• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.569-575
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• 2006

The 530 stem-loop is a 46 nucleotide stem-loop structure found in all small-subunit ribosomal RNAs. Phylogenetic and mutational studies by others suggest the requirement for Watson-Crick interactions between the nucleotides 505-507 and 524-526 (530 pseudoknot), which are highly conserved. To examine the nature and functional significance of these interactions, a random mutagenesis experiment was conducted in which the nucleotides in the proposed pseudoknot were simultaneously mutated and functional mutants were selected and analyzed. Genetic analysis revealed that the particular nucleotide present at each position except 524 was not exclusively critical to the selection of functional mutants. It also indicated that basepairing interactions between the positions 505-507 and 524-526 were required for ribosomal function, and much weaker base-pairing interactions than those of the wild-type also allowed high ribosomal function. Our results support the hypothesis that the 530 pseudoknot structure may undergo a 'conformational switch' between folded and unfolded states during certain stages of the protein synthesis process by interacting with other ligands present in its environment.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.4
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• pp.530-536
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• 2010

Cdc25B is a mitotic regulator that might act as a starter phosphatase to initiate the positive feedback loop at the entry into mitotic (M) phase. In the present study, distribution of Cdc25B mRNA in duodenal mucosa of the chicken was demonstrated by means of in situ hybridization histochemistry (ISHH) using sense and antisense digoxigenin (DIG)-labeled RNA probes. The results showed that there were many labeled cells distributing in the duodenal mucosa of the adult chicken. Of these labeled cells, 81.60${\pm}$9.63% of Cdc25B mRNA positive cells was distributed in the basilar part and mid-portion of the intestinal gland and 36.21${\pm}$8.81% in the middle and basilar portion of villi of the small intestine of the chicken, respectively. Most of these labeled cells were positive in the regions of the stem cell and proliferation. The signals of ISHH decreased from basilar to upper part in the crypt of Lieberkuhn and weakened in the inferior villi of the duodenum. Moreover, the positive signals were both in the cytoplasm and cell nucleus. However, the labeled cells were negative in both the lamina muscularis mucosae and muscular layer. The results of ISHH suggested the existence of Cdc25B mRNA and vigorous proliferation activities in the duodenal mucosa of adult chicken, replenishing the cells which had sloughed off from the superior part of the villus. Our results provide some molecular evidence for a regular pattern of avian intestinal epitheliosis and functional partition and provide an approach to further study of the locations of Cdc25B in the chicken.