Monday 22 May 2017

Mary Anning's Fossils and the Cliffs at Lyme Regis

Mary Anning was a nineteenth century fossil collector and paleontologist who made important contributions to science. The fossils came from the Jurassic period and were obtained from the cliffs and beaches of Lyme Regis in England. The cliffs were once part of the seabed. Even today they contain a rich source of fossils.

Mary developed an impressive knowledge of local life in the Jurassic. Though she eventually became respected by geologists, she didn't receive as much attention as she deserved. She lived at a time when science was predominantly the domain of males. She also came from a poor family and had little social standing, which further hindered the attention that she received from the scientific community.




Mary Anning
 Unknown artist (created before 1842)
Public domain license


Mary Anning's Life


Mary was born in 1799. Her father died when she was only eleven, leaving his family in debt. Fortunately, he was a keen fossil hunter and had passed on his skills to his family. The family was short of money but were able to survive by collecting and selling fossils. The fossils became more than just a means of survival for Mary. She studied, analyzed, and documented her discoveries, moving out of the realm of being only a collector and into the realm of paleontology.


Mary's fossils were sent to scientists, museums, and private collections, but often the fact that she had discovered a particular fossil was omitted or forgotten. In addition, scientists sometimes presented her discoveries to an audience without acknowledging that Mary had found and prepared the fossil.


Life was often financially difficult for Mary, but there were times when she was better off than others. In 1817 a wealthy fossil collector became a supporter of the Anning family. He sold his own fossil collection and gave the proceeds to the family. He was also careful to attribute their discoveries to them. This helped to publicize the family's activities as well as to aid them financially, at least for a while. As her life progressed, Mary's fortunes rose when a commercially desirable fossil had recently been found and fell when there was a prolonged gap between significant discoveries.




An ichthyosaur skeleton
Photo by Adam Dingley
CC BY-SA 3.0 License


Later Life


Mary eventually become recognized as a dedicated and careful fossil collector by scientists. In 1838 she received an annuity from the British Association for the Advancement of Science. In addition, she received a stipend from the Geological Society of London. These regular sums of money were probably very helpful for her. Unfortunately, Mary died from breast cancer in 1847 while she was still relatively young. The Quarterly Journal of the Geological Society published her obituary. The society didn't admit women until 1904.



Lyme Regis


Lyme Regis is a town on the southern coast of England. Its coastline forms part of a World Heritage Site. The cliffs and the beach beside them are a rich source of fossils. Even 170 years after Mary's death, people successfully hunt for fossils in the area. The cliffs are eroding rapidly, a process that continually adds new fossils to the beach. It also means that visitors need to be careful that they don't get hit by falling pieces of rock.


There are two versions of the painting of Mary Anning shown above. The one that I've included is reportedly the earlier one. The second version is similar but not identical and is said to be a copy of the first one. It's important to note that using a pick to hammer the unstable cliffs as Mary apparently did at Lyme Regis is dangerous. She nearly died in a landslide that killed her dog, though I don't know the immediate cause of this event.




A cast of a plesiosaur
Photo by Adrian Pingstone
Public domain license



Mary's Discoveries


The Jurassic period lasted from approximately 199.6 million years ago (mya) to 145.6 mya. Mary found many fossils from this time period. The first major discovery happened when she was only a child. When she was twelve, her brother Joseph found the skull of an ichthyosaur. A few months later Mary found the rest of the animal. This was the first complete ichthyosaur skeleton to be discovered. Ichthyosaurs were marine reptiles that had a fish-shaped body.


Mary was also the first person to discover a complete (or almost complete) plesiosaur skeleton. Plesiosaurs were marine reptiles with a long neck, a small head, and flippers. Another important discovery was a skeleton of Pterodactylus macronyx, which is now known as Dimorphodon. The animal was a type of pterosaur. Pterosaurs were flying reptiles with wings. Mary also found other interesting and often significant items, including fossilized ink sacs that resembled those of today's octopuses and squid.


The discovery of coprolites demonstrates how Mary's work helped scientists. She noticed that coprolites—or bezoar stones as they were known then—were often found in the abdominal region of ichthyosaur specimens. She also noticed that the stones contained fossilized bones of fish and other creatures. Based on these facts, a geologist named William Buckland proposed (correctly) that the stones were fossilized feces.


The interest in Mary Anning's work has been revived in recent times, and rightly so, I think. Her discoveries were important in their own right and also enabled scientists to discover more about life in the Jurassic period.



References 


Mary Anning biography from the San Diego Supercomputer Center website (which includes biographies of female scientists)


The Three Mary Annings from the University of Waterloo


Information from UCMP (University of California Museum of Paleontology)

Tuesday 16 May 2017

A Biodegradable Sanitary Pad Based on a Seaweed Ingredient

The disposal of sanitary pads (or napkins) and related products creates a big environmental problem that needs to be solved. Women need some kind of protection during menstruation. A sanitary pad is a popular choice, but unfortunately most brands are not biodegradable and collect in the environment as waste after use. Researchers at the University of Utah have created a new pad which they say is effective, comfortable, and safe for the environment. It relies on a substance from brown algae or brown seaweed for its ability to absorb liquids.



`
Brown Algae in Norway
Photo by Ximonic, CC BY-SA 4.0

Each year, nearly 20 billion sanitary pads, tampons and applicators are dumped into North American landfills. (Quotation Source: University of Utah News Release)

Biodegradable Products


Biodegradable products would seem to be a solution for the environmental problems cause by discarded sanitary pads. There are problems with at least some of these products, however. Complaints include the fact that they don't absorb enough fluid, don't fit properly, or are uncomfortable. The researchers at the University of Utah have created what they believe is a "better sustainable sanitary pad".


