Regulation of drought tolerance by gene manipulation of 9-cis-epoxycarotenoid dioxygenase, a key enzyme in abscisic acid biosynthesis in Arabidopsis

Abscisic acid (ABA), a plant hormone, is involved in responses to environmental stresses such as drought and high salinity, and is required for stress tolerance. ABA is synthesized de novo in response to dehydration. 9-cis-epoxycarotenoid dioxygenase (NCED) is thought to be a key enzyme in ABA biosynthesis. Here we demonstrate that the expression of an NCED gene of Arabidopsis, AtNCED3, is induced by drought stress and controls the level of endogenous ABA under drought-stressed conditions. Overexpression of AtNCED3 in transgenic Arabidopsis caused an increase in endogenous ABA level, and promoted transcription of drought- and ABA-inducible genes. Plants overexpressing AtNCED3 showed a reduction in transpiration rate from leaves and an improvement in drought tolerance. By contrast, antisense suppression and disruption of AtNCED3 gave a drought-sensitive phenotype. These results indicate that the expression of AtNCED3 plays a key role in ABA biosynthesis under drought-stressed conditions in Arabidopsis. We improved drought tolerance by gene manipulation of AtNCED3 causing the accumulation of endogenous ABA.

Scanning electron microscopic observation of the architecture of collagen fibres in chicken M. iliotibialis lateralis

1. The collagen architecture of M. iliotibialis lateralis in chicken was observed under the scanning electron microscope after muscle maceration in NaOH. 2. Immunohistochemical methods showed Type I and III collagens to be distributed over both perimysium and endomysium. 3. Thick perimysium around secondary myofibre fasciculi was composed of many large longitudinal collagen bundles and a few small circumferential bundles. In contrast, thin perimysium around primary myofibre fasciculi showed mainly circumferential bundles. 4. Endomysium had a honeycomb-like structure and consisted of a fine collagen mesh, its main fibre striation being circumferential. 5. It is suggested that functional demand differs between thick perimysium and thin endomysium.

The AHK4 gene involved in the cytokinin-signaling pathway as a direct receptor molecule in Arabidopsis thaliana

We previously identified a set of structurally related genes, AHK2, 3 and 4, each encoding a sensor histidine kinase in Arabidopsis thaliana. To determine the relevant biological functions, we identified a loss-of-function mutation of the AHK4 gene. The mutant exhibited the cytokinin-resistant phenotype not only in inhibition of root growth by cytokinin but also in greening and shoot induction of calli. Moreover, AHK4 expressed in budding yeast showed histidine kinase activity in a manner dependent on the presence of cytokinin. These results strongly suggested that AHK4 is involved in the cytokinin-signaling pathway, as a direct receptor molecule, in Arabidopsis.

[Early results and new indication of the off-pump coronary artery bypass (OPCAB)]

BACKGROUND

The off-Pump coronary artery bypass (OPCAB) has recently gained popularity. However the safety and feasibility of the procedure has not been fully proven especially for unstable myocardial ischemia.

METHODS

Between March 1998 and November 2000, 135 patients with a mean age of 69.7 (41-95) underwent off-pump coronary artery bypass via sternotomy. Eight patients were operated on emergently and 11 were urgently. LV function ranged from 8% to 70%. Eleven patients required preoperative IABP.

RESULTS

All procedures were completed without conversion to cardiopulmonary bypass. The mean number of grafts per patient was 2.8 (range, 1 to 6). Cardiac-related hospital mortality was 2.2% (3/135). Angiographic assessment of grafts demonstrated an overall patency of 98.0%, arterial grafts 98.7% and venous grafts 96.6%. In retrospect, these were equivalent results of conventional coronary artery bypass by the same operator.

CONCLUSION

OPCAB is safe and feasible even with LV dysfunction or unstable myocardial ischemia.

Arabidopsis NPL1: a phototropin homolog controlling the chloroplast high-light avoidance response

Chloroplasts relocate their positions in a cell in response to the intensity of incident light, moving to the side wall of the cell to avoid strong light, but gathering at the front face under weak light to maximize light interception. Here, Arabidopsis thaliana mutants defective in the avoidance response were isolated, and the mutated gene was identified as NPL1 (NPH-like 1), a homolog of NPH1 (nonphototropic hypocotyl 1), a blue light receptor used in phototropism. Hence, NPL1 is likely a blue light receptor regulating the avoidance response under strong light.

Role of the putative membrane-bound endo-1,4-beta-glucanase KORRIGAN in cell elongation and cellulose synthesis in Arabidopsis thaliana

A temperature-sensitive, elongation-deficient mutant of Arabidopsis thaliana was isolated. At the non-permissive temperature of 31 degrees C, the mutation impaired tissue elongation; otherwise, tissue development was normal. Hypocotyl cells that had established cell walls at 21 degrees C under light-dark cycles ceased elongation and swelled when the mutant was shifted to 31 degrees C and darkness, indicating that the affected gene is essential for cell elongation. Analysis of the cell walls of mutant plants grown at 31 degrees C revealed that the cellulose content was reduced to 40% and the pectin content was increased to 162% of the corresponding values for the wild type grown at the same temperature. The increased amounts of pectin in the mutant were bound tightly to cellulose microfibrils. No change in the content of hemicellulose was apparent in the 31 degrees C-adapted mutant. Field emission-scanning electron microscopy suggested that the structure of cellulose bundles was affected by the mutation; X-ray diffraction, however, revealed no change in the crystallite size of cellulose microfibrils. The regeneration of cellulose microfibrils from naked mutant protoplasts was substantially delayed at 31 degrees C. The recessive mutation was mapped to chromosome V, and map-based cloning identified it as a single G-->A transition (resulting in a Gly(429)-->Arg substitution) in KORRIGAN, which encodes a putative membrane-bound endo-1,4-beta-glucanase. These results demonstrate that the product of this gene is required for cellulose synthesis.

