Development And Verification Of A Model For The Population Dynamics Of The Protistan Parasite, Perkinsus Marinus, Within Its Host, The Eastern Oyster, Crassostrea Virginica, In Chesapeake Bay

A simulation model was developed to investigate the population dynamics of the protistan parasite, Perkinsus marinus, within its host, the eastern oyster, Crassostrea virginica. The main objective was to evaluate the relationship between P. marinus population dynamics and environmental conditions in order to predict the onset and termination of P. marinus epizootics in Chesapeake Bay oyster populations. Information derived from laboratory experiments and from direct field observations of P. marinus dynamics in the James River for the years 1990 to 1993 was utilized for model development. The individual-based model, which is driven by temperature and salinity, tracks the average within-host parasite density at a daily time step. The model was verified against monthly field observations of parasite abundance for the years 1994 to 1999 at three oyster bars located along a 0-20-ppt salinity gradient in the James River, Virginia. Simulated populations exhibited a distinct seasonal periodicity with annual density maximums and minimums occurring in October and May, respectively. Parasite abundance decreased in an upriver direction with decreasing salinity along the salinity gradient. Predicted parasite densities significantly correlated with actual observed densities at all three locations; however, the strength of the association decreased from bar to bar in an upriver direction. Predicted parasite abundance exhibited a dynamic steady state for all three oyster bars during the 6-year time series. Simulations run without the input of a midsummer transmission event resulted in a destabilization and extinction of the parasite from the oyster population located farthest upriver. but the parasite remained enzootic during the six year simulation at the two lower river stations. This suggests that a single transmission event may be sufficient for P. marinus to become enzootic in specific year classes of oyster populations located in moderate to high salinity areas, while periodic transmission events are required for the parasite to persist in low salinity areas. Simulation results suggest that fairly accurate quantitative predictions of P. marinus abundance can be made using in situ temperature and salinity data and a relatively simple model

Natural Disease Resistance in Threatened Staghorn Corals

Disease epidemics have caused extensive damage to tropical coral reefs and to the reef-building corals themselves, yet nothing is known about the abilities of the coral host to resist disease infection. Understanding the potential for natural disease resistance in corals is critically important, especially in the Caribbean where the two ecologically dominant shallow-water corals, Acropora cervicornis and A. palmata, have suffered an unprecedented mass die-off due to White Band Disease (WBD), and are now listed as threatened under the US Threatened Species Act and as critically endangered under the IUCN Red List criteria. Here we examine the potential for natural resistance to WBD in the staghorn coral Acropora cervicornis by combining microsatellite genotype information with in situ transmission assays and field monitoring of WBD on tagged genotypes. We show that six percent of staghorn coral genotypes (3 out of 49) are resistant to WBD. This natural resistance to WBD in staghorn corals represents the first evidence of host disease resistance in scleractinian corals and demonstrates that staghorn corals have an innate ability to resist WBD infection. These resistant staghorn coral genotypes may explain why pockets of Acropora have been able to survive the WBD epidemic. Understanding disease resistance in these corals may be the critical link to restoring populations of these once dominant corals throughout their range

The interest of the Spanish network of investigators in back pain for rehabilitation physician

Background: The Spanish Back Pain Research Network (REIDE) brings together teams of researchers and clinicians who are interested in nonspecific neck and back pain (BP). Its objective is to improve the efficacy, safety, effectiveness, and efficiency of the clinical management of BP. Method: The Network welcomes clinicians and researchers interested in BP. The only requirement to become a member of REIDE is to take part in one of its research projects, and any member can propose a new one. The Network supports those projects that are of interest to two or more groups by assuming their administration and management, which allows the researchers to focus on their task. Its working method ensures methodological quality, a multidisciplinary approach, and the clinical relevance of those projects that are carried out. Results: 179 researchers from 11 areas in Spain are involved in REIDE, including experts in all of the relevant fields of BP research. Most Spanish studies on BP that have been published in international scientific journals come from the teams involved in REIDE, and it currently has 13 ongoing research projects. Conclusions: The Network can help to enhance research among rehabilitation specialists who are interested in BP, and can contribute to the development of research projects which are of interest to the specialty. © 2005 Sociedad Española de Rehabilitación y Medicina Física (SERMEF) y Elsevier España, S.L