Nonself vegetative fusion and genetic exchange in the arbuscular mycorrhizal fungus Glomus intraradices.

Arbuscular mycorrhizal fungi (AMF) form symbioses with the majority of plants and form extensive underground hyphal networks simultaneously connecting the roots of different plant species. No empirical evidence exists for either anastomosis between genetically different AMF or genetic exchange.Five isolates of one population of Glomus intraradices were used to study anastomosis between hyphae of germinating spores. We show that genetically distinct AMF, from the same field, anastomose, resulting in viable cytoplasmic connections through which genetic exchange could potentially occur.Pairs of genetically different isolates were then co-cultured in an in vitro system.Freshly produced spores were individually germinated to establish new cultures.Using several molecular tools, we show that genetic exchange occurred between genetically different AMF. Specific genetic markers from each parent were transmitted to the progeny. The progeny were viable, forming symbioses with plant roots. The phenotypes of some of the progeny were significantly different from either parent.Our results indicate that considerable promiscuity could occur in these fungi because nine out of 10 combinations of different isolates anastomosed. The ability to perform genetic crosses between AMF experimentally lays a foundation for understanding the genetics and evolutionary biology of these important plants symbionts.

Effect of length and location of heterologous sequences on RecA-mediated strand exchange.

We systematically investigated the effect of heterology on RecA-mediated strand exchange between double-stranded linear and single-stranded circular DNA. Strand exchange took place through heterologies of up to 150-200 base pairs when the insertion was at the proximal (initiating) end of the duplex DNA but was completely blocked by an insert of only 22 base pairs placed at the distal end of the duplex. In the case of medial heterology created by insertion either in the duplex or the single-stranded DNA, the ability of RecA to exchange strands decreased as the heterology was shifted toward the distal end of the duplex. These results suggest that two different strand exchange mechanisms operate in the proximal and distal portions of the duplex substrate.

The ATPase activity of RecA is needed to push the DNA strand exchange through heterologous regions.

The role of ATP hydrolysis during the RecA-mediated recombination reaction is addressed in this paper. Recent studies indicated that the RecA-promoted DNA strand exchange between completely homologous double- and single-stranded DNA can be very efficient in the absence of ATP hydrolysis. In this work we demonstrate that the energy derived from the ATP hydrolysis is strictly needed to drive the DNA strand exchange through the regions where the interacting DNA molecules are not in a homologous register. Therefore, in addition to the role of the ATP hydrolysis in promoting the dissociation of RecA from the products of the recombination reaction, as described earlier, ATP hydrolysis also plays a crucial role in the actual process of strand exchange, provided that the lack of homologous register obstructs the process of branch migration.

Leader corruption depends on power and testosterone

We used incentivized experimental games to manipulate leader power-the number of followers and the discretion leaders had to enforce their will. Leaders had complete autonomy in deciding payouts to themselves and their followers. Although leaders could make prosocial decisions to benefit the public good they could also abuse their power by invoking antisocial decisions, which reduced the total payouts to the group but increased leader's earnings. In Study 1 (N = 478), we found that both amount of followers and discretionary choices independently predicted leader corruption. In Study 2 (N = 240), we examined how power and individual differences (e.g., personality, hormones) affected leader corruption over time; power interacted with testosterone in predicting corruption, which was highest when leader power and baseline testosterone were both high. Honesty predicted initial level of leader antisocial decisions; however, honesty did not shield leaders from the corruptive effect of power.

A Dethroned King? The Limits of State Infrastructural Power in France

Since the 1980s in Western Europe, centralized states' control over subnational territories has been deeply affected by processes of Europeanization and regionalization. These changes have raised the issue of state territorial restructuring in a particular fashion: what capacity have formerly centralized states retained to steer and control subnational territories? The article draws on Mann's concept of infrastructural power, which refers to the state's capacity to exercise control and implement political decisions over the national territory. The article applies the two main operationalizations of the concept, namely the capability of the state to exercise control and the weight of the state in the subnational territories. Empirically, the article focuses on the French state in two policy sectors (education and housing). Although France is a most likely case, this article challenges this expectation, and shows the limits of the French state's infrastructural power over the subnational territories since the late 1980s.

Fat oxidation kinetics during exercise in obese individuals

Introduction An impaired ability to oxidize fat may be a factor in the obesity's aetiology (3). Moreover, the exercise intensity (Fatmax) eliciting the maximal fat oxidation rate (MFO) was lower in obese (O) compared with lean (L) individuals (4). However, difference in fat oxidation rate (FOR) during exercise between O and L remains equivocal and little is known about FORs during high intensities (>60% ) in O compared with L. This study aimed to characterize fat oxidation kinetics over a large range of intensities in L and O. Methods 12 healthy L [body mass index (BMI): 22.8±0.4] and 16 healthy O men (BMI: 38.9±1.4) performed submaximal incremental test (Incr) to determine whole-body fat oxidation kinetics using indirect calorimetry. After a 15-min resting period (Rest) and 10-min warm-up at 20% of maximal power output (MPO, determined by a maximal incremental test), the power output was increased by 7.5% MPO every 6-min until respiratory exchange ratio reached 1.0. Venous lactate and glucose and plasma concentration of epinephrine (E), norepinephrine (NE), insulin and non-esterified fatty acid (NEFA) were assessed at each step. A mathematical model (SIN) (1), including three variables (dilatation, symmetry, translation), was used to characterize fat oxidation (normalized by fat-free mass) kinetics and to determine Fatmax and MFO. Results FOR at Rest and MFO were not significantly different between groups (p≥0.1). FORs were similar from 20-60% (p≥0.1) and significantly lower from 65-85% in O than in L (p≤0.04). Fatmax was significantly lower in O than in L (46.5±2.5 vs 56.7±1.9 % respectively; p=0.005). Fat oxidation kinetics was characterized by similar translation (p=0.2), significantly lower dilatation (p=0.001) and tended to a left-shift symmetry in O compared with L (p=0.09). Plasma E, insulin and NEFA were significantly higher in L compared to O (p≤0.04). There were no significant differences in glucose, lactate and plasma NE between groups (p≥0.2). Conclusion The study showed that O presented a lower Fatmax and a lower reliance on fat oxidation at high, but not at moderate, intensities. This may be linked to a: i) higher levels of insulin and lower E concentrations in O, which may induce blunted lipolysis; ii) higher percentage of type II and a lower percentage of type I fibres (5), and iii) decreased mitochondrial content (2), which may reduce FORs at high intensities and Fatmax. These findings may have implications for an appropriate exercise intensity prescription for optimize fat oxidation in O. References 1. Cheneviere et al. Med Sci Sports Exerc. 2009 2. Holloway et al. Am J Clin Nutr. 2009 3. Kelley et al. Am J Physiol. 1999 4. Perez-Martin et al. Diabetes Metab. 2001 5. Tanner et al. Am J Physiol Endocrinol Metab. 2002