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Bacteria
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
All of the clinically significant bacteria are chemoorganotrophs (heterotrophs). That is, most of their nutritional carbon must be supplied to them as preformed carbon compounds that contain carbon to carbon chemical bonds; such as are found in amino acids, proteins, sugars, etc., that when metabolized, release energy in a form that can be used by the organotroph.
Structure and Evolution of the Small Blue Proteins
Published in René Lontie, Copper Proteins and Copper Enzymes, 1984
The bacterial species mentioned fall in a rather close group. Pseudomonas, Alcaligenes, and Bordetella are found in the Pseudomonaceae, a family of free-living Gram-negative aerobic bacteria. Paracoccus belongs to the Enterobacteriaceae, but resembles several species of the genera Alcaligenes and Pseudomonas, the main difference being the coccoid shape during exponential growth and the absence of flagellation.18Paracoccus denitrificans and some species of Thiobacillus, in particular the denitrifying strains, are in turn quite similar and were earlier confused.19 Doudoroff20 summarizes the situation: “On many grounds, it seems likely that the genera Paracoccus, Pseudomonas, and Alcaligenes are very closely related to each other and that at least the facultatively organotrophic species of the genus Thiobacillus belong in the same generic cluster.”
Beneficial Lactic Acid Bacteria
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
LAB representatives are gram-positive, nonsporulating, catalase-negative, anaerobic or microaerophilic, acid-tolerant, organotrophic, and strictly fermentative rods or cocci producing lactic acid as a major end product (König and Fröhlich 2009). Cell wall of LAB has the typical gram-positive structure formed by a thick, multilayered peptidoglycan envelope decorated with proteins, teichoic acids, and polysaccharides and surrounded in genus Lactobacillus by an outer shell of proteins packed in a paracrystalline layer (S-layer) (Delcour et al. 1999). Lactobacillus S-layer proteins differ from those of other bacteria in their smaller size and highly predicted pI. The positive charge in S-layer proteins is concentrated in the more conserved cell wall binding domain, which can be either N- or C-terminal depending on the species. The more variable domain is responsible for the self-assembly of the monomers into a periodic structure (Hynönen and Palva 2013). Peptidoglycan is the main constituent of the gram-positive cell wall consisting of glycan chains composed of alternating N-acetylglucosamine and N-acetylmuramic acid and linked by β-1,4 bonds. In most bacterial species, peptidoglycan basic structure is partially altered; either glycan chains undergo N-deacetylation or O-acetylation or free carboxyl groups of the amino acids in the peptide chains are amidated. Teichoic acids, anionic polymers made up of alditol-phosphate repeating units, also can be modified by replacing free hydroxyl groups of the alditol-phosphate chains with various sugars or D-alanin. Bacterial polysaccharides of cell wall exhibit great diversity in sugar composition, linkage, branching, and substitution. The structural divergence shown by these cell wall components may underlie differences in processes such as autolysis and characteristics such as stress resistance, probiotic properties, or phage sensitivity (Chapot-Chartier and Kulakauskas 2014). The extracellular and surface-associated proteins also can be involved in cell wall metabolism, degradation, and uptake of nutrients, communication, and binding to substrates or hosts (Zhou et al. 2010).
MET inhibitors in cancer: pitfalls and challenges
Published in Expert Opinion on Investigational Drugs, 2020
Helena Oliveres, Estela Pineda, Joan Maurel
The hepatocyte growth factor (HGF) or scatter factor (SF) is an epithelial factor derived from fibroblasts and mesenchymal cells. Identified as a potent cellular mitogen in cultured hepatocytes[1], it has the ability to promote tissue repair and organ regeneration after injury. On top of mitogenic responses, it has morphogenic, motogenic, angiogenic and antiapoptotic activities [2]. HGF participates as an organotrophic factor in the regeneration and protection of various organs (liver, lung, kidney, stomach, pancreas, heart, brain), acting in an endocrine, autocrine and/or paracrine manner. In turn, it also participates in the embryonic development of liver, kidney, lung, mammary gland, muscle and neuronal tissue [3]. Although several phases I and II clinical trials with MET inhibitors have been conducted with monoclonal antibodies and tyrosine kinase receptor inhibitors (MET selective or nonselective TKI), prospective biomarkers' efficacy has not been usually evaluated. In this review, we focus on pitfalls of early trials development and we speculate biological reasons for MET inhibitor phase III clinical trial failures.
Epibiotic bacteria on the carapace of hawksbill and green sea turtles
Published in Biofouling, 2023
Javad Loghmannia, Ali Nasrolahi, Sergey Dobretsov
The composition of bacteria in different species of sea turtles from the same habitat was different. Our results from the SIMPER analysis showed that the genera Pseudomonas, Iamia, Lewinella, Chroococcidiopsis, and Phormidium contributed to these differences. Lewinella is a Gram-negative, aerobic chemo-organotrophic organism previously isolated from the marine snail Nodilittorina trochoides (Khan et al. 2007). Chroococcidiopsis is an endolithic cyanobacterium that is resistant to desiccation and UV radiation (Cockell et al. 2005), which may explain its occurrence in the carapace of sea turtles. The presence of a toxin-producing cyanobacterium Phormidium (McAllister et al. 2016) could be an indication of the possible negative effect of this species on sea turtles and the spread of this cyanobacterium due to anthropogenic factors. Although epibiotic bacteria had not been compared with different species of sea turtles before this study, the species-specific nature of epibiotic bacterial communities has been previously suggested (Weinbauer et al. 2019). For example, a previous study comparing epibiotic bacteria on coral species found that the community on Madrepora oculata was dominated by Gammaproteobacteria, while that on Lophelia pertusa was dominated by Alphaproteobacteria (Meistertzheim et al. 2016). However, our study suggested that different sampling locations do not significantly affect the bacterial communities associated with sea turtles. This is in contrast to previous studies that showed that barnacle composition varied among loggerhead turtles from different habitats (Senties et al. 1999).