scholarly journals Overestimation of the adaptive substitution rate in fluctuating populations

2018 ◽  
Vol 14 (5) ◽  
pp. 20180055 ◽  
Author(s):  
Marjolaine Rousselle ◽  
Maeva Mollion ◽  
Benoit Nabholz ◽  
Thomas Bataillon ◽  
Nicolas Galtier
Keyword(s):  
Substitution Rate ◽  
Population History ◽  
Comparative Genomic ◽  
Coding Sequences ◽  
Potential Source ◽  
Genomic Studies ◽  
Demographic Fluctuations ◽  
Fluctuating Populations ◽  
Adaptive Substitution

Estimating the proportion of adaptive substitutions ( α ) is of primary importance to uncover the determinants of adaptation in comparative genomic studies. Several methods have been proposed to estimate α from patterns polymorphism and divergence in coding sequences. However, estimators of α can be biased when the underlying assumptions are not met. Here we focus on a potential source of bias, i.e. variation through time in the long-term population size ( N ) of the considered species. We show via simulations that ancient demographic fluctuations can generate severe overestimations of α , and this is irrespective of the recent population history.

scholarly journals Comparative Virulence and Genomic Analysis of Streptococcus suis Isolates

2021 ◽  
Vol 11 ◽  
Author(s):  
Tracy L. Nicholson ◽  
Ursula Waack ◽  
Tavis K. Anderson ◽  
Darrell O. Bayles ◽  
Sam R. Zaia ◽  
...  
Keyword(s):  
Systemic Disease ◽  
Streptococcus Suis ◽  
Comparative Genomic ◽  
Functional Genomic ◽  
Protein Coding ◽  
Genetic Characteristics ◽  
Coding Sequences ◽  
Allelic Replacement ◽  
Disease Outcomes ◽  
Genomic Studies

Streptococcus suis is a zoonotic bacterial swine pathogen causing substantial economic and health burdens to the pork industry. Mechanisms used by S. suis to colonize and cause disease remain unknown and vaccines and/or intervention strategies currently do not exist. Studies addressing virulence mechanisms used by S. suis have been complicated because different isolates can cause a spectrum of disease outcomes ranging from lethal systemic disease to asymptomatic carriage. The objectives of this study were to evaluate the virulence capacity of nine United States S. suis isolates following intranasal challenge in swine and then perform comparative genomic analyses to identify genomic attributes associated with swine-virulent phenotypes. No correlation was found between the capacity to cause disease in swine and the functional characteristics of genome size, serotype, sequence type (ST), or in vitro virulence-associated phenotypes. A search for orthologs found in highly virulent isolates and not found in non-virulent isolates revealed numerous predicted protein coding sequences specific to each category. While none of these predicted protein coding sequences have been previously characterized as potential virulence factors, this analysis does provide a reliable one-to-one assignment of specific genes of interest that could prove useful in future allelic replacement and/or functional genomic studies. Collectively, this report provides a framework for future allelic replacement and/or functional genomic studies investigating genetic characteristics underlying the spectrum of disease outcomes caused by S. suis isolates.

scholarly journals High-Density Genetic Map Construction and Identification of QTLs Controlling Leaf Abscission Trait in Poncirus trifoliata

2021 ◽  
Vol 22 (11) ◽  
pp. 5723
Author(s):  
Yuan-Yuan Xu ◽  
Sheng-Rui Liu ◽  
Zhi-Meng Gan ◽  
Ren-Fang Zeng ◽  
Jin-Zhi Zhang ◽  
...  
Keyword(s):  
Qtl Mapping ◽  
Linkage Map ◽  
Genetic Map ◽  
Expression Patterns ◽  
High Density ◽  
Poncirus Trifoliata ◽  
Leaf Abscission ◽  
Comparative Genomic ◽  
Map Comparison ◽  
Genomic Studies

