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Two aromatic species (Ocimum basilicum L. and Satureja hortensis L.) with different water requirements were submitted to varying water supply, as characterised by different soil water capacities [SWC; control (C), 70% SWC; Stress 1 (S1), 50% SWC; and Stress 2 (S2), 30% SWC] in a growth chamber. The effect of water deficit on the formation of malondialdehyde (MDA), a product of lipid peroxidation (LPO), and on superoxide dismutase (SOD) activity were evaluated at three phenological phases (before flowering, at full-flowering, and after flowering) in both plant species. The results revealed that MDA contents were significantly higher in savory than in basil. However, significant increases in MDA contents, as a consequence of changes in the water supply, were detected only in basil (by 23% and 49% in S1 and S2, respectively). In contrast, SOD activities in control plants showed similar values in both species. Elevated SOD activities were detected in basil and in savory as a reaction to water deficit stress, with maximum SOD activities occurring during full-flowering (3.212 Units mg-1 protein and 2.655 Units mg-1 protein in basil and savory, respectively). We conclude that water deficit stress (to 50% or 30% SWC) may result in increased SOD activities, which were responsible for the decreased levels of superoxide free radicals in both species examined. However, under the conditions used here, enhanced LPO was detectable only in basil, known as a plant with a high water requirement. [ABSTRACT FROM AUTHOR]

Mycotoxin production by aflatoxin B1 (AFB1) -producing Aspergillus flavus Zt41 and sterigmatocystin (ST) -hyperproducer Aspergillus creber 2663 mold strains on corn and rice starch, both of high purity and nearly identical amylose-amylopectin composition, as the only source of carbon, was studied. Scanning electron microscopy revealed average starch particle sizes of 4.54 ± 0.635 µm and 10.9 ± 2.78 µm, corresponding to surface area to volume ratios of 127 1/µm for rice starch and 0.49 1/µm for corn starch. Thus, a 2.5-fold difference in particle size correlated to a larger, 259-fold difference in surface area. To allow starch, a water-absorbing powder, to be used as a sole food source for Aspergillus strains, a special glass bead system was applied. AFB1 production of A. flavus Zt41 was determined to be 437.6 ± 128.4 ng/g and 90.0 ± 44.8 ng/g on rice and corn starch, respectively, while corresponding ST production levels by A. creber 2663 were 72.8 ± 10.0 µg/g and 26.8 ± 11.6 µg/g, indicating 3-fivefold higher mycotoxin levels on rice starch than on corn starch as sole carbon and energy sources. KEY POINTS: • A glass bead system ensuring the flow of air when studying powders was developed. • AFB1 and ST production of A. flavus and A. creber on rice and corn starches were studied. • 3-fivefold higher mycotoxin levels on rice starch than on corn starch were detected., (© 2024. The Author(s).)

Authors studied the effect of sterigmatocystin from infected corn (STC), purified sterigmatocystin (PSTC), and aflatoxin B1 from infected corn (AFB 1 ) on lipid peroxidation and glutathione redox parameters, including the expression of their encoding genes in a sub-chronic (14 days) trial. A total of 144 three-week-old cockerels was divided into four experimental groups ( n = 36 in each). Control feed was contaminated with STC or PSTC (1590 µg STC/kg or 1570.5 µg STC/kg feed), or with AFB 1 (149.1 µg AFB 1 /kg feed). Six birds from each group were sampled at day 1, 2, 3, 7 and 14 of mycotoxin exposure. As parameters of lipid peroxidation, conjugated dienes (CD) and trienes (CT) were measured in the liver, while malondialdehyde (MDA) concentration was determined in blood plasma, red blood cell hemolysate and liver. Reduced glutathione (GSH) concentration and glutathione peroxidase (GPx) activity were determined in the same samples, and expression of glutathione peroxidase 4 ( GPX4 ), glutathione synthetase ( GSS ) and glutathione reductase ( GSR ) genes was measured by RT-PCR in the liver. STC, PSTC or AFB 1 caused a slight, but not significant, increase in CD and CT levels; however, in the case of MDA, no increase was found in the liver. Glutathione redox system was activated in the liver by AFB 1 , but less markedly by STC/PSTC. PSTC and AFB 1 resulted in a higher expression of GPX4 , while GSS expression was down-regulated by AFB 1 on day 1, but up-regulated by STC on day 2 and by both mycotoxins on day 7. However, on day 14, GSS expression was down-regulated by PSTC. Expression of GSR was low on day 1 in AFB 1 and PSTC groups, but later it was up-regulated by AFB 1 . The observed changes regarding gene expression strengthen the hypothesis that the mild oxidative stress, caused by the applied STC doses, activates the glutathione redox system of broiler chickens., Competing Interests: The authors declare no conflict of interest.

A pot experiment was carried out with lemon balm (Melissa officinalis L.) and thyme (Thymus vulgaris L.). Different water supply was applied: 25%, 40% and 70% saturation of soil water capacity (SWC). Morphological traits, biomass and phenolic type active ingredients were investigated. Among the two species, main differences were registered in biomass and TPC. Lower SWC resulted in reduced biomass production of lemon balm, while the applied stress treatments did not effect the biomass of thyme. In lemon balm, highest TPC contents were measured in control plants both in shoots and roots but in thyme, the shoots showed a significantly increased TPC at the 25% SWC conditions. Neither the content of total flavonoids nor that of the rosmarinic acid was affected by the treatments. The antioxidant capacity proved to be in tight connection with the TPC in both species (r = 0.766-0.883). The rosmarinic acid content of lemon balm plants contributed to the antioxidant capacity, as well (r = 0.679-0.869).