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Within host evolution

Michaela H Kloesener, Joy Bose, Rebecca D Schulte
Host-parasite coevolution is predicted to have complex evolutionary consequences, potentially leading to the emergence of genetic and phenotypic diversity for both antagonists. However, little is known about variation in phenotypic responses to coevolution between different parasite strains exposed to the same experimental conditions. We infected Caenorhabditis elegans with one of two strains of Bacillus thuringiensis and either allowed the host and the parasite to experimentally coevolve (coevolution treatment) or allowed only the parasite to adapt to the host (one-sided parasite adaptation)...
July 17, 2017: Evolution; International Journal of Organic Evolution
Longlong Wang, Longxiang Wang, Yu Zhou, Deqiang Duanmu
Nitrogen-fixing rhizobia have established a symbiotic relationship with the legume family through more than 60 million years of evolution. Hundreds of legume host genes are involved in the SNF (symbiotic nitrogen fixation) process, such as recognition of the bacterial partners, nodulation signaling and nodule development, maintenance of highly efficient nitrogen fixation within nodules, regulation of nodule numbers, and nodule senescence. However, investigations of SNF-related gene functions and dissecting molecular mechanisms of the complicated signaling crosstalk on a genomic scale were significantly restricted by insufficient mutant resources of several representative model legumes...
2017: Progress in Molecular Biology and Translational Science
Brandon K B Seah, Thomas Schwaha, Jean-Marie Volland, Bruno Huettel, Nicole Dubilier, Harald R Gruber-Vodicka
Symbioses between eukaryotes and sulfur-oxidizing (thiotrophic) bacteria have convergently evolved multiple times. Although well described in at least eight classes of metazoan animals, almost nothing is known about the evolution of thiotrophic symbioses in microbial eukaryotes (protists). In this study, we characterized the symbioses between mouthless marine ciliates of the genus Kentrophoros, and their thiotrophic bacteria, using comparative sequence analysis and fluorescence in situ hybridization. Ciliate small-subunit rRNA sequences were obtained from 17 morphospecies collected in the Mediterranean and Caribbean, and symbiont sequences from 13 of these morphospecies...
July 12, 2017: Proceedings. Biological Sciences
John D Perpich, Awdhesh Kalia, Christopher T D Price, Snake C Jones, Kathy Wong, Kalle Gehring, Yousef Abu Kwaik
Within macrophages and amoeba, the Legionella-containing vacuole (LCV) membrane is derived from the ER. The bona fide F-box AnkB effector protein of L. pneumophila strain AA100/130b is anchored to the cytosolic side of the LCV membrane through host-mediated farnesylation of its C-terminal eukaryotic "CaaX" motif. Here we show that the AnkB homologue of the Paris strain has a frame shift mutation that led to a loss of the CaaX motif and a concurrent generation of a unique C-terminal KNKYAP motif, which resembles the eukaryotic di-lysine ER-retention motif (KxKxx)...
July 11, 2017: Scientific Reports
N B Chilton, M A Shuttleworth, F Huby-Chilton, A V Koehler, A Jabbar, R B Gasser, I Beveridge
Sequences of the first and second internal transcribed spacers (ITS1 + ITS2) of nuclear ribosomal DNA were employed to determine whether the congeneric assemblages of species of the strongyloid nematode genus Cloacina, found in the forestomachs of individual species of kangaroos and wallabies (Marsupialia: Macropodidae), considered to represent species flocks, were monophyletic. Nematode assemblages examined in the black-striped wallaby, Macropus (Notamacropus) dorsalis, the wallaroos, Macropus (Osphranter) antilopinus/robustus, rock wallabies, Petrogale spp...
July 12, 2017: Parasitology
Yuh Chwen G Lee, Gary H Karpen
Transposable elements (TEs) are widespread genomic parasites, and their evolution has remained a critical question in evolutionary genomics. Here, we study the relatively unexplored epigenetic impacts of TEs and provide the first genome-wide quantification of such effects in D. melanogaster and D. simulans. Surprisingly, the spread of repressive epigenetic marks (histone H3K9me2) to nearby DNA occurs at >50% of euchromatic TEs, and can extend up to 20 kb. This results in differential epigenetic states of genic alleles and, in turn, selection against TEs...
