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Biomedical subjects

Akira Kanazawa

Publications and source records attributed to Akira Kanazawa.

9 recordsLinked to original sources

Suppressor activity against cosuppression conferred by the petunia vein clearing virus genome.

The petunia genome contains an endogenous pararetrovirus, petunia vein clearing virus (PVCV). Previous analyses indicate that PVCV has suppressor activity against RNA silencing, but the suppressor protein has not been identified. Here we tested whether an open reading frame (ORF) of PVCV confers the activity that can suppress cosuppression of the CHS-A genes encoding chalcone synthase, which has a high rate of RNA turnover in the petal tissues of petunia. Petunia transformants that express PVCV ORF under the control of cauliflower mosaic virus 35S promoter were produced. The transgenic plants were crossed with those that have CHS-A cosuppression to produce plants that contain both the PVCV ORF transgene and CHS-A transgene. The coexistence of these transgenes resulted in phenotypic changes: pigmentation of various extents occurred on the originally white petals of CHS-A cosuppression phenotype. The generation of pigmented portions in flower petals coincided with higher transcript levels of CHS-A and PVCV ORF and less CHS-A short interfering RNA. These results indicate that the PVCV ORF can suppress CHS-A cosuppression and change the flower color phenotype when it is expressed as a transgene.

Petunia↗

The regulatory function of the upstream sequence of the beta-conglycinin alpha subunit gene in seed-specific transcription is associated with the presence of the RY sequence.

beta-conglycinin, a major component of seed-storage proteins in soybean, comprises three subunits: alpha, alpha', and beta. Expression of these genes is spatially regulated in a stringent manner and occurs during seed development. To understand the mechanisms that control expression of the alpha subunit gene, we analyzed the nucleotide sequence of the 2.9-kb region upstream of the gene. The upstream sequence up to -1357 or a series of its 5'-deleted derivatives was fused to the beta-glucuronidase (GUS) gene. These reporter gene constructs were introduced into Arabidopsis thaliana plants via Agrobacterium-mediated gene transfer. Prominent GUS activity was detected in developing seeds of the T3 generation when 245 bp or longer sequences of the upstream region were fused to the GUS gene. We found a clear association of decreased GUS activity with a stepwise deletion of a region containing the RY sequence from the original construct. These results are consistent with the notion that multiple sequence elements including the RY sequences are involved in the seed-specific transcriptional activation of the beta-conglycinin alpha subunit gene in soybean.

Antigens, Plant↗

The star-type color pattern in Petunia hybrida 'red Star' flowers is induced by sequence-specific degradation of chalcone synthase RNA.

Petunia hybrida 'Red Star' is a variety whose flowers exhibit a star-type red and white bicolor pattern. We analyzed the mRNA levels of six genes involved in anthocyanin biosynthesis. Only the level of chalcone synthase (CHS) mRNA was depressed in the unpigmented flower sectors. Both transcriptional activity and the accumulation of short interfering RNA of CHS in the unpigmented sectors were detected. Viral infection blocked the generation of CHS-silenced sectors. These results indicate that sequence-specific degradation of CHS RNA is the primary cause of the formation of white sectors in 'Red Star' flowers.

Acyltransferases↗

Molecular analysis and physicochemical properties of electrophoretic variants of wild soybean Glycine soja storage proteins.

Cultivated soybeans (Glycine max) are derived from wild soybeans (Glycine soja) and can be crossed with them to produce fertile offspring. The latter exhibit greater genetic variation than the former, suggesting a possibility that wild soybeans contain storage proteins with properties different from and better than those of cultivated soybeans. To identify a wild soybean suitable for breeding a new soybean cultivar, we analyzed seed proteins from 390 lines of wild soybeans by electrophoresis. We found some lines containing electrophoretic variants of glycinin and beta-conglycinin subunits: one line containing a small alpha' subunit of beta-conglycinin and two and five lines containing small A3 and large A4 polypeptides of glycinin, respectively. Beta-Conglycinin and glycinin containing such variant subunits exhibited solubility and emulsifying ability similar to those of the predominant types of wild and cultivated soybeans. Glycinins containing small A3 and large A4 gave a shoulder derived from the start of denaturation at a temperature 4 degrees C lower than that of glycinin from the predominant types of wild and cultivated soybeans, although their thermal denaturation midpoint temperatures were very similar to each other. Cloning and sequencing of the predominant and variant subunit cDNAs revealed that the small alpha' and the small A3 lacked 24 amino acid residues in the extension region and four amino acid residues in the hypervariable region, respectively, and that the large A4 did not have an insert corresponding to the difference in the electrophoretic mobility but Arg279 and Gln305 were replaced by glutamine and histidine, respectively, in the hypervariable region. These suggest that small differences even in the hypervariable region can affect the thermal stability, as well as the electrophoretic mobilities, of the proteins.

Amino Acid Sequence↗

New sequence polymorphisms in the outer loops of the JC polyomavirus major capsid protein (VP1) possibly associated with progressive multifocal leukoencephalopathy.

