Generalist grasshoppers from thermally variable sites do not have higher thermal tolerance than grasshoppers from thermally stable sites - A study of five populations

Thermal tolerance allows many organisms, including insects, to withstand stressful temperatures. Thermal generalists are expected to have higher thermal tolerance than specialists, but the environmental conditions leading to the evolution of a thermal generalist life history are not fully understood. Thermal variability has been put forth as an evolutionary driver of high thermal tolerance, but rarely has this been empirically tested. We used a generalist agricultural pest grasshopper, Melanoplus differentialis, to test upper and lower thermal limits of populations that experienced different levels of thermal variability.We quantified thermal heterogeneity at five sites in a longitudinal transect in the Midwestern U.S. by examining, over a 101-year period, 1) variance in daily thermal maxima and minima; and 2) daily range. Also, as a measure of a biologically relevant thermal extreme, we depicted days per month at each site that reached a stressfully high temperature for M. differentialis. We collected individuals from these sites and tested their upper and lower thermal limits. We found that most of our metrics of thermal heterogeneity differed among sites, while all sites experienced an average of at least two stressfully high temperature events per month. We found that heavier males from these sites were able to withstand both warmer and colder temperatures than smaller males, while heavier females had no thermal advantage over lighter females. However, site of origin had no effect on thermal tolerance.Our findings indicate three things: 1) there is no clear correlation between thermal variability and thermal tolerance in the populations we studied; 2) weight affects thermal tolerance range among sites for M. differentialis males, and 3) thermal extremes may be more important than thermal variability in determining CTMax in this species.     

Beneficial developmental acclimation in reproductive performance under cold but not heat stress

Thermal plasticity can help organisms coping with climate change. In this study, we analyse how laboratory populations of the ectotherm species Drosophila subobscura, originally from two distinct latitudes and evolving for several generations in a stable thermal environment (18 °C), respond plastically to new thermal challenges. We measured adult performance (fecundity traits as a fitness proxy) of the experimental populations when exposed to five thermal regimes, three with the same temperature during development and adulthood (15-15 °C, 18-18 °C, 25-25 °C), and two where flies developed at 18 °C and were exposed, during adulthood, to either 15 °C or 25 °C. Here, we test whether (1) flies undergo stress at the two more extreme temperatures; (2) development at a given temperature enhances adult performance at such temperature (i.e. acclimation), and (3) populations with different biogeographical history show plasticity differences. Our findings show (1) an optimal performance at 18 °C only if flies were subjected to the same temperature as juveniles and adults; (2) the occurrence of developmental acclimation at lower temperatures; (3) detrimental effects of higher developmental temperature on adult performance; and (4) a minor impact of historical background on thermal response. Our study indicates that thermal plasticity during development may have a limited role in helping adults cope with warmer - though not colder - temperatures, with a potential negative impact on population persistence under climate change. It also emphasizes the importance of analysing the impact of temperature on all stages of the life cycle to better characterize the thermal limits.     

Infrared thermography reveals surface body temperature changes during proestrus and estrus reproductive phases in Gyr heifers (Bos taurus indicus)

Our aim was to evaluate the application of infrared thermography (IRT) to detect body surface temperature variation of body regions during the proestrus and estrus phases of the reproductive cycle of Gyr heifers and investigate environmental factors that could affect these measurements. Fifty-seven heifers were submitted to an ovulation synchronization protocol. This was followed by monitoring the heifers every 12 h over 60 h. Heifers were monitored for rectal and vaginal temperature using a digital thermometer. The surface temperature of the eye, vulva, and muzzle regions were monitored by IRT. Meteorological data was recorded for temperature and humidity. Observation of sexual behavior was performed to monitor estrus onset. Transrectal ultrasonography was used to identify the dominant follicle and confirm ovulation of all heifers. We observed a decrease in temperature of the rectum and vagina, as well as in the eye and vulva regions within the first 12 h after the completion of the synchronization. This period coincides with the expected proestrus phase of the estrous cycle. A progressive increase in all temperatures was noticed in the following 36 h, which coincides with the estrus phase of the reproductive cycle. The regions evaluated around the vulva and eye exhibited the highest temperature and experienced less environmental distortion than the muzzle area thermographs. Environmental factors, such as rainfall and temperature-humidity index, influenced the IRT readings altering the radiation patterns detected. In conclusion, IRT is an effective method to detect temperature variation during the proestrus and estrus phases in Gyr heifers. Furthermore, biological and environmental effects should be considered when collecting and interpreting IRT data in livestock.     

