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Recent advances in agricultural biotechnology have highlighted the need for experimental evidence and sound scientific judgment to assess the benefits and risks to society. Nutrition scientists and other animal biologists need a balanced understanding of the issues to participate in this assessment. To date most modifications to crop plants have benefited producers. Crops have been engineered to decrease pesticide and herbicide usage, protect against stressors, enhance yields and extend shelf life. Beyond the environmental benefits of decreased pesticide and herbicide application, consumers stand to benefit by development of food crops with increased nutritional value, medicinal properties, enhanced taste and esthetic appeal. There remains concern that these benefits come with a cost to the environment or increased risk to the consumer. Most U.S. consumers are not aware of the extent that genetically modified foods have entered the marketplace. Consumer awareness of biotechnology seems to have increased over the last decade, yet most consumers remain confused over the science. Concern over the impact on the safety of the food supply remains low in the United States, but is substantially elevated in Europe. Before a genetically engineered crop is introduced into commerce it must pass regulatory scrutiny by as many as four different federal regulatory bodies to ensure a safe food supply and minimize the risk to the environment. Key areas for more research are evaluation of the nutritional benefits of new crops, further investigation of the environmental impact, and development of better techniques to identify and track genetically engineered products.

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The type 1 fimbriae of Actinomyces viscosus mediate the adherence of this organism to saliva-treated hydroxyapatite. The gene encoding a putative subunit of this fimbrial adhesin was cloned in Escherichia coli, and its product was examined. A. viscosus T14V chromosomal DNA was partially restricted with Sau3AI and cloned into E. coli JM109 by using the plasmid vector pUC13. Two Two immunologically distinct types of fimbriae on the gram-positive oral bacterium Actinomyces viscosus T14V have been identified (5). Those designated as type 1 are thought to be the principal adhesin for bacterial attachment to the tooth surface. This has been inferred from the ability of specific type 1 fimbria antibody to inhibit the attachment of A. viscosus to saliva-treated hydroxyapatite (8) and by the demonstration that mutants lacking type 1 fimbriae fail to attach (J. 0. Cisar, A. E. Vatter, W. B. Clark, S. H. Curl, S. Hurst-Calderone, and A. L. Sandberg, manuscript in preparation). In contrast to type 1, the type 2 fimbriae are the sites of a lactose-sensitive lectin activity involved in the interactions of Actinomyces spp. with certain streptococci (5) as well as with sialidase-treated mammalian cells (4,24).While functional activities have been associated with each type of A. viscosus fimbria, these adhesins have not been structurally characterized because isolated fimbriae are resistant to complete dissociation by various means (5). Therefore, cloning of A. viscosus genes in Escherichia coli has been initiated as an approach to the identification of the fimbrial subunits. In this respect, a type 2 fimbrial gene has recently been cloned into a cosmid vector by Donkersloot et al. (10) and the encoded protein (molecular weight, 59,000) has been identified by its reaction with anti-type 2 fimbria antibody. The cosmid library was also screened for recombinant clones that expressed the type 1 fimbrial antigen, but none were detected. The present study describes the cloning of the type 1 fimbrial subunit gene of A. viscosus T14V by using pUC as the expression vector. rotor. Fractions of 200 RI were collected, and 25 pI of each fraction was analyzed by agarose gel electrophoresis. Fractions containing DNA fragments of less than 10 kb were pooled, concentrated, and dissolved in 10 mM Tris-1 mM EDTA (pH 8.0) (TE) for ligation. Plasmid pUC13 (restricted with BamHI and dephosphorylated with bacterial alkaline phosphatase) was purchased from Boehringer Mannheim Biochemicals, Indianapolis, Ind. Sau3AI-restricted A. viscosus DNA and BamHIrestricted pUC13 were combined (3:1 molar ratio) and incubated at 14°C with 2 U of T4 DNA ligase (Bethesda Research Laboratories) in 20 pul of ligation buffer (18). The ligation mixture was used to transform E. coli JM109 competent cells prepared by the method of Hanahan (12). Portions of transformed cells were plated onto LB (18) agar plates containing ampicillin (50 pug/ml), 5-bromo-4-chloro-3-indolyl-p-Dgalactopyranoside (X-Gal; 0.005%), and isopropyl-p-Dthiogalactopyranoside (IPTG; 0.25 mM).Plasm...