Characterization of QEet.ocs-5A.1, a quantitative trait locus for ear emergence time on wheat chromosome 5AL

QEet.ocs‐5A.1, a quantitative trait locus controlling ear emergence time, has been detected on wheat chromosome 5AL using single chromosome recombinant lines (SCRs) developed from a cross between ‘Chinese Spring’ (CS) (‘Cappelle‐Desprez’ 5A) and CS (Triticum spelta 5A). This locus has little influence on grain yield and its components, and thus has breeding potential for changing ear emergence time without yield reduction. To characterize the phenotypic expression of QEet.ocs.1 and to test its interaction with the Vrn‐A1 gene for vernalization response, six near‐isogenic SCRs differing for these two gene regions were grown together with the parental controls under different vernalization and photoperiod regimes. The T. spelta allele of QEet.ocs.1 accelerated heading time when vernalization and photoperiod were satisfied, demonstrating that the function of this QTL is earliness per se. There was no interaction between Vrn‐A1 and QEet.ocs.1.     

Genetic variation and phylogenetic relationships in East and South Asian melons, Cucumis melo L., based on the analysis of five isozymes

Genetic structure and phylogenetic relationships in East and South Asian melons were analyzed, based on the geographical variation of five isozymes. The analysis of Indian melon accessions showed a continuous variation in seed length, ranging from 4 to 13 mm. Most of the East Asian melons, vars. makuwa and conomon, were classified as the small seed type with seed length shorter than 9 mm. The frequency of the small seed type increased from the west to the east in India. Allelic variation was detected at a total of nine loci of five isozymes among 114 melon accessions. Gene diversity calculated for the nine loci indicated that Indian melon was rich in genetic variation, which decreased from India towards the east. Clear geographical variation was detected in two enzymes, APS and6-PGDH. Pgd-1 ¹ and Ap-3 ¹ were frequent in India and Myanmar, while most of the melons in Laos, China, Korea and Japan carried Pgd-1 ³ and Ap-3 ³, except var. inodorusin China. Among the latter two alleles, the frequency of Ap-3 ³ was more than 50% in the small seed type in north and east India, indicating that vars. makuwa and conomon were related to the small seed type in these areas. It was also suggested that the small seed type with wet tolerance originated in central India and was selected under wet condition in the east. This revised version was published online in August 2006 with corrections to the Cover Date.     

Adaptation and ecological differentiation in wheat with special reference to geographical variation of growth habit and Vrn genotype

Geographical variation of growth habit was studied for 749 landraces from various parts of the world, with special reference to their adaptation and ecogeographical differentiation. The total frequency of spring‐type landraces was 49.9%, and varied between localities. Spring‐type landraces were frequent in two distinct areas where the average January temperature was either below ‐7°C or above 4°C, with winter‐type landraces in areas from ‐7°C to 4°C. These results indicated that geographical variation of growth habit is closely related to the degree of winter coldness. An analysis of the Vrn genotype for 216 spring‐type landraces demonstrated the uneven distribution of four Vrn genes, with Vrn4 being the least frequent. The adaptive Vrn genotype was different between localities. Genotypes carrying Vrn‐A1 and additional Vrn gene(s) were frequent in two distinct areas where the average January temperature was either below ‐7°C or over 10°C, while genotypes with any of three Vrn genes, except Vrn‐A1, adapted to areas with temperatures from 4°C to 10°C. Therefore, it was concluded that the adaptability of wheat landraces differed depending on their growth habit and Vrn genotype, and that ecotypes with different Vrn genotypes were allopatrically distributed as a result of adaptation to different winter temperature. However, the differential distribution of Vrn‐B1, Vrn‐D1 and Vrn4 could not be explained by their adaptability, and might reflect the polyphyletic origin of common wheat.     

Mitochondrial DNA variation in foxtail millet, Setaria italica (L.) P. Beauv.

Mitochondrial DNA (mtDNA) wascharacterized by RFLPs in 94 strains offoxtail millet, Setaria italica (L.)P. Beauv. Three RFLP patterns wereobserved by using rice atp6 as aprobe, and were designated as types I-III. Difference between types I and II seems tobe attributed to recombination between twoatp6 genes. In East and SoutheastAsia and Afghanistan, both of types I andII were found, while type I was predominantin India, Central Asia and Europe. InChina, type III was also found. Chinesestrains showed higher gene diversity thanthose from other regions. This resultcoincided the previous studies on isozymesand nuclear RFLPs.     

Increased grain dormancy in white-grained wheat by introgression of preharvest sprouting tolerance QTLs

White-grained wheat cultivars have long been recognized to be less resistant to preharvest sprouting (PHS) than the red-grained ones. Previously two QTLs for grain dormancy, QPhs.ocs-3A.1 (QPhs-3AS) and QPhs.ocs-4A.1 (QPhs-4AL) were identified in a highly dormant Japanese red wheat, Zenkoujikomugi (Zen). Aiming at improvement of PHS tolerance in white-grained wheat, the introgression effect of these two QTLs in a white-grained population consisting of 40 recombinant inbred lines (RILs) developed from a cross between Zen and white-grained Spica was examined here. Random 20 RILs with red grains were also developed from the same cross and used as a control population. The RILs were grown in the field and in the glasshouse to evaluate the grain dormancy by germination test. Several SSR markers closely linked to the QPhs-3AS and QPhs-4AL were used to estimate the alleles at the QTLs. Dormancy variation in the RILs was significantly associated with the differences for grain color and the alleles at QPhs-3AS over several years. Although allelic variation was detected in a SSR marker closely linked to QPhs-4AL there was no difference in germination data between the Zen-allele and the Spica-allele groups. As expected, the red-grained RILs with the Zen allele at QPhs-3AS were the most dormant. Some white-grained RILs with the Zen allele at QPhs-3AS showed higher dormancy compared to the red-grained RILs with the alternative allele. These results demonstrated that introgression of the QPhs-3AS gene could contribute to the increased grain dormancy in white-grained wheat.     

