Influence Of Symbiotic Wolbachia And Cardinium Bacteria On Oogenesis Of The Laodelphax Striatellus And Sogatella Furcifera

Bacterial pathogens have unique traits that provide a survival advantage after infection of the hosts. Some pathogens manipulate the immune response of its hosts, while some pathogens can prevent apoptosis during infection. The research of bacterial pathogens to inhibit apoptosis in eukaryotic cells is a rising theme. Wolbachia is an example of bacteria with this ability. Wolbachia is a group of Gram-negative, obligatory intracellular and maternally transmitted a-proteobacterium, and is well-known sex ratio distorters that can manipulate the reproduction of hosts through ways such as cytoplasmic incompatibility (CI), male-killing, thelytokous parthenogenesis and feminization to enhance its transmission.We investigate the artificial transfection of Wolbachia in L. Striatellus and S. furcifera. Some recent data suggest Wolbachia are associated with in the reproductive abnormalities in their hosts, in addition, tthere are different degrees of impact on the fitness costs and benefits of host populations. Previous studies have shown that S. furcifera and L. striatellus were infected Wolbachia with the same strain. We use the method of using microinjection of people will striatellus not infected with Wolbachia injected into the white-backed planthopper, the results showed it was hard to transfect Wolbachia strains from L. Striatellus to S. furcifera. Those results suggested that the main reason of Wolbachia strains originated from L. striatellus can not transfect to S. furcifera was correlated with the host genetic background variation and it might be connected with host immunity.We investigate the influence of symbiotic Wolbachia bacteria on oogenesis in L. Striatellus and S. furcifera. In L. Striatellus, Wolbachia could cause intense CI, and the CI level was quite high and even aged males strongly caused CI. In addition, L. Striatellus containing the symbiotic bacteria exhibit reproductive advantage. Previous studies have shown that S. furcifera and L. striatellus were infected with the same strain of Wolbachia. In S. furcifera, there is other intracellular symbiont Cardinium which is also one leading factor of CI. It has been reported that the Longitudinals lacking(Lola) is acting in a pathway leading to the regulation of PCD during oogenesis, and the WW domain containing oxidoreductase (WWOX) gene is a pro-apoptotic gene. In order to reveal whether Wolbachia. providing benefits to its host, we removed the Wolbachia by antibiotic treatment and detected apoptosis of the nurse cells during oogenesis in symbiotic and aposymbiotic individuals of L. Striatellus and S. furcifera. In addition, we also use antibiotics to remove Cardinium in S. furcifera. Finally, comparing the expression levels of WWOX and Lola genes in ovaries of symbiotic and aposymbiotic individuals.The apoptosis-specific TUNEL assay demonstrated significant apoptosis of the nurse cells of Wolbachia-uninfected L. striatellus females during the pre-spawning period. At this stage apoptosis also occurred in the ovarioles of Wolbachia-infected L. striatellus females. In comparison with Wolbachia-uninfected females, the apoptosis of nurse cells of Wolbachia-infected females was reduced. For S. furcifera, there was no difference in apoptosis of the nurse cells between symbiotic and aposymbiotic individuals. Apoptosis occurs at several stages during oogenesis and it is an essential component of insect oogenesis in response to both developmental and environmental stimuli. Our result suggests that Wolbachia reduces apoptosis of nurse cells in L. striatellus. Furthermore, significant differences of the WWOX and Lola genes were detected between symbiotic and aposymbiotic females. The results of qRT-PCR showed that transcripts of WWOX and Lola genes were detected from the Wolbachia-infected and uninfected ovaries of 5-6 days after the L. striatellus emergence. The Lola gene expression reached a significantly low level on the Wolbachia-infected L. Striatellus. WWOX gene expression had a similar result. Our results show that, in L. Striatellus, the presence of Wolbachia leads to the expression levels of WWOX and Lola genes which associated with PCD in ovaries significant down-regulation.