The effect of prolonged “bleaching” on skeletal banding and stable isotopic composition in Montastrea annularis

X-radiography and carbon and oxygen stable isotope analysis have been used to examine the effects of prolonged bleaching on the growth rate and chemical composition of the skeleton of the massive reef coral, Montastrea annularis. The post-bleaching linear growth of one colony that remained bleached for 10 to 12 months following the 1987 Caribbean-wide bleaching event was only 37% of mean annual growth from pre-bleaching years, and was manifest as a loss of the following year's low density band. Two colonies that did not bleach (normal) and two that bleached and regained their coloration (recovered) had linear growth rates over the same period that were 81 to 98% of mean pre-bleaching annual growth. Linear growth by a third recovered coral was 66% of pre-bleaching growth. No sub-annual stress bands were associated with the bleaching. The skeleton of the bleached colony had carbon and oxygen isotopic compositions that were reduced in range and enriched (increased) in both ¹³C and ¹⁸O in the post-bleaching year. The skeletons of two of the nine colonies, one bleached and one recovered, had depleted (reduced) ¹⁸O values (-5.3 and -4.8%., respectively) during the bleaching episode that agree with the suggestion that positive temperature anomalies occurred during, and may have caused, the bleaching event. The range and values for all other normal and recovered corals, however, were not different between the post-bleaching year and previous years. Our data suggest that stress bands and isotopic analysis of coral skeletons may not always be reliable tools for examining the occurrence, cause or effects of certain discrete stress events that may interrupt skeletal growth.     

Biochar’s effect on crop productivity and the dependence on experimental conditions—a meta-analysis of literature data

Background and aims

For the last decade, there has been an increasing global interest in using biochar to mitigate climate change by storing carbon in soil. However, there is a lack of detailed knowledge on the impact of biochar on the crop productivity in different agricultural systems. The objective of this study was to quantify the effect of biochar soil amendment (BSA) on crop productivity and to analyze the dependence of responses on experimental conditions.

Methods

A weighted meta-analysis was conducted based on data from 103 studies published up to April, 2013. The effect of BSA on crop productivity was quantified by characterizing experimental conditions.

Results

In the published experiments, with biochar amendment rates generally <30 t ha^?1, BSA increased crop productivity by 11.0 % on average, while the responses varied with experimental conditions. Greater responses were found in pot experiments than in field, in acid than in neutral soils, in sandy textured than in loam and silt soils. Crop response in field experiments was greater for dry land crops (10.6 % on average) than for paddy rice (5.6 % on average). This result, associated with the higher response in acid and sandy textured soils, suggests both a liming and an aggregating/moistening effect of BSA.

Conclusions

The analysis suggests a promising role for BSA in improving crop productivity especially for dry land crops, and in acid, poor-structured soils though there was wide variation with soil, crop and biochar properties. Long-term field studies are needed to elucidate the persistence of BSA’s effect and the mechanisms for improving crop production in a wide range of agricultural conditions. At current prices and C-trading schemes, however, BSA would not be cost-effective unless persistent soil improvement and crop response can be demonstrated.     

Strategies for maintaining Na⁺ balance in zebrafish (Danio rerio) during prolonged exposure to acidic water

