Acute reduction of neuronal RNA binding Elavl2 protein and Gap43 mRNA in mouse hippocampus after kainic acid treatment.

Activity-dependent gene regulation in neurons has been hypothesized to be under transcriptional control and to include dramatic increases in immediate early genes (IEGs) after neuronal activity. In addition, several reports have focused on post-transcriptional regulation, which could be mediated by neuronal post-transcriptional regulators, including RNA binding proteins (RNABPs). One such protein family is the neuronal Elavls (nElavls; Elavl2, Elavl3, and Elavl4), whose members are widely expressed in peripheral and central nervous system. Previous reports showed that Elavl3 and 4 are up-regulated following repeated stimulation such as during cocaine administration, a seizure, or a spatial discrimination task. In this study, we focused on Elavl2, a candidate gene for schizophrenia and studied its role in neuronal activity. First we found that Elavl2 has a cell-type specific expression pattern that is highly expressed in hippocampal CA3 pyramidal neurons and hilar interneurons using Elavl2 specific antibody. Second, unexpectedly, we discovered that the Elavl2 protein level in the hippocampus was acutely down-regulated for 3 h after a kainic acid (KA)-induced seizure in the hippocampal CA3 region. In addition, level of Gap43 mRNA, a target mRNA of Elavl2 is decreased 12 h after KA treatment, thus suggesting the involvement of Elavl2 in activity-dependent RNA regulation.

Loss of the Homeodomain Transcription Factor Prep1 Perturbs Adult Hematopoiesis in the Bone Marrow.

Prep1, a TALE-family homeodomain transcription factor, has been demonstrated to play a critical role in embryonic hematopoiesis, as its insufficiency caused late embryonic lethality associated with defective hematopoiesis and angiogenesis. In the present study, we generated hematopoietic- and endothelial cell-specific Prep1-deficient mice and demonstrated that expression of Prep1 in the hematopoietic cell compartment is not essential for either embryonic or adult hematopoiesis, although its absence causes significant hematopoietic abnormalities in the adult bone marrow. Loss of Prep1 promotes cell cycling of hematopoietic stem/progenitor cells (HSPC), leading to the expansion of the HSPC pool. Prep1 deficiency also results in the accumulation of lineage-committed progenitors, increased monocyte/macrophage differentiation and arrested erythroid maturation. Maturation of T cells and B cells is also perturbed in Prep-deficient mice. These findings provide novel insight into the pleiotropic roles of Prep1 in adult hematopoiesis that were unrecognized in previous studies using germline Prep1 hypomorphic mice.

RNA-binding protein research with transcriptome-wide technologies in neural development.

An increasing number of studies have demonstrated that neural RNA-binding proteins (nRNABPs) participate in several steps of neural development through post-transcriptional regulation of their RNA targets (Grabowski Curr Opin Genet Dev 21:388-394, 2011). Classical genetics and in vitro biochemical approaches have identified several important RNA targets of nRNABPs linked to cell-fate decision and neuronal functions. In recent years, new technologies, such as unbiased in vivo protein-RNA interaction approaches, high-throughput sequencing-cross-linked immunoprecipitation (HITS-CLIP), microarrays, RNAseq and others, have been developed. The use of these with genetics has succeeded in defining a dynamic range of RNA targets of RNABPs at the transcriptome-wide level. This new platform also provides the mechanistic insights into a specific biological function of nRNABPs. This review highlights the discoveries and challenges of the interplay between the nRNABPs and their biological functions in neural development.

Determination of short-chain fatty acids in rat and human feces by high-performance liquid chromatography with electrochemical detection.

A simple method for determining short-chain fatty acids (SCFAs) in rat and human feces was developed using high-performance liquid chromatography with electrochemical detection (HPLC-ECD). A two-channel HPLC-ECD system was fabricated using an ion exclusion column and an electrochemical detector with a glassy carbon working electrode. Aqueous solutions of 0.1 mM HClO(4) and of ethanol containing 2-methyl-1,4-naphthoquinone served as a mobile phase and a quinone solution, respectively. Peak areas for lactic, acetic, propionic, butyric, isovaleric, and valeric acids at a detection potential of -0.9 V vs. an Ag/AgCl electrode showed a linear relationship with the acid amount in the range 0.1 to 40 nmol. Standard acids at 4 nmol were determined ten times with relative standard deviations (RSD) of less than 2.0%. The analytical results of healthy human feces were measured within 35 min. RSD (n = 5) in all SCFAs were less than 2.7%, and recoveries of SCFAs were more than 92%. The present method was characterized by reproducibility with the simple and rapid procedure without derivatization of analytes, and it has the potential for clinical and biomedical applications.

Elimination of a back-reflected TE mode in a TM-mode optical isolator with a Mach-Zehnder interferometer.

Eimination of a back-reflected TE mode traveling in a TM-mode optical isolator was investigated. The optical isolator had a Mach-Zehnder interferometer that included a polarization-dependent reciprocal phase shifter in one of the arms. The reciprocal phase shift was achieved by an optical path difference between the two arms. By adjustment of the length of the reciprocal phase shifter, the interferometer prevented the back-reflected TE mode from coupling into an input port of the isolator. An extinction ratio of more than 18 dB was obtained against the back-reflected TE mode at a wavelength of 1.55 microm.