Oh Yeah, Developmental Biology!

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Aug 1

paleontologue:

In 1905, E. G. Conklin published a remarkable fate map of the ascidian embryo. He showed that “all the principle organs of the larva in their definitive positions and proportions are here marked out in the 2-cell stage by distinct kinds of protoplasm.” This study of cell lineage has been the basis for all subsequent research on the autonomous specification of tunicates. The color plates of this study are considered to be some of the best examples of embryological illustration and descriptive anatomy.

scienceyoucanlove:

CALICO DOG MAY BE A CHIMERA

A photograph of a dog at a veterinary hospital has gone viral this week because of the animal’s unusual but beautiful markings. The Labrador Retriever, Bull, has a coat colored like that of a calico cat. He is a patient at Texas A&M Veterinary Medical Teaching Hospital, according to MSN Now.

Because of Bull’s unique coat, he is suspected of being a chimera, a single animal that genetically is two animals, i.e., an individual that is its own twin. Bull, then, appears to be a chimera that is both black Lab and yellow Lab.

We saw this phenomenon last summer when a "two-faced" calico chimera cat named Venus caught the Internet’s attention. Bull has emerged as Venus’ canine counterpart, albeit without the same dead-even color split down the middle of his face.

Whether Bull is a chimera hasn’t been confirmed medically yet, but we’ll watch the veterinary hospital’s Facebook page to see if they post any further information and, hopefully, more photos of this interesting dog.

source


What is a chimera?

A chimera is typically formed from four parent cells (either two fertilized eggs, or two early embryos that have fused together).When the organism forms, the cells that had already begun to develop in the separate embryos keep their original phenotypes and appearances — resulting in a two-faced cat like Venus. (see second picture)

It can happen to humans too. In 1953 a human chimera was reported in the British Medical Journal. A woman was found to have blood containing two different blood types that apparently resulted from cells from her twin brother living in her body. Other such instances have been reported in the decade since.

source

Heart, heal thyself! No problem, says the zebrafish

(Image: BHF/Dr Jana Koth)image

The future of regenerative medicine is bright: in this case, literally. This image of a stained zebrafish heart glowing with multiple colours is one of the winners of the British Heart Foundation’s annual heart and blood vessel photography competition.

The green staining of the two-day-old heart highlights the cardiomyocytes, the cells of the heart muscle itself. The red and blue-stained areas represent the contractile apparatus, the muscles that keep the heart beating strong.

Zebrafish are useful experimental animals: their genome has been fully sequenced, their bodies are transparent, and their developing embryos are fairly robust. Even more impressively, their hearts have the ability to regenerate after damage. Zebrafish can lose up to 20 per cent of their heart muscle without long-term consequences, as they can repair the damage completely within eight weeks.

Adult mammals lack this superpower. Although some newborn mammals can regenerate damaged heart tissue, this ability vanishes as they mature. During a heart attack, heart muscle cells are deprived of oxygen and they die, leaving scar tissue. “Understanding how zebrafish regenerate [their heart] may one day help victims of heart attacks recover,” says Jana Koth of the BHF Centre of Research Excellence at Oxford University , who took the photograph.

Dinosaurs, Fruit Flies, and Us

lcresearchcenter:

image

July 26th, 2013

There have been revolutionary advances in our knowledge of genetics in the past 30 years. This is particularly true in a field of endeavor called developmental genetics, which strives to understand how genes work to put us together. To make a baby that grows and eventually makes its own babies.

We have found that genes which coordinate development in the fruit fly are similar in structure, function, expression, and genomic organization to genes in human beings (i.e., how they are arranged on chromosomes, what regulates them and how they interact with each other). Yet fruit flies are not like us: among other obvious differences they have wings and we don’t (even if we wish we did!).

The formation of wings or legs or a segmented abdomen or hundreds of other steps are all part of a genetically specified developmental program leading to a body plan, a process which is called pattern formation. The revolution in part is the understanding of the degree of conservation of the genes responsible across huge phylogenetic chasms. In other words the degree to which the genes are the same even though we evolved into different animals almost a hundred million years ago.

