44 research outputs found
Myxomycetes from bark of living trees in Panola Mountain State Park, 1972
No full textThe objectives of this study were: (1) to survey the corticolous myxomycete bionta of a relatively undisturbed and pollution free natural area, (2) to determine whether affinities exists between species of corticolous myxomycetes and species of trees on which they occur, and (3) to determine whether the occurrence of corticolous myxomycetes is seasonal in nature. To accomplish these objectives 42 trees growing in Panoia Mountain State Park, a natural preserved area located approximately 20 miles southeast of Atlanta, were selected for the study. The genera and species of the trees selected were Quercus falcata and Q.prinus, Pinus taeda and P. echinata, Carya glabra, Cornus florida, and Liriodendron tulipifera. Seven collection sites were selected in the Park and each site represented a different ecological setting where one or more trees of each of the seven tree species grew within a few yards of each other. Bark samples were removed at six-week intervals from the selected trees and were subsequently incubated in moisture chambers under laboratory conditions. Frequent examinations of these bark samples were made for the appearance of myxomycete fruiting bodies. In this study, twenty-three species of myxomycetes, representing 12 genera, have appeared on bark collected from trees in Panola Mountain State Park. These species were: Arcyria carnea, A cinerea, and A pomiformis; Comatricha elegans, C fimbriata, C lurida, C nigra, and C suksdorfii; Cribraria microcarpa, C minutissima, and C violacea;Diderma rugosum; Didymium sguamulosum and D megalosporum; Echinostelium minutum; Lamproderma scintillans; Licea operculata; Metatrichia vesparium; Perichaena chrysosperma; Physarum notabile, P nudum, and P viride; Trichia floriformis. The appearance of some species was seasonal and some species were restricted to the bark of certain tree species. Echinostelium minutum, for example, was the most ubiquitous species. It was found throughout the year on bark of all trees sampled. Cribraria minutissima also appeared throughout the year but only on Pinus taeda. Comatricha fimbriata was common in the fall on bark ofQuercus falcata. Data from these studies suggest that affinities exist between bark of some species of trees and species of myxomycetes; that the appearance of some species of corticolous myxomycetes may vary with the season of the year; and that bark of living trees apparently represent a natural substratum for myxomycete bionta. Some of the species of myxomycetes found in this study represent species previously unreported from the state of Georgia
Further studies on corticolous myxomycetes from within the city limits of Atlanta, Georgia, 1976
No full textDuring a twoyear period, beginning in the summer of 1973 and ending in the summer of 1975, a study was conducted on myxomycete bionta from bark of living trees growing in five widely separated localities within the Atlanta city limits. The objectives of the study were to determine (1) whether bark of living trees is a natural substratum for certain kinds of myxomycetes; (2) whether certain myxomycetes manifest affinities for certain species of trees; (3) whether seasonal variations exist in corticolous myxomycete occurrence; and (4) whether any correlation exists between the distribution of corticolous myxomycetes and tree habitats. Since two earlier studies of limited scope represent the only reports of systematic studies on corticolous myxomycetes of Georgia, a need has existed for more extensive information on this myxomycete bionta of the state. This study was undertaken in order to fulfill that need. To accomplish the objectives a total of 171 trees, representing 12 genera and 21 species, growing in five selected areas within the city limits of Atlanta, were chosen for the study. The genus and species of the trees used were Acer and A. saccharinum, Carya illinoensis and C. ovata, Cedrus deodara, Cornus florida, Diospyros virginiana, Liquidambar styraciflua, Liriodendron tulipifera, Ostrya virginiana, Pinus echinata and P. taeda, Prunus serotina, Quercus alba, Q. falcata, Q. nigra, Q. phellos, Q. stellata, and Q. velutina, Ulmus alata and U. americana. The five different localities used in this study included three relatively undisturbed wooded areas and two open park areas. The localities were (1) a wooded area in the Highpoint section; (2) a wooded hillside in the Collier Heights section; in the Beecher Circle section; and (4) two city parks, namely, Washington and Piedmont Parks. Specific plots were selected within each locality for sampling. Each plot was approximately 15 meters square and contained at least one tree of each species that was to be studied. In two of the localities, viz., Collier Heights and Beecher Circle, fallen debris on the forest floor was periodically examined in the