Detection of microwave radiation of cytochrome CYP102 A1 solution during the enzyme reaction

Microwave radiation at 3.4–4.2 GHz frequency of the cytochrome P450 CYP102 A1 (BM3) solution was registered during the lauric acid hydroxylation reaction. The microwave radiation generation was shown to occur following the addition of electron donor NADPH to a system containing an enzyme and a substrate. The radiation occurs for the enzyme solutions with enzyme concentrations of 10^?8 and 10^?9 М. The microwave radiation effect elicited by the aqueous enzyme solution was observed for the first time. The results obtained can be used to elaborate a new approach to enzyme systems research, including studying of the mechanism of interaction of a functioning enzyme system with microenvironment.     

Evidences for Chlorogenic Acid — A Major Endogenous Polyphenol Involved in Regulation of Ripening and Senescence of Apple Fruit

To learn how the endogenous polyphenols may play a role in fruit ripening and senescence, apple pulp discs were used as a model to study the influences of chlorogenic acid (CHA, a major polyphenol in apple pulp) on fruit ripening and senescence. Apple (‘Golden Delicious’) pulp discs prepared from pre-climacteric fruit were treated with 50 mg L^-1 CHA and incubated in flasks with 10 mM MES buffer (pH 6.0, 11% sorbitol). Compared to the control samples, treatment with CHA significantly reduced ethylene production and respiration rate, and enhanced levels of firmness and soluble solids content of the pulp discs during incubation at 25°C. These results suggested that CHA could retard senescence of the apple pulp discs. Proteomics analysis with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry (MALDI-TOF/TOF) revealed that the expressions of several key proteins correlated to fruit ripening and senescence were affected by the treatment with CHA. Further study showed that treating the pulp discs with CHA remarkably reduced levels of lipoxygenase, β-galactosidase, NADP-malic enzyme, and enzymatic activities of lipoxygenase and UDP-glucose pyrophosphorylase, all of which are known as promoters of fruit ripening and senescence. These results could provide new insights into the functions of endogenous phenolic compounds in fruit ripening and senescence.     

Scavenging of reactive oxygen species by a novel glucurinated flavonoid antioxidant isolated and purified from spinach

NAO is a natural water soluble antioxidant that was isolated and purified from spinach leaves. Using HPLC, NMR, and CMR spectroscopy, the main components were identified as flavonoids and p-coumaric acid derivatives. The NAO was found to be a very effective antioxidant in several in vivo and in vitro biological systems. In the present study, the antioxidant activity of the novel antioxidant glucurinated flavonoid (GF) isolated and characterized from NAO, is compared to well-known antioxidants. In addition, the direct free radical scavenging properties of the purified component GF were studied using the electron spin resonance (ESR) technique. GF and NAO were found to be superior to EGCG and NAC and to the Vitamin E homologue Trolox in inhibiting reactive oxygen species (ROS) formation in the autooxidation system of linoleic acid and in fibroblasts exposed to metal oxidation. GF and NAO were found to inhibit the ESR signal intensity of DMPO-O(2) radical formation during the riboflavin photodynamic reaction. 10 mM GF caused approximately 90% inhibition in the intensity of the ESR signal, while NAO at a concentration of 60 microg/ml caused an inhibition of about 50%. Using the Fenton reaction, GF and NAO were found to inhibit DMPO-OH radical formation. A concentration of 2 mM GF caused a 70% inhibition in the intensity of the DMPO-OH radical ESR signal, while propyl gallate at the same concentration caused only 50% inhibition. Furthermore, both GF and NAO also inhibited the (1)O(2) dependent TEMPO radical generated in the photoradiation TPPS4 system. About 80% inhibition was obtained by 4 mM GF. The results obtained indicate that the natural antioxidants derived from spinach may directly affect the scavenging of ROS and, as a consequence, may be considered as effective sources for combating oxidative damage.     

Mineral Composition of Wild Onions and Their Nutritional Value

Leaf accumulation of 11 microelements (Fe, Zn, Cu, Co, Mn, Ni, Pb, Cd, Sr, Cr, and Se) was studied in seven wild onion species of the genus Allium. A. flavescens Bess. accumulates five microelements (Cr, Ni, Cu, Zn, and Se) and also contains Fe, Co, and Mn at high concentrations. These features underlie the significant promise of this species as a means of procurement (nutritional adjustment of the content) of these microelements. The content of Cr in 100 g of leaves of this species is equivalent to 84% of the daily human need for this microelement. A. fistulosum L., A. odorum L., and the broad-leaved form of A. nutans specifically accumulate Cu, Zn, and Se. A. montanum Schmidt. is characterized by the accumulation of Zn. A. angulosum L. and A. schoenoprasum L. are characterized by the accumulation of Se. The broad-leaved forms of A. schoenoprasum L., A. nutans L., and A. odorum L. accumulate higher amounts of Zn and Cu than their narrow-leaved counterparts.     

