Resistance against microbes

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tabacina frequently causes severe necrosis, but does not induce systemic resistance against blue mold (Tiizun and Kuc, unpublished). 

Oleuropein, the secoiridoid responsible for the bitter taste of olives, was studied in vitro for its antimicrobial activity. Recently, it was investigated against Mycoplasma hominis, Mycoplasma fermentas, Mycoplasma pneumoniae, Mycoplasma pirum [87], O. europaea is a plant resistant to microbe and insectan attack. In particular, oleuropein has been shown to inhibit or stop the growth time of a serial of bacteria and microfungi [88]. In general, this compound is used as a food additive. 

The marine environment clearly holds a tremendous potential for the discovery of lead compounds for development of agents active against infectious diseases and parasites. Within the vast resource of marine flora and fauna are new chemotypes to stem the tide of drug-resistant microbes and insects. Tapping this biological reserve depends on the technology to collect, rapidly recognize, and characterize trace quantities of secondary metabolites. Recent advances in life-support systems and analytical instrumentation, notably with CCUBA, HPLC, NMR, and MS have made this possible. 

A new halogen-containing member of the penitrem family of indole-diterpe-noids, which have insecticidal activity (1397), is thomitrem A (1466) from Penicil-lium crustosum (1398). The novel dichlorinated calmodulin inhibitor, malbrancheamide (1467), was characterized from the fungus Malbranchea auran-tiaca (1399). The microbe Streptomyces rugosporus produces pyrroindomycin B (1468), which is active against both methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci (1400). The Chinese shrub Acacia confusa has yielded the unusual chlorotryptamine alkaloid 1469, which does not appear to be an artifactual dichloromethane adduct (1401). 

This was by far the greatest crisis the earth has ever endured. Many kinds of microbes were immediately wiped out. Microbial life had no defence against this cataclysm except the standard way of DNA replication and duplication, gene transfer and mutation. From multiple deaths and an enhanced bacterial sexuality that is characteristic of bacteria exposed to toxins came a reorganisation of the superorganism we call the microcosm. The newly resistant bacteria multiplied, and quickly replaced those sensitive to oxygen on the Earth s surface as other bacteria survived beneath them in the anaerobic layers of mud and soil. From a holocaust that rivals the nuclear one we fear today came one of the most spectacular and important revolutions in the history of life. 

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