Palmer RE et al. (1994) Worm Breeder's Gazette "Use of an Expression Library to Clone Genes by Complementation"

Palmer RE, Sternberg PW

[Worm Breeder's Gazette, 1994]

Use of an expression library to clone genes by complemcntation. RE. Palmer and P.W. Sternberg, HHMI and Division of Biology, Caltech, Pasadena, CA 91125

Salser SJ et al. (1994) Worm Breeder's Gazette "mab-5 Expression Repeatedly Switches ON and OFF in the V5 Lineage"

Kenyon CJ, Salser SJ

[Worm Breeder's Gazette, 1994]

mab-5 Expression Repeatedly Switches ON and OFF in the V5 Lineage S. Salser and C. Kenvon, UCSF, San Francisco, CA. 94143

Simske JS et al. (1994) Worm Breeder's Gazette "Specification of Vulval Cell Fates By Sequential Signalling Pathways."

Simske JS, Kim SK

[Worm Breeder's Gazette, 1994]

Specification of vulval cell fates by sequential signaling pathways Jeffrey S. Simske and Stuart K. Kim, Dept. of Developmental Biology, Stanford University Medical Center, Stanford CA 94305

Sommer RJ et al. (1994) Worm Breeder's Gazette "Evolution of Vulva-Formation: Part II: Species With a Central Vulva"

Sommer RJ, Sternberg PW

[Worm Breeder's Gazette, 1994]

Evolution of vulva-formation: Part II: Species with a central vulva Ralf J. Sommer & Paul W. Sternberg, California Institute of Technology, Division of Biology 156-29, Pasadena, CA 91125

Kenyon CJ et al. (1994) Worm Breeder's Gazette "Activity of the polyray-1 Maintenance Gene Must Be Overcome To Allow For Correct Temporal Expression of HOM-C Genes"

Kenyon CJ, Maloof JN

[Worm Breeder's Gazette, 1994]

Activity of the polyray-1 maintenance gene must be overcome to allow for correct temporal expression of HOM-C genes Julin Maloof and Cynthia Kenyon, Dept of Biochemistry, UCSF, San Francisco, CA 94143 0554

Schachat FH et al. (1981) Worm Breeder's Gazette "characterization and roles of calmodulin and a second calcium regulatory protein from C elegans."

Schachat FH, Vanaman TC, Bronson DD, Jamieson G

[Worm Breeder's Gazette, 1981]

In these studies we have purified and characterized two proteins involved in Ca-regulation in Caenorhabditis st is calmodulin (CaM) which is considered to be an intracellular receptor for calcium because of the large number of cellular processes it activates in a Ca-dependent manner. The second protein which is similar to CaM in many of its physical and chemical properties, we have called the troponin-C like protein (TnCLP) . Because of a report which suggested invertebrate CaMs are dissimilar to those of vertebrates our studies on C. elegans CaM have focused on a comparison of its properties to those of bovine brain CaM. The C. elegans protein shows no major difference in amino acid composition, cyanogen bromide (CNBr) peptide maps, electrophoretic behavior or enzymatic properties in those studies. The C. elegans TnCLP, which copurifies with the CaM until DE-52 ion exchange chromatography, can be distinguished from CaM. It differs in amino acid composition, CNBr peptide maps and molecular weight, and lacks the ability to activate bovine brain cyclic nucleotide phosphodiesterase. Our concern with it has centered about defining its possible physiological roles. TnCLP forms Ca-dependent complexes with rabbit fast skeletal muscle troponin I and troponin T. It copurifies with thin myofilaments. These observations coupled with its inability to activate bovine brain cyclic nucleotide phosphodiesterase suggest that C. elegans TnCLP is not a second generalized Ca-dependent activator like CaM, but functions as a troponin C. We believe that the C. elegans TnCLP and CaM are responsible for the 2 thin and thick myofilament Ca-regulation that has been reported in C. elegans. The TnCLP acting in a troponin-like complex to regulate thin filaments. The CaM acting on thick filaments through a myosin light chain kinase as has been reported for other actomyosin contractile systems. In support of that later contention we have shown that there is an in vitro Ca and CaM dependent phosphorylation of one of the C. elegans myosin light chains. We expect these studies will serve as the basis for elucidating the Ca-dependent events in muscle contraction (as well as in other processes) both in vivo and in vitro through the analysis of genetic variants of C. elegans that may be blocked in different steps or pathways of Ca-regulation.

Sommer RJ et al. (1994) Worm Breeder's Gazette "Evolution of Vulva Formation: Part IV: Variation in AC Position Can Cause a Shift of Vulva Formation Towards P(4-6).p."

