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17 Sep 2018

In this short clip, you can see the mantis shrimp using somesort of feathery arm/claw to rub its eyes. Looking at a diagramhere, it appears possibly that it's using maxillipeds. Someone withknowledge of crustaceans (the behavior is probably not unique tomantis shrimp) would be appreciated.

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Hubert Koch
Hubert KochLv2
17 Sep 2018

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For Discussion (2-3 paragraphs) • What was the concentration of your pre-diluted NPs? • Determine the effect of NPs on brine shrimp lethality. • Determine the effect of NPs on cell viability. • What is (are) the control(s) in this experiment? What is its purpose? • Based on your data in this lab, what is a safe concentration for brine shrimp Threshold Level of Toxicity (TTL)? • Often indicator species are used to study the overall health of an ecosystem. If you were to study an ecosystem containing brine shrimp, would you use it as an indicator species? Why or Why not? Explain your reasoning. • What possible sources of error were present in this experiment?

Introduction

LD50 is a commonly used term to describe acute toxicity: LD stands for Lethal Dose and 50 is used because the dose could kill 50% of the animals exposed to the chemical. For LD50 tests, the animals are given specific amounts of the chemical, orally, by injection or dermally. The value is then reported along with the method of administration and the type of animal used in the test. LD50 is typically reported in milligrams or grams per kilogram of body weight of the animal. The lower the LD50 is, the higher the toxicity of the chemical would be. This information is always provided in Safety Data Sheet (SDS) of chemicals in the “toxicity data” category. A similar measure, the LC50 is usually used to describe the ecological hazards of chemicals. LC stands for lethal concentration that could kill 50% of the animals after 24-96 hours. This value is always provided in Safety Data Sheet (SDS) of chemicals in the “Ecological Data” category. In this lab, you will be measuring LC50 or LD50 of iron oxide nanoparticles using brine shrimp. Iron oxide nanoparticles are magnetic. Application of magnetic nanoparticles ranges from magnetic storage media to medical industry where they can be used for targeted drug delivery or as contrast agents in MRI. Thus, measuring environmental and biological toxicity of these nanoparticles is crucial. To test toxicity of any such reagents on small organisms, Daphnia and brine shrimps (also known as Artemia) can be used. Artimia are found in salt lakes around the world. They are important live food for aquarium fish. In this lab, you will use brine shrimp to measure toxicity of the nanoparticles. Trypan blue is a stain used to assess cell viability. It is able to diffuse through cell membranes of dead cells but is unable to permeate live cells. This stain can be used to assess cell survival 1 Fall 2017 following exposure to chemicals, nanoparticles and experimental drugs. The ratio of live: dead cells can be used as a preliminary assessment of cytotoxicity and translated to tissue viability.

Methods Part A: Serial Dilution of NP Solution 1) Label 5 test tubes as 0, 1:1, 1:10, 1:100, 1:1000 2) Add 2mL of seawater to tube 0 3) Add 2mL of specific group stock solution to tube 1:1 and add 2mL of seawater to it. 4) Transfer 1mL of stock solution to tube 1:10 and add 9mL of seawater to this tube 5) Transfer 1mL of 1:10 solution to the tube labeled as 1:100 and add 9mL of seawater to 
this tube 6) Transfer 1mL of 1:100 solution to the test tube labeled as 1:1000 and add 9mL of 
seawater to this tube Part B: Preparation of test environments 1) Label 5 wells of 6-well plate as control (0), 1:1, 1:10, 1:100 and 1:1000 2) Label 3 petri dishes as: control (0), 1:1 and 1:1000 
NOTE: Be sure to include your initials on all plates 3) Transfer 2mL of each solution from the corresponding test tube to the respective wells on your six-well plate and each petri dish Part C: Preparing specimens for the Trypan blue cell viability test 1) Transfer 2 brine shrimp into each of the pre-labeled petri dishes containing the solution of NPs and seawater (0, 1:1 & 1:1000) and set a timer for 30 minutes. 2) Transfer a single brine shrimp into the unlabeled petri dish with a drop (~50ul) of seawater and use the dissecting microscope to make observations related to the behavior and morphology of untreated brine shrimp.
Make observations in lab notebook of all samples Part D: Preparation of specimens for the toxicity assay 1) 2) 3) 4) 5) Add 10 brine shrimp into each well in the 6 -well plate Make observations in lab notebook Using a dissecting microscope (if needed), count the number of brine shrimp in each well (alive shrimps).
Record your data in your notebook using the graphic below as a template. Close the plate and store it for next observation.
Observations must be done within 24h-96h
Note: There will be times allocated and a sign up paper for observations Part E: Trypan blue viability test 2 Fall 2017 1) Label 3 glass slides to match the petri dishes prepared in Part C. 2) Transfer 1 brine shrimp from each petri dish onto the corresponding slide. 
Make observations in your lab notebook 3) Add a drop (~60 μl) of PBS on top of each specimen 4) Add 60 μl of Trypan blue to your shrimp and incubate for 1-2 minutes at room 
temperature. 5) Wick away excess liquid 6) Add 100 μl PBS to sample and observe (while alive!), looking for blue cells, using the 
dissecting scope 
Make observations in your lab notebook 7) Label 3 microfuge tubes to align with each sample. 8) Transfer each brine shrimp from the slide into the corresponding microfuge tube 9) Add 50 μl of PBS to the tube and use the mechanical disruption tool to homogenize the 
sample for ~2 minutes until a cell suspension has been generated. 10) Load 30-50 μl of your sample onto a new glass slide and add a cover slip. 11)Observe the sample on high power and use the scale below to qualitatively assess cytotoxicity” 0-no blue 1-some blue 2-fairly blue 3-totally blue.