Phosphorylation and growth inhibitory activity of all ketohexose analogs

Sugars are not only important energy sources and structural components, but they also act as signaling molecules that are involved in specific signal sensing. Among all ketohexose analogs (d ‐fructose, d ‐psicose, d ‐tagatose, d ‐sorbose, l ‐fructose, l ‐psicose, l ‐tagatose and l ‐sorbose), only d ‐psicose inhibited the growth of Arabidopsis roots. Phosphorylation by fructokinase occurred in d ‐fructose and d ‐psicose. d ‐Psicose‐induced inhibition was relieved by adding d ‐fructose. Thus, the inhibition could not be attributed to the toxicity of phosphorylated d ‐psicose. The phosphorylation process requires ATP. After phosphorylation, d ‐fructose is metabolized in glycolysis and becomes energy sources and structural components, whereas d ‐psicose cannot contribute to the energy sources and structural components because it does not get metabolized further. However, d ‐psicose did not affect ATP level in the Arabidopsis roots, suggesting that the d ‐psicose‐induced growth inhibition may not be related to the starvation of ATP. The phosphorylation of ketohexoses by fructokinase is known to a trigger signal‐sensing resulting in growth inhibition. Therefore, d ‐psicose can be phosphorylated by fructokinase and this process may play a possible role in signal‐sensing. This is probably one of the useful model systems for the study of the hexokinase‐independent sugar‐sensing function and for developing new types of weed‐control agents.     

Anti-Thy-1 Antibody-mediated Complement-dependent Cytotoxicity is Regulated by the Distribution of Antigen,Antibody and Membrane Complement Regulatory Proteins in Rats

Some therapeutic antibodies as anticancer agents exert their effects through the host immune system, but the factors that predict their cytotoxicity, including complement-dependent cytotoxicity (CDC), are unclear. In the present study, we attempted to elucidate some of these factors in a preclinical model. CDC-related mesangiolysis caused by administration of the anti-Thy-1.1 antibody can be studied in the rat anti-Thy-1 glomerulonephritis model, so the model was used in this study. Three animals each were sacrificed at 0.5, 1, 8, 24 and 48 hours after i.v. administration of the anti-Thy-1.1 antibody at 1mg/kg. The distribution of the Thy-1.1 antigen and 2 membrane complement regulatory proteins (mCRPs), Crry and CD55, in three non-treated animals and the distribution of the injected antibody and C3 in the model was studied by immunohistochemistry. In the mesangial cells of the kidney, both expression of the antigen and distribution of the antibody with C3 deposition were observed with weak expression of mCRPs. There was also antigen and antibody distribution in the medullary cells of the adrenal gland and in the lymphocytes of the thymus but no C3 deposition, which was thought to be related to high expression of mCRPs. The antigen was observed in several other organs and tissues without distribution of the antibody. Cell death was only observed in the mesangial cells. These results clearly demonstrate that activation of CDC is regulated by several factors, such as distribution of the target molecule, antibody distribution and the balance among the molecules of the CDC cascade and mCRPs.     

Single-copy nuclear PolA1 gene sheds light on the origin of S genome with relationships to B and G genomes of polyploid wheat species

PolA1, a single-copy nuclear gene encoding the largest subunit of RNA polymerase I, comprises highly polymorphic intron 19 and nucleotide tag (Ntag) sequences. We analyzed these sequences in 42 accessions, which differed in ploidy, of Triticum–Aegilops and Hordeum species. The lengths of the intron 19 sequences were ca. 110?bp long in Triticum–Aegilops species, except in four Sitopsis species, Ae. longissima, Ae. searsii, Ae. sharonensis, Ae. speltoides, which had introns similar in length to those of Hordeum species, i.e., ca. 240?bp long. Phylogenetic analyses of the Ntag sequences showed that the four Sitopsis and remaining Triticum–Aegilops species were classified into two discrete Hordeum and Triticum clades, respectively. The A and D genome-specific Ntag sequences of polyploid wheats were highly homologous with those of T. urartu and Ae. tauschii, respectively. In Ae. bicornis, another Sitopsis species, two accessions had the short intron 19 and Triticum–type Ntag sequence, which were highly homologous with those of the B genome in polyploid wheats, whereas one accession contained the long intron 19 and Hordeum–type Ntag sequences. In contrast, partial sequence analyses revealed that the three accessions of Ae. bicornis shared highly homology to single-copy DMC1 and EF-G genes. The discrepancy between these results indicates that the Sitopsis species were probably established by hybrid speciation including ancient introgressive hybridization between progenitors of Triticum–Aegilops and Hordeum. Although many researchers have proposed Ae. speltoides as a candidate for the B genome donor, our data suggest the existence of diploid B genome species in the past that were responsible for the origin of both polyploid wheats and Sitopsis species, including Ae. speltoides.     

Ferromagnetic imprinting of nuclear spins in semiconductors

We examine how a ferromagnetic layer affects the coherent electron spin dynamics in a neighboring gallium arsenide semiconductor. Ultrafast optical pump-probe measurements reveal that the spin dynamics are unexpectedly dominated by hyperpolarized nuclear spins that align along the ferromagnet's magnetization. We find evidence that photoexcited carriers acquire spin-polarization from the ferromagnet, and dynamically polarize these nuclear spins. The resulting hyperfine fields are as high as 9000 gauss in small external fields (less than 1000 gauss), enabling ferromagnetic control of local electron spin coherence.