JC polyomavirus (JCPyV) causes progressive multifocal leukoencephalopathy (PML) in patients with decreased immune competence. To elucidate genetic changes in JCPyV associated with the pathogenesis of PML, multiple complete JCPyV DNA clones originating from the brains of three PML cases were established and sequenced. Although unique rearranged control regions occurred in all clones, a low level of nucleotide variation was also found in the coding region. In each case, a parental coding sequence was identified, from which variant coding sequences with nucleotide substitutions would have been generated. A comparison between the parental and variant coding sequences demonstrated that all 12 detected nucleotide substitutions gave rise to amino acid changes. Interestingly, seven of these changes were located in the surface loops of the major capsid protein (VP1). Finally, 16 reported VP1 sequences of PML-type JCPyV (i.e. derived from the brain or cerebrospinal fluid of PML patients) were compared with their genotypic prototypes, generated as consensus sequences of representative archetypal isolates belonging to the same genotypes; 13 VP1 proteins had amino acid changes in the surface loops. In contrast, VP1 proteins from isolates from the urine of immunocompetent and immunosuppressed patients rarely underwent mutations in the VP1 loops. The present findings suggest that PML-type JCPyV frequently undergoes amino acid substitutions in the VP1 loops. These polymorphisms should serve as a new marker for the identification of JCPyV isolates associated with PML. The biological significance of these mutations, however, remains unclear.

Adult↗

[A 65-year-old man with rigid-bradykinetic parkinsonism, vertical gaze palsy, difficulty of eye-lid opening, and marked pseudo-bulbar palsy].

We report a 65-year-old man with rigid-bradykinetic parkinsonism, vertical gaze palsy, difficulty in eye-lid opening, and marked pseudo-bulbar palsy. He felt difficulty of it, hand movement at 59 years old. When he was 60 years old, monotonous speech and slowness of movement appeared. He visited a neurologist who noted vertical gaze palsy, neck rigidity, and bradykinesia. He was diagnosed as progressive supranuclear palsy (PSP) and given 300 mg L-Dopa/Benserazide by the neurologist. This medication improved his rigidity and bradykinesia. At 62 years of the age, his eye-lids closed involuntary and it was difficult to open. In addition, he began to complain of wearing-off, autonomic symptoms, and dysphagia. Anti-parkinsonian drugs were increased, but his bradykinesia progressed. At 64 years of the age, he was admitted to the Neurology Service of Juntendo Hospital. On admission, he was alert and not demented. No aphasia, apraxia, or agnosia was noted. In the cranial nerves, upward and downward gaze were markedly restricted. His face was hypomimic and seborrhoic. It was difficult to swallow liquid or solid for him. No weakness was noted, but he walked in small steps with freezing and falling tendency to backward. Rigidity was noted on his extremities and stronger on his left side than right. Tremor was absent. Bradykinesia of his body and extremities was marked. No cerebellar ataxia was noted. Deep tendon reflexes were within normal range. Planter response was flexor bilaterally. Myerson's sign was noted. Sensory and autonomic function were normal. He was treated with L-Dopa, Pergolide, and Bromocriptine. However, these medications improved his bradykinesia and gait disturbance only slightly, dysphagia became progressively worse. He developed aspiration pneumonia when he was 65 years old and admitted to Juntendo Hospital. A large amount of sputum was aspirated from his trachea. Two days after from admission, he was found dead on his bed. He was discussed in a neurological CPC and the chief discussant arrived at a conclusion that the patient had progressive supranuclear palsy (PSP). Other differential diagnoses included Parkinson's disease, pallido-nigroluysian atrophy (PNLA), multiple system atrophy (MSA), and corticobasal degeneration(CBD). Many participants considered that PSP or PNLA was most likely. Post-mortem exmination revealed marked nigral neuronal loss and gliosis. The globus pallidus and the luysian body changed mildly. However, the frontal cortex was relatively spared, there were many ballooned neurons in the cortical layer. Other parts were spared. With sliver (Bodian and Gallyas-Braak) and anti-phsphorylated tau stain, abundant astrocytic plaques, neurofibrillary tangles, and argyrophilic threads on the frontal cortex, striatum, and substantia nigra were seen. There was no tufted astrocyte which was hallmark of diagnosis of PSP. In addition, several Lewy bodies were seen in the brainstem. Because astrocyte plaque was considered specific for pathology of CBD, the pathologist revealed that the pathological diagnosis of this patient was CBD. Nevertheless, discussion was focused on the relatively mild degeneration of the frontal cortex for CBD.

Aged↗

[The cognitive dysfunction in Parkinson's disease].

Parkinson's disease (PD) is a slowly progressive disorder which begins with motor symptoms. Several cognitive deficits can be observed in nondemented patients with PD during their history. The core symptom in the cognitive deficits in PD is the executive dysfunction. Neuropsychological tests such as Wisconsin Card Sorting Test, Trail Making Test are used to measure the degree of this dysfunction. Executive dysfunction is thought related to abnormalities in the dorsolateral prefrontal circuit which largely passes through the caudate nucleus. The dysfunction emerges as the pathology spreads to the nigrocaudate project corresponding to Hoehn & Yahr stage II-III. Effective therapy for cognitive dysfunction in PD remains elusive, however donepezil, Attention Process Training, Music therapy and Transcranial magnetic stimulation have been reported to have partial efficacy.

Cognition Disorders↗