New Plant Growth Retardants

Phosphatidylcholine hydroperoxide was assayed with phospholipase A₂ and glutathione peroxidase, based on fluorometry with N(9-acridinyl)maleimide. The hydroperoxide was poorly reduced by glutathione peroxidase, and was converted by phospholipase A₂ into reactable forms of glutathione peroxidase. A linear relationship was found between hydroperoxides assayed by the enzymatic and chemical methods in the range from 0.05 to 5.0 nmol with 0.5 to 1.5 mg of the sample. The hydroperoxides of fatty acids, triacylglycerol and phosphatidylcholine were assayed in their mixtures and in commercial lecithins.     

Involvement of ASK1–p38 pathway in the pathogenesis of diabetes triggered by pancreatic ß cell exhaustion

Background

Diabetes mellitus is characterized by high blood glucose levels. Pancreatic ß cell death contributes to type 1 and type 2 diabetes. Akita mice, which harbor a human permanent neonatal diabetes-linked mutation (Cys96Tyr) in the insulin gene, are well established as an animal model of diabetes caused by pancreatic ß cell exhaustion. Mutant Insulin 2 protein (Ins2^C96Y) induces endoplasmic reticulum (ER) stress and pancreatic ß cell death in Akita mice, although the molecular mechanism of Ins^C96Y-induced cell death remains unclear.

Methods

We investigate the mechanisms of Ins2^C96Y-induced pancreatic ß cell death in vitro and in vivo, using p38 inhibitor (SB203580), MIN6 cell (pancreatic ß cell line), Akita mice and apoptosis signal-regulating kinase 1 (ASK1) knockout mice.

Results

The expression of Ins^C96Y activated the ASK1–p38 pathway. Deletion of ASK1 mitigated Ins^C96Y-induced pancreatic ß cell death and delayed the onset of diabetes in Akita mice. Moreover, p38 inhibitor suppressed Ins^C96Y-induced MIN6 cell death.

Conclusions

These findings suggest that ER stress-induced ASK1–p38 activation, which is triggered by the accumulation of Ins^C96Y, plays an important role in the pathogenesis of diabetes.

General significance

Pancreatic ß cell death caused by insulin overload appears to be involved in the pathogenesis of type 1 and type 2 diabetes. Inhibition of the ASK1–p38 pathway may be an effective therapy for various types of diabetes.     

Quantitative analysis of cutaneous malassezia in atopic dermatitis patients using real-time PCR

We quantified the cutaneous Malassezia in patients with atopic dermatitis using a real-time PCR assay. Seven to 12 times more Malassezia colonized the head and neck compared to the trunk or limbs, and the species M. globosa and M. restricta accounted for approximately 80% of all Malassezia colonization at any body site.     

Spectral sensitivity of melanophores of a freshwater teleost, Zacco temmincki

1. The melanophores of a freshwater teleost, Zacco temmincki, responded to changes in illumination: in darkness the melanophores induced a melanosome aggregation and when subjected to light they caused a melanosome dispersion. 2. Using monochromatic light, the spectral sensitivity of the melanophores was examined. 3. The melanophores showed a different sensitivity to light between 400 and 600 nm with a maximum at about 525 nm. 4. The action spectrum closely resembled a porphyropsin absorbance curve, suggesting a porphyropsin or similar photopigment is active in the melanophore light response of Zacco temmincki.     

Conserved and divergent expression of T-box genes Tbx2-Tbx5 in Xenopus

We report here the identification of four members of T-box family genes, Xltbx2-Xltbx5, in Xenopus. Two of them are probable pseudovariant genes of XTbx5 and ET, a putative Xenopus ortholog of Tbx3. We compared their expression patterns in both embryos and limbs. In embryos, expression of Xltbx2 and Xltbx3 showed novel diversities, such as Xltbx2 in the neural crest cells and Xltbx3 in the ventral spinal cord, together with mutual similarities in the following regions: dorsal retina, proctoderm, lateral line organ, cement gland and cranial ganglia. The patterns in limbs were highly conserved with mouse and chick orthologs, including the limb-type specific expression of Xltbx4 and Xltbx5. In addition, RT-PCR analysis showed that they are expressed weakly even in adult limbs as previously reported in the newt.     

Babesia bovis: subcellular localization of host erythrocyte membrane components during their asexual growth

In the present study, the subcellular localization of the host red blood cell (RBC) membrane components, the alpha2-3-linked sialic acid (SA) residues and the lipid bilayer, was observed during the asexual growth of Babesia bovis using two erythrocyte probes, the SA-specific lectin (MALII) and the lipophilic fluorescent (PKH2) probes, respectively. In confocal laser scanning microscopy with MALII, the SA residues on the surface of parasitized RBCs appeared to accumulate into the intracellular parasites as the parasites matured as well as to remain on the surface of extracellular parasites. Furthermore, when PKH2-labeled RBCs were infected with B. bovis, PKH2 signals were also observed around both the intracellular and the extracellular parasites, similarly to the results of MALII. These results indicated that the components derived from the host erythrocyte membrane are incorporated into the intracellular parasites during their asexual growth within the parasitized RBC, suggesting the possible formation of a parasitophorous vacuole-based network or a parasite surface coat.     

Metamorphic change in EP37 expression: members of the βγ-crystallin superfamily in newt

 EP37 is an epidermis-specific protein found in the developing embryo of the Japanese newt, Cynops pyrrhogaster. Our previous study predicted the presence of genes homologous to EP37, which show temporary shared expression at the turn of metamorphosis. In this study, we isolated and characterized three cDNAs encoding novel EP37 homologues; two from the skin of an adult newt and the other from swimming larva. Conceptual translation of the open reading frames of these cDNAs predicted proteins carrying βγ-crystallin motifs and putative calcium-binding sites, both of which are features shared by the originally identified EP37 (EP37L1), as well as a spore coat protein of Myxococcus xanthus, protein S. Immunoblot analyses and immunohistochemical studies indicated that two of the EP37 proteins, EP37L1 and EP37L2, are exclusively expressed in the epidermis (skein cells) including the figures of Eberth at premetamorphic stages. During and after metamorphosis, the expression of EP37 proteins was mainly observed in cutaneous glands, and a molecular transition to the adult types of EP37, EP37A1 and EP37A2, occurred. These observations suggest that EP37 proteins play an important role in construction of integumental tissues and adaptation to the aquatic or amphibious environment. Received: 6 September 1996 / Accepted: 30 October 1996