Esther Marza et al. (2007) International Worm Meeting "Polyunsaturated fatty acids regulate synaptic vesicle endocytosis."

David Hall, Toni Long, Giovanni Lesa, Esther Marza

[International Worm Meeting, 2007]

Long chain polyunsaturated fatty acids (PUFAs), fatty acids with several double bonds, are highly enriched in synaptic vesicles and presynaptic plasma membranes, but their precise functions remain unknown. To clarify their role in neurotransmission, we generated C. elegans strains depleted of PUFAs by inactivating the gene fat-3, which encodes an enzyme essential for PUFA biosynthesis. We demonstrated that fat-3 mutants release abnormally low levels of acetylcholine and serotonin at neuromuscular junctions resulting in impaired locomotion and have an abnormally low number of synaptic vesicles at presynaptic terminals. This reduction in synaptic vesicles is unlikely to be caused by a defect in synaptic vesicle fusion, since synaptic vesicles docked to presynaptic membranes are abnormally low in fat-3 mutants. Instead, synaptic vesicle depletion could be caused by insufficient synaptic vesicle biogenesis in the neuronal cell body, defective transport of vesicles down the axon, and/or impaired recycling of synaptic vesicle components at presynaptic sites. We have now investigated the reasons of synaptic vesicle depletion in fat-3 mutants. The absence of PUFAs does not detectably affect the biosynthesis or the transport of synaptic vesicle components from neuronal cell bodies to presynaptic sites. However, PUFA-depleted animals display defects consistent with impaired synaptic vesicle recycling. First, the synaptic vesicle component synaptobrevin/VAMP is not retrieved efficiently after synaptic vesicles fuse with the presynaptic plasma membrane. Second, in fat-3 mutants we observed abnormally large endosomal-like compartments and synaptic vesicles at presynaptic terminals. The impaired locomotion as well as the defective retrieval of synaptobrevin from the plasma membrane are rescued by providing exogenous PUFAs to fat-3 mutants. Our results suggest that PUFAs are required for efficient synaptic vesicle recycling. We propose that PUFAs regulate synaptic vesicle recycling by enabling the correct localization or by modulating the function of proteins required for synaptic vesicle endocytosis.

Rose JK et al. (2002) Learn Mem "A new group-training procedure for habituation demonstrates that presynaptic glutamate release contributes to long-term memory in Caenorhabditis elegans."

Kaun KR, Rankin CH, Rose JK

[Learn Mem, 2002]

In the experiments reported here we have developed a new group-training protocol for assessing long-term memory for habituation in Caenorhabditis elegans. We have replicated all of the major findings of the original single-worm protocol using the new protocol: (1) distributed training produced long-term retention of training, massed training did not; (2) distributed training at long interstimulus intervals (ISIs) produced long-term retention, short ISIs did not; and (3) long-term memory for distributed training is protein synthesis-dependent as it could be blocked by heat shock during the inter-block interval. In addition, we have shown that long-term memory for habituation is graded, depending on the number of blocks of stimuli in training. The inter-block interval must be >40 min for long-term retention of training to occur. Finally, we have tested long-term memory for habituation training in a strain of worms with a mutation in a vesicular glutamate transporter in the sensory neurons that transduce tap (eat-4). The results from these eat-4 worms indicate that glutamate release from the sensory neurons has an important role in the formation of long-term memory ror habituation.

Beck CDO et al. (1997) Anim Learn Behav "Long-term habituation is produced by distributed training at long ISIs and not by massed training or short ISIs in Caenorhabditis elegans."

Beck CDO, Rankin CH

[Anim Learn Behav, 1997]

To begin an investigation of the cellular processes that underlie long-term memory in the nematode Caenorhabditis elegans, it is first necessary to determine that C. elegans is capable of retention over 24 h, and to investigate the factors that may influence the expression of long-term memory. In the present study, the effects of stimuli number, interstimulus interval (ISI), and training procedure on longterm retention of habituation were tested in C. elegans. At a long (60-sec) ISI, distributed training sessions produced long-term habituation retained for 24 h, whereas massed training sessions or training with few stimuli did not. When training was performed at a short (10-sec) ISI, long-term habituation was not detectable with testing at either a 10- or a 60-sec ISI. The long-term habituation observed after distributed training sessions at a 60-sec ISI was consistently expressed when the training procedures were varied. Thus it is clear that C. elegans can reliably express long-term retention for distributed training sessions at a 60-sec ISI, making the system a candidate for further investigations into the cellular processes supporting memory.

Huawei Weng et al. (2005) International Worm Meeting "A web-based searchable image database for C.elegans anatomy."

