Transcriptional Analysis of Distant Signaling Induced by Insect Elicitors and Mechanical Wounding in Zea mays

When plants are under insect herbivore attack defensive measures are activated not only locally, but also in distant and systemic tissues. While insect elicitors (IE) abundant in the oral secretions of the attacking herbivore are essential in the regulation of induced defenses, little is known about their effects on systemic defense signaling in maize (Zea mays). The goal of this study was therefore to identify genetic markers that can be used to further characterize local and systemic signaling events induced by IE or mechanical wounding (MW). We selected genes for this study based on their putative involvement in signaling (allene oxide synthase), regulation of gene expression (transcription factor MYC7), and in direct defenses (ribosome inactivating protein) and analyzed their expression in different sections of the treated leaf as well as in systemic parts of the same plant. We found the most significant transcript accumulation of the selected genes after treatment with insect elicitors in those parts with increased JA levels. Additionally, treatment with IE did also induce the accumulation of MYC7 transcripts in basal parts of the treated leaf and systemically. MW, in contrast, did induce RIP and AOS only locally, but not MYC7. This local suppression of MYC7 was further studied by adding glutathione (GSH) as an electron donor to MW plants to quench putative α, β-unsaturated carbonyls, which build up to significant levels around the damage site. Indeed, GSH-treated MW plants accumulated MYC7 at the damage site and also produced more volatiles, suggesting a putative redox-regulatory element being involved in the suppression of MYC7. The results presented herein provide evidence for the specific induction of distant signaling events triggered by IE, most likely through electric signaling. Additionally, a putative role for MW-induced α, β-unsaturated carbonyls in the transcriptional regulation of defense genes was discovered

Trait plasticity in species interactions: a driving force of community dynamics.

Evolutionary community ecology is an emerging field of study that includes evolutionary principles such as individual trait variation and plasticity of traits to provide a more mechanistic insight as to how species diversity is maintained and community processes are shaped across time and space. In this review we explore phenotypic plasticity in functional traits and its consequences at the community level. We argue that resource requirement and resource uptake are plastic traits that can alter fundamental and realised niches of species in the community if environmental conditions change. We conceptually add to niche models by including phenotypic plasticity in traits involved in resource allocation under stress. Two qualitative predictions that we derive are: (1) plasticity in resource requirement induced by availability of resources enlarges the fundamental niche of species and causes a reduction of vacant niches for other species and (2) plasticity in the proportional resource uptake results in expansion of the realized niche, causing a reduction in the possibility for coexistence with other species. We illustrate these predictions with data on the competitive impact of invasive species. Furthermore, we review the quickly increasing number of empirical studies on evolutionary community ecology and demonstrate the impact of phenotypic plasticity on community composition. Among others, we give examples that show that differences in the level of phenotypic plasticity can disrupt species interactions when environmental conditions change, due to effects on realized niches. Finally, we indicate several promising directions for future phenotypic plasticity research in a community context. We need an integrative, trait-based approach that has its roots in community and evolutionary ecology in order to face fast changing environmental conditions such as global warming and urbanization that pose ecological as well as evolutionary challenges. © Springer Science+Business Media B.V. 2010

Caregiver burden during the year following severe traumatic brain injury

Fifty-two primary caregivers of people with a severe traumatic brain injury (TBI) were assessed at 6-months and 1-year postinjury. Caregiver appraisal of the person with TBI's physical, cognitive, emotional, behavioural, and social functioning was assessed. Caregiver psychosocial functioning and levels of subjective andobjective burden were also assessed. Some aspects of the difficulties reported for the people with TBI remained stable, while others increased in frequency, over time. At 6-months postinjury, approximately one third of caregivers reported clinically significant symptoms of anxiety and depression, and poor social adjustment. By 1-year postinjury, the prevalence of anxiety and depression remained the same, although only one-quarter continued to report poor social adjustment. There was some evidence of adaptation by caregivers,as the frequency with which various types of objective burden were reported remained stable, while the distress caused by these decreased in the first year postinjury. It appears that the impact on caregivers of physical impairment is comparatively short-lived and that caregivers learn some practical ways to manage the behavioural problems of the people with TBI. Despite this, over time the person with TBI's behavioural and cognitive problems begins to play a larger role in the level of distress experienced by the caregiver.However, it is the person with TBI's social isolation that has a stable and consistent role in the experience of subjective burden for primary caregivers in the first year postinjury

Psychosocial function during the year following severe traumatic brain injury

The psychosocial functioning of a group of 65 adults with severe traumatic brain injury was assessed at 6 months and 1 year post-injury. Aspects of emotional, behavioural, and social functioning were investigated. The prevalence of depression remained constant (24%) over time, although there was some individual variation in the reporting of symptoms. Impatience was the most frequently reported behavioural problem at both assessments. Whilst there was a slight increase in the number of behavioural problems and level of distress reported over time, the most obvious change was in the type of behavioural problems that caused distress. At 1 year post-injury, problems with emotional control were found to be most distressing for the patients. A comparison with pre-morbid social functioning showed the loss of employment to be 70%, 30% returned to live with their parents, and relationship breakdown occurred for 38%. There was also a significant and ongoing decrease in all five aspects of social and leisure activitie

Neuropsychological functioning during the year following severe traumatic brain injury

The neuropsychological functioning of a group of 65 adults with severe traumatic brain injury was assessed at 6 months and 1 year post-injury. The cognitive domains assessed were pre-morbid intellectual level, current level of general intellectual functioning, simple and complex attention, verbal memory, executive functioning, and perceptual functioning. At least 40%, and up to 74%, of the TBI patients displayed some degree of impairment on tests administered at 6 months. Improvement was found to occur in all areas of cognitive functioning over the first year following injury. Despite this improvement at least 31%, and up to 63%, of TBI patients displayed some degree of impairment on tests administered at 1 year post-injury. The various types of neuropsychological functioning were affected to different degrees, indicating that different aspects of cognition are more susceptible to injury, and that recovery takes place at a differential rate across functions. The implications of these findings for the appropriate planning and allocation of treatment and rehabilitation resources, and the development of effective rehabilitation interventions are outlined