Tropical cloud forest canopy and subcanopy adapt to different light environments by regulating photosynthetic pigments

The canopy and subcanopy of a Tropical Cloud Forest provide distinctly different light environments. Here, the amounts and ratios of photosynthetic pigments in leaves from a Cloud Forest canopy and subcanopy plants are compared. The pigments of forty canopy and subcanopy leaf samples are extracted using acetone and analyzed using a spectrophotometer. It is found that canopy and subcanopy plants possess equivalent means of concentrations of photosynthetic pigments per mass of leaf tissue (x = 0.21± 0.09 mg/g and 0.22 ± 0.11 mg/g, respectively). Therefore, plants from these two microhabitats invest the same quantity in major pigments for photosynthesis. However, the availability of light cause canopy plants to produce a higher concentration of photosynthetic pigments per area (x = 0.0079 ± 0.0026 mg/cm²) than subcanopy plants (x = 0.0059 ± 0.0019 mg/cm²). Based on the ratio of chlorophyll a to chlorophyll b, it appears that canopy plants (x =1.63 ± 0.57) use their photosynthetic pigments to maximize their rate of light processing. Subcanopy plants (x = 0.98 ± 0.26), in contrast, appear to maximize light absorption. Using the ratio of carotenoids to chlorophyll b, canopy plants (x = 1.24 ± 0.27) may be using carotenoids to prevent photoinhibition. Subcanopy plants, having a much lower carotenoids to chlorophyll b ratio (x = 0.97 ± 0.27), are possibly using carotenoids for further light absorption. El dosel y subdosel de un bosque nuboso tropical proporcionan ambientes de luz muy diferentes. En este caso, se comparan las cantidades y proporciones de los pigmentos fotosintéticos en hojas de un dosel del bosque nuboso y las plantas del subdosel.https://digitalcommons.usf.edu/tropical_ecology/1558/thumbnail.jp

Tropical cloud forest canopy and subcanopy adapt to different light environments by regulating photosynthetic pigments

The canopy and subcanopy of a Tropical Cloud Forest provide distinctly different light environments. Here, the amounts and ratios of photosynthetic pigments in leaves from a Cloud Forest canopy and subcanopy plants are compared. The pigments of forty canopy and subcanopy leaf samples are extracted using acetone and analyzed using a spectrophotometer. It is found that canopy and subcanopy plants possess equivalent means of concentrations of photosynthetic pigments per mass of leaf tissue (x = 0.21± 0.09 mg/g and 0.22 ± 0.11 mg/g, respectively). Therefore, plants from these two microhabitats invest the same quantity in major pigments for photosynthesis. However, the availability of light cause canopy plants to produce a higher concentration of photosynthetic pigments per area (x = 0.0079 ± 0.0026 mg/cm²) than subcanopy plants (x = 0.0059 ± 0.0019 mg/cm²). Based on the ratio of chlorophyll a to chlorophyll b, it appears that canopy plants (x =1.63 ± 0.57) use their photosynthetic pigments to maximize their rate of light processing. Subcanopy plants (x = 0.98 ± 0.26), in contrast, appear to maximize light absorption. Using the ratio of carotenoids to chlorophyll b, canopy plants (x = 1.24 ± 0.27) may be using carotenoids to prevent photoinhibition. Subcanopy plants, having a much lower carotenoids to chlorophyll b ratio (x = 0.97 ± 0.27), are possibly using carotenoids for further light absorption. El dosel y subdosel de un bosque nuboso tropical proporcionan ambientes de luz muy diferentes. En este caso, se comparan las cantidades y proporciones de los pigmentos fotosintéticos en hojas de un dosel del bosque nuboso y las plantas del subdosel.https://digitalcommons.usf.edu/tropical_ecology/1558/thumbnail.jp

Thunderstorm phobia in dogs

Master of ScienceDepartment of Animal Sciences and IndustryJanice C. SwansonCanine thunderstorm phobia is a common, frustrating, and complex problem that, due to the often severe nature of the clinical signs, can lead to canine relinquishment to shelters. Although a potentially treatable disorder, existing treatment options have several limitations and variable success rates. Three survey-based studies were conducted to increase the knowledge base for canine thunderstorm phobia. The first study distributed 1445 surveys through 16 Kansas veterinary clinics to determine the prevalence and characteristics of thunderstorm phobic dogs and assess differences between affected and non-affected dogs. Of 463 dogs surveyed, 240 were thunderstorm phobic as assessed by their owners. Severe weather warning systems may play a role in thunderstorm phobia. Thunderstorm phobic dogs were more fearful when exposed to tornado sirens, both during actual storms and siren testing, indicating a possible effect of classical conditioning. No differences were noted regarding sex, breed, pedigree, or neuter status. Most affected dogs preferred to be indoors remaining near their owners. The second study distributed 1600 surveys through eight Kansas animal shelters to determine the prevalence of relinquished dogs with thunderstorm phobia. Other reasons for relinquishment were also assessed. A fear of thunder was among the least common behavioral problems leading to relinquishment in dogs. Only a quarter of owners had visited a veterinarian for assistance with behavioral problems. The third study involved the administration of dog appeasing pheromone (DAP) in a double-blind, placebo-controlled, randomized clinical trial to assess its efficacy as a sole treatment for thunderstorm phobia. Data was collected from 60 dog owners using behavioral assessment questionnaires. In dogs given the placebo, six behaviors significantly improved, with another eleven showing a numerical trend toward improvement. However, in dogs given DAP, significant improvement was seen in three of these same behaviors. Consequently, these results do not indicate the potential use of DAP for reducing fearful behaviors associated with thunderstorm phobia when compared to negative controls. Information gained from these studies allows veterinarians and behavioral researchers to better understand the extent of this behavioral disorder and hopefully stimulates future research to find new and more effective ways to treat it

