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Biomedical subjects

D Dean

Publications and source records attributed to D Dean.

At least 163 records · Page 9Linked to original sources
PubMed1980

Feedback regulation of ribosomal protein gene expression in Escherichia coli: structural homology of ribosomal RNA and ribosomal protein MRNA.

Certain ribosomal proteins (r proteins) in Escherichia coli, such as S4 and S7, function as feedback repressors in the regulation of r-protein synthesis. These proteins inhibit the translation of their own mRNA. The repressor r proteins so far identified are also known to bind specifically to rRNA at an initial stage in ribosome assembly. We have found structural homology between the S7 binding region on 16S rRNA and a region of the mRNA where S7 acts as a translational repressor. Similarly, there is structural homology between one of the reported S4 binding regions on 16S rRNA and the mRNA target site for S4. The observed homology supports the concept that regulation by repressor r proteins is based on competition between rRNA and mRNA for these proteins and that the same structural features and of the r proteins are used in their interactions with both rRNA and mRNA.

Bacterial Proteins↗
PubMed1980

Feedback regulation of ribosomal protein gene expression in Escherichia coli.

The structural genes for Escherichia coli ribosomal protein (r-protein) genes L1, S4, and S11 were inserted into a plasmid vector containing the lac operator and promoter such that the synthesis of L1, S4, and S11 was controlled by lac regulatory elements. Synthesis of L1, S4, and S11 was stimulated by addition of an inducer of the lac operon (isopropyl thiogalactoside) to exponentially growing cells. Elevated synthesis of L1 caused a specific decrease in L11 synthesis, whereas overproduction of S4 resulted in lowered synthesis of S13 and L17. Stimulation of L1 or S4 synthesis also inhibited cell growth. Overproduction of S11 did not affect synthesis of other r-proteins or alter growth. These results confirm previous in vitro studies [Yates, J. L., Arfsten, A. E. & Nomura, M. (1980) Proc. Natl. Acad. Sci. USA 77, 1837-1841] and support the hypothesis that certain r-proteins have the capacity to selectively inhibit synthesis of r-proteins whose genes are in the same operon as their own.

Bacteriophage lambda↗
PubMedDate not supplied

Improved sensitivity of a modified polymerase chain reaction amplified DNA probe in comparison with serial tissue culture passage for detection of Chlamydia trachomatis in conjunctival specimens from nepal.

A sensitive means for detecting ocular chlamydial infections is needed to accurately define the epidemiology of trachoma. Tissue culture is considered the "gold standard," yet it is less than 50% sensitive for ocular specimens. The purpose of this study was to improve the detection rate of culture by serial passage and thereby provide a more reliable basis for comparing polymerase chain reaction (PCR) amplified and 32P DNA probes and direct fluorescent antibody (DFA) tests with culture. Ocular exams on 1043 individuals were scored for trachoma; 252 (24%) had moderate/severe intensity. A total of 1214 conjunctival samples were collected and passaged twice. Of 1053 samples, 276 negative at second passage were passaged an additional two times. The vast majority (93%) of all culture-positive samples were recovered by first passage. Only 80 of 252 cases (32%) with moderate/severe intensity were diagnosed by culture. The sensitivity of the 32P and PCR probes were 87% and 90%, respectively. For DFA versus culture, the sensitivity rate was 48%. Our results indicate that true rates of infection can not be accurately determined by culture even with serial passage. The sensitivity of the probes and DFA tests may, therefore, be higher. The PCR probe holds promise as an epidemiologic tool for studying chlamydial ocular infections.

Chlamydia trachomatis↗