The circadian system and melatonin: lessons from rats and mice

The circadian system (CS) comprises three key components: (1) endogenous oscillators (clocks) generating a circadian rhythm; (2) input pathways entraining the circadian rhythm to the astrophysical day; and (3) output pathways distributing signals from the oscillator to the periphery. This contribution briefly reviews some general aspects of the organization of the rodent CS and pays particular attention to recent results obtained with various mouse strains, related to molecular mechanisms involved in entraining the endogenous clock and the role of the pineal hormone melatonin as a hand of the endogenous clock.     

Molecular cloning and daily variations of the <Emphasis Type="Italic">Period</Emphasis> gene in a reef fish <Emphasis Type="Italic">Siganus guttatus</Emphasis>

As the first step in understanding the molecular oscillation of the circa rhythms in the golden rabbitfish Siganus guttatus—a reef fish with a definite lunar-related rhythmicity—we cloned and sequenced a Period gene (rfPer). The rfPer gene contained an open reading frame that encodes a protein consisting of 1,452 amino acids; this protein is highly homologous to PER proteins of vertebrates including zebrafish. Phylogenetic analyses indicated that the rfPER protein is related to the zebrafish PER1 and PER4. The expression of rfPer mRNA in the whole brain, retina, and liver under light/dark (LD) conditions increased at 06:00 h and decreased at 18:00 h, suggesting that its robust circadian rhythm occurs in neural and peripheral tissues. When daily variation in the expression in rfPer mRNA in the whole brain and cultured pineal gland were examined under LD conditions, similar expression patterns of the gene were observed with an increase around dawn. Under constant light condition, the increased expression of rfPer mRNA in the whole brain disappeared around dawn. The present results demonstrate that rfPer is related to zPer4 and possibly zPer1. The present study is the first report on the Period gene from a marine fish.     

急性力竭运动对大鼠胃肠传输速率及回肠肌间神经丛氮能神经的影响

目的：研究力竭运动对大鼠胃肠动力的影响及其肠神经机制。方法：24只大鼠随机分成对照组和急性力竭运动组,建立力竭运动大鼠模型,测定胃肠传输速率,用酶组织化学方法和计算机图像分析技术对两组大鼠回肠肌间神经丛内氮能神经元的数目和一氧化氮合酶（NOS）的表达进行测定。结果：急性力竭运动组大鼠胃肠传输速率明显延迟,回肠肌间神经丛内氮能神经元的数目明显增多和NOS的表达显著增强（P〈0．05和P〈0．01）。结论：大鼠力竭运动后小肠肌问神经丛内氮能神经元的数目增多和NOS的表达增强可能是导致胃肠传输速率延迟的重要原因之一。     

Review of spino-occipital and spinal nerves in Tetraodontiformes,with special reference to pectoral and pelvic fin muscle innervation

The spino-occipital nerve (SO) and ventral rami of the spinal nerves (SV) in 10 tetraodontiform families and 5 outgroup taxa were examined, with special reference to pectoral and pelvic fin muscle innervation. Compared with the outgroup taxa, tetraodontiforms were characteristic in having SO3 + SV1 (SO3 in tetraodontids) that gave off several lateral subbranches to the pectoral fin base and SO participation in infracarinalis anterior innervation. SO and SV1 were connected with one another (6 patterns) before entering the pectoral fin muscles in most species, including the outgroup taxa, resulting in the participation of SV1 in the innervation of almost all of the pectoral fin muscles. SO3 + SV1 was present in all tetraodontiforms (except in 2 tetraodontids having only SO3) and the outgroup taxa, an upper dorsal branch uniformly extending dorsally into the pectoral fin base. The pectoral fin base also received a branch ventrally, but its identity differed (participation or nonparticipation of SV2). SV1 alone constituting the branch was a derived condition occurring in Aracanidae, Ostraciidae, Tetraodontidae, Diodontidae, and Molidae. No strong characters supporting a tetraodontiform sister group were recognized among the spino-occipital nerve and ventral rami of spinal nerves.     

