Large Ventral Lateral Neurons Determine the Phase of Evening Activity Peak across Photoperiods in Drosophila melanogaster

The dual-oscillator model, originally proposed as a mechanism for how vertebrates adapt to seasonal changes, has been invoked to explain circadian entrainment in Drosophila melanogaster. Distinct subsets of neurons have been designated as "morning" and "evening" oscillators that function as regulators of rhythmic activity/rest behavior. Some studies have led to a model in which a subset of 8 "morning" cells (4 bilaterally located small ventral lateral neurons) and another subset of approximately 130 "evening" cells exert different levels of dominance within the circadian circuit in different seasons. However, many studies propose a more integrative neuronal network, with the whole network orchestrating activity/rest rhythms in different seasons, as opposed to hierarchical dominance among neurons. Within the circadian network, our understanding of the role of the large ventral lateral neurons (l-LN(v)) has thus far been limited to conveying light information to the clocks and as light-activated neurons mediating arousal. In support of the framework of a more distributed model, we report an important circadian clock-related role for the l-LN(v) in electrical activity-dependent phasing of the evening peak across a range of photoperiods. Further, we propose a model in which l-LN(v) enable adaptation to seasonal changes by regulating the phase of the evening peak. Additionally, we demonstrate a hitherto unknown role for the small ventral lateral neurons (s-LN(v)) in the arousal circuit, thus showing that neuronal function is flexible such that certain neurons can play more than one role in distinct circuits.     

Architectural and Functional Diversity of Polycomb Group Response Elements in Drosophila

Polycomb group response elements (PREs) play an essential role in gene regulation by the Polycomb group (PcG) repressor proteins in Drosophila. PREs are required for the recruitment and maintenance of repression by the PcG proteins. PREs are made up of binding sites for multiple DNA-binding proteins, but it is still unclear what combination(s) of binding sites is required for PRE activity. Here we compare the binding sites and activities of two closely linked yet separable PREs of the Drosophila engrailed (en) gene, PRE1 and PRE2. Both PRE1 and PRE2 contain binding sites for multiple PRE–DNA-binding proteins, but the number, arrangement, and spacing of the sites differs between the two PREs. These differences have functional consequences. Both PRE1 and PRE2 mediate pairing-sensitive silencing of mini-white, a functional assay for PcG repression; however, PRE1 requires two binding sites for Pleiohomeotic (Pho), whereas PRE2 requires only one Pho-binding site for this activity. Furthermore, for full pairing-sensitive silencing activity, PRE1 requires an AT-rich region not found in PRE2. These two PREs behave differently in a PRE embryonic and larval reporter construct inserted at an identical location in the genome. Our data illustrate the diversity of architecture and function of PREs.     

果糖暴食对大鼠下丘脑外侧核与伏隔核Orexin 神经元的影响

目的:探讨给予间歇性摄食大鼠模型(Intermittent Access Model[IAM])果糖是否可使IAM大鼠对果糖产生暴食行为,以及下丘脑外侧核(LHA)和伏隔核Orexin(ORX)神经元对果糖暴食行为的影响。方法:给予IAM大鼠4%、8%或12%的果糖溶液及生理盐水,观察和记录大鼠果糖摄入量及能否产生果糖暴食行为;测定果糖凝集反应大鼠伏隔核壳(NAc shell)、伏隔核核(NAc core)和背侧纹状体(Dorsal striatum)多巴胺受体(D1R、D2R)数目(Bmax)和受体亲和力(Kd);分别监测长期和短期IAM大鼠室旁核(PVN)、杏仁核(CeA)、伏隔核(NAc)等相关核团的C-Fos神经元活性(Fos-IR);给予长期IAM大鼠OX1R拮抗剂SB334867,记录大鼠摄食量。结果:长期IAM大鼠表现出果糖暴食行为,但相应的多巴胺受体数目并未改变。与对照组相比,果糖暴食组大鼠伏隔核c-Fos蛋白减少,神经元活性降低。短期IAM大鼠可产生果糖暴食但Fos-IR未改变。给予长期IAM大鼠OX1R拮抗剂SB-334867(30 mg/kg),大鼠果糖暴食量和食物摄入量均减少。结论:长短期IAM大鼠均可产生果糖暴食行为;仅长期果糖暴食可致Orexin释放增加,减少伏隔核Orexin神经元激活,增强外侧核Orexin神经元激活。     

