Mechanical behavior of the crystal lattice of natural cellulose in wood under repeated uniaxial tension stress in the fiber direction

This study investigated the relationship between the cellulose crystal lattice strain (crystalline region) and the macroscopic surface strain in specimens of Chamaecyparis obtusa wood under repeated uniaxial tension stress in the fiber direction. Changes in the strain of the crystal lattice were measured from the peak of (004) reflection using the transit X-ray method. The macroscopic surface strain of each specimen was measured with a strain gauge. In both loading and unloading, the surface strain changed linearly with changes in stress. However, crystal lattice strain was not linear but exhibited changes along a curve with changing stress. Under stressed conditions, the crystal lattice strain was always less than the surface strain, regardless of the frequency of repetition in the loading and unloading cycle. The ratio of the crystal lattice strain to the surface strain showed a negative correlation for stress in both loading and unloading. That is, the ratio decreased with increasing stress, and finally tend to converge to a specific value. The ratio (I/I ₀) between the diffracted intensity (I ₀) in the (004) plane in the unloaded condition and the diffracted intensity (I) in the (004) plane in the loaded condition tend to converge on a specific value with increasing frequency of repetition. When the substantial tension Young’s modulus of the wood in the longitudinal direction decreased, the ratio of the strain of the crystal lattice to the surface strain also decreased. Moreover, the ratio decreased with increasing microfibril angle of the specimen.     

Increasing mutagenic efficiency of gamma-radiation in rice by irradiation of seeds at extremely low temperature

Summary Dry seeds of rice, Oryza sativa L., containing about 13 percent moisture, were exposed to ⁶⁰Co gamma raysat extremely low temperature (–196°C). M₁ damage on survival rate, seedling height and seed set were found to become much smaller in the cooling treatment than in the not-cooled control. Chlorophyll and heading date mutation frequencies in the M₂ generation were not affected by the decreased M₁ damage caused by the cooling treatment, and the mutation frequencies could be significantly increased by applying higher doses combined with the cooling treatment. Frequency of sterile or semi-sterile mutants in the M₂ generation was found to be significantly lower in the cooling treatment than in the not-cooled control.It is assumed from the experimental results that extremely low temperatures during irradiation could reduce the amount of physiological damage and gross chromosome aberrations. This results in an increased efficiency of producing minute deletions and/or point mutations.     

Indica-japonica differentiation in Chinese rice landraces

Summary Ninety Chinese rice landraces were examined with special reference to the indica-japonica differentiation in terms of traditional criteria, isozyme analysis and PCR analysis of the chloroplast DNA (cpDNA). Cultivars were separated into indica and japonica defined by a discriminant function (Z) based on key characters, as well as by isozyme genotypes. Most indica landraces had chloroplast DNAs with a deletion at the Pst-12 fragment, while most japonica landraces had cpDNAs without the deletion. Two traditionally recognized varietal groups in China, keng and hsien, corresponded largely to the respective japonica and indica revealed in our study. The results obtained in this study showed good agreement for classification of indica and japonica types by the three methods: discriminant analysis by Z value, isozyme analysis, and PCR analysis for cpDNA.     

Dual origin of the cultivated rice based on molecular markers of newly collected annual and perennial strains of wild rice species, Oryza nivara and O. rufipogon

The direct ancestor of rice (Oryza sativa L.) is believed to be AA genome wild relatives of rice in Asia. However, the AA genome wild relatives involve both annual and perennial forms. The distribution of the retrotransposon p-SINE1-r2, a short interspersed nuclear element (SINE) at the waxy locus was analyzed in diverse accessions of the AA genome wild relatives of rice (O. rufipogon sensu lato). Most annual wild rice accessions had this retrotransposon, while most perennial types lacked this element, contradicting results to the previous studies. Results presented here suggest that O. sativa has dual origin that lead to indica-japonica differentiation. Results suggest the indica line of rice varieties evolved from the annual genepool of AA genome and the japonica varieties from the perennial genepool of AA genome wild rice.     

