We describe the identification and structural characterization of a novel family of Arabidopsis genes related to ATL2 which encode a variant of the RING zinc finger domain, known as RING-H2. Analysis of genes selected by us and of sequences from Arabidopsis stored in databases permitted the prediction of several RING-H2 proteins that contain highly homologous RING domains. The ATL gene family is represented by fifteen sequences that contain, in addition to the RING, a transmembrane domain which is located in most of them towards the N-terminal end. Transgenic Arabidopsis seedlings carrying the ATL2 promoter fused to the GUS reporter gene revealed that the expression of ATL2 is rapidly induced after exposure to chitin or inactivated crude cellulase preparations. Rapid induction of transcript accumulation of another member of the ATL family was also observed under the same conditions. These results suggest that some ATLs may be involved in the early stages of the defense response triggered in plants in response to pathogen attack.
In an effort to identify novel regulatory plant genes, conditional overexpression of toxic Arabidopsis thaliana gene products in Saccharomyces cerevisiae was evaluated as a genetic selection scheme. The screening method was tested on a fraction of a cDNA expression library and led to the identification of two Arabidopsis cDNA clones that were toxic to yeast; one corresponded to histone H1 and the other to a previously unidentified gene. This new gene, named ATL2, combines a RING-like zinc-binding motif and a putative signal anchor sequence for membrane insertion in the same molecule. Furthermore, inspection of the 3' untranslated region reveals two types of sequences which appear to be key determinants in rapid transcript decay. Indeed, rapid and transient accumulation of transcript occurs in the presence of a protein synthesis inhibitor and of the growth regulator auxin. These features provide evidence that ATL2 is an early-response gene. Thus, ATL2 represents one of the first early-response plant genes to be described which possesses a distinct regulatory domain; the fact that ATL2 mRNA is induced by auxin suggests that it might have a role during the response of plants to this growth regulator.
In an effort to identify novel regulatory plant genes, conditional overexpression of toxic Arabidopsis thaliana gene products in Saccharomyces cerevisiae was evaluated as a genetic selection scheme. The screening method was tested on a fraction of a cDNA expression library and led to the identification of two Arabidopsis cDNA clones that were toxic to yeast; one corresponded to histone H1 and the other to a previously unidentified gene. This new gene, named ATL2, combines a RING-like zinc-binding motif and a putative signal anchor sequence for membrane insertion in the same molecule. Furthermore, inspection of the 3' untranslated region reveals two types of sequences which appear to be key determinants in rapid transcript decay. Indeed, rapid and transient accumulation of transcript occurs in the presence of a protein synthesis inhibitor and of the growth regulator auxin. These features provide evidence that ATL2 is an early-response gene. Thus, ATL2 represents one of the first early-response plant genes to be described which possesses a distinct regulatory domain; the fact that ATL2 mRNA is induced by auxin suggests that it might have a role during the response of plants to this growth regulator.
Nanostructured materials (NSMs) of silver (Ag@TiO2) and copper (TiO2-Cu2+) doped titanium dioxide were synthesized, fully characterized, and evaluated for their antimicrobial efficiency and effects onArabidopsis thaliana. The NSMs were prepared using an environmentally benign route. The physicochemical properties of the materials were determined with analytical techniques. These materials are active under visible light, exhibit a small size (10–12 nm), are crystalline (anatase), and liberate metal ions (Ag+and Cu2+) in solution. Microbicide activity was observed inE. coliC600 andS. cerevisiaeW303 strains treated with several concentrations of Ag@TiO2and TiO2-Cu2+, radiated and nonradiated, and after different times. Higher inactivation was achieved with Ag@TiO2inE. coli, with value of log inactivation of 2.2 with 0.5 mg/mL after 4 h, than inS. cerevisiae, with a log inactivation of 2.6 with 10 mg/mL after 24 h. The impact of these NSMs in plants was evaluated inArabidopsis thalianaCol-0 strain exposed to such materials at different conditions and concentrations, and physical and biochemical effects were analyzed. Seeds exposed to NSMs did not show effects on germination and growth. However, seedlings treated with these materials modified their growth and their total chlorophyll content.
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