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neurosciencestuff:

A new weapon against stroke
UC Davis stem cell study uncovers the brain-protective powers of astrocytes
One of regenerative medicine’s greatest goals is to develop new treatments for stroke. So far, stem cell research for the disease has focused on developing therapeutic neurons — the primary movers of electrical impulses in the brain — to repair tissue damaged when oxygen to the brain is limited by a blood clot or break in a vessel. New UC Davis research, however, shows that other cells may be better suited for the task.
Published today in the journal Nature Communications, the large, collaborative study found that astrocytes — neural cells that transport key nutrients and form the blood-brain barrier — can protect brain tissue and reduce disability due to stroke and other ischemic brain disorders.
“Astrocytes are often considered just ‘housekeeping’ cells because of their supportive roles to neurons, but they’re actually much more sophisticated,” said Wenbin Deng, associate professor of biochemistry and molecular medicine at UC Davis and senior author of the study. “They are critical to several brain functions and are believed to protect neurons from injury and death. They are not excitable cells like neurons and are easier to harness. We wanted to explore their potential in treating neurological disorders, beginning with stroke.”
Deng added that the therapeutic potential of astrocytes has not been investigated in this context, since making them at the purity levels necessary for stem cell therapies is challenging. In addition, the specific types of astrocytes linked with protecting and repairing brain injuries were not well understood.
The team began by using a transcription factor (a protein that turns on genes) known as Olig2 to differentiate human embryonic stem cells into astrocytes. This approach generated a previously undiscovered type of astrocyte called Olig2PC-Astros. More importantly, it produced those astrocytes at almost 100 percent purity.
The researchers then compared the effects of Olig2PC-Astros, another type of astrocyte called NPC-Astros and no treatment whatsoever on three groups of rats with ischemic brain injuries. The rats transplanted with Olig2PC-Astros experienced superior neuroprotection together with higher levels of brain-derived neurotrophic factor (BDNF), a protein associated with nerve growth and survival.  The rats transplanted with NPC-Astros or that received no treatment showed much higher levels of neuronal loss.
To determine whether the astrocytes impacted behavior, the researchers used a water maze to measure the rats’ learning and memory. In the maze, the rats were required to use memory rather than vision to reach a destination. When tested 14 days after transplantation, the rats receiving Olig2PC-Astros navigated the maze in significantly less time than the rats that received NPC-Astros or no treatment.
The investigators used cell culture experiments to determine whether the astrocytes could protect neurons from oxidative stress, which plays a significant role in brain injury following stroke. They exposed neurons co-cultured with both types of astrocytes to hydrogen peroxide to replicate oxidative stress. They found that, while both types of astrocytes provided protection, the Olig2PC-Astros had greater antioxidant effects. Further investigation showed that the Olig2PC-Astros had higher levels of the protein Nrf2, which increased antioxidant activity in the mouse neurons.
“We were surprised and delighted to find that the Olig2PC-Astros protected neurons from oxidative stress in addition to rebuilding the neural circuits that improved learning and memory,” said Deng.
The investigators also investigated the genetic qualities of the newly identified astrocytes. Global microarray studies showed they were genetically similar to the standard NPC-Astros. The Olig2PC-Astros, however, expressed more genes (such as BDNF and vasoactive endothelial growth factor, or VEGF) associated with neuroprotection. Many of these genes help regulate the formation and function of synapses, which carry signals between neurons.
Additional experiments showed that both the Olig2PC-Astros and NPC-Astros accelerated synapse development in mouse neurons. The Olig2PC-Astros, however, had significantly greater protective effects over the NPC-Astros.
In addition to being therapeutically helpful, the Olig2PC-Astros showed no tumor formation, remained in brain areas where they were transplanted and did not differentiate into other cell types, such as neurons.
“Dr. Deng’s team has shown that this new method for deriving astrocytes from embryonic stem cells creates a cell population that is more pure and functionally superior to the standard method for astrocyte derivation,” said Jan Nolta, director of the UC Davis Institute for Regenerative Cures. “The functional improvement seen in the brain injury models is impressive, as are the higher levels of BDNF. I will be excited to see this work extended to other brain disease models such as Huntington’s disease and others, where it is known that BDNF has a positive effect.”
Deng added that the results could lead to stem cell treatments for many neurodegenerative diseases.
“By creating a highly purified population of astrocytes and showing both their therapeutic benefits and safety, we open up the possibility of using these cells to restore brain function for conditions such as Alzheimer’s disease, epilepsy, traumatic brain disorder, cerebral palsy and spinal cord injury,” said Deng.

