ESTREPTOCINASA MECANISMO ACCION PDF

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It is mainly obtained form crustacean shells. Chitin and its derivatives have shown to be effective in controlling plagues and plants diseases. Their mechanism of action is strongly linked to their chemical structures. These mechanisms can result from the direct action on the pathogen or can be a consequence of its capacity to induce defensive mechanisms on plants.

In any case, the effect is their protection against various vegetable diseases, before and after harvest. The addition of chitin and its derivatives to the soil favours the growth and activity of many chitinolytic organisms that constitute biological controls and are natural enemies of many agents responsible for vegetable plagues and diseases, generating a synergistic effect. On the other side, these biopolymers also favour the growth and development of beneficial microorganisms that establish synergistic relationships with plants, such a as mycorrhizas or Rhizobium species.

On top of that, increasing the microbial population and activity in the soil improves the properties of nutrients and their availability.

La quitina y sus derivados, biopolímeros con potencialidades de aplicación agrícola

As growth regulators, it has been established that these biopolymers accelerate seeds germination, the ability of plants to grow as well as the agricultural yield. It is concluded that chitin and its derivatives have great potential for applications in mefanismo. It is foreseen that in the future these biopolymers will be used in greater extension, mainly for substituting actual chemical pesticides or as growth regulators.

Ella y sus derivados son efectivos en el control de enfermedades y plagas vegetales. For this purpose, the use of chitin and its derivatives is a promising alternative, based on its biological activity and easy-to-obtain procedures. Several studies show the mechanisms of action and the efficiency of such active principles in agriculture, mainly at laboratory scale and under controlled environmental conditions.

estreptoquinasa mecanismo de accion pdf files

However, there are few field study reports and low reproducibility of results, especially studies of scaling up technologies for applying those derivatives at open field production.

This has been influenced by dispersion of the available information, and the lack of technical and practical details required to reproduce them, among other aspects. Researches concerning these elements, from Cuba and other countries, are gathered here to facilitate the availability of data for applying chitin and its derivatives in agriculture, and the investigations aimed to introduce such bioproducts in the Cuban agriculture.

Mecanlsmo bearing a high regeneration rate, with annual estimates of at least 1 x 10 9 tons accion synthesized and degraded every year in nature 1. This substance is found in cellular structures of fungi 2bacteria 3insects 4arachnids 5crustaceans 6nematodes 7 and other invertebrates such as: Chitin is a white, partially crystalline, odorless and tasteless solid at its pure state. Therefore, chitin shows a structure that resembles cellulose, except for the carbon residue at position 2 which has an acetamide group attached to chitin instead of the hydroxyl group of cellulose Figure.

Its properties as a product vary depending on the source estreptociasa which it was obtained and prepared. This has led to further developments to improve production methods and to achieve more convenient properties for different uses As Chitin is insoluble in water, a characteristic that limits its application, working with some of its direct derivatives will be more convenient than with the natural polymer.

Chitosan is the most relevant derivative, and it can be found in nature or can be obtained in synthetic form Figurecomposed acxion by deacetylated units, influencing its chemical and biological properties. Chitosan is soluble in diluted acid solutions, and is also among the few cationic polymers found in nature, with amino groups able to get positive charges and responsible in part for its estrdptocinasa antimicrobial activity 12, The high viscosity of chitosan solutions is also a relevant characteristic that favors its biological properties, which are determined in general by a number of factors, including the average molecular weight of the polymer, acetylation degree and solution concentration, among others.

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Films and threads for dressing can be obtained from chitosan solutions for a great number of industrial accino Other chitin derivatives are oligosaccharides of 2 to 20 N-acetylglucosamine residues in length.

Their estreptocunasa molecular weights provide them with chemical and biological properties other than those of the original polymer, such as water solubility and signaling functions during symbiotic interactions in plants Chitin and all its derivatives share a high nitrogen content 6.

Nevertheless, they are also substrates very susceptible to degradation by several enzyme families, this aspect derived mecanismi their composition and natural origin The presence of functional hydroxyl and amino groups these in the deacetylated units support the formation of coordination compounds complexes with metal ions of cooper, zinc and iron and others, but not with those of alkaline e.

These complexes show a strong antimicrobial activity against some vegetable pathogens, being promising agents for agricultural application Moreover, they bear absorptive properties, very useful to remove stains 18, 19residuals from water 20and they are useful for other applications.

All these make chitin and their derivatives highly applicable to human activity Wastes coming from other marketable species as shrimp, and sea and freshwater crabs are also used.

Acicon fact, several procedures were developed to prepare chitin depending on the application. For example, the method that generates high quality and pure chitin for pharmaceutical application is regarded as one of the first among Ibero-American countries At present there are two factories in Cuba producing this pharmaceutical-grade chitin at levels overreaching the demands.

Additionally, there is a process for integral processing of the wastes 28and another designed to acion chitin and its derivatives for specific application in agriculture Four main approaches have been identified for chitin application in agriculture see table: Protection of plants from pests and diseases before and after harvest.

Enhancing of antagonist microorganisms action and biological controls. Enhancing the beneficial symbiotic plant-microorganism interactions; and 4. Regulating plant growth and development. Some results evidenced that polymeric chitin does not show a substantial antimicrobial activity affecting growth and development of plant pathogens.

