More oxygen during development enhanced flight performance but not thermal tolerance of Drosophila melanogaster

High temperatures can stress animals by raising the oxygen demand above the oxygen supply. Consequently, animals under hypoxia could be more sensitive to heating than those exposed to normoxia. Although support for this model has been limited to aquatic animals, oxygen supply might limit the heat tolerance of terrestrial animals during energetically demanding activities. We evaluated this model by studying the flight performance and heat tolerance of flies (Drosophila melanogaster) acclimated and tested at different concentrations of oxygen (12%, 21%, and 31%). We expected that flies raised at hypoxia would develop into adults that were more likely to fly under hypoxia than would flies raised at normoxia or hyperoxia. We also expected flies to benefit from greater oxygen supply during testing. These effects should have been most pronounced at high temperatures, which impair locomotor performance. Contrary to our expectations, we found little evidence that flies raised at hypoxia flew better when tested at hypoxia or tolerated extreme heat better than did flies raised at normoxia or hyperoxia. Instead, flies raised at higher oxygen levels performed better at all body temperatures and oxygen concentrations. Moreover, oxygen supply during testing had the greatest effect on flight performance at low temperature, rather than high temperature. Our results poorly support the hypothesis that oxygen supply limits performance at high temperatures, but do support the idea that hyperoxia during development improves performance of flies later in life

Analysis of the Delta Variant B.1.617.2 COVID-19

With the delta variant of COVID-19, known as B.1.617.2, quickly ramping up infections around the world, we need to understand what makes this variant more contagious. One study has reported that the delta variant is 60% more transmissible than the alpha variant. As of August 2021, the delta variant has quickly become the dominant strain. Despite countries like the US, where most of the population is vaccinated, COVID-19 has made a resurgence in infections. Collectively, as a country, we ask: is it more deadly? What makes it more “contagious” or “transmissible”? This review article delves into the information we already know about the delta variant and how it compares with the other SARS-CoV-2 variants. The current vaccine companies like AstraZeneca, Pfizer/BioNTech, and Moderna have reported that their vaccines can provide protection against this variant but with a slightly reduced efficacy. In this article, we do a comprehensive review and summary of the delta B.1.617.2 variant and what makes it more contagious

Flight performance depended on body temperature and oxygen supply.

<p>At 37°C (left) and 39°C (center), flies performed better if they had developed with a greater supply of oxygen. At 41°C (right), flies performed poorly overall. The color of each bar denotes the oxygen level at which flies were tested (light gray = 12%, dark gray = 21%, black = 31%). The most likely probability of flight under each condition was computed by multimodel averaging. The number of observations used to estimate the mean is marked at the top of each bar.</p

All likely models included an effect of temperature on flight performance.

<p>The two most likely models also included an effect of developmental temperature. For each model, we provide the Akaike information criterion (<i>AIC</i>_<i>c</i>) and the Akaike weight, which equals the probability that the model describes the data better than other models. All models contained an intercept and an error term associated with isofemale line.</p

At 25°C, flies raised at normoxia performed best when tested at normoxia.

<p>The most likely probability of flight under each condition was computed by multimodel averaging. Fifty flies were tested at each concentration of oxygen.</p

The importance of factors in our models of flight performance and knockdown time.

<p>Importance equals the sum of Akaike weights for models that include the factor (or the probability that the factor would occur in the best model). A dash indicates that a factor was not considered in the set of models.</p