The SIX5 Protein in Fusarium oxysporum f. sp. cepae Acts as an Avirulence Effector toward Shallot (Allium cepa L. Aggregatum Group)

Fusarium oxysporum f. sp. cepae (Foc) causes basal rot disease in Allium species, including onions (Allium cepa L.) and shallots (A. cepa L. Aggregatum group). Among Allium species, shallots can be crossbred with onions and are relatively more resistant to Foc than onions. Thus, shallots are considered a potential disease-resistant resource for onions. However, the mechanisms underlying the molecular interactions between shallots and Foc remain unclear. This study demonstrated that SIX5, an effector derived from Foc (FocSIX5), acts as an avirulence effector in shallots. We achieved this by generating a FocSIX5 gene knockout mutant in Foc, for which experiments which revealed that it caused more severe wilt symptoms in Foc-resistant shallots than the wild-type Foc and FocSIX5 gene complementation mutants. Moreover, we demonstrated that a single amino acid substitution (R67K) in FocSIX5 was insufficient to overcome shallot resistance to Foc.

Development of a genome-wide marker design workflow for onions and its application in target amplicon sequencing-based genotyping

Onions are one of the most widely cultivated vegetables worldwide; however, the development and utilization of molecular markers have been limited because of the large genome of this plant. We present a genome-wide marker design workflow for onions and its application in a high-throughput genotyping method based on target amplicon sequencing. The efficiency of the method was evaluated by genotyping of F₂ populations. In the marker design workflow, unigene and genomic sequence data sets were constructed, and polymorphisms between parental lines were detected through transcriptome sequence analysis. The positions of polymorphisms detected in the unigenes were mapped onto the genome sequence, and primer sets were designed. In total, 480 markers covering the whole genome were selected. By genotyping an F₂ population, 329 polymorphic sites were obtained from the estimated positions or the flanking sequences. However, missing or sparse marker regions were observed in the resulting genetic linkage map. We modified the markers to cover these regions by genotyping the other F₂ populations. The grouping and order of markers on the linkages were similar across the genetic maps. Our marker design workflow and target amplicon sequencing are useful for genome-wide genotyping of onions owing to their reliability, cost effectiveness, and flexibility.

Insights from the first genome assembly of Onion (Allium cepa)

Onion is an important vegetable crop with an estimated genome size of 16 Gb. We describe the de novo assembly and ab initio annotation of the genome of a doubled haploid onion line DHCU066619, which resulted in a final assembly of 14.9 Gb with an N50 of 464 Kb. Of this, 2.4 Gb was ordered into eight pseudomolecules using four genetic linkage maps. The remainder of the genome is available in 89.6 K scaffolds. Only 72.4% of the genome could be identified as repetitive sequences and consist, to a large extent, of (retro) transposons. In addition, an estimated 20% of the putative (retro) transposons had accumulated a large number of mutations, hampering their identification, but facilitating their assembly. These elements are probably already quite old. The ab initio gene prediction indicated 540,925 putative gene models, which is far more than expected, possibly due to the presence of pseudogenes. Of these models, 47,066 showed RNASeq support. No gene rich regions were found, genes are uniformly distributed over the genome. Analysis of synteny with Allium sativum (garlic) showed collinearity but also major rearrangements between both species. This assembly is the first high-quality genome sequence available for the study of onion and will be a valuable resource for further research.

Insights from the first genome assembly of Onion (Allium cepa)

Onion is an important vegetable crop with an estimated genome size of 16 Gb. We describe the de novo assembly and ab initio annotation of the genome of a doubled haploid onion line DHCU066619, which resulted in a final assembly of 14.9 Gb with an N50 of 464 Kb. Of this, 2.4 Gb was ordered into eight pseudomolecules using four genetic linkage maps. The remainder of the genome is available in 89.6 K scaffolds. Only 72.4% of the genome could be identified as repetitive sequences and consist, to a large extent, of (retro) transposons. In addition, an estimated 20% of the putative (retro) transposons had accumulated a large number of mutations, hampering their identification, but facilitating their assembly. These elements are probably already quite old. The ab initio gene prediction indicated 540,925 putative gene models, which is far more than expected, possibly due to the presence of pseudogenes. Of these models, 47,066 showed RNASeq support. No gene rich regions were found, genes are uniformly distributed over the genome. Analysis of synteny with Allium sativum (garlic) showed collinearity but also major rearrangements between both species. This assembly is the first high-quality genome sequence available for the study of onion and will be a valuable resource for further research.

A Dual-Color Tyr-FISH Method for Visualizing Genes/Markers on Plant Chromosomes to Create Integrated Genetic and Cytogenetic Maps

In situ imaging of molecular markers on a physical chromosome is an indispensable tool for refining genetic maps and validation genome assembly at the chromosomal level. Despite the tremendous progress in genome sequencing, the plant genome assembly at the chromosome level remains a challenge. Recently developed optical and Hi-C mapping are aimed at assistance in genome assembly. For high confidence in the genome assembly at chromosome level, more independent approaches are required. The present study is aimed at refining an ultrasensitive Tyr-FISH technique and developing a reliable and simple method of in situ mapping of a short unique DNA sequences on plant chromosomes. We have carefully analyzed the critical steps of the Tyr-FISH to find out the reasons behind the flaws of this technique. The accurate visualization of markers/genes appeared to be significantly dependent on the means of chromosome slide preparation, probe design and labeling, and high stringency washing. Appropriate adjustment of these steps allowed us to detect a short DNA sequence of 1.6 Kb with a frequency of 51.6%. Based on our results, we developed a more reliable and simple protocol for dual-color Tyr-FISH visualization of unique short DNA sequences on plant chromosomes. This new protocol can allow for more accurate determination of the physical distance between markers and can be applied for faster integration of genetic and cytogenetic maps.

Comprehensive Metabolite Profiling in Genetic Resources of Garlic (Allium sativum L.) Collected from Different Geographical Regions

Garlic (Allium sativum) is the second most important Allium crop that has been used as a vegetable and condiment from ancient times due to its characteristic flavor and taste. Although garlic is a sterile plant that reproduces vegetatively through cloves, garlic shows high biodiversity, as well as phenotypic plasticity and environmental adaptation capacity. To determine the possible mechanism underlying this phenomenon and to provide new genetic materials for the development of a novel garlic cultivar with useful agronomic traits, the metabolic profiles in the leaf tissue of 30 garlic accessions collected from different geographical regions, with a special focus on the Asian region, were investigated using LC/MS. In addition, the total saponin and fructan contents in the roots and cloves of the investigated garlic accessions were also evaluated. Total saponin and fructan contents did not separate the garlic accessions based on their geographical origin, implying that saponin and fructan contents were clone-specific and agroclimatic changes have affected the quantitative and qualitative levels of saponins in garlic over a long history of cultivation. Principal component analysis (PCA) and dendrogram clustering of the LC/MS-based metabolite profiling showed two major clusters. Specifically, many Japanese and Central Asia accessions were grouped in cluster I and showed high accumulations of flavonol glucosides, alliin, and methiin. On the other hand, garlic accessions grouped in cluster II exhibited a high accumulation of anthocyanin glucosides and amino acids. Although most of the accessions were not separated based on country of origin, the Central Asia accessions were clustered in one group, implying that these accessions exhibited distinct metabolic profiles. The present study provides useful information that can be used for germplasm selection and the development of new garlic varieties with beneficial biotic and abiotic stress-adaptive traits.

