Reproductive Suicide: Similar Mechanisms of Aging in C. elegans and Pacific Salmon

In some species of salmon, reproductive maturity triggers the development of massive pathology resulting from reproductive effort, leading to rapid post-reproductive death. Such reproductive death, which occurs in many semelparous organisms (with a single bout of reproduction), can be prevented by blocking reproductive maturation, and this can increase lifespan dramatically. Reproductive death is often viewed as distinct from senescence in iteroparous organisms (with multiple bouts of reproduction) such as humans. Here we review the evidence that reproductive death occurs in C. elegans and discuss what this means for its use as a model organism to study aging. Inhibiting insulin/IGF-1 signaling and germline removal suppresses reproductive death and greatly extends lifespan in C. elegans, but can also extend lifespan to a small extent in iteroparous organisms. We argue that mechanisms of senescence operative in reproductive death exist in a less catastrophic form in iteroparous organisms, particularly those that involve costly resource reallocation, and exhibit endocrine-regulated plasticity. Thus, mechanisms of senescence in semelparous organisms (including plants) and iteroparous ones form an etiological continuum. Therefore understanding mechanisms of reproductive death in C. elegans can teach us about some mechanisms of senescence that are operative in iteroparous organisms.

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Semelparity and Reproductive Death in Caenorhabditis elegans

10.20944/preprints202011.0019.v1 ◽

2020 ◽

Author(s):

David Gems ◽

Carina Kern ◽

Joseph Nour ◽

Marina Ezcurra

Keyword(s):

Caenorhabditis Elegans ◽

Reproductive Effort ◽

Model Organism ◽

Small Extent ◽

Resource Reallocation ◽

Reproductive Maturity ◽

C Elegans ◽

Reproductive Maturation ◽

Single Bout

In some species of salmon, reproductive maturity triggers the development of massive pathology resulting from reproductive effort, leading to rapid post-reproductive death. Such reproductive death, which occurs in many semelparous organisms (with a single bout of reproduction), can be prevented by blocking reproductive maturation, and this can increase lifespan dramatically. Reproductive death is often viewed as distinct from senescence in iteroparous organisms (with multiple bouts of reproduction) such as humans. Here we review the evidence that reproductive death occurs in C. elegans and discuss what this means for its use as a model organism to study aging. Inhibiting insulin/IGF-1 signaling and germline removal suppresses reproductive death and greatly extends lifespan in C. elegans, but can also extend lifespan to a small extent in iteroparous organisms. We argue that mechanisms of senescence operative in reproductive death exist in a less catastrophic form in iteroparous organisms, particularly those involving costly resource reallocation, and exhibiting endocrine-regulated plasticity. Thus, mechanisms of senescence in semelparous organisms (including plants) and iteroparous ones form an etiological continuum. Therefore understanding mechanisms of reproductive death in C. elegans can teach us about some mechanisms of senescence that are operative in iteroparous organisms.

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C. elegans provide milk for their young

10.1101/2020.11.15.380253 ◽

2020 ◽

Author(s):

Carina C. Kern ◽

StJohn Townsend ◽

Antoine Salzmann ◽

Nigel B. Rendell ◽

Graham W. Taylor ◽

...

Keyword(s):

Sexual Maturity ◽

Reproductive Effort ◽

Pacific Salmon ◽

Resource Transfer ◽

C Elegans ◽

Destructive Process ◽

Severe Pathology ◽

Intestinal Atrophy ◽

Insight Into

AbstractAdult C. elegans hermaphrodites exhibit severe senescent pathology that begins to develop within days of reaching sexual maturity (Ezcurra et al., 2018; Garigan et al., 2002; Herndon et al., 2002; Wang et al., 2018). For example, after depletion of self-sperm, intestinal biomass is converted into yolk leading to intestinal atrophy and yolk steatosis (pseudocoelomic lipoprotein pools, PLPs) (Ezcurra et al., 2018; Garigan et al., 2002; Herndon et al., 2002; Sornda et al., 2019). These senescent pathologies are promoted by insulin/IGF-1 signalling (IIS), which also shortens lifespan (Ezcurra et al., 2018; Kenyon, 2010). This pattern of rapid and severe pathology in organs linked to reproduction is reminiscent of semelparous organisms where massive reproductive effort leads to rapid death (reproductive death) as in Pacific salmon (Finch, 1990; Gems et al., 2020). Moreover, destructive conversion of somatic biomass to support reproduction is a hallmark of reproductive death (Gems et al., 2020). Yet arguing against the occurrence of reproductive death in C. elegans is the apparent futility of post-reproductive yolk production. Here we show that this effort is not futile, since post-reproductive mothers vent yolk through their vulva, which is consumed by progeny and supports their growth; thus vented yolk functions as a milk, and C. elegans mothers exhibit a form of lactation. Moreover, IIS promotes lactation, thereby effecting a costly process of resource transfer from postreproductive mothers to offspring. These results support the view that C. elegans hermaphrodites exhibit reproductive death involving a self-destructive process of lactation that is promoted by IIS. They also provide new insight into how the strongly life-shortening effects of IIS in C. elegans evolved.

