Identification and expression analysis of CBF/DREB1 and COR15 genes in mutants of Brassica oleracea var. botrytis with enhanced proline production and frost resistance.

Frost resistant mutants of Brassica oleracea var. botrytis were investigated for the presence of CBF/DREB1 and COR15a gene products and induced frost resistance. Total RNA of clones was isolated after 3 h, 6 h, 24 h and 14 d acclimation at 4 °C and proteins and free proline were isolated after 14 d acclimation. cDNA was produced using RT-PCR and the first CBF gene in B. oleracea detected and did quantify. Through SDS-PAGE and Western blotting, the COR15a protein was detected for the first time in B. oleracea. The results confirmed the first report of the presence of BoCBF/DREB1 in B. oleracea and this only appeared under cold acclimation. The sequence analysis of predicted amino acids revealed a very high homology (90%) with CBF sequences of other Brassica species (BnCBF5/DREB1, BrDREB1 and BjDREB1B) and homology reduced to 67% when compared to plants other than Brassicas. BoCBF/DREB1 transcript levels increased up to 24 h acclimation and then declined. Some mutants showed BoCBF/DREB1 expression at 3 h while others only after 6 h and 24 h acclimation. The genotypes showed positive significant correlation between BoCBF/DREB1 expression and frost resistance (R(2) = 0.9343). The proline level under acclimation increased about 8 fold and demonstrated positive and significant correlation with BoCBF/DREB1 expression. Proline also showed positive and significant correlation with frost resistance under cold acclimation but very not under non-acclimation. All clones were positive for COR15a protein after 14 d cold acclimation and expression correlated with frost resistance. Under non-acclimation COR15a was constitutively expressed in 3 mutants

Short-term heat acclimation is effective and may be enhanced rather than impaired by dehydration

Most heat acclimation data are from regimes longer than 1 week, and acclimation advice is to prevent dehydration. Objectives: We hypothesized that (i) short-term (5-day) heat acclimation would substantially improve physiological strain and exercise tolerance under heat stress, and (ii) dehydration would provide a thermally independent stimulus for adaptation. Methods: Nine aerobically fit males heat acclimated using controlled-hyperthermia (rectal temperature 38.5°C) for 90 min on 5 days; once euhydrated (EUH) and once dehydrated (DEH) during acclimation bouts. Exercising heat stress tests (HSTs) were completed before and after acclimations (90-min cycling in T a 35°C, 60% RH). Results: During acclimation bouts, [aldosterone] plasma rose more across DEH than EUH (95%CI for difference between regimes: 40-411 pg ml -1 ; P=0.03; n=5) and was positively related to plasma volume expansion (r=0.65; P=0.05), which tended to be larger in DEH (CI: -1 to 10%; P=0.06; n=9). In HSTs, resting forearm perfusion increased more in DEH (by 5.9 ml 100 tissue ml -1 min -1 : -11.5 to -1.0; P=0.04) and end-exercise cardiac frequency fell to a greater extent (by 11 b min -1 : -1 to 22; P=0.05). Hydration-related effects on other endocrine, cardiovascular, and psychophysical responses to HSTs were unclear. Rectal temperature was unchanged at rest but was 0.3°C lower at end exercise (P < 0.01; interaction: P=0.52). Conclusions: Short-term (5-day) heat acclimation induced effective adaptations, some of which were more pronounced after fluid-regulatory strain from permissive dehydration, and not attributable to dehydration effects on body temperature. Am. J. Hum. Biol. 26:311-320, 2014. © 2014 Wiley Periodicals, Inc

