Role of mitochondria in the pheromone- and amiodarone-induced programmed death of yeast

Although programmed cell death (PCD) is extensively studied in multicellular organisms, in recent years it has been shown that a unicellular organism, yeast Saccharomyces cerevisiae, also possesses death program(s). In particular, we have found that a high doses of yeast pheromone is a natural stimulus inducing PCD. Here, we show that the death cascades triggered by pheromone and by a drug amiodarone are very similar. We focused on the role of mitochondria during the pheromone/amiodarone-induced PCD. For the first time, a functional chain of the mitochondria-related events required for a particular case of yeast PCD has been revealed: an enhancement of mitochondrial respiration and of its energy coupling, a strong increase of mitochondrial membrane potential, both events triggered by the rise of cytoplasmic [Ca2+], a burst in generation of reactive oxygen species in center o of the respiratory chain complex III, mitochondrial thread-grain transition, and cytochrome c release from mitochondria. A novel mitochondrial protein required for thread-grain transition is identified.     

Phylogenetic relationships of typical antbirds (Thamnophilidae) and test of incongruence based on Bayes factors

Background  

The typical antbirds (Thamnophilidae) form a monophyletic and diverse family of suboscine passerines that inhabit neotropical forests. However, the phylogenetic relationships within this assemblage are poorly understood. Herein, we present a hypothesis of the generic relationships of this group based on Bayesian inference analyses of two nuclear introns and the mitochondrial cytochrome b gene. The level of phylogenetic congruence between the individual genes has been investigated utilizing Bayes factors. We also explore how changes in the substitution models affected the observed incongruence between partitions of our data set.     

Specific modification of nucleic acids inside the cell with alkylating derivatives of oligonucleotides ethylated at internucleotide phosphates

The alkylating derivatives of (C6H5NH)2P[dTp(Et)]4U and [dTp(Et)]9 U with completely esterified internucleotide phosphates bearing reactive 2,3 -O-4(N-2-chloroethyl N-methylamino)-benazylidene moiety attached to 3 -end cis-diol group were prepared. These alkylating derivatives of non-ionisable oligonucleotide analogs were demonstrated to penetrate efficiently into Krebs ascites tumor cells and to alkylate nucleic acids inside the cells with a strong preference towards complementary poly(A)-fragments of mRNA.     

Direct exchange of vitamin B12 is demonstrated by modelling the growth dynamics of algal–bacterial cocultures

The growth dynamics of populations of interacting species in the aquatic environment is of great importance, both for understanding natural ecosystems and in efforts to cultivate these organisms for industrial purposes. Here we consider a simple two-species system wherein the bacterium Mesorhizobium loti supplies vitamin B₁₂ (cobalamin) to the freshwater green alga Lobomonas rostrata, which requires this organic micronutrient for growth. In return, the bacterium receives photosynthate from the alga. Mathematical models are developed that describe minimally the interdependence between the two organisms, and that fit the experimental observations of the consortium. These models enable us to distinguish between different mechanisms of nutrient exchange between the organisms, and provide strong evidence that, rather than undergoing simple lysis and release of nutrients into the medium, M. loti regulates the levels of cobalamin it produces, resulting in a true mutualism with L. rostrata. Over half of all microalgae are dependent on an exogenous source of cobalamin for growth, and this vitamin is synthesised only by bacteria; it is very likely that similar symbiotic interactions underpin algal productivity more generally.     

Rate of progression of CT-quantified emphysema in male current and ex-smokers: a follow-up study

Background

Little is known about the factors associated with CT-quantified emphysema progression in heavy smokers. The objective of this study was to investigate the effect of length of smoking cessation and clinical / demographical factors on the rate of emphysema progression and FEV₁-decline in male heavy smokers.

Methods

3,670 male smokers with mean (SD) 40.8 (17.9) packyears underwent chest CT scans and pulmonary function tests at baseline and after 1 and 3 years follow-up. Smoking status (quitted ≥5, ≥1-<5, <1 years or current smoker) was noted. Rate of progression of emphysema and FEV₁-decline after follow-up were assessed by analysis of variance adjusting for age, height, baseline pulmonary function and emphysema severity, packyears, years in study and respiratory symptoms. The quitted ≥5 group was used as reference.

