Williams Oral exam

how long is the life cycle of the hermaphroditic nematode and how many progeny per adult?

3 day life cycle with 300 offspring

what is the difference between forward and reverse genetics?

forward —> starting with mutations in the protein sequence and observing the mutated phenotypes

reverse —> starting with a mutated phenotype and finding the mutated protein sequence

how does C. elegans complement in vitro models?

it allows research that is usually conducted in single-cell models (serotonergic synapses) to be conducted in a functional multicellular unit

c. elegans have 302 neurons, but how many neuronal subtypes?

118 subtypes

how many chemical synapses? electrical junctions? neuromuscular junctions?

6393 chemical synapses, 890 electrical junctions, 1410 neuromuscular junction

the main _________ systems and _______ networks are phylogenetically conserved from nematodes to vertebrates

neurotransmitter systems and genetic networking

what is a key method for testing a specific neurons function in c. elegans?

neuronal ablation

sinusoidal movement in c. elegans refers to what?

the amplitude and frequency of body bends

what two neurotransmission pathways are studied when analyzing nematode sinusoidal movement?

GABAergic and cholinergic motor neuronal function

_______ and _______ functions of _________ neurons are evaluated by measuring the pharyngeal pumping rates and response to touch

motor and mechanosensory functions of glutamatergic neurons —> pharyngeal pumping rates and response to touch

TRUE/FALSE: the electrophysiological response to drugs in C. elegans is comparable to that of vertebrates

TRUE

what is the main nematode characteristic responsible for unraveling evolutionarily conserved cellular and genetic pathways responsible for neuron fate specificity?

transgenic mutants

2002 Nobel prize in physiology and medicine was awarded for what?

mechanistic elucidation of apoptotic pathways in c. elegans

what does MAPK stand for in p38 MAPK?

mitogen-activated protein kinase

what is p38 MAPK activated by and what downstream effects are caused?

p38 MAPK can be activated by cellular stress and inflammatory stimuli, this can activated apoptosis and cell differentiation

activation of the AKT pathway results in what responses from the cell?

promotes cell survival, growth, proliferation, metabolism

what characteristic of c. elegans allow for sex-specific studying?

c. elegans are amenable to gender manipulation

what are interneurons? what are the four pairs of interneuron pairs in c. elegans?

interneurons are neurons that connect sensory neurons and motor neurons. the four are AVA, AVB, AVD and PVC

what is the difference in A-type and B-type motor neurons in C. elegans?

A-type neurons in c. elegans are responsible for backwards movements whereas B-type motor neurons in C. elegans are responsible for forwards movements

what do D-type motor neurons do in c. elegans?

coordinate motor movement (sinusoidal movement)

what are the six main mechanosensory neurons in C. elegans

ALM (R and L), AVM, PLM (R and L), PVM

which c. elegans neurons are mainly responsible for chemical/danger avoidance?

ASH

what roles do M3, MC, M4 and NSM neurons play in feeding?

M3 (pharyngeal relaxation), MC (pumping rate control), M4 (isthmus peristalsis) and NSM (stimulates feeding)

what are the AIY and AIZ neuron functions in c. elegans?

both are interneurons that facilitate sensory information (from AFD sensory neurons) into motor coordination

what neurons do AIY and AIZ talk to to facilitate motor movements in response to sensory inputs?

RIA and RIB neurons

what neuronal pathway(s) are used to turn sensory information into motor movements?

AFD sensory neurons —> AIY and AIZ interneurons —> RIA and RIB interneurons —> SMD and RMD motor neurons (in the head)

what are RMD and SMD neurons responsible for in c. elegans?

motor movements in the head

CEP neurons function is responsible for dopamine-encouraged ______________ in the head

mechanosensation

ADE neurons are dopaminergic nose-touch ____________

mechanoceptors

ADE modulate locomotion behavior in the presence of food via what mechanism?

mechanosensation

all forms of paraquats are reduced to a radical ion, which generates superoxide radicals which goes on to react with what cellular components?

unsaturated membrane lipids

what is age-1 in c. elegans?

age-1 is a subunit of PI3K, a kinase crucial to the IGF-1/insulin signaling pathway

what key finding in rotenone exposure was found using C. elegans?

mutating complex I in the MTC resulted in hypersensitivity to rotenone, implicating complex I in rotenone resistance

what key finding in paraquat exposure was found using C. elegans?

functioning sod-1 sod-2 and age-1 are all crucial in mitigating paraquat-induced oxidative stress

what key findings in OP exposures were found using C. elegans?

