A new study by Boston University researchers sheds light on some of these processes by providing evidence that A new study by Boston University researchers sheds light on some of these processes by providing evidence that Wolbachia target the ovarian stem cell niches of its hosts—a strategy previously overlooked to explain how Wolbachia thrive in nature. Wolbachia target the ovarian stem cell niches of its hosts—a strategy previously overlooked to explain how Wolbachia thrive in nature.

The study, “Evolutionarily conserved Wolbachia-encoded factors control pattern of stem-cell niche tropism in Drosophila ovaries and favor infection,” has been published in the current issue of PNAS Early Edition.

Although Wolbachia are mainly vertically transmitted (from the parental generation of the species to the offspring), there is also evidence of extensive horizontal transmission (from one individual to another in the same generation). The study shows that both vertical and horizontal transmission occurs through

“Because Wolbachia are maternally transmitted, their presence in the germ line is essential for their vertical propagation to the next generation,” says Michelle Toomey, Boston University PhD student who, with Kanchana Panaram, a former postdoctoral fellow in the Frydman Lab at the Department of Biology, are the study’s co-first authors. “However, Wolbachia are often found in several somatic tissues as well, and this distribution varies among different Wolbachia–host associations.”

The study indicates it is easier for Wolbachia to reach the germ line through the stem cell niches during vertical transmission and probably during horizontal transmission as well.

“Wolbachia represent the first reported case of bacteria living in a stem cell niche. The data presented in this study provide the foundation for future methodologies toward the identification of genetic pathways mediating Wolbachia’s stem-cell niche tropism in hosts,” says Horacio Frydman, assistant professor of biology. Understanding the basis of Wolbachia targeting of specific tissues in the host and its consequences toward bacterial transmission will provide further insight into their extremely successful propagation and help identify new Wolbachia-based vector control approaches.

The study was co-authored by Michelle E. Toomey, Department of Biology and National Emerging Infectious Disease Laboratory, Boston University; Kanchana Panaram, Department of Biology, Boston University; Eva M. Fast, Department of Biology, Boston University; Catherine Beatty, Department of Biology, Boston University, and Horacio M. Frydman, Department of Biology and National Emerging Infectious Disease Laboratory, Boston University.