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1.
The daily and seasonal distribution of airborne fungal particles was recorded in a high altitude tropical zone. Sampling was
carried out in the southern part of Mexico City. An Andersen air sampler was used over a period of six months. Ten minutes
sampling for each set of plates was done at fixed schedule: 07:30, 14:00 and 19:00 hours. The sampler was placed 10 m above
the ground. Daily variation was found to be associated with the season, weather and atmospheric stability. The highest value
of mold counts (3195 CFU m−3) was recorded in the evening on October, a transitional month between the rainy and the dry seasons, the lowest (45 CFU m−3) at noon during the rainy season. Mold counts were significantly correlated with temperature, having negative signs both
in the morning and at noon, and being positive in the evening. The abundance of only three genera was recorded.Cladosporium, was isolated more frequently, and its abundance at 14:00 h was of 38%;Alternaria represented 4.0%, at 14:00 h, andAspergillus 3.0% at 7:30 h. Fifteen species belonging to the latter genera were identified and most of them are considered as opportunistic
molds of clinical significance. 相似文献
2.
Irene Bronillet Tarragó 《Aerobiologia》1996,12(1):191-195
An investigation of airborne pollen in northern Mexico City was carried out for one year. A total of 24 taxa were identified and classified according to the growing form in pollen of trees, weeds and grasses. Pollen grains were recorded all year round with a peak in December. The trees group showed the highest quantity of pollen as well as taxa diversity, although its peak period was in the dry season. The weeds and grasses emitted a larger quantity of pollen in the rainy season. The dominant taxa wereAlnus, Casuarina, Compositae and Gramineae. As for their relation with meteorological parameters, we found that the increase of pollen concentration was related to high temperatures, low relative humidity and high wind speed, the latter causing an increase of airborne pollen with no dilution at all. The hours with the highest pollen concentration where from 16:00 to 18:00. 相似文献
3.
Irene Bronillet Tarragó 《Aerobiologia》1996,12(3):191-195
An investigation of airborne pollen in northern Mexico City was carried out for one year. A total of 24 taxa were identified
and classified according to the growing form in pollen of trees, weeds and grasses. Pollen grains were recorded all year round
with a peak in December. The trees group showed the highest quantity of pollen as well as taxa diversity, although its peak
period was in the dry season. The weeds and grasses emitted a larger quantity of pollen in the rainy season. The dominant
taxa wereAlnus, Casuarina, Compositae and Gramineae. As for their relation with meteorological parameters, we found that the increase of pollen concentration
was related to high temperatures, low relative humidity and high wind speed, the latter causing an increase of airborne pollen
with no dilution at all. The hours with the highest pollen concentration where from 16:00 to 18:00. 相似文献
4.
Thirty homes of asthmatic adults located in Mexico City were examined to determine the predominant culturable fungi and the
changes in their airborne concentrations. Fungi were cultured and identified microscopically from air samples collected in
naturally ventilated homes, during both wet (July–August) and cool dry (November–December) seasons, and from settled dust
from the same homes. Airborne dust from indoor yielded 99–4950 cfu m−3, and settled dust 102–106 cfu g−1 on DG18 agar. The indoor geometric mean concentration of airborne fungi during the cool dry season was 460 cfu m−3 while in the wet season it was 141 cfu m−3. Similarly, numbers of airborne fungal propagules out of doors decreased 60% between the dry and wet season. In general,
the total fungal concentrations in indoor air were less than 103 cfu m−3 and a large proportion of them was collected in Stage-2 of the Andersen sampler. Moreover, the ratio between indoor and outdoor
concentrations was <3:1. Five of the 30 sampled homes yielded >500 cfu m−3 of one genus, with up to 1493Cladosporium cfu m−3 or 2549Penicillium cfu m−3. Also, these two genera were predominant in both airborne and settled dust, and their concentrations were greater indoors
than out, indicating a possible indoor source of fungal propagules. The predominant species wereCladosporium herbarum, Penicillium aurantiogriseum andP. chrysogenum. These results suggest that exposure to large concentrations of fungi occurs indoors and is associated with both seasons
of the year and with particular home characteristics. 相似文献
5.