Validation of ThermoHuman automatic thermographic software for assessing foot temperature before and after running

The aim of the study was to evaluate an automatic thermographic software package (ThermoHuman®) for assessing skin temperature on the soles of the feet before and after running and to compare it with two manual definitions of the regions of interest (ROIs). 120 thermal images of the soles of the feet of 30 participants, at two measurement points (before and after running 30 min) and on two measurement days were analyzed. Three different models of thermographic image analyses were used to obtain the mean temperature of 9 ROIs: A) ThermoHuman (automatic definition of ROIs using ThermoHuman® software), B) Manual (manual delimitation of ROIs by proportion criteria), and C) Manual-TH (manual delimitation of ROIs in an attempt to replicate the regions analyzed by ThermoHuman). ThermoHuman resulted in an 86% reduction in time involved compared to manual delimitation. Fourteen of the 120 images (12%) presented some error in one or more of the ROI delimitations. Although the three procedures presented significant differences between them (53% in the comparison between ThermoHuman and Manual, 47% between ThermoHuman and Manual-TH, and 28% between Manual and Manual-TH), all differences had a small effect size (ES 0.2–0.4) or lower (ES < 0.2). Bland-Altman plots showed similar 95% limits of agreement between the three procedures before and after running. Intraclass correlation coefficient analysis of the three procedures presented excellent reliability (ICC>0.8). In conclusion, ThermoHuman® software was observed to be time-saving for image analysis with excellent reliability. Although results suggest that ThermoHuman® and manual methods are both valid in themselves, combining them is not recommended due to the differences observed between them.     

Rebalancing microbial carbon distribution for L-threonine maximization using a thermal switch system

In metabolic engineering, unbalanced microbial carbon distribution has long blocked the further improvement in yield and productivity of high-volume natural metabolites. Current studies mostly focus on regulating desired biosynthetic pathways, whereas few strategies are available to maximize L-threonine efficiently. Here, we present a strategy to guarantee the supply of reduced cofactors and actualize L-threonine maximization by regulating cellular carbon distribution in central metabolic pathways. A thermal switch system was designed and applied to divide the whole fermentation process into two stages: growth and production. This system could rebalance carbon substrates between pyruvate and oxaloacetate by controlling the heterogenous expression of pyruvate carboxylase and oxaloacetate decarboxylation that responds to temperature. The system was tested in an L-threonine producer Escherichia coli TWF001, and the resulting strain TWF106/pFT24rp overproduced L-threonine from glucose with 111.78% molar yield. The thermal switch system was then employed to switch off the L-alanine synthesis pathway, resulting in the highest L-threonine yield of 124.03%, which exceeds the best reported yield (87.88%) and the maximum available theoretical value of L-threonine production (122.47%). This inducer-free genetic circuit design can be also developed for other biosynthetic pathways to increase product conversion rates and shorten production cycles.     

Determination of heavy metals in the fruit of date palm growing at different locations of Riyadh

Exposure of heavy metals to human beings has risen dramatically in the last 50 years. In today’s urban and industrial society, there is no escaping from exposure to toxic chemicals and heavy metals. Humans are more likely to be exposed to heavy metal contamination from the dust that adheres to edible plants than from bioaccumulation. This is because it is very difficult to wash off all the dust particles from the plant material before ingesting them. The objectives of this experiment were to determine the concentrations of lead (Pb) and cadmium (Cd) in washing residues and in the tissues of fruits of date palm growing in 14 sites of Riyadh and also to assess whether the fruits were safe for human consumption. The washing residues and tissue of date palm fruits collected from different sites showed the presence of significant amounts of the Pb and Cd. The concentration of Pb in the dust and fruit tissue increased with increasing anthropogenic sources. Therefore, fruits of date palm might be used as a pollution indicator; it might be recommend that fruits of date palm could be safe for human consumption after washing. The mean concentration of Pb and Cd in all the samples collected from different sites is within the safe limits recommended by FAO/WHO.     

Effect of ionic liquids activation on laccase from Trametes versicolor: Enzymatic stability and activity

The stability and activity of laccase from Trametes versicolor in two water‐soluble ionic liquids (ILs), namely 1‐butyl‐3‐methylimidazolium methyl sulfate, [bmim][MeSO₄] and 1,3‐dimethylimidazolium methyl sulfate, [mmim][MeSO₄], were investigated in this study. Thermal inactivation of laccase was characterized in the presence of these both ILs and as expected first‐order kinetics was followed. Inactivation rate constant (k), half‐life time (t_1/2), and energy of activation (Ea) were determined. Kinetics of 2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulfonic acid) oxidation by laccase in the presence of these ILs was studied and Michaelis–Menten parameters were calculated. There is no enzymatic inactivation since the maximum reaction rate remained constant for IL concentrations up to 25%, and surprisingly, it was found that laccase was activated for concentrations of 35% of ILs, since the reaction rate increased 1.7 times.     

