Papers by Linda Whitehand
Journal of Food Protection, 2002
Recent foodborne outbreaks have linked infection by enterohemorrhagic Escherichia coli (EHEC) ser... more Recent foodborne outbreaks have linked infection by enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 to the consumption of contaminated lettuce. Contamination via food handler error and on-the-farm contamination are thought to be responsible for several outbreaks. Though recent studies have examined the application of EHEC to store-bought lettuce, little is known about the attachment of EHEC to growing plants. We investigated the association of lettuce seedlings with EHEC O157:H7 strains implicated in lettuce or fruit outbreaks using hydroponic and soil model systems. EHEC strains that express the green fluorescent protein were observed by stereomicroscopy and confocal laser scanning microscopy to determine adherence patterns on growing lettuce seedlings. Bacteria adhered preferentially to plant roots in both model systems and to seed coats in the hydroponic system. Two of five nonpathogenic E. coli strains showed decreased adherence to seedling roots in the hydroponic sys...
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Journal of Economic Entomology, 1994
A 2-yr program of sterile Mediterranean fruit fly, Ceratitis capitata (Wiedemann), releases (yr 1... more A 2-yr program of sterile Mediterranean fruit fly, Ceratitis capitata (Wiedemann), releases (yr 1: 535 million; yr 2: 941 million flies) was conducted on Kauai Island, HI., in commercial coffee (Coffea arabica L.) fields. Fruit collections were used to estimate relative abundances of (1) C. capitata , the target species; (2) oriental fruit fly, Bactrocera dorsalis (Hendel), a potential competing fruit fly species; and (3) a beneficial wasp, Biosteres arisanus (Sonan), that attacks both fruit flies. During season 2, C. capitata abundance in the treatment area was suppressed by as much as 56% compared with the control area. In contrast, the number of B. dorsalis in treated coffee fields was within 6% of that in the control field for both years of the study, indicating that its abundance was not affected by C. capitata sterile releases. Numbers of B. dorsalis were not correlated with those of C. capitata, suggesting that these tephritids were not competitors in that habitat at that time. C. capitata and B. arisanus abundances were correlated positively in two of the four situations studied. Mean numbers of B. arisanus per 100 fruits in treated fields were 5.3 and 3.2 during seasons 1 and 2, respectively. Data suggest that high numbers of B. arisanus remain in a habitat inundated with sterile flies and that sterile C. capitata releases are compatible with B. arisanus parasitism for fruit fly control.
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Journal of Cereal Science, 2016
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Journal of Economic Entomology, 1995
... ROGER I. VARGAS,LINDA WHITEHAND,l WILLIAM A. WALSH, JOHN P. SPENCER,2 AND CHIOU-LING HSU ... ... more ... ROGER I. VARGAS,LINDA WHITEHAND,l WILLIAM A. WALSH, JOHN P. SPENCER,2 AND CHIOU-LING HSU ... 1980) over large, flat areas in California, whereas in Mexico and Gua-temala airplanes are used to release C. capitata in flat coastal areas, but helicopters are ...
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Journal of Economic Entomology, 2000
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Journal of Aquatic Plant Management
Giant reed (Arundo donax L.) occurs throughout the U.S. from California to Maryland. It is consid... more Giant reed (Arundo donax L.) occurs throughout the U.S. from California to Maryland. It is considered an invasive plant in some parts of this range but not others. To test the hypothesis that plants from different regions have similar growth characteristics, we grew plants from stem cuttings collected at two sites in Florida, one site in Texas, and two sites in California in a common garden experiment in Davis, California. Plants were grown outdoors in topsoil or a 90:10 sand:topsoil mix, in large plastic containers. All plants survived winter conditions in Davis, California, during 2004, when the minimum air temperature was -3.3 C. Stem width, number of stems per plant, number of leaves per stem, total leaf area per plant, and RGR(NSTEMS) did not differ among the provenances studied. Variegated plants had somewhat greater stem angles, indicating that the stems were more prostrate early in the growing season. Differences in stem height, number of internodes per stem, and mean intern...
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Food Science and Technology, 2003
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Proteome Science, 2011
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Mutagenesis, 1989
The use of a fluorescent stain containing Hoechst 33258 and pyronin Y in the fetal mouse transpla... more The use of a fluorescent stain containing Hoechst 33258 and pyronin Y in the fetal mouse transplacental micronucleus assay allows classification of erythrocytes into three subpopulations on the basis of RNA staining, and permits micronuclei to be scored in all three subpopulations. The youngest erythrocytes stain uniformly positive for RNA (UEs). In older erythrocytes RNA aggregates to give the cells a stippled appearance (SEs) and ultimately disappears, leaving cells which do not stain positively for RNA. Frequencies of micronucleated UEs and SEs were determined at 30 and 48 h following a single dose of methyl methanesulfonate, benzo[a]pyrene, lasiocarpine, monocrotaline or heliotrine. With each agent and dose tested, the frequency of micronuclei increased first in the younger UEs and later in SEs. The use of the Hoechst/pyronin staining procedure, which permits DNA to be distinguished from RNA, minimizes the potential for mis-scoring RNA artefacts as micronuclei and also increases the efficiency of the assay by permitting two age populations of erythrocytes to be scored in each sample.
