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A rapid method has been developed to visualize cell surface receptors in the SEM. Thus mannan at the surface of Candida utilis cells was localized by stabilized colloidal gold granules coated with either anti-mannan antibodies or Con A.

Previous experiments have shown that the behavior of experimental mucormycotic infection shows striking differences in the normal as compared with the metabolically abnormal host. In rabbits with acute alloxan diabetes and acidosis the inoculation of the fungus produced an acute spreading and fatal infection while the fungus lesions in the metabolically normal host remained confined to the site of inoculation and healed spontaneously (I). These observations referred primarily to fully developed acute lesions. Therefore, the present experiments were designed to compare the development of the inflammatory response to mucormycosis in normal and metabolically abnormal rabbits at various time intervals during the first 24 hours after inoculation. MethodsWhite male rabbits ranging from 1800 to 2300 gin. in weight were used. In 38 animals acute alloxan diabetes with acidosis was produced and the presence of hyperglycemia, glycosuria, and ketonuria were determined as previously described (1). The presence of fully developed acute diabetes was established by blood sugar levels above 400 rag. per cent and 4 plus ketonuria. Forty-one rabbits received no alloxan and served as controls. All 79 animals were inoculated intradermally, without anesthesia, in four sites on the shaved back with 0.3 ml. of a standardized spore suspension of Rhizopus oryzae to which 1 per cent of sterilized India ink had been added to facilitate the identification of the inoculum in the tissues (1). 1Both diabetic and control rabbits were sacrificed at 5, 10, 20, 30, 45, 60 minutes and at 2, 4, 6, 12, and 24 hours after inoculation by intravenous injection of air preceded by 1 cc. of undiluted nembutal administered rapidly. The skin lesions were excised, fixed in Helly's fluid, and each lesion was examined in its entire extent, with multiple sections stained with Giemsa. Complete autopsies were performed and histologic preparations of tissues other than

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A fatal case of human encephalitis has been observed for which our results indicate that Semliki Forest virus (SFV) was the etiologic agent. This is surprising in view of the fact that this virus, which has been widely studied, was believed to be one of the arboviruses nonpathogenic for man. Described are the clinical course, the virological examinations performed, and the histopathological findings in the central nervous system.

Sera from certain rabbits bearing SchmidtRuppin strain Rous sarcoma virus (RSV)induced tumors precipitated p6Osrc from chicken cells transformed by the homologous virus as well as by other strains [Prague strain RSV, Bryan high-titer strain RSV, and Bratislava 77 strain of avian sarcoma virus (ASV)J, the molecular weights (Mrs) In order to test whether the protein kinase reaction is directly catalyzed by p6Osrc, we compared the in vitro temperature sensitivities of the kinase activities from cells infected by transformation-temperature-sensitive mutant and parental wild-type virus. The first-order rate constant for the inactivation of the kinase from extracts of cells infected by the mutant virus was 2-fold greater than that from cells infected by wild-type virus. This result implicates the protein kinase as an enzymatic activity of the src gene product, the p60src. Concomitant with the loss of the kinase activity by heat inactivation, p60src loses 60-70% of its phosphate content. The kinetics of dephosphorylation exactly parallel those for the inactivation of the kinase activity, suggesting that the p6osrc kinase is itself dependent on phosphorylation for its activity. In recent papers, Erikson and coworkers have shown that sera from rabbits bearing tumors induced by the Schmidt-Ruppin (SR) strain of Rous sarcoma virus (RSV) precipitated a sarcoma virus-specific protein of molecular weight (Mr) 60,000 from extracts of SR-transformed chicken embryo cells (1), as well as from various mammalian cells transformed by the same virus (2). The in vitro cell-free translation of the 3' one-third of the RSV genome, the region known to. contain the viral transforming information [the src gene (3, 4)1, yielded a protein of the same molecular weight and similar peptide composition (5, 6). Hence, this protein is thought to be responsible for RSVinduced cell transformation and has been named p6Osrc. A protein kinase activity is associated with the p6Osrc, because immunoprecipitates of p60src incorporate 32P from [y-32P]ATP into the Mr 53,000 subunit of IgG (7). This activity was greatly reduced (though not completely lost) in immunoprecipitates prepared from cells that were infected by a transformationdefective temperature-sensitive (ts) mutant of avian sarcoma virus (ASV) when the cells were grown at the nonpermissive temperature for transformation. These data were interpreted to indicate that the kinase activity found in immunoprecipitates of p60src is an enzymatic activity of the protein and not of a contaminant (7).In the present study we show that p60srC can be precipitated by certain rabbit sera from extracts of cells infected by several different strains of ASV and that all these immunoprecipitates exhibit a kinase activity. p60src proteins from cells infected with wild-type and transformation-defective (T class) ts mutants of RSV were compared with respect to protein kinase inactivation kinetics at 42°C. The results obtained show that, after in vitro incubations, the protein kinase activity from cells infecte...