Rostral paraxial mesoderm regulates refinement of the eye field through the bone morphogenetic protein (BMP) pathway

The eye field is initially a large single domain at the anterior end of the neural plate and is the first indication of optic potential in the vertebrate embryo. During the course of development, this domain is subject to interactions that shape and refine the organogenic field. The action of the prechordal mesoderm in bisecting this single region into two bilateral domains has been well described, however the role of signalling interactions in the further restriction and refinement of this domain has not been previously characterised. Here we describe a role for the rostral cephalic paraxial mesoderm in limiting the extent of the eye field. The anterior transposition of this mesoderm or its ablation disrupted normal development of the eye. Importantly, perturbation of optic vesicle development occurred in the absence of any detectable changes in the pattern of neighbouring regions of the neural tube. Furthermore, negative regulation of eye development is a property unique to the rostral paraxial mesoderm. The rostral paraxial mesoderm expresses members of the bone morphogenetic protein (BMP) family of signalling molecules and manipulation of endogenous BMP signalling resulted in abnormalities of the early optic primordia.     

Screening the V2R-type putative odorant receptor gene repertoire in bitterling Tanakia lanceolata

To study evolution of dinucleotide simple sequence repeats (diSSRs) we searched recently available mammalian genomes for UTR-localized diSSRs with conserved upstream flanking sequences (CFS). There were 252 reported Homo sapiens genes containing the repeats (AC)n, (GT)n, (AG)n or (CT)n in their UTRs including 22 (8.7%) with diSSR-upstream flanking sequences conserved comparing divergent mammalian lineages represented by Homo sapiens and the marsupial, Monodelphis domestica. Of these 22 genes, 19 had known functions including 18 (95%) that proved critical for mammalian nervous systems (Fishers exact test, P<0.0001). The remaining gene, Cd2ap, proved critical for development of kidney podocytes, cells that have multiple similarities to neurons. Gene functions included voltage and chloride channels, synapse-associated proteins, neurotransmitter receptors, axon and dendrite pathfinders, a NeuroD potentiator and other neuronal activities. Repeat length polymorphism was confirmed for 68% of CFS diSSRs even though these repeats were nestled among highly conserved sequences. This finding supports a hypothesis that SSR polymorphism has functional implications. A parallel study was performed on the self-complementary diSSRs (AT)n and (GC)n. When flanked by conserved sequences, the self-complementary diSSR (AT)n was also associated with genes expressed in the developing nervous system. Our findings implicate functional roles for diSSRs in nervous system development.     

The historical biogeography of the freshwater knifefishes using mitogenomic approaches: A Mesozoic origin of the Asian notopterids (Actinopterygii: Osteoglossomorpha)

The continental distributions of freshwater fishes in the family Notopteridae (Osteoglossomorpha) across Africa, India, and Southeast Asia constitute a long standing and enigmatic problem of freshwater biogeography. The migrational pathway of the Asian notopterids has been discussed in light of two competing schemes: the first posits recent transcontinental dispersal while the second relies on distributions being shaped by ancient vicariance associated with plate-tectonic events. In this study, we determined complete mitochondrial DNA sequences from 10 osteoglossomorph fishes to estimate phylogenetic relationships using partitioned Bayesian and maximum likelihood methods and divergence dates of the family Notopteridae with a partitioned Bayesian approach. We used six species representing the major lineages of the Notopteridae and seven species from the remaining osteoglossomorph families. Fourteen more-derived teleosts, nine basal actinopterygians, two coelacanths, and one shark were used as outgroups. Phylogenetic analyses indicated that the African and Asian notopterids formed a sister group to each other and that these notopterids were a sister to a clade comprising two African families (Mormyridae and Gymnarchidae). Estimated divergence time between the African and Asian notopterids dated back to the early Cretaceous when India–Madagascar separated from the African part of Gondwanaland. Thus, estimated time of divergence based on the molecular evidence is at odds with the recent dispersal model. It can be reconciled with the geological and paleontological evidence to support the vicariance model in which the Asian notopterids diverged from the African notopterids in Gondwanaland and migrated into Eurasia on the Indian subcontinent from the Cretaceous to the Tertiary. However, we could not exclude an alternative explanation that the African and Asian notopterids diverged in Pangea before its complete separation into Laurasia and Gondwanaland, to which these two lineages were later confined, respectively.     

