Search Results (87)

Insect pests inflict significant agricultural and economic losses on crops globally. Chemical control refers to the use of agrochemicals, such as insecticides, herbicides, and fungicides, to manage pests and diseases. Chemical control is still the prioritized method, as insecticides are highly effective and toxic to insect pests. However, it reduces the quality of the environment, threatens human health, and causes serious 3R (reduce, reuse, and recycle) problems. Current advances in the mining of functional symbiotic bacteria resources provide the potential to assuage the use of insecticides while maintaining an acceptably low level of crop damage. Recent research on insect–microbe symbiosis has uncovered a mechanism labeled “detoxifying symbiosis”, where symbiotic microorganisms increase host insect resistance through the metabolism of toxins. In addition, the physiological compensation effect caused by insect resistance affects the ability of the host to regulate the community composition of symbiotic bacteria. This paper reviews the relationship between symbiotic bacteria, insects, and insecticide resistance, focusing on the effects of insecticide resistance on the composition of symbiotic bacteria and the role of symbiotic bacteria in the formation of resistance. The functional symbiotic bacteria resources and their mechanisms of action need to be further explored in the future so as to provide theoretical support for the development of pest control strategies based on microbial regulation. Full article

Photosynthetic eukaryotes have shaped the Earth’s biosphere by producing oxygen and organic compounds using light energy in specialized organelles called plastids. Plastids evolved from free-living cyanobacteria ingested by heterotrophic unicellular eukaryotes. Two such independent engulfment processes, called cyanobacterial endosymbioses, have been reported. The first gave rise to primary plastids and three Archaeplastida lineages: glaucophytes, red algae, and green algae with land plants, whereas the second resulted in chromatophores in the rhizarian amoeba Paulinella. Importantly, Archaeplastidans donated their plastids to many protist groups, further spreading photosynthesis across the tree of life. To reveal complex plastid evolution, we performed comprehensive phylogenetic and molecular clock analyses using new fossil calibrations and the largest number yet of plastid-encoded proteins from 108 taxa, representing diverse photosynthetic organisms. Our results indicate that primary plastids evolved prior to 2.1–1.8 Ga, i.e., before glaucophytes diverged from other Archaeplastidans, and Paulinella chromatophores were likely before 292–266 Ma. Red and green algae were engulfed by cryptophyte and chlorarachniophyte ancestors between 1.7–1.4 Ga and 1.1–1.0 Ga, respectively; the former subsequently triggered plastid transfers to other eukaryotes. We also examined the impact of molecular clocks and calibration sets on age estimates, showing that clocks are the main source of variation. Full article

It is known that the ciliate Paramecium cell surface including cilia is completely covered by high-molecular-mass GPI-anchored proteins named surface antigens (SAgs). However, their functions are not well understood. It was found that ciliate Paramecium caudatum reversibly changes its SAgs depending on the absence or presence of the endonuclear symbiotic bacterium Holospora obtusa in the macronucleus. Immunofluorescence microscopy with a monoclonal antibody produced SAg of the H. obtusa-free P. caudatum strain RB-1-labeled cell surface of the H. obtusa-free P. caudatum RB-1 cell but not the H. obtusa-bearing RB-1 cell. When this antibody was added to the living P. caudatum RB-1 cells, only H. obtusa-free cells were immobilized. An immunoblot with SAgs extracted from Paramecium via cold salt/ethanol treatment showed approximately 266-kDa SAgs in the extract from H. obtusa-free cells and 188 and 149-kDa SAgs in the extract from H. obtusa-bearing cells. H. obtusa-free RB-1 cells produced from H. obtusa-bearing cells via treatment with penicillin-G-potassium re-expressed 266-kDa SAg, while the 188 and 149-kDa SAgs disappeared. This phenotypic change in the SAgs was not induced by degrees of starvation or temperature shifts. These results definitively show that Paramecium SAgs have functions related to bacterial infection. Full article

