP53 mutations, particularly in male patients.ConclusionsOur findings suggest that compared to other TP53 mutations, IDHmut astrocytomas may select for TP53R273C mutations during tumorigenesis. The genotype, sex, and mutation-specific findings are clinically relevant and should prompt further investigation of TP53R273C.

Genetic diversity and population structure of Indian willow (Salix tetrasperma Roxb.) along its distributional range in the Himalayan region

Indian willow ( Salix tetrasperma ) is distributed across India, South China, Indo Malaya to Java along the banks of rivers and streams in wet swampy areas. Different parts of the plant have been used as traditional medicine due to the presence of compounds such as catechol, salicin and their derivatives. Leaves of the plant are used as fodder while its wood is used as fuel, agricultural tools, furniture and soil binder on embankments. The genetic diversity and population structure of Indian willow populations of North India was examined using 25 microsatellites. The observed heterozygosity (0.70 ± 0.03) was higher than the expected heterozygosity (0.50 ± 0.015) and fixation index of populations (−0.39 ± 0.03) confirmed the outcrossing nature of the species. The genetic differentiation (Fst = 0.081) and gene flow among populations (Nm = 2.85) was moderate. Genetic distance was found significant with geographic distance (R 2 = 0.11) as per Mantel test. Bayesian clustering pattern through STRUCTURE software showed existence of three gene pools which was further supported by principal coordinate and cluster analysis of molecular data. This study will be helpful in formulating conservation strategies and developing effective selection strategies for genetic improvement of Salix tetrasperma .

Underlying selection for the diversity of spike protein sequences of SARS-CoV-2.

The global spread of SARS‐CoV‐2 is fast moving and has caused a worldwide public health crisis. In the present article, we analyzed spike protein sequences of SARS‐CoV‐2 genomes to assess the impact of mutational diversity. We observed from amino acid usage patterns that spike proteins are associated with a diversity of mutational changes and most important underlying cause of variation of amino acid usage is the changes in hydrophobicity of spike proteins. The changing patterns of hydrophobicity of spike proteins over time and its influence on the receptor binding affinity provides crucial information on the SARS‐CoV‐2 interaction with human receptor. Our results also show that spike proteins have evolved to prefer more hydrophobic residues over time. The present study provides a comprehensive analysis of molecular sequence data to consider that mutational variants might play a crucial role in modulating the virulence and spread of the virus and has immediate implications for therapeutic strategies.