Formation of mRNP granules in Toxoplasma gondii during the lytic cycle

Two poly(A) binding proteins (PABPs) of Toxoplasma gondii, were identified and characterized. They were named TgPABPC and TgPABPN as they were found to localize in the cytoplasm and nucleus respectively. TgPABPC, which colocalizes with mRNA granules, is therefore used as a cellular marker of mRNP granules. We detected that the formation of mRNP granules was independent of polymerized microtubules, and that the granules were distributed stochastically within the cytosol. Formation of mRNP granules was found to occur prior to parasite egress when a Ca²⁺ ionophore is used to induce egress. It was also found that maturation of mRNP granules could be described as a two-phase process. First, prior to host cell lysis, mRNP granules were formed rapidly within the cytosol. Second, the mRNP granule load was reduced within 10 min post egress. To investigate the link between translational state and mRNP granule formation, treatments with salubrinal, nutrient deprivation, and pH stress were used. While salubrinal induced granule formation in tachyzoites, nutrient starvation and pH stress showed no induction effect on mRNP granule formation. Interestingly, salubrinal treatment in bradyzoites did not induce RNP granule formation, thus suggesting that mRNP granule formation is not a ubiquitous response or directly related to translational repression. Instead, mRNP granule formation is likely a response to the rapid increase in non-translating RNA brought on by sudden changes in translational state.

Niche construction, social cognition, and language: hypothesizing the human as the production of place

New data is emerging from evolutionary anthropology and the neuroscience of social cognition on our species-specific hyper-cooperation (HC). This paper attempts an integration of third-person archaeological and second-person, neuroscientific perspectives on the structure of HC, through a post-Ricoeurian development in hermeneutical phenomenology. We argue for the relatively late evolution of advanced linguistic consciousness (ALC) (Hiscock in Biological Theory 9:27–41, 2014), as a reflexive system based on the ‘in-between’ or ‘cognitive system’ as reported by Vogeley et al. (in: Interdisziplinäre anthropologie, Heidelberg, Springer, 2014) of face-to-face social cognition, as well as tool use. The possibility of a positive or negative tension between the more recent ALC and the more ancient, pre-thematic, self-organizing ‘in-between’ frames an ‘internal’ niche construction. This indexes the internal structure of HC as ‘convergence’, where complex, engaged, social reasoning in ALC mirrors the cognitive structure of the pre-thematic ‘in-between’, extending the bio-energy of our social cognition, through reflexive amplification, in the production of ‘social place’ as ‘humanized space’. If individual word/phrase acquisition, in contextual actuality, is the distinctive feature of human language (Hurford in European Reviews 12:551–565, 2004), then human language is a hyperbolic, species-wide training in particularized co-location, developing consciousness of a shared world. The humanization of space and production of HC, through co-location, requires the ‘disarming’ of language as a medium of control, and a foregrounding of the materiality of the sign. The production of ‘hyper-place’ as solidarity beyond the face-to-face, typical of world religions, becomes possible where internal niche construction as convergence with the ‘in-between’ (world in us) combines with religious cosmologies reflecting an external ‘cosmic’ niche construction (world outside us).