Expression of inwardly rectifying K+ channels in the carotid body of rat

The inwardly rectifying K+ channels, Kir1.1, Kir2.3, Kir4.1-Kir5.1, and Kir4.2-Kir5.1, are candidate chemosensory molecules for CO2/H+. Here, we determined the mRNA expression and immunohistochemical localization of these channels in the carotid body (CB) and petrosal ganglion (PG) of the rat. RT-PCR analysis revealed mRNA expression of Kir4.1 and Kir5.1 in CB, and Kir1.1, Kir4.1, and Kir5.1 in PG. Immunohistochemistry identified the glomus cells in CB to express both Kir4.1 and Kir5.1 protein, while the nerve fibers in CB were immunoreactive for Kir1.1, Kir4.1, and Kir5.1. In the PG, immunoreactivity for Kir1.1, Kir4.1, and Kir5.1 was observed in some ganglion cells. Our findings suggest that Kir channels in the peripheral chemoreceptors play a role in sensing hypercapnic acidosis and maintaining the resting membrane potentials.

3-D finite element analysis and experimental study on brain injury mechanism

The purpose of this paper is to discuss the basic study of mechanism of brain injury analytically and experimentally, in respect to the frequency analysis of the pressure changes. First, a three-dimensional FEM model for impact analysis was presented. The pressure changes inside a brain agar phantom and its frequency analysis were calculated. Second, an experimental system to perform an impact experiment was presented. In the impact experiments, the pressure changes inside a brain agar phantom after impact were measured. The comparison of the computer simulation and the experimental results of the impacts showed that the negative pressure, which seemed to cause the contrecoup injury at the contrecoup side of a brain, also appeared in the contrecoup side of the brain agar phantom. Finally the results of the frequency analysis of pressure changes by FFT were presented. From the results of computer simulations and impact experiments, we found similar spectrums in some frequency bands, which seemed to be the occurrence of the brain injury.

Finite element analysis and experimental study on mechanism of brain injury using brain model

The aim of this study is to discuss the occurrence mechanism of the brain injury analytically and experimentally. In this paper, first, an experimental system to do an impact experiment was presented. The pressure changes inside a brain agar phantom were measured. Second, a three-dimensional FEM model of the impact experiment was constructed. From the results of the fundamental analysis, the transmitted pressure inside the brain agar phantom could be presented. The comparison of the computer simulation and experimental results showed that the negative pressure values, same as the positive pressure occurred in the coup side region of the agar, also appeared in the contrecoup side region of the agar.

Isolation of a subfamily of genes for R2R3-MYB transcription factors showing up-regulated expression under nitrogen nutrient-limited conditions

Plant R2R3-MYB transcription factors are encoded by more than 100 copies of genes. In this study, we attempted to isolate some members of the R2R3-MYB superfamily involved in regulation of nitrogen fixation in legumes. A library of 300 recombinant plasmid clones containing the R2R3-MYB fragments of the superfamily was screened by differential hybridization to isolate R2R3-MYB genes whose expression was up-regulated under nitrogen nutrient-limited conditions. Two groups of clones were identified, each of which seemed to represent a gene responsive to nitrogen starvation. The entire coding regions for the genes were further isolated by PCR and were designated LjMYB101 and LjMYB102. By screening a genomic library of Lotus japonicus with a probe derived from LjMYB101, the third gene, LjMYB103, was isolated. In addition, a candidate for the soybean orthologue of LjMYB101 was isolated and designated GmMYB101. Sequence alignment of the genes with members of the plant R2R3-MYB superfamily showed that they all belonged to the subgroup 10 of the superfamily. The expression analysis of the genes showed that the organ-specific and nitrate-regulated expression profile of MYB101 was very similar to that of CHS in Lotus as well as in soybean, suggesting a possible role for MYB101 in regulation of flavonoid biosynthesis in response to nitrate starvation. On the other hand, an interesting relationship, in structure and function, was found between LjMYB101 and LjGln1, suggesting an alternative role for MYB101 in regulation of nitrogen metabolism.