A heat acclimation protocol for team sports

Background: It is well documented that heat acclimation of 6 or more sessions of at least 60 min duration prolongs the time to exhaustion during endurance walking, cycling and running in the heat. However, this type of acclimation is not specific to team sport activity and the effect of acclimation on prolonged high intensity intermittent running has not yet been investigated. Objective: To assess the impact of an intermittent acclimation protocol on distance run during team sport activity. Methods: The impact of 4 short heat acclimation sessions (30 – 45 min of the Loughborough Intermittent Shuttle Test; LIST) on high-intensity intermittent running capacity (LIST) in the heat (30oC, 27% RH), was examined. Seventeen female welltrained games players were split into 3 groups; an acclimation group (30oC, 24% RH), a moderate training group (18oC, 41% RH), and a control group who did not complete any training between the main trials (pre- and post-acclimation). The pre- (A) and post-acclimation (B) trials were separated by 28 days to control for menstrual phase and verified using hormonal analysis. The 4 acclimation or moderate training sessions utilising the LIST were completed with one or two rest days interspersed between each session in a 10-day period prior to the post-acclimation trial (B). Results: In the post-acclimation trial distance run was increased by 33% in the acclimation group (A: 7703 ± 1401 vs B: 10215 ± 1746m; interaction group x trial P<0.05), but was unchanged in the moderate and control groups. The acclimation group had a lower rectal temperature (interaction group x trial x time P<0.01) due to a lower rate of rise, and an increase in thermal comfort [1] after acclimation (End A: 7 ± 2 vs 6 ± 2; interaction group x trial P<0.01). There was no difference in serum 3 progesterone, aldosterone or cortisol concentrations following acclimation or between groups. Conclusion: Four 30-45 min sessions of intermittent exercise induced acclimation, and resulted in an improvement in intermittent running exercise capacity in female games players. A lower rectal temperature and a concomitant rise in thermal comfort may be partly responsible for the improvement in exercise capacity

How consistent are the transcriptome changes associated with cold acclimation in two species of the Drosophila virilis group?

This work was financially support by a Marie Curie Initial Training Network grant, “Understanding the evolutionary origin of biological diversity” (ITN-2008–213780 SPECIATION), grants from the Academy of Finland to A.H. (project 132619) and M.K. (projects 268214 and 272927), a grant from NERC, UK to M.G.R. (grant NE/J020818/1), and NERC, UK PhD studentship to D.J.P. (NE/I528634/1).For many organisms the ability to cold acclimate with the onset of seasonal cold has major implications for their fitness. In insects, where this ability is widespread, the physiological changes associated with increased cold tolerance have been well studied. Despite this, little work has been done to trace changes in gene expression during cold acclimation that lead to an increase in cold tolerance. We used an RNA-Seq approach to investigate this in two species of the Drosophila virilis group. We found that the majority of genes that are differentially expressed during cold acclimation differ between the two species. Despite this, the biological processes associated with the differentially expressed genes were broadly similar in the two species. These included: metabolism, cell membrane composition, and circadian rhythms, which are largely consistent with previous work on cold acclimation/cold tolerance. In addition, we also found evidence of the involvement of the rhodopsin pathway in cold acclimation, a pathway that has been recently linked to thermotaxis. Interestingly, we found no evidence of differential expression of stress genes implying that long-term cold acclimation and short-term stress response may have a different physiological basis.PostprintPeer reviewe

Artificial Gravity in Mars Orbit for Crew Acclimation

NASAs current baseline plan for a crewed Mars mission anticipates a transit time of up to three hundred days in microgravity and 3-14 days on the Martian surface for gravity acclimation before the crew can safely perform their first Extra-Vehicular Activity (EVA). While there are multiple options for how initial surface operations will be performed, all current designs involve acclimation on the surface, and the impacts on the mission schedule, required supplies, and crew lander systems are significant. This paper proposes an alternative option utilizing artificial gravity, which offers benefits in terms of mission scope, mass savings, crew health, and long-term strategic vision. By moving the acclimation requirement to the orbiting habitats existing systems, rather than adding redundant systems to the lander, the Mars Descent Vehicle (MDV) can be a much smaller, simpler, and lighter design. Rather than the lander being designed to support crew for days, it would be mere hours. While ambitious, the concept of pre-acclimation in orbit can be not only safe and feasible, but done with fairly minimal changes to the planned architecture and overall mass requirements. The data used draws on decades of established research and demonstrates how this capability can be not only used for pre-acclimation, but also to support crew during early orbital-only missions, surface abort contingency scenarios, return-to-orbit abort scenarios, and as an early proof of capability into larger and more ambitious artificial gravity designs needed for extended exploration missions in the future

