Successful implementation of genetic Education for Native Americans workshops at national conferences

Genetic Education for Native Americans (GENA) was a National Human Genome Research Institute (NHGRI)/Ethical, Legal, and Social Implications (ELSI)-funded educational intervention designed to provide a unique genetics education program for Native American college and university students. A curriculum was developed and implemented in workshops in geographically diverse settings throughout the United States, primarily in conjunction with regional and national scientific conferences that include substantial numbers of Native American attendees. The original curriculum includes 24 objectives and has been offered in two formats, as a 16-hr "comprehensive" program and in briefer workshops (referred to as "customized" hereafter) that are designed to include objectives for selected audiences. Both formats teach sufficient genetics to allow discussion and understanding of the ELSI and cultural issues related to genetics science. This article describes the evaluation findings from our implementation of both formats of the GENA curriculum.     

Tooth development and replacement in the Atlantic Cutlassfish,Trichiurus lepturus,with comparisons to other Scombroidei

Atlantic Cutlassfish, Trichiurus lepturus, have large, barbed, premaxillary and dentary fangs, and sharp dagger-shaped teeth in their oral jaws. Functional teeth firmly ankylose to the dentigerous bones. We used dry skeletons, histology, SEM, and micro-CT scanning to study 92 specimens of T. lepturus from the western North Atlantic to describe its dentition and tooth replacement. We identified three modes of intraosseous tooth replacement in T. lepturus depending on the location of the tooth in the jaw. Mode 1 relates to replacement of premaxillary fangs, in which new tooth germs enter the lingual surface of the premaxilla, develop horizontally, and rotate into position. We suggest that growth of large fangs in the premaxilla is accommodated by this horizontal development. Mode 2 occurs for dentary fangs: new tooth germs enter the labial surface of the dentary, develop vertically, and erupt into position. Mode 3 describes replacement of lateral teeth, in which new tooth germs enter a trench along the crest of the dentigerous bone, develop vertically, and erupt into position. Such distinct modes of tooth replacement in a teleostean species are unknown. We compared modes of replacement in T. lepturus to 20 species of scombroids to explore the phylogenetic distribution of these three replacement modes. Alternate tooth replacement (in which new teeth erupt between two functional teeth), ankylosis, and intraosseous tooth development are plesiomorphic to Bluefish + other Scombroidei. Our study highlights the complexity and variability of intraosseous tooth replacement. Within tooth replacement systems, key variables include sites of formation of tooth germs, points of entry of tooth germs into dentigerous bones, coupling of tooth germ migration and bone erosion, whether teeth develop horizontally or immediately beneath the tooth to be replaced, and how tooth eruption and ankylosis occur. Developmentally different tooth replacement processes can yield remarkably similar dentitions.     

Chronic ethanol alters the receptor binding characteristics of the delta opioid receptor ligand,DAla2DLeu5 enkephalin in mouse brain

The binding characteristics of the delta opioid receptor ligand, ³HDAla²DLeu⁵ enkephalin, were markedly altered in brains obtained from mice fed an ethanol-containing diet for five days. Control mice exhibited both a high and low affinity site for ³HDAla²DLeu⁵ enkephalin, whereas those consuming the ethanol diet were found to possess only one binding site. This singular site has an intermediate K_D value with an increase in receptor number when compared to the high and low affinity sites observed in control mice. The $\text{in}$$\text{vitro}$ addition of ethanol to a brain membrane preparation obtained from untreated mice, at a concentration equivalent to that found in the blood of the ethanol-treated mice, did not markedly affect DAla²DLeu⁵ enkephalin binding characteristics. No alteration in the binding characteristics of ³H-naloxone, a mu receptor ligand, was noted following five days of ethanol consumption. Mice maintained on the ethanol-containing diet were tolerant to the activity-stimulating effects of acute ethanol administration. These results suggest that mice consuming an ethanol diet in sufficient quantities to render them tolerant exhibit a specific loss of a ³HDAla²DLeu⁵ enkephalin binding site, while the binding of ³H-naloxone was unchanged.     

