Antibiotics Friend and Foe: “From Wonder Drug to Causing Mitochondrial Dysfunction, Disrupting Human Microbiome and Promoting Tumorigenesis”

Mitochondria are evolutionary bacteria that are dynamic intracellular organelles involved in many vital cellular functions. However, modern medicine has fallen prey to misuse and over-usage of antibiotics. This misuse can damage the mitochondrion, alter host antibiotic interactions, and cause serious pathophysiologic conditions. We believe this leads to mitochondrial dysfunction, which may promote tumorigenesis and neurodegeneration. This opinion commentary’s goal is to bring awareness of this important hot topic to the medical community before induced modern plagues are irreversible.

Pathogenic bacterium Vibrio harveyi: an endosymbiont in the marine parasitic ciliate protozoan Cryptocaryon irritans

Vibrio harveyi, known as a pathogenic bacterium caused severe secondary bacterial infections of the large yellow croaker Larimichthys crocea, was identified as an endosymbiont in the marine parasitic ciliate protozoan Cryptocaryon irritans. Meta 16 S sequencing method was used to identify the bacterial flora in C. irritans, and V.harveyi was isolated via culture-dependent method. Vibrio harveyi was observed in cytoplasm of C. irritans at the stage of tomont both by transmission electron microscopy and by Fluorescence in situ hybridization; no signal,however, was detected in nucleus area. The relationship between V. harveyi and C. irritans and the role of endosymbiotic V. harveyi in C. irritans merit further investigation.

High Temperature Effects on Yeast-like Endosymbiotes and Pesticide Resistance of the Small Brown Planthopper, Laodelphax striatellus

The newly-hatched nymphs of the small brown planthopper (SBPH), Laodelphax striatellus, including field and sensitive populations, were subjected to the high-temperature (35°C) treatment. The number of yeast-like endosymbiotes in SBPH reduced by 23.47%–34.23%, 57.86%–61.51% and 88.96%–90.71% after the high-temperature treatment for 1 d, 2 d, and 3 d, respectively. However, the size of yeast-like endosymbiotes was not obviously affected. Resistance of SBPH to three insecticides (imidacloprid, chlorpyrifos and fipronil) decreased with the increase of treatment time.

Converting antimicrobial into targeting peptides reveals key features governing protein import into mitochondria and chloroplasts

We asked what peptide features govern targeting to the mitochondria versus the chloroplast,using antimicrobial peptides as a starting point.This approach was inspired by the endosymbiotic hypothesis that organelle-targeting peptides derive from antimicrobial amphipathic peptides delivered by the host cell,to which organelle progenitors became resistant.To explore the molecular changes required to convert antimicrobial into targeting peptides,we expressed a set of 13 antimicrobial peptides in Chlamydomonas reinhardtii.Peptides were systematically modified to test distinctive features of mitochondrion-and chloroplast-targeting peptides,and we assessed their targeting potential by following the intracellular localization and maturation of a Venus fluorescent reporter used as a cargo protein.Mitochondrial targeting can be achieved by some unmodified antimicrobial peptide sequences.Targeting to both organelles is improved by replacing lysines with arginines.Chloroplast targeting is enabled by the presence of flanking unstructured sequences,additional constraints consistent with chloroplast endosymbiosis having occurred in a cell that already contained mitochondria.If indeed targeting peptides evolved from antimicrobial peptides,then required modifications imply a temporal evolutionary scenario with an early exchange of cationic residues and a late acquisition of chloroplast-specific motifs.

Symbiosome-like intracellular colonization of cereals and other crop plants by nitrogen-fixing bacteria for reduced inputs of synthetic nitrogen fertilizers

It has been forecast that the challenge of meeting increased food demand and protecting environmental quality will be won or lost in maize, rice and wheat cropping systems,and that the problem of environmental nitrogen enrichment is most likely to be solved by substituting synthetic nitrogen fertilizers by the creation of cereal crops that are able to fix nitrogen symbiotically as legumes do. In legumes, rhizobia present intraceliularly in membrane-bound vesicular compartments in the cytoplasm of nodule cells fix nitrogen endosymbiotically. Within these symbiosomes, membrane-bound vesicular compartments, rhizobia are supplied with energy derived from plant photosynthates and in return supply the plant with biologically fixed nitrogen, usually as ammonia. This minimizes or eliminates the need for inputs of synthetic nitrogen fertilizers. Recently we have demonstrated, using novel inoculation conditions with very low numbers of bacteria, that cells of root meristems of maize, rice, wheat and other major non-legume crops, such as oilseed rape and tomato, can be intracellularly colonized by the non-rhizobial, non-nodulating, nitrogen fixing bacterium, Gluconacetobacter diazotrophicus that naturally occurs in sugarcane. G. diazotrophicus expressing nitrogen fixing (nifH) genes is present in symbiosome-like compartments in the cytoplasm of cells of the root meristems of the target cereals and non-legume crop species, somewhat similar to the intracellular symbiosome colonization of legume nodule cells by rhizobia. To obtain an indication of the likelihood of adequate growth and yield, of maize for example, with reduced inputs of synthetic nitrogen fertilizers,we are currently determining the extent to which nitrogen fixation, as assessed using various methods, is correlated with the extent of systemic intracellular colonization by G. diazotrophicus,with minimal or zero inputs.

Genome-Wide Survey and Evolutionary Analysis of Trypsin Proteases in Apicomplexan Parasites

Apicomplexa are an extremely diverse group of unicellular organisms that infect humans and other animals. Despite the great advances in combating infectious diseases over the past century, these parasites still have a tremendous social and economic burden on human societies, particularly in tropical and subtropical regions of the world. Proteases from apicomplexa have been characterized at the molecular and cellular levels, and central roles have been proposed for proteases in diverse processes. In this work, 16 new genes encoding for trypsin proteases are identified in 8 apicomplexan genomes by a genome-wide survey. Phylogenetic analysis suggests that these genes were gained through both intracellutar gene transfer and vertical gene transfer. Identification, characterization and understanding of the evolutionary origin of protease-mediated processes are crucial to increase the knowledge and improve the strategies for the development of novel chemotherapeutic agents and vaccines.