Synthesis of 5-substituted [N3-15N]-pyrimidine nucleosides: Developing model systems for NMR studies of substituent effects on the N-H...N hydrogen bond in duplex DNA

The effects on various NMR parameters of substitutions, which may influence the hydrogen bond strengths of Watson-Crick-type base pairs, were investigated for DNA dodecamers containing 5-substituted-2'-deoxyuridine derivatives in oligomers, 5'-d(CGCGAATXCGCG)-3', where A and X were [ul-15N]-2'-deoxyadenosine and [3(-15)N]-2'-deoxyuridine derivatives. The substitution effects on the NMR parameters were linearly correlated with the pKa values of the 2'-deoxyuridine derivatives.

Sequence divergence at chalcone synthase gene in pigmented seed coat soybean mutants of the Inhibitor locus

Seed coat color in soybeans is determined by the I (Inhibitor) locus. The dominant I allele inhibits seed coat pigmentation, and it has been suggested that there is a correlation between the inhibition of pigmentation by the I allele and chalcone synthase (CHS) gene silencing in the seed coat. Analysis of spontaneous mutations from I to i has shown that these mutations are closely related to the deletion of one of the CHS genes (designated ICHS1). In soybeans with the I/I genotype (cv. Miyagi shirome), a truncated form of the CHS gene (CHS3) is located in an inverse orientation 680 bp upstream of ICHS1, and it was previously suggested that the truncated CHS3- ICHS1 cluster might be involved in CHS gene silencing in the seed coat. In the current study, the truncated CHS3- ICHS1 cluster was compared with the corresponding region of pigmented seed coat mutants in which I had changed to i in Miyagi shirome and in the strain Karikei 584. In the Karikei 584 mutant, the truncated CHS3-ICHS1 cluster was retained and the sequence diverged at a point immediately upstream (32 bp) of this cluster. The sequences upstream of the points of divergence in both mutants almost perfectly matched a part of the registered sequence in a soybean BAC clone containing the soybean cyst nematode resistance-associated gene, and inspection of the sequences suggested that the sequence divergence of the CHS gene in the Karikei 584 and Miyagi shirome mutants was due to an unequal crossing-over via 4-bp or 5-bp short repeats, respectively.

Origin of cytoplasm substituted rice cultivars found in Japan

Genetic variation of Japanese rice cultivars were examined. Five of 450 lowland cultivars and another five of 200 upland cultivars were determined as the indica type by using isozyme genotypes and the remainder were of the japonica type. The major characteristics of these indica cultivars, revealed a slender shape of grains, a short apiculus hair length, a positive allele for Ph reaction, and allele-3 for the Pgd1 locus. Three of these indica cultivars showed a non-deletion ORF100, which is essential to the japonica-type plastid. The plastid subtype identity (PS-ID) sequences of these plastids is 6C7A, which is also a japonica-specific repeat unit. Thus, these cultivars were concluded to be naturally generated cytoplasm substituted lines. These plastids were introduced into a indica genetic background from japonica cultivars grown elsewhere. The rest of the indica cultivars revealed a deletion-type ORF100 and plastid subtype 8C8A, both of which are indica-specific. These cultivars carried indica-type allelic constitutions for diagnostic isozyme loci. However, other characters were identical to the cytoplasm-substituted cultivars in Japan. In East and Southeast Asia, cultivars carrying a indica-type nuclear genotype with a japonica-type plastid are restricted to Aus cultivars in the Bengal region. Genetic and historical records suggest that Japanese indica cultivars and the Aus cultivars are closely related. The Aus cultivars acquire necessary genetic constitutions from both indica and japonica cultivars through naturally occurring out-crossing to adapt to a particular cultivation condition in the region. The wide adaptability enabled them to be introduced into a northern region like Japan.

