Cutting edge Seminar
Speaker: Masaru Tamura （Research Scientis, Technology and Development Team for Mouse Phenotype Analysis, RIKEN BioResource Center ）
Title: Morphometrics of the mouse embryo using the X-Ray Computed Tomography (CT)
Date&Time: 14 Mar. (Wed.) 2018, 12:00- 13:00
Venue: Conference Room(1F), IMEG
Abstract:
Classic histological technique using the paraffin sections followed by hematoxylin and eosin staining is a gold standard to detect morphological anomalies of mutants or to compare morphological features of model animals. Though this method is well established and widely performed everywhere, there are following weak points. Preparation of the excellent sections needs dexterous manipulation, and is time-consuming. Reconstruction of the 3D images from the 2D section information is arduous task. In addition to these, genome editing technologies such as CRISPR/Cas9 system make it possible to the gene knockout of various animals, which has no embryonic stem (ES) cells, with unprecedented simplicity and speed. It means that bottleneck of the functional gene analysis will make up the transition from generating the knockout animal to the phenotyping. Therefore, we need easy and high-throughput phenotyping methods.
In medical fields, multi-detector row computed tomography (MDCT) is now commonly used for diagnosis, and becoming a powerful tool for detection and classification of human symptomatic state. X-ray micro-computed tomography (micro-CT) for model animals is identical in its basic principles to MDCT. Micro-CT easily generates 2D slice images at any position and angle, and thereby reconstructs 3D image. It provides excellent images of bone and adipose tissues, because these samples have high contrast Hounsfield unit. Adversely, it has not provided good images of other non-mineralized soft tissues. In this seminar, we would like to introduce an improved method to obtain high resolution of 2D and 3D images of soft tissues in mouse embryos using the micro-CT with inorganic iodine or phosphotungstic acid as a contrast reagent. We also argue about the possibility of this method for future high-throughput morphometrics from various aspects, e.g., degree of resolution, simplicity and costs.
References:
- Meehan TF. et al., Disease Model Discovery from 3,328 Gene Knockouts by The International Mouse Phenotyping Consortium. Nature Genetics 2017, 49: 1231-1238.
- Fujihira H., Masahara-Negishi Y., Tamura M., Harada Y., Chengcheng H., Wakana S., Taniguchi N., Kondoh G., Yamashita T., Funakoshi Y. and Suzuki T. Lethality of mice bearing a knockout of the Ngly1-gene is rescued by the additional deletion of the Engase gene. PLoS Genet. 2017 13: e1006696
- Kitazawa M., Tamura M., Kaneko-Ishino T. and Ishino F. Severe damage to the placental fetal capillary network causes mid to late fetal lethality and reduction of placental size in Peg11/Rtl1 KO mice. Genes to Cells 2017, 22: 174-188.
- Dickinson ME. et al., High-throughput discovery of novel developmental phenotypes. Nature 2016, 537: 508-514
- Tamura M. and Shiroishi T. GSDM family genes meet autophagy. Biochemical Journal, 2015 469: e5.
- Xie Z., Liang X., Guo L., Kitamoto A., Tamura M., Shiroishi T. and Gillies D. An automatic classification framework for ventricular septal defects: a pilot study on high-throughput mouse embryo cardiac phenotyping. J. Med. Imag., 2015 2 (4): 041003
- Tamura M., Amano T. and Shiroishi T. The Hand2 gene dosage effect in developmental defects and human congenital disorders. Curr. Top. Dev. Biol., 2014 110: 129-152.
8. Tamura M., Hosoya M., Fujita M., Iida T., Amano T., Maeno A., Kataoka T., Otsuka T., Tanaka S, Tomizawa S. and Shiroishi T. Over-dosage of Hand2 causes limb and heart defects in human chromosomal disorder, partial trisomy distal 4q. Hum. Mol. Genet., 2013 22: 2471-2481
