Brachypodium distachyon line Bd3-1 resistance is elicited by the barley stripe mosaic virus triple gene block 1 movement protein

Barley stripe mosaic virus North Dakota 18 (ND18), Beijing (BJ), Xinjiang (Xi), Type (TY) and CV21 strains are unable to infect the Brachypodium distachyon Bd3-1 inbred line, which harbours a resistance gene designated Bsr1, but the Norwich (NW) strain is virulent on Bd3-1. Analysis of ND18 and NW genomic RNA reassortants and RNA beta mutants demonstrates that two amino acids within the helicase motif of the triple gene block 1 (TGB1) movement protein have major effects on their Bd3-1 phenotypes. Resistance to ND18 correlates with an arginine residue at TGB1 position 390 (R-390) and a threonine at position 392 (T-392), whereas the virulent NW strain contains lysines (K) at both positions. ND18 TGB1 R390K ((ND)TGB1(R390K)) and (ND)TGB1(T392K) single substitutions, and an (ND)TGB1(R390K,T392K) double mutation resulted in systemic infections of Bd3-1. Reciprocal (ND)TGB1 substitutions into (NW)TGB1 ((NW)TGB1(K390R) and (NW)TGB1(K392T)) failed to affect virulence, implying that K-390 and K-392 compensate for each other. In contrast, an (NW)TGB1(K390R,K392T) double mutant exhibited limited vascular movement in Bd3-1, but developed prominent necrotic streaks that spread from secondary leaf veins. This phenotype, combined with the appearance of necrotic spots in certain ND18 mutants, and necrosis and rapid wilting of Bd3-1 plants after BJ strain ((BJ)TGB1(K390,T392)) inoculations, show that Bd3-1 Bsr1 resistance is elicited by the TGB1 protein and suggest that it involves a hypersensitive response

Parasite host range and the evolution of host resistance

Parasite host range plays a pivotal role in the evolution and ecology of hostsand the emergence of infectious disease. Although the factors that promotehost range and the epidemiological consequences of variation in host rangeare relatively well characterized, the effect of parasite host range on hostresistance evolution is less well understood. In this study, we tested theimpact of parasite host range on host resistance evolution. To do so, we usedthe host bacterium Pseudomonas fluorescens SBW25 and a diverse suite of coevolvedviral parasites (lytic bacteriophage Φ2) with variable host ranges(defined here as the number of host genotypes that can be infected) as ourexperimental model organisms. Our results show that resistance evolutionto coevolved phages occurred at a much lower rate than to ancestral phage(approximately 50% vs. 100%), but the host range of coevolved phages didnot influence the likelihood of resistance evolution. We also show that thehost range of both single parasites and populations of parasites does notaffect the breadth of the resulting resistance range in a na€ıve host but thathosts that evolve resistance to single parasites are more likely to resist other(genetically) more closely related parasites as a correlated response. Thesefindings have important implications for our understanding of resistanceevolution in natural populations of bacteria and viruses and other host–parasitecombinations with similar underlying infection genetics, as well as thedevelopment of phage therap

Dynamics of adaptation in experimental yeast populations exposed to gradual and abrupt change in heavy metal concentration

Directional environmental change is a ubiquitous phe-nomenon that may have profound effects on all living organisms. However, it is unclear how different rates of such change affect the dynamics and outcome of evolution. We studied this question using experimental evolution of heavy metal tolerance in the baker’s yeast Saccharomyces cerevisiae. To this end, we grew replicate lines of yeast for 500 generations in the presence of (1) a constant high concentration of cadmium, nickel, or zinc or (2) a gradually increas-ing concentration of these metals. We found that gradual environ-mental change leads to a delay in fitness increase compared with abrupt change but not necessarily to a different fitness of evolution-ary endpoints. For the nonessential metal cadmium, this delay is due to reduced fitness differences between genotypes at low metal con-centrations, consistent with directional selection to minimize intra-cellular concentrations of this metal. In contrast, for the essential metals nickel and zinc, different genotypes are selected at different concentrations, consistent with stabilizing selection to maintain con-stant intracellular concentrations of these metals. These findings in-dicate diverse fitness consequences of evolved tolerance mechanisms for essential and nonessential metals and imply that the rate of en-vironmental change and the nature of the stressor are crucial deter-minants of evolutionary dynamics

Glycemic Control in Type 2 Diabetes (Drug Treatments)

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Autocrine expression of the epidermal growth factor receptor ligand heparin-binding EGF-like growth factor in cervical cancer

Molecular tumour pathology - and tumour genetic

Landelijke Eerstelijns Samenwerkings Afspraak Diabetes mellitus type 2.

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Genomics of adaptation depends on the rate of environmental change in experimental yeast populations

The rate of directional environmental change may have profound consequences for evolutionary dynamics and outcomes. Yet, most evolution experiments impose a sudden large change in the environment, after which the environment is kept constant. We previously cultured replicate Saccharomyces cerevisiae populations for 500 generations in the presence of either gradually increasing or constant high concentrations of the heavy metals cadmium, nickel, and zinc. Here, we investigate how each of these treatments affected genomic evolution. Whole genome sequencing of evolved clones revealed that adaptation occurred via a combination of SNPs, small indels, and whole genome duplications and other large-scale structural changes. In contrast to some theoretical predictions, gradual and abrupt environmental change caused similar numbers of genomic changes. For cadmium, which is toxic already at comparatively low concentrations, mutations in the same genes were used for adaptation to both gradual and abrupt increase in concentration. Conversely, for nickel and zinc, which are toxic at high concentrations only, mutations in different genes were used for adaptation depending on the rate of change. Moreover, evolution was more repeatable following a sudden change in the environment, particularly for nickel and zinc. Our results show that the rate of environmental change and the nature of the selection pressure are important drivers of evolutionary dynamics and outcomes, which has implications for a better understanding of societal problems such as climate change and pollution

Genomics of adaptation depends on the rate of environmental change in experimental yeast populations

The rate of directional environmental change may have profound consequences for evolutionary dynamics and outcomes. Yet, most evolution experiments impose a sudden large change in the environment, after which the environment is kept constant. We previously cultured replicate Saccharomyces cerevisiae populations for 500 generations in the presence of either gradually increasing or constant high concentrations of the heavy metals cadmium, nickel, and zinc. Here, we investigate how each of these treatments affected genomic evolution. Whole genome sequencing of evolved clones revealed that adaptation occurred via a combination of SNPs, small indels, and whole genome duplications and other large-scale structural changes. In contrast to some theoretical predictions, gradual and abrupt environmental change caused similar numbers of genomic changes. For cadmium, which is toxic already at comparatively low concentrations, mutations in the same genes were used for adaptation to both gradual and abrupt increase in concentration. Conversely, for nickel and zinc, which are toxic at high concentrations only, mutations in different genes were used for adaptation depending on the rate of change. Moreover, evolution was more repeatable following a sudden change in the environment, particularly for nickel and zinc. Our results show that the rate of environmental change and the nature of the selection pressure are important drivers of evolutionary dynamics and outcomes, which has implications for a better understanding of societal problems such as climate change and pollution