Identification of CRE1 as a cytokinin receptor from Arabidopsis

Cytokinins are a class of plant hormones that are central to the regulation of cell division and differentiation in plants. It has been proposed that they are detected by a two-component system, because overexpression of the histidine kinase gene CKI1 induces typical cytokinin responses and genes for a set of response regulators of two-component systems can be induced by cytokinins. Two-component systems use a histidine kinase as an environmental sensor and rely on a phosphorelay for signal transduction. They are common in microorganisms, and are also emerging as important signal detection routes in plants. Here we report the identification of a cytokinin receptor. We identified Arabidopsis cre1 (cytokinin response 1) mutants, which exhibited reduced responses to cytokinins. The mutated gene CRE1 encodes a histidine kinase. CRE1 expression conferred a cytokinin-dependent growth phenotype on a yeast mutant that lacked the endogenous histidine kinase SLN1 (ref. 10), providing direct evidence that CRE1 is a cytokinin receptor. We also provide evidence that cytokinins can activate CRE1 to initiate phosphorelay signalling.

Crystal structure of glucose dehydrogenase from Bacillus megaterium IWG3 at 1.7 A resolution

The crystal structure of glucose dehydrogenase (GlcDH) from Bacillus megaterium IWG3 has been determined to an R-factor of 17.9% at 1.7 A resolution. The enzyme consists of four identical subunits, which are similar to those of other short-chain reductases/dehydrogenases (SDRs) in their overall folding and subunit architecture, although cofactor binding sites and subunit interactions differ. Whereas a pair of basic residues is well conserved among NADP(+)-preferring SDRs, only Arg39 was found around the adenine ribose moiety of GlcDH. This suggests that one basic amino acid is enough to determine the coenzyme specificity. The four subunits are interrelated by three mutually perpendicular diad axes (P, Q, and R). While subunit interactions through the P-axis for GlcDH are not so different from those of the other SDRs, those through the Q-axis differ significantly. GlcDH was found to have weaker hydrophobic interactions in the Q-interface. Moreover, GlcDH lacks the salt bridge that stabilizes the subunit interaction in the Q-interface in the other SDRs. Hydrogen bonds between Q-axis related subunits are also less common than in the other SDRs. The GlcDH tetramer dissociates into inactive monomers at pH 9.0, which can be attributed mainly to the weakness of the Q-axis interface.

Synechocystis sp. PCC 6803 - a useful tool in the study of the genetics of cyanobacteria

The cyanobacterium Synechocystis sp. PCC 6803 was the first phototrophic organism to be fully sequenced. The genomic sequence has revealed the structure of the genome and its gene constituents (3167 genes), as well as the relative map positions of each gene. The functions of nearly half of the genes has been deduced using similarity searches. The genome sequence has also allowed for the implementation of systematic strategies to study gene function and the mechanisms of gene regulation on a genome-wide level. Two genome databases, CyanoBase and CyanoMutants, have been established and act as a central repository for information on gene structure and gene function, respectively. As a result of the genome sequencing and the establishment of these databases, Synechocystis sp. PCC 6803 provides an extremely versatile and easy model to study the genetic systems of photosynthetic organisms.

Complete genome structure of the nitrogen-fixing symbiotic bacterium Mesorhizobium loti

The complete nucleotide sequence of the genome of a symbiotic bacterium Mesorhizobium loti strain MAFF303099 was determined. The genome of M. loti consisted of a single chromosome (7,036,071 bp) and two plasmids, designated as pMLa (351,911 bp) and pMLb (208, 315 bp). The chromosome comprises 6752 potential protein-coding genes, two sets of rRNA genes and 50 tRNA genes representing 47 tRNA species. Fifty-four percent of the potential protein genes showed sequence similarity to genes of known function, 21% to hypothetical genes, and the remaining 25% had no apparent similarity to reported genes. A 611-kb DNA segment, a highly probable candidate of a symbiotic island, was identified, and 30 genes for nitrogen fixation and 24 genes for nodulation were assigned in this region. Codon usage analysis suggested that the symbiotic island as well as the plasmids originated and were transmitted from other genetic systems. The genomes of two plasmids, pMLa and pMLb, contained 320 and 209 potential protein-coding genes, respectively, for a variety of biological functions. These include genes for the ABC-transporter system, phosphate assimilation, two-component system, DNA replication and conjugation, but only one gene for nodulation was identified.

Complete structure of the chloroplast genome of a legume, Lotus japonicus

The nucleotide sequence of the entire chloroplast genome (150,519 bp) of a legume, Lotus japonicus, has been determined. The circular double-stranded DNA contains a pair of inverted repeats of 25,156 bp which are separated by a small and a large single copy region of 18,271 bp and 81,936 bp, respectively. A total of 84 predicted protein-coding genes including 7 genes duplicated in the inverted repeat regions, 4 ribosomal RNA genes and 37 tRNA genes (30 gene species) representing 20 amino acids species were assigned on the genome based on similarity to genes previously identified in other chloroplasts. All the predicted genes were conserved among dicot plants except that rpl22, a gene encoding chloroplast ribosomal protein CL22, was missing in L. japonicus. Inversion of a 51-kb segment spanning rbcL to rpsl6 (positions 5161-56,176) in the large single copy region was observed in the chloroplast genome of L. japonicus. The sequence data and gene information are available on our World Wide Web database at http://www.kazusa.or.jp/en/plant/database.html.

Sequence and analysis of chromosome 3 of the plant Arabidopsis thaliana

Arabidopsis thaliana is an important model system for plant biologists. In 1996 an international collaboration (the Arabidopsis Genome Initiative) was formed to sequence the whole genome of Arabidopsis and in 1999 the sequence of the first two chromosomes was reported. The sequence of the last three chromosomes and an analysis of the whole genome are reported in this issue. Here we present the sequence of chromosome 3, organized into four sequence segments (contigs). The two largest (13.5 and 9.2 Mb) correspond to the top (long) and the bottom (short) arms of chromosome 3, and the two small contigs are located in the genetically defined centromere. This chromosome encodes 5,220 of the roughly 25,500 predicted protein-coding genes in the genome. About 20% of the predicted proteins have significant homology to proteins in eukaryotic genomes for which the complete sequence is available, pointing to important conserved cellular functions among eukaryotes.

