Midsummer heat wave effects on lacustrine plankton: Variation of assemblage structure and fatty acid composition

The effects of the 2003 European heat wave on a freshwater plankton assemblage and its fatty acid (FA) composition were investigated. Composition and FA profiles of four size categories of planktonic organisms collected in 2003 were compared to those of the colder year 2002.     

Cluster analysis of behavioural and event-related potentials during a contingent negative variation paradigm in remitting-relapsing and benign forms of multiple sclerosis

Background  

Event-related potentials (ERPs) may be used as a highly sensitive way of detecting subtle degrees of cognitive dysfunction. On the other hand, impairment of cognitive skills is increasingly recognised as a hallmark of patients suffering from multiple sclerosis (MS). We sought to determine the psychophysiological pattern of information processing among MS patients with the relapsing-remitting form of the disease and low physical disability considered as two subtypes: 'typical relapsing-remitting' (RRMS) and 'benign MS' (BMS). Furthermore, we subjected our data to a cluster analysis to determine whether MS patients and healthy controls could be differentiated in terms of their psychophysiological profile.     

Centrifugation of 2-cell mouse ova: cytoplasm stratification and recovery

Summary Two-cell mouse ova, which were centrifuged for l h at 70 000–90 000xg, showed a precise stratification of the cytoplasm and an elongation of the nucleus. The ova were fixed at different times and observed by light and electron microscopy using cytochemical methods and detergent extractions. Within 40 min after centrifugation the normal-looking morphology was recovered except for the persisting lipid caps at the centripetal poles of the blastomeres. Cleavage, compaction and blastulation were not prevented by centrifugation. Treatments with colcemid or cytochalasin D delayed but did not impair recovery. These results suggest that a resilient cytoskeletal structure may be involved in this kind of embryonic regulation.     

Benzodiazepines in the brain

Great progress has been made in the last 5 yr in demonstrating the presence of benzodiazepines (BDZs) in mammalian tissues, in beginning studies on the origin of these natural compounds, and in elucidating their possible biological roles. Many unanswered questions remain regarding the sources and biosynthetic pathways responsible for the presence of BDZs in brain and their different physiological and/or biochemical actions. This essay will focus on recent findings supporting that: (1) BDZs are of natural origin; (2) mammalian brain contains BDZs in concentrations ranging between 5.10⁻¹⁰–10⁻⁸ M; (3) dietary source of BDZs might be a plausible explanation for their occurrence in animal tissues, including man; (4) the formation of BDZ-like molecules in brain is a possibility, experimentally supported; (5) BDZ-like molecules including diazepam andN-desmethyldiazepam are elevated in hepatic encephalopathy; and (6) natural BDZs in the brain are involved in the modulation of memory processes. Future studies using the full range of biochemical, physiological, behavioral, and molecular biological techniques available to the neuroscientist will hopefully continue to yield exciting and new information concerning the biological roles that BDZs might play in the normal and pathological functioning of the brain.