LANDSLIDE MONITORING IN A BUILT-UP AREA

The article deals with the evaluation and comparison of measured data from geotechnical monitoring of a gabion wall and an adjacent slope. In 2015, new anomalous phenomena related to deformations and a shift in the area of previously activated landslide were recorded on some monitoring elements in the area of the gabion wall. Measurements carried out in previous stages had revealed the re activation of landslides, probably due to a significant rise in groundwater levels, whose fluctuation has been up to 3 m. A proper evaluation of the obtained results cannot be quantified without the determination of warning status or without a stability calculation. Only the trend and magnitude of the measured values can be evaluated

Long-Term Cold Acclimation Extends Survival Time at 0°C and Modifies the Metabolomic Profiles of the Larvae of the Fruit Fly Drosophila melanogaster

Drosophila melanogaster is a chill-susceptible insect. Previous studies on this fly focused on acute direct chilling injury during cold shock and showed that lower lethal temperature (LLT, approximately -5°C) exhibits relatively low plasticity and that acclimations, both rapid cold hardening (RCH) and long-term cold acclimation, shift the LLT by only a few degrees at the maximum.We found that long-term cold acclimation considerably improved cold tolerance in fully grown third-instar larvae of D. melanogaster. A comparison of the larvae acclimated at constant 25°C with those acclimated at constant 15°C followed by constant 6°C for 2 d (15°C→6°C) showed that long-term cold acclimation extended the lethal time for 50% of the population (Lt(50)) during exposure to constant 0°C as much as 630-fold (from 0.137 h to 86.658 h). Such marked physiological plasticity in Lt(50) (in contrast to LLT) suggested that chronic indirect chilling injury at 0°C differs from that caused by cold shock. Long-term cold acclimation modified the metabolomic profiles of the larvae. Accumulations of proline (up to 17.7 mM) and trehalose (up to 36.5 mM) were the two most prominent responses. In addition, restructuring of the glycerophospholipid composition of biological membranes was observed. The relative proportion of glycerophosphoethanolamines (especially those with linoleic acid at the sn-2 position) increased at the expense of glycerophosphocholines.Third-instar larvae of D. melanogaster improved their cold tolerance in response to long-term cold acclimation and showed metabolic potential for the accumulation of proline and trehalose and for membrane restructuring

Overwintering Strategy and Mechanisms of Cold Tolerance in the Codling Moth (<i>Cydia pomonella</i>)

<div><p>Background</p><p>The codling moth (<i>Cydia pomonella</i>) is a major insect pest of apples worldwide. Fully grown last instar larvae overwinter in diapause state. Their overwintering strategies and physiological principles of cold tolerance have been insufficiently studied. No elaborate analysis of overwintering physiology is available for European populations.</p><p>Principal Findings</p><p>We observed that codling moth larvae of a Central European population prefer to overwinter in the microhabitat of litter layer near the base of trees. Reliance on extensive supercooling, or freeze-avoidance, appears as their major strategy for survival of the winter cold. The supercooling point decreases from approximately −15.3°C during summer to −26.3°C during winter. Seasonal extension of supercooling capacity is assisted by partial dehydration, increasing osmolality of body fluids, and the accumulation of a complex mixture of winter specific metabolites. Glycogen and glutamine reserves are depleted, while fructose, alanine and some other sugars, polyols and free amino acids are accumulated during winter. The concentrations of trehalose and proline remain high and relatively constant throughout the season, and may contribute to the stabilization of proteins and membranes at subzero temperatures. In addition to supercooling, overwintering larvae acquire considerable capacity to survive at subzero temperatures, down to −15°C, even in partially frozen state.</p><p>Conclusion</p><p>Our detailed laboratory analysis of cold tolerance, and whole-winter survival assays in semi-natural conditions, suggest that the average winter cold does not represent a major threat for codling moth populations. More than 83% of larvae survived over winter in the field and pupated in spring irrespective of the overwintering microhabitat (cold-exposed tree trunk or temperature-buffered litter layer).</p></div

Uncovering the benefits of fluctuating thermal regimes on cold tolerance of drosophila flies by combined metabolomic and lipidomic approach

