scholarly journals Embryonic Methamphetamine Exposure Inhibits Methamphetamine Cue Conditioning and Reduces Dopamine Concentrations in Adult N2 Caenorhabditis elegans

2016 ◽  
Vol 38 (2) ◽  
pp. 139-149 ◽  
Author(s):  
Simon N. Katner ◽  
Bethany S. Neal-Beliveau ◽  
Eric A. Engleman
Keyword(s):  
Caenorhabditis Elegans ◽  
Chloride Ions ◽  
Well Test ◽  
Long Term Effects ◽  
Liquid Filtration ◽  
C Elegans ◽  
Embryonic Exposure ◽  
Conditioning Data ◽  
Food Conditioning

Methamphetamine (MAP) addiction is substantially prevalent in today's society, resulting in thousands of deaths and costing billions of dollars annually. Despite the potential deleterious consequences, few studies have examined the long-term effects of embryonic MAP exposure. Using the invertebrate nematode Caenorhabditis elegans allows for a controlled analysis of behavioral and neurochemical changes due to early developmental drug exposure. The objective of the current study was to determine the long-term behavioral and neurochemical effects of embryonic exposure to MAP in C. elegans. In addition, we sought to improve our conditioning and testing procedures by utilizing liquid filtration, as opposed to agar, and smaller, 6-well testing plates to increase throughput. Wild-type N2 C. elegans were embryonically exposed to 50 μM MAP. Using classical conditioning, adult-stage C. elegans were conditioned to MAP (17 and 500 μM) in the presence of either sodium ions (Na+) or chloride ions (Cl-) as conditioned stimuli (CS+/CS-). Following conditioning, a preference test was performed by placing worms in 6-well test plates spotted with the CS+ and CS- at opposite ends of each well. A preference index was determined by counting the number of worms in the CS+ target zone divided by the total number of worms in the CS+ and CS- target zones. A food conditioning experiment was also performed in order to determine whether embryonic MAP exposure affected food conditioning behavior. For the neurochemical experiments, adult worms that were embryonically exposed to MAP were analyzed for dopamine (DA) content using high-performance liquid chromatography. The liquid filtration conditioning procedure employed here in combination with the use of 6-well test plates significantly decreased the time required to perform these experiments and ultimately increased throughput. The MAP conditioning data found that pairing an ion with MAP at 17 or 500 μM significantly increased the preference for that ion (CS+) in worms that were not pre-exposed to MAP. However, worms embryonically exposed to MAP did not exhibit significant drug cue conditioning. The inability of MAP-exposed worms to condition to MAP was not associated with deficits in food conditioning, as MAP-exposed worms exhibited a significant cue preference associated with food. Furthermore, our results found that embryonic MAP exposure reduced DA levels in adult C. elegans, which could be a key mechanism contributing to the long-term effects of embryonic MAP exposure. It is possible that embryonic MAP exposure may be impairing the ability of C. elegans to learn associations between MAP and the CS+ or inhibiting the reinforcing properties of MAP. However, our food conditioning data suggest that MAP-exposed animals can form associations between cues and food. The depletion of DA levels during embryonic exposure to MAP could be responsible for driving either of these processes during adulthood.

Caenorhabditis elegans Learning and Memory

2019 ◽  
Author(s):  
James S.H. Wong ◽  
Catharine H. Rankin
Keyword(s):  
Carbon Dioxide ◽  
Caenorhabditis Elegans ◽  
Classical Conditioning ◽  
Learning And Memory ◽  
Long Term Memory ◽  
Context Conditioning ◽  
Term Memory ◽  
C Elegans

The nematode, Caenorhabditis elegans (C. elegans), is an organism useful for the study of learning and memory at the molecular, cellular, neural circuitry, and behavioral levels. Its genetic tractability, transparency, connectome, and accessibility for in vivo cellular and molecular analyses are a few of the characteristics that make the organism such a powerful system for investigating mechanisms of learning and memory. It is able to learn and remember across many sensory modalities, including mechanosensation, chemosensation, thermosensation, oxygen sensing, and carbon dioxide sensing. C. elegans habituates to mechanosensory stimuli, and shows short-, intermediate-, and long-term memory, and context conditioning for mechanosensory habituation. The organism also displays chemotaxis to various chemicals, such as diacetyl and sodium chloride. This behavior is associated with several forms of learning, including state-dependent learning, classical conditioning, and aversive learning. C. elegans also shows thermotactic learning in which it learns to associate a particular temperature with the presence or absence of food. In addition, both oxygen preference and carbon dioxide avoidance in C. elegans can be altered by experience, indicating that they have memory for the oxygen or carbon dioxide environment they were reared in. Many of the genes found to underlie learning and memory in C. elegans are homologous to genes involved in learning and memory in mammals; two examples are crh-1, which is the C. elegans homolog of the cAMP response element-binding protein (CREB), and glr-1, which encodes an AMPA glutamate receptor subunit. Both of these genes are involved in long-term memory for tap habituation, context conditioning in tap habituation, and chemosensory classical conditioning. C. elegans offers the advantage of having a very small nervous system (302 neurons), thus it is possible to understand what these conserved genes are doing at the level of single identified neurons. As many mechanisms of learning and memory in C. elegans appear to be similar in more complex organisms including humans, research with C. elegans aids our ever-growing understanding of the fundamental mechanisms of learning and memory across the animal kingdom.

