Head-to-Head Comparison of Three Methods of Quantifying Competitive Fitness in C. elegans

AbstractOrganismal fitness is relevant in many contexts in biology. The most meaningful experimental measure of fitness is competitive fitness, when two or more entities (e.g., genotypes) are allowed to compete directly. In theory, competitive fitness is simple to measure: an experimental population is initiated with the different types in known proportions and allowed to evolve under experimental conditions to a predefined endpoint. In practice, there are several obstacles to obtaining robust estimates of competitive fitness in multicellular organisms, the most pervasive of which is simply the time it takes to count many individuals of different types from many replicate populations. Methods by which counting can be automated in high throughput are desirable, but for automated methods to be useful, the bias and technical variance associated with the method must be (a) known, and (b) sufficiently small relative to other sources of bias and variance to make the effort worthwhile.The nematode Caenorhabditis elegans is an important model organism, and the fitness effects of genotype and environmental conditions are often of interest. We report a comparison of three experimental methods of quantifying competitive fitness, in which wild-type strains are competed against GFP-marked competitors under standard laboratory conditions. Population samples were split into three replicates and counted (1) “by eye” from a saved image, (2) from the same image using CellProfiler image analysis software, and (3) with a large particle flow cytometer (a “worm sorter”). From 720 replicate samples, neither the frequency of wild-type worms nor the among-sample variance differed significantly between the three methods. CellProfiler and the worm sorter provide at least a tenfold increase in sample handling speed with little (if any) bias or increase in variance.

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An intestinally secreted host factor promotes microsporidia invasion of C. elegans

eLife ◽

10.7554/elife.72458 ◽

2022 ◽

Vol 11 ◽

Author(s):

Hala Tamim El Jarkass ◽

Calvin Mok ◽

Michael R Schertzberg ◽

Andrew G Fraser ◽

Emily R Troemel ◽

...

Keyword(s):

Bacterial Pathogen ◽

Oral Route ◽

Intestinal Lumen ◽

Wild Type ◽

Parasite Invasion ◽

Competitive Fitness ◽

Obligate Intracellular ◽

C Elegans ◽

Fitness Advantage ◽

Trade Offs

Microsporidia are ubiquitous obligate intracellular pathogens of animals. These parasites often infect hosts through an oral route, but little is known about the function of host intestinal proteins that facilitate microsporidia invasion. To identify such factors necessary for infection by Nematocida parisii, a natural microsporidian pathogen of Caenorhabditis elegans, we performed a forward genetic screen to identify mutant animals that have a Fitness Advantage with Nematocida (Fawn). We isolated four fawn mutants that are resistant to Nematocida infection and contain mutations in T14E8.4, which we renamed aaim-1 (Antibacterial and Aids invasion by Microsporidia). Expression of AAIM-1 in the intestine of aaim-1 animals restores N. parisii infectivity and this rescue of infectivity is dependent upon AAIM-1 secretion. N. parisii spores in aaim-1 animals are improperly oriented in the intestinal lumen, leading to reduced levels of parasite invasion. Conversely, aaim-1 mutants display both increased colonization and susceptibility to the bacterial pathogen Pseudomonas aeruginosa and overexpression of AAIM-1 reduces P. aeruginosa colonization. Competitive fitness assays show that aaim-1 mutants are favoured in the presence of N. parisii but disadvantaged on P. aeruginosa compared to wild type animals. Together, this work demonstrates how microsporidia exploits a secreted protein to promote host invasion. Our results also suggest evolutionary trade-offs may exist to optimizing host defense against multiple classes of pathogens.

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Microfluidic immobilization and subcellular imaging of developing Caenorhabditis elegans

10.1101/139915 ◽

2017 ◽

Author(s):

Jordan Shivers ◽

Sravanti Uppaluri ◽

Clifford P. Brangwynne

Keyword(s):

Larval Development ◽

Protein Interactions ◽

3D Imaging ◽

Fluorescence Recovery After Photobleaching ◽

Model Organism ◽

Fluorescence Recovery ◽

C Elegans ◽

Nucleolar Proteins ◽

Multicellular Organisms

C. elegans has been an essential model organism in the fields of developmental biology, neuroscience, and aging. However, these areas have been limited by our ability to visualize and track individual C. elegans worms, especially at the subcellular scale, over the course of their lifetime. Here we present a microfluidic device to culture individual C. elegans in parallel throughout post-embryonic development. The device allows for periodic mechanical immobilization of the worm, enabling 3D imaging at subcellular precision. The immobilization is sufficient to enable fluorescence recovery after photobleaching (FRAP) measurements on organelles and other substructures within the same specific cells, throughout larval development, without the use of chemical anesthetics. Using this device, we measure FRAP recovery of two nucleolar proteins in specific intestinal cells within the same worms during larval development. We show that these exhibit different fluorescence recovery as they grow, suggesting differential protein interactions during development. We anticipate that this device will help expand the possible uses of C. elegans as a model organism, enabling its use in addressing fundamental questions at the subcellular scale, including the role of phase transitions in driving spatiotemporal intracellular organization within multicellular organisms.

