Combined actions of bacteriophage-encoded genes in -induced male lethality.

Some endosymbionts induce male killing, whereby male offspring of infected females are killed during development; however, the origin and diversity of the underlying mechanisms remain unclear. In this study, we identified a 76 kbp prophage region specific to male-killing hosted by the moth . The prophage encoded a homolog of the male-killing gene in moths and the gene that induces various toxicities in .

Cytoplasmic incompatibility in the semivoltine longicorn beetle Acalolepta fraudatrix (Coleoptera: Cerambycidae) double infected with Wolbachia.

Wolbachia are obligatory endosymbiotic α-proteobacteria found in many arthropods. They are maternally inherited, and can induce reproductive alterations in the hosts. Despite considerable recent progress in studies on the associations between Wolbachia and various taxonomic groups of insects, none of the researches have revealed the effects of Wolbachia on longicorn beetles as the host insect.

A Novel, Extremely Elongated, and Endocellular Bacterial Symbiont Supports Cuticle Formation of a Grain Pest Beetle.

The saw-toothed grain beetle, (Silvanidae), is a cosmopolitan stored-product pest. Early studies on in the 1930s described the presence of peculiar bacteriomes harboring endosymbiotic bacteria in the abdomen. Since then, however, the microbiological nature of the symbiont has been elusive.

Small genome symbiont underlies cuticle hardness in beetles.

Beetles, representing the majority of the insect species diversity, are characterized by thick and hard cuticle, which plays important roles for their environmental adaptation and underpins their inordinate diversity and prosperity. Here, we report a bacterial endosymbiont extremely specialized for sustaining beetle's cuticle formation. Many weevils are associated with a γ-proteobacterial endosymbiont lineage , whose evolutionary origin is estimated as older than 100 million years, but its functional aspect has been elusive.

Male-killing symbiont damages host's dosage-compensated sex chromosome to induce embryonic apoptosis.

Some symbiotic bacteria are capable of interfering with host reproduction in selfish ways. How such bacteria can manipulate host's sex-related mechanisms is of fundamental interest encompassing cell, developmental and evolutionary biology. Here, we uncover the molecular and cellular mechanisms underlying Spiroplasma-induced embryonic male lethality in Drosophila melanogaster.

Infection Density Dynamics of the Citrus Greening Bacterium "Candidatus Liberibacter asiaticus" in Field Populations of the Psyllid Diaphorina citri and Its Relevance to the Efficiency of Pathogen Transmission to Citrus Plants.

Huanglongbing, or citrus greening, is a devastating disease of citrus plants recently spreading worldwide, which is caused by an uncultivable bacterial pathogen, "Candidatus Liberibacter asiaticus," and vectored by a phloem-sucking insect, Diaphorina citri. We investigated the infection density dynamics of "Ca. Liberibacter asiaticus" in field populations of D.

Male-killing Spiroplasma induces sex-specific cell death via host apoptotic pathway.

Some symbiotic bacteria cause remarkable reproductive phenotypes like cytoplasmic incompatibility and male-killing in their host insects. Molecular and cellular mechanisms underlying these symbiont-induced reproductive pathologies are of great interest but poorly understood. In this study, Drosophila melanogaster and its native Spiroplasma symbiont strain MSRO were investigated as to how the host's molecular, cellular and morphogenetic pathways are involved in the symbiont-induced male-killing during embryogenesis.

Spiroplasma as a model insect endosymbiont.

Members of the genus Spiroplasma are actively motile and helical bacteria of the class Mollicutes, which are associated with a variety of arthropods and plants. Some spiroplasmas cause female-biased sex ratios of their host insects as a result of selective death of the male offspring during embryogenesis. Several strains of male-killing spiroplasmas have been successfully transfected into Drosophila melanogaster by haemolymph injection and maintained in laboratory fly stocks.

Longicorn beetle that vectors pinewood nematode carries many Wolbachia genes on an autosome.

