Identification of the blast resistance gene Pit in rice cultivars using functional markers

DNA markers that allow for identification of resistance genes in rice germplasm have a great advantage in resistance breeding because they can assess the existence of the genes without laborious inoculation tests. Functional markers (FMs), which are designed from functional polymorphisms within the sequence of genes, are unaffected by nonfunctional allelic variation and make it possible to identify an individual gene. We previously showed that the resistance function of the rice blast resistance gene Pit in a resistant cultivar, K59, was mainly acquired by up-regulated promoter activity through the insertion of a long terminal repeat (LTR) retrotransposon upstream of Pit. Here, we developed PCR-based DNA markers derived from the LTR-retrotransposon sequence and used these markers to screen worldwide accessions of rice germplasm. We identified 5 cultivars with the LTR-retrotransposon insertion out of 68 rice accessions. The sequence and expression pattern of Pit in the five cultivars were the same as those in K59 and all showed Pit-mediated blast resistance. The results suggest that the functional Pit identified using the markers was derived from a common progenitor. Additionally, comparison of the Pit coding sequences between K59 and susceptible cultivars revealed that one nucleotide polymorphism, which caused an amino acid substitution, offered another target for a FM. These results indicate that our DNA markers should enhance prediction of Pit function and be applicable to a range of rice varieties/landraces cultivated in various regions worldwide and belonging to the temperate japonica, tropical japonica, and indica groups.

Oligoastrocytoma of the brain in a hooded crane (Grus monacha)

A cerebral tumor was identified at necropsy in a mature female hooded crane (Grus monacha). On gross examination, the cut surface of the tumor revealed a soft gelatinous mass. On histologic examination, the tumor was mainly composed of 2 discrete components that resembled oligodendroglioma and astrocytoma. Both components had anaplastic changes, such as pleomorphism, high proliferative activity, microvascular proliferation, and necrosis. The oligodendrogliomatous component showed a honeycomb appearance formed by the accumulation of variably sized neoplastic cells with perinuclear halos and central nuclei. The astrogliomatous component consisted of remarkably pleomorphic cells, including bizarre giant cells. Immunohistochemistry revealed that the oligodendrogliomatous component cells were partially immunoreactive for vimentin and myelin basic protein, and the astrogliomatous component cells were immunoreactive for vimentin, S-100, and glial fibrillary acidic protein. Based on these findings, the tumor was diagnosed as an oligoastrocytoma.

Needle-shaped deposits on retinal surface in a case of ocular amyloidosis

PURPOSE

To report a case in which optical coherence tomography (OCT) showed needle-shaped deposits on the retinal surface oriented toward the vitreous cavity and immunohistochemical findings suggested light chain-related amyloidosis.

METHODS

A 59-year-old man with no systemic complications had bilateral neovascular glaucoma and vitreous opacities in the right eye. Vitrectomy was conducted on the right eye and the excised vitreous was examined histopathologically.

RESULTS

Glass wool-like opacities were observed during vitrectomy. Postoperative fundus examination of the right eye showed retinal hemorrhage and white deposits around blood vessels and on retinal surface. Fluorescein angiography revealed hyperfluorescence of the optic disc, non-perfusion areas, and vascular focal staining. OCT depicted needle-shaped deposits perpendicular to the retinal surface oriented toward the vitreous. Histologic examination of deposits revealed positive reaction for Congo red stain, and immunohistochemical examination demonstrated positive reactivities for anti-lambda and anti-kappa light chains (precursors of amyloid protein), suggesting a diagnosis of light chain-related amyloidosis.

CONCLUSIONS

In this case, OCT showed needle-shaped deposits perpendicular to the retinal surface. Special staining with Congo red revealed the deposit to be amyloid deposition. Immunohistochemical staining suggested light chain-related amyloidosis. Vascular obstructive lesions and neovascular glaucoma secondary to retinal vascular damage in amyloidosis warrant particular attention.

Induced Rice Resistance to Blast Varies as a Function of Magnaporthe grisea Avirulence Genes

Incompatibility reactions between rice and the blast fungus Magnaporthe grisea produce various degrees of lesions, from large brown flecks to small, nearly invisible lesions. We previously identified four avirulence genes (AvrPia, AvrPii, AvrPit, and Avr-Hattan3) in M. grisea isolates by genetic analysis of progeny from crosses between isolates with differing pathogenicity. Using progeny known to contain a specific avirulence gene, we demonstrated that the type of resistance lesion produced in rice by an avirulent isolate and the degree of leaf blast suppression by preinoculation with that isolate were determined by the combination of avirulence and resistance genes in the isolate and the cultivar. The degree of leaf blast suppression by preinoculation with an avirulent isolate increased with larger resistance lesions. When two genes were involved in an isolate's avirulence, lesions appeared that resembled those expected for the gene that produced the smaller lesion. The degree of leaf blast suppression by the isolate with two avirulence genes was comparable with that induced by the isolate with the avirulence gene that produced the smaller effect. The ability of specific resistance gene combinations that effectively suppress blast disease is discussed for each avirulence gene.

Significant associations of metabolic syndrome and its components with silent lacunar infarction in middle aged subjects

BACKGROUND

Metabolic syndrome (MetS) is associated with an increased risk of ischaemic stroke, including silent brain infarction. No study has examined its association with the lacunar subtype. The present cross sectional study examined the relationship between MetS, its components and silent lacunar infarction (SLI) in middle aged subjects.

METHODS

We studied 2076 subjects aged 40-59 years with no history of stroke or clinical symptoms, who visited a health care facility for a routine health checkup and underwent brain MRI. MetS was defined according to the National Cholesterol Education Programme Adult Treatment Panel III report. A multiple logistic regression model was used to examine the associations between MetS and SLI while adjusting for age, gender, a past history of ischaemic heart disease and current smoking.

RESULTS

MetS was strongly associated with the presence of SLI (adjusted OR 6.52; 95% CI 4.30 to 9.90). Regarding MetS components, elevated blood pressure, impaired fasting glucose, hypertriglyceridaemia and large waist circumference were significantly associated with SLI, independent of an interrelationship between the components, while low high density lipoprotein cholesterol was not significantly associated.

CONCLUSIONS

MetS was significantly associated with the prevalence of SLI in middle aged persons. Independent risk factors for SLI not only included elevated blood pressure and impaired fasting glucose, which are well known risk factors, but also hypertriglyceridaemia and large waist circumference.