Teleost fish store lipids among several tissues primarily as triacylglycerol (TG). Upon metabolic demand, stored TGs are hydrolyzed by hormone-sensitive lipase (HSL). In this study, two distinct cDNAs encoding HSL were isolated, cloned, and sequenced from adipose tissue of rainbow trout. The full-length cDNAs, designated HSL1 and HSL2, were 2562-bp and 2887-bp in length, respectively, and share 82% nucleotide identity. Phylogentic analysis suggests that the two HSLs derive from paralogous genes that may have arisen during a teleost-specific genome duplication event. Quantitative real-time PCR revealed that HSL1 and HSL2 were differentially expressed, both in terms of distribution among tissues as well as in terms of abundance within selected tissues of juvenile trout. HSL1 and HSL2 mRNAs were detected in the brain, spleen, pancreas, kidney, gill, intestine, heart, and white muscle, but were most abundant in the red muscle, liver, and adipose tissue. HSL1 mRNA was more abundant than HSL2 mRNA in the adipose tissue, whereas HSL2 mRNA was more abundant than HSL1 mRNA in the liver. Short term fasting (4 weeks) increased HSL1 and HSL2 mRNA expression in the adipose tissue, but only HSL1 mRNA levels increased in the liver and the red muscle. During a prolonged fast (6 weeks), there was continued elevation of HSL1 and HSL2 mRNA levels in the liver and muscle; HSL mRNA expression in mesenteric fat declined, coincident with depletion of mesenteric fat mass. Refeeding fish reduced HSL expression to levels seen in continuously fed fish. These findings indicate that the pattern of HSL expression is consistent with the diverse lipid storage pattern of fish and suggest that distinct mechanisms serve to regulate differential expression of the two HSLs in tissues and during a progressive fast.     

Monitoring athletes’ hydration status and sleep patterns during Ramadan observance: methodological and practical considerations

During Ramadan, dehydration and disturbed sleep patterns are common, so accurate reliable methods for the assessment of hydration and sleep of athletes are necessary to maintain performance. The purpose of this review is: (1) to identify appropriate tools/methods for monitoring hydration status and sleep in sports people; (2) to discuss which of these tools/methods can be confidently used by sport scientists and trainers during Ramadan; and (3) to discuss the possible link that may exist between sleep and hydration status. Several markers of hydration status are currently used and include body mass, plasma/serum osmolality, dilution techniques, and neutron activation analysis. Used in an appropriate context, all can be indicative of the hydration status in the laboratory. In the field, monitoring hydration status in physically active individuals and athletes may be performed using a combination of body mass with some measure of urine concentration (e.g. urine osmolality, urine-specific gravity, urine color) and sensation of thirst. During Ramadan, appropriate timing of sample collection and the use of reference methods in future studies are warranted. In the field, careful use of body mass in conjunction with urine indices may be used to monitor the hydration status of subjects practicing physical activity during Ramadan. There is a need for the use of polysomnography or actigraphy for sleep assessment during Ramadan in future laboratory-based studies of athletes. However, in the field, monitoring sleep–wake patterns may be performed using actigraphy and/or the PSQI questionnaire.     

Oxidative stress and its effect on cell functional activity in Alzheimer’s disease

The review summarizes literature data on the importance of oxidative stress as one of the pathogenetic mechanisms in Alzheimer’s disease. Special attention is paid to the main specific and nonspecific ways of reactive oxygen species (ROS) generation in the course of the disease development. Generated ROS influence functional activity of cells, particularly, apoptosis and the mitotic cycle. Phosphorylation/dephosphorylation processes associated with intense phosphorylation of tau protein and mitosis-specific proteins play the nodal regulatory role in the cell. Alzheimer’s disease is accompanied by impairments of the regulatory functions of peptidyl-prolyl isomerases, particularly, Pin1 involved in maintaining a balanced state of phosphorylation/dephosphorylation processes. Taking into consideration the multifactorial impairment of the cell cycle control, this process should be considered from the viewpoint of the general state of metabolic processes, and oxidative stress has one of the key positions in aging.     

Oddity and the ‘confusion effect’ in predation

We report on two sets of experiments designed to clarify the roles of sensory ‘confusion’ and prey ‘oddity’ as they interact to influence the hunting success of a pursuit predator, the largemouth bass (Micropterus salmoides), on silvery minnows (Hybognathus nuchalis). Bass quickly captured solitary minnows, but performed many unsuccessful attacks and took much longer to make a capture as prey school size was increased. At school sizes of eight and above, bass were effectively stymied, demonstrating the ‘confusion effect’. The inclusion of one or two ‘odd’ (blue-dyed) minnows in a school of eight greatly increased the ability of bass to capture both normal and odd prey, but this effect of oddity disappeared at a school size of 15. The implications of these results for understanding the adaptive basis of mixed species flocks, herds and schools is discussed.     

