eChapters

Sister Chromatid Exchange and Homologous Recombination

The staining of harlequin chromosomes can reveal recombination between sister chromatids

The holliday model describes a molecular mechanism for the recombination process

More recent models have refined the molecular steps of homologous recombination

Various proteins are necessary to facilitate homologous recombination

Gene conversion may result from DNA gap repair synthesis or DNA mismatch repair

General Effect of Mutation

Gene mutations are molecular changes in the DNA sequence of a gene

Gene mutations can alter the coding sequence within a gene

Gene mutations are also given names that describe how they affect the wild-type genotype and phenotype

Gene mutations can occur outside of the coding sequence and still influence gene expression

DNA sequences known as trinucleotide repeats may cause mutation

Changes in chromosome structure can affect the expression of a gene

Mutations can occur in germ line or somatic cells

The Structure of Proteins

Proteins are composed of building blocks called amino acids. A string of amino acids is called a polypeptide chain. Once such a chain has folded into its working three-dimensional shape, it is a protein. Though there are tens of thousands of different proteins, all of them are put together from a starting set of 20 amino acids. It is the order in which the amino acids are linked in a polypeptide chain that determines which protein will be produced.

The Genetic Basis for Protein Synthesis

Archibald Garrod proposed that some genes code for the production of a single enzyme

Beadle and Tatum’s experiments with Neurospora led them to propose the one gene-one enzyme hypothesis

During translation, the genetic code within mRNA is used to make a polypeptide with a specific amino acid sequence

Exceptions to the genetic code are known to occur, which include the incorporation of selenocysteine and pyrrolysine into polypeptides

Synthetic RNA helped to decipher the genetic code

The use of RNA copolymers and the triplet binding assay also helped to crack the genetic code

A polypeptide chain has directionality from its amino terminal to its carboxyl terminal end

The amino acid sequences of polypeptides determine the structure and function of proteins

Cellular proteins are primarily responsible for the characteristics of living cells and an organism’s traits

Overview of Transcription

Gene expression requires base sequences that perform different functional roles

The three stages of transcription are initiation, elongation, and termination

RNA transcripts have different functions Transcription in Bacteria

A promoter is a short sequence of DNA that is necessary to initiate transcription

Bacterial transcription is initiated when RNA polymerase holoenzyme binds at a promoter sequence

The RNA transcript is synthesized during the elongation stage

Transcription is terminated by either an RNA-binding protein or an intrinsic terminator

Identification of DNA as the Genetic Material

Experiments with pneumococcus suggested that DNA is the genetic material

Hershey and Chase provided evidence that the genetic material injected into the bacterial cytoplasm is T2 phage DNA

RNA functions as the genetic material in some viruses Work Before Watson and Crick

Nucleotides are the building blocks of nucleic acids

Nucleotides are linked together to form a strand

In 1869, Miescher first isolated DNA and named it “nuclein.”

In 1902, Archibald Garrod linked heredity to enzyme (protein) defects. In 1909 he published a book entitled “Inborn Errors of Metabolism.”

In 1928, Griffith identified a “transforming factor” that transmitted infectiousness in bacteria.

In 1944, Avery, MacLeod and McCarty showed that the transforming factor was DNA)

In 1950, Hershey and Chase, using their famous “blender” experiment, confirmed that DNA, not protein, is the genetic material.

The work of chemist Phoebus Levene showed that DNA includes deoxyribose, nitrogenous bases, and phosphates, in equal proportions.

Chargaff s data showed that the number of purines equals the number of pyrimidines.

