-
Sural S, Gourgou E, Akba K, Deb A, Kamak M, Ji EJ, Pereira B, Moyle MW, Glater E, Willis AR, Giunti S, Hernandez Lima M, Soo S, Charlesworth AG, De Rosa MJ, Singhvi A, Traa A
[
J Neurogenet,
2020]
In the following pages, we share a collection of photos, drawings, and mixed-media creations, most of them especially made for this JoN issue, manifesting <i>C. elegans</i> researchers' affection for their model organism and the founders of the field. This is a celebration of our community's growth, flourish, spread, and bright future. Descriptions provided by the contributors, edited for space. <sup>1</sup>.
-
[
International Worm Meeting,
2015]
Investigation of the neuronal basis of economic decisions would be accelerated by establishing decision making paradigms in simple, genetically tractable organisms, such as the nematode Caenorhabditis elegans. For an organism to be a valid model of economic decision making its choice behavior must be sensitive to: (i) the difference between high and low quality goods, and (ii) the relative cost of those options.Previous work has shown that the nematode worm C. elegans quickly learns to feed on those foods (species of bacteria) that promote higher rates of growth and reproduction. Worms spend more time foraging in patches of Good bacteria (high worm growth rate) versus Mediocre bacteria (moderate growth rate) when equally abundant. Until now, however, it has not been possible to simultaneously present two food choices of different quality and cost. To that end, we have developed an electro-microfluidic device in which a semi-restrained worm forages between contiguous yet discrete fluid streams containing good and mediocre quality food. This arrangement constitutes a two-alternative forced-choice task, analogous to those used in behavioral economics. Electrodes inserted into the device monitor muscular impulses associated with individual swallowing events. Relative consumption of Good and Mediocre food is measured by counting the number of swallowing events in the respective fluid streams. The fraction of total swallowing events in Good vs Mediocre food serves as an index of food preference. Importantly, we can alter the effective prices of the two foods by adjusting the concentration of the bacteria, with price being inversely related to concentration.Here we present behavioral data delineating preference for Good vs Mediocre food across a range of relative prices. We find that worms exposed to the two species of bacteria at equal prices prefer Good bacteria, indicating that feeding preferences are normal in the device. Worms respond to price adjustments as predicted by economic theory in that increasing the relative price of a food leads to a decline in its consumption. In addition, we present calcium-imaging data from sensory neurons showing that they respond to transitions between Good and Mediocre foods, and the amplitude of calcium signal scales with relative food preference. These results show that C. elegans forages in an economic manner, and that relative value is represented at the level of the sensory neurons.
-
Price, Jon, Willis, Alexandra, Stevens, Lewis, Miska, Eric, Fisher, Kinsey, Reinke, Aaron, Burton, Nick, Braukmann, Fabian, Baugh, L. Ryan
[
International Worm Meeting,
2021]
Despite reports of parental exposure to stress promoting adaptations in progeny in diverse organisms, there remains considerable debate over the ecological significance and evolutionary conservation of these multigenerational effects. Here, we investigate four independent examples of intergenerational adaptations to stress in C. elegans - bacterial infection, microsporidia infection, osmotic stress and starvation - across four different Caenorhabditis species. We found that all four intergenerational adaptations to stress are conserved in at least one other species, that the responses and evolutionary conservation patterns are stress specific, and that intergenerational adaptive effects have deleterious trade-offs in mismatched environments. By profiling the intergenerational and transgenerational effects of different stresses on gene expression across species, we identified 3,174 genes that exhibited intergenerational changes in expression in multiple species in response to stress. Furthermore we found that an inversion in the expression of certain stress response genes required for intergenerational adaptations, from increased expression in the offspring of stressed parents to decreased expression in the offspring of stressed parents, correlates with an inversion of an adaptive response to infection in C. elegans and C. kamaaina to a deleterious intergenerational effect in C. briggsae. By contrast, we did not observe any conserved transgenerational changes in gene expression in response to stress, suggesting that the intergenerational effects of stress on offspring gene expression are not maintained transgenerationally. Our results demonstrate that intergenerational responses to stress play a substantial, evolutionarily conserved, and largely reversible role in regulating animal physiology.
