Rogerson, Andrew
http://hdl.handle.net/10211.3/121893
2024-03-29T08:16:34Z
2024-03-29T08:16:34Z
Protozoan Epibionts on the Prop Roots of the Red Mangrove Tree, Rhizaphora mangle
Maybruck, Brian T.
Rogerson, Andrew
http://hdl.handle.net/10211.3/123732
2014-10-02T10:05:34Z
2004-01-01T00:00:00Z
Protozoan Epibionts on the Prop Roots of the Red Mangrove Tree, Rhizaphora mangle
Maybruck, Brian T.; Rogerson, Andrew
Despite the importance of understanding carbon flow in mangrove systems, relatively
little research has focused on the grazing protozoan populations inhabiting these
sensitive areas. A conspicuous feature of the mangrove tree is the array of emergent
aerial roots that are covered in epibiont film. This study is the first to consider the
numbers of protozoa inhabiting this dense surface film layer. No obvious temporal
pattern was detected throughout a one year sampling program; numbers of protozoa
were variable between sampling events but always abundant. Heterotrophic flagellates
averaged 2.7 x 10^3 g^- 1 dry film, amoebae were the next most abundant group at 7.7 x 10^3 g^- 1 dry wt and ciliates averaged 4.8 x 10^3 g^- 1 dry wt. In this non -limited substrate
environment, bacteria were numerous averaging 6.9 x 10^9 cells g^ -1 dry wt as were the
other possible prey items, the cyanobacteria (9.8 x 10^6 cells g^- 1 dry wt) and pennate
diatoms ( 2.4 x 10^6 cells g ^-1 dry wt). It was estimated that the combined protozoan
population was only removing about 3% of bacteria carbon d 1, suggesting that
micrograzers are not major regulators of bacterial carbon in this specialized habitat.
Some preliminary trials comparing the growth of protozoa (as generation time) on
tightly and loosely associated bacteria suggest that amoebae are more capable of
removing tightly-associated bacteria than the other micrograzers. Since these attached
bacteria are likely to be involved in the degradation of mangrove carbon, this observation
suggests a possible important ecological role for amoebae in the film community.
Copyright of and published by The International Journal of Protistology, in affiliation with Protozoological Society RAS, Institute of Cytology RAS, and Penza State University. The definitive version of this article is available at: http://protistology.ifmo.ru/
2004-01-01T00:00:00Z
Acanthamoeba in the Domestic Water Supply of Huntington, West Virginia, U.S.A.
Trzyna, W.C.
Mbugua, M.W.
Rogerson, Andrew
http://hdl.handle.net/10211.3/123343
2014-10-02T09:33:26Z
2010-04-01T00:00:00Z
Acanthamoeba in the Domestic Water Supply of Huntington, West Virginia, U.S.A.
Trzyna, W.C.; Mbugua, M.W.; Rogerson, Andrew
The aim of this study was to determine the prevalence of Acanthamoeba in the domestic water supply in Huntington, West Virginia (U.S.A.) and the factors that may contribute to their presence or absence. One hundred sixty-two one liter tap water samples were collected over eight months. Amoebae in the samples (cysts or trophozoites) were harvested by passively filtering onto 5 µm pore size filters and enriching for amoebae on non-nutrient amoeba saline agar plates seeded with Escherichia coli for cultivation. Thirteen percent of all samples were positive for amoebae and 9.3% were positive for the amoeba of interest, Acanthamoeba. Chlorine levels were determined for samples at the time of collection, yielding a mean level of 1.56 mg 1^(-1) chlorine in the distribution system ca. 8 kilometers from the water treatment plant. Cysts and trophozoites of Acanthamoeba clonal isolates were found to tolerate up to 50 mg 1^(-1) and 4 mg 1^(-1) chlorine respectively. This study showed that Acanthamoeba were present in the domestic water supply in Huntington, WV and although no attempt was made to count cells in liter samples, their frequency of occurrence (9.3%) and failure to be present in all replicates, suggests they were present at background levels of perhaps a few cells per five liters. This is only the second U.S. study to consider amoebae in tap water and is unique since the source water was river water. Acanthamoeba trophozoites and cysts were able to withstand levels of chlorine higher than those typically found in tap water suggesting they may be present in either form in the distribution system. Acanthamoeba are opportunistic pathogens capable of causing eye infections and their presence in tap water is a potential risk factor for susceptible individuals, particularly contact lens wearers who may use tap water to clean lenses and storage cases.
