Interstitial movement and emergence of barbel Barbus barbus free embryos and larvae

The movement of barbel Barbus barbus free embryos in the interstitial zone and the timing of larval emergence were studied for 12 days in an artificial stream. After egg fertilization (day 1), hatching occurred on day 6, downstream interstitial movements of free embryos on day 9 and emergence and downstream movement of all larvae on day 12, with density of free embryos decreasing as day of emergence approached. The results suggest that a memory‐based response of B. barbus to environmental conditions, previously observed in 0+ year juveniles, begins at an early age.     

Folate metabolite profiling of different cell types and embryos suggests variation in folate one-carbon metabolism, including developmental changes in human embryonic brain

Apolipoprotein A-I (ApoA-I) mimetic peptide inhibits the development of atherosclerosis (AS) in apolipoprotein E-deficient mice; however, the underlying mechanism remains unclear. Endothelial progenitor cells (EPCs) can prevent AS progression through repairing proatherogenic factors impaired endothelium. In the present study, we examined the effect of reverse D-4F, one of apoA-I mimetic peptide on the proliferation, migration, and tube formation of mouse bone marrow-derived late EPCs. The present study showed that reverse D-4F (10–100 μg/ml) significantly improved the proliferation, migration, and tube formation of EPCs in a dose-dependent manner, and activated phospho-AKT at serine residue 473 and phospho-eNOS at serine residue 1177. LY294002 (PI3-kinase inhibitor) and L-NAME (NOS inhibitor) significantly inhibited reverse D-4F mediated improvement of EPCs biological functions, and LY294002 significantly decreased reverse D-4F stimulated activation of phospho-AKT (473) and phospho-eNOS (1177). The results indicate that reverse D-4F mediated improvement of EPCs functions is dependent on the PI3K/AKT/eNOS pathway.     

Acute effects of hydrogen peroxide on skeletal muscle microvascular oxygenation from rest to contractions

Reactive oxygen species, such as hydrogen peroxide (H(2)O(2)), exert a critical regulatory role on skeletal muscle function. Whether acute increases in H(2)O(2) modulate muscle microvascular O(2) delivery-utilization (Qo(2)/Vo(2)) matching [i.e., microvascular partial pressure of O(2) (Pmv(O(2)))] at rest and following the onset of contractions is unknown. The hypothesis was tested that H(2)O(2) treatment (exogenous H(2)O(2)) would enhance Pmv(O(2)) and slow Pmv(O(2)) kinetics during contractions compared with control. Anesthetized, healthy young Sprague-Dawley rats had their spinotrapezius muscles either exposed for measurement of blood flow (and therefore QO(2)), VO(2), and Pmv(O(2)), or exteriorized for measurement of force production. Electrically stimulated twitch contractions (1 Hz, ~7 V, 2-ms pulse duration, 3 min) were evoked following acute superfusion with Krebs-Henseleit (control) and H(2)O(2) (100 μM). Relative to control, H(2)O(2) treatment elicited disproportionate increases in QO(2) and VO(2) that elevated Pmv(O(2)) at rest and throughout contractions and slowed overall Pmv(O(2)) kinetics (i.e., ~85% slower mean response time; P < 0.05). Accordingly, H(2)O(2) resulted in ~33% greater overall Pmv(O(2)), as assessed by the area under the Pmv(O(2)) curve (P < 0.05). Muscle force production was not altered with H(2)O(2) treatment (P > 0.05), evidencing reduced economy during contractions (~40% decrease in the force/VO(2) relationship; P < 0.05). These findings indicate that, although increasing the driving force for blood-myocyte O(2) flux (i.e., Pmv(O(2))), transient elevations in H(2)O(2) impair skeletal muscle function (i.e., reduced economy during contractions), which mechanistically may underlie, in part, the reduced exercise tolerance in conditions associated with oxidative stress.     