Metabolome-Based Discrimination Analysis of Shallot Landraces and Bulb Onion Cultivars Associated with Differences in the Amino Acid and Flavonoid Profiles

Shallot landraces and varieties are considered an important genetic resource for Allium breeding due to their high contents of several functional metabolites. Aiming to provide new genetic materials for the development of a novel bulb onion cultivar derived from intraspecific hybrids with useful agronomic traits from shallots, the metabolic profiles in the bulbs of 8 Indonesian shallot landraces and 7 short-day and 3 long-day bulb onion cultivars were established using LC–Q-TOF-MS/MS. Principal component analysis, partial least squares discriminant analysis, and dendrogram clustering analysis showed two major groups; group I contained all shallot landraces and group II contained all bulb onion cultivars, indicating that shallots exhibited a distinct metabolic profile in comparison with bulb onions. Variable importance in the projection and Spearman’s rank correlation indicated that free and conjugated amino acids, flavonoids (especially metabolites having flavonol aglycone), and anthocyanins, as well as organic acids, were among the top metabolite variables that were highly associated with shallot landraces. The absolute quantification of 21 amino acids using conventional HPLC analysis showed high contents in shallots rather than in bulb onions. The present study indicated that shallots reprogrammed their metabolism toward a high accumulation of amino acids and flavonoids as an adaptive mechanism in extremely hot tropical environments.

Multichromosomal structure of the onion mitochondrial genome and a transcript analysis

The structures of plant mitochondrial genomes are more complex than those of animals. One of the reasons for this is that plant mitochondrial genomes typically have many long and short repeated sequences and intra- and intermolecular recombination may create various DNA molecules in this organelle. Recombination may sometimes create a novel gene that causes cytoplasmic male sterility (CMS). The onion has several cytoplasm types, with some causing CMS while others do not. The complete mitochondrial genome sequence of the onion was reported for an inbred line with CMS-S cytoplasm; however, the number of differences between onion strains remains unclear, and studies on purified mitochondrial DNA (mtDNA) have not yet been performed. Furthermore, analyses of transcripts in the mitochondrial genome have not been conducted. In the present study, we examined the mitochondrial genome of the onion variety "Momiji-3" (Allium cepa L.) possessing CMS-S-type cytoplasm using next-generation sequencing (NGS). The "Momiji-3" mitochondrial genome mainly exists as three circles as a result of recombination through repeated sequences and we herein succeeded for the first time in visualizing its structure using pulsed field gel electrophoresis (PFGE). The ability to clarify the structure of the mitochondrial genome is rare in plant mitochondria; therefore, "Momiji-3" represents a good example for elucidating complex plant mitochondrial genomes. We also mapped transcript data to the mitochondrial genome in order to identify the RNA-editing positions in all gene-coding regions and estimate the expression levels of genes. We identified 635 editing positions in gene-coding regions. Start and stop codons were created by RNA editing in six genes (nad1, nad4L, atp6, atp9, ccmFC, and orf725). The transcript amounts of novel open reading frames (ORFs) were all markedly lower than those of functional genes. These results suggest that a new functional gene was not present in the mitochondrial genome of "Momiji-3", and that the candidate gene for CMS is orf725, as previously reported.

RNA-sequencing-based transcriptome and biochemical analyses of steroidal saponin pathway in a complete set of Allium fistulosum-A. cepa monosomic addition lines

The genus Allium is a rich source of steroidal saponins, and its medicinal properties have been attributed to these bioactive compounds. The saponin compounds with diverse structures play a pivotal role in Allium’s defense mechanism. Despite numerous studies on the occurrence and chemical structure of steroidal saponins, their biosynthetic pathway in Allium species is poorly understood. The monosomic addition lines (MALs) of the Japanese bunching onion (A. fistulosum, FF) with an extra chromosome from the shallot (A. cepa Aggregatum group, AA) are powerful genetic resources that enable us to understand many physiological traits of Allium. In the present study, we were able to isolate and identify Alliospiroside A saponin compound in A. fistulosum with extra chromosome 2A from shallot (FF2A) and its role in the defense mechanism against Fusarium pathogens. Furthermore, to gain molecular insight into the Allium saponin biosynthesis pathway, high-throughput RNA-Seq of the root, bulb, and leaf of AA, MALs, and FF was carried out using Illumina's HiSeq 2500 platform. An open access Allium Transcript Database (Allium TDB, http://alliumtdb.kazusa.or.jp) was generated based on RNA-Seq data. The resulting assembled transcripts were functionally annotated, revealing 50 unigenes involved in saponin biosynthesis. Differential gene expression (DGE) analyses of AA and MALs as compared with FF (as a control) revealed a strong up-regulation of the saponin downstream pathway, including cytochrome P450, glycosyltransferase, and beta-glucosidase in chromosome 2A. An understanding of the saponin compounds and biosynthesis-related genes would facilitate the development of plants with unique saponin content and, subsequently, improved disease resistance.

Dissection of Trichoderma longibrachiatum-induced defense in onion (Allium cepa L.) against Fusarium oxysporum f. sp. cepa by target metabolite profiling

Trichoderma spp. are versatile opportunistic plant symbionts that can cause substantial changes in the metabolism of host plants, thereby increasing plant growth and activating plant defense to various diseases. Target metabolite profiling approach was selected to demonstrate that Trichoderma longibrachiatum isolated from desert soil can confer beneficial agronomic traits to onion and induce defense mechanism against Fusarium oxysporum f. sp. cepa (FOC), through triggering a number of primary and secondary metabolite pathways. Onion seeds primed with Trichoderma T1 strain displayed early seedling emergence and enhanced growth compared with Trichoderma T2-treatment and untreated control. Therefore, T1 was selected for further investigations under greenhouse conditions, which revealed remarkable improvement in the onion bulb growth parameters and resistance against FOC. The metabolite platform of T1-primed onion (T1) and T1-primed onion challenged with FOC (T1+FOC) displayed significant accumulation of 25 abiotic and biotic stress-responsive metabolites, representing carbohydrate, phenylpropanoid and sulfur assimilation metabolic pathways. In addition, T1- and T1+FOC-treated onion plants showed discrete antioxidant capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) compared with control. Our findings demonstrated the contribution of T. longibrachiatum to the accumulation of key metabolites, which subsequently leads to the improvement of onion growth, as well as its resistance to oxidative stress and FOC.

Diversity evaluation based on morphological, physiological and isozyme variation in genetic resources of garlic (Allium sativum L.) collected worldwide

The aim of this study was to obtain primary information about the global diversity of garlic (Allium sativum L.) by evaluating morphological, physiological and isozyme variation. A total of 107 garlic accessions collected worldwide were grown in Yamaguchi, Japan. Five morphological traits (bulb weight, bulb diameter, number of cloves per bulb, number of bulbils and scape length) and one physiological trait (bolting period) of the collected garlic showed wide variation. Meanwhile, a total of 140 garlic accessions, including the 107 mentioned above, were characterized by leucine aminopeptidase (LAP) and phosphoglucoisomerase (PGI) isozyme analyses; they clearly showed polymorphisms in putative isozyme loci (Lap-1, Lap-2 and Pgi-1). Allelic frequencies were estimated in each group of accessions categorized by their geographical origin, and the observed (H_o) and expected (H_e) heterozygosities were calculated. The allelic frequencies differed between groups. A principal component analysis based on morpho-physiological data indicated a grouping of the garlic accessions into Central Asian and Northern Mediterranean groups as well as others. We discuss the roles of artificial and natural selection that may have caused differentiation in these traits, on the assumption that ancestral domesticated garlic populations have adapted in various regions using standing variation or mutations that accumulated during expansion, and have evolved along with human-preferred traits over a long history of cultivation.