Influence of vibration on the excitability of spinal α-motoneurons under static conditions and during evoked stepping in humans

The excitability of spinal α-motoneurons in healthy humans was investigated with vibrostimulation (20–60 Hz) applied to different groups of muscles both under stationary conditions and during vibration-evoked stepping movements with leg suspension. In 15 subjects, the H-reflex amplitude was compared under the conditions of vibration of the left leg quadriceps femoris (QFM) or biceps femoris (BFM) muscle, as well as under the conditions of vibration of the contralateral, motionless leg QFM muscle in three spatial positions of the body: upright, supine, and lying on the side with the left leg suspended. Under dynamic conditions, the H-reflex value was compared during evoked and voluntary steppings at eight intervals of the step cycle. In all body positions, the vibration of each ipsilateral leg muscle caused a significant H-reflex suppression, this suppression being more prominent under the air-stepping conditions. The vibration of the contralateral leg QFM had weak influence on the H-reflex amplitude. In seven subjects, the vibration of the ipsilateral and contralateral leg muscles generated stepping movements. During vibration-evoked air-stepping, the H-reflex had different amplitudes in different phases of the step cycle. At the same time, the differences between responses under voluntary and involuntary stepping conditions were revealed only in the step cycle phase corresponding to the stance phase. Thus, the different degrees of the H-reflex suppression by vibration in different spatial positions of the body seem to depend on the summary afferent inflows to the spinal cord interneurons involved in the regulation of locomotion and posture. Apparently, an increase in the spinal cord neuronal excitability, which is necessary for activating locomotor automatism under the leg unloading conditions, occurs during evoked air-stepping in the swing phase.     

Human thermoregulatory responses during prolonged walking in water at 25, 30 and 35°C

Eight healthy and physically well-trained male students exercised on a treadmill for 60 min while being immersed in water to the middle of the chest in a laboratory flowmill. The water velocity was adjusted so that the intensity of exercise correspond to 50% maximal oxygen uptake of each subject, and experiments were performed once at each of three water temperatures: 25, 30, 35°C, following a 30-min control period in air at 25°C, and on a treadmill in air at an ambient temperature of 25°C. Thermal states during rest and exercise were determined by measuring rectal and skin temperatures at various points, and mean skin temperatures were calculated. The intensity of exercise was monitored by measuring oxygen consumption, and heart rate was monitored as an indicator for cardiovascular function. At each water temperature, identical oxygen consumption levels were attained during exercise, indicating that no extra heat was produced by shivering at the lowest water temperature. The slight rise in rectal temperature during exercise was not influenced by the water temperature. The temperatures of skin exposed to air rose slightly during exercise at 25°C and 30°C water temperature and markedly at 35°C. The loss of body mass increased with water temperature indicating that both skin blood flow and sweating during exercise increased with the rise in water temperature. The rise in body temperature provided the thermoregulatory drive for the loss of the heat generated during exercise. Heart rate increased most during exercise in water at 35°C, most likely due to enhanced requirements for skin blood flow. Although such requirements were certainly smallest at 25°C water temperature, heart rate at this temperature was slightly higher than at 30°C suggesting reflex activation of sympathetic control by cold signals from the skin. There was a significantly greater increase in mean skin and rectal temperatures in subjects exercising on the treadmill in air, compared to those exercising in water at 25°C. Accepted: 22 May 1998     

The effect of elevated CO2 on photochemistry and antioxidative defence capacity in wheat depends on environmental growing conditions – A FACE study

