The rice TAL effector-dependent resistance protein XA10 triggers cell death and calcium depletion in the endoplasmic reticulum.

The recognition between disease resistance (R) genes in plants and their cognate avirulence (Avr) genes in pathogens can produce a hypersensitive response of localized programmed cell death. However, our knowledge of the early signaling events of the R gene-mediated hypersensitive response in plants remains limited. Here, we report the cloning and characterization of Xa10, a transcription activator-like (TAL) effector-dependent R gene for resistance to bacterial blight in rice (Oryza sativa). Xa10 contains a binding element for the TAL effector AvrXa10 (EBEAvrXa10) in its promoter, and AvrXa10 specifically induces Xa10 expression. Expression of Xa10 induces programmed cell death in rice, Nicotiana benthamiana, and mammalian HeLa cells. The Xa10 gene product XA10 localizes as hexamers in the endoplasmic reticulum (ER) and is associated with ER Ca(2+) depletion in plant and HeLa cells. XA10 variants that abolish programmed cell death and ER Ca(2+) depletion in N. benthamiana and HeLa cells also abolish disease resistance in rice. We propose that XA10 is an inducible, intrinsic terminator protein that triggers programmed cell death by a conserved mechanism involving disruption of the ER and cellular Ca(2+) homeostasis.

Progression of cognitive impairment after stroke: one year results from a longitudinal study of Singaporean stroke patients.

BACKGROUND AND PURPOSE: Vascular dementia accounts for 40-50% of dementia cases in Singapore. The aim of this study is to examine the prevalence and natural history of cognitive impairment in a cohort of Singaporean post-stroke patients. METHODS: The Vascular Dementia Battery (VDB) was offered to 252 patients with a transient ischaemic attack (TIA) or non-disabling ischaemic stroke at baseline (within 6 months post index stroke) and annually thereafter. The VDB assesses six cognitive domains: attention, language, verbal memory (recall and recognition), visual memory (recall and recognition), visuoconstruction and visuomotor speed. Dementia was diagnosed using the DSM-IV criteria. Patients who did not meet the DSM-IV criteria but were impaired in one or more cognitive domains were classified as 'cognitively impaired but not demented'. Those who were unimpaired in all cognitive domains were classified as 'cognitively intact'. RESULTS: At baseline, 56% of patients were 'cognitively intact', 40% were 'cognitively impaired but not demented' and 4% were 'demented'. At 1-year follow-up, 33% patients had a changed classification from baseline. While 31% of those who were 'cognitively impaired but not demented' at baseline improved to 'cognitively intact', 10% of the 'cognitively intact' group deteriorated to 'cognitively impaired but not demented' and 11% deteriorated from 'cognitively impaired but not demented' to 'demented'. Cognitive performance at baseline predicted for deterioration. CONCLUSIONS: This study suggests that the long-term cognitive performance in stroke patients change over time. Further studies are required to identify risk factors and effective treatment for cognitive deterioration after stroke.