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Supplemental Cellular Protection by a Carotenoid Extends Lifespan via Ins/IGF-1 Signaling inCaenorhabditis elegans

Oxidative Medicine and Cellular Longevity ◽

10.1155/2011/596240 ◽

2011 ◽

Vol 2011 ◽

pp. 1-9 ◽

Cited By ~ 26

Author(s):

Koumei Yazaki ◽

Chinatsu Yoshikoshi ◽

Satoru Oshiro ◽

Sumino Yanase

Keyword(s):

Model Organism ◽

Lifespan Extension ◽

Cell Organelle ◽

Wild Type ◽

Marine Animals ◽

Cellular Protection ◽

C Elegans ◽

Expression Of Genes ◽

Genes Encoding ◽

In The Wild

Astaxanthin (AX), which is produced by some marine animals, is a type of carotenoid that has antioxidative properties. In this study, we initially examined the effects of AX on the aging of a model organismC. elegansthat has the conserved intracellular pathways related to mammalian longevity. The continuous treatments with AX (0.1 to 1 mM) from both the prereproductive and young adult stages extended the mean lifespans by about 16–30% in the wild-type and long-lived mutantage-1ofC. elegans. In contrast, the AX-dependent lifespan extension was not observed even in adaf-16null mutant. Especially, the expression of genes encoding superoxide dismutases and catalases increased in two weeks after hatching, and the DAF-16 protein was translocated to the nucleus in the AX-exposed wild type. These results suggest that AX protects the cell organelle mitochondria and nucleus of the nematode, resulting in a lifespan extension via an Ins/IGF-1 signaling pathway during normal aging, at least in part.

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Expression of β-1,4-galactosyltransferases during Aging in Caenorhabditis elegans

Gerontology ◽

10.1159/000510722 ◽

2020 ◽

Vol 66 (6) ◽

pp. 571-581

Author(s):

Jennifer Kremer ◽

Cornelia Brendel ◽

Elisabeth Karin Maria Mack ◽

Hildegard Isolde Dietlinde Mack

Keyword(s):

Caenorhabditis Elegans ◽

Model Organism ◽

Mrna Levels ◽

Germline Stem Cells ◽

Wild Type ◽

Activity Increase ◽

C Elegans ◽

Targeted Analysis ◽

Age Dependent ◽

Plasma Activity

Background: Altered plasma activity of β-1,4-galactosyltransferases (B4GALTs) is a novel candidate biomarker of human aging. B4GALT1 is assumed to be largely responsible for this activity increase, but how it modulates the aging process is unclear at present. Objectives: To determine how expression of B4GALT1 and other B4GALT enzymes changes during aging of an experimentally tractable model organism, Caenorhabditis elegans. Methods: Targeted analysis of mRNA levels of all 3 C. elegans B4GALT family members was performed by qPCR in wild-type and in long-lived daf-2 (insulin/IGF1-like receptor)-deficient or germline-deficient animals. Results: bre-4 (B4GALT1/2/3/4) is the only B4GALT whose expression increases during aging in wild-type worms. In addition, bre-4 levels also rise during aging in long-lived daf-2-deficient worms, but not in animals that are long-lived due to the lack of germline stem cells. On the other hand, expression of sqv-3 (B4GALT7) and of W02B12.11 (B4GALT5/6) appears decreased or constant, respectively, in all backgrounds during aging. Conclusions: The age-dependent bre-4 mRNA increase in C. elegans parallels the age-dependent B4GALT activity increase in humans and is consistent with C. elegans being a suitable experimental organism to define potentially conserved roles of B4GALT1 during aging.

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Healthspan Enhancement by Olive Polyphenols in C. elegans Wild Type and Parkinson’s Models

International Journal of Molecular Sciences ◽

10.3390/ijms21113893 ◽

2020 ◽

Vol 21 (11) ◽

pp. 3893 ◽

Cited By ~ 24

Author(s):

Gabriele Di Rosa ◽

Giovanni Brunetti ◽

Maria Scuto ◽

Angela Trovato Salinaro ◽

Edward J. Calabrese ◽

...

