5th International Symposium on the Biology of Vertebrate Sex Determination 2009

The 5th international symposium on the biology of vertebrate sex determination is going to be held at Royal Kona Resort in Kona, Hawaii from April 20 through April 24, 2009. The aim of this symposium is to bring together scientists and students from a wide variety of disciplines with a common interest in sex determination. I am also participating at the meeting and the title is “Neurotrophin-3, a target gene for Sry action”. I anticipate meeting with renown scientists in the field. So far, in each symposium, scientists have presented at least one breakthrough in the field. I am anxiously waiting to hear another yet new breakthrough  on Sry/Sox9 signalling in the gonad. For details of this and previous meetings, please visit the following website:

Symposium website

Photogallery 2006

With Drs. Eva Eicher and Roger V. Short.

 

Functional lifespan of Sry

Kanai group in Tokyo set an experiment to show  how long the Sry gene becomes functionally active to induce downstream genes to complete the process of male sex determination in mice. It is a novel finding.

A critical time window of Sry action in gonadal sex determination in mice.

Hiramatsu R, Matoba S, Kanai-Azuma M, Tsunekawa N, Katoh-Fukui Y, Kurohmaru M, Morohashi K, Wilhelm D, Koopman P, Kanai Y.

Department of Veterinary Anatomy, The University of Tokyo, Yayoi 1-1-1, Bunkyoku, Tokyo 113-8657, Japan.

In mammals, the Y-linked sex-determining gene Sry cell-autonomously promotes Sertoli cell differentiation from bipotential supporting cell precursors through SRY-box containing gene 9 (Sox9), leading to testis formation. Without Sry action, the supporting cells differentiate into granulosa cells, resulting in ovarian development. However, how Sry acts spatiotemporally to switch supporting cells from the female to the male pathway is poorly understood. We created a novel transgenic mouse line bearing an inducible Sry transgene under the control of the Hsp70.3 promoter. Analysis of these mice demonstrated that the ability of Sry to induce testis development is limited to approximately 11.0-11.25 dpc, corresponding to a time window of only 6 hours after the normal onset of Sry expression in XY gonads. If Sry was activated after 11.3 dpc, Sox9 activation was not maintained, resulting in ovarian development. This time window is delimited by the ability to engage the high-FGF9/low-WNT4 signaling states required for Sertoli cell establishment and cord organization. Our results indicate the overarching importance of Sry action in the initial 6-hour phase for the female-to-male switching of FGF9/WNT4 signaling patterns.

Article link: http://www.ncbi.nlm.nih.gov/pubmed/19036799 

 

A new addition to the understanding of testis cord formation

Koopman group in Australia have recently shown that endothelial cells contribute to testis cord formation in mice.

Endothelial cell migration directs testis cord formation

Combes AN, Wilhelm D, Davidson T, Dejana E, Harley V, Sinclair A, Koopman P.

Division of Molecular Genetics and Development, Institute for Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia.

While the molecular cues initiating testis determination have been identified in mammals, the cellular interactions involved in generating a functional testis with cord and interstitial compartments remain poorly understood. Previous studies have shown that testis cord formation relies on cell migration from the adjacent mesonephros, and have implicated immigrant peritubular myoid cells in this process. Here, we used recombinant organ culture experiments to show that immigrant cells are endothelial, not peritubular myoid or other interstitial cells. Inhibition of endothelial cell migration and vascular organisation using a blocking antibody to VE-cadherin, also disrupted the development of testis cords. Our data reveal that migration of endothelial cells is required for testis cord formation, consistent with increasing evidence of a broader role for endothelial cells in establishing tissue architecture during organogenesis.

Article link: http://www.ncbi.nlm.nih.gov/pubmed/19041858

 

 

Skinner Laboratory

I am working in the Laboratory of Dr. Michael Skinner  at Washington State Univesity, Pullman, WA. Dr. Skinner is a preeminent figure in the field of reproductive biology and epigenetics. Recent finding that the effects of environmental toxic substances cause epigenetic changes in the germ line that can pass to subsequent generations has received public attention.

This laboratory focuses on three major areas of research: testis development, ovary development, and epigenetics. In testis development project, I am involved. We are searching for molecular mechanisms underlying Sertoli and Leydig cell differentiation in the fetal testis. Ovary project focuses on molecular events in primordial to primary follicle transition. Epigenetic project focuses on mapping of whole rat/mouse epigenome, epigenetically imprinted genes and discovery of epigenetic biomarkers.