Results

Median (Q1-Q3) emphysema severity,<-950 HU, was 8.8 (5.1 – 14.1) and mean (SD) FEV₁ was 3.4 (0.73) L or 98.5 (18.5) % of predicted. The group quitted ‘>5 years’ showed significantly lower rates of progression of emphysema compared to current smokers, 1.07% and 1.12% per year, respectively (p<0.001). Current smokers had a yearly FEV₁-decline of 69 ml, while subjects quit smoking >5 years had a yearly decline of 57.5 ml (p<0.001).

Conclusion

Quit smoking >5 years significantly slows the rate of emphysema progression and lung function decline.

Trial registration

Registered at http://www.trialregister.nl with trial number ISRCTN63545820.     

Adjustment of juvenile tuatara to a cooler,southern climate: operative temperatures,emergence behaviour and growth rate

Translocations for conservation often involve species limited to relict distributions. However, uncertainty can exist regarding the ability of source individuals to acclimatise following a shift to a distant location. We investigated the ability of captive-reared juvenile tuatara (Sphenodon punctatus) of Cook Strait stock (41°S) to adjust to outdoor, predator-protected pens within Orokonui Ecosanctuary (45 °S). We examined potential basking and within burrow temperatures, the influence of temperature on emergence, and growth rates in comparison with other locations. Tuatara at Orokonui reached their preferred temperature when basking over summer, and burrows provided protection from freezing over winter. Emergence was temperature-dependent and essentially ceased during winter. Growth rates of Orokonui-held juveniles were within the range for four other captive-rearing facilities and faster than for wild juveniles from a Cook Strait population. As all Orokonui-held juveniles have survived and grown we conclude that the climate at this southern location is suitable to consider a free-release.     

Cooperative Interactions of the Oligodeoxyribonucleotides on the Complementary Template. The Influence of Chemical Groups and Mismatched Nucleotides at the 5′- and 3′-ends of Oligonucleotides on the Parameters of Cooperativity

Abstract

Parameters of cooperative interactions of two or three oligodeoxyribonucleotides or their derivatives bound with the adjacent sites of the complementary template were measured using method of “complementary addressed modification titration” (CAMT). Complementary template (target) were modified with the reactive oligonucleotide derivatives (reagents) bearing covalently attached alkylating 4-[N-(2-chloroethyl)-N-methylaminojbenzylamino- group (C1RCH₂NH)- at 5′-terminal phosphate. The targets had only one binding site for the reagent and either no (T10), or one (T'22 and T22) or two sites (T26) for the oligonucleotides (effectors) cooperatively bound with the adjacent sites on the template. Both unmodified oligonucleotides E₁, E₂ and their derivatives E₁ ^phn, E₂ ^phn bearing N- (2-hydroxyethyl)-phenazinium residues Phn- both at 5′- and 3′- ends covalently linked via ethylenediamine linker were used as effectors. Effectors E₁ and E₂ (E₁ ^Phn and E₂ ^Phn) bind, respectively, upstream or downstream from the reagent. Hexameric (X6) or octameric (X8 or X8^m) reagents were used for the target modification. The reagent X8^m formed one TT-mismatch with the target at the end opposite to location of the reactive moiety. The cooperativity parameter values characterizing the mutual interactions between the reagents X6, X8, X8^m and effectors E₁, E₂, E₁ ^phn, E₂ ^Phn have been found as the ratio of the association constants of the reagents in the presence of effectors. The association constants were calculated from the dependencies of the target modification extent on initial concentrations of the reagents. The use of T26 existing both in linear and hairpin conformations permitted us to estimate additionally the role of indirect cooperativity originating from the induction of the target conformational change by the effectors. The following conclusions were done from the quantitative results. The efficiency of direct cooperativity is independent on the length of oligonucleotide for the same nature of the contact. The cooperativity parameter increases by factor about 3 in the presence of Phn-group covalently attached to oligonucleotides and located at the junctions. The presence of either alkylating group CIRCH₂NH- or TT-mismatch at the junctions eliminates cooperative interaction between the bases. In the same time sufficiently effective cooperative interaction takes place in the case of simultaneous presence of both Phn- and either CIRCH₂NH- group or TT-mismatch at the junction.