scholarly journals Waste Corn as a Point Source of Inoculum for Aspergillus flavus in the Corn Agroecosystem

Plant Disease ◽  
1997 ◽  
Vol 81 (6) ◽  
pp. 576-581 ◽  
Author(s):  
O. M. Olanya ◽  
G. M. Hoyos ◽  
L. H. Tiffany ◽  
D. C. McGee
Keyword(s):  
Aspergillus Flavus ◽  
Sampling Time ◽  
Point Sources ◽  
Plant Infection ◽  
Carpophilus Lugubris ◽  
Airborne Conidia ◽  
Nitidulid Beetles ◽  
Corn Kernels ◽  
Cedar Rapids ◽  
Sampling Times

Sporulation of Aspergillus flavus was detected on kernels in deposits of waste corn close to corn storage cribs and bins at 18 locations throughout Iowa in 1991 and 1992. A. flavus was detected in spore traps located 3 m from the deposits and was isolated from nitidulid beetles within the deposits or in insect traps within 3 m of the deposits. A. flavus also was isolated from asymptomatic corn kernels in the deposits and from soil beneath the deposits. Linear dispersal gradients of airborne conidia of A. flavus, sampled at distances of 2, 6, 10, and 14 m from waste corn deposits into adjacent cornfields, were detected at three sampling times between 28 July and 1 September 1992 at Cedar Rapids and Williamsburg, Iowa. Linear dispersal gradients from the deposits also were detected for A. flavus-infested nitidulid beetle species Carpophilus lugubris and Glischrochilus quadrisignatus. The incidence of A. flavus infection on corn leaves, silks, and kernels in the fields adjacent to the deposits were correlated to numbers of airborne conidia at each sampling time at both locations. In a field experiment in Ames in which waste corn was placed in the center of individual corn plots, linear dispersal of conidia of A. flavus and plant infection gradients similar to those found from natural deposits were detected at distances of 1.7 to 8.5 m from the deposits at four sampling times from 6 August to 26 September 1992. Few airborne conidia of A. flavus were detected, and no infection of leaves, silks, and kernels by A. flavus occurred in the corresponding noninfested control plots. This study showed that deposits of waste corn infested with A. flavus found in the vicinity of corn storage cribs and bins are point sources of inoculum for A. flavus in the corn agroecosystem.

scholarly journals The 28 + 28 day design is an effective sampling time for analyzing mutant frequencies in rapidly proliferating tissues of MutaMouse animals

2021 ◽  
Vol 95 (3) ◽  
pp. 1103-1116
Author(s):  
Francesco Marchetti ◽  
Gu Zhou ◽  
Danielle LeBlanc ◽  
Paul A. White ◽  
Andrew Williams ◽  
...  
Keyword(s):  
Germ Cells ◽  
False Negative ◽  
Sampling Time ◽  
Male Germ Cells ◽  
Negative Results ◽  
False Negative Results ◽  
Detection Of Mutations ◽  
The Impact ◽  
Sampling Times

AbstractThe Organisation for Economic Co-Operation and Development Test Guideline 488 (TG 488) uses transgenic rodent models to generate in vivo mutagenesis data for regulatory submission. The recommended design in TG 488, 28 consecutive daily exposures with tissue sampling three days later (28 + 3d), is optimized for rapidly proliferating tissues such as bone marrow (BM). A sampling time of 28 days (28 + 28d) is considered more appropriate for slowly proliferating tissues (e.g., liver) and male germ cells. We evaluated the impact of the sampling time on mutant frequencies (MF) in the BM of MutaMouse males exposed for 28 days to benzo[a]pyrene (BaP), procarbazine (PRC), isopropyl methanesulfonate (iPMS), or triethylenemelamine (TEM) in dose–response studies. BM samples were collected + 3d, + 28d, + 42d or + 70d post exposure and MF quantified using the lacZ assay. All chemicals significantly increased MF with maximum fold increases at 28 + 3d of 162.9, 6.6, 4.7 and 2.8 for BaP, PRC, iPMS and TEM, respectively. MF were relatively stable over the time period investigated, although they were significantly increased only at 28 + 3d and 28 + 28d for TEM. Benchmark dose (BMD) modelling generated overlapping BMD confidence intervals among the four sampling times for each chemical. These results demonstrate that the sampling time does not affect the detection of mutations for strong mutagens. However, for mutagens that produce small increases in MF, sampling times greater than 28 days may produce false-negative results. Thus, the 28 + 28d protocol represents a unifying protocol for simultaneously assessing mutations in rapidly and slowly proliferating somatic tissues and male germ cells.

scholarly journals Impact of Exposure to Low Temperature Degrees in Field Conditions on Leaf Pigments and Chlorophyll Fluorescence in Leaves of Mango Trees

