Protective Effects of Calcium Against Chronic Waterborne Cadmium Exposure to Juvenile Rainbow Trout

Juvenile rainbow trout (Oncorhynchus mykiss [Walbaum]) on 1% daily ration were exposed to 0 (control) or 2 μg of cadmium as Cd(NO3)2·4H2O per liter added to four different calcium (Ca) concentrations: 260 (background), 470 (low), 770 (medium), or 1200 (high) μM of Ca added as Cd(NO3)2·4H2O in synthetic soft water for 30 d. Mortality was highest (;80%) in the background 1 Cd treatment. Approximately 40% mortality was observed in the low 1 Cd exposure; mortality was 10% or less for all other treatments. No growth effects were seen for any of the exposures. Kidneys accumulated the greatest concentration of Cd during the 30 d, followed by gills and livers. Accumulation of Cd in gills, kidney, and liver decreased at higher water Ca concentrations. No differences in whole-body or plasma Ca concentrations were found. Swimming performance was impaired in the low + Cd-exposed fish. Influx of Ca2+ into whole bodies decreased as water Ca concentrations increased; influx of Ca2+ into background + Cd–treated fish was significantly reduced compared to that in control fish. Experiments that measured uptake of new Cd into gills showed that the affinity of gills for Cd (KCd-gill) and the number of binding sites for Cd decreased as water Ca concentrations increased. Acute accumulation of new Cd into gills and number of gill Cd-binding sites increased with chronic Cd exposure, whereas the affinity of gills for Cd decreased with chronic Cd exposure. Longer-term gill binding (72 h) showed reduced uptake of new Cd at higher water Ca levels and increased uptake with chronic Cd exposure. Complications were found in applying the biotic ligand model to fish that were chronically exposed to Cd because of discrepancies in the maximum number of gill Cd-binding sites among different studies

Thermoregulation by big brown bats (eptesicus fuscus): ontogeny, proximate mechanisms, and dietary influences

Bibliography: p. 167-193Some pages are in colour.I studied the thermoregulatory behaviour of big brown bats (Eptesicus fuscus) of different ages in the field, investigated adaptations associated with thermoregulation (i.e., degree of insulation, clustering behaviour, hair development, and changes in metabolic rate), and examined potential dietary influences (i.e., fatty acid content of milk and handling-time of beetles) on the use of torpor. By extrapolating laboratory measurements of metabolic rate at given skin temperatures and ambient temperatures, I estimated metabolic savings associated with torpor in the field for bats based on skin temperature and ambient temperature measurements alone. On a daily basis, estimated energy expenditure of individual bats in the field was 5-19% lower than if they had remained normothermic over 24 h. Morphological, behavioural, and physiological factors may contribute to energy expenditure or energy savings from the use of torpor. For example, clustering within the roost further reduced expenditure. Laboratory measurements of skin temperature and metabolic rate indicated that clustering by older juveniles and adults reduced metabolic expenditure by up to 52%. Alternatively, by going torpid at low ambient temperatures, metabolic savings up to 98% were realized by bats during metabolic trials. Unlike older juveniles, early prevolant juveniles appear incapable of staying warm when their mothers are away from the roost during foraging. The body of E. fuscus was fully furred by 7 days of age, coinciding with fully developed thermoregulatory capability. Because early prevolant juveniles did not maintain normothermic body temperatures at low ambient temperatures when stimulated to do so, it appears as though they are physiologically incapable of staying warm, rather than being capable of staying warm but choosing not to. Early prevolant juveniles may not realize any energetic benefits associated with clustering, and it may be more beneficial for them to roost alone. Changes in milk composition during lactation corresponded to changes in thermoregulatory ability of juvenile E. fuscus. Handling time of beetles by volant juveniles was significantly different from that of adults, corresponding with a reduction in the use of torpor by early volant juveniles. These data suggest that diet may play a significant role in limiting use of torpor

Variation in body temperature and isolation calls of juvenile big brown bats, Eptesicus fuscus

Ye

Mutations in the gene encoding the 3'-5' DNA exonuclease TREX1 are associated with systemic lupus erythematosus

TREX1 acts in concert with the SET complex in granzyme A - mediated apoptosis, and mutations in TREX1 cause Aicardi-Goutieres syndrome and familial chilblain lupus. Here, we report monoallelic frameshift or missense mutations and one 3' UTR variant of TREX1 present in 9/ 417 individuals with systemic lupus erythematosus but absent in 1,712 controls (P= 4.1x10(-7)). We demonstrate that two mutant TREX1 alleles alter subcellular targeting. Our findings implicate TREX1 in the pathogenesis of SLE