RESUMO
BACKGROUND: R2 elements are a clade of early branching Long Interspersed Elements (LINEs). LINEs are retrotransposable elements whose replication can have profound effects on the genomes in which they reside. No crystal or EM structures exist for the reverse transcriptase (RT) and linker regions of LINEs. RESULTS: Using limited proteolysis as a probe for globular domain structure, we show that the protein encoded by the Bombyx mori R2 element has two major globular domains: (1) a small globular domain consisting of the N-terminal zinc finger and Myb motifs, and (2) a large globular domain consisting of the RT, linker, and type II restriction-like endonuclease (RLE). Further digestion of the large globular domain occurred within the RT. Mapping these RT cleavages onto an updated model of the R2Bm RT indicated that the thumb of the RT was largely protected from proteolytic cleavage. The crystal structure of the large globular domain of Prp8, a eukaryotic splicing factor, was a major template used in building the R2Bm RT model, particularly the thumb region. The large fragment of Prp8 consists not only of a RT similar to R2Bm, but also an RLE and a linker connecting the two regions. The linker sequences adjacent to the RLE in LINEs and Prp8 share a set of two important α-helices and a (presumptive) knuckle/ßßα structural motif that are closely associated with the thumb. The RLEs of LINEs and Prp8 share a unique catalytic core residue spacing as well as other key residues. CONCLUSIONS: The protein encoded by RLE LINEs consists of two major globular domains. The larger of the two globular domain contains the RT, linker, and RLE and is similar to the large fragment of the spliceosomal protein Prp8. The similarities are suggestive of possible common ancestry.
RESUMO
The present study investigates into some socio-economic, demographic, and nutritional features that can predispose Bangladeshi children to malnutrition and Shigella flexneri infection. Significant prognostic indicators associated with malnutrition were mother's illiteracy (unadjusted odds ratio, OR = 2.580; 95% confidence interval, CI = 1.134-5.867 and adjusted odds ratio, ORa, 3.814; 95% CI = 1.124-12.943), low birth weight (OR = 3.143; 95% CI = 1.2-8.232 and ORa = 2.404; 95% CI = 0.870-6.644) and poor socioeconomic status (OR = 2.549; 95% CI = 1.382-4.701 and ORa = 1.808; 95% CI = 0.852-3.838). Age was the strongest predictor for the acquisition of S. flexneri infection in the studied population (OR = 5.472; 95% CI = 2.583-11.592 and ORa = 5.808; 95% CI = 2.420-13.942). The severity of malnutrition was significantly (P = 0.033) related to seroprevalence of S. flexneri infection. To reduce malnutrition emphasis should be given on controlling the incidence of low birth weight, improving the literacy status especially of mothers and narrowing the gap between different socio-economic levels. Malnourished children should be examined for severity and direct intervention therapy should be given when necessary.
