Drought reduces productivity and anti-herbivore defences, but not mycorrhizal associations, of perennial prairie forbs.

During drought, plants allocate resources to aboveground biomass production and belowground carbohydrate reserves, often at the expense of production of defence traits. Additionally, drought has been shown to alter floral resources, with potential implications for plant-pollinator interactions. Although soil symbionts, such as arbuscular mycorrhizal (AM) fungi, can alleviate drought stress in plants, certain levels of drought may negatively impact this relationship, with potential cascading effects. Because of their importance to plant and animal community diversity, we examined effects of drought on biomass production, physical defence properties, nectar production, and associated AM fungal abundance of five common prairie forb species in a greenhouse study. Reduced soil moisture decreased vegetative biomass production. Production of trichomes and latex decreased under drought, relative to well-watered conditions. Ruellia humilis flowers produced less nectar under drought, relative to well-watered conditions. Intra-radical AM fungal colonization was not significantly affected by drought, although extra-radical AM fungal biomass associated with S. azurea decreased following drought. Overall, grassland forb productivity, defence, and nectar production were negatively impacted by moderate drought, with possible negative implications for biotic interactions. Reduced flower and nectar production may lead to fewer pollinator visitors, which may contribute to seed limitation in forb species. Reduced physical defences increase the likelihood of herbivory, further decreasing the ability to store energy for essential functions, such as reproduction. Together, these results suggest drought can potentially impact biotic interactions between plants and herbivores, pollinators, and soil symbionts, and highlights the need for direct assessments of these relationships under climate change scenarios.

Systemic lupus erythematosus: neuropsychiatric signs and symptoms related to cerebral MRI findings.

A 76.2% prevalence of abnormalities was found in the cerebral MR scans of 21 patients with systemic lupus erythematosus (SLE). These patients were enrolled in the study consecutively as they presented at an immunological out-patient unit. They were not selected on the basis of neuro/psychiatric findings. Circumscribed non-periventricular brain lesions were found in 12 patients (57.1%), mainly in the frontal white or gray matter. Periventricular lesions directly adjacent to the ventricles were detected in 10 patients (47.6%). Eleven patients (52.4%) showed signs of cerebral atrophy. MRI detected more lesions in patients with clinically focal CNS lupus than in patients with seizures or patients without clinically localized findings. Eleven patients had abnormal neuropsychiatric CNS findings; there was no clear correlation between neuropsychiatric signs and symptoms and brain abnormalities as shown by MRI. Seven patients had asymptomatic lesions. Cerebral MRI proved to be the method of choice for the non-clinical diagnosis of neuropsychiatric SLE.

Incidental white-matter foci on MRI in "healthy" subjects: evidence of subtle cognitive dysfunction.

The clinical significance of incidental white-matter foci seen on MRI is controversial. Mainly using a computer-assisted neuropsychological test battery, we tested the hypothesis that there is a clinical correlate of these foci. We studied 41 individuals aged 45-65 years with no history of neurological or psychiatric disorder, in whom no indication of central nervous system abnormalities was found on standardised neurological examination. A computer-assisted neuropsychological test battery, with the advantage of precise measuring of both time and deviation (e.g. in position memory tests), and rating scales for emotional dysfunction were administered; selected soft neurological signs were assessed. In 16 subjects (39%) MRI showed high-signal foci in the white matter on spin-echo sequences. White-matter foci not adjacent to the lateral ventricles were found to be related to performance on immediate visual memory/visuoperceptual skills, visuomotor tracking/psychomotor speed and, to a lesser degree, learning capacity and abstract and conceptual reasoning skills. Subtle cognitive dysfunction would appear to be a clinical correlate of punctate white-matter foci on MRI of otherwise "healty" individuals.