Biological Complexity

Properties of plants

Carries out photosynthesis (reduces carbon), synapomorphy, selectively responds to the environment, high surface area to volume ratio, anchored to absorb water and nutrients from the soil

What is synapomorphy?

Defining characteristics or traits of an evolutionary group

How did neurologists discover lytico-bodig (ALS-PDC)?

They observed that many of the Chamorro people had a disease that resembled ALS, Parkinson’s Disease, and Alzheimer’s Disease. Highest rate of ALS-type disease on earth (1/4 adults)

What led scientists to believe that ALS-PDC wasn’t genetic?

If someone marries into a family, even from a different country, they sometimes get the disease

How did scientists explore the environmental factors that affected ALS-PDC onset?

Water tests showed low levels of aluminum in the water, tests showed calcium and magnesium were not deficient in soil, and disease is not transmitted from person to person.

What did scientists uncover about dietary factors relating to ALS-PDC?

Scientists isolated 2 neurotoxins from the cycad seeds that the Chamorro people eat. Many Chamorro people eat tortillas made from cycad flour.

What are cycads?

Seed plants, pollen-producing structures and ovule-producing structures on different plants, with no flowers. Cycads produce large seeds that are high in starch and contain toxins that have been known for 100 years.

What experiments did researchers conduct to determine the possibility of cycad seeds as a cause of ALS-PDC?

Seeds and flour were fed to laboratory animals; however, similar neurological disorders were not observed. The seeds were also analyzed and they found low concentrations of neurotoxins

Why were flying foxes (bats) investigated?

They eat cycad seeds, and the bats were eaten by the Chamorro people.

What did the researchers conclude about the cause of ALS-PDC?

The consumption of flying foxes in Guam drastically increases the chances of onset. Since men ate the whole flying fox more often than women, there is a higher incidence of ALS-PDC in men.

Why is there a delayed onset of symptoms in ALS-PDC?

Neurotoxin is bound up in proteins, and a neurotoxin is an amino acid analog. Protein degradation releases the toxin. Protein-associated BMAA was much higher than free BMAA in Chamorro people.

How was cyanobacteria involved in the neurotoxins?

Neurotoxin is produced in the roots; toxin synthesis is associated with cyanobacterial symbiont infection. Fix nitrogen for plants, gets sugars and amino acids in return, and makes a neurotoxin that becomes sequestered in the seeds