Localization of CD26/DPPIV in nucleus and its nuclear translocation enhanced by anti-CD26 monoclonal antibody with anti-tumor effect

Background  

CD26 is a type II, cell surface glycoprotein known as dipeptidyl peptidase (DPP) IV. Previous studies have revealed CD26 expression in T cell leukemia/lymphoma and malignant mesothelioma, and an inhibitory effect of anti-CD26 monoclonal antibody (mAb) against the growth of CD26+ cancer cells in vitro and in vivo. The function of CD26 in tumor development is unknown and the machinery with which the CD26 mAb induces its anti-tumor effect remains uncharacterized.     

Isolation and characterization of 12 microsatellite loci for cross-species amplification in the cyprinid gudgeons Squalidus chankaensis and S. japonicus

Twelve dinucleotide markers were successfully isolated and characterized from a microsatellite‐enriched genomic library obtained for the gudgeon Squalidus chankaensis biwae. These markers were also available for the congeners S. c. tsuchigae and S. japonicus from Japan, which had five to 46 alleles and an expected heterozygosity ranging from zero to 0.946. Linkage equilibrium was observed at all loci, and most loci did not show significant deviation from Hardy–Weinberg equilibrium. The isolated microsatellite markers will be useful for genetic diversity studies of Squalidus populations.     

Involvement of proton-sensing receptor TDAG8 in the anti-inflammatory actions of dexamethasone in peritoneal macrophages

Dexamethasone (DEX), a potent glucocorticoid, increased the expression of T-cell death associated gene 8 (TDAG8), a proton-sensing G protein-coupled receptor, which is associated with the enhancement of acidic pH-induced cAMP accumulation, in peritoneal macrophages. We explored the role of increased TDAG8 expression in the anti-inflammatory actions of DEX. The treatment of macrophages with either DEX or acidic pH induced the cell death of macrophages; however, the cell death was not affected by TDAG8 deficiency. While DEX inhibited lipopolysaccharide-induced production of tumor necrosis factor-α, an inflammatory cytokine, which was independent of TDAG8, at neutral pH, the glucocorticoid enhanced the acidic pH-induced inhibition of tumor necrosis factor-α production in a manner dependent on TDAG8. In conclusion, the DEX-induced increase in TDAG8 expression is in part involved in the glucocorticoid-induced anti-inflammatory actions through the inhibition of inflammatory cytokine production under the acidic pH environment. On the other hand, the role of TDAG8 in the DEX-induced cell death is questionable.     

Neurexin-1, a presynaptic adhesion molecule, localizes at the slit diaphragm of the glomerular podocytes in kidneys

The slit diaphragm connecting the adjacent foot processes of glomerular epithelial cells (podocytes) is the final barrier of the glomerular capillary wall and serves to prevent proteinuria. Podocytes are understood to be terminally differentiated cells and share some common features with neurons. Neurexin is a presynaptic adhesion molecule that plays a role in synaptic differentiation. Although neurexin has been understood to be specifically expressed in neuronal tissues, we found that neurexin was expressed in several organs. Several forms of splice variants of neurexin-1α were detected in the cerebrum, but only one form of neurexin-1α was detected in glomeruli. Immunohistochemical study showed that neurexin restrictedly expressed in the podocytes in kidneys. Dual-labeling analyses showed that neurexin was colocalized with CD2AP, an intracellular component of the slit diaphragm. Immunoprecipitation assay using glomerular lysate showed that neurexin interacted with CD2AP and CASK. These observations indicated that neurexin localized at the slit diaphragm area. The staining intensity of neurexin in podocytes was clearly lowered, and their staining pattern shifted to a more discontinuous patchy pattern in the disease models showing severe proteinuria. The expression and localization of neurexin in these models altered more clearly and rapidly than that of other slit diaphragm components. We propose that neurexin is available as an early diagnostic marker to detect podocyte injury. Neurexin coincided with nephrin, a key molecule of the slit diaphragm detected in a presumptive podocyte of the developing glomeruli and in the glomeruli for which the slit diaphragm is repairing injury. These observations suggest that neurexin is involved in the formation of the slit diaphragm and the maintenance of its function.     

