A voltage-gated H+ channel underlying pH homeostasis in calcifying coccolithophores.

Marine coccolithophorid phytoplankton are major producers of biogenic calcite, playing a significant role in the global carbon cycle. Predicting the impacts of ocean acidification on coccolithophore calcification has received much recent attention and requires improved knowledge of cellular calcification mechanisms. Uniquely amongst calcifying organisms, coccolithophores produce calcified scales (coccoliths) in an intracellular compartment and secrete them to the cell surface, requiring large transcellular ionic fluxes to support calcification. In particular, intracellular calcite precipitation using HCO3⁻ as the substrate generates equimolar quantities of H+ that must be rapidly removed to prevent cytoplasmic acidification. We have used electrophysiological approaches to identify a plasma membrane voltage-gated H+ conductance in Coccolithus pelagicus ssp braarudii with remarkably similar biophysical and functional properties to those found in metazoans. We show that both C. pelagicus and Emiliania huxleyi possess homologues of metazoan H(v)1 H+ channels, which function as voltage-gated H+ channels when expressed in heterologous systems. Homologues of the coccolithophore H+ channels were also identified in a diversity of eukaryotes, suggesting a wide range of cellular roles for the H(v)1 class of proteins. Using single cell imaging, we demonstrate that the coccolithophore H+ conductance mediates rapid H+ efflux and plays an important role in pH homeostasis in calcifying cells. The results demonstrate a novel cellular role for voltage gated H+ channels and provide mechanistic insight into biomineralisation by establishing a direct link between pH homeostasis and calcification. As the coccolithophore H+ conductance is dependent on the trans-membrane H+ electrochemical gradient, this mechanism will be directly impacted by, and may underlie adaptation to, ocean acidification. The presence of this H+ efflux pathway suggests that there is no obligate use of H+ derived from calcification for intracellular CO2 generation. Furthermore, the presence of H(v)1 class ion channels in a wide range of extant eukaryote groups indicates they evolved in an early common ancestor.

"I Spent Most of Freshers in my Room"-A Qualitative Study of the Social Experiences of University Students on the Autistic Spectrum.

Autistic university students face extra challenges in both their academic and social life. Barriers to socialising appear to be less well understood and supported by universities than academic requirements. Semi-structured interviews were conducted with ten autistic university students to explore their social experiences. Questions explored their social experiences, satisfaction with social life, disclosure of ASD to others, and the impact of mental wellbeing on university life. Thematic analysis indicated most participants were unsatisfied with their social lives and experienced mental health issues. Factors exacerbating social isolation included lack of suitable social events, lack of social support and feeling unable to disclose to peers. Factors which reduced social isolation included joining an autism or special interest society and receiving social mentoring.

Guidance should end mystery of learning difficulties.

The recently launched RCN guidance on dyslexia, dyspraxia and dyscalculia (news August 18) provides managers with concise explanations and information on making practical accommodation in the workplace for staff with specific learning difficulties (SpLDs).

Iron blocks the accumulation and activity of tetracyclines in bacteria.

The apparent sensitivities of several bacterial pathogens to tetracyclines varied by up to 128-fold with the medium content of Fe, but not of other metals. The effect of Fe was independent of superoxide dismutase activity and of intracellular Fe, but accumulation of tetracyclines was blocked in high-Fe medium. Thus, synergistic suppression of bacterial growth in the presence of a low Fe concentration and tetracyclines arises because of elevated antibiotic accumulation.