Showing papers by "R. Wayne Litaker published in 2003"

Identification of pfiesteria piscicida (dinophyceae) and pfiesteria-like organisms using internal transcribed spacer-specific pcr assays1

Abstract: The putative harmful algal bloom dinoflagellate, Pfiesteria piscicida (Steidinger et Burkholder), frequently co-occurs with other morphologically similar species collectively known as Pfiesteria -like organisms (PLOs). This study specifically evaluated whether unique sequences in the internal transcribed spacer (ITS) regions, ITS1 and ITS2, could be used to develop PCR assays capable of detecting PLOs in natural assemblages. ITS regions were selected because they are more variable than the flanking small subunit or large subunit rRNA genes and more likely to contain species-specific sequences. Sequencing of the ITS regions revealed unique oligonucleotide primer binding sites for Pfiesteria piscicida , Pfiesteria shumwayae (Glasgow et Burkholder), Florida “Lucy” species, two cryptoperidiniopsoid species, “H/V14” and “PLO21,” and the estuarine mixotroph, Karlodinium micrum (Leadbetter et Dodge). These PCR assays had a minimum sensitivity of 100 cells in a 100-mL sample (1 cell·mL � 1 ) and were successfully used to detect PLOs in the St. Johns River system in Florida, USA. DNA purification and aspects of PCR assay development, PCR optimization, PCR assay controls, and collection of field samples are discussed.

Tritrichomonas foetus and not pentatrichomonas hominis is the etiologic agent of feline trichomonal diarrhea

Abstract: Recently, several investigators have reported large-bowel diarrhea in cats associated with intestinal trichomonad parasites. These reports have presumptively identified the flagellates as Pentatrichomonas hominis, an organism putatively capable of infecting the intestinal tracts of a number of mammalian hosts, including cats, dogs, and man. The purpose of the present study was to determine the identity of this recently recognized flagellate by means of rRNA gene sequence analysis; restriction enzyme digest mapping; and light, transmission, and scanning electron microscopy (SEM).

Airborne detection of ecosystem responses to an extreme event: Phytoplankton displacement and abundance after hurricane induced flooding in the Pamlico-Albemarle Sound System, North Carolina

Abstract: Airborne laser-induced fluorescence measurements were used to detect and monitor ecosystem wide changes in the distribution and concentration of chlorophyll biomass and colored dissolved organic matter in the Pamlico-Albemarle Sound system, North Carolina, U.S., following massive flooding caused by a series of three hurricanes in the late summer of 1999. These high-resolution data provided a significantly more detailed representation of the overall changes occurring in the system than could have been achieved by synoptic sampling from any other platform. The response time for the distribution of chlorophyll biomass to resume pre-flood conditions was used as a measure of ecosystem stability. Chlorophyll biomass patterns were reestablished within four mo of the flooding, whereas higher chlorophylla biomass concentrations persisted for approximately 6 mo. The primary trophic level in the Pamlico-Albemarle Sound system returned to equilibrium in less than a year of a major perturbation.

Extreme events and ecological forecasting

Abstract: Almost all extreme events lasting less than several weeks that significantly impact ecosystems are weather related. This review examines the response of estuarine systems to intense short-term perturbations caused by major weather events such as hurricanes. Current knowledge concerning these effects is limited to relatively few studies where hurricanes and storms impacted estuaries with established environmental monitoring programs. Freshwater inputs associated with these storms were found to initially result in increased primary productivity. When hydrographic conditions are favorable, bacterial consumption of organic matter produced by the phytoplankton blooms and deposited during the initial runoff event can contribute to significant oxygen deficits during subsequent warmer periods. Salinity stress and habitat destruction associated with freshwater inputs, as well as anoxia, adversely affect benthic populations and fish. In contrast, mobile invertebrate species such as shrimp, which have a short life cycle and the ability to migrate during the runoff event, initially benefit from the increased primary productivity and decreased abundance of fish predators. Events studied so far indicate that estuaries rebound in one to three years following major short-term perturbations. However, repeated storm events without sufficient recovery time may cause a fundamental shift in ecosystem structure (Scavia et al. 2002). This is a scenario consistent with the predicted increase in hurricanes for the east coast of the United States. More work on the response of individual species to these stresses is needed so management of commercial resources can be adjusted to allow sufficient recovery time for affected populations.