July 11, 2017: ELife
Minjie Fu, Bruce Waldman
Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), has been implicated in population declines and species extinctions of amphibians around the world. Susceptibility to the disease varies both within and among species, most likely attributable to heritable immunogenetic variation. Analyses of transcriptional expression in hosts following their infection by Bd reveal complex responses. Species resistant to Bd generally show evidence of stronger innate and adaptive immune system responses...
July 10, 2017: Immunogenetics
Beilei Wu, Mark P Zwart, Jesús A Sánchez-Navarro, Santiago F Elena
The existence of multipartite viruses is an intriguing mystery in evolutionary virology. Several hypotheses suggest benefits that should outweigh the costs of a reduced transmission efficiency and of segregation of coadapted genes associated with encapsidating each segment into a different particle. Advantages range from increasing genome size despite high mutation rates, faster replication, more efficient selection resulting from reassortment during mixed infections, better regulation of gene expression, or enhanced virion stability and cell-to-cell movement...
July 10, 2017: Scientific Reports
Travis N Mavrich, Graham F Hatfull
Bacteriophages play key roles in microbial evolution(1,2), marine nutrient cycling(3) and human disease(4). Phages are genetically diverse, and their genome architectures are characteristically mosaic, driven by horizontal gene transfer with other phages and host genomes(5). As a consequence, phage evolution is complex and their genomes are composed of genes with distinct and varied evolutionary histories(6,7). However, there are conflicting perspectives on the roles of mosaicism and the extent to which it generates a spectrum of genome diversity(8) or genetically discrete populations(9,10)...
July 10, 2017: Nature Microbiology
Ladislav Šimo, Maria Kazimirova, Jennifer Richardson, Sarah I Bonnet
As long-term pool feeders, ticks have developed myriad strategies to remain discreetly but solidly attached to their hosts for the duration of their blood meal. The critical biological material that dampens host defenses and facilitates the flow of blood-thus assuring adequate feeding-is tick saliva. Saliva exhibits cytolytic, vasodilator, anticoagulant, anti-inflammatory, and immunosuppressive activity. This essential fluid is secreted by the salivary glands, which also mediate several other biological functions, including secretion of cement and hygroscopic components, as well as the watery component of blood as regards hard ticks...
2017: Frontiers in Cellular and Infection Microbiology
Thibault Stalder, Linda M Rogers, Chris Renfrow, Hirokazu Yano, Zachary Smith, Eva M Top
Multidrug resistant bacterial pathogens have become a serious global human health threat, and conjugative plasmids are important drivers of the rapid spread of resistance to last-resort antibiotics. Whereas antibiotics have been shown to select for adaptation of resistance plasmids to their new bacterial hosts, or vice versa, a general evolutionary mechanism has not yet emerged. Here we conducted an experimental evolution study aimed at determining general patterns of plasmid-bacteria evolution. Specifically, we found that a large conjugative resistance plasmid follows the same evolutionary trajectories as its non-conjugative mini-replicon in the same and other species...
July 7, 2017: Scientific Reports
Hela El Kafsy, Guy Gorochov, Martin Larsen
Genetic evolution of multicellular organisms occurred as a response to environmental challenges, in particular competition for nutrients, climatic change, physical and chemical stressors and pathogens. However organism fitness depends on both the efficiency of its defences and its capacities for benefiting from its symbiotic organisms. Indeed microbes not only engender pathogenies, but enable efficient uptake of host non-self biodegradable nutriments. Furthermore, microbes play an important role in the development of host immunity...
2017: Biologie Aujourd'hui
Sayanta Bera, Manuel G Moreno-Pérez, Sara García-Figuera, Israel Pagán, Aurora Fraile, Luis F Pacios, Fernando García-Arenal
In gene-for-gene host-virus interactions, virus evolution to infect and multiply in previously resistant host genotypes, i.e., resistance-breaking, is a case of host range expansion, predicted to be associated with fitness penalties. Negative effects of resistance-breaking mutations on within-host virus multiplication have been documented for several plant viruses. However, understanding virus evolution requires analyses of potential trade-offs between different fitness components. Here we analyze if coat protein (CP) mutations in Pepper mild mottle virus breaking L-gene resistance in pepper affect particle stability and, thus, survival in the environment...
