Caloric Substitution of Diets with Apple Pomace was Determined to be Safe for Renal and Bone Health Using a Growing Rat Model

Aims: To determine the safety of caloric substitution with 10% (g/kg) apple pomace to a healthy or Western diet. Study Design: Growing (age 22-29 days) female Sprague-Dawley rats were randomly assigned (n=8 rats/group) to consume a purified standard rodent diet (AIN-93G), AIN-93G/10% g/kg apple pomace (AIN/AP), Western diet, or Western/10% g/kg apple pomace (Western/AP) diets for 8 weeks. Results: Histological evaluation showed renal interstitial hypercellularity in rats fed AIN/AP, Western, and Western/AP diets. However, there were no effects on renal expression of oxidative stress and inflammatory genes or serum measures of kidney damage and function among diet groups. Apple pomace was also high in calcium which can affect calcium balance. Dietary calcium consumption was highest (P < .001) in rats consuming Western/AP. However, there were no significant differences in calcium absorption and retention among diet groups. Further, there was no evidence of renal calcification. There were also no impacts on femoral calcium, total mineral content, size or strength. Conclusions: Based on the results, apple pomace consumption was safe for renal and bone health in a rodent model, regardless of diet quality. Future preclinical studies should be conducted to further determine the efficacy and safety of apple pomace.

In silico analysis of phytohormone metabolism and communication pathways in citrus transcriptome

Plant hormones play a crucial role in integrating endogenous and exogenous signals and in determining developmental responses to form the plant body throughout its life cycle. In citrus species, several economically important processes are controlled by phytohormones, including seed germination, secondary growth, fruit abscission and ripening. Integrative genomics is a powerful tool for linking newly researched organisms, such as tropical woody species, to functional studies already carried out on established model organisms. Based on gene orthology analyses and expression patterns, we searched the Citrus Genome Sequencing Consortium (CitEST) database for Expressed Sequence Tags (EST) consensus sequences sharing similarity to known components of hormone metabolism and signaling pathways in model species. More than 600 homologs of functionally characterized hormone metabolism and signal transduction members from model species were identified in citrus, allowing us to propose a framework for phytohormone signaling mechanisms in citrus. A number of components from hormone-related metabolic pathways were absent in citrus, suggesting the presence of distinct metabolic pathways. Our results demonstrated the power of comparative genomics between model systems and economically important crop species to elucidate several aspects of plant physiology and metabolism.

Genetic machinery for RNA silencing and defense against viruses in Citrus

RNA silencing mechanisms are conserved throughout eukaryotic evolution, possibly due to their importance in viral resistance and other aspects of cell biology. Here, we explored the Citrus EST (CitEST) database in search of sequences related to the most important known genes involved in RNA silencing. Transcripts strongly matching Argonaute (AGO), Dicer-like (DCL), Hua enhancer (HEN), and RNA-dependent RNA Polymerase (RdRP) were found in many of the citrus libraries. The reads were clustered and quantified. This shows that post-transcriptional gene silencing apparatus is active in citrus. It seems plausible that a better understanding of the players of RNA silencing in Citrus spp. and related genera may help create new tools to defeat the viral diseases that affect the citrus industry. Functional analyses of these citrus genes would enable the pursuit of this hypothesis.