1.1-billion-year-old porphyrins establish a marine ecosystem dominated by bacterial primary producers.

The average cell size of marine phytoplankton is critical for the flow of energy and nutrients from the base of the food web to higher trophic levels. Thus, the evolutionary succession of primary producers through Earth's history is important for our understanding of the radiation of modern protists ∼800 million years ago and the emergence of eumetazoan animals ∼200 million years later. Currently, it is difficult to establish connections between primary production and the proliferation of large and complex organisms because the mid-Proterozoic (∼1,800-800 million years ago) rock record is nearly devoid of recognizable phytoplankton fossils. We report the discovery of intact porphyrins, the molecular fossils of chlorophylls, from 1,100-million-year-old marine black shales of the Taoudeni Basin (Mauritania), 600 million years older than previous findings. The porphyrin nitrogen isotopes (δ15Npor = 5.6-10.2‰) are heavier than in younger sedimentary sequences, and the isotopic offset between sedimentary bulk nitrogen and porphyrins (εpor = -5.1 to -0.5‰) points to cyanobacteria as dominant primary producers. Based on fossil carotenoids, anoxygenic green (Chlorobiacea) and purple sulfur bacteria (Chromatiaceae) also contributed to photosynthate. The low εpor values, in combination with a lack of diagnostic eukaryotic steranes in the time interval of 1,600-1,000 million years ago, demonstrate that algae played an insignificant role in mid-Proterozoic oceans. The paucity of algae and the small cell size of bacterial phytoplankton may have curtailed the flow of energy to higher trophic levels, potentially contributing to a diminished evolutionary pace toward complex eukaryotic ecosystems and large and active organisms.

PLANET TOPERS: Planets, Tracing the Transfer, Origin, Preservation, and Evolution of their ReservoirS.

The Interuniversity Attraction Pole (IAP) 'PLANET TOPERS' (Planets: Tracing the Transfer, Origin, Preservation, and Evolution of their Reservoirs) addresses the fundamental understanding of the thermal and compositional evolution of the different reservoirs of planetary bodies (core, mantle, crust, atmosphere, hydrosphere, cryosphere, and space) considering interactions and feedback mechanisms. Here we present the first results after 2 years of project work.

[Nontuberculous mycobacterial epitrochlear adenitis]. / Adénite épitrochléenne à mycobactérie non tuberculeuse.

We report the case of a 2-year-old girl referred for unilateral epitrochlear lymphadenitis caused by Mycobacterium avium. Adenitis is the most frequent presentation of non tuberculous mycobacteria in children. Typical locations are the cervical, submandibular, axillar, inguinal, mediastinal, and parotid regions. To our knowledge, this is the first observation of an epitrochlear location. The diagnosis was made by evidencing the causal bacterium but also by the exclusion of other causes such as Bartonella henselae and Mycobacterium tuberculosis infections. Treatment is based on surgical excision, which provides a cure rate of 90%. Macrolides are reserved for extended lesions and/or relapsing lesions despite surgical management.

Functional MRI of the cervical spinal cord on 1.5 T with fingertapping: to what extent is it feasible?

INTRODUCTION: Until recently, functional magnetic resonance imaging (fMRI) with blood oxygen level-dependent (BOLD) contrast, was mainly used to study brain physiology. The activation signal measured with fMRI is based upon the changes in the concentration of deoxyhaemoglobin that arise from an increase in blood flow in the vicinity of neuronal firing. Technical limitations have impeded such research in the human cervical spinal cord. The purpose of this investigation was to determine whether a reliable fMRI signal can be elicited from the cervical spinal cord during fingertapping, a complex motor activity. Furthermore, we wanted to determine whether the fMRI signal could be spatially localized to the particular neuroanatomical location specific for this task. METHODS: A group of 12 right-handed healthy volunteers performed the complex motor task of fingertapping with their right hand. T2*-weighted gradient-echo echo-planar imaging on a 1.5-T clinical unit was used to image the cervical spinal cord. Motion correction was applied. Cord activation was measured in the transverse imaging plane, between the spinal cord levels C5 and T1. RESULTS: In all subjects spinal cord responses were found, and in most of them on the left and the right side. The distribution of the activation response showed important variations between the subjects. While regions of activation were distributed throughout the spinal cord, concentrated activity was found at the anatomical location of expected motor innervation, namely nerve root C8, in 6 of the 12 subjects. CONCLUSION: fMRI of the human cervical spinal cord on an 1.5-T unit detects neuronal activity related to a complex motor task. The location of the neuronal activation (spinal cord segment C5 through T1 with a peak on C8) corresponds to the craniocaudal anatomical location of the neurons that activate the muscles in use.

5,5-Bis(3-hydroxyphenyl)hydantoin, a minor metabolite of diphenylhydantoin (dilantin) in the rat and human.

5,5-Bis(4-hydroxyphenyl) hydantoin has been identified as a minor metabolite of diphenylhydantoin (DPH) in the rat and human. This metabolite was synthesized in the laboratory from 4,4'-dihydroxybenzophenone. Gas chromatographic and mass spectrometric comparison of the permethylated synthetic compound with the permethylated derivative of the metabolite obtained from biological sources showed that they were identical. The metabolite was excreted as a glucuronide and accounted for about 1% of the total hydroxylated metabolites of DPH in human urine and rat bile. When the synthetic standard was added to the recirculating perfusate of the isolated perfused rat liver, a monoglucuronide, a trihydroxy-DPH glucuronide, and a dihydroxymethoxy-DPH glucuronide were identified in the bile.