Screening and incorporation of rust resistance from Allium cepa into bunching onion (Allium fistulosum) via alien chromosome addition

Bunching onion (Allium fistulosum L.; 2n = 16), bulb onion (Allium cepa L. Common onion group), and shallot (Allium cepa L. Aggregatum group) cultivars were inoculated with rust fungus, Puccinia allii, isolated from bunching onion. Bulb onions and shallots are highly resistant to rust, suggesting they would serve as useful resources for breeding rust resistant bunching onions. To identify the A. cepa chromosome(s) related to rust resistance, a complete set of eight A. fistulosum - shallot monosomic alien addition lines (MAALs) were inoculated with P. allii. At the seedling stage, FF+1A showed a high level of resistance in controlled-environment experiments, suggesting that the genes related to rust resistance could be located on shallot chromosome 1A. While MAAL, multi-chromosome addition line, and hypoallotriploid adult plants did not exhibit strong resistance to rust. In contrast to the high resistance of shallot, the addition line FF+1A+5A showed reproducibly high levels of rust resistance.

Genetic and Pathogenic Variability of Fusarium oxysporum f. sp. cepae Isolated from Onion and Welsh Onion in Japan

Fusarium oxysporum f. sp. cepae causes Fusarium basal rot in onion (common onion) and Fusarium wilt in Welsh onion. Although these diseases have been detected in various areas in Japan, knowledge about the genetic and pathogenic variability of F. oxysporum f. sp. cepae is very limited. In this study, F. oxysporum f. sp. cepae was isolated from onion and Welsh onion grown in 12 locations in Japan, and a total of 55 F. oxysporum f. sp. cepae isolates (27 from onion and 28 from Welsh onion) were characterized based on their rDNA intergenic spacer (IGS) and translation elongation factor-1α (EF-1α) nucleotide sequences, vegetative compatibility groups (VCGs), and the presence of the SIX (secreted in xylem) homologs. Phylogenetic analysis of IGS sequences showed that these isolates were grouped into eight clades (A to H), and 20 onion isolates belonging to clade H were monophyletic and assigned to the same VCG. All the IGS-clade H isolates possessed homologs of SIX3, SIX5, and SIX7. The SIX3 homolog was located on a 4 Mb-sized chromosome in the IGS-clade H isolates. Pathogenicity tests using onion seedlings showed that all the isolates with high virulence were in the IGS-clade H. These results suggest that F. oxysporum f. sp. cepae isolates belonging to the IGS-clade H are genetically and pathogenically different from those belonging to the other IGS clades.

Compartmentation and localization of bioactive metabolites in different organs of Allium roylei

To investigate the involvement of Allium roylei metabolites in the plant's defenses, a comprehensive analysis of the content of cysteine sulfoxides, flavonols, polyphenols, ascorbic acid, and saponins was carried out in the various organs of this species. Metabolomics high performance liquid chromatography (HPLC), spectral-based analysis, and histochemcial studies have given important insight to the validity of saponins as a key component involved in plant protection. The root-basal stem, bulb, and leaf extracts exhibited 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with inhibition concentration (IC(50)) ranging from 0.649 to 0.757 mg/mL. The antimicrobial properties of the saponin and flavonoid crude extracts were evaluated. The saponin extracts demonstrated significant antifungal activity depending on the applied concentration, and the growth inhibition rate of the tested fungal pathogens ranged from 1.07 to 47.76%. No appreciable antibacterial activity was recorded in the same sample.

Supplementation with Japanese bunching onion (Allium fistulosum L.) expressing a single alien chromosome from shallot increases the antioxidant activity of Kamaboko fish jelly paste in vitro

Kamaboko is a traditional type of processed seafood made from fish jelly paste that is unique to Japan. We supplemented Kamaboko with Japanese bunching onion (Allium fistulosum L.) with an alien monosome from shallot (Allium cepa L. Aggregatum group) and we measured in vitro the oxygen radical absorbance capacity (ORAC) value, an index of antioxidant activity. We also evaluated the results of sensory testing. The ORAC value of plain Kamaboko was 166±14 μmol trolox equivalent (TE)/100 g fresh weight (FW). The values of the edible Alliaceae powder, i.e., Japanese bunching onion (JBO, genome FF, 2n=2x=16) and the alien addition line of JBO carrying the 6A chromosome from shallot (FF+6A, 2n=2x+1=17), were 6,659±238 and 14,096±635 μmol TE/100 g dry weight (DW). We hypothesized that the 6A chromosome encoded the enhancement of polyphenol production. Subsequently, we created Kamaboko containing 4.8% JBO powder or 4.8% FF+6A powder. The ORAC value of each modified Kamaboko product was increased to 376±24 μmol TE/100 g FW for the JBO powder and to 460±16 μmol TE/100 g FW for the FF+6A powder, respectively. We next created Kamaboko containing 9.0% JBO powder or 9.0% FF+6A powder and the ORAC values of the respective modified Kamaboko products was increased to 671±16 and 740±21 μmol TE/100 g FW, i.e., 4.1- and 4.5-times the value of plain Kamaboko. Consequently, taking into consideration the sensory evaluation regarding taste and appearance as well, the use of Kamaboko supplemented with 4.8% FF+6A powder is recommended.

Identification and biological activity of antifungal saponins from shallot ( Allium cepa L. Aggregatum group)

The n-butanol extract of shallot basal plates and roots showed antifungal activity against plant pathogenic fungi. The purified compounds from the extract were examined for antifungal activity to determine the predominant antifungal compounds in the extract. Two major antifungal compounds purified were determined to be alliospiroside A (ALA) and alliospiroside B. ALA had prominent antifungal activity against a wide range of fungi. The products of acid hydrolysis of ALA showed a reduced antifungal activity, suggesting that the compound's sugar chain is essential for its antifungal activity. Fungal cells treated with ALA showed rapid production of reactive oxygen species. The fungicidal action of ALA was partially inhibited by a superoxide scavenger, Tiron, suggesting that superoxide anion generation in the fungal cells may be related to the compound's action. Inoculation experiments showed that ALA protected strawberry plants against Colletotrichum gloeosporioides , indicating that ALA has the potential to control anthracnose of the plant.

Discovery of a new source of resistance to Fusarium oxysporum, cause of Fusarium wilt in Allium fistulosum, located on chromosome 2 of Allium cepa Aggregatum group

This study was carried out to evaluate the antifungal effect of Allium cepa Aggregatum group (shallot) metabolites on Fusarium oxysporum and to determine the shallot chromosome(s) related to Fusarium wilt resistance using a complete set of eight Allium fistulosum - shallot monosomic addition lines. The antifungal effects of hexane, butanol, and water extraction fractions from bulbs of shallot on 35 isolates of F. oxysporum were examined using the disc diffusion method. Only hexane and butanol fractions showed high antifungal activity. Shallot showed no symptom of disease after inoculation with F. oxysporum f. sp. cepae. The phenolic content of the roots and the saponin content of root exudates of inoculated shallot increased to much higher levels than those of the control at 3 days after inoculation. Application of freeze-dried shallot root exudates to seeds of A. fistulosum soaked in a spore suspension of F. oxysporum resulted in protection of seedlings against infection. Among eight monosomic addition lines and A. fistulosum, FF+2A showed the highest resistance to Fusarium wilt. This monosomic addition line also showed a specific saponin band derived from shallot on the thin layer chromatography profile of saponins in the eight monosomic addition lines. The chromosome 2A of shallot might possess some of the genes related to Fusarium wilt resistance.