Analysis of the duplicated CHS1 gene related to the suppression of the seed coat pigmentation in yellow soybeans

Seed coat color in soybean is controlled by the classically defined I ( Inhibitor) locus. The seeds of most commercial soybean varieties are yellow due to the presence of a dominant allele of the I locus ( I: yellow seed coat, or i(i) : pigmented hilum and yellow seed coat), which inhibits seed coat pigmentation. Analysis of spontaneous mutations from I (yellow seed coat) to i (pigmented seed coat) has shown that these mutations are correlated with the deletion of a duplicated chalcone synthase gene-1 ( CHS1) region. In the current study, we isolated the duplicated CHS1 region from a soybean cultivar with a I/I genotype (cv Miyagi shirome) and determined its structure. The results showed that the duplicated CHS1 contained intact regulatory and coding regions. We designated the duplicated CHS1 as ICHS1. In the hypocotyls of Miyagi shirome, the cDNA derived from ICHS1 mRNA was identified by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, whereas in the immature seed coats it was suggested that the amount of transcripts from ICHS1 and/or another type of CHS1 ( CHS1.1) was very low. Interestingly, in the Miyagi shirome genome with a I/I genotype, ICHS1 was closely linked to the truncated CHS3, and sequence comparison showed that this cluster probably arose from the CHS1-CHS3 cluster by a 1.8-kb deletion event.

Different maternal origins of Japanese lowland and upland rice populations

Plastid subtype ID (PS-ID) sequences were determined from sequence data based on CA repeats between genes rpl16 and rpl14 in Japanese lowland and upland cultivars. The PS-ID sequences of Japanese rice cultivars showed that there are different maternal origins between lowland and upland cultivars. One subtype, 6C7A, of PS-ID sequences was predominant in all but one Japanese lowland cultivar and carried a combination of the indica-specific subtype 8C8A and japonica-specific nuclear markers for the isozyme genotype. It is probably a nuclear-cytoplasmic recombinant resulting from natural out-crossing and succeeding self-pollination. The origin of the plastid was re-confirmed by the existence of an indica-specific deletion in the plastid genome. In contrast, the Japanese upland cultivars showed two subtypes, 7C6A and 6C7A, of PS-ID sequences. An upland-specific isozyme allele as a nuclear marker was equally predominant in cultivars carrying each subtype. The existence of these particular upland-specific nuclear and cytoplasmic genotypes suggests that the origin of Japanese upland cultivars is different from that of Japanese lowland cultivars. Cultivars carrying the upland-specific nuclear genotype are common in Southeast Asia, but the combination of the upland-specific nuclear and cytoplasmic genotypes which is the same as the Japanese upland predominant type was found in cultivars only in Taiwan and Indonesia. Japanese upland cultivars are closely related to those cultivars.

Extensive trans-species mitochondrial polymorphisms in the carabid beetles Carabus subgenus Ohomopterus caused by repeated introgressive hybridization

To study the potential importance of introgressive hybridization to the evolutionary diversification of a carabid beetle lineage, we studied intraspecific and trans-species polymorphisms in the mitochondrial NADH dehydrogenase subunit 5 (ND5) gene sequence (1083 bp) in four species of the subgenus Ohomopterus (genus Carabus) in central and eastern Honshu, Japan. Of the four species, C. insulicola is parapatric with the other three, and can hybridize naturally with at least two. This species possesses two haplotypes of remote lineages. We classified ND5 haplotypes using polymerase chain reaction-restriction fragment length polymorphism with TaqI endonuclease for 524 specimens, and sequenced 143 samples. Analysis revealed that each species was polyphyletic in its mitochondrial DNA phylogeny, representing a marked case of trans-species polymorphism. Recent one-way introgression of mitochondria from C. arrowianus nakamurai to C. insulicola, and from C. insulicola to C. esakii, was inferred from the frequency of identical sequences between these species and from direct evidence of hybridization in their contact zones. Other intraspecific polymorphisms in the four species may be due to undetected introgressive hybridization (e.g. C. insulicola to C. maiyasanus) or from stochastic lineage sorting of ancestral polymorphisms. This beetle group has a genital lock-and-key system, with species-specific or subspecies-specific genital morphology that may act as a barrier to hybridization. However, our results demonstrate that introgressive hybridization has occurred multiple times, at least for mitochondria, despite differences among, and stability within, morphological characters that distinguish local populations. Thus, hybridization and introgression could have been key processes in the evolutionary diversification of Ohomopterus.