The present study examines photosynthesis, photochemistry and low weight molecular antioxidants (ascorbic acid and glutathione) of two Triticum aestivum L. cultivars (H45 and Yitpi) in response to growth under two CO₂ concentrations (elevated CO₂, e[CO₂] vs. ambient CO₂, a[CO₂]), two sowing times (time of sowing 1, TOS1, less stressful growing conditions vs. time of sowing 2, TOS2, more stressful growing conditions) and two water treatments (rain-fed vs. irrigated). The objective was to evaluate (1) if growth under e[CO₂] will alleviate climate stresses such as higher temperature and/or limited water supply thereby reducing the need for photoprotection and concentrations of low weight molecular antioxidants and (2) cultivar-specific responses to combined climate change factors which may be useful to identify intra-specific variation in stress tolerance for future breeding. We compared gas exchange, chlorophyll fluorescence and antioxidative defence compounds (ascorbic acid, glutathione) of flag leaves of Australian Grains Free Air Carbon dioxide Enrichment (AGFACE) grown wheat. When plants were grown under the less stressful growing conditions of TOS1, e[CO₂] increased light saturated net assimilation rates (A_sat) and quantum yield of PSII electron transport (ΦPSII) but decreased thermal energy dissipation (indicated by increased efficiency of open PSII centres, Fv′/Fm′), while antioxidant concentrations did not change. Under the more stressful growing conditions of TOS2, e[CO₂] also increased A_sat (like at TOS1), however, photochemical processes were not affected while antioxidant concentrations (especially ascorbic acid) were decreased. Cultivar specific responses also varied between sowing dates: Only at TOS2 and additional irrigation, antioxidant concentrations were lower in e[CO₂] grown H45 as compared to Yitpi indicating decreased photo-oxidative pressure in H45. These results suggest a photo-protective role of e[CO₂] as well as some intra-specific variability between investigated cultivars in their stress responsiveness, all strongly modified by environmental growing conditions.     

Genetic and biochemical studies on perchloroethylene ‘in vitro’ and ‘in vivo’

Perchloroethylene (PCE) was tested in a diploid strain (D7) of the yeast Saccharomyces cerevisiae in suspension tests with and without a mammalian microsomal activation system (S9) and ‘in vivo’ by the intrasanguineous host-mediated assay. In addition, enzyme alteration studies were performed in mice non-pretreated or pretreated with phenobarbital + β-naphthoflavone. PCE did not induce any genetic effect either ‘in vitro’ or ‘in vivo’. In the suspension test, PCE was more toxic without metabolic activation and less toxic with mammalian microsomal activation. The enzymatic determinations showed an increase of the aminopyrine demethylase activity and of the level of cytochrome P-450.     

Sharper angle,higher risk? The effect of cutting angle on knee mechanics in invasion sport athletes

IntroductionCutting is an important skill in team-sports, but unfortunately is also related to non-contact ACL injuries. The purpose was to examine knee kinetics and kinematics at different cutting angles.Material and methods13 males and 16 females performed cuts at different angles (45°, 90°, 135° and 180°) at maximum speed. 3D kinematics and kinetics were collected. To determine differences across cutting angles (45°, 90°, 135° and 180°) and sex (female, male), a 4 × 2 repeated measures ANOVA was conducted followed by post hoc comparisons (Bonferroni) with alpha level set at α ≤ 0.05 a priori.ResultsAt all cutting angles, males showed greater knee flexion angles than females (p < 0.01). Also, where males performed all cutting angles with no differences in the amount of knee flexion −42.53° ± 8.95°, females decreased their knee flexion angle from −40.6° ± 7.2° when cutting at 45° to −36.81° ± 9.10° when cutting at 90°, 135° and 180° (p < 0.01). Knee flexion moment decreased for both sexes when cutting towards sharper angles (p < 0.05). At 90°, 135° and 180°, males showed greater knee valgus moments than females. For both sexes, knee valgus moment increased towards the sharper cutting angles and then stabilized compared to the 45° cutting angle (p < 0.01). Both females and males showed smaller vGRF when cutting to sharper angles (p < 0.01).ConclusionIt can be concluded that different cutting angles demand different knee kinematics and kinetics. Sharper cutting angles place the knee more at risk. However, females and males handle this differently, which has implications for injury prevention.     

