A new species of Amolops from Thailand (Amphibia, Anura, Ranidae)

We describe a new species of torrent-dwelling ranid frog of the genus Amolops from western to peninsular Thailand. Amolops panhai, new species, differs from its congeners by the combination of: small body, males 31-34 mm, females 48-58 mm in snout-vent length; head narrower than long; tympanum distinct; vomerine teeth in short, oblique patches; first finger subequal to second; disc of first finger smaller than that of second, with circummarginal groove; no wide fringe of skin on third finger; toes fully webbed; outer metatarsal tubercle present; supratympanic fold present; dorsolateral fold indistinct; axillary gland present; horny spines on back, side of head and body, and chest absent; large tubercles on side of anus absent; glandular fold on ventral surface of tarsus absent; nuptial pad and paired gular pouches present in male; white band along the upper jaw extending to shoulder absent; larval dental formula 7(4-7)/3(1). This new species is the second anuran discovered which has a disjunct distribution around the Isthmus of Kra.     

Co-occurrence of mutations in both dystrophin- and androgen-receptor genes is a novel cause of female Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder. Here, we report a novel mechanism for the occurrence of DMD in females. In a Vietnamese DMD girl, conventional PCR amplification analysis disclosed a deletion of exons 12–19 of the dystrophin gene on Xp21.2, with a karyotype of 46, XY. Furthermore, a novel mutation in the androgen-receptor gene on Xq11.2-q12 was identified in this girl, which led to male pseudohermaphroditism. Co-occurrence of mutations of these two genes constitutes a novel mechanism underlying female DMD.     

Analysis of sialyltransferase-like proteins from Oryza sativa

Sialic acids are widely distributed among living creatures, from bacteria to mammals, but it has been commonly accepted that they do not exist in plants. However, with the progress of genome analyses, putative gene homologs of animal sialyltransferases have been detected in the genome of some plants. In this study, we cloned three genes from Oryza sativa (Japanese rice) that encode sialyltransferase-like proteins, designated OsSTLP1, 2, and 3, and analyzed the enzymatic activity of the proteins. OsSTLP1, 2, and 3 consist of 393, 396, and 384 amino acids, respectively, and each contains sequences similar to the sialyl motifs that are highly conserved among animal sialyltransferases. The recombinant soluble forms of OsSTLPs produced by COS-7 cells were analyzed for sialyltransferase-like activity. OsSTLP1 exhibited such activity toward the oligosaccharide Galbeta1,4GlcNAc and such glycoproteins as asialofetuin, alpha1-acid glycoprotein, and asialo-alpha1-acid glycoprotein; OsSTLP3 exhibited similar activity toward asialofetuin; and OsSTLP2 exhibited no sialyltransferase-like activity. The sialic acid transferred by OsSTLP1 or 3 was linked to galactose of Galbeta1,4GlcNAc through alpha2,6-linkage. This is the first report of plant proteins having sialyltransferase-like activity.     

Sphingosine-1-phosphate receptor agonists suppress concanavalin A-induced hepatic injury in mice

T cell-mediated immune responses play a critical role in a variety of liver injuries including autoimmune hepatitis. Injection of concanavalin A (Con A) into mice mimics the histological and pathological phenotype of T cell-mediated hepatitis. Recent advances in host immune control of organ transplantation include the development of sphingosine-1-phosphate (S1P) receptor agonists such as FTY720, which alter lymphocyte homing but do not suppress host general immunity. Herein we examined the effect of the new S1P receptor agonist KRP-203 on the Con A-induced liver damage model. In normal liver lymphocytes of BALB/c mice, both FTY720 and KRP203 promoted lymphocyte sequestering from the liver to secondary lymph nodes and significantly reduced the number of liver lymphocytes (p<0.05). Based on this observation, KRP203 was employed in the Con A-induced hepatitis model. KRP203 markedly reduced the number of CD4(+) lymphocytes that infiltrate Con A-treated liver (p<0.05) and successfully reduced serum transaminase elevation (p=0.017), therefore protecting mice from Con A-induced liver injury. Interestingly this homing modulation less occurs in natural hepatic T cell homing through the chemokine receptor, CXCR4. Therefore, S1P receptor agonists preferentially target CXCR4(+)CD4(+) peripheral blood T lymphocytes and suppress the occurrence of Con A-induced hepatitis, suggesting their therapeutic usefulness against T cell-mediated hepatic injury.     

Functional expression of thiocyanate hydrolase is promoted by its activator protein, P15K

Thiocyanate hydrolase (SCNase) is a cobalt-containing enzyme with a post-translationally modified cysteine ligand, gammaCys131-SO(2)H. When the SCNase alpha, beta and gamma subunits were expressed in Escherichia coli, the subunits assembled to form a hetero-dodecamer, (alphabetagamma)(4), like native SCNase but exhibited no catalytic activity. Metal analysis indicated that SCNase was expressed as an apo-form irrespective of the presence of cobalt in the medium. On the contrary, SCNase co-expressed with P15K, encoded just downstream of SCNase genes, in cobalt-enriched medium under the optimized condition (SCNase((+P15K))) possessed 0.86 Co atom/alphabetagamma trimer and exhibited 78% of the activity of native SCNase. SCNase((+P15K)) showed a UV-Vis absorption peak characteristic of the SCNase cobalt center. About 70% of SCNase((+P15K)) had the gammaCys131-SO(2)H modification. These results indicate that SCNase((+P15K)) is the active holo-SCNase. P15K is likely to promote the functional expression of SCNase probably by assisting the incorporation of cobalt ion.     