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C. elegans hermaphrodites undergo semelparous reproductive death

10.1101/2020.11.16.384255 ◽

2020 ◽

Cited By ~ 1

Author(s):

Carina C. Kern ◽

Shivangi Srivastava ◽

Marina Ezcurra ◽

Nancy Hui ◽

StJohn Townsend ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Sibling Species ◽

Early Onset ◽

Reproductive Effort ◽

Pacific Salmon ◽

Larval Growth ◽

Present Evidence ◽

C Elegans ◽

Species Pairs ◽

Intestinal Atrophy

AbstractAgeing in the nematode Caenorhabditis elegans is unusual in terms of the severity and early onset of senescent pathology, particularly affecting organs involved in reproduction (Ezcurra et al., 2018; Garigan et al., 2002; Herndon et al., 2002). In post-reproductive C. elegans hermaphrodites, intestinal biomass is converted into yolk leading to intestinal atrophy and yolk steatosis (Ezcurra et al., 2018; Sornda et al., 2019). We recently showed that post-reproductive mothers vent yolk which functions as a milk (yolk milk), supporting larval growth that is consumed by larvae (Kern et al., 2020). This form of massive reproductive effort involving biomass repurposing leading to organ degeneration is characteristic of semelparous organisms (i.e. that exhibit only a single reproductive episode) ranging from monocarpic plants to Pacific salmon where it leads to rapid death (reproductive death) (Finch, 1990; Gems et al., 2020). Removal of the germline greatly increases lifespan in both C. elegans and Pacific salmon, in the latter case by suppressing semelparous reproductive death (Hsin and Kenyon, 1999; Robertson, 1961). Here we present evidence that reproductive death occurs in C. elegans, and that it is suppressed by germline removal, leading to extension of lifespan. Comparing three Caenorhabditis sibling species pairs with hermaphrodites and females, we show that lactation and massive early pathology only occurs in the former. In each case, hermaphrodites are shorter lived and only in hermaphrodites does germline removal markedly increase lifespan. Semelparous reproductive death has previously been viewed as distinct from ageing; however, drawing on recent theories of ageing (Blagosklonny, 2006; de Magalhães and Church, 2005; Maklakov and Chapman, 2019), we argue that it involves exaggerated versions of programmatic mechanisms that to a smaller extent contribute to ageing in non-semelparous species. Thus, despite the presence of reproductive death, mechanisms of ageing in C. elegans are informative about ageing in general.

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Health and longevity studies in C. elegans: the “healthy worm database” reveals strengths, weaknesses and gaps of test compound-based studies

Biogerontology ◽

10.1007/s10522-021-09913-2 ◽

2021 ◽

Vol 22 (2) ◽

pp. 215-236

Author(s):

Nadine Saul ◽

Steffen Möller ◽

Francesca Cirulli ◽

Alessandra Berry ◽

Walter Luyten ◽

...

Keyword(s):

Healthy Aging ◽

Model Organism ◽

Research Field ◽

Aging Research ◽

Genetic Manipulations ◽

C Elegans ◽

Starting Point ◽

Health Related ◽

Phenotype Measurement ◽

Or Gene

AbstractSeveral biogerontology databases exist that focus on genetic or gene expression data linked to health as well as survival, subsequent to compound treatments or genetic manipulations in animal models. However, none of these has yet collected experimental results of compound-related health changes. Since quality of life is often regarded as more valuable than length of life, we aim to fill this gap with the “Healthy Worm Database” (http://healthy-worm-database.eu). Literature describing health-related compound studies in the aging model Caenorhabditis elegans was screened, and data for 440 compounds collected. The database considers 189 publications describing 89 different phenotypes measured in 2995 different conditions. Besides enabling a targeted search for promising compounds for further investigations, this database also offers insights into the research field of studies on healthy aging based on a frequently used model organism. Some weaknesses of C. elegans-based aging studies, like underrepresented phenotypes, especially concerning cognitive functions, as well as the convenience-based use of young worms as the starting point for compound treatment or phenotype measurement are discussed. In conclusion, the database provides an anchor for the search for compounds affecting health, with a link to public databases, and it further highlights some potential shortcomings in current aging research.

