The black box at the beginning of life

September 16, 2015, Kyoto University
Kyoto University scientists are casting light into the black box of human "germ cell" development. It is hoped that their new model may lead to findings in all stages of human development, from the creation of sperm and eggs to the process of embryo-to-adult development. Credit: Kyoto University

Life begins with an egg and a sperm: that much is clear. But how do these "germ cells" form, and how do they pass genetic traits from one generation to the next?

Researchers working at Kyoto University have created a lab-based human germ cell development model that should shed light on these basic questions. The hope is that their accomplishment may lead to a molecular-level understanding of conditions such as infertility.

The underlying mechanisms of early germ cell development in humans have remained unclear because of a lack of robust experimental methods, as well as inherent difficulties with studying human embryos. In a promising breakthrough, recently published in Cell Stem Cell, the research team has recreated human germ cell development in the laboratory, revealing specific key elements and events that occur at the beginning of human life.

"When I read about his work I knew I had to come back [to Japan]", said co-first author Kotaro Sasaki, referring to lead researcher Mitinori Saitou's previous work in the field. Sasaki, who had established a pathology career in the United States, returned to join Saitou's team in Kyoto. For this study, five laboratories at the university's Center for iPS Cell Research and Application (CiRA) collaborated.

To date, most such research has been restricted to mice. While this work provides useful information that is generally applicable to mammals, there has still been a lack of information specific to humans.

To that end, Saitou's team recreated the developmental process of human , which gives rise to reproductive sperm and eggs. In addition to illustrating key transcription interactions and signaling events, the scientists gained insight into how epigenetic marks—traits that are inherited without changes to the DNA sequence—are "erased" at the beginning of germ cell development.

"We demonstrated the early events in human germ cell development," explains Sasaki. "Our work should provide a basis to gain a better understanding of how certain disorders such as infertility and growth impairment come about."

The team's model, still in its early stages, is hoped to form a foundation for continuing studies on germ cell lineage. "By further reconstituting human germ in vitro, we may be able to discover the mechanisms throughout the entire developmental process from embryo to adult," says Professor Saitou.

Explore further: Egg and sperm race: Scientists create precursors to human egg and sperm in the lab

More information: "Robust In Vitro Induction of Human Germ Cell Fate from Pluripotent Stem Cells" Cell stem cell 17, Published Online: July 16, 2015. dx.doi.org/10.1016/j.stem.2015.06.014

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JVK
1 / 5 (2) Sep 16, 2015
Excerpt: "...the scientists gained insight into how epigenetic marks—traits that are inherited without changes to the DNA sequence—are "erased" at the beginning of germ cell development."

See also: Intronic Non-CG DNA hydroxymethylation and alternative mRNA splicing in honey bees
http://www.biomed...4/14/666 The authors present evidence that argues that alternative splicing is used to alter protein phosphorylation, which can alter protein stability, subcellular localization, activity, and other properties [45].

Our model of epigenetically-effected RNA-mediated cell type differentiation was extended to insects in 2000 and to life-history transistions in honeybees in 2005. We published in 1996 in Hormones and Behavior. From Fertilization to Adult Sexual Behavior http://www.hawaii...ion.html

See our section on molecular epigenetics.

JVK
1 / 5 (2) Sep 16, 2015
See also: Team finds key to making neurons from stem cells
http://medicalxpr...lls.html

Cell type differentiation appears to be biophysically constrained by nutrient uptake and RNA-mediated protein folding chemistry that protects DNA from virus-driven genomic entropy in all cell types of all individuals of all living genera via conserved molecular mechanisms and fixation of amino acid substitutions that stabilize the organized genomes of species from microbes to man via their pheromone-controlled physiology of reproduction.

Evolutionary theorists hate the fact that all of the above links the nutrient-dependent de novo creation of olfactory receptor genes to chromosomal rearrangements and all biodiversity without mention of mutations, natural selection (except for food) or evolution. Watch them down-rate my posts so that others will see only their pseudoscientific nonsense.
Vietvet
5 / 5 (2) Sep 16, 2015
Why does JVK get down-rated?

Creationist crank

Despises Darwin

Lies about the work of real scientists (He flunked out of college, worked as a lab tech).

He sells a "perfume" based on pseudoscience.

Uses word salads to hide is biological ignorance.

Changes the topic when he is cornered.

Historically ignorant.
JVK
1 / 5 (1) Sep 17, 2015
See also: Nutrient-dependent/pheromone-controlled adaptive evolution: a model.
http://www.ncbi.n...24693353

AND

Cell types, immune profiling, health, and pathology

http://rna-mediat...thology/
Vietvet
not rated yet Sep 17, 2015
Criticisms of the nutrient-dependent pheromone-controlled evolutionary model

http://www.ncbi.n...4049134/

http://rna-mediat...thology/ is a phishing site
JVK
1 / 5 (1) Sep 17, 2015
Re: Criticisms and the claim that RNA-mediated.com is a phishing site>
http://www.ncbi.n...4049134/

Editor's comment: "The 2013 review article by James Vaughn Kohl published in Socioaffective Neuroscience & Psychology and criticized in the above Letter to the Editor was subjected to standard peer review and the revised version was accepted by me after it had been accepted by both reviewers."

If biologically uninformed science idiots scare you away from visiting http://rna-mediated.com/ you can find information at http://www.rnasociety.org/ or via a google search:

https://www.googl...mediated

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