Huawei Weng, Toni Long, Erik Hyrkas, David H Hall, Tylon Stephney

[International Worm Meeting, 2005]

The Center for C. elegans Anatomy holds an archive of over 200,000 electron micrographs generated by the C. elegans community over the last 30 years including those used in such landmark studies as the reconstruction of the hermaphrodite *(White et al., 1986; Hall et al., 1991). We have been developing a digital image database that will make this material readily available to the community at large. This web-based searchable database will allow C.elegans researchers to efficiently retrieve high resolution TEM images (and later, images from other types of microscopy) over internet. We are using MySQL as a relational database management system, and JAVA, Java Server Page (JSP) and Java Database Connectivity(JDBC) technology to develop the data access and web interface layers. We are scanning archival prints and negatives for wild type and mutants at various magnifications and covering most tissues. Image database features include: 1.Advanced search tools let the user choose an image by creating a query to the database according to sex, age, genotype, body region and tissue type. 2. A browse list that sorts the retrieved images by age, body region and worm name. 3. For each image there are three sizes and associated archival data such as source, age, genotype, fixation method, microscopy method, tissue type, color code etc. stored in the database. Thus the user can scan thumbnails, inspect a medium resolution view, or assess the archival data before downloading the highest resolution image. 4. Data sharing function: an online feedback form allows the user to add their own comments for an individual image; if the user chooses to make it public, comments will be posted as added archival data for that image; alternately they can save it as private with limited access to a selected audience. The project is part of Wormatlas: http://www.wormatlas.org and is supported by NIH RR 12596. *We are grateful for donation of many images from MRC/LMB, U. Wisconsin, U. Missouri, Mt. Sinai Res. Institute, Caltech and others. We welcome further donations of EM images from wild type and mutant studies to our collection.

Esther Marza et al. (2008) European Worm Meeting "Polyunsaturated fatty acids regulate synaptic vesicle endocytosis by modulating synaptojanin localization"

Giovanni M Lesa, Toni Long, Esther Marza, Stefan Eimer, David H Hall, Adolfo Saiardi

[European Worm Meeting, 2008]

Long chain polyunsaturated fatty acids (LC-PUFAs), fatty acids with several. double bonds and more than 18 C, are highly enriched in synaptic membranes,. including synaptic vesicles, but their precise functions at nerve terminals. remain unknown. To clarify their role in neurotransmission, we generated C.. elegans strains depleted of LC-PUFAs by mutating the gene fat-3, which. encodes D6-desaturase, an enzyme essential for LC-PUFAs biosynthesis. fat-3. mutants release abnormally low levels of serotonin and acetylcholine at. neuromuscular junctions (thus causing an uncoordinated phenotype), and are. severely depleted of synaptic vesicles at presynaptic sites.. We have investigated the mechanisms underlying the depletion of synaptic. vesicles observed in LC-PUFA-deficient fat-3 mutants. Our results suggest. that the depletion of synaptic vesicles and the defects in neurotransmitter. release are caused by an impairment in synaptic vesicles recycling. First,. the synaptic vesicles protein synaptobrevin is not efficiently recycled. after synaptic vesicles fuse with the presynaptic membrane. Second,. presynaptic terminals contain enlarged synaptic vesicles as well as. abnormally large endosomal-like compartments. Third, fat-3 mutants have. severely reduced levels of the phosphoinositide phosphatase synaptojanin. and accumulate its main substrate, phosphatidylinositol 4,5-bisphosphate,. at release sites. Fourth fat-3 and synaptojanin act in the same genetic. pathway to retrieve synaptobrevin from the presynaptic plasma membrane.. Fifth, exogenous LC-PUFAs restored normal synaptojanin levels at sites of. release as well as normal synaptobrevin recycling, indicating that the. endocytosis defect is caused by LC-PUFA depletion. We therefore propose. that LC-PUFAs are required for efficient synaptic vesicle recycling by. controllinfluencingmodulating synaptojanin localization at sites of. neurotransmitter release.

Briga M et al. (2015) Exp Gerontol "What can long-lived mutants tell us about mechanisms causing ageing and lifespan variation in natural environments?"

Verhulst S, Briga M

[Exp Gerontol, 2015]

Long-lived mutants of model organisms have brought remarkable progress in our understanding of ageing mechanisms. However, long-lived mutants are usually maintained in optimal standardized laboratory environments (SLEs), and it is not obvious to what extent insights from long-lived mutants in SLEs can be generalized to more natural environments. To address this question we reviewed experiments that compared the fitness and lifespan advantage of long-lived mutants relative to their wild type controls in SLEs and more challenging environments. In competition experiments over multiple generations, the long-lived mutants had a lower fitness relative to wild type controls, and this disadvantage was clearest when the environment included natural challenges such as limited food (N=6 studies ranging from yeast to mice). It is well known that most long-lived mutants have impaired reproduction, which provides one reason for the fitness disadvantage. However, based on 12 experiments in various model organisms such as the nematode worm C. elegans, the fruitfly D. melanogaster and the mouse Mus musculus, we found that the lifespan advantage of long-lived mutants is diminished in more challenging environments, often to the extent that the wild type controls outlive the long-lived mutants. Thus, it appears that information on ageing mechanisms obtained from long-lived mutants in SLEs may be specific to such environments, because those same mechanisms do not extend lifespan in more natural environments. This suggests that different mechanisms cause variation in ageing and lifespan in SLEs compared to natural populations.

