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some identical twins dont have the same dna

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some identical twins dont have the same dna

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Identical twins may not be carbon copies at the DNA level after all.

On average, identical twins differ by 5.2 genetic changes, researchers report January 7 in Nature Genetics. The finding is important because identical twins - also called monozygotic twins because they come from a single fertilized egg - are often studied to determine whether particular traits, diseases or conditions result from genetics or from environmental influences. Identical twins were thought to be genetically the same, so differences in their health were considered to be the product of their environment. The new finding suggests that some genetic changes could also account for differences between twins.

Researchers in Iceland deciphered the complete genetic makeup, or genome, of 381 pairs of identical twins. Of those, 38 pairs were genetic duplicates of each other, but most had some differences in DNA that probably arose very early in development, either just before one embryo split to form two or shortly after the split. Some of the twins had many genetic differences, including 39 pairs who had more than 100 changes between the twins.

Patterns of mutations among twins suggest that embryos don't split neatly when twins form, the findings suggest. Some twins may arise when a single cell or a small group of cells splits off from the embryo. The number of cells that a twin originates from may determine how genetically different they are from their twin, with more uneven splits of the embryo leading to a greater number of differences between the twins.

Questions or comments on this article? E-mail us at feedback@sciencenews.org

A version of this article appears in the January 30, 2021 issue of Science News.

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master's degree in science journalism from Boston University.

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Some identical twins don't have identical DNA

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Identical twins may not be carbon copies at the DNA level after all. On average, identical twins differ by 5.2 genetic changes, researchers report January 7 in Nature Genetics. The finding is important because identical twins - also called monozygotic twins because they come from a single fertilized egg - are often studied to determine whether particular traits, diseases or conditions result from genetics or from environmental influences.

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In symbiosis:Plants control the genetics of microbes.

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In symbiosis:Plants control the genetics of microbes.

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Researchers from the University of Ottawa have discovered that plants may be able to control the genetics of their intimate root symbionts -- the organism with which they live in symbiosis -- thereby providing a better understanding of their growth.

In addition to having a significant impact on all terrestrial ecosystems, their discovery may lead to improved eco-friendly agricultural applications.

We talked to research lead Nicolas Corradi, Associate Professor in the Department of Biology and Research Chair in Microbial Genomics at the University of Ottawa, and lead author Vasilis Kokkoris, Postdoctoral Fellow in the Corradi Lab, to learn more about their recent study published in the journal Current Biology.

Can you tell us more about your findings?

Nicolas Corradi: "We have uncovered a fascinating genetic regulation between plants and their microbial symbionts, known as Arbuscular Mycorrhizal Fungi (AMF).

AMF are plant obligate symbionts that grow within the plant roots and help their hosts to grow better and be more resistant to environmental stressors.

AMF genetics have long been mysterious; while typical cells carry one nucleus, the cells of AMF carry thousands of nuclei that can be genetically diverse. How these nuclei communicate with each other and whether the plants can control their relative abundance, has been a total mystery.

Our work provides insights into this unique genetic condition:

1- We demonstrate that the host plant symbiont influences the relative abundance of thousands of co-existing nuclei carried by their fungal symbionts.

2- We find evidence that co-existing nuclei of different genetic backgrounds cooperate, rather than compete with one another thus potentially maximizing growth benefits for both the fungi and their plant partners."

How did you come to these conclusions?

Vasilis Kokkoris: "We implemented a novel molecular approach accompanied by advanced microscopy and mathematical modelling. Every single AMF spore carries hundreds of nuclei (see image).

By analyzing single spores, we were able to quantify the genetics of thousands of nuclei and define their relative abundance in different fungal strains and across plant species.

To ensure that we accurately analyze single nuclei, we used advanced microscopy to visualize and count the nuclei in the spores.

Lastly, we used mathematical modelling to prove that the observed abundance of nuclear genotypes we identified cannot be a product of luck but instead is the result of a driven cooperation between them.

To better understand what is regulating the AMF nuclei we grew different AMF strains with different hosts and found that plants have control of the relative abundance of the fungal nuclei."

What are the impacts of your discovery?

Nicolas Corradi: "For many years, AMF have been considered to be genetic peculiarities and far away from model organisms. Inconsistencies are commonly observed in plant-AMF experiments. For example, growing the same fungal strain with different plants can lead to drastically different plant yields. For a long time, this variance in plant growth was blamed on the AMF mysterious genetics.

Our research provides an answer as we demonstrate that the genetics of these fungi, and their effect on plant growth, can be manipulated by plants thus explaining the reason for the observed variability on plant growth.

From an environmental standpoint, this new knowledge allows for better understanding how plants can influence the genetics of their symbiotic partners, thus influencing entire terrestrial ecosystems.

From an economic standpoint, it opens doors to improved sustainable agricultural applications."

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endangered plants; botany; genetics; fungus; ecology; sustainability; rainforests; exotic species

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In symbiosis: Plants control the genetics of microbes

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Researchers have discovered that plants may be able to control the genetics of their intimate root symbionts - the organism with which they live in symbiosis - thereby providing a better understanding of their growth. In addition to having a significant impact on all terrestrial ecosystems, their discovery may lead to improved eco-friendly agricultural applications.

