Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Paracoccidioides brasiliensis  (25)
  • Aflatoxin  (22)
  • 11
    ISSN: 1573-0832
    Keywords: Aflatoxin ; soya-bean root ; leucine ; mycotoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present work reports a portion of our continuing effort to determine the mechanism(s) whereby aflatoxins cause toxic responses in in vitro cultured plant tissues. Few investigations have dealt with the mode of action of aflatoxin B1 (AFB1) in excised plant tissues. Here is detailed AFB1 influence on growth, uptake and incorporation of 14C-leucine by excised, incubated soya-bean roots. Pure AFB1 was added to culture medium prior to autoclaving. One gram fresh weight portions of roots from three-day old soya-bean seedlings were excised and incubated for 4, 8, 12 and 24 hours. Growth was assayed by following changes in root dry weight. Aflatoxin B1 inhibited root dry weight at both 20 and 30 μg/ml. Uptake of 14C-leucine was checked by following its depletion from the medium. Reduced 14C-leucine uptake by roots exposed to 20 μg/ml AFB1 suggests that the toxin may alter the plasmalemma. A possible role for AFB1 in modification of membrane-associated amino acid transport mechanisms is discussed. Incorporation of 14C-leucine into trichloroacetic acid-precipitable cytoplasm was assayed. Inhibition of this incorporation at 20 μg/ml AFB1 was most apparent at 12 hours. Thus, AFB1 may also impair the ability of excised soya-bean roots to carry out protein synthesis.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 12
    ISSN: 1573-0832
    Keywords: Acridine orange ; Dye exclusion ; Erythrosin B ; Horse serum ; Janus green ; Methylene blue ; Paracoccidioides brasiliensis ; Paracoccidiodomycosis ; Plating efficiency ; South American blastomycosis ; Ultrasound ; Vital dyes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mild sonication was used to obtain single cell suspensions of Paracoccidioides brasiliensis. These cells were intact by microscopic criteria. Direct cell counts in a given inoculum and colony formation on various media were used to determine plating efficiency. Sonicated and nonsonicated cell suspensions were used to study plating efficiency and to estimate viability by means of vital dyes. Methylene blue, Erythrosin B, and Janus green were unreliable when used with P. brasiliensis, but vital dyes were accurate when tested with Candida albicans. Acridine orange gave more meaningful results of viability. Estimates of viability, however, changed significantly as a result of relatively minor alterations in the composition of the suspending medium. In initial experiments, the plating efficiency of P. brasiliensis was dismally low. It descended abruptly with increasing dilution of inoculum. Efficiency was much improved if horse serum was added to brain heart infusion plates or if glucose glycine yeast extract (GGY) plates were incubated at room temperature and mycelial colonies were counted. With the technique we report, current plating efficiency of sonicated suspensions is of the order of 25 %. Our results and procedures have an important bearing upon those studies concerned with in vitro killing of P. brasiliensis in suspensions or with isolating this fungus from clinical or environmental specimens.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 13
    ISSN: 1573-0832
    Keywords: Paracoccidioides brasiliensis ; paracoccidioidomycosis ; passage in vitro ; virulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Stability of virulence in P. brasiliensis isolates was studied with respect to the in vitro culture history and methods used for storage. Virulence in yeast-form P. brasiliensis isolates was tested in a chronic pulmonary murine model of paracoccidioidomycosis where progression of disease was quantitated in terms of colony forming units recoverable from lungs. Four isolates of P. brasiliensis, including recently isolated from patients or experimental animals, caused chronic progressive disease. Two isolates with a history of subculturing showed attenuation by causing resolving but chronic disease. An attenuated isolate became avirulent subsequent to 15 more years of subculturing. These findings suggest that virulence of P. brasiliensis can be attenuated or lost subsequent to cycles of subculturing over long periods. Our data suggest that the use of fresh P. brasiliensis isolates may be needed to provide reproducible virulence for experimental systems.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 14
    ISSN: 1573-0832
    Keywords: Aflatoxin ; Aspergillus flavus ; aflatoxin natural ; semisynthetic and synthetic media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have studied the aflatoxin producing capacity of 41 Aspergillus flavus strains isolated from the mycoflora present of natural media (wheat, rice and mixed feed) synthetic medium (Aflatoxin Producing Ability Medium) and semisynthetic media (Coconut Agar Medium and Glucose Yeast Extract Agar) were compared. Aflatoxins were analysed on days 4 and 8 post-inoculation under an incubation temperature of 28 °C. A total of 30 strains (75.7%) were producers on natural media as detected by Thin Layer Chromatography: 23 strains on wheat, 27 on rice and 12 on mixed feed. The results by qualitative flourescence tests on synthetic and semisynthetic media were: 3 strains positive on Coconut Agar Medium (CAM) 1 on Glucose Yeast Extract Agar (GY + Agar) and none on Aflatoxin Producing Ability Medium (APA).
