Role of glutathione in ethanol stress tolerance in yeast Pachysolen tannophilus

The effect of glutathione enrichment and depletion on the survival of Pachysolen tannophilus after ethanol stress was investigated. In this work, we verified that both control and glutathione deficient yeast cells were much more oxidized after ethanol stress. Depletion of cellular glutathione enhanced the sensitivity to ethanol and suppressed the adaptation. Incubation of the cell with amino acids constituting glutathione (GIu, Cys, Gly) increased the intracellular glutathione content, and subsequently the cell acquired resistance against ethanol. The level of reactive oxygen species, protein carbonyl, and lipid peroxidation in glutathione enriched groups were also studied. These results strongly suggest that intracellular glutathione plays an important role in the adaptive response in P. tannophilus to ethanol induced oxidative stress.     

桂西北喀斯特土壤对生态系统退化的响应

在桂西北喀斯特地区选取玉米 红薯轮作地（KMS）、放牧+冬季火烧草地（KGB）、自然恢复地（KNR）和原生林地（KPF）4种典型生态系统,研究了土壤有机碳、全氮、全磷,微生物生物量碳、氮、磷和土壤结构对生态系统退化的响应.结果表明：KPF土壤有机碳、全氮、全磷和微生物生物量碳、氮、磷均极显著高于其他3种土壤;其他3种土壤中,有机碳和全氮为：KNR > KGB > KMS,但差异不显著;KMS土壤全磷含量（0.87g·kg^-1）分别是KNR和KGB的2.07和9.67倍 (P<0.01);KGB和KNR土壤微生物生物量碳、氮、磷含量均显著大于KMS;KGB中微生物生物量碳显著大于KNR,但二者间微生物生物量氮和磷含量差异不显著.说明减少人为干扰后喀斯特退化生态系统可以缓慢增加土壤有机碳含量,适当放牧和自然恢复都可以作为退化生态系统恢复的方式;土壤微生物生物量对生态系统的变化响应较灵敏,可以作为喀斯特地区土壤养分变化或生态系统退化的一个敏感指标.土壤结构以>0.25 mm水稳性大团聚体为主（>70%）(KMS除外,以2～0.25 mm团聚体为主),并以>2 mm团聚体为主;土壤结构破坏率KMS（51.62%）大于KGB（23.48%）,KNR和KPF较小（分别为9.09%和9.46%）.说明人为干扰或农业耕作破坏了土壤水稳性大团聚体,使其向小粒级转变,土壤结构破坏率增大.对喀斯特地区退化严重的生态系统应减少人为干扰,以自然恢复等保护性措施为主.     

苏北沿海不同土地利用方式土壤水溶性有机碳含量特征

土壤水溶性有机碳(WSOC)是土壤碳循环最活跃的组成部分之一。土地利用方式的改变可能显著影响土壤有机碳的组成和结构,进而影响到大气与土壤间的碳交换。本研究以苏北沿海地区农田、杨农复合经营、杨树纯林以及草地等4种不同土地利用方式土壤为研究对象,采用TOC-VCPN总有机碳仪测定了4种不同土地方式下土壤WSOC含量的变化。分析了土壤WSOC与土壤总有机碳(TOC)、易氧化碳(ROC)及理化性质的相关关系。结果表明:WSOC和TOC、土壤全氮(TN)、ROC呈显著正相关,与碳氮比、pH、土壤容重呈显著负相关;WSOC的含量随土层的加深而减少,与总有机碳的变化特征一致,在各个土层,不同土地利用方式WSOC含量差异不显著;农田和草地的WSOC含量在0～10cm土层与10～25cm土层之间差异显著(P<0.05),杨农复合经营的WSOC含量在10～25cm土层与25～40cm土层之间差异显著(P<0.05),其他3种类型差异不显著。     

Solution structure of DNA/RNA hybrid duplex with C8-propynyl 2′-deoxyadenosine modifications: Implication of RNase H and DNA/RNA duplex interaction

