Effects of the Physical Environment and Primate Gut Passage on the Early Establishment of Ampelocera hottlei Standley in Rain Forest Fragments

The regeneration of many tropical trees is threatened by forest fragmentation because it produces major physical, biological and ecological changes that limit seed germination and seedling establishment. We analyzed the regenerative potential of an old growth forest tree species—Ampelocera hottlei (Ulmaceae)—in three contrasting habitats located in the Lacandona rain forest, southeastern Mexico: continuous forest, fragments occupied by black howler monkeys (Alouatta pigra) and fragments unoccupied by howlers. We tested if germination of A. hottlei seeds among habitats was affected by understory temperature, light incidence and ingestion by A. pigra. We compared seedling survival and relative growth rate in height (RGR_H) for 20 d among habitats and between ingested and control seeds (from mature fruits). Germination was higher in continuous forest than in fragments (occupied or not), with higher germination rates for ingested seeds in fragments. Temperature and light incidence were lower in continuous forest than in fragments. Germination decreased with increasing temperature and light incidence with this relationship being significantly higher for ingested seeds. Seedling survival was higher in continuous forest than in fragments, whereas RGR_H did not differ among habitats. In addition, survival and RGR_H were higher in seedlings originating from ingested seeds. Overall, our results suggest that the populations of A. hottlei can be limited in fragments where changes in the understory physical environment and the extirpation of A. pigra will likely have deleterious consequences for the regeneration of A. hottlei and possibly for other tree species, ultimately affecting forest composition and structure. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

ENERGY EVALUATION OF MW EFFECTS ON ACh RECEPTOR CHANNELS WITH PARALLEL COMPUTING

We present an evaluation of the effects of microwave fields on the acetylcholine (ACh) receptor channel, based on energy issues. The channel is considered a stochastic automaton, flipping randomly from one state to another, and the incident field modifies transitions among the states. The observation of some appropriate biochemical parameters demonstrates that microwave fields cause conformational changes in the receptor site. An energetic mapping of ACh conformational changes is also achieved, clearing the ground for future development of this research in the field of molecular simulations.     

Dichlorophenyl dimethylurea (DCMU) induced increase in chlorophyll a fluorescence intensity – An index of photosynthetic oxygen evolution in leaves, chloroplasts and algae

Dichlorophenyl dimethylurea (DCMU) treatment in photosynthetic samples resulted in an increase in the level of steady state chlorophyll a fluorescence at room temperature which was directly proportional to the photosynthetic efficiency. The applicability of this method for the rapid determination of the efficiency of oxygen evolution in leaves, algae, mesophyll cells and chloroplasts has been investigated. Especially reliable values with less than 5% error were obtained if the fluorescence measurements were made under low excitation intensities with a sample chlorophyll concentration below 1.0 μg/ml.     

Influence of Different Storage Conditions on the Mycotoxin Production and Quality of Fusarium-Infected Wheat Grain

Wheat seed samples with different initial infection levels of Fusarium culmorum were kept under different storage conditions for 36 weeks. Samples for analysis were drawn before storage and at intervals of 6‐8 weeks to determine the mycotoxin contents, seed health and seed quality. Zearalcnone (ZEA) accumulated to higher kernel contents towards the end of storage, when the seed was stored under warm and humid conditions [25°C/90% relative humidity (RH)], whereas the deoxynivalenol (DON) content of severely infected kernel samples (> 50%) remained unchanged under any of the conditions. On the other hand, DON contents increased in samples with a slight (4%) or moderate (15%) Fusarium infection level. when the seed was stored under Warm and humid conditions. Nivalenol (NIV) was not found in any samples immediately after harvest but later on in storage, and only under cool or warm but very humid conditions (15°C/84% RH and 25°C/90% RH). During storage, the mycotoxin contents of the samples did not reflect the percentage of Fusarium infected kernels. Under warm but dry conditions (25°C/62% RH) the seed germination rate showed a slight increase or remained nearly constant; at the same time the Fusarium infection level of the kernels decreased fairly fast. Cool and dry conditions (15°C/56% RH) maintained good seed quality but the Fusarium infection level of the kernels remained largely the same. Warm and humid conditions are not appropriate to maintaining quality of both seed and grain product.     

Effects of housing condition and early corticosterone treatment on learned features of song in adult male zebra finches

Early developmental stress can have long-term physiological and behavioral effects on an animal. Developmental stress and early corticosterone (Cort) exposure affect song quality in many songbirds. Early housing condition can act as a stressor and affect the growth of nestlings and adult song, and improvements in housing condition can reverse adverse effects of early stress exposure in rodents. However, little is known about this effect in songbirds. Therefore, we took a novel approach to investigate if housing condition can modify the effects of early Cort exposure on adult song in male zebra finches. We manipulated early housing conditions to include breeding in large communal flight cages (FC; standard housing condition; with mixed-sex and mix-aged birds) versus individual breeding cages (IBC, one male–female pair with small, IBC-S, or large clutches, IBC-L) in post-hatch Cort treated male birds. We found that Cort treated birds from IBC-S have higher overall song learning scores (between tutor and pupil) than from FC but there is no difference between these groups in the No-Cort treated birds. When examining the effects of Cort within each housing condition, overall song learning scores decreased in Cort treated birds from flight cages but increased in birds from IBC-S compared to controls. Likewise, the total number of syllables and syllable types increased significantly in Cort treated birds from IBC-S, but decreased in FC-reared birds though this effect was not statistically significant. These findings suggest that the effects of early Cort treatment on learned features of song depend on housing condition.     

