Coordinating
the Raucous
Crowd:
Quorum Sensing
Signals Affecting
Microbial Social
Function
Overview
• Introduction to Quorum Sensing:
Acyl-Homoserine lactones (Acyl-HSLs)
• Occurrence, Structures and Characteristics
• Signal Synthesis and Degradation
Egland & Leadbetter
Luciferase activity (quanta per sec X 107)
100
1
10
0.1
1
0
2
4
6
8
Optical density (660 nm)
1000
10
0.01
10
Time (hours)
Nealson & Hastings
O
O
O
N
H
O
O
N
H
OH
O
O
N
H
O
O
O
O
O
N
H
O
O
O
N
H
O
O
Prototypical Acyl-HSL Mediated Quorum Sensing Systems
Overall
•Bacteria
Details
Synthase
(LuxI homologues) Acyl-Homoserine
Lactones (AHLs)
Genes
off”
Regulator
(LuxR homologues)
Genes
“on”
Quorum Regulated Genes
Examples of Functions Regulated by Quorum Sensing:
•
Light production
•
Exopolysaccharide synthesis
•
Extracellular enzymes synthesis: proteases, chitinases, pectinases,
elastases
•
Antibiotic synthesis: carbapenem, cyanide, phenazines
•
Biofilm formation
Examples of Environments from which Quorum Sensing Bacteria are
Isolated
•
Marine animals: Gut tracts and light organs
•
Clinical biofilms: lungs, urinary catheters
•
Plant roots: nodules of legumes, crown galls
•
Plant leaves: leaf wilt diseases
•
Soils
Rotten Lettuce in your refrigerator?
It’s probaby due to a plant pathogen,
(a Pseudomonas or Erwinia species)
responding by quorum sensing
to acyl-HSLs.
Biological Quorum Signal Decay Mechanisms
Acyl-homoserine Lactone (AHL)
Chemical Hydrolysis
AHL Lactonase
Bacillus
Agrobacterium
Klebsiella
Arthrobacter
Acyl-homoserine (AHS)
CO2
other products
AHL Acylase
Variovorax
Ralstonia
Pseudomonas
+
Fatty Acid
+
Homoserine
Lactone
Arthrobacter
Burkholderia
In the laboratory as in nature:
- Bacteria can make and respond to Acyl-HSL signals.
- Bacteria can break them down and utilize them.
1) ARE Acyl-HSL SIGNALS STABLE IN SOILS?
2) IS Acyl-HSL SIGNAL BIODEGRADATION RELEVANT
TO QUORUM SENSING BACTERIA ?
QUIZ! (14 pts)
1, Please name the primary generalized function of quorum sensing (QS).
(2 pt)
2, What are four physiological processes are regulated by QS? (2 pts)
3, What are two completely different types of molecules that function in
QS in different bacteria? (2 pts)
4, Please provide the generalized chemical structure of an acylhomoserine lactone. (2 pt)
5, What types of bacteria make and respond to them? ( 2 pts)
6, How and why do these bacteria degrade these molecules? (2 pts)
7, What are the consequences of the loss of QS in general?
(2 pt)
Bacteriology Final
There are 126 pts total
and 37 questions.
Please write your name
and number of lectures
missed due to sickness
on the first page of the
exam.
Bacteriology Final: Short answers (29)
1. Please provide 3 benefits resulting from the establishment and study of
protein
homologies. (3)
1.
2. List 5 very different benefits to humans resulting from the study of
bacteriology. (5)
3. What are the three best ways to control bacterial infectious diseases? (3)
4. Describe two forms of “jet propulsion” motility, and two forms of “crawling”
or “twitching” motility in bacteria. (4)
5. Please list 5 unique characteristics of archaeal envelopes and their
constituents that distinguish them from bacterial and eukaryotic envelopes. (5)
6. Name three conditions that are known to cause or allow bacteria and
archaea to reduce the sizes of their genomes. (3)
7. You are infected with Bacillus anthracis while in the Tortuguero rain forest.
Explain why you didn’t come down with anthrax until welcome week. (2)
8. What are 4 basic differences between the structures of and assembly
mechanisms for flagella and pili? (4)
Bacteriology Final: Essay type (8)
9. What are the two principle modes of
energy generation observed for
organoheterotrophic living
organisms?
Be sure to list and describe four
distinguishing features for each of
these two processes.
Bacteriology Final: True/False (10)
10. Prions are infectious particles that pathogenic bacteria secrete to cause disease
in the host animal organism.
11. Mycolic acids in the outer membranes of Mycobacterium tuberculosis and Mycobacterium leprae enhance resistance to antibiotics and therefore cause prolongation
of the human and animal diseases caused by these actinobacteria.
12. The only human cells which are known to be immortal are germ and embryonic
cells.
13. Mycoplasmas and their close relatives are the only known bacteria that do not
have peptidoglycan cell walls.
14. Pili are able to transfer proteins and DNA from a male bacterium to female
bacteria.
