Limited ventilation causes stress and changes in Arabidopsis morphological, physiological and molecular phenotype during in vitro growth.

A huge number of experiments in plant biology are conducted in sterile, sealed containers, providing environmental stability and full control of factors influencing the plant system. With respect to roots the in vitro growth has another benefit - the ease of conducting visual observations when grown in transparent media. Moreover, straightforward measurements of in vitro grown root systems make them a sensitive and convenient sensor of multiple stresses which may occur during experiments. In order to optimize root nematode infection tests for Arabidopsis mutants with relatively mild phenotypes, two Petri dish sealing techniques were tested (permeable medical adhesive tape and a popular non-permeable plastic film). Using standard experimental settings applied for infection tests, the root architecture, nematode infections, ion leakage, efficiency of photosynthesis, ethylene (ET) production, and CO2 accumulation were monitored in Arabidopsis thaliana Ws-0 wild-type and lsd1 (lesion stimulating disease 1) plants, which is a conditional dependent programmed cell death mutant. All tested parameters gave statistically significant differences between the analyzed sealing tapes, indicating the importance of air exchange. This factor is quite obvious but often ignored in experiments performed in Petri dishes. The results clearly indicate that stress is greater in air-tight sealed plates. These observations were supported by the great expression variation of several marker genes associated with reactive oxygen species (ROS), ET, salicylic (SA), and jasmonic acid (JA) biosynthesis and signaling in two-week-old seedlings. These results are discussed in light of the observed changes in the ET and CO2 concentration. Our results clearly indicate the importance of culture parameters for monitoring of abiotic and biotic stress responses in laboratory conditions, including accurate mutant phenotyping.

Assessment of dietary amino acid scarcity on growth and blood plasma proteome status of broiler chickens.

Dietary Lys needs for chicks were studied. A titration diet consisting of progressive amounts of dietary Lys from 0.95% up to 1.40% was fed to broiler chicks from 0 to 18 d of age. Optimal dietary Lys level was calculated using regression analysis. Body weight gain and feed conversion were maximized at Lys levels of 1.24% (1.10% digestible) and 1.27% (1.13% digestible) of diet, respectively. Blood samples were then collected from 2 groups: birds fed the lowest Lys level and birds fed dietary Lys nearest the determined requirement level (1.25% Lys). Plasma was analyzed for protein spectra via mass spectrometry and then classified by their functional characteristics. The number of proteins was similar between the 2 samples, but there was a tendency toward increased peptides for specific proteins in plasma from chicks fed adequate Lys levels. Furthermore, after these proteins were classified, more muscle-related proteins were found in plasma samples of birds fed Lys-adequate diets. It would appear that an individual dietary amino acid deficiency does not necessarily translate into decreasing protein synthesis proportionate to body weight, but rather significant changes may be occurring within the types of proteins undergoing anabolism. In conclusion, results herein illustrate the potential for using functional genomics in nutritionally related responses of poultry.