TG-1 * Transgallaxys Forum 1

Pages: [1]

Author Topic: Forscher gestrandet. Ihr Gehirn setzt aus. Mitochondrien versagen.  (Read 237 times)

Zahnfee

  • Jr. Member
  • *
  • Posts: 25

Das sieht nach einem klassischen Denkfehler aus.

https://www.dailymail.co.uk/news/article-6424407/Every-person-spawned-single-pair-adults-living-200-000-years-ago-scientists-claim.html

[*quote*]
All humans are descended from just TWO people and a catastrophic event almost wiped out ALL species 100,000 years ago, scientists claim

    Genetic 'bar codes' of five million animals from different species were surveyed
    The research deduced that humans and animals sprang from single pair
    This happened after a catastrophic event a long time after the last ice age
[*/quote*]


www.pontecorboli.com/digital1/humanevolution/blog/2018/05/22/why-should-mitochondria-define-species/

[*quote*]
Why should mitochondria define species?

Stoeckle M.Y., Thaler D.S.

More than a decade of DNA barcoding encompassing about five million specimens covering 100,000 animal species supports the generalization that mitochondrial DNA clusters largely overlap with species as defined by domain experts. Most barcode clustering reflects synonymous substitutions. What evolutionary mechanisms account for synonymous clusters being largely coincident with species? The answer depends on whether variants are phenotypically neutral. To the degree that variants are selectable, purifying selection limits variation within species and neighboring species may have distinct adaptive peaks. Phenotypically neutral variants are only subject to demographic processes—drift, lineage sorting, genetic hitchhiking, and bottlenecks. The evolution of modern humans has been studied from several disciplines with detail unique among animal species.  Mitochondrial barcodes provide a commensurable way to compare modern humans to other animal species. Barcode variation in the modern human population is quantitatively similar to that within other animal species. Several convergent lines of evidence show that mitochondrial diversity in modern humans follows from sequence uniformity followed by the accumulation of largely neutral diversity during a population expansion that began approximately 100,000 years ago. A straightforward hypothesis is that the extant populations of almost all animal species have arrived at a similar result consequent to a similar process of expansion from mitochondrial uniformity within the last one to several hundred thousand years.

Stoeckle M.Y.
Program for the Human Environment
The Rockefeller University
1230 York AVE
New York, NY 10065
USA
Email: mark.stoeckle@rockefeller.edu

Thaler D.S.
Biozentrum, University of Basel Klingelbergstrasse 50/70
CH – 4056 Basel
Switzerland
Email: david.thaler@unibas.ch
davidsthaler@gmail.com

DOI: 10.14673/HE2018121037

Download Open Access article
http://www.pontecorboli.com/digital/he_archive_articles/he122018/1_Stockle_Thaler.pdf

Categorie HE-Vol. 33 - n.1-2-2018   
Navigazione articolo
What went wrong in cross-cultural psychology over the past 40 years? The developmental approach in opposition to two main ideologies of our time, cultural relativism and universalism of mind
Behaviorally Induced Change in Post-cranial (Upper Ankle Joint) Morphology: Phenotypic Plasticity in an Altered Habitat
[*/quote*]


https://phys.org/news/2018-05-gene-survey-reveals-facets-evolution.html

[*quote*]
Sweeping gene survey reveals new facets of evolution
May 28, 2018 by Marlowe Hood

For the planet's 7.6 billion people, 500 million house sparrows, or 100,000 sandpipers, genetic diversity "is about the same," Mark Stoeckle from the Rockefeller University in New York told AFP

Who would have suspected that a handheld genetic test used to unmask sushi bars pawning off tilapia for tuna could deliver deep insights into evolution, including how new species emerge?

And who would have thought to trawl through five million of these gene snapshots—called "DNA barcodes"—collected from 100,000 animal species by hundreds of researchers around the world and deposited in the US government-run GenBank database?

That would be Mark Stoeckle from The Rockefeller University in New York and David Thaler at the University of Basel in Switzerland, who together published findings last week sure to jostle, if not overturn, more than one settled idea about how evolution unfolds.

It is textbook biology, for example, that species with large, far-flung populations—think ants, rats, humans—will become more genetically diverse over time.

But is that true?

"The answer is no," said Stoeckle, lead author of the study, published in the journal Human Evolution.

For the planet's 7.6 billion people, 500 million house sparrows, or 100,000 sandpipers, genetic diversity "is about the same," he told AFP.

The study's most startling result, perhaps, is that nine out of 10 species on Earth today, including humans, came into being 100,000 to 200,000 years ago.


"This conclusion is very surprising, and I fought against it as hard as I could," Thaler told AFP.

That reaction is understandable: How does one explain the fact that 90 percent of animal life, genetically speaking, is roughly the same age?

Was there some catastrophic event 200,000 years ago that nearly wiped the slate clean?

