Evaluation of Metarhizium anisopliae for the control of Culicoides brevitarsis Kieffer (Diptera: Ceratopogonidae), the principal vector of bluetongue virus in Australia.

Four isolates of the entomopathogenic fungus Metarhizium anisopliae were tested for their potential to control the biting midge Culicoides brevitarsis, the principal vector of bluetongue virus in Australia. Adult C. brevitarsis died three to eight days after walking on paper substrate treated with 0.7 g/m(2) conidia of any of the isolates, indicating that M. anisopliae has potential as a surface treatment or topical application control strategy. Incorporation of the fungus into freshly excreted cattle dung at rates of between 0.25 and 1 g conidia/kg reduced the emergence of adult midges by up to 98.5% compared to untreated dung indicating that M. anisopliae has the potential to control C. brevitarsis larvae in cattle dung. Three of the isolates produced similar mortality rates on adult and immature C. brevitarsis while the fourth isolate produced lower, but still significant, mortality rates on adult and immature stages.

Afferent regulation of oxidative stress in the chick cochlear nucleus.

The chick auditory brain stem has been a useful model system for examining the afferent-dependent signals that regulate postsynaptic neurons. Like other sensory systems, compromised afferent input results in rapid death and atrophy of postsynaptic neurons. The present paper explores the possible contributions of an oxidative stress pathway in determining neuronal fate following deafferentation. Levels of reactive oxygen species, lipid damage measured by 4-hydroxynonenal formation, and a compensatory reactive oxygen species-induced response regulated by glutathione s transferase M1 and the reactive oxygen species-sensitive transcriptional factor, nuclear respiratory factor 1 were examined. Unilateral cochlea removal surgery was performed on young posthatch chicks. Labeling in the cochlear nucleus, nucleus magnocellularis, on opposite sides of the same tissue sections were compared by densitometry. The results showed a dramatic increase in reactive oxygen species in the deafferented nucleus magnocellularis by 6 h following cochlea removal. This increase in reactive oxygen species was accompanied by lipid damage and a compensatory upregulation of both glutathione s transferase M1 and nuclear respiratory factor 1. Double-labeling revealed that glutathione s transferase M1 expression was highest in neurons that were likely to survive deafferentation, as assessed immunocytochemically with Y10b, a marker for ribosomal integrity. Together, these data suggest reactive oxygen species are generated and a compensatory detoxifying pathway is upregulated in the first few hours following deafferentation. This is consistent with the hypothesis that oxidative stress plays a role in determining whether a given neuron survives following deafferentation.

Induction of sister-chromatid exchanges in cultured human cells by an organophosphorous insecticide: malathion.

Because malathion is a widely used organophosphorous insecticide, the effects of non-toxic concentrations (2.5--40 micrograms/ml) on sister-chromatid exchange (SCE) frequencies were determined. Human fetal fibroblasts were exposed once or twice to malathion, with 20 h between exposures. A single exposure to a concentration of 40 micrograms/ml resulted in a highly significant increase in the number of SCEs. After a double exposure, a concentration of 20 micrograms/ml induced an even greater increase in SCE frequencies. Comparison of Sce frequencies after single and double exposures indicated a cumulative effect; the number of exchanges at concentrations of 5 micrograms/ml or higher was significantly greater after the double exposure. An analysis of SCEs by chromosome group showed that exchanges were distributed approximately according to chromosome length.

A poxvirus of primates. I. Growth of the virus in vitro and comparison with other poxviruses.

A primate poxvirus (OrTeCa) isolated from a skin lesion in a rhesus monkey (Macaca mulatta) was studied along with four known poxviruses: vaccinia, monkeypox, swinepox, and Yaba. It grows in established lines of monkey kidney cells at a rate intermediate between that of vaccinia and monkeypox and that of swinepox and Yaba. The cytopathic effects produced by OrTeCa virus resemble those produced by swinepox virus, although, unlike swinepox, it cannot be propagated in porcine cells. Neither can OrTeCa be grown in rabbit kidney or chick embryo cells or on chick chorioallantoic membranes, all of which support the growth of vaccinia and monkeypox viruses. OrTeCa forms plaques about the same size as those of Yaba and swinepox viruses, but they appear earlier; they are morphologically similar to the plaques of vaccinia and monkeypox viruses. The thermal stability of OrTeCa is about the same as that of vaccinia and monkeypox but greater than that of Yaba virus.

A poxvirus of primates. II. Immunology.

OrTeCa poxvirus shares antigens with Yaba virus, as evidenced by two-way crossreactions in complement-fixation and neutralization tests. Antibodies produced by vaccinia and monkeypox viruses showed weak complement-fixation reactions with OrTeCa viral antigen, but neutralization reactions were negative and cross protection in vivo was not demonstrated. OrTeCa and Yaba virus antisera both contained complement-fixing and neutralizing antibodies against swinepox virus, but swinepox antiserum had no antibodies to any other poxvirus. Long-lasting immunity to the OrTeCa pox disease was produced in monkeys and man by spontaneous infection or vaccination with OrTeCa poxvirus. Complement-fixing antibody titers could be measured in convalescence, but tended to drop to low levels or disappear thereafter. In contrast, neutralizing antibody titers remained high for 3 years, and monkeys that were challenged with OrTeCa virus were reFractory to a second infection.