Roubicek DA Gutiérrez-Castillo ME Sordo M Cebrián-García ME Ostrosky-Wegman P 《Mutation research》2007,631(1):9-15
Particulate air pollution is an important environmental health risk. In the present study, we have investigated the ability of chemically characterized water and organic-soluble extracts of PM(10) from two different regions of Mexico City to induce micronuclei in a human epithelial cell line. We also evaluated the association between the chemical characteristics of the PM and its genotoxicity. The airborne particulate samples were collected from an industrial and a residential region; a Hi-Vol air sampler was used to collect PM(10) on glass fiber filters. PM mass was determined by gravimetric analysis of the filters. One section of each PM(10) filter was agitated either with deionized water to extract water-soluble compounds or with dichloromethane to prepare organic-soluble compounds. The chemical composition of the extracts was determined by ion and gas chromatography and atomic adsorption spectroscopy. A549-human alveolar epithelial cells were exposed to different concentrations of PM(10) extracts and the cytokinesis blocked micronucleus assay was performed to measure DNA damage. Even though the industrial region had a higher PM concentration, higher amounts of metals and PAHs were found in the residential area. Both industrial and residential extracts induced a significant concentration-related increase in the micronuclei frequency. The PM(10) water-soluble industrial extract induced significantly more micronuclei than the one of the residential region; inversely, the organic residential extract induced more micronuclei than the one from the industrial region. The association between the induction of micronuclei and the chemical components obtained by the comparative analysis of standardized regression coefficients showed that cadmium and PAHs were significantly associated with micronuclei induction. Data indicate that water-soluble metals and the organic-soluble fraction of PM(10) are both important in the production of micronuclei. Effects observed, point to the risk of PM exposure and shows the need of integrative studies. 相似文献
6.
Irma Rosas Alma Yela Eva Salinas Roberto Arreguin Adela Rodriguez-Romero 《Aerobiologia》1995,11(2):81-86
The protein associated with airborne particles was measured during 1991 as an indicator of airborne biological material in
different outdoor urban environments. Fifty air samples were collected simultaneously at three sampling sites, located in
the north, south and downtown Mexico City, using a PM10 high-volume sampler (particles<10 μm). The air filters were weighed
and protein extracted using a phosphate buffer. Protein concentrations were determined by Lowry assay. The extracts were also
analysed by SDS electrophoresis and IEF using a Phastsystem. High concentrations of airborne particles were recorded at the
sampling sites with a geometric mean of 70.2 μg/m3 in the south (residential area), 95.5 μg/m3 in the center (urban-commercial area), and with the highest value of 108.9 μg/m3 in the north (urban-industrial area). No statistically significant difference (P>0.05) was observed among the protein concentrations from the sampling sites and the concentrations ranged from non-detectable
to 2.54 μg/m3. However, the protein concentrations presented significant difference (P<0.05) with respect to rainy and dry seasons. The Spearman correlation coefficient between protein concentration and airborne
particles concentration was statistically significant (r=0.50). The molecular weights (MW) and isoelectric points (pI) for the proteins present in some of the extracts were determined.
The values ranged from approximately 8000 to 106 000 Da and the pI values from nearly 4.0 to 5.85. This is important because
the major allergens from inhalants are mostly acidic proteins with molecular weights in the range of 20 000–40 000 Da. 相似文献
7.
C. Calderón J. Lacey A. McCartney I. Rosas 《International journal of biometeorology》1997,40(2):71-80
The effect of an urban climate upon the spatial and temporal distribution of Deuteromycete spores was studied during 1991
using Burkard volumetric spore traps in two areas of Mexico City with different degrees of urbanization. Deuteromycete conidia
formed the largest component of the total airborne fungal spore load in the atmosphere of Mexico City, contributing 52% of
the spores trapped in an urban-residential area (southern area) and 65% of those in an urban-commercial area (central area).
