New Insights into the Circadian Rhythm of Acute Myocardial Infarction in Subgroups

The aim of this study was to determine the existence of the circadian rhythm (CR) in the onset of acute myocardial infarction (AMI) in different patient subgroups. Information was collected about 41,244 infarctions from the database of the ARIAM (Analysis of Delay in AMI) Spanish multicenter study. CR in AMI were explored in subgroups of cases categorized by age, gender, previous ischemic heart disease (PIHD), outcome in coronary care unit, infarction electrocardiograph (ECG) characteristics (Q wave or non‐Q wave), and location of AMI. Cases were classified according to these variables in the different subgroups. To verify the presence of CR, a simple test of equality of time series based on the multiple‐sinusoid (24, 12, and 8 h periods) cosinor analysis was developed. For the groups as a whole, the time of pain onset as an indicator of the AMI occurrence showed a CR (p<0.0001), with a morning peak at 10:10 h. All the analyzed subgroups also showed CR. Comparison between subgroups showed significant differences in the PIHD (p<0.01) and infarction ECG characteristics (p<0.01) groups. The CR of the subgroup with Q‐wave infarction differed from that of non‐Q wave subgroup (p<0.01) when the patients had PIHD (23% in Q wave infarction vs. 39.2% in non‐Q wave). AMI onset followed a CR pattern, which is also observed in all analyzed subgroups. Differences in the CR according to the Q/non‐Q wave infarction characteristics could be determined by PIHD. The cosinor model fit with three components (24, 12, and 8 h periods) showed a higher sensitivity than the single 24 h period analysis.     

Effects of Transient and Continuous Wheel Running Activity on the Upper and Lower Limits of Entrainment to Light‐Dark Cycles in Female Hamsters

The entrainment limits to light‐dark cycles can be modified by the experimental conditions under which they are tested. Among the factors that may influence entrainment is the amount of wheel running exerted by the animal. In the present work, the effects of transitory and continuous wheel running on entrainment to light‐dark cycles were tested using a range of T cycles at the entrainment limits. Four groups of female hamsters were submitted to 1 h stepwise changes in T cycles. Two groups were exposed to T cycles of which the period was shortened at the lower limit from T22 to T18, and the other two groups were exposed to cycles that lengthened at the upper limit from T27 to T32. One of the groups at the lower limit and one at the upper limit had continuous access to a running wheel, while the others had the wheel locked, except at certain T when a lack of period control by T cycle appeared. The study demonstrates that access to running wheel widens the limits of entrainment to LD cycles. Specifically, the following observations were made: the effects of wheel running for entrainment were more evident in the groups with continuous access to wheel, as they did entrain to T19 and T32; continuous access to a wheel produced aftereffects only after T19, but not under T32; and when animals without a wheel showed relative coordination, unlocking the wheel favored entrainment in all the animals at T31, but in only 1 out 6 at T19. All of these indicate a different effect of the wheel running on the upper and lower limits of entrainment.     

Structural and Stereochemical Studies of Hydroxyanthraquinone Derivatives from the Endophytic Fungus Coniothyrium sp

Four known hydroxyanthraquinones ( 1–4 ) together with four new derivatives having a tetralone moiety, namely coniothyrinones A–D ( 5–8 ), were isolated from the culture of Coniothyrium sp., an endophytic fungus isolated from Salsola oppostifolia from Gomera in the Canary Islands. The structures of the new compounds were elucidated by detailed spectroscopic analysis and comparison with reported data. The absolute configurations of coniothyrinones A ( 5 ), B ( 6 ), and D ( 8 ) were determined by TDDFT calculations of CD spectra, allowing the determination of the absolute configuration of coniothyrinone C ( 7 ) as well. Coniothyrinones A ( 5 ), B ( 6 ), and D ( 8 ) could be used as ECD reference compounds in the determination of absolute configuration for related tetralone derivatives. This is the first report of anthraquinones and derivatives from an isolate of the genus Coniothyrium sp. These compounds showed inhibitory effects against the fungus Microbotryum violaceum, the alga Chlorella fusca, and the bacteria Escherichia coli and Bacillus megaterium. Chirality 25:141–148, 2013. © 2012 Wiley Periodicals, Inc.     

