pH对灵芝液态发酵代谢物及抗氧化活性的影响

已有研究报道灵芝栽培生长的最适pH在中性偏酸环境,在碱性范围的生长及代谢情况鲜见报道。本研究主要探究广泛pH对灵芝液态发酵代谢物及其抗氧化活性的影响。采用摇瓶液态培养后分析代谢物中灵芝三萜、胞内外多糖、菌丝体蛋白及抗氧化活性等指标,系统比较灵芝菌丝体在pH值2-11的生长和代谢情况。研究结果表明,灵芝菌丝体生长、合成灵芝三萜、胞内多糖、30E胞外多糖、菌丝体蛋白和菌丝体水解氨基酸的最适pH值分别为10、3、2、7、2和2。对应结果分别为17.13 g/L、33.86 mg/g、72.73 mg/g、7.86 g/L、71.42 mg/g和107.10 mg/g。比对照分别提高28.5%、77.3%、22.4%、96.5%、97.1%和70.8%。胞内多糖组分1和组分2最高分子量均在初始pH 4,分别为1.016×10⁸ g/mol和9.280×10⁴ g/mol,胞外多糖组分1最高分子量在初始pH 10,为4.946×10⁶ g/mol;对菌丝体的总抗氧化能力、1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2- picrylhydrazyl,DPPH)自由基清除能力、羟自由基清除能力分析结果表明最佳的初始pH分别为3、7、9。本研究为液态发酵方式下灵芝生长及其代谢物定向调控发酵的工艺优化提供参考依据,同时发现灵芝菌丝体中优质蛋白及抗氧化活性可在功能性食品和化妆品领域推广应用。     

脓青素对光抑制条件下菠菜叶绿体的保护作用

在有氧条件下,脓青素可以缓解强光对菠菜叶绿体电子传递的抑制作用。加入解联剂尼日利亚菌素消除跨膜质子梯度会加剧叶绿体的光抑制,但脓青素的保护作用并不消失。脓青素对光系统Ⅰ与光系统Ⅱ均表现出保护作用,但对ＰＳⅡ的保护在光抑制初期较明显;在厌氧条件下,脓青素加剧叶绿体的光抑制,引起ＤＣＩＰ光还原与水到ｐ－ＢＱ电子传递活力的降低。推测脓青素可能通过促进细胞色素ｂ５５９介导的ＰＳⅡ循环电子传递,减轻了叶绿体的光抑制。     

Interaction of synthetic peptide corresponding to signal sequence of glucitol permease of Escherichia Coli and its analogue with liposomes

The N-terminal signal sequence of glucitol pcrmease of Escherichia Coli (Gut22) and its analogue (Gut22Ana) were synthesized. The analogue had a Pro residue substituting for the His at the 7th position of Gut22 and a Val residue substituting for the Glu at the 10th position. The intrinsic fluorescence emission spectra indicated that the binding of Gut22 with lipid bilayer was much stronger than that of Gut22Ana. The leakage experiments with calcein-loaded liposomes showed that Gut22 strongly perturbed lipid bilayers while Gut22Ana did not. The apparent partition constant of Gut22 for partitioning into phosphatidylserine/phosphatidylcholine bilayers was measured; the effect of membrane potential on the interaction of Gut22 with lipid bilayers was studied and the conformation changes of Gut22 and Gut22Ana upon interacting with liposomes were studied by the method of circular dichroism analysis.     

厉螨科－新属及二新种（蜱螨亚纲：革螨股）

本文记述厉螨科一新属,邓厉螨属Ｔｅｎｇｉｌａｅｌａｐｓｇｅｎ．ｎｏｖ,其主要特征;角化较强,体毛壮,背毛２９对;颚角粗钝,具纵裂;头盖尖角形;胸板六角形,各角均尖突;殖腹板毛１对;各足股、膝节上均具长毛、模式种为天牛邓厉螨,新种Ｔｅｎｇｉｌａｅｌａｐｓｃｅｒａｍｂｙｃｉｕｓｓｐ．ｎｏｖ。另一新种为副单阳厉螨ＡｎｄｒｏｌａｅｌａｐｓＰａｒａｓｉｎｇｕｌａｒｉｓｓｐ．ｎｏｖ。模式标本均采自云南省的甲虫体上。     

Temporal and spatial variations in the oxygen-18 content of leaf water in different plant species

Temporal variations in the δ¹⁸ oxygen (δ¹⁸O) content of water transpired by leaves during a simulated diurnal cycle fluctuated around the δ¹⁸O content of the source water. Reconstructed variations in the δ¹⁸O values of leaf water differed markedly from those predicted by conventional models. Even when transpiring leaves were maintained under constant conditions for at least 3 h, strict isotopic steady-state conditions of leaf water (equality of the ¹⁸O/¹⁶O ratios in the input and transpired water) were rarely attained in a variety of plant species (Citrus reticu-lata, Citrus paradisi, Gossypium hirsutum, Helianthus annuns, Musa musaceae and Nicotinia tabacum). Isotopic analysis of water transpired by leaves indicated that leaves approach the isotopic steady state in two stages. The first stage takes 10 to 35 min (with a rate of change of about 3–3%h^?1), while in the second stage further approach to the isotopic steady state is asymptotic (with a rate of change of about 0–4% h^?1), and under conditions of low transpiration leaves can last for many hours. Substantial spatial isotopic heterogeneity was maintained even when leaves were at or near isotopic steady state. An underlying pattern in this isotopic heterogeneity is often discerned with increasing ¹⁸O/¹⁶O ratios from base to tip, and from the centre to the edges of the leaves. It is also shown that tissue water along these spatial isotopic gradients, as well as the average leaf water, can have ¹⁸O/¹⁶O ratios both lower and higher than those predicted by the conventional Craig and Gordon model. We concluded, first, that at any given time during the diurnal cycle of relative humidity the attainment of an isotopic steady state in leaf water cannot be assumed a priori and, secondly, that the isotopic enrichment pattern of leaf water reflects gradual enrichment along the water-flow pathway (e.g. as in a string of pools), rather than a single-step enrichment from source water, as is normally assumed.     

西藏厚厉螨属一新种和毛绥螨属一新种(蜱螨亚纲:厚厉螨科,裂胸螨科)

本文报道革螨二新种,西藏厚厉螨Pachylaelapsxizangensissp．nov．和亚东毛绥螨Lasioseiusyadongensissp．nov,1985年采自西藏亚东。     

中国弯茎叶蝉属一新种记述(同翅目:叶蝉科:片角叶蝉亚科)

本文记述中国弯茎叶蝉属FlexocerusKnohetFang1新种,吴萸弯茎叶蝉Flexocerusevodianussp．nov.,新种外形特征与弯茎叶蝉FlexocerusflexureuskuohetFang相似。模式标本保存在贵州农学院。     

中国厕蝇属一新种（双翅目：厕蝇科）

本文记述采自山西省的厕蝇属Ｆａｎｎｉａ Ｒ．－Ｄ．,１８３０一新种。录属于瘤胫厕蝇群ｘｃａｌａｒｉｓ－ｇｒｏｕｐ,胸刺厕蝇亚群ｆｕｓｃｕｌａ－ｓｕｂｇｒｏｕｐ,命名为突尾厕蝇Ｆａｎｎｉａ ｐｒｏｃｅｓｓｉｃａｕｄａ ｓｐ．ｎｏｖ．,新种模式标本保存于山西省大同市地方病防治所。