Experimental and Theoretical Mutation of Exciton States on the Smallest Type-I Photosynthetic Reaction Center Complex of a Green Sulfur Bacterium Chlorobaclum tepidum.

The exciton states on the smallest type-I photosynthetic reaction center complex of a green sulfur bacterium Chlorobaculum tepidum (GsbRC) consisting of 26 bacteriochlorophylls a (BChl a) and four chlorophylls a (Chl a) located on the homodimer of two PscA reaction center polypeptides were investigated. This analysis involved the study of exciton states through a combination of theoretical modeling and the genetic removal of BChl a pigments at eight sites. (1) A theoretical model of the pigment assembly exciton state on GsbRC was constructed using Poisson TrESP (P-TrESP) and charge density coupling (CDC) methods based on structural information. The model reproduced the experimentally obtained absorption spectrum, circular dichroism spectrum, and excitation transfer dynamics, as well as explained the effects of mutation. (2) Eight BChl a molecules at different locations on the GsbRC were selectively removed by genetic exchange of the His residue, which ligates the central Mg atom of BChl a, with the Leu residue on either one or two PscAs in the RC. His locations are conserved among all type-I RC plant polypeptide, cyanobacteria, and bacteria amino acid sequences. (3) Purified mutant-GsbRCs demonstrated distinct absorption and fluorescence spectra at 77 K, which were different from each other, suggesting successful pigment removal. (4) The same mutations were applied to the constructed theoretical model to analyze the outcomes of these mutations. (5) The combination of theoretical predictions and experimental mutations based on structural information is a new tool for studying the function and evolution of photosynthetic reaction centers.

Roles of Probiotics in Reduction of Neonatal Jaundice in Term Newborns.

Objective: the primary objective was to examine the effect of Bifidobacterium on decreasing the bilirubin level in term neonates delivered by Caesarean Section (CS). Materials and Methods: A total of 153 healthy term neonates delivered by CS were included in this study and were divided into the non-probiotic group (n=99) and probiotic group (n=54) based on the history of probiotics administration. There were no infants who underwent phototherapy. A total of 20 doses of probiotics were given orally from the first day of life. The transcutaneous bilirubin (TcB) levels were measured every day for the first 5 days of life. Data of each infant and mother were gathered from medical records. Results: The bilirubin level per day (day-1 to day-5) in the non-probiotic group was no different from the probiotic group. Differences in bilirubin level between day-5 and day-1, and also between day-5 and day-2 were not different between the two groups. There was a significant (p = 0.03) body weight gain in the probiotic groups with a mean of 36.09 ± 8.23 gram/day. No obvious adverse reactions were seen in both the non-probiotic group and probiotic group. Conclusions: Our findings suggest no significant effects of probiotics on lowering bilirubin levels in the first five days of life. Also, probiotics have a positive effect on body weight gain in healthy term infants, and it is safe to be given to newborns.