Lee Lau H et al. (2013) Genes Brain Behav "Genetic dissection of memory for associative and non-associative learning in Caenorhabditis elegans."

Mahmoud R, Lee Lau H, Timbers TA, Rankin CH

[Genes Brain Behav, 2013]

The distinction between non-associative and associative forms of learning has historically been based on the behavioral training paradigm. Through discovering the molecular mechanisms that mediate learning, we can develop a deeper understanding of the relationships between different forms of learning. Here, we genetically dissect short- and long-term memory for a non-associative form of learning, habituation and an associative form of learning, context conditioning for habituation, in the nematode Caenorhabditis elegans. In short-term chemosensory context conditioning for habituation, worms trained and tested in the presence of either a taste (sodium acetate) or smell (diacetyl) context cue show greater retention of habituation to tap stimuli when compared with animals trained and tested without a salient cue. Long-term memory for olfactory context conditioning was observed 24 h after a training procedure that does not normally induce 24 h memory. Like long-term habituation, this long-term memory was dependent on the transcription factor cyclic AMP-response element-binding protein. Worms with mutations in glr-1 [a non-N-methyl-d-aspartate (NMDA)-type glutamate receptor subunit] showed short-term but not long-term habituation or short- or long-term context conditioning. Worms with mutations in nmr-1 (an NMDA-receptor subunit) showed normal short- and long-term memory for habituation but did not show either short- or long-term context conditioning. Rescue of nmr-1 in the RIM interneurons rescued short- and long-term olfactory context conditioning leading to the hypothesis that these interneurons function to integrate information from chemosensory and mechanosensory systems for associative learning.

Zagoriy V et al. (2010) Chem Biodivers "Long-chain O-ascarosyl-alkanediols are constitutive components of Caenorhabditis elegans but do not induce dauer larva formation."

Matyash V, Zagoriy V, Kurzchalia T

[Chem Biodivers, 2010]

Two long-chain ascarosides, O-ascarosylnonacosane-2,28-diol and O-ascarosyluntriacontane-2,30-diol, were isolated from Caenorhabditis elegans and detected in all developmental stages of the worm. The long-chain ascarosides were shown to be minor lipid components, and it was also shown that they do not induce dauer larva formation.

Rose JK et al. (2022) Front Behav Neurosci "Neuroligin Plays a Role in Ethanol-Induced Disruption of Memory and Corresponding Modulation of Glutamate Receptor Expression."

Lin CHS, Butterfield M, Rankin CH, Rose JK, Liang J, Parvand M

[Front Behav Neurosci, 2022]

Exposure to alcohol causes deficits in long-term memory formation across species. Using a long-term habituation memory assay in Caenorhabditis elegans, the effects of ethanol on long-term memory (> 24 h) for habituation were investigated. An impairment in long-term memory was observed when animals were trained in the presence of ethanol. Cues of internal state or training context during testing did not restore memory. Ethanol exposure during training also interfered with the downregulation of AMPA/KA-type glutamate receptor subunit (GLR-1) punctal expression previously associated with long-term memory for habituation in C. elegans. Interestingly, ethanol exposure alone had the opposite effect, increasing GLR-1::GFP punctal expression. Worms with a mutation in the C. elegans ortholog of vertebrate neuroligins (nlg-1) were resistant to the effects of ethanol on memory, as they displayed both GLR-1::GFP downregulation and long-term memory for habituation after training in the presence of ethanol. These findings provide insights into the molecular mechanisms through which alcohol consumption impacts memory.

Rose JK et al. (2003) J Neurosci "GLR-1, a non-NMDA glutamate receptor homolog, is critical for long-term memory in Caenorhabditis elegans."

Rose JK, Kaun KR, Chen SH, Rankin CH

[J Neurosci, 2003]

Long-term memory for habituation to tap in Caenorhabditis elegans depends on glr-1, a homolog of mammalian non-NMDA glutamate receptors; mutations in glr-1 blocked long-term memory formation. Green fluorescent protein (GFP) constructs were used to visualize glr-1 expression in the interneurons of the mechanosensory circuit and synaptobrevin in the tap sensory neurons of trained and untrained worms. Trained animals had less GLR-1::GFP expression than untrained animals; there was no difference in the vesicle marker synaptobrevin. Heat shock during training blocked both the behavioral expression of long-term memory and the change in GLR-1::GFP expression. Thus, long-term memory in C. elegans is dependent on glr-1 and likely involves changes in the expression or