Sequence and analysis of chromosome 5 of the plant Arabidopsis thaliana

The genome of the model plant Arabidopsis thaliana has been sequenced by an international collaboration, The Arabidopsis Genome Initiative. Here we report the complete sequence of chromosome 5. This chromosome is 26 megabases long; it is the second largest Arabidopsis chromosome and represents 21% of the sequenced regions of the genome. The sequence of chromosomes 2 and 4 have been reported previously and that of chromosomes 1 and 3, together with an analysis of the complete genome sequence, are reported in this issue. Analysis of the sequence of chromosome 5 yields further insights into centromere structure and the sequence determinants of heterochromatin condensation. The 5,874 genes encoded on chromosome 5 reveal several new functions in plants, and the patterns of gene organization provide insights into the mechanisms and extent of genome evolution in plants.

Testis developments and puberty in the male Tokara (Japanese native) goat

In male Tokara (Japanese native) goats, testis development and the onset of puberty were studied histologically and observing sexual behaviour. Testes weight increased from 36+/-5.4 (S.E.) g (n=5) at 3 months of age to 126+/-6.3 g (n=6) at 12 months. The degree of the testis development differed among kids at 3 months of age and only one of four had produced spermatozoa in the testis. Large number of spermatozoa were always present in seminiferous tubules and epididymal ducts from 4 months of age. The diameter of seminiferous tubules increased from 133+/-9.9 microm (n=4) at 3 months to 198+/-1.0 microm (n=3) at 6 months with little increase thereafter. Mounting and pelvic thrusts onto a teaser doe started at from 9 to 14 weeks of age. Ejaculated semen contained sperm with good motility for the first time from 17 weeks. The male Tokara goat reaches puberty at around 4 months of age but testis development continues to 12 months.

Genome-wide expression-monitoring of jasmonate-responsive genes of Arabidopsis using cDNA arrays

Jasmonates are generally considered to mediate signalling, such as defence responses, flowering and senescence. However, factors involved in the jasmonate signal-transduction pathway remain unclear. To clarify the functions and signalling mechanisms of jasmonates on a genome-wide level, we adopted a cDNA macroarray technique. We prepared nylon filters of a cDNA macroarray on which 2880 independent expressed sequence tag clones of Arabidopsis were blotted, and hybridized (33)P-labelled single-strand DNAs synthesized from mRNAs of methyl jasmonate (MeJA)-treated and untreated Arabidopsis plants to the nylon filters. By analysing the data from the cDNA macroarray, we identified many function-known and unknown genes as MeJA-responsive genes, and confirmed that the profiles of the expression showed good agreement with Northern-blot analysis. These results demonstrate the efficiency of the cDNA macroarray for systematically analysing jasmonate-responsive genes on a genome-wide scale.

Myofibre composition and total collagen content in M. iliotibialis lateralis and M. pectoralis of Silkie and White Leghorn chickens

1. Using adult Silkie and White Leghorn (WL) chickens, fibre composition and total collagen content were compared between M. iliolibialis lateralis (ITL) and M. pectoralis (PT). 2. Fibres were divided into type IIR and IIW showing strong and weak reduced nicotinamide adenine dinucleotide dehydrogenase activities, respectively. 3. Fibre composition differed markedly between ITL and PT muscle. ITL muscle was composed of both types IIR and IIW fibre but PT muscle of only type IIW Breed difference on composition was noted only in ITL muscle of cocks (type IIR; Silkie 53.8% and WL 37.0%). 4. Total collagen content was greater in ITL muscles and in cocks in both muscles. However, a breed difference was observed only in the PT muscle of hens. 5. In conclusion, the total collagen content was affected by muscle location within the body and by sex rather than by fibre composition.

Fate of fibrin sealant in pericardial space

BACKGROUND

Although fibrin sealant (Beriplast, Aventis Behring, Marburg, Germany) has been widely used as a supplementary measure for hemostasis during cardiac surgery in Europe and is becoming popular in the United States, the pharmocokinetics of fibrin sealant applied in pericardial space has not been elucidated.

METHODS

A small incision was made on the epicardial surface of the left ventricle of a rat, and the incision was sutured. Total 0.2 ml of fibrin sealant containing iodine 125 (125I)-labeled fibrinogen, aprotinin, blood coagulation factor XIII and thrombin was applied to the area around the suture line.

RESULTS

Distributions of 125I-labeled fibrinogen in the heart on postoperative days 1, 3, 7, and 14 were 48.2% +/- 1.8%, 20.7% +/- 2.2%, 0.15% +/- 0.02%, and 0.01% +/- 0.02%, respectively. The radioactivity was negligible in the blood, liver, spleen, and kidney except for the thyroid in which the radioactivity increased to 7.9% +/- 0.7% and 4.3% +/- 0.4%, respectively, on postoperative days 7 and 14. Iodine 125-labeled fibrinogen concentrations of the heart and other organs showed a similar change in the time course of distribution. Dense and thick fibrin network, observed on postoperative day 1, had dissipated and was thinner with collagen formation by postoperative day 7.

CONCLUSIONS

Fibrin sealant applied to the pericardial cavity regresses rapidly and plays an important role in wound healing.

Chloroplast development in Arabidopsis thaliana requires the nuclear-encoded transcription factor sigma B

Development of plastids into chloroplasts, the organelles of photosynthesis, is triggered by light. However, little is known of the factors involved in the complex coordination of light-induced plastid gene expression, which must be directed by both nuclear and plastid genomes. We have isolated an Arabidopsis mutant, abc1, with impaired chloroplast development, which results in a pale green leaf phenotype. The mutated nuclear gene encodes a sigma factor, SigB, presumably for the eubacterial-like plastid RNA polymerase. Our results provide direct evidence that a nuclear-derived prokaryotic-like SigB protein, plays a critical role in the coordination of the two genomes for chloroplast development.

Crystallization and preliminary X-ray analysis of glucose dehydrogenase from Bacillus megaterium IWG3

Glucose dehydrogenase from Bacillus megaterium IWG3 has been crystallized in the presence of NAD(+) using the hanging-drop vapour-diffusion method with PEG 2000 as the precipitant. Crystals belong to space group C2 and have unit-cell parameters a = 120.8 (1), b = 66.7 (1), c = 119.6 (1) A, beta = 93.25 (3) degrees with standard deviations in parentheses. Assumption of four subunits in the asymmetric unit gave the most probable Matthews coefficient V(M) of 2.1 A(3) Da(-1) (solvent content 41.7% by volume). X-ray diffraction data were collected to 1.7 A on a synchrotron-radiation source.

