[Show abstract][Hide abstract] ABSTRACT: The objective of this study was to examine the role of basic psychological need satisfaction as a potential
mediator of the relationship between health-enhancing physical activity (HEPA) and well-being.
Participants (N = 201) were young adults who recalled their HEPA behavior, experiences of psychological
need satisfaction, and levels of well-being across multiple indicators using a cross-sectional
design targeting the previous day. Results from path analysis demonstrated that effort put forth in
HEPA activities, as opposed to frequency or duration of HEPA, predicted well-being. Further, psychological
needs satisfaction mediated between 10% and 44% of the HEPA-Effort - well-being relationship.
Overall, these findings lend credence to the notion that effortful investment is associated with well-being
when engaged in HEPA, and that the satisfaction of basic psychological needs may act as a salient
explanatory mechanism partially accounting for that relationship.
Mental Health and Physical Activity 12/2012; 5(2):141-147. DOI:10.1016/j.mhpa.2012.10.004
[Show abstract][Hide abstract] ABSTRACT: Objectives
The purpose of this study was to examine the effects of different scoring protocols used with instruments designed to assess motivation in line with Organismic Integration Theory (OIT; Deci & Ryan, 2002).DesignThis study used non-probability based sampling within a cross-sectional (survey) design.Methods
Participants across four samples (N's ranged from 236 to 1200) completed either (a) the Behavioral Regulation in Exercise Questionnaire (BREQ), (b) the BREQ-2, or (c) the BREQ-2R in conjunction with a self-report assessment of physical activity behavior.ResultsParticipants endorsed more self-determined than controlled motives for physical activity. Identified regulation was the dominant correlate of more frequent physical activity behavior. The link between external regulation and physical activity was consistently weak. Multiple regression analyses revealed identified regulation was the strongest predictor of physical activity compared with other motives. Regression models using omnibus scoring protocols accounted for less variance in physical activity behavior in contrast to an item-aggregation scoring protocol.Conclusions
Identified regulation may be a key source of physical activity motivation in adults. The scoring protocol used with OIT-based instruments represents an important consideration for advancing physical activity research.
Psychology of Sport and Exercise 09/2012; 13(5):614-622. DOI:10.1016/j.psychsport.2012.03.009 · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objectives: The purpose of this investigation was to test associations between the fulfillment of basic psychological needs and two dimensions of psychological well-being using (a) an additive model and (b) a balanced model. Design: This study employed a non-probability based sampling and a cross-sectional design. Methods: Collegiate volleyball players (N = 219; n(females) = 127) completed a battery of self-report instruments. Results: Aligned within Basic Psychological Needs Theory (Deci & Ryan, 2002) and study hypotheses (Sheldon & Niemiec, 2006), results demonstrated that basic psychological need fulfillment was associated with psychological well-being in the context of volleyball (R(adj)(2) ranged from 0.20 to 0.35). Balanced psychological need fulfillment was generally predictive, albeit minimally, of well-being indices beyond the contributions made by perceived competence, autonomy and relatedness. Conclusions: This investigation highlights the need for further study of BPNT in the realm of sport including assessments of balanced need satisfaction on markers of well-being.
Psychology of Sport and Exercise 09/2011; 12(5):533-539. DOI:10.1016/j.psychsport.2011.05.006 · 1.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Kong, L., Tull, R., Holtz, C.T., Montello, P.M., Sakowski, R., Nairn, C.J., and Merkle, S.A. 2011. Application of airlift bioreactors for highly efficient genetic transformation of American chestnut. In: Proceedings of the 31st Southern Forest Tree Improvement Conference, June 13-16, Biloxi, MS, p.102.
The 31st Southern Forest Tree Improvement Conference; 06/2011
[Show abstract][Hide abstract] ABSTRACT: Merkle, S.A., Kong, L., Tull, R., Andrade, G., Montello, P.M., Holtz, C.T., Sakowski, R., and Nairn, C.J. 2011. Scaling-up Transgenic American Chestnut Somatic Seedling Production for the Forest Health Initiative. In: Proceedings of the 31st Southern Forest Tree Improvement Conference, June 13-16, Biloxi, MS, pp. 58-60.
