Sensitization biotic

In addition, the memy elements of an ecoi stem may react differentfy to variation in pollutant level or rate of deposition. Fish are often taken as the target organism in aquatic ecosystems (Minns, Elder and Moore, 1988) however, there are more sensitive biotic elements that will decline before fish are affected (Eilers, Lien and Berg, 1984). The integration of ecosystem response in relation to particular critical loads or levels is extremely difficult, particularly as both structural (species diversity, species number. 

An important factor in the response of vegetation to oxidants (primarily ozone) is the presence of biotic pathogens. Such responses have been studied from several perspectives since Yarwood and Middleton accidentally found that rust-infected bean leaves were less sensitive to photochemical oxidants (probably PAN). Several investigators have looked at the protection from ozone injury afforded to plants with active infections others have noted that ozone injury increases the sensitivity of plants to... 

The response of some plants to oxidants is conditioned by the presence or absence of biotic pathogens. Depending on the plant and the pathogen, oxidants may cause more or less injuiy to a given species. Pathogens may protect their host or make it more sensitive. The pathogens themselves may be injured or may be protected by the host plant. This subject is just beginning to be understood. 

Of the 188 studies reported in Tables 1, 2 and 3, more than half (n = 101) were conducted with two or more tests representing at least two biotic levels (i.e., test battery approach or TBA), as opposed to those performed with a single biotic level (n = 87). While test and biotic level selection may be based on a variety of reasons and study objectives (e.g., practicality, cost, personnel availability), preference for TBAs can also be influenced by the need to assess hazard at different levels so as not to underestimate toxicity. Indeed, contaminants can demonstrate trophic-level specificity (e.g., phytototoxic effects of herbicides) or they can exert adverse effects at multiple levels (e.g., particular sensitivity of cladocerans toward heavy metals in contrast to bacteria). When TBAs are used, they are mostly conducted with two, three or four trophic levels (Tab. 4). 

Bossuyt BTA, De Schamphelaere K AC, Janssen CR. 2004. Using the biotic ligand model for predicting the acute sensitivity of cladoceran dominated communities to copper in natural surface waters. Environ Sci Technol 38 5030-5037. 

Due to the complexity of organic matter sources in estuaries and the aforementioned problems associated with making only bulk measurements to constrain them, the application of chemical biomarkers has become widespread in estuarine research (see review, Bianchi and Canuel, 2001). The term biomarker molecule has recently been defined by Meyers (2003, p. 262) as compounds that characterize certain biotic sources and that retain their source information after burial in sediments, even after some alteration. This molecular information is more specific and sensitive than bulk elemental and isotopic techniques in characterizing sources of organic matter, and further allows for identification of multiple sources (Meyers, 1997, 2003). 

We have already described that a number of rhizobial LPS mutants are sym-biotically defective because they likely induce an increased defense response by the host and/or are more sensitive to the host defense response. One structural feature of rhizobial LPS that appears to be important is the presence of OPS since its absence appears to result in a more robust plant defense response. We have also suggested (above) that the lack of OPS exposes the anionic COS on the bacterial surface which may make the rhizobial cell more sensitive to antimicrobial cationic peptides. Recent work in our laboratory (Brown, unpublished) has shown that a mutation of R. leguminosarum biovar viciae 3841 which specifically results in the loss of GalA residues from the core increases resistance to cationic peptides. It has also recently been shown that R. etli CE3 mutants in IpxE and IpxF, which are unable to remove the 1 and 4 -phosphates and, therefore have LA with increased anionic character, show increased sensitivity to cationic peptides (Ingram et al., 2010). 

K. Hoppstock, F. Alt, K. Cammann, G. Weber, Determination of platinum in biotic and environmental materials. Part II a sensitive voltammetric method, Fresenius J. Anal. Chem., 335 (1989), 813D816. 

Data on acute toxicity, skin and eye irritation, skin sensitization, mutagenicity and biotic degradation were required for new substances from 10 kg. 

Initial reaction. In all known cases of effective biotic sensitization of plants reported to date, a critical factor appears to be the necrosis of host cells in the zone of initial infection. However, while non-necrotic infections are ineffective inducers, necrosis per se is not effective in inducing resistance. Injury by abiotic agents such as heat, chemicals, dry ice, or various extracts from plants and microbes does not protect cucumbers against lagenarium (8-10). Infection of tobacco by a wide variety of Peronosporales fungi other than P. tabacina frequently causes severe necrosis, but does not induce systemic resistance against blue mold (Tiizun and Kuc, unpublished). 

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