Generation of expressed sequence tags from low-CO2 and high-CO2 adapted cells of Chlamydomonas reinhardtii

To characterize genes whose expression is induced in carbon-stress conditions, 12,969 and 13,450 5'-end expressed sequence tags (ESTs) were generated from cells grown in low-CO2 and high-CO2 conditions of the unicellular green alga, Chlamydomonas reinhardtii. These ESTs were clustered into 4436 and 3566 non-redundant EST groups, respectively. Comparison of their sequences with those of 3433 non-redundant ESTs previously generated from the cells under the standard growth condition indicated that 2665 and 1879 EST groups occurred only in the low-CO2 and high-CO2 populations, respectively. It was also noted that 96.2% and 96.0% of the cDNA species respectively obtained from the low-CO2 and high-CO2 conditions had no similar EST sequence deposited in the public databases. The EST species identified only in the low-CO2 treated cells included genes previously reported to be expressed specifically in low-CO2 acclimatized cells, suggesting that the ESTs generated in this study will be a useful source for analysis of genes related to carbon-stress acclimatization. The sequence information and search results of each clone will appear at the web site: http://www.kazusa.or.jp/en/plant/chlamy/EST/.

Ultrastructural localization of gustducin immunoreactivity in microvilli of type II taste cells in the rat

Gustducin is a transducin-like G protein (guanine nucleotide-binding protein) that is expressed in taste bud cells. Gustducin is believed to be involved in bitter and possibly sweet taste transduction. In the present study, we demonstrate that a subset of type II cells displays immunoreactivity to antisera directed against gustducin in taste buds of rat circumvallate papilla. Immunogold particles are present both in the microvilli and cytoplasm of the immunoreactive cells. Quantitative analysis of the data suggests that the number of colloidal gold particles (P<0.001) and nanogold particles (P<0.01) in the immunoreactive type II cells are much greater than in type I cells. There are also approximately 2.5 times (P<0.05) as many colloidal gold particles associated with the microvilli versus the cytoplasm in the immunoreactive type II cells. The ultrastructural distribution of gustducin immunoreactivity is consistent with its proposed role in the initial events of sensory transduction by gustatory receptor cells.

hosoba toge toge, a syndrome caused by a large chromosomal deletion associated with a T-DNA insertion in Arabidopsis

We isolated a T-DNA-tagged mutant named hosoba toge toge (hot) in which a pleiotropic phenotype was observed in both the shoot and root throughout the life cycle. The phenotype and allelism indicated that the mutant has a defect in both the FASCIATA1 (FAS1) gene and the FT gene located on the bottom arm of chromosome 1. Analysis of the junctions between the T-DNA ends and the plant genome suggested the presence of a 75.8-kbp deletion at the insertion site. In addition to FAS1 and FT, 13 genes were predicted to exist in the region corresponding to that deleted in hot. They include homologs of genes for type II inositol-1,4,5-triphosphate 5-phosphatase (IP5Pase), the beta-chain of N-acetyl-beta-glucosaminidase (NAGase), NADPH oxidoreductase of the zeta-crystallin family, polygalacturonase, and endo-1,4-beta-glucanase. Although most aspects of the hot phenotype can be explained by loss of FAS1 and FT functions, some novel phenotypic features which may represent aspects of a mutant phenotype due to loss-of-function of other gene(s) were observed. One "wild-type" ecotype and a previously reported T-DNA insertion line, neither of which has any obvious phenotypic abnormality, carry a possible loss-of-function mutation in the zeta-crystallin homolog and in the NAGase beta chain homolog, respectively.

High expression of glycogen-debranching enzyme in Escherichia coli and its competent purification method

Glycogen-debranching enzyme (GDE) gene from Saccharomyces cerevisiae was cloned and expressed into Escherichia coli. A 99.3% homology was found between the nucleotide sequences of GDE gene harbored in the recombinant E. coli plasmid (pTrc99A) and the open reading frame (902039-906646 position) of the 4608-bp fragment of S. cerevisiae chromosome XVI. We investigated the best conditions for GDE expression. When the cultivation temperature of recombinant E. coli strains was lowered to 25 degrees C and the isopropyl-beta-d-thiogalactopyranoside (IPTG) concentration used for induction was decreased to as low as 0.02 mM, a total of about 33 mg of recombinant GDE can be isolated from a liter culture as estimated by amylo-1,6-glucosidase activity. Consecutively, we developed a new method for purifying GDE. The method requires only a single-step purification via beta-cyclodextrin-immobilized Sepharose 6B (beta-CD Sepharose 6B) affinity chromatography and renders a 90% recovery of the enzyme. Moreover, the purified recombinant GDE is a homogeneous protein and possesses the same characteristics as those of S. cerevisiae. With the highly expressed GDE in recombinant E. coli and a rapid and effective purification method, we successfully resolved the hurdle always faced for obtaining an ample amount of purified GDE. The availability of GDE, hence, may allow advancement on GDE studies and provide new prospects for GDE on biotechnological application.

A large scale analysis of cDNA in Arabidopsis thaliana: generation of 12,028 non-redundant expressed sequence tags from normalized and size-selected cDNA libraries

For comprehensive analysis of genes expressed in the model dicotyledonous plant, Arabidopsis thaliana, expressed sequence tags (ESTs) were accumulated. Normalized and size-selected cDNA libraries were constructed from aboveground organs, flower buds, roots, green siliques and liquid-cultured seedlings, respectively, and a total of 14,026 5'-end ESTs and 39,207 3'-end ESTs were obtained. The 3'-end ESTs could be clustered into 12,028 non-redundant groups. Similarity search of the non-redundant ESTs against the public non-redundant protein database indicated that 4816 groups show similarity to genes of known function, 1864 to hypothetical genes, and the remaining 5348 are novel sequences. Gene coverage by the non-redundant ESTs was analyzed using the annotated genomic sequences of approximately 10 Mb on chromosomes 3 and 5. A total of 923 regions were hit by at least one EST, among which only 499 regions were hit by the ESTs deposited in the public database. The result indicates that the EST source generated in this project complements the EST data in the public database and facilitates new gene discovery.