International audienceWhen exposed to constant low temperatures (CLTs), insects often suffer from cumulative physiological injuries that can severely compromise their fitness and survival. Yet, mortality can be considerably lowered when the cold stress period is interrupted by periodic warm interruption(s), referred to as fluctuating thermal regimes, FTRs. In this study, we have shown that FTRs strongly promoted cold tolerance of Drosophila melanogaster adults. We then assessed whether this marked phenotypic shift was associated with detectable physiological changes, such as synthesis of cryoprotectants and/or membrane remodeling. To test these hypotheses, we conducted two different time-series Omics analyzes in adult flies submitted to CLTs vs. FTRs: metabolomics (GC/MS) and lipidomics (LC/ESI/MS) targeting membrane phospholipids. We observed increasing levels in several polyhydric alcohols (arabitol, erythritol, sorbitol, mannitol, glycerol), sugars (fructose, mannose) and amino acids (serine, alanine, glutamine) in flies under CLT. Prolonged exposure to low temperature was also associated with a marked deviation of metabolic homeostasis and warm interruptions as short as 2 h were sufficient to periodically return the metabolic system to functionality. Lipidomics revealed an increased relative proportion of phosphatidylethanolamines and a shortening of fatty acyl chains in flies exposed to cold, likely to compensate for the ordering effect of low temperature on membranes. We found a remarkable correspondence in the time-course of changes between the metabolic and phospholipids networks, both suggesting a fast homeostatic regeneration during warm intervals under FTRs. In consequence, we suggest that periodic opportunities to restore system-wide homeostasis contribute to promote cold tolerance under FTRs. © 2016 Elsevier B.V

Glutamine.

<p>Seasonal whole-body and tissues changes of glutamine concentrations in field-sampled caterpillars of <i>Cydia pomonella</i> during 2010/2011. Each point is the mean ± S.D. (<i>n</i> = 3 replicates, 3 individuals each). Influence of sampling date on glutamine concentration was tested by ANOVA followed by Bonferroni's post hoc test (means flanked with different letters are significantly different).</p

Cold tolerance is unaffected by oxygen availability despite changes in anaerobic metabolism

CITATION: Boardman, L., et al. 2016. Cold tolerance is unaffected by oxygen availability despite changes in anaerobic metabolism. Scientific Reports 6:32856, doi:10.1038/srep32856.The original publication is available at http://www.nature.com/srepInsect cold tolerance depends on their ability to withstand or repair perturbations in cellular homeostasis caused by low temperature stress. Decreased oxygen availability (hypoxia) can interact with low temperature tolerance, often improving insect survival. One mechanism proposed for such responses is that whole-animal cold tolerance is set by a transition to anaerobic metabolism. Here, we provide a test of this hypothesis in an insect model system (Thaumatotibia leucotreta) by experimental manipulation of oxygen availability while measuring metabolic rate, critical thermal minimum (CTmin), supercooling point and changes in 43 metabolites in moth larvae at three key timepoints (before, during and after chill coma). Furthermore, we determined the critical oxygen partial pressure below which metabolic rate was suppressed (c. 4.5 kPa). Results showed that altering oxygen availability did not affect (non-lethal) CTmin nor (lethal) supercooling point. Metabolomic profiling revealed the upregulation of anaerobic metabolites and alterations in concentrations of citric acid cycle intermediates during and after chill coma exposure. Hypoxia exacerbated the anaerobic metabolite responses induced by low temperatures. These results suggest that cold tolerance of T. leucotreta larvae is not set by oxygen limitation, and that anaerobic metabolism in these larvae may contribute to their ability to survive in necrotic fruit.https://www.nature.com/articles/srep32856Publisher's versio

Fresh mass, dry mass, total lipid mass.

<p>Gradual losses of FM, DM and total lipid mass (all masses are in mg) in caterpillars of <i>Cydia pomonella</i> during their overwintering in the field in 2011/2012. Each point is the mean ± S.D. (<i>n</i> = 10 individuals). Black symbols are for larvae that were analyzed at the beginning of November, while red symbols are for larvae, in which gradual loss of FM was measured in approximately 14 d-intervals throughout the cold season and their DM and total lipids were analyzed in April (see text for details). The larvae were located on tree trunks (see text for details) and the course of ambient temperatures was recorded in 2 h-intervals.</p

Cold tolerance.

<p>Survival at subzero temperatures in supercooled and partially frozen states in the field-sampled caterpillars of <i>Cydia pomonella</i> during 2010/2011. Each point is the percentage of survivors in a sample of <i>n</i> larvae (<i>n</i> = flanking number). Supercooled larvae were exposed either to −5°C for 14 d or to −15°C for 7 d. Partially frozen larvae were exposed to −5°C for 1 h.</p