Larval cells become imaginal cells under the control of homothorax prior to metamorphosis in the Drosophila tracheal system

AbstractIn Drosophila melanogaster, one of the most derived species among holometabolous insects, undifferentiated imaginal cells that are set-aside during larval development are thought to proliferate and replace terminally differentiated larval cells to constitute adult structures. Essentially all tissues that undergo extensive proliferation and drastic morphological changes during metamorphosis are thought to derive from these imaginal cells and not from differentiated larval cells. The results of studies on metamorphosis of the Drosophila tracheal system suggested that large larval tracheal cells that are thought to be terminally differentiated may be eliminated via apoptosis and rapidly replaced by small imaginal cells that go on to form the adult tracheal system. However, the origin of the small imaginal tracheal cells has not been clear. Here, we show that large larval cells in tracheal metamere 2 (Tr2) divide and produce small imaginal cells prior to metamorphosis. In the absence of homothorax gene activity, larval cells in Tr2 become non-proliferative and small imaginal cells are not produced, indicating that homothorax is necessary for proliferation of Tr2 larval cells. These unexpected results suggest that larval cells can become imaginal cells and directly contribute to the adult tissue in the Drosophila tracheal system. During metamorphosis of less derived species of holometabolous insects, adult structures are known to be formed via cells constituting larval structures. Thus, the Drosophila tracheal system may utilize ancestral mode of metamorphosis

Licensing of complementary technologies and enforcement of intellectual property rights

In this paper, we examine the effect of enforcement of IPR on the equilibrium outcome and welfare through unilateral and cross licensing decisions between duopolistic firms with patents of two complementary technologies. We find the conditions on both the imitation cost of the infringer and probability of the accuser firm winning the lawsuit under that a unilateral licensing / a cross licensing may be contracted between them, and efficient social surplus of duopoly realizes

Parallel trade, pharmaceutical innovation, and intellectual property rights

This paper examines how the parallel trade influences the pharmaceutical innovation and welfare. We consider the case where one monopolist in the home potentially sells in the both domestic and foreign markets with different price elasticities of demand. As relevant in the pharmaceutical context, the price of a good sold in the foreign country is determined by the negotiation between the firm and the foreign government. When the parallel trade is allowed, this negotiated foreign price also becomes the domestic price and thus the firm cannot set different price in each market. This paper shows that the parallel trade may enhance pharmaceutical innovation, when the bargaining power of the foreign government is strong and the price elsticity of demand in the foreign market is small

Discovery of sediment indicating rapid lake-level fall in the late Pleistocene Gokarna Formation, Kathmandu Valley, Nepal: implication for terrace formation

Sediment indicating a rapid fall in lake level has been discovered in the late Pleistocene Gokarna Formation, Kathmandu Valley, Nepal. The indicator is observed along a widely traceable erosional surface in this formation, and is characterized by (1) gently inclined (ca. 10°) tabular cross-stratified sand beds of delta front origin consisting of coarser material and showing gradual decrease in elevation of its top to the progradation direction, (2) an antidune cross-laminated sand bed that interfingers with the delta front deposit, and (3) an approximately 5 m-deep erosional depression filled with convolute laminated sand beds and recognized at a location distal to that where deposits (1) and (2) were found. The early phase of rapid lake level fall caused minor erosion of the delta plain deposits by fluvial processes, introducing a higher rate of progradation of the delta front and resulting in the accumulation of deposit (1). The delta emerged as dry land due to further lowering of the lake level. The antidune cross-laminated sand bed shows evidence of having accumulated from a high-velocity stream that may have formed as the lake water drained from the delta front during the lowering of lake level. When the lake level fell below the level of the topographic high created by delta accumulation, incised valleys may have formed and part of them may have been filled with sediment at that time. The rapid fall in lake level is interpreted to have been the result of lake-wall failure, which would have occurred at the gorge outlet as the only discharge path for the basin. The initial rise of lake level causing accumulation of terrace sediments may have been due to the formation of a plug at this outlet, attributable to mass movement along the gorge

