Epitranscriptomic profile of Lactobacillus agilis and its adaptation to growth on inulin

Iron Fortification and Inulin Supplementation in Early Infancy: Evaluating the Impact on Iron Metabolism and Trace Mineral Status in a Piglet Model

Background

Infant formula in the United States contains abundant iron, raising health concerns about excess iron intake in early infancy.

Objectives

Using a piglet model, we explored the impact of high iron fortification and prebiotic or synbiotic supplementation on iron homeostasis and trace mineral bioavailability.

Methods

Twenty-four piglets were stratified and randomly assigned to treatments on postnatal day 2. Piglets were individually housed and received an iron-adequate milk diet (AI), a high-iron milk diet (HI), HI supplemented with 5% inulin (HI with a prebiotic [HIP]), or HIP with an oral gavage of Ligilactobacillus agilis YZ050, an inulin-fermenting strain, every third day (HI with synbiotic [HIS]). Milk was provided in 14 meals daily, mimicking formula feeding in infants. Fecal consistency score and body weight were recorded daily or every other day. Blood and feces were sampled weekly, and tissues collected on postnatal day 29. Data were analyzed using mixed model analysis of variance with repeated measures whenever necessary.

Results

Diet did not affect growth. HI increased hemoglobin, hematocrit, and serum iron compared to AI. Despite marginal adequacy, AI upregulated iron transporter genes and maintained satisfactory iron status in most pigs. HI upregulated hepcidin gene expression in liver, caused pronounced tissue iron deposition, and markedly increased colonic and fecal iron. Inulin supplementation, regardless of L. agilis YZ050, not only attenuated hepatic iron overload but also decreased colonic and fecal iron without altering pH or the expression of iron regulatory genes. HI lowered zinc (Zn) and copper (Cu) in the duodenum and liver compared to AI, whereas HIP and HIS further decreased Zn and Cu in the liver and diminished colonic and fecal trace minerals.

Conclusions

Early-infancy excessive iron fortification causes iron overload and compromises Zn and Cu absorption. Inulin decreases trace mineral absorption likely by enhancing gut peristalsis and stool frequency.

Epitranscriptomic Mass Spectrometry

Every chemical group that is added to any one of the canonical ribonucleotides in a transcript would create a specific RNA modification. Currently, 170+ RNA modifications have been identified. A specific epitranscriptome refers to all the RNA modifications in a given biological system and is considered to play an important role in the regulations of cellular activities. Mass spectrometry-based methods have proven to be the most accurate way to identify RNA modifications and determine the amount of each detectable modification. Relating to the recent development of mapping specific RNA modifications within a transcriptome, the profiling of all RNA modifications can serve as a prescreening tool for mapping and provides support for analyzing the data obtained from mapping. In this chapter, the details for setting up a commonly used mass spectrometry-based method to profile all the RNA modifications in specific epitranscriptomes are described, and the possible options if available are discussed.

The Dihydrouridine landscape from tRNA to mRNA: a perspective on synthesis, structural impact and function

The universal dihydrouridine (D) epitranscriptomic mark results from a reduction of uridine by the Dus family of NADPH-dependent reductases and is typically found within the eponym D-loop of tRNAs. Despite its apparent simplicity, D is structurally unique, with the potential to deeply affect the RNA backbone and many, if not all, RNA-connected processes. The first landscape of its occupancy within the tRNAome was reported 20 years ago. Its potential biological significance was highlighted by observations ranging from a strong bias in its ecological distribution to the predictive nature of Dus enzymes overexpression for worse cancer patient outcomes. The exquisite specificity of the Dus enzymes revealed by a structure-function analyses and accumulating clues that the D distribution may expand beyond tRNAs recently led to the development of new high-resolution mapping methods, including Rho-seq that established the presence of D within mRNAs and led to the demonstration of its critical physiological relevance.