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Motilin (MLN) is a peptide hormone originally isolated from the mucosa of the porcine intestine. Its orthologs have been identified in various vertebrates. Although MLN regulates gastrointestinal motility in tetrapods from amphibians to mammals, recent studies indicate that MLN is not involved in the regulation of isolated intestinal motility in zebrafish, at least in vitro. To determine the unknown function of MLN in teleosts, we examined the expression of MLN and the MLN receptor (MLNR) at the cellular level in Japanese medaka (Oryzias latipes). Quantitative PCR revealed that mln mRNA was limitedly expressed in the gut, whereas mlnr mRNA was not detected in the gut but was expressed in the brain and kidney. By in situ hybridization and immunohistochemistry, mlnr mRNA was detected in the dopaminergic neurons of the area postrema in the brain and the noradrenaline-producing cells in the interrenal gland of the kidney. Furthermore, we observed efferent projections of mlnr-expressing dopaminergic neurons in the lobus vagi (XL) and nucleus motorius nervi vagi (NXm) of the medulla oblongata by establishing a transgenic medaka expressing the enhanced green fluorescence protein driven by the mlnr promoter. The expression of dopamine receptor mRNAs in the XL and cholinergic neurons in NXm was confirmed by in situ hybridization. These results indicate novel sites of MLN activity other than the gastrointestinal tract. MLN may exert central and peripheral actions through the regulation of catecholamine release in medaka. [ABSTRACT FROM AUTHOR]

Lysozyme is one of the most prominent antimicrobial peptides and has been identified from many mammalian species. However, this enzyme has not been studied in the order Insectivora, which includes the most primitive placental mammals. Here, we done the lysozyme cDNA from Suncus murinus (referred to as suncus, its laboratory name) and compare the predicted amino acid sequence to those from other mammalian species. Quantitative PCR analysis revealed a relatively higher expression of this gene in the spleen and gastrointestinal tract of suncus. The lysozyme-immunopositive (ip) cells were found mainly in the red pulp of the spleen and in the mucosa of the whole small intestine, including the follicle-associated epithelium and subepithelial dome of Peyer's patches. The lysozyme-ip cells in the small intestine were mostly distributed in the intestinal crypt, although lysozyme-expressing cells were found not only in the crypt but also in the villi. On the other hand, only a few lysozyme-ip cells were found in the villi and some granules showing intense fluorescence were located toward the lumen. As reported for other mammals, Ki67-ip cells were localized in the crypt and did not co-localize with the lysozyme-ip cells. Moreover, fasting induced a decrease in the mRNA levels of lysozyme in the intestine of suncus. In conclusion, we firstly identified the lysozyme mRNA sequence, clarified expression profile of lysozyme transcripts in suncus and found a unique distribution of lysozyme-producing cells in the suncus intestine. [ABSTRACT FROM AUTHOR]

The adenohypophysis is formed from the oral ectoderm and consists of the pars distalis (PD), pars intermedia, and pars tuberalis (PT). The mechanisms of PD development have been extensively studied, and the cellular differentiation of the PD is well understood. However, the morphogenesis and differentiation of the PT are still unclear, and the genes expressed during PT development remain largely unknown. We have explored genes specifically expressed in the PT during embryonic development and analyzed their spatiotemporal expression patterns. Microarray analysis of laser-captured PT and PD tissues obtained from chick embryos on embryonic day 10 (E10.0) has shown high expression of Cytokine-like 1 ( CYTL1) and Gap junction protein alpha 5 ( GJA5) genes in the PT. Detailed analysis of these spatiotemporal expression patterns during chick embryo development by in situ hybridization has revealed that CYTL1 mRNA first appears in the lateral head ectoderm and ventral head ectoderm at E1.5. The expression of CYTL1 moves into Rathke's pouch at E2.5 and is then localized in the PT primordium where it is continuously expressed until E12.0. GJA5 mRNA is transiently detected in the PT primordium from E6.0 to E12.0, whereas its expression is not detected in the PD during development. Thus, these genes might be involved in the regulation mechanisms of PT development and could be useful markers for PT development. [ABSTRACT FROM AUTHOR]

Secretoglobin (SCGB) 3A2 was originally identified as a downstream target for the homeodomain transcription factor NKX2-1 in the lung. NKX2-1 plays a role in the genesis and expression of genes in the thyroid, lung and ventral forebrain; Nkx2- 1-null mice have no thyroid and pituitary and severely hypoplastic lungs and hypothalamus. To demonstrate whether SCGB3A2 plays any role in pituitary hormone production, NKX2-1 and SCGB3A2 expression in the mouse pituitary gland was examined by immunohistochemical analysis and RT-PCR. NKX2-1 was localized in the posterior pituitary lobe, whereas SCGB3A2 was observed in both anterior and posterior lobes as shown by immunohistochemistry and RT-PCR. Expression of CCAAT-enhancer binding proteins (C/EBPs), which regulate mouse Scgb3a2 transcription, was also examined by RT-PCR. C/EBPβ, γ, δ and ζ were expressed in the adult mouse pituitary gland. SCGB3A2 was expressed in the anterior and posterior lobes from postnatal days 1 and 5, respectively and the areas where SCGB3A2 expression was found coincided with the area where FSH-secreting cells were found. Double-staining for SCGB3A2 and pituitary hormones revealed that SCGB3A2 was mainly localized in gonadotrophs in 49 % of FSH-secreting cells and 47 % of LH-secreting cells. In addition, SCGB3A2 dramatically inhibited LH and FSH mRNA expression in rat pituitary primary cell cultures. These results suggest that SCGB3A2 regulates FSH/LH production in the anterior pituitary lobe and that transcription factors other than NKX2-1 may regulate SCGB3A2 expression. [ABSTRACT FROM AUTHOR]

The primordium of the mammalian adenohypophysis derived from Rathke’s pouch (RP) is known to be formed by oral ectoderm invagination. However, in the early phase of pituitary development, the detailed process by which the oral ectoderm develops into the adenohypophysis remains largely unknown. Using high-resolution non-radiolabeled in situ hybridization and the BrdU and TUNEL methods, we have examined the detailed expression pattern of factors involved in the formation of RP of chicken and the changes in the mitotic and apoptotic cell regions in RP. In the chicken embryo, Sonic hedgehog (Shh) mRNA was initially expressed in the stomodeal plate but not in the oral ectoderm. After prospective diencephalon had detached from the oral ectoderm, another Shh-expressing region appeared in the most rostral part of the recess. LIM homeobox gene 3 (Lhx3) mRNA first appeared in the anterior area of Rathke’s recess, and expression then spread to the caudal region. αGSU mRNA-expressing cells were observed at both ends of the Lhx3-expressing region, and thereafter the expression area moved to the posterior region. Furthermore, a close overlap was found between the proliferating region and Lhx3 mRNA-expressing area, and TUNEL-positive cells appeared in Seessel’s pouch derived from the foregut. Thus, the primordium of the pituitary gland corresponding to the Lhx3-expressing region is surrounded by the Shh-expressing region, which appears in two steps, and the mass growth and invagination of RP of chicken result from the coordination of the dorsal extension of the anterior region and the ventral extension of the posterior region of RP. [ABSTRACT FROM AUTHOR]