Endosymbiosis can be considered a regressive or degenerative evolutionary process characterized at the genomic level by genome erosion and degeneration due to high mutational pressure toward AT (adenine and thymine) bases. The genomic and biological complexity of endosymbionts must be lower than that of the free-living bacteria from which they evolved. In the present work, we contrasted whether two proposed metrics for measuring genomic complexity in both types of bacteria, GS and BB, reflect their complexity, expecting higher values in free-living bacteria than in endosymbionts. On the other hand, we endeavored to delve into the factors that contribute to the reduction in metric values in endosymbionts, as well as their eventual relationship with six genomic parameters associated with functionality. This study aimed to test the robustness of these proposed metrics in a well-known biological scenario, such as the endosymbiosis process. Full article

Paramecium bursaria, a ciliated protist, forms a symbiotic relationship with the green alga Chlorella variabilis. This endosymbiotic association is a model system for studying the establishment of secondary symbiosis and interactions between the symbiont and its host organisms. Symbiotic algae reside in specialized compartments called perialgal vacuoles (PVs) within the host cytoplasm, which protect them from digestion by host lysosomal fusion. The relationship between P. bursaria and symbiotic Chlorella spp. is characterized by mutualism, in which both organisms benefit from this association. Furthermore, symbiotic algae also influence their host phenotypes, and algae-free P. bursaria can be obtained through various methods and reassociated with symbiotic algae, making it a valuable tool for studying secondary endosymbiosis. Recent advancements in genomic and transcriptomic studies on both hosts and symbionts have further enhanced the utility of this model system. This review summarizes the infection process of the symbiotic alga C. variabilis and its effects on the algal infection on number of host trichocysts, mitochondria, cytoplasmic crystals, total protein amount, stress responses, photoaccumulation, and circadian rhythms of the host P. bursaria. Full article

Mitochondrial holocytochrome c synthase (HCCS) is an essential protein in assembling cytochrome c (cyt c) of the electron transport system. HCCS binds heme and covalently attaches the two vinyls of heme to two cysteine thiols of the cyt c CXXCH motif. Human HCCS recognizes both cyt c and cytochrome c₁ of complex III (cytochrome bc₁). HCCS is mutated in some human diseases and it has been investigated recombinantly by mutational, biochemical, and reconstitution studies in the past decade. Here, we employ structural prediction programs (e.g., AlphaFold 3) on HCCS and its two substrates, heme and cytochrome c. The results, when combined with spectroscopic and functional analyses of HCCS and variants, provide insights into the structural basis for heme binding, apocyt c binding, covalent attachment, and release of the holocyt c product. Results from in vitro reconstitution of purified human HCCS using cyt c and cyt c₁ peptides as acceptors are consistent with the structural modeling of substrate binding. Reconstitution of HCCS and cyt c₁ provides an approach to studying cyt c₁ assembly, which has been refractile to recombinant in vivo reconstitution (unlike HCCS and cyt c). We propose a structural basis for release of the holocyt c product from HCCS based on in vitro studies and on cryoEM structures of the bacterial cyt c synthase (CcsBA) active site. We analyze the kinetoplastid mitochondrial synthase (KCCS), and hypothesize a molecular evolutionary path from mitochondrial endosymbiosis to the current HCCS. Full article

(1) Background: Microbial keratitis is a serious eye infection that carries a significant risk of vision loss. Acanthamoeba spp. are known to cause keratitis and their bacterial endosymbionts can increase virulence and/or treatment resistance and thus significantly worsen the course of the disease. (2) Methods and Results: In a suspected case of Acanthamoeba keratitis, in addition to Acanthamoeba spp., an endosymbiont of acanthamoebae belonging to the taxonomic order of Holosporales was detected by chance in a bacterial 16S rDNA-based pan-PCR and subsequently classified as Candidatus Paracaedibacter symbiosus through an analysis of an enlarged 16S rDNA region. We used Oxford Nanopore Technology to evaluate the usefulness of whole-genome sequencing (WGS) as a one-step diagnostics method. Here, Acanthamoeba castellanii and the endosymbiont Candidatus Paracaedibacter symbiosus could be directly detected at the species level. No other microbes were identified in the specimen. (3) Conclusions: We recommend the introduction of WGS as a diagnostic approach for keratitis to replace the need for multiple species-specific qPCRs in future routine diagnostics and to enable an all-encompassing characterisation of the polymicrobial community in one step. Full article