Inhibitory effects of oolong tea polyphenols on pancreatic lipase in vitro

Fifty-four polyphenols isolated from tea leaves were evaluated for their inhibitory activities against pancreatic lipase, the key enzyme of lipid absorption in the gut. (-)-Epigallocatechin 3-O-gallate (EGCG), which is one of major polyphenols in green tea, showed lipase inhibition with an IC50 of 0.349 microM. Moreover, flavan-3-ol digallate esters, such as (-)-epigallocatechin-3,5-digallate, showed higher activities of inhibition on lipase with an IC50 of 0.098 microM. On the other hand, nonesterified flavan-3-ols, such as (+)-catechin, (-)-epicatechin, (+)-gallocatechin, and (-)-epigallocatechin, showed zero and/or the lowest activities against pancreatic lipase (IC50 > 20 microM). These data suggested that the presence of galloyl moieties within the structure was required for enhancement of pancreatic lipase inhibition. It is well-known that flavan-3-ols are polymerized by polyphenol oxidase and/or heating in a manufacturing process of oolong tea. Oolonghomobisflavans A and B and oolongtheanin 3'-O-gallate, which are typical in oolong tea leaves, showed strong inhibitory activities with IC50 values of 0.048, 0.108, and 0.068 microM, respectively, even higher than that of EGCG. The oolong tea polymerized polyphenols (OTPP) were prepared for the assay from oolong tea extract, from which the preparation effectively subtracted the zero and/or less-active monomeric flavan-3-ols by preparative high-performance liquid chromatography. The weight-average molecular weight (Mw) and number-average molecular-weight (Mn) values of OTPP were 2017 and 903, respectively, by using gel permeation choromatography. OTPP showed a 5-fold stronger inhibition against pancreatic lipase (IC50 = 0.28 microg/mL) by comparison with that of the tannase-treated OTPP (IC50 = 1.38 microg/mL). These data suggested that the presence of galloyl moieties within their chemical structures and/or the polymerization of flavan-3-ols were required for enhancement of pancreatic lipase inhibition.     

Recommended doses of medetomidine-midazolam-butorphanol with atipamezole for preventing hypothermia in mice

A non-narcotic anesthetic combination (Me/Mi/Bu) of medetomidine (Me), midazolam (Mi), and butorphanol (Bu) has been recommended as the injectable anesthesia in mice. An original dose of Me/Mi/Bu (0.3/4.0/5.0 mg/kg) has provided sufficient anesthetic duration of 40–50 min in mice. In addition, atipamezole is available for reversal of Me/Mi/Bu anesthesia. As an adverse effect of Me/Mi/Bu anesthesia, however, severe hypothermia has been also observed in mice. In the present study, we investigated 1) the main agent in Me/Mi/Bu to cause of hypothermia, 2) the effects of the differential doses of atipamezole on hypothermia induced by Me/Mi/Bu anesthesia and on the plasma levels of creatinine phosphokinase and transaminases, and 3) those recommended doses for preventing hypothermia induced by Me/Mi/Bu anesthesia in mice. The results suggested that 1) the α₂-agonist medetomidine is most likely to induce hypothermia in mice under Me/Mi/Bu anesthesia, 2) the antagonism of atipamezole within proper dose range is effective in promoting the recovery from Me/Mi/Bu-induced hypothermia, and 3) Me/Mi/Bu at the recommended dose of 0.2/6.0/10.0 mg/kg enable to provide anesthetic effects for 40 min and is more considerable to prevent the hypothermia than that at the original dose of 0.3/4.0/5.0 mg/kg.     

A linear, O-coordinated eta1-CO2 bound to uranium

The electron-rich, six-coordinate tris-aryloxide uranium(III) complex [((AdArO)3tacn)U(III)] [where (AdArOH)3tacn = 1,4,7-tris(3-adamantyl-5-tert-butyl-2-hydroxybenzyl)1,4,7-triazacyclononane] reacts rapidly with CO2 to yield [((AdArO)3tacn)U(IV)(CO2)], a complex in which the CO(2) ligand is linearly coordinated to the metal through its oxygen atom (eta1-OCO). The latter complex has been crystallographically and spectroscopically characterized. The inequivalent O-C-O bond lengths [1.122 angstroms (A) for the O-C bond adjacent to uranium and 1.277 A for the other], considered together with magnetization data and electronic and vibrational spectra, support the following bonding model: U(IV)=O=C*-O- <--> U(IV)-OC-O-. In these charge-separated resonance structures, the uranium center is oxidized to uranium(IV) and the CO2 ligand reduced by one electron.