Eukaryotic microbes have three primary mechanisms for obtaining nutrients and energy: phagotrophy, photosynthesis and osmotrophy. Traits associated with the latter two functions arose independently multiple times in the eukaryotes. The Fungi successfully coupled osmotrophy with filamentous growth, and similar traits are also manifested in the Pseudofungi (oomycetes and hyphochytriomycetes). Bot...

The luminous bacterial symbionts of anomalopid flashlight fish are thought to be obligately dependent on their hosts for growth and share several aspects of genome evolution with unrelated obligate symbionts, including genome reduction. However, in contrast to most obligate bacteria, anomalopid symbionts have an active environmental phase that may be important for symbiont transmission. Here we...

It is proposed that the phenomena of cytoplasmic incompatibility is explicable in terms of the selfish interests of the prokaryotic symbionts associated with the phenomena. It is hypothesized that in males the symbionts produce a product, termed wolbachin, which is carried in sperm and has the capability of inhibiting zygotic development if not neutralized. Symbionts are capable of neutralizing...

Sap-sucking insects typically engage in obligate relationships with symbiotic bacteria that play nutritional roles in synthesizing nutrients unavailable or in scarce supply from the plant-sap diets of their hosts. Adelgids are sap-sucking insects with complex life cycles that involve alternation between conifer tree species. While all adelgid species feed on spruce during the sexual phase of th...

Recent analyses of the small subunit ribosomal DNA (srDNA) from dinoflagellate symbionts of cnidaria have confirmed historical descriptions of a diverse but well-defined clade, Symbiodinium, as well as several other independent symbiont lineages (Rowan 1991; Rowan and Powers 1992; Sadler et al. 1992; McNally et al 1994). Dinoflagellates also occur as intracellular symbionts in a number of pelag...

Symbiotic associations between animals and inherited micro-organisms are widespread in nature. In many cases, hosts may be superinfected with multiple inherited symbionts. Acyrthosiphon pisum (the pea aphid) may harbour more than one facultative symbiont (called secondary symbionts) in addition to the obligate primary symbiont, Buchnera aphidicola. Previously we demonstrated that, in a controll...

Intracellular thioautotrophic symbionts of deep-sea vesicomyid clams lack some DNA repair genes and are thought to be undergoing reductive genome evolution (RGE). In this study, we addressed two questions, 1) how these symbionts lost their DNA repair genes and 2) how such losses affect RGE. For the first question, we examined genes associated with nucleotide excision repair (NER; uvrA, uvrB, uv...

Host-symbiont cospeciation and reductive genome evolution have been identified in obligate endocellular insect symbionts, but no such example has been identified from extracellular ones. Here we first report such a case in stinkbugs of the family Plataspidae, wherein a specific gut bacterium is vertically transmitted via "symbiont capsule." In all of the plataspid species, females produced symb...