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論文
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Kiya, Taketoshi ; Ugajin, Atsushi ; Kunieda, Takekazu ; Kubo, Takeo
概要:
The honeybee is a social insect that exhibits various social behaviors. To elucidate the neural basis of honeybee behavi
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or, we detected neural activity in freely-moving honeybee workers using an immediate early gene (IEG) that is expressed in a neural activity-dependent manner. In European honeybees (Apis mellifera), we identified a novel nuclear non-coding RNA, termed kakusei, as the first insect IEG, and revealed the neural activity pattern in foragers. In addition, we isolated a homologue of kakusei, termed Acks, from the Japanese honeybee (Apis cerana), and detected active neurons in workers fighting with the giant hornet. © 2012 by the authors; licensee MDPI, Basel, Switzerland.
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| 2.
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論文
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Roy, Anuradha ; Shimizu, Sakiko ; Kiya, Taketoshi ; Mita, Kazuei ; Iwami, Masafumi
概要:
The insect brain secretes prothoracicotropic hormone (PTTH), which stimulates the prothoracic gland to synthesize ecdyso
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ne. The active metabolite of ecdysone, 20-hydroxyecdysone (20E), works through ecdysone receptor (EcR) and ultraspiracle (USP) to initiate molting and metamorphosis by regulating downstream genes. Previously, we found that EcR was expressed in the PTTH-producing neurosecretory cells (PTPCs) in larval brain of the silkworm Bombyx mori, suggesting that PTPCs function as the master cells of development under the regulation of 20E. To gain a better understanding of the molecular mechanism of the 20E control of PTPCs, we performed a comprehensive screening of genes induced by 20E using DNA microarray with brains of day-2 fifth instar silkworm larvae. Forty-one genes showed greater than twofold changes caused by artificial application of 20E. A subsequent semiquantitative screening identified ten genes upregulated by 20E, four of which were novel or not previously identified as 20E-response genes. Developmental profiling determined that two genes, UP4 and UP5, were correlated with the endogenous ecdysteroid titer. Whole-mount in situ hybridization showed exclusive expression of these two genes in two pairs of cells in the larval brain in response to 20E-induction, suggesting that the cells are PTPCs. BLAST searches revealed that UP4 and UP5 are Bombyx homologs of vrille and tarsal-less, respectively. The present study identifies 20E-induced genes that may be involved in the ecdysone signal hierarchies underlying pupal-adult development and/or the 20E regulation of PTPCs. © 2012 Zoological Society of Japan.<br />発行後1年より全文公開
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| 3.
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Suzuki, Takumi ; Sakurai, Sho ; Iwami, Masafumi
概要:
Holometabolous insects do not excrete but store metabolic wastes during the pupal period. The waste is called meconium a
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nd is purged after adult emergence. Although the contents of meconium are well-studied, the developmental and physiological regulation of meconium accumulation is poorly understood. In Bombyx mori, meconium is accumulated in the rectal sac; thereby, the rectal sac distends at the late pupal stage. Here, we show that rectal sac distention occurs between 4 and 5 days after pupation. The distention is halted by brain-removal just after larval-pupal ecdysis but not by brain-removal 1 day after pupation. In the pupae, brain-removal just after ecdysis kept the hemolymph ecdysteroid titer low during early and mid-pupal stages. An injection of 20-hydroxyecdysone (20E) evoked the distention that was halted by brain-removal in a dose-dependent manner. Therefore, brain-removal caused the lack of ecdysteroid, and rectal sac distention did not appear in the brain-removed pupae because of the lack of ecdysteroid. We conclude that rectal sac distention is one of the developmental events regulated by 20E during the pupal period in B. mori. © 2008 Elsevier Ltd. All rights reserved.
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| 4.
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論文
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Monwar, Hossain ; Shimizu, Sakiko ; Matsuki, Masahiko ; Imamura, Masanori ; Sakurai, Sho ; Iwami, Masafumi
概要:
金沢大学理工研究域自然システム学系<br />The insect brain is the center of developmental control, from which ecdysone governs brain morpho
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genesis and regulates gene expression cascades associated with molting and metamorphosis. In order to identify the 20-hydroxyecdysone (20E)-inducible genes responsible for molting and metamorphosis, we constructed a 20E-induced subtraction complementary DNA library from the fifth instar larval brain of the silkworm Bombyx mori. We isolated 10 genes, designated as bombeil-1 to bombeil-10, three of which did not show any sequence similarity to previously identified Bombyx genes. Whole-mount in situ hybridization revealed that all of these bombeil messenger RNAs were exclusively located in two pairs of lateral neurosecretory cells in the larval brain, known as prothoracicotropic hormone (PTTH)-producing cells. RNA-interference knockdown targeting bombeil-2 resulted in larval-pupal molt defects, and adult wing and leg malformations. These results, together with the cell-specific co-localization of bombeil transcripts with PTTH, suggest that bombeil genes play important roles during larval-pupal-adult development. © 2008 Elsevier Ltd. All rights reserved
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