A high-density genetic linkage map is essential for genetic and genomic studies including QTL mapping, genome assembly, and comparative genomic analysis. Here, we constructed a citrus high-density linkage map using SSR and SNP markers, which are evenly distributed across the citrus genome. The integrated linkage map contains 4163 markers with an average distance of 1.12 cM. The female and male linkage maps contain 1478 and 2976 markers with genetic lengths of 1093.90 cM and 1227.03 cM, respectively. Meanwhile, a genetic map comparison demonstrates that the linear order of common markers is highly conserved between the clementine mandarin and Poncirus trifoliata. Based on this high-density integrated citrus genetic map and two years of deciduous phenotypic data, two loci conferring leaf abscission phenotypic variation were detected on scaffold 1 (including 36 genes) and scaffold 8 (including 107 genes) using association analysis. Moreover, the expression patterns of 30 candidate genes were investigated under cold stress conditions because cold temperature is closely linked with the deciduous trait. The developed high-density genetic map will facilitate QTL mapping and genomic studies, and the localization of the leaf abscission deciduous trait will be valuable for understanding the mechanism of this deciduous trait and citrus breeding.

scholarly journals The Diversity and Evolution of Sex Chromosomes in Frogs

Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 483
Author(s):  
Wen-Juan Ma ◽  
Paris Veltsos
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Comparative Genomic ◽  
Ancestral State ◽  
Heteromorphic Sex Chromosomes ◽  
Genomic Studies ◽  
Evolutionary Trajectories ◽  
Heterogametic Sex

Frogs are ideal organisms for studying sex chromosome evolution because of their diversity in sex chromosome differentiation and sex-determination systems. We review 222 anuran frogs, spanning ~220 Myr of divergence, with characterized sex chromosomes, and discuss their evolution, phylogenetic distribution and transitions between homomorphic and heteromorphic states, as well as between sex-determination systems. Most (~75%) anurans have homomorphic sex chromosomes, with XY systems being three times more common than ZW systems. Most remaining anurans (~25%) have heteromorphic sex chromosomes, with XY and ZW systems almost equally represented. There are Y-autosome fusions in 11 species, and no W-/Z-/X-autosome fusions are known. The phylogeny represents at least 19 transitions between sex-determination systems and at least 16 cases of independent evolution of heteromorphic sex chromosomes from homomorphy, the likely ancestral state. Five lineages mostly have heteromorphic sex chromosomes, which might have evolved due to demographic and sexual selection attributes of those lineages. Males do not recombine over most of their genome, regardless of which is the heterogametic sex. Nevertheless, telomere-restricted recombination between ZW chromosomes has evolved at least once. More comparative genomic studies are needed to understand the evolutionary trajectories of sex chromosomes among frog lineages, especially in the ZW systems.

Will Strategy Prevail over Economics? An Analysis of Charanka Solar Park in Gujarat

2016 ◽  
Vol 5 (2) ◽  
pp. 162-167
Author(s):  
Saif Siddiqui ◽  
Sumaira Jan
Keyword(s):  
Solar Energy ◽  
Solar Power ◽  
Power Production ◽  
Energy Crisis ◽  
Energy Sources ◽  
Potential Source ◽  
The World ◽  
Made In

The Charanka Solar Park, one of the world’s largest multi-developer and multi-beneficiary solar parks, is the hub of solar power production in India. It contributes about 6 per cent to the total solar power production in the country. Although solar power is more expensive than the traditional power in the country, its sheen is still not high to make it a potential source to eliminate energy crisis not just in India but all across the world. Researchers are continuously pushing their envelope to explore as to why solar energy should be adopted over traditional energy sources irrespective of the fact that it is more expensive. The war between its financial and strategic viability is going on. Efforts are being made in the direction of reducing its costs and making it as a financially viable and strategically active option. This case is an attempt in the same direction. We are using Charanka Solar Park as a base to explore if there is any future for such projects in the country. There are projects which are no doubt operational but their long-term viability is truly questionable.

scholarly journals Identification of RD5-EncodedMycobacterium tuberculosisProteins As B-Cell Antigens Used for Serodiagnosis of Tuberculosis