Responses of woody vegetation to exclusion of large herbivores in semi‐arid savannas

The Nkuhlu large‐scale long‐term exclusion experiment in Kruger National Park was designed to study the long‐term effects of large herbivores on vegetation. One treatment excludes elephants, another excludes all herbivores larger than hares and another one comprises an open, control area. Vegetation monitoring was implemented in 2002 when a baseline survey was conducted prior to exclusion. Monitoring was repeated 5 years after exclusion. Data from the surveys were analysed to establish how structure and composition of woody vegetation had changed 5 years after herbivore exclusion. The analysis showed that neither plant assemblage nor mean vegetation height had changed significantly since exclusion. However, both species richness and density of woody plants increased 5 years after exclusion of all large herbivores, but not after the exclusion of elephants alone. One already common species, Dichrostachys cinerea, became more common after excluding all large herbivores compared with either no exclusion or elephant exclusion, possibly leading to competitive suppression of other species. Species other than D. cinerea tended to either increase or decrease in density, but the changes were insufficient to induce significant shifts in the overall assemblage of woody plants. The results indicate that after 5 years of exclusion, the combined assemblage of large herbivores, and not elephants alone, could induce changes in species richness and abundances of woody plants, but the effect was so far insufficient to induce measureable shifts in the assemblages of woody plants. It is possible that assemblages will change with time and increasing elephant numbers may amplify future changes.     

Bordetella bronchiseptica infection of rats and mice

Bordetella bronchiseptica has long been associated with respiratory tract infections in laboratory research, food-producing, companion, and wildlife animal species. Its range of distribution also may include humans and contaminated inanimate environmental sources. Natural diseases due to B. bronchiseptica infections in laboratory rats and mice were described before many of the major pathogens of these hosts were discovered. To our knowledge, there are no recent reports of natural disease due to B. bronchiseptica in these species; as a result, some have questioned its role as a natural pathogen in murine hosts. We reviewed occurrence of natural B. bronchiseptica infections and present information gained from recent experimental infection studies in murine hosts. We also discuss the potential impact of natural B. bronchiseptica infections on research and methods of control.     

Leo Semenovich Berg and the biology of Acipenseriformes: a dedication

This volume is dedicated to the memory of Leo Semenovich Berg (1876–1950), a Russian ichthyologist and geographer. In the foreword to the English translation of Berg's remarkable treatise, Nomogenesis or evolution according to law, Theodosius Dobzhansky wrote: Berg was one of the outstanding intellects among Russian scientists. The breadth of his interests and the depth as well as the amplitude of his scholarship were remarkable. He had the reputation of being a walking library, because of the amount of information he could produce from his memory (Dobzhansky 1969, p. xi). Berg was prolific, publishing 217 papers and monographs on ichthyology, 30 papers on general zoology and biology, 20 papers on paleontology, 32 papers on zoogeoégraphy, 320 papers and monographs on geography, geology, and ethnography, as well as 290 biographies, obituaries, and popular articles (Berg 1955, Sokolov 1955).     

Reticulocyte and micronucleated reticulocyte responses to gamma irradiation: dose-response and time-course profiles measured by flow cytometry

A flow cytometric, anti-CD71-based method was used to measure peripheral blood reticulocyte and micronucleated reticulocyte frequencies in response to (137)Cs total body irradiation (TBI). In three independent experiments, groups of five female C57BL/6N mice were irradiated at graded doses up to 3 Gy, and peripheral blood specimens were collected at 43 h post-irradiation. Whereas the frequency of reticulocytes declined over the range of doses studied, micronucleated reticulocyte incidence was observed to increase in a dose-dependent manner up to 1 Gy. At doses greater than approximately 1 Gy, micronucleated reticulocyte frequencies declined with increasing exposure. These responses were highly reproducible, with significant effects on reticulocyte and micronucleated reticulocyte frequencies observed for the lowest dose studied (0.125 Gy). A time-course experiment was performed to test whether radiation-induced cell cycle delay may explain saturation of the micronucleated reticulocyte endpoint at doses >1 Gy. For this experiment, groups of four female C57BL/6N mice were exposed to 1, 1.5, or 2 Gy TBI, and blood collection occurred at 12h intervals from 43 to 115 h post-exposure. Reduced reticulocyte frequencies were observed for each dose studied, and the recovery of reticulocytes was increasingly delayed with higher radiation doses. Maximal micronucleated reticulocyte frequencies were observed at 43 or 55 h, with progressively lower values at later time points. At no time did micronucleated reticulocyte frequencies induced by 1.5 or 2 Gy significantly exceed that observed for 1 Gy at 43 h. These time-course data suggest that radiation-induced cell cycle delay cannot account for the micronucleated reticulocyte downturn phenomenon observed at doses greater than 1 Gy. An alternate hypothesis is discussed whereby apoptotic elimination of severely damaged bone marrow erythroid precursors plays a dominant role in saturating the radiation-induced micronucleated reticulocyte response observed for C57BL/6N mice.