Sex Steroids in Insects and the Role of the Endosymbiont Wolbachia:A New Perspective

Manipulation of Arthropod Sex Determination by Endosymbionts: Diversity and Molecular Mechanisms

“…It is thus possible that many of the symbiont phenotypes rely on epigenetic mechanisms, particularly those related to histone regulation. Moreover, paternal effects of CI, maternal effects of PI, and mechanisms of early MK may all involve some form of genomic imprinting [Werren, 2011;Negri and Pellecchia, 2012;Rabeling and Kronauer, 2013]. The currently strongest evidence for a role of epigenetics was found by Negri et al [2009] who showed that Wolbachia interferes with host sexual differentiation in the leafhopper Z. pullula by disrupting methylation patterns and genetic imprinting.…”

“…Hormonal manipulation seems mostly associated with feminization, but male killing may also make use of hormonal signals that are different between the sexes. It should, however, be noted that sex determination in insects is generally considered as a cellular genetic process and that the importance of hormonal signaling is still under debate [Steinmann-Zwicky et al, 1989;Schütt and Nöthiger, 2000;Negri and Pellecchia, 2012]. This is informative for the transition between MK and FM which is observed in the moth Ostrinia scapulalis .…”

“…First, Wolbachia has been shown to interact with the insulin pathway in Drosophila [Ikeya et al, 2009]. Even though this pathway is not directly involved in sex determination, insulin-like peptides regulate ecdysteroid synthesis, and recent results indicate that 20-Hydroxyecdysone could play the role of a sex hormone in insects [Negri et al, 2010;Negri and Pellecchia, 2012]. Hormonal manipulation seems mostly associated with feminization, but male killing may also make use of hormonal signals that are different between the sexes.…”

“…The MK in Ostrinia is the first well documented case of direct interference of endosymbionts upon host sex determination genes. Due to being the central gear of the key sex determination gene , transformer is expected to be a particularly likely target for such manipulation in holometabolous insect sex determination [Beukeboom, 2012;Negri and Pellecchia, 2012].…”

Effect of Wolbachia Infection on Aging and Longevity-Associated Genes in Drosophila

“…For example, flies heterozygous for the mutation in the gene encoding ecdysone receptor, EcRV559fs, exhibit increased life span and resistance to various stresses compared to controls without the mutation, with no apparent deficit in fertility or activity (Simon et al 2003). It may be hypothesized that Wolbachia produces regulators able to interact directly or indirectly with ecdysone receptor resulting in modulation of ecdysteroid signaling (Negri and Pellecchia 2012).…”