[Drugs that modulate the cellular function of calcium ion]

Cytoplasmic Ca(2+) concentration is kept low level of about 10(-7)M. When Ca(2+) concentration increases by specific stimuli via opening of channel proteins, Ca(2+) binds to Ca(2+)-binding proteins, activating specific proteins, results in responding the stimuli. In this report, we summarize the effect of drugs, of which targets are the proteins above, including Ca(2+)-pump, ion exchanger, ion channels, calmodulin and calmodulin-binding proteins, and other Ca(2+) binding proteins.

Reconstruction of urinary tract utilizing transverse colon conduit for a cystectomized patient with post-ureterocutaneostomy complications and sigmoid colon cancer

A seventy-four years old man had been suffering from symptomatic and infectious complications associated with conjoined cutaneoureterostomy following the radical cystectomy for advanced transitional cell carcinoma of the bladder 3 years ago. He underwent urinary reconstruction using transverse colon conduit after diagnostic exclusion of recurrent urothelial tumor in the upper urinary tract, evaluation of performance status and endoscopic examination of the colon. Enteroscopy incidentally revealed he had an early stage adenocarcinoma in his sigmoid colon to be resected, and the resection was followed by the urinary diversion. Postoperatively he is satisfied to be free from urinary complications and frequently visits the outpatient clinic for painful and troublesome ureteral catheter exchange.

A highly sensitive method for measurement of myosin ATPase activity by reversed-phase high-performance liquid chromatography

A new method for measurement of myosin ATPase activity has been developed utilizing reversed-phase high-performance liquid chromatography (HPLC), which detects as low as 0.05 nmol of ADP hydrolyzed from ATP. After termination of the ATPase reaction by addition of perchloric acid, the hydrolysate ADP and substrate ATP were separated by reversed-phase HPLC. The absorbance of ADP was monitored at 259 nm, and the amount of ADP was quantified from its peak area on the chromatogram by use of the NIH Image computer software. Our method showed linearity over a wide range from 0.05 to 10 nmol of ADP per 20 microl with a coefficient of determination (r(2)) of 0.99. Myosin ATPase activities determined by the HPLC method were almost identical to those determined by the malachite green method, a widely used spectrophotometric method with range of detection from 1 to 8 nmol of phosphate. Because our method requires only a small volume of reaction solution, it will be a powerful tool for measuring ATPase activity of motor proteins, which are difficult to obtain in large amount.

New rat model for attention deficit hyperactive disorder (ADHD)

PURPOSE

In a strain of the Long-Evans Cinnamon (LEC) rats, we found spontaneously hyperactive animals designated as "wiggling," and established a congenic wiggling (Wig) rat by transferring the gene from the LEC to the Wistar King-Aptekman/Hokkaido (WKAH) strain. We evaluated the feasibility of the Wig rat for an animal model of human attention deficit hyperactive disorder (ADHD).

METHODS

Mode of inheritance was examined by use of linkage analyses. Motor activity, behavior, and working memory were assessed by use of electric digital counters, open field test, and Y-maze and water-maze tests.

RESULTS

The abnormal behavior, including hyperactivity, was transmitted in autosomal recessive mode. Diurnal and nocturnal motor activity of 12- to 14-week-old Wig rats was markedly higher than that of controls, and this hyperactivity was more prominent during nighttime than daytime. Ambulation in the open-field test was significantly increased in Wig rats, but rearing was decreased in Wig rats, compared with controls. Results of the Y-maze tests indicated that spontaneous alternation behavior was significantly impaired in Wig rats, although there was no difference in the total arm entries. The water-maze test could not be performed because, when exposed to water, Wig rats panicked and almost drowned.

