Mutational analysis of differences in thermostability between histones from mesophilic and hyperthermophilic archaea

Amino acid residues responsible for the large difference in thermostability between HMfB and HFoB, archaeal histones from the hyperthermophile Methanothermus fervidus and the mesophile Methanobacterium formicicum, respectively, have been identified by site-specific mutagenesis. The thermal denaturation of approximately 70 archaeal histone variants has been monitored by circular dichroism, and the data generated were fit to a two-state unfolding model (dimer-->two random coil monomers) to obtain a standard-state (1M) melting temperature for each variant dimer. The results of single-, double-, and triple-residue substitutions reveal that the much higher stability of rHMfB dimers, relative to rHFoB dimers, is conferred predominantly by improved intermolecular hydrophobic interactions near the center of the histone dimer core and by additional favorable ion pairs on the dimer surface.     

The EEG Consistency Index as a Measure of ADHD and Responsiveness to Medication

The primary diagnostic procedure for Attention-Deficit/Hyperactivity Disorder (ADHD) is the clinical interview, because psychological, neuropsychological, and neurological tests to date have not had sufficient specificity. Currently, there is no objective means to measure severity of ADHD, or the extent to which it is benefited by various dosages of medication. We recently reported that a certain EEG profile, the Consistency Index, occurring during the transition between two easy cognitive tasks clearly differentiated ADHD from non-ADHD boys between the ages of 8 and 12. The current study replicated this with older males (19–25) using different tasks, and a double blind, placebo versus Ritalin® controlled crossover design. Seven ADHD subjects were found to have a significantly lower Consistency Index than 6 non-ADHD males while transitioning from 2 Simple tasks during placebo condition, while only the ADHD subjects demonstrated a significant improvement in their Consistency Index while on Ritalin®. Similar but nonsignificant trends were observed while transitioning across Hard tasks.     

Fetal rabbit pulmonary artery smooth muscle cell response to ryanodine is developmentally regulated

To study developmental changes in intracellular calcium handling in pulmonary artery smooth muscle cells (PASMCs), cells were isolated from distal and proximal pulmonary arteries from rabbits at different developmental stages: juvenile (4-6 wk old), newborn (<48 h), and full-term fetal. Isolated PASMCs were studied using the calcium-sensitive dye fura 2. Cells from each age group responded to caffeine with an increase in calcium; however, ryanodine (50 microM) only increased calcium in fetal distal PASMCs. The ryanodine-induced increase was due to influx of extracellular calcium because it was blocked by removal of extracellular calcium or by diltiazem. The calcium-sensitive potassium (K(Ca)) channel blocker iberiotoxin produced a transient increase in calcium in the fetal distal PASMCs, which could be inhibited by prior application of ryanodine. Conversely, the ryanodine response was inhibited if iberiotoxin was given first. With the use of electrophysiology and confocal microscopy, fetal PASMCs were shown to exhibit spontaneous transient outward currents and calcium sparks, respectively. These observations suggest that ryanodine-sensitive release of calcium from the sarcoplasmic reticulum and K(Ca) channels act together to control intracellular calcium only in fetal distal PASMCs.     

Histones and nucleosomes in Archaea and Eukarya: a comparative analysis

Archaeal histones from mesophilic, thermophilic, and hyperthermophilic members of the Euryarchaeota have primary sequences, the histone fold, tertiary structures, and dimer formation in common with the eukaryal nucleosome core histones H2A, H2B, H3, and H4. Archaeal histones form nucleoprotein complexes in vitro and in vivo, designated archaeal nucleosomes, that contain histone tetramers and protect approximately 60 base pairs of DNA from nuclease digestion. Based on the sequence and structural homologies and experimental data reviewed here, archaeal nucleosomes appear similar, and may be homologous in evolutionary terms and function, to the structure at the center of the eukaryal nucleosome formed by the histone (H3+H4)₂ tetramer. Received: January 22, 1998 / Accepted: February 16, 1998     

Results of 12 years' treatment of chronic renal failure by dialysis and transplantation.