-
[
Worm Breeder's Gazette,
1982]
Two sets of experiments have recently established the nature of sup- 5 and
sup-7 mediated suppression. In the allele first approach Micheline Harris and Hazel Sive showed that
unc-54(
e1300) produces a COOH truncated myosin about 7,000 daltons smaller than the full length polypeptide. Suzanne Bolten cloned the DNA from this mutant using an
unc-54 probe from Jon Karn to screen an
e1300 library in. Jon's lambda1059 vector. We sent the clone to Jon who sequenced the 3' segment, and found a C+T mutation at position 8013 which changed a glutamine codon to an amber terminator. EMS at least in one instance has produced a GC to AT transition! In the suppressor first approach, we made crude tRNA preps from N2,
sup-5 and
sup-7 strains and sent them to Norma Wills in Ray Gesteland's lab in Salt Lake. Norma used the tRNAs in an in vitro translation system, which employs wheat germ extracts programmed with various messengers to test suppression of all 3 terminators. After initial negative results, we prepared nematode S-100 and Norma included this in her assays. It worked! Convincing suppression of a Brome Mosaic Virus coat protein UAG terminator with
sup-7 tRNA was seen, and separation of the tRNAs by RPC-5 and Sepharose 4B chromatography produced a fraction greatly enriched for suppressor activity. The S-100 can come from either wild type or suppressor strains and works only with tRNA from either
sup-5 or
sup-7. In fact wild type yeast S-100 will substitute for C. elegans S-100. No suppression of other terminators was seen. The amino acid inserted by the suppressor is not yet known, nor do we know for certain that the suppression comes from a change in a tRNA anticodon . Currently we are trying to clone the suppressor genes using complementation of yeast amber mutations with a C. elegans library in an E. coli yeast shuttle vector, and ,screening lambda libraries with a partially purified tRNA preparation with suppressor activity. Nothing definitive yet but some encouraging results.
-
[
International Worm Meeting,
2009]
Behavioral and developmental choices made by any animal represent a strategy for surviving and reproducing in its environment. The essence of strategy is making decisions on the basis of incomplete information, decisions whose costs and benefits can''t be accurately determined at the time they must be made. Worms make many such choices: the decision to leave low-quality food in search of higher quality, the decision to lay eggs or allow them to hatch internally, and the decision to become a dauer or remain a dauer are examples. Not coincidentally, most of these decisions involve food availability, perhaps the most important environmental variable to a worm. I am trying to quantitatively model such decisions, using mathematical tools developed for financial markets. The L2/L2d decision is particularly interesting, because it appears to be unnecessary. An L2d can become either an L3 or a dauer, while an L2 can only become an L3. Since the L2d can do everything the L2 can do and more, why does the L2 exist? A likely answer is suggested by the work of Golden and Riddle. They showed that L1 L2d L3 pathway takes a few hours more than L1 L2 L3. Under ideal conditions a worm population doubles in 10-11 hours. (This number is calculated from published life-history traits, and is in approximate accord with lab experience.) A delay of 7 hours, therefore, reduces fitness by a factor of 27/10.5 = 0.62. Thus a worm that becomes an L2d pays a price of about 40% of its fitness for the option of eventually becoming a dauer. A worm should become an L2d if it can confidently predict that conditions will be so bad in the future as to cause a decrease of fitness of this magnitude. Most of what we know about dauer formation concerns how the worm evaluates environmental conditions. However, the L2d should also be preferred in highly uncertain environments, since it postpones the dauer decision into the future, when more accurate information will be available. This effect can be modeled using the tools of stochastic calculus, used to price options in financial markets. They predict that the L2/L2d decision should be strongly influenced not only by how good the environment is, but also by how volatile it is.
