Study reveals the genetic start-up of a human embryo

Human Embryo. Credit: Ed Uthman, MD/Wikipedia

An international team of scientists led from Sweden's Karolinska Institutet has for the first time mapped all the genes that are activated in the first few days of a fertilized human egg. The study, which is being published in the journal Nature Communications, provides an in-depth understanding of early embryonic development in human - and scientists now hope that the results will help finding for example new therapies against infertility.

At the start of an individual's life there is a single fertilized egg cell. One day after fertilization there are two cells, after two days four, after three days eight and so on, until there are billions of cells at birth. The order in which our are activated after fertilization has remained one of the last uncharted territories of .

There are approximately 23,000 in total. In the current study, scientists found that only 32 of these genes are switched on two days after fertilization, and by day three there are 129 activated genes. Seven of the genes found and characterized had not been discovered previously.

"These genes are the 'ignition key' that is needed to turn on human . It is like dropping a stone into water and then watching the waves spread across the surface", says principal investigator Juha Kere, professor at the Department of Bio-sciences and Nutrition at Karolinska Institutet and also affiliated to the SciLifeLab facility.

The researchers had to develop a new way of analyzing the results in order to find the new genes. Most genes code for proteins but there are a number of repeated DNA sequences that are often considered to be so-called 'junk DNA', but are in fact important in regulating gene expression. In the current study, the researchers show that the newly identified genes can interact with the 'junk DNA', and that this is essential to the start of development.

"Our results provide novel insights into the regulation of in human. We identified novel factors that might be used in reprogramming cells into so-called for possible treatment of a range of diseases, and potentially also in the treatment of infertility", says Outi Hovatta, professor at Karolinska Institutet's Department of Clinical Science, Intervention and Technology, and a senior author.

The study was a collaboration between three research groups from Sweden and Switzerland that each provided a unique set of skills and expertise. The work was supported by the Karolinska Institutet Distinguished Professor Award, the Swedish Research Council, the Strategic Research Program for Diabetes funding at Karolinska Institutet, Stockholm County, the Jane & Aatos Erkko Foundation, the Instrumentarium Science Foundation, and the Åke Wiberg and Magnus Bergvall foundations. The computations were performed on resources provided by SNIC through Uppsala Multidisciplinary Center for Advanced Computational Science (UPPMAX).

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More information: 'Novel PRD-like homeodomain transcription factors and retrotransposon elements in early human development.', Virpi Töhönen, Shintaro Katayama, Liselotte Vesterlund, Eeva-Mari Jouhilahti, Mona Sheikhi, Elo Madissoon, Giuditta Filippini-Cattaneo, Marisa Jaconi, Anna Johnsson, Thomas R. Bürglin, Sten Linnarsson, Outi Hovatta and Juha Kere, Nature Communications, 3 September 2015, DOI: 10.1038/NCOMMS9207
Journal information: Nature Communications

Citation: Study reveals the genetic start-up of a human embryo (2015, September 3) retrieved 13 October 2019 from
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Sep 03, 2015
From Fertilization to Adult Sexual Behavior

All cell type differentiation is nutrient-dependent and RNA-directed via RNA-mediated gene duplication and RNA-mediated amino acid substitutions linked to the physiology of reproduction in all living genera.

See also: Nutrient-dependent/pheromone-controlled adaptive evolution: a model.

Sep 03, 2015
Criticisms of the nutrient-dependent pheromone-controlled evolutionary model


Sep 03, 2015
Kohl doesn't understand what happens during differentiation and confuses differentiation of cells during maturation of a single organism over its lifetime with changes occurring over multiple generations.

Duplications do not occur in somatic cells during maturation and neither do amino acid substitutions. All of your cells have the exact same genome besides RBCs and immune system cells that undergo somatic hypermutation.

Sep 04, 2015
anonymous_9001 (Andrew Jones) and Vietvet (Steven Taylor) are biologically uninformed science idiots who know nothing about how cell type differentiation occurs.

See also: Role of olfaction in Octopus vulgaris reproduction


The octopus genome and the evolution of cephalopod neural and morphological novelties

The octopus genome sequencing linked our 1996 review of RNA-mediated cell type differentiation across all species via the biophysically constrained chemistry of nutrient-dependent protein folding and physiology of reproduction in marine invertebrates, insects, and all vertebrates via microRNAs, adehesion proteins, and nutrient-dependent amino acid substitutions.

Elekonich and Robinson (2000) included mention of our 1996 model in "Organizational and activational effects of hormones on insect behavior" http://www.ncbi.n...d/109802

Sep 04, 2015
All of your cells have the exact same genome besides RBCs and immune system cells that undergo somatic hypermutation.

More than 1100 nutrient-dependent human hemoglobin variants must be placed into the context of ridiculous theories to be included in the context of somatic hypermutations.

http://medical-di...mutation hypermutation (hī'pĕr-myū-tā'shŭn),
A process whereby heavy and light chain genes of the antibody molecule are mutated at a high rate, leading to diversity in the antibody repertoire.

Alternatively, a single amino acid substitution links RNA-mediated cell type differentiation in all living genera via what is currently known to serious scientists about physics, chemistry, and the conserved molecular mechanisms of biophysically constrained protein folding in all cells of all individuals.

See: Here you will find information that links physics, chemistry, and molecular epigenetics...

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