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Benefits of Using the Invertebrate Model Organism C. Elegans in an Inquiry-Based Laboratory Activity

Teaching of Psychology ◽

10.1177/00986283211029649 ◽

2021 ◽

pp. 009862832110296

Author(s):

Angy J. Kallarackal

Keyword(s):

American Psychological Association ◽

Model Organism ◽

Learning Goals ◽

Research Skills ◽

Final Exam ◽

Laboratory Activity ◽

Writing Ability ◽

C Elegans ◽

Invertebrate Model ◽

Laboratory Experiences

Background: The goals of laboratory experiences include developing knowledge base, research skills, and scientific communication abilities. Objective: The aim was to assess an inquiry-based laboratory activity using the model organism Caenorhabditis elegans in relation to learning goals. Method: Students in a Biopsychology laboratory course worked in groups to test the effect of various drugs (e.g., nicotine, ethanol, fluoxetine, and melatonin) on C. elegans behavior. The activity included literature review, experimental design, and a final lab report. A cumulative final exam included a synaptic communication question related to the content of the activity. Results: Students showed better retention of laboratory-related content compared to other topics from the course, as demonstrated through performance on the final exam and were able to replicate previous research demonstrating effects of drug on locomotion. However, students did not improve writing ability compared to performance on a previous American Psychological Association style lab report. Conclusion: This study demonstrates that using a student-designed, multi-week laboratory assignment in an undergraduate Biopsychology course supports the growth of psychology knowledge and the development of research skills. Teaching Implications: Instructors should consider using the described laboratory activity for biopsychology or behavioral neuroscience classes or consider similarly designed laboratory formats for other courses in Psychology.

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Wormicloud: a new text summarization tool based on word clouds to explore the C. elegans literature

Database ◽

10.1093/database/baab015 ◽

2021 ◽

Vol 2021 ◽

Author(s):

Valerio Arnaboldi ◽

Jaehyoung Cho ◽

Paul W Sternberg

Keyword(s):

Search Engines ◽

Complex Structure ◽

Model Organism ◽

Gene Interaction ◽

Relevant Information ◽

Biomedical Literature ◽

C Elegans ◽

Word Clouds ◽

Scientific Papers ◽

Model Organism Databases

Abstract Finding relevant information from newly published scientific papers is becoming increasingly difficult due to the pace at which articles are published every year as well as the increasing amount of information per paper. Biocuration and model organism databases provide a map for researchers to navigate through the complex structure of the biomedical literature by distilling knowledge into curated and standardized information. In addition, scientific search engines such as PubMed and text-mining tools such as Textpresso allow researchers to easily search for specific biological aspects from newly published papers, facilitating knowledge transfer. However, digesting the information returned by these systems—often a large number of documents—still requires considerable effort. In this paper, we present Wormicloud, a new tool that summarizes scientific articles in a graphical way through word clouds. This tool is aimed at facilitating the discovery of new experimental results not yet curated by model organism databases and is designed for both researchers and biocurators. Wormicloud is customized for the Caenorhabditis elegans literature and provides several advantages over existing solutions, including being able to perform full-text searches through Textpresso, which provides more accurate results than other existing literature search engines. Wormicloud is integrated through direct links from gene interaction pages in WormBase. Additionally, it allows analysis on the gene sets obtained from literature searches with other WormBase tools such as SimpleMine and Gene Set Enrichment. Database URL: https://wormicloud.textpressolab.com

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Behavioral Effects of Volatile Anesthetics in Caenorhabditis elegans

Anesthesiology ◽

10.1097/00000542-199610000-00027 ◽

1996 ◽

Vol 85 (4) ◽

pp. 901-912 ◽

Cited By ~ 38

Author(s):

Michael C. Crowder ◽

Laynie D. Shebester ◽

Tim Schedl

Keyword(s):

