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[
Worm Breeder's Gazette,
1986]
It appears that a large proportion of rhabditoid nematodes found in the soil are associated with specific invertebrates, and of these nematodes, a large proportion are protandric hermaphrodites. There is a definite advantage in being associated with an invertebrate--it provides the nematode with a potential food source which becomes available when the invertebrate dies and is colonized by bacteria. Since competition for this bacterial-rich source is great, an advantage is gained by nematodes which are 'on the spot.' The best way of achieving this is to be associated with the invertebrate before it dies. The hermaphrodite's advantage becomes apparent since time is valuable and a single amphimictic nematode has no opportunity of establishing itself. Most of the rhabditoid nematodes remain in the dauer stage while associated with the invertebrate (e.g. Rhabditis aspersa in snails, Rhabditis pellio in earthworms, Caenorhabditis dolichura in ants) and then initiate development as soon as the host dies. Recently Rhabditis myriophila, another hermaphrodite, was recovered from the gut of a milliped, and basically follows a cycle similar to the above-mentioned species. Other advantages of being associated with invertebrates are protection during adverse environmental conditions and distribution. Although the easiest way to recover specific rhabditoid species is to search for their associated invertebrate, all stages of these nematodes can also be found in soil when they are labelled freeliving ( ecological term) or microbotrophic (nutritional term). By just being a hermaphroditic rhabditoid nematode, the chances that C. nvertebrate associate somewhere out there are good.
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[
Worm Breeder's Gazette,
1975]
A Zeiss universal microscope with Nomarski optics has been modified by the addition of a semi-silvered mirror mounted behind the objective. A dye laser giving 0.25 joule pulses at 450 nm wavelength is set up so that the beam is brought into focus in the plane of the object. A spot size of about 1.5 m is produced and this can be used to kill individual cells in the nematode with no apparent damage to their neighbors. It has been found that there is very little regulation of the nematode. When one of the precursors that migrate into the ventral cord is killed, the adjacent ones go through their normal sequence of divisions. The daughters of the precursor that migrates into the RVG behave differently from those in the rest of the cord. When this precursor is killed the next one along will go into the RVG. We are at the moment performing an E/M autopsy on one of these animals to see whether the daughter cells from this precursor behave as the original one would have done or as those from a normal cord precursor. When the mesodermal blast cell of the hermaphrodite is killed a perfectly normal looking animal is produced which is lacking in all the cells which derive from that cell. It cannot lay eggs however, as it has no vulval muscles. When the gonad primordium is killed in the hermaphrodite there is no gonad or vulva produced but the vulval muscles migrate to the right place and start twitching even though there is nothing there.
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[
Worm Breeder's Gazette,
1976]
Nematodes can be grown conveniently in gram quantities on plates. Using the Cambridge bacterial strain, NA22 and increasing the amount of Bactopeptone in NGM media from 0.25% to 2% in 0.25 steps results in an approximately linear increase in yield on 8.5 cm diameter petri dishes. The settled volumes are 0.03 ml to 0.22 ml of worms per plate for 0.25% and 2%, respectively. N2, E675, and E190 have been grown this way. Caution: l) I can't guarantee that a single nematode would behave in this manner. All of my work has involved washing nematodes off NGM plates with M9 buffer, letting the nematodes settle, and then pipetting the nematodes onto enriched peptone plates at no more than a 10x dilution. 2) Although 2% Bactopeptone plates may not be the limit for linearity of nematode growth, a medium can be too rich. For example, 3xD plates cause nematodes to go into dauer or die.