Genotypic variation in sulfur assimilation and metabolism of onion (Allium cepa L.) III. Characterization of sulfite reductase

Genomic and cDNA sequences corresponding to a ferredoxin-sulfite reductase (SiR) have been cloned from bulb onion (Allium cepa L.) and the expression of the gene and activity of the enzyme characterized with respect to sulfur (S) supply. Cloning, mapping and expression studies revealed that onion has a single functional SiR gene and also expresses an unprocessed pseudogene (φ-SiR). Northern and qPCR analysis revealed differences in expression pattern between the SiR gene and the pseudogene. Western analysis using antibodies raised to a recombinant SiR revealed that the enzyme is present in chloroplasts and phylogenetic analysis has shown that the onion protein groups with lower eudicots. In hydroponically-grown plants, levels of SiR transcripts were significantly higher in the roots of S-sufficient when compared with S-deficient plants of the pungent cultivar 'W202A' but not the less pungent cultivar 'Texas Grano'. In these same treatments, a higher level of enzyme activity was observed in the S-sufficient treatment in leaves of both cultivars before and after bulbing. In a factorial field trial with and without sulfur fertilization, a statistically significant increase in SiR activity was observed in the leaves of the pungent cultivar 'Kojak' in response to added S but not in the less pungent cultivar 'Encore'.

AlliumMap-A comparative genomics resource for cultivated Allium vegetables

Background

Vegetables of the genus Allium are widely consumed but remain poorly understood genetically. Genetic mapping has been conducted in intraspecific crosses of onion (Allium cepa L.), A. fistulosum and interspecific crosses between A. roylei and these two species, but it has not been possible to access genetic maps and underlying data from these studies easily.

Description

An online comparative genomics database, AlliumMap, has been developed based on the GMOD CMap tool at http://alliumgenetics.org. It has been populated with curated data linking genetic maps with underlying markers and sequence data from multiple studies. It includes data from multiple onion mapping populations as well as the most closely related species A. roylei and A. fistulosum. Further onion EST-derived markers were evaluated in the A. cepa x A. roylei interspecific population, enabling merging of the AFLP-based maps. In addition, data concerning markers assigned in multiple studies to the Allium physical map using A. cepa-A. fistulosum alien monosomic addition lines have been compiled. The compiled data reveal extensive synteny between onion and A. fistulosum.

Conclusions

The database provides the first online resource providing genetic map and marker data from multiple Allium species and populations. The additional markers placed on the interspecific Allium map confirm the value of A. roylei as a valuable bridge between the genetics of onion and A. fistulosum and as a means to conduct efficient mapping of expressed sequence markers in Allium. The data presented suggest that comparative approaches will be valuable for genetic and genomic studies of onion and A. fistulosum. This online resource will provide a valuable means to integrate genetic and sequence-based explorations of Allium genomes.

Alien genes introgression and development of alien monosomic addition lines from a threatened species, Allium roylei Stearn, to Allium cepa L

To produce alien monosomic addition lines (AMALs) of Allium cepa (genomes CC, 2n = 2x = 16) carrying extrachromosomes from Allium roylei (RR, 2n = 2x = 16), reciprocal backcrossing of allotriploids (2n = 24, CCR) with diploids (2n = 16, CC) and selfing of a single allotriploid were carried out. The chromosome numbers in the BC(2)F(1) and BC(1)F(2) progenies ranged from 16 to 32. Forty-eight plants were recorded to possess 2n = 17 among a total of 169 plants in observation. Through the analyses of isozymes, expressed sequence tag (EST) markers, and karyotypes, all eight possible types of A. cepa-A. roylei monosomic addition lines (CC+1R-CC+8R) could be identified. Seven types of representative AMALs (without CC+2R) were used for the GISH analysis of somatic chromosomes. Except for CC+6R, all AMALs showed an entire (unrecombined) extrachromosome from A. roylei in the integral diploid background of A. cepa. A single recombination between A. cepa and A. roylei was observed on the extrachromosome in the remaining type. All alloplasmic AMALs possessing A. roylei cytoplasm showed high or complete pollen sterility. Only the autoplasmic CC+4R with A. cepa cytoplasm possessed relatively high pollen fertility. The bulbs of CC+4R displayed the distinct ovoid shape that discriminates them from spherical or oval ones in other AMALs. Downy mildew screening in the field showed higher resistance in A. roylei, a hypo-allotriploid (CCR-nR, 2n = 23), and an allotriploid (CCR, 2n = 24). Meanwhile, no complete resistance was found in some AMALs examined. This was the first trial toward the establishment of a complete set of A. cepa-A. roylei monosomic additions.

Direct determination of the chromosomal location of bunching onion and bulb onion markers using bunching onion-shallot monosomic additions and allotriploid-bunching onion single alien deletions

To determine the chromosomal location of bunching onion (Allium fistulosum L.) simple sequence repeats (SSRs) and bulb onion (A. cepa L.) expressed sequence tags (ESTs), we used a complete set of bunching onion-shallot monosomic addition lines and allotriploid bunching onion single alien deletion lines as testers. Of a total of 2,159 markers (1,198 bunching onion SSRs, 324 bulb onion EST-SSRs and 637 bulb onion EST-derived non-SSRs), chromosomal locations were identified for 406 markers in A. fistulosum and/or A. cepa. Most of the bunching onion SSRs with identified chromosomal locations showed polymorphism in bunching onion (89.5%) as well as bulb onion lines (66.1%). Using these markers, we constructed a bunching onion linkage map (1,261 cM), which consisted of 16 linkage groups with 228 markers, 106 of which were newly located. All linkage groups of this map were assigned to the eight basal Allium chromosomes. In this study, we assigned 513 markers to the eight chromosomes of A. fistulosum and A. cepa. Together with 254 markers previously located on a separate bunching onion map, we have identified chromosomal locations for 766 markers in total. These chromosome-specific markers will be useful for the intensive mapping of desirable genes or QTLs for agricultural traits, and to obtain DNA markers linked to these.

Molecular and biochemical identification of alien chromosome additions in shallot (Allium cepa L. Aggregatum group) carrying extra chromosome(s) of bunching onion (A. fistulosum L.)

To develop the bunching onion (Allium fistulosum L.; genomes, FF) chromosome-specific genetic markers for identifying extra chromosomes, eight shallot (A. cepa L. Aggregatum group; genomes, AA)--A. fistulosum monosomic addition plants (AA+nF) and 62 shallot--A. fistulosum single-alien deletion plants (AAF-nF) were analyzed by 23 different chromosome-specific genetic markers of shallot. The eight monosomic addition plants consisted of one AA+2F, two AA+6F, and five AA+8F. Of the 62 single-alien deletion plants, 60 could be identified as six different single-alien deletion lines (AAF-1F, -3F, -4F, -6F, -7F, and -8F) out of the eight possible types. Several single-alien deletion lines were classified on the basis of leaf and bulb characteristics. AAF-8F had the largest number of expanded leaves of five deletion plants. AAF-7F grew most vigorously, as expressed by its long leaf blade and biggest bulb size. AAF-4F had very small bulbs. AAF-7F and AAF-8F had different bulbs from those of shallot as well as other types of single-alien deletion lines in skin and outer scale color. Regarding the sugar content of the bulb tissues, the single-alien deletion lines showed higher fructan content than shallot. Moreover, shallot could not produce fructan with degree of polymerization (DP) 12 or higher, although the single-alien deletion lines showed DP 20 or higher. The content of S-alk(en)yl-L-cysteine sulfoxide (ACSO) in the single-alien deletion lines was significantly lower than that in shallot. These results indicated that chromosomes from A. fistulosum might carry anonymous factors to increase the highly polymerized fructan production and inhibit the synthesis of ACSO in shallot bulbs. Accordingly, alien chromosomes from A. fistulosum in shallot would contribute to modify the quality of shallot bulbs.

