EPR studies on gamma-irradiated barley seeds: identification of trapped electrons

Evaluation of mature miR398 family, expression analysis and the post-transcriptional regulation evidence in gamma-irradiated and nitrogen-stressed Medicago sativa seedlings

BACKGROUND

The miR398 (microRNA398) posttranscriptionally regulates the superoxide dismutase (Cu/Zn-SOD).

MATERIALS AND METHODS

The miR398 level was quantitated in gamma-irradiated (20Gy and 200Gy) and nitrogen-stressed seedlings by stem-loop RT-PCR (Real Time-Polymerase chain reaction). The positional preference of nucleotide (nt) for miR398 families and new targets was done. The SOD enzyme was assayed in native PAGE (Polyacrylamide gel electrophoresis).

RESULTS

A relative increase in miR398-3p expression in the roots, and reduction in shoots for gamma-irradiated tissue and downregulation in miR398-5p in shoots is noted. The nitrogen stress shows upregulation of miR398-3p in roots and shoots, whereas the expression of miR398-5p is upregulated in roots and downregulated in shoots. Positional preference in miR398-3p for 1-14 nt is 90% conserved unlike miR398-5p where no nucleotide positional preference is seen. Targets obtained were functionally characterized.

CONCLUSIONS

The mature miR398-5p and miR398-3p levels estimated in gamma-irradiated (20 and 200Gy) and nitrogen-stressed Medicago sativa seedlings show differential levels in roots and shoots. Native PAGE of Cu/Zn-SOD suggests its negative correlation with miR398 in shoots of irradiated and nitrogen-stressed samples. The nucleotide preferences for the nucleotide for a given position and functional characterization of targets are reported herein.

The impact of short-term UV irradiation on grains of sensitive and tolerant cereal genotypes studied by EPR

BACKGROUND

UV irradiation has ionisation character and leads to the generation of reactive oxygen species (ROS). The destructive character of ROS was observed among others during interaction of cereal grains with ozone and was caused by changes in structures of biomolecules leading to the formation of stable organic radicals. That effect was more evident for stress sensitive genotypes. In this study we investigated the influence of UV irradiation on cereal grains originating from genotypes with different tolerance to oxidative stress.

RESULTS

Grains and their parts (endosperm, embryo and seed coat) of barley, wheat and oat were subjected to short-term UV irradiation. It was found that UV caused the appearance of various kinds of reactive species (O₂^-• , H₂ O₂ ) and stable radicals (semiquinone, phenoxyl and carbon-centred). Simultaneously, lipid peroxidation occurred and the organic structure of Mn(II) and Fe(III) complexes become disturbed.

CONCLUSIONS

UV irradiation causes damage of main biochemical structures of plant tissues, the effect is more significant in sensitive genotypes. In comparison with ozone treatment, UV irradiation leads to stronger destruction of biomolecules in grains and their parts. It is caused by the high energy of UV light, facilitating easier breakage of molecular bonds in biochemical compounds. © 2017 Society of Chemical Industry.

Prevalence of some bacteria yeasts and molds in meat foods in San Luis, Argentina

In this work we evaluate the microbiological quality and the hygiene degree of meat foods consumed in the city of San Luis. A total of 515 meat food samples (315 from fresh sausages, 100 from hamburgers and 100 from ground beef) were processed, being the most of them non-industrial products. The microbiological quality was determined by counts of total mesophilic bacteria, coliforms, Escherichia coli, molds and yeasts, and Clostridium perfringens. The number of total mesophilic aerobes was within the 10(6) cfu/g limit set by the Argentinaan Alimentary Code (AAC). Two hundred seventy six samples exhibited E. coli levels between 10(1) and 10(3) cfu/g. The 58.26% of the samples with E. coli counts above > 10(1) cfu/g came from hamburgers and fresh sausages exceeding the AAC limits. Counts of molds and yeasts ranged between 10(3) and 10(6) cfu/g. From a total of 515 samples, 126 exhibited C. perfringens, out of which 80 (64.08%) gave counts > 10(2)/g, exceeding the limits set by the AAC. Out of these 80 samples, C. perfringens counts were above 10(5) cfu/g in 12 of them, and E. coli was also detected in 48 samples (38.10%). The samples with counts > 10(5) C. perfringens/g are potentially responsible for alimentary intoxication. The results obtained indicate the need to improve the processing and handling conditions of these products.