Active site of bovine adrenocortical cytochrome P-450(11) beta studied by resonance Raman and electron paramagnetic resonance spectroscopies: distinction from cytochrome P-450scc

Cytochrome P-45011 beta was purified as the 11-deoxycorticosterone-bound form from bovine adrenocortical mitochondria and its active site was investigated by resonance Raman and EPR spectroscopies. Resonance Raman spectra of the purified sample revealed that the heme iron adopts the pure pentacoordinated ferric high-spin state on the basis of the nu 10 (1629cm-1) and nu 3 (1490 cm-1) mode frequencies, which are higher than those of the hexacoordinated ferric high-spin cytochrome P-450scc-substrate complexes. In the ferrous-CO state, a Fe2(+)-CO stretching mode was identified at 481.5 cm-1 on the basis of an isotopic substitution technique; this frequency is very close to that of cytochrome P-450scc in the cholesterol-complexed state (483 cm-1). The EPR spectra of the purified sample at 4.2 K showed ferric high-spin signals (at g = 7.98, 3.65, and 1.71) that were clearly distinct from the cytochrome P-450scc ferric high-spin signals (g = 8.06, 3.55, and 1.68) and confirmed previous assignments of ferric high-spin signals in adrenocortical mitochondria. The EPR spectra of the nitric oxide (NO) complex of ferrous cytochrome P-45011 beta showed EPR signals with rhombic symmetry (gx = 2.068, gz = 2.001, and gy = 1.961) very similar to those of the ferrous cytochrome P-450scc-NO complex in the presence of 22(S)-hydroxycholesterol and 20(R),22-(R)-dihydroxycholesterol at 77 K.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhanced detection of human immunodeficiency virus type 1-specific T-cell responses to highly variable regions by using peptides based on autologous virus sequences

The antigenic diversity of human immunodeficiency virus type 1 (HIV-1) represents a significant challenge for vaccine design as well as the comprehensive assessment of HIV-1-specific immune responses in infected persons. In this study we assessed the impact of antigen variability on the characterization of HIV-1-specific T-cell responses by using an HIV-1 database to determine the sequence variability at each position in all expressed HIV-1 proteins and a comprehensive data set of CD8 T-cell responses to a reference strain of HIV-1 in infected persons. Gamma interferon Elispot analysis of HIV-1 clade B-specific T-cell responses to 504 overlapping peptides spanning the entire expressed HIV-1 genome derived from 57 infected subjects demonstrated that the average amino acid variability within a peptide (entropy) was inversely correlated to the measured frequency at which the peptide was recognized (P = 6 x 10(-7)). Subsequent studies in six persons to assess T-cell responses against p24 Gag, Tat, and Vpr peptides based on autologous virus sequences demonstrated that 29% (12 of 42) of targeted peptides were only detected with peptides representing the autologous virus strain compared to the HIV-1 clade B consensus sequence. The use of autologous peptides also allowed the detection of significantly stronger HIV-1-specific T-cell responses in the more variable regulatory and accessory HIV-1 proteins Tat and Vpr (P = 0.007). Taken together, these data indicate that accurate assessment of T-cell responses directed against the more variable regulatory and accessory HIV-1 proteins requires reagents based on autologous virus sequences. They also demonstrate that CD8 T-cell responses to the variable HIV-1 proteins are more common than previously reported.     

Overexpression of the mango MiCO gene delayed flowering time in transgenic Arabidopsis

Plant Cell, Tissue and Organ Culture (PCTOC) - CONSTANS (CO)/CONSTANS-like (COL) genes play an important role in the photoperiodic flowering pathway. However, the functional roles of the CO/COL...     

