In this laboratory¹ you will apply the techniques of dilution and measurement of concentrations to investigate a physiological parameter: the hemolymph (or blood) volume of an insect. A parameter is a quantifiable variable of a system you wish to study. Determining values for a parameter such as hemolymph volume allows you to measure the effect of a treatment in an experiment, or to calculate other things. For example, you can determine the absolute amount of a metabolite such as an amino acid if you know both its concentration and the volume of the hemolymph containing it. We have chosen the cockroach because it is readily available and it is large (for an insect!).

Your objectives are:

1. To determine cockroach hemolymph volume by injecting a known amount of Amaranth Red dye, and measuring its dilution by the hemolymph.
2. To think about and correct for possible errors in the method.

Outline:

1. Derive a standard curve for dye concentration by a method simulating the dilution by the hemolymph.
2. Inject a cockroach with a known amount of Amaranth Red.
3. Extract hemolymph samples at given times
4. Plot your data and calculate hemolymph volume.

My friend Steve and I were partners for the cockroach experiment. Steve was the data recorder, I was the grunt who did the actual dirty work. I told you he was smart.

The experiment consisted of us diluting cockroach blood in situ with Amaranth Red dye. Some reports have indicated a degree of carcinogenicity² with this dye, and the lab manual that we were working from told us to be careful with it because it was carcinogenic. As part of my grunt responsibilities, I had to draw the extracted blood/dye mixture up into a pipette (a long measuring tube).

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1. http://www.ableweb.org/volumes/vol-15/8-smith/8-smith.htm [↩]
2. http://msds.chem.ox.ac.uk/AM/amaranth.html [↩]

Q31: Pam Pollister writes: What color is the blood of a cockroach?

A: Pam, The long answer: Cockroach blood is not red because they do not use hemoglobin to carry oxygen. In fact their bloodstream is not used to carry oxygen either. They use a system of pipes called tracheae to bring the oxygen and remove carbon dioxide from their tissues.As a result other factors determine the blood color. Male cockroaches have relatively colorless blood. Larval females have colorless blood. Only adult females which are producing eggs have a slightly orange blood because of the protein vitellogenin which is made in the cockroach liver (its fat body) and transported through the blood to the ovary. This protein like chicken yolk is orange because it carries a carotenoid, which is a vitamin A like molecule needed by embryos to develop normally.

The short answer: Cockroach female adult blood is occasionally orange. All other cockroach blood is colorless.¹

Insect blood is actually called hemolymph, or haemolymph for those of you who are not American. But I digress. Let’s back up a little bit.

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1. http://boards.9thwonders.com/lofiversion/index.php/t58015.html [↩]

As Periapex was trying to survive the week, I ended up speaking with a patient of mine about full moons and lunar eclipses. My patient had worked for some time in the pyschiatric ward of a hospital and remembered this particular patient that admitted himself to the hospital the night of an eclipse.

He arrived at the hospital shivering and soaked and with rope abrasions around his neck. Apparently he had tried to commit suicide by hanging himself from a tree branch. The branch broke, he fell into a stream and almost drowned.

He was in quite a bad state of mind, not because of his failed suicide attempt, but because he almost drowned…

I’ve just re-added the moon tracker module to the sidebar on the right (it was on the original version of the blog). My front desk staff puts all full moons for the year into the appointment book because of the wackiness that happens around those times. The last full moon and lunar eclipse was an especially crazy time. Don’t know if it’s because of me, or the patients, or a combination of both.

This last week started out on an abjectly depressing note for me. Some major (almost catastrophic) family issues caused me to really withdraw into myself. Things have slowly been resolving and through the support of my wife, my brother and his wife I’m almost back to myself again. Thankfully my patients didn’t suffer too much.

I now know who does and should matter most to me in this short life that we live.

I’ve always maintained that blogging is a therapeutic exercise for me. Although through my comments this week you’ve probably had no inclination of what I was going through, my blog and its readers have been an anchor of sanity for me.

Thank you all.

Thanks to Chris again:

“…express an interest in learning about that particular breed; cater to the ego and ask how long they’ve been breeding/exhibiting – in dogs longevity is a source of pride. Ask a breeder how they choose prospective mates or how they choose which pup to keep.

I’d stay away from the usual….how do you walk that many dogs; or how do you deal with mealtimes; or do you win any money at dog shows (the answer is no haha); or how much do you sell your puppies for.“