Project description:Plant mitochondria signal to the nucleus leading to altered transcription of nuclear genes by a process called mitochondrial retrograde regulation (MRR). MRR is implicated in metabolic homeostasis and responses to stress conditions. Transcriptional consequences on nuclear gene expression of mitochondrial perturbations were examined by a microarray analyses. Expression of 606 genes was altered by monofluoroacetate (MFA) inhibition of the TCA cycle in leaves of soil grown Arabidopsis plants in the dark for 10 hours. Functional gene category (MapMan) and cluster analyses showed that genes with expression levels affected by perturbation from MFA inhibition were most similarly affected by biotic stresses such as pathogens, not oxidative stresses. Overall, the data provide further evidence for the presence of mtROS-independent MRR signaling, and support the proposed involvement of MRR and mitochondrial function in plant responses to biotic stress. Three independent (bio-replicate) experiments were done using three independent plant samples in the treatments. For each, approximately 30 plants were used for the treated sample and about 30 plants were used as the control sample. Plants were treated with 5 mM monofluoroacetate in 0.01% Tween 20 and incubated in the dark at room temperature (25C) for 6 hours. RNA was isolated from the inhibitor treated and control plants and used for microarray experiments. For each independent (bio-replicate) experiment, two microarrays were utilized using Cy3 and Cy5 dye-labeled samples and dye swapping was incorporated- 2 microarrays for each of 3 independent experiments (6 microarrays total).
Project description:Skeletal muscle atrophy is a consequence of many diseases, environmental insults, inactivity, age and injury. Atrophy is characterized by active degradation and removal of contractile proteins and a reduction in fiber size. Animal models have been extensively used to identify pathways leading to atrophic conditions. Here we have used genome-wide expression profiling analysis and quantitative PCR to identify the molecular changes that occur in two clinically relevant animal mouse models of muscle atrophy, hindlimb casting and Achilles tendon laceration (tenotomy). Gastrocnemius muscle samples were collected 2, 7 and 14 days after insult. The total amount of muscle loss as measured by wet weight and muscle fiber size was equivalent between models, although tenotomy resulted in a more rapid induction of muscle atrophy. Furthermore, tentomy resulted in the regulation of significantly more mRNA transcripts then casting. Analysis of the regulated genes and pathways suggest that the mechanism of atrophy is distinct between these models. The degradation following casting appears ubiquitin-proteasome-mediated while degradation following tenotomy appears lysosomal and matrix-metalloproteinase (MMP)-mediated. This data suggests that there are multiple mechanisms leading to muscle atrophy and that specific therapeutic agents may be necessary to combat the atrophy seen under different conditions. Muscle atrophy was induced through two methods; unloading induced by tendon laceration (Tenotomy) and immobilization induced by hindlimb casting (Casting). For the tenotomy, eight week old male C57/B6 mice were anesthetized by ether inhalation and subsequent intramuscular injection of ketamine-xylazine (0.1 ml/g). The right Achilles tendon just proximal to the calcaneus was severed with a sterile scalpel. The mice were allowed to recover and move freely about their cage. An additional cohort of animals was sham operated (Sham) which involved isolation and manipulation of the Achilles tendon without laceration. For the casting, the right hindlimbs of eight week old male C57Bl/6 mice were immobilized through casting. After 2, 7 or 14 days, animals were sacrificed and the left and right gastrocnemius muscles were carefully removed, flash frozen in liquid nitrogen, and stored at -80°C for further processing. The left untreated legs served as controls. A group of naïve animals that received no treatment or manipulation was included as an additional control. Each group consisted of between 5 and 10 samples for a total of 111 individual samples.