Genetic Characterization of Escherichia coli O157:H7 Strains Isolated from the One-Humped Camel (Camelus dromedarius) by Using Microarray DNA Technology

From the Camelidae family members, several serotypes of Escherichia coli (E. coli) have recently been isolated from diarrhoeic and non-diarrhoeic faecal samples. To date Shiga toxin-producing E. coli (STEC) strains have never been typed in one-humped camel (Camelus dromedarius). In the present study, two E. coli O157:H7 strains isolated from sick dromedaries were investigated. Virulence gene profiles were determined using a custom E. coli virulence DNA microarray, composed of 70-mer oligonucleotide probes targeting 264 virulence or related genes of known E. coli pathotypes. Both strains displayed positive hybridization signals for the Locus of enterocyte effacement (LEE) gene probes (ler, eae, espA, espB, tir genes), two Shiga toxin probes (stx1 and stx2), the O157 O-antigen specific probe, various virulence plasmid (pO157) probes like katP in addition to other accessory virulence genes characterized in STEC.     

Photosynthetic electron transfer through the cytochrome b6f complex can bypass cytochrome f

The cytochrome b(6)f complex is an obligatory electron transfer and proton-translocating enzyme in all oxygenic photosynthesis. Its operation has been described by the "Q-cycle." This model proposes that electrons are transferred from plastoquinol to plastocyanin (the reductant of P700 in Photosystem I) through, obligatorily in series, the iron-sulfur and the cytochrome f redox centers in the cytochrome b(6)f complex. However, here we demonstrate that (a) the iron-sulfur center-dependent reductions of plastocyanin and P700 are much faster than cytochrome f reduction, both in Chlamydomonas reinhardtii cytochrome f mutants and in the wild type, and (b) the steady-state photosynthetic electron transport does not correlate with strongly inhibited cytochrome f reduction kinetics in the mutants. Thus, cytochrome f is not an obligatory intermediate for electrons flowing through the cytochrome b(6)f complex. The oxidation equivalents from Photosystem I are delivered to the high potential chain of the cytochrome b(6)f complex both at the cytochrome f level and, independently, at another site connected to the quinol-oxidizing site, possibly the iron-sulfur center.     

Prevention of adhesion bands by ibuprofen‐loaded PLGA nanofibers

In this study, prevention of the adhesion bands and inflammatory features has been investigated using poly (lactic‐co‐glycolic acid)‐ibuprofen (PLGA‐IB) nanofibrous meshes in a mice model. To find the optimized membrane for prevention of postoperative adhesion bands, we have compared PLGA‐IB group with PLGA, IB, and control groups in a mice adhesion model. Two scoring adhesion systems were used to represent the outcome. According to the results obtained in this study, the PLGA‐IB nanofiber membrane showed a greater reduction in adhesion band than other groups. In conclusion, among FDA‐approved polymers and drugs, PLGA‐IB meshes could be applicable as a potential candidate for prevention of postoperative abdominal inflammation and adhesion bands formation. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:990–997, 2016     

Top-down analysis of temporal hierarchy in biochemical reaction networks

The study of dynamic functions of large-scale biological networks has intensified in recent years. A critical component in developing an understanding of such dynamics involves the study of their hierarchical organization. We investigate the temporal hierarchy in biochemical reaction networks focusing on: (1) the elucidation of the existence of "pools" (i.e., aggregate variables) formed from component concentrations and (2) the determination of their composition and interactions over different time scales. To date the identification of such pools without prior knowledge of their composition has been a challenge. A new approach is developed for the algorithmic identification of pool formation using correlations between elements of the modal matrix that correspond to a pair of concentrations and how such correlations form over the hierarchy of time scales. The analysis elucidates a temporal hierarchy of events that range from chemical equilibration events to the formation of physiologically meaningful pools, culminating in a network-scale (dynamic) structure-(physiological) function relationship. This method is validated on a model of human red blood cell metabolism and further applied to kinetic models of yeast glycolysis and human folate metabolism, enabling the simplification of these models. The understanding of temporal hierarchy and the formation of dynamic aggregates on different time scales is foundational to the study of network dynamics and has relevance in multiple areas ranging from bacterial strain design and metabolic engineering to the understanding of disease processes in humans.