10. I am interested in cloning the "hox" gene in my favorite non-model organism - clam shrimp. I make a cDNA plasmid library from adult females, plate it, and Sanger sequence 60,000 random clones. Since clam shrimp likely only have about 20,000 genes, I expect to sequence the hox gene roughly 3X. Is this a reasonable research strategy?

A. No, a cDNA library will not contain hox genes, they are non-transcribed DNA elements B. Yes. The probability of getting the hox gene is pretty high given that you have 3X

sequencing coverage of the library.
C. No, the probability of any given clone being a hox gene is NOT 1/20,000. It is

proportional to the expression level of the gene (and that could be low).
D. No, the probability of getting a hox gene is proportional to its length, and hox genes are

short

11. If I said I was going to sequence your genome using an "assembly by reference" approach, what does this mean?

A. I would make an Illumina gDNA library of your genome, Illumina sequence it, and assemble your genome using sequence overlaps

B. I would make a plasmid gDNA library of your genome, Sanger sequence it, and assemble your genome using sequence overlaps

C. I would make an Illumina cDNA library of your genome, Illumina sequence it, and identify mutations in promoters

D. I would make an Illumina gDNA library of your genome, Illumina sequence it, and identify variants by aligning the reads to a "reference" human genome

Explanation would be greatly appreciated! Final in two hours so plez help

The Eye Exam It was a sunny day in 2005, and time for Eric’s annual eye exam. Dr. Tim flipped through his charts. “You know, we really should measure your visual fields. It’s been at least ten years since you had that done!” “I hate them!” Eric grumbled. “I get disoriented and, anyhow, we already know I have a large blind spot.” He raised his hand, squinting through one eye. “Here. I can’t see my finger here.” “I know.” Dr. Tim was sympathetic. “But weren’t you just telling me you haven’t seen stars for a while? It’s important. You had that tumor on your pituitary gland. Your optic nerves cross in that area, right in front of the pituitary, so if anything is happening again we’d probably notice it first by changes in your eyesight. It really is important!” An hour later, Eric was seated in front of a large white screen, staring intently at a light in the middle. “Keep looking at that light, so your eyes don’t move. If you see another light anywhere else, push this button.” Eric began the test by focusing on the light he saw in the center. The machine then successively displayed points of light of varying intensity in different places around the entire visual field. When Eric saw the peripheral light, he pushed a button. He did his best to detect the flashes, but realized he was probably missing some. The machine mapped out where he could see and where he could not. Dr. Tim looked at the printout. His face grew serious. “Eric, we have a problem. You have limited peripheral vision, and it’s bad enough that I don’t think you should be driving! This looks to me like something called retinitis pigmentosa. We should refer you to a specialist.” He pulled out more papers. “Here, look at this. Here are your visual fields. The numbers show how well you can see in that area of your eye, and in the graph on the right the darker the box is the less you can see. Now here are a normal person’s visual fields. Do you see the difference?”

1. How do your eyes work? What is the difference between focal vision and peripheral vision?

2. What is the anatomy around the pituitary gland? Why are the optic nerves likely to be affected by pituitary tumors?

3. Eric has retinitis pigmentosa In this disease pigments lining your eye gradually break down, so you can’t sense the light that hits your eye. Why do you need the pigments in order to see the images and light?

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