Integrated Biology Laboratories
Germline Biology Group



Keywords:
Non-coding RNA, small RNA, Germline cell, Gametogenesis, Drosophila melanogaster
Unveiling the secret of germline cells
Although individual animals do die, the species is maintained by producing the next generation through active sexual reproduction. Individuals are just like vehicles in which passengers -genetic information– can ride to be inherited by the next generation through germline lineage. As such, germline cells are the most important cells to maintain the species. Drosophila melanogaster is one of the ideal model organisms where we can easily study gametogenesis. How are germline stem cells maintained in a microenvironment,niche? What is the molecular mechanism that controls differentiation of germline cells to eggs and sperm? How are germline genomes safely guarded by non-coding RNA called piRNA from transposons attacks? How are the piRNAs generated in membrane-less organelle called nuage? Our group has been addressing such molecular mechanisms for the better understanding of gametogenesis.

Tejas (fly homolog of Tdrd5) localizes to a membrane-less organelle called nuage at the periphery of the nucleus of germline cells, and functions in the production of piRNAs.
Members
Toshie Kai (Professor) | kai.toshie.fbs[at]osaka-u.ac.jp |
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Taichiro Iki (Associate Professor) | iki.taichiro.fbs[at]osaka-u.ac.jp |
Shinichi Kawaguchi (Assistant Professor) | kawaguchi.shinichi.fbs[at]osaka-u.ac.jp |
Ritsuko Suyama (Specially Appointed Assistant Professor) | suyama.ritsuko.fbs[at]osaka-u.ac.jp |
Chisato Yanagisawa (Technical Assistant&Secretary) | |
You could probably reach more information of individual researchers by Research Map and researcher's search of Osaka-U.
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Q&A
- What is your hot research topic?
- Genomes in germline cells that differentiate into gametes are inherited by the next generation, and gene expression is tightly regulated by epigenetic control. Currently, we are analyzing not only non-coding RNA and RNA modification, but also function of nuage, a membrane-less organelle that is specific to germline cells. We are excited by the unexpected discoveries of the secrets of germline cells.
- What kind of background do your lab members have?
- The laboratory staff has backgrounds in biochemistry and genetics, and long experience of studying abroad. Since the lab opened in 2015, the number of PhD students has gradually increased, but at first only staff. While in Singapore, PhD students were the main lab members and we had only one postdoc. These individuals were from India, China, Singapore, France, and Malaysia. The current lab at FBS also has a high proportion of international students, so the main language in the lab is English.
- Do you collaborate with other institutions and universities?
- Because I spent many years overseas, I have many friends and former colleagues all over the world. Hence there are many opportunities for international collaborations based on long-standing relationships. We have international collaborations with the labs at the National University of Singapore, the University of Hawaii, and in Japan, Tokyo University and NIBB.
- What kind of careers do your Lab's alumni go on to?
- Two former PhD students became PIs in academic labs in Singapore and India, respectively. Others became senior researchers in India and Singapore. There is one teaching science in one of the top junior high schools in Singapore. The graduate students I supervised in OU got positions at the Scientific Research Institute.
Research Highlights
Publications (Research Articles, Reviews, Books)
2024
piRNA processing within non-membrane structures is governed by constituent proteins and their functional motifs
FEBS J. 2024 (PMID:39739617 DOI:10.1111/febs.17360)
HemK2 functions for sufficient protein synthesis and RNA stability through eRF1 methylation during Drosophila oogenesis
Development 151 (14): dev202795 2024 (PMID:38881530 DOI:10.1242/dev.202795)
2023
Microbes control Drosophila germline stem cell increase and egg maturation through hormonal pathways
Commun. Biol. 6(1):1287 2023 (PMID:38123715 DOI:10.1038/s42003-023-05660-x)
Tejas functions as a core component in nuage assembly and precursor processing in Drosophila piRNA biogenesis
J. Cell Biol. 222(10):e202303125 2023 (PMID:37555815 DOI:10.1083/jcb.202303125)
miRNA/siRNA-directed pathway to produce noncoding piRNAs from endogenous protein-coding regions ensures Drosophila spermatogenesis
Science Advances Vol. 9, No. 29 2023 (PMID:37467338 DOI:10.1126/sciadv.adh0397)
2022
The Tudor-domain containing protein, Kotsubu (CG9925), localizes to the nuage and functions in piRNA biogenesis in D. melanogaster
Frontiers in Molecular Biosciences (section RNA Networks and Biology) Vol. 9, Article 818302 2022 (PMID:35425810 DOI:10.3389/fmolb.2022.818302)
2021
Review: Non-membranous RNP condensates control the fate of germline cells
Jikken-igaku special issue Vol. 39, No. 10 2021
2020
Modulation of Ago2 Loading by Cyclophilin 40 Endows a Unique Repertoire of Functional miRNAs During Sperm Maturation in Drosophila
Cell Rep. Vol. 33, No. 6, 108380 2020 (PMID:33176138 DOI:10.1016/j.celrep.2020.108380)
A genome database for a Japanese population of the larvacean Oikopleura dioica
Dev. Growth Differ. Vol. 62, No. 6, 450-461 2020 (PMID:32677034 DOI:10.1111/dgd.12689)
Drosophila MARF1 ensures proper oocyte maturation by regulating nanos expression
PLoS ONE Vol. 15, No. 4, e0231114 2020 (PMID:32243476 DOI:10.1371/journal.pone.0231114)
Finding cell-specific expression patterns in the early Ciona embryo with single-cell RNA-seq
Sci. Rep. 10:4961-4970 2020 (PMID:32188910 DOI:10.1038/s41598-020-61591-1)
Editorial overview: Stem cells orchestrate oogenesis: a lesson from the fruit fly, Drosophila melanogaster.