Simultaneous Recording of Calcium Signals from Identified Neurons and Feeding Behavior of Drosophila melanogaster

To study neuronal networks in terms of their function in behavior, we must analyze how neurons operate when each behavioral pattern is generated. Thus, simultaneous recordings of neuronal activity and behavior are essential to correlate brain activity to behavior. For such behavioral analyses, the fruit fly, Drosophila melanogaster, allows us to incorporate genetically encoded calcium indicators such as GCaMP¹, to monitor neuronal activity, and to use sophisticated genetic manipulations for optogenetic or thermogenetic techniques to specifically activate identified neurons^2-5. Use of a thermogenetic technique has led us to find critical neurons for feeding behavior (Flood et al., under revision). As a main part of feeding behavior, a Drosophila adult extends its proboscis for feeding⁶ (proboscis extension response; PER), responding to a sweet stimulus from sensory cells on its proboscis or tarsi. Combining the protocol for PER⁷ with a calcium imaging technique⁸ using GCaMP3.0^{1, 9}, I have established an experimental system, where we can monitor activity of neurons in the feeding center – the suboesophageal ganglion (SOG), simultaneously with behavioral observation of the proboscis. I have designed an apparatus ("Fly brain Live Imaging and Electrophysiology Stage": "FLIES") to accommodate a Drosophila adult, allowing its proboscis to freely move while its brain is exposed to the bath for Ca²⁺ imaging through a water immersion lens. The FLIES is also appropriate for many types of live experiments on fly brains such as electrophysiological recording or time lapse imaging of synaptic morphology. Because the results from live imaging can be directly correlated with the simultaneous PER behavior, this methodology can provide an excellent experimental system to study information processing of neuronal networks, and how this cellular activity is coupled to plastic processes and memory.     

Persistence and Periodic Solutions of a System of Two Competing Species with Functional Response

1IntroductionOneofthemOStnit~tingquestionsinrnathernaticalbiologyconcernsthesurvivalofspeCiesinecologiCalmodels.Perslstenceisanimportantconceptindabingwiththeseproblems.Therearemanyliteraturesaboutthedy'ndricsofdiffuSivecompetingspeCies,butthefunctionalresPOnseofthisfOITnhasnotbeenst'Udiedtoomuchyet.Inthispaper,weconsiderthepersistenceproblemforanonautonomoussystemoftwOcompetingspecieswithfunctionalreSPOnse,themodelweconsiderinthispaperishereallri(t),ail(t),D,(t)anda(t)areassumedtobecon…     

Notch Is Required in Adult Drosophila Sensory Neurons for Morphological and Functional Plasticity of the Olfactory Circuit

Olfactory receptor neurons (ORNs) convey odor information to the central brain, but like other sensory neurons were thought to play a passive role in memory formation and storage. Here we show that Notch, part of an evolutionarily conserved intercellular signaling pathway, is required in adult Drosophila ORNs for the structural and functional plasticity of olfactory glomeruli that is induced by chronic odor exposure. Specifically, we show that Notch activity in ORNs is necessary for the odor specific increase in the volume of glomeruli that occurs as a consequence of prolonged odor exposure. Calcium imaging experiments indicate that Notch in ORNs is also required for the chronic odor induced changes in the physiology of ORNs and the ensuing changes in the physiological response of their second order projection neurons (PNs). We further show that Notch in ORNs acts by both canonical cleavage-dependent and non-canonical cleavage-independent pathways. The Notch ligand Delta (Dl) in PNs switches the balance between the pathways. These data define a circuit whereby, in conjunction with odor, N activity in the periphery regulates the activity of neurons in the central brain and Dl in the central brain regulates N activity in the periphery. Our work highlights the importance of experience dependent plasticity at the first olfactory synapse.     

