Author Archives: isabella correa

Horseshoe crabs save lives and we must think about saving theirs

You may no know much about horseshoe crabs, but these ancient animals have saved your life multiple times with their peculiar blue blood. However, we need to take better care for these alien-like creatures.

File:Limulus polyphemus.jpg

Horseshoe crabs painted

 

Horseshoe crabs have an immensely efficient immune system that is not well understood and much less reproducible. It does not involve antibodies, the immune cells in the animal can detect bacterial toxins to the part per trillion and release a poorly understood substance, limulus amoebocyte lysate (LAL), that traps pathogens in a gel-like substance. No other known method can detect and destroy pathogens with such efficiency.

We started using horseshoe crab blood for medical sterilization in the 1970s when it replaced the rabbit pyrogen test; injecting a sterilized medication into a healthy rabbit and correlating the increase in its body temperature to the amount of bacterial toxin. Since then, the blue blood became indispensable to modern medicine. The LAL test is used for every injectable medicine the regulated market to determine its safety and in the sterilization of surgical equipment. It is also widely used in medical research for sterilizing and to maintain safety when studying dangerous bacteria. The blue blood of these animals has been estimated to cost 15000 U$ dollars per litre.  

“A still from the PBS Nature documentary Crash PBS” – The Atlantic (2014) – documentary linked in the article

Only a few organizations in the world can harvest horseshoe crab blood. They capture 600000 specimens per year, bleed out 30% of their blood volume and return them to the sea after a recovery period; the whole process last about 48-hours. The mortality rate of the bleeding process is low but problems along the way are endangering this 450-million-year-old species.

The amount of blood and specimens the authorized organizations can harvest is not regulated and some have been known to sell the crabs as bait or let them die. Furthermore, the bleeding process has long term effects on the animals, they become slower, weaker and less likely to mate after bleed. Their habitat is also at risk and overall populations seem to be decreasing. Meanwhile, not much literature is published to try to replicate or understand LAL.

In other words, we need to become aware that horseshoe crab populations are important for us. A few recent research projects try to find ways to improve the harvesting and conservation processes as well as LAL research. But progress is slow, plus funding and regulation need to follow these efforts. Well now you know that a peculiar 450-million-year old species has helped you live without giving much thought to a lot of infections, so spread the word and if you ever find yourself supporting research or environmental regulation please have these fellows in mind.

-Isabella Correa

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Lignin: using the whole plant

 Lignin is one of the most abundant materials on Earth but it is still painfully difficult to work with. Lignin is the name we give to a group of polymers that make plants stiff and somewhat waterproof. It is made of many aromatic groups that could be useful but its structure is so unpredictable that it ends up being an obstacle in processes like biofuel synthesis.

Location of lignin in a primitive plant: Sleaginella
National Science Foundation https://nsf.gov/news/mmg/mmg_disp.jsp?med_id=62375&f

So, the problem with lignin is that we don’t know how it will break down until it has been broken down. Many studies have tried and failed to use oxidation-reduction reactions and electrochemical processes to break lignin down into useful components. The processes are long, complicated, dependant on high temperatures and nothing seems to work well enough.

Researchers at the University of Michigan  published a paper for a one pot, room temperature method to break down lignin. To do so they combined electricity and a relatively common compound for catalysis NHPI. The advantage of this approach is they knew how the NHPI would react with a C-O bond in the pine lignin they studied. The known process told them how the reaction would start and what to expect if it worked. This catalyst is also cheaper than metal catalysts.

Then, they needed to keep the reaction going to prevent a small amount of lignin pieces from reattaching to the larger pieces. To do this, they tested many solvents and used known electrochemical conditions until they found evidence of lignin monomers and dimers (pieces of one or two molecules broken from the lignin polymer).

Polymer-dimer-monomer relation
http://www.webassign.net/question_assets/wertzcams3/ch_13/manual.html

However, all this work was done with very small amounts of material. To make the reaction work at a larger scale they used a modern technique called photocatalysis.

An example of a photocatalysis reaction
https://www.hindawi.com/journals/jnm/2012/624520/fig2/

The team found that lignin was also breaking down at the larger scale and the yield was pretty good for a lignin experiment. The study showed a hopeful future for lignin research and application as well as for electrochemistry and photocatalysis processes.

Isabella Correa

Gongronella cleanse

A cruel side of independence is mold; we barely remembered it existed and now it’s in places we didn’t even know we had to clean.  But fungi can also clean what we leave lying around. This is an underrated story about fungi and how they can restore ecosystems in former mines.

Mineral exploitation leaves many problems behind. These places suffer from soil alkalinity and are deficient in minerals that support life. They are “inhospitable environment with huge loss of soil and water, vegetation recession, rock bareness, and productivity loss” as reads the research article by Yawen Wu and others about the fungal strain Gongronella sp (of the Cunninghamellaceae family of fungi) and its role in restoring soil and life after rock mining.

