Archive for July, 2014

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UV Trans-Illuminator

July 22nd, 2014

Ultraviolet (UV) Trans-illuminators are used to visualize fluorescent markers that are used in gel electrophoresis like agar gel electrophoresis for nucleic acids (DNA, RNA) and SDS-PAGE for proteins.

UV transilluminators are usually consist of a UV light source and associated electronics housed in a box with appropriate optical filters. For safety purpose it has a light transmitting cover with UV filter that transmits visible light to allow gels to be viewed. All UV trans-illuminator are major sources of UV radiations which can cause damage to skin and eyes of an individual. The use of UV trans-illuminator should be replaced whenever practicable by the use of blue light trans illuminator and appropriate dyes.

Risks from Radiation from UV trans-illuminator

These devices emit high level of UV radiations. UV radiation are mutagenic and cancerous, they can cause the mutation (UV radiations are responsible for the formation of dimers in DNA strands). Working unprotected for even a few minutes can cause injury, so it is required to use safety precautions while working with UV trans-illuminator. Effects of UV can occur within a short period (Photokeratitis and Erythema) or a long period after exposure (skin cancer).

  • Radiations from these UV trans-illuminators may have the potential effects on eyes (photokeratitis, photoconjunctivitis and cataracts) and
  • can cause skin erythema (sunburn like condition), elastosis ( photoaging and skin cancer).
  • Hands, arms, face and eyes are likely sites of injury.

Some individuals have greater than usual photosensitivity. It is possible to calculate acute threshold for acute effects and therefore set exposure limits, however it is not possible to do so for chronic effects, therefore there is no safe exposure level and exposure should be reduced as much as possible.

Safety Guidelines While Using the UV Trans-Illuminator

UV Trans-illuminator is the source of UV radiations which can be harmful for a personnel doing the experiment so it is required to consider the safety precautions.

  • Always avoid looking directly into the UV light. Only observe through the UV safety cover provided in the trans-illuminator if possible wear UV blocking spectacles during observation.
  • Do avoid unnecessary exposure to eyes or skin. There is no safe exposure level to avoid skin cancer.
  • While putting the gel in the UV trans-illuminator the personnel should wear the gloves as UV radiations are mutagenic.
  • All the skin areas that are exposed must be covered including the wrist area upto the end of the lab coat sleeves.
  • Appropriate shield (protective cover) should be used to prevent irradiation of the eyes and skin. An appropriate material for shield is Perspex.

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Tissue Culture Microscope

July 15th, 2014

A microscope consists of a compound light microscope with high power objectives facing upward is known as tissue culture microscope. This is also known as inverted tissue culture microscope because the objective faces upward.

This inverted design of objective piece is required because the microscope is used to view the bottom of a Petri dish or flask since the culture is growing on the bottom of the dish. The higher the power of objective, the closer the objective needs to be to the specimen.

These microscopes are very expensive but are easy to operate. They provide useful information about the morphology and state of the cell by visualizing the cell with the help of these microscopes so that early signs of cell stress may be easily identified and appropriate action can be taken to prevent loss of cultures.

Cell/tissue removed from an organism, will continue to grow if they are supplied with the appropriate nutrients and conditions. When this process is carried in laboratory or in vitro the process is known as tissue or cell culture.

Plant Tissue Culture

Plant Tissue Culture refers to the culture of plant tissue/cells and organs such as root, shoot tips and leaves in artificial nutrient media aseptically.Growth and morphogenesis of tissue/cells in vitro are largely governed by composition of culture media.

Culture media used for the in vitro cultivation of plant cells are composed of following components

  • Essential elements, or minerals, supplied as a complex mixture of salts;
  • An organic supplement supplying vitamins and amino acids
  • A source of fixed carbon; usually supplied as the sugar sucrose
  • A gelling agent
  • Growth regulators (Auxins, cytokinines, Gibberellins, Abscisic acid and Ethylene)

Plant Tissue Culture is of many types such as callus culture, cell-suspension culture, protoplast culture, organ culture, meristem culture, root culture, embryo culture, haploid culture, anther culture and ovary culture.