Generation of 10,154 expressed sequence tags from a leafy gametophyte of a marine red alga, Porphyra yezoensis

A total of 10,154 5'-end expressed sequence tags (EST) were established from the normalized and size-selected cDNA libraries of a marine red alga, Porphyra yezoensis. Among the ESTs, 2140 were unique species, and the remaining 8014 were grouped into 1127 species. Database search of the 3267 non-redundant ESTs by BLAST algorithm showed that the sequences of 1080 species (33.1%) have similarity to those of registered genes from various organisms including higher plants, mammals, yeasts, and cyanobacteria, while 2187 (66.9%) are novel. Codon usage analysis in the coding regions of 101 non-redundant EST groups showing significant similarity to known genes indicated the higher GC contents at the third position of codons (79.4%) than the first (62.2%) and the second position (45.0%), suggesting that the genome has been exposed to high GC pressure during evolution. The sequence data of individual ESTs are available at the web site http://www.kazusa.or.jp/en/plant/porphyra/EST/.

Analysis of expressed sequence tags of flower buds in Lotus japonicus

In order to study gene expression in a reproductive organ, we constructed a cDNA library of mature flower buds in Lotus japonicus, and characterized expressed sequence tags (ESTs) of 842 clones randomly selected. The EST sequences were clustered into 718 non-redundant groups. From BLAST and FASTA search analyses of both protein and DNA databases, 58.5% of the EST groups showed significant sequence similarities to known genes. Several genes encoding these EST clones were identified as pollen-specific genes, such as pectin methylesterase, ascorbate oxidase, and polygalacturonase, and as homologous genes involved in pollen-pistil interaction. Comparison of these EST sequences with those derived from the whole plant of L. japonicus, revealed that 64.8% of EST sequences from the flower buds were not found in EST sequences of the whole plant. Taken together, the EST data from flower buds generated in this study is useful in dissecting gene expression in floral organ of L. japonicus.

Structural analysis of Arabidopsis thaliana chromosome 3. II. Sequence features of the 4,251,695 bp regions covered by 90 P1, TAC and BAC clones

To deduce the entire sequence of the top arm of the Arabidopsis thaliana chromosome 3, the sequence determination was performed on a total of 90 P1, TAC and BAC clones chosen according to our sequencing strategy. Sequence features of the resulting 4,251,695 bp regions were analyzed with various computer programs for similarity search and gene modeling. As a result, a total of 941 potential protein-coding genes were identified. The average density of the genes identified was 1 gene per 4210 bp. Introns were observed in 73% of the genes, and the average number per gene and the average length of the introns were 3.6 and 159 bp, respectively. These sequence features are essentially identical to those of chromosomes 3 and 5 in our previous reports. The regions also contained 14 tRNA genes when searched by similarity to reported tRNA genes and the tRNA scan-SE program. The sequence data and information on the potential genes are available through the World Wide Web database KAOS (Kazusa Arabidopsis data Opening Site) at http://www.kazusa.or.jp/kaos/.

Generation of 7137 non-redundant expressed sequence tags from a legume, Lotus japonicus

For comprehensive analysis of genes expressed in a model legume, Lotus japonicus, a total of 22,983 5' end expressed sequence tags (ESTs) were accumulated from normalized and size-selected cDNA libraries constructed from young (2 weeks old) plants. The EST sequences were clustered into 7137 non-redundant groups. Similarity search against public non-redundant protein database indicated that 3302 groups showed similarity to genes of known function, 1143 groups to hypothetical genes, and 2692 were novel sequences. Homologues of 5 nodule-specific genes which have been reported in other legume species were contained in the collected ESTs, suggesting that the EST source generated in this study will become a useful tool for identification of genes related to legume-specific biological processes. The sequence data of individual ESTs are available at the web site: http://www.kazusa.or.jp/en/plant/lotus/EST/.

Structural analysis of Arabidopsis thaliana chromosome 3. I. Sequence features of the regions of 4,504,864 bp covered by sixty P1 and TAC clones

Based on the physical map of Arabidopsis thaliana chromosome 3 previously constructed with CIC YAC, TAC, P1 and BAC clones (Sato, S. et al., DNA Res., 5, 163-168, 1998), a total of 60 P1 and TAC clones were sequenced, and the sequence features of the resulting 4,504,864 bp regions were analyzed by applying various computer programs for similarity search and gene modeling. As a result, a total of 1054 potential protein-coding genes were identified. The average density of the genes identified was 1 gene per 4066 bp. Introns were observed in 77% of the genes, and the average number per gene and the average length of the introns were 3.9 and 156 bp, respectively. These sequence features are essentially identical to those of chromosome 5 in our previous reports, but the gene density was slightly higher than that observed for chromosomes 2 and 4. The regions also contained 10 tRNA genes when searched by similarity to reported tRNA genes and the tRNA scan-SE program. The sequence data and information on the potential genes are available through the World Wide Web database KAOS (Kazusa Arabidopsis data Opening Site) at http://www.kazusa.or.jp/kaos/.

An anterograde and retrograde tract-tracing study on the projections from the thalamic gustatory area in the rat: distribution of neurons projecting to the insular cortex and amygdaloid complex

Projections from the thalamic gustatory nucleus, i.e. the parvicellular part of the posteromedial ventral thalamic nucleus (VPMpc) to the forebrain regions were studied in the rat by the tract-tracing methods with anterograde tracer (biotinylated dextran amine, BDA) and anterograde/retrograde tracer (wheat-germ agglutinin-horseradish peroxidase, WGA-HRP). After BDA injection into the VPMpc, terminal labeling was observed in the insular cortex, amygdaloid complex, and fundus striati. The terminal labeling in the amygdaloid complex was distributed in dorsolateral area of the rostral part of the lateral amygdaloid nucleus and the rostral part of the lateral subdivision of the central amygdaloid nucleus. The terminal labeling in the central amygdaloid nucleus extended to the fundus striati. The retrograde tracing study with WGA-HRP revealed that the projection fibers from the VPMpc to the amygdaloid complex originated from the medial part of the VPMpc and also from the thalamic area medial to the VPMpc. In the rats injected with Fluoro-Gold and WGA-HRP, respectively into the insular cortex and amygdaloid complex, no double-labeled neuronal cell bodies were found in the VPMpc, although neurons labeled singly with Fluoro-Gold were intermingled with those singly labeled with WGA-HRP in the medial part of the VPMpc. The results indicated that VPMpc neurons projecting to the amygdaloid complex constituted a population different from VPMpc neurons projecting to the insular cortex.

