Clean sample

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WhyMe
Posts: 23
Joined: Fri Dec 27, 2019 10:04 pm

Clean sample

#1 Post by WhyMe » Wed Jan 15, 2020 2:05 pm

I was wondering if anyone would share their procedure on how to obtain a clean sample to observe? All the videos and pictures I see online have very few clumps of grit. What are the tools to use and how to use them? Also, calming solutions, how to apply and what to use. Some of the animals move really fast and I can't follow them!

Chris Dee
Posts: 55
Joined: Mon Aug 12, 2019 1:02 pm

Re: Clean sample

#2 Post by Chris Dee » Wed Jan 15, 2020 3:05 pm

I'll add the simplest method. Float a cover slip on the surface of a pond water sample and leave for 8 hours. Place a drop of clean sample water on a slide then carefully lift the cover slip off the surface and place on the slide. The hard bit is lifting the floating cover slip off without contaminating the top surface with water. Not the end of the world as it can be wicked off with tissue, but best avoided especially if using high NA objectives.

gastrotrichman
Posts: 44
Joined: Mon Nov 12, 2018 4:04 pm
Location: Oregon, USA

Re: Clean sample

#3 Post by gastrotrichman » Wed Jan 15, 2020 4:44 pm

If you Google "make Irwin loop" you'll see information about how Irwin loops are used, and how they can be made. They allow individual critters to be captured and moved to a clean droplet of water on a slide. Using a stereoscope and a fine transfer pipette, I capture a gastrotrich (or other critter) from a Petri dish, and transfer it to a slide along with a good sized pool of water. I then use an Irwin loop and the stereo scope to capture an individual gastrotrich (gastrotrichs are almost constantly moving) and transfer it to a clean slide with a small drop of clean water drawn from just below the water surface in the Petri dish. Beads of petroleum jelly on opposing edges of a cover slip keep the gastrotrich from being crushed by the cover slip … pieces of a broken cover slip or small dabs of modelling clay can be used at each corner of the cover slip to accomplish the same thing.

If you check one of the treatises on aquatic invertebrates, you should be able to find information on slowing or stopping various critters. For gastrotrichs, I press the cover slip down, which flattens the petroleum jelly beads and eventually squeezes the gastrotrich slightly. Or, more often, I run a small drop of 1 percent magnesium chloride under the cover slip as an anesthetic.

Happy hunting!
gastrotrichman

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WhyMe
Posts: 23
Joined: Fri Dec 27, 2019 10:04 pm

Re: Clean sample

#4 Post by WhyMe » Thu Jan 16, 2020 12:09 am

Chris Dee wrote:
Wed Jan 15, 2020 3:05 pm
I'll add the simplest method. Float a cover slip on the surface of a pond water sample and leave for 8 hours. Place a drop of clean sample water on a slide then carefully lift the cover slip off the surface and place on the slide. The hard bit is lifting the floating cover slip off without contaminating the top surface with water. Not the end of the world as it can be wicked off with tissue, but best avoided especially if using high NA objectives.
Thank you I will try that. But I fear I'm all thumbs :lol:

WhyMe
Posts: 23
Joined: Fri Dec 27, 2019 10:04 pm

Re: Clean sample

#5 Post by WhyMe » Thu Jan 16, 2020 12:58 am

gastrotrichman wrote:
Wed Jan 15, 2020 4:44 pm
If you Google "make Irwin loop" you'll see information about how Irwin loops are used, and how they can be made. They allow individual critters to be captured and moved to a clean droplet of water on a slide. Using a stereoscope and a fine transfer pipette, I capture a gastrotrich (or other critter) from a Petri dish, and transfer it to a slide along with a good sized pool of water. I then use an Irwin loop and the stereo scope to capture an individual gastrotrich (gastrotrichs are almost constantly moving) and transfer it to a clean slide with a small drop of clean water drawn from just below the water surface in the Petri dish. Beads of petroleum jelly on opposing edges of a cover slip keep the gastrotrich from being crushed by the cover slip … pieces of a broken cover slip or small dabs of modelling clay can be used at each corner of the cover slip to accomplish the same thing.

If you check one of the treatises on aquatic invertebrates, you should be able to find information on slowing or stopping various critters. For gastrotrichs, I press the cover slip down, which flattens the petroleum jelly beads and eventually squeezes the gastrotrich slightly. Or, more often, I run a small drop of 1 percent magnesium chloride under the cover slip as an anesthetic.

Happy hunting!
Irwin loop..... they look simple to make so I'll give it a try. The plan calls for nichrome wire, I've built a hot wire cutter for a few projects I've done in the past and I have some left. When I make one I'm sure I'll have some questions on how to use it!

I'm willing to try the magnesium chloride also!

Thank you for the information!

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