Palaeoecology of a billion-year-old non-marine cyanobacterium from the Torridon Group and Nonesuch Formation

A new chroococcalean cyanobacterium is described from approximately 1-billion-year-old non-marine deposits of the Torridonian Group of Scotland and the Nonesuch Formation of Michigan, USA. Individual cells of the new microfossil, Eohalothece lacustrina gen. et sp. nov., are associated with benthic microbial biofilms, but the majority of samples are recovered in palynological preparations in the form of large, apparently planktonic colonies, similar to extant species of Microcystis. In the Torridonian, Eohalothece is associated with phosphatic nodules, and we have developed a novel hypothesis linking Eohalothece to phosphate deposition in ancient freshwater settings. Extant cyanobacteria can be prolific producers of extracellular microcystins, which are non-ribosomal polypeptide phosphatase inhibitors. Microcystins may have promoted the retention and concentration of sedimentary organic phosphate prior to mineralization of francolite and nodule formation. This has a further implication that the Torridonian lakes were nitrogen limited as the release of microcystins is enhanced under such conditions today. The abundance and wide distribution of Eohalothece lacustrina attests to the importance of cyanobacteria as oxygen-producing photoautotrophs in lacustrine ecosystems at the time of the Mesoproterozoic–Neoproterozoic transition

Pellicle ultrastructure demonstrates that Moyeria is a fossil euglenid

An earlier proposal of euglenid affinity for the acritarch Moyeria was based primarily on the pattern of bi-helical striate ornamentation as seen in scanning electron microscopy and light microscopy. Examination of specimens using transmission electron microscopy reveals that the ‘striae’ are actually integral components of the microfossil wall itself, corresponding to the pellicle strips of some euglenid species today. A Silurian specimen from Scotland preserves an articulated wall composed of thickened arches and thinner U-shaped interconnecting segments paralleling that seen in some modern photosynthetic euglenids. A second specimen from the Moyeria holotype section (Silurian of New York State) shows fused articulation, again compatible with some extant euglenids. This evidence is sufficient to transfer Moyeria out of the Incertae sedis group, Acritarcha, and into the Euglenida. This proposal helps establish the morphological basis for the recognition of euglenid microfossils and ultimately provides evidence of a lengthy fossil record of the eukaryotic supergroup Excavata

Lateralization of emotional expression under a neuroleptic drug

Sixteen student volunteers were administered placebo and 50 mg of chlorpromazine (CPZ) in tablet form, on separate occasions, two hours before testing. Whilst volunteers related pleasant and unpleasant personal life events, the frequency and intensity of expressions on the left and right sides of the face were rated by independent observers. Subsequently the valence of the narration was also rated. Similar to a previous study facial expressions during negative emotions were expressed more often and intensely in the left face but positive emotions were bilaterally represented. CPZ neutralised the emotion on both sides of the face, irrespective of whether it was positive or negative. However, because negative emotions were almost completely lateralised to the left face the drug's effect on this emotion was most pronounced on this side. Independent ratings of the narration of the life events showed CPZ made them more pleasant. It is suggested that emotional arousal increases the asymmetry of behaviours when these are unilaterally represented or controlled. CPZ may equalize the symmetry of behaviour by reducing emotional arousal rather than by blocking all behaviour