Construction of SSR-based chromosome map in bunching onion (Allium fistulosum)

We have constructed a linkage map of bunching onion (Allium fistulosum L., 2n = 16) using an F(2) population of 225 plants. The map consists of 17 linkage groups with 212 bunching onion SSR markers and 42 bulb onion (A. cepa L.) SSR, InDel, CAPS or dCAPS markers, covering 2,069 cM. This is the first report of a linkage map mainly based on SSR markers in the genus Allium. With the 103 anchor markers [81 bunching onion SSRs, 11 bulb onion SSRs and 11 bulb onion non-SSRs (1 InDel, 9 CAPSs and 1 dCAPS)] whose chromosome assignments were identified in A. cepa and/or A. fistulosum, via the use of several kinds of Allium alien addition lines, 16 of the 17 linkage groups were connected to the 8 basic chromosomes of A. cepa.

Biochemical and genetic analysis of carbohydrate accumulation in Allium cepa L

Onion and shallot (Allium cepa L.) exhibit wide variation in bulb fructan content, and the Frc locus on chromosome 8 conditions much of this variation. To understand the biochemical basis of Frc, we conducted biochemical and genetic analyses of Allium fistulosum (FF)-shallot (A. cepa Aggregatum group) alien monosomic addition lines (AALs; FF+1A-FF+8A) and onion mapping populations. Sucrose and fructan levels in leaves of FF+2A were significantly lower than in FF throughout the year, and the springtime activity of acid invertase was also lower. FF+8A showed significantly higher winter sucrose accumulation and sucrose phosphate synthase (SPS) activity. Inbred high fructan (Frc_) lines from the 'W202Ax Texas Grano 438' onion population exhibited significantly higher sucrose levels prior to bulbing than low fructan (frcfrc) lines. Sucrose synthase (SuSy) activity in these lines was correlated with leaf hexose content but not with Frc phenotype. Markers for additional candidate genes for sucrose metabolism were obtained by cloning a major SPS expressed in onion leaf and exhaustively mining onion expressed sequence tag resources. SPS and SuSy loci were assigned to chromosome 8 and 6, respectively, using AALs and linkage mapping. Further loci were assigned, using AALs, to chromosomes 1 (sucrose phosphate phosphatase), 2 (SuSy and three invertases) and 8 (neutral invertase). The concordance between chromosome 8 localization of SPS and elevated leaf sucrose levels conditioned by high fructan alleles at the Frc locus in bulb onion or alien monosomic additions of chromosome 8 in A. fistulosum suggest that the Frc locus may condition variation in SPS activity.

Complete assignment of structural genes involved in flavonoid biosynthesis influencing bulb color to individual chromosomes of the shallot (Allium cepa L.)

We analyzed Japanese bunching onion (Allium fistulosum L.) - shallot (Allium cepa L. Aggregatum group) alien chromosome addition lines in order to assign the genes involved in the flavonoid biosynthesis pathway to chromosomes of the shallot. Two complete sets of alien monosomic additions (2n = 2x + 1 = 17) were used for determining the chromosomal locations of several partial sequences of candidate genes, CHS, CHI, F3H, DFR, and ANS via analyses of PCR-based markers. The results of DNA marker analyses showed that the CHS-A, CHS-B, CHI, F3H, DFR, and ANS genes should be assigned to chromosomes 2A, 4A, 3A, 3A, 7A, and 4A, respectively. HPLC analyses of 14 A. fistulosum - shallot multiple alien additions (2n = 2x + 2 - 2x + 7 = 18 - 23) were conducted to identify the anthocyanin compounds produced in the scaly leaves. A direct comparison between the genomic constitution and the anthocyanin compositions of the multiple additions revealed that a 3GT gene for glucosylation of anthocyanidin was located on 4A. Thus, we were able to assign all structural genes involved in flavonoid biosynthesis influencing bulb color to individual chromosomes of A. cepa.

Once-daily administration of fluticasone propionate does not worsen controlled airway hyperresponsiveness in patients with asthma

BACKGROUND

Inhaled steroids are currently the most important drugs for asthma patients, but compliance tends to be low. Compliance could be improved by reducing the number of daily administrations.

OBJECTIVES

In the present study, we compared once- and twice-daily administration of fluticasone propionate (FP) to determine the differences in efficacy.

METHODS

Subjects were 40 patients diagnosed with bronchial asthma with stable symptoms and pulmonary functions who were on twice-daily FP administration of 100 microg. There were 14 men and 26 women ranging from 29 to 72 years of age. After a 4-week observation period, subjects were randomized into two administration groups by the envelope method and followed for 8 weeks: group A, once-daily administration (200 microg of FP at night), and group B, twice-daily administration (100 microg of FP in the morning and at night). Clinical symptoms, pulmonary functions and airway responsiveness were compared between these two groups.

RESULTS

No significant deterioration in clinical symptoms, pulmonary functions and airway responsiveness were observed in group A compared with group B.

CONCLUSIONS

These results demonstrate that once-daily FP administration is as effective as twice-daily administration, and that it may improve the compliance for inhaled steroids.

Genetic mapping of a major gene affecting onion bulb fructan content

The non-structural dry matter content of onion bulbs consists principally of fructose, glucose, sucrose and fructans. The objective of this study was to understand the genetic basis for the wide variation observed in the relative amounts of these carbohydrates. Bulb carbohydrate composition was evaluated in progeny from crosses between high dry matter storage onion varieties and sweet, low dry matter varieties. When samples were analysed on a dry weight basis, reducing sugar and fructan content exhibited high negative correlations and bimodal segregation suggestive of the action of a major gene. A polymorphic SSR marker, ACM235, was identified which exhibited strong disequilibrium with bulb fructan content in F(2:3) families from the 'W202A' x 'Texas Grano 438' mapping population evaluated in two environments. This marker was mapped to chromosome 8 in the interspecific population 'Allium cepa x A. roylei'. Mapping in the 'Colossal Grano PVP' x 'Early Longkeeper P12' F2 population showed that a dominant major gene conditioning high-fructan content lay in the same genomic region. QTL analysis of total bulb fructan content in the intraspecific mapping population 'BYG15-23' x 'AC43' using a complete molecular marker map revealed only one significant QTL in the same chromosomal region. This locus, provisionally named Frc, may account for the major phenotypic differences in bulb carbohydrate content between storage and sweet onion varieties.

Direct comparison between genomic constitution and flavonoid contents in Allium multiple alien addition lines reveals chromosomal locations of genes related to biosynthesis from dihydrokaempferol to quercetin glucosides in scaly leaf of shallot (Allium cepa L.)