Additive roles of XPA and MSH2 genes in UVB-induced skin tumorigenesis in mice

We have made xeroderma pigmentosum group A gene (XPA)-knockout mice (XPA(-/-) mice). The XPA(-/-) mice had no detectable activity for nucleotide excision repair (NER) and showed a high incidence of UVB-induced skin tumorigenesis. We have also found that cell lines derived from skin cancers in UVB-irradiated XPA(-/-) mice become tolerant to UV-irradiation and showed abnormal UV-induced cell cycle checkpoints and decreased mismatch repair (MMR) activity. These results suggested that the MMR-downregulation may help cells escape killing by UV-irradiation and thus MMR-deficient clones are selected for during the tumorigenic transformation of XPA(-/-) cells. In this report, we examined whether the incidence of UVB-induced skin tumorigenesis is enhanced in XPA(-/-)MSH2(-/-), XPA(-/-) and MSH2(-/-) mice when compared with that in wild-type mice. Our results indicate that the MSH2-deficiency caused a high incidence of spontaneous and UVB-induced skin tumorigenesis and the XPA and MSH2 genes have additive roles in the UV-induced skin tumorigenesis.     

The N-terminal replacement of an olfactory receptor for the development of a yeast-based biomimetic odor sensor

For the development of a biomimetic odor-sensing system, we investigated the effects of replacing the N-terminus of an olfactory receptor (OR) on its functional expression in the budding yeast, Saccharomyces cerevisiae. Using the mouse olfactory receptor OR226 (mOR226), three types of chimeric ORs were constructed by replacing N-terminal regions of mOR226 with the corresponding regions of the rat I7 receptor, which is known to be functionally expressed in yeast. The replacement of the N-terminal region of mOR226 dramatically affected the expression and localization of the receptor and improved the sensing ability of the yeast cells for the odorant. Furthermore, the replacement of the endogenous yeast G-protein α subunit (Gpa1) by the OR-specific G(olf) drastically elevated the odorant-sensing ability of the yeast cells and caused the cells to display a dose-dependent responsiveness to the odorant. Because of the suitability of yeast cells for screening large-scale libraries, the strategy presented here would be useful for the establishment of advanced biomimetic odor-sensing systems.     

Exogenous and endogenous ghrelin counteracts GLP-1 action to stimulate cAMP signaling and insulin secretion in islet β-cells

We studied interactive effects of insulinotropic GLP-1 and insulinostatic ghrelin on rat pancreatic islets. GLP-1 potentiated glucose-induced insulin release and cAMP production in isolated islets and [Ca(2+)](i) increases in single β-cells, and these potentiations were attenuated by ghrelin. Ghrelin suppressed [Ca(2+)](i) responses to an adenylate cyclase activator forskolin. Moreover, GLP-1-induced insulin release and cAMP production were markedly enhanced by [D-lys(3)]-GHRP-6, a ghrelin receptor antagonist, in isolated islets. These results indicate that both exogenous and endogenous islet-derived ghrelin counteracts glucose-dependent GLP-1 action to increase cAMP production, [Ca(2+)](i) and insulin release in islet β-cells, positioning ghrelin as a modulator of insulinotropic GLP-1.     

Effect of photoperiod and temperature on the induction of diapause in a Japanese strain of <Emphasis Type="Italic">Aphidoletes aphidimyza</Emphasis> (Diptera: Cecidomyiidae)

The aphidophagous gall midge Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae), a dominant natural enemy of aphids, has been used as a biological control agent in many countries to control aphids in greenhouses. As developmental arrest in diapause lowers the effectiveness of natural enemies, we studied the effect of photoperiod and temperature on the incidence of diapause in a Japanese strain of A. aphidimyza by examining diapause induction under different day-length conditions in the laboratory. The critical day length for diapause induction was determined to be 12.7 h at 20°C. Diapause incidence was completely prevented at 30°C even though the photoperiod used was 11L13D. We also examined diapause induction under changing temperature conditions while maintaining the critical day length (12.7L11.3D). Diapause incidence was 100% in both field and greenhouse conditions under alternating temperatures of 20/16 or 25/16°C while the critical day length of 12.7 h was maintained. The Japanese strain of A. aphidimyza was sensitive to diapause entry from the first to the third noncocooned instar larval stages. Its eggs do not seem to be sensitive to diapause induction. Our results suggest that constant short-day conditions for at least four days are needed to induce diapause in the Japanese strain of A. aphidimyza.