20 research outputs found
Wolbachia in the flesh: symbiont intensities in germ-line and somatic tissues challenge the conventional view of Wolbachia transmission routes
Symbionts can substantially affect the evolution and ecology of their hosts. The investigation of the tissue-specific distribution of symbionts (tissue tropism) can provide important insight into host-symbiont interactions. Among other things, it can help to discern the importance of specific transmission routes and potential phenotypic effects. The intracellular bacterial symbiont Wolbachia has been described as the greatest ever panzootic, due to the wide array of arthropods that it infects. Being primarily vertically transmitted, it is expected that the transmission of Wolbachia would be enhanced by focusing infection in the reproductive tissues. In social insect hosts, this tropism would logically extend to reproductive rather than sterile castes, since the latter constitute a dead-end for vertically transmission. Here, we show that Wolbachia are not focused on reproductive tissues of eusocial insects, and that non-reproductive tissues of queens and workers of the ant Acromyrmex echinatior, harbour substantial infections. In particular, the comparatively high intensities of Wolbachia in the haemolymph, fat body, and faeces, suggest potential for horizontal transmission via parasitoids and the faecal-oral route, or a role for Wolbachia modulating the immune response of this host. It may be that somatic tissues and castes are not the evolutionary dead-end for Wolbachia that is commonly thought
Cellular Tropism, Population Dynamics, Host Range and Taxonomic Status of an Aphid Secondary Symbiont, SMLS (Sitobion miscanthi L Type Symbiont)
SMLS (Sitobion miscanthi L type symbiont) is a newly reported aphid secondary symbiont. Phylogenetic evidence from molecular markers indicates that SMLS belongs to the Rickettsiaceae and has a sibling relationship with Orientia tsutsugamushi. A comparative analysis of coxA nucleotide sequences further supports recognition of SMLS as a new genus in the Rickettsiaceae. In situ hybridization reveals that SMLS is housed in both sheath cells and secondary bacteriocytes and it is also detected in aphid hemolymph. The population dynamics of SMLS differ from those of Buchnera aphidicola and titer levels of SMLS increase in older aphids. A survey of 13 other aphids reveals that SMLS only occurs in wheat-associated species
Bidirectional incompatibility among divergent Wolbachia and incompatibility level differences among closely related Wolbachia in Nasonia
Author Posting. © The Author(s), 2007. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Heredity 99 (2007): 278–287, doi:10.1038/sj.hdy.6800994.Most insect groups harbor obligate bacterial symbionts from the alphaproteobacterial
genus Wolbachia. These bacteria alter insect reproduction in ways that
enhance their cytoplasmic transmission. One of the most common alterations is
cytoplasmic incompatibility (CI) - a post-fertilization modification of the paternal
genome that renders embryos inviable or unable to complete diploid development in
crosses between infected males and uninfected females or infected females harboring a
different strain. The parasitic wasp species complex Nasonia (N. vitripennis, N.
longicornis, and N. giraulti) harbor at least six different Wolbachia that cause
cytoplasmic incompatibility. Each species have double infections with a representative
from both the A and B Wolbachia subgroups. CI relationships of the A and B Wolbachia
of N. longicornis with those of N. giraulti and N. vitripennis are investigated here. We
demonstrate that all pairwise crosses between the divergent A strains are bidirectionally
incompatible. We were unable to characterize incompatibility between the B Wolbachia,
but we establish that the B strain of N. longicornis induces no or very weak CI in
comparison to the closely related B strain in N. giraulti that expresses complete CI.
Taken together with previous studies, we show that independent acquisition of divergent
A Wolbachia has resulted in three mutually incompatible strains, while codivergence of B
Wolbachia in N. longicornis and N. giraulti is associated with differences in CI level.
Understanding the diversity and evolution of new incompatibility strains will contribute
to a fuller understanding of Wolbachia invasion dynamics and Wolbachia-assisted
speciation in certain groups of insects.This work was supported by grant EF-0328363 and DEB-9981634 from the
National Science Foundation to J.H.W. and an Ernst Caspari Research Fellowship to
S.R.B while he was at the University of Rochester. S.R.B. acknowledges support from
the NASA Astrobiology Institute (NNA04CC04A)