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Miao-Miao Zhang ◽  
Jun-Wei Zhao ◽  
Zhan-Qiang Sun ◽  
Jun Liu ◽  
Xiao-Kui Guo ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Detection Sensitivity ◽  
Comparative Genomic ◽  
Healthy Controls ◽  
Specific Diagnosis ◽  
Pulmonary Tb ◽  
Genomic Studies ◽  
Immunodominant Antigens ◽  
Genomic Regions ◽  
Hiv Negative

Comparative genomic studies have identified severalMycobacterium tuberculosis-specific genomic regions of difference (RDs) which are absent in the vaccine strains ofMycobacterium bovisBCG and which may be useful in the specific diagnosis of tuberculosis (TB). In this study, all encoded proteins from DNA segment RD5 ofMycobacterium tuberculosis, that is, Rv3117–Rv3121, were recombined and evaluated by enzyme-linked immunosorbent assays for antibody reactivity with sera from HIV-negative pulmonary TB patients (n=60) and healthy controls (n=32). The results identified two immunodominant antigens, that is, Rv3117 and Rv3120, both of which revealed a statistically significant antigenic distinction between healthy controls and TB patients (P<0.05). In comparison with the well-known early-secreted antigen target 6 kDa (ESAT-6) (sensitivity 21.7%, specificity 90.6%), the higher detection sensitivity and higher specificity were achieved (Rv3117: sensitivity 25%, specificity 96.9%; Rv3120: sensitivity 31.7%, specificity 96.9%). Thus, the results highlight the immunosensitive and immunospecific nature of Rv3117 and Rv3120 and indicate promise for their use in the serodiagnosis of TB.

scholarly journals Novel start codons introduce novel coding sequences in the human genomes

2020 ◽  
Author(s):  
He Zhang ◽  
Yang Xie
Keyword(s):  
Translation Initiation ◽  
Genomic Analysis ◽  
Comparative Genomic ◽  
Human Populations ◽  
The Novel ◽  
Coding Sequences ◽  
Human Genomes ◽  
High Level ◽  
Selection Signal ◽  
Human Specific

AbstractStart-gain mutations can introduce novel start codons and generate novel coding sequences that may affect the function of genes. In this study, we systematically investigated the novel start codons that were either polymorphic or fixed in the human genomes. 829 polymorphic start-gain SNVs were identified in the human populations, and the novel start codons introduced by these SNVs have significantly higher activity in translation initiation. Some of these start-gain SNVs were reported to be associated with phenotypes and diseases in previous studies. By comparative genomic analysis, we found 26 human-specific start codons that were fixed after the divergence between the human and chimpanzee, and high-level translation initiation activity was observed on them. The negative selection signal was detected in the novel coding sequences introduced by these human-specific start codons, indicating the important function of these novel coding sequences. This study reveals start-gain mutations are keeping appearing in the human genomes during the evolution and may be important sources altering the function of genes which may further affect the phenotypes or cause diseases.

scholarly journals Unexpected cryptic species among streptophyte algae most distant to land plants

2021 ◽  
Vol 288 (1963) ◽  
Author(s):  
Iker Irisarri ◽  
Tatyana Darienko ◽  
Thomas Pröschold ◽  
Janine M. R. Fürst-Jansen ◽  
Mahwash Jamy ◽  
...  
Keyword(s):  
Land Plants ◽  
Comparative Genomic ◽  
Future Studies ◽  
Form And Function ◽  
Genomic Studies ◽  
Plant Form ◽  
Phylogenomic Analyses ◽  
And Function ◽  
Shed Light ◽  
Green Lineage

Streptophytes are one of the major groups of the green lineage (Chloroplastida or Viridiplantae). During one billion years of evolution, streptophytes have radiated into an astounding diversity of uni- and multicellular green algae as well as land plants. Most divergent from land plants is a clade formed by Mesostigmatophyceae, Spirotaenia spp. and Chlorokybophyceae. All three lineages are species-poor and the Chlorokybophyceae consist of a single described species, Chlorokybus atmophyticus. In this study, we used phylogenomic analyses to shed light into the diversity within Chlorokybus using a sampling of isolates across its known distribution. We uncovered a consistent deep genetic structure within the Chlorokybus isolates, which prompted us to formally extend the Chlorokybophyceae by describing four new species. Gene expression differences among Chlorokybus species suggest certain constitutive variability that might influence their response to environmental factors. Failure to account for this diversity can hamper comparative genomic studies aiming to understand the evolution of stress response across streptophytes. Our data highlight that future studies on the evolution of plant form and function can tap into an unknown diversity at key deep branches of the streptophytes.