Simpler, cheaper

To understand the answer, one has to understand DNA barcoding. Animals have two kinds of DNA.

The one we are most familiar with, nuclear DNA, is passed down in most animals by male and female parents and contains the genetic blueprint for each individual.

In analysing DNA barcodes across 100,000 species, researchers found a telltale sign showing that almost all the animals emerged about the same time as humans

The genome—made up of DNA—is constructed with four types of molecules arranged in pairs. In humans, there are three billion of these pairs, grouped into about 20,000 genes.

But all animals also have DNA in their mitochondria, which are the tiny structures inside each cell that convert energy from food into a form that cells can use.

Mitochondria contain 37 genes, and one of them, known as COI, is used to do DNA barcoding.

Unlike the genes in nuclear DNA, which can differ greatly from species to species, all animals have the same set of mitochondrial DNA, providing a common basis for comparison.

Mitochondrial DNA is also a lot simpler, and cheaper, to isolate.

Around 2002, Canadian molecular biologist Paul Hebert—who coined the term "DNA barcode"—figured out a way to identify species by analysing the COI gene.

"The mitochondrial sequence has proved perfect for this all-animal approach because it has just the right balance of two conflicting properties," said Thaler.

'Neutral' mutations

On the one hand, the COI gene sequence is similar across all animals, making it easy to pick out and compare.

On the other hand, these mitochondrial snippets are different enough to be able to distinguish between each species.

"It coincides almost perfectly with species designations made by specialist experts in each animal domain," Thaler said.

In analysing the barcodes across 100,000 species, the researchers found a telltale sign showing that almost all the animals emerged about the same time as humans.

What they saw was a lack of variation in so-called "neutral" mutations, which are the slight changes in DNA across generations that neither help nor hurt an individual's chances of survival.

In other words, they were irrelevant in terms of the natural and sexual drivers of evolution.

A new DNA study found that nine out of 10 species on Earth today, including humans, came into being 100,000 to 200,000 years ago

How similar or not these "neutral" mutations are to each other is like tree rings—they reveal the approximate age of a species.

Which brings us back to our question: why did the overwhelming majority of species in existence today emerge at about the same time?

Darwin perplexed

Environmental trauma is one possibility, explained Jesse Ausubel, director of the Program for the Human Environment at The Rockefeller University.

"Viruses, ice ages, successful new competitors, loss of prey—all these may cause periods when the population of an animal drops sharply," he told AFP, commenting on the study.

"In these periods, it is easier for a genetic innovation to sweep the population and contribute to the emergence of a new species."

But the last true mass extinction event was 65.5 million years ago when a likely asteroid strike wiped out land-bound dinosaurs and half of all species on Earth. This means a population "bottleneck" is only a partial explanation at best.

"The simplest interpretation is that life is always evolving," said Stoeckle.

"It is more likely that—at all times in evolution—the animals alive at that point arose relatively recently."

In this view, a species only lasts a certain amount of time before it either evolves into something new or goes extinct.

And yet—another unexpected finding from the study—species have very clear genetic boundaries, and there's nothing much in between.

"If individuals are stars, then species are galaxies," said Thaler. "They are compact clusters in the vastness of empty sequence space."

The absence of "in-between" species is something that also perplexed Darwin, he said.

Explore further: Far from special: Humanity's tiny DNA differences are 'average' in animal kingdom
[*/quote*]


Das ist erschütternd. Philosphisches Geschwätz statt sinnvoller Forschung. Kaum oder gar nicht verständliche Sätze statt einfacher Beschreibungen dessen, was sie gemacht haben.

Auch der Download (http://www.pontecorboli.com/digital/he_archive_articles/he122018/1_Stockle_Thaler.pdf) ändert daran nicht viel

Wieviele Generationen gibt es für 100.000 Jahre Mensch und wieviele für Zauneidechse und wieviele für Erdhummel? Die Spezies haben unterschiedliche Lebensdauern bevor sie geschlechtsreif werden und dementsprechend ist die Zahl von 100.000 Jahren FÜR ALLE falsch.

Wenn es 100.000 Jahre FÜR ALLE sind, und dies unabhängig davon, wieviele Generationen es in diesen 100.000 Jahren gab, dann hat ein Rötgenblitz oder was auch immer kurzfristig eine Menge Individuen ausgelöscht. Das ist kein Massensterben der Arten, sondern ein Massensterben der Individuen. Die Arten leben nachher weiter wie vorher. Nur sind es weniger Individuen.

Beim Absturz des Meteoriten ist das anders gewesen, weil der Meterorit die Lebensumstände dauerhaft geändert hat.

Man hat für die Zeit vor 100.000 - 200.000 keinen Absturz finden können. Einen Strahlungsexplosion hinterläßt keine Massen an Gestein auf der Erdoberfläche, sondern brennt nur DNA durch.