2020 ◽  
Vol 10 ◽  
pp. 30-45
Author(s):  
Ali A.S. Sayed ◽  
Farouk M. Gadallah ◽  
Mohamed A. Seif El-Yazal ◽  
Gamal A. Abdel-Samad
Keyword(s):  
Chlorophyll Fluorescence ◽  
Low Temperature ◽  
Chlorophyll Concentration ◽  
Ambient Air ◽  
Sampling Time ◽  
Chlorophyll B ◽  
Physiological And Biochemical ◽  
Sampling Times ◽  
Fayoum Governorate

This experiment was conducted to found the connection between low temperature stress in vivo conditions (ambient-air temperature) and the changes in some physiological and biochemical events (leaf pigments and chlorophyll fluorescence) of mango trees in response to exposure to natural low temperature (cold). To verify this objective, 12 popular commonly mango cultivars (25 years old) which grown in private orchard in Fayoum Governorate, Egypt were selected for this study which carried out during the period from November to March of years; 2012 and 2013. The selected cultivars were: Alphonso, Baladi, Bullock's Heart, Helmand, Hindi Besennara, Mabrouka, Mestekawy, Nabeeh, Oweisi, Spates, Taimour and Zebda. Based on the obtained results, it can be stated that, chlorophyll (a) concentration in the leaves was significantly differed among the cultivars throughout the whole sampling times, in this respect, Helmand one gave the highest one while, and the highest one by sampling times was November one. The concentration of chlorophyll (b) was significant as effected by the effect of cultivars and sampling time recorded the highest value by the cultivar of Spates and December sample, respectively. Total chlorophyll concentration in the leaves reached its peak by the cultivar of Nabeeh and sampling time of December as compared to others. The both of Ewais cultivar and the sample of March showed the highest values of carotenoids concentration in the leaves. The levels of anthocyanin in leaves were significantly differed as affected by the cultivars and sampling times, indicating that the cultivar of Helmand and November sample recorded the highest values of anthocyanin in leaves. The greatest reductions in Fv/Fmratio were recorded at month of November and indicated that the reductions were in the order of Alphonso˃ Mabrouka˃Taimour˃ others. The effect of sampling time, cultivars and their interaction on Fv/Fm were significant, but small between some values of Fv/Fm.

Comparison of Two Sampling Methods for Escherichia coli O157:H7 Detection in Feedlot Cattle

2005 ◽  
Vol 68 (8) ◽  
pp. 1724-1728 ◽  
Author(s):  
M. L. KHAITSA ◽  
M. L. BAUER ◽  
P. S. GIBBS ◽  
G. P. LARDY ◽  
D. DOETKOTT ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Sampling Methods ◽  
Feedlot Cattle ◽  
Sampling Time ◽  
Escherichia Coli O157 ◽  
Confounding Factors ◽  
Rank Tests ◽  
E Coli ◽  
Signed Rank ◽  
Sampling Times

Two sampling methods (rectoanal swabs and rectal fecal grabs) were compared for their recovery of Escherichia coli O157:H7 from feedlot cattle. Samples were collected from 144 steers four times during the finishing period by swabbing the rectoanal mucosa with cotton swabs and immediately obtaining feces from the rectum of each individual steer. The number of steers with detectable E. coli O157:H7 increased from 2 of 144 (1.4%) cattle on arrival at the feedlot to 10 of 144 (6.9%) after 1 month, 76 of 143 (52.8%) after 7 months, and 30 of 143 (20.8%) at the last sampling time before slaughter. Wilcoxon signed-rank tests indicated that the two sampling methods gave different results for sampling times 3 and 4 (P < 0.05) but not for sampling time 2 (P = 0.16). Agreement between the two sampling methods was poor (kappa < 0.2) for three of the four sampling times and moderate (kappa = 0.6) for one sampling time, an indication that in this study rectoanal swabs usually were less sensitive than rectal fecal grabs for detection of E. coli O157:H7 in cattle. Overall, the herd of origin was not significantly associated with E. coli O157:H7 results, but the weight of the steers was. Further investigation is needed to determine the effects of potential confounding factors (e.g., size and type of swab, consistency of feces, site sampled, and swabbing technique) that might influence the sensitivity of swabs in recovering E. coli O157:H7 from the rectoanal mucosa of cattle.