The universe began 13.8 billion years ago, and Earth was born 4.6 billion years ago. Early traces of life were found as soon as 4.1 billion years ago; then, ~200,000 years ago, the human being was born. The evolution of life on earth was to become individual rather than cellular life. The birth of mitochondria made this possible to be the individual life. Since then, individuals have had a limited time of life. It was 1.4 billion years ago that a bacterial cell began living inside an archaeal host cell, a form of endosymbiosis that is the development of eukaryotic cells, which contain a nucleus and other membrane-bound compartments. The bacterium started to provide its host cell with additional energy, and the interaction eventually resulted in a eukaryotic cell, with both archaeal (the host cell) and bacterial (mitochondrial) origins still having genomes. The cells survived high concentrations of oxygen producing more energy inside the cell. Further, the roles of mitochondria in human being’s life and aging will be discussed. Full article

Hydra is known for its natural occurrence, anatomical simplicity, intricate physiology, regenerative capacity, and ease of maintenance and manipulation in laboratory environments. It has proven to be a valuable model organism in various disciplines. Its applications range from developmental biology, stem cell research, animal physiology to environmental toxicology including ecotoxicology. The sensitivity of Hydra to a variety of environmental stressors and chemical agents such as metals, nanomaterials, and toxic organic compounds provides valuable insights into physiological mechanisms affected by environmental stressors and pollution, and Hydra can be of great use in environmental monitoring. Furthermore, since green Hydra lives in a symbiotic relationship with unicellular photoautotrophic algae, it is a suitable model organism for symbiosis research. Recently, it has become a popular model in holobiont research. The adaptability and importance of Hydra also extends to aquatic science and aquatic ecology, particularly in the context of monitoring and water pollution. Since the 1980s, Hydra has been increasingly used in various fields of research and has established itself as an important versatile model organism in numerous scientific studies. Hydra also represents an outstanding model in the fields of education and STEM. Hydra continues to be an important model in the 21st century, contributing significantly to our understanding of the biology of water and advancing freshwater research, and possibly finding its way to regenerative medicine and tumor pathobiology research. Full article

Three genera of viruses of the family Totiviridae establish endosymbiotic associations with flagellated protozoa responsible for parasitic diseases of great impact in the context of One Health. Giardiavirus, Trichomonasvirus, and Leishmaniavirus infect the protozoa Giardia sp., Trichomonas vaginalis, and Leishmania sp., respectively. In the present work, we review the characteristics of the endosymbiotic relationships established, the advantages, and the consequences caused in mammalian hosts. Among the common characteristics of these double-stranded RNA viruses are that they do not integrate into the host genome, do not follow a lytic cycle, and do not cause cytopathic effects. However, in cases of endosymbiosis between Leishmaniavirus and Leishmania species from the Americas, and between Trichomonasvirus and Trichomonas vaginalis, it seems that it can alter their virulence (degree of pathogenicity). In a mammalian host, due to TLR3 activation of immune cells upon the recognition of viral RNA, uncontrolled inflammatory signaling responses are triggered, increasing pathological damage and the risk of failure of conventional standard treatment. Endosymbiosis with Giardiavirus can cause the loss of intestinal adherence of the protozoan, resulting in a benign disease. The current knowledge about viruses infecting flagellated protozoans is still fragmentary, and more research is required to unravel the intricacies of this three-way relationship. We need to develop early and effective diagnostic methods for further development in the field of translational medicine. Taking advantage of promising biotechnological advances, the aim is to develop ad hoc therapeutic strategies that focus not only on the disease-causing protozoan but also on the virus. Full article

The formation of phytoene by condensing two geranylgeranyl diphosphate molecules catalyzed by phytoene synthase (PSY) is the first committed and rate-limiting step in carotenoid biosynthesis, which has been extensively investigated in bacteria, land plants and microalgae. However, this step in macroalgae remains unknown. In the present study, a gene encoding putative phytoene synthase was cloned from the economic red alga Pyropia yezoensis—a species that has long been used in food and pharmaceuticals. The conservative motifs/domains and the tertiary structure predicted using bioinformatic tools suggested that the cloned PyPSY should encode a phytoene synthase; this was empirically confirmed by pigment complementation in E. coli. This phytoene synthase was encoded by a single copy gene, whose expression was presumably regulated by many factors. The phylogenetic relationship of PSYs from different organisms suggested that red algae are probably the progeny of primary endosymbiosis and plastid donors of secondary endosymbiosis. Full article

