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Welcome to the Microscopy Blog! Here you'll find chronicles of experiments, techniques, observations, and ideas pertaining to light microscopy. Subject matter will include compound microscopes, stereo microscopes, staining, specimens, histotechnique, chemistry, crystals, critters, and just about anything else that pertains to what can be viewed under a light microscope. The first few posts are going to remain right here on this page; to access the main blog, please click here. The main blog has all the normal features (comments, archiving) that you'd expect. The web page you're on right now was something I created while trying to figure out how to work the controls; I'm going to leave it in place as an entry page. Digging Through The Slide Box 16 March 2008 One way to make semi-permanent mounts is to put a line of mounting medium or varnish all the way around the edges of the cover slip. When it dries, it will greatly slow the drying-out of the specimen. Going through my slide box, I found a few that have really started drying out. The water evaporates slowly through micro cracks in the varnish. Last year I wrote up an article about a stain recipe having three, common food dyes. One of the slides (a semi-permanent, prepared as above) has started to dry out. It's leaving behind some strikingly cartoon-like crystals: 
I don't know if the multiple dyes are forming co-crystals, but it seems possible. The predominant crystal type (by far) has a tan hue that is similar to the muddy, tan aspect the dyebath takes on if not treated with alcohol. It could be that there's a dye supermolecule here, possibly the product of hydrogen bonding (as opposed to the charge interactions that yield methylene blue eosinate). It is amazing what can be seen with little more than a student-grade microscope. -Chris Tape Lift Reveals Fungal Pigment 15 March 2008 Tape lifts can be a convenient source of microscopy specimens. You can even make them with plastic slides. Simply get a fresh piece of clear plastic tape, press the sticky side to a specimen-rich surface, lift it off, and stick it to a clean slide. The mounts are semi-permanent. (Don't use tape lifts on valuable surfaces; the tape can rip away paint, varnish, wallpaper, and so forth.) I have a mold specimen from several years ago, lifted prior to the main colony's becoming acquainted with strong NaOCl. (I had hoped to capture a specimen of the dread Stachybotrys chartarum, but no joy). I don't yet know what species I have here, perhaps something from the genus Cladosporium. However, today the tape lift (now at least 5 years old) revealed something I hadn't noticed before. 
Photo taken with a USB MiniVID eyepiece camera on an Observer III microscope. Notice the purple coloration. It appears to be a fungal pigment. I don't recall seeing this when I made the slide, but it's here now. It seems the presence of coloration depends on air space; another sample, made from the same colony but embedded in synthetic mounting medium, shows no visible trace of pigment. Many species of fungi, including some from the genera Cladosporium [1], Epicoccum [2], Phorum [3], Cercospora [4], and others, can produce purple or bluish pigments. It appears that is what these tape-trapped fungi have done. Could outgassed chemicals from the tape have played any role (e.g., as nutrients)? Could these colonies have been attempting to grow in their new environment? It seems very possible. Fungal pigments can be fairly complex and hard to characterize; I don't know what this one is. Also, if anyone can identify the mold species, feel free. - Chris Another view of the tape-lifted mold specimen. This one also shows some of the purple pigment (upper right corner of photo; look carefully). References: [1] Image GK503 from the Geraldine Kaminsky Mycology Library, hosted at doctorfungus.org. (Link) [2] Kimbrough, J. "Indoor Air Pollution". PLP News: The Newsletter of the Plant Pathology Department at the University of Florida 8(1): 7, 2004. (Link) [3] US Micro-Solutions, Inc. website (Link) [4] Roy, K and Abney, T. "Purple seed stain of soybeans". Phytopathology 66: 1045-1049, 1976. New Site, First Post 14 March 2008 First entry in the blog. Yes, you're seeing it right here. Welcome to the brand-new website microscopyblog.com. In case you are wondering, it's a blog about microscopy (as opposed to a blog about micros that copy, whatever that would mean.) Until I've set up the proper blog controls, I'll post entries right here on this main page. -Chris All graphics, text, and photos are Copyright 2008. All rights reserved. |
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