Extracellular vesicles synchronize cellular phenotypes of differentiating cells

細胞外小胞が細胞の分化を同調させる現象の発見. 京都大学プレスリリース. 2021-10-01.Cells act in unison when next to each other. 京都大学プレスリリース. 2021-10-01.During embryonic development, cells differentiate in a coordinated manner, aligning their fate decisions and differentiation stages with those of surrounding cells. However, little is known about the mechanisms that regulate this synchrony. Here we show that cells in close proximity synchronize their differentiation stages and cellular phenotypes with each other via extracellular vesicle (EV)-mediated cellular communication. We previously established a mouse embryonic stem cell (ESC) line harbouring an inducible constitutively active protein kinase A (CA-PKA) gene and found that the ESCs rapidly differentiated into mesoderm after PKA activation. In the present study, we performed a co-culture of Control-ESCs and PKA-ESCs, finding that both ESC types rapidly differentiated in synchrony even when PKA was activated only in PKA-ESCs, a phenomenon we named ‘Phenotypic Synchrony of Cells (PSyC)’. We further demonstrated PSyC was mediated by EVs containing miR-132. PKA-ESC-derived EVs and miR-132-containing artificial nano-vesicles similarly enhanced mesoderm and cardiomyocyte differentiation in ESCs and ex vivo embryos, respectively. PSyC is a new form of cell-cell communication mediated by the EV regulation of neighbouring cells and could be broadly involved in tissue development and homeostasis

Bipolar localization of putative photoreceptor protein for phototaxis in thermophilic cyanobacterium Synechococcus elongatus

Funding Information: This work was supported in part by Grants-in-Aid for scientific research from the Ministry of Education, Science, Sports and Culture, Japan (no. 11640653 to K.M.).We identified an open reading frame from a database of the entire genome of Synechococcus elongatus, the product of which was very similar to pixJ1, which was proposed as photoreceptor gene for phototaxis in Synechocystis sp. PCC6803 [Yoshihara et al. (2000) Plant Cell Physiol. 41: 1299]. The mRNA of S. elongatus pixJ (SepixJ) was expressed in vivo as a part of the product of an operon. SePixJ was detected exclusively in the membrane fraction after cell fractionation. Immunogold labeling of SePixJ in ultra-thin sections indicated that it existed only in both ends of the rod-shaped cell; probably bound with the cytoplasmic membrane.publishersversionPeer reviewe

Concentric zones, cell migration and neuronal circuits in the Drosophila visual center

金沢大学フロンティアサイエンス機構The Drosophila optic lobe comprises a wide variety of neurons, which form laminar neuropiles with columnar units and topographic projections from the retina. The Drosophila optic lobe shares many structural characteristics with mammalian visual systems. However, little is known about the developmental mechanisms that produce neuronal diversity and organize the circuits in the primary region of the optic lobe, the medulla. Here, we describe the key features of the developing medulla and report novel phenomena that could accelerate our understanding of the Drosophila visual system. The identities of medulla neurons are pre-determined in the larval medulla primordium, which is subdivided into concentric zones characterized by the expression of four transcription factors: Drifter, Runt, Homothorax and Brain-specific homeobox (Bsh). The expression pattern of these factors correlates with the order of neuron production. Once the concentric zones are specified, the distribution of medulla neurons changes rapidly. Each type of medulla neuron exhibits an extensive but defined pattern of migration during pupal development. The results of clonal analysis suggest homothorax is required to specify the neuronal type by regulating various targets including Bsh and cell-adhesion molecules such as N-cadherin, while drifter regulates a subset of morphological features of Drifter-positive neurons. Thus, genes that show the concentric zones may form a genetic hierarchy to establish neuronal circuits in the medulla.出版社許諾要件により、2012年3月より全文公開

The "Yin-Yang Grid": An Overset Grid in Spherical Geometry

A new kind of overset grid, named Yin-Yang grid, for spherical geometry is proposed. The Yin-Yang grid is composed of two identical component grids that are combined in a complemental way to cover a spherical surface with partial overlap on their boundaries. Each component grid is a low latitude part of the latitude-longitude grid. Therefore the grid spacing is quasi-uniform and the metric tensors are simple and analytically known. One can directly apply mathematical and numerical resources that have been written in the spherical polar coordinates or latitude-longitude grid. The complemental combination of the two identical component grids enables us to make efficient and concise programs. Simulation codes for geodynamo and mantle convection simulations using finite difference scheme based on the Yin-Yang grid are developed and tested. The Yin-Yang grid is suitable for massively parallel computers.Comment: 9 figure