-
[
International Worm Meeting,
2017]
Value-based decision making - choices driven by subjective assessments of utility - is a central function of the brain and the focus of intensive study in mammals. Until now, evidence that nematodes are capable of value-based decision making has mainly been suggestive. However, economists have developed formal procedures for determining whether a consumer's decisions are based on subjective value as opposed to random or capricious impulses. We recently developed microfluidic devices that enable such tests to be performed on nematodes for the first time. The worm is held at the confluence of contiguous streams of high and low quality bacterial food leaving its head free to move. Bacteria concentrations are adjusted by the experimenter to change the relative "prices" of the two foods in terms of number of bacteria consumed per pharyngeal pump. Food concentrations can also be adjusted in tandem to increase or decrease the worm's overall consumption possibilities, i.e. "budget." Consumption is measured by counting pharyngeal pumps recorded electrically. Worms typically fed in both streams, consuming a mixture of high and low quality food that was unique for each combination of price and budget. We found that worms make globally rational choices in that they obey transitivity. That is, for all sets of food mixtures A, B, and C, if A is preferred to B, and B to C, then A is preferred to C. As transitivity is the necessary and sufficient condition for value maximization, these data provide formal evidence that C. elegans exhibits value-based decision making. Further, we found that the olfactory neuron AWC, known to be activated by the sudden absence of food, is required for intact food choice behavior. Surprisingly, however, we found that AWC is also activated by the switch from high quality food to low quality food, even when the two foods are at the same concentration (price). Thus, subjective value may be represented at the level of individual olfactory neurons. Our behavioral and neuronal data are consistent with a model in which olfactory neurons represent the subjective value of the local environment to direct behavior toward preferable mixtures of particular foods. To our knowledge, this is the first formal demonstration of value-based decision making in a genetically tractable model organism with a simple nervous system, opening the door to the discovery of conserved genes and neural circuits for rational decision making.
-
[
Worm Breeder's Gazette,
1992]
After tabulating the results of the Worm Plate Survey. we have come up with some interesting results. Most notably. the high variability in prices that labs are paying for their plates, even for the exact same plates from the same supplier, and the fact that most plates are marked up considerably over the actual cost. The replies can be separated into 4 categories: Labs that get plates from Fisher ($29-$58). but wish they had non-vented plates Labs that get non-vented plates via Applied Scientific (~$38) Labs that get plates from Falcon (vented) or Nunc (non-vented) and pay much more Most labs' plates were "slipable" or "semi-stackable", but all labs wanted plates that stack well for easy manual pouring, seeding, carrying, and using. Everyone wanted plates with shallow lids such that the bottoms can be lifted out of the tops for inverted use. Some labs expressed an interest in plates slightly smaller than "60 mm". That number is in quotes because all of the companies' plates have bottoms smaller than 60 mm (e.g. Fisher -54 x 14 mm). We have negotiated with the plastic companies that really make the plates for Fisher, Applied Scientific, etc. (that actually just resell them to you). I have come to the conclusion that we can provide you with better worm plates, the same worm plates cheaper, or in most cases better worm plates cheaper. This is true for every lab. The bottom line is that we can get you top quality non-vented "60 mm" plates (like Applied Scientific's, except fully stackable) for about $29 per 500 case INCLUDING shipping depending on your usage and how many cases you can receive at one time. Several labs have found the non-vented plates last longer without drying out or getting contaminated, compared with normal vented plates, so you should save that way, too. We offer full service shipping (e.g. standing orders and same-day telephone orders, free. Similarly low prices are available on 100 mm and 150 mm plates that exceed industry standards for flatness (reducing media usage) and clarity. The 100 mm are about $27 per 500 case plus shipping; The 150 mm dishes (good for DNA & RNA preps and library platings, with more than 2.25x the surface area of 100 mm dishes) are made thicker and deeper than industry standards and are about $21.50 per 100 case plus shipping. The shipping charge is very low for labs, or groups of labs in one city, that can take delivery of many cases in a single shipment. You can even suggest that your stockroom order plates from us. Call us for an exact price quote depending on your usage and how many cases you can receive at one time. In any case, we'll work things out to save you money. In the future, we can offer inexpensive 35 mm dishes if the community at large can order about 2000 cases per year, so let me know about your needs for other sizes. The response was very mixed about pre-poured plates. We may set that up later, but for now we can help the most by saving you lots on empty petri dishes (and later, maybe media .supplies). We are happy to send out free samples so you can examine the dishes. If we haven't contacted you yet, just give us a call. Respondents: 38 (including 5 anonymous) "Winners": Horvitz = 550, Meyer = 400, Thomas = 400, Greenwald = 300 200-299 cases 8 labs 100-199 cases 7 labs 4-99 cases 19 labs Highest price per case: US = 118.75, Canada = $117 (non-vented) Lowest price per case: US = $29, Canada = $25 (vented) Farthest away response: Malta! No responses from MRC or anyone else in Europe or Asia. It is possible that we can save money and/or provide better plates for these labs, including, shipping, too. Let us know.