Efficient functional analysis system for cyanobacterial or plant cytochromes P450 involved in sesquiterpene biosynthesis

Tractable plasmids (pAC-Mv-based plasmids) for Escherichia coli were constructed, which carried a mevalonate-utilizing gene cluster, towards an efficient functional analysis of cytochromes P450 involved in sesquiterpene biosynthesis. They included genes coding for a series of redox partners that transfer the electrons from NAD(P)H to a P450 protein. The redox partners used were ferredoxin reductases (CamA and NsRED) and ferredoxins (CamB and NsFER), which are derived from Pseudomonas putida and cyanobacterium Nostoc sp. strain PCC 7120, respectively, as well as three higher-plant NADPH-P450 reductases, the Arabidopsis thaliana ATR2 and two corresponding enzymes derived from ginger (Zingiber officinale), named ZoRED1 and ZoRED2. We also constructed plasmids for functional analysis of two P450s, α-humulene-8-hydroxylase (CYP71BA1) from shampoo ginger (Zingiber zerumbet) and germacrene A hydroxylase (P450NS; CYP110C1) from Nostoc sp. PCC 7120, and co-transformed E. coli with each of the pAC-Mv-based plasmids. Production levels of 8-hydroxy-α-humulene with recombinant E. coli cells (for CYP71BA1) were 1.5- to 2.3-fold higher than that of a control strain without the mevalonate-pathway genes. Level of the P450NS product with the combination of NsRED and NsFER was 2.9-fold higher than that of the CamA and CamB. The predominant product of P450NS was identified as 1,2,3,5,6,7,8,8a-octahydro-6-isopropenyl-4,8a-dimethylnaphth-1-ol with NMR analyses.     

Molecular identification of ghrelin receptor (GHS-R1a) and its functional role in the gastrointestinal tract of the guinea-pig

Ghrelin stimulates gastric motility in vivo in the guinea-pig through activation of growth hormone secretagogue receptor (GHS-R). In this study, we identified GHS-R1a in the guinea-pig, and examined its distribution and cellular function and compared them with those in the rat. Effects of ghrelin in different regions of gastrointestinal tract were also examined. GHS-R1a was identified in guinea-pig brain cDNA. Amino acid identities of guinea-pig GHS-R1a were 93% to horses and 85% to dogs. Expression levels of GHS-R1a mRNA were high in the pituitary and hypothalamus, moderate in the thalamus, cerebral cortex, pons, medulla oblongata and olfactory bulb, and low in the cerebellum and peripheral tissues including gastrointestinal tract. Comparison of GHS-R1a expression patterns showed that those in the brain were similar but the expression level in the gastrointestinal tract was higher in rats than in guinea-pigs. Guinea-pig GHS-R1a expressed in HEK 293 cells responded to rat ghrelin and GHS-R agonists. Rat ghrelin was ineffective in inducing mechanical changes in the stomach and colon but caused a slight contraction in the small intestine. 1,1-Dimethyl-4-phenylpiperazinium and electrical field stimulation (EFS) caused cholinergic contraction in the intestine, and these contractions were not affected by ghrelin. Ghrelin did not change spontaneous and EFS-evoked [³H]-efflux from [³H]-choline-loaded ileal strips. In summary, guinea-pig GHS-R1a was identified and its functions in isolated gastrointestinal strips were characterized. The distribution of GHS-R1a in peripheral tissues was different from that in rats, suggesting that the functional role of ghrelin in the guinea-pig is different from that in other animal species.