Papa and Baby Diatom

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micron
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Papa and Baby Diatom

Post by micron »

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While surveying a sample of diatoms I came across the pair shown in the picture (phase contrast objective – 25x/0.80). They illustrate an interesting aspect of diatom asexual reproduction well described by Lund & Lund in “Freshwater Algae” re: “Diatom division results in the production of two new daughter cells. The siliceous box in which diatoms live causes the average cell size to decrease unless the normal course of multiplication can be altered. Multiplication is by binary fission. Of the two daughter cells so produced, one keeps the wall of the larger valve that is the top of the box and forms a new wall to fit inside it. Hence, this new cell is the same as the cell it arose from i.e., the mother cell. The other daughter cell arising from this binary fission retains the wall of the smaller valve of the mother cell and forms a new wall which fits within it like the bottom of the original box. Now we have two new cells, one the same size at the mother the cell and one smaller then the mother cell. As cell multiplication continues so more and more cells smaller than the original cell will arise and the smallest cells will become even smaller until they cannot grow normally or at all.” At some point in natural populations (as opposed to lab cultures) these small cells form auxospores which then “germinate” to form a normal size cell and the process begins a new.

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Ken Ramos
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Post by Ken Ramos »

Great images Ron and an interesting text. Sounds like a complicated process in coming full circle. Thanks for an informative post. :D
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Wim van Egmond
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Post by Wim van Egmond »

Dear Ron,

Wonderful! An excellent illustration of this strange aspect of diatoms.

Wim

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micron
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Post by micron »

I was lucky to catch these diatoms in the same frame (they were moving pass one another). I have seen this sort of thing few times in the past but did not have a camera ready to take a picture. Apparently these small cells are relatively rare in natural settings, but fairly common in lab cultures.

Vim - glad to see you have joined the group (your images and Web site are first rate). Tom and company deserve special thanks for setting up and maintaining this site. In my view it is the best group microscopy site on the Internet.

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Tom and company deserve special thanks for setting up and maintaining this site. In my view it is the best group microscopy site on the Internet.
Darn, Ron :!: :D You're making us blush :oops: :D :!:
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Post by Charles Krebs »

Good stuff Ron :D
One of the things I enjoy here is not only seeing fascinating images, but learning a good deal about the subjects as well!

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