Chloroplasts and mitochondria, descendants of ancient prokaryotes via endosymbiosis, occupy a pivotal position in plant growth and development due to their intricate connections with the nuclear genome. Genes encoded by the nuclear genome but relocated to or being functional within these organelles are commonly referred as organelle-targeting nuclear genes (ONGs). These genes are essential for maintaining cytonuclear coordination, thereby determining the stability of the life cycle. While molecular function and cytonuclear coordination of some endosymbiosis-derived ONGs (E-ONGs) have been extensively studied, the evolutionary history and characteristics from a more widespread range of non-endosymbiosis-derived ONGs (NE-ONGs) remain largely enigmatic. In this study, we focused on 12 representative species within the Poaceae family to systematically identify NE-ONGs and investigated their evolutionary history and functional significance on a phylogenetic timescale. Upon aligning these 12 species’ evolutionary histories, we observed the following phenomena: (i) an exploration of NE-ONGs between the BOP and PACMAD clades unveiled dynamic compositions, potentially influencing their photosynthetic divergence; (ii) the majority of the abundant species-specific NE-ONGs exist in a single-copy status, and functional enrichment analysis further underscored their specialized roles, which could be crucial for species adaptation; and (iii) comparative analyses between plasmid- and mitochondria-related NE-ONGs (pNE-ONGs and mNE-ONGs) revealed a prevalence of pNE-ONGs, indicating tighter control for chloroplast function in Poaceae. In summary, this study offers novel insights into the cytonuclear co-evolutionary dynamics in Poaceae speciation and draws attention to crop improvement by using NE-ONGs. Full article

We explored the metabolic integration of Blattella germanica and its obligate endosymbiont Blattabacterium cuenoti by the transcriptomic analysis of the fat body of quasi-aposymbiotic cockroaches, where the endosymbionts were almost entirely removed with rifampicin. Fat bodies from quasi-aposymbiotic insects displayed large differences in gene expression compared to controls. In quasi-aposymbionts, the metabolism of phenylalanine and tyrosine involved in cuticle sclerotization and pigmentation increased drastically to compensate for the deficiency in the biosynthesis of these amino acids by the endosymbionts. On the other hand, the uricolytic pathway and the biosynthesis of uric acid were severely decreased, probably because the reduced population of endosymbionts was unable to metabolize urea to ammonia. Metabolite transporters that could be involved in the endosymbiosis process were identified. Immune system and antimicrobial peptide (AMP) gene expression was also reduced in quasi-aposymbionts, genes encoding peptidoglycan-recognition proteins, which may provide clues for the maintenance of the symbiotic relationship, as well as three AMP genes whose involvement in the symbiotic relationship will require additional analysis. Finally, a search for AMP-like factors that could be involved in controlling the endosymbiont identified two orphan genes encoding proteins smaller than 200 amino acids underexpressed in quasi-aposymbionts, suggesting a role in the host–endosymbiont relationship. Full article

The eukaryotic lineage has enjoyed a long-term “stable” mutualism between nucleus and mitochondrion, since mitochondrial endosymbiosis began about 2 billion years ago. This mostly cooperative interaction has provided the basis for eukaryotic expansion and diversification, which has profoundly altered the forms of life on Earth. While we ignore the exact biochemical details of how the alpha-proteobacterial ancestor of mitochondria entered into endosymbiosis with a proto-eukaryote, in more general terms, we present a signaling games perspective of how the cooperative relationship became established, and has been maintained. While games are used to understand organismal evolution, information-asymmetric games at the molecular level promise novel insights into endosymbiosis. Using a previously devised biomolecular signaling games approach, we model a sender–receiver information asymmetric game, in which the informed mitochondrial sender signals and the uninformed nuclear receiver may take actions (involving for example apoptosis, senescence, regeneration and autophagy/mitophagy). The simulation shows that cellularization is a stabilizing mechanism for Pareto efficient sender/receiver strategic interaction. In stark contrast, the extracellular environment struggles to maintain efficient outcomes, as senders are indifferent to the effects of their signals upon the receiver. Our hypothesis has translational implications, such as in cellular therapy, as mitochondrial medicine matures. It also inspires speculative conjectures about how an analogous human–AI endosymbiosis may be engineered. Full article