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PLoS ONE (2)
Autism Research and Treatment (1)
Journal of Bacteriology (1)
Moody, Eric K. (2)
Blakeley-Smith, Audrey (1)
Clayton, Murray K. (1)
Hayes, W. (1)
Hepburn, Susan (1)
Leuthe, Eileen (1)
Moody, Eric (1)
Moody, Eric E. M. (1)
Reaven, Judy (1)
Sabo, John L. (1)
Solomon, Christopher T. (1)
Vander Zanden, M. Jake (1)
Weidel, Brian C. (1)
Year of Publication
Stable Isotope Turnover and Half-Life in Animal Tissues: A Literature Synthesis
Vander Zanden, M. Jake
Clayton, Murray K.
Solomon, Christopher T.
Weidel, Brian C.
Stable isotopes of carbon, nitrogen, and sulfur are used as ecological tracers for a variety of applications, such as studies of animal migrations, energy sources, and food web pathways. Yet uncertainty relating to the time period integrated by isotopic measurement of animal tissues can confound the interpretation of isotopic data. There have been a large number of experimental isotopic diet shift studies aimed at quantifying animal tissue isotopic turnover rate λ (%·day-1, often expressed as isotopic half-life, ln(2)/λ, days). Yet no studies have evaluated or summarized the many individual half-life estimates in an effort to both seek broad-scale patterns and characterize the degree of variability. Here, we collect previously published half-life estimates, examine how half-life is related to body size, and test for tissue- and taxa-varying allometric relationships. Half-life generally increases with animal body mass, and is longer in muscle and blood compared to plasma and internal organs. Half-life was longest in ecotherms, followed by mammals, and finally birds. For ectotherms, different taxa-tissue combinations had similar allometric slopes that generally matched predictions of metabolic theory. Half-life for ectotherms can be approximated as: ln (half-life) = 0.22*ln (body mass) + group-specific intercept; n = 261, p<0.0001, r2 = 0.63. For endothermic groups, relationships with body mass were weak and model slopes and intercepts were heterogeneous. While isotopic half-life can be approximated using simple allometric relationships for some taxa and tissue types, there is also a high degree of unexplained variation in our models. Our study highlights several strong and general patterns, though accurate prediction of isotopic half-life from readily available variables such as animal body mass remains elusive.
Crayfish Impact Desert River Ecosystem Function and Litter-Dwelling Invertebrate Communities through Association with Novel Detrital Resources
Sabo, John L.
Shifts in plant species distributions due to global change are increasing the availability of novel resources in a variety of ecosystems worldwide. In semiarid riparian areas, hydric pioneer tree species are being replaced by drought-tolerant plant species as water availability decreases. Additionally, introduced omnivorous crayfish, which feed upon primary producers, allochthonous detritus, and benthic invertebrates, can impact communities at multiple levels through both direct and indirect effects mediated by drought-tolerant plants. We tested the impact of both virile crayfish (Orconectes virilis) and litter type on benthic invertebrates and the effect of crayfish on detrital resources across a gradient of riparian vegetation drought-tolerance using field cages with leaf litter bags in the San Pedro River in Southeastern Arizona. Virile crayfish increased breakdown rate of novel drought-tolerant saltcedar (Tamarix ramosissima), but did not impact breakdown of drought-tolerant seepwillow (Baccharis salicifolia) or hydric Fremont cottonwood (Populus fremontii) and Gooding's willow (Salix goodingii). Effects on invertebrate diversity were observed at the litter bag scale, but no effects were found at the cage scale. Crayfish decreased alpha diversity of colonizing macroinvertebrates, but did not affect beta diversity. In contrast, the drought-tolerant litter treatment decreased beta diversity relative to hydric litter. As drought-tolerant species become more abundant in riparian zones, their litter will become a larger component of the organic matter budget of desert streams which may serve to homogenize the litter-dwelling community and support elevated populations of virile crayfish. Through impacts at multiple trophic levels, crayfish have a significant effect on desert stream ecosystems.
Facing Your Fears in Adolescence: Cognitive-Behavioral Therapy for High-Functioning Autism Spectrum Disorders and Anxiety
Autism Research and Treatment
Adolescents with high-functioning autism spectrum disorders (ASDs) are at high risk for developing psychiatric symptoms, with anxiety disorders among the most commonly cooccurring. Cognitive behavior therapies (CBTs) are considered the best practice for treating anxiety in the general population. Modified CBT approaches for youth with high-functioning ASD and anxiety have resulted in significant reductions in anxiety following intervention. The purpose of the present study was to develop an intervention for treating anxiety in adolescents with ASD based on a CBT program designed for school-aged children. The Facing Your Fears-Adolescent Version (FYF-A) program was developed; feasibility and acceptability data were obtained, along with initial efficacy of the intervention. Twenty-four adolescents, aged 13–18, completed the FYF-A intervention. Results indicated significant reductions in anxiety severity and interference posttreatment, with low rates of anxiety maintained at 3-month follow-up. In addition, nearly 46% of teen participants met criteria for a positive treatment response on primary diagnosis following the intervention. Initial findings from the current study are encouraging and suggest that modified group CBT for adolescents with high-functioning ASD may be effective in reducing anxiety symptoms. Limitations include small sample size and lack of control group. Future directions are discussed.
Chromosome Transfer by Autonomous Transmissible Plasmids: the Role of the Bacterial Recombination (rec) System
Journal of Bacteriology
The ability of autonomous transmissible plasmids or sex factors to transfer chromosomal genes to F− recipient bacteria has been investigated by using a series of rec+ and recA− donor strains. It is concluded that chromosome transfer by most sex factors is virtually dependent upon the functional integrity of the bacterial recombination system. However, evidence is presented that suggests the existence of plasmid-specified mechanisms of interaction with the chromosome which are independent of the bacterial recombination system.
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