Novel flavonol glycoside, 7-O-methyl mearnsitrin, from Sageretia theezans and its antioxidant effect

A novel flavonol glycoside, 7-O-methylmearnsitrin (7,4'-O-dimethylmyricetin 3-O-alpha-L-rhamnopyranoside), and myricetrin, kaempferol 3-O-alpha-L-rhamnopyranoside, europetin 3-O-alpha-L-rhamnoside, and 7-O-methyl quercetin 3-O-alpha-L-rhamnopyranoside were isolated from the leaves of Sageretia theezans, and their chemical structures were identified by spectroscopic analyses including two-dimensional NMR (HSQC, HMBC). Whereas myricetrin, europetin 3-O-alpha-L-rhamnoside, and 7-O-methylquercetin 3-O-alpha-L-rhamnopyranoside showed stronger activities than ascorbic acid and alpha-tocopherol, 7-O-methylmearnsitrin showed very weak antioxidant activities by ESR and LDL oxidation inhibition tests.     

Effects of heat stress on the redox status in the oviduct and early embryonic development in mice

This study examined the association between redox status in the oviduct and early embryonic death in heat-stressed mice. In Experiment 1, non-pregnant mice were heat-stressed at 35 C with 60% relative humidity for 12, 24, or 36 h, and the maternal redox status was verified by measuring the levels of reactive oxygen species (ROS) and free radical scavenging activity (FRSA) in the oviduct, and thiobarbituric acid reactive substances (TBARS) and glutathione peroxidase (GSH-Px) activity in the liver. In Experiment 2, zygotes were collected from mice heat-stressed for 12 h on the day of pregnancy, and their developmental abilities were assessed in vitro, along with the intensity of DNA damage at the 2-cell stage. The TBARS value and GSH-Px activity in the liver, and ROS level in the oviduct were significantly higher in heat-stressed mice, and this increase appeared to depend on the duration of the heat stress. Maternal heat stress significantly reduced the percentage of zygotes that developed to the morula and blastocyst and the total cell number in the blastocyst. In addition, DNA damage at the 2-cell stage was significantly higher in maternally heat-stressed embryos. These results suggest that heat stress induces systemic changes in redox status in the maternal body, and the resultant increase in oxidative stress in the oviduct is possibly involved in heat stress-induced early embryonic death .     

Phylogenetic analysis of AGAMOUS sequences reveals the origin of the diploid and tetraploid forms of self-pollinating wild buckwheat,Fagopyrum homotropicum Ohnishi

Fagopyrum homotropicum Ohnishi is a self-pollinating wild buckwheat species indigenous to eastern Tibet and the Yunnan and Sichuan Provinces of China. It is useful breeding material for shifting cultivated buckwheat (F. esculentum ssp. esculentum Moench) from out-crossing to self-pollinating. Despite its importance as a genetic resource in buckwheat breeding, the genetic variation of F. homotropicum is poorly understood. In this study, we investigated the genetic variation and phylogenetic relationships of the diploid and tetraploid forms of F. homotropicum based on the nucleotide sequences of a nuclear gene, AGAMOUS (AG). Neighbor-joining analysis revealed that representative individuals clustered into three large groups (Group I, II and III). Each group contained diploid and tetraploid forms of F. homotropicum. We identified tetraploid plants that had two diverged AG sequences; one belonging to Group I and the other belonging to Group II, or one belonging to Group II and the other belonging to Group III. These results suggest that the tetraploid form originated from at least two hybridization events between deeply differentiated diploids. The results also imply that the genetic diversity contributed by tetraploidization of differentiated diploids may have allowed the distribution range of F. homotropicum to expand to the northern areas of China.     

