Activity and Survival of Orrina phyllobia: Preliminary Investigations on the Effects of Solutes.

The motility and survival of Orrina phyllobia fourth-stage juveniles (J4) were examined in NaCl, sucrose, and synthetic soil solutions. Synthetic soil solutions (SSSs) contained Na, K, Ca(2), Mg(2), Cl, and NO at relative concentrations identical to those in a known agronomic soil. Nematode activity was dependent on solute composition and on water potential. In all solutions, motility ceased at a water potential of -30 x 10 Pa and nematodes partially desiccated. Activity inhibition in NaCl began at -5 x 10 Pa. At -15 x 10 Pa, a high level of activity was sustained only in SSS. Lethal effects occurred at -15 and -60 x 10 Pa in NaCl and SSS, respectively. No lethal effects were measured in sucrose solutions. Hydrogen ion concentration over the pH range 4.5-9.5 had no measurable effect on nematode activity.

Effects of the Ionic Composition and Water Potential of Aqueous Solution on the Activity and Survival of Orrina phyllobia.

The activity and survival of Orrina phyllobia fourth-stage juveniles (J4) were examined in aqueous solutions representing 96 combinations of eight predominant soil solution ions at total concentrations of 100, 200, and 1,000 meq/liter. Various water potentials were imposed by the addition of mannitol or polyethylene glycol to ionic solutions. Nematode longevity increased as water potential was decreased. Longevity was approximately doubled at a water potential of -23 x 10 Pa and more than tripled at -60 x 10 Pa. No combination oflons at 200 meq/liter was lethal after a 6-day exposure. Several ion combinations significantly increased longevity at -10 and -23 x 10 Pa. Single cation Na solutions consistently inhibited activity and more than doubled nematode longevity.

Some Factors Affecting Survival of Desiccation by Infective Juveniles of Orrina phyllobia.

The survival of desiccation by J4 Orrina phyllobia was examined at controlled relative humidities. When nematodes were transferred from water to air at 10% relative humidity (rh), 80% died within 30 minutes. When nematodes were transferred from water to air with rh at 70% or greater for ca. 15 minutes prior to being transferred to 10% rh, more than 90% of them survived desiccation. This phenomenon is referred to as preconditioning and occurred at much faster rates (2-30 minutes) than has been observed for other nematode species (24 hours). Differences in preconditioning rates may be due to technique-dependent variations in boundary layer resistance around nematodes during desiccation.

Effects of Oxygen and Temperature on the Activity and. Survival of Nothanguina phyllobia.

The effects of oxygen and temperature on the activity and survival of infective forth-stage juveniles of Nothanguina phyllobia Thorne were examined in aqueous suspension. Rate of movement was not affected by a wide range of O concentration (0.8-8.6 ppm). Activity decreased below 0.8 ppm 0 2, and at 0.15 ppm O nematodes became motionless. Activity increased as a linear function of temperature up to a thermal optimum of 24 C; beyond 24 C activity decreased. Survival was greatly prolonged at low temperature. At 23 C, 50% mortality occurred within 7 d, whereas at 4 C, 70% survived after 98 d.

A plastic tube technique for direct vision of endodontic procedures.

A technique for the direct visualization of endodontic procedures utilizing clear plastic tubes machined to simulate root canals is described. The visualization of endodontic procedures allows for their evaluation by the clinician as well as their use as an adjunct to didactic courses in endodontics. During mechanical instrumentation it is evident that a concerted effort must be made to debride all of the walls of a canal. Hydraulic forces are seen to play a major role in irrigation and in applying root canal cement. The technique also reveals voids in the completed root canal filling when verticle condensation is used to obturate the canals.

Antibiotic sensitivities of enterococci isolated from treated root canals.

Enterococci that persisted in debrided, medicated root canals were tested by the Kirby-Bauer procedure for sensitivity to various antibiotics. The 50 strains tested were uniformly sensitive to ampicillin and vancomycin. More than 90% were also sensitive to erythromycin. Varying degrees of sensitivity and resistance were noted to bacitracin, cephaloridine, cephalothin, chloramphenicol, gentamicin, and tetracycline. All organisms were either partly or wholly resistant to clindamycin; penicillin; streptomycin; and sulfadiazine, sulfamerazine, and sulfamethazine (triple sulfas).

Yeast spheroplasts formed by cell wall-degrading enzymes from Oerskovia sp.

Oerskovia sp. produces inducible extracellular enzymes which degrade the walls of various yeasts. Yeast spheroplasts are formed from both log- and stationary-phase cells.

Ultrastructure of nematode-trapping fungi.

Capture cells differ ultrastructurally from vegetative cells in the nematode-trapping fungi, Dactylella drechslerii, Monacrosporium rutgeriensis and Arthrobotrys dactyloides, which capture prey by means of adhesive knobs, adhesive hyphal networks, and constricting rings, respectively. Adhesive knobs and adhesive networks contain dense inclusions not found in hyphal tips or subapical regions of the vegetative hyphae, and rough- and smooth-surfaced membranes are abundant in these trap cells. The fine structure of constricting rings differs from that of adhesive traps, and it is altered by closure. In the open configuration, there are membrane-bound inclusions, labyrinthine networks, and electron-lucent regions between the protoplasts and cell wall, all localized on the luminal side of the ring cells. After closure, these features no longer are evident and the cytoplasm of trap cells stains less densely.