But how can fungi solve this problem? The team researched how fungi could improve the process of external-soil spray seeding. The technique consists in spraying plant nutrients and seeds to restore vegetation. However, it tends to fail because the soil layers in abandoned mines are very thin; this is where the Gongronella comes in.

The fungi can, in theory, do two things the spray can’t: degrade rocks to make the soil lining thicker and release organic material from as deep as 12mm from the surface.

To undestand this, we need to think about how some fungi eat and grow. Some fungi grow in net-like structures called mycelia which are composed of structures called hyphae. These fungal ramifications grow towards food sources and mold to them, so they can access creases and shapes of the mine rocks. The fungus eats by digesting whatever materials it finds around the hyphae and absorbing some of it so some of the digested organic material would remain available in the mine’s ground.

Parrts of a fungus (https://moodle.clsd.k12.pa.us/district_videos/Biology/iText/products/0-13-115540-7/ch21/ch21_s1_2.html)

Fungi secrets enzymes that digest compounds neat it and then uptakes the digestted products (http://www.biologymad.com/master.html?http://www.biologymad.com/digestion/digestion.htm)

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The team isolated Gongronella sp fungi from a rock mine and cultured them in the presence of rock samples. They used analytical chemistry techniques to monitor the presence of organic acids, monitored the pH as the cultures grew, measured the general loss of mass in the rocks and tracked the appearance of minerals that are necessary for plant growth like Mg2+ and Ca2+.

As expected, the team found a decrease in pH and increase in Ca and Mg from the rocks as the fungi grew. The rocks degraded into small soil particles very quickly and they observed how the mycelium helped these results happen. Furthermore, the organic acids (citric acid, succinic acid and others) that resulted from the fungi digesting the rocks have the advantage for plant life too. They provide grounds for coordination complexes which are widely used by plants and much better compared to the inorganic acids that would result from neutralizing the mine’s pH with industrial inorganic chemicals.

The Gongronella seems to be mostly useful in rocky mines but other fungal strains like Penicillium or Mucor have been found useful for metal mines. As much as we hate mold in bread, fungi prove to be fascinating and may really have our back someday, so stay weird fungi and thank you.

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-Isabella Correa

The Gongronella cleanse

A cruel side of independence is mold; there’s no sugar-coating it, we barely remembered it existed and now it’s in places we didn’t even know needed cleaning.  But fungi can also clean what we leave lying around, not bathrooms or kitchens but the places where they come from. This is an underrated story about fungi and how they can restore ecosystems in former mines, cleaning the mess of our lifestyle.

Mineral exploitation leaves many problems in site. Soil alkalinity and deficiencies in minerals of importance for life make these areas an “inhospitable environment with huge loss of soil and water, vegetation recession, rock bareness, and productivity loss” as reads the research article by Yawen Wu and others about the fungal strain Gongronella sp (of the Cunninghamellaceae family of fungi) and its role in restoring life after rock mining.

But how can fungi solve such a complex problem? The team researched ways in which the fungi could aid a process known as external-soil spray seeding. The technique consists in spraying plant nutrients and seeds to restore vegetation. However, it tends to fail because the soil layers being too thin; this is where the Gongronella comes in.

The fungi can, in theory, do two things the spray can’t: degrade rocks to make the soil lining thicker and mold to the rocks to degrade them and release organic material from as deep as 12mm from the surface. This all because of their mycelia structure in which the fungus extends in ramifications towards their food source and can secrete chemicals from the tips or hyphae. These hyphae can also grow into the rock cracks and deepen decomposition.

Credit: Benjamin Cummings

To bring these characteristics into use, the team used the Gongronella sp fungi they isolated from a rock mine and cultured them in the presence of rock samples. They used high performance liquid chromatography to monitor the presence of organic acids, monitored the pH as the cultures grew, tracked the appearance of Mg2+ and Ca2+ from their solid state and monitored the general erosion of the rocks into soil.

As expected, the team found a decrease in pH and increase in Ca and Mg from the rocks as the fungi grew. The erosion rate was significantly faster and into very small particles, they observed how the mycelium structure helped this process. Furthermore, the organic acids (citric acid, succinic acid and others) secreted from the fungi have the advantage of providing grounds for coordination complexes which are more useful to life form remediation than the minerals obtained with inorganic acid remediation.

The Gongronella seems to be mostly useful in rocky mines but other fungal strains like Penicillium or Mucor have been found useful for metal mines. We will always hate mold in old bread, but fungi prove to be more fascinating than we tend to give them credit for and they may really have our back someday so stay weird fungi and thank you.

-Isabella Correa