Keyword(s):

Neurodegenerative Disorder ◽

Model Organism ◽

Full Potential ◽

Wild Type ◽

Motor Impairments ◽

C Elegans ◽

Beneficial Effects ◽

Swim Performance ◽

Polyphenolic Extract ◽

Health Promoting

Parkinson’s disease (PD) is the second most prevalent late-age onset neurodegenerative disorder, affecting 1% of the population after the age of about 60 years old and 4% of those over 80 years old, causing motor impairments and cognitive dysfunction. Increasing evidence indicates that Mediterranean diet (MD) exerts beneficial effects in maintaining health, especially during ageing and by the prevention of neurodegenerative disorders. In this regard, olive oil and its biophenolic constituents like hydroxytyrosol (HT) have received growing attention in the past years. Thus, in the current study we test the health-promoting effects of two hydroxytyrosol preparations, pure HT and Hidrox® (HD), which is hydroxytyrosol in its “natural” environment, in the established invertebrate model organism Caenorhabditis elegans. HD exposure led to much stronger beneficial locomotion effects in wild type worms compared to HT in the same concentration. Consistent to this finding, in OW13 worms, a PD-model characterized by α-synuclein expression in muscles, HD exhibited a significant higher effect on α-synuclein accumulation and swim performance than HT, an effect partly confirmed also in swim assays with the UA44 strain, which features α-synuclein expression in DA-neurons. Interestingly, beneficial effects of HD and HT treatment with similar strength were detected in the lifespan and autofluorescence of wild-type nematodes, in the neuronal health of UA44 worms as well as in the locomotion of rotenone-induced PD-model. Thus, the hypothesis that HD features higher healthspan-promoting abilities than HT was at least partly confirmed. Our study demonstrates that HD polyphenolic extract treatment has the potential to partly prevent or even treat ageing-related neurodegenerative diseases and ageing itself. Future investigations including mammalian models and human clinical trials are needed to uncover the full potential of these olive compounds.

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The Perfect C. ELEGANS Project: An Initial Report

Artificial Life ◽

10.1162/106454698568495 ◽

1998 ◽

Vol 4 (2) ◽

pp. 141-156 ◽

Cited By ~ 9

Author(s):

Hiroaki Kitano ◽

Shugo Hamahashi ◽

Sean Luke

Keyword(s):

Cell Lineage ◽

Model Organism ◽

Soil Nematode ◽

Initial Report ◽

C Elegans ◽

Complete Cell ◽

And Function ◽

Multicellular Organisms ◽

And Behavior ◽

Synthetic Models

The soil nematode Caenorhabditis Elegans (C. elegans) is the most investigated of all multicellular organisms. Since the proposal to use it as a model organism, a series of research projects have been undertaken, investigating various aspects of this organism. As a result, the complete cell lineage, neural circuitry, and various genes and their functions have been identified. The complete C. elegans DNA sequencing and gene expression mapping for each cell at different times during embryogenesis will be identified in a few years. Given the abundance of collected data, we believe that the time is ripe to introduce synthetic models of C. elegans to further enhance our understanding of the underlying principles of its development and behavior. For this reason, we have started the Perfect C. elegans Project, which aims to produce ultimately a complete synthetic model of C. elegans' cellular structure and function. This article describes the goal, the approach, and the initial results of the project.

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High-speed large-scale 4D activities mapping of moving C. elegans by deep-learning-enabled light-field microscopy on a chip

10.1101/2021.01.19.427254 ◽

2021 ◽

Author(s):

Tingting Zhu ◽

Lanxin Zhu ◽

Yi Li ◽

Xiaopeng Chen ◽

Mingyang He ◽

...

Keyword(s):

Deep Learning ◽

High Speed ◽

Large Scale ◽

Light Field ◽

Wild Type ◽

C Elegans ◽

Neural Activities ◽

Biological Studies ◽

Different Types ◽

Field Imaging

We report a novel fusion of microfluidics and light-field microscopy, to achieve high-speed 4D (space + time) imaging of moving C. elegans on a chip. Our approach combines automatic chip-based worm loading / compartmentalization / flushing / reloading with instantaneous deep-learning light-field imaging of moving worm. Taken together, we realized intoto image-based screening of wild-type and uncoordinated-type worms at a volume rate of 33 Hz, with sustained observation of 1 minute per worm, and overall throughput of 42 worms per hour. With quickly yielding over 80000 image volumes that four-dimensionally visualize the dynamics of all the worms, we can quantitatively analyse their behaviours as well as the neural activities, and correlate the phenotypes with the neuron functions. The different types of worms can be readily identified as a result of the high-throughput activity mapping. Our approach shows great potential for various lab-on-a-chip biological studies, such as embryo sorting and cell growth assays.