The survival of 305 patients with chronic renal failure treated at the Vancouver General Hospital by centre and home peritoneal dialysis, centre and home hemodialysis and cadaver renal transplantation over a 12-year period was analysed. There was decreasing survival with age except in patients undergoing home dialysis. Hypertension and analgesic nephropathy as primary causes of renal disease were associated with a poor prognosis. Hence age and diagnosis appear to be two of the main determinants of survival. Cardiovascular disease was the commonest cause of death but seven deaths were due to dialysis dementia. The results compare favourably with other published statistics.     

Effect of temperature on seed production in the invasive grass Glyceria maxima (Hartm.) Holmb. (Poaceae) in South Africa

Temperature is one of the main factors that determine sexual reproduction in terrestrial and emergent aquatic plant species. The effect of temperature on sexual reproduction and seed production of Glyceria maxima (Hartm.) Holmb. in the southern hemisphere is unknown. Glyceria maxima collections in February 2010 at three isolated infestations in KwaZulu-Natal failed to yield a single seed, only empty panicles. Laboratory experiments showed that vernalisation had no consistent effect on seed production. Field- and laboratory-grown plants produced seeds in the 2010/2011 season, because of having sufficient time at optimum temperatures required for seed production (1 491 and 1 585 hours, respectively), compared to a shorter period (1 352 hours) of suitable temperatures during the 2009/2010 growing season. An inadequate period of optimum temperatures (15–25°C) during seed production resulted in the lack of seeds in the field in the 2009/2010 growing season. This study showed that temperature and duration of exposure thereto during the seed-production period play vital roles in G. maxima sexual reproduction.     

Relative bioactivities of cholecystokinins-8 and -33 on rat pancreatic acini

The relative potencies of cholecystokinin (CCK-33) and its carboxyl terminal octapeptide (CCK-8) for stimulation of amylase release from rat pancreatic acini was measured. Porcine CCK-33 and synthetic CCK-8 were initially subjected to high pressure liquid chromatography to assess purity. Concentrations of each peptide were determined by amino acid analysis. The relative immunoreactivities of CCK-33 and CCK-8 were compared using an antibody that recognizes the common carboxyl terminus of these forms. This antibody bound CCK-8 and CCK-33 with nearly equal affinity. The relative potencies of CCK-33 and CCK-8 were then measured by comparing their abilities to stimulate amylase release from isolated rat pancreatic acini. Statistical analysis of the relative potencies of the two hormones indicated that CCK-8 was 36% more potent than CCK-33 in this assay system. These data suggest that differences in biological activities between large and small forms of CCK are not as great as previously reported.     

Complete genome sequence of Rhizobium leguminosarum bv. trifolii strain WSM1325, an effective microsymbiont of annual Mediterranean clovers

Rhizobium leguminosarum bv trifolii is a soil-inhabiting bacterium that has the capacity to be an effective nitrogen fixing microsymbiont of a diverse range of annual Trifolium (clover) species. Strain WSM1325 is an aerobic, motile, non-spore forming, Gram-negative rod isolated from root nodules collected in 1993 from the Greek Island of Serifos. WSM1325 is produced commercially in Australia as an inoculant for a broad range of annual clovers of Mediterranean origin due to its superior attributes of saprophytic competence, nitrogen fixation and acid-tolerance. Here we describe the basic features of this organism, together with the complete genome sequence, and annotation. This is the first completed genome sequence for a microsymbiont of annual clovers. We reveal that its genome size is 7,418,122 bp encoding 7,232 protein-coding genes and 61 RNA-only encoding genes. This multipartite genome contains 6 distinct replicons; a chromosome of size 4,767,043 bp and 5 plasmids of size 828,924 bp, 660,973 bp, 516,088 bp, 350,312 bp and 294,782 bp.