FINE STRUCTURE OF THE OCTOPUS RETINA

The fine structure of the visual and the supporting cells and of the blood capillaries in the octopus retina is described. Lamellated structures contained in the proximal segment of the visual cell consist of compact arrays of dense membranes each of which is quintuple-layered and divides at its margins into two thinner sheets or membranes which are connected directly with the agranular or granular endoplasmic reticulum. Proximal to the deeper extremities of the rhabdomeres, the lateral plasma membranes of two adjoining visual cells contact each other forming a quintuple-layered compound membrane, which results in occlusion of the intercellular space. The central layer of the compound membrane is of high density, so that the membrane, as a whole, appears to be a single thick layer at low magnifications. The supporting cells are connected with the neighboring visual cells by two types of junctions. Long slender processes extend from the supporting cells to the surface of the retina through narrow spaces among the distal segments of the visual cells. The capillary endothelial cells are characterized by luminal surfaces irregularly contoured and by lateral surfaces elaborately interdigitated. The functional significance of the close contact between adjoining visual cells is discussed.     

Structural basis for the specificity and catalysis of human Atg4B responsible for mammalian autophagy

Reversible modification of Atg8 with phosphatidylethanolamine is crucial for autophagy, the bulk degradation system conserved in eukaryotic cells. Atg4 is a novel cysteine protease that processes and deconjugates Atg8. Herein, we report the crystal structure of human Atg4B (HsAtg4B) at 1.9-A resolution. Despite no obvious sequence homology with known proteases, the structure of HsAtg4B shows a classical papain-like fold. In addition to the papain fold region, HsAtg4B has a small alpha/beta-fold domain. This domain is thought to be the binding site for Atg8 homologs. The active site cleft of HsAtg4B is masked by a loop (residues 259-262), implying a conformational change upon substrate binding. The structure and in vitro mutational analyses provide the basis for the specificity and catalysis of HsAtg4B. This will enable the design of Atg4-specific inhibitors that block autophagy.     

Total synthesis of aurachins C,D, and L,and a structurally simplified analog of aurachin C

The quinoline antibiotics aurachins C, D, and L, and a structurally simplified analog of aurachin C were synthesized from 1-(2-nitrophenyl)butane-1,3-dione via reductive cyclizations of δ-nitro ketone intermediates, with zinc or iron as key steps. The results of antimicrobial tests indicate that the N-hydroxyquinolone nucleus mimics the electron carrier in the respiratory chain more strongly than the quinoline N-oxide nucleus.     

Psychiatrists' Attitudes toward Metabolic Adverse Events in Patients with Schizophrenia

Background

There is growing concern about the metabolic abnormalities in patients with schizophrenia.

Aims

The aim of this study was to assess the attitudes of psychiatrists toward metabolic adverse events in patients with schizophrenia.

Method

A brief questionnaire was constructed to cover the following broad areas: the psychiatrists'' recognition of the metabolic risk of antipsychotic therapy, pattern of monitoring patients for physical risks, practice pattern for physical risks, and knowledge of metabolic disturbance. In March 2012, the questionnaire was mailed to 8,482 psychiatrists who were working at hospitals belonging to the Japan Psychiatric Hospitals Association.

Results

The overall response rate was 2,583/8,482 (30.5%). Of the respondents, 85.2% (2,200/2,581) reported that they were concerned about prescribing antipsychotics that have a risk of elevating blood sugar; 47.6% (1,201/2,524) stated that their frequency of monitoring patients under antipsychotic treatment was based on their own experiences; and only 20.6% (5,22/2,534) of respondents answered that the frequency with which they monitored their patients was sufficient to reduce the metabolic risks.

Conclusions

Psychiatrists practicing in Japan were generally aware and concerned about the metabolic risks for patients being treated with antipsychotics. Although psychiatrists should monitor their patients for metabolic abnormalities to balance these risks, a limited number of psychiatrists answered that the frequency with which they monitored patients to reduce the metabolic risks was sufficient. Promotion of the best practices of pharmacotherapy and monitoring is needed for psychiatrists treating patients with schizophrenia.     