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 15
    ISSN: 1573-0832
    Keywords: Estrous cycle ; female mouse ; Paracoccidioides brasiliensis ; paracoccidioidomycosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The relationship between paracoccidioidomycosis in ddY mouse and its estrous cycle was studied. Adult ddY mice of both sexes were used as experimental animals. Estrous cycle of female mice was examined before inoculation of Paracoccidioides brasiliensis yeast cells and mice were divided into 5 groups such as proestrus, estrus, metestrus-I, metestrus-II and diestrus. Each mouse was inoculated intravenously with 106 P. brasiliensis yeast cell units and sacrificed on day 28 after inoculation. Their internal organs were cultured, and in addition, their histopathologies were studied. As a result, there was no difference in the organ cultures among the male and the female mice of 5 groups. However, histopathologically, the female groups at estrus, metestrus-I and metestrus-II were affected more severely than the male group, and the susceptibility of the female mice to the fungus was closely related to their estrous cycles.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 16
    ISSN: 1573-0832
    Keywords: Aflatoxin ; Aspergillus flavus ; Central Japan ; Soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In Kanagawa Prefecture, located in central Japan, aflatoxin-producingAspergillus flavus was isolated in 4 (2.5%) of 160 field soil samples. In the 4 fields, whose soil contained aflatoxin-producingA. flavus, the annual average temperature of the sampling sites of the soil ranged from 13.8 to 15.1°C. Of all the isolated strains of aflatoxin-producingA. flavus, 4 strains, isolated from a single soil sample, produced large amounts of aflatoxin B1 and B2 when incubated in coconut agar, peanut agar, peanuts or trilaurin-added rice, although they did not produce aflatoxin when incubated in rice, yeast extract-sucrose broth or sucrose-low salts broth.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 17
    ISSN: 1573-0832
    Keywords: Aflatoxin ; Biodeterioration ; ‘Donkwa’ ; Fungi ; Relative humnidity ; Storage time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A total of 14 fungal species, mostly toxigenic, were isolated from 50 samples of ‘donkwa’ snack obtained from 16 producers. All of the isolates recorded substantial growth, though at varying rates, on the 2% snack agar provided. They also induced a reduction in the oil and an increase in free fatty acids of the substrate suggesting their participatory roles in deterioration. Most of the snack samples analysed contained initial amounts of aflatoxins above the ‘safe’ permissible level (30 ppb). The initial toxin levels increased substantially with storage time under 79.5, 89.5 and 100% ambient relative humidities but increased only slightly when samples were kept at 71% relative humidity. Almost constant toxin levels were recorded throughout the study period under 51% relative humidity. Accumulation of aflatoxin B1 in samples was most enhanced at 89.5% relative humidity. Comparatively, greater amounts of aflatoxin B1 accumulated under all conditions than the amounts recorded for aflatoxin G1.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 18
    ISSN: 1573-0832
    Keywords: Aflatoxin ; Aspergillus ; Versicolorin B ; Versiconal hemiacetal acetate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The sequence of steps versiconal hemiacetal acetate (VHA) to versiconal (VL) catalyzed by an esterase and VL to versicolorin B (VB) catalyzed by VL cyclase has been previously demonstrated in cell-free systems fromAspergillus parasiticus. VHA esterase and VL cyclase activities were estimated by determining the amounts of VL and VB after incubation of VHA in cell-free extracts from mycelia that were either synthesizing or not synthesizing aflatoxins. VHA esterase activity but not VL cyclase activity was present in extracts from cells grown in a nonaflatoxin-producing medium. VHA esterase activity was present in extracts from mycelia grown in aflatoxin-producing medium harvested after one to six days of incubation. VL cyclase activity was absent at one day, low at two days, maximal at three to five days, and lower at six days. VL cyclase activity appears in the later part of the growth period which is also the period of aflatoxin biosynthesis. This supports a role for VL cyclase in the aflatoxin biosynthetic pathway.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 19
    ISSN: 1573-0832
    Keywords: Aflatoxin ; Aspergillus flavus ; Fumonisins ; Fusarium ; Maize ; Mycotoxins ; Stenocarpella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Sixty nine samples of maize were collected from pre-harvest standing crops and on-farm storage facilities from 52 smallholder farms located within 4 regions of Honduras during October 1992 and November 1993. Samples were visually assessed for insect damage and fungal spoilage, and the mycoflora quantified on artificial media. The major components of the ear rot complex were:Fusarium moniliforme, F. moniliforme var.subglutinans, Penicillium species,Stenocarpella maydis, S. macrospora andAcremonium spp. Representative samples were also assayed for mycotoxin content. Fumonisin B1 was detected in all 24 samples tested at levels of between 68–6,555 (µg/kg), and aflatoxin was detected in 2 samples heavily contaminated withAspergillus flavus. Moniliformin and tenuazonic acid were not detected in the samples tested. The implications of these findings for human and livestock health risk are discussed, together with possible strategies for controlling these pathogens.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 20
    ISSN: 1573-0832
    Keywords: armadillo ; GP43kDa gene ; Paracoccidioides brasiliensis ; pathogenicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We studied three different isolates of Paracoccidioides brasiliensis obtained from the mesenteric lymph node (D3LY1), the spleen (D3S1) and the liver (D3LIV1) of the same armadillo ( Dasypus novemcinctus ).Pulmonal inflammatory area was evaluated by intravenous inoculation of 106 yeast cells of each isolates in young, male, ddY mice. Moreover, the partial sequence of GP43kDa gene of P. brasiliensis was analyzed. The lung inflammatory area was greater in animals inoculated with isolate D3S1. The partial sequence of GP43kDa gene indicated that isolate D3S1 is different from isolates D3LY1 and D3LIV1. This study suggested that the same armadillo might be susceptible to multiple P. brasiliensis isolates simultaneously.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...