This is determined by its insolubility in water and compact structure. Otherwise, its deacetylated derivative chitosan has certainly shown a potent antimicrobial activity, due to protonation of its amino groups in solution. Moreover, positively charged oligochitosans showed antifungal activity, which was absent in chitin oligomers uncharged when compared to the control treatment Vegetal membranes respond to polymeric chitin and its derivatives by surmounting a cascade of enzymatic reactions which ultimately results in induced and systemic resistance in plants This has been corroborated by isolating chitin-specific membrane receptors in soybean and rice Chitin has also been used to enhance the efficiency of natural biological controls.

Many microorganisms acting as antagonists mecanismmo chitinases against estreptocinssa pests and diseases e. These enzymes are overproduced together with other hydrolases in the presence of chitins and some of its derivatives, increasing the efficiency of microorganisms acting as biocontrols Acdion findings demonstrate that chitin and its derivatives can improve legume- Rhizobium symbiosis. Nodulation factors excreted by Rhizobium sp. Therefore, chitin can be provided as precursor substrate for these metabolites.

Other types of interactions e. Moreover, chitin was demonstrated to favor plant growth and development by increasing enzyme and metabolic functions, also accelerating germination Crop protection from pests and diseases Chitin and its derivatives have been used to protect crops from diseases either before or after harvest, directly or indirectly, depending on the specific plant-pathogen interaction.

Some results of such applications are shown in the following by pathogen group. Antifungal activity Plants are protected from fungi by the biological activity mecanlsmo chitin and its derivatives through two main mechanisms: Regarding chitin derivatives, especially those bearing highly mecansimo functional groups as chitosan and derived compounds, they were demonstrated as having direct antifungal activity on phytopathogenic fungi Several studies confirmed these results, ,ecanismo the relevance of fungal type In vitro inhibition of mycelial growth fluctuated in a sample of 14 different phytopathogenic fungi, depending on acetylation degree and molecular weight of esgreptocinasa chitin derivatives assayed.

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Nevertheless, a tendency towards growth inhibition was observed by increasing both deacetylation and molecular weight of the compounds tested. Regarding the mechanisms of action of chitin and its derivatives, it was established acciin free amino group protonation on a slightly acidic medium enhanced antifungal activity. Some authors point out that the positively charged compounds interact better at mecanismp level, improving the expression of genes involved in plant resistance There are other reports on their interaction with the plasma membrane, interfering with its functions as chelating agents and modifying membrane permeability It is also suggested that the activity affects Rhizopus stolonifer in influencing the balance between biosynthesis and meecanismo of cell wall components.

Noteworthy, the pH of the resulting solution affects the positive charge of amino groups, since fungi growth was just slightly inhibited at pH 6, while sporulation remained fully arrested Some studies have remarked the relevance of fungi family and genus on its susceptibility to chitin derivatives, with cell wall chitin content as a factor that explains the differences observed.

Mycelial growth of some species as Phythophtora parasitica are inhibited at low chitosan concentrations i. Particularly, the artificial stimulation of plant defensive mechanisms have been studied by adding chitin derivatives as elicitors elicitationsince they become generally protected by systemic resistance from several diseases Results from investigations in rice demonstrated that seeds recovered with chitin derivatives increase hydrolytic enzymes production, such as chitinases and b 1, 3 glycanases which degrade chitin and 1, 3 glycans, respectively.

As we know, these two types of compounds are major cell wall components in most phytopathogenic fungi 53, Besides, chitosan and its positively charged derivatives stimulate plants to produce antifungal metabolites In spite of these evidences, there are reports on derivatives lacking positive charge, and even insoluble polymeric chitin, as inducing high levels of very potent antimicrobial metabolites e.

Among these molecules are momilactones and oryzalexins, which completely inhibit Pyricularia grisea Sacc at concentrations as low as 0. Other authors suggest that oligomers could be more effective in plants, because of its smaller molecular size which determines mecsnismo root absorption, or by foliar aspersion Several crops have been evaluated for protection from diseases caused by soil fungal pathogens by delivering chitin derivatives.

For example, chitosan protects pepper from Phytium aphanidermatum In tomato, partially acetylated chitosans delivered either by seed or foliar routes induced hydrolytic enzyme production and estreptocinaas Fusarium oxysporum licopersici – caused lesions Other authors found a lower incidence of diseases estreptocihasa wheat and rice, leading to significantly increased production yields Protection was also detected in peanut, as well as defensive mechanisms Noteworthy, most of these investigations used chitosan and mecansimo derivatives seeking for protection, but it was clearly established that acetylation is essential to induce production of hydrogen peroxide and other oxygen reactive species.

These metabolites are the key components triggering enzymatic reaction pathways which ultimately lead to systemic resistance mecanosmo plants Although uncharged, chitin and its fragments are potentially protective in plants, mostly in monocotyledonous. Chitin but not chitosan oligomers promote several defensive reactions in rice, wheat, arabidopsis, water melon, bean, soybean and peanut 34, 58, 61, These responses include the accumulation of pathogenesis-related proteins e. Antiviral activity Chitin accon display antiviral activity, specially the cationic ones which are very potent at inhibiting locally-produced etsreptocinasa injuries.

Its action is attributed to virus infection dependence on surface charge Nonetheless, neither acetylation nor molecular weight correlates with antiviral activity, since acetylated chitin oligomers inhibited the mosaic alfalfa virus in bean at 0.

Additionally, the antiviral activity varies among plant species. Evidences point towards two mechanisms: Noteworthy, these compounds protect plants not only from mechanically but also from vector-borne diseases All these results are very valuable for agriculture, due to the almost absolute lack of chemicals able to control plant viral infections.

Anti-bacterial activity in plants Chitin derivatives can jecanismo protect plants from bacterial diseases.