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[
Worm Breeder's Gazette,
1996]
There is precious little in the literature regarding the regenerative ability of nematodes (Poinar, 1988). The received wisdom has been that the determinate cleavage in these pseudocoelomates precludes any possibility of epimorphic regeneration (K.A. Wright pers. comm., 1988). Although Filipjev (1921) stated that regeneration is "completely absent" in nematodes, other reports by Micoletzky and Kreis (1930) and Allgen (1959) present another picture which seemingly contradicts such a blanket generalization. Last year it was reported that a gastrotrich (undescribed species of Turbanella) of the genera Macrodasyidae, a primitive sister group of the Nematoda, restored epidermis with complete wound closure following transection; restructuring of Y organ and intestine; and caudal adhesive tubes forming anew (Manylov, 1995). This is the first report of regeneration in this group. In another recent paper from the former Soviet Union, Voronov and Panchin (1995a) report that a nematode, of the order Enoplida (E.brevis), has a process of gastrulation which contradicts the patterns of cleavage formerly ascribed to the Enoplida (Malakhov,1994). They observed that up to the sixteenth cell stage cleavage is usually (though this can vary) equal and synchronous, producing blastomeres of equal appearance; elsewhere they observe that the primordia which gives rise to all the endoderm can be derived from either the anterior or posterior at the two-cell stage (Voronov and Panchin,1995b). This variability, they offer, makes the Enoplida different from other nematodes studied. Malakhov believes that this variability "can even engender the idea that the cleavage among members of marine Enoplida is indeterminate, but this is not so." (p.166). However, the cleavage of the Enoplida may be indeterminate enough to allow for the regenerative phenomena recently witnessed in a gastrotrich. In sum, Enoplid cleavage patterns would appear to be similar to the more primitive patterns seen in the Macrodasyidae, which is consistent with the notion that equal cleavage is ancestral and determination of early blastomere fate derived (Baguna and Boyer,1990). Also, it should be remembered that in addition to the single species reported by Micoletzky and Kreis, all nine of the species which Allgen found evidence of regeneration were marine Enoplids. Allgen,C.A.(1959)Free living marine nematodes. Further Zool. Results Swed. Antarct. Exp. 1901-03 vol.5 no.2: 1-293. Baguna,J.,B.C.Boyer(1990)Descriptive and experimental embryology of the Turbellaria: Present knowledge, open questions and future trends. In Marthy, H.(ed), Experimental Embryology in Aquatic Plants and Animals. NATO ASI 195; 95-128. Filipjev,I.N.(1921)Free living nematodes in the vicinity of Sevastapol. (in Russian), Akad. Nauk SSSR. Trudy osob. zool. lab. ser 2 41: 351-614. Malakhov,V.V.(1994)Nematodes: Structure, Development, Classification and Phylogeny. Smithsonian Inst. Press. Manylov,O.G.(1995)Regeneration in Gastrotricha - I. Light microscopical observations on the regeneration in Turbanella sp. . Acta Zool. 76:1-6. Micoletzky,H.,H.A.Kreis(1930)Freilbende marine Nematoden von den sunda-Inseln. Dansk natur. Foren. Vid. medd. Bd 87: 243-339. Poinar,G.O.(1992)Immune responses and wound repair. In Diseases of Nematodes. vol 1, p.133-40, CRC Press, Boca Raton, Florida. Voronov,D.A.,Y.V.Panchin(1995a)The early-stage of the cleavage in the free-living marine nematode Enoplus brevis (Enoplida, Enoplidae) in the normal and experimental conditions. Zool. Zhurn. 74(6): 31-38. Voronov,D.A.,Y.V.Panchin(1995b)Gastrulation in the free-living marine nematode Enoplus brevis and the localization of endodermal material at the stage of 2 blastomeres in the nematodes of the order Enoplida. Zool. Zhurn. 74(10): 10-18.
