Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (July 13, 2006) Includes bibliographical references.

Aflatoxins B₁, B₂, G₁ and G₂ and a crude preparation of freshly prepared aflatoxin produced by Aspergillus parasiticus NRRL 2999 were added to the fertilized oyster, Crassostrea gigas, eggs. The addition of 2, 3, 4 and 5 ug/ml of aflatoxin B₁, inhibited the first cell division of fertilized oyster eggs by 10, 30, 70 and 90 percent, respectively. First cell division did not appear to be inhibited by 5 ug/ml of either aflatoxins B₂,G₁ or G₂ A change in the fine structure of the fertilized oyster eggs was observed following the addition of 5 ug/ml of aflatoxin B₁. Visible changes or alterations in the aflatoxin treated zygotes were not readily detectible in the electron micrographs except for the segregation of the fibrillar and granular components of the nucleolus, an apparent decrease of the vesicles surrounding the cisternal rough endoplasmic reticulum, and the final inhibition of the mitotic division process before first cell division. The data is consistant with the observed cytotoxic effects suggesting an inhibition at the cell DNA replication, RNA transcription and protein translational levels in the aflatoxin B₁ treated oyster zygotes. / Land and Food Systems, Faculty of / Graduate

Thesis (Ph. D.)--Illinois State University, 1981. / Title from title page screen, viewed March 29, 2005. Dissertation Committee: A. Richardson (chair), H. Brockman, F. Schwalm, M. Nadakavukaren, A. Katz. Includes bibliographical references (leaves 138-153) and abstract. Also available in print.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

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M.Sc. (Biochemistry) / Please refer to full text to view abstract

Graduation date: 1969

Aflatoxins are toxic organic compounds produced by fungi in grains. Moderately contaminated grains that cannot be used as food are often directed to animal feed. Economically-feasible detoxification measures for contaminated feeds are needed. The objectives of this research were to identify effective bentonites as aflatoxin adsorbents and to evaluate the performance of the clays as aflatoxin amendments in feed for broiler chickens. Five bentonite samples from Gonzales, Texas, USA were collected and analyzed against the published selection criteria for aflatoxin adsorbents: aflatoxin adsorption capacity, pH, cation exchange capacity (CEC), organic carbon, particle size distribution, and mineralogical and structural compositions. Two bentonites were identified as potentially good aflatoxin adsorbents based on the analyses. These two bentonites were selected for an in vivo poultry experiment where chickens were fed with aflatoxin-contaminated corn (1400 ppb) to test the detoxification efficacy of the clays. Detailed mineralogy analyses were conducted on these two samples (4TX and 1TX) after size fractionation. Clay 4TX and 1TX contained 87 percent and 65 percent clay, respectively. Smectite was the dominant mineral phase in both clay fractions. Quartz and feldspars were also present in both samples. These minerals are unlikely to cause harmful effects on the chickens. The presence of pyrite and heavy metals in 1TX raised concerns about its use in animal feed. The clays were introduced into feed by mixing the dry bentonite powder with the feed for twelve minutes in a mechanical mixer. The body weight was increased by 21 percent with clay 4TX and 14 percent with clay 1TX in the aflatoxin diet. The concentration of total aflatoxins in liver was reduced by 36 percent with the addition of clays. Liver visual appearance was also improved from pale red to a more reddish color resembling the healthy red liver. All chickens fed clean feed had significantly higher body weights than those fed with highly contaminated feed, suggesting that the clays did not completely eliminate aflatoxin toxicity. The published aflatoxin binder selection criteria were useful for screening bentonites as aflatoxin amendments. The selected bentonites based on the criteria could effectively sequester aflatoxins in vivo. Yet direct mixing of bentonite as dry powder to highly contaminated poultry feed could not eliminate the toxicity of aflatoxins.