Using Rosalind Franklin’s X-ray diffraction patterns, Watson and Crick deduced that DNA is a double helix

Variation in Chromosome Structure

Natural variation exists in chromosome structure

Changes in chromosome structure include deletions, duplications, inversions, and translocations

The loss of genetic material in a deletion tends to be detrimental to an organism

Duplications tend to be less harmful than deletions

Duplications provide additional material for gene evolution, sometimes leading to the formation of gene families

Copy number variation is relatively common among members of the same species

Comparative genomic hybridization is used to detect chromosome deletions and duplications

Inversions often occur without phenotypic consequences

Inversion heterozygotes may produce abnormal chromosomes due to crossing over

Translocations involve exchanges between different chromosomes

Individuals with reciprocal translocations may produce abnormal gametes due to the segregation of chromosomes

Portrait of a Chromosome

• Cytogenetics is the study of chromosome abnormalities and associated effects on health or other traits.
• Excess or deficient genetic material can cause syndromes or end prenatal development.
• Chromosomes consist of highly coiled DNA, RNA, histones, and nonhistone proteins.

Telomeres and Centromeres are Essential

Telomeres consist of repeat sequences and protect chromosome tips.

A centromere is a constricted site where spindle fibers attach during cell division.

Centromeres are regions of repeated DNA bound to centromere-associated proteins.

Sex Chromosomes

Sex can be considered at chromosomal, gonadal, phenotypic, and gender identity levels.

Human females are homogametic (XX) and males are heterogametic (XY).

The Y chromosome contains few identified genes, while the larger X chromosome contains several thousand genes. Pseudoautosomal regions at both tips of the Y chromosome contain genes that have counterparts on the X chromosome.

The male determining gene, SRY, has been found on the Y chromosome.

Genetic Transfer and Mapping in Bacteria a

Bacteria can transfer genetic material during conjugation

Hfr strains contain an F factor integrated into the bacterial chromosome

Hfr strains can transfer a portion of the bacterial chromosome to recipient cells

Conjugation experiments can map genes along the E. coli chromosome

A genetic map of the E. coli chromosome has been obtained from many conjugation studies

Bacteria may contain different types of plasmids

Bacteriophages transfer genetic material from one bacterial cell to another via transduction

Cotransduction can be used to map genes that are within 2 minutes of each other

Bacteria can also transfer genetic material by transformation

Bacteria may acquire new genes by horizontal gene transfer

Linkage and Crossing Over

Crossing over may produce recombinant phenotypes.

Bateson and Punnett discovered two traits that did not assort independently.

Morgan provided evidence for the linkage of several X-linked genes and proposed that crossing over between X chromosomes can occur.

A chi square analysis can be used to distinguish between linkage and independent assortment.

Creighton and McClintock correlated crossing over that produced new combinations of alleles with the exchange of homologous chromosomes.

Crossing over occasionally occurs during mitosis. Genetic Mapping in Plants and Animals

The frequency of recombination between two genes can be correlated with their map distance along a chromosome

Alfred Sturtevant used the frequency of crossing over in dihybrid crosses to produce the first genetic map.

Trihybrid crosses can be used to determine the order and distance between linked genes.

Interference can influence the number of double crossovers that occur in a short region.

Genetic Transfer and Mapping in Bacteria

Bacteria can transfer genetic material during conjugation

Hfr strains contain an f factor integrated into the bacterial chromosome

Conjugation experiments can be used to map genes along the E. coli chromosome

A detailed genetic map of the E. coli chromosome has been obtained from many conjugation studies

Bacteriophages can also transfer genetic material from one bacterial cell to another in the process of transduction

Cotransduction can be used to map genes that are within 2 minutes of each other

Bacteria can also transfer genetic material by transformation

Horizontal gene transfer is the transfer of genes among different species

When Gene Expression Appears to Alter Mendelian Ratios Lethal Allele Combinations

Us recessive lethal alleles eliminaters a progeny class. Multiple Alleles

A gene can have more than two alleles, but a diploid individual only has one or two of them.

Different allele combinations can produce different phenotypes and different severities of symptoms.

Different Dominance Relationships

Incomplete dominance of an allele produces a phenotype in the heterozygote that is intermediate between that of either homozygote.

Codominant alleles are both expressed in a heterozygote. Epistasis-When One Gene Affects Expression of Another

In epistasis, one gene masks the effect of another. An example of epistasis in humans is the Bombay phenotype.

