scholarly journals Hidden diversity of double-stranded DNA phages in symbiotic Rhizobium species

2021 ◽  
Vol 377 (1842) ◽  
Author(s):  
Rosa I. Santamaría ◽  
Patricia Bustos ◽  
Jannick Van Cauwenberghe ◽  
Víctor González
Keyword(s):  
Genetic Variation ◽  
Phylogenetic Tree ◽  
Gene Loss ◽  
Selective Pressure ◽  
Economic Importance ◽  
Viral Diversity ◽  
Theme Issue ◽  
Rhizobium Species ◽  
Double Stranded Dna ◽  
Geographical Locations

In this study, we addressed the extent of diversification of phages associated with nitrogen-fixing symbiotic Rhizobium species. Despite the ecological and economic importance of the Rhizobium genus, little is known about the diversity of the associated phages. A thorough assessment of viral diversity requires investigating both lytic phages and prophages harboured in diverse Rhizobium genomes. Protein-sharing networks identified 56 viral clusters (VCs) among a set of 425 isolated phages and predicted prophages. The VCs formed by phages had more proteins in common and a higher degree of synteny, and they group together in clades in the associated phylogenetic tree. By contrast, the VCs of prophages showed significant genetic variation and gene loss, with selective pressure on the remaining genes. Some VCs were found in various Rhizobium species and geographical locations, suggesting that they have wide host ranges. Our results indicate that the VCs represent distinct taxonomic units, probably representing taxa equivalent to genera or even species. The finding of previously undescribed phage taxa indicates the need for further exploration of the diversity of phages associated with Rhizobium species. This article is part of the theme issue ‘The secret lives of microbial mobile genetic elements’.

Viral Diversity, Evolution, and Selective Pressure

Norovirus ◽  
2019 ◽  
pp. 59-78
Author(s):  
Angelique Ealy ◽  
Kari Debbink
Keyword(s):  
Selective Pressure ◽  
Viral Diversity

High Levels of Genetic Variability in an Isolated Colony of Rock-wallabies (Petrogale assimilis): Evidence from Three Classes of Molecular Markers

1997 ◽  
Vol 45 (2) ◽  
pp. 199 ◽  
Author(s):  
Peter B. S. Spencer ◽  
Mark Adams ◽  
Helene Marsh ◽  
David J. Miller ◽  
Mark D. B. Eldridge
Keyword(s):  
Genetic Variation ◽  
Molecular Markers ◽  
Genetic Variability ◽  
Mating Systems ◽  
Selective Pressure ◽  
Multiple Mating ◽  
Dna Fingerprints ◽  
Average Heterozygosity ◽  
Low Levels ◽  
High Level

Estimates of genetic variation for a small (Ne = 39) colony of allied rock-wallabies (Petrogale assimilis) were calculated with three different categories of molecular marker. Average heterozygosity was estimated at 3·8% for allozymes, 47·3% for multilocus ‘DNA fingerprints’ and 85·5% for microsatellite markers. Overall these values indicate that this small isolated colony of rock-wallabies maintains a high level of genetic variation despite its relative isolation and the apparently low levels of migration between colonies. It is likely that mechanisms exist (such as kin avoidance, multiple mating systems, high and variable selective pressure in extreme and fluctuating environmental conditions) that promote the maintenance of high levels of genetic variation in isolated colonies of P. assimilis. These mechanisms are discussed in the context of the results obtained from the molecular markers.

scholarly journals AFLP Analysis for Genetic Diversity in Capsicum Annuum and Related Species

2006 ◽  
Vol 1 (3) ◽  
pp. 1934578X0600100
Author(s):  
Sanjog T. Thul ◽  
Ajit K. Shasany ◽  
Mahendra P. Darokar ◽  
Suman P. S. Khanuja
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Length Polymorphism ◽  
Great Degree ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
Aflp Analysis ◽  
Variation Analysis ◽  
Average Similarity ◽  
Geographical Locations

