Elevated CO2 and conifer roots: effects on growth, life span and turnover

Elevated CO₂ increases root growth and fine (diam. 2 mm) root growth across a range of species and experimental conditions. However, there is no clear evidence that elevated CO₂ changes the proportion of C allocated to root biomass, measured as either the root:shoot ratio or the fine root:needle ratio. Elevated CO₂ tends to increase mycorrhizal infection, colonization and the amount of extramatrical hyphae, supporting their key role in aiding the plant to more intensively exploit soil resources, providing a route for increased C sequestration. Only two studies have determined the effects of elevated CO₂ on conifer fine-root life span, and there is no clear trend. Elevated CO₂ increases the absolute fine-root turnover rates; however, the standing crop root biomass is also greater, and the effect of elevated CO₂ on relative turnover rates (turnover:biomass) ranges from an increase to a decrease. At the ecosystem level these changes could lead to increased C storage in roots. Increased fine-root production coupled with increased absolute turnover rates could also lead to increases in soil organic C as greater amounts of fine roots die and decompose. Although CO₂ can stimulate fine-root growth, it is not known if this stimulation persists over time. Modeling studies suggest that a doubling of the atmospheric CO₂ concentration initially increases biomass, but this stimulation declines with the response to elevated CO₂ because increases in assimilation are not matched by increases in nutrient supply.     

Habitat Use and Survival of Preflight Wild Turkey Broods

Abstract: Wild turkey (Meleagris gallopavo) broods spend the first several days of life on the ground until poult flight capabilities are attained. This is a critical period of wild turkey life history, with poult survival ranging from 12% to 52%. We measured vegetation in plots used by Rio Grande wild turkey (M. g. intermedia) preflight broods at 4 sites in southwest Kansas and the Texas Panhandle, USA, to determine microhabitat selection for ground roosting and to determine if microhabitat was related to poult survival. Hens selected ground-roost locations with more visual obstruction from multiple observation heights than random sites. Plots surrounding ground roosts had 1) greater visual obstruction; 2) increased tree decay; 3) higher percent grass, shrub, litter, and forb cover; and 4) lower percent bare ground cover than random sites. Grass, shrubs, and downed trees appeared to provide desired cover for ground-roosting broods. Poult survival increased with age of poult, size of brood, and density of shrubs 1–2 m tall. Plots used by broods <10 days old with above average survival contained more visual obstruction and shrubs than plots used by broods 10–16 days old with above average survival, signifying a shift in habitat use by successful broods as poults attain flight abilities. Density of shrubs 1–2 m tall in brood-use areas appears to be important for poult survival to 16 days of age on southern Great Plains rangeland habitats. Ground-level vegetative cover appears to be a significant factor in preflight poult survival. Provisions of ground-level vegetative cover should be considered during wild turkey brooding periods where increased poult survival is desired.     

Livestock Protection Dogs for Deterring Deer From Cattle and Feed

Abstract: Disease transmission between wildlife and livestock is a worldwide issue. Society needs better methods to prevent interspecies transmission to reduce disease risks. Producers have successfully used livestock protection dogs (LPDs) for thousands of years to reduce predation. We theorized that LPDs raised and bonded with cattle could be used to also reduce risk of bovine tuberculosis (Myobacterium bovis; TB) transmission between white-tailed deer (Odocoileus virginianus) and cattle by minimizing contact between the 2 species and use of cattle feed by deer. We evaluated 4 LPDs over 5 months, utilizing 2 data collection methods (direct observation and motion-activated video) on deer farms that supported higher densities than wild populations. Dogs were highly effective in preventing deer from using concentrated cattle feed (hay bales), likely the greatest risk factor of TB transmission on farms. Dogs also prevented deer from approaching cattle in core areas of pastures (near hay bales) and were very effective throughout pastures. Our research supports the theory that LPDs, specifically trained to remain with cattle, may be a practical tool to minimize potential for livestock to contract TB from infected deer in small-scale cattle operations. Where disease is present in deer, it may be possible to reduce the potential for disease transmission by employing LPDs.     

Keratinocytes Suppress TRP‐1 Expression and Reduce Cell Number of Co‐cultured Melanocytes – Implications For Grafting of Patients with Vitiligo

A pilot study for grafting of patients with vitiligo using cultured epithelial autografts containing melanocytes gave disappointing clinical results, with pigmentation achieved in only one out of five patients. Irrespective of the fate of melanocytes grafted back onto the patients, we experienced problems in identifying melanocytes within these well‐integrated keratinocyte sheets. This led us to explore the fate of these cells within these sheets in vitro and to seek to improve their number and function within the sheets. We report that the introduction of a fibroblast feeder layer can improve melanocyte number within melanocyte/keratinocyte co‐cultures initially, but at very high keratinocyte density, there is a marked loss of melanocytes (as detected by staining for S100). Additionally, we found that keratinocytes not only down‐regulate melanocyte number, but also pigmentary function; thus, it was possible to identify melanocytes that were S100 positive but tyrosinase‐related protein‐1 (TRP‐1) negative in confluent well‐integrated keratinocyte sheets. In summary, our data suggest that keratinocytes at high density initially suppress melanocyte pigmentation (as evidenced by a lack of TRP‐1 expression) and then cause a physical loss of melanocytes. The introduction of a fibroblast feeder layer can help maintain melanocyte number while keratinocytes are subconfluent, but fails to oppose the inhibitory influence of the keratinocytes on melanocyte TRP‐1 expression.     

Some Interactions of Gibberellic Acid with Naringenin (5,7, 4'-trihydroxy flavanone) in the Control of Dormancy and Growth in Plants

The possibility that dormancy and growth are at least partlycontrolled by an interaction between endogenous gibberellinand inhibitor was investigated. Antagonistic effects of twonaturally occurring inhibitors (coumarin and naringenin) upondormancy-breaking or growth-stimulation by gibberellic acid(GA₃) was demonstrated. Naringenin, which occurs in dormantpeach buds, was found competitively to antagonize GAS in thelatter compound's effect of breaking peachbud dormancy. Naringeninwas found to induce a light-requirement for the germinationof ‘Great Lakes’ lettuce seed, which effect couldbe reversed by the addition of GA₃, the extent of the reversalbeing a function of the relative concentrations of the two compounds.Interaction between GA₃ and either coumarin or naringenin innon-dormant tissue (lettuce hypocotyl growth assay) was foundto be non-competitive. An analogy is drawn between the knownoestrogenic and other physiological activities of flavonoids,and the growth-effects of naringenin and hydrangenol.