The extrachromosome 5A of shallot (Allium cepa L., genomes AA) has an important role in flavonoid biosynthesis in the scaly leaf of Allium fistulosum-shallot monosomic addition lines (FF+nA). This study deals with the production and biochemical characterisation of A. fistulosum-shallot multiple alien addition lines carrying at least 5A to determine the chromosomal locations of genes for quercetin formation. The multiple alien additions were selected from the crossing between allotriploid FFA (female symbol) and A. fistulosum (male symbol). The 113 plants obtained from this cross were analysed by a chromosome 5A-specific PGI isozyme marker of shallot. Thirty plants were preliminarily selected for an alien addition carrying 5A. The chromosome numbers of the 30 plants varied from 18 to 23. The other extrachromosomes in 19 plants were completely identified by using seven other chromosome markers of shallot. High-performance liquid chromatography analyses of the 19 multiple additions were conducted to identify the flavonoid compounds produced in the scaly leaves. Direct comparisons between the chromosomal constitution and the flavonoid contents of the multiple alien additions revealed that a flavonoid 3'-hydroxylase (F3'H) gene for the synthesis of quercetin from kaempferol was located on 7A and that an anonymous gene involved in the glucosidation of quercetin was on 3A or 4A. As a result of supplemental SCAR analyses by using genomic DNAs from two complete sets of A. fistulosum-shallot monosomic additions, we have assigned F3'H to 7A and flavonol synthase to 4A.

Control of isoperoxidases involved in chlorophyll degradation of stored broccoli (Brassica oleracea) florets by heat treatment

Changes in isoperoxidases involved in chlorophyll (Chl) degradation of stored broccoli (Brassica oleracea L.) florets and their control by heat treatment (HT) were determined. Chl a and b contents in non-heat-treated broccoli florets decreased greatly after 2 days at 15 degrees C, whereas the contents in heat-treated florets (50 degrees C for 2 h) showed almost no change. Three isoperoxidases involved in Chl degradation were detected by means of molecular exclusion chromatography and the molecular weights of those isoperoxidases were about 95 (Type I), 67 (Type II) and 56 (Type III) kDa, respectively. Only Type I was detected in broccoli florets immediately after harvest, and its activity in non-heat-treated broccoli increased greatly during storage. Both Type II and Type III were present in non-heat-treated broccoli with floret senescence. HT suppressed the enhancement of all of the isoperoxidase activities. Cycloheximide treatment also effectively retarded the increase in Types I, II and III isoperoxidase activities concomitant with the suppression of floret yellowing. The K(m) values corresponding to Chl a of Type II and Type III were lower than Type I, and the V(max)/K(m) values corresponding to Chl a of Type II and Type III were higher than Type I. This suggests that both Types II and III could be closely associated with Chl degradation in broccoli florets and that HT might inhibit floret senescence by suppression of isoperoxidase activities.

Genetic mapping of expressed sequences in onion and in silico comparisons with rice show scant colinearity

The Poales (which include the grasses) and Asparagales [which include onion (Allium cepa L.) and other Allium species] are the two most economically important monocot orders. Enormous genomic resources have been developed for the grasses; however, their applicability to other major monocot groups, such as the Asparagales, is unclear. Expressed sequence tags (ESTs) from onion that showed significant similarities (80% similarity over at least 70% of the sequence) to single positions in the rice genome were selected. One hundred new genetic markers developed from these ESTs were added to the intraspecific map derived from the BYG15-23xAC43 segregating family, producing 14 linkage groups encompassing 1,907 cM at LOD 4. Onion linkage groups were assigned to chromosomes using alien addition lines of Allium fistulosum L. carrying single onion chromosomes. Visual comparisons of genetic linkage in onion with physical linkage in rice revealed scant colinearity; however, short regions of colinearity could be identified. Our results demonstrate that the grasses may not be appropriate genomic models for other major monocot groups such as the Asparagales; this will make it necessary to develop genomic resources for these important plants.

Effect of single alien chromosome from shallot (Allium cepa L. Aggregatum group) on carbohydrate production in leaf blade of bunching onion (A. fistulosum L.)

We used a complete set of Allium fistulosum - shallot (A. cepa Aggregatum group) monosomic addition lines (FF+1A - FF+8A) to identify shallot chromosomes affecting the production of sugars. In the alien addition lines grown over two years in an experimental field at Yamaguchi University (34 degrees N, 131 degrees E), shallot chromosomes 2A and 8A altered sugar contents in leaf-bunching onion (A. fistulosum). Except for FF+2A, every monosomic addition accumulated non-reducing sugars in winter leaf blades. FF+8A caused an increase in the amounts of non-reducing sugars in the winter. FF+2A hardly produced non-reducing sugar throughout the two-year study. These results indicated that genes related to non-reducing sugar metabolism are located on the 2A and 8A chromosomes. The results of regression analyses using 2002 data on A. fistulosum and the monosomic addition set revealed a correlation (r = 0.63 +/- 0.07; mean +/- SE., n = 9) between reducing sugar and monosaccharide (Glc+Fru) contents but no correlation between non-reducing sugar and sucrose contents. This result indicates the existence of other polysaccharides (e.g., scorodose) as non-reducing sugars in the leaf blade.

Production and characterization of alien chromosome additions in shallot (Allium cepa L. Aggregatum group) carrying extra chromosome(s) of Japanese bunching onion (A. fistulosum L.)

First and second backcrosses of amphidiploid hybrids (2n = 4x = 32, genomes AAFF) between shallot (Allium cepa Aggregatum group) and A. fistulosum were conducted to produce A. cepa - A. fistulosum alien addition lines. When shallot (A. cepa Aggregatum group) was used as a pollinator, the amphidiploids and allotriploids set germinable BC(1) and BC(2) seeds, respectively. The 237 BC(1) plants mainly consisted of 170 allotriploids (2n = 3x = 24, AAF) and 42 hypo-allotriploids possessing 23 chromosomes, i.e., single-alien deletions (2n = 3x-1 = 23, AAF-nF). The single-alien deletions in the BC(1) progeny showed dwarfing characteristics and were discriminated from the allotriploids (2n = 24) and hyper-allotriploids (2n = 25) by means of flow cytometric analysis. The chromosome numbers of 46 BC(2) seedlings varied from 16 to 24. Eight monosomic additions (2n = 2x+1 = 17, AA+nF) and 20 single-alien deletions were found in these BC(2) seedlings. Consequently, six kinds of A. cepa - A. fistulosum alien chromosome additions possessing different chromosome numbers (2n = 17, 18, 20, 21, 22, 23) were recognized in the BC(1) and BC(2) populations. A total of 79 aneuploids, including 62 single-alien deletions, were analyzed by a chromosome 6F-specific isozyme marker (Got-2) in order to recognize its existence in their chromosome complements. This analysis revealed that two out of 62 single-alien deletions did not possess 6F. One (AAF-6F) out of the possible eight single-alien deletions could be identified at first. The present study is a first step toward the development of a useful tool, such as a complete set of eight different single-alien deletions, for the rapid chromosomal assignment of genes and genetic markers in A. fistulosum.

Transmission of alien chromosomes from selfed progenies of a complete set of Allium monosomic additions: the development of a reliable method for the maintenance of a monosomic addition set

Selfed progeny of a complete set of Allium fistulosum - Allium cepa monosomic addition lines (2n = 2x + 1 = 17, FF+1A-FF+8A) were produced to examine the transmission rates of respective alien chromosomes. All eight types of the selfed monosomic additions set germinable seeds. The numbers of chromosomes (2n) in the seedlings were 16, 17, or 18. The eight extra chromosomes varied in transmission rate (%) from 9 (FF+2A) to 49 (FF+8A). The complete set of monosomic additions was reproduced successfully by self-pollination. A reliable way to maintain a set of Allium monosomic additions was developed using a combination of two crossing methods, selfing and female transmission. FF+8A produced two seedlings with 18 chromosomes. Cytogenetical analyses, including GISH, showed that the seedlings were disomic addition plants carrying two entire homologous chromosomes from A. cepa in an integral diploid background of A. fistulosum. Flow cytometry analysis showed that a double dose of the alien 8A chromosome caused fluorescence intensity values spurring in DNA content, and isozyme analysis showed increased glutamate dehydrogenase activity at the gene locus Gdh-1.

