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Kayla Sassaman
Professor Becker
Biology 303-001
April 30, 2023
Annotated Bibliography
The capability of tardigrades’ survival in harmful environments.
Boothby TC et al. 2017 Tardigrades Use Intrinsically Disordered Proteins to Survive
Desiccation. Molecular cell : doi:10.1016/j.molcelvol. 65,6
a. The hypothesis in this article was that the tardigrade-specific intrinsically disordered
proteins (TDPs) or expressed at different levels depending on the environment around
them. The more an area is lacking moisture the more the TDPs are expressed.
b. This theory was examined by sequencing the dehydration and rehydration of
transcriptomes at different desiccation tolerance levels. As these tests are performed
slowly moisture is removed from the environment to determine a survival pattern of the
tardigrade. It is discovered that pre-conditions are necessary to ensure increased
maximum survival. For example, this study follows the species M. tardigradum, which
concludes that specific tardigrades require specific pre-conditions for survival in extreme
conditions. It is discovered once the desiccation process begins instead of TDPs being
upper regulated it is shown that the cytosolic abundant heat soluble (CAHS) is upper
United 4 to 20 times during desiccation relative conditions. Another test that was run
during the study was whether TDPs are a good protectant during the desiccation of
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bacteria and yeast engineered to up-regulate with CAHS proteins. Results show that
using the TDPs in this study allowed the yeast to increase its protection via CAHS
proteins by almost 100-fold and the bacteria tested doubled in magnitude. It was also
seen that another form of self-preservation that the tardigrades have adapted to use is the
vitrification of biological matter. This occurs when the trehalose forms a glass-like matrix
in the cells, ultimately preventing protein aggregation, protein denaturation, and
membrane fusion during desiccation. With these biological defenses that the tardigrades
have adapted to it is safe to say they play a role in the species’ ability to withstand
extreme living conditions.
c. With the extensive research done, I believe they have uncovered significant evidence of
how tardigrades are capable of withstanding extreme conditions.
d. This article was very suitable for my topic because it examined key factors on how
tardigrades can withstand harsh conditions on a biological level.
e. The research provided helped determine what proteins in the tardigrades allow them to
withstand severe conditions. Other research can be done to dive deep into a more
intensive biological study of tardigrades to fully understand cryptobiotic organisms and
what molecules and proteins help protect and potentially stabilize sensitive biological
material.
Fukuda Y, Kim J, Inoue T. 2020 "Structure of cytochrome b unique to tardigrades."
5Protein
science: a publication of the Protein Society vol. 29,8: 1829-1835
a. In this article, it is hypothesized that specific structural characteristics of a
cytochrome protein in a desiccation-tolerant species of tardigrade, b5-like Ramazzotius
varieornatus.
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b. This data was collected via amino acid sequencing of resulting in only a 30~36%Rv bCyt 5
match to typical cytochrome b (Cyt ). Certain tardigrades with Cytb5-like proteins like
5b5
the ones studied in this article lack the C-terminal transmembrane helix, this membrane
serves as an anchor to the mitochondrial membrane, which in turn makes the proteins
soluble. Some Cyt proteins in specific tardigrades have key components that are b5
distinguishable from other species. This is the insertion of amino acid residues that have
been aptly named the tardigrade-specific loops (TS loop). It has been examined that the
closely related tardigrade ( ) and Hypsibius exemplars He bCyt 5Ramazzotius varieornatus
(Rv bCyt 5) have different lengths of the TS loop. This is a result of the TS loops
containing Ser, Gly, and Pro residues, these amino acids leave residues on the loop which
then form disordered regions. When looking at the Cyt proteins at a resolution of 1.4 Å b5
by a single wavelength anomalous dispersion method it is seen to have a crystal structure.
When looking closer at this structure it was seen that the is made up of five β Rv bCyt 5
strands and five α-helices. When comparing the differences between and any Rv bCyt 5
ordinary Cyt proteins is the presence of the TS loop between β3 and β4. These b5
structures observed it is expected that the tardigrade proteins unlike typical Rv bCyt 5
Cytb5 are involved in certain parts of the electric transport chain.
c. Based on the analysis of the done in this article relates to my topic very well in Rv bCyt 5
the sense that it shows the structure of the specific protein that protects the tardigrades
from harsh environments.
d. The TS loops are linked to the tardigrades’ tolerance to desiccation.