Aging alters the contribution of nitric oxide to regional muscle hemodynamic control at rest and during exercise in rats

Advanced age is associated with altered skeletal muscle hemodynamic control during the transition from rest to exercise. This study investigated the effects of aging on the functional role of nitric oxide (NO) in regulating total, inter-, and intramuscular hindlimb hemodynamic control at rest and during submaximal whole body exercise. We tested the hypothesis that NO synthase inhibition (N(G)-nitro-l-arginine methyl ester, l-NAME; 10 mg/kg) would result in attenuated reductions in vascular conductance (VC) primarily in oxidative muscles in old compared with young rats. Total and regional hindlimb muscle VCs were determined via radiolabeled microspheres at rest and during treadmill running (20 m/min, 5% grade) in nine young (6-8 mo) and seven old (27-29 mo) male Fisher 344 × Brown Norway rats. At rest, l-NAME increased mean arterial pressure (MAP) significantly by ～17% and 21% in young and old rats, respectively. During exercise, l-NAME increased MAP significantly by ～13% and 19% in young and old rats, respectively. Compared with young rats, l-NAME administration in old rats evoked attenuated reductions in 1) total hindlimb VC during exercise (i.e., down by ～23% in old vs. 43% in young rats; P < 0.05), and 2) VC in predominantly oxidative muscles both at rest and during exercise (P < 0.05). Our results indicate that the dependency of highly oxidative muscles on NO-mediated vasodilation is markedly diminished, and therefore mechanisms other than NO-mediated vasodilation control the bulk of the increase in skeletal muscle VC during the transition from rest to exercise in old rats. Reduced NO contribution to vasomotor control with advanced age is associated with blood flow redistribution from highly oxidative to glycolytic muscles during exercise.     

Chemical and biological explorations of the electrophilic reactivity of the bioactive marine natural product halenaquinone with biomimetic nucleophiles

The electrophilic reactivity of the bioactive marine sponge natural product halenaquinone has been investigated by reaction with the biomimetic nucleophiles N-acetyl-l-cysteine and N_α-acetyl-l-lysine. While cysteine reacted at the vacant quinone positions C-14 and C-15, lysine was found to react preferentially at the keto-furan position C-1. A small library of analogues was prepared by reaction of halenaquinone with primary amines, and evaluated against a range of biological targets including phospholipase A₂, farnesyltransferases (FTases) and Plasmodium falciparum. Geranylamine analogue 11 exhibited the most potent activity towards FTases (IC₅₀ 0.017-0.031 μM) and malaria (IC₅₀ 0.53-0.62 μM).     

Risk screening of the potential invasiveness of non-native aquatic species in Vietnam

Biological Invasions - The impact of non-native species, together with their pervasiveness, necessitates a means of identifying which species are most likely to pose an elevated risk of becoming...     

Roles of alcohol dehydrogenase, lactate dehydrogenase and pyruvate decarboxylase in low-temperature sweetening in tolerant and susceptible varieties of potato (Solanum tuberosum)

Low-temperature sweetening (LTS) results when tubers of potato ( Solanum tuberosum ) are stored at temperatures below 9–10°C with the accumulation of sucrose and reducing sugars glucose and fructose. Our earlier study showed that the LTS-tolerant varieties have higher ethanol and lactate tissue levels compared with the LTS-susceptible variety Monona ( Blenkinsop et al. 2003 ), which led us to investigate the role of the anaerobic respiratory pathway in LTS tolerance. The anaerobic respiratory enzymes alcohol dehydrogenase (ADH), l -lactate dehydrogenase (LDH) and pyruvate decarboxylase (PDC) were, therefore, investigated in LTS-tolerant and -susceptible potato varieties. A positive correlation ( P ≤ 0.05) was observed between reducing sugar concentration and the K _M of PDC, with the LTS-tolerant ND 860-2 possessing a lower K _M and reducing sugar content than the LTS-susceptible Monona variety. The moderately LTS-tolerant variety, Snowden, exhibited intermediate behavior between the two aforementioned cultivars at 4°C. The isozyme profile of the tolerant varieties differed from the susceptible variety. Two groups of LDH isozyme families were observed in all varieties with the exception of ND 860-2, where the second group appeared only during low-temperature exposure. Moreover, the tolerant variety possessed one additional ADH isozyme. Gene expression levels of these enzymes were higher in ND 860-2 as compared with Monona at 4°C. The above results suggest that the anaerobic respiratory enzymes contribute to LTS-tolerance.