Invasion: Type III Secretion System
Gram-negative bacteria of the genus Xanthomonas infect more than 300 different species worldwide. Xanthomonas campestris pv. vesicatoria causes bacterial spot disease on pepper and tomato plants.
- The bacteria enter the plant intercellular spaces via natural openings.
- Bacterial surface structures allow the attachment to host cells.
- Xanthomonas produces the extracellular polysaccharide xanthan that protects the bacteria from environmental factors.
- An essential pathogenicity factor is the type III protein secretion system which spans the bacterial membranes…
- … And is associated with an extracellular pilus.
- The pilus is connected to a channel-like translocon that is inserted into the plant plasma membrane.
- The type III secretion system transports approximately 30 different bacterial effector proteins into the plant cell.
- Bacterial effector proteins are transported to different cellular compartments and manipulate host cellular pathways. Some effector proteins reach the plant cell nucleus and modify plant gene expression.
- Effector proteins suppress plant defense responses and promote bacterial multiplication at the infection site.
Video by Bernd Montag, Duc Phan Tran, Felix Herbst, Frank Montag.
One of New York City’s five boroughs, the Bronx is only now beginning to escape the cliches of urban blight that defined it from the 60s through the 80s: arson, drug addiction, and social neglect. But the borough has always been a launching pad for immigrant working families, who since the 30s have had their own beach (the only one in the Bronx), Orchard Beach, created by New York’s master builder and social planner, Robert Moses. Photographer Wayne Lawrence acknowledges the beach’s reputation as one of the worst in the city (‘Horseshit Beach’ is one of its more printable nicknames), but insists that the scarred landscape is nonetheless ‘a treasured respite from the sweltering confines of the concrete jungle’ for Bronx residents. ‘I began shooting portraits of Orchard Beach’s summertime regulars in 2005 shortly after moving to New York,’ he writes by way of introducing the people pictured in his book. He realized, he writes, ‘that the stigma attached to this oasis was largely unjustified—I felt compelled to engage with this community of working class families and colorful characters. The photographs in Orchard Beach: The Bronx Riviera’ celebrate the pride and dignity of the beach’s visitors, working-class people.’