On simulation of air temperature curve near the ground in presence of frosts in Valley of Perote (Mexico)

An exponential of the time function was used in order to model the air temperature curve near the ground after frost in the Valley of Perote (Mexico). From January to March 1989 air temperature was recorded with a telethermograph, and data from 22 frosts were used to adjust and evaluate the exponential function.     

Microalgal polysaccharide production for the conditioning of agricultural soils

Summary Two species of mucilaginous green algae,Chlamydomonas mexicana andC. sajao, were evaluated forin situ production of polysaccharides in untilled samples of selected agricultural soils. Greenhouse experiments indicated that the moisture content of the soils must be maintained near 100% of field capacity to permit growth of the algae. The algae increased the polysaccharide content of the uppermost 2 mm of soil by 20% to 129%, but in only 3 treatments out of 12 was there any significant increase in soil polysaccharide content at the 3–8 millimeter depth. More than 99% of the algal cells and most of the polysaccharide produced by the algae remained in the top 2 millimeters of soil. The results suggest that although these algae can increase the polysaccharide content of the uppermost strata, where soil crust formation may present problems in agriculture, frequent irrigation is necessary to maintain algal growth. Tillage would be necessary to incorporate the algal polymers for soil conditioning at depths greater than 2 millimeters.     

Self-hydration and thermoregulatory processes of average-level paddlers during international surfski events in a tropical climate

The aim was to investigate thermal response, hydration behaviour and performance in flatwater kayaking races in tropical conditions (35.9 ± 2.8°C and 64 ± 4% RH). Eight regionally ranked paddlers (ARP) participated in the 2012 Surfski Ocean Racing World Cup in Guadeloupe (an inline 15-km downwind race). Core temperature (T_c) and heart rate (HR) were measured using portable telemetry units, while water intake was deduced from backpack absorption. The kayakers were asked to rate both their comfort sensation and thermal sensation on a scale before and after the race. The performance was not related to any measured parameters, and high values of post-race T_c were related to high pre-race T_c. The present study demonstrated that average-range paddlers are able to perform in a tropical climate, drinking little and paddling at high intensity without any interference from thermal sensations. Core temperature at the end of the race was positively related to pre-race T_c, which reinforces the importance of beginning surfski races with a low T_c and raises the question of pre-cooling strategies for paddlers, and more specifically for those with a low convection body surface.     

Periodic boundary conditions for the simulation of uniaxial extensional flow of arbitrary duration

It is very common with molecular dynamics and other simulation techniques to apply Lees–Edwards periodic boundary conditions (PBCs) for the simulation of shear flow. However, the behaviour of a complex liquid can be quite different under extensional flow. Simple deformation of a simulation cell and its periodic images only allows for simulations of these flows with short duration. For the simulation of planar extensional flow, it was recognised that the PBCs of Kraynik and Reinelt [Int. J. Multiphase Flow 1992;18:1045] could be used to perform simulations of this flow with arbitrary duration. However, a very common extensional flow in industrial applications and experiment is uniaxial extensional flow. Kraynik and Reinelt found that their method could not be directly generalised to this flow because of the lack of a lattice which reproduces itself during uniaxial extension. PBCs are presented in this article, which avoid this problem by finding a lattice which is compatible with the flow, finding the reduced basis to the lattice at all times and using this basis when calculating the position and separation of particles. Using these new PBCs, we perform nonequilibrium molecular dynamics simulations of a simple liquid and show that the technique gives results which agree with those from simulations using simply deforming PBCs.     

Standard guidelines for the publication of telomere qPCR results in evolutionary ecology

Telomere length has been used as a proxy of fitness, aging and lifespan in vertebrates. In the last decade, dozens of articles reporting on telomere dynamics in the fields of ecology and evolution have been published for a wide range of taxa. With this growing interest, it is necessary to ensure the accuracy and reproducibility of telomere length measurement techniques. Real‐time quantitative PCR (qPCR) is routinely applied to measure relative telomere length. However, this technique is highly sensitive to several methodological variables and the optimization of qPCR telomere assays remains highly variable between studies. Therefore, standardized guidelines are required to enable the optimization of robust protocols, and to help in judging the validity of the presented results. This review provides an overview of preanalytical and analytical factors that can lead to qPCR inconsistencies and biases, including: (a) sample type, collection and storage; (b) DNA extraction, storage and quality; (c) qPCR primers, laboratory reagents, and assay conditions; and (d) data analysis. We propose a minimum level of information for publication of qPCR telomere assays in evolutionary ecology considering the methodological pitfalls and sources of error. This review highlights the complexity of the optimization and validation of qPCR for telomere measurement per se, demonstrating the importance of transparency and clarity of reporting methodological details required for reliable, reproducible and comparable qPCR telomere assays. We encourage efforts to implement standardized protocols that ensure the rigour and quality of telomere dynamics studies.