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Copy number variation (CNV) of genes coding for certain enzymes has been shown to be responsible for adaptation of arthropods to anthropogenic toxins. Natural toxins produced by cyanobacteria in freshwater ecosystems, that is, protease inhibitors (Pls), have been demonstrated to increase in frequency over the last decades due to eutrophication and global warming. These Pls inhibit digestive proteases of Daphnia, the major herbivore of phytoplankton and cyanobacteria. The adjustment of isoforms, differences in gene expression, and activity of gut proteases determine tolerance to dietary Pls in single Daphnia genotypes. Here, we tested whether similar mechanisms are also responsible for differences in tolerance among Daphnia population. We developed a droplet digital PCR (ddPCR) method for the analysis of CNV of Daphnia proteases. We report that one Daphnia protease gene showed CNV between populations and that CNV correlates with chymotrypsin gene expression among populations. We showed that populations of Daphnia magna differ in tolerance to cyanobacterial Pls according to the cyanobacterial background of their lake of origin, which hints at local adaptation. The tolerance of the populations correlates with IC50 values of their chymotrypsins, which is probably due to a combined effect of CNV(translating into gene expression differences) and positive selection of tolerant protease isoforms. This is the first study using ddPCR to demonstrate CNV of a gene with ecologically relevant function, and the first report of differences in tolerance to cyanobacterial Pls among Daphnia populations in combination with the assessment of underlying molecular mechanisms.

The plant viral family Luteoviridae is divided into three genera: Luteovirus, Polerovirus and Enamovirus. Without assistance from another virus, members of the family are confined to the cells of the host plant’s vascular system. The first open reading frame (ORF) of poleroviruses and enamoviruses encodes P0 proteins which act as silencing suppressor proteins (VSRs) against the plant’s viral defense-mediating RNA silencing machinery. Luteoviruses, such as barley yellow dwarf virus-PAV (BYDV-PAV), however, have no P0 to carry out the VSR role, so we investigated whether other proteins or RNAs encoded by BYDV-PAV confer protection against the plant’s silencing machinery. Deep-sequencing of small RNAs from plants infected with BYDV-PAV revealed that the virus is subjected to RNA silencing in the phloem tissues and there was no evidence of protection afforded by a possible decoy effect of the highly abundant subgenomic RNA3. However, analysis of VSR activity among the BYDV-PAV ORFs revealed systemic silencing suppression by the P4 movement protein, and a similar, but weaker, activity by P6. The closely related BYDV-PAS P4, but not the polerovirus potato leafroll virus P4, also displayed systemic VSR activity. Both luteovirus and the polerovirus P4 proteins also showed transient, weak local silencing suppression. This suggests that systemic silencing suppression is the principal mechanism by which the luteoviruses BYDV-PAV and BYDV-PAS minimize the effects of the plant’s anti-viral defense. © 2017 by the authors.

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Genome Biology and Evolution 9 (2017): 659-676, doi:10.1093/gbe/evx023., Understanding and predicting the fate of populations in changing environments require knowledge about the mechanisms that support phenotypic plasticity and the adaptive value and evolutionary fate of genetic variation within populations. Atlantic killifish (Fundulus heteroclitus) exhibit extensive phenotypic plasticity that supports large population sizes in highly fluctuating estuarine environments. Populations have also evolved diverse local adaptations. To yield insights into the genomic variation that supports their adaptability, we sequenced a reference genome and 48 additional whole genomes from a wild population. Evolution of genes associated with cell cycle regulation and apoptosis is accelerated along the killifish lineage, which is likely tied to adaptations for life in highly variable estuarine environments. Genome-wide standing genetic variation, including nucleotide diversity and copy number variation, is extremely high. The highest diversity genes are those associated with immune function and olfaction, whereas genes under greatest evolutionary constraint are those associated with neurological, developmental, and cytoskeletal functions. Reduced genetic variation is detected for tight junction proteins, which in killifish regulate paracellular permeability that supports their extreme physiological flexibility. Low-diversity genes engage in more regulatory interactions than high-diversity genes, consistent with the influence of pleiotropic constraint on molecular evolution. High genetic variation is crucial for continued persistence of species given the pace of contemporary environmental change. Killifish populations harbor among the highest levels of nucleotide diversity yet reported for a vertebrate species, and thus may serve as a useful model system for studying evolutionary potential in variable and changing environments., This work was primarily supported by a grant from the National Science Foundation (collaborative research grants DEB-1265282, DEB-1120512, DEB-1120013, DEB-1120263, DEB-1120333, DEB-1120398 to J.K.C., D.L.C., M.E.H., S.I.K., M.F.O., J.R.S., W.W., and A.W.). Further support was provided by the National Institute of Environmental Health Sciences (1R01ES021934-01 to A.W., P42ES7373 to T.H.H., P42ES007381 to M.E.H., and R01ES019324 to J.R.S.), the National Institute of General Medical Sciences (P20GM103423 and P20GM104318 to B.L.K.), and the National Science Foundation (DBI-0640462 and XSEDE-MCB100147 to D.G.).

The problem addressed observed the lack of succession planning at two-year colleges in Georgia in identifying future leaders in higher education. Due to escalating impending retirements, resignation, and discharge, it is vital that succession plans are implemented within the college for promotions. Leadership succession planning has seldom been incorporated into community college’s strategic planning. The emphasis of this research study was to examine how leadership succession planning can be developed and implemented in the community college arena in Georgia. Challenged by increased enrollments, diminishing state funding, accountability for student success, and increased public oversight, this study intended to provide awareness into the leadership challenges facing community colleges. This study focused on the lived experiences of individuals and groups’ data collected by means of interviews and observation. With the use of existing literature on succession planning, higher education and other organizational settings are used to check the emerging patterns and recommendations for the necessary process, strategies, and methods required to establish a successful succession plan within the executive leadership at community colleges. Succession planning is nothing new as one great example is described in the Bible with the story of Moses and his successor Joshua. Moses became a mentor to Joshua and provided him the opportunity to complete various leadership tasks to further his development. The same principles of succession planning that were used in the transfer of leadership from Moses to Joshua are still applicable to today’s transitions in leadership.

This study investigated the combined use of the phonetic spelling code and an electronic spellchecker as a means by which secondary students with moderate spelling difficulties may write in a more decipherable manner, and spell more words accurately according to the conventional spelling code. Eighteen Year 7 secondary school students with moderate spelling difficulties were taught to use two simple phonetic spelling strategies in conjunction with an electronic phonetic dictionary, the Franklin TMQ 200, under three treatment conditions: whole class, small group and individual tuition. It was hypothesized that the individual treatment would be the most effective, followed by the small group, then whole class conditions. All but one student made gains in correct spelling on the South Australian Spelling Test (Range 1–9), although there were no differences between the instructional conditions and no significant gains in understandable (phonetically regular) attempts to spell, pre‐test to post‐test. It is a significant finding in its own right that many students had mastered and were applying the phonetic code, when the correct spelling of a word was not immediately accessible to them. The potential value of the program for students with severe remedial spelling needs, as well as those with moderate needs, is also discussed.