15. The presence of c-type cytochromes allows certain pili to function as nanowires,
transferring electrons from extracellular solid minerals to NAD+ or NADP+ in the
bacterial cytoplasm.
16. In the presence of increasing concentrations of an attractant, a chemoreceptor
binds the compound on the outside of the cell to activate dephosphorylation and
methylation of the MCP receptor.
17. Catabolism involves breaking bonds in metabolites to generate ATP via substrate
level phosphorylation.
for anabolism.
18. Most kinds of photoauxotrophic bacteria can use molecular oxygen (O2) as the
electron donor.
19. No archaeon is known to cause a disease in an animal, plant or fungus.
Bacteriology Final: Matching (mulitple
answers are possible; 3 pts per
2 organismal type)
020, What macromolecules are common to the envelopes of:
a, lipopolysaccharides
b, mycolic acids
A, Gram-negative bacteria
c, ether lipids
d, ester lipids
e, murine
B, Low G+C Gram-positive bacteria
f, teichoic acids
g, L-glycerol lipids
C, High G+C Gram-positive bacteria
h, D-glycerol lipids
D, Archaea
i, isoprenoid lipids
Bacteriology Final: Fill in the blanks.
(1 pt per blank; 7 pts total)
21, Autotrophic bacteria that live in the caves in Tabasco, Mexico that do not require
fixed carbon compounds are called ______________ where the compound
______________ serves as the electron donor for respiration.
22, Two metabolic pathways that produce ATP by substrate level phosphorylation
are ______________ and ________________. To make a pmf from ATP the
enzyme called the_______________ is required.
23, The primary pathway that generates a pmf or an smf as the primary source of
energy is called the _________________, and the proteins that generate the pmf
or smf are called _________________.
Bacteriology Final: ESSAY TYPE
(ten points each)
24, Show schematically and describe how peptides are believed to have evolved
into complex group translocators of the phosphotransferase system (PTS). Please
explain what is going on according to the scheme you present.
25, Describe the mechanistic (molecular) essence of any short term memory system
(such as the one that allows E. coli to chemotax up an attractant concentration and
down a repellent concentration). Use this chemotaxis system to exemplify the
process, but also indicate which elements are general to all memory systems,
and which are specific to this one.
26. Please describe and show schematically how the F-type ATPase (ATP synthase),
present in almost all living cells, interconverts chemical and chemiosmotic energy.
Be specific about the molecular mechanism.
Bacteriology Final: Multiple Choice
(multiple answers possible; 2 pts each)
27. Type I (ABC)
a, can secrete only proteins
b,bcan secrete proteins and DNA
c, can secrete proteins, lipids
and carbohydrates
28. Type II (Sec)
d, uses ATP to energize secretion
e, uses the pmf to energize secretion
f, does not use energy
29. Type III ( Fla, Path)
g, can insert proteins into the
membrane
30. Type IV (Conj, Vir)
Bacteriology Final: Multiple choice (2 each)
A,
31. Transduction
32. Conjugation
33. Transformation
34. Gene Transfer Agent
A, involves an infectious agent
B, involves type IV secretion
C, is related to an infectious agent
D, the DNA donor always dies
E, the DNA donor sometimes dies
F, the DNA donor never dies
,
Bacteriology Final (2)
35. Define quorum sensing.
36. List 4 of its biological
functions.
37. Give the names of
three molecular types
(different molecules).
Bacteriology Final:
CONGRATULATIONS;
YOU’RE DONE!
Human Impact (H.I.)
on the Environment:
Final Exam
42 questions; 109 pts today.
OVERALL:
48 questions; 144 pts. including 6
questions worth 35 pts of take home
extra credit
H. I. Final
( Multiple Choice; multiple answers per questions; three points each)
11, What are the PRIMARY contributors to green house gas production?
A,
B,
C,
D,
E,
Deforestation
Burning of fossil fuels
Agriculture
Cows belching and farting
Growing rice for the human population
2, Use of fertilizers containing nitrates can cause:
A, increased O2 concentrations in lakes and ocean deltas
B, increased fish populations in lakes and ocean deltas
C, increased algal growth
D, decreased O2 content of lakes and ocean deltas
E, decreased fish populations in lakes and ocean deltas
F, eutriphication and putrification
H. I. Final
(Multiple choice and fill in the blanks; there may be more than one answer. 3 pts each)
3, About how many mammals and birds are killed in the United States per year for
human consumption?
A,
B,
C,
D,
E,
10 millions
100 millions
1 billion
10 billions
3 brazilians
4, In the U. S. alone, the average beef cow is slaughtered at about ___________ years of
age, the average pig at ___________ years, and the average dairy cow at __________
years.
5, What were the purposes of reinstating the Global Gag Rule in 2000?
