Environmental DNA monitoring method of the commercially important and endangered fish Gnathopogon caerulescens

Limnology - Gnathopogon caerulescens is an endangered but commercially important fish in Lake Biwa, Japan. The population size of G. caerulescens has drastically reduced in the past decades, and...     

Sequence- and seed-structure-dependent polymorphic fibrils of alpha-synuclein

Synucleinopathies comprise a diverse group of neurodegenerative diseases including Parkinson's disease (PD), dementia with Lewy bodies, and multiple system atrophy. These share a common pathological feature, the deposition of alpha-synuclein (a-syn) in neurons or oligodendroglia. A-syn is highly conserved in vertebrates, but the primary sequence of mouse a-syn differs from that of human at seven positions. However, structural differences of their aggregates remain to be fully characterized. In this study, we found that human and mouse a-syn aggregated in vitro formed morphologically distinct amyloid fibrils exhibiting twisted and straight structures, respectively. Furthermore, we identified different protease-resistant core regions, long and short, in human and mouse a-syn aggregates. Interestingly, among the seven unconserved amino acids, only A53T substitution, one of the familial PD mutations, was responsible for structural conversion to the straight-type. Finally, we checked whether the structural differences are transmissible by seeding and found that human a-syn seeded with A53T aggregates formed straight-type fibrils with short protease-resistant cores. These results suggest that a-syn aggregates form sequence-dependent polymorphic fibrils upon spontaneous aggregation but become seed structure-dependent upon seeding.     

Delayed sleep/wake rhythm and excessive daytime sleepiness correlate with decreased daytime brain activity during cognitive task in university students

Insufficient sleep and irregular sleep/wake rhythm are common problems among university students. We investigated the effect of sleep/wake rhythm and excessive daytime sleepiness (EDS) on the cortical oxygenation as measured by near-infrared spectroscopy (NIRS) and cognitive performance in university students. Peak- and integral values by a word fluency task were measured with NIRS. EDS was evaluated by the Epworth sleepiness scale (ESS), and performance function was evaluated using N-back task. Peak cerebral oxygenation was significantly correlated with ESS, bedtime, wake-up time, and median time of sleep. Accuracy on 2-back task was significantly correlated with integral value. Peak- and integral values were significantly lower, and bedtime and median time of sleep were significantly delayed in the EDS group than in the non-EDS group. EDS accompanied by delayed sleep/wake rhythm and short sleep duration may play an important role in decreasing daytime brain activity and cognitive performance.     

Occurrence and subcellular location of NADH- and NADPH-linked aquacobalamin reductases in human liver

1. Both activities of NADH- and NADPH-linked aquacobalamin reductases were found in some human tissues, liver, kidney pancreas, heart, spleen, lung, cerebrum, cerebellum, adrenal glands, stomach, duodenum, jejunum, ileum, colon and bone marrow. 2. Human liver contained both enzymes with higher specific activities than any other tissues. 3. The liver NADH-linked enzyme was distributed in both mitochondrial (approx. 60%) and microsomal (40%) fractions; similar to the distribution of the NADPH-linked enzyme, but of which 40% activity was found in the mitochondria and the remaining activity was recovered in the microsomes. 4. The results suggest that the synthetic systems of the cobalamin coenzymes occur in both mitochondria and microsomes of human liver.     

EGF family ligand-dependent phenotypic modulation of smooth muscle cells through EGF receptor

The phenotypic modulation of smooth muscle cells (SMCs) is closely associated with the development and progression of various SMC diseases. We investigated the molecular mechanism of phenotypic modulation triggered by EGF family ligands using a primary culture system of differentiated SMCs. Among four EGF-receptor (EGFR) family members, the EGFR was solely activated by EGF, heparin-binding EGF (HB-EGF), transforming growth factor alpha (TGF alpha), epiregulin (ER), and betacellulin (BTC), resulting in induction of phenotypic modulation of SMCs. This effect was mediated through the coordinated activation of the extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38MAPK) pathways. These results suggest that EGF family ligand- and EGFR-triggered signaling pathways are critically involved in the phenotypic modulation of SMCs.     