Nervous System ◽

Caenorhabditis Elegans ◽

Time Course ◽

Model Organism ◽

Volatile Anesthetic ◽

Volatile Anesthetics ◽

Effective Concentration ◽

Forward Genetics ◽

C Elegans ◽

Median Effective Concentration

Background The nematode Caenorhabditis elegans offers many advantages as a model organism for studying volatile anesthetic actions. It has a simple, well-understood nervous system; it allows the researcher to do forward genetics; and its genome will soon be completely sequenced. C. elegans is immobilized by volatile anesthetics only at high concentrations and with an unusually slow time course. Here other behavioral dysfunctions are considered as anesthetic endpoints in C. elegans. Methods The potency of halothane for disrupting eight different behaviors was determined by logistic regression of concentration and response data. Other volatile anesthetics were also tested for some behaviors. Established protocols were used for behavioral endpoints that, except for pharyngeal pumping, were set as complete disruption of the behavior. Time courses were measured for rapid behaviors. Recovery from exposure to 1 or 4 vol% halothane was determined for mating, chemotaxis, and gross movement. All experiments were performed at 20 to 22 degrees C. Results The median effective concentration values for halothane inhibition of mating (0.30 vol%-0.21 mM), chemotaxis (0.34 vol%-0.24 mM), and coordinated movement (0.32 vol% - 0.23 mM) were similar to the human minimum alveolar concentration (MAC; 0.21 mM). In contrast, halothane produced immobility with a median effective concentration of 3.65 vol% (2.6 mM). Other behaviors had intermediate sensitivities. Halothane's effects reached steady-state in 10 min for all behaviors tested except immobility, which required 2 h. Recovery was complete after exposure to 1 vol% halothane but was significantly reduced after exposure to immobilizing concentrations. Conclusions Volatile anesthetics selectively disrupt C. elegans behavior. The potency, time course, and recovery characteristics of halothane's effects on three behaviors are similar to its anesthetic properties in vertebrates. The affected nervous system molecules may express structural motifs similar to those on vertebrate anesthetic targets.

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Mask R-CNN Based C. Elegans Detection with a DIY Microscope

Biosensors ◽

10.3390/bios11080257 ◽

2021 ◽

Vol 11 (8) ◽

pp. 257

Author(s):

Sebastian Fudickar ◽

Eike Jannik Nustede ◽

Eike Dreyer ◽

Julia Bornhorst

Keyword(s):

Cell Biology ◽

High Throughput Screening ◽

Low Cost ◽

Image Acquisition ◽

Rapid Development ◽

Model Organism ◽

Large Data ◽

Data Set ◽

C Elegans ◽

Do It Yourself

Caenorhabditis elegans (C. elegans) is an important model organism for studying molecular genetics, developmental biology, neuroscience, and cell biology. Advantages of the model organism include its rapid development and aging, easy cultivation, and genetic tractability. C. elegans has been proven to be a well-suited model to study toxicity with identified toxic compounds closely matching those observed in mammals. For phenotypic screening, especially the worm number and the locomotion are of central importance. Traditional methods such as human counting or analyzing high-resolution microscope images are time-consuming and rather low throughput. The article explores the feasibility of low-cost, low-resolution do-it-yourself microscopes for image acquisition and automated evaluation by deep learning methods to reduce cost and allow high-throughput screening strategies. An image acquisition system is proposed within these constraints and used to create a large data-set of whole Petri dishes containing C. elegans. By utilizing the object detection framework Mask R-CNN, the nematodes are located, classified, and their contours predicted. The system has a precision of 0.96 and a recall of 0.956, resulting in an F1-Score of 0.958. Considering only correctly located C. elegans with an [email protected] IoU, the system achieved an average precision of 0.902 and a corresponding F1 Score of 0.906.

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Stochastic left–right neuronal asymmetry in Caenorhabditis elegans

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2015.0407 ◽

2016 ◽

Vol 371 (1710) ◽

pp. 20150407 ◽

Cited By ~ 16

Author(s):

Amel Alqadah ◽

Yi-Wen Hsieh ◽

Rui Xiong ◽

Chiou-Fen Chuang

Keyword(s):

Caenorhabditis Elegans ◽

Molecular Mechanisms ◽

Neurological Diseases ◽

Calcium Signalling ◽

Model Organism ◽

Brain Asymmetry ◽

C Elegans ◽

Left And Right ◽

Left Right Asymmetry ◽

Neuronal Asymmetry

Left–right asymmetry in the nervous system is observed across species. Defects in left–right cerebral asymmetry are linked to several neurological diseases, but the molecular mechanisms underlying brain asymmetry in vertebrates are still not very well understood. The Caenorhabditis elegans left and right amphid wing ‘C’ (AWC) olfactory neurons communicate through intercellular calcium signalling in a transient embryonic gap junction neural network to specify two asymmetric subtypes, AWC OFF (default) and AWC ON (induced), in a stochastic manner. Here, we highlight the molecular mechanisms that establish and maintain stochastic AWC asymmetry. As the components of the AWC asymmetry pathway are highly conserved, insights from the model organism C. elegans may provide a window onto how brain asymmetry develops in humans. This article is part of the themed issue ‘Provocative questions in left–right asymmetry’.

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