Clostridium botulinum is a taxonomic designation for many diverse anaerobic spore-forming rod-shaped bacteria that have the common property of producing botulinum neurotoxins (BoNTs). The BoNTs are exoneurotoxins that can cause severe paralysis and death in humans and other animal species. A collection of 174 C. botulinum strains was examined by amplified fragment length polymorphism (AFLP) analysis and by sequencing of the 16S rRNA gene and BoNT genes to examine the genetic diversity within this species. This collection contained representatives of each of the seven different serotypes of botulinum neurotoxins (BoNT/A to BoNT/G). Analysis of the16S rRNA gene sequences confirmed previous identifications of at least four distinct genomic backgrounds (groups I to IV), each of which has independently acquired one or more BoNT genes through horizontal gene transfer. AFLP analysis provided higher resolution and could be used to further subdivide the four groups into subgroups. Sequencing of the BoNT genes from multiple strains of serotypes A, B, and E confirmed significant sequence variation within each serotype. Four distinct lineages within each of the BoNT A and B serotypes and five distinct lineages of serotype E strains were identified. The nucleotide sequences of the seven toxin genes of the serotypes were compared and showed various degrees of interrelatedness and recombination, as was previously noted for the nontoxic nonhemagglutinin gene, which is linked to the BoNT gene. These analyses contribute to the understanding of the evolution and phylogeny within this species and assist in the development of improved diagnostics and therapeutics for the treatment of botulism.Clostridium botulinum is a taxonomic collection of several distinct species of anaerobic gram-positive spore-forming bacteria that produce the most poisonous substance known, botulinum neurotoxin (BoNT) (1,8). These organisms, along with related neurotoxin-producing species that, for a variety of reasons, were not included under the C. botulinum taxon, pose global health problems that affect both infant and adult humans and can also affect wildlife, waterfowl, and domestic animals. They cause intoxication through ingestion of the neurotoxin in contaminated foods. Toxicoinfections can also occur after contact with bacteria or bacterial spores (6, 17). These pathogens are ubiquitous and can be found in soils and sedi-

Alcohol use is prevalent among college students and may contribute to elevated rates of sexual risk taking. Using event-level data, the hypothesis that partner type would moderate the effect of alcohol consumption on condom use was tested. Sexually active college students (N = 330; 67% female) reported on characteristics of their most recent sexual encounter, including partner type, alcohol use, and condom use, along with measures of sex-related alcohol expectancies, sensation seeking, and typical alcohol use. Unprotected vaginal sex (UVS) was reported by 39% of the sample and 32% reported alcohol use prior to sex. For the complete sample, UVS was just as likely for non-drinking events as for events involving alcohol use. However, for sexual encounters involving a non-steady partner, alcohol consumption was associated with an increase in UVS, whereas rates of UVS did not vary by drinking status for encounters involving a steady partner. These effects remained in analyses that controlled for sex-related alcohol expectancies, sensation seeking, and typical alcohol use. Findings confirm that the effects of alcohol vary according to the context in which it is used. Keywords alcohol; partner type; risky sexual behavior; condom use; HIV Alcohol Use, Partner Type, and Risky Sexual Behavior Among College Students: Findings from an Event-Level StudyAlcohol use is highly prevalent among college students and may contribute to elevated rates of sexual risk taking (Cerwonka, Isbell, & Hansen, 2000;Hingson, Heeren, Zakocs, Kopstein, & Wechsler, 2002;Perkins, 2002;Wechsler, Lee, Kuo, & Lee, 2000). Indeed, an estimated 42% of college aged students engage in binge drinking (Wechsler, Lee, Kuo, & Lee, 2000), and as many as 400,000 college students have unprotected sex after drinking in a given year (Hingson, Heeren, Zakocs, Kopstein, & Wechsler, 2002). However, empirical research exploring the causal linkage of alcohol use to high risk sexual behavior has yielded mixed findings among college students (Anderson & Mathieu, 1998;Cooper, 2002) and other at-risk populations (Weinhardt & Carey, 2000). Global association studies that focus on overall Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. patterns of alcohol use and high-risk sexual practices suggest a positive association between drinking and sexual risk behavior (for a review, see Dingle & Oei, 1997). In contrast, eventlevel studies that link alcohol use to sexual activity for specific encounters often show no difference in condom use for drinking versus non-drinking encounters (Desiderato & Crawford, 1995;Senf & Price, 1994;Te...

These data suggest that the presence of an individual who provides passive or active support reduces experimental pain.