The Bombay phenotype results in O type blood for individuals homozygous recessive for the recessive “h” allele.

About Mendel

Born in what is now the Czeck Republic.

Grew up in an agricultural environment.

Became a priest-teacher at a local monastery.

Took courses in botany, physics, and mathematics at the University of Vienna.

Gregor Mendel was the first person to comprehend some of the most basic principles of genetics. He reached these understandings in the mid-nineteenth century; working in what is now the Czech Republic and using as his experimental subjects a species of garden pea, Pisum sativum..

Carried out “hybridization” experiments with the common garden pea.

Mendel’s hypotheses became the laws of inheritance in modern genetics.

Mendel’s work re-discovered by Correns, DeVries, and Tschermak in 1900. Period of modern “Mendelian” genetics begin.

Cells are the Working Units of Life

With the possible exception of viruses, every form of life on Earth either is a cell or composed of cells. All cells come into existence through the activity of other cells.

All Cells are either Prokaryotic or Eukaryotic

All cells can be classified as prokaryotic or eukaryotic. All plants, animals, fungi, and protists are either single eukaryotic cells or are composed of eukaryotic cells. Prokaryotic cells are either bacteria or archaea. Eukaryotic cells have most of their DNA contained in a membrane-lined nucleus, whereas prokaryotic cells do not have a nucleus. Eukaryotic cells also have more specialized structures, called organelles, than do prokaryotic cells. All prokaryotes are single-celled, whereas many eukaryotes are multi-celled.

The Eukaryotic Cell

There are five principal components to the eukaryotic animal cell: the nucleus, other organelles, the cytosol, the cytoskeleton, and the plasma membrane. Organelles are “tiny organs” within the cell that carry out specialized functions, such as energy transfer and material recycling. The cytosol is the fluid in which these organelles are immersed (The cytoplasm is the region of the cell inside the plasma membrane but outside the nucleus.) The cytoskeleton is composed of several groups of proteins that give the cell support and facilitate transportation of cellular elements. The plasma membrane is the chemically active outer boundary of the animal cell. Plant cells have a plasma membrane that has, outside of it, a cell wall.

A Overview

Genetics is a branch of biology concerned with heredity and variation.

Genes are the unit of inheritance and are composed of DNA.

The effects of genes are noticeable at the molecular, cellular, family, and population levels.

Genes are DNA sequences that instruct cells to produce particular proteins, which in turn determine traits.

Genes can exist in more than one form and the variants of a gene arise by mutation.

An allele is a variant of a gene that alters its expression in a detectable way. Alleles can be dominant or recessive.

A polymorphism is a particular sequence of DNA that varies in one percent or more of the population.

Single nucleotide polymorphisms are single base pair sites that differ among individuals.

Chromosomes consist of genes and associated proteins.

The human genome consists of 22 pairs of autosomes and one pair of sex chromosomes.

A karyotype is the photographic catalog of the human chromosomes.

Specialized cells and tissues arise by differentiation from the stem cells of the early embryo.

Pedigree diagrams enable recessive and dominant traits to be followed through multiple generations of a family.

A gene pool is the collection of alleles in a population.

Comparative genomics is leading to a more detailed and subtle understanding of evolutionary relationships among species

NATIONAL LEVEL FACILITIES OF LABORATORY ANIMALS

• National Laboratory Animal Centre, Central Drug Research Institute, Lucknow.
• National Centre for Laboratory Animal Sciences (NCLAS) National Institute of Nutrition, Hyderabad

INSTITUTIONAL LABORATORY ANIMAL FACILITIES AT

The term Anesthesia means loss of sensation.

GENERAL ANESTHESIA

In the technique of anesthesia, a drug is capable of causing loss of sensation together with loss of consciousness, sufficient to allow a surgical operation to be carried out.

Routes of General Anesthesia (G.A.)
Inhalation

Ether, Nitrous oxide, Halothane, Chloroform etc.