                            Candida albicans growing on agar in a yeast form
                                            and in a filamentous form.
                                       Photo by Garnhami, CC BY-SA 4.0

The SHERO Pad 


The University of Utah researchers say that their product is thinner than other biodegradable pads. It's known as a SHERO pad and is composed of four layers. The outer layer is made of the same material as tea bags. Below this is a cotton layer that helps to absorb liquid. Next is a highly absorbent substance called agarose, which is obtained from brown algae. The last layer of the pad is made from corn and serves as a moisture barrier.

Agarose is a polymer and a polysaccharide that is obtained from the agar in seaweed. Polymers are long molecules made of repeating subunits. In a polysaccharide, the subunits are sugar molecules. In biology, the word "sugar" refers to a family of chemicals instead of just sucrose, or table sugar. 


Agar (sometimes known as agar-agar) is a substance obtained from certain algae that forms a gel when added to water. It's often supplied to the public in a dried form as a powder or flakes. When water is added to the dried agar, the gel is produced. Agar is used as a vegetarian substitute for gelatin. It's also a common substrate for bacteria in the petri dishes used in biology and medical labs. Agarose is one of the chemicals in agar that is responsible for its ability to form gels.


The inventors of the new pad say that once discarded it will break down within forty-five days to six months. The difference in time presumably depends on the environmental conditions. The pads are said to be completely degradable, unlike some pads that claim to be so. 
The average woman will menstruate for about four decades and use an estimated 16,800 sanitary pads or tampons in the process — that’s 250 to 300 pounds of waste. In the U.S. alone, some 12 billion pads and 7 billion tampons are disposed of annually. (Quotation Source: grist.org)

Creating and Selling the Pad


The SHERO pad was created for women in developing countries, especially those in Guatemala. In fact, its creation was stimulated by a request from a Guatemalan advocacy group for women and children. Safe drinking water and public sanitation are sometimes unavailable in the country, especially in rural areas. Discarded sanitary napkins add to the pollution burden.

The researchers have launched a startup company and hope to have the product available in Guatemala and for sale in the United States within a year. They also say that it may be possible for communities in some parts of Guatemala to produce the pads themselves from local materials, as long as they have a grinding stone and a press. It will be interesting to see how practical this process is. It will also be interesting to see if the pads are as effective and as biodegradable as the researchers believe.



Reference

University of Utah News Report 

Saturday 6 May 2017

Maintaining and Controlling the Blood-Brain Barrier

The blood-brain barrier, or BBB, is a layer of cells that stops specific substances in the blood from entering brain tissue. This is an essential job, since the brain controls our body and keeps us alive. It must be protected from harmful materials. Sometimes, though, researchers are frustrated when a medication that could help a neurological problem is unable to enter the brain due to the presence of the BBB. Understanding how the barrier works and learning how to safely modify its actions are important endeavours.



Salmon contains DHA, which helps to keep the
blood-brain barrier strong. (Public domain photo)


The Blood-Brain Barrier


The blood-brain barrier consists of tightly packed endothelial cells that line the capillaries around and inside the brain. The membranes of adjacent cells in the barrier are joined by so-called "tight junctions", which block the passage of virtually all materials. Materials are forced to travel through the cells in the barrier in order to enter the brain tissue. This enables the cells to have some control over the passage of the materials.


The blood-brain barrier does allow some substances to enter the brain, including nutrients such as oxygen, glucose, amino acids, and water. Brain cells need these chemicals in order to survive. Lipid-soluble substances can also pass through the barrier. Bacteria, other pathogens, and substances that could act as neurotoxins are blocked, however.



Role of an Omega-3 Fatty Acid


Researchers at the Harvard Medical School have recently explored the role of a specific type of omega-3 fatty acid in the blood-brain barrier. Their research has shown that the chemical is important for maintaining the integrity of the BBB and enabling it to block the movement of substances. The fatty acid in question is docosahexaenoic acid, or DHA. It's found in oily fish and certain algae. The researchers have found that the endothelial cells in brain capillaries have two to five times more DHA than the ones in lung capillaries.


The blood-brain barrier protects the brain. 
(Public domain photo)


A Transporter Protein


The endothelial cells lining blood vessels around and in the brain contain a protein known as Mfsd2a. This protein transports lipids, or fatty materials, including ones containing DHA. It moves the lipids with DHA into the membrane of the endothelial cells, which keeps the BBB strong. 

The protein also inhibits transcytosis in the cells. This is a process in which a substance enters a cell via vesicle formation (endocytosis), moves to the opposite membrane of the cell, and then leaves the cell in another vesicle (exocytosis). A vesicle is a small, membranous sac. The cell has other ways to transport materials, but some substances must move through the cell by transcytosis.


The Harvard researchers have bred mice with a mutated form of the gene that codes for the Mfsd2a protein. The mutation in the gene causes an altered protein to be produced. The altered protein can no longer transport lipids containing DHA. As a result, the mice develop "leaky" blood-brain barriers which allow the passage of materials that are normally blocked. In addition, the formation of the vesicles needed in transcytosis is no longer inhibited, which also increases the passage of materials. The same results occur when mice lack the Mfsd2a protein entirely.



Human Applications


Assuming that the process discovered in mice works the same way in humans, it might be useful to us. If we could temporarily block the activity of the Mfsd2a protein, we might be able to send medications for treating Alzheimer's disease, brain cancer, strokes, and other conditions into the brain. The problem is that we need to do this without allowing harmful substances into the brain, or at least while limiting their entry. Hopefully we will discover how to do this as we learn more about how the blood-brain barrier works.


Research Reference


Role of omega-3 fatty acids in keeping the blood-brain barrier closed