Distribution and characterization of recrystallization inhibitor activity in plant and lichen species from the UK and maritime Antarctic

Extracts from a range of evolutionarily diverse plant and lichen species from the UK and maritime Antarctic have been assayed for inhibition of ice recrystallization. Approximately 25% of overwintering UK species and all Antarctic species exhibited antifreeze activity when exposed to low temperature. Preliminary characterization of the active extracts has demonstrated that the molecules co-opted to antifreeze activity by different species are biochemically diverse.     

Contribution of the lean body mass to insulin resistance in postmenopausal women with visceral obesity: a Monet study

Some insulin-resistant obese postmenopausal (PM) women are characterized by an android body fat distribution type and higher levels of lean body mass (LBM) compared to insulin-sensitive obese PM women. This study investigates the independent contribution of LBM to the detrimental effect of visceral fat (VF) levels on the metabolic profile. One hundred and three PM women (age: 58.0+/-4.9 years) were studied and categorized in four groups on the basis of their VF (higher vs. lower) and lean BMI (LBMI=LBM (kg)/height (m2); higher vs. lower). Measures included: fasting lipids, glucose homeostasis (by euglycemic/hyperinsulinemic clamp technique and 2-h oral glucose tolerance test (OGTT)), C-reactive protein (CRP) levels, fat distribution (by computed tomography (CT) scan), and body composition (by dual-energy X-ray absorptiometry). Women in the higher VF/higher LBMI group had lower glucose disposal and higher plasma insulin levels compared to the other groups. They also had higher plasma CRP levels than the women in the lower VF/lower LBMI group. VF was independently associated with insulin levels, measures of glucose disposal, and CRP levels (P<0.05). LBMI was also independently associated with insulin levels, glucose disposal, and CRP levels (P<0.05). Finally, significant interactions were observed between LBMI and VF levels for insulin levels during the OGTT and measures of glucose disposal (P<0.05). In conclusion, VF and LBMI are both independently associated with alterations in glucose homeostasis and CRP levels. The contribution of VF to insulin resistance seems to be exacerbated by increased LBM in PM women.     

Physical Activity and Low-Fat Diet: Is it Enough to Maintain Weight Stability in the Reduced-Obese Individual Following Weight Loss by Drug Therapy and Energy Restriction?

DOUCET, ERIC, PASCAL IMBEAULT, NATALIE ALMÉRAS, AND ANGELO TREMBLAY. Physical activity and low-fat diet: Is it enough to maintain weight stability in the reduced-obese individual following weight loss by drug therapy and energy restriction? Obes Res. Objective: The anthropometric and physiological effects of a physical activity (PA) and a mildly energy-restricted low-fat diet (LFD) follow-up program after a long-term dietary restriction were studied in 12 men and 8 women. Research Methods and Procedures: The dietary restriction (?700 kcal/day) was accompanied by a fenfluramine (60 mg/day) or placebo treatment for 15 weeks, whereas the mean duration of the PA-LFD follow-up was 18 weeks. Results: The long-term dietary restriction reduced body weight (?11. 9 and ?7. 6 kg, p<. 001), fat mass (FM) (?10. 6 and ?5. 8 kg, p<0. 01), resting metabolic rate (RMR) (?304 kcal/day, p<0. 01 and ?148 kcal/day, NS) in men and women, respectively. A decrease in fat-free mass (FFM) was also observed in women (?1. 8 kg, p<0. 05). The PA-LFD follow-up preserved weight stability at a reduced body weight and caused an additional significant decrease in FM for men (?3. 4 kg, p<0. 05). This part of the intervention also caused an increase in daily RMR for men (134 kcal/day, NS) to the point where this value no longer differed from the pre-energy restriction value. In contrast, RMR was further reduced in women (?200 kcal/day) to the point where it Significantly differed from initial values (p<0. 01). Resting seated heart rate was reduced by the PA-LFD follow-up in men leading it to differ significantly from both pre- and post-energy restriction values (?8. 5 and ?5. 5 bpm, p<0. 01). Discussion: In conclusion, these results suggest that a PA-LFD follow-up has the potential to permit body weight stability and may even accentuate fat loss in the reduced-obese state. Moreover, resting energy expenditure is increased under such conditions in men. These stimulating effects seem to be specific to energy metabolism since seated heart rate was either further reduced or remained stable in response to the PA-LFD follow-up.     