Published by and copyright of Jagiellonian University Press. The definitive version of this article is available at: https://www.wuj.pl/UserFiles/File/acta%20protozoologica/Acta%20Protozoologica%2049/2010/Text_49_1_2010/protozoologica2.pdf
2010-04-01T00:00:00Z
Tolerance of Naked Amoebae to Low Oxygen Levels with an Emphasis on the Genus Acanthamoeba
Cometa, Ivan
Schatz, Scott
Trzyna, Wendy
Rogerson, Andrew
http://hdl.handle.net/10211.3/123340
2014-10-02T09:37:15Z
2011-05-01T00:00:00Z
Tolerance of Naked Amoebae to Low Oxygen Levels with an Emphasis on the Genus Acanthamoeba
Cometa, Ivan; Schatz, Scott; Trzyna, Wendy; Rogerson, Andrew
Amoebae feed on attached bacteria within, and below, bacterial biofilms where they experience reduced oxygen levels. The
implications of this were examined by comparing the migration (an index of growth) of thirteen strains of Acanthamoeba and five species of
naked amoebae grown under microaerophilic and aerobic conditions. All amoebae replicated well under both conditions and twelve isolates
migrated significantly faster under low oxygen. Only one isolate, Vannella sp., migrated further (presumably grew faster) under aerobic
conditions. The data show most amoebae prefer low oxygen as befits the biofilm habitat. Interestingly, the eleven acanthamoeba strains
that replicated faster under microaerophilic conditions were all T4 genotypes and included four strains isolated from patients with amoeba
keratitis (AK) infections. This genotype is most frequently found in AK cases and it is suggested that strains of Acanthamoeba capable rapid
growth in a biofilm of a poorly cleansed contact lens may be an important factor in the development of an effective infective dose when
placed on the cornea.
Published by and copyright of Jagiellonian University Press. The definitive version of this article is available at: http://www.ejournals.eu/Acta-Protozoologica/Tom-50(2011)/50/art/801/
2011-05-01T00:00:00Z
Efficacy of Hand Held, Inexpensive UV Light Sources on Acanthamoeba, Causative Organism in Amoebic Keratitis
Cometa, Ivan
Rogerson, Andrew
Schatz, Scott
http://hdl.handle.net/10211.3/121897
2014-10-02T06:24:33Z
2010-01-01T00:00:00Z
Efficacy of Hand Held, Inexpensive UV Light Sources on Acanthamoeba, Causative Organism in Amoebic Keratitis
Cometa, Ivan; Rogerson, Andrew; Schatz, Scott
Multipurpose lens cleaning solutions (MPS) fail to consistently kill or inactivate Acanthamoeba cysts and UV irradiation, while effective at high doses, can damage contact lenses. The present study considered synergy of action between MPS and hand-held inexpensive (ie, relatively weak) UV irradiation units. Regardless of disinfection method recently formed cysts (<10 days) were far more susceptible to treatment than mature cysts (>14 days). This has important implications for future protocols on testing methods for killing amoebae. The study also showed that cysts of different strains (two tested, FLA2 and P120) are variable in their response to MPS, presumably reflecting differences in cyst wall structure and thus permeability to the disinfectant. On the other hand, the effect of UV irradiation was not wall structure dependent. A 6-hour treatment with MPS alone killed trophic amoebae but failed to kill any mature cysts. Cysts of strain FLA2 were killed after 24 hours with MPS but cysts of strain P120 survived. UV irradiation with the larger 4 W unit killed all cysts after 7 minutes and was more effective than the smaller battery-powered unit (after 10 minutes about 50% of cysts were killed). When the larger unit was used with the MPS disinfection, all trophozoites were killed using UV for 3 minutes and MPS for 1 hour. The resistant P120 cysts remained a challenge but a 2- to 4-minute UV treatment followed by MPS for 3 or 6 hours reduced mature cyst survival by about 50%. The small unit in combination with MPS was less effective but did reduce the time required to kill trophic amoebae in MPS (6 hours MPS alone versus 3 hours MPS with a 1-minute UV treatment). In short, inexpensive UV units do enhance MPS disinfection and future lens cleaning systems/protocols might capitalize on this synergistic action.
© 2010 Cometa et al, publisher and licensee Dove Medical Press Ltd. This is an Open Access article which permits unrestricted noncommercial use, provided the original work is properly cited.
2010-01-01T00:00:00Z