Molecular heterogeneity of heat-stable toxin-producing and non-producing Escherichia coli O25 strains isolated in Japan

Escherichia coli O25 strains that produce heat-stable toxin (ST) have been recently isolated in Japan, and epidemiological study of this type of enterotoxigenic E. coli is required. In this study the heterogeneity of 16 ST-producing and non-producing strains of E. coli O25 was investigated. All eight ST-producing strains were shown to have STIb gene, and seven of them had similar profiles of plasmids, ladder-banding of LPS in SDS-polyacrylamide gel electrophoresis, and chromosomal DNA digestions in pulsed-field gel electrophoresis (PFGE). In contrast, ST-non-producing strains were more heterogeneous in all parameters examined. PFGE of the digested chromosomal DNA with several restriction enzymes was proved to be an effective procedure to compare the closely related strains of E. coli O25.     

Biochemical and structural characterization of an endoplasmic reticulum-localized late embryogenesis abundant (LEA) protein from the liverwort Marchantia polymorpha

Late embryogenesis abundant (LEA) proteins, which accumulate to high levels in seeds during late maturation, are associated with desiccation tolerance. A member of the LEA protein family was found in cultured cells of the liverwort Marchantia polymorpha; preculture treatment of these cells with 0.5 M sucrose medium led to their acquisition of desiccation tolerance. We characterized this preculture-induced LEA protein, designated as MpLEA1. MpLEA1 is predominantly hydrophilic with a few hydrophobic residues that may represent its putative signal peptide. The protein also contains a putative endoplasmic reticulum (ER) retention sequence, HEEL, at the C-terminus. Microscopic observations indicated that GFP-fused MpLEA1 was mainly localized in the ER. The recombinant protein MpLEA1 is intrinsically disordered in solution. On drying, MpLEA1 shifted predominantly toward α-helices from random coils. Such changes in conformation are a typical feature of the group 3 LEA proteins. Recombinant MpLEA1 prevented the aggregation of α-casein during desiccation–rehydration events, suggesting that MpLEA1 exerts anti-aggregation activity against desiccation-sensitive proteins by functioning as a “molecular shield”. Moreover, the anti-aggregation activity of MpLEA1 was ten times greater than that of BSA or insect LEA proteins, which are known to prevent aggregation on drying. Here, we show that an ER-localized LEA protein, MpLEA1, possesses biochemical and structural features specific to group 3 LEA proteins.     

Molecular analysis of X-linked ichthyosis in Japan

BACKGROUND: X-linked ichthyosis (XLI) is an inherited skin disorder caused by a deficiency of steroid sulfatase (STS). The gene and protein of STS were examined in 19 Japanese patients with XLI. RESULTS: In Western blotting analysis, no cross-reacting peptide was detected in the patients' placenta, although a single band (63 kD) corresponding to STS in a normal subject was observed. Southern blotting was performed using EcoRI digests of cellular DNA from 13 XLI patients and full-length human STS cDNA as a probe. Normal males had bands of 20, 15, 10, 9.0, 6.1, 4.2, 2.6, and 1.5 kb. Twelve of the 19 patients had only 20- and 1.5-kb bands. Only one patient had the same band pattern as that of normal males. The STS gene was analyzed by PCR in 6 of the 19 patients. PCR amplification products were sequenced to analyze the STS gene. Two cases with one-base change in the STS gene and variation in amino acids H444R and E560P were found. Mutant STS cDNA was transfected into COS-1 cells and the STS enzyme activity was assayed. The enzyme activities were less than the minimum detection value of the detection system. CONCLUSIONS: These results suggest that XLI is mainly caused by an extensive deletion of the STS gene and that the PCR method is useful for detection of STS point mutations.     