Reproductive is fundamental property of living beings. While lower animals reproduce by simple methods, the higher animals attain greater degree of animals reproduce by complexities in the reproductive functions. Basic units (Gonads) of males and females are testis and ovaries respectively. The gonads of each sex perform dual roles:

• Formation of gametes (sperms by testis and ovum by the ovaries)
• Production of hormones.

Role of Hormones in Reproduction

Accurately in the clinical diagnosis of a disease in experimental animals frequently depends on the result of laboratory examination of blood specimen from the diseased animals. A prerequisite for good experiment result is the proper collection and handling of the blood samples. If properly collected samples can not be sent to the laboratory quickly. It must be preserved or stored in such a manner that the necessary tests may be conducted. The technician/researchers

Going to collect the blood from a laboratory animal should be aware of the purpose of blood collection, the sites of blood collection, the technique of blood collection, the Use of various anti coagulants, the techniques of blood examination.

Blood Examination of Animal may be Necessary

ETHICS OF ANIMAL USE IN RESEARCH

• The use of animals in scientific research is a controversial issue. Animals have been used throughout the history for anatomical and physiological research as well as for testing toxic substances.
• Many medical advances, including vaccines for polio and rabies, the development of certain antibiotics, anti cancer agents and transplant medicine have been developed by using animals in research.
• But the question is whether it is right or wrong to use animals for these purposes.
• All scientists working with laboratory animals must have a deep ethical consideration for the animals they are dealing with.
• From the ethical point of view it is important that such considerations are taken care at the individual level, at institutional level and finally at the national level.

What are Ethics ?

INTRODUCTION

Rabbit production is the upcoming livestock farming throughout the world. The domestic rabbit are raised meat, fur –skins and wool. Climatic condition of Karnataka are not favourable for raising wool breeds of rabbits, but are definitely well for broiler rabbit production.

Rabbits require less space for housing and highly prolific. Initial investment for rabbits farming is very less and maintenance cost is also very low. There is no religious barriers in rabbit meet consumption and rabbit meat contains very low cholesterol when compared to the other meats.

Rabbit farming can be very well fit into mixed farming systems. It can be adopted by small and marginal for maximum utilization of lands and resources, and to derive substantial income under rural condition.

Important by product from Rabbit are meat, wool, planner and skin. It can be made highly profitable if products are properly processed and marketed. Many rabbit products are wasted because people do not have enough knowledge about their processing. Rabbit farming is profitable preservation of its by-product.

Slaughtering: Know when and how.

Slaining: Familiar with how to remove skin and carcass preparation and processing. How the skin has to be processed into a product from the skin obtained.

Manure: Know how to collect and preserve it.

Introduction

Germfree (GF) animal is one which is isolated from all demonstrable living microorganisms like bacteria, virus, fungus, parasite, algae, yeast. The aim of GF work is isolation (Prevent contamination from air, water, food and environment). It can be attained mechanically and scientifically. GF animal research began in 1895 but in 1897 Nuttall and Thierfelder started to rear GF guinea pigs in their lab. Chicks are classical animal for GF research. Rats and mice are reared through reproduction. Permanent breeding colonies of these have been established.

Synonyms : Axenic animal –meaning free from strange. Gnotobiotic – known life derived from Greek word-Gnoto & biota means known flora & fauna.

Gnotobiote (Gnotobiotic animal ) : Is an animal derived by aseptic caesarian or sterile tatching of eggs that is restored & continuously maintained with Germ free technique under isolator condition in which flora & fauna is clearly defined.

Flora animal: A gnotobiote maintained under isolator condition in international association with one or more known types of microorganisms.

Committee recognized throughout world on laboratory animal called International Committee on Laboratory Animal (ICLA) This committee is responsible to make the rules and regulations and laws which governs production, maintenance and usage of laboratory animal. This committee has defined Specific Pathogen Free (SPF) animal which are free of specified micro organisms and parasites but not necessarily free of the ones which are not specified. Example pasteurella free SPF animal.