Localization of Motor Neurons and Central Pattern Generators for Motor Patterns Underlying Feeding Behavior in Drosophila Larvae

Motor systems can be functionally organized into effector organs (muscles and glands), the motor neurons, central pattern generators (CPG) and higher control centers of the brain. Using genetic and electrophysiological methods, we have begun to deconstruct the motor system driving Drosophila larval feeding behavior into its component parts. In this paper, we identify distinct clusters of motor neurons that execute head tilting, mouth hook movements, and pharyngeal pumping during larval feeding. This basic anatomical scaffold enabled the use of calcium-imaging to monitor the neural activity of motor neurons within the central nervous system (CNS) that drive food intake. Simultaneous nerve- and muscle-recordings demonstrate that the motor neurons innervate the cibarial dilator musculature (CDM) ipsi- and contra-laterally. By classical lesion experiments we localize a set of CPGs generating the neuronal pattern underlying feeding movements to the subesophageal zone (SEZ). Lesioning of higher brain centers decelerated all feeding-related motor patterns, whereas lesioning of ventral nerve cord (VNC) only affected the motor rhythm underlying pharyngeal pumping. These findings provide a basis for progressing upstream of the motor neurons to identify higher regulatory components of the feeding motor system.     

腹侧被盖区多巴胺能神经元对奖赏/厌恶刺激反应的异质性

中脑多巴胺奖赏系统,由腹侧被盖区及其投射靶区组成,参与药物依赖、精神疾病等病理过程的调控.奖赏和厌恶刺激是衡量上述病理过程的重要手段.一直以来,不同研究在该系统对奖赏和厌恶刺激的反应上存在分歧,越来越多的研究倾向于认为该系统,特别是腹侧被盖区多巴胺能神经元存在较大的异质性.本文从腹侧被盖区多巴胺能神经元判定标准、解剖定位和投射特异性等角度对其在奖赏和厌恶刺激中的功能异质性进行综述,并对未来研究方向进行展望.     

Opposing Regulation of Cocaine Seeking by Glutamate and GABA Neurons in the Ventral Pallidum

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Morphological Identification and Development of Neurite in Drosophila Ventral Nerve Cord Neuropil

In Drosophila, ventral nerve cord (VNC) occupies most of the larval central nervous system (CNS). However, there is little literature elaborating upon the specific types and growth of neurites as defined by their structural appearance in Drosophila larval VNC neuropil. Here we report the ultrastructural development of different types VNC neurites in ten selected time points in embryonic and larval stages utilizing transmission electron microscopy. There are four types of axonal neurites as classified by the type of vesicular content: clear vesicle (CV) neurites have clear vesicles and some T-bar structures; Dense-core vesicle (DV) neurites have dense-core vesicles and without T-bar structures; Mixed vesicle (MV) neurites have mixed vesicles and some T-bar structures; Large vesicle (LV) neurites are dominated by large, translucent spherical vesicles but rarely display T-bar structures. We found dramatic remodeling in CV neurites which can be divided into five developmental phases. The neurite is vacuolated in primary (P) phase, they have mitochondria, microtubules or big dark vesicles in the second (S) phase, and they contain immature synaptic features in the third (T) phase. The subsequent bifurcate (B) phase appears to undergo major remodeling with the appearance of the bifurcation or dendritic growth. In the final mature (M) phase, high density of commensurate synaptic vesicles are distributed around T-bar structures. There are four kinds of morphological elaboration of the CV_I neurite sub-types. First, new neurite produces at the end of axon. Second, new neurite bubbles along the axon. Third, the preexisting neurite buds and develops into several neurites. The last, the bundled axons form irregularly shape neurites. Most CV_I neurites in M phase have about 1.5–3 µm diameter, they could be suitable to analyze their morphology and subcellular localization of specific proteins by light microscopy, and they could serve as a potential model in CNS in vivo development.     

Response of NADPH-Diaphorase-Exhibiting Neurons in the Medullar Reticular Formation to High Spinal Cord Injury

1. The effect of hemisection of the cervical spinal cord on NADPH-diaphorase staining in the reticular nuclei of the rabbit medulla was investigated using histochemical technique.2. A quantitative assessment of somal and neuropil NADPH-diaphorase staining was made by an image analyzer in a selected area of each reticular nucleus of the rabbit medulla.3. On the 7th postsurgery day, the highest up-regulation of somatic NADPH-diapho- rase staining was observed in regions regulating cardiorespiratory processes; however, the highest increase of neuropil NADPH-diaphorase staining was found in the reticular nuclei modulating the tonus of postural muscles.4. The degeneration of non-NADPH-diaphorase-stained neurons was detected throughout the reticular formation of the medulla, but the extent of neuronal death did not correlate with the up-regulation of the NADPH-diaphorase staining in the reticular nuclei of the medulla.5. The findings provide evidence that NADPH-diaphorase-exhibiting neurons are refractory to the hemisection of the cervical spinal cord and that the neuronal up-regulation of NADPH-diaphorase at the medullar level is probably not a causative factor leading to the death of the reticulospinal neurons.     