Structural analysis of Arabidopsis thaliana chromosome 5. X. Sequence features of the regions of 3,076,755 bp covered by sixty P1 and TAC clones

In our ongoing project to deduce the nucleotide sequence of Arabidopsis thaliana chromosome 5, non-redundant P1 and TAC clones have been sequenced on the basis of the fine physical map, and as of January, 2000, the sequences of 16.6 Mb representing approximately 60% of chromosome 5 have been accumulated and released at our web site. Along with the sequence determination, structural features of the sequenced regions have been analyzed by applying a variety of computer programs, and we already predicted a total of 2697 potential protein coding genes in the 11,166,130 bp regions, which are covered by 159 P1 and TAC clones. In this paper, we describe the structural features of the 3,076,755 bp regions covered by newly analyzed 60 P1 and TAC clones. A total of 715 potential protein coding genes were identified, giving an average density of the genes identified of 1 gene per 4001 bp. Introns were observed in 80% of the genes, and the average number per gene and the average length of the introns were 4.5 and 147 bp, respectively. These sequence features are nearly identical to those in our latest report in which the data were compiled based on a new standard of gene assignment including the computer-predicted hypothetical genes. The regions also contained 12 tRNA genes when searched by similarity to reported tRNA genes and the tRNA scan-SE program. The sequence data and information on the potential genes are available through the World Wide Web database KAOS (Kazusa Arabidopsis data Opening Site) at http://www.kazusa.or.jp/kaos/.

Reproliferation and relocation of mouse male germ cells (gonocytes) during prespermatogenesis

In the prespermatogenesis period, male germ cells (gonocytes) begin to reproliferate and move to the basement membrane of the seminiferous tubule. Although these two events-reproliferation and relocation-are important for establishment of spermatogenesis, they have not been greatly analyzed both in a mechanical and in an endocrine or paracrine aspect. In this study, the relationship between reproliferation and relocation of gonocytes was examined, using the thymidine analog bromodeoxyuridine (BrdU) labeling method and transmission electron microscopy (TEM). BrdU was injected into the fetuses [day 13.5 post coitus (dpc) to 18.5 dpc] and pups [day 0. 5 post partum (dpp) to 6.5 dpp] of C57BL/6J mice. Two hours later, BrdU positive gonocytes were examined immunohistochemically and these data were analyzed. TEM and LM observation was carried out as well. Gonocytes began to relocate on the basement membrane from 18.5 dpc (1.4%) while BrdU-labeled gonocytes were first detected on 1.5 dpp (13.6%). Relocated BrdU-negative gonocytes were recognized from 18.5 dpc (1.4%), and relocated BrdU-labeled gonocytes were recognized from 1.5 dpp (8.4%). On the other hand, non-relocated BrdU-labeled gonocytes were detected from 1.5 dpp (5.2%). Gonocyte relocation began 2 days earlier than reproliferation during the late fetal period. After birth, the two events occurred at random. These results indicate that the reproliferation of the gonocyte does not correlate with relocation. The two events may be regulated by different mechanisms.

CyanoBase, the genome database for Synechocystis sp. strain PCC6803: status for the year 2000

CyanoBase provides an online resource for access to data on genomic information about the cyanobacterium Synechocystis sp. strain PCC6803. The database contains annotations for each protein-coding gene deduced from the entire nucleotide sequence of the genome, gene classification lists, and keyword and similarity search engines. Core portions of CyanoBase consist of annotations for each of the 3168 protein genes deduced from the entire nucleotide sequence of this genome. The contents of each gene were improved by updating with the results of similarity searches and by introducing references for analysis in bioinformatics. The database now contains repository facilities that store and provide experimental information, in addition to providing proposals for the function of each gene. This information should help to avoid unnecessary, overlapping experiments and should assist communication between scientists who wish to elucidate the function of putative genes on the cyanobacteria genome. The current URL of CyanoBase is http://www.kazusa.or.jp:8080/cyano/

[A case of spontaneous pneumothorax in pregnancy]

Spontaneous pneumothorax rarely happened in woman compared to man generally. Furthermore, it is said that spontaneous pneumothorax in the pregnancy is very rare. We experienced a case of spontaneous pneumothorax in 32 weeks gestation. She complains chest pain and dyspnea in hospital because of medication to urgent premature. Throcar catheter has been placed after delivery. Video assisted thoracoscopic bullectomy was performed on the next day of the delivery and discharged 5 days after operation. Treatment of spontaneous pneumothorax in pregnancy was believed to be difficult, but she delivered safely because of being under the tube drainage. We believed that the tube drainage during pregnancy or the operation were recommended for these cases because of security of mother and embryo.

A large scale structural analysis of cDNAs in a unicellular green alga, Chlamydomonas reinhardtii. I. Generation of 3433 non-redundant expressed sequence tags

To understand genetic information carried in a unicellular green alga, Chlamydomonas reinhardtii, normalized and size-selected cDNA libraries were constructed from cells at photoautotrophic growth, and a total of 11,571 5'-end sequence tags were established. These sequences were grouped into 3433 independent EST species. Similarity search against the public non-redundant protein database indicated that 817 groups showed significant similarity to registered sequences, of which 140 were of previously identified C. reinhardtii genes, but the remaining 2616 species were novel sequences. The coverage of full-length protein coding regions was estimated to be over 60%. These cDNA clones and EST sequence information will provide a powerful source for the future genome-wide functional analysis of uncharacterized genes.

