SurvCurv database and online survival analysis platform update

Easy C. elegans Worm Lifespan Plotting and Statistics with WLSplot

WLSplot is an R package used to easily analyze lifespan survival data, and display results graphically as a survival curve with useful labels and statistical information auto-generated from the data and added to the graph, within a single function. It is designed primarily with Caenorhabditis elegans lifespan data in mind initially but can easily be used for other types of survival data. The WLSplot GitHub repository provides a blank template spreadsheet to be used for collecting lifespan data, instructions on how to install and run WLSplot, and examples covering RNAi, Genotype, or Drug lifespan experimental set-ups. WLSplot can analyze and plot multiple experiments in bulk while correctly italicizing worm gene names and adding asterisks and p-values to the plot legend when a significantly different lifespan from the designated control lifespan is seen. This is returned as an editable scalable vector graphics (svg) file for each output, and WLSplot can also return the summary of the directly plotted data so that the researcher can do their own further manipulation, in addition to being able to edit the output svg files.

The Drosophila Individual Activity Monitoring and Detection System (DIAMonDS)

Here, we have developed DIAMonDS (Drosophila Individual Activity Monitoring and Detection System) comprising time-lapse imaging by a charge-coupled device (CCD) flatbed scanner and Sapphire, a novel algorithm and web application. DIAMonDS automatically and sequentially identified the transition time points of multiple life cycle events such as pupariation, eclosion, and death in individual flies at high temporal resolution and on a large scale. DIAMonDS performed simultaneous multiple scans to measure individual deaths (≤1152 flies per scanner) and pupariation and eclosion timings (≤288 flies per scanner) under various chemical exposures, environmental conditions, and genetic backgrounds. DIAMonDS correctly identified 74-85% of the pupariation and eclosion events and ~ 92% of the death events within ± 10 scanning frames. This system is a powerful tool for studying the influences of genetic and environmental factors on fruit flies and efficient, high-throughput genetic and chemical screening in drug discovery.

Calorie restriction is the most reasonable anti-ageing intervention: a meta-analysis of survival curves

Despite technological advances, the survival records from longevity experiments remain the most indispensable tool in ageing-related research. A variety of interventions, including medications, genetic manipulations and calorie restriction (CR), have been demonstrated to extend the lifespan of several species. Surprisingly, few systematic studies have investigated the differences among these anti-ageing strategies using survival data. Here, we conduct a comprehensive and comparative meta-analysis of numerous published studies on Caenorhabditis elegans and Drosophila. We found that CR and genetic manipulations are generally more effective than medications at extending the total lifespan in both models, and CR can improve the ageing pattern of C. elegans. We further analysed the survival variation for different anti-ageing medications and determined that hypoglycaemic agents and antioxidants are advantageous despite only moderately increasing the overall lifespan; therefore, these two types of medications are promising CR mimetics. Analysis of genetic manipulations also indicated that the genes or pathways that extend lifespan in a healthier pattern are associated with CR. These results suggest that CR or CR mimetics may be the most reasonable and potentially beneficial anti-ageing strategy.

Two forms of death in ageing Caenorhabditis elegans

Ageing generates senescent pathologies, some of which cause death. Interventions that delay or prevent lethal pathologies will extend lifespan. Here we identify life-limiting pathologies in Caenorhabditis elegans with a necropsy analysis of worms that have died of old age. Our results imply the presence of multiple causes of death. Specifically, we identify two classes of corpse: early deaths with a swollen pharynx (which we call 'P deaths'), and later deaths with an atrophied pharynx (termed 'p deaths'). The effects of interventions on lifespan can be broken down into changes in the frequency and/or timing of either form of death. For example, glp-1 mutation only delays p death, while eat-2 mutation reduces P death. Combining pathology and mortality analysis allows mortality profiles to be deconvolved, providing biological meaning to complex survival and mortality profiles.

Survival assays using Caenorhabditis elegans

Caenorhabditis elegans is an important model organism with many useful features, including rapid development and aging, easy cultivation, and genetic tractability. Survival assays using C. elegans are powerful methods for studying physiological processes. In this review, we describe diverse types of C. elegans survival assays and discuss the aims, uses, and advantages of specific assays. C. elegans survival assays have played key roles in identifying novel genetic factors that regulate many aspects of animal physiology, such as aging and lifespan, stress response, and immunity against pathogens. Because many genetic factors discovered using C. elegans are evolutionarily conserved, survival assays can provide insights into mechanisms underlying physiological processes in mammals, including humans.

Protocols to Study Aging in Drosophila

The fruit fly Drosophila melanogaster offers a host of advantages for studying the biology of aging: a well-understood biology, a wide range of genetic reagents, well-defined dietary requirements, and a relatively short life span, with a median of ~80 days and maximum ~100 days. Several phenotypes can be used to assess the aging process, but the simplest and most widely used metric is length of life. Here we describe a standard life span assay for Drosophila housed on a simple sugar/yeast diet.