Atmospheric CO2 Enrichment and Reactive Nitrogen Inputs Interactively Stimulate Soil Cation Losses and Acidification.

Reactive N inputs (Nr) may alleviate N-limitation of plant growth and are assumed to help sustain plant responses to the rising atmospheric CO2 (eCO2). However, Nr and eCO2 may elicit a cascade reaction that alters soil chemistry and nutrient availability, shifting the limiting factors of plant growth, particularly in acidic tropical and subtropical croplands with low organic matter and low nutrient cations. Yet, few have so far examined the interactive effects of Nr and eCO2 on the dynamics of soil cation nutrients and soil acidity. We investigated the cation dynamics in the plant-soil system with exposure to eCO2 and different N sources in a subtropical, acidic agricultural soil. eCO2 and Nr, alone and interactively, increased Ca2+ and Mg2+ in soil solutions or leachates in aerobic agroecosystems. eCO2 significantly reduced soil pH, and NH4+-N inputs amplified this effect, suggesting that eCO2-induced plant preference of NH4+-N and plant growth may facilitate soil acidification. This is, to our knowledge, the first direct demonstration of eCO2 enhancement of soil acidity, although other studies have previously shown that eCO2 can increase cation release into soil solutions. Together, these findings provide new insights into the dynamics of cation nutrients and soil acidity under future climatic scenarios, highlighting the urgency for more studies on plant-soil responses to climate change in acidic tropical and subtropical ecosystems.

Transect based analysis versus area based analysis to quantify shoreline displacement: spatial resolution issues.

Field surveys, aerial photographs, and satellite images are the most commonly employed sources of data to analyze shoreline position, which are further compared by area based analysis (ABA) or transect based analysis (TBA) methods. The former is performed by computing the mean shoreline displacement for the identified coastal segments, i.e., dividing the beach area variation by the segment length; the latter is based on the measurement of the distance between each shoreline at set points along transects. The present study compares, by means of GIS tools, the ABA and TBA methods by computing shoreline displacements recorded on two stretches of the Tuscany coast (Italy): the beaches of Punta Ala, a linear coast without shore protection structures, and the one at Follonica, which is irregular due to the presence of groins and detached breakwaters. Surveys were carried out using a differential global positioning system (DGPS) in RTK mode. For each site, a 4800-m-long coastal segment was analyzed and divided into ninety-six 50-m-long sectors for which changes were computed using both the ABA and TBA methods. Sectors were progressively joined to have a length of 100, 200, 400, and 800 m to examine how this influenced results. ABA and TBA results are highly correlated for transect distance and sector length up to 100 m at both investigated locations. If longer transects are considered, the two methods still produce good correlated data on the smooth shoreline (i.e. at Punta Ala), but correlation became significantly lower on the irregular shoreline (i.e., at Follonica).

Seeking Safety treatment for male veterans with a substance use disorder and post-traumatic stress disorder symptomatology.

AIMS: To determine whether substituting Seeking Safety (SS), a manualized therapy for comorbid substance use disorders (SUD) and post-traumatic stress disorder (PTSD) for part of treatment-as-usual (TAU) improves substance use outcomes. DESIGN: Randomized controlled effectiveness trial. SETTINGS: Out-patient Veterans Administration Health Care System SUD clinic. PARTICIPANTS: Ninety-eight male military Veterans with a SUD and co-occurring PTSD symptomatology. MEASUREMENTS: Drug and alcohol use and PTSD severity, measured on the first day of treatment, and 3 (i.e. the planned end of SS sessions) and 6 months following the baseline assessment. Treatment attendance and patient satisfaction were measured following treatment (3-month follow-up). Active coping was measured at treatment intake and following treatment. FINDINGS: SS compared to TAU was associated with better drug use outcomes (P < 0.05), but alcohol use and PTSD severity decreased equally under both treatments (P's < 0.01). SS versus TAU was associated with increased treatment attendance, client satisfaction and active coping (all P's < 0.01). However, neither these factors nor decreases in PTSD severity mediated the effect of treatment on drug use. CONCLUSIONS: The manualized treatment approach for substance use disorder, Seeking Safety, is well received and associated with better drug use outcomes than 'treatment as usual' in male veterans with post-traumatic stress disorder. However, the mechanism of its effect is unclear.

SGEF, a RhoG guanine nucleotide exchange factor that stimulates macropinocytosis.

SGEF (SH3-containing Guanine Nucleotide Exchange Factor) is a RhoGEF of unknown function. We found the SGEF protein to be expressed in many established cell lines and highly expressed in human liver tissue. SGEF stimulated the formation of large interconnected membrane ruffles across dorsal surfaces when expressed in fibroblasts. SGEF required its proline-rich amino-terminus to generate dorsal, but not lateral, membrane ruffles and a functional SH3 domain to colocalize with filamentous actin at sites of membrane protrusion. Full-length SGEF activated RhoG, but not Rac, when expressed in fibroblasts. Further, recombinant SGEF DH/PH protein exchanged nucleotide on RhoG, but not on Rac1 or Rac3, in vitro. Scanning electron microscopy of fibroblasts demonstrated that SGEF induced dorsal ruffles that were morphologically similar to those generated by constitutively active RhoG, but not constitutively active Rac1. Transient expression of SGEF stimulated fibroblast uptake of 10-kDa dextran, a marker of macropinocytosis. This required the full-length protein and a catalytically active DH domain. Finally, activated RhoG was found to be more effective than activated Rac, and comparable to SGEF, in its ability to trigger dextran uptake. Together, this work establishes SGEF as a RhoG exchange factor and provides evidence that both SGEF and RhoG regulate membrane dynamics in promotion of macropinocytosis.