Flowering response of rice to photoperiod and temperature: a QTL analysis using a phenological model

In this study we have attempted to quantify the thermal and photoperiodical responses of rice (Oryza sativa L.) flowering time QTLs jointly by a date-of-planting field experiment of a mapping population, and a phenological model analysis that separately parameterizes the two responses, based on daily temperature, daily photoperiod and flowering date. For this purpose, the three-stage Beta model, which parameterizes the sensitivity to temperature (parameter ), the sensitivity to photoperiod (parameter ), and earliness under optimal conditions (10 h photoperiod at 30°C) (parameter G), was applied to Nipponbare × Kasalath backcross inbred lines that were transplanted on five dates. QTLs for the value were detected in the four known flowering time QTL (Hd1, Hd2, Hd6 and Hd8) regions, while QTLs for the G value were detected only in the Hd1 and Hd2 regions. This result was consistent with previous reports on near-isogenic lines (NILs) of Hd1, Hd2 and Hd6, where these loci were involved in photoperiod sensitivity, and where Hd1 and Hd2 conferred altered flowering under both 10 and 14 h photoperiods, while Hd6 action was only affected by the 14 h photoperiod. Hd8 was shown to control photoperiod sensitivity for the first time. Interestingly, Hd1 and Hd2 were associated with a QTL for the value, which might support the previous hypothesis that the process of photoinduction depends on temperature. These results demonstrate that our approach can effectively quantify environmental responses of flowering time QTLs without controlled environments or NILs.     

Possible antitumor promoters in Spinacia oleracea (spinach) and comparison of their contents among cultivars

Spinach leaves were found to contain two potent antitumor promoters as detected by the activity against tumor promoter-induced Epstein-Barr virus activation. The active components were identified as 1-O-alpha-linolenoyl-2-O-(7Z,10Z,13Z)-hexadecatrienoyl-3-O-beta-D-galactopyranosyl-sn-glycerol and 1,2-di-O-alpha-linolenoyl-3-O-beta-D-galactopyranosyl-sn-glycerol by spectroscopic data and some chemical and enzymatic reactions. Their contents significantly varied with the cultivar and with the culture conditions.     

Wavelength modulation by molecular environment in visual pigments

The absorption and regenerability characteristics are compared for rhodopsin contained in rod outer segment membranes and purified in a series of alkyl sucrose esters. It is found that membrane-bound rhodopsin has maximum absorbance from 504 to 500 nm between 1.5 and 40 degrees C. After purification, rhodopsin absorbance can be blue-shifted by up to 6 nm, depending on the detergent species used. Only the longest chain sucrose esters give purified rhodopsin with maximum absorbance comparable to that of the native pigment. In the same manner, detergent-purified rhodopsin will be easily regenerated as long as its native spectral characteristics are maintained. Sucrose esters thus prove to be mild enough to maintain rhodopsin functionality with respect to these two properties and could probably be used successfully to maintain other membrane proteins' integrity.     

A new prostaglandin E1 analogue (TFC-612) prevents a decrease in motor nerve conduction velocity in streptozocin-diabetic rats

A new prostaglandin E1 analogue (TFC-612) was orally given to streptozocin-diabetic rats for 4 weeks after the induction of diabetes and its effects on motor nerve conduction velocity were studied. The compound significantly prevented a decrease of the velocity but did not reverse abnormal sorbitol and myo-inositol contents of the sciatic nerve. The results suggest that TFC-612 has a potent effect on diabetic nerve dysfunction via other mechanism than the correction of sorbitol and myo-inositol metabolisms and could be a potential compound for therapy of diabetic polyneuropathy.     

Studies on Camellia sasanqua Thunb

A glycoside “Sasanquin” was separated from methanol extract of young leaves of Camellia sasanqua Thunb. It was not able to be found in young leaves of Camellia japonica L. and Thea sinensis L. on paper chromatogram. Investigations showed that this glycoside is composed of eugenol, D-glucose and D-xylose, and it has a structure of 3-methoxy-4-β-primeverosidoxy-allylbenzene.     