OP exposures (below survival reduction levels) reduced motor coordination, likely via an attack on the cholinergic system

what three outcomes were shown in C. elegans expressing human alpha-synuclein?

reduced overall DA content, increased DA neurodegeneration and motor deficits

knockdown/mutations in the PARK2 (nematode:PARKIN) and PARK7 (nematode:DJ1) resulted in what?

similar pharmacological vulnerabilities to those worms expressing alpha-synuclein

why is the transgenic c. elegans model organism good for drug-induced or genetic mutated neurodegenerative models?

a.) provides rapid insights of genetic pathways in neurodegenerative models

b.) offers broad high-throughput screening methods for anti-neurodegenerative drugs

what is the main presenilin orthologue in c. elegans?

sel-12

most knowledge about AD acquired in C. elegans came from which two transgenic models?

worms expressing betaAPP and worms expressing TAU

what is the main “scissoring” transmembrane protein implicating in Alzheimer’s?

gamma-secretase

betaAPP transgenic worms revealed which two genes involved in the progression of AD?

aph-1 and pen-2

which DNA repair mechanism shows the least conservation between c. elegans and mice/humans

base excision repair

________ _______ repair is crucial to repair DNA damage induced by environmental toxins

nucleotide excision repair

what are three main qualities that make c. elegans amenable to high-throughput screening?

the variation in maintenance conditions (plate type), variation in exposure conditions (injects, acute, chronic etc.) and automated imaging methods

what nematode ortholog encodes for human IGF-1 receptor?

daf-2

what is the reversion assay?

you start with a mutant with a clearly observed phenotype (ex. uncoordinated movement) and expose to a toxin. If the toxin induces a mutation, normal phenotypes will be observed

in a mutagenic PCR assay, the amount of PCR product is ________ proportional to the amount of DNA damage

inversely

inducing a mutation in C. elegans via a toxin is then analyzed to find the mutation site (forward genetics) via _____-_____ rescue or RNAi _________

single-gene rescue or RNAi phenocopying

what is the ahringer library

a library of 16,000 bacterial strains that each code for a single gene RNAi knockout phenotype that is fed to c. elegans which knocks the genes out

what are the three ways RNAi can be introduced/activated in C. elegans?

introducing interfering dsDNA via:

1. injection into the worms

2. feeding them E. coli the produce the dsDNA

3. soaking them in a solution with dsDNA

where are two locations C. elegans can be naturally found?

rotting fruits in the wild and the interstitial water between soil particles

what enzyme does the lacZ gene encode for? what does this enzyme do?

lacZ encodes for B-galactosidase, which cleaves lactose into glucose or a simpler sugar. the color of bacterial colonies, via this gene, are indicative of whether a segment is properly inserted into the plasmid or not

how was “feeding” quantified in Williams metal toxicity study?

Optical density at 570nm was measured at each timepoints and had the control optical density subtracted from it at each timepoint

why is the “feeding” assay crucial as a supplementary assay to other toxicity endpoints?

these results could show a lack of feeding in the nematode, which could give rise to/explain other toxicities observed (loss of locomotion, survival, growth)

What environmental factor significantly reduced the quantified toxicities observed in heavy metal toxicity screening in C. elegans?

the presence of sodium and potassium in the medium reduced metal toxicities

for the “using the nematode C. elegans to predict mammalian acute lethality to metallic salts” paper, what was the major finding?

using lethality assays to calculate the LC₅₀ values in C. elegans revealed similar toxicity trends to the LD₅₀ values of the same metallic salts in mammalian models (mice and rats). While the C. elegans values were higher, the overall trends and rankings of the metallic salts remained true