IR Home
DAO
Home
Editors
Forthcoming
Information
Journals
Home
MEPS
AME
CR
DAO
ESEP
Search
Subscribe
Book Series
EE Books
Top Books
ESEP Books
Order
EEIU Brochures
(pdf format)
Discussion Forums
Home
Research
Endangered Species Programs
Institutions
International Ecology Institute
Eco-Ethics International Union
Foundation
Otto Kinne Foundation
 | |
DAO 56:145-154 (2003)
|
Abstract
|
Mapping multiple genetic loci associated with Ceratomyxa shasta resistance in Oncorhynchus mykiss
Krista M. Nichols1,3,*, Jerri Bartholomew2, Gary H. Thorgaard1
1School of Biological Sciences and Center for Reproductive Biology, Washington State University, Pullman, Washington 99164-4236, USA
2Center for Fish Disease Research, Department of Microbiology, Oregon State University, Corvallis, Oregon 97331-3804, USA
3Present address: National Oceanic and Atmospheric Administration, Northwest Fisheries Science Center, Conservation Biology Division, 2725 Montlake Blvd E, Seattle, Washington 98112, USA
*Email: krista.nichols@noaa.gov
ABSTRACT: Ceratomyxa shasta is enzootic to some rivers of the Pacific Northwest and California, and has caused extensive mortalities of salmonids, the only known host of the actinosporean stage of the pathogen. Mortalities from C. shasta are
induced by severe inflammation and necrosis of the intestinal tract, and no therapeutants have been discovered for the treatment of ceratomyxosis. Inheritance studies by previous investigators suggested that C. shasta resistance is genetically
controlled, but none have revealed the number and locations of gene regions associated with resistance. Here, we characterized differences in resistance among clonal lines, and used line crosses between clonal lines with resistance differences for a
genetic analysis of C. shasta resistance in Oncorhynchus mykiss, following a short term in situ exposure to the pathogen. We found that Oregon State University (OSU) x Arlee (ARL) clonal hybrids were highly
susceptible, while OSU x Clearwater (CW) hybrids were highly resistant to C. shasta. Doubled haploids, produced by androgenesis from an F1 hybrid between the OSU and CW lines, were evaluated for the
co-segregation of molecular markers and resistance phenotype. Amplified fragment length polymorphic (AFLP) markers, used to construct a genetic linkage map in this cross, were tested for associations with resistance expressed as absolute survival (binary
trait) and days to death (survival analysis). Segregation of the resistance phenotype suggested that the resistance was inherited as a single Mendelian locus, but the binary trait failed to map to a single genomic location. Markers identified in
single-marker analyses were used in multiple-regression model selection, within both the linear regression and Cox proportional-hazards survival analysis frameworks, to determine the number and potential location of loci simultaneously contributing to
variation in the survival phenotypes of doubled-haploid progeny. We found multiple genomic loci associated with C. shasta resistance through these models, confirming studies by previous investigators that suggested C. shasta resistance is
polygenic.
KEY WORDS: Ceratomyxa shasta · Oncorhynchus mykiss · Survival analysis · Quantitative trait loci
Full text in pdf format
Published in DAO Vol.
56, No. 2
(2003) on September 24
Print ISSN: 0177-5103; Online ISSN: 1616-1580.
Copyright © Inter-Research, Oldendorf/Luhe, 2003
|