The 31st Southern Forest Tree Improvement Conference; 06/2011
[Show abstract][Hide abstract] ABSTRACT: In order to facilitate infection, fungal pathogens produce various types of secreted proteases likely to target and perturb important plant proteins that are involved in controlling basal defense. In addition, they secrete several protease inhibitors such as Avr9 of Cladosporium fulvum that, based on its structure, is predicted to be a carboxy peptidase inhibitor. Protease inhibitors are potentially able to deactivate or detoxify host target proteases and, therefore, might play an important role during infection. In this study we are investigating the role of C. fulvum protease and protease inhibitors in disease establishment by using both functional genomics and biochemical approaches. We mined the genome of C. fulvum and found numerous proteases and protease inhibitors of which many are secreted. Expression analyses of these genes were performed using RNA extracted from fungal mycelium grown in vitro on liquid media under different conditions as well as from inoculated susceptible tomato plants. Interestingly, many of these genes are highly expressed only in vitro and/or in planta and based on their expression profiles we selected a number of candidates for further functional analyses. We will generate knock‐out mutants of the selected proteases and protease inhibitors to identify their role in virulence. In addition, biochemical approaches will be used to pull‐down the host target proteins of some presumably important candidate proteins such as for example the Avr9 protein
[Show abstract][Hide abstract] ABSTRACT: Most fungal effectors characterized so far are species-specific and facilitate virulence on a particular host plant. During infection of its host tomato, Cladosporium fulvum secretes effectors that function as virulence factors in the absence of cognate Cf resistance proteins and induce effector-triggered immunity in their presence. Here we show that homologs of the C. fulvum Avr4 and Ecp2 effectors are present in other pathogenic fungi of the Dothideomycete class, including Mycosphaerella fijiensis, the causal agent of black Sigatoka disease of banana. We demonstrate that the Avr4 homolog of M. fijiensis is a functional ortholog of C. fulvum Avr4 that protects fungal cell walls against hydrolysis by plant chitinases through binding to chitin and, despite the low overall sequence homology, triggers a Cf-4-mediated hypersensitive response (HR) in tomato. Furthermore, three homologs of C. fulvum Ecp2 are found in M. fijiensis, one of which induces different levels of necrosis or HR in tomato lines that lack or contain a putative cognate Cf-Ecp2 protein, respectively. In contrast to Avr4, which acts as a defensive virulence factor, M. fijiensis Ecp2 likely promotes virulence by interacting with a putative host target causing host cell necrosis, whereas Cf-Ecp2 could possibly guard the virulence target of Ecp2 and trigger a Cf-Ecp2-mediated HR. Overall our data suggest that Avr4 and Ecp2 represent core effectors that are collectively recognized by single cognate Cf-proteins. Transfer of these Cf genes to plant species that are attacked by fungi containing these cognate core effectors provides unique ways for breeding disease-resistant crops
[Show abstract][Hide abstract] ABSTRACT: In Germany, maize is one of the most important agriculture commodities, a major component in animal feed as well as an essential substrate producing biogas. Maize car rot poses a major impact worldwide as it is caused by several Fusarium spp., most of which have the ability to produce mycotoxins. Despite of the expansion of the maize acreage in recent years, limited information is available concerning the incidence of Fusarium car rot in Germany. Therefore, in a two-year survey maize crops were sampled in the major maize-producing areas in Germany to establish the severity of Fusarium car rot and the biodiversity of Fusarium species. In 2006, the frequency of kernels infected by Fusarium spp. ranged from 0.7% to 99.7%; the average incidence was 32.4%. Thirteen Fusarium species were isolated from maize kernels, with F verticillioides, F. graminearum and F. proliferatum being the predominant species. In 2007, the highest incidence of Fusarium car rot was 64%; the mean level of infection was 21.7%. F. graminearum was by far the most frequent species isolated from all sampled fields in 2007. In addition, F. crookwellense, F. subglutinans and F. avenaceum were also frequently isolated, In particular, the fumonisin-producing species F. verticillioides all F. proliferatum were less frequent than in 2006. The year-to-year variability in the frequency of Fusarium species and in the overall infection rate may be explained by significant differences ill temperature and precipitation during the growth periods.
[Show abstract][Hide abstract] ABSTRACT: A quantitative detection tool was developed to enable the monitoring of fumonisin-producing fungi in food and feed commodities. To this end, a quantitative PCR (TaqMan) was developed that targets a conserved region in the polyketide synthase gene fum1, which is involved in the biosynthesis of fumonisin. Hence, this method specifically detected isolates from the fumonisin-producing species Fusarium verticillioides, F. proliferatum, F. nygamai and F. globosum whereas isolates of the fumonisin non-producing species F. equiseti, F. graminearum, F. oxysporum, F. semitectum and F. subglutinans that commonly occur on maize were not detected. Moreover, a few fumonisin non-producing F. verticillioides isolates did not generate any fluorescent signals and were therefore not detected. The correlation between quantitative PCR and mycotoxin content was determined using field samples collected at homestead farms in South Africa. Among 40 samples from the Eastern Cape collected in 2005 a good correlation (R2=0.8303) was found between pg fungal DNA and fumonisin content. A similar correlation (R2=0.8658) was found among 126 samples collected from four provinces in South Africa in 2007. These observations indicate that samples containing ¿ 40 pg fungal DNA/mg sample are suspected of also exceeding the 1 mg/kg total fumonisin level and therefore do not comply with the European Commission limit for fumonisins B1+B2 for maize intended for direct human consumption that applies from 1 October 2007. Combined with the very high maize intake, our results indicate that fumonisin levels in maize from South African homesteads regularly exceed the tolerable daily intake for fumonisins.
World Mycotoxin Journal 02/2008; 1(1). DOI:10.3920/WMJ2008.x005 · 2.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Understanding the factors that motivate health-enhancing physical activity has considerable merit given the role of this lifestyle behaviour in combating disease and promoting quality of life. The purpose of this article is to provide a broad overview of research investigating participation issues in exercise from the perspective of self-determination theory (SDT; Deci & Ryan, 2002). Evidence informing the application of SDT to the study of motivational issues in exercise is reviewed around three central questions: (a) Does the quality of motivation regulating exercise behaviour "matter"?, (b) How important are basic psychological needs within exercise contexts?, and (c) Can contextual variables be manipulated to create adaptive environments for exercise? The available evidence is supportive of many propositions set forth within SDT by Deci and Ryan's (2002). Future avenues for exercise motivation research are offered based on the available evidence with a view to addressing unresolved issues and advancing SDT's development.
Canadian Psychology 01/2008; 49:250-256. · 1.54 Impact Factor