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LWT - Food Science and Technology, 1994
ABSTRACT
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Seed microstructure provides complementary information to physico-chemical determinations. Scanni... more Seed microstructure provides complementary information to physico-chemical determinations. Scanning electron micrographs of cross sections of black bean extrudates illustrated the increase in volume expansion, with an increase of sodium bicarbonate (NaHCO 3) in the extrudate. This increase in volume expansion is attributed to the increase in air cell size and corresponding decrease in air cell wall thickness with additional concentrations of NaHCO 3. The measured increase in diameter and expansion ratio of extru-dates with NaHCO 3 addition may be explained by the increase in number of air cells within the extrudate and the increase in pores in the gelatinized starch matrix of air cell walls. Extrusion conditions, which involved the use of heat and moisture, provided the necessary conditions for the release of CO 2 from NaHCO 3 during processing. Expansion ratio increases between the control extrudate, and extrudate with 0.5% NaHCO 3 addition were twofold at the node and 1.8-fold at the area between the nodes. Statistical analysis of color data exhibited no significant change in L*, hue or chroma across concentrations of NaHCO 3 for nonextruded flours. A simple linear regression adequately described changes in L* and hue for extruded flours. However, a curvilinear relationship was needed to explain changes in chroma versus NaHCO 3 for extruded flours, making changes in chroma measurements less easy to interpret. The color data in this study serve as primary information for future establishment of cutoff values of color for the development of an acceptable legume snack.
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Journal of Cereal Science, 2009
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Journal of Agricultural and Food Chemistry, 2008
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Journal of Agricultural and Food Chemistry, 2004
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Journal of Agricultural and Food Chemistry, 2004
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Cereal Chemistry, 2006
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Applied and Environmental Microbiology, 2002
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Aquatic Botany, 2010
We determined leaf and stem strength for Arundo donax from plants grown in different geographic a... more We determined leaf and stem strength for Arundo donax from plants grown in different geographic areas and at different times within their growing cycle. Mean leaf strength for plants collected within California was 1.72 Newtons (N) and ranged from 0.36 to 6.32N, based on 1170 individual determinations. For leaves collected from 30 plants within four states between July 11 and
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Journal of Economic Entomology, 2005
The effects of methyl bromide (MB) concentration (16, 32,48, or 64 g/m3), fumigation temperature ... more The effects of methyl bromide (MB) concentration (16, 32,48, or 64 g/m3), fumigation temperature (15, 20, 25, or 30 degrees C), and fumigation time interactions on the survival of Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), eggs and first and third instars were recorded. Increasing the fumigation temperature from 15 to 20 degrees C or from 20 to 25 degrees C resulted in a significant reduction in fumigation time required for equivalent egg and larval mortalities at all studied MB concentrations; no further reductions in fumigation time resulted from increasing the temperature from 25 to 30 degrees C. Conversely, increasing temperature and time allowed for a reduction in MB concentration to obtain equivalent mortality. Thus, the optimum fumigation temperature for Mediterranean and oriental fruit fly eggs and larvae was 25 degrees C. Reducing MB concentrations required for phytosanitary fumigations would save time and expense, and reduce the amount of MB released into the atmosphere during aeration. Mediterranean fruit fly was as or more tolerant to MB than oriental fruit fly in MB tolerance for eggs and first instars. The egg stage was generally more tolerant to MB regardless of concentration. However, Mediterranean fruit fly eggs showed similar tolerance to first instars at 25 degrees C for the three highest concentrations and to third instars at 25 and 30 degrees C for the highest concentration, with no significant difference between them. Therefore, eggs alone can be used to obtain MB fumigation efficacy and quarantine security data at fumigation temperatures between 15 and 30 degrees C for Mediterranean and oriental fruit fly.
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Lake and Reservoir Management, 1993
Field experiments may be useful for researchers and managers concerned with aquatic plants. Since... more Field experiments may be useful for researchers and managers concerned with aquatic plants. Since experimental design and statistical analysis are closely related, this paper discusses statistical and practical considerations for conducting and evaluating field experiments with aquatic plants. Special emphasis is given to the analysis of variance, assumptions required for its use, and concepts related to it (e.g., statistical power,
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Papers by Linda Whitehand