Time as a constraint on the distribution of feral goats at high latitudes

We use data on feral goats on the Isle of Rum to explore the hypothesis that time is a major constraint on the latitudinal and altitudinal distribution of this species. Daylength and temperature were the principal factors influencing the main time budget elements (feeding, moving and resting). Because the goats do not feed at night due to low ambient temperatures, they faced particular problems during winter when daylengths were at their shortest. A mean monthly windchill‐adjusted temperature of 5°C appeared to be a critical threshold in terms of the animals’ ability to survive on Rum. We used these data to model the animals’ time budgets at different latitudes and altitudes. We show that winter daylength would be shorter than the required feeding time north of about 60° latitude, with a narrowing altitudinal cone approaching sea level at this latitude. Biogeographic evidence confirms that feral goat populations are not self‐sustaining north of this latitude.     

Effects of salinity on the immune response of an ‘osmotic generalist’ bird

Salt stress can suppress the immune function of fish and other aquatic animals, but such an effect has not yet been examined in air-breathing vertebrates that frequently cope with waters (and prey) of contrasting salinities. We investigated the effects of seawater salinity on the strength and cost of mounting an immune response in the dunlin Calidris alpina, a long-distance migratory shorebird that shifts seasonally from freshwater environments during the breeding season to marine environments during migration and the winter period. Phytohaemagglutinin (PHA)-induced skin swelling, basal metabolic rate (BMR), body mass, fat stores, and plasma ions were measured in dunlins acclimated to either freshwater or seawater (salinity: 0.3 and 35.0 ‰, respectively). Seawater-acclimated dunlins mounted a PHA-induced swelling response that was up to 56 % weaker than those held under freshwater conditions, despite ad libitum access to food. Freshwater-acclimated dunlins significantly increased their relative BMR 48 h after PHA injection, whereas seawater-acclimated dunlins did not. However, this differential immune and metabolic response between freshwater- and seawater-acclimated dunlins was not associated with significant changes in body mass, fat stores or plasma ions. Our results indicate that the strength of the immune response of this small-sized migratory shorebird was negatively influenced by the salinity of marine habitats. Further, these findings suggest that the reduced immune response observed under saline conditions might not be caused by an energy or nutrient limitation, and raise questions about the role of osmoregulatory hormones in the modulation of the immune system.     

The critical soil P levels for crop yield, soil fertility and environmental safety in different soil types

Background and aims

Sufficient soil phosphorus (P) is important for achieving optimal crop production, but excessive soil P levels may create a risk of P losses and associated eutrophication of surface waters. The aim of this study was to determine critical soil P levels for achieving optimal crop yields and minimal P losses in common soil types and dominant cropping systems in China.

Methods

Four long-term experiment sites were selected in China. The critical level of soil Olsen-P for crop yield was determined using the linear-plateau model. The relationships between the soil total P, Olsen-P and CaCl₂-P were evaluated using two-segment linear model to determine the soil P fertility rate and leaching change-point.

Results

The critical levels of soil Olsen-P for optimal crop yield ranged from 10.9 mg kg^?1 to 21.4 mg kg^?1, above which crop yield response less to the increasing of soil Olsen-P. The P leaching change-points of Olsen-P ranged from 39.9 mg kg^?1 to 90.2 mg kg^?1, above which soil CaCl₂-P greatly increasing with increasing soil Olsen-P. Similar change-point was found between soil total P and Olsen-P. Overall, the change-point ranged from 4.6 mg kg^?1 to 71.8 mg kg^?1 among all the four sites. These change-points were highly affected by crop specie, soil type, pH and soil organic matter content.

Conclusions

The three response curves could be used to access the soil Olsen-P status for crop yield, soil P fertility rate and soil P leaching risk for a sustainable soil P management in field.     

Variation in cadmium accumulation and translocation among peanut cultivars as affected by iron deficiency

Purpose

The current study aimed to test the hypothesis that the variations in shoot Cd accumulation among peanut cultivars was ascribed to the difference in capacity of competition with Fe transport, xylem loading and transpiration.

Methods

A hydroponics experiment was conducted to determine the plant biomass, gas exchange, and Cd accumulation in Fe-sufficient or -deficient plants of 12 peanut cultivars, at low Cd level (0.2 μM CdCl₂).

Results

Peanut varied among cultivars in morpho-physiological response to Cd stress as well as Cd accumulation, translocation and distribution. Qishan 208 and Xvhua 13 showed a higher capacity for accumulating Cd in their shoots. Fe deficiency increased the concentration and amount of Cd in plant organs, but decreased TF _{root to shoot} and TF _{root to stem}, while TF _{stem to leaf} remained unaffected. Fe deficiency-induced increase rates of Cd concentration and total Cd amount in roots and leaves were negatively correlated with the values in Fe-sufficient plants. Transpiration rate was positively correlated with leaf Cd concentration, TF _{root to shoot}, TF _{root to stem} and TF _{stem to leaf}.