Effect of potassium humate on apple cv. ‘Golden Delicious’ cultured in vitro

The effects of humic substances on in vitro culture of Golden Delicious apple are reported. Potassium humate (KH) when used in proliferation showed a negative interaction with BA while it enhanced rooting when IBA was not present in the culture medium. In the presence of IBA, KH increased root number and reduced root growth. The highest concentration tested, 500 mg l^-1, caused a drastic reduction in root system development. 50 mg l^-1 KH hastened rooting and plants grew more rapidly when transferred to soil.     

The effect of antioxidants on in vivo and in vitro methemoglobin formation in erythrocytes of patients with Parkinson’s disease

Methemoglobin formation was examined in erythrocytes of 16 patients with Parkinson’s disease (PD) (stage 3–4 by the Hoehn and Yahr scale). The patients receiving levodopa-containing drugs (madopar, nakom) were also treated with intramuscular injections of mexidol (daily dose 100 mg/day) for 14 days. Control group included 12 clinically healthy persons. The erythrocyte methemoglobin content was determined by electronic paramagnetic resonance (EPR) using the EPR signal intensity with the g-factor 6.0. The methemoglobin content was significantly higher in erythrocytes of PD patients than in healthy donors. The complex therapy with mexidol normalized the methemoglobin content in erythrocytes of PD patients. Incubation in vitro of erythrocytes of donors and PD patients with acrolein increased the methemoglobin content, while incubation with carnosine normalized the methemoglobin content in erythrocytes of PD patients. Prophylactic (i.e. before acrolein addition) and therapeutic administration of carnosine to the incubation system with acrolein decreased the methemoglobin content to its initial level. Results of this study suggest that inclusion of the antioxidants mexidol and carnosine in the scheme of basic therapy of PD may reduce side effects associated with methemoglobinemia.     

The effect of prolonged anoxia at 3°C on tissue high energy phosphates and phosphodiesters in turtles: A 31P-NMR study

Selected tissues (skeletal muscle, heart ventrical, and liver), sampled from turtles (Chrysemys picta bellii) at 3°C either under normoxic conditions or after 12 weeks of anoxic submergence were quantiaatively analysed for intracellular pH and phosphorus metabolites using ³¹P-NMR. Plasma was tested for osmolality and for the concentrations of lactate, calcium, and magnesium to confirm anoxic stress. We hypothesized that, in the anoxic animals, tissue ATP levels would be maintained and that the increased osmolality of the body fluids of anoxic turtles would be accounted for by a corresponding increase in the concentrations of phosphodiesters. The responses observed differed among the three tissues. In muscle, ATP was unchanged by anoxia but phosphocreatine was reduced by 80%; in heart, both ATP and phosphocreatine fell by 35–40%. The reduction in phosphocreatine in heart tissue at 3°C was similar to that observed in isolated, perfused working hearts from turtles maintained at 20°C but no decrease in ATP occurred in the latter tissues. In liver, although analyses of several specimens were confounded by line-broadening, neither ATP nor phosphocreatine was detectable in anoxic samples. Phosphosdiesters were detected in amounts sufficient to account for 30% of normoxic cell osmotic concentration in heart and 11% and 12% in liver and muscle, respectively. The phosphodiester levels did not change in anoxia. Heart ventricular phosphodiester levels in turtles at 3°C were significantly higher than those determined for whole hearts from turtles at 20°C. ¹H, ¹³C and ³¹P NMR analyses of perchloric acid extracts of heart and skeletal muscle from 20°C turtles con firmed that the major phosphodiester observed by NMR in these tissues is serine ethanolamine phosphate. We conclude that the three types of tissues studied differ substantially in their ability to maintain levels of ATP during anoxia, and that liver may continue to function despite NMR-undetectable levels of this metabolite. In addition, we conclude that phosphodiesters do not serve as regulated osmolytes during anoxia, and that the functional significance of their high concentrations in turtle tissues remains uncertain.     