CONCLUSIONS

Wig rats are hyperactive and have impaired working memory and impulsive behavior, as assessed by the motor activity and open-field tests and the Y-maze test, and these abnormalities are transmitted by a single gene with Mendelian pattern. Wig rats represent an excellent animal model of human ADHD.

Hyponatremia with increased plasma antidiuretic hormone in a case of hypothyroidism

We report a 70-year-old woman with hypothyroidism and severe hyponatremia. Her plasma antidiuretic hormone (ADH) level was inappropriately high for her low plasma osmolality. Her low serum sodium level was gradually corrected by water restriction and sodium supplementation prior to the initiation of thyroid hormone replacement. After a diagnosis of Hashimoto's thyroiditis had been made, the patient was treated with levothyroxine. Following this treatment, the patient's serum sodium level increased drastically. It is suggested that the elevated plasma ADH level played an important role in the development of hyponatremia in this case.

Retinal fascin: functional nature, subcellular distribution, and chromosomal localization

PURPOSE

To investigate the functional properties, subcellular localization, and chromosomal location of retinal fascin.

METHODS

Recombinant retinal fascin protein was prepared by using a baculovirus-insect expression system. Actin-binding and -bundling assays were performed with chick actin purified from skeletal muscle. Western blot analysis and immunohistochemistry were performed with a polyclonal antibody raised against bovine retinal fascin. A human retinal cDNA library was screened with an expressed sequence tag cDNA fragment. Chromosomal location was determined with fluorescent in situ hybridization.

RESULTS

The actin-binding and actin-bundling activities of retinal fascin were demonstrated by high- and low-speed centrifugation assays. Formation of filamentous (F)-actin bundles by retinal fascin in vitro was also morphologically confirmed by fluorescence microscopy and electron microscopy. Immunohistochemical analysis revealed that retinal fascin protein was localized specifically in the outer and inner segments of the photoreceptor cells in the retina. Two splicing variants of human retinal fascin cDNA were also located. One clone encoded 492 amino acids, and the other encoded 516 amino acids. The gene encoding retinal fascin was localized to human chromosome 17, region q24 -25.

CONCLUSIONS

These results suggest that retinal fascin may play a role in formation of unique morphologic structures of the photoreceptor cells and is a candidate gene for retinal degenerative disorders.

Stable transfectants of smooth muscle cell line lacking the expression of myosin light chain kinase and their characterization with respect to the actomyosin system

We constructed a plasmid vector having a 1.4-kilobase pair insert of myosin light chain kinase (MLCK) cDNA in an antisense direction to express antisense mRNA. The construct was then transfected to SM3, a cell line from vascular smooth muscle cells, producing a few stable transfectants. The down-regulation of MLCK expression in the transfectants was confirmed by both Northern and Western blots. The control SM3 showed chemotaxic motility to platelet-derived growth factor-BB, which was supported by lamellipodia. However, the transfectants showed neither chemotaxic motility nor developed lamellipodia, indicating the essential role of MLCK in the motility. The specificity for the targeting was assessed by a few tests including the rescue experiment. Despite this importance of MLCK, platelet-derived growth factor-BB failed to induce MLC20 phosphorylation in not only the transfectants but also in SM3. The mode in which MLCK was involved in the development of membrane ruffling is discussed with special reference to the novel property of MLCK that stimulates the ATPase activity of smooth muscle myosin without phosphorylating its light chain (Ye, L.-H., Kishi, H., Nakamura, A., Okagaki, T., Tanaka, T., Oiwa, K., and Kohama, K. (1999) Proc. Natl. Acad. Sci. U. S. A. 96, 6666-6671).