家蚕非编码RNA在神经系统中的表达分析

【目的】非编码RNA(non-coding RNA,ncRNA)在家蚕Bombyx mori发育过程中具有重要调控作用。本研究旨在探索ncRNA参与家蚕神经系统发育的分子机理。【方法】采用实时荧光定量PCR技术对22个中等长度的ncRNA及3个ncRNA的邻近编码基因在家蚕幼虫神经系统中的表达水平进行检测。【结果】8个ncRNA(包括1个C/D box snoRNA,4个H/ACA box snoRNA和3个不能归类的ncRNA)在家蚕5龄幼虫神经组织和非神经组织中均有表达,且在胸腹神经中的表达量明显高于头部神经中的表达量。其中,snoRNA Bm-51,Bm-18和Bm-86在胸腹神经中的表达量分别是头部神经中的23,5和4.7倍。进一步研究发现,这3个内含子起源的ncRNA与其宿主基因在家蚕神经系统中的表达趋势一致,宿主基因在胸腹神经中的表达量也明显高于头部神经中的表达量。【结论】本研究筛选到的在家蚕不同神经部位存在差异表达的ncRNA,特别是在胸腹神经中高表达的ncRNA可能协同其邻近编码基因,参与家蚕神经发育或神经活动过程。该结果为研究ncRNA参与家蚕神经系统发育提供了分子依据,为从非编码RNA角度探索鳞翅目害虫防治提供了新的思路。     

Expression and Localization of Type II Diacylglycerol Kinase Isozymes δ and η in the Developing Mouse Brain

The functions of type II diacylglycerol kinase (DGK) δ and -η in the brain are still unclear. As a first step, we investigated the spatial and temporal expression of DGKδ and -η in the brains of mice. DGKδ2, but not DGKδ1, was highly expressed in layers II–VI of the cerebral cortex; CA–CA3 regions and dentate gyrus of hippocampus; mitral cell, glomerular and granule cell layers of the olfactory bulb; and the granule cell layer in the cerebellum in 1- to 32-week-old mice. DGKδ2 was expressed just after birth, and its expression levels dramatically increased from weeks 1 to 4. A substantial amount of DGKη (η1/η2) was detected in layers II–VI of the cerebral cortex, CA1 and CA2 regions and dentate gyrus of the hippocampus, mitral cell and glomerular layers of the olfactory bulb, and Purkinje cells in the cerebellum of 1- to 32-week-old mice. DGKη2 expression reached maximum levels at P5 and decreased by 4 weeks, whereas DGKη1 increased over the same time frame. These results indicate that the expression patterns of DGK isozymes differ from each other and also from other isozymes, and this suggests that DGKδ and -η play distinct and specific roles in the brain.     

Ectoderm removal prevents cutaneous nerve formation and perturbs sensory axon growth in the chick hindlimb

Target tissues are thought to provide important cues for growing axons, yet there is little direct evidence that they are essential for axonal pathfinding. Here we examined whether target ectoderm is necessary for the formation of cutaneous nerves, and for the normal growth and guidance of cutaneous axons as they first enter the limb plexus. To do this, we removed a patch of ectoderm from the chick hindlimb at various times during early axon outgrowth. We find there is a critical period when cutaneous nerve formation requires target ectoderm. When the ectoderm is absent during this time, axons progress into the limb more slowly and, although a few sensory axons occasionally diverge a short distance from the plexus, they do not form a discrete nerve that travels to the skin. A few days later, when the nerve pattern is mature, axons normally destined for the 'deprived' cutaneous nerve are not segregated appropriately within the plexus. Some cutaneous axons are instead misdirected along an inappropriate cutaneous nerve, while others have seemingly failed to reach their correct target, or a suitable alternative, and died. These results demonstrate that the target ectoderm is necessary for normal sensory axon growth and guidance in the hindlimb.