Action of two juvenile hormone antagonists on lepidopteran epidermis

The juvenile hormone antagonist ETB (ethyl-4-2(t-butylcarbonyloxy)-butoxybenzoate) caused formation of precocious larval-pupal intermediates after the 4th (penultimate)-larval instar of the tobacco hornworm, Manduca sexta, when 50 μg were applied to any 3rd stage larvae or to 4th stage larvae within 12 hr after ecdysis. This dose was most effective within 12 hr after ecdysis to the 3rd stage. In the black mutant larval assay for juvenile hormone, ETB had activity, 0.75 μg per larva giving half-maximal score. In vitro ETB acted as a juvenile hormone to prevent the ecdysteroid-induced change in commitment at concentrations above 0.1 μg/ml with an ED₅₀ at 2.8 μg/ml and as a partial juvenile hormone antagonist to 0.1 μg/ml juvenile hormone I at concentrations between 10^?3 and 10^?2 μg/ml. By contrast, EMD (ethyl-E-3-methyl-2-dodecenoate) had little juvenile hormone-like activity in vitro up to its limits of solubility (100 μg/ml) and exhibited sporadic partial juvenile hormone antagonistic activity in vitro at concentrations between 1 and 100 μg/ml. Since these concentrations were 10–1000 times that of juvenile hormone I in the medium, EMD apparently is not an efficient competitor.     

Incidence of Clostridium botulinum Type E in Salmon and Other Marine Fish in the Pacific Northwest

Salmon, sole, cod, oysters, clams, and crabs from ocean waters along the coast of Oregon and Washington were examined for the presence of Clostridium botulinum type E. The organism was detected by identification of the type E toxin in enrichment cultures of the viscera of individual fish. Of 369 salmon specimens, 48 yielded cultures containing toxin lethal to mice, and almost half of the toxic cultures were shown to contain botulinal toxin, chiefly type E. Eighteen of 113 sole and cod specimens, 4 of 22 Dungeness crab specimens, 5 of 16 oyster specimens, and 27 of 115 clam specimens gave rise to cultures containing botulinal toxin which was usually type E, although types A and B were occasionally encountered.     

Virus Aggregation as the Cause of the Non-neutralizable Persistent Fraction

The non-neutralizable or persistent fraction of virus populations has been found to be caused by aggregated virus. Detailed investigation was performed with the prototype strain of echovirus type 4 (Pesascek), as this virus is notorious for its large non-neutralizable fraction. When Pesascek virus was clarified by low-speed centrifugation, homologous antiserum hardly neutralized the virus. However, when the virus was filtered through membranes having a porosity only twice the diameter of the virus, monodispersed virus was obtained which was efficiently neutralized. Serum titers were up to 1,000 times higher if the neutralization test was carried out with monodispersed virus. Virus in non-neutralizable aggregates was found to constitute 30% of the infective units of unfiltered Pesascek virus but only 0.1% of the antigenically related DuToit strain. This explains why DuToit strain has been a more satisfactory indicator strain for detecting type 4 antibodies, regardless of the echo 4 strain used for inducing the antibodies. Clarified suspensions and ultrafiltrates of viruses belonging to the picorna-, reo-, myxo-, adeno-, herpes-, and poxvirus groups were studied. Clarified suspensions yielded persistent fractions of 0.005% for poliovirus, of 0.1% for reovirus, of 0.6% for influenza virus, of <0.001% for adenovirus, of 0.06% for herpesvirus, and of 10 to 30% for vaccinia virus. In all cases the persistent fractions were removed by membrane filters which had a pore diameter no larger than twice that of the virus under test, and the high concentration of virus in each ultrafiltrate was completely neutralized by antiserum.     