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Cautionary note on the use of Caenorhabditis elegans to study muscle phenotypes caused by mutations in the human MYH7 gene

BioTechniques ◽

10.2144/btn-2020-0012 ◽

2020 ◽

Vol 68 (6) ◽

pp. 296-299

Author(s):

Alejandro Gil-Gálvez ◽

Pilar Carbonell-Corvillo ◽

Carmen Paradas ◽

Antonio Miranda-Vizuete

Keyword(s):

Caenorhabditis Elegans ◽

Fluorescent Protein ◽

Cardiac Myosin ◽

Wild Type ◽

Cautionary Note ◽

Gene Encoding ◽

C Elegans ◽

Slow Skeletal Muscle ◽

Different Types ◽

Green Fluorescent

Mutations in the human MYH7 gene, encoding a slow skeletal muscle/β-cardiac myosin heavy chain, cause different types of myopathies. The nematode model Caenorhabditis elegans has frequently been employed to study the molecular and physiological consequences of MYH7 mutations in muscle function by introducing mutations into the unc-54 gene, the worm MYH7 ortholog. We report here that the C. elegans model is not appropriate for such studies if they involve expression of the UNC-54 protein (wild-type or fused to green fluorescent protein) above endogenous levels.

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Experimental investigation using micro-PIV of the effect of microRNA-1 deficiency on motility in Caenorhabditis elegans

10.1101/2020.06.16.119396 ◽

2020 ◽

Author(s):

S. Ravikumar ◽

M. Fedrizzi ◽

R. Prabhakar ◽

R. Pocock ◽

M. K. O’Bryan ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Swimming Speed ◽

Model Organism ◽

The Body ◽

Wild Type ◽

Mean Power ◽

C Elegans ◽

Micro Piv ◽

Image Velocimetry ◽

Beating Frequency

AbstractCaenorhabditis elegans is a microscopic nematode used extensively as a model organism in studies of neuromuscular function and neurodegenerative disorders. A mutation in mir-1 affects signalling at the neuromuscular junction. We investigate the effect of this mutation on the propulsive power exerted by nematodes as they grow in size with age. We compare the motility of wild-type and mir-1(gk276) mutant nematodes in a Newtonian fluid using a two-component, two dimensional (2C-2D) Digital Microscopic Particle Image Velocimetry (µ-PIV) technique. Beating amplitudes of the head and tail, the wavelength of undulatory waves and the swimming speed scale linearly with size in both the wild-type and mutant strains. The beating frequency is independent of size or position along the body. Differences in the magnitudes of these kinematic parameters between the two strains, however, grow systematically with age. The swimming speed scales linearly with the wave speed of the neuromuscular undulation in both nematode strains with a conserved ratio. The magnitude of mean power and mean local fluid circulation in the mutant is significantly lower compared to those of the wild-type animals of the same age. This indicates that a mutation in mir-1 adversely affects motility in C. elegans.

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Promoters of the dhs-21 gene encoding dicarbonyl/l-xylulose reductase in Caenorhabditis elegans

Vietnam Journal of Biotechnology ◽

10.15625/1811-4989/15/2/12353 ◽

2018 ◽

Vol 15 (2) ◽

pp. 359-365

Author(s):

Lê Thọ Sơn ◽

Joohong Ahnn ◽

Jeong Hoon Cho ◽

Nguyễn Huy Hoàng

Keyword(s):

Caenorhabditis Elegans ◽

Model Organism ◽

Biological Research ◽

Loss Of Function ◽

Wild Type ◽

C Elegans ◽

Larval Stages ◽

Vital Functions

Dicarbonyl/L-xylulose (DCXR) was identified as a dehydrogenase. This type of enzyme was presented in various forms of lives including bacteria, fungi, plants and animals. Generally, it converts L-xylulose to xylitol in the presence of either cofactor NADH or NADPH in vitro. Previous studies reported the biochemistry properties and crystal structure but largely uncovered biological roles of DCXRs. It was impossible to dissect the functions in mice or human cells that had many DCXR homologs in their genomes. Interestingly, the wild-type Caenorhabditis elegans, a well-known model organism in biological research, has only nuclear genomic dhs-21 that encodes a unique homologous DCXR. Thus Ce.dhs-21 and the host C. elegans were relevant for investigation of the physiologically-vital functions of the DCXR. This research aimed to the expression of dhs-21 in vivo. We defined three promoters , manipulated three relative reporter-constructs that conjugated the dhs-21 gene and Green Flouresent Protein (known as GFP) one. The construct vectors were transferred into wild-type C. elegans N2 and as well as the hermaphroditic loss of function dhs-21(jh129) by microinjection. In the results, we found that the expression pattern of dhs-21 under the only p2-promoter construct was stable and similar to immunogold Electric Microscopy (EM) images. The dhs-21 gene was expressed in both sexes of at all larval stages till the deaths of worms. DHS-21 was expressed in the cytosol of the intestinal, gonad sheath and uterous seam cell (utse).

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