Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How IVF could be causing genetic errors in embryos

19.06.2006
The conditions in which embryos are cultured in the laboratory during in vitro fertilisation could be causing genetic errors that are associated with certain developmental syndromes and other abnormalities in growth and development, such as low birth weight.

Researchers told the 22nd annual conference of the European Society of Human Reproduction and Embryology today (Monday) that preliminary work investigating genetic imprinting in mouse embryos had shown that certain culture media and concentrations of oxygen altered the expression of several imprinted genes.

Imprinting is the process by which some genes are activated or inactivated depending on whether they have been inherited in chromosomes from the mother or the father.

Professor Paolo F Rinaudo, a scientist at the Center for Reproductive Sciences, University of California, San Francisco, USA, said: “We found that the culture of mouse embryos in the laboratory is sufficient to alter the expression of several imprinted genes and that this effect can be modified by the composition of the culture medium and oxygen concentration.

“Interestingly, the expression of one gene, H19, was reduced regardless of the culture conditions, and as H19 is associated with Beckwith Wiedeman syndrome, this finding needs to be investigated further.”

However, he cautioned against reading too much into his results at this stage. “These studies are important for better directing future resources and studies in humans. But we must remember that these are preliminary results in a mouse model, and they need to be repeated and confirmed in other strains of mice before translating to studies in humans.”

Other research has suggested that culturing embryos in the laboratory during IVF could be affecting embryos adversely. “Emerging new evidence shows that some neurological and behavioural abnormalities are associated with assisted reproductive techniques. Cases of Angelman and Beckwith Wiedeman syndromes in humans, which are due to aberrant genomic imprinting, and other abnormalities in growth and development in mice have been described after culture in vitro,” said Professor Rinaudo. Angelman syndrome is characterised by severe mental retardation, speech impairment, balance disorder and a happy, excitable demeanour; it occurs in about one in 10,000 to 30,000 of the population. Beckwith Wiedeman syndrome is characterised by overgrowth, with an abnormally large tongue, umbilical hernia, neonatal hypoglycaemia and a predisposition to certain tumours, in particular, Wilms tumour and hepatoblastoma; it is rare, occurring in one in 36,000 of the population.

Professor Rinaudo and his colleagues cultured mouse embryos in four media with 5% oxygen. Two of the four media were also used with 20% oxygen, making six different cultures in total. As a control, some embryos were left to mature in the mice (in vivo).

“We identified 38 imprinted genes, most of which showed no difference in expression after in vitro culture compared to the in vivo embryos. Five genes showed a statistical difference compared to the in vivo control, depending on the culture conditions,” he said.

The five genes were:

- Cd81– expresses a membrane protein with unknown function during embryogenesis. It is involved in T cell development (part of the immune system) and the hepatitis C virus binds to it to gain entry to cells.

- H19 – a developmentally regulated gene, thought to be a tumour suppressor and associated with Beckwith Wiedeman syndrome.

- Slc38a4 – plays a role in amino acid transport to cells.

- Copg2 – plays a role in transport of proteins within cells and is associated with Silver-Russell syndrome, a growth disorder occurring in 1 in 75,000 births (involves intrauterine growth restriction and subsequent poor growth).

- Gnas – plays a role in cell signalling and is associated with McCune-Albright syndrome (involves bone, hormone and skin abnormalities), pseudohypoparathyroidism Ib (involves inadequate levels of calcium and excessive levels of phosphates in the blood), and GH-secreting adenomas (type of tumour).

Of these, the greatest changes in gene expression were seen in Cd81 (consistently over-expressed in all media) and H19 (consistently under-expressed in all media), but Professor Rinaudo said the significance of these findings was unclear at present.

“The next stage of our research is to examine further the effects of IVF and ICSI on the genetic make-up and the form and function of cells from mouse embryos. We want to understand why these techniques appear to be affecting the imprinting of these genes. We hope this understanding will enable the scientific community to make better culture media for IVF in humans.”

Mary Rice | alfa
Further information:
http://www.mrcommunication.org

More articles from Health and Medicine:

nachricht New malaria analysis method reveals disease severity in minutes
14.08.2017 | University of British Columbia

nachricht New type of blood cells work as indicators of autoimmunity
14.08.2017 | Instituto de Medicina Molecular

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>