316 Does sampling time matter? Relationships of circulating metabolites at various neonatal sampling times in beef calves

2016 ◽  
Vol 94 (suppl_2) ◽  
pp. 148-149
Author(s):  
J. M. Larson ◽  
B. L. Vander Ley ◽  
S. M. Bolen ◽  
N. B. Duncan ◽  
A. M. Meyer
Keyword(s):  
Sampling Time ◽  
Beef Calves ◽  
Sampling Times

scholarly journals Resistance to Aspergillus flavus in Corn Kernels Is Associated with a 14-kDa Protein

1998 ◽  
Vol 88 (4) ◽  
pp. 276-281 ◽  
Author(s):  
Z.-Y. Chen ◽  
R. L. Brown ◽  
A. R. Lax ◽  
B. Z. Guo ◽  
T. E. Cleveland ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Trypsin Inhibitor ◽  
Aflatoxin Contamination ◽  
Inhibitor Protein ◽  
Trypsin Activity ◽  
Terminal Sequence ◽  
High Concentration ◽  
Resistant Varieties ◽  
Corn Kernels

Corn genotypes resistant or susceptible to Aspergillus flavus were extracted for protein analysis using a pH 2.8 buffer. The profile of protein extracts revealed that a 14-kDa protein is present in relatively high concentration in kernels of seven resistant corn genotypes, but is absent or present only in low concentration in kernels of six susceptible ones. The N-terminal sequence of this 14-kDa protein showed 100% homology to a corn trypsin inhibitor. The 14-kDa protein purified from resistant varieties also demonstrated in vitro inhibition of both trypsin activity and the growth of A. flavus. This is the first demonstration of antifungal activity of a corn 14-kDa trypsin inhibitor protein. The expression of this protein among tested genotypes may be related to their difference in resistance to A. flavus infection and subsequent aflatoxin contamination.

scholarly journals Lack of Host Specialization inAspergillus flavus

2000 ◽  
Vol 66 (1) ◽  
pp. 320-324 ◽  
Author(s):  
Raymond J. St. Leger ◽  
Steven E. Screen ◽  
Bijan Shams-Pirzadeh
Keyword(s):  
Aspergillus Fumigatus ◽  
Aspergillus Nidulans ◽  
Aspergillus Flavus ◽  
Galleria Mellonella ◽  
Host Specialization ◽  
Plant Tissues ◽  
Animal Hosts ◽  
Insect Hemocytes ◽  
Corn Kernels ◽  
Bean Leaves

ABSTRACT Aspergillus spp. cause disease in a broad range of organisms, but it is unknown if strains are specialized for particular hosts. We evaluated isolates of Aspergillus flavus,Aspergillus fumigatus, and Aspergillus nidulansfor their ability to infect bean leaves, corn kernels, and insects (Galleria mellonella). Strains of A. flavus did not affect nonwounded bean leaves, corn kernels, or insects at 22°C, but they killed insects following hemocoelic challenge and caused symptoms ranging from moderate to severe in corn kernels and bean leaves injured during inoculation. The pectinase P2c, implicated in aggressive colonization of cotton bolls, is produced by most A. flavus isolates, but its absence did not prevent colonization of bean leaves. Proteases have been implicated in colonization of animal hosts. All A. flavus strains produced very similar patterns of protease isozymes when cultured on horse lung polymers. Quantitative differences in protease levels did not correlate with the ability to colonize insects. In contrast to A. flavus, strains ofA. nidulans and A. fumigatus could not invade living insect or plant tissues or resist digestion by insect hemocytes. Our results indicate that A. flavus has parasitic attributes that are lacking in A. fumigatus and A. nidulans but that individual strains of A. flavus are not specialized to particular hosts.

scholarly journals Antifungal activity of Cymbopogon citratus essential oil against Aspergillus flavus

2019 ◽  
Vol 41 ◽  
pp. 20
Author(s):  
Ana Paula Martinazzo ◽  
Filipe Da Silva de Oliveira ◽  
Carlos Eduardo de Souza Teodoro
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Essential Oil ◽  
Aspergillus Flavus ◽  
Inhibitory Concentration ◽  
Fungal Growth ◽  
In Vitro Tests ◽  
Cymbopogon Citratus ◽  
Object Of Study ◽  
Corn Kernels

The search for alternatives for the control of microbiological contamination in foods has been the object of study in different scientific areas. This study aimed to evaluate the efficiency of lemon grass (Cymbopogon citratus) essential oil in controlling the growth of the fungus Aspergillus flavus in three types of analysis: first, by in vitro tests, in essential oil doses between 0.2 and 1.0 μL/ml; second, by serial microdilution to determine the minimum inhibitory concentration, in doses between 0.1 and 1.2 μL/mL; and third, by inhibition of fungal growth in corn kernels contaminated using essential oil doses of 0.4, 0.7, and 1.0 μL/mL, in the incubation times of 14, 28, and 42 days. The in vitro tests showed that the essential oil controlled the fungus from doses of 0.6 μL/mL, but the dose of 1.0 μL/mL controlled 100% growth until day eight of incubation, from which it decreased. The minimum inhibitory concentration for the microdilution analysis was 0.9 μL/mL. The evaluation of the corn kernels for all doses of essential oil and times tested showed 100% inhibition of the fungal growth.

Sign in / Sign up

Export Citation Format

Share Document