field. Five different techniques were used to create conditions favor able for myxomycete development. These techniques were as follows: (1) a modification of the moist chamber technique originally used by Gilbert and Martin; (This modification involved the gradual soaking of bark pieces in sterile petri dishes by adding small volumes of sterile water intermittently as was absorbed by the bark, This practice reduced the possibility of spores being discarded, as may happen when the method of Gilbert and Martin is used.) (2) the placing of bark samples in polyethylene bags and attaching these bags to the sides of the trees from which they were collected; (Sterile distilled water was added to the bags in order to first saturate the bark pieces and subsequently maintain a high humidity.) (3) the removal of bark samples from trees and the incubation of these samples in petri dish moist chambers that were left in the field at the base of the tree from which the samples were removed; (4) the attaching of large waterfilled polyethylene bags to trees at about breast height; (The bags were perforated at the bottom by puncturing the corners and the middle with a few pin holes. This enabled water to slowly drip onto the bark below the bag and consequently keep the trunk in that region continuously moist.) and (5) the periodic examination of undisturbed bark of standing trees with a 1OX hand lens in a search for naturally developing slime molds. Field examinations of leaf litter were also made in order to determine whether myxomycetes that developed in moist chamber on bark samples also developed naturally on plant debris on the forest floor. A total of 46 species of myxomycetes was found during the two years of the study. Forty species of myxomycetes, representing 16 genera, appeared on collected bark samples during the course of the study, and six other species representing six genera were found on field observed leaf litter. The following species of myxomycetes were found: Arcyria carnea, A. cinerea and A. nutans, Badhamia nitens and B. obovata, Calomyxa metallica, Ceratiomyxa fruitculosa, Clastoderma debaryanum, Comatricha elegans, C. fimbriata, C. lurida, C. nigra and C. pulchella, Cribraria minutissima and C. violacea, Dictydium cancellatum, Diderma hemispaericum, Didymium difforme, D. iridis and D. squamulosum, Echinostelium minutum, Enerthenema papillatum, Fuligo septica, Hemitrichia stipitata, Lamproderma scintillans, Licea erecta, L. kleistobolus and L. operculata, Lycogala epidendrum, Macbrideola cornea, M. decapillata, M. martini, M. scintillans and M. synsporos, Metatrichia vesparium, Perichaena chrysosperma and P. minor, Physarum cinereum, P. crateriforme, P. decipiens, P. leucophaeum, P. nutans and P. viride, Stemonitis axifera, S. flavogenita, S. fusca and S. virginiensis The data from this study shows that some myxomycete species will develop only on bark from living trees, some species develop only on forest floor debris, and some species will develop on bark of living trees as well as on fallen debris. The species that appeared on fallen debris as well as on tree bark were Arcyria carnea and A. nutans, Physarum cinereum, P. nutans and P. viride, Stemonitis axifera and S. fusca. The species that were found on bark from living trees but were not found on fallen debris were Badhamia obvata, Clastoderma debaryanum, Comatricha fimbriata, C. elegans, and C. nigra, Cribraria minutissima, C. violacea, Didymium squamulosum, Licea erecta, L. kleistobolus and L. operculata, Macbrideola synsporos, Perichaena chrysosperma and P. minor, Physarum crateriforme, P. decipiens, and P. leucophaeum. The species of slime molds that were found on forest floor litter but were not found on bark of living trees were Ceratiomyxa fruitculosa, Dictydium cancellatum, Fuligo septica, Hemitrichia stipitata, Lycogala epidendrum, and Metatrichia vesparium. Echinostelium minutum is a ubiquitous species for it was common on bark from living trees as well as on fallen plant debris. Throughout this study variations were noted in the number of species of slime molds appearing on incubated bark samples during different seasons of the year. Echinostelium minutum appeared throughout the year on bark of all trees sampled except Acer negundo, A. saccharinum, Cedrus deodara, and Quercus phellos. Didymium squamulosum was found throughout the entire collecting period, except for the spring of 1974. Except for the summer of 1973, Comatricha fimbriata appeared on bark samples collected each season over the twoyear period of study. In some instances a slime mold may have appeared during a particular season in one year and may not have been found the following year during the same season. For example, Arcyria nutans was found during the winter of 1974, but was not found during the winter of 1973. Comatricha lurida appeared during the spring of 1974. Comatricha pulchella appeared only during