Effects of parasitization of Trichoplusia ni by Chelonus sp.

ABSTRACT. Parasitization of Trichoplusia ni (Huebner) (Lepidoptera: Noctuidae) by Chelonus sp. (Hymenoptera: Braconidae), an egg-larval parasitoid, leads to precocious cocoon spinning of the host in the fourth (penultimate) stadium followed by parasitoid emergence from the prepupa. We have investigated the mechanism by which Chelonus sp. disrupts host development. The developing larva and fluids injected by the adult female separately from the egg, are not the source of these effects, but it remains a possibility that the teratocytes, originating from the trophamnion of the parasitoid egg, are responsible. The titre of the juvenile hormone esterase activity in the haemolymph of the parasitized fourth instar host is similar to that in the initial period of the final instar of normal T. ni, but lacks the postwandering peak of activity. The increased JHE activity leads to a reduced JH titre early in the fourth stadia. This indicates that disruption of host development occurs within 12h after apolysis to the fourth stadium, if not before. Anti-juvenile hormone activity is not detected in extracts of parasitized T. ni. The morphological and behavioural changes associated with precocious development of the T. ni host are prevented by applications of juvenile hormone I, juvenile hormone II and the juvenoid, Ro 10–3108, but not juvenile hormone III and the juvenoid R 20458. However, these applications fail to prevent the onset of juvenile hormone esterase activity, another marker of precocious development. These observations indicate that simple anti-juvenile hormone activity may not be the mechanism of disruption of host development. Development of the parasitoid is disrupted by application of Ro 10–3108 and juvenile hormones I, II and III, but timing of eclosion is only affected by application of juvenile hormone I, juvenile hormone II and Ro 10–3108. This observation may indicate a discrimination by the parasitoid between its own juvenile hormone III and the host's juvenile hormone II.     

Rhythmic cyclic AMP changes in Chlamydomonas cells synchronized by temperature and light cycles in chemostat culture

Division in chemostat cultures of Chlamydomonas reinhardi was synchronized by daily cycles of both temperature and light. In response to 8 h cool (20 degrees C) - dim light/16 h warm (28 degrees C) - bright light cycles and continuous dilution that removed half the cells daily, the cells replicated nuclear DNA late in the warm-bright phase; released an average of two daughter zoospores early in the warm-bright phase of the next cycle. In these synchronized green algal cultures all ATP and most cAMP were intracellular; most cGMP (approximately 91%) was extracellular. Early in the warm-bright phase ATP doubled after which cAMP level fell 25%. During DNA replication cAMP level doubled, rising to a modest peak reached as replication ended.     

Development of a diagnostic test system for detecting soluble staphylococcal antigens by an immunoenzyme method

ELISA is used for detecting the soluble staphylococcal antigen in patients with purulent septic infections. The optimum conditions for the assay have been established: the dose of staphylococcal gamma globulin for plate sensitization should be 5.0-10.0 micrograms/ml, the pH of the buffer solution 9.6-10.0, the time and temperature of incubation 18-20 hours at 4 degrees C or 5 hours at 37 degrees C. The possibility of using plates manufactured in the USSR has been shown. The sensitivity of the above diagnostic test system is 0.005 microgram/ml.     

Low-frequency response characteristics of three Grass model 7 polygraphs

A low-frequency response analysis of three Grass model 7 polygraphs was undertaken. Observed error was generally found to fall within the manufacturer's stated range of +5 to -10% of DC signal height over the frequency range of human respiration (0.1-3 Hz), but this was not the case for frequencies greater than 6 Hz under certain circumstances. The magnitude of error was seen to vary directly with frequency and indirectly with pen-deflection amplitude and paper speed. The pen-oscillograph apparatus was the predominant source of low-frequency error, and this is probably due to pen inertia and pen friction on the writing surface. Two schemes to reduce such error are presented.     

O-acetyl-salicylic acid promotes colony formation from protoplasts of an elite maize inbred

The salicylic acid derivative acetylsalicylic acid (ASA) was found to promote colony formation from protoplasts isolated from embryogenic suspension cultures of an elite maize inbred line. The drug was most effective at concentrations of 30–100 mg/l, and increases of more than 20-fold in the number of colonies recovered from protoplasts were obtained. The rate of growth of protoplast-derived cell colonies was not affected.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - DMSO dimethylsulfoxide - KM Kao and Michayluk medium (1975) - MES 2[N-morpholino]ethanesulfonic acid - ASA acetylsalicylic acid