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Lion genetics study uncovers major consequences of habitat fragmentation

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Over the course of only a century, humanity has made an observable impact on the genetic diversity of the lion population. That's the conclusion of a recently published study by Drs. Caitlin Curry and James Derr from the Texas A&M University College of Veterinary Medicine & Biomedical Sciences.

By comparing the DNA of lions today to lions from 100 years ago, they found that there is clear genetic evidence of recent population fragmentation, which is when groups of a species are isolated from each other. This fragmentation could ultimately have a long-term impact on the genetic health of the iconic species. The research was published in the journal Molecular Biology and Evolution.

"I was surprised at what we found -- surprised and disappointed, because it's not what I wanted to see," Derr said. "I really wanted to be able to tell everyone that the management we've been doing for the last 100 years is perfect and to keep doing what we've been doing and everything will be fine. But that's not the take-home lesson; unfortunately, that's not the story we can tell.

Curry and Derr started their study with one overarching question: Has the genetic structure of lion populations changed over the last 100 years?

There have been several studies on modern lions, so gathering data for the modern populations was straightforward. Curry pulled together DNA data from three previously published studies on lions that lived between 1990-2012.

The historical populations, against which they wanted to compare the modern lion DNA, provided more of a challenge. Fortunately, scientists have a way to turn back time. Many of those lion remains still reside perfectly preserved in collections around the world. Curry used DNA extracted from bones, teeth and hides of 143 lions that lived between 1880-1949 to create a historical population data set.

Both population data sets cover the same geographical range from India to Southern Africa where lions are found. Scientists call this type of analysis, comparing data from the same space at different times, a spatiotemporal study.
No Room To Roam
It has been understood for a long time that female lions tend to stay close to the pride in which they were born, while males travel great distances to find new prides. Therefore, males are almost exclusively responsible for the movement of genes in the population, which helps keep genetic diversity within the species high.

As the human population continues to rapidly grow across Africa and more and more barriers to lion movement have gone up in the form of cities, fences and farmland, male lions haven't been able to travel the distances they once could.

According to Curry, while lions are still genetically diverse right now, the results in the DNA were more pronounced than she expected.

"In the historical population, you couldn't easily identify where a lion was from based on its nuclear DNA. This is due to high historical levels of gene flow across the population," she said. "But in the modern population, you can determine the general area, or sub-population, for most of the lions. But, even with sub-populations being more isolated, the overall level of genetic diversity is still considered high across all lion populations."
Consequences Of Low Genetic Diversity
If lions are still generally genetically healthy today, then why does this matter?

"Over the last 100 years or so, we have restricted the natural movements of many species," Derr said. "This isolation leads to reduced gene flow and ultimately may result in reducing genetic diversity to a level that threatens the survival of local populations."

Perhaps the most well-known example of what happens with a lack of genetic diversity is another large cat, the African cheetah.

According to genetic analysis, scientists believe cheetahs have suffered two large bottleneck events, or events that lead to a rapid shrinking of the gene pool. When these events happen, it results in the breeding of closely related individuals in the population, or inbreeding, creating very low genetic diversity.

This has led to a current cheetah population that, even in the wild, struggles to fend off new diseases, has difficulty breeding, and faces other significant health problems.
A Story Of Hope
But that fate can still be avoided in lions, especially now that experts are armed with proof that lion populations have been significantly impacted by isolation and subdivision.

"This should not be a disheartening story but rather one of hope," Curry said. "Yes, we see a decrease in genetic diversity across lion populations over the past century. But, currently, compared with other mammalian species, lion genetic diversity is still considered high across all lion populations.

"With responsible management focused on giving prides enough space to breed and allowing males to move more freely between isolated pockets, it is possible to increase the genetic diversity and reduce population sub-division across lion populations."

There have been multiple reintroduction programs bringing lions back to areas where lions once roamed, and coexistence strategies are increasingly being integrated into wildlife conservation programs.

"The positive take-home message is now that we've documented this and we understand it, policies can be tailored to manage these populations differently," Derr said. "We know now that you can't treat all lions the same. Now we have the responsibility to manage these animals, and many other managed wildlife species, in ways that better reflects their current biology."

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cats; wild animals; evolutionary biology; biochemistry research; ecology; biodiversity; floods; el nino and la nina

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Lion genetics study uncovers major consequences of habitat fragmentation: Research shows how lions have developed genetically and how different populations were separated

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Over the course of only a century, humanity has made an observable impact on the genetic diversity of the lion population. That's the conclusion of a recently published study by Drs. Caitlin Curry and James Derr from the Texas A&M University College of Veterinary Medicine & Biomedical Sciences.

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you may look like your mom as a baby then look like your dad when you get older 

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you may look like your mom as a baby then look like your dad when you get older 

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https://www.parents.com/getting-pregnant/genetics/tests/baby-looks/

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Plants have chloroplasts, the organelle of photosynthesis, and are known as producers and autotrophs.

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Like Flu, COVID-19 May Turn Out to Be Seasonal...

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Like Flu, COVID-19 May Turn Out to Be Seasonal...

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Trees have DNA.

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https://www.sciencedaily.com/releases/2021/02/210204192528.htm

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healthy oceans need healthy soundscapes 

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https://www.sciencenewsforstudents.org/article/some-identical-twins-dont-have-identical-dna-genetics

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Add your Genetics Current Event title or link and a pic

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Add your Genetics Current Event title or link and a pic