scholarly journals DNA Amplifications and Aneuploidy, High Proliferative Activity and Impaired Cell Cycle Control Characterize Breast Carcinomas with Poor Prognosis

2003 ◽  
Vol 25 (3) ◽  
pp. 103-114 ◽  
Author(s):  
Harald Blegen ◽  
John S. Will ◽  
B. Michael Ghadimi ◽  
Hesed‐Padilla Nash ◽  
Anders Zetterberg ◽  
...  
Keyword(s):  
Copy Number ◽  
Proliferative Activity ◽  
Distant Metastases ◽  
Comparative Genomic ◽  
Short Term ◽  
Ki 67 ◽  
Chromosomal Copy ◽  
Copy Number Changes ◽  
Long Term Survivors

In order to explore whether specific cytogenetic abnormalities can be used to stratify tumors with a distinctly different clinical course, we performed comparative genomic hybridization (CGH) of tumors from patients who were diagnosed with metastatic disease after an interval of less than 2 years or who remained free from distant metastases for more than 10 years. All patients presented with distant metastases after mastectomy indicating that none of the patients in this study was cured and free of remaining tumor cells. Tumors in the group of short‐term survivors showed a higher average number of chromosomal copy alterations compared to the long‐term survivors. Of note, the number of sub‐chromosomal high‐level copy number increases (amplifications) was significantly increased in the group of short‐term survivors. In both short‐ and long‐term survivors recurrent chromosomal gains were mapped to chromosomes 1q, 4q, 8q, and 5p. Copy number changes that were more frequent in the group of short‐term survivors included gains of chromosome 3q, 9p, 11p and 11q and loss of 17p. Our results indicate that low‐ and high grade malignant breast adenocarcinomas are characterized by a specific pattern of chromosomal copy number changes. Furthermore, immunohistochemical evaluation of the expression levels of Ki‐67, p27KIP1, p21WAF1, p53, cyclin A and cyclin E revealed a correlation between increased proliferative activity and poor outcome.

Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques

2010 ◽  
Keyword(s):  
Fish Community ◽  
Larval Fish ◽  
Rank Order ◽  
Food Resource ◽  
Rio Grande ◽  
Reproductive Phenology ◽  
Comparative Genomic ◽  
Spawning Cues ◽  
Long Term Studies

<em>Abstract</em>.—Timing of reproduction differs among fish species in nearly all rivers, and reproductive phenology is predicted to strongly influence freshwater fish community structure in some systems. Despite its potential importance, few long-term studies of reproductive phenology in river fishes have been conducted in a community context. Here, we evaluated timing and sequence of reproduction of fishes in the Rio Grande, New Mexico over 9 years. Dates and rank order of first appearance of larvae varied among species and years, but three consistent spawning guilds were evident: early season, late season, and species that were intermediate in rank order of spawning. We hypothesized that appropriate reproductive timing enhanced recruitment to the extent that spawning cues predicted future availability of critical resources for larvae. Analysis of historical discharge records indicated that present and future discharge exhibited positive autocorrelation for up to 90 d. Likewise, larval fish densities were highest at moderate flows and coincident with high food resource abundance. However, stable isotope data for larval and adult fishes indicated considerable overlap in food resource use among larvae and adult fishes. There may be pressure for spawning time to converge among species to match the appearance of seasonal resources, but to diverge to lessen competition among young-of-year fishes in a classical trade-off scenario. More long-term studies are needed, and we propose that an integrated research program that combines detailed analysis of reproductive phenology, food web dynamics, and comparative genomic analyses could forge connections between environmental variation in spawning cues, recruitment success, and community assembly in river fishes. Such an integrated program could lead to better predictions about fish community responses to global warming, especially in vulnerable arid-land systems like the Rio Grande.

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