The recent completion of genome sequencing and annotation of the metabolic pathways of Wolbachia from B. malayi have identified important candidates for the dependency of the symbiosis (Foster et al., 2005).  In comparison with insect Wolbachia and related Rickettsia, the genome of Wolbachia from B. malayi is drastically reduced in size, a feature common to the lifestyle of other endosymbiotic bacteria.  However, Wolbachia contain more intact metabolic pathways, which may be important in contributing to the welfare and fecundity of its host.  The ability to provide riboflavin, flavin adenine dinucleotide (FAD), heme and nucleotides are likely to be the bacterial contribution, whereas the host nematode provides amino acids required for bacterial growth with the exception of the only amino acid synthesized by the bacteria, meso-diaminopimelate, a major component of peptidoglycan (Taylor et al., 2005a).  Other features include a common type IV secretion system and an abundance of ankyrin domain containing proteins, which could regulate host gene expression as suggested for Ehrlichia phagocytophilia AnkA (Park et al., 2004; Ijdo et al., 2007).  Glutathione biosynthesis genes may be a source of glutathione for the protection of the host nematode from oxidative stress or immunological effector molecules.  Heme from Wolbachia could be critical to worm embryogenesis, moulting and reproduction are regulated by ecdysteroid-like hormones (Warbrick et al., 1993).  Depletion of Wolbachia might therefore stop production of these hormones and block embryogenesis.  Alternatively, or in addition, Wolbachia may be an essential source of nucleotides during embryogenesis.  Thus, the achievement of the wBm genome provides useful information, which may help to understand the molecular basis for the endosymbiosis between Wolbachia and filarial nematodes.  The novel and test drugs already registered for use in humans, which might inhibit key biochemical pathways in the Wolbachia that could lead to sterility or killing of the adult worms will be screened for these properties  (Taylor et al., 2005a; Ghedin et al., 2007; 2008).

จากคุณ : Nor-mai - [ 24 ก.พ. 52 23:19:47 ]