Protection of Mice against Lethal Coxsackievirus B3 Infection by Using DNA Immunization

Vaccination with DNA and recombinant vaccinia viruses (rec.VV) has been studied with the coxsackievirus B3 (CVB3) model system. Plasmids encoding all structural proteins of CVB3, when injected intramuscularly, induced only low levels of virus-specific antibodies. However, DNA vaccination with the major structural protein VP1 protected 72.2% of mice from lethal challenge, whereas VP1 expressed by rec.VV was much less efficient.     

Nerve growth factor (NGF) regulates adult rat cultured dorsal root ganglion neuron responses to the excitotoxin capsaicin

An overlap between subpopulations of nerve growth factor (NGF)-responsive and capsaicin-sensitive dorsal root ganglion (DRG) sensory neurons has been suggested from a number of in vivo studies. To examine this apparent link in more detail, we compared the effects of capsaicin on adult rat DRG neurons cultured in the presence or absence of NGF. Capsaicin sensitivity was assessed histochemically by a cobalt staining method, by measuring capsaicin-induced 45Ca2+ uptake, and by electrophysiological recording of capsaicin-evoked membrane currents. When cultured with NGF, approximately 50% of these adult DRG neurons were capsaicin-sensitive, whereas adult sympathetic neurons or ganglionic nonneuronal cells were insensitive. DRG cultures grown in the absence of NGF, however, were essentially unresponsive to capsaicin. Capsaicin sensitivity could be regained fully within 4-6 days of replacement of NGF. These results indicate that, at least in vitro, NGF can modify the capsaicin sensitivity of adult DRG neurons.     

Potentiation of salivary fluid secretion in ixodid ticks: a new receptor system for gamma-aminobutyric acid

gamma-Aminobutyric acid (GABA), having minimal intrinsic activity, potentiates dopamine-induced fluid secretion in salivary glands of female ixodid ticks. Because the effect of GABA was similar to that of spiperone, we tested whether these two drugs act at a common recognition site. Potentiation was not augmented when salivary glands were exposed to supramaximal concentrations of spiperone (1 microM) plus GABA (100 microM). (+/-)-Sulpiride (100 microM), a spiperone antagonist in this system, also blocked GABA-induced potentiation. Picrotoxin (100 microM) and (-)-bicuculline (100 microM), two GABA antagonists, blocked GABA-induced and spiperone-induced potentiation. Inhibition of GABA by picrotoxin and (-)-bicuculline was noncompetitive. Muscimol (an agonist at GABAA receptors) also potentiated dopamine-induced secretion. Baclofen (an agonist at GABAB receptors) did not elicit potentiation. We suggest that GABA may function as a neuromodulator for dopamine-induced fluid secretion in tick salivary glands.     

A scanning electron microscope study of the effect of an enterotoxin from Clostridium perfringens 8-6 on mice of different ages

Intestinal damage to mice caused by an enterotoxin from a coatless spore mutant of Clostridium perfringens type A (8-6) was examined by scanning electron microscopy. Two distinct types of damage were observed, both of which could be correlated with animal age. Damage appeared to occur in a specific sequence similar to that found in previous studies in rabbits. We conclude that the type of ileal tissue damage reflects the mode of toxin incorporation from the gut, which is a function of animal age.     

Changes in density of DNA after interaction with dipicolinic acid and its possible role in spore heat resistance

We examined the effect of interacting dipicolinic acid and its calcium chelate on the wet and dry density of DNA. Complexes are produced whose densities are different from those of the individual components. Also, we observed two modes of binding, one strong the other weak, between DPA or CaDPA and DNA. The strength of the binding modes was reflected in the rate of dissolution of the complexes as monitored by changes in wet density with time and temperature. We conclude from these and other data in the literature that the interaction of dipicolinic acid with DNA not only influences the spore wet density and the ratio of core/core⁺ cortex volume, but may also influence the spore heat resistance.     

A NEW GENUS OF PROTOSTELIDS SHOWING AFFINITIES WITH CERATIOMYXA

A new genus and species of the Protosteliida (Mycetozoa), Ceratiomyxella tahitiensis, was isolated from dead plant material—var. tahitiensis from Tahiti and var. neotropicalis from Brazil and Colombia. The sporocarps have deciduous spores borne singly on slender hollow stalks; zoocysts with anteriorly flagellate planonts are produced. The trophic stage is comprised of uninucleate to plurinucleate amoeboid cells and reticulate plasmodia; the uninucleate cells become flagellate in water. The prespore cells and spores are plurinucleate. Sexuality has not been demonstrated. Var. tahitiensis has globose spores and produces its zoocysts just after spore germination, whereas var. neotropicalis has subglobose spores and forms zoocysts later in the life cycle. The species is thought to show phylogenetic relationships with Ceratiomyxa, which was recently transferred to the Protosteliida by Olive.     

Internal proteins of bacteriophage T4D: Their characterization and relation to head structure and assembly

Three basic proteins of low molecular weight (about 8000, 10,000 and 18,000) were isolated from the T4D phage particle. Many molecules of each protein are located within the phage head, possibly in association with the DNA, and together with the proteins which form the head membrane comprise most of the head structural protein. The purified internal proteins were characterized by physicochemical and immunological techniques; a radio-immunoassay allowed measurement of their synthesis in phage infected bacteria. Each internal protein is synthesized at both early and late times after infection. Their structural genes are present in the phage genome, but do not appear to be among the known amber mutant-containing genes of T4D. No evidence was found to suggest that the internal proteins are formed from a common precursor molecule, nor are their origins related to those of the internal peptides; however, one of the internal proteins may be altered before its incorporation into the phage. Pulse-chase experiments with two of these proteins show that they are incorporated into certain defective T4D heads. Whether or not they are incorporated appears to depend on the degree of completion of these heads, perhaps with respect to DNA packaging.