the winter of 1974 as did Didymium difforme. Some slime mold species appeared only once during the course of the study. Macbrideola cornea and M. decapillata, Physarum cinereum, and Stemonitis axifera, are examples of species that were found once. Based on the data from this study, bark of living trees appear to represent a natural substratum for some species of myxomycetes. Some general affinity is apparent between some species of trees and some species of myxomycetes, depending upon the locality. Also, the appearance of some species of corticolous myxomycetes may vary with the season of the year, and some correlation appears to exist between the distribution of some myxomycete species and tree habitat. Some of the myxomycetes found in this study represent species previously unreported from the state. Those species are Calomyxa metallica, Clastoderma debaryanum, Badhamia nitens, B. obovata, Licea erecta, Macbrideola cornea, M. decapillata, M. martinii and M. synsporos, Perichaena minor, Physarum crateriforme, P decipiens and P. leucophaeum
Myxomycetes of Panola Mountain State Park, 1978
No full textThe objective of this study was to survey the myxomycete population as it exists at Panola Mountain State Park, concentrating on those species found living on natural litter such as rotting logs, grass, leaves, and twigs. Some samples were taken from the bark of living trees but this substrate was not collected from frequently. The collecting area was restricted by the property boundaries of Panola Mountain State Park, a natural area day-use park located eighteen miles southeast of Atlanta on Georgia 155. Collections were made throughout this 537 acre tract of park land. Sampling began during the early summer of 1976 and continued through early fall of 1977. There were thirty species of myxomycetes collected during this study. Those species collected were as follows: Arcyria cinerea, A. denudata, A. incarnata, Comatricha aequalis, C. pulchella, Craterium leuco- cephalum, C. minutum, Cribraria lanquescence, C. micro- carpa, Diachea leucopodia, Dictydium cancellatum, Didy- mium nigripes, D. ovoideum, D. squamulosum/ Fuligo septica, Hemitrichia calyculata, Lamproderma arcyrionema, L. scintillans, Lycogola epidendrum, Metatrichia vesparium, Physarum bivalve, P. leucophaeum, P. mellemn, P. nutans, P. polycephalum, P. superbum, P. viride, Stemonitis auxi- fera, S. fusca, and Tubifera microsperma. All of the species collected have been reported as found in Georgia. Many of the species were reported by Pendergrass in his studies of myxomycetes living on the bark of living trees at Panola Mountain State Park and other areas in and around Atlanta
Health Hazard Evaluation Report: HETA 96-0032-2649: A. W. Dimock Laboratory, Cornell University, Ithaca, New York
No full textIn response to a request from Cornell University, a health hazard evaluation was conducted at the A. W. Dimock Laboratory (SIC-0181), Cornell University, Ithaca, New York. Concern had been expressed regarding exposure of researchers and greenhouse workers to nicotine (54115). The greenhouse contained a variety of plants used to study the transmission of viruses by aphid vectors. Nicotine alkaloid was used in a biweekly rotation about every 6 weeks with other fumigants. Personal breathing zone samples from three workers indicated that they were not exposed to levels of nicotine which exceeded the recommended limits. Area air samples were collected before, during and after a 13-hour fumigation process. Within 10 minutes of the start of fumigation the nicotine concentrations inside the sections peaked at 3.3mg/m3 but fell within 60 minutes to less than the 0.5mg/m3 limit. Wipe samples on commonly used surfaces showed that residual nicotine levels in some locations were 60 times higher after fumigation. The author concludes that airborne nicotine concentrations did not represent a hazard to greenhouse personnel. As nicotine is readily absorbed through the skin, the author recommends that workers remove or cover portable tools and hoses during fumigation and use gloves and good personal hygiene practices
Quantifying metastatic inefficiency:rare genotypes versus rare dynamics
No full textWe introduce and solve a 'null model' of stochastic metastatic colonization. The model is described by a single parameter ?: the ratio of the rate of cell division to the rate of cell death for a disseminated tumour cell in a given secondary tissue environment. We are primarily interested in the case in which colonizing cells are poorly adapted for proliferation in the local tissue environment, so that cell death is more likely than cell division, i.e. ? 1, we find that the probability of establishment is exponentially rare, as expected, and yet the mean time for such rare events is of the form ~log (N)/(1 - ?) while the standard deviation of colonization times is ~1/(1 - ?). Thus, counter to naive expectation, for ? 1), i.e. the statistics show a duality mapping (1 - ?) --> (? - 1). We conclude our analysis with a study of heterogeneity in the fitness of colonising cells, and describe a phase diagram delineating parameter regions in which metastatic colonization is dominated either by low or high fitness cells, showing that both are plausible given our current knowledge of physiological conditions in human cancer