Long-term sediment exposure to ZnO nanoparticles induces oxidative stress in Caenorhabditis elegans

2019 ◽  
Vol 6 (8) ◽  
pp. 2602-2614 ◽  
Author(s):  
Chi-Wei Huang ◽  
Shang-Wei Li ◽  
Vivian Hsiu-Chuan Liao
Keyword(s):  
Oxidative Stress ◽  
Transcription Factor ◽  
Caenorhabditis Elegans ◽  
Zno Nanoparticles ◽  
Gene Activation ◽  
Benthic Organism ◽  
Zno Nps ◽  
C Elegans ◽  
Sediment Exposure

Long-term sediment exposure to ZnO-NPs induces oxidative stress in benthic organism C. elegans which is mediated by the transcription factor DAF-16/FOXO triggering stress-responsive gene activation.

scholarly journals Salmonella biofilms program innate immunity for persistence in Caenorhabditis elegans

2019 ◽  
Vol 116 (25) ◽  
pp. 12462-12467 ◽  
Author(s):  
Stuti K. Desai ◽  
Anup Padmanabhan ◽  
Sharvari Harshe ◽  
Ronen Zaidel-Bar ◽  
Linda J. Kenney
Keyword(s):  
Caenorhabditis Elegans ◽  
Temporal Dynamics ◽  
Innate Immune ◽  
Heterologous Host ◽  
C Elegans ◽  
Parasitic Lifestyle ◽  
Induced Changes ◽  
Infectious Form

The adaptive in vivo mechanisms underlying the switch in Salmonella enterica lifestyles from the infectious form to a dormant form remain unknown. We employed Caenorhabditis elegans as a heterologous host to understand the temporal dynamics of Salmonella pathogenesis and to identify its lifestyle form in vivo. We discovered that Salmonella exists as sessile aggregates, or in vivo biofilms, in the persistently infected C. elegans gut. In the absence of in vivo biofilms, Salmonella killed the host more rapidly by actively inhibiting innate immune pathways. Regulatory cross-talk between two major Salmonella pathogenicity islands, SPI-1 and SPI-2, was responsible for biofilm-induced changes in host physiology during persistent infection. Thus, biofilm formation is a survival strategy in long-term infections, as prolonging host survival is beneficial for the parasitic lifestyle.

Caenorhabditis elegans utilizes dauer pheromone biosynthesis to dispose of toxic peroxisomal fatty acids for cellular homoeostasis

2009 ◽  
Vol 422 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Hyoe-Jin Joo ◽  
Yong-Hyeon Yim ◽  
Pan-Young Jeong ◽  
You-Xun Jin ◽  
Jeong-Eui Lee ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Caenorhabditis Elegans ◽  
Fatty Acyl ◽  
Pheromone Biosynthesis ◽  
Side Chain ◽  
Term Survival ◽  
Developmental Defects ◽  
C Elegans ◽  
Massive Accumulation

Caenorhabditis elegans excretes a dauer pheromone or daumone composed of ascarylose and a fatty acid side chain, the perception of which enables worms to enter the dauer state for long-term survival in an adverse environment. During the course of elucidation of the daumone biosynthetic pathway in which DHS-28 and DAF-22 are involved in peroxisomal β-oxidation of VLCFAs (very long-chain fatty acids), we sought to investigate the physiological consequences of a deficiency in daumone biosynthesis in C. elegans. Our results revealed that two mutants, dhs-28(tm2581) and daf-22(ok693), lacked daumones and thus were dauer defective; this coincided with massive accumulation of fatty acyl-CoAs (up to 100-fold) inside worm bodies compared with levels in wild-type N2 worms. Furthermore, the deficiency in daumone biosynthesis and the massive accumulation of fatty acids and their acyl-CoAs caused severe developmental defects with reduced life spans (up to 30%), suggesting that daumone biosynthesis is be an essential part of C. elegans homoeostasis, affecting survival and maintenance of optimal physiological conditions by metabolizing some of the toxic non-permissible peroxisomal VLCFAs from the worm body in the form of readily excretable daumones.

