Biology subjects

van der Veen, D. R.

Publications and source records attributed to van der Veen, D. R..

3 recordsLinked to original sources

bioRxiv2024

Rhythmic variation in proteomics: challenges and opportunities for statistical power and biomarker identification

Time-of-day variation in the molecular profile of biofluids and tissues is a well-described phenomenon, but - especially for proteomics - is rarely considered in terms of the challenges this presents to reproducible biomarker identification. In this work we demonstrate these confounding issues using a small-scale proteomics analysis of male participants in a constant routine protocol following an 8-day laboratory study, in which sleep-wake, light-dark and meal timings were controlled. We provide a case study analysis of circadian and ultradian rhythmicity in proteins in the complement and coagulation cascades, as well as apolipoproteins, and demonstrate that rhythmicity increases the risk of Type II errors due to the reduction in statistical power from increased variance. For the proteins analysed herein we show that to maintain statistical power if chronobiological variation is not controlled for, n should be increased (by between 9% and 20%); failure to do so would increase {beta}, the chance of Type II error, from a baseline value of 20% to between 22% and 28%. Conversely, controlling for rhythmic time-of-day variation in study design offers the opportunity to improve statistical power and reduce the chances of Type II errors. Indeed, control of time-of-day sampling is a more cost-effective strategy than increasing sample sizes. We recommend that best practice in proteomics study design should account for temporal variation as part of sampling strategy where possible. Where this is impractical, we recommend that additional variance from chronobiological effects be considered in power calculations, that time of sampling be reported as part of study metadata, and that researchers reference any previously identified rhythmicity in biomarkers and pathways of interest. These measures would mitigate against both false and missed discoveries, and improve reproducibility, especially in studies looking at biomarkers, pathways or conditions with a known chronobiological component.

molecular biology↗

bioRxiv2019

Host circadian rhythms are disrupted during malaria infection in parasite genotype-specific manners

Infection can dramatically alter behavioural and physiological traits as hosts become sick and subsequently return to health. Such \"sickness behaviours\" include disrupted circadian rhythms in both locomotor activity and body temperature. Host sickness behaviours vary in pathogen species-specific manners but the influence of pathogen intraspecific variation is rarely studied. We examine how infection with the murine malaria parasite, Plasmodium chabaudi, shapes sickness in terms of parasite genotype-specific effects on host circadian rhythms. We reveal that circadian rhythms in host locomotor activity patterns and body temperature become differentially disrupted and in parasite genotype-specific manners. Locomotor activity and body temperature in combination provide more sensitive measures of health than commonly used virulence metrics for malaria (e.g. anaemia). Moreover, patterns of host disruption cannot be explained simply by variation in replication rate across parasite genotypes or the severity of anaemia each parasite genotype causes. It is well known that disruption to circadian rhythms is associated with non-infectious diseases, including cancer, type 2 diabetes, and obesity. Our results reveal that disruption of host circadian rhythms is a genetically variable virulence trait of pathogens with implications for host health and disease tolerance.

ecology↗

bioRxiv2017

Timing of host feeding drives rhythms in parasite replication

Circadian rhythms enable organisms to synchronise the processes underpinning survival and reproduction to anticipate daily changes in the external environment. Recent work shows that daily (circadian) rhythms also enable parasites to maximise fitness in the context of ecological interactions with their hosts. Because parasite rhythms matter for their fitness, understanding how they are regulated could lead to innovative ways to reduce the severity and spread of diseases. Here, we examine how host circadian rhythms influence rhythms in the asexual replication of malaria parasites. Asexual replication is responsible for the severity of malaria and fuels transmission of the disease, yet, how parasite rhythms are driven remains a mystery. We perturbed feeding rhythms of hosts by 12 hours (i.e. diurnal feeding in nocturnal mice) to desynchronise the hosts peripheral oscillators from the central, light-entrained oscillator in the brain and their rhythmic outputs. We demonstrate that the rhythms of rodent malaria parasites in day-fed hosts become inverted relative to the rhythms of parasites in night-fed hosts. Our results reveal that the hosts peripheral rhythms (associated with the timing of feeding and metabolism), but not rhythms driven by the central, light-entrained circadian oscillator in the brain, determine the timing (phase) of parasite rhythms. Further investigation reveals that parasite rhythms correlate closely with blood glucose rhythms. In addition, we show that parasite rhythms resynchronise to the altered host feeding rhythms when food availability is shifted, which is not mediated through rhythms in the host immune system. Our observations suggest that parasites actively control their developmental rhythms. Finally, counter to expectation, the severity of disease symptoms expressed by hosts was not affected by desynchronisation of their central and peripheral rhythms. Our study at the intersection of disease ecology and chronobiology opens up a new arena for studying host-parasite-vector coevolution and has broad implications for applied bioscience.\n\nAuthor summaryHow cycles of asexual replication by malaria parasites are coordinated to occur in synchrony with the circadian rhythms of the host is a long-standing mystery. We reveal that rhythms associated with the time-of-day that hosts feed are responsible for the timing of rhythms in parasite development. Specifically, we altered host feeding time to phase-shift peripheral rhythms, whilst leaving rhythms driven by the central circadian oscillator in the brain unchanged. We found that parasite developmental rhythms remained synchronous but changed their phase, by 12 hours, to follow the timing of host feeding. Furthermore, our results suggest that parasites themselves schedule rhythms in their replication to coordinate with rhythms in glucose in the hosts blood, rather than have rhythms imposed upon them by, for example, host immune responses. Our findings reveal a novel relationship between hosts and parasites that if disrupted, could reduce both the severity and transmission of malaria infection.

microbiology↗