Structures of oncogenic, suppressor and rescued p53 core‐domain variants: mechanisms of mutant p53 rescue

To gain insights into the mechanisms by which certain second-site suppressor mutations rescue the function of a significant number of cancer mutations of the tumor suppressor protein p53, X-ray crystallographic structures of four p53 core-domain variants were determined. These include an oncogenic mutant, V157F, two single-site suppressor mutants, N235K and N239Y, and the rescued cancer mutant V157F/N235K/N239Y. The V157F mutation substitutes a smaller hydrophobic valine with a larger hydrophobic phenylalanine within strand S4 of the hydrophobic core. The structure of this cancer mutant shows no gross structural changes in the overall fold of the p53 core domain, only minor rearrangements of side chains within the hydrophobic core of the protein. Based on biochemical analysis, these small local perturbations induce instability in the protein, increasing the free energy by 3.6 kcal mol(-1) (15.1 kJ mol(-1)). Further biochemical evidence shows that each suppressor mutation, N235K or N239Y, acts individually to restore thermodynamic stability to V157F and that both together are more effective than either alone. All rescued mutants were found to have wild-type DNA-binding activity when assessed at a permissive temperature, thus pointing to thermodynamic stability as the critical underlying variable. Interestingly, thermodynamic analysis shows that while N239Y demonstrates stabilization of the wild-type p53 core domain, N235K does not. These observations suggest distinct structural mechanisms of rescue. A new salt bridge between Lys235 and Glu198, found in both the N235K and rescued cancer mutant structures, suggests a rescue mechanism that relies on stabilizing the β-sandwich scaffold. On the other hand, the substitution N239Y creates an advantageous hydrophobic contact between the aromatic ring of this tyrosine and the adjacent Leu137. Surprisingly, the rescued cancer mutant shows much larger structural deviations than the cancer mutant alone when compared with wild-type p53. These suppressor mutations appear to rescue p53 function by creating novel intradomain interactions that stabilize the core domain, allowing compensation for the destabilizing V157F mutation

Longitudinal evaluation of whole blood miRNA expression in firefighters

Background: Dysregulated microRNA (miRNA) expression could provide a mechanism linking firefighter exposure to increased cancer risk. Objective: To determine if changes in longitudinal miRNA expression in firefighters are associated with occupational exposures. Methods: Whole blood MiRNA was evaluated in 52 new recruits prior to live-fire training and 20–37 months later. Linear mixed effects models adjusted for age, ethnicity, BMI, and batch effects were used to determine associations separately for all fires and structure fires only between employment duration, cumulative fire-hours and fire-runs, and time since most recent fire with (1) nine a priori and (2) the full array of 799 miRNAs. Results: For multivariable models including all fires, two a priori miRNAs were associated with employment duration and four with time since most recent fire. For multivariable models restricted to structure fires, three a priori miRNAs were associated with employment duration and one with fire-runs. Additional miRNAs from the full array were associated with employment duration for all fires and/or structure fires. In general, tumor suppressive miRNAs decreased and oncogenic miRNAs increased with exposure. Significance: Changes in miRNAs may serve as biomarkers of exposure effects and a mechanism for increased cancer risk in firefighters. © 2021, The Author(s).Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Differential DNA Methylation by Hispanic Ethnicity Among Firefighters in the United States

Firefighters are exposed to a variety of environmental hazards and are at increased risk for multiple cancers. There is evidence that risks differ by ethnicity, yet the biological or environmental differences underlying these differences are not known. DNA methylation is one type of epigenetic regulation that is altered in cancers. In this pilot study, we profiled DNA methylation with the Infinium MethylationEPIC in blood leukocytes from 31 Hispanic white and 163 non-Hispanic white firefighters. We compared DNA methylation (1) at 12 xenobiotic metabolizing genes and (2) at all loci on the array (>740 000), adjusting for confounders. Five of the xenobiotic metabolizing genes were differentially methylated at a raw P-value <.05 when comparing the 2 ethnic groups, yet were not statistically significant at a 5% false discovery rate (q-value <.05). In the epigenome-wide analysis, 76 loci exhibited DNA methylation differences at q <.05. Among these, 3 CpG sites in the promoter region of the biotransformation gene SULT1C2 had lower methylation in Hispanic compared to non-Hispanic firefighters. Other differentially methylated loci included genes that have been implicated in carcinogenesis in published studies (FOXK2, GYLTL1B, ZBTB16, ARHGEF10, and more). In this pilot study, we report differential DNA methylation between Hispanic and non-Hispanic firefighters in xenobiotic metabolism genes and other genes with functions related to cancer. Epigenetic susceptibility by ethnicity merits further study as this may alter risk for cancers linked to toxic exposures. © The Author(s) 2021.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]