Elizabethtown College

About: Elizabethtown College is a education organization based out in Elizabethtown, Pennsylvania, United States. It is known for research contribution in the topics: Social work & Spacetime. The organization has 329 authors who have published 636 publications receiving 10083 citations.

Model systems for environmental signaling.

Abstract: SYNOPSIS. Studies of environmental signaling in animals have focused primarily on organisms with relatively constrained responses, both temporally and phenotypically. In this regard, existing model animals (e.g., ‘‘worms and flies’’) are particularly extreme. Such animals have relatively little capacity to alter their morphology in response to environmental signals. Hence, they exhibit little phenotypic plasticity. On the other hand, basal metazoans exhibit relatively unconstrained responses to environmental signals and may thus provide more general insight, insofar as these constraints are likely traits derived during animal evolution. Such enhanced phenotypic plasticity may result from greater sensitivity to environmental signals, or greater abundance of suitable target cells, or both. Examination of what is known of the components of environmental signaling pathways in cnidarians reveals many similarities to well-studied model animals. In addition to these elements, however, macroscopic basal metazoans (e.g., sponges and cnidarians) typically exhibit a system-level capability for integrating environmental information. In cnidarians, the gastrovascular system acts in this fashion, generating local patterns of signaling ( e.g., pressure, shear, and reactive oxygen species) via its organism-wide functioning. Contractile regions of tissue containing concentrations of mitochondrion-rich, epitheliomuscular cells may be particularly important in this regard, serving in both a functional and a signaling context. While the evolution of animal circulatory systems is usually considered in terms of alleviating surface-to-volume constraints, such systems also have the advantage of enhancing the capacity of larger organisms to respond quickly and efficiently to environmental signals. More general features of animals that correlate with relatively unconstrained responses to environmental signals ( e.g., active stem cells at all stages of the life cycle) are also enumerated and discussed.

Detection of Alexandrium tamarensis by rapid PCR analysis

Abstract: Alexandrium tamarensis is a toxigenic dinoflagellate found in coastal waters worldwide. A critical factor in alleviating the health and economic threats posed by this species is the development of a rapid and reliable method for detection. This study stream-lined a labor- and resource-intensive protocol for the isolation of A. tamarensis ribosomal DNA (rDNA). Subcultures of A. tamarensis were established in water samples from several coastal Atlantic sites. A commercial DNA isolation kit protocol for cultured cells was used for isolation of the dinoflagellate DNA. Samples were amplified by PCR using primers specific for a 700-bp sequence of A. tamarensis rDNA. It was determined that this method facilitated the detection of 10(-4) ng/microL of A. tamarensis DNA. Furthermore, the kit enabled A. tamarensis to be isolated from the water sources with little signal degradation. This is a valuable technique for the rapid detection of A. tamarensis, even before cell numbers are large enough for morphological identification.

National Geographic magazine and the Eskimo stereotype: a photographic analysis, 1949–1990

Abstract: The origins of the ‘Eskimo stereotype’ found in the consciousness of today’s American students are explored, tracing its specific elements such as wearing traditional clothing and hunting sea mammals to Robert Peary’s Arctic exploration. Peary’s exploits were followed closely by an eager public reading about the journeys in popular media such as newspapers and magazines, who were especially captivated by his Polar Eskimo companions. National Geographic magazine is hypothesized to have contributed to the Eskimo stereotype by publishing photographs through four decades that continued the traditional themes and activities contained in Peary’s original dispatches. To test that hypothesis, the author evaluated National Geographic photographs from 1949 through 1990 for components of the North American Arctic stereotype begun by Peary, assessing 30% of the nearly 400 Eskimo photographs contained in the magazine during the study period for thematic elements and activities. The results suggested that Natio...

Listeria monocytogenes at the human-wildlife interface: black bears (Ursus americanus) as potential vehicles for Listeria.

Abstract: Listeria monocytogenes is the causative agent of the foodborne illness listeriosis, which can result in severe symptoms and death in susceptible humans and other animals. L. monocytogenes is ubiquitous in the environment and isolates from food and food processing, and clinical sources have been extensively characterized. However, limited information is available on L. monocytogenes from wildlife, especially from urban or suburban settings. As urban and suburban areas are expanding worldwide, humans are increasingly encroaching into wildlife habitats, enhancing the frequency of human-wildlife contacts and associated pathogen transfer events. We investigated the prevalence and characteristics of L. monocytogenes in 231 wild black bear capture events between 2014 and 2017 in urban and suburban sites in North Carolina, Georgia, Virginia and United States, with samples derived from 183 different bears. Of the 231 captures, 105 (45%) yielded L. monocytogenes either alone or together with other Listeria. Analysis of 501 samples, primarily faeces, rectal and nasal swabs for Listeria spp., yielded 777 isolates, of which 537 (70%) were L. monocytogenes. Most L. monocytogenes isolates exhibited serotypes commonly associated with human disease: serotype 1/2a or 3a (57%), followed by the serotype 4b complex (33%). Interestingly, approximately 50% of the serotype 4b isolates had the IVb-v1 profile, associated with emerging clones of L. monocytogenes. Thus, black bears may serve as novel vehicles for L. monocytogenes, including potentially emerging clones. Our results have significant public health implications as they suggest that the ursine host may preferentially select for L. monocytogenes of clinically relevant lineages over the diverse listerial populations in the environment. These findings also help to elucidate the ecology of L. monocytogenes and highlight the public health significance of the human-wildlife interface.

Life history, enamel formation, and linear enamel hypoplasia in the Ceboidea.

Abstract: Linear enamel hypoplasia (LEH), a developmental defect of enamel, increases in frequency from prosimian to monkey to lesser ape to great ape grades (Guatelli-Steinberg 2000 Am. J. Phys. Anthropol. 112:395-410, [2001] Evol. Anthropol. 10:138-151; Newell 1998 Ph.D. dissertation, Temple University). This taxonomic pattern in the distribution of LEH is closely related to maturation length across the primate order (Newell 1998 Ph.D. dissertation, Temple University, 2000 Am. J. Phys. Anthropol. [Suppl.] 30:236). Longer maturation periods are associated with higher LEH frequencies; they appear to provide greater opportunity for defects to form. The present study explores the relationship between maturation length and LEH frequency within the Ceboidea. Because of its prolonged period of growth, Cebus is predicted to manifest LEH at a higher frequency than the more rapidly maturing ceboid genera. To test this hypothesis, two separate researchers (E.A.N. and D.G.-S.) examined LEH in nonoverlapping museum series of ceboids. The results support the hypothesis: in 13 genera (n = 1,276), E.A.N. found that LEH frequencies ranged from 0% in Callicebus, Cebuella, and Saimiri to 20% in Cebus. D.G.-S. found similar frequencies among five genera (n = 107), from 0% in Saimiri to 32% in Cebus. Thus, the broad pattern of LEH distribution evident across major taxonomic groups of primates is repeated within the Ceboidea. We also examined a related hypothesis linking the spacing of perikymata, which is influenced by enamel extension rates (Shellis 1998 J. Hum. Evol. 35:387-400), to LEH. The most likely areas of tooth crowns to exhibit LEH in human teeth are those in which perikymata are most closely spaced (Hillson and Bond 1997 Am. J. Phys. Anthropol. 104:89-103). We hypothesized that the longer-maturing Cebus, with its elevated LEH frequency, will also exhibit more closely spaced perikymata than other ceboids. Analysis of a small microscopic subsample (n = 8) lends limited support to this second hypothesis.