Solution structures of DNA/RNA hybrid duplexes, d(GCGCA*AA*ACGCG): r(cgcguuuugcg)d(C) (designated PP57), containing two C8-propynyl 2′-deoxyadenosines (A*) and unmodified hybrid (designated U4A4) are solved. The C8-propynyl groups on 2′-deoxyadenosine perturb the local structure of the hybrid duplex, but overall the structure is similar to that of canonical DNA/RNA hybrid duplex except that Hoogsteen hydrogen bondings between A* and U result in lower thermal stability. RNase H is known to cleave RNA only in DNA/RNA hybrid duplexes. Minor groove widths of hybrid duplexes, sugar puckerings of DNA are reported to be responsible for RNase H mediated cleavage, but structural requirements for RNase H mediated cleavage still remain elusive. Despite the presence of bulky propynyl groups of PP57 in the minor groove and greater flexibility, the PP57 is an RNase H substrate. To provide an insight on the interactions between RNase H and substrates we have modeled Bacillus halodurans RNase H-PP57 complex, our NMR structure and modeling study suggest that the residue Gly(15) and Asn(16) of the loop residues between first β sheet and second β sheet of RNase HI of Escherichia coli might participate in substrate binding.     

Nutrient uptake relationship to root characteristics of rice

Data on root parameters and distribution are important for an improved understanding of the factors influencing nutrient uptake by a crop. Therefore, a study was conducted on a Crowley silt loam at the Rice Research and Extension Center near Stuttgart, Arkansas to measure root growth and N, P and K uptake by three rice (Oryza sativa L.) cultivars at active tillering (36 days after emergence (DAE)), maximum tillering (41 DAE), 1.25 cm internode elongation (55 DAE), booting (77 DAE) and heading (88 DAE). Soil-root core samples were taken to a depth of 40 cm after plant samples were removed, sectioned into 5 cm intervals, roots were washed from soil and root lengths, dry weights and radii were measured. Root parameters were significantly affected by the soil depth × growth stage interaction. In addition, only root radius was affected by cultivar. At the 0- to 5-cm soil depth, root length density ranged from 38 to 93 cm cm^-3 throughout the growing season and decreased with depth to about 2 cm cm^-3 in the 35- to 40-cm depth increment. The increase in root length measured with each succeeding growth stage in each soil horizon also resulted in increased root surface area, hence providing more exposed area for nutrient uptake. About 90% of the total root length was found in the 0- to 20-cm soil depth throughout the season. Average root radius measured in the 0- to 5-cm and 35- to 40-cm depth increments ranged from 0.012 to 0.013 cm and 0.004 to 0.005 cm, respectively throughout the season. Total nutrient uptake by rice differed among cultivars only during vegetative growth. Differences in total nutrient uptake among the cultivars in the field appear to be related to absorption kinetics of the cultivars measured in a growth chamber study. Published with permission of the Arkansas Agricultural Experiment Station.     

Structural and functional characterization of simvastatin-induced myotoxicity in different skeletal muscles

Background

Statins are the most commonly used drugs for the treatment of hypercholesterolemia. Their most frequent side effect is myotoxicity. To date, it remains unclear whether statins preferentially induce myotoxicity in fast- or in slow-twitch muscles. Therefore, we investigated these effects on fast- (extensor digitorum longus; EDL), slow- (soleus; SOL), and mixed-twitch muscles (diaphragm; DIA) in rats by comparing their contractile and molecular structural properties.

Methods

Simvastatin-induced functional changes were determined by muscle contraction measurements, and drug-induced molecular changes were investigated using Fourier transform infrared (FTIR) and attenuated total reflectance (ATR) FTIR spectroscopy.

Results

With simvastatin administration (30 days, 50 mg/kg), a depression in the force–frequency curves in all muscles was observed, indicating the impairment of muscle contractility; however, the EDL and DIA muscles were affected more severely than the SOL muscle. Spectroscopic findings also showed a decrease in protein, glycogen, nucleic acid, lipid content and an increase in lipid order and lipid dynamics in the simvastatin-treated muscles. The lipid order and dynamics directly affect membrane thickness. Therefore, the kinetics and functions of membrane ion channels were also affected, contributing to the statin-induced impairment of muscle contractility. Furthermore, a reduction in α-helix and β-sheet and an increase in random coil, aggregated and antiparallel β-sheet were observed, indicating the protein denaturation. Spectral studies showed that the extent of molecular structural alterations in the muscles following simvastatin administration was in the order EDL > DIA > SOL.

