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Biology of microbes
Published in Philip A. Geis, Cosmetic Microbiology, 2006
A little more complexity appears when we look at the basal body of the bacterial flagellum. It is embedded within the bacterial cell wall and consists of a number of rings that vary, depending on whether the bacterium is Gram-negative or Gram-positive. A hook links the filament and the basal body. The basic difference between Gram-negative and Gram-positive flagella is the number of basal body rings. Gram-negative bacteria usually have four basal body rings. The first two rings are attached to the outer membrane (L-ring) and peptidoglycan layer (P-ring). The inner two rings contact the periplasmic space (S-ring) and the plasma membrane (M-ring). The Gram-positive flagellum has only two rings: one attached to the plasma membrane and the other attached to the peptidoglycan.
Myofibrillar Protein Synthesis Following Ingestion of Soy Protein Isolate at Rest and After Resistance Exercise in Elderly Men
Published in Chad Cox, Clinical Nutrition and Aging, 2017
Yifan Yang, Tyler A. Churchward-Venne, Nicholas A. Burd, Leigh Breen, Mark A. Tarnopolsky, Stuart M. Phillips
Participants reported to the laboratory at ~0700 in a 10 h post-absorptive state. Upon arriving at the laboratory, a baseline breath sample was collected to measure 13CO2 enrichment via isotope ratio mass spectrometry (BreathMat Plus; Finnigan MAT GmbH, Bremen, Germany). A plastic catheter was then inserted into an antecubital vein and a baseline blood sample was collected before initiating a 0.9% saline drip to keep the catheter patent for repeated blood sampling during the infusion trial. After baseline breath and blood samples were taken, a bout of unilateral knee-extensor resistance exercise was performed on a guided-motion knee extension machine. The exercise bout involved 3 sets, using a pre-deter-mined load based on each participant’s 10RM. Each set was completed within ~25 s with an interest rest interval of 2 min. Immediately following exercise, blood and breath samples were obtained and a second catheter was inserted into the contralateral antecubital vein to prime the bicarbonate pool with NaH13CO2 (2.35 μmol·kg). Thereafter, priming doses of [1-13 C] leucine (7.6 μmol·kg-1) and L-ring-13 C6 phenylalanine (2 μmol·kg-1; 99 atom percent; Cambridge Isotopes, Andover, MA) were introduced, before a continuous infusion of L-[1-13 C] leucine (7.6 μmol·kg-1·h-1) and L-ring-13 C6 phenylalanine was initiated (0.05 μmol·kg-1·min-1). Arterialized blood samples were obtained by wrapping the forearm in a heating blanket (45°C) for the duration of the infusion; a procedure we have found completely arterializes venous blood sampled from a hand vein. Blood samples were processed as previously described [5]. Immediately after post-exercise blood and breath samples had been obtained, participants consumed water (0 g) or a drink containing 20 g or 40 g of either whey or soy protein isolate (W20, W40, S20, S40) dissolved in 400 mL water. The whey protein was generously donated by PGP International (IWPI 9500, California, USA), while the soy protein was generously donated by the Solae Company (SUPRO 660-IP, St Louis, MO). The amino acid composition of both the whey and soy protein drinks is provided in Additional file 2: Table S2. On the basis of a leucine content of 10% in whey and 8% in soy, and a phenylalanine content of 3% in whey and 5% in soy protein, drinks were enriched to 8% with [1-13 C] leucine and 8% with 13 C6 phenylalanine to minimize disturbances in isotopic steady state; an approach that we have validated [22]. Complete drink consumption was considered t = 0 min and the isotopic infusion was continued until t = 240 min. During the remainder of the infusion, arterialized blood and breath samples were obtained to confirm steady state and measure leucine oxidation and MPS as previously described [5,8]. At the end of the infusion (t = 240 min) muscle biopsies were obtained (described below).
Outer membrane vesicles induce the mussel plantigrade settlement via regulation of c-di-GMP
Published in Biofouling, 2023
Guanju Wu, Xiao-Meng Hu, Li-Hua Peng, Wen Zhang, Xiao Liang, Sergey Dobretsov, Jin-Long Yang
In our study, the OMV biogenesis tolB gene deletion caused a reduction in the concentration of c-di-GMP and bacterial motility, and an increase in biofilm formation. This contradicts previous reports, which have indicated that high c-di-GMP level is associated with increased biofilm and low c-di-GMP level with increased motility (Elgamoudi et al. 2022; Piazza et al. 2022). Interestingly, the deficiency in the 01912 gene has been found to increase c-di-GMP levels and biofilm formation, while reducing motility (Peng et al. 2020), which is consistent with comments of the reviewer. Yet another noteworthy possibility is that deletion of the tolB gene could damage the precise location and stability of the L-ring and rod components in the E. coli flagella, leading to the disintegration of the flagellum matrix, which resulting in reduced bacterial motility and increased biofilm formation ability (Hirakawa et al. 2019). As we know, bacterial flagella, as a moving organ, can help bacteria to have mobility and have a vital impact on biofilm formation (Aschtgen et al. 2019). This may help explain the decrease in bacterial motility of the ΔtolB strain and the increase in biofilm formation in P. marina.