Synonyms of SPF Animals

• Disease free animal
• Healthy animal
• Pathogen free animal
• Clean animal
• Caesarian derived animal

The main aim for the production of GFA is for isolation of animal free of all organism.

Objectives

To acquaint with the various methods of sterilization and disinfection used in laboratory animals.

Materials Required

Boiler, autoclave, hot air oven, chemical disinfection.

Sterilization

It is a process of the complete removal or destruction of living organisms including viruses, vegetative forms and spores. Sterilization is an absolute term. Nothing can be “partially sterile’’, either, it is or it is ‘not’. An article must be protected from recontamination after sterilization.

Objectives

• To keep the laboratory animal house neat and clean
• To maintain healthy stock

The disease may be bacterial, viral, fungal or of parasitic origin. All the measures taken to reduce growth and also to control spread of pathogenic organism is a sanitary measure like ventilation, building without cracks crevices.

Important aspect of good sanitation is insect control or pest control. Most effective measure is to just chase them out. To achieve this :

COMPOSITION OF DIET

Objectives

• To study the general considerations on feeding aspects of laboratory animals.
• To get acquainted with the specific nutritional requirements of laboratory manures.
• To familiarize with the watering system.
• To know the daily feed schedule of different species of laboratory animal.

Materials Required

Laboratory animals, feed ingredients, water, green vegetables.

For having good growth and production, proper balanced diet should be fed, thus nutrients can be classified into 6 classes:

RECORD KEEPING

Objectives

• To carry out the routine activities of animal house
• Breeding of animals

Materials required- Different types of record

Proper record keeping is very important and it is also highly essential to carry out the animal house activity in a systematic manner. The records should be simple, complete and should preferably be computer compatible.

The records are kept and maintained in different forms. Unnecessary information should be avoided in these records. The records of breeding, experimental animal and morality of animals are highly essential. Other records are:

IDENTIFICATION OF ANIMALS

It has been in practice since long, not recent item in livestock farming. In earlier day’s in Egyptian era, people used to mark the animal to identify their animals. But in recent days, due to development in bio-medical science where usage of animal has increased within turn has become necessary to establish a suitable identification method for various species of animal. There are many methods available to identified animal, however the methods employed should be simple, economical and easy to identify animal and should be harmless to animal, quickly applicable and should be suitable to experiment conducted.

HOUSING OF LABORATORY ANIMALS

Objectives

The important criteria to be kept in mind for the construction of animal house are:

• Got to satisfy the requirements of animal care takers and animal technician whose place of work it is.
• Got to satisfy animals which are house in animal house.
• Research workers who conduct research on animal in the laboratory should be satisfied.

Materials required- Small animal house, Animal colonies, type of cages and equipments.

HANDLING OF ANIMALS

Objectives

• For carrying or shifting the animal
  Sexing the animal – to know the sexing of animal.
• Administration of substances
  To conduct experiments.

Materials required – Laboratory animals, apron, tattle and clean towel, weighing balance.

IDENTIFICATION OF BODY PARTS

Objectives

To become familiar with external parts of the body

Physical examination

Administration of medicine or substances
Oral administration : can be done with the help of syringes or stomach Tube. In large animals, mouth gag is used before passing stomach tube.

MANAGEMENT

Management includes housing, feeding, disease control.

India is rich in bird population → 8650 species distributed through more than 2000 species are found in India alone. This is due to diversity of habitat and favourable climate condition.

Birds population is restricted to Rajasthan and Himalayan region i.e., in desert, hilly region, forest and also in grass lands → habitat.

Diversity of habitat → mentioned in Rig Vedic period. Even people are distributed among different regions.

CATS

Cats are classified under family Felidae. Felidae is divided into 3 sub families.

False sabes (Toothed cats)

Felids (Cats → Felinae)

Big felids (Pantherine)

Felinae

28 species, have been classified in 15 genera.

Chromosome no 2n=38.

Exterior Morphology of Cats

LICENSE, REGISTRATION & INSURANCE FOR DOGS

To keep dog, license from local Municipality or Panchayat. Only when certified for vaccination against rabies is shown, license is given to rear dog.