特定化合物同位素分析技术在树木非结构性碳水化合物研究中的应用

特定化合物同位素分析(CSIA)可以实现对复杂基质中特定化合物稳定碳同位素组成(δ¹³C)的精确测定。应用此方法测定树木非结构性碳水化合物(NSC)中特定成分(如糖类、有机酸和糖醇)的δ¹³C,不仅能够追踪新同化的光合产物在树木中的运移及与外界的碳交换,还能够更敏感地指示树木生理状况对环境变化的响应。本文首先系统介绍了CSIA从样品采集、处理到δ¹³C测定的方法,然后综述了树木NSC中各成分之间及各成分在不同器官之间的δ¹³C差异,阐述了树木NSC的δ¹³C时间动态变化特征及内在机制,最后分析了NSC作为主要呼吸底物,其δ¹³C与树木呼吸释放CO₂的δ¹³C(δ¹³C_R)之间的联系,并针对CSIA分析技术在后光合分馏、树木逆境生理和年轮δ¹³C形成机制等研究的应用前景提出了展望。     

肥沃耕层构建对东北黑土区旱地土壤肥力和玉米产量的影响

有机物料还田是提高土壤肥力、改善土壤结构和增加作物产量的重要农艺措施之一。本研究通过分析有机物料深混还田构建肥沃耕层后土壤的有机质、速效养分含量和玉米产量,明确了黑土区不同土壤类型旱地土壤肥力指标和玉米产量对肥沃耕层构建方式的响应特征,以期为实现东北黑土区旱地保护性利用和农业可持续发展提供科学依据。采用小区试验与大区示范相结合的方式,在黑龙江省、吉林省和辽宁省选取9个生态类型区作为试验点,土壤类型包括黑土(中厚黑土和薄层黑土)、草甸土、黑钙土、白浆土、棕壤、暗棕壤和褐土。每个试验点均设置了玉米秸秆深混构建肥沃耕层(CF_Ⅰ)、秸秆配合有机肥深混构建肥沃耕层(CF_Ⅱ)和无有机物料还田(CK)3个处理。其中,CF_Ⅰ、CF_Ⅱ处理的小区试验和大区示范的秸秆还田量分别为10000 kg·hm^-2和全量还田,CF_Ⅱ处理的有机肥施用量为30000 t·hm^-2;CF_Ⅰ和CF_Ⅱ处理中有机物料的还田深度均为0~35 cm。结果表明: 不同土壤类型旱地的土壤肥力差异较大,不同土层表现为亚耕层土壤肥力小于耕层土壤,其中暗棕壤和白浆土尤为突出;棕壤、褐土耕层和亚耕层的土壤肥力均偏低;黑土和草甸土的质地比较黏重和犁底层较厚。在试验时间为两年以上的5个试验点中,与CK相比,CF_Ⅰ和CF_Ⅱ处理耕层的土壤有机质、碱解氮、速效磷和速效钾含量平均增加1.85 g·kg^-1、20.16 mg·kg^-1、1.56 mg·kg^-1和17.2 mg·kg^-1,亚耕层较耕层增加了2.09 g·kg^-1、12.06 mg·kg^-1、2.18 mg·kg^-1和3.84 mg·kg^-1。与CK相比,CF_Ⅰ处理显著增加了耕作层和亚耕层土壤有机质和速效磷含量,CF_Ⅱ处理显著增加了耕作层和亚耕层的全部土壤肥力指标,说明肥沃耕层构建是提高土壤肥力的重要途径,其中玉米秸秆配施有机肥是快速提升土壤肥力的有效方法。受不同地区水热条件和土壤类型等的影响,不同试验区的玉米产量差异较大;不同处理间差异显著,表现为CF_Ⅱ>CF_Ⅰ>CK,说明肥沃耕层构建方式在不同生态类型区均能有效提高玉米产量。采用玉米秸秆或者玉米秸秆配合有机肥深混的肥沃耕层构建方式能够同步培肥耕层和亚耕层土壤,提高玉米产量。不同生态类型区应根据土壤类型、有机物料来源等采取相应的肥沃耕层构建方式,建议在有机肥源充足的区域,优先采用秸秆配合有机肥深混构建肥沃耕层。     

阴道微生态在早产中的研究进展

阴道微生态是由阴道的局部解剖结构、周期性的内分泌变化、阴道局部免疫系统和阴道内微生物菌群共同组成的阴道环境和生态系统。多项研究证实阴道微生态失调通过局部炎症因子释放、黏膜免疫应答的改变和局部代谢变化,可引起早产的发生。阴道内小分子物质如糖类、短链脂肪酸和胺类通过代谢路径和代谢产物在阴道微生态失调与早产的发病机制起作用。近年来,阴道微生态的理念得到重视,治疗方法由传统的抗生素治疗转向了综合治疗,目的是恢复正常阴道菌群和阴道上皮黏膜免疫系统。但阴道微生态与宿主之间存在复杂的相互作用,因此仍需要进一步的研究。