Among the most common spore types, Cladosporium and Alternaria showed a marked seasonal periodicity with significant differences in concentration (P<0.05) between the dry and wet seasons. Maximum conidial concentrations were found during the end of the wet season and the
beginning of the cool, dry season (October–December). Daily mean concentrations of the predominant airborne spore types did
not differ significantly between the southern and central areas. Daily mean spore concentrations were significantly correlated
(P<0.05) in southern and central areas with maximum temperature (south, r = –0.35; central, r = –0.40) and relative humidity (south, r = 0.43; central, r = 0.29) from the previous day. Moreover, multiple regression analysis of spore concentrations with several meteorological
factors showed significant interactions between fungal spores, relative humidity and maximum temperature in both areas. The
diurnal periodicity of Cladosporium conidia characteristically showed two or three peaks in concentration during the day at 0200–0400, ∼ 1400 and 2000–2200 hours,
while that of Alternaria showed only one peak (1200 to 2000 hours) in both areas. Maximum concentrations of these spores generally occurred 2–4 h earlier
in the southern than in the central area. The lag in reaching maximum concentrations in the central area probably resulted
from differences in the local conditions between the study areas, and from spores transported aerially into the city from
distant sources. The analysis of maximum hourly concentrations of Cladosporium and Alternaria spores during 1 month of the dry season (February), and another month of the wet season (September) showed significant differences
between the two study areas. Environmental factors and sources (green areas) affected diurnal changes in conidial concentration
in the southern area (urbanization index, UI, 0.25), but not in the central area (UI 0.97). In general, spore concentrations
were greatest in the southern area when relative humidities were low, and temperatures and wind velocities were high. It was
difficult to establish effects of climatic factors on the spore concentration in the city centre. This probably results from
the large amounts of air pollution, the heat island phenomenon, and from the distant origin of trapped conidia obviating aerial
transport. Nevertheless, the seasonal and diurnal distributions of conidia found were similar to those reported for other
tropical regions of the world.
Received: 13 August 1996 / Accepted: 4 December 1996 相似文献
8.
M. C. Calderón-Ezquerro C. Guerrero-Guerra B. Martínez-López F. Fuentes-Rojas F. Téllez-Unzueta E. D. López-Espinoza M. E. Calderón-Segura A. Martínez-Arroyo M. M. Trigo-Pérez 《Aerobiologia》2016,32(2):225-244
The worldwide human population suffering from allergies continues to increase. Pollen grains are a major source of airborne allergens and significant cause of these diseases. Therefore, continuous monitoring of pollen grains released and transported in the air locally or regionally is required to determine the prevalence of various pollen types and identify intra-day and intra-annual seasonal variations over time. In this study, we developed the first pollen calendar for Mexico City, which includes a large variety of taxa, many of which show a long Main Pollen Season which may last throughout the year. The analysis and comparison of daily, monthly and annual values showed that the occurrence and abundance of the main types of aero-allergenic pollen in the atmosphere were species of Fraxinus, Cupressaceae and Alnus, which occur during the periods from December through March, whereas airborne pollens of several species of Poaceae and Urticaceae occurred throughout the year. The variation in pollen concentration showed that the greatest intra-diurnal variations occurred during the second half of the day. Regarding the relationship of pollen with bioclimatic factors, the increase in temperature favoured the presence of pollen in the air, whereas the increase in pluvial precipitation and relative humidity was associated with a decrease in airborne pollen. Large tracts of the Valley of Mexico have atmospheric conditions that are conducive to the accumulation of airborne particles, including pollen. Anomalous winds from the southeast dominated the surface wind variability during the first months of 2010. These patterns induced extreme values in wind convergence at the lower levels of the atmosphere, which resulted in high concentrations of pollen at our sampling site. We suggest that these conditions are related to the warm phase of the El Niño Southern Oscillation phenomenon (2009–2010). 相似文献
9.
A. Rodríguez M. A. Falcón A. Carnicero F. Perestelo G. De la Fuente J. Trojanowski 《Applied microbiology and biotechnology》1996,45(3):399-403
An extracellular laccase capable of oxidizing ABTS (the diammonium salt of 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic
acid) was detected in ligninolytic cultures of Penicillium chrysogenum. By contrast, no lignin peroxidase, manganese-dependent peroxidase or aryl-alcohol oxidase was detected at any time during
culturing. Both ABTS laccase activity and mineralization of dehydrogenative polymerizate of coniferyl alcohol were regulated
by the C/N ratio in the medium and partially inhibited in the presence of thioglycolic acid, suggesting that both events are
associated. In the presence of several known laccase inducers neither ABTS laccase activity nor mineralization rates were
enhanced. However, a new laccase was detected in P. chrysogenum, able to oxidize 2,6-dimethoxyphenol but not involved in lignin mineralization. Studies with the known ligninolytic basidiomycete
Trametes villosa suggest that lignin degradation by this fungus also involves the action of laccase.
Received: 6 July 1995/Received revision: 28 October 1995/Accepted: 6 November 1995 相似文献
10.