Conclusions

Simvastatin-induced structural and functional alterations are more profound in the fast-twitch than in the slow-twitch muscles.

General significance

Myotoxic effects of simvastatin are primarily observed in the fast-twitch muscles.     

Lipase-catalyzed asymmetric synthesis of naphtho[2,3-c]furan-1(3H)-one derivatives by a one-pot dynamic kinetic resolution/intramolecular Diels–Alder reaction: Total synthesis of (−)-himbacine

One-pot sequential reactions using the acyl moieties installed by enzymatic dynamic kinetic resolution of alcohols have been little investigated. In this work, the acryloyl moiety installed via the lipase/oxovanadium combo-catalyzed dynamic kinetic resolution of a racemic dienol [4-(cyclohex-1-en-1-yl)but-3-en-2-ol or 1-(cyclohex-1-en-1-yl)but-2-en-1-ol] with a (Z)-3-(phenylsulfonyl)acrylate underwent an intramolecular Diels–Alder reaction in a one-pot procedure to produce an optically active naphtho[2,3-c]furan-1(3H)-one derivative (98% ee). This method was successfully applied to the asymmetric total synthesis of (?)-himbacine.     

An HPLC‐ESMS study on the solid‐phase assembly of C‐terminal proline peptides

DKP formation is a serious side reaction during the solid‐phase synthesis of peptide acids containing either Pro or Gly at the C‐terminus. This side reaction not only leads to a lower overall yield, but also to the presence in the reaction crude of several deletion peptides lacking the first amino acids. For the preparation of protected peptides using the Fmoc/tBu strategy, the use of a ClTrt‐Cl‐resin with a limited incorporation of the C‐terminal amino acid is the method of choice. The use of resins with higher loading levels leads to more impure peptide crudes. The use of HPLC‐ESMS is a useful method for analysing complex samples, such as those formed when C‐terminal Pro peptides are prepared by non‐optimized solid‐phase strategies. Copyright © 1999 European Peptide Society and John Wiley & Sons, Ltd.     

Serum paraoxonase-1 (PON1) activities (PONase/AREase) and polymorphisms in patients with type 2 diabetes mellitus in a North-West Indian population

Objective

Paraoxonase-1 (PON1), an HDL-C associated enzyme, protects lipoproteins from oxidation. There is evidence that PON1 enzyme activity is reduced in the patients with type 2 diabetes mellitus (T2DM). North-West Indian Punjabis, a distinct ethnic group has high incidence of T2DM. However till date there is no information regarding PON1 enzyme activities and PON1 polymorphisms in T2DM patients of this ethnic group.

Methods

We identified polymorphisms in the coding Q192R, L55M and promoter − 909G/C, − 162A/G, − 108C/T of the PON1 gene by using PCR-RFLP, multiplex PCR and allele specific oligonucleotide PCR assays in 250 T2DM patients and 300 healthy controls. We also assessed paraoxonase (PONase) and arylesterase (AREase) activities of PON1 enzyme.

Results

The serum PONase (114.2 vs. 178.0 nmol/min/ml) and AREase (62.7 vs. 82.5 μmol/min/ml) activities were significantly lower (p < 0.0001) in patients as compared to controls. PONase activity was affected by all the studied PON1 polymorphisms. However, AREase activity was not affected by any of these polymorphisms. Coding Q192R and promoter − 909G/C polymorphisms showed significant differences in genotypic distribution. QR, RR (Q192R) and GC, CC (− 909G/C) genotypes and L-C-A-R-G, L-T-A-R-G, L-T-G-Q-C haplotypes showed significant association with type 2 diabetes. No significant linkage disequilibrium was observed among the five polymorphisms.

Conclusion

Both PONase and AREase activities are lower in patients and this could lead to increased lipid peroxidation and accelerated atherosclerosis in them. PONase activity, but not AREase activity is influenced by PON1 polymorphisms. QR, RR, GC, CC genotypes and L-C-A-R-G, L-T-A-R-G, L-T-G-Q-C haplotypes are commoner in diabetics as compared to controls and may be related to genetic susceptibility to type 2 diabetes.