Effects of Trypanosoma congolense and nutritional supplements on establishment and outcome of pregnancy in trypanotolerant Djallonké ewes

Interactions between Trypanosoma congolense and nutritional status were studied in 42 ewes, bred at the peak of parasitaemia after synchronisation of oestrus. As experimental design a randomised block design was used with four treatment combinations (2×2 factors), of which two were on a restricted diet (L), the remainder on an unrestricted diet (H) and half of each nutritional group infected with T. congolense (LI, HI), the remainder serving as controls (LC, HC). Severity of parasitaemia was not influenced by supplementation and mortality rates were higher in the HI and LC groups, but these differences were found not significant. Progesterone levels during the synchronised cycle were significantly lower in the infected groups. Levels of pregnant specific protein B (PSPB) in pregnant sheep at days 21 and 26 were not significantly affected by nutrition or infection, despite the tendency of a decrease in infected groups. T. congolense clearly affected establishment of pregnancy, as shown by lower rates of pregnancy and extended intervals between breeding and confirmation of pregnancy, nor was there any benefit of nutritional supplementation. Mean progesterone concentration during pregnancy, in those ewes which lambed, was not different between groups. The effect of the T. congolense infection on the outcome of pregnancy was not clear with the LI and HC performing well and poor pregnancy outcomes in groups HI and LC, although differences in litter size might explain these anomalies. It is concluded that the most pronounced effect of T. congolense was a negative influence on establishment of pregnancy, with nutritional supplementation unable to overcome this effect but having a beneficial influence on maintenance and successful outcome of pregnancy. However, individual exceptions indicate that some ewes cope better with the negative effects of infection and poor nutrition.     

Neuroprotective effect of the hexapeptide HLDF-6 on rat hippocampal neurons on the in vivo and in vitro models of alzheimer’s disease

The neuroprotective effect of Thr-Gly-Glu-Asn-His-Arg hexapeptide (HLDF-6), a biologically active fragment of the differentiation factor of human leukemia cells (HLDF), was demonstrated on models of Alzheimer’s disease in vivo and in vitro. The syndromes of this pathology were induced in male rats by injection of beta-amyloid peptide (25–35) and ibotenic acid into the hippocampus. HLDF-6 prevented loss of long-term memory and decrease in the exploratory behavior of these animals and significantly decreased the number of pyknotic neurons in the CA1 area of the hippocampus. This peptide also exerts a protective effect in vitro on the primary cultures of the rat hippocampal and cerebellar neurons under conditions of the beta-amyloid toxicity. An increase in the dihydrotestosterone (DHT) content was demonstrated in the blood plasma of rats with the syndrome of Alzheimer’s disease and in the medium of the culture of hippocampal neurons in the presence of the Aβ(25–35) peptide. HLDF-6 inhibited this increase in both cases. A probable mechanism of the neuroprotective effect of HLDF-6 was suggested as being connected to its possible effect on both the biosynthesis and the metabolism of sex steroid hormones.     

Similarities and differences in the effect of cocaine on α-adrenergic and muscarinic response

Similarities and differences in the effect of cocaine on [alpha]-adrenergic and muscarinic receptors were shown in three experimental models. The postsynaptic stimulating effect of cocaine, mediated by [alpha]-adrenergic receptors was revealed in uninnervated chick amnion and innervated rat vas deferens. In vas deferens cocaine caused an increase of the amount of active [alpha]-adrenergic receptors, the appearance of an additional receptor pool, and change in the dimerization level. Cocaine acted as an antagonist on muscarinic receptors of the chick amnion. The inhibition by cocaine of muscarinic receptors in the rat brain cortex membranes led to a decrease in the number of receptors and their partial monomerization. Thus, cocaine influences both the [alpha]-adrenergic and the muscarinic response at the receptor level. Experiments on various objects have shown that cocaine activates the [alpha]-adrenergic response and inhibits the muscarinic one.