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The National Institutes of Child Health and Human Development awarded Phase I and Phase II Small Business Innovative Research Grants to develop The Visible Embryo. Initally designed to evaluate the internet as a teaching tool for first year medical students, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than one million visitors each month.

Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development
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Home | Pregnancy Timeline | News Alerts |News Archive Oct 16, 2013

 

Making memories requires a two step process of making proteins at the RIGHT TIME and
from PRE-ASSEMBLED PROTEINS. This diagram of RNA translation represents
the second step which occurs at the nerve synapse.

Image Credit: Wikimedia





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Making memories has to be a speedy business

The brain is plastic - adapting to the hundreds of experiences in our daily lives by reorganizing pathways and making new connections between nerve cells. This requires that memories of new information and experiences are formed fast. So fast that the body has a special mechanism, unique to nerve cells, to enable that memories are made rapidly.

In a new study from The Montreal Neurological Institute and Hospital, The Neuro, McGill University with colleagues at the Université de Montréal, researchers have discovered that nerve cells have a special ‘pre-assembly’ technique to expedite the manufacture of proteins at nerve cell connections (synapses), enabling the brain to rapidly form memories and be plastic.

The research was published in Proceedings of the National Academy of Sciences (PNAS.org).


Making a memory requires the production of proteins at synapses. These proteins then change the strength of the connection or pathway.

In nerve cells the production process for memory proteins is already pre-assembled at the synapse but stalled, waiting for the proper signals to finish, which speeds up the entire process.

When it comes time to make the memory, the process is switched on, completed, and the protein is made in a flash.

This process is analogous to a pre-fab home that is assembled in advance and then quickly completed in the correct location at the correct time.


“It’s not only important to make proteins in the right place but, it’s also important not to make the protein when it’s the wrong time,” says Dr. Wayne Sossin, neuroscientist at The Neuro and senior investigator on the paper. “This is especially important with nerve cells in the brain, you only want the brain to make precise connections.

If this process is indiscriminate, it leads to neurological disease. This explanation for memory protein synthesis answers two problems:

1) how to make proteins only at the right time
2) how to make proteins as quickly as possible in order to tightly associate the synaptic change with an experience — which is to become a memory.


Making proteins from genetic material involves two major steps [a Nobel prize was awarded for the identification of the cell’s protein-making process].

Transcription: In the first step, the information in DNA that is stored and protected within the centre of the cell is copied to a messenger RNA (mRNA) – this copy is then moved to where it is needed in the cell.

Translation: In the second step,the mRNA is used as a template of genetic information and ‘read’ by little machines called ribosomes, which decode the mRNA sequence and stitch together the correct amino acids to form the protein.


Dr. Sossin’s group at The Neuro has discovered that mRNA travels to the synapse already attached to the ribosome, with the protein production process stopped just before completion of the product (at the elongation/termination step of translation, where amino acids are being assembled into protein). The ‘pre-assembly’ process then waits for synaptic signals before re-activating to produce a lot of proteins quickly in order to form a memory.

“Our results reveal a new mechanism underlying translation-dependent synaptic plasticity, which is dysregulated in neurodevelopmental and psychiatric pathologies [illness],” added Dr. Sossin. “Understanding the pathways involved may provide new therapeutic targets for neurodevelopmental disorders. “

Abstract
Some forms of synaptic plasticity require rapid, local activation of protein synthesis. Although this is thought to reflect recruitment of mRNAs to free ribosomes, this would limit the speed and magnitude of translational activation. Here we provide compelling in situ evidence supporting an alternative model in which synaptic mRNAs are transported as stably paused polyribosomes. Remarkably, we show that metabotropic glutamate receptor activation allows the synthesis of proteins that lead to a functional long-term depression phenotype even when translation initiation has been greatly reduced. Thus, neurons evolved a unique mechanism to swiftly translate synaptic mRNAs into functional protein upon synaptic signaling using stalled polyribosomes to bypass the rate-limiting step of translation initiation. Because dysregulated plasticity is implicated in neurodevelopmental and psychiatric disorders such as fragile X syndrome, this work uncovers a unique translational target for therapies.

The Neuro
The Montreal Neurological Institute and Hospital — The Neuro, is a unique academic medical centre dedicated to neuroscience. Founded in 1934 by the renowned Dr. Wilder Penfield, The Neuro is recognized internationally for integrating research, compassionate patient care and advanced training, all key to advances in science and medicine. The Neuro is a research and teaching institute of McGill University and forms the basis for the Neuroscience Mission of the McGill University Health Centre. Neuro researchers are world leaders in cellular and molecular neuroscience, brain imaging, cognitive neuroscience and the study and treatment of epilepsy, multiple sclerosis and neuromuscular disorders. For more information, visit theneuro.com.

Original press releas: http://www.mcgill.ca/channels/news/live-and-learn-making-memories-has-be-speedy-business-231072