Monochamus alternatus is the longicorn beetle notorious as a vector of the pinewood nematode that causes the pine wilt disease. When two populations of M. alternatus were subjected to diagnostic polymerase chain reaction (PCR) detection of four Wolbachia genes, only the ftsZ gene was detected from one of the populations.

High and low temperatures differently affect infection density and vertical transmission of male-killing Spiroplasma symbionts in Drosophila hosts.

We investigated the vertical transmission, reproductive phenotype, and infection density of a male-killing Spiroplasma symbiont in two Drosophila species under physiological high and low temperatures through successive host generations. In both the native host Drosophila nebulosa and the nonnative host Drosophila melanogaster, the symbiont infection and the male-killing phenotype were stably maintained at 25 degrees C, rapidly lost at 18 degrees C, and gradually lost at 28 degrees C. In the nonnative host, both the high and low temperatures significantly suppressed the infection density of the spiroplasma.

Spiroplasma infection causes either early or late male killing in Drosophila, depending on maternal host age.

Symbiont-induced male-killing phenotypes have been found in a variety of insects. Conventionally, these phenotypes have been divided into two categories according to the timing of action: early male killing at embryonic stages and late male killing at late larval stages. In Drosophila species, endosymbiotic bacteria of the genus Spiroplasma have been known to cause early male killing.

Prevalence of a non-male-killing spiroplasma in natural populations of Drosophila hydei.

Male-killing phenotypes are found in a variety of insects and are often associated with maternally inherited endosymbiotic bacteria. In several species of Drosophila, male-killing endosymbionts of the genus Spiroplasma have been found at low frequencies (0.1 to 3%).

Asymmetrical interactions between Wolbachia and Spiroplasma endosymbionts coexisting in the same insect host.

We investigated the interactions between the endosymbionts Wolbachia pipientis strain wMel and Spiroplasma sp. strain NSRO coinfecting the host insect Drosophila melanogaster. By making use of antibiotic therapy, temperature stress, and hemolymph microinjection, we established the following strains in the same host genetic background: the SW strain, infected with both Spiroplasma and Wolbachia; the S strain, infected with Spiroplasma only; and the W strain, infected with Wolbachia only.

Tissue-specific infection dynamics of male-killing and nonmale-killing spiroplasmas in Drosophila melanogaster.

The male-killing spiroplasma strain NSRO causes an extremely female-biased sex ratio of the host, Drosophila melanogaster, as a result of selective death of male offspring during embryogenesis. The spiroplasma strain NSRO-A, a variant of NSRO, does not cause such symptoms. In an attempt to gain insights into the mechanism underlying the symbiont-induced reproductive phenotype, infection densities of the spiroplasmas in different tissues were monitored during host aging using a quantitative PCR technique.

Functional analysis of unique class II insertion sequence IS1071.

Various xenobiotic-degrading genes on many catabolic plasmids are often flanked by two copies of an insertion sequence, IS1071. This 3.2-kb IS element has long (110-bp) terminal inverted repeats (IRs) and a transposase gene that are phylogenetically related to those of the class II transposons.

Population dynamics of male-killing and non-male-killing spiroplasmas in Drosophila melanogaster.

The endosymbiotic bacteria Spiroplasma spp. are vertically transmitted through female hosts and are known to cause selective death of male offspring in insects. One strain of spiroplasma, NSRO, causes male killing in Drosophila species, and a non-male-killing variant of NSRO, designated NSRO-A, has been isolated.

Hidden from the host: Spiroplasma bacteria infecting Drosophila do not cause an immune response, but are suppressed by ectopic immune activation.

Insects and other arthropods have an effective innate immune system that can clear infections with bacteria and other microorganisms. Despite this ability, one group of bacteria, the spiroplasmas, survive unharmed within the haemolymph of a wide range of arthropod hosts. We investigated the interaction between one member of this clade, a relative of Spiroplasma poulsonii, and the immune system of its Drosophila host.