Primary structure of hemolytic lectin CEL-III from marine invertebrate Cucumaria echinata and its cDNA: structural similarity to the B-chain from plant lectin, ricin

CEL-III, a galactose/N-acetylgalactosamine (Gal/GalNAc) specific lectin purified from a marine invertebrate Cucumaria echinata has a strong hemolytic activity especially toward human and rabbit erythrocytes. We determined the primary structure of the CEL-III by examining the amino acid sequences of the protein and the nucleotide sequence of the cDNA. The cDNA encoding CEL-III has 1823 nucleotides and an open reading frame of 1296 nucleotides. CEL-III is composed of 432 amino acid residues with a M(r) of 47¿ omitted¿457 and has six internal tandem repeats, each with of 40-50 amino acids, comprising the N-terminal two-thirds of the molecule. Similar repeats are found in the B-chains of cytotoxic plant lectins, such as ricin and abrin, where six repetitive sequences extend throughout the molecules. A hydropathy plot predicts hydrophobic segments in the C-terminal region of CEL-III. These findings suggest that the N-terminal region of CEL-III plays an important role in binding to carbohydrate receptors on the target cell membranes, an event which triggers an intermolecular hydrophobic interaction of the C-terminal region, the result being oligomerization of CEL-III to lead to pore-formation in erythrocyte membrane.

Endothelium-dependent flow-mediated vasodilation in the postprandial state in type 2 diabetes mellitus

This study examined the effects of fat- plus sucrose-rich meals on endothelium-dependent flow-mediated vasodilation in diabetic patients. Flow-mediated vasodilation in the postprandial state decreased significantly, and the decrease correlated inversely with the magnitude of postprandial hyperglycemia, suggesting that endothelial function in diabetic patients becomes impaired postprandially.

Complete structure of the chloroplast genome of Arabidopsis thaliana

The complete nucleotide sequence of the chloroplast genome of Arabidopsis thaliana has been determined. The genome as a circular DNA composed of 154,478 bp containing a pair of inverted repeats of 26,264 bp, which are separated by small and large single copy regions of 17,780 bp and 84,170 bp, respectively. A total of 87 potential protein-coding genes including 8 genes duplicated in the inverted repeat regions, 4 ribosomal RNA genes and 37 tRNA genes (30 gene species) representing 20 amino acid species were assigned to the genome on the basis of similarity to the chloroplast genes previously reported for other species. The translated amino acid sequences from respective potential protein-coding genes showed 63.9% to 100% sequence similarity to those of the corresponding genes in the chloroplast genome of Nicotiana tabacum, indicating the occurrence of significant diversity in the chloroplast genes between two dicot plants. The sequence data and gene information are available on the World Wide Web database KAOS (Kazusa Arabidopsis data Opening Site) at http://www.kazusa.or.jp/arabi/.

Effect of streptozotocin-induced diabetes mellitus on type 1 deiodinase (D1) in inherited D1-deficient mice

We investigated the effects of streptozotocin (STZ)-induced diabetes on thyroid hormone levels, type 1 deiodinase (D1) activity and messenger RNA (mRNA) levels in inherited D1 deficient C3H mice in a comparative manner with control C57 mice. The apparent maximum velocity (Vmax) D1 values in C3H mice were 3% (liver) and 26% (kidney) of those in C57 mice. In C3H mice, similar serum T3, slightly higher T4, and 2.6-fold higher rT3 levels were observed compared with C57 mice. In STZ-induced diabetes, serum T4 level markedly decreased in both C3H and C57 mice. Serum T3 levels in STZ-C3H mice similarly decreased as in STZ-C57 mice. On the other hand, serum rT3 levels increased to 3.3-fold higher in STZ-C3H than in STZ-C57 mice. The Vmax values were decreased to 12% (STZ-C3H) and to 30% (STZ-C57) in liver, and decreased to 33% (both STZ-C3H and STZ-C57) in kidney. The changes in D1 mRNA levels in diabetes versus control were comparable to those of D1 activities in both strains. In summary, similar mechanism(s) to those which decrease the D1 expression and the serum T3 level in diabetes, function in D1 deficient C3H mice as in C57 mice. It appears that hepatic and renal D1 activity alone can not explain the similar reduction in T3 level in STZ-C3H mice and STZ-C57 mice.

Arterial revascularization. 18-year experience with coronary artery bypass grafting in familial hypercholesterolemia

Familial hypercholesterolemia is characterized by a high plasma level of cholesterol and is frequently associated with rapidly progressing coronary heart disease. The internal thoracic artery is recognized as the conduit of choice for coronary artery bypass grafting. This study was performed to determine whether multiple arterial grafting was associated or not with additional benefits for patients with familial hypercholesterolemia. Between June 1980 and March 1998, 95 patients with familial hypercholesterolemia. underwent a total of 103 coronary artery bypass procedures with one hospital death. The patients were divided into 3 groups according to the type of bypass graft. Group 1 included 31 patients with only saphenous vein grafts; Group 2,48 patients with one arterial graft and supplemental vein grafts; and Group 3, 24 patients with multiple arterial grafts. The overall actuarial survival rate was 90.9% at 10 years and 81.8% at 18 years. The overall actuarial freedom from recurrent angina was 68.9% at 10 years and 55.8% at 16 years. The actuarial survival rate in group 2 was higher than that in Group 1 (p < 0.05). There was no difference in the actuarial survival or in the freedom from cardiac events between Group 2 and Group 3. Single arterial grafting improved the long-term survival in patients with familial hypercholesterolemia. However, no additional benefit from multiple arterial grafting was identified.