Registeration of Pups

Pups from the registered parent should be registered as soon as it is born.

Pups should be registered with Kennel club. Registered usually where parents are registered. Immediately after the birth, pup should be registered.

Dog Show

Most registered Kennel clubs conduct Dog show. They allow the dog to participate only if it is registered with the club. Usually Kennel club avoid prizes to animal. To give prize, they should have the following classification :

Adult female is called bitch and adult male is called dog.

Female comes to heat which is called season. Comes to season for first time at 6-8 months of age. Smaller breeds mature faster than large breeds.

SYMPTOMS OF HEAT

Females in heat becomes nuisance to both owner and public since the animal becomes unmanageable, goes out of house and sometimes street male dogs gets into house because of peculiar pheromone smell.

Has different stages

HOUSING

Dogs are kept in cages and they are tied with a chain in one corner of the house or left free in the house → but hair falling will be seen throughout → allergy.

House in wire mesh all round and wooden flooring → gives warmth to animal. Roof can be made of asbestos sheet.

Cage → 2 ft LX 3 ft BX4 ft H. This should be kept in a cool place.

With cement covering all round with mesh door asbestos roofing.

Dog is always chained. This should be long enough and strong enough to withstand pulling of animal. Along with this collar is provided with strong buckles.

Docile animals can be left free in the house → Pomerian, Dash hound, Dobberman should be chained.

Petting too much leads to transmission of diseases → parasite and allergy.

Dogs, Cats and birds are pet animals.

Chromosome number of dogs-78

Good Angora breed yield wool of 2-2 ½ “ an average. On record, 8” of wool is also obtained.

Mainly reared for wool production. They require cooler environment to have better wool growth. The rearing is restricted to hilly regions where the weather is cool which helps in better wool production.

• Qualitative
• Quantitative

Quality-Length of the wool, texture of wool, shininess/ brightness of wool.

During marketing, classified into 3 categories:

Grade I → Rs. 1000/ kg

Grade II → Rs. 600-800

Grade III → Rs. 400-600

DISEASES OF RABBITS

The Disease Occurrence in rabbit colony is minimal if good sanitation and hygiene measures are followed.

Diseases are caused by Bacteria, Viral, Parasitic and managemental.

Bacterial Disease

Pasteurellosis → similar to Haemorrahgic septicaemia

Organism → Pasterurella multocida

Affects respiratory system with difficulty in breathing. Temperature 103 ° F Occulonasal discharge observed.

Lab → Blood smear shows bipolar organisms by Giemsa stain.

Treatment → Sulpha drugs, long acting tetracyclines.

CARE AND MANAGEMENT

Pregnant female should be fed with green, fresh vegetable, green leaves. Only with good management, healthy young ones can be expected. Similar to birds, rabbits have Nest building behaviour. Around 25 days of pregnancy, keep the pregnant animal in cage provided with bedding material separately. Around 28 days, the female makes nest by pulling the fur from abdominal region and also bedding material. The fur from abdominal region is pulled to make teats clean for young ones to suck milk. If female makes good nest, it can be concluded that it will be a good mother. Some females due to disturbance are unable to make nest and also abandon young ones, go astray.

Act of parturition in rabbit is kindling and it takes place in early hours of day and late evenings. Full process is completed in 90 minutes. In some females, aggressive behaviour is seen. Such aggressive females have good mothering ability.

Buck can be mated to several does not gives many young ones. So quality of buck will be passed on to many number of young one. Choose bucks whose relatives have good commercial character performance can be known by looking at breeding record should have too well development testicle, have good growth, good healthy condition, not be too fat, good physical condition.

Best time is when animal is 2 kgs of body weight and age of 3-4 months.

It is advisable to purchase buck from good reliable source since it brings new characteristics and avoid inbreeding.

The mating of the buck of particular breed with die of another breed is cross breeding usually cross breeding has better commercial value → Hybrids which has hybrid vigour → grow faster, better litter size.

