Transfer of budding Candida albicans yeast cells from the rich, complex medium YEPD to the defined tissue culture medium RPMI 1640 (RPMI) at 37 degrees C and 5% CO2 causes rapid onset of hyphal induction. Among the genes induced under these conditions are hyphal-specific genes as well as genes expressed in response to changes in temperature, CO2 and specific media components. A cDNA library constructed from cells incubated for 20 min in RPMI was differentially screened with yeast (YEPD)- and hyphal (RPMI)-specific probes resulting in identification of a gene expressed in response to culture conditions but not regulated by the yeast-hyphal transition. The deduced gene product displays significant identity to Saccharomyces cerevisiae alpha-agglutinin, encoded by AG alpha 1, an adhesion glycoprotein that mediates mating of haploid cells. The presence of this gene in C. albicans is curious since the organism has not been observed to undergo meiosis. We designate the C. albicans gene ALS1 (for agglutinin-like sequence). While the N- and C-termini of the predicted 1260-amino-acid ALS1 protein resemble those of the 650-amino-acid AG alpha 1, ALS1 contains a central domain of tandem repeats consisting of a highly conserved 36-amino-acid sequence not present in AG alpha 1. These repeats are also present on the nucleotide level as a highly conserved 108 bp motif. Southern and Northern blot analyses indicate a family of C. albicans genes that contain the tandem repeat motif; at least one gene in addition to ALS1 is expressed under conditions similar to those for ALS1 expression. Genomic Southern blots from several C. albicans isolates indicate that the number of copies of the tandem repeat element in ALS1 differs across strains and, in some cases, between ALS1 alleles in the same strain, suggesting a strain-dependent variability in ALS1 protein size. Potential roles for the ALS1 protein are discussed.

No abstract

In an effort to study in detail the nature of the protein product of the human protoorcogene c-myc, we have expressed the gene at high levels in Escherichia coli. The c-myc coding region was taken from a full-length cDNA clone and inserted into a vector designed to express foreign gene products efficiently in E. coli.Pulse-labeling experiments indicated that the rate of expression of c-myc in this thermoind,pcible expression system is very efficient. The product was relatively stable and accumulated to approximately 10% of total cellular protein. A purification protocol was devised which allowed the c-myc protein to be readily purified in quantities sufficient for detailed biochemical and physical analyses. A high-titer polyclonal antiserum was raised against the pure protein and shown tfo immunoprecipitate the p11$am--Yc fusion protein of MC-29-infected quail cells. This antiserum also selectively detects a protein with an apparent molecular weight of 64,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis from a Burlitt lymphoma cell line. We conclude that this 64-kilodalton protein is the human c-myc gene product since the E. coli-made protein exhibits an equivalent molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, even though its calculated molecular weight is 49,000. Furthermore, we demonstrate that the bacterially made human c-myc protein is a DNA-binding protein and that it exhibits a high nonspecific affinity for doublestranded DNA.

Focal cerebral ischemia elicits local inflammatory reaction as demonstrated by the accumulation of inflammatory cells and mediators in the ischemic brain. Interferon‐inducible protein‐10 (IP‐10) is a member of the C‐X‐C chemokine family that possesses potent chemoattractant actions for monocytes, T cells, and smooth muscle cells. To investigate a potential role of IP‐10 in focal stroke, we studied the temporal expression of IP‐10 mRNA after occlusion of the middle cerebral artery in rat by means of northern analysis. IP‐10 mRNA expression after focal stroke demonstrated a unique biphasic profile, with a marked increase early at 3 h (4.9‐fold over control; p < 0.01), a peak level at 6 h (14.5‐fold; p < 0.001) after occlusion of the middle cerebral artery, and a second wave induction 10–15 days after ischemic injury (7.2‐ and 9.3‐fold increase for 10 and 15 days, respectively; p < 0.001). In situ hybridization confirmed the induced expression of IP‐10 mRNA and revealed its spatial distribution after focal stroke. Immunohistochemical studies demonstrated the expression of IP‐10 peptide in neurons (3–12 h) and astroglial cells (6 h to 15 days) of the ischemic zone. To explore further the potential role of IP‐10 in focal stroke, we demonstrated a dose‐dependent chemotactic action of IP‐10 on C6 glial cells and enhanced attachment of rat cerebellar granule neurons. Taken together, the data suggest that ischemia induces IP‐10, which may play a pleiotropic role in prolonged leukocyte recruitment, astrocyte migration/activation, and neuron attachment/sprouting after focal stroke.

Medical SciencesGustin concentration changes relative to salivary zinc and taste in humans (zinc deficiency/zinc treatment/taste dysfunction/salivary proteins/parotid saliva)