ABSTRACT
Plasmid constructs containing a putative Trypanosoma cruzi rRNA promoter and transcription start point upstream from the bacterial chloramphenicol acetyltransferase (CAT) reporter gene were transfected into cultured T. cruzi epimastigotes to verify the presence of a promoter activity. Constructs bearing the putative promoter and a 3' trans-splicing acceptor site in the proper orientation yielded approx. two orders of magnitude greater CAT expression than that previously observed with the T. cruzi spliced leader (SL) gene promoter. In contrast, similar constructs lacking the known 3' splice site yielded reduced but readily measurable expression suggesting that sequences near the promoter may function as cryptic 3' splice sites. A repeated sequence upstream from the putative basal rRNA promoter in a position analogous to rRNA gene enhancer elements in other eukaryotes did not enhance expression from the T. cruzi rRNA promoter. Finally, these constructs were functional in some but not all T. cruzi isolates, and were inactive in other kinetoplastid species, suggesting that the T. cruzi rRNA promoter may have a limited host range.
Subject(s)
Gene Expression Regulation , Promoter Regions, Genetic , RNA, Protozoan/genetics , RNA, Ribosomal/genetics , Trypanosoma cruzi/genetics , Animals , Chloramphenicol O-Acetyltransferase/biosynthesis , Chloramphenicol O-Acetyltransferase/genetics , DNA-Directed RNA Polymerases/metabolism , Genes, Reporter , Kinetoplastida/genetics , Protozoan Proteins/metabolism , RNA Splicing , Recombinant Fusion Proteins/biosynthesis , Species Specificity , Transcription, GeneticABSTRACT
The prevalences of several sexually transmitted diseases (STD) among patients attending a public STD clinic were determined in a prospective study. Rates of gonorrhea, syphilis, genital herpes, trichomoniasis, nongonococcal urethritis, pediculosis pubis, scabies, and venereal warts were ascertained according to sex, sexual preference, and race. Numbers of cases of diseases not routinely reported to most public health agencies exceeded numbers of cases of diseases that are routinely reported. Rates of gonorrhea were higher among men than among women and higher among blacks than among whites. Syphilis was most common among homosexual men. Trichomoniasis was three times more frequent among blacks than among whites. Rates of nongonococcal urethritis among heterosexual men were almost twice those among homosexual men. Whites were more likely than blacks to have pediculosis pubis, scabies, and venereal warts. STD not routinely reported to most public health agencies are commonly seen in public clinics, and rates vary according to sex, sexual preference, and race.
