Editorial

Systemic Practice and Action Research -     

Denning chronology of black bears in eastern Rocky Mountain National Park, Colorado

Understanding factors influencing the timing of den entrance and emergence of black bears ( Ursus americanus ) provides insight for bear management. We determined den entrance and emergence dates for bears in Rocky Mountain National Park (RMNP) and related these dates to vegetative productivity, weather, habitat, and demographic factors to assess the influence of these factors on denning chronology. Date of den entrance was most strongly influenced by age class, precipitation, and proportion of human-use areas in annual home ranges. Den entrance was typically later for adult bears during wetter years and when annual home ranges contained a greater proportion of human-use areas. Sex and presence of human-use areas were most strongly related to den emergence. Male bears typically emerged from dens before females, and bears emerged from dens earlier when human-use areas composed a greater proportion of annual home ranges. Collectively, our results suggest that denning behavior of black bears in RMNP was strongly influenced by presence of human-use areas, likely because of foods associated with such areas. Managers of black bears in RMNP can use precipitation to predict relative dates of den entrance, thereby allowing for more efficient strategies to combat potentially negative human–black bear encounters.     

Reproduction of the prairie skink, Eumeces septentrionalis , in Nebraska

Clutch sizes of the prairie skink, Eumeces septentrionalis , in Nebraska are positively correlated with female snout-vent lengths (SVLs). Data presented in this study and others indicate Nebraska populations of E. septentrionalis have larger average clutch sizes than other populations within this species' range.     

Nutritional condition of elk in Rocky Mountain National Park

We tested the hypothesis that elk in Rocky Mountain National Park (RMNP) were at ecological carrying capacity by determining herd-specific levels of nutritional condition and fecundity. Ingesta-free body fat levels in adult cows that were lactating were 10.6% ( s = 1.7; range = 6.2-15.4) and 7.7% ( s = 0.5; range = 5.9-10.1) in November 2001 for the Horseshoe and Moraine Park herds, respectively. Cows that were not lactating were able to accrue significantly more body fat: 14.0% ( s = 1.1; range = 7.7-19.3) and 11.5% ( s = 0.8; range = 8.6-15.1) for the Horseshoe and Moraine Park herds, respectively. Cow elk lost most of their body fat over winter (April 2002 levels were 3.9% [ s = 0.4] and 2.9% [ s = 0.4] for the Horseshoe and Moraine Park herds, respectively). Nutritional condition indicated that both Horseshoe Park and Moraine Park elk were well below condition levels elk can achieve on very good-excellent nutrition (i.e., > 15% body fat; Cook et al. 2004) and were comparable to other free-ranging elk populations. However, condition levels were higher than those expected at a ""food-limited"" carrying capacity, and a proportion of elk in each herd were able to achieve condition levels indicative of very good-excellent nutrition. Elk in RMNP are likely regulated and/or limited by a complex combination of density-independent (including significant heterogeneity in forage conditions across RMNP's landscape) and density-dependent processes, as condition levels contradict a simple density-dependent model of a population at ecological carrying capacity.     

Knowing of the Unknowable

A number of systemic theories appear to be converging in conclusion. The conclusion is that things are inherently unknowable to the human mind. People are coming to know of the unknowable. This paper introduces such ideas in the context of systemic practice. Implications for efficiency, effectiveness, and ethical matters are discussed.     

Additional studies on the effects of neonatal thymectomy and lactate dehydrogenase virus infection on mice

Zusammenfassung Die gegebenen Befunde lassen vermuten, dass neonatale Thymektomie und/oder Infektion mit LDH-Virus einen Effekt auf eine Anzahl von Faktoren wie LDH-Plasma-Spiegel, Gewichtserhöhung und Lebensdauer in Mäusen hervorrufen können. Der Virustiter im Plasma ist vom Zeitpunkt der Infektion abhängig.

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Supported by Public Health Service research grant No. 5 R01 CA05742-06 from the National Cancer Institute.     

Fluorescein-concanavalin A conjugates distinguish between normal and malignant human cells: a preliminary report

A method is described for using a fluorescein isothiocyanate concanavalin A conjugate to stain human cell membranes in formalin fixed paraffin embedded tissue. 57 neoplastic and normal tissue sites were examined. In 54 malignant tumours, bright green fluorescence was confined to the cell membranes while in 23 benign tumours and normal tissue sites, the membranes were unstained or showed a diminished level of fluorescence. The distinction between malignant and hyperplastic or normal cells was clear cut and definite.     

CD36 is a sensor of diacylglycerides

Toll-like receptor 2 (TLR2) is required for the recognition of numerous molecular components of bacteria, fungi and protozoa. The breadth of the ligand repertoire seems unusual, even if one considers that TLR2 may form heteromers with TLRs 1 and 6 (ref. 12), and it is likely that additional proteins serve as adapters for TLR2 activation. Here we show that an N-ethyl-N-nitrosourea-induced nonsense mutation of Cd36 (oblivious) causes a recessive immunodeficiency phenotype in which macrophages are insensitive to the R-enantiomer of MALP-2 (a diacylated bacterial lipopeptide) and to lipoteichoic acid. Homozygous mice are hypersusceptible to Staphylococcus aureus infection. Cd36(obl) macrophages readily detect S-MALP-2, PAM(2)CSK(4), PAM(3)CSK(4) and zymosan, revealing that some--but not all--TLR2 ligands are dependent on CD36. Already known as a receptor for endogenous molecules, CD36 is also a selective and nonredundant sensor of microbial diacylglycerides that signal via the TLR2/6 heterodimer.