Theoretical studies of the ATP hydrolysis mechanism of myosin

The ATP hydrolysis mechanism of myosin was studied using quantum chemical (QM) and molecular dynamics calculations. The initial model compound for QM calculations was constructed on the basis of the energy-minimized structure of the myosin(S1dc)-ATP complex, which was determined by molecular mechanics calculations. The result of QM calculations suggested that the ATP hydrolysis mechanism of myosin consists of a single elementary reaction in which a water molecule nucleophilically attacked gamma-phosphorus of ATP. In addition, we performed molecular dynamics simulations of the initial and final states of the ATP hydrolysis reaction, that is, the myosin-ATP and myosin-ADP.Pi complexes. These calculations revealed roles of several amino acid residues (Lys185, Thr186, Ser237, Arg238, and Glu459) in the ATPase pocket. Lys185 maintains the conformation of beta- and gamma-phosphate groups of ATP by forming the hydrogen bonds. Thr186 and Ser237 are coordinated to a Mg(2+) ion, which interacts with the phosphates of ATP and therefore contributes to the stabilization of the ATP structure. Arg238 and Glu459, which consisted of the gate of the ATPase pocket, retain the water molecule acting on the hydrolysis at the appropriate position for initiating the hydrolysis.     

Nonsense and frameshift mutations in ZFHX1B, encoding Smad-interacting protein 1, cause a complex developmental disorder with a great variety of clinical features

Mutations in ZFHX1B, encoding Smad-interacting protein 1 (SIP1), have been recently reported to cause a form of Hirschsprung disease (HSCR). Patients with ZFHX1B deficiency typically show mental retardation, delayed motor development, epilepsy, microcephaly, distinct facial features, and/or congenital heart disease, in addition to the cardinal form of HSCR. To investigate the breadth of clinical variation, we studied DNA samples from six patients with clinical profiles quite similar to those described elsewhere for ZFHX1B deficiency, except that they did not have HSCR. The results showed the previously reported R695X mutation to be present in three cases, with three novel mutations-a 2-bp insertion (760insCA resulting in 254fs262X), a single-base deletion (270delG resulting in 91fs107X), and a 2-bp deletion (2178delTT resulting in 727fs754X)-newly identified in the other three. All mutations occurred in one allele and were de novo events. These results demonstrate that ZFHX1B deficiency is an autosomal dominant complex developmental disorder and that individuals with functional null mutations present with mental retardation, delayed motor development, epilepsy, and a wide spectrum of clinically heterogeneous features suggestive of neurocristopathies at the cephalic, cardiac, and vagal levels.     

Reclassification of Pichia scaptomyzae and Pichia galeiformis

Based on the base composition of nuclear DNA and DNA/DNA hybridization, Pichia galeiformis IFO 10718T was reclassified as a synonym of Pichia manshurica, and Pichia scaptomyzae IFO 1073 1T was confirmed to be a synonym of Pichia membranifaciens. Comparison of 18S rRNA gene sequences indicated that IFO 10731T (P. scaptomyzae) is identical to P. membranifaciens IFO 10215T and IFO 10725, and IFO 10718T (P. galeiformis) is identical to P. manshurica IFO 10726T. These data were consistent with the view that P scaptomyzae and P membranifaciens should be conspecific, as should P. galeiformis and P manshurica. Variation among 26S rRNA gene domain D1/D2 sequences from three P membranifaciens strains indicated that this species encompasses a genetically heterogeneous population.     

Overexpression of the Wiskott-Aldrich syndrome protein N-terminal domain in transgenic mice inhibits T cell proliferative responses via TCR signaling without affecting cytoskeletal rearrangements

Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by thrombocytopenia with small platelets, severe eczema, and recurrent infections due to defects in the immune system. The disease arises from mutations in the gene encoding the WAS protein (WASP), which plays a role as an adaptor molecule in signal transduction accompanied by cytoskeletal rearrangement in T cells. To investigate the functional domain of WASP, we developed transgenic mice overexpressing the WASP N-terminal region (exon 1-5) including the Ena/VASP homology 1 (pleckstrin homology/WASP homology 1) domain, in which the majority of mutations in WAS patients have been observed. WASP transgenic mice develop and grow normally under the specific pathogen-free environment, and showed normal lymphocyte development. However, proliferative responses and cytokine production induced by TCR stimulation were strongly inhibited in transgenic mice, whereas Ag receptor capping and actin polymerization were normal. These findings suggest that overexpressed Ena/VASP homology 1 (pleckstrin homology/WASP homology 1) domain of WASP inhibits the signaling from TCR without coupling of cytoskeletal rearrangement. WASP transgenic mice shown here could be valuable tools for further understanding the WASP-mediated processes.