Secondary sexual characters and sperm traits in coho salmon Oncorhynchus kisutch

A study was undertaken to examine secondary sexual characters (spawning colouration and overall body size) in relation to sperm metrics in one alternative reproductive tactic of coho salmon Oncorhynchus kisutch : large hooknose males that spawn in dominance-based hierarchies. Males with less intense red spawning colouration had higher sperm velocities than males with darker red spawning colouration. There was no relationship between male body size and sperm metrics. These results suggest that within an alternative reproductive tactic, variation in sperm competition intensity may select for a trade-off between investment in sexual colouration and sperm quality.     

DNA mesophases induced by spermidine: structural properties and biological implications.

Conditions of formation of DNA aggregates by the addition of spermidine were determined with 146 base pair DNA fragments as a function of spermidine and NaCl concentration. Two different phases of spermidine-DNA complexes are obtained: a cholesteric liquid crystalline phase with a large helical pitch, with interhelix distances ranging from 31.6 to 32.6 A, and a columnar hexagonal phase with a restricted fluidity in which DNA molecules are more closely packed (29.85 +/- 0.05 A). In both phases, the DNA molecule retains its B form. These phases are always observed in equilibrium with the dilute isotropic solution, and their phase diagram is defined for a DNA concentration of 1 mg/ml. DNA liquid crystalline phases induced by spermidine are compared with the DNA mesophases already described in concentrated solutions in the absence of spermidine. We propose that the liquid crystalline character of the spermidine DNA complexes is involved in the stimulation of the functional properties of the DNA reported in numerous experimental articles, and we discuss how the nature of the phase could regulate the degree of activity of the molecule.     

Extensive seed and pollen dispersal and assortative mating in the rain forest tree Entandrophragma cylindricum (Meliaceae) inferred from indirect and direct analyses

Pollen and seed dispersal are key processes affecting the demographic and evolutionary dynamics of plant species and are also important considerations for the sustainable management of timber trees. Through direct and indirect genetic analyses, we studied the mating system and the extent of pollen and seed dispersal in an economically important timber species, Entandrophragma cylindricum (Meliaceae). We genotyped adult trees, seeds and saplings from a 400‐ha study plot in a natural forest from East Cameroon using eight nuclear microsatellite markers. The species is mainly outcrossed (t = 0.92), but seeds from the same fruit are often pollinated by the same father (correlated paternity, r_p = 0.77). An average of 4.76 effective pollen donors (N_ep) per seed tree contributes to the pollination. Seed dispersal was as extensive as pollen dispersal, with a mean dispersal distance in the study plot approaching 600 m, and immigration rates from outside the plot to the central part of the plot reaching 40% for both pollen and seeds. Extensive pollen‐ and seed‐mediated gene flow is further supported by the weak, fine‐scale spatial genetic structure (Sp statistic = 0.0058), corresponding to historical gene dispersal distances (σ_g) reaching approximately 1,500 m. Using an original approach, we showed that the relatedness between mating individuals (F_ij = 0.06) was higher than expected by chance, given the extent of pollen dispersal distances (expected F_ij = 0.02 according to simulations). This remarkable pattern of assortative mating could be a phenomenon of potentially consequential evolutionary and management significance that deserves to be studied in other plant populations.     

Neuromuscular electrical stimulation for skeletal muscle function

Lack of neural innervation due to neurological damage renders muscle unable to produce force. Use of electrical stimulation is a medium in which investigators have tried to find a way to restore movement and the ability to perform activities of daily living. Different methods of applying electrical current to modify neuromuscular activity are electrical stimulation (ES), neuromuscular electrical stimulation (NMES), transcutaneous electrical nerve stimulation (TENS), and functional electrical stimulation (FES). This review covers the aspects of electrical stimulation used for rehabilitation and functional purposes. Discussed are the various parameters of electrical stimulation, including frequency, pulse width/duration, duty cycle, intensity/amplitude, ramp time, pulse pattern, program duration, program frequency, and muscle group activated, and how they affect fatigue in the stimulated muscle.