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[
Worm Breeder's Gazette,
1989]
The map is now widely distributed electronically (see WBG 10(3), 67), but we are once again providing a summary for the gazette in the form of an output from the routine CHPLT. Do note that this is a provisional best guess, and that some linkages may later go away: please enquire if you need to know about the status of particular areas. When you receive cosmid clones, as stabs, please IMMEDIATELY streak them out on selective medium, pick small colonies, and grow 4ml minipreps (protocol from Alan Coulson if needed). For some cosmids, larger preps are liable to yield deleted DNA. Check that cosmid DNA appears full size (runs slower than lambda on agarose gels), then freeze a sample of good cells in 20% glycerol at -70 C. MRC computer account 'ARC' does not exist; Alan and John share account JES. A database node is now open at Seattle: modem number 206-467-2957; operator Phil Meneely. The summary of clone types given on the next page may be helpful when you are deciding which clones to request for your research. To reveal the most suitable clones for microinjection, the buried clones need to be displayed by the routine CONTASS; we will help you to do this if you ask. [See Figures 1- 3]
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[
Worm Breeder's Gazette,
1977]
The gonad of the adult male is a single reflexed cylindrical structure, containing all stages of spermatogenesis in a single wave of development. In the end, distal from the cloaca, the cells are syncytial, surrounding a common core, similar to the arrangement in the distal arm of the hermaphrodite gonad. Further toward the cloaca, the different stages of meiosis are seen. Cells in diplotene and diakinesis contain many golgi complexes. Some golgis are associated with vesicles that have a dark amorphous collar around their necks. Other golgis are next to bodies containing microfilaments. After the vesicles and filament bodies grow, their membranes fuse to form a composite structure. The fused membranes develop dark staining thickenings and fold into convoluted sacs and tubes. The cells then go through the two meiotic divisions. At telophase II, all the cellular organelles cluster at the spindle poles. Cleavage furrows separate the daughter cells and slough off a substantial volume of cytoplasm. In the resulting spermatid the nucleus condenses to a dark staining mass of chromatin. The microfilaments of the fibrous bodies disappear. The cytoplasm becomes denser and contains numerous wavy tubular elements. The composite structures fuse with the plasma membrane forming an invagination of extracellular space that is partially filled with the convoluted membranes and the cytoplasm trapped within the foldings.
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[
Worm Breeder's Gazette,
1984]
I have written a program for the IBM PC that keeps track of nematode stocks. The current version allows a naive operator to 1) add, edit, or delete data on a strain; 2) obtain the complete listing on a strain identified by its strain name, allele name, gene name, or inhouse designation; 3) list (either on the screen or a printer) the collection by strain, Revco location, liquid nitrogen tank location; 4) list the lab's own strains or mutations; 5) list strains that contain particular genes or mutations or have particular phenotypes; 6) list the alleles of a gene (e.g.
unc-3) or a series of genes (e.g.
unc-3 to
unc-17); and 7) list a subcollection of the data, i.e. it will give the strain, gene, and mutation names and the chromosome for each allele on an imputted list (e.g. stocks at 25 C). The program is written in dBASE II (version 2.4). Anyone who would like to use or play with this program is welcome to it. However, please do not write me for a copy. Mark Edgley at the stock center has generously consented to be the go-between in all of this. Mark says that $10 should cover the costs of copying the program and sending a diskette. We cannot, however, distribute copies of dBASE II; these have to be obtained elsewhere. The program is clearly not complete (e.g. as of yet there is no provision to easily get information on references that cite particular strains). People should use the program as a guide and feel free to modify it any way they wish. I would enjoy hearing about any improvements.
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[
Worm Breeder's Gazette,
1975]
As most people are probably aware by now, I first started by collecting a large number of temperature-sensitive mutants that are blocked in the reproductive life cycle. These mutants were then placed into six phenotypic categories. The zygote-defective mutants are those that lay fertilized eggs that fail to hatch. Gonadogenesis- defective mutants are those that when reared at restrictive temperature produce neither fertilized eggs nor progeny. Spermatogenesis mutants are those that when reared at restrictive temperature, can be rescued for progeny production by mating with wild type males at restrictive temperature. The accumulators are those that grow to an intermediate larval stage and either stop growing or die at an immature stage. The abnormal F1 are mutants that when placed at restrictive temperature grow up to be adults, produce progeny, but those progeny grow up to be sterile adults. In addition, a few temperature sensitive morphological mutants were isolated. Rebecca Vanderslice and I originally studied in greater detail three particular mutants in the zygote-defective category. They were interesting in two respects. (1) Not only did they show zygote- defective phenotype when the adults were placed in restrictive temperature, they also showed gonadogenesis-defective phenotype if they had been reared from L1 onward at high temperature. (2) Each of the three mutants is a maternal-effect mutant. At the present time, Becky Vanderslice and Bill Wood are re-examining the zygote-defective class and the gonadogenesis-defective class to find out which are and which are not maternal-effect mutants. One of the central questions we are asking is, what is the distribution of critical times of temperature sensitivity among the mutants and which of these are maternal effect mutants? We're asking how far into development do the mutants go with maternal contributions.