Intra- and inter-specific genetic variation analysis was conducted using amplified fragment length polymorphism (AFLP) profiling in Capsicum accessions in the germplasms collected from different geographical locations in India. A total of 24 accessions were investigated belonging to six species, namely C. annuum, C. baccatum, C. chinence, C. eximium, C. frutescens and C. luteum. Average similarity within the 15 accessions of C. annuum was highest (100%) between accessions CIMAP/CA45 and CIMAP/CA49 obtained from IISR, Kerala and 43% among the species CIMAP/CC1 and CIMAP/CB2. In this analysis, accessions were clustered more pronouncedly according to their geographical locations than to their taxonomic labels. A great degree of intermixing of present day domesticated chillies is evident from the present study.

scholarly journals Raw Sewage Harbors Diverse Viral Populations

mBio ◽  
2011 ◽  
Vol 2 (5) ◽  
Author(s):  
Paul G. Cantalupo ◽  
Byron Calgua ◽  
Guoyan Zhao ◽  
Ayalkibet Hundesa ◽  
Adam D. Wier ◽  
...  
Keyword(s):  
Genetic Material ◽  
Viral Diversity ◽  
Emerging Pathogens ◽  
Viral Genomes ◽  
Untreated Wastewater ◽  
Virus Diversity ◽  
Double Stranded Dna ◽  
Large Numbers ◽  
Ideal System ◽  
Species Specific

ABSTRACTAt this time, about 3,000 different viruses are recognized, but metagenomic studies suggest that these viruses are a small fraction of the viruses that exist in nature. We have explored viral diversity by deep sequencing nucleic acids obtained from virion populations enriched from raw sewage. We identified 234 known viruses, including 17 that infect humans. Plant, insect, and algal viruses as well as bacteriophages were also present. These viruses represented 26 taxonomic families and included viruses with single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), positive-sense ssRNA [ssRNA(+)], and dsRNA genomes. Novel viruses that could be placed in specific taxa represented 51 different families, making untreated wastewater the most diverse viral metagenome (genetic material recovered directly from environmental samples) examined thus far. However, the vast majority of sequence reads bore little or no sequence relation to known viruses and thus could not be placed into specific taxa. These results show that the vast majority of the viruses on Earth have not yet been characterized. Untreated wastewater provides a rich matrix for identifying novel viruses and for studying virus diversity.IMPORTANCEAt this time, virology is focused on the study of a relatively small number of viral species. Specific viruses are studied either because they are easily propagated in the laboratory or because they are associated with disease. The lack of knowledge of the size and characteristics of the viral universe and the diversity of viral genomes is a roadblock to understanding important issues, such as the origin of emerging pathogens and the extent of gene exchange among viruses. Untreated wastewater is an ideal system for assessing viral diversity because virion populations from large numbers of individuals are deposited and because raw sewage itself provides a rich environment for the growth of diverse host species and thus their viruses. These studies suggest that the viral universe is far more vast and diverse than previously suspected.

scholarly journals Proactive strategies to avoid infectious disease

2011 ◽  
Vol 366 (1583) ◽  
pp. 3361-3363 ◽  
Author(s):  
Richard J. Stevenson ◽  
Trevor I. Case ◽  
Megan J. Oaten
Keyword(s):  
Infectious Disease ◽  
Immune Responses ◽  
Mate Selection ◽  
Selective Pressure ◽  
Healthy Individuals ◽  
Disease Avoidance ◽  
Theme Issue ◽  
Shaping Process ◽  
Treatment Of Infection ◽  
Selection Of

Infectious disease exerts a large selective pressure on all organisms. One response to this has been for animals to evolve energetically costly immune systems to counter infection, while another—the focus of this theme issue—has been the evolution of proactive strategies primarily to avoid infection. These strategies can be grouped into three types, all of which demonstrate varying levels of interaction with the immune system. The first concerns maternal strategies that function to promote the immunocompetence of their offspring. The second type of strategy influences mate selection, guiding the selection of a healthy mate and one who differs maximally from the self in their complement of antigen-coding genes. The third strategy involves two classes of behaviour. One relates to the capacity of the organisms to learn associations between cues indicative of pathogen threat and immune responses. The other relates to prevention and even treatment of infection through behaviours such as avoidance, grooming, quarantine, medicine and care of the sick. In humans, disease avoidance is based upon cognition and especially the emotion of disgust. Human disease avoidance is not without its costs. There is a propensity to reject healthy individuals who just appear sick—stigmatization—and the system may malfunction, resulting in various forms of psychopathology. Pathogen threat also appears to have been a highly significant and unrecognized force in shaping human culture so as to minimize infection threats. This cultural shaping process—moralization—can be co-opted to promote human health.