A, To promote economic development through free trade
B, To prevent foreign family planning agencies from providing abortion counseling and
referrals
C, To diminish the incidence of AIDS
D, To force standards on developing countries that were in need of financial aid
E, To impose the standards of a religious minority on the world population
H. I. Final
Short answers, two OR three OR four OR five points each as indicated below
6, Name three ways Costa Rica has succeeded in conserving its rain forests. (3)
7, Please provide 4 observations that reflect the extent of current global warming. (4)
8, Regarding the Monte Verde Reserve, what are three negative consequences of ecotourism? (3)
9, Name, define and cite the primary causes of two types of smog. (4)
10, According to Prof. Dave Woodruff, what is the # 1 cause of species extinction?
Name three ways in which humans have caused this. (3)
11, The two most important things we can do to preserve biodiversity on Earth are to (1)
_____________________, and (2) ______________________. (2)
12, What were 3 strategies used by the coal companies to make people question the
scientific evidence concerning the occurrence of global warming? (3)
13, What were 5 strategies used FOX “News” to make viewers reject liberal views? (5)
H. I. Final
14, According to Dr Tom English, what are the 5 principle causes of species extinction?
(5)
TRUE/FALSE (1 pt each)
15, Over 70% of oil used by the U. S. is imported.
16, The George C. Marshall Institute used the same techniques to cause people to
question (1) the harmful effects of cigarette smoking, (2) the consequences of ozone
depletion, and (3) the catastrophic consequences of global warming.
17, Per unit protein, meat consumes roughly 10x the amount of fossil fuels and land ,
and 20x the amount of water than the production of the same amount of soy protein.
18, For the benefit of human health and the environment, and to promote an ethical life
style, one should eat vegetarian diets.
19, Children who grow up in LA have 20% less lung capacity than children raised
elsewhere.
20. Only 4% of corn grown in the US is used directly for human consumption.
H. I. Final
T/F cont.
21, Genetic variability correlates with species fitness.
22, Biogeochemical cycles are due more to bacterial activities than to human activities.
Essay type. (7 pts)
23.
Compare and contrast China’s and Iran’s fight against overpopulation. What
differences in tactics did they use? Did they achieve their goals? What do these
observations imply?
Fill in the blanks ((8)
24.
Our greatest failure to implement renewable energy is our ___________. To
encourage the development of renewable energy, the government could and
should have (1)__________, (2)____________, and (3) ____________, thus providing
incentive to develop these new resources. Unfortunately, the Bush administration
has not implemented such measures mostly because of __________, ___________,
__________ and ___________.
H. I. Final
31. About how many insect species are believed to
exist in the Costa Rican rain forests?
32. How many mammalian species make their
homes in the CR rain forests?
33. How many bat species?
34. How many primate species?
35. How many rodents?
(1 pt each for 31 - 38)
36. How many plant species?
37. How many marine mammals?
38. How many eukaryotic species have been
identified and classified altogether on Earth?
H. I. Final
39. Why are Costa Rica’s health stats above
those of the United States in spite of the
tremendously greater wealth of the U. S.?
Please provide 5 tangible (including societal)
reasons as discussed during Dr. Fred Gifford’s
and Dr. Mario Tristan’s lectures.
Hint: SICKO (5)
40. What are three very important bacterial
infectious diseases in Costa Rica? (3)
H. I. Final
41. (8 pts) Please explain how
aerosols such as CFCs and
HCFCs cause destruction of
the stratospheric ozone layer.
Explain the time lapses for
decay and the principle of the
molecular mechanism involved.
H. I. Final
Please translate into English (3 pts):Spanish
43 43, Pura Vida!
44, Lo siento.
45, Soy vegetariano.
Please translate into Spanish (3 pts):
Please
46, Don’t worry!
47, Have a good time!
48, Congratulations!46
H. I. Final: extra credit; take home
42. Please list and explain the
importance of 5 factors that
throughout history, and including
the present, have inhibited
formation of a unified,
international, human community
that could help deal with the
immense global environmental
problems that face our species.
(10)
Take Home; extra credit
25. List 25 ways YOU personally can become more environmentally friendly. (5 pts)
Please then check those you actually have recently, or honestly plan to implement
in the near future into your personal life style. (5 pts)
Essay type questions
26.
According to OUTFOXED, what approaches has Fox “News” used to promote the
Republican REACTIONARY agenda. Please list and describe at least 5 such
approaches. (5)
27.
Please describe an ORIGINAL approach (ONE THAT YOU HAVE NEVER HEARD
PRESENTED BY SOMEONE ELSE) that you might implement so as to decrease
your own contribution to global warming. (5)
28.
What observations have you made since coming to Costa Rica that have had a
lasting impact on your approach(s) to environmentalism, and how do you plan to
implement the change(s) you propose? (5)
29.
What observations have you made in Costa Rica that have changed your view of
the world we live in? (5)
30.
Based on what you have learned in Costa Rica over the past 5 weeks, WHAT
POLICIES CHANGES ARE MOST URGENT FOR THE MAINTENANCE OF A
FUNCTIONAL HUMAN SOCIETY? Please list five. (5)
H. I. Final
Congratulations!
You’re done with both
finals! Pura Vida, let’s
celebrate!
(But only after grading)
H. I. Final