Analysis of the RpoS regulon in Borrelia burgdorferi in response to mammalian host signals provides insight into RpoS function during the enzootic cycle.

Borrelia burgdorferi (Bb) adapts to its arthropod and mammalian hosts by altering its transcriptional and antigenic profiles in response to environmental signals associated with each of these milieus. In studies presented here, we provide evidence to suggest that mammalian host signals are important for modulating and maintaining both the positive and negative aspects of mammalian host adaptation mediated by the alternative sigma factor RpoS in Bb. Although considerable overlap was observed between genes induced by RpoS during growth within the mammalian host and following temperature-shift, comparative microarray analyses demonstrated unequivocally that RpoS-mediated repression requires mammalian host-specific signals.

Epizootiology of Myxobolus cerebralis, the causative agent of salmonid whirling disease in the Rock Creek drainage of west-central Montana.

Whirling disease, caused by the myxozoan parasite Myxobolus cerebralis, remains a health threat to salmonid fish in the western United States. Although various aspects of this host-parasite system have been studied, investigations examining the overall epizootiology of whirling disease in an ecosystem are lacking. Therefore, in June 1998, studies were initiated in the Rock Creek watershed of west-central Montana and continued through 2003 to assess the intensity of infection in trout using sentinel cages stationed throughout the drainage.

Artificial regulation of ospC expression in Borrelia burgdorferi.

Outer surface lipoprotein (Osp) C is a virulence factor required for transmission of the Lyme disease agent, Borrelia burgdorferi. We have constructed an inducible promoter system to study the function and regulation of OspC by integrating regulatory elements from the Escherichia coli lac operon into the B. burgdorferi genome.

Whirling disease of salmonid fish: life cycle, biology, and disease.

Myxobolus cerebralis is the myxozoan parasite responsible for causing whirling disease in salmonid fish. Although the parasite was first described nearly 100 yr ago, it received relatively little attention until the discovery of its 2-host life cycle in the mid 1980s. This was the first, complete, myxozoan life cycle to be described, and it was greeted with some skepticism because it united 2 stages of M.

Phylogenetic analysis of intestinal microflora indicates a novel Mycoplasma phylotype in farmed and wild salmon.

All studies of the microbial community of the gastrointestinal tract of salmon to date have employed culture-based approaches, typically on pond- or tank-raised, freshwater animals. We present a phylogenetic survey of the bacterial populations present in the distal intestine of salmon from three different marine locations in Europe. This was accomplished through PCR amplification, cloning, and sequencing of partial 16S rDNA genes from microbial community DNA isolated from the contents of the GI tract distal to the pyloric ceca.