Structural analysis of Arabidopsis thaliana chromosome 5. IX. Sequence features of the regions of 1,011,550 bp covered by seventeen P1 and TAC clones

In this series of projects sequencing the entire genome of Arabidopsis thaliana chromosome 5, non-redundant P1 and TAC clones have been sequenced according to the fine physical map, and as of May 7, 1999, the sequences of 16.2 Mb representing approximately 60% of chromosome 5 have been accumulated and released at our web site. In parallel, structural features of the sequenced regions have been analyzed by applying a variety of computer programs, and to date we have predicted a total of 2380 potential protein-coding genes in the 10,154,580 bp regions, which are covered by 142 P1 and TAC clones. In this paper, we newly analyzed the structural features of the 1,011,550 bp regions covered by additional 17 P1 and TAC clones, and predicted 298 protein-coding genes. The average density of the genes identified was 1 gene per 3394 bp. Introns were observed in 67% of the genes, and the average number per gene and the average length of the introns were 3.2 and 159 bp, respectively. The gene density became higher than the value estimated in the previously analyzed regions (1 gene per 4,267 bp), as the data in this paper were compiled based on a new standard of gene assignment including the computer-predicted hypothetical genes. The regions also contained 8 tRNA genes when searched by similarity to reported tRNA genes and the tRNA scan-SE program. The sequence data and information on the potential genes are available on the database KAOS (Kazusa Arabidopsis data Opening Site) at http://www.kazusa.or.jp/arabi/.

Effect of triiodothyronine administration on reduced expression of type 1 iodothyronine deiodinase messenger ribonucleic acid in streptozotocin-induced diabetic rats

To examine the mechanism behind a decrease in type 1 iodothyronine deiodinase (D1) gene expression in diabetes mellitus, we evaluated the effect of administering T3 and/or insulin on D1 activity and the mRNA levels in the liver of streptozotocin (STZ)-induced diabetic rats. STZ (100 mg/kg BW) was administered to male Wistar rats, and the rats were divided into four groups as follows: (1) STZ alone, (2) STZ and T3 (5 microg/100 g BW daily for 7 days), (3) STZ and insulin (intermediate-acting insulin, 4 units/100 g BW daily for 7 days), and (4) STZ, T3, and insulin. Blood glucose levels increased in Group 1, but were normalized in Group 3. Serum T3 levels were markedly decreased in Group 1. They were within normal limits 24 hours after the last administration of T3 in Group 2 and after the administration of insulin in Group 3. T3 levels were supranormal in Group 4. TSH levels were normal in Groups 1 and 3, but were suppressed in Groups 2 and 4, suggesting that rats in Groups 2 and 4 were actually in a hyperthyroid state after injecting a large amount of T3. D1 activity in Group 1 was reduced significantly, but it was normal in Groups 2 and 3, and increased in Group 4. D1 mRNA levels in the liver in Group 1 decreased significantly, but they were increased to within normal limits by adding insulin in Group 3. They were also normal in Group 2 where hyperglycemia was evident and rats were hyperthyroid after administering T3. D1 mRNA in Group 4 increased significantly where glucose levels were normal and T3 levels were increased. We suggest that the decrease in hepatic D1 mRNA in STZ-induced diabetic rats is due to metabolic derangement caused by insulin deficiency in addition to a possible decrease in tissue T3 availability.

Complementation of plant mutants with large genomic DNA fragments by a transformation-competent artificial chromosome vector accelerates positional cloning

To accelerate gene isolation from plants by positional cloning, vector systems suitable for both chromosome walking and genetic complementation are highly desirable. Therefore, we developed a transformation-competent artificial chromosome (TAC) vector, pYLTAC7, that can accept and maintain large genomic DNA fragments stably in both Escherichia coli and Agrobacterium tumefaciens. Furthermore, it has the cis sequences required for Agrobacterium-mediated gene transfer into plants. We cloned large genomic DNA fragments of Arabidopsis thaliana into the vector and showed that most of the DNA fragments were maintained stably. Several TAC clones carrying 40- to 80-kb genomic DNA fragments were transferred back into Arabidopsis with high efficiency and shown to be inherited faithfully among the progeny. Furthermore, we demonstrated the practical utility of this vector system for positional cloning in Arabidopsis. A TAC contig was constructed in the region of the SGR1 locus, and individual clones with ca. 80-kb inserts were tested for their ability to complement the gravitropic defects of a homozygous mutant line. Successful complementation enabled the physical location of SGR1 to be delimited with high precision and confidence.

A sequence-ready contig map of the top arm of Arabidopsis thaliana chromosome 3

A fine physical map of the top arm of Arabidopsis thaliana chromosome 3 has been constructed by ordering P1, TAC and BAC clones using the sequences of a variety of DNA markers and end-sequences of clones. The marker sequences used in this study were derived from 58 DNA markers, 93 YAC end-sequences, and 807 end-sequences of P1, TAC and BAC clones. The entire top arm of chromosome 3, except for the centromeric and telomeric regions, was covered by a single contig 13.3 Mb long. This fine physical map will facilitate gene isolation by map-based cloning experiments as well as genome sequencing of the top arm of chromosome 3. The map and end-sequence information are available on the web site KAOS (Kazusa Arabidopsis data Opening Site) at [http://www.kazusa.or.jp/arabi/].

Osteogenic phenotype expression of allogeneic rat marrow cells in porous hydroxyapatite ceramics

Porous hydroxyapatite (HA) ceramics were combined with either allogeneic (ACI) or isogeneic (Fischer 344) rat marrow cells and implanted in subcutaneous sites of Fischer rats. FK506 as an immunosuppressant or saline was administered to the recipient rats. The implanted marrow/HA composites were harvested on day 28 and analyzed for bone-forming capability by determining osteoblastic phenotype expression levels of protein synthesis and gene expression. The alkaline phosphatase (ALP) activity and osteocalcin (OC) contents were very low and mRNAs (Northern blot analysis) were not detected in the allografts without FK506. However, high activity of ALP and high content of OC were found and mRNAs were detected in the allografts with FK506 and in the isografts (with and without FK506). This analysis indicates the osteogenic potential of allogeneic marrow cells in the presence of FK506. The histologic sections revealed that allografts without FK506 did not show bone formation but did show the infiltration of many small cells in the ceramics indicating an immunologic reaction, however, the allografts with FK506 and the isografts (with and without FK506) showed consistent de novo bone formation on the HA pore surface. These results indicate that FK506 can suppress the immunologic reaction in the allografts and induce a favorable conditions to support osteoblastic differentiation of allogeneic rat marrow stromal stem cells on the surface of HA ceramics. Therefore, our study suggests the feasibility of clinical transplantation of allogeneic bone marrow for a selected bone graft in applications using adjuvant systemic immunosuppression.