The Chemical Constitution of Rubrofusarin

Alkaline degradation of rubrofusarin and nor-rubrofusarin were studied; nor-rubrofusarin readily underwent hydrolysis to give a tetrahydroxynaphthalenc, acetone, and acetic acid; whereas, rubrofusarin, after prolonged time of hydrolysis, yielded a β-methoxytrihydroxynaphthalene instead of the naphthol. Physical and chemical studies revealed that the naphthol is 1,3,6,8-tetrahydroxynaphthalene and it has been confirmed by the synthesis from chromotropic acid (disodium salt). Thus, evidently, rubrofusarin has a naphthalene nucleus to which a methoxyl group is attached at β-position. The formation, on the hydrolysis, of acetone and acetic acid, along with the naphthol, indicates the presence of 2-methyl-γ-pyrone structure in rubrofusarin.     

Phase advance of the light-dark cycle perturbs diurnal rhythms of brain-derived neurotrophic factor and neurotrophin-3 protein levels, which reduces synaptophysin-positive presynaptic terminals in the cortex of juvenile rats

In adult rat brains, brain-derived neurotrophic factor (BDNF) rhythmically oscillates according to the light-dark cycle and exhibits unique functions in particular brain regions. However, little is known of this subject in juvenile rats. Here, we examined diurnal variation in BDNF and neurotrophin-3 (NT-3) levels in 14-day-old rats. BDNF levels were high in the dark phase and low in the light phase in a majority of brain regions. In contrast, NT-3 levels demonstrated an inverse phase relationship that was limited to the cerebral neocortex, including the visual cortex, and was most prominent on postnatal day 14. An 8-h phase advance of the light-dark cycle and sleep deprivation induced an increase in BDNF levels and a decrease in NT-3 levels in the neocortex, and the former treatment reduced synaptophysin expression and the numbers of synaptophysin-positive presynaptic terminals in cortical layer IV and caused abnormal BDNF and NT-3 rhythms 1 week after treatment. A similar reduction of synaptophysin expression was observed in the cortices of Bdnf gene-deficient mice and Ca(2+)-dependent activator protein for secretion 2 gene-deficient mice with abnormal free-running rhythm and autistic-like phenotypes. In the latter mice, no diurnal variation in BDNF levels was observed. These results indicate that regular rhythms of BDNF and NT-3 are essential for correct cortical network formation in juvenile rodents.     

Synthesis and biological activity of 4-methyl-3,5-dioxane derivatives as thromboxane A2 receptor antagonists

The synthesis and biological activity of novel 4-methyl-3,5-dioxane analogues are described. All compounds were produced through modification of the substituent formally corresponding to the omega-octenol side chain of thromboxane A2 (TXA2), in reference to the structure of SQ29548. Several compounds were found to be potent TXA2 receptor antagonists. Compound 8b was the most effective inhibitor of 9,11-epoxymethano PGH2 (U-46619)-induced human platelet aggregation (IC50 = 7.4 nM).     

Analysis of hunger-driven gene expression in the Drosophila melanogaster larval central nervous system

A transposon-inserted mutant of Drosophila melanogaster was recently identified, and the larvae show no food preference (Ryuda and Hayakawa, 2005). To reveal the genetic mechanism underlying the preference change in this mutant, a large-scale oligo-DNA microarray screening was carried out to identify genes whose expression is different in control and mutant strains. We focused especially on hunger-driven changes in gene expression in the larval central nervous system (CNS) of both strains, because the state of food depletion should promote a feeding response due to changed expression of certain genes in the CNS. We identified 22 genes whose expression changed after starvation in either or both of the two strains. Quantitative RT-PCR analyses confirmed the expression changes in four genes, CG6271, CG6277, CG7953, and new glue 3 (ng3, encoding a putative structural molecule). CG6271 and CG6277 encode triacylglycerol lipase, and CG7953 produces a protein homologous to a juvenile hormone (JH) binding protein. The expression of these two groups of genes was enhanced in control strain larvae with a normal food preference but not in GS1189 strain larvae. Given that these genes contribute to mediating hunger-driven changes in food preference and intake in D. melanogaster larvae, the dysfunction of these key genes could cause the defect in food preference observed in GS1189-strain larvae.