The evolution of hermaphroditism by an infectious male-derived cell lineage : an inclusive-fitness analysis

This work was supported by funding from Balliol College, the Royal Society (A.G.), and the University of Groningen (L.R.).There has been much recent interest in the role for genetic conflicts to drive the evolution of genetic systems. Here we consider the evolution of hermaphroditism in the scale insect tribe Iceryini and the suggestion that this has been driven by conflict between a female and an infectious male tissue derived from her father. We perform an inclusive-fitness analysis to show that, owing to genetic relatedness between father and daughter, there is scope for collaboration as well as conflict over the establishment of the infectious tissue. We also consider the evolutionary interests of a maternally inherited bacterial symbiont that has been implicated in mediating the tissue's establishment. More generally, our analysis reveals that genetic conflicts can drive the evolution of hermaphroditism.Publisher PDFPeer reviewe

Self-Association of CaMKII-Delta in Low ATP/Low pH Conditions

poster abstractCalcium-Calmodulin Dependent Protein Kinase II (CaMKII), an enzyme critical for brain function and involved in learning and memory, becomes inactive and aggregates following ischemic insult such as seen with stroke or traumatic brain injury. The Hudmon Lab’s working model is that loss of CaMKII signaling exacerbates glutamate excitotoxicity, in turn inducing astrocytes to release neurotoxic levels of ATP, causing secondary cell death. CaMKII can autophosphorylate resulting in autonomous activity, and research by Hudmon Lab reveals that CaMKII will inactivate and self-associate when activating under low pH and low ATP conditions. CaMKII is coded by four genes, and for this study we focus on the alpha and delta isoforms. Alpha is found primarily in neurons and readily aggregates under conditions mimicking ischemic stress. However, delta is primarily expressed in astrocytes and its response to ischemic stress is uncharted territory. We ask how CaMKII delta self-associates under autophosphorylation conditions mimicking ischemic stress (low pH, low ATP) and how it differs from CaMKII alpha self-association. We use real-time light scattering and sedimentation assay to elucidate the time-course of delta aggregation as well as the kinase’s sensitivity to differing pH and ATP concentrations. Light scattering suggests that alpha and delta have a similar aggregation profile, but also that delta has reduced light scattering over time. Sedimentation analysis suggests delta truly does aggregate under these conditions and that it undergoes a molecular weight shift, indicative of autophosphorylation-induced inactivation. In future studies, we plan to investigate delta’s kinase activity under aggregation conditions, perform the same experiments detailed here on the gamma isoform, and investigate delta and gamma aggregation directly in astrocytes. If we can understand how all the isoforms of CaMKII aggregate, it may prove to be a novel research topic for therapies aimed at neuroprotection in victims of ischemic insults

Sexual antagonism in haplodiploids

Funding: Royal Society (Grant Number(s): DHF\R1\180120; Grant recipient(s): Laura Ross). Natural Environment Research Council (Grant Number(s): NE/K009524/1; Grant recipient(s): Andy Gardner). University of St Andrews (Grant Number(s): PhD studentship; Grant recipient(s): Thomas Hitchcock). H2020 European Research Council (Grant Number(s): 771387; Grant recipient(s): Andy Gardner).Females and males may face different selection pressures, such that alleles conferring a benefit in one sex may be deleterious in the other. Such sexual antagonism has received a great deal of theoretical and empirical attention, almost all of which has focused on diploids. However, a sizeable minority of animals display an alternative haplodiploid mode of inheritance, encompassing both arrhenotoky, whereby males develop from unfertilized eggs, and paternal genome elimination (PGE), whereby males receive but do not transmit a paternal genome. Alongside unusual genetics, haplodiploids often exhibit social ecologies that modulate the relative value of females and males. Here, we develop a series of evolutionary-genetic models of sexual antagonism for haplodiploids, incorporating details of their molecular biology and social ecology. We find that: (1) PGE promotes female-beneficial alleles more than arrhenotoky, and to an extent determined by the timing of elimination—and degree of silencing of—the paternal genome; (2) sib-mating relatively promotes female-beneficial alleles, as do other forms of inbreeding including limited male-dispersal, oedipal-mating, and the pseudo-hermaphroditism of Icerya purchasi; (3) resource competition between related females inhibits the invasion of female-beneficial alleles; and (4) sexual antagonism foments conflicts between parents and offspring, endosymbionts and hosts, and maternal- and paternal-origin genes.Publisher PDFPeer reviewe