Cryopreservation produces limited long-term effects on the nematode Caenorhabditis elegans

Cryobiology ◽  
2020 ◽  
Vol 92 ◽  
pp. 86-91
Author(s):  
J.J. Stastna ◽  
A.D. Yiapanas ◽  
A.A. Mandawala ◽  
K.E. Fowler ◽  
S.C. Harvey
Keyword(s):  
Caenorhabditis Elegans ◽  
Long Term Effects ◽  
Nematode Caenorhabditis Elegans

scholarly journals Muscle and epidermal contributions of the structural protein β-spectrin promote hypergravity-induced motor neuron axon defects in C. elegans

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Saraswathi S. Kalichamy ◽  
Alfredo V. Alcantara ◽  
Ban-Seok Kim ◽  
Junsoo Park ◽  
Kyoung-hye Yoon ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Motor Neuron ◽  
Motor Neurons ◽  
High Gravity ◽  
Axon Pathfinding ◽  
Structural Protein ◽  
Long Term Effects ◽  
C Elegans ◽  
Migration Pathways

AbstractBiology is adapted to Earth’s gravity force, and the long-term effects of varying gravity on the development of animals is unclear. Previously, we reported that high gravity, called hypergravity, increases defects in the development of motor neuron axons in the nematode Caenorhabditis elegans. Here, we show that a mutation in the unc-70 gene that encodes the cytoskeletal β-spectrin protein suppresses hypergravity-induced axon defects. UNC-70 expression is required in both muscle and epidermis to promote the axon defects in high gravity. We reveal that the location of axon defects is correlated to the size of the muscle cell that the axon traverses. We also show that mutations that compromise key proteins of hemidesmosomal structures suppress hypergravity-induced axon defects. These hemidesmosomal structures play a crucial role in coupling mechanical force between the muscle, epidermis and the external cuticle. We speculate a model in which the rigid organization of muscle, epidermal and cuticular layers under high gravity pressure compresses the narrow axon migration pathways in the extracellular matrix hindering proper axon pathfinding of motor neurons.

Identifying sources of D-serine in Caenorhabditis elegans and their impact on behavior

2021 ◽  
Author(s):  
Tian A. Qiu ◽  
Harvey M. Andersen ◽  
Nissa J. Larson ◽  
Nathan E. Schroeder ◽  
Jonathan V. Sweedler
Keyword(s):  
Caenorhabditis Elegans ◽  
Sequence Similarity ◽  
Serine Racemase ◽  
Behavioral Changes ◽  
C Elegans ◽  
Aspartate Receptor ◽  
Two Factors ◽  
Locomotion Behavior ◽  
Culturing Conditions

Free D-serine (D-Ser) is a potent co-agonist of the N-methyl-D-aspartate receptor (NMDAR) in glutamate neurotransmission and regulates NMDAR functions in the nervous system. Serine racemases convert L-serine to D-Ser and are believed to be the major source of D-Ser in animals. In Caenorhabditis elegans, a knockout of the serine racemase serr-1 results in behavioral changes, but the level of D-Ser is unaffected. By growing C. elegans on peptone-free nematode growth medium (PF-NGM), we delineated the sources of D-Ser, both exogenous from peptone in culturing media and endogenous from the serine racemase serr-1, and a potential serine/aspartate racemase candidate, Y51H7C.9, identified by sequence similarity network analysis. We also discovered a new serine dehydratase (aka serine ammonia-lyase), K01C8.1, in C. elegans. We identified the serr-1 knockout and PF-NGM culturing conditions as two independent factors that impact C. elegans locomotion behavior after off-food, both short-term and long-term, and no interactions were found between the two factors.

scholarly journals Effects of sub-lethal teratogen exposure during larval development on egg laying and egg quality in adult Caenorhabditis elegans

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 2925 ◽  
Author(s):  
Alexis Killeen ◽  
Caralina Marin de Evsikova
Keyword(s):  
Caenorhabditis Elegans ◽  
Larval Development ◽  
Early Development ◽  
Low Dose ◽  
Egg Quality ◽  
Egg Laying ◽  
High Dose ◽  
Long Term Effects ◽  
Embryo Viability

Background: Acute high dose exposure to teratogenic chemicals alters the proper development of an embryo leading to infertility, impaired fecundity, and few viable offspring. However, chronic exposure to sub-toxic doses of teratogens during early development may also have long-term impacts on egg quality and embryo viability. Methods: To test the hypothesis that low dose exposure during early development can impact long-term reproductive health, Caenorhabditis elegans larvae were exposed to 10 teratogens during larval development, and subsequently were examined for the pattern of egg-laying and egg quality (hatched larvae and embryo viability) as gravid adults. After the exposure, adult gravid worms were transferred to untreated plates and the numbers of eggs laid were recorded every 3 hours, and the day following exposure the numbers of hatched larvae were counted. Results: While fecundity and fertility were typically impaired by teratogens, unexpectedly, many teratogens initially increased egg-laying at the earliest interval compared to control but not at later intervals. However, egg quality, as assessed by embryo viability, remained the same because many of the eggs (<50%) did not hatch. Conclusions: Chronic, low dose exposures to teratogens during early larval development have subtle, long-term effects on egg laying and egg quality.

Ovarian Dysfunction in Fetally Irradiated Beagles

1977 ◽  
Vol 35 ◽  
pp. 658-659
Author(s):  
T. M. Seed ◽  
M. H. Sanderson ◽  
D. L. Gutzeit ◽  
T. E. Fritz ◽  
D. V. Tolle ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Low Dose ◽  
Long Term Effects ◽  
Ovarian Dysfunction ◽  
Dose Rates ◽  
Highly Sensitive ◽  
Microscopic Evaluation ◽  
Ovarian Pathology ◽  
Normal Offspring

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.

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