Occurrence of airborne enteric bacteria in Mexico city 总被引:1,自引:0,他引:1
Summary An investigation of microbial air quality in the area of the National Autonomous University of Mexico, located in the southern part of Mexico City, was conducted for one year. Ambient outdoor concentrations and size distribution of airborne bacteria were measured, 130 samples were taken at noon, using an Andersen 6 stage sampler, located 2 m above ground level. Concentration ranges and colony-forming units per cubic meter of air (CFU m–3) found, were as follows:14 to 12999 for total bacteria, No growth (NG) to 55 for coliform bacteria, NG to 11 for fecal coliform and NG to 10 for fecal Streptococci.Bacteria associated with the potentially respirable fraction (0.65 to 4.7 µm) averaged 37% and 9% for total bacteria and coliform bacteria respectively. In 23% of the samples, coliform bacteria were recovered, with higher incidences during dry season. The most common of these were:Escherichia coli (15%), followed bySerratia (13%) andEnterobacter (10%),The total bacteria correlated significatively (p<0.05) with the following parameters: particulate matter smaller than 10 µm (PM10) (r=0.40), total suspended particulates (TSP) (r=0.26), daily variation of temperature (r=0.18), and vapor pressure (r=–0.16). These relationships indicate that fecal soil pollution could affect air quality with potential health risks. 相似文献
11.
It is known that the poor colony-forming ability of B6 bone marrow transplanted into B6D2F1 hybrids can be improved if B6 lymphocytes are given in addition. It was recently reported that the augmenting lymphocytes decrease the doubling time of differentiating hemopoietic cells. To determine whether thymus cells alter the self-renewal of CFUs in this parent leads to F1 combination, retransplantation and 3H-thymidine 'suicide' were employed as methods to determine the cell-division rate. We have observed that in the presence of thymocytes, parental bone marrow cells are seeded more efficiently in the spleen, and the lag phase of the CFUs growth curve is shortened. However, thymic lymphocytes do not increase the slope of the exponential growth phase of CFUs. 相似文献
12.
13.
Meteorological effects on variation of airborne algae in Mexico 总被引:2,自引:0,他引:2
Irma Rosas Guadalupe Roy-Ocotla Pedro Mosiño 《International journal of biometeorology》1989,33(3):173-179
Sixteen species of algae were collected from 73.8 m3 of air. Eleven were obtained in Minatitlán and eleven in México City. The data show that similar diversity occurred between the two localities, in spite of the difference in altitude. This suggests that cosmopolitan airborne microorganisms might have been released from different sources. Three major algal divisions (Chlorophyta, Cyanophyta and Chrysophyta) formed the airborne algal group. Also, a large concentration of 2220 algae m–3 was found near sea-level, while lower amounts were recorded at the high altitude of México City. The generaScenedesmus, Chlorella andChlorococcum dominated. Striking relationships were noted between the concentration of airborne green and blue-green algae, and meteorological conditions such as rain, vapour pressure, temperature and winds for different altitudes. In Minatitlán a linear relationship was established between concentration of algae and both vapour pressure (mbar) and temperature (° C), while in México City the wind (m s–1) was associated with variations in the algal count. 相似文献
14.
The Resplendent Quetzal (Pharomachrus mocinno) is an altitudinal migrant that nests in high elevation cloud forests and migrates toward lower areas during the summer rainy season. It has been suggested that its migratory movements are related to the abundance of ripe Lauraceae fruits. We studied the quetzal diet during two consecutive years, as well as changes in fruit abundance of the plant species on which the bird feeds at El Triunfo Biosphere Reserve, southeastern Mexico. The quetzal was observed feeding on 32 plant species; of these, 24 are new records in its diet. We chose 20 of these 32 species and studied their fruit phenology for two years in order to describe the relationship between fruit and quetzal abundance. Our results showed that quetzal abundance in the breeding area was correlated with the total number of fruiting species, whereas the correlation between quetzal abundance and the number of fruiting Lauraceae species was only marginal. Additionally, a correlation test showed that quetzal abundance was marginally correlated with total fruit availability (total no. of fruits per month); however, the correlation between quetzal abundance and the number of fruits in the Lauraceae was not significant. Our results suggest that the dynamics of food resources may be playing a major role in the quetzal's migratory behavior. Knowing the bird's diet may aid in characterizing the type of habitat adequate for its conservation. Our observations in this respect suggest that conservation efforts to preserve this bird species should concentrate on the protection of its habitat, including both breeding and nonbreeding (migration) locations. 相似文献
15.
María del Carmen González Teófilo Herrera Miguel Ulloa Richard T. Hanlin 《Mycoscience》1998,39(2):115-121
The abundance and diversity of species of microfungi was investigated on the beaches of Delfines, Km 24 Veracruz-Alvarado
Highway, and El Coco, located on the coasts of the Caribbean Sea, Gulf of Mexico, and the Pacific Ocean, respectively. On
each beach a sample composed of sand, subtidal wood or washed-up detritus with moist sand was collected. The samples were
analyzed by three different methods, resulting in a total of 1,160 occurrences that fluctuated between 340 and 441 occurrences/sample.