The Influence of Body Size and Hemoglobin Multiplicity on Critical Oxygen Threshold in Red Drum (Sciaenops ocellatus)

Hypoxia is common in marine environments and fishes use a suite of cardiorespiratory adjustments to defend aerobic metabolism, including reducing standard metabolic rate (SMR), the minimum metabolic rate needed to sustain life at a specified temperature, or increasing hemoglobin (Hb)-O2 affinity. Nonetheless, hypoxia can constrain oxygen transport whereby fish cannot accommodate standard metabolic rate; a point known as critical oxygen tension (Pcrit). Currently, it is unclear how life history traits may impact Pcrit, but available data on red drum (Sciaenops ocellatus) suggest that its SMR decreases with size, and its transcriptome contains multiple Hb-α and Hb-β subunits. Therefore we sought to explore the influence of body size and acclimation to hypoxia. Critical oxygen tension (Pcrit) was measured for fish over a 2500-fold range in mass (0.26 - 686 g) and surprisingly showed an increase (Pcrit = 3.15 logM + 16.19; R2 = 0.44) despite decreasing SMR. Two groups of S. ocellatus (90.96 ± 5.00 g ranging from 69.7 g to 141.9 g) were also subjected to either normoxia ( > 95% P_(O_2 )) or hypoxia (30%±5% P_(O_2 )) treatment for two weeks. Only fish subjected to hypoxia treatment showed a statistically significant decrease in Pcrit after the treatment. Acclimation had no impact on gill surface area, diffusion distance or relative ventricular mass, but mRNA expression levels of the major Hb-α subunit switched from Hbα-3.1 in the normoxia group to Hbα-3.2 in the hypoxia treatment group and expression levels of Hbα-2, Hbα-3.2 and Hbβ-3.1 showed a statistically significant increase in the hypoxia treatment group. Decrease in P50 and thus an increase in Hb-O2 binding affinity was observed for fish subjected to hypoxia treatment. Taken together these data indicate that hypoxia tolerance is affected by both developmental stage and hypoxia acclimation.Integrative Biolog

Does Long-Term Elevation of CO2 Concentration Increase Photosynthesis in Forest Floor Vegetation? (Indiana Strawberry in a Maryland Forest).

As the partial pressure of CO2 (pCO2) in the atmosphere rises, photorespiratory loss of carbon in C3 photosynthesis will diminish and the net efficiency of light-limited photosynthetic carbon uptake should rise. We tested this expectation for Indiana strawberry (Duchesnea indica) growing on a Maryland forest floor. Open-top chambers were used to elevate the pCO2 of a forest floor habitat to 67 Pa and were paired with control chambers providing an ambient pCO2 of 38 Pa. After 3.5 years, D. indica leaves grown and measured in the elevated pCO2 showed a significantly greater maximum quantum efficiency of net photosynthesis (by 22%) and a lower light compensation point (by 42%) than leaves grown and measured in the control chambers. The quantum efficiency to minimize photorespiration, measured in 1% O2, was the same for controls and plants grown at elevated pCO2. This showed that the maximum efficiency of light-energy transduction into assimilated carbon was not altered by acclimation and that the increase in light-limited photosynthesis at elevated pCO2 was simply a function of the decrease in photorespiration. Acclimation did decrease the ribulose-1,5-bisphosphate carboxylase/oxygenase and light-harvesting chlorophyll protein content of the leaf by more than 30%. These changes were associated with a decreased capacity for light-saturated, but not light-limited, photosynthesis. Even so, leaves of D. indica grown and measured at elevated pCO2 showed greater light-saturated photosynthetic rates than leaves grown and measured at the current atmospheric pCO2. In situ measurements under natural forest floor lighting showed large increases in leaf photosynthesis at elevated pCO2, relative to controls, in both summer and fall. The increase in efficiency of light-limited photosynthesis with elevated pCO2 allowed positive net photosynthetic carbon uptake on days and at locations on the forest floor that light fluxes were insufficient for positive net photosynthesis in the current atmospheric pCO2