July 5, 2017: Journal of Virology
Christina Nagler, Marie K Hörnig, Joachim T Haug, Christoph Noever, Jens T Høeg, Henrik Glenner
Rhizocephala, a group of parasitic castrators of other crustaceans, shows remarkable morphological adaptations to their lifestyle. The adult female parasite consists of a body that can be differentiated into two distinct regions: a sac-like structure containing the reproductive organs (the externa), and a trophic, root like system situated inside the hosts body (the interna). Parasitism results in the castration of their hosts, achieved by absorbing the entire reproductive energy of the host. Thus, the ratio of the host and parasite sizes is crucial for the understanding of the parasite's energetic cost...
2017: PloS One
Rebbeca M Duar, Xiaoxi B Lin, Jinshui Zheng, Maria Elena Martino, Théodore Grenier, María Elisa Pérez-Muñoz, François Leulier, Michael Gänzle, Jens Walter
Lactobacillus species are found in nutrient-rich habitats associated with food, feed, plants, animals and humans. Due to their economic importance, the metabolism, genetics and phylogeny of lactobacilli have been extensively studied. However, past research primarily examined lactobacilli in experimental settings abstracted from any natural history, and the ecological context in which these bacteria exist and evolve has received less attention. In this review, we synthesize phylogenetic, genomic and metabolic metadata of the Lactobacillus genus with findings from fine-scale phylogenetic and functional analyses of representative species to elucidate the evolution and natural history of its members...
June 30, 2017: FEMS Microbiology Reviews
Yasir Mehmood, Prabhakaran Sambasivam, Sukhjiwan Kaur, Jenny Davidson, Audrey E Leo, Kristy Hobson, Celeste C Linde, Kevin Moore, Jeremy Brownlie, Rebecca Ford
The Australian Ascochyta rabiei (Pass.) Labr. (syn. Phoma rabiei) population has low genotypic diversity with only one mating type detected to date, potentially precluding substantial evolution through recombination. However, a large diversity in aggressiveness exists. In an effort to better understand the risk from selective adaptation to currently used resistance sources and chemical control strategies, the population was examined in detail. For this, a total of 598 isolates were quasi-hierarchically sampled between 2013 and 2015 across all major Australian chickpea growing regions and commonly grown host genotypes...
2017: Frontiers in Plant Science
Sunlu Chen, Huizhen Zheng, Yuji Kishima
The interplay of different virus species in a host cell after infection can affect the adaptation of each virus. Endogenous viral elements, such as endogenous pararetroviruses (PRVs), have arisen from vertical inheritance of viral sequences integrated into host germline genomes. As viral genomic fossils, these sequences can thus serve as valuable paleogenomic data to study the long-term evolutionary dynamics of virus-virus interactions, but they have rarely been applied for this purpose. All extant PRVs have been considered autonomous species in their parasitic life cycle in host cells...
June 2017: PLoS Pathogens
Rama H R Dadu, Rebecca Ford, Prabhakaran Sambasivam, Dorin Gupta
Substantial yield losses and poor seed quality are frequently associated with Ascochyta blight infection of lentil caused by Ascochyta lentis. Recently reported changes in aggressiveness of A. lentis have led to decreased resistance within cultivars, such as Northfield and Nipper in Australia. Furthermore, the narrow genetic base of the current breeding program remains a risk for further selective pathogen evolution to overcome other currently used resistances. Therefore, incorporation of potentially novel and diverse resistance genes into the advanced lines will aid to improve cultivar stability...
2017: Frontiers in Plant Science
McKenna J Penley, Levi T Morran
Hosts exhibit a variety of defence mechanisms against parasites, including avoidance. Both host-parasite coevolutionary dynamics and the host mating system can alter the evolutionary trajectories of populations. Does the nature of host-parasite interactions and the host mating system affect the mechanisms that evolve to confer host defence? In a previous experimental evolution study, mixed mating and obligately outcrossing Caenorhabditis elegans host populations adapted to either coevolving or static Serratia marcescens parasite populations...
June 28, 2017: Parasitology
Chaoyang Zhao, Paul D Nabity
BACKGROUND: The herbivore lifestyle leads to encounters with plant toxins and requires mechanisms to overcome suboptimal nutrient availability in plant tissues. Although the evolution of bacterial endosymbiosis alleviated many of these challenges, the ability to manipulate plant nutrient status has evolved in lineages with and without nutritional symbionts. Whether and how these alternative nutrient acquisition strategies interact or constrain insect evolution is unknown. We studied the transcriptomes of galling and free-living aphidomorphs to characterize how amino acid transporter evolution is influenced by the ability to manipulate plant resource availability...
June 27, 2017: BMC Evolutionary Biology
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