The number of species/sample fluctuated between 20 and 32. A total of 52 species was found, of which 12 were marine, and 40
nomarine, of terrestrial origin, and of these 15 were ascomycetes, 34 were hyphomycetes, 2 were blastomycetes and one was
a coelomycete. The abundance distribution showed few species with high or low values, with the greates proportion having intermediate
values. In order to compare species diversity among the samples frequency curves were utilized, based on the number of species
expected from samples taken at random; the results showed that the beach at El Coco was richest in species. 相似文献
16.
17.
R. Ben-Shahar 《植被学杂志》1991,2(3):345-350
The relationships of plant species associations and underlying environmental factors in a woodland savanna in South Africa were investigated. 40 plots were included with 25 tree and 17 grass species dominating the arboreal and ground cover. Correspondence Analysis described the relationships between soil moisture retention, soil nutrients and the abundance of trees and grasses. Dry matter indices represented the accumulated effects of rainfall, fire and grazing of the herbaceous layer. Variations in the abundance of plants corresponded to well-defined gradients of soil nutrients. The distribution of grass and tree species along the ordination axes indicated that soils with high water retention capacity and high nutrient contents provided a suitable substrate for many of the tree species sampled. However, grass species abundance was high in plots with porous soils and poor nutrient availability. 相似文献
18.
Kaiser Naguib 《Archives of microbiology》1959,34(1):12-15
Summary
Penicillium lilacinum was grown in a synthetic medium highly conducive to fat formation. Calcium pantothenate was added to fungal cultures when 5 days old at 3 different concentrations, namely, 0.1, 1.0, and 2.5 mg/100 ml medium. Sugar uptake was suppressed at the three experimental concentrations. Growth was first suppressed but was later accelerated. Fat formation was also suppressed at first but later the fat content of the vitamin-supplied cultures exceeded the controls and a fat content amounting to 56% could be obtained with 1.0 mg vitamin/100 ml medium, compared with about 46% for the controls. It is assumed that, during suppression of growth, alcohol and other intermediate products may have accumulated and were later utilised in fat synthesis. 相似文献
19.
Laccase activities of a soil fungus Penicillium simplicissimum in relation to lignin degradation 总被引:1,自引:0,他引:1
Guang Ming Zeng Hong Yan Yu Hong Li Huang Dan Lian Huang Yao Ning Chen Guo He Huang Jian Bing Li 《World journal of microbiology & biotechnology》2006,22(4):317-324
Summary The laccase activities of Penicillium simplicissimum H5 during solid-state fermentation with rice straw were studied. Degradation of lignocellulose was also followed. Results
showed that all supplemental carbon sources inhibited the laccase activity in different degrees, while suitable concentrations
of supplemental nitrogen sources remarkably enhanced the laccase activity. The enhancement of activity by the ordinary laccase
inducers 2, 2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) and xylidine was not observed in this study. Lignocellulose
degradation was improved when laccase activity was relatively low, suggesting a polymerizing function of laccase in lignin
degradation by P. simplicissimum. 相似文献
20.
Aparna Telang 《Journal of vector ecology》2011,36(1):75-85
It is currently unclear if the potential for West Nile virus transmission by mosquito vectors in the eastern United States is related to landscape or climate factors or both. We compared abundance of vector species between urban and suburban neighborhoods of Henrico County, VA, in relation to the following factors: temperature, precipitation, canopy cover, building footprint, and proximity to drainage infrastructure. Mosquitoes were collected throughout the 2005, 2006, and 2007 seasons and tested for West Nile virus (WNV) in pools of 10–50. Test results of mosquito pools were compared to average site abundance from 37 sites in Henrico County, VA; abundance was then examined in relation to ecological variables. Urban infrastructure was positively correlated with the abundance of Culex pipiens L./Cx. restuans, and our findings implicate combined sewer overflow systems as large contributors to Culex vector populations. No measure of urbanization examined in our study was correlated with Aedes albopictus abundance. Our study showed that certain landscape variables identified using Geographic Information Systems are valuable for predicting primary WNV vector abundance in Virginia, and that temperature along with low precipitation are strong predictors of population growth. Our results support other regional studies that found WNV proliferates under drought conditions. 相似文献