Cannibalistic Behavior and Functional Response in Chrysomya albiceps (Diptera: Calliphoridae)

Chrysomya albiceps is a facultative predator and cannibal species during the larval stage. Very little is known about cannibalism and prey size preference, especially in blowflies. The purpose of this investigation was to determine the influence of prey size and larval density on cannibalism by third-instar larvae of C. albiceps under laboratory conditions. Our results indicate that no cannibalism occurs by third-instar larvae on first- and second-instar larvae, but third-instar larvae do eat second-instar larvae. The functional response on second-instar larvae is consistent with Holling type II. The consequences of consuming second-, compared to first- or third-, instar larvae as well as the implications of cannibalism for the population dynamics of C. albiceps are discussed.     

Response of Fish Assemblage Structure and Function Following Restoration of Two Small Bahamian Tidal Creeks

Disruption of hydrologic connectivity via road crossings is extremely common in Bahamian tidal creeks, resulting in increased sedimentation and decreased habitat quality and quantity for biota. We restored hydrologic connectivity (i.e., tidal flow) in two small Bahamian mangrove tidal creeks in May 2004 and 2005. We observed the characteristics of fish assemblage structure (species richness) and function (secondary production and transient species utilization of restored areas) before and after restoration, and compared these data with fragmented and unfragmented reference creeks. Restoration significantly increased species richness and secondary production of resident fish species in one of the two restored creeks. Increased utilization of the previously blocked wetlands by transient fishes was observed in both creeks. We suggest success could be attributed to the presence of adjacent nearshore recruitment sources, a more complex local seascape (i.e., high habitat heterogeneity in the creek and local nearshore), and the creation of deep upstream refugia pools. This is one of the first studies to use both structural and functional characteristics to monitor the success of restoration in mangrove ecosystems. Studies combining both structural and functional metrics in restoration monitoring are imperative in linking restoration ecology theory with practical ecological restoration efforts.     

Function of Ventral and Lateral Processes in Larvae of Chironomus (Diptera, Chironomidae)

Oxygen consumption by larvae of five Chironomus species from the Plumosus group belonging to different larval forms was studied. Larvae of C. agilis ( f. l. reductus) were unable to utilize oxygen at its concentrations lower than 1 mg/l. Larvae of C. plumosus ( f. l. plumosus) used oxygen from water at concentrations higher than 0.7 mg/l; pupas of this species and larvae of C. borokensis ( f. l. plumosus) utilized oxygen at concentrations lower than 0.4 mg/l. C. entis and C. muratensis (both-- f. l. semireductus) utilized oxygen from water at its concentrations up to 0.05 mg/l. The lack of correlation between the rate and ability of larvae to use oxygen at low concentrations and the degree of development of processes allows suggesting that these structures are not additional respiratory organs, as is commonly accepted. At the same time, ability of species to inhabit under conditions of oxygen deficiency correlates directly with the size of the processes. Therefore, ventral and lateral processes are suggested to perform a function of excretion of anaerobic metabolism metabolites.     

Reward Anticipation in Ventral Striatum and Individual Sensitivity to Reward: A Pilot Study of a Child-Friendly fMRI Task

Reward processing has been implicated in developmental disorders. However, the classic task to probe reward anticipation, the monetary incentive delay task, has an abstract coding of reward and no storyline and may therefore be less appropriate for use with developmental populations. We modified the task to create a version appropriate for use with children. We investigated whether this child-friendly version could elicit ventral striatal activation during reward anticipation in typically developing children and young adolescents (aged 9.5–14.5). In addition, we tested whether our performance-based measure of reward sensitivity was associated with anticipatory activity in ventral striatum. Reward anticipation was related to activity in bilateral ventral striatum. Moreover, we found an association between individual reward sensitivity and activity in ventral striatum. We conclude that this task assesses ventral striatal activity in a child-friendly paradigm. The combination with a performance-based measure of reward sensitivity potentially makes the task a powerful tool for developmental imaging studies of reward processing.