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e. Potential angles of new research can be the relationship between the electron transport
chain of tardigrades and that of other animals. Because this field of research is so new
there are many ways to expand on this research.
Kletetschka G, Jolana H. 2015 Dissolved Gases and Ice Fracturing During the Freezing of a
Multicellular Organism: Lessons from Tardigrades. BioResearch open access vol. 4,1 209-
17: doi:10.1089/biores.2015.0008.
a. The purpose behind the experiments executed in this article is to observe the
cryopreservation of multicellular organisms, such as tardigrades, as well as to discuss the
analogy for cryopreservation of larger organs.
b. Tardigrades have the capability of almost fully stopping all bioprocesses, going into a tun
state, for an extended period while environmental conditions are less than applicable. It is
thought that a potential biological survival tactic for tardigrades accumulate solutes such as
nonreducing colloidal disaccharides such as trehalose could potentially play a role in the
protection of the cell during desiccation. While most tardigrade species are tested in
extremely dry conditions this article tests the tardigrade, Ramazzottius varieornatus’s,
survival capacity of this species in below-freezing conditions in both the hydrated and
dehydrated state. These tests involved a sample of dehydrated and hydrated tardigrades to
freeze them at a rate of >10K/min. It was concluded that roughly 75% of the dehydrated
sample survived the freezing process. Furthermore, the hydrated samples did not survive
the freezing process. A potential reason for these results was thought to be because of the
moisture in the hydrated samples precipitated during the freezing process and the
dehydrated samples had no moisture to precipitate during the freezing process. With the
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precipitant freezing in the organism, it causes cracking in the cellular structure that is
irreversible during rehydration which then leads to the organism’s death.
c. The results of these experiments are quite extensive with the number of tests they were able
to perform. This allowed them to provide ample evidence to support any hypothesis tested.
d. The results of the tests done in these experiments fit my topic because the writer tested the
tardigrades in multiple sicarios of extreme conditions.
e. Based on the findings in this article and the findings from previous studies a potential topic
that can be further researched is the potential testing of colloidal sugars in different multi-
cellular organisms to see the effect of cryopreservation.
Rizzo AM, Altiero T, Corsetto PA, Montorfano G, Guidetti R, Rebecchi L. 2015 Space flight
effects on antioxidant molecules in dry tardigrades: the TARDIKISS experiment. BioMed
research international vol. 2015: 167642. doi:10.1155/2015/167642
a. The purpose of the experiments done in his article is to determine the effects of space
stressors on animal life cycles, survivability, pathways of molecules working as
antioxidants, and DNA integrity.
b. This experiment was unique in the sense that the tests were performed during the DAMA
(Dark Matter) organized by the Italian Space Agency (ISA). This provided scientists to use
the microgravity environment to their advantage while performing tests to study certain
space stressors. Paramacrobiotus richtersi Ramazzottius oberhaeuseri and are the two
tardigrade species used in these experiments. During these experiments, both species
were exposed to oxidase stressors which allowed the scientists to evaluate the catalytic
activity and examine the activity of glutathione reductase. Each test was recorded in
flight and on the ground to provide a baseline for each experiment. The results of the
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following tests Ramazzottius oberhaeuseri did not have any detectable results of
glutathione peroxidase activity and glutathione content. While Paramacrobiotus richtersi
showed an increase in glutathione peroxidase activity. Each species’ fatty acid percentage
was recorded post-induction of peroxidation resulting in Ramazzottius oberhaeuseri
having a significant decrease of the fatty acid C22-6 n-3. In comparison to a temperature-
controlled sample Paramacrobiotus richtersi, Ramazzottius oberhaeuseri is significantly
lower.
c. Based on limited resources and how quickly the experiment had to be done it is
surprising how much data was collected. A better description of what resources were
needed for these experiences and what limitations prevented any other extensive research
could be noted to determine what changes could be done in the future if the chance for
these experiments ever arises again.
d. The main research topic was to determine the effect of microgravity conditions on the
tardigrade species. These experiments allowed scientists to learn how tardigrades'
adaptive tendencies with space stressors can survive for extended periods. This in turn
may allow scientists to then use this research to determine safer methods to make human
space travel safer.
e. The opportunity of doing more extensive research in space with tardigrades in both
hydrated and tun states for longer periods can potentially lead scientists to learn better and
safer ways to extend space travel missions for humans.