neurosciencestuff:

A new weapon against stroke

UC Davis stem cell study uncovers the brain-protective powers of astrocytes

One of regenerative medicine’s greatest goals is to develop new treatments for stroke. So far, stem cell research for the disease has focused on developing therapeutic neurons — the primary movers of electrical impulses in the brain — to repair tissue damaged when oxygen to the brain is limited by a blood clot or break in a vessel. New UC Davis research, however, shows that other cells may be better suited for the task.

Published today in the journal Nature Communications, the large, collaborative study found that astrocytes — neural cells that transport key nutrients and form the blood-brain barrier — can protect brain tissue and reduce disability due to stroke and other ischemic brain disorders.

“Astrocytes are often considered just ‘housekeeping’ cells because of their supportive roles to neurons, but they’re actually much more sophisticated,” said Wenbin Deng, associate professor of biochemistry and molecular medicine at UC Davis and senior author of the study. “They are critical to several brain functions and are believed to protect neurons from injury and death. They are not excitable cells like neurons and are easier to harness. We wanted to explore their potential in treating neurological disorders, beginning with stroke.”

Deng added that the therapeutic potential of astrocytes has not been investigated in this context, since making them at the purity levels necessary for stem cell therapies is challenging. In addition, the specific types of astrocytes linked with protecting and repairing brain injuries were not well understood.

The team began by using a transcription factor (a protein that turns on genes) known as Olig2 to differentiate human embryonic stem cells into astrocytes. This approach generated a previously undiscovered type of astrocyte called Olig2PC-Astros. More importantly, it produced those astrocytes at almost 100 percent purity.

The researchers then compared the effects of Olig2PC-Astros, another type of astrocyte called NPC-Astros and no treatment whatsoever on three groups of rats with ischemic brain injuries. The rats transplanted with Olig2PC-Astros experienced superior neuroprotection together with higher levels of brain-derived neurotrophic factor (BDNF), a protein associated with nerve growth and survival.  The rats transplanted with NPC-Astros or that received no treatment showed much higher levels of neuronal loss.

To determine whether the astrocytes impacted behavior, the researchers used a water maze to measure the rats’ learning and memory. In the maze, the rats were required to use memory rather than vision to reach a destination. When tested 14 days after transplantation, the rats receiving Olig2PC-Astros navigated the maze in significantly less time than the rats that received NPC-Astros or no treatment.

The investigators used cell culture experiments to determine whether the astrocytes could protect neurons from oxidative stress, which plays a significant role in brain injury following stroke. They exposed neurons co-cultured with both types of astrocytes to hydrogen peroxide to replicate oxidative stress. They found that, while both types of astrocytes provided protection, the Olig2PC-Astros had greater antioxidant effects. Further investigation showed that the Olig2PC-Astros had higher levels of the protein Nrf2, which increased antioxidant activity in the mouse neurons.

“We were surprised and delighted to find that the Olig2PC-Astros protected neurons from oxidative stress in addition to rebuilding the neural circuits that improved learning and memory,” said Deng.

The investigators also investigated the genetic qualities of the newly identified astrocytes. Global microarray studies showed they were genetically similar to the standard NPC-Astros. The Olig2PC-Astros, however, expressed more genes (such as BDNF and vasoactive endothelial growth factor, or VEGF) associated with neuroprotection. Many of these genes help regulate the formation and function of synapses, which carry signals between neurons.

Additional experiments showed that both the Olig2PC-Astros and NPC-Astros accelerated synapse development in mouse neurons. The Olig2PC-Astros, however, had significantly greater protective effects over the NPC-Astros.

