No abstract

The excessive accumulation of body fat has become a serious problem in the broiler industry. However, the molecular mechanisms underlying the regulation of lipid metabolism-related genes in broiler chickens are not fully understood. In the present study, we investigated the role of glucagon on the expression of lipid metabolism-related genes in chicken white adipose tissue (WAT). Four hours of fasting significantly increased plasma levels of free fatty acid in broiler chickens. The mRNA levels of adipose triglyceride lipase (ATGL) and pyruvate dehydrogenase kinase 4 (PDK4) in abdominal WAT significantly increased by fasting, whereas the mRNA levels of diacylglycerol O-acyltransferase homolog 2 (DGAT2) and peroxisome proliferator-activated receptor-γ (PPARγ) significantly decreased. The results suggest that fasting stimulates lipolysis and suppresses adipogenesis and re-esterification of TG in chicken WAT. Glucagon significantly increased the mRNA levels of PDK4 in chicken primary adipocytes, whereas there were no significant changes in the mRNA levels of ATGL, DGAT2, and PPARγ. Our findings suggest that glucagon upregulates PDK4 expression and may stimulate lipolysis without affecting the expression of ATGL in chicken WAT.

Liver is the most important target organ for investigation of lipid metabolism in domestic fowls. However, little is known about the regulatory mechanism of fatty acid oxidation in chicken liver. In mammals, proliferator-activated receptor alpha (PPARα), a transcription factor, plays an essential role in the regulation of hepatic fatty acid oxidation. The aim of the present study was to investigate the regulatory mechanisms of PPARα-induced gene expression involved in hepatic fatty acid oxidation in chickens in vivo and in vitro. WY14643, a PPARα agonist, significantly increased the messenger RNA (mRNA) levels of carnitine palmitoyltransferase 1a (CPT1a) and acyl-coenzyme A oxidase (ACO), but not long-, middle- and short-chain acyl-coenzyme A dehydrogenase (LCAD, MCAD and SCAD, respectively), hydroxyacyl-coenzyme A dehydrogenase (HAD), and PPARα itself in chicken hepatoma cells. In contrast, WY14643 significantly increased the mRNA levels of CPT1a, ACO, MCAD, SCAD, HAD and PPARα in human hepatoma cells. The mRNA levels of CPT1a and ACO in the liver were significantly increased by 6 h of fasting in chickens, whereas the mRNA levels of LCAD, MCAD, SCAD and HAD were unchanged. These results suggest that, unlike in mammals, CPT1a and ACO might play an important role in PPARα-induced fatty acid oxidation in the liver of chickens.

In vertebrate embryos, dorsal midline tissues, including the notochord, the prechordal plate, and the floor plate, play important roles in patterning of the central nervous system, somites, and endodermal tissues by producing extracellular signaling molecules, such as Sonic hedgehog (Shh). In Ciona, hedgehog.b, one of the two hedgehog genes, is expressed in the floor plate of the embryonic neural tube, while none of the hedgehog genes are expressed in the notochord. We have identified a cis-regulatory region of hedgehog.b that was sufficient to drive a reporter gene expression in the floor plate. The hedgehog.b cis-regulatory region also drove ectopic expression of the reporter gene in the endodermal strand, suggesting that the floor plate and the endodermal strand share a part of their gene regulatory programs. The endodermal strand occupies the same topographic position of the embryo as does the vertebrate hypochord, which consists of a row of single cells lined up immediately ventral to the notochord. The hypochord shares expression of several genes with the floor plate, including Shh and FoxA, and play a role in dorsal aorta development. Whole-embryo single-cell transcriptome analysis identified a number of genes specifically expressed in both the floor plate and the endodermal strand in Ciona tailbud embryos. A Ciona FoxA ortholog FoxA.a is shown to be a candidate transcriptional activator for the midline gene battery. The present findings suggest an ancient evolutionary origin of a common developmental program for the midline structures in Olfactores.

The design rainfall for flood control planning is assumed to have 24 or 48 hours duration and spatially uniform distribution. However, the heavy rainfall which has short duration and small area seems to put small rivers at risk. The purpose of this study is to reveal the effects of Depth-Area-Duration (DAD) of heavy rainfall on the flood risk assessment. DAD relationship is calculated using Radar-AMeDAS rainfall data and the methods of making rainfall models holding DAD relationship are proposed. Finally, the flood risk is assessed by runoff analysis. The result says that peak flow at points on river channel tends to be maximum value when the spatial scale of heavy rain equals to the catchment area of each point. It suggests that the flood risk along the tributaries located at the upper stream of the river may be underestimated when the target rainfall is assumed to have the basin scale.