Identification of hot spots within harbour sediments through a new cumulative hazard index. Case study: Port of Bari,Italy

While numerous quality guidelines unquestionably drive the management of harbour sediments, port managers increasingly require easy-to-use tools supporting them in assessing the sediment quality. In this work, a new hazard index, named cumulative Normalized and Weighted Average Concentration (c_NWAC), is proposed, considering the concentrations of main hazardous, toxic and bio-accumulative sediment contaminants. This index is an upgraded version of the previously introduced NWAC index, which considered only the metal concentrations. The c_NWAC values range from 0 to 10 scores, and their visualization on a colour base code map leads to an easy identification of hotspots. The applicability of the new index was verified using a dataset derived from the analyses of 42 samples collected at different depths of the seabed of the Port of Bari (Italy). The concentrations of 58 parameters were considered, namely 11 metals and metalloids, 17 congeners of polychlorinated biphenyls (PCBs), 16 congeners of polycyclic aromatic hydrocarbons (PAHs), further 11 organic micropollutants, total organic carbon (TOC) and nutrients (N_tot, P_tot). For the study area, the obtained c_NWAC values resulted well correlated to the corresponding values of the commonly used mean Effects Range Median quotient (mERMq), and similar hazard categories were developed for the new index, even if the latter do not necessarily explain the real sediment toxicity, because they were derived from a different sediment dataset and different test species.Moreover, the hazard predictive ability of the new index was verified (with satisfactory results) by testing the considered samples by eco-toxicological assays, using three different biological species, and comparing the obtained results to the corresponding hazard categories developed for c_NWAC.     

A model for the time–temperature–mortality relationship in the chill-susceptible beetle, Alphitobius diaperinus, exposed to fluctuating thermal regimes

Exposing insects to a fluctuating thermal regime (FTR) compared with constant low temperature (CLT) significantly reduces cold-induced mortality. The beneficial effects of FTR result from physiological repair during warming intervals. The duration and the temperature experienced during the recovery period are supposed to strongly impact the resulting cold survival; however, disentangling the effects of both recovery variables had not been broadly investigated. In this study, we investigate cold tolerance (lethal time, Lt₅₀) of the polyphagous beetle Alphitobius diaperinus. We examined adult survival under various CLTs (0, 5, 10 and 15 °C), and under 20 different FTR conditions, where the 0 °C exposure alternated with various recovery temperatures (Rt) (5, 10, 15 and 20 °C) combined with various recovery durations (Rds) (0.5, 1, 2, 3 and 4 h). Under CLTs, Lt₅₀ increased with temperature until no mortality occurred above the upper limit of cold injury zone (ULCIZ). Under FTRs, Lt₅₀ increased with both Rt and Rd. The magnitude of the survival gain was clearly boosted when Rt was above the ULCIZ (at 20 °C). Based on a data matrix of lethal times with multiple Rt×Rd combinations, a predictive model showed that cold survival increased exponentially with Rt and Rd. This model was subsequently validated with additional survival tests. We suggest that increasing recovery durations associated with optimal recovery temperatures eventually leads to a progressive chilling compensation.     

Investigations of antiproliferative and antioxidant activity of β-lactam morpholino-1,3,5-triazine hybrids

This article reports for the first time the synthesis of some novel β-lactam morpholino-1,3,5-triazine hybrids by a [2+2]-cycloaddition reaction of imines 7a–c, 9a–c and 11 with ketenes derived from substituted acetic acids. The reaction was totally diastereoselective, leading exclusively to the formation of cis-β-lactams 8a–l, 10a–f and 12a–c. The synthesized compounds were tested for activity towards SW1116, MCF-7 and HepG2 cancer cell lines and non-cancerous HEK-293 cell line by MTT assay. None of the compounds exert an observable effect on HepG2, MCF-7 and HEK-293 cells, but compounds 7b, 8f, 8g, 8l, 10c, and 10e exhibited excellent growth inhibitory activity (IC₅₀ < 5 µM) against SW 1116 cells, comparable to that of doxorubicin (IC₅₀ = 6.9 µM). An evaluation of the antioxidant potential of each of the compounds, performed by diphenylpicrylhydrazyl (DPPH) assay, indicated that 7b, 9a, 9b and 9c have strong free radical scavenging activity. UV absorption titration studies reveal that 7b, 8l, 8g and 8f interact strongly with calf-thymus DNA (CT-DNA) in the order of 8l > 7b > 8f > 8g. Collectively, the in vitro capabilities of some of these morpholino-triazine imines and β-lactams suggest possible applications to development of new antioxidants and DNA binding therapeutics.