Genomic Analysis of a New Mammalian Distal-less Gene: Dlx7

We have cloned a new Dlx gene (Dlx7) from human and mouse that may represent the mammalian orthologue of the newt geneNvHBox-5.The homeodomains of these genes are highly similar to all other vertebrate Dlx genes, and regions of similarity also exist between mammalian Dlx7 and a subset of vertebrate Dlx genes downstream of the homeodomain. The sequence divergence between human and mouse Dlx7 in these regions is greater than that predicted from comparisons of other vertebrate Dlx genes, however, and there is little sequence similarity upstream of the homeodomain both between these two genes and with other Dlx genes. We present evidence for alternative splicing of mouseDlx7upstream of the homeodomain that may account for some of this divergence. We have mapped humanDLX7distal to the 5′ end of the HOXB cluster at an estimated distance of between 1 and 2 Mb by FISH. Both the human and the mouse Dlx7 are shown to be closely linked to Dlx3 in a convergently transcribed orientation. These mapping results support the possibility that vertebrate distal-less genes have been duplicated in concert with the Hox clusters.     

Isolation of a bacterium that causes anaaki disease of the red algae Porphyra yezoensis

Anaaki disease causes severe damage to the red algae Porphyra yezoensis from which the Japanese traditional food 'nori'is produced. The causative agent of anaaki disease was isolated by several repeats of single-colony isolation and infection experiments, and was identified as Flavobacterium sp. LAD-1. The bacterium showed hydrolytic activity toward porphyran but not toward other polysaccharides composing the thallus of Porphyra , such as β-1,3-xylan or β-1,4-mannan. The bacterium also showed β-D-galactosidase activity.     

Sarcoplasmic reticulum calsequestrins: Structural and functional properties

Calsequestrin is the major Ca²⁺-binding protein localized in the terminal cisternae of the sarcoplasmic reticulum (SR) of skeletal and cardiac muscle cells. Calsequestrin has been purified and cloned from both skeletal and cardiac muscle in mammalian, amphibian, and avian species. Two different calsequestrin gene products namely cardiac and fast have been identified. Fast and cardiac calsequestrin isoforms have a highly acidic amino acid composition. The amino acid composition of the cardiac form is very similar to the skeletal form except for the carboxyl terminal region of the protein which possess variable length of acidic residues and two phosphorylation sites. Circular dichroism and NMR studies have shown that calsequestrin increases its -helical content and the intrinsic fluorescence upon binding of Ca²⁺. Calsequestrin binds Ca²⁺ with high-capacity and with moderate affinity and it functions as a Ca²⁺ storage protein in the lumen of the SR. Calsequestrin has been found to be associated with the Ca²⁺ release channel protein complex of the SR through protein-protein interactions. The human and rabbit fast calsequestrin genes have been cloned. The fast gene is skeletal muscle specific and transcribed at different rates in fast and slow skeletal muscle but not in cardiac muscle. We have recently cloned the rabbit cardiac calsequestrin gene. Heart expresses exclusively the cardiac calsquestrin gene. This gene is also expressed in slow skeletal muscle. No change in calsequestrin mRNA expression has been detected in animal models of cardiac hypertrophy and in failing human heart.     

Evolution of restriction sites of ribosomal DNA in natural populations of the field mouse,Apodemus speciosus

An analysis by restriction endonuclease digestion of ribosomal DNA (rDNA) was carried out in natural populations of Apodemus speciosus, a field mouse that is endemic to Japan. Two restriction sites, the EcoRI (E3) and DraI (D4) sites, in the nontranscribed spacer region downstream from the gene for 28S RNA showed polymorphism within and between individuals in the populations from the Japanese main islands. By contrast, populations from the small adjoining islands which are thought to have separated from the main islands 1–2 × 10⁴ years ago showed relatively low levels of polymorphism within and between individuals, i.e., one of the polymorphic bands in the case of each enzyme was predominant in these populations, irrespective of the variants. These results indicate that the rate of fixation of site variations depends on population size and that the direction of fixation is random. Furthermore, each polymorphic restriction site seems to be fixed independently.Correspondence to: H. Suzuki     

Conformation of (2→1)-β-d-fructan in aqueous solution

The conformation and dilute solution properties of (2→1)-β-d-fructan in aqueous solution were studied by gel permeation chromatography, low-angle laser light-scattering photometry, viscometry, small-angle X-ray scattering and electron microscopy. Fractions covering a broad range of weight-average molecular weights (M_w) from 1.49 × 10⁴ to 5.29 × 10⁶ were obtained from a native sample by ultrasonic degradation and fractional precipitation. For M_w < 4 × 10⁴, the intrinsic viscosity [η] varies with M_w^0.71, indicating that the fructan chain behaves as a random coil expanded by an excluded-volume effect in this molecular weight region. For M_w > 10⁵, [η] exhibits an unusually weak dependence on M_w and finally becomes almost independent of molecular weight. This behaviour is interpreted in terms of a globular conformation of the high-molecular-weight fructan molecules. Small-angle X-ray-scattering measurements and electron microscopic observations support this interpretation of the values of [η] observed.     

Synthesis of sulfated derivatives of curdlan and their anti-HIV activity

Sulfopropyl curdlan was synthesized, its structure was determined, and the anti-HIV activity was compared with that of standard curdlan sulfates obtained with piperidine N-sulfonic acid in dimethyl sulfoxide. It was shown that sulfopropyl curdlan exhibits weaker anti-HIV activity than curdlan sulfate. Curdlan sulfates were synthesized with a SO₃-pyridine complex in a heterogeneous phase. It was shown from ¹³C-NMR spectra of acetylated curdlan sulfates that they had a different substituent distribution from standard curdlan sulfate. The cytotoxicity of the curdlan sulfates was attributed to their heterogeneous structure.     

Additive Induction of Egr-1 (zif/268) mRNA Expression in Neuroblastoma × Glioma Hybrid NG108-15 Cells via Cholinergic Muscarinic, α2-Adrenergic, and Bradykinin Receptors

Abstract: Administration of carbachol, noradrenaline, and bradykinin induced Egr-1 mRNA expression within 1 h in mouse neuroblastoma × rat gliomahybrid NG108–15 cells. With specific receptor antagonists, the Egr-1 inductions by carbachol and noradrenaline were shown to be mediated via cholinergic muscarinic and α₂-adrenergic receptors, respectively. At their saturation levels for Egr-1 induction, the two agonists had additive effects when added together, but no prolongation of the effect on Egr-1 induction was observed. Addition of carbachol or noradrenaline 6 h after primary stimulation with carbachol or noradrenaline did not result in secondary Egr-1 induction, probably because of receptor desensitization. On the other hand, bradykinin consistently had an additive effect on Egr-1 induction, irrespective of the time of its addition, suggesting that the signal pathways for Egr-1 induction by carbachol or noradrenaline and by bradykinin are different. Treatment of cells with pertussis toxin or cholera toxin strongly inhibited Egr-1 induction by carbachol or noradrenaline but only partially inhibited the induction by bradykinin. Thus, the signals transduced in NG108–15 cells by different neurotransmitter receptors appear to have different effects on Egr-1 induction, depending on the times of stimulation and the combinations of receptors stimulated.     

Correction to: Comparison of the usability of an automatic sleep staging program via portable 1-channel electroencephalograph and manual sleep staging with traditional polysomnography

Sleep and Biological Rhythms -