Biology subjects

Pearson, A. C.

Publications and source records attributed to Pearson, A. C..

3 recordsLinked to original sources

bioRxiv2024

Post-senescence reproductive rebound in Daphnia does not accelerate mortality and is associated with reversal of age-related transcriptional changes in lipid and protein metabolism

A long-lived species of zooplankton microcrustaceans, Daphnia magna, sometimes exhibits late-life rebound of reproduction, briefly reversing reproductive senescence. Such events are often interpreted as terminal investment in anticipation of imminent mortality. We demonstrate that such post-senescence reproductive events (PSREs) neither cause not anticipate increased mortality. We analyze an RNAseq experiment comparing young, old reproductively senescent, and old PSRE Daphnia females. We first show that overall age-related transcriptional changes are dominated by the increase transcription of guanidine monophosphate synthases and guanylate cyclases, as well as two groups of presumed transposon-encoded proteins and by a drop in transcription of protein synthesis-related genes. We then focus on gene families and functional groups in which full or partial reversal of age-related transcriptional changes occur. This analysis reveals reversal, in the PSRE individuals, of age-related up-regulation of apolipoproteins D, lysosomal lipases, and peptidases and of age-related down-regulation of E3 ubiquitin kinases, V-type proton ATPases, and numerous proteins related to mitochondrial and muscle functions. While it is not certain which of these changes enable reproductive rejuvenation, and which are by-products of processes that lead to it, we present some evidence that post-senescence reproductive events are associated with the reversal of age-related protein and lipid aggregates removal, apoptosis, and with restoration of mitochondrial integrity. Significance statementAdvances in aging studies revealed the need to extend the old-age health and functionality data from the Drosophila-C.elegans-yeast triad of model organisms to include those that combine the advantages of non-vertebrate models with stronger similarities to mammalian aging. This paper presents a previously unreported phenomenon: reproductive "rejuvenation" in Daphnia - a classic and a re-emerging choice model for longevity studies. These postsenescence reproductive episodes result in fecundity similar to that of young individuals and are accompanied by transcriptional shifts, often reverting age-related changes to youthful levels. Transcripts that show such reversal point to restoration of aggregate removal and of mitochondrial function. We believe that this finding opens a novel window of research towards mechanistic understanding of healthy aging.

ecology↗

bioRxiv2024

Short lifespan is one's fate, long lifespan is one's achievement: lessons from Daphnia

Studies of longevity and senescence rely on baseline life expectancy of reference genotypes measured in standardized conditions such as food level and group size. Variation in baseline lifespan data across labs and protocols and among genotypes can make longevity intervention studies difficult to compare, particularly when GxE interactions exist. Furthermore, extending the lifespan of a short-lived genotype or of any genotype under suboptimal conditions may be of a lesser theoretical and translational value than extending the maximal possible lifespan. Daphnia is rapidly becoming a model organism of choice for longevity research complementing data obtained on traditional models. In this study we report baseline longevity of several genotypes (parthenogenetic clones) of a long-lived species D. magna under a variety of laboratory protocols, aiming to document the highest possible lifespan, factors reducing it, and physiological parameters that change with age and correlate with longevity. Combining data from 25 different experiments across two labs we report strong differences among clones of different geographic origin, moderate effects of group size and medium composition on longevity, and strong GxE with respect to food level. Specifically, short-lived clones that tend to originate from small intermittent habitats show little or no caloric restriction (CR) longevity extension, while long-lived ones expand their lifespan even further when maintained at 25% of the ad libitum food. We find no evidence of any trade-offs between longevity and fecundity across clones or correlations with age-specific feeding rate. We find that in the short-lived, CR non-responsive clones show little correlation between longevity and two measures of lipid peroxidation (LPO: lipid hydroperoxides and MDA abundance). In contrast, the long-lived, CR-responsive clones show a positive longevity correlation with lipid hydroperoxide abundance at any age, and a negative correlation with MDA concentration measured at about median lifespan. This indicates differences among genotypes in longevity-related accumulation of LPO targets, efficiency of detoxification of LPO products, and/or their effects on longevity. Our observations support the hypothesis that a long lifespan can be affected by food availability and levels of oxidative damage, while genetically determined short lifespan remains short regardless. We suggest a set of condition and genotypes to be used as a reference for longevity studies in Daphnia.

ecology↗

bioRxiv2024

Cingulate cortex shapes early postnatal development of social vocalizations

The social dynamics of vocal behavior has major implications for social development in humans. We asked whether early life damage to the anterior cingulate cortex (ACC), which is closely associated with socioemotional regulation more broadly, impacts the normal development of vocal expression. The common marmoset provides a unique opportunity to study the developmental trajectory of vocal behavior, and to track the consequences of early brain damage on aspects of social vocalizations. We created ACC lesions in neonatal marmosets and compared their pattern of vocalization to that of age-matched controls throughout the first 6 weeks of life. We found that while early life ACC lesions had little influence on the production of vocal calls, developmental changes to the quality of social contact calls and their associated sequential and acoustic characteristics were compromised. These animals made fewer social contact calls, and when they did, they were short, loud and monotonic. We further determined that damage to ACC in infancy results in a permanent alteration in downstream brain areas known to be involved in social vocalizations, such as the amygdala and periaqueductal gray. Namely, in the adult, these structures exhibited diminished GABA-immunoreactivity relative to control animals, likely reflecting disruption of the normal inhibitory balance following ACC deafferentation. Together, these data indicate that the normal development of social vocal behavior depends on the ACC and its interaction with other areas in the vocal network during early life.

neuroscience↗