Health Hazard Evaluation Report: HETA 97-0004-2642: Centre Foundry & Machine Company, Wheeling, West Virginia
No full textIn response to a confidential request, a health hazard evaluation was conducted at Centre Foundry and Machine Company (SIC-3321), Wheeling, West Virginia. The company employed 52 workers in the manufacture of grey iron castings used in steel production. All seven personal breathing zone (PBZ) samples taken were over the limit for respirable silica (14808607). Several also exceeded the limits for iron (7439896) and manganese (7439965). One carbon- monoxide (630080) sample exceeded the limit of 35 parts per million (ppm). Air concentrations of resorcinol (108463), furfuryl-alcohol (98000), aluminum (7429905), barium (7440393), chromium (7440473), magnesium (7439954), nickel (7440020), phosphorus (7723140), titanium (7440326), and zinc (7440666) were below the respective limits. Levels of p-toluene-sulfonic-acid (104154) ranged from 29 to 125 micrograms/cubic meter. Discussions with workers did not reveal any major health concerns. Some potential safety and health hazards were identified during the walk-through inspection such as the use of compressed air to clean loose sand from castings and cluttered walkways. The author concludes that workers were overexposed to respirable silica, iron, manganese, and carbon- monoxide. Use of respirators would be expected to reduce exposures to silica, iron, and manganese to below exposure limits. The author recommends specific measures to reduce these exposures
Health Hazard Evaluation Report: HETA 95\u20130044\u20132561: Metropolitan St. Louis Sewer District, Bissell Point Wastewater Treatment Plant, St. Louis, Missouri
No full textIn response to an employer request, an industrial hygiene survey was conducted at the Metropolitan St. Louis Sewer Bissell Point Wastewater Treatment Plant (SIC-4952), St. Louis, Missouri. The facility received an average of 111 million gallons per day of wastewater. There were about 100 workers on three shifts. Personal breathing zone and general area air samples were collected along with bulk samples of waste activated sewage sludge and wastewater. Air samples were tested for hydrogen-sulfide (7783064) and endotoxin. No overexposures were noted during the investigation. Waste activated sewage sludge and wastewater samples were analyzed for headspace volatile organic compounds (VOCs). General air samples were analyzed for VOCs. General air samples for individual VOCs were below respective occupational limits. Waste activated sewage sludge and incinerator ash bulk samples were analyzed for elemental composition. The author concludes that belt press room workers were not exposed to hydrogen-sulfide concentrations exceeding the NIOSH ceiling limit of 10 parts per million at the time of the survey. The author recommends that daily monitoring for hydrogen-sulfide be continued due to potential seasonal variations in air concentrations. Personal hydrogen-sulfide monitors and respiratory protection should be used when air concentrations equal or exceed 10 parts per million
Health Hazard Evaluation Report: HETA 94-0405-2551: Metropolitan St. Louis Sewer District, Lemay Wastewater Treatment Plant, St. Louis, Missouri
No full textIn response to a request from the employer and employee representatives of the Metropolitan St. Louis Sewer District, Lemay wastewater treatment facility (SIC-4952), a health hazard investigation was begun. Workers reported headaches, burning sensation to the nose, loss of breath, sore throat, eye irritation, nausea, and diarrhea. There are 101 employees at the site. The maximum hydrogen-sulfide (7783064) concentrations in the personal breathing zone air samples ranged from nondetectable to 20 parts per million (ppm). Only one sample from a maintenance mechanic, which contained 20ppm, exceeded the NIOSH recommended exposure limit ceiling value of 10ppm. Endotoxin concentrations ranged from 1.08 to 5.51 units per cubic meter of air in the personal breathing zone air samples. Volatile organic compounds (VOCs) were identified in general area air samples at levels up to 0.40ppmall concentrations were considered to be quite low. Incinerator ash was found under the incinerators and on the lower floors of the incinerator area. The author concludes that daily monitoring for hydrogen-sulfide should continue. The author recommends that personal hydrogen- sulfide monitors and respiratory protection be used when hydrogen- sulfide concentrations approach or exceed 10ppm
