Micromanipulation pipettes

For the type of pipettes, refer to this document available at cookmedical (micromanipulation pipette).

This is the first time I am going to handle the above assembly to manipulate embryos and I am researching the type of micromanipulation pipettes available.

In addition to getting pipettes from manufacturers, these pipettes can be made in the lab using a micropipette puller. Refer to Sutter pipette cookbook to determine the settings required for pulling different types of pipette. These pipettes need to be fire-polished (or flame-polished) to smoothen the surface.

In addition, holding pipette can be generated by briefly exposing micropipette to flame (or via microforge for more precision under microscope observation).

Fig shows fire-polished glass micropipette or pipette. Taken from Nature Publishing.

Fig shows microforge used for processing micropipettes. Taken from Tritechresearch.

A video showing how to process micropipette using microforge and grinder.

Equipment available in the following links

• Narishige needle processing catalog by Tritechresearch
• Sutter Instrument micropipettes fabrication tools.
• Leica DMi8 microscope for micromanipulation.

Solved: How to disable highlighting new programs in Windows 7, Vista & XP

Thanks to HowToGeek instruction, I was able to disable the annoying persistent highlight of new programs installed in Windows 7. Refer to the post here with pictorials.

First, move mouse cursor to taskbar, right click to bring out a menu option, then go to properties. Click on the Start Menu tab. Click on Customize… (to customize how links, icons, and menus look and behave in the Start Menu). Scroll down a list and search for “Highlight newly installed programs”. Deselect that. Done.

Scientific misconduct and recent cases

I followed the first one about a Japanese researcher Haruko Obokata who was suspected of spiking her work with stem cells from other sources to suggest that she could induce inducible pluripotent stem cells iPSCs by stressing normal cells (or somatic cells).

Recently, another case in the US about a researcher Dong Pyou Han who spiked his rabbit blood samples with human antibodies to suggest that vaccine injected to the rabbits was able to induce immune response against the vaccine against HIV.

For the latest case, the perpetrator got a prison sentence.

XIST and pol III in XCI

X-chromosome inactive specific transcript (or Xist) is involved in X chromosome inactivation (XCI).
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Silencing or kd of Xist in somatic cells only produces low level reactivation in XCI.
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Those reactivated XCI transcripts are non-coding and upstream of the regulatory region contains SINEs (Short-INterspersed repetitive Elements targeted by RNA pol III).
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Involvement of RNA pol III?
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Kd of RNA pol III changed chromatin epigenetic landscape. A promising sign.
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Refers to work by Prof Zhang Li-feng (Nanyang Technological University)

Mnemonic for nucleotide nomenclature

This information is procured from "Nucleotide Nomenclature and Symbol" (In Biological Sciences).

Mnemonic for nucleotide nomenclature and symbol. The letters cap and underlined are the symbols. E.g. W represents Adenine and Thymine (or W = A or T), K represents Guanine and Thymine (K = G or T).

Information unfriendly commercial companies

I get it, that secret ingredients are what makes commercial companies thrive.
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Unfortunately, kits with minimal information is not helping students understand the concept behind workability of the kit (or approach). It is a disservice to Science and knowledge.
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I never liked companies that provided less-to-no information about their products. I shun away from these companies to save myself from being made into a technical person who follow instructions.
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Some companies are friendlier while others are protective of self-interest.
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For those who want to learn more about kits, the ideal place to look would be via patent files. Google is one place to start.
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Just to share.

Estimate the molecular/formula weight of DNA based on its length in base pair (bp)

This is just an estimation, i.e. 650.
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How to calculate Molarity and Number of DNA molecules

• Calculate the molecular weight of DNA molecule

A double stranded DNA of 100 bp will have an estimated molecular/formula weight = 100 bp x 650/bp = 65,000. Note that 650 is the molecular weight of one base pair.
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• Calculate the Molarity of DNA solution

To calculate molarity of DNA, e.g. 100 µg/ml (equivalent to 0.1 g/l) of 100 bp DNA will corresponds to 0.1/65000 Molar = 1.5 µM DNA (equivalent to 1.5 µmol/l).
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• Calculate the number of DNA molecules in a volume of DNA solution

To calculate the numbers of DNA molecules in 1 µl (equivalent to 1 x 10^-6 l) of 1.5 µM DNA, use the Avagadro number to convert mol to the number of molecules. First, determine the mol of DNA in 1 µl of 1.5 µmol/l DNA solution, e.g. 1.5 x 10^-6 x 10^-6 = 1.5 x 10^-12 mol. Next, determine number of DNA molecules, e.g. 1.5 x 10^-12 x 6.023 x 10^23 = 9.03 x 10^11 DNA molecules. That is equivalent to 0.9 trillion DNA molecules.
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• Calculate the number of DNA molecules based on mass

If I have a mass of DNA molecule, e.g. 135 pg of 500 bp dsDNA, how many DNA molecules is there? First, determine the molecular weight, i.e. 500 bp x 650/bp = 325,000. Note that 135 pg is equivalent to 135 x 10^-12 g. Next, determine the mol of DNA, i.e. 135 x 10^-12 / 325,000 = 4.15 x 10^-16 mol. In a mole, there is 6.023 x 10^23 molecules, thus the amount of DNA molecules is 4.15 x 10^-16 x 6.023 x 10^23 = 250 million DNA molecules.
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This is for my own reference.