China
Africa
Explore chapters and articles related to this topic
An Overview of Parasite Diversity
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
With the publication of Darwin’s Origin of Species came the compelling metaphor of the tree of life (Figure 2.2A). It indicates the origin of all life from common ancestry followed by diversification of lineages of life as represented by branches and twigs on this growing tree. This view emphasizes the vertical acquisition of genetic information from one’s ancestors and assumes there is a core complement of genes that is retained and reflects ancestry, with the gene encoding the RNA found in the small ribosomal subunit (SSU rRNA gene) being one. Some buds on the tree, representing successful lineages of organisms, gave rise to new branches that further diversified, whereas others withered and died out. Such a tree depicts the patterns of historical relatedness among all organisms. Given that such relationships exist, it would be optimal to have our modern taxonomic schemes follow the tree’s branching patterns such that taxonomy mirrors the actual sequence of evolutionary events leading to the diversity we observe. For many years, we had no way to verify if our taxonomic schemes actually reflected evolutionary relationships. For some groups, the availability of fossils exemplifying transitional forms helped to verify taxonomy, but for parasites, which are mostly soft-bodied and have left a poor fossil record (but see Box 7.4), this is usually not an option.
Diamond–Blackfan Anemia
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Ribosome is a cellular structure involved in the translation of messenger RNA (mRNA) to an amino acid sequence (protein). In eukaryotes, ribosome (measuring 80S in size) is separated into the small (40S) and the large (60S) subunit, each of which consists of ribosomal RNA (rRNA) and RP. The large 60S subunit comprises a 5S rRNA, a 28S rRNA, a 5.8S subunit, and ∼46 RP (or RPL, i.e., RP associated with large ribosomal subunit); whereas the small 40S subunit contains 18S rRNA and ∼33 RP (or RPS, i.e., RP associated with small ribosomal subunit). During ribosome biogenesis, RP are synthesized by RP genes in pre-existing ribosomes in the cytoplasm and transferred into the nucleus to assemble with rRNA for new ribosomes. In addition, some RP take part in signaling pathways within the cell that regulate cell division and control apoptosis [9–13].
Ribosomal RNA Processing Sites
Published in S. K. Dutta, DNA Systematics, 2019
Robert J. Crouch, Jean-Pierre Bachellerie
Proceeding from the 5′ to the 3′ direction on the pre-rRNA various types of discontinuities can be found. To date there is but a single example of an interruption in the rRNA of the small ribosomal subunit. In Paramecium192a there is a segment near the 3′ terminus of 18S rRNA that is cleaved from the precursor resulting in two fragments of 18S rRNA which remain together via hydrogen bonds. In certain insects, 5.8S rRNA is found to be comprised of two fragments (“5.8S” + “2S”). In D. melanogaster62 and S. coprophila63 26 and 22 nucleotides, respectively are removed from the pre-rRNA to produce “5.8S” + 2S.
Single-cell genomics for resolution of conserved bacterial genes and mobile genetic elements of the human intestinal microbiota using flow cytometry
Published in Gut Microbes, 2022
Dylan Lawrence, Danielle E. Campbell, Lawrence A. Schriefer, Rachel Rodgers, Forrest C. Walker, Marissa Turkin, Lindsay Droit, Miles Parkes, Scott A. Handley, Megan T. Baldridge
Culturing of individual bacteria represents the classical approach to functionally characterize, and additionally obtain full genomes for, different taxa. While many members of the human intestinal microbiota have been cultured, many more have proven challenging to cultivate.5 One of the first culture-independent approaches developed for characterizing and studying bacterial communities was amplicon sequencing of the 16S rRNA gene.6 The 16S rRNA gene encodes for the structural RNA component of the small ribosomal subunit conserved in all bacteria, and its sequence has been used to assign taxonomy for several decades.7 The advent of high-throughput sequencing has facilitated the application of this technique to analyze complex communities including microbiota samples, providing a cost-effective means to describe bacterial communities in an unbiased way. However, 16S rRNA gene sequencing has numerous limitations, including failing to provide information on the remainder of the bacterial genome, and generally being insufficient to differentiate species- and strain-level differences in complex samples.8
A promising technology for wound healing; in-vitro and in-vivo evaluation of chitosan nano-biocomposite films containing gentamicin
Published in Journal of Microencapsulation, 2021
Hossein Asgarirad, Pedram Ebrahimnejad, Mohammad Ali Mahjoub, Mohammad Jalalian, Hamed Morad, Ramin Ataee, Seyyedeh Saba Hosseini, Ali Farmoudeh
Gentamicin (GNT) is an aminoglycoside with high efficiency against gram-negative bacterial infections. Aminoglycosides attack small ribosomal subunit and attach to the 16 s-RNA inducing discontinuation of the translation process in protein biosynthesis (Qi et al. 2004). By preparing the CHI biocomposite and loading the GNT, it is possible to increase the drug’s penetration into the bacterial cytoplasm. This article aimed to prepare GNT NPs and loading them in the CHI biocomposite. The physicochemical properties of the formulation and its efficacy in surgical wound healing were studied using animal models of Wistar rats.
Analysis of the Escherichia coli extracellular vesicle proteome identifies markers of purity and culture conditions
Published in Journal of Extracellular Vesicles, 2019
Jiwon Hong, Priscila Dauros-Singorenko, Alana Whitcombe, Leo Payne, Cherie Blenkiron, Anthony Phillips, Simon Swift
First, a combination of all eight UPEC-derived EV samples were analyzed simultaneously in the iTRAQ#1 experiment, and all eight Nissle samples in the iTRAQ#2 experiment (Table 1) to identify the overall EV proteomes for each strain, irrespective of growth or purification conditions. The number of peptides and proteins identified in the two iTRAQ experiments are summarized in Table 2 with a total of 205 and 189 proteins identified in UPEC and Nissle EV samples, respectively. Of these, 130 proteins were common to both UPEC and Nissle EVs, 75 were unique to UPEC EV and further 59 in Nissle EV only (Supplementary Data 6; Venn diagram in Figure 2(a)). Outer membrane proteins like ferrienterobactin receptor FepA, outer membrane protein OmpA, and penicillin-binding protein activator LpoA were found to be abundant (based on “N”, the rank of specified protein relative to all other proteins in the list of detected proteins) and commonly present in both UPEC and Nissle EVs. Hemolysin was N = 1 and had the highest “Unused ProtScore” (the amount of total unique peptide evidence related to a given protein), and the highest “Peptides (95%)” score (the number of distinct peptides having ≥95% confidence), and was identified only in UPEC EV, confirming that this well-known virulence factor [27] is highly abundant in EVs of the pathogenic strain. GO functional enrichment analysis (full results in Supplementary Data 7) highlighted significant enrichments (Bonferroni-corrected p values <0.05) – some common between the strains and some unique to a strain due to their protein variability (Figure 2(b–d)). In both UPEC and Nissle EVs, cell outer membrane components (GO:0009279) were highly enriched, but bacterial inner membrane components (GO:0005886) were significantly depleted (Figure 2(c)), supporting the outer membrane origin of EVs [14]. In contrast, ribosome-related GO terms such as ribosome assembly (GO:0042255), cytosolic small ribosomal subunit (GO:0022627) and rRNA binding (GO:0019843) were uniquely enriched in UPEC EV, whereas proteins involved in glycolytic process (GO:0006096) and ligase activity (GO:0016874) were enriched in Nissle EV, indicating some differences between the strains (Figure 2(b–d)).