Molecular followup of newly diagnosed bladder cancer using urine samples

PURPOSE

Patients with superficial bladder cancer can be treated with transurethral resection. However, 50% to 70% of them have intravesical recurrence after transurethral resection and muscle invasive disease develops in 10% to 20%, which is eventually indicated for radical cystectomy. Therefore, reliable predictors of intravesical recurrence are required for management of superficial bladder cancer. We investigated whether detection of the loss of heterozygosity in urine samples would be available as a sensitive diagnostic modality for recurrence of bladder cancer.

MATERIALS AND METHODS

Urine samples, cancer tissue and peripheral blood lymphocytes were obtained from 37 patients with newly diagnosed bladder cancer, and analyzed for the loss of heterozygosity on chromosomes 9 and 17p by single strand DNA conformation polymorphism analysis.

RESULTS

Chromosomal loss was detected on 24 (65%) cancer tissues and 26 (70%) urine samples. The loss of heterozygosity on chromosome 17p was detected in 19 (51%) urine samples, mostly in cancers with higher grades and/or stages. During postoperative followup of 24 patients with superficial bladder cancer who had undergone transurethral resection, intravesical recurrence did not develop in 9 of 10 without chromosomal aberrations in urine samples. In contrast, intravesical recurrence developed in 11 of 14 patients who had a loss of heterozygosity in urine samples. This loss showed a significant correlation with the intravesical disease-free period (p = 0.004). Multivariate analysis revealed that the loss of heterozygosity in urine samples was a significant predictor of intravesical recurrence.

CONCLUSIONS

Detection of the loss of heterozygosity in urine samples is available as a sensitive marker for predicting intravesical recurrence of superficial bladder cancer.

N-omega-nitro-L-arginine methyl ester increases airway responsiveness to serotonin but not to acetylcholine in cats in vivo

BACKGROUND

We previously reported that N(omega)-nitro-L-arginine methyl ester (L-NAME) enhances airway responsiveness to inhaled serotonin in cats treated with atropine and propranolol.

OBJECTIVE

To further elucidate the role of nitric oxide (NO) in airway responsiveness, we investigated whether L-NAME induces airway hyperresponsiveness to serotonin and acetylcholine (ACh) in animals with intact innervation.

METHODS

Cats were anesthetized with pentobarbital sodium (50 mg/kg, i.p.), and mechanically ventilated. To assess airway responsiveness, we measured increase in total pulmonary resistance (RL) produced by delivering serotonin or ACh aerosol to the airway, and determined PC200 (the concentration which caused a 200% increase in RL).

RESULTS

The following results were obtained: (1) Airway responsiveness to serotonin was significantly enhanced by the administration of L-NAME (100 mg/kg) in animals treated with atropine and propranolol. (2) Airway responsiveness to serotonin was also significantly enhanced by L- NAME in animals with intact innervation. (3) In contrast, airway responsiveness to ACh was not changed by the addition of L-NAME in cats with intact innervation.

CONCLUSION

These results suggest that NO modulates nonspecific airway responsiveness in animals with intact innervation, presumably by a reflex mechanism.

Pituitary adenylate cyclase activating peptide mediates inhibitory nonadrenergic noncholinergic relaxation

We investigated the contribution of pituitary adenylate cyclase activating peptide (PACAP) to inhibitory nonadrenergic noncholinergic (inhibitory-NANC) relaxation of tracheal smooth muscle in cats. We also investigated the roles of vasoactive intestinal peptide (VIP) and nitric oxide (NO) on this function. Smooth muscle strips prepared from feline trachea were precontracted with 1 microM serotonin, and inhibitory-NANC relaxation was induced by electrical-field stimulation in the presence of atropine and propranolol. PACAP-(6-38) (a selective antagonist of PACAP; 1, 3 and 10 microM), VIP-(10-28) (a selective antagonist of VIP; 1, 3 and 10 microM) and N(omega)-nitro-L-arginine methyl ester (L-NAME, a selective NO synthase inhibitor; 3, 10 and 30 microM) each partially but significantly attenuated the amplitude of inhibitory-NANC relaxation. The effects of PACAP-(6-38) and VIP-(10-28) were additive. Addition of PACAP-(6-38) and/or VIP-(10-28) further attenuated relaxation in the presence of L-NAME. These results suggest that PACAP, VIP and NO contribute to the relaxation induced by inhibitory-NANC in tracheal smooth muscle in cats, and that they mediate this relaxation via different pathways.

Effect of the Chinese herbal medicine, Bakumondo-to, on airway hyperresponsiveness induced by ozone exposure in guinea-pigs

OBJECTIVE

Bakumondo-to (Maimendong tang) is a Chinese herbal medicine that has been used as an anti-tussive agent. However, the effects of Bakumondo-to on airway hyperresponsiveness are unknown. We examine whether Bakumondo-to can inhibit airway hyperresponsiveness induced by ozone.

METHODOLOGY

Measurements of airway responsiveness and plasma extravasation and bronchoalveolar lavage (BAL) were performed before and after ozone exposure (3 p.p.m., 2 h). Guinea-pigs were anaesthetized with pentobarbital sodium and mechanically ventilated. Airway responsiveness was determined by an inhalation of doubling concentration of histamine, and the concentration of histamine required to produce a 200% increase in R(L) (PC200) was calculated by log-linear interpolation. Plasma extravasation was evaluated by measuring the extravasation of Evans blue dye in the airway.

RESULTS

Ozone produced significant airway hyperresponsiveness and plasma extravasation, with an influx of neutrophils in BAL fluid. Bakumondo-to (400 mg/kg p.o.) significantly inhibited airway hyperresponsiveness, but had no effect on neutrophil influx or plasma extravasation.

CONCLUSIONS

We demonstrated that Bakumondo-to can attenuate airway hyperresponsiveness induced by ozone without affecting airway inflammation, which suggests that Bakumondo-to may act on the subsequent mechanisms after the induction of inflammation, such as mediator release.

PACAP reverses airway hyperresponsiveness induced by ozone exposure in guinea pigs

BACKGROUND

We previously demonstrated that pituitary adenylate cyclase activating peptide (PACAP) inhibits airway smooth muscle contraction and plasma extravasation.

OBJECTIVE

We thus hypothesized that PACAP may regulate airway responsiveness through these effects and examined the effects of exogenously applied PACAP on the airway hyperresponsiveness induced by ozone exposure.

METHODS

Ozone exposure was carried out in awake, spontaneously breathing guinea pigs using 3 ppm for 2 h. Airway responsiveness to histamine was determined before and 30 and 90 min after the termination of ozone exposure for 2 h in anesthetized animals. Extravasation of Evans blue was measured before and 90 min after the termination of ozone exposure. Either PACAP (10(-6) mol/kg) or vehicle was administered intravenously 60 min after exposure. The airway responsiveness was expressed as the concentration of histamine required to produce a 200% increase in total pulmonary resistance (PC(200)).