In addition to being therapeutically helpful, the Olig2PC-Astros showed no tumor formation, remained in brain areas where they were transplanted and did not differentiate into other cell types, such as neurons.

“Dr. Deng’s team has shown that this new method for deriving astrocytes from embryonic stem cells creates a cell population that is more pure and functionally superior to the standard method for astrocyte derivation,” said Jan Nolta, director of the UC Davis Institute for Regenerative Cures. “The functional improvement seen in the brain injury models is impressive, as are the higher levels of BDNF. I will be excited to see this work extended to other brain disease models such as Huntington’s disease and others, where it is known that BDNF has a positive effect.”

Deng added that the results could lead to stem cell treatments for many neurodegenerative diseases.

“By creating a highly purified population of astrocytes and showing both their therapeutic benefits and safety, we open up the possibility of using these cells to restore brain function for conditions such as Alzheimer’s disease, epilepsy, traumatic brain disorder, cerebral palsy and spinal cord injury,” said Deng.

Women in science: How can we plug the leaking pipeline? - 05 June 2013 - New Scientist

Baby dinos pumped their muscles inside the egg

currentsinbiology:


Sperm Replace the Germ

The physical location of many stem cell niches is difficult to identify, but in the Drosophila testis, the niche is easy to locate. At the tip of each testis is a cluster of nondividing cells called the hub (blue nuclei on left-hand side) with two populations of stem cells surrounding it: the male germline stem cells (green) give rise to interconnected spermatogonia, whereas the somatic cyst stem cells (bright red nuclei) produce cyst cells (faint red nuclei). The cyst cells envelope the germline cells throughout their differentiation and are analogous to Sertoli cells in mammals. Images such as this one have shown that clusters of interconnected spermatogonia can replace missing germline stem cells.
Image: A whole Drosophila testis is imaged with a laser scanning confocal microscope. A nuclear marker stains somatic cyst stem cells bright red, whereas it diminishes in their daughters. Germline stem cells and their progeny are marked green with a cortically localized GFP. DNA is blue. (Erika Matunis and Becca Sheng, Johns Hopkins University

currentsinbiology:

Sperm Replace the Germ

The physical location of many stem cell niches is difficult to identify, but in the Drosophila testis, the niche is easy to locate. At the tip of each testis is a cluster of nondividing cells called the hub (blue nuclei on left-hand side) with two populations of stem cells surrounding it: the male germline stem cells (green) give rise to interconnected spermatogonia, whereas the somatic cyst stem cells (bright red nuclei) produce cyst cells (faint red nuclei). The cyst cells envelope the germline cells throughout their differentiation and are analogous to Sertoli cells in mammals. Images such as this one have shown that clusters of interconnected spermatogonia can replace missing germline stem cells.

Image: A whole Drosophila testis is imaged with a laser scanning confocal microscope. A nuclear marker stains somatic cyst stem cells bright red, whereas it diminishes in their daughters. Germline stem cells and their progeny are marked green with a cortically localized GFP. DNA is blue. (Erika Matunis and Becca Sheng, Johns Hopkins University

heythereuniverse:

Mouse embryo, 10.5 days old | Alan Boyde

heythereuniverse:

Mouse embryo, 10.5 days old Alan Boyde

Jun 4

Lemon Shark: Sac to “Stem” 

Shown about halfway through its 12-month gestation period in a computer-generated illustration, a lemon shark—like a human embryo—is literally connected to its mother via an umbilical cord attached to a placenta. But it wasn’t always so.

Until about three months in the womb, baby sharks feed off a yolk sac. Once the embryo has depleted the yolk, the collapsed sac settles against the womb wall and shoots blood vessels into the wall, tapping into the mother’s circulatory system.

By the time the embryo is six months old (pictured), it has a sense of smell 10,000 times sharper than a human’s. This and other sensory adaptations—including electro-sensors that detect the faint voltage of other animals—will one day allow the shark to detect even a fin flick hundreds of feet away, according to the National Geographic documentary In the Womb: Extreme Animals.

From the National Geographic (US) and Channel 4 (UK) Documentary Animals in the womb.