CENP-B-mediated DNA loops regulate activity and stability of human centromeres.

Chromosome inheritance depends on centromeres, epigenetically specified regions of chromosomes. While conventional human centromeres are known to be built of long tandem DNA repeats, much of their architecture remains unknown. Using single-molecule techniques such as AFM, nanopores, and optical tweezers, we find that human centromeric DNA exhibits complex DNA folds such as local hairpins. Upon binding to a specific sequence within centromeric regions, the DNA-binding protein CENP-B compacts centromeres by forming pronounced DNA loops between the repeats, which favor inter-chromosomal centromere compaction and clustering. This DNA-loop-mediated organization of centromeric chromatin participates in maintaining centromere position and integrity upon microtubule pulling during mitosis. Our findings emphasize the importance of DNA topology in centromeric regulation and stability.

Isolation and Characterization of Bacteria and Fungi Associated with Agarwood Fermentation.

Agarwood oil, often called attar, is a valuable perfume retainer derived from Aquilaria malaccensis. It is obtained through a process of fermentation followed by distillation. The microbes involved in fermentation during agarwood processing have neither been documented nor their role in the process deciphered yet. The present study characterizes the fungi and bacteria engaged in the agarwood fermentation and assesses their colony forming units (CFU) in three categories of agarwood fermentation broth (AFB) collected from three small-scale industries of Hojai, Assam at varying time points. It was interesting to note that grade-A AFB contained the highest CFU count for both bacteria and fungi; the metabolite profile also revealed that the oil obtained from grade-A agarwood comprised of the highest number of compounds. The CFU count increased from 0 to 21 days during fermentation. A total of 105 bacteria and 9 fungi were isolated from 3 different grades of AFB. Shannon index (H' = 0.81) was observed maximum in grade-C AFB and fisher index (α = 2.6) observed maximum for grade-A AFB. The genus Bacillus with a Pi value of 0.61 exhibited dominance among isolated bacteria, while the genus Galactomyces was dominant among fungi with a Pi value of 0.43. The metabolite profiles of three grades of oil obtained after fermentation and one solvent extracted (S.E.) grade agarwood oil analyzed using GC-MS, which showed distinct differences among the oil. The outcomes of this study are expected to create new opportunities for improving oil production methods by modulating biochemical processes involved in fermentation.