Fight or learn to live with the consequences?

Individuals can fight their infectious diseases by reducing the growth of a pathogen (resistance), but they can also ameliorate the disease it causes (tolerance). A recent paper shows that there is variation between mouse strains in tolerance to a rodent malaria and that this was negatively correlated with resistance. This is important, because tolerance has major implications for the epidemiology and coevolution of host-parasite interactions, but has been neglected in the animal literature.     

打架还是谈情做爱——Fight or Make Love?

性和暴力是文学艺术、电影永恒的两大主题。这两种截然不同的社会行为虽然非常有趣,但其神经生物学基础一直是个谜。最近加州理工学院的Anderson研究组在小鼠的下丘脑中发现了控制这两种不同行为的神经网络。     

Interleukin-33: Friend or Enemy in the Fight against Tumors?

Molecular Biology - Interleukin-33 (IL-33) belongs to the IL-1 cytokine family and acts as a danger signal. IL-33 is released from stressed or necrotic cells. Initially, IL-33 was described as an...     

Fight or flight? – Flight increases immune gene expression but does not help to fight an infection

Flight represents a key trait in most insects, being energetically extremely demanding, yet often necessary for foraging and reproduction. Additionally, dispersal via flight is especially important for species living in fragmented landscapes. Even though, based on life‐history theory, a negative relationship may be expected between flight and immunity, a number of previous studies have indicated flight to induce an increased immune response. In this study, we assessed whether induced immunity (i.e. immune gene expression) in response to 15‐min forced flight treatment impacts individual survival of bacterial infection in the Glanville fritillary butterfly (Melitaea cinxia). We were able to confirm previous findings of flight‐induced immune gene expression, but still observed substantially stronger effects on both gene expression levels and life span due to bacterial infection compared to flight treatment. Even though gene expression levels of some immunity‐related genes were elevated due to flight, these individuals did not show increased survival of bacterial infection, indicating that flight‐induced immune activation does not completely protect them from the negative effects of bacterial infection. Finally, an interaction between flight and immune treatment indicated a potential trade‐off: flight treatment increased immune gene expression in naïve individuals only, whereas in infected individuals no increase in immune gene expression was induced by flight. Our results suggest that the up‐regulation of immune genes upon flight is based on a general stress response rather than reflecting an adaptive response to cope with potential infections during flight or in new habitats.     

Elevators or stairs?

Background:

Staff in hospitals frequently travel between floors and choose between taking the stairs or elevator. We compared the time savings with these two options.

Methods:

Four people aged 26–67 years completed 14 trips ranging from one to six floors, both ascending and descending. We compared the amount of time per floor travelled by stairs and by two banks of elevators. Participants reported their fatigue levels using a modified Borg scale. We performed two-way analysis of variance to compare the log-transformed data, with participant and time of day as independent variables.

Results:

The mean time taken to travel between each floor was 13.1 (standard deviation [SD] 1.7) seconds by stairs and 37.5 (SD 19.0) and 35.6 (SD 23.1) seconds by the two elevators (F = 8.61, p < 0.001). The difference in time taken to travel by stairs and elevator equaled about 15 minutes a day. Self-reported fatigue was less than 13 (out of 20) on the Borg scale for all participants, and they all stated that they were able to continue their duties without resting. The extra time associated with elevator use was because of waiting for its arrival. There was a difference in the amount of time taken to travel by elevator depending on the time of day and day of the week.

Interpretation:

Taking the stairs rather than the elevator saved about 15 minutes each workday. This 3% savings per workday could translate into improved productivity as well as increased fitness.Open in a separate windowImage courtesy of © Thinkstock 2011The areas visited by hospital staff in internal medicine are often on different floors, with staff making multiple trips by stairs or elevator each day. The reasons for choosing to take the elevator over the stairs include concerns about dyspnea and fatigue, and the amount of time saved.Although many people feel that taking the elevator saves time, there is little evidence to support this claim. We compared travel times for staff taking elevators and stairs in a typical urban hospital.     

Heterosis or Neutrality?

Various statistics have been proposed on an ad hoc basis to test whether alleles at a locus are selectively neutral. By considering population models in which selection operates, this paper shows that the population homozygosity is a powerful test statistic for testing departures from neutrality, in the direction of heterozygote advantage or disadvantage. The sample homozygosity plays a similar role when only sample data are available. Some numerical examples are included, showing the application of the test.—An analysis is made of the effect of heterosis on such quantities as the expected number of alleles in the population or sample, the effective number of alleles, the expected homozygosity, and on the population and sample allele frequency distributions generally.