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53楼2012-02-14 20:21:46

见神一笑

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有生物学专用的词典才好啊，多谢楼主

63楼2012-02-15 08:47:50

zhangyan813

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下载了，谢谢楼主的无私分享！

64楼2012-02-15 08:48:37

hanruiyun

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谢谢

79楼2012-02-15 12:04:47

stellaever

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下载后说包含病毒立即清除

81楼2012-02-15 15:24:36

幽幽深谷竹

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81楼: Originally posted by stellaever at 2012-02-15 15:24:36:
下载后说包含病毒立即清除

我试过的，没有这种情况啊，其他人如果也有这种情况的话尽快通知我，我会处理的。

83楼2012-02-15 15:49:13

zheng~8804

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The balansiaceous endophytes produce a diversearray of secondary metabolites. Several well-studiedtoxic syndromes may develop in mammals feeding onforage grasses colonized by species of Neotyphodiumor Epichloe¨ (Lane, Christensen & Miles 2000, Schardlet al. 2004). The toxic alkaloids include the anti-insectalkaloids peramine and lolines, and the anti-vertebratealkaloids lolitrem B and ergovaline (Schardl 2001).Whereas most of the metabolites are of fungal origin,there is evidence of biosynthetic interaction. Shelbyet al. (1997) found ergopeptide variants that wereapparently modified by plant metabolism. Justus, Witte
& Hartmann (1997) reported traces of loline even inuninfected plants of Festuca pratensis. Their chemistryand activity have been extensively reviewed and summarizedby Lane et al. (2000).Sincecolonisation of the host is primarily intercellular,the endophytes are dependent on nutrients ofthe apoplast for growth. As summarized by Bacon &White (2000), only a few studies deal with translocationand the specific physiology on nutrient exchange oraccumulation in vivo. For example, Schmid, Spiering &Christensen (2000) studied distribution and nutrition ofthe endophytes in planta. And more recently, Pan &Clay (2004) found that 14C movement from labelledleaves was greater for infected stolons than for those ofnon-infected plants. Studies on enzyme activities, concentrationsof amino acids, and ammonium, indicatethat the interaction significantly alters at least nitrogenmetabolism. Nevertheless, there may be an inducedplant defence reaction; Roberts et al. (1992) found thatendophyte-infected plants producedgreater amountsof chitinase than uninfected plants.Even though some balansiaceous endophytes contributenothing to the fitness of their hosts and mayeven be antagonistic (Sinclair & Cerkauskas 1996,Faeth & Fagan 2002, Sieber 2002, Schardl et al. 2004),their symbiosis with their hosts is widely accepted asbeing mutualistic (Schardl & Clay 1997). Physiologicalstudies (Schardl 2001) indicate that signals communicatingbetween E. festucae and host plants ensure adelicately balanced interaction between the partners.The primary benefits for the fungal partner are nutritional,but also include protection from abiotic stress(Bacon & Hill 1996), for example, desiccation, as wellas from competing epiphytic organisms (White et al.2000). The main advantage of the interaction forplants is presumably protection against herbivory bytoxic alkaloids produced in the symbiotic association.Additionally, the endophyte may mediate induced resistance,i.e. as an extension of the defensive mutualismhypothesis ; the activation of the host defence throughconstitutive and induced resistance (Bultman &Murphy 2000). The expectation of induced resistancein infected plants is strengthened by reports thatenvironmental stresses can stimulate the productionof mycotoxins in endophyte-infected plants (Bultman& Murphy 2000).

88楼2012-02-15 21:34:00