Conclusions

The difference in shoot Cd concentration among peanut cultivars was mainly ascribed to the difference in Fe transport system, xylem loading capacity and transpiration.     

Growth and survival of cork oak (Quercus suber) seedlings after simulated partial cotyledon consumption under different soil nutrient contents

Aims

We examined the importance of partial seed consumption (cotyledon loss) by rabbits in the early establishment of seedlings of cork oaks restricted to nutrient-impoverished soils.

Methods

To determine the importance of cotyledons in the growth and development of seedlings, we simulated two levels of predation [light (30 % cotyledon loss) and heavy (60 % loss) partial consumption] and two soil nutrient contents (nutrient-poor soil, nutrient-rich soil). Seedlings height, root length, dry root and shoot biomass, specific leaf mass, leaf density, gas exchange, chlorophyll fluorescence parameters and photosynthetic pigment concentrations were determined.

Results

Results indicated that effect of nutrient level on the growth of the oak seedlings was more important than that of cotyledon biomass. However, in nutrient–poor soils, cotyledon biomass played a major role in the early performance of cork oaks. Acorns grown in nutrient-rich substrate, despite having greater aerial vigor, were slower to develop a vertical root, and hence less likely to reach permanent moisture. Cotyledon loss caused a decrease in the biomass of roots and shoots when acorns were heavily consumed, and as a result experienced a reduction in net photosynthetic rate, stomatal conductance and chlorophyll concentration. Survival of seedlings was unaffected by either soil type or cotyledon loss.

Conclusions

Our results show that effects of soil type on the survival of oak seedlings were more important than those of cotyledon biomass. However, in a competitive situation, cotyledon biomass, as an indicative of growth nutrient support rather than an energy source, could be vital in a nutrient-poor environment, particularly in Mediterranean climate regions and for species with little inherent drought tolerance (as is the case of Quercus spp.), where rapid root growth is required to ensure that contact with soil moisture is maintained over the first summer.     

Converting paddy fields to Lei bamboo (Phyllostachys praecox) stands affected soil nutrient concentrations, labile organic carbon pools, and organic carbon chemical compositions

Background and aims

Land-use change often markedly alters soil carbon (C) and nitrogen (N) pool sizes with implications for climate change and soil sustainability. The objective of this research was to study the effect of converting paddy fields to Lei bamboo (Phyllostachys praecox) stands on soil C and N and other nutrient pools as well as the chemical structure of soil organic C (SOC) in the soil profile.

Methods

Soils (Anthrosols) from four adjacent paddy field–bamboo forest pairs with a known land-use history were sampled from Lin’an County, Zhejiang Province. Soil water soluble organic C (WSOC), hot water soluble organic C (HWSOC), microbial biomass C (MBC), readily oxidizable C (ROC), water soluble organic N (WSON), and other soil chemical and physical properties were determined. Soil organic C functional group compositions were determined by ¹³C-nuclear magnetic resonance (NMR).

Results

Concentrations of soil available P, available K, and different N forms increased (P?<?0.05) by the land-use conversion. Higher concentrations of SOC and total N (TN) were observed in the subsoil (20–40 and 40–60 cm soil layers) but not in the topsoil (0–20 cm layer) in the bamboo stands than in the paddy fields. The storage of SOC and TN in the entire soil profile (0–60 cm) increased by 56.7 and 70.7 %, respectively, after the land-use change. The increases in the SOC stock of the three soil layers were 11.0, 14.3, and 9.5 Mg C ha^?1, respectively. The conversion decreased WSOC concentrations in the subsoil but increased the ROC concentration in the topsoil. Solid-state NMR spectroscopy of soil samples showed that the conversion increased (P?<?0.05) the O-alkyl C content while decreased the aromatic C content, alkyl C to O-alkyl C ratio (A/O-A), and aromaticity of SOC.

Conclusions

Conversion of paddy fields to bamboo stands increased soil nutrient availability, and SOC and TN stocks. Effects of land-use change on C pools and C chemistry of SOC varied among different soil layers in the profile. The impact of the land-use conversion on soil organic C pools was not restricted to the topsoil, but changes in the subsoil were equally large and should be accounted for.