Sternberg PW, Sommer RJ

[Worm Breeder's Gazette, 1994]

Evolution of vulva formation: Part IV: Variation in AC position can cause a shift of vulva formation towards p(4- 6).p Ralf J. Sommer & Paul W. Sternberg, HHMI & California Institute of Technology, Division of Biology 156-29, Pasadena, CA

Weisblat D et al. (1975) Worm Breeder's Gazette "Electrophysiological Studies of Ascaris Muscle"

Byerly L, Russell RL, Weisblat D

[Worm Breeder's Gazette, 1975]

Using Ascaris as a model system, we are studying ionic mechanisms of the spontaneous electrical activity in nematode somatic muscle. The fast spike potentials appear to be Ca+2 mediated; their amplitude depends on the external Ca+2 concentration, they are TTX insensitive, they persist when Na+ is replaced by Tris+, choline+, or Cs+, and they are blocked by Co+2 and La+3. When the normal solution is replaced by one containing 11 mM Ba+2 and 0.15 mM Ca+2 as the only divalent cations, the slow waves underlying the normal spike activity appear to increase dramatically in amplitude and duration; spike activity gradually disappears. The duration and amplitude of the slow waves at steady state under these conditions increase with Ba+2 concentration, reaching values of 1-2 minutes and 50-60 mV, respectively, in 26 mM Ba+2. These results and others lead us to conclude that the slow waves are also Ca+2 mediated. The muscles are depolarized by 0.1 mM ouabain, suggesting some involvement of an electrogenic pump in maintaining the membrane potential. TEA, in concentrations as low as 1 mM, has pronounced effects on the spontaneous myogenic activity, consistent with the effects observed when TEA is injected iontophoretically into C. elegans.

Chuang P-T et al. (1994) Worm Breeder's Gazette "DPY-27: A Protein Required For Dosage Compensation is Associated With the X Chromosome in XX Animals"

Chuang P-T, Meyer BJ, Albertson DG

[Worm Breeder's Gazette, 1994]

Dpy-27: A Protein Required for Dosage Compensation Is Associated with the X chromosome in XX Animals Pao-Tien Chuangl, Donna Albertson2 and Barbara Meyerl, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720~ and MRC Laboratory of Molecular biology, Hills Road, Cambridge, CB2 2QH UK2

Dent JA et al. (1993) Worm Breeder's Gazette "A Defined Medium for the Pharynx"

Dent JA, Avery L

[Worm Breeder's Gazette, 1993]

In order to make the pharynx more directly accessible to drugs and electrophysiological probes, I have developed a medium that supports normal pumping of dissected pharynxes. Leon Avery and David Raizen showed that when one decapitates a worm by cutting just behind the terminal bulb (TB) with a scalpel, the pharynx protrudes from under the remaining cuticle and body muscle, directly exposing the pharynx to the medium. When dissected in Ascaris Saline (AS) and 1 M serotonin, the pharynxes pump regularly and their electropharyngeograms (EPGs) can be measured. AS was chosen because it almost exactly approximates the ionic composition of Ascaris pseudocoelomic fluid as determined by Brading & Caldwell (J. Physiol. 173.36P) and has been used successfully for electrophysiological studies of Ascaris. However, dissected C. elegans pharynxes in AS have brief pumps with little corpus motion and a correspondingly short p-phase in the EPG. By varying the ion concentrations in the medium I found that: 1) Using chloride instead of an organic anion (acetate in the case of AS) did not affect the pharynx adversely, contrary the idea that a high chloride concentration is bad for (all) nematode muscles, 2) For unknown reasons, the usually inert organic cations choline and methylglucamine cause hypercontraction of the pharynx at low (10 mM) concentrations, 3) Pump length is dependent on the external calcium concentration. The effect of calcium concentration on pump length is remarkable. By measuring the length of the P-phase on an EPG, the precise length of the pump (as defined by the period of depolarization) can be determined even when the calcium concentration is so low that the muscle stops contracting. Basically one can vary the length of a pump at will by changing the calcium concentration - high [Ca], short pump, low [Ca], long pump. By contrast, equivalent changes in the sodium or potassium concentrations mostly just reduced the amplitude of the EPG and at extremes caused pumping to cease. All effects were reversed by changing [Ca] back to normal (about 3 mM). To see if this could be an effect of calcium flux across the membrane, I treated the pharynxes with the calcium channel blockers verapamil, diltiazem, and nifedipine at concentrations of 10-20 M. All extended the pump length significantly. Increasing concentrations of magnesium also lengthened the P-phase, presumably by competitively blocking calcium channels. The effects of calcium channel blockers could be rescued by raising the [Ca]. Unfortunately Bay K, a calcium channel activator, had no effect at a concentration of 5 M. The reason for the calcium effect is not clear. If changing the external calcium concentration were affecting the ability of internal calcium to maintain the depolarization, then decreasing [Ca] should decrease the pump length, not increase it. This is not an effect on the nervous system because it occurs in a worm in which the pharyngeal nervous system was ablated. Changing external [Ca] could change the resting potential of the muscle, making the membrane more or less excitable. Alternatively, calcium could be a second messenger that is necessary for repolarization of the membrane, for example by interacting with a calcium-activated K channel; this explanation would also account for the effect of the calcium channel blockers. Improved pharynx pumping medium: 138 mM NaCl 6 mM KCI 3mMCaCl(2) 1 mM Mg Cl(2) mM phosphate buffer pH 7.4 1 M serotonin