Electronic recording of mosquito activity

Spontaneous locomotor activity of mosquitoes (Aedes aegypti) was tested over twenty-four hour periods using an electronic recording device which gave a permanent time graph of activity. Single mosquitoes were placed on a wire grid with alternate strands connected to the positive and negative poles of an electric circuit. Each time the mosquito moved, the electric current changed and the event was recorded by a pen-writer. The number of peaks per time interval gave the index of activity. Variables which may affect activity include age, physiological state, sex and strain. A distinct activity cycle was evident in both virgin and mated females but not in males; peak activity came in the early evening and activity was lowest in the early afternoon.

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Zusammenfassung Die spontane lokomotorische Aktivität von Mücken (Aedes aegypti) wurde über 24stündige Perioden mit Hilfe einer elektronischen Registriereinrichtung untersucht, die eine ununterbrochene Zeitschreibung der Aktivität ergab. Einzelne Mücken wurden auf einen Gürtel feiner Drähte gesetzt, deren Stränge abwechselnd zu den positiven und negativen Polen eines elektrischen Stromkreises führten. Jedesmal wenn sich die Mücke bewegte, änderte sich der elektrische Stromfluß; dieses Ereignis wurde von einer Schreibfeder aufgezeichnet. Die Anzahl der Ausschläge pro Zeiteinheit ergab den Aktivitätsindex. Variable, welche die Aktivität beeinflussen, umfassen Alter, physiologischen Zustand, Geschlecht und Abstammung. Bei jungfräulichen wie bei begatteten Weibchen war ein bestimmter Aktivitätszyklus erkennbar, jedoch nicht bei Männchen; der Aktivitätsgipfel lag in den frühen Abendstunden und die Aktivität war am zeitigen Nachmittag am geringsten.

     

Expression of members of the Saccharomyces cerevisiae hsp70 multigene family

The hsp70 multigene family of Saccharomyces cerevisiae is a complex multigene family, composed of members exhibiting complex patterns of regulation. Expression of some members is induced after a heat shock, whereas expression of others is repressed. Some members of the family are expressed during exponential growth. One gene, SSA3, shows an unusual pattern of expression during approach to stationary phase. While most RNAs decrease in abundance, SSA3 RNA levels dramatically increase. The constitutive expression of SSA3 in cells lacking adenylate cyclase activity suggests that cAMP modulates SSA3 expression.     

Characterization of a Nerve Growth Factor-Stimulated Protein Kinase in PC12 Cells Which Phosphorylates Microtubule-Associated Protein 2 and pp250

Treatment of PC12 cells with nerve growth factor (NGF) resulted in the rapid, but transient, activation of a protein kinase which specifically phosphorylated an endogenous 250-kDa cytoskeletal protein (pp250). We report that the microtubule-associated protein, MAP2, is an alternative substrate for the NGF-activated kinase. NGF treatment maximally activated the kinase within 5 min; however, the activity declined with longer exposure to NGF. The enzyme was localized predominantly in microsomal and soluble fractions and phosphorylated MAP2 on serine and threonine residues. The soluble enzyme was fractionated by DEAE chromatography and gel filtration and had an apparent Mr of 45,000. The enzyme was purified to near homogeneity by chromatofocussing and had a pI of 4.9. Kinetic analysis revealed that NGF treatment caused a sevenfold increase in Vmax for MAP2. The Km with respect to the MAP2 substrate was approximately 50 nM and was not altered by NGF treatment. A novel feature of the NGF-stimulated enzyme was its sharp dependence on Mn2+ concentration. The active enzyme is likely to be phosphorylated, because inclusion of phosphatase inhibitors was required for recovery of optimal activity and the activity was lost on treatment of the enzyme with alkaline phosphatase. Histones, tubulin, casein, bovine serum albumin, and the ribosomal subunit protein S-6 were not phosphorylated by this enzyme. The NGF-stimulated kinase was distinct from A kinase, C kinase, or other NGF-stimulated kinases. The rapid and transient activation of the protein kinase upon NGF treatment suggests that the enzyme may play a role in signal transduction in PC12 cells.