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Molecular mechanism of the regulation of insect metamorphosis by juvenile hormone eluciated

posted Dec 5, 2015, 6:04 AM by Yukio Ishikawa   [ updated Dec 5, 2015, 3:38 PM ]

Dr. T. Kayukawa Ms. Y. Ito, and Dr. T. Shinoda of the National Institute of Agrobiological Sciences (NIAS), in collaboration with members of our laboratory (K. Nagamine and Y. Ishikawa) and Dr. Y. Nishita of Hokkaido University, have clarified the molecular mechanism of the regulation of insect metamorphosis by juvenile hormone (JH).   It was found that JH directly suppresses the expression of Krüppel homolog 1 (Kr-h1)a gene that suppresses the expression of Broad-complex (BR-C), a master gene that controls the expression of genes specific to the pupal stage. 
  1. Takumi Kayukawa, Keisuke Nagamine, Yuka Ito, Yoshinori Nishita, Yukio Ishikawa, and Tetsuro Shinoda (2015). Krüppel homolog 1 inhibits insect metamorphosis via direct transcriptional repression of Broad-complex, a pupal specifier gene. The Journal of Biological Chemistry.

For further information, please see

posted Nov 9, 2012, 11:34 PM by Yukio Ishikawa


An article selected by Faculty of 1000

posted Feb 26, 2012, 4:38 PM by Yukio Ishikawa   [ updated Mar 12, 2012, 6:31 PM ]

One of the articles published from our lab, "A male-killing Wolbachia carries a feminizing factor and is associated with degradation of the sex-determining system of its host (Biol Lett 2012 Jan 4)", has been selected and evaluated by Nina Wedell, a Member of the Faculty of 1000 (F1000), which places this work the top 2% of published articles in biology and medicine. 

Comments:
This intriguing study indicates that male-killing Wolbachia carries a genetic factor that feminizes genetic Ostrinia scapulalis male moths, thereby causing a mismatch between the genetic and phenotypic sex resulting in death. The interaction between genetic and phenotypic sex was determined in normal, infected, and infected-and-cured individuals using a sex-specifically spliced homologue of doublesex (Osdsx) and sex chromatin bodies unique to genetic female moths. This revealed that female spliced Osdsx was expressed in infected male larvae destined to die, whereas the male Osdsx type was expressed in females causing them to die. These results indicate that the male-killing Wolbachia carries a feminizing factor that interferes with the sex-determination system of the host, possibly by affecting the sex-specific splicing of Osdsx. The results also indicate a degradation of the sex-determination system as genetic females cured of infection become masculinized and express the male Osdsx type resulting in death. Taken together, the observed discourse between genetic and phenotypic sexes appears to be responsible for embryonic death and that feminization may in fact underlie male killing in this species. This tentatively hints at common mechanisms potentially underlying the diversity of reproductive manipulations of this endosymbiont.

Prof. Emeritus S. Tatsuki will be honored a Prize

posted Jan 26, 2012, 6:01 AM by Yukio Ishikawa   [ updated Jan 27, 2012, 10:26 PM ]

The former professor of our laboratory, Professor Emeritus Sadahiro Tatsuki, will be honored the "Japan Prize of Agricultural Science" this April.  This award is most prestigious in the field of agricultural science.  His dedication to basic and applied researches on sex pheromones of agricultural pests has been highly appreciated.    

New paper published in Biology Letters

posted Jan 15, 2012, 12:55 AM by Yukio Ishikawa   [ updated Mar 12, 2012, 6:30 PM ]

A new paper "A male-killing Wolbachia carries a feminizing factor and is associated with degradation of the sex-determining system of its host" has been published in Biology Letters (http://dx.doi.org/10.1098/rsbl.2011.1114).  
    In the moth Ostrinia scapulalis infected with an endosymbiotic bacterium, Wolbachia (wSca), male progenies are inviable (thus called male killing) while female progenies in turn become inviable when cured of infection.  We found that the infected male progenies destined to die were feminized while the cured female progenies destined to die were masculinized.  It was concluded that wSca, a male killer, has a genetic factor that feminizes the male host, and that the host lost its ability to determine its own sex in association with the takeover of this function by wSca.   

Vibratory communication in the humus soil

posted Oct 17, 2011, 9:54 PM by Yukio Ishikawa   [ updated Mar 12, 2012, 6:26 PM ]

Wataru Kojima, a graduate student in our laboratory, and Dr. Takuma Takanashi (OB) of the Forest and Forest Products Research Institute revealed that pupae and larvae of a group-living Japanese rhinoceros beetle, Trypoxylus dichotoma, communicate using vibrations in their habitat, humus soil.  It was suggested that pupae generate vibrations to deter conspecific larvae, thereby preventing damage to the pupal cells, in which they molt and stretch to become adults.  Please see 'Behavioral Ecology and Sociobiology'  http://dx.doi.org/10.1007/s00265-011-1264-5 for more information.

Paper published in PNAS

posted Oct 17, 2011, 9:36 PM by Yukio Ishikawa   [ updated Oct 17, 2011, 9:38 PM ]

A paper authored by Takeshi Fujii, Yukio Ishikawa, and several collaborators has been published in the online version of Proceedings of the National Academy of the USA on October 18, 2011. http://www.pnas.org/cgi/doi/10.1073/pnas.1107282108

Normal males of silkmoth respond to bombykol, which is secreted by females as the sex pheromone.  However, the male moths of spli mutants showed only weak response to bombykol, but strongly responded to bombykal, an oxidized form of bombykol.  We found that a transcription factor, Bmacj6, was completely deleted in the spli mutant.  Deletion of Bmacj6 was found to cause decrease in the expression of bombykol receptor and induce mistargeting of the neurons in the brain.      

Dr. Takanashi (our OB) got "Japan Prize in Agricultural Sciences, Achievement Award for Young Scientists"

posted Oct 4, 2011, 1:48 AM by Yukio Ishikawa   [ updated Oct 4, 2011, 1:57 AM ]

Dr. Takanashi, who completed doctoral course of the University of Tokyo in 2001 and now working for Forestry and Forestry Products Research Institute, will receive the 2011 "Japan Prize in Agricultural Sciences, Achievement Award for Young Scientists" from the The Foundation of Agricultural Sciences of Japan.  The award is given for his "Studies on the functions of sound/vibration generated by pest insects and development of pest management system utilizing the sound/vibration". 

Dr. Ohno (our OB) got an encouragement award

posted Oct 2, 2011, 2:09 AM by Yukio Ishikawa   [ updated Oct 4, 2011, 1:55 AM ]

Dr. Ohno, who completed doctoral course of the University of Tokyo in 2003 and now working for Okinawa Agricultural Research Station, will receive the 2012 encouragement award from the Japanese Society of Applied Entomology and Zoology (AEZ).  The award is given for his "Fundamental researches on eradication and/or integrated management of agricultural pests in Nansei Islands (Southwestern Islands off Kyushu and in the Okinawan archipelago)". 

Award wining presentation

posted Sep 2, 2011, 3:07 AM by Takashi Matsuo

Our lab member Wataru Kojima (PhD student, JSPS fellow) attended the 13th International Meeting on Invertebrate Sound and Vibration (University of Missouri, Columbia, June 4-7), and presented a poster entitled "Vibratory communication in the soil: pupal signals deter larval intrusion in a group-living beetle Trypoxylus dichotoma (Wataru Kojima, Yukio Ishikawa, & Takuma Takanashi)", wining a Student Poster Award. Congratulations!

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