During development, an embryo is exposed to a variety of stressors through mother’s exposure to such substances. Such an exposure significantly impacts the developmental processes and at the same time any abnormality that occurs can easily be epigenetically-imprinted. We are trying to show the world how future diseases get imprinted in the germ line when life is still within the fetus and passes to subsequent generations via germ-line transmission. Some of the findings have already been ranked one of the top 100 discoveries in the USA. 

Dr. Skinner keeps his lab running in a very friendly atmosphere. Science is our passion and friendship is our relation. 

 

 

 

>Laboratory of Dr. Michael Skinner

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I am working in the laboratory of Dr. Michael Skinner, Washington State Univesity. Dr. Skinner is a preeminent figure in reproductive biology and Epigenetics. The finding that the effects of environmental toxic sustances cause epigenetic changes in the germ line that can pass to subsequent generations has received public attention. We are trying to show the world how future diseases can get imprinted in the germ line when life is still within the fetus. Some findings have been ranked one of the top 100 discoveries in the year 2007.
Dr. Skinner keeps his lab running in a very friendly atmosphere. Science is our passion and friendship is our relation.Here is the picture of our team- half the members are absent in the picture, though.

 

>Blurring the edges in vertebrate sex determination: a review

>I usually wrap up all the review and article published about gonadal sex determination in mammals and other vertebrates. Following review by Dr. Blanche Capel et al. is worth reading:

Blurring the edges in vertebrate sex determination:

Lindsey A Barske and Blanche Capel
Current Opinion in Genetics & Development
Volume 18, Issue 6, December 2008, Pages 499-505

Abstract: Sex in vertebrates is determined by genetically or environmentally based signals. These signals initiate molecular cascades and cell–cell interactions within the gonad that lead to the adoption of the male or female fate. Previously, genetically and environmentally based mechanisms were thought to be distinct, but this idea is fading as a result of the unexpected discovery of coincident genetic and thermal influences within single species. Together with accumulating phylogenetic evidence of frequent transitions between sex-determining mechanisms, these findings suggest that genetic and environmental sex determination actually represent points on a continuum rather than discrete categories, and that populations may shift in one direction or the other in response to mutations or changing ecological conditions. Elucidation of the underlying molecular basis of sex determination in mice has yielded a bistable model of mutually antagonistic signaling pathways and feedback regulatory loops. This system would be highly responsive to changes in the upstream primary signal and may provide a basis for the rapid evolution of and transitions between different methods of sex determination.

Article link: http://www.ncbi.nlm.nih.gov/pubmed/19152784

 

Calmodulin drives entry of transcription factors into the nucleus of Sertoli cells

I found this article very interesting. It is worth reading if you are searching for singalling pathways that SRY controls during embryogenesis.

Calmodulin-driven nuclear entry: Trigger for sex determination and terminal differentiation.

Hanover JA, Love DC, Prinz WA. Laboratory of Cell Biochemistry and Biology, NIDDK, NIH, Bethesda, MD 20892-0851.

We originally proposed that Ca+2*Calmodulin mediates a novel nuclear entry pathway distinct from the canonic Ran-dependent pathway. Ca+2*Calmodulin -driven nuclear entry, while seemingly redundant, is now known to facilitate nuclear delivery of architectural transcription factors to chromatin. Intriguingly, defects in calmodulin-driven nuclear import of the transcription factors SRY and SOX9 in Sertoli cells lead to human sex reversal diseases with altered male gonad development. Calmodulin-triggered nuclear entry is an evolutionarily ancient feature of eukaryotes observed from yeast to man. Ca+2*Calmodulin-triggered nuclear entry of key architectural transcription factors is a potentially key epigenetic regulator of terminal differentiation in response to cellular signaling.

 

>My daughter (Niha) Dancing

>Niha like dancing. I saw her dancing for the first time without instruction. She just looked at you tube for Nepalese folk dance and picked up some steps.

NihaDancing

 

My daughter (Niha) Dancing

Niha like dancing. I saw her dancing for the first time without instruction. She just looked at you tube for Nepalese folk dance and picked up some steps.

NihaDancing

 

>Congratulations ! Mr. Obama.

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Barack Obama has been elected as a 44th President of United States of America. My heartfelt congratulations to him and the people of United States on this historic victory. His victory symbolizes that America is the land of Opportunity. You aim and work hard, America will fullfil your dreams! Let’s hope he will bring about socio-economic changes in the USA and also a peace in the whole world. May he excel in his presidency.

We look forward to getting supports to education and research.

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