Morphology and molecular phylogeny of the marine diatom genus Nagumoea (Bacillariophyceae) from Japan

The canal-bearing diatom genus Nagumoea, described based on only morphological evidence, was tentatively assigned to the order Bacillariales, although its phylogenetic position remained unclear. Because three isolates of Nagumoea (SK002, SK024 and SK053) were successfully established from Japanese coasts, we performed their morphological observations and molecular phylogenetic analyses to discuss the phylogeny and taxonomic position of this genus. Strains SK002 and SK024 were identified as Nagumoea africana, whereas SK053 conformed with Nagumoea serrata. There was high interspecific divergence between N. africana and N. serrata in the rbcL sequences (8.03–8.17%), indicating their distinctness. Furthermore, intraspecific variations were detected within N. africana (2.35%) in the rbcL, implying its cryptic diversity. The maximum likelihood and Bayesian phylogenetic trees inferred from the plastid rbcL, psbC and nuclear 18S rDNA genes recovered Nagumoea as monophyletic with strong statistical support and embedded within an unresolved, poorly supported lineage containing Achnanthes, Craspedostauros, Staurotropis and Undatella in the canal-bearing order Bacillariales (= the family Bacillariaceae). Although the constrained tree based on the monophyly of Nagumoea and the other canal-bearing clade (Surirellales and Rhopalodiales) was statistically rejected by the topology tests, the phylogenetic position of Nagumoea with other Bacillarialean members remains equivocal. The possession of two plastids positioned fore and aft, observed in the present study, and lack of keel, typical of the Bacillariales, indicate the possibility of Nagumoea being part of the ingroup of the Bacillariales or its closely related outgroup.     

Identification of IL-18 and Th17 cells in salivary glands of patients with Sjögren's syndrome, and amplification of IL-17-mediated secretion of inflammatory cytokines from salivary gland cells by IL-18

IL-18 is a proinflammatory cytokine and plays an important pathogenic role in inflammatory and autoimmune disorders. IL-17 is also a proinflammatory cytokine and IL-17-secreting Th17 cells are involved in autoimmunity. However, the pathological roles of IL-18 and Th17 cells in Sj?gren's syndrome (SS) remain to be elucidated. This study showed that the expression of IL-18 was detected in acinar cells, intraducts, and CD68(+) macrophages in salivary glands of SS patients, but not in those of healthy subjects or patients with chronic graft-vs-host disease, by immunohistochemistry, and immunoblot analysis revealed that 24-kDa precursor form of IL-18 (proIL-18) and 18-kDa mature IL-18 were detected in SS salivary glands. The majority of the infiltrating cells in the salivary glands of SS patients were CD4(+) T cells, and CD8(+) T cells were infiltrated to a lesser extent. The predominant expression of IL-17 was found in infiltrating CD4(+) T cells, whereas a small number of infiltrating CD8(+) T cells expressed IL-17. Human salivary gland HSY and acinar AZA3 cells constitutively expressed proIL-18 and caspase-1, and a calcium ionophore A23187 induced the secretion of IL-18 from the cells. HSY and AZA3 cells expressed IL-18R and IL-17R on the cell surface, and IL-18 amplified the secretion of IL-6 and IL-8 that were induced by low amounts of IL-17. Primary salivary gland cells from normal subjects partially confirmed these findings. These results suggest that IL-18 and Th17 cells detected in the salivary glands in SS patients are associated with the pathogenesis of SS in the salivary glands.     

Correlation between X-chromosome inactivation and cell differentiation in female preimplantation mouse embryos

By means of a cytological method involving BrdU incorporation and acridine orange fluorescence staining in combination with embryo manipulation, we studied X-chromosome activity in female preimplantation mouse embryos with special reference to the correlation between X-chromosome inactivation and cell differentiation. There was no sign of asynchronous replication between the two X chromosomes from the one-cell to intermediate blastocyst stage. The allocyclic X chromosome, first detected in late blastocysts, was paternal in origin, mostly replicating early in the S phase and limited to the trophectoderm. Subsequent X-chromosome inactivation occurring in the primary endoderm was also characterized by the involvement of the paternal X and early replication. Both X chromosomes continued to replicate synchronously in the embryonic ectoderm or epiblast at this stage. It was evident that overt cell differentiation preceded the appearance of the asynchronously replicating X chromosome in the trophectoderm and primary endoderm. This finding seems to support the view that cell differentiation is an important correlate of X-chromosome inactivation.