RESULTS

Ozone exposure caused a significant decrease in PC(200) (n = 5, p < 0.05) 30 min after ozone exposure which persisted 90 min thereafter, thus suggesting that ozone caused airway hyperresponsiveness. PACAP significantly suppressed the increase in airway hyperresponsiveness induced by ozone 90 min after exposure (n = 5, p < 0.05). In contrast, this peptide did not have any effect on plasma extravasation.

CONCLUSION

We thus conclude that PACAP decreases ozone-induced airway responsiveness, and, therefore, intravenously administered PACAP may be useful in reversing airway hyperresponsiveness.

Effect of inhaled glucocorticoid on the cellular profile and cytokine levels in induced sputum from asthmatic patients

Cytokines are considered to play a role in the airway inflammation of bronchial asthma. We examined the cellular profile and cytokine levels in induced sputum samples obtained before and after treatment with beclomethasone dipropionate (BDP, 800 microg/day, for 4 weeks) in 12 mild to moderate asthmatic subjects who had not previously received inhaled glucocorticosteroids. Sputum was induced with a 20-min inhalation of 3% saline by an ultrasonic nebulizer. The freshly expectorated sputum separated from the saliva was analyzed for cell counts, for the concentration of interleukin-8 (IL-8), and for the concentration of granulocyte-macrophage colony-stimulating factor (GM-CSF). The mean percentage of eosinophils in the sputum samples decreased significantly after BDP treatment, but no significant change in the percentage of neutrophils was observed. The mean IL-8 and GM-CSF levels also decreased significantly after treatment. The BDP treatment was associated with an increase in the mean peak expiratory flow (PEF) and with a decrease in the diurnal variation of PEF. These results suggest that inhaled steroids improve airway inflammation and lung function in asthmatics, presumably in part by inhibiting the synthesis of inflammatory cytokines such as IL-8 and GM-CSF.

Allelic loss on chromosome 9 in bladder cancer tissues and urine samples detected by blunt-end single-strand DNA conformation polymorphism

Allelic loss on chromosome 9 is the most frequent and earliest genetic event in bladder carcinogenesis, and its detection in urine samples would be useful for detecting bladder cancer. A highly sensitive method to detect loss of heterozygosity (LOH) at 5 polymorphic loci on chromosome 9p and 9q was developed by the use of blunt-end single-strand DNA conformation polymorphism (blunt-end SSCP) analysis. Tumor tissues, urine samples and peripheral blood lymphocytes from 34 patients with transitional cell carcinoma of the bladder were analyzed. LOHs on 9p and/or 9q were found in 24 (71%) of 34 tumor samples and 23 (70%) of 33 urine samples, while no allelic loss was detected in 20 urine samples from benign urothelial diseases. The frequency of allelic loss in tumor tissues was 67%, 71% and 80% in the pTa, pT1 and > or = pT2 stages and 50%, 80% and 79% in G1, G2 and G3 tumors, respectively. In comparison with a urine cytological examination, LOH on chromosome 9 was detected in 70% of urine samples diagnosed as transitional cell carcinoma, 67% of those as atypia and 70% of those as no malignant cells. Thus, detection of LOH on chromosome 9 from urine samples by blunt-end SSCP is a more sensitive diagnostic modality than cytologic examination for detecting bladder cancer. It would be useful for postoperative management of bladder cancer, particularly when the allelic loss is revealed in the tumor tissues obtained at first surgery.

Role of adrenergic nervous system in cigarette smoke-induced bronchoconstriction in guinea pigs

The goal of this study was to clarify the role of the adrenergic nervous system in bronchoconstriction induced by exposure to cigarette smoke in guinea pigs. Artificially ventilated animals were exposed to 160 puffs of smoke for 8 min. Bronchoconstriction was assessed as a percentage of the baseline total pulmonary resistance (RL). The effects of pretreatment with phentolamine (0.1 mg/kg, i.v.), propranolol (1 mg/kg, i.v.), and/or atropine (1 mg/kg, i.v.) were evaluated. Exposure to cigarette smoke caused significant bronchoconstriction. Phentolamine, an alpha-adrenoceptor antagonist, significantly inhibited cigarette smoke-induced bronchoconstriction, while propranolol, a beta-adrenoceptor antagonist, significantly enhanced it. Combined use of these compounds further enhanced the bronchoconstriction. All of modulations of the bronchoconstriction by adrenoceptor antagonists were completely abolished by pretreatment with atropine. Phentolamine and/or propranolol had no effect on the bronchoconstriction induced by inhaled acetylcholine. Pretreatment with yohimbine (0.5 mg/kg, i.v.), a selective alpha2-adrenoceptor antagonist, showed modulatory effects similar to those of phentolamine on cigarette smoke-induced bronchoconstriction. These results suggest that cigarette smoke-induced bronchoconstriction is regulated by the prejunctional modulation of the cholinergic system via alpha- and beta-adrenoceptors. This mechanism may be modulated by the autoregulation of adrenergic nerves via the alpha2-autoreceptor.

Eosinophilic airway inflammation induced by repeated exposure to cigarette smoke

Acute exposure to cigarette smoke causes airway hyperresponsiveness (AHR) in guinea-pigs, which resolves within a few hours. Repeated exposure may have a different effect on the airways. To address this question, guinea-pigs were repeatedly exposed to cigarette smoke (six cigarettes for 1 h x day(-1)) for 14 consecutive days. Airway responsiveness to inhaled histamine and differential cell counts in bronchoalveolar lavage fluid (BALF) were evaluated 1 day after the last exposure. Significant neutrophilia in BALF was observed after 3 days of smoke exposure. Significant eosinophilia in BALF and AHR were observed after 14 days of smoke exposure, but not after 3 or 7 days of smoke exposure. These changes persisted until 3 days after the last exposure and resolved 7 days afterwards. Histologically, the recruited eosinophils were observed predominantly in the airways, but not in the alveoli. Treatment with E-6123, a specific platelet-activating factor receptor antagonist (1 mg x kg(-1) x day(-1) p.o. during smoke exposure) significantly inhibited the eosinophil influx and AHR. Repeated exposure to cigarette smoke may induce prolonged airway inflammation and airway hyperresponsiveness in guinea-pigs. Platelet-activating factor or platelet-activating factor-like lipids may play a key role in airway hyperresponsiveness, presumably by the induction of eosinophilic airway inflammation.

Pituitary adenylate cyclase activating peptide regulates neurally mediated airway responses

To clarify the protective effects of pituitary adenylate cyclase activating peptide (PACAP) on airway narrowing, we examined the effects of PACAP on smooth muscle contraction and plasma extravasation in guinea-pig airways. Smooth muscle contraction evoked by electrical field stimulation (EFS) or exogenously applied acetylcholine (ACh) or substance P (SP) was measured before and after PACAP in vitro. The effect of PACAP on airway plasma extravasation was also measured in vivo. In trachea, PACAP (10(-9) - 10(-7) M) significantly suppressed smooth muscle contraction evoked by EFS without affecting ACh sensitivity, suggesting that PACAP inhibits cholinergic neuroeffector transmission. In the main bronchi, PACAP (10(-9) - 10(-8) M) significantly suppressed the contraction evoked by EFS without affecting SP sensitivity in the presence of atropine, suggesting that PACAP inhibits SP release from excitatory nonadrenergic noncholinergic (eNANC) nerves. In animals treated with atropine and propranolol, PACAP attenuated the increase in plasma extravasation induced by electrical vagus stimulation or by SP. These results suggest that pituitary adenylate cyclase activating peptide may play a role in modulation of airway responses through inhibition of cholinergic and noncholinergic mechanisms.