scholarly journals Analisis Keragaman Genetik Acremonium yang Berasosiasi dengan Tanaman Gaharu Menggunakan Teknik Random Amplified Polymorphic DNA (RAPD)

2016 ◽  
Vol 5 (2) ◽  
pp. 65
Author(s):  
Dewi Rahmawati ◽  
Nurita Toruan-Mathius
Keyword(s):  
Cluster Analysis ◽  
Genetic Variation ◽  
Genetic Similarity ◽  
Random Amplified Polymorphic Dna ◽  
Economic Value ◽  
Similarity Index ◽  
Similarity Coefficients ◽  
West Sumatra ◽  
High Degree ◽  
Geographical Locations

<p>Agarwood<br />or gaharu is a plant that has a high economic value in Asia,<br />due to its use for production of incense and traditional<br />medicines. The agarwood formation occurs in the trunk and<br />roots of trees that have been infected by a fungus, such as<br />Acremonium spp. Various fungi were associated with the<br />agarwood formation. Acremonium is generally considered as<br />highly polyphyletic, contains distantly related fungi. A study<br />was done to identify genetic diversities in 10 isolates of<br />Acremonium spp. from four different areas in Indonesia that<br />are associated with Aquilaria and Gyrinops verstigii using the<br />Random Amplified Polymorphic DNA (RAPD) technique.<br />Eight RAPD primers, i.e., OPA 02, OPB 04, OPB 07, OPB 17,<br />OPC 11, OPD 03, OPD 05, and OPE 07 were used in the<br />analyses. The results indicated that similarity index values of<br />the genetic variation ranged from 0.21 to 0.97. Based on the<br />Nei and Li’s similarity coefficients, these values indicating<br />the presence of high degree of genetic variability. The lowest<br />degree of genetic similarity were found between isolates F<br />(Acremonium spp., which is associated with G. verstigii from<br />Mataram, Nusa Tenggara Barat), and LM2 from south coastal<br />area of West Sumatra. The highest genetic similarity value<br />(0.97) was found between isolates Sr2 and Sr4 from Sorong,<br />Papua. Results from the cluster analysis indicated that the<br />isolates could be grouped into two major clusters that were<br />associated with their geographical locations.</p>

scholarly journals Genetic variation and molecular relationships taxa of Conringia heist. ex Fabr. (Brassicaceae) based on RAPD markers in Turkey

Genetika ◽  
2020 ◽  
Vol 52 (1) ◽  
pp. 107-114
Author(s):  
Emre Sevġndġk ◽  
Yavuz Paksoy ◽  
Melike Aydoğan ◽  
Feyzanur Topseçer
Keyword(s):  
Genetic Variation ◽  
Phylogenetic Tree ◽  
Rapd Markers ◽  
Uv Light ◽  
Genetic Relationships ◽  
Genetic Distances ◽  
Genomic Dna Isolation ◽  
Pcr Products ◽  
Polymerase Chain ◽  
Molecular Relationships

In this study, genetic variation and phylogenetic analysis of 13 populations of 6 species belonging to Conringia genus spreading in Turkey were performed using RAPD markers. Genomic DNA isolation from the leaves of the Conringia plant samples was performed via using a commercial kit. Seven RAPD primers were used to identify the genetic diversity between the populations. Polymerase Chain Reaction (PCR) was performed using DNA samples and primers. PCR products were resolved using agarose gel electrophoresis and visualized under UV light. All gel images were analyzed, and the absence and presence of polymorphic bands were scored. The total of 34 DNA bands were detected by seven RAPD primers. PAUP 4.0b10 analysis program was used to calculate phylogenetic tree and genetic distances between the species. The phylogenetic tree was obtained using the UPGMA algorithm and it was composed of two clades. According to the PAUP analysis, the species having the closest distance between each other are C. planisiliqua (Ankara-Aya?) and C. planisiliqua (Ankara-Nall?han) with the value of 0.000 and those having the longest distance are C. grandiflora (Akseki ?ukurk?y) and C. orientalis (Elaz??-Baskil) with the value of 0.6000. The results suggest that the RAPD markers are useful tools to demonstrate the genetic relationships between populations of the Conringia species.

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