Cryptomonad algae contain a photosynthetic, eukaryotic endosymbiont. The endosymbiont is much reduced but retains a small nucleus. DNA from this endosymbiont nucleus encodes rRNAs, and it is presumed that these rRNAs are incorporated into ribosomes. Surrounding the endosymbiont nucleus is a small volume of cytoplasm proposed to be the vestigial cytoplasm of the endosymbiont. If this compartment...

A unique lineage of bacteria belonging to the order Bacteroidales was identified as an intracellular endosymbiont of the protist Pseudotrichonympha grassii (Parabasalia, Hypermastigea) in the gut of the termite Coptotermes formosanus. We identified the 16S rRNA, gyrB, elongation factor Tu, and groEL gene sequences in the endosymbiont and detected a very low level of sequence divergence (<0.9% o...

Individual traits vary among and within populations, and the co-occurrence of different endosymbiont species within a host may take place under varying endosymbiont loads in each individual host. This makes the recognition of the potential impact of such endosymbiont associations in insect species difficult, particularly in insect pest species. The maize weevil, Sitophilus zeamais Motsch. (Cole...

Phylogenetic trees can reveal the origins of endosymbiotic lineages of bacteria and detect patterns of co-evolution with their hosts. Although taxon sampling can greatly affect phylogenetic and co-evolutionary inference, most hypotheses of endosymbiont relationships are based on few available bacterial sequences. Here we examined how different sampling strategies of Gammaproteobacteria sequence...

Mitochondria and plastids originated through endosymbiosis, and subsequently became reduced and integrated with the host in similar ways. Plastids spread between lineages through further secondary or even tertiary endosymbioses, but mitochondria appear to have originated once and have not spread between lineages. Mitochondria are also generally lost in secondary and tertiary endosymbionts, with...

Kryptoperidinium foliaceum is a binucleate dinoflagellate that contains an endosymbiont nucleus of diatom origin. However, it is unknown whether the binucleate condition is permanent or not and how the diatom nucleus behaves during the life history processes. In this sense, it is also unknown if there is a sexual cycle or a resting stage during the life history of this species, two key aspects ...

Microscopic localization of endosymbiotic bacteria in three species of mealybug (Pseudococcus longispinus, the long-tailed mealybug; Pseudococcus calceolariae, the citrophilus mealybug; and Pseudococcus viburni, the obscure mealybug) showed these organisms were confined to bacteriocyte cells within a bacteriome centrally located within the hemocoel. Two species of bacteria were present, with th...

Symbiotic associations are widespread in nature and represent a driving force in evolution. They are known to impact fitness, and thereby shape the host phenotype. Insects subsisting on nutritionally poor substrates have evolved mutualistic relationships with intracellular symbiotic bacteria (endosymbionts) that supply them with metabolic components lacking in their diet. In many species, endos...

Wolbachia is an endosymbiotic bacterium widely present in arthropods and animal-parasitic nematodes. Despite previous efforts, it has never been identified in plant-parasitic nematodes. Random sequencing of genes expressed by the burrowing nematode Radopholus similis resulted in several sequences with similarity to Wolbachia genes. The presence of a Wolbachia-like endosymbiont in this plant-par...

The endosymbiont of Acanthamoeba strain UWC8 is an obligate amoeba endosymbiont belonging to the family of "Candidatus Midichloriaceae" in Rickettsiales. We report here the complete genome sequence of this bacterium, which should catalyze future studies of amoeba-symbiont interactions.