Triploid Induction in the Yellowtail Tetra,Astyanax altiparanae,Using Temperature Shock: Tools for Conservation and Aquaculture

Triploidization is an interesting tool to produce sterile fish. In the yellowtail tetra, Astyanax altiparanae, this can be applied for aquaculture and surrogate technologies. In this study, we compared the efficacy of cold (2 C) or heat shock (38 C, 40 C, and 42 C) on triploid induction in the yellowtail tetra. The eggs were treated with cold or heat shock, 2 min postfertilization (30 min in cold shock or 2 min in heat shock). Intact embryos served as the control group. Ploidy status was confirmed by karyotyping, flow cytometry, and nuclear diameter of erythrocytes. The hatching rate decreased after cold shock (12.69 ± 15.76%) and heat shock at 42 C (0.35 ± 0.69%) in comparison with the control group (63.19 ± 16.82%). At 38 C and 40 C, hatching rates (61.29 ± 17.73% and 61.75 ± 22.1%, respectively) were not decreased. Only one triploid arose at 38 C (1/80). At 40 C, a high number of triploids arose (72/78). At 42 C, very few embryos developed into the hatching stage. A large number of haploid individuals arose after cold shock (61/75), with only one triploid. Our results indicate that heat shocking of embryos at 40 C is optimum for triploid production in the yellowtail tetra.     

Anther culture in rice proportionally rescues microspores according to gametophytic gene effect and enhances genetic study of hybrid sterility

Background

To investigate plant hybrid sterility, we studied interspecific hybrids of two cultivated rice species, Asian rice (Oryza sativa) and African rice (O. glaberrima). Male gametes of these hybrids display complete sterility owing to a dozen of hybrid sterility loci, termed HS loci, but this complicated genetic system remains poorly understood.

Results

Microspores from these interspecific hybrids form sterile pollen but are viable at the immature stage. Application of the anther culture (AC) method caused these immature microspores to induce callus. The segregation distortion of 11 among 13 known HS loci was assessed in the callus population. Using many individual calli, fine mapping of the HS loci was attempted based on heterozygotes produced from chromosome segment substitution lines (CSSLs). Transmission ratio distortion (TRD) from microspores was detected at 6 of 11 HS loci in the callus population. The fine mapping of S₁ and S₁₉ loci using CSSLs revealed precise distances of markers from the positions of HS loci exhibiting excessive TRD.

Conclusions

We demonstrated that AC to generate callus populations derived from immature microspores is a useful methodology for genetic study. The callus population facilitated detection of TRD at multiple HS loci and dramatically shortened the process for mapping hybrid sterility genes.

     

Linkage analysis of RFLP markers for clubroot resistance and pigmentation in Chinese cabbage (Brassica rapa ssp. pekinensis)

A restriction fragment length polymorphism (RFLP) – based linkage map of Chinese cabbage (Brassica rapa ssp. pekinensis) (2n=20) including two agronomic traits, clubroot resistance and orange-yellow pigmentation, was constructed using doubled haploid parents. The total linkage distance was 735 cM; 63 loci were distributed into ten linkage groups. Clubroot resistance of the parental line T136-8 to the current pathotype, race 2, was predominantly controlled by a single dominant gene that originated from European turnip. The locus for clubroot resistance by the dominant major gene (CRa) was mapped on linkage group 3, and RFLP loci HC352b and HC181 were located 3 cM and 12 cM from it, respectively. The locus HC352b was identified by a 4.4 Kb Eco R I fragment, which segregated for null allele. The absence of an allelic fragment in HC352b could be interpreted by deletion in the resistance source; homozygotes for CRa could be efficiently selected by detecting null types for the marker. Orange-yellow pigmentation expressed in head inner leaves and petals was governed by a single recessive gene. The locus (Oy) for the pigmentation was mapped on linkage group 1, being located 17–19 cM from three RFLP loci that were closely linked to each other. The linkage analysis for clubroot resistance and unique pigmentation revealed some informative RFLP markers. Identification of molecular markers for clubroot resistance and other agronomically important traits would provide useful information in breeding programs of Chinese cabbage. This revised version was published online in August 2006 with corrections to the Cover Date.     

Rheological Properties of White Salted Noodles with Different Amylose Content at Small and Large Deformation

The rheological properties of cooked white salted noodles made from eight wheat cultivars with varied amylose content were analyzed at small and large deformation. Their dynamic shear viscoelasticity was measured using a rheometer with parallel plate geometry. Compressive force and creep‐recovery curves were measured using various probes and sample shapes. Noodles with lower amylose content showed a lower storage shear modulus (G′) and a higher frequency dependence of G′. The G′ values of noodles were highly correlated with amylose content in wheat flour and with G′ values of 30 and 40% starch gels. Remarkable differences in the characteristics of creep‐recovery curves were observed between cultivars. The difference in amylose content in wheat flour reflected the creep‐recovery properties of noodles. A negative correlation was demonstrated between amylose content and both maximum creep and recovery compliance. The compressive force required for 20, 50, 80, and 95% strains was compared. At 20 and 50% strain, noodles made from lower amylose wheat flour showed lower compressive force. Noodles of waxy wheat had a higher compressive force than nonwaxy noodles when the strain was >80%, indicating the waxy wheat noodles are soft but difficult to completely cut through.     

