Tetrahymena Metallothioneins Fall into Two Discrete Subfamilies

BACKGROUND: Metallothioneins are ubiquitous small, cysteine-rich, multifunctional proteins which can bind heavy metals. METHODOLOGY/PRINCIPAL FINDINGS: We report the results of phylogenetic and gene expression analyses that include two new Tetrahymena thermophila metallothionein genes (MTT3 and MTT5). Sequence alignments of all known Tetrahymena metallothioneins have allowed us to rationalize the structure of these proteins. We now formally subdivide the known metallothioneins from the ciliate genus Tetrahymena into two well defined subfamilies, 7a and 7b, based on phylogenetic analysis, on the pattern of clustering of Cys residues, and on the pattern of inducibility by the heavy metals Cd and Cu. Sequence alignment also reveals a remarkably regular, conserved and hierarchical modular structure of all five subfamily 7a MTs, which include MTT3 and MTT5. The former has three modules, while the latter has only two. Induction levels of the three T. thermophila genes were determined using quantitative real time RT-PCR. Various stressors (including heavy metals) brought about dramatically different fold-inductions for each gene; MTT5 showed the highest fold-induction. Conserved DNA motifs with potential regulatory significance were identified, in an unbiased way, upstream of the start codons of subfamily 7a MTs. EST evidence for alternative splicing in the 3′ UTR of the MTT5 mRNA with potential regulatory activity is reported. CONCLUSION/SIGNIFICANCE: The small number and remarkably regular structure of Tetrahymena MTs, coupled with the experimental tractability of this model organism for studies of in vivo function, make it an attractive system for the experimental dissection of the roles, structure/function relationships, regulation of gene expression, and adaptive evolution of these proteins, as well as for the development of biotechnological applications for the environmental monitoring of toxic substances

Cambios bioquímicos en respuesta al ataque de roya en plantaciones de café

Abstract: Plants use various mechanisms to defend against pathogenic fungi attack. Some of these mechanisms include the increase of secondary metabolites, antioxidant and hydrolytic enzymes and polysaccharides that cause death or reduce the progression of pathogenic fungi. Hemileia vastatrix (coffee rust) is a biotrofo fungus that causes severe damage to coffee plantations. Occasionally, plants with rust absence of symptoms may be observed in coffee plantations. The study of these asymptomatic plants is of paramount importance for conservation and breeding of resistant germplasm to H. vastatrix. For the study, plants that did not have symptoms during the incidence of the disease were called uninfected (Ni) and those that had them infected (i). Two periods were evaluated: before and during rust infection, in Ni and i plants grown in the field under an organic production system. In this study enzymatic activity of quitinase, β-1-3 glucanase and peroxidase were determined. Additionally, total phenols, chlorogenic (3-CQA), criptochlorogenic (4-CQA), neochlorogenic (5-CQA), pherulic (AF), cafeico (AC), gallic acids and cafeine (Caf) were quantified in infected or non-infected C. arabica plants. No differences (p<0.05) were found in the concentration of 3-CQA and caffeic acid in the i and Ni plants in the two periods evaluated. The concentration of 5-CQA was 5.3 times lower in Ni plants compared to i during rust infection, however, this metabolite was not detected prior to the incidence of rust infection. The concentration of ferulic acid was higher in the Ni before infection, while the content of gallic acid in the i. Chitinase activity was higher in Ni and this activity increased during infection, glucanases was higher in i and peroxidase was higher in Ni in both periods. The results suggest that the resistance of coffee plants to rust disease is related to the presence of phenolic compounds and pathogenesis-related proteins (PR) such as chitinases, glucanases and peroxidase activities.Resumen: Las plantas utilizan diversos mecanismos para defenderse del ataque de hongos patógenos. Algunos de estos mecanismos incluyen el aumento de metabolitos secundarios, antioxidantes, enzimas hidrolíticas y polisacáridos que causan la muerte o reducen la progresión de hongos patógenos. Hemileia vastatrix (roya del café) es un hongo biótrofo que causa graves daños a las plantaciones de café. Ocasionalmente, se pueden observar plantas con ausencia de síntomas. El estudio de estas plantas asintomáticas es de suma importancia para la conservación y mejoramiento del germoplasma resistente a H. vastatrix. Para el estudio, aquellas plantas que durante la incidencia de la enfermedad no presentaban síntomas fueron denominadas no infectadas (Ni) y las que si los presentaban como infectadas (i). Se evaluaron dos periodos: antes de la infección por roya y durante ésta, en plantas de Coffea arabica Ni e i cultivadas en campo bajo un sistema de producción orgánico. Se determinó la actividad enzimática de quitinasa, β-1-3 glucanasa y peroxidasa; además, de la cuantificación de fenoles totales, ácido clorogénico (3-CQA), ácido criptoclorogénico (4-CQA), ácido neoclorogénico (5-CQA), ácido ferúlico (AF), ácido cafeico (AC), ácido gálico (AG) y cafeína (Caf). No se encontraron diferencias (p<0.05) en la concentración de 3-CQA y ácido cafeico en las hojas de plantas i y Ni en los dos periodos evaluados. La concentración de 5-CQA fue 5.3 veces menor en plantas Ni en comparación con las i durante la infección por roya, sin embargo, este metabolito no se detectó antes de la incidencia de ésta. La concentración de ácido ferúlico fue mayor en las Ni antes de la infección, mientras que el contenido de ácido gálico en las i. La actividad de las quitinasas fue mayor en las Ni y esta actividad aumentó durante la infección, la de glucanasas fue mayor en las i y las peroxidasas fueron mayores en las Ni en los dos periodos. Los resultados sugieren que la resistencia de las plantas de café a la enfermedad por roya está relacionada por la presencia de compuestos fenólicos y proteínas relacionadas con la patogénesis (PR) como la quitinasa, glucanasa y peroxidasa

Influence of vermicomposting on solid wastes decomposition kinetics in soils*

The effect of vermicomposting on kinetic behavior of the products is not well recognized. An incubation study was conducted to investigate C mineralization kinetics of cow manure, sugarcane filter cake and their vermicomposts. Two different soils were treated with the four solid wastes at a rate of 0.5 g solid waste C per kg soil with three replications. Soils were incubated for 56 d. The CO2-C respired was monitored periodically and a first-order kinetic model was used to calculate the kinetic parameters of C mineralization. Results indicated that the percentage of C mineralized during the incubation period ranged from 31.9% to 41.8% and 55.9% to 73.4% in the calcareous and acidic soils, respectively. The potentially mineralizable C (C 0) of the treated soils was lower in the solid waste composts compared to their starting materials. Overall, it can be concluded that decomposable fraction of solid wastes has decreased due to vermicomposting