-
Papazoglou, TG, Filippidis, G, Kouloumentas, C, Voglis, G, Kapsokalyvas, D, Tavernarakis, N
[
J Phys D Appl Phys,
2005]
Two-photon excitation fluorescence (TPEF) and second-harmonic generation (SHG) are relatively new promising tools for the imaging and mapping of biological structures and processes at the microscopic level. The combination of the two image-contrast modes in a single instrument can provide unique and complementary information concerning the structure and the function of tissues and individual cells. The extended application of this novel, innovative technique by the biological community is limited due to the high price of commercial multiphoton microscopes. In this study, a compact, inexpensive and reliable setup utilizing ferntosecond pulses for excitation was developed for the TPEF and SHG imaging of biological samples. Specific cell types of the nematode Caenorhabditis elegans were imaged. Detection of the endogenous structural proteins of the worm, which are responsible for observation of SHG signals, was achieved. Additionally, the binding of different photosensitizers in the HL-60 cell line was investigated, using non-linear microscopy. The sub-cellular localization of photosensitizers of a new generation, very promising for photodynamic therapy (PDT), (Hypericum perforatum L. extracts) was achieved. The sub-cellular localization of these novel photosensitizers was linked with their photodynamic action during PDT, and the possible mechanisms for cell killing have been elucidated.
-
[
European Worm Meeting,
2006]
Yohann Duverger1, Jrme Reboul2, Daniel Wong1 and Jonathan Ewbank1 For the last three years, we have offered a service of worm sorting based around the Union Biometrica COPAS platform. The COPAS machine is equipped with a Zymark twister robot, allowing automated analysis of multiple 96 well plates. We recently upgraded the machine to include the Profiler II that generates >1000 individual measurements per worm simultaneously for up to 4 channels (including 2 fluorescent). This equipment has been applied to a wide range of biological questions. They include quantifying the level of fluorescent reporter gene expression, large-scale RNAi and genetic screens and combinatorial library drug screening. Examples of each will be presented.. This platform is part of a fully integrated functional genomics facility open to the academic community (see
http://www.ciml.univ-mrs.fr/EWBANK_jonathan /RIO.html). Other resources include the ORFeome (developed in Marc Vidals laboratory), and Julie Ahringers RNAi library, together with whole-genome microarrays. For the latter, through a collaboration with the Genome Sequencing Center at Washington, and the transcriptome platform at Nice, we have spotted the Illumina long oligo set onto glass slides and provide microarrays free of charge to the French C.elegans community and at cost price to academic researchers in Europe.. This French functional genomics platform has been made possible through funding from the National Genopole network, Marseille-Nice genopole, the CNRS and support from Union Biometrica.
-
[
International Worm Meeting,
2007]
Cell to cell interactions play critical roles in early embryogenesis, therefore, it is very important to have information about the arrangements of cells, cell shapes and the contact among them. We have been developing a computer system to create cell shape models from a time series of confocal microscopic images of the embryo whose plasma membrane is labeled with a vital fluorescent dye or a fluorescent protein. In this system, cell shapes are automatically calculated by a seeded region growing algorithm from a 3D image and a set of seed point coordinates. Manual editing of the seed coordinates is required and is assisted by its graphical user interface. We applied this system on the "dub" data set in WORM 4D CDs kindly provided by Bill Mohler, and obtained cell shape models of 24-200 cell stages successfully for the most part. This time, in collaboration with Jon Audhya, we performed live recording of OD58, the strain expressing the fusion of GFP with pleckstrin homology domain which is targeted to the plasma membrane. We successfully obtained data sets of 1-24 cell stages. We also developed a post-processing system to remove the bumps of cell shapes derived from image noises by implementing an active balloon model under gradient vector flow. As a result, the phenotype of
par-2 RNAi embryos could be evaluated in terms of cell volumes and cell-to-cell contacting areas. We are improving the system more, and plan to apply this system to compare the cellular arrangements and the cell-to-cell contacts among mutant embryos and the embryos from other species closely related to C. elegans.