Cyanide-resistant electron transport in sporulating Bacillus megaterium KM.

The NADH oxidase activity of stage V mother-cell membranes, isolated from sporulating Bacillus megaterium KM, shows a greater inhibition by cyanide and displays this response at lower concentrations of cyanide than the stage V forespore inner membrane. Comparison of the effects of various respiratory inhibitors reveals that the difference in cyanide sensitivity between these membranes is located on the oxidase side of the 2-heptyl-4-hydroxyquinoline N-oxide-sensitive step. Both membranes contain cytochromes a+a3, b-562, b-555, c and d, with three potential oxidases: cytochromes a+a3, o and d. Cyanide difference spectra suggest that cytochromes b-562 and d may be the components involved in the cyanide-resistant electron transport pathway. Membrane ascorbate-N,N,N',N'-tetramethylphenylenediamine and ascorbate 2,6-dichlorophenolindophenol oxidase activities are highly sensitive to cyanide. Evidence is presented for terminal branching of the respiratory chain with branches differing in cyanide sensitivity. The cyanide sensitivity of the NADH oxidase of membranes prepared from various stages of sporulation is compared. Morphogenesis of the mother-cell plasma membrane to a cyanide-sensitive form during stages II and III of sporulation is postulated.     

Comparison of Bacillus thuringiensis subsp. israelensis CryIVA and CryIVB cloned toxins reveals synergism in vivo

When the gene for the mosquitocidal protein CryIVA was expressed in two strains of Bacillus thuringiensis (Bt) cured of their resident delta-endotoxin genes, the protein accumulated as large inclusions. The inclusions produced in the Bt subsp. kurstaki recipient strain were twice as soluble at alkaline pH as the inclusions produced in Bt subsp. israelensis. Solubilized protoxins were activated by treatment with mosquito gut extracts or trypsin for varying lengths of time and tested for in vitro cytotoxicity on cell lines of three genera of mosquito. CryIVA treated with any of the mosquito gut extracts for 6 h showed significant toxicity against Anopheles gambiae cells and slight activity on Culex quinquefasciatus cells. For CryIVB, the only significant cytotoxicity observed was against Aedes aegypti cells after treatment with Aedes gut extract. In in vivo bioassays, both CryIVA, purified from either of the Bt recipient strains, and CryIVB inclusions were similarly toxic to A. aegypti and A. gambiae larvae but CryIVA was 25-fold more toxic to C. quinquefasciatus. Synergism in vivo between the two toxins was revealed when results from assaying single toxins and mixtures were compared. Mixtures of CryIVA and CryIVB proved to be 5-fold more toxic to Culex than either toxin used singly and showed a reduced but similar synergism when tested against Aedes and Anopheles larvae. The synergism was not duplicated in vitro using cell lines from these three insects.     

Zinc release and the sequence of biochemical events during triggering of Bacillus megaterium KM spore germination.

Zinc release is the first quantitatively significant event detected during the triggering of Bacillus megaterium KM spore germination. Of the total spore Zn2+ pool 25% is released from non-heat-activated spores within 4 min of triggering germination. During this period only 10% of the spore population becomes irreversibly committed to germinate. The investigation of a putative role for Zn2+ in the germination trigger mechanism has established a relationship between the rate and extent of Zn2+ release and the stimulation of spore germination by heat activation. Furthermore, a correlation can be demonstrated between the extent of zinc release from spore populations and the time required to obtain 50% commitment of these populations to germinate over a wide temperature range. These findings have been used to expand a recently published model for the triggering of bacterial spore germination.     

The Emerging Role of Copeptin

Direct measurement of the nonapeptide vasopressin has been limited by analyte instability ex vivo and in vivo rapid degradation, low serum concentrations requiring a sensitive assay and inherent secretory pulsatility. Copeptin is a 39 amino acid glycopeptide cleavage product of vasopressin synthesis with high stability, providing a marker of vasopressin secretion. Copeptin measurement has applications in diagnosis of diabetes insipidus and other diseases with altered vasopressin secretion. This review summarises our current understanding of serum copeptin measurement in diabetes insipidus and possible future applications of copeptin assays. As vasopressin is a stress hormone, there is emerging evidence on the use of copeptin for diagnosis and prognostication of disorders such as syndrome of inappropriate anti-diuretic hormone secretion, diabetes mellitus, critical illness, stroke, cardiovascular disease, respiratory disease, renal disease and thermal stress. Copeptin concentration measurement is likely to improve the diagnostic reliability of diabetes insipidus and, as a marker of stress, may have diagnostic or prognostic utility in specific clinical circumstances. Further studies are needed to determine if goal-directed therapy using plasma copeptin concentrations may improve patient outcomes.     

ANTHROPOMETRIC DETERMINANTS OF ROWING ERGOMETER PERFORMANCE IN PHYSICALLY INACTIVE COLLEGIATE FEMALES

The aim of the study was to evaluate anthropometric characteristics as determinants of 500 m rowing ergometer performance in physically inactive collegiate females. In this cross-sectional study, which included 196 collegiate females aged 19-23 years not participating in regular physical activities, body mass (BM), body height (BH), length of upper limbs (LA), length of lower limbs (LL), body mass index (BMI), slenderness index (SI), and the Choszcz-Podstawski index (CPI) were measured and a stepwise multiple regression analysis was performed. Participants performed 500 m maximal effort on a Concept II rowing ergometer. BM, BH, LA, LL, and the BMI, SI and CPI indices were found to be statistically significant determinants of 500 m performance. The best results (T) were achieved by females whose BH ranged from 170 to 180 cm, with LA and LL ranging from 75 to 80 cm and 85 to 90 cm, respectively. The best fitting statistical model was identified as: T = 11.6793 L_R – 0.1130 L_R² – 0.0589 L_N² + 29.2157 CPI² + 0.1370 LR·LN - 2.6926 LR·CPI – 211.7796. This study supports a need for additional studies focusing on understanding the importance of anthropometric differences in rowing ergometer performance, which could lead to establishing a better quality reference for evaluation of cardiorespiratory fitness tested using a rowing ergometer in collegiate females.