Common ringtail possum (Pseudocheirus peregrinus) as a management model for the Pseudocheiridae: Reproductive scope,behavior, and biomedical values on a browse-free diet

The purposes of this study were to determine 1) the life history characteristics of a captive colony of the arboreal folivore Pseudocheirus peregrinus maintained on a browse free diet under enhanced laboratory conditions, 2) the direction and magnitude of life history differences from wild population values, and 3) the feasibility of developing captive colonies of this and related species for conservation and research programs. Rates of reproduction, growth, and development; demographic trends; behavioral patterns pertinent to exhibition; and management and medical techniques are reported. Fecundity was 67% greater than that of wild populations and there was an approximate four-fold increase in the rate of offspring survival to sexual maturity. These trends were due largely to reduced post-pouch emergence mortality and the decay of reproductive seasonality. The results indicate that a properly designed “artificial” diet can support significantly enhanced reproduction in a trophic specialist. Other demographic, developmental, and behavioral measures found to be consistent with those reported from wild populations indicate that there was no significant life history distortion caused by the management regime. Empirical data are presented showing that the common ringtail is nocturnal, has low rates of activity, and has specific space and substrate preferences. These results suggest ways in which the animals' physical environment can be manipulated to improve exhibition. We conclude that the reproductive rates of other ringtail possum species might also be enhanced under comparable management conditions.     

Temperature effects on food supply and chick mortality in tree swallows (Tachycineta bicolor)

Tree swallow (Tachycineta bicolor) breeding success in Ithaca, NY, USA, over the past quarter century has shown generally healthy fledgling production punctuated by years of high nestling mortality. This study tested the potential effects that temperature may have on the food supply and breeding success of swallows. Data from 17 years of daily insect samples were used to relate flying insect abundances to daily maximum temperatures and to define “cold snaps” as strings of consecutive days when the maximum temperatures did not exceed critical temperatures. The distributions of cold snaps and chick mortality events were investigated both through detailed reconstructions of the fates and fate dates of individual chicks, focused on the three breeding seasons of lowest fledging success, and with less detailed brood-level analyses of a larger 11-year dataset including years of more moderate mortality. Mark–recapture analyses of daily brood survival rate (DSR) reveal very strong support for the effects of cold temperatures on brood survival rates, and all the top models agree on a critical temperature of 18.5 °C for insect flight activity in Ithaca. The individual-level analyses, focused on years of higher mortality, favored a 3-day cold snap definition as the most predictive of DSR effects, whereas the larger-scale brood-level analyses revealed 1- and 2-day cold snaps as having the most significant effects on DSR. Regardless, all analyses reveal that, in an age of generally warmer climates, the largest effect of weather on swallow fledgling production is from cold temperatures.     

Evidence that the catalytic differences of two structurally homologous forms of cytochrome P-450 relate to their heme environment

Cytochromes P-450 PB3a and PB3b, which appear to be equivalent to forms b and e described by Ryan et al. [Ryan, D.E., Thomas, P.E., & Levin, W. (1982) Arch. Biochem. Biophys. 216, 272-288], have been shown to share 97% sequence homology [Suwa, Y., Mizukami, Y., Sogawa, K., & Fujii-Kuriyama, Y. (1985) J. Biol. Chem. 260, 7980-7984] yet exhibit an intriguing difference in enzymatic activity. Studies to establish the basis for this difference, including a development of the technique of surface-enhanced resonance Raman spectroscopy (SERRS), are reported. Studies on substrate binding, metabolism, and redox properties, as well as SERRS, indicate a significant difference in the heme environment of these two proteins. No significant difference in the interaction of the two proteins with P-450 reductase could be established. However, this interaction appeared sensitive to changes in ionic strength, suggesting ionic interactions are important in the functional coupling of these electron-transport components. A marked variation in the ratio of PB3a to PB3b activity in the metabolism of different substrates, which included a series of structurally similar resorufin analogues, provided further evidence that reductase coupling was not a critical factor. Therefore, the few amino acid differences observed between these proteins indicate sites that may be important in influencing the heme environment of these cytochrome P-450's.     

Time-Course Analysis of Brain Regional Expression Network Responses to Chronic Intermittent Ethanol and Withdrawal: Implications for Mechanisms Underlying Excessive Ethanol Consumption

Long lasting abusive consumption, dependence, and withdrawal are characteristic features of alcohol use disorders (AUD). Mechanistically, persistent changes in gene expression are hypothesized to contribute to brain adaptations leading to ethanol toxicity and AUD. We employed repeated chronic intermittent ethanol (CIE) exposure by vapor chamber as a mouse model to simulate the cycles of ethanol exposure and withdrawal commonly seen with AUD. This model has been shown to induce progressive ethanol consumption in rodents. Brain CIE-responsive expression networks were identified by microarray analysis across five regions of the mesolimbic dopamine system and extended amygdala with tissue harvested from 0-hours to 7-days following CIE. Weighted Gene Correlated Network Analysis (WGCNA) was used to identify gene networks over-represented for CIE-induced temporal expression changes across brain regions. Differential gene expression analysis showed that long-lasting gene regulation occurred 7-days after the final cycle of ethanol exposure only in prefrontal cortex (PFC) and hippocampus. Across all brain regions, however, ethanol-responsive expression changes occurred mainly within the first 8-hours after removal from ethanol. Bioinformatics analysis showed that neuroinflammatory responses were seen across multiple brain regions at early time-points, whereas co-expression modules related to neuroplasticity, chromatin remodeling, and neurodevelopment were seen at later time-points and in specific brain regions (PFC or HPC). In PFC a module containing Bdnf was identified as highly CIE responsive in a biphasic manner, with peak changes at 0 hours and 5 days following CIE, suggesting a possible role in mechanisms underlying long-term molecular and behavioral response to CIE. Bioinformatics analysis of this network and several other modules identified Let-7 family microRNAs as potential regulators of gene expression changes induced by CIE. Our results suggest a complex temporal and regional pattern of widespread gene network responses involving neuroinflammatory and neuroplasticity related genes as contributing to physiological and behavioral responses to chronic ethanol.     

The Role of Regret in Informed Consent

Informed consent to medical procedures tends to be construed in terms of principle-based ethics and one or other form of expected utility theory. These constructions leave problems created by imperfect communication; subjective distress and other emotions; imperfect knowledge and incomplete understanding; complexity, and previous experience or the lack of it. There is evidence that people giving consent to therapy or to research participation act intuitively and assess consequences holistically, being influenced more by the magnitude of outcomes than their probability. People avoid decisions they may regret, but modern regret theory has received little attention in discussions of informed consent. This essay suggests ways in which regret may be acknowledged in the consent process and in the assessment of the information that is an intrinsic part of it.