6: Biomagnetism (Lecture + Literature) Flashcards
Name the two ways in which lower organisms produce magnetic material
Magnetotactic bacteria, Iron-reducing bacteria
What is the biomagnetic link between lower and higher organisms?
Both use magnetism as a form of magneto-reception
What is magnetoreception?
The use of a magnetic mineral within the organism to determine direction of travel or location
What does BOM stand for?
Biologically organized mineralization
What does BIM stand for?
Biologically induced mineralization
What is the primary difference between BOM and BIM?
BOM is intracellular, BIM is extracellular
What are the three main mechanisms which appear to induce the creation of magnetic minerals in higher organisms?
Magneto-reception, Armor, Metabolic build-up – disease (?)
Name an example of an insect that carries magnetic minerals and the reason why (Authors)?
Monarch Butterfly – migratory so potentially use of magneto-reception (McFadden and Jones, 1985)
Name an example of a bird, with the type of grain (size and arrangement) carried, location of grains, reason for magnetic material, with (Authors).
Homing Pigeon, SP magnetite arranged in clusters on beak, used for magnetoreception (Holtkamp-Rotzler et al, 1997)
The increase in ____ in the brain appears to be strongly linked with ____. It can be detected using a ____, commonly known as an MRI.
Magnetite, neurodegenerative disorders, magnetic resonance imaging.
___ mollusks have an organ which acts as a ___ to scrape microorganisms off rocks. There are many little ___ on the ___ made from ___ crystals. The grains are used solely for their ____, not their ___ properties.
Chiton, tounge, teeth, radula, magnetite, hardness, magnetic
___ is found in Limpets
Goethite
What is elemental symbol of Greigite?
Fe3S4
What size (μm) magnetite grains have been found on many species of fish?
0.03 – 0.05 μm
In a study by (Authors) a rainbow trout was found to have ___ grains within a ___ cell on its head. It had coercivities between __ to __ mT, which is magnetically close to that of __ ___
Diebel et al, 2000, SD grains, magnetoreceptor, 20-40mT, bacterial magnetosomes
What is thought to be the link between nerve tissue and magnetic minerals?
Magnetite in membrane allows movement of tissue through osmosis
___ ___ are found to swim ___ and ___ in the NH and ___ and ___ in the SH. The actions in each hemisphere are due to the ___ magnetisation. It is thought that this action is used as ___ so as to keep the organism ____.
Magneto-tactic bacteria, northwards and downwards, southwards and downwards, opposite, magnetoreception, correct oxygen environment
Which (Authors) studied trout heads so as to understand the presence of magnetite grains?
Diabel et al, 2000
What was the location of the study by Snowball (1994)?
Swedish lake sediments
What was special about the location chosen by Snowball (1994)?
No external input of magnetic material
In the study by Snowball (1994), SIRM was found to be abnormally ___, at ____Am2kg-1, at a depth of ___cm.
High, 40Am2kg-1, 35cm
The study by Snowball (1994) used the ____ test to confirm the presence of ____ ____.
Oldfield, 1994, bacterial magnetosomes
What did Snowball (1994) find with depth, and what was the cause?
Decreasing fossil magnetosomes, due to dissolving by reductive diagenesis.
What was the location used by McNeill (1990)?
Great Bahama Bank
What was the test used by McNeill (1990), and what did it show?
Lowrie-Fuller test, positive for SD grains
What was the secondary line of evidence used by McNeill (1990) to show presence of bacterial magnetite?
Microscopic observation
What was the domain formation of the magnetite found by McNeill (1990)?
All SSD grains
What was found in microscopic observation which made McNeill (1990) believe that it was BOM?
SD grains arranged in a chain with progressively smaller grains near the end
Why does certain bacteria arrange itself into chains?
Magnetoreceptors
How can we tell the saturation point of BOM?
Apply larger and larger fields while maintaining a fast rotation around the bacteria – the magnetic field at which the bacteria can no longer keep up to the spin is the point at which it is saturated.
When are the earliest documented magneto-fossils from?
2.1bn a-1
Where and when was the Martian meteorite which contained magneto-fossils found?
Allen Hills, Antarctica, 1984
When did the Martian meteorite break off from Mars, and when did it make impact with Earth?
16mil years ago, 13,000 years ago
What would the presence of BOM magnetite in the Martian meteorite mean for planetary research?
Mars has a strong magnetic field and thus liquid conducting core?
Which (Authors) published on their magnetic findings in Swedish lake sediments?
Snowball (1994)
Which (Authors) published on their magnetic findings on the Great Bahama Bank?
McNeill (1990)
In Scotland, Snowball and Thompson (1988) found ___ produced by ____, (B__M). The grains acted as ___ grains, where ___ only plays a small role.
Greigite (Fe3S4), sulfate reducing bacteria (BIM), SD, SP.
Snowball (1991) found a high concentration of ____ in two lakes in Sweden, with grain sizes of ___ and ___. There was no ___ grains, which means there there was likely to be no BIM component.
Greigite (Fe3S4), SD and PSD, no SP
What is thought to be the possible origin of the banded iron formations, the source of ___% of iron mined today (And what geological age)?
Bacterial oxidation of ferrous iron, Precambrian oceans, 90%.
Hanesch and Petersen (1999) found what when they introduced a source of “food” to BIM?
An increase in susceptibility caused by BIM producing magnetite
Lovley et al (1987) found bacteria which produced a ____ which was found to be ___. Some of the grains larger than ___, as they could carry remanence
Black precipitate, magnetite, SP
Who were the (authors) which added “food” to BIM to increase susceptibility?
Hanesch and Petersen (1999)
Who were the (authors) whom observed a black precipitate of BIM magnetite in a river in Maryland?
Lovley et al (1987)
What do you plot for the Oldfield (1994) test, and what is it thought give?
Xarm/X against Xarm/Xfd thought to give specific groupings of SSD biological magnetite.
Which test do you plot Xarm/X against Xarm/Xfd to attain a grouping of SSD biological magnetite?
Oldfield (1994)
What was the major scrutiny with the Oldfield (1994) test when it was first published?
The biological magnetite was not tested using transmission electron microscopy to be sure.
