Hydrothermal sensitivities of seed populations underlie fluctuations of dormancy states in an annual plant community

Plant germination ecology involves continuous interactions between changing environmental conditions and the sensitivity of seed populations to respond to those conditions at a given time. Ecologically meaningful parameters characterizing germination capacity (or dormancy) are needed to advance our understanding of the evolution of germination strategies within plant communities. The germination traits commonly examined (e.g., maximum germination percentage under optimal conditions) may not adequately reflect the critical ecological differences in germination behavior across species, communities, and seasons. In particular, most seeds exhibit primary dormancy at dispersal that is alleviated by exposure to dry after-ripening or to hydrated chilling to enable germination in a subsequent favorable season. Population-based threshold (PBT) models of seed germination enable quantification of patterns of germination timing using parameters based on mechanistic assumptions about the underlying germination physiology. We applied the hydrothermal time (HTT) model, a type of PBT model that integrates environmental temperature and water availability, to study germination physiology in a guild of coexisting desert annual species whose seeds were after-ripened by dry storage under different conditions. We show that HTT assumptions are valid for describing germination physiology in these species, including loss of dormancy during after-ripening. Key HTT parameters, the hydrothermal time constant (θHT ) and base water potential distribution among seeds (Ψb (g)), were effective in describing changes in dormancy states and in clustering species exhibiting similar germination syndromes. θHT is an inherent species-specific trait relating to timing of germination that correlates well with long-term field germination fraction, while Ψb (g) shifts with depth of dormancy in response to after-ripening and seasonal environmental variation. Predictions based on variation among coexisting species in θHT and Ψb (g) in laboratory germination tests matched well with 25-yr observations of germination dates and fractions for the same species in natural field conditions. Seed dormancy and germination strategies, which are significant contributors to long-term species demographics under natural conditions, can be represented by readily measurable functional traits underlying variation in germination phenologies.This 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]

Sex Differences in Change in Skin Temperature When Exercising in a Hot, Humid Environment

The risk for heat-related illness is increased when exercising in a hot, humid environment. In an effort to protect the athlete, body temperature is measured continuously while exercising in extreme environments. Currently, researchers and laboratory personnel employ the use of mean skin temperature to monitor athlete safety; however, this measurement fails to consider localized changes in temperature that may arise as a function of sex and exercise time. Therefore, the purpose of this study was to examine potential sex differences in the change in skin temperature at 17 different upper body locations while exercising in a hot, humid environment. Young men and women were recruited and completed a 60-min walk/jog interval protocol in a hot (34.1 ± 1 °C), humid (64 ± 8%) environment while skin temperature was continuously measured. To account for differences that may have arisen due to differing workloads between men and women, energy expenditure and metabolic heat production were calculated after the completion of exercise. Data was analyzed either a repeated-measures ANOVA (change in skin temperature) or t-test­ (energy expenditure and metabolic heat production). Location of interaction effects was determined using a Fisher’s Least Significant Difference test. Significance was set a p\u3c0.05 for all statistical testing. There was no difference between men and women in total energy expenditure; however, men were found to have a higher metabolic heat production. Women had a higher change in skin temperature at three locations on the back (left upper, right upper, and right mid-back). Conversely, there were no differences at any time point between men and women in the change in core temperature from baseline measurements. This study highlights the need to further investigate sex differences in cooling mechanisms while exercising in a hot, humid environment

Consumption of a high-fat meal increased monocyte adhesion molecule expression and oxLDL phagocytosis: implications for cardiovascular disease risk?

Macrophage-derived foam cells are the predominant component of arterial plaques in the early stages of atherosclerosis. The deposition of arterial plaques is effected by several factors that are influenced by a person’s daily nutritional habits. One factor that poses a major risk for plaque development is high levels of plasma LDL resulting from the consumption of a high-fat meal. In order to understand how an individuals’ diet effects arterial plaque deposition via the process of foam cell formation, we measured the acute response in circulating monocyte activity after consuming a high-fat meal. Samples were acquired on a FlowSight (EMD Millipore) equipped with 405, 488, 642, and 785 nm lasers. Samples were analyzed in IDEAS software to identify pro-inflammatory (CD14+/16+) and classic (CD14+/16-) monocytes. We measured monocyte concentration, adhesion molecule expression, scavenger R expression, and oxLDL phagocytosis for 5 h postprandial. We found that consuming a high-fat meal caused an increase in pro-inflammatory monocyte concentration, adhesion molecule expression, monocyte phagocytosis of oxLDL, and CD36 expression in pro-inflammatory monocytes. These results suggest that consuming a high-fat meal increases the potential of monocytes to become foam cells for at least 5 h postprandial

Synthesis of N-Acyl-N,O-Acetals from N-Aryl Amides and Acetals in the Presence of TMSOTf

Secondary amides undergo in situ silyl imidate formation mediated by TMSOTf and an amine base, followed by addition to acetal acceptors to provide N-acyl-N,O-acetals in good yields. An analogous, high-yielding reaction is observed with 2-mercaptothiazoline as the silyl imidate precursor. Competing reduction of the acetal to the corresponding methyl ether via transfer hydrogenation can be circumvented by the replacement of i-Pr2NEt with 2,6-lutidine under otherwise identical reaction conditions

Using Dry Blood Spots to Evaluate Serum Cytokines and Chemokines in Humans via Multiplex Technology