Andererseits kann der Mitochondrienzirkus auch ganz anders abgelaufen sein. Das glaube ich erst, wenn Vergleiche zwischen langlebigen und kurzlebigen Tieren vorliegen.
Logged

Krokant

  • Jr. Member
  • *
  • Posts: 166
Re: Forscher gestrandet. Ihr Gehirn setzt aus. Mitochondrien versagen.
« Reply #1 on: November 27, 2018, 10:56:24 PM »

 :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P  :P



https://twitter.com/MAG2ART/status/1067426184835866625

[*quote*]
Dylan Burnette @MAG2ART

Scientific Dogma: "Humans exclusively get the powerhouses of their cells, mitochondria, from their mother."

Luo et al: "Our data shows mitochondria can come from both parents."

Scientific Dogma (shrugging): "Its not the first time I was wrong."

http://www.pnas.org/content/early/2018/11/21/1810946115

6:33 AM - 27 Nov 2018
[*/quote*]

http://www.pnas.org/content/early/2018/11/21/1810946115

[*quote*]
Biparental Inheritance of Mitochondrial DNA in Humans

Shiyu Luo, C. Alexander Valencia, Jinglan Zhang, Ni-Chung Lee, Jesse Slone, Baoheng Gui, Xinjian Wang, Zhuo Li, Sarah Dell, Jenice Brown, Stella Maris Chen, Yin-Hsiu Chien, Wuh-Liang Hwu, Pi-Chuan Fan, Lee-Jun Wong, Paldeep S. Atwal, and Taosheng Huang
PNAS published ahead of print November 26, 2018 https://doi.org/10.1073/pnas.1810946115
Add to Cart ($10)

    Edited by Douglas C. Wallace, Children’s Hospital of Philadelphia and University of Philadelphia, Philadelphia, PA, and approved October 29, 2018 (received for review June 26, 2018)

    Article Figures & SI Info & Metrics
    PDF

This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.

Significance

The energy-producing organelle mitochondrion contains its own compact genome, which is separate from the nuclear genome. In nearly all mammals, this mitochondrial genome is inherited exclusively from the mother, and transmission of paternal mitochondria or mitochondrial DNA (mtDNA) has not been convincingly demonstrated in humans. In this paper, we have uncovered multiple instances of biparental inheritance of mtDNA spanning three unrelated multiple generation families, a result confirmed by independent sequencing across multiple unrelated laboratories with different methodologies. Surprisingly, this pattern of inheritance appears to be determined in an autosomal dominantlike manner. This paper profoundly alters a widespread belief about mitochondrial inheritance and potentially opens a novel field in mitochondrial medicine.

Abstract

Although there has been considerable debate about whether paternal mitochondrial DNA (mtDNA) transmission may coexist with maternal transmission of mtDNA, it is generally believed that mitochondria and mtDNA are exclusively maternally inherited in humans. Here, we identified three unrelated multigeneration families with a high level of mtDNA heteroplasmy (ranging from 24 to 76%) in a total of 17 individuals. Heteroplasmy of mtDNA was independently examined by high-depth whole mtDNA sequencing analysis in our research laboratory and in two Clinical Laboratory Improvement Amendments and College of American Pathologists-accredited laboratories using multiple approaches. A comprehensive exploration of mtDNA segregation in these families shows biparental mtDNA transmission with an autosomal dominantlike inheritance mode. Our results suggest that, although the central dogma of maternal inheritance of mtDNA remains valid, there are some exceptional cases where paternal mtDNA could be passed to the offspring. Elucidating the molecular mechanism for this unusual mode of inheritance will provide new insights into how mtDNA is passed on from parent to offspring and may even lead to the development of new avenues for the therapeutic treatment for pathogenic mtDNA transmission.

    human genetics mitochondria biparental inheritance paternal transmission mtDNA

Footnotes

    ↵1Present address: Section of Molecular Genetics, PerkinElmer Genomics, Branford, CT 06405.

    ↵2Present address: Center for Medical Genetics, School of Life Sciences, Central South University, 410008 Changsha, Hunan, China.

    ↵3P.S.A. and T.H. contributed equally to this work.
    ↵4To whom correspondence should be addressed. Email: taosheng.huang@cchmc.org.

    Author contributions: P.S.A. and T.H. designed research; S.L., J.Z., N.-C.L., J.S., B.G., Z.L., S.D., J.B., S.M.C., Y.-H.C., W.-L.H., and P.-C.F. performed research; S.L., C.A.V., J.Z., J.S., X.W., L.-J.W., and T.H. analyzed data; S.L., C.A.V., J.S., and T.H. wrote the paper; and N.-C.L., Y.-H.C., W.-L.H., P.-C.F., P.S.A., and T.H. evaluated patients and their families.

    The authors declare no conflict of interest.

    This article is a PNAS Direct Submission.

    This article contains supporting information online at http://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1810946115/-/DCSupplemental

Published under the PNAS license.
View Full Text
[*/quote*]
Logged
Pages: [1]