Curr. Opin. Insect Sci. 37:1-62 2020 (PMID:32199590 DOI:10.1016/j.cois.2020.03.001)
2018
A Suppressor Screen for AGO1 Degradation by the Viral F-Box P0 Protein Uncovers a Role for AGO DUF1785 in sRNA Duplex Unwinding
Plant Cell 30(6):1353-1374 2018 (PMID:29848768 DOI:10.1105/tpc.18.00111)
Structural Flexibility Enables Alternative Maturation, ARGONAUTE Sorting and Activities of miR168, a Global Gene Silencing Regulator in Plants
Mol. Plant. 11(8):1008-1023 2018 (PMID:29803952 DOI:10.1016/j.molp.2018.05.006)
Heterochromatin protein 1a functions for piRNA biogenesis predominantly from pericentric and telomeric regions in Drosophila
Nat. Commun. 9(1):1735 2018 (PMID:29728561 DOI:10.1038/s41467-018-03908-3)
Protecting and diversifying the germline.
Genetics 208(2):435-471 2018 (PMID:29378808 DOI:10.1534/genetics.117.300208)
2017
In vitro formation of plant RNA-induced silencing complexes using as extract of evacuolated tobacco protoplasts
Methods Mol Biol 1640:39-53 2017 ( DOI:10.1007/978-1-4939-7165-7_3)
A complex of Arabidopsis DRB proteins can impair dsRNA processing.
RNA 23(5):782-797 2017 (PMID:28232389 DOI:10.1261/rna.059519.116)
Biochemical and genetic functional dissection of the P38 viral suppressor of RNA silencing.
RNA 23(5):639-654 2017 (PMID:28148824 DOI:10.1261/rna.060434.116)
Messages on Small RNA Duplexes in Plants
J. Plant Res. 130(1):7-16 2017 (PMID:27878651 DOI:10.1007/s10265-016-0876-2)
2016
The piRNA pathway is developmentally regulated during spermatogenesis in Drosophila.
RNA 22(7):1044-54 2016 (PMID:27208314 DOI:10.1261/rna.055996.116)
A Short Open Reading Frame Encompassing the MicroRNA173 Target Site Plays a Role in trans-Acting Small Interfering RNA Biogenesis
Plant Physiol. 171(1):359-368 2016 (PMID:26966170 DOI:10.1104/pp.16.00148)
Our ideal candidate (as a graduate student)
Kai Laboratory is looking for students dedicated to the stuides addressing the mystery of germline cells.
FBS is a very advanced research/educational institution that attracts diverse researchers. FBS has well equipped common facilities and ooffers a variety of learning oppoorunites.The graduate students are very well supported. If you wish to enrol, please refer the information about the entrance examination of FBS and contact the Kai-lab staff.
Prof Kai has supervised many PhD students and interns at Canegie Institution, National University of Singapore and Nanyang Technological University. Taking advantage of her long experience in research in USA and Singapore, we hope to contribute to global human resources.
If you would like to participate the lab as a postdoctoral researcher, please do not hesitate to contact the Kai-lab staffs.
Contact
Germline Biology Group, Graduate School of Frontier Biosciences, Osaka University,
1-3 Yamadaoka, Suita, Osaka 565-0871 Japan.
TEL: +81-6-6879-7974
E-mail: kai.toshie.fbs[at]osaka-u.ac.jp (Prof. Toshie Kai)
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