Relationship among physiological quality, heterosis, and amylase gene expression in maize seeds.

In this study, we analyzed heterosis, amylase enzyme gene expression, and the physiological quality of maize seeds with different genotypes and sizes, which were subjected to aging and not subjected to aging. We used seeds from 2 maize lines that differed with regard to physiological quality, the hybrid, and the reciprocal hybrid; they were classified into 2 sizes and were subjected to aging and not subjected to aging. Physiological quality was assessed by performing tests for germination, emergence, emergence speed index, and artificial aging. Expressions of the genes alpha amylase B73, alpha amylase (LOC542522), isoamylase mRNA clone 353244, and the endogenous controls ubiquitin and alcohol dehydrogenase in the seeds were studied using quantitative real-time-polymerase chain reaction. We observed heterosis for seed quality and for expression of amylase genes in the genotypes studied. We found no difference in seed quality between large and small seeds.

Physiological quality and gene expression related to heat-resistant proteins at different stages of development of maize seeds.

We quantified and characterized the expression of heat-resistant proteins during seed development of maize lines with distinct levels of tolerance to high drying temperature. A corn field was planted for multiplication of seeds of different lines, two tolerant and two non-tolerant to high drying temperatures. Harvest of the seeds was carried out at various stages of development and they were then subjected to tests of moisture content, germination, first count of germination, accelerated aging, and cold test. The seeds were stored in a freezer for later analysis of expression of heat-resistant proteins by means of real-time PCR, electrophoresis, and spectrophotometry. We observed that heat-resistant proteins are expressed in a differential manner in seeds from different lines and at different stages of development. The expression of heat-resistant proteins was earlier in lines tolerant to high drying temperatures. Greater germination and vigor values was found for seeds collected at the last stage of development.

Bioactive amines and quality of egg from Dekalb hens under different storage conditions.

The objective of this study was to investigate the possibility of using bioactive amines as an index of quality of fresh and stored eggs. Large white eggs from 24-wk-old Dekalb layers were randomly distributed in 3 groups: (i) 10 freshly laid eggs, (ii) 60 eggs stored at 25 +/- 1 degrees C and 60% RH for 30 d, and (iii) 50 eggs stored at 6 +/- 1 degrees C and 60% RH for 50 d. The eggs were weighed and the internal quality was evaluated by Haugh units (HU), pH of albumen, total solids, total volatile bases, and bioactive amines in the albumen and yolk. The fresh eggs had, on average, 56.85 g, 98.55 HU, albumen pH of 8.02, total solids of 12.17 g/100 g in the albumen and 52.43 g/100 g in the yolk, and absence of volatile bases. None of the 10 amines investigated were detected in the albumen; however, the yolk contained 0.37 mg/kg of spermidine. Throughout storage, there was a significant decrease in the weight of the egg and HU and a significant increase in the pH and in the total solids of the albumen. The decrease in HU and the increase in the total solids of the albumen were faster at 25 +/- 1 degrees C compared with 6 +/- 1 degrees C. At 50 and 30 d of storage at 6 +/- 1 and 25 +/- 1 degrees C, respectively, significant levels of total volatile bases were detected. The levels of spermidine in the yolk increased significantly at the 40th and 15th days of storage at 6 +/- 1 and 25 +/- 1 degrees C, respectively. At these storage times, the presence of putrescine and agmatine was also detected. Therefore, the presence of other amines besides spermidine or spermidine levels higher than 1.0 mg/kg in the yolk could be used as an index of quality of fresh eggs and throughout storage.