Some important Applications of Plant Tissue Culture

Clonal Propagation; Multiplication of genetically identical copies of a cultivar by asexual reproduction is called clonal propagation. A population derived from a single individual by asexual reproduction constitutes a clone. Clonal propagation through tissue culture is known as Micropropagation.

Production of Virus free plants; infection can be eliminated by micropropagation of unaffected parts of plants. The basic method of production of virus free plant is culture of apical meristems.

Artificial seeds; somatic embryos may develop in vitro through embryogenesis. These can be preserved through the preparation of artificial seeds.

Production of secondarymetabolites; chemical molecules such as alkaloids, resins, tannins, latex, these chemicals are known as secondary metabolites. Their function is mainly associated with the defense against of pests and pathogens. By utilizing tissue culture technique these chemicals are produced in large scale.

Animal Tissue Culture

Cells in animals exist in an organized tissue matrix which require for their controlled growth and differentiation. These cells from intact organisms may be isolated, maintained and grown in vitro in culture media aseptically containing suitable mixtures of nutrients and growth factors, this process is called Animal Tissue Culture.

Some major applications of Animal Tissue Culture

Model System; animal cell culture provides a good model system for studying

  • Basic cell biology and biochemistry
  • Effects of drugs on cells
  • Interactions between diseases causing agents and cells
  • Nutritional studies

Cancer Research; since both normal and cancer cell can be grown in culture so there differences can easily be studies

Virology; replication of virus in cell culture for the production of vaccines.

Toxicity testing; cultured cells are widely used alone or in conjuction with animal tests to study the effects of new drugs, cosmetics and chemicals on survival and growth of cell.

Applications areas of Tissue Culture Microscope

  • Cellular biology
  • Molecular biology
  • Biology classroom equipment
  • Microbiological study
  • Environmental research
  • Medical diagnostics
  • Medical research

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Thermo Hygrograph

July 8th, 2014

A Thermo Hygrograph is a scientific instrument which measures the Temperature and Humidity and plots it on a chart. It monitors the environmental changes. Thermo Hygrographs are used to produce a continuous record of the variation of both the Temperature and Relative Humidity of the atmosphere against time, by drawing colored traces on a chart.

Thermo Hygrograph is portable, accurate and easy to operate. Variations in Relative Humidity can affect many manufacturing processes, storage of raw materials, weights of items such as wool, paper, tobacco, confectionery, and computer operation, as well as being an important factor in human comfort. Since Temperature is often linked to changes in Relative Humidity, this instrument records both on a single chart.

Thermo Hygrograph requires ongoing maintenance to ensure that they are recording accurately and to ensure that the cylinder is rotating at the right rate. And Thermo Hygrograph also needs to be calibrated periodically.

Principle

Thermo Hygrpgraph works on the principle that organic materials expand and contract as the Relative Humidity changes. In this case, the organic material is Human Hair (it is need to be reconditioned).

The hairs are bundled together and stretched between a fixed pin and movable pin. The movable pin is attached to a series of levers, which amplify the movement of the hairs. A pen is attached to the end lever, and this pen plots the movement of the lever on a chart, which is mounted on a rotating cylinder. The rate of rotation can be altered, so that the Relative Humidity is plotted over a day, a week or a month.

It also has a Temperature Sensor which records the Temperature on same chart. The chart should be changed at the end of each recording period and the pen should be set on the correct line.

Advantages

  • It measures the temperature and relative humidity of
  1.  Museums
  2.  Libraries
  3. Storage Areas
  • It gives the relationship between humidity and temperature.
  • The chart also shows when fluctuation occurred, so one can relate fluctuation to events in the area being monitored, e.g. the arrival of a bus load of tourists on a wet day.

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