Das Abhijit, Chiang Albert, Davla Sejal, Priya Rashi, Reichert Heinrich, VijayRaghavan K, Rodrigues Veronica
Department of Biological Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400005, India.
National Centre for Biological Sciences, TIFR, UAS-GKVK Campus, Bangalore-560065, India.
Neural Syst Circuits. 2011 Jan 26;1(1):4. doi: 10.1186/2042-1001-1-4.
The antennal lobe of Drosophila is perhaps one of the best understood neural circuits, because of its well-described anatomical and functional organization and ease of genetic manipulation. Olfactory lobe interneurons - key elements of information processing in this network - are thought to be generated by three identified central brain neuroblasts, all of which generate projection neurons. One of these neuroblasts, located lateral to the antennal lobe, also gives rise to a population of local interneurons, which can either be inhibitory (GABAergic) or excitatory (cholinergic). Recent studies of local interneuron number and diversity suggest that additional populations of this class of neurons exist in the antennal lobe. This implies that other, as yet unidentified, neuroblast lineages may contribute a substantial number of local interneurons to the olfactory circuitry of the antennal lobe.
We identified and characterized a novel glutamatergic local interneuron lineage in the Drosophila antennal lobe. We used MARCM (mosaic analysis with a repressible cell marker) and dual-MARCM clonal analysis techniques to identify this novel lineage unambiguously, and to characterize interneurons contained in the lineage in terms of structure, neurotransmitter identity, and development. We demonstrated the glutamatergic nature of these interneurons by immunohistochemistry and use of an enhancer-trap strain, which reports the expression of the Drosophila vesicular glutamate transporter (DVGLUT). We also analyzed the neuroanatomical features of these local interneurons at single-cell resolution, and documented the marked diversity in their antennal lobe glomerular innervation patterns. Finally, we tracked the development of these dLim-1 and Cut positive interneurons during larval and pupal stages.
We have identified a novel neuroblast lineage that generates neurons in the antennal lobe of Drosophila. This lineage is remarkably homogeneous in three respects. All of the progeny are local interneurons, which are uniform in their glutamatergic neurotransmitter identity, and form oligoglomerular or multiglomerular innervations within the antennal lobe. The identification of this novel lineage and the elucidation of the innervation patterns of its local interneurons (at single cell resolution) provides a comprehensive cellular framework for emerging studies on the formation and function of potentially excitatory local interactions in the circuitry of the Drosophila antennal lobe.
果蝇的触角叶可能是理解最为透彻的神经回路之一，这得益于其详尽的解剖学和功能组织，以及易于进行基因操作。嗅觉叶中间神经元——该网络中信息处理的关键要素——被认为由三个已明确的中枢脑成神经细胞产生，这三个成神经细胞都会产生投射神经元。其中一个位于触角叶外侧的成神经细胞，还会产生一群局部中间神经元，这些神经元可以是抑制性的（γ-氨基丁酸能）或兴奋性的（胆碱能）。最近对局部中间神经元数量和多样性的研究表明，触角叶中还存在这类神经元的其他群体。这意味着其他尚未确定的成神经细胞谱系可能为触角叶的嗅觉回路贡献大量局部中间神经元。
我们在果蝇触角叶中鉴定并表征了一个新的谷氨酸能局部中间神经元谱系。我们使用MARCM（可抑制细胞标记的镶嵌分析）和双MARCM克隆分析技术明确鉴定了这个新谱系，并从结构、神经递质特性和发育方面对该谱系中的中间神经元进行了表征。我们通过免疫组织化学和使用一个报告果蝇囊泡谷氨酸转运体（DVGLUT）表达的增强子捕获品系，证明了这些中间神经元的谷氨酸能特性。我们还以单细胞分辨率分析了这些局部中间神经元的神经解剖学特征，并记录了它们在触角叶肾小球神经支配模式上的显著多样性。最后，我们追踪了这些dLim-1和Cut阳性中间神经元在幼虫和蛹期的发育过程。
我们鉴定了一个在果蝇触角叶中产生神经元的新成神经细胞谱系。这个谱系在三个方面非常一致。所有后代都是局部中间神经元，它们在谷氨酸能神经递质特性上是一致的，并在触角叶内形成少肾小球或多肾小球神经支配。这个新谱系的鉴定以及对其局部中间神经元神经支配模式（单细胞分辨率）的阐明，为果蝇触角叶回路中潜在兴奋性局部相互作用的形成和功能的新兴研究提供了一个全面的细胞框架。