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[
Worm Breeder's Gazette,
1977]
It remains the feeling of this laboratory that very little is known of the behavior of wild type C. elegans and that detailed analysis of the behavior of individuals still provides the best method of study. We are currently analyzing the behavior of adults, 4 1/2 days + 1/2 day at 20 C as our recent study (Croll, Smith & Zuckerman, 1977, Experimental Aging Research) has shown that age is critical in determining the rates of different behavioral actions. The wave patterns of individuals is significantly altered by L-tryptophan and D- tryptophan (5mM), an approach derived from Dusenbery (J. Exp. Biol. 1975, 193; 413). The patterns are further significantly affected by small temperature changes from the eccritic response. As well as any directional component attributed to chemical or thermal gradients, we are now considering them to be important 'behavior modifiers' in non- directional environments. A full description of defecation has been completed which supports our earlier contention that defecation is a feature of the 'feeding phase' and that its rate is dependent upon an endogenous signal(s) and not upon the rate of ingestion. When not ingesting rapidly there is a spontaneous 'pseudocrap' in which faeces are not voided! Further details (J. Zool. Lon.) can be provided of this study now in press upon request. C. elegans adults respond very strongly to electric currents and potentials between .01-.06 mA and 1.0 to 3.3 V/cm. This is now being investigated with thresholds, habituation phenomena and feeding factors being included. This response could provide a new set of mutants for those in the business of making them. Worms can go either towards the cathode or anode depending upon the current strength. We would like to develop this investigation to see if certain amphid-defective, chemoreceptive-defective mutants had also lost their galvanotaxes - any offers?
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[
Worm Breeder's Gazette,
1987]
The reason worms don't fall off an upside-down plate is surface tension. The force pressing the worm to the agar surface is roughly the surface tension of water times the perimeter of a sagittal section: 10+E5 -10+E6 times the weight of the worm for a young L1. Because of this, I thought worms might be able to survive high-speed centrifugation. Since Gary Ruvkun bet me ten dollars they wouldn't, I did the experiment. The worms were very young L1s prepared by hatching eggs in the absence of food. I first spun some at 100,000G (32,500 rpm in an 80Ti rotor). The spin was as short as I could make it: 5 min acceleration, a few seconds at speed, and 5 min deceleration. The worms were unaffected. About half of them thrashed in liquid, all looked normal in Nomarski, and all grew up to healthy, active adults and produced large broods in the normal time. Next I spun some more worms at 460,000G (70,000 rpm, as fast as our centrifuge would go). These worms were all clearly abnormal in Nomarski. There were usually empty spaces between the buccal cavity and the head cuticle, and the tail often had similar holes. In some the viscera pulled away from the cuticle in other places, too. Many individual cells were killed. Most of these worms arrested as L1s, though some continued to move. But some of them grew up to become healthy adults and produce progeny. Spinning at high speed stresses worms in three ways: there are forces flattening them against the bottom of the tube (like the surface tension forces on a plate), a very high static pressure that will affect chemical reactions (e.g. dissolution of gases, as in the bends), and forces causing components of the worm to sediment with respect to each other. Judging from the Nomarski result, it might be the last of these that bothers the worms most, though they are very resistant to all three.