Despite the fact that cold shock domain proteins (CSDPs) and glycine-rich RNA-binding proteins (GRPs) have been implicated to play a role during the cold adaptation process, their importance and function in eukaryotes, including plants, are largely unknown. To understand the functional role of plant CSDPs and GRPs in the cold response, two CSDPs (CSDP1 and CSDP2) and three GRPs (GRP2, GRP4 and GRP7) from Arabidopsis thaliana were investigated. Heterologous expression of CSDP1 or GRP7 complemented the cold sensitivity of BX04 mutant Escherichia coli that lack four cold shock proteins (CSPs) and is highly sensitive to cold stress, and resulted in better survival rate than control cells during incubation at low temperature. In contrast, CSDP2 and GRP4 had very little ability. Selective evolution of ligand by exponential enrichment (SELEX) revealed that GRP7 does not recognize specific RNAs but binds preferentially to G-rich RNA sequences. CSDP1 and GRP7 had DNA melting activity, and enhanced RNase activity. In contrast, CSDP2 and GRP4 had no DNA melting activity and did not enhance RNAase activity. Together, these results indicate that CSDPs and GRPs help E.coli grow and survive better during cold shock, and strongly imply that CSDP1 and GRP7 exhibit RNA chaperone activity during the cold adaptation process.
BackgroundDespite recent advances in methods for culturing Mycobacterium tuberculosis (MTB), the diagnostic yield of tuberculous pleural effusion (TBPE) remains unsatisfactory. However, unlike repeated sputum cultures of pulmonary tuberculosis, little is known about the role of repeated pleural cultures. We examined whether repeated pleural cultures are associated with increased MTB yield from TBPE.MethodsA multicenter, retrospective cohort study was performed from January 2012 to December 2015 in South Korea. Patients were categorized into two groups: single- or repeated-culture groups. The diagnostic yield of MTB and clinical, radiological, and pleural fluid characteristics were evaluated.ResultsAmong the 329 patients with TBPE, 77 (23.4%) had repeated cultures and 252 (76.5%) had a single culture. Pleural culture was performed twice in all 77 patients in the repeated-culture group at a 1-day interval (inter-quartile range, 1.0–2.0). In the repeated-culture group, the yield of MTB from the first culture was 31.2%, which was similar to that in the single-culture group (31.2% vs. 29.8%, P = 0.887). However, the yield of MTB from the second culture (10/77, 13.0%) was more than that from the first. These results may be attributable to the insufficient immune clearance for MTB invasion into the pleural space between the first and second cultures. Over time, the yield of the second cultures decreased from 17.4% to 6.7% and then 6.3%. Finally, the overall yield of MTB in the repeated- and single-culture groups was 44.2% and 29.8% respectively (P < 0.001).ConclusionsThe results showed that repeated pleural cultures increased MTB yield from TBPE in human immunodeficiency virus-negative individuals. Furthermore, repeated cultures may increase yield when carried out for two consecutive days.
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