Introduction: Dried Blood Spot (DBS) analysis has been used routinely since 1963 for the assessment of metabolic diseases in neonates; however, recent efforts have focused on the refinement and validation of DBS for other patient populations. The purpose of this study was to adapt existing DBS methods to analyze 38 serum cytokines/chemokines in human subjects. Validation will be completed by comparing DBS to serum for a given analyte. Methods: After providing informed consent, subjects (N=21) provided a finger-stick DBS or venous serum sample using standard technique. Subjects were apparently healthy, non-obese, and had no known disease. Finger-stick capillary blood samples were collected on Whatman 903 Protein Saver Card (Maidstone, U.K.) and frozen with desiccant in sealed bags prior to elution. DBS samples (2, 6 mm punches) were eluted and transferred through 96-well Multiscreen and Ultracel plates (EMD Millipore) using elution buffer (PBS with 0.5 M NaCL and 0.1% Tween-20) for 16-18 h in the refrigerator. The resultant DBS elute was resuspended in 90 mL of nuclease-free water. Serum samples were thawed overnight in the refrigerator to prevent protein loss. Prior to Milliplex analysis, protein and lipid content were analyzed using a IR-based spectrometer (EMD Millipore Direct Detect). DBS solutions were also analyzed for hemoglobin concentration. Samples were analyzed in pairs to determine the concentration 38 cytokines/chemokines using a Magnetic Multiplex Kit (Milliplex Map Kit High Sensitivity Human Cytokine; Billerica ,MA), A minimum of 50 beads of each targeted analyte were collected on a Luminex MagPix (Austin, TX) and analyzed using Milliplex Analyst Software. Bi-variate correlations were completed in SPSS to compare DBS with serum. Results: Of the 38 markers, 13 were measurable in both DBS and serum, and 3 of these were significantly correlated with each other: Eotaxin (.755), MDC (.446), IP-10 (.831). Based on a post-hoc sample size analysis we need to expand our sample size by approximately 40 subjects in order to establish significant correlations the other 10 DBS measurable cytokines/chemokines. Conclusion: Utilization of DBS may make it possible to obtain previously unobtainable blood samples in a field setting. Despite the potential for DBS all serum markers have not been validated in this sample source. An increase in validated biomarkers detectable in DBS could make the decision to utilize DBS over venipuncture easier. Now that we have identified changes in resting cytokines/chemokines, the next logical step is to evaluate the effect of exercise

Volume-energy correlations in the slow degrees of freedom of computer-simulated phospholipid membranes

Constant-pressure molecular-dynamics simulations of phospholipid membranes in the fluid phase reveal strong correlations between equilibrium fluctuations of volume and energy on the nanosecond time-scale. The existence of strong volume-energy correlations was previously deduced indirectly by Heimburg from experiments focusing on the phase transition between the fluid and the ordered gel phases. The correlations, which are reported here for three different membranes (DMPC, DMPS-Na, and DMPSH), have volume-energy correlation coefficients ranging from 0.81 to 0.89. The DMPC membrane was studied at two temperatures showing that the correlation coefficient increases as the phase transition is approached

The biomechanics of amnion rupture: an X-ray diffraction study

Pre-term birth is the leading cause of perinatal and neonatal mortality, 40% of which are attributed to the pre-term premature rupture of amnion. Rupture of amnion is thought to be associated with a corresponding decrease in the extracellular collagen content and/or increase in collagenase activity. However, there is very little information concerning the detailed organisation of fibrillar collagen in amnion and how this might influence rupture. Here we identify a loss of lattice like arrangement in collagen organisation from areas near to the rupture site, and present a 9% increase in fibril spacing and a 50% decrease in fibrillar organisation using quantitative measurements gained by transmission electron microscopy and the novel application of synchrotron X-ray diffraction. These data provide an accurate insight into the biomechanical process of amnion rupture and highlight X-ray diffraction as a new and powerful tool in our understanding of this process

Reduced Inflammatory and muscle damage biomarkers following oral supplementation with bioavailable curcumin

This article seeks to determine the effects of oral curcumin supplementation on muscle and activities of daily living soreness, creatine kinase, and inflammatory cytokines following exercise-induced muscle damage

HCI policy and the smart city

While the idea of the ‘Smart City’ has attracted increasing attention from academia, industry, and government this interest has largely had a technical and technological focus. This paper identifies some of the important political and policy challenges facing the idea, the discourse, of a ‘smart city’ as a means to optimise HCI input into the ‘smart city’ debate. It then addresses that gap by detailing a research project that explored how experts in smart city research and development in the UK context responded to this policy challenge. Experts were asked questions regarding their prior experience with the “smart city”, their understandings of what it means for a city to be smart, and what policy potentials they've recognised in the smart city. The paper analyses and offers a synthesis of the responses collected throughout the research with the current policies concerning various smart city proximity, thereby providing a critical assessment of the values underlying the smart city. The paper aims to explore and present some of the policy possibilities for UK smart cities that are potentially useful for politicians, policy makers, planners, academics, and technology companies. I believe that these perspectives for policy development can be used to inform responsible development, spatially and socially inclusive technologies, and ultimately more resilient and liveable cities

Behavior and Impact of Zirconium in the Soil–Plant System: Plant Uptake and Phytotoxicity

Because of the large number of sites they pollute, toxic metals that contaminate terrestrial ecosystems are increasingly of environmental and sanitary concern (Uzu et al. 2010, 2011; Shahid et al. 2011a, b, 2012a). Among such metals is zirconium (Zr), which has the atomic number 40 and is a transition metal that resembles titanium in physical and chemical properties (Zaccone et al. 2008). Zr is widely used in many chemical industry processes and in nuclear reactors (Sandoval et al. 2011; Kamal et al. 2011), owing to its useful properties like hardness, corrosion-resistance and permeable to neutrons (Mushtaq 2012). Hence, the recent increased use of Zr by industry, and the occurrence of the Chernobyl and Fukashima catastrophe have enhanced environmental levels in soil and waters (Yirchenko and Agapkina 1993; Mosulishvili et al. 1994 ; Kruglov et al. 1996)