Developed a genetic map of the structure of an entire organism from a single cell
One of the great mysteries of biology is how a single, fertilized egg gives rise to many types of cells, tissues and organs that fit together to form an entire organism. The researchers, through a combination of single cell sequencing technology and computational tools, have provided the most detailed picture of the process.
Regardless of whether the mowimy about a worm, a human or a blue whale, a lifetime of multicomorkowe begins as a single-cellorkowe egg. From this lone comorki emerges a whole host of others thatore are needed to build a complete organism. Each new comorka develops in the right place at the right time to perform a precise function in coordination with neighboring comorkami.
This is one of the most unusual processesoin nature and despite decades of research and prob to create a complete map of gene expressionow, understanding of the process has eluded scientists. Technological advances in DNA sequencing and algorithmoin computers made it possible to analyze the expression of thousands of genesoin a single comorce.
In the pages of the journal „Science” Three scientific articles have been published, in whichorych researchers describe their observations of gene activityow comorks in the embryos of a popular aquarium fish – striped danios – and in frog embryos. The goal was to draw a kind of roadmap, whichora shows howob a single comorka builds the entire organism.
The discoveries represent a catalog of genetic "recipes" for generating roThe type ofoin the comorek. Researchers from Harvard Medical School (HMS) and Harvard University have traced the fate of post-olnych comorek within the first 24 hours of embryonic lifeow. Their analyses reveal a process in whichorym genes are switched on or off, and the comoembryonic cells transition into new states and new types of.
– Thanks to the sequencing of single cellorek we can summarize in a single day decades of painstaking research into the decisions made by comorki at the earliest stages of life – said Allon Klein of HMS wspołautor dwoch of three studies published in „Science”. (first article, second article)
– In addition to shedding new light on the early stages of life, our work may open the door to a new understanding of many diseasesob – assessed Alexander Schier of Harvard University, coołautor of the third of the aforementioned publications. – Any complex biological process in whichorym comorki alter the expression of geneoin time, can be reconstructed using the approach we developed. Not only does developingoj embryosow, but even the development ofoj tumorow or chorob neurodegenerative mozgu– added.
Each comorc of the developing embryo carries a copy of the full genome of the organism. Like construction workers using when laying foundationsoin building the relevant part of the plan, the comorki must express the necessary genes at the right time for the embryo to develop properly.
The researchers analyzed this process in the striped danios and the African clawed frog. These are two of the best studied speciesoin the biology of. They took advantage of the technology of sequencing single comorek to capture gene expression dataow of each comorki of the embryo. In total, within 24 hours, the compositeoThe new instruments have profiled more than 200,000 comorek in rotion points in time.
To map the path of each comorks as the embryo develops, along with the exact sequence of gene expression eventsow, whichore mark new states and types of comorek, teams of scientistsoat commonoWorking together, they have developed new computational techniques, including the introduction of artificial codesoIn DNA barcodes to track relationships between comorkami.
The result of the work is something like comork family tree, whichore revealed how the expression of geneow w rospecific types of comorek during their specialization.
Tracking the development of embryonicow has allowed scientists to observe how cellsorki take on specialized roles, such as turning into nerve tissue or skohand. Sometimes the comorki, whichore seemed created for only one task, they took on other roles. – Comorki are more plastic than we might have thought – pointed out Schier.
Team discoveriesoreflect in the case of both speciesow much of what was previously known about the progression of germline developmentow. This gave the researchers confidence that they were going down the right path. But analyses made with new instruments have revealed in particularoThe cascade of events thatore move the cellsorks from early stateow "ogolnych" to more specialized ones with narrowly defined functions.
The researchers also identified other difficult-to-detect detailsos, such as rare types of comorec and their subtypes, and linked new and highly specific gene expression patternsoIn the z rowith new lines of comorkowe. In several cases, they discovered that types of comorek appeared much earlier than previously thought.
The result of this research could result in significant advances in many branches of medicine. In regenerative medicine, scientists have for decades aimed to manipulate the cellsostem cells toward determining their specifications to replace defective comorks, tissues or organs. The data collected during the study can helpoc accelerate the emergence of specific types ofoinorecords.
– If one wants to create a specific type of comorki, now has at its disposal a recipe, or rather mapped stages, whichore these comorki have undergone in the process of forming. In a sense, we have established a gold standard of behavior – explained Klein.
The results of the work show that the path from a single comork to the fully formed organism is much more dynamic than previously thought. A picture of the development thatory obtained by the researchers is smoother than that described in biology textbooks.
Now that techniques and algorithms have been developed, a number of scientists areow will use them by applying them to a wide range of creatures to track their developmentoj. – Understanding howob Evolution has modified the dynamics of gene expressionoin development to create each new type of cellorek and organ, will be fascinating – stated Klein.
– We can now reconstruct the trajectory of almost all comorek and all genow during embryogenesis. It’s almost like going from seeing a few stars to seeing the entire Universe – said Schier.
SourceoSource: Nature, Science Daily, Science, fot. Sean Megason/Harvard Medical School