The genetic architecture underlying prey-dependent performance in a microbial predator

Natural selection should favour generalist predators that outperform specialists across all prey types. Two genetic solutions could explain why intraspecific variation in predatory performance is, nonetheless, widespread: mutations beneficial on one prey type are costly on another (antagonistic pleiotropy), or mutational effects are prey-specific, which weakens selection, allowing variation to persist (relaxed selection). To understand the relative importance of these alternatives, we characterised natural variation in predatory performance in the microbial predator Dictyostelium discoideum. We found widespread nontransitive differences among strains in predatory success across different bacterial prey, which can facilitate stain coexistence in multi-prey environments. To understand the genetic basis, we developed methods for high throughput experimental evolution on different prey (REMI-seq). Most mutations (~77%) had prey-specific effects, with very few (~4%) showing antagonistic pleiotropy. This highlights the potential for prey-specific effects to dilute selection, which would inhibit the purging of variation and prevent the emergence of an optimal generalist predator.

A simple bypass assay for DNA polymerases shows hypermutating variants associated with cancer show mechanistic differences in vitro

Errors made by DNA polymerases contribute to both natural variation and, in extreme cases, to genome instability and its associated diseases. Recently the importance of polymerase misincorporation in disease has been highlighted by the identification of cancer-associated polymerase variants and the recognition that a subgroup of these variants have a hypermutation phenotype in tumours. We have developed a bypass assay to rapidly determine the tendency of a polymerase to misincorporate in vitro. We have used the assay to compare misincorporation by wild-type, exonuclease defective and two hypermutating DNA polymerase e variants, P286R and V411L. The assay clearly distinguished between the misincorporation rates of wild type, exonuclease dead and P286R polymerases. However, the V411L polymerase showed different misincorporation characteristics to P286R, suggesting that these variants cause hypermutation by different mechanisms. Using this assay misincorporation opposite a templated C nucleotide was consistently higher than for other nucleotides, and this caused predominantly C to T transitions. This is consistent with the observation that C to T transitions are commonly seen in POLE mutant tumours.

Population differences and domestication effects on mating and remating frequencies in Queensland fruit fly

Females of many insect species are unreceptive to remating for a period following their first mating. This inhibitory effect may be mediated by either the female or her first mate, or both, and often reflects the complex interplay of reproductive strategies between the sexes. Natural variation in remating inhibition and how this phenotype responds to captive breeding are largely unexplored in insects, including many pest species. We investigated genetic variation in remating propensity in the Queensland fruit fly, Bactrocera tryoni, using strains differing in source locality and degree of domestication. We found up to threefold inherited variation between strains from different localities in the level of intra-strain remating inhibition. The level of inhibition also declined significantly during domestication, which implied the existence of genetic variation for this trait within the starting populations as well. Inter-strain mating and remating trials showed that the strain differences were mainly due to the genotypes of the female and, to a lesser extent, the second male, with little effect of the initial male genotype. Implications for our understanding of fruit fly reproductive biology and population genetics and the design of Sterile Insect Technique pest management programs are discussed.

Validation of Signed Language Assessments for Adult L2 Learners

This chapter focuses on the validity of tests of second language (L2) signed language learners. Test validity depends on how test developers take the language as well as the modality into consideration and how the test captures natural variation in local signed languages, which impacts the use of tests and interpretation of results. In this chapter, the argument-based approach to validation is used to evaluate claims that test developers make about the uses of tests. A sample of signed language tests for L2 learners is reviewed and discussed. Caution in the extrapolation and making decisions based on test results are discussed. The chapter ends with suggestions about how to evaluate the validity of future L2 signed language tests.

Influence of genetic and environmental factors on the contents of carotenoids and phenolic acids in red pepper fruits (Capsicum annuum L.)

Red pepper is enriched in antioxidant components, such as carotenoids, phenolic compounds, and vitamins. In this study, we investigated the natural variability in the content of carotenoids and phenolic acids in 11 red pepper cultivars grown in two locations in South Korea during 2016, 2017, and 2018. Seven carotenoids and six phenolic acids, including soluble and insoluble forms, were detected in the red fruit pericarps. The major carotenoids were β-carotene (40%) and capsanthin (20%). The content of insoluble phenolic acids was higher than that of soluble phenolic acids because of the large amount of insoluble p-coumaric acid. The statistical analysis of combined data showed significant differences among varieties, locations, and years for most of the measured components. The results from variance component analysis indicated that the effects of location, year and the interaction of location and year mainly accounted for the variation in carotenoids, whereas variations in phenolic acid content were attributed to year and variety. In addition, the results of principal component analysis and orthogonal partial least-squares discriminant showed that carotenoids were well discriminated by location and year, whereas phenolic acids were distinctively separated only by year. The data from this study could explain the natural variation in the content of carotenoids and phenolic acids in red pepper fruits by genotype and environment.

Using drone technology for preserving the economic sustainability of the agricultural holdings

In the present era, precision agriculture, through the set of innovative technologies that it uses, allows to effectively manage the terrain, machinery, and input acquisition, considering the specific natural variation of the environmental conditions. One of such innovations is the unmanned aerial vehicle (drone) technology which has gained popularity and has been widely used in adopting efficient strategies for preserving the economic sustainability of the agricultural holdings. The need for an efficient management, the complex climatic, technological, economic, and biological changes that have recently occurred at the level of agro-systems impose a continuous and accurate knowledge of the growing production resources and the vegetation state in cultures. In this context, the article investigates a series of particularities regarding the use of geospatial and informational technology in the process of taking, storing, analysing, and interpreting them to optimize inputs, considering the state of the crops and the degree of soil supply in each relatively homogeneous area of the terrain..