Presence of a Minor Amylose Fraction in the Central Portion of Waxy Wheat Starch Granules and Its Contribution to Granular Stability

When wheat starch granules containing various amounts of amylose (2.1–25%) were stained with 25% KI/10% I₂ solution, the granules largely changed to ghost structures below ≈5.0% amylose. The ghost showed a typical double structure: a black‐brown central portion and a red‐brown surrounding portion. The proportion of the black‐brown central portion in the ghost was strongly correlated to the amylose content (%) in the starch, that is, the black‐brown central portion decreased with a decrease in amylose. This suggests that amylose is possibly present in the black‐brown central portion. Sonication (20 kHz) followed by centrifugation of the ghost separated the black‐brown central portion from the red‐brown surrounding portion, and the amylose content in each portion was determined. The results indicated that the amylose content in the black‐brown central portion was 6.9%, whereas in the surrounding portion, it was only 1.0%. Furthermore, the central and surrounding portions were subjected to Sepharose CL‐2B gel‐filtration column chromatography and the presence of amylose could only be observed in the black‐brown central portion.     

Effect of Amylose Content on Gelatinization,Retrogradation, and Pasting Properties of Starches from Waxy and Nonwaxy Wheat and Their F1 Seeds

We studied the effect of amylose content on the gelatinization, retrogradation, and pasting properties of starch using wheat starches differing in amylose content. Starches were isolated from waxy and nonwaxy wheat and reciprocal F1 seeds by crossing waxy and nonwaxy wheat. Mixing waxy and nonwaxy wheat starch produced a mixed starch with the same amylose content as F1 seeds for comparison. The amylose content of F1 seeds ranged between waxy and nonwaxy wheat. Nonwaxy‐waxy wheat had a higher amylose content than waxy‐nonwaxy wheat. Endothermic enthalpy and final gelatinization temperature measured by differential scanning calorimetry correlated negatively with amylose content. Gelatinization onset and peak temperature clearly differed between F1 and mixed starches with the same amylose content as F1 starches. Enthalpy for melting recrystallized starches correlated negatively with amylose content. Rapid Visco Analyser measurement showed that F1 starches had a higher peak viscosity than waxy and nonwaxy wheat starches. Mixed starches showed characteristic profiles with two low peaks. Setback and final viscosity correlated highly with amylose content. Some of gelatinization and pasting properties differed between F1 starches and mixed starches.     

First feeding of diploid and triploid yellowtail tetra Astyanax altiparanae: An initial stage for application in laboratory studies

In this study, the aim was to establish a protocol for first feeding of diploid and triploid yellowtail tetra Astyanax altiparanae in laboratory conditions. The fry were fed with five different diets: (i) Artemia franciscana nauplii, (ii) plankton, (iii) dry food, (iv) Artemia franciscana nauplii + plankton, and (v) Artemia nauplii + plankton + dry food. Additionally, the growth and survival rates of diploid and triploid individuals were also evaluated. On day 10, the length of the fish between the treatments differed significantly (p = .0001) and ranged from 4.07 ± 0.06 mm (dry food) to 8.50 ± 0.64 mm (plankton + Artemia). The sizes of the fish increased with time, except for the fish fed with dry food. The survival rates were similar for the fish fed with the four diets and ranged from 80.7 ± 5.4% (dry food + plankton + Artemia to 92.0 ± 1.6% (plankton + Artemia), but differed from the fish fed with dry food (17.7 ± 5.8%, p = .0017). Diploids and triploids did not present differences on day 0 (p = .2252) and on day 10 (p = .4844) when the fish presented 6.77 ± 0.25 mm and 6.54 ± 0.15 mm respectively. Survival of diploids (87.3 ± 5.13%) and triploids (74.67 ± 2.30%) were also similar (p = .0285). These data are innovative and useful for establishing protocols for this species in both academic and applied sciences.