| BIOL-100 |
Biological Techniques
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The wool-producing ‘factory’ is the 50 million or so follicles embedded in the skin of sheep. This theme covers in detail, how these follicles form, what cellular and molecular processes produce the fibre, how genetics and nutrition affect these processes, and how genetic engineering might be used to produce a better fibre. With an understanding of the biology of the skin and the fleece, the characteristics of the wool follicle and fibre can be related to production, technology and the processing of wool. |
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Topics within this theme examine and explain techniques which have been established to measure fibre growth, cell division rates and, detection and testing of molecules involved in follicle function. |
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You can download all presentations for each Topic as PPT presentations within a compressed archive (.ZIP) using the link provided for each Topic. You can preview the PPT presentation for each Module in PDF format using the link provided for each Module. The PDF does not include the notes.
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| BIOL-100-100 |
Techniques to measure fibre growth |
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This topic describes techniques used to facilitate wool growth research that allow a high degree of control over growth conditions and that allow measurement of wool growth over short periods of time. |
| BIOL-100-100-100 |
Microscopy in Wool Biology |
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To ascertain whether factors are affecting wool production and quality it is essential that something can be measured to determine the degree of change. Likewise to study the structure of the wool fibre, the skin and its follicles it is important that we can see these microscopic features. This module describes the microscopes that are routinely used to examine wool growth and quality and the wool follicle. Images from the light microscope, transmission and electron scanning microscopes are supplied. |
| BIOL-100-100-200 |
Wool growth measurement |
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This module describes methods that are routinely used to measure the effects of various factors on wool growth and quality, including midside patch production, dye-banding and autoradiography. Photos of each technique are provided. |
| BIOL-100-100-300 |
In vitro follicle culture |
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This module describes an in vitro follicle culture technique than can be used to measure short term effects of various factors on the wool follicle. |
| BIOL-100-200 |
Techniques to measure cell division |
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The modules in this topic deal with techniques for measuring the rate of cell division in wool follicles. Cell division is the driving force behind fibre growth. |
| BIOL-100-200-100 |
Estimating cell division rate |
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This module is a summary of the main methods used to establish the proportion of the population of cells which are in a particular stage at a certain time that may affect wool growth and quality. These methods may be used to determine cell cycle times, or cell division rate or cell birth rate. Results of cell division rates estimated using two methods (stathmokinetics and nucleoside labelling) are compared. Further details can be found in the modules “Estimating cell population kinetics using BrdU” and “Estimating cell population kinetics using colchicine”. |
| BIOL-100-200-200 |
Estimating cell division rate using cell cycle manipulation with colchicine |
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Since cell division is essential for follicle function and fibre formation it is necessary to understand how cells replicate. This module provides a brief summary of stathmokinetic methods used to estimate cell division rate. Photomicrographs of sheep skin that has been injected with colchicine are provided. |
| BIOL-100-200-300 |
Estimating cell population kinetics using nucleoside labelling (BrdU) |
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Determination of cell cycle times/cell division rate/cell birth rate is useful for understanding the controls of wool production. One method that has been used to examine the length of the cell cycle and cell division rate in sheep utilises immunocytochemistry (see “Immunocytochemistry” module). This module examines aspects of this method using BrdU to estimate cell birth rate and shows a photomicrograph of cells that have been labelled with BrdU. |
| BIOL-100-300 |
Molecular Biology Techniques |
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A range of sophisticated techniques is now available that allow precise detection of molecules involved in follicle function. These are described in these modules. |
| BIOL-100-300-050 |
Molecular detection |
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To understand many aspects of wool biology and how wool biology may impact on wool production, a basic understanding of molecular biology is required. There are many techniques that are used in molecular biology. This module describes the techniques used to detect molecules of interest. Molecules of interest include proteins, RNA and DNA. The methods all involve similar principles of blotting and detection. DNA detection was first developed by Southern and hence DNA detection is called Southern blotting. Later, detection of RNA was developed and called Northern blotting and protein detection was named Western. This module describes Southern blotting but the same basic principles apply for Northern and Western Blotting. |
| BIOL-100-300-100 |
Detecting and testing molecules involved in follicle function |
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To understand the formation, initiation and development of follicles it is useful to study other organs that develop in a similar way. Epithelial-mesenchymal interactions are essential for follicle initiation and a number of molecules have been implicated in follicle initiation and development. This module describes the molecular strategies used for testing the proposed developmental roles for these molecules. |
| BIOL-100-300-150 |
Gel electrophoresis |
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This module describes gel electrophoresis which is the bread and butter of a molecular biologist. Agarose Gel electrophoresis allows strands of DNA to be separated according to size. It is perhaps the most fundamental technique of a molecular biologist. It not only enables DNA to be separated according to size, it also allows DNA to be visualised. This is extremely important because DNA is not normally visible at the amounts we use and you certainly can not pick it up and check whether the sticky ends are complementary or not and then join them together. So we need to be able to track the DNA and see whether if we put two fragments we suspect have similar ends together with ligase (see “DNA modification enzymes” module), they do actually join. If we run the ligation on an agarose gel and the fragments have joined we would see that the size of the fragment is equivalent to the combined length of the two fragments. If they do not join then we should see two separate bands of smaller size. |
| BIOL-100-300-200 |
Two-dimensional gel electrophoresis |
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This module expands on the “Gel Electrophoresis” module and describes performing gel electrophoresis in a second direction. This method is commonly used to examine proteins in keratin fibres. |
| BIOL-100-300-250 |
In situ-hybridisation |
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This module describes the process of and shows a photomicrograph of in situ hybridisation. This technique is used to localise where DNA or RNA is present in a tissue. So unlike blots where the tissue of interest is homogenised, in situ hybridisation allows the exact location of a particular DNA or RNA to be identified on a tissue sample with a microscope. |
| BIOL-100-300-300 |
Polymerase chain reaction (PCR) |
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This module describes the polymerase chain reaction (PCR) that is used to increase the amount of DNA from as little as one copy to many copies of a strand of DNA. |
| BIOL-100-300-350 |
Immunocytochemistry |
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Immunocytochemistry (ICC) is a technique that allows proteins, carbohydrates, nucleic acids, lipids and many other compounds (both natural and synthetic) to be visualised. In fact, any compound that can be used as an antigen against which antibodies can be used can be viewed by ICC. ICC exploits the specific binding that occurs in an antigen-antibody reaction (“immuno-“). A marker that is visible microscopically is then attached to the antibody. The marker may be a fluorescent dye, an enzyme or colloidal gold. A microscope (either light or electron) is then used to identify the cells in which the antigen-antibody complex is present (“-cytochemistry”). This module illustrates the general ICC principles that are used in wool biology. |
| BIOL-100-300-400 |
The Reaction Diffusion System |
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There are a number of mechanisms and processes that cause cells to behave differently to their neighbours. Experiments to examine the mechanism responsible for follicle initiation and fibre formation include morphological observations, epidermal/dermal recombinations, chemical modifications, mechanical modifications, genetic modifications and changes in gene expression patterns. By taking these results into account, models/theories can be developed to explain follicle initiation and fibre formation. One of these, the reaction diffusion theory, has been used to explain wool follicle initiation and fibre formation. This module describes the reaction diffusion (RD) system. |