Usually breeding of 2 hybrid is not advisable because we will not be sure which hybrid characteristics will be passed on to young ones.

The back yard rabbitry has mixed breeding programme of low quality with reference to commercial characteristics. To improve back yard rabbitry, good well known breeding buck should be introduced to have better performance.

Extension worker play a important role in rabbit keeping. It increases food production and experience in rabbit farming, people has to be educated as they have no knowledge of rabbit keeping especially people of towns and villages.

These have to be told the advantages of rabbitry. It is difficult to convince villagers, so extension is very important.

Rabbit Census : Recently taken up.

In Karnataka, census was taken in 1990. There were 16,327 animals.

GUINEA PIGS

Guinea Pigs are herbivores and they can be fed with green grass, vegetable wastes, sprouted grains and commercially available diet and diets made of locally available cereals, pulses. Guinea Pig are not able to synthesize vitamin C. So it has to be supplemented externally through diet and supplementation should be 120 mg of body weight.

Guinea Pig are highly fastidious animals (strict about their diet and their requirement i.e., they are choosy in their diet).

Minimum Requirement

Pr - 16-20%

Fat - 4%

CHO - 30-35%

Fibre - about 10%

Mice are omnivores and can be fed with commercial feeds like pellets or fed with mixed feed which is locally available cereal, pulses and grains.

However, nutritionally requirement of mice

Carbohydrates - 45-55%

Protein - 16- 24%

Fibre - 4-5%

Fat - 4-6%

Supplement vitamin and minerals.

Proper records can be maintained and individual performance can be noted.

Disadvantages: A number of males should be maintained which is not economical.

Advantages of polygamous mating: Economical because 1 male can be used for 4-5 females. We can use postpartum estrus effectively.

Immediately after parturition after 7 days they come to heat. Breeding can be done 7 days after parturition after separating the young ones. [Weaning age 21 days]

But this is usually not followed because the number of young ones born reduces subsequently.

Disadvantages: Proper records cannot be maintained.

Rabbits: Housed in mesh floor cages made of galvanized iron, aluminium or steel.

Cleaning should be done regularly (but not within the animal room). Clean feed, water should be given to animals to keep them free of diseases.

Guinea pig: In case of guinea pig, environmental factors play a very important role → Temperature, relative humidity, lighting and ventilation.

Temp → 18-21°C for all laboratory animals

Relative Humidity → 45-55%

Lighting → 12-16 hours for normal physiological activity.

Ventilation → Min 12-15 changes of air for animal room. This can be provided with the help of exhaust fan.

For guinea pig, temperature should not go beyond 30°C, because they cannot dissipate heat from body and they suffer from heat stress and heat frustration because they have loose fold of skin. Highly susceptible for respiratory infection, so adequate ventilation should be given.

They can be housed on wire mesh, floor, and cages. Also directly on floor provided with bedding material → paddy/ ragi straw. In some animal facilities they give saw dust as bedding material. For Guinea Pig saw dust should be given as bedding material as they get adhered to vulva that causes irritation and also it blocks the vulva. There will be reduction in fecundity of the animal →worst

CLASSIFICATION

• Wistar albino
• Sprague Dawley
• Long Evans
• Charles

Wistar Albino

Wistar albino is common strain found in most laboratories and used extensively for research. They have the following characteristics: (i) Less resistance of inflammation, (ii) No incidence of spontaneous tumor.

Sprague Dawley

All scientists working with laboratory animals must have a deep ethical consideration for the animals they are dealing with. From the ethical point of view it is important that such considerations are taken care at the individual level, at Institutional level and finally at the national level.

Individually each investigator has an obligation to abide by all the ethical guidelines laid down in this regard at institutional level. The Head of the institution, maintaining animals for scientific experiments , should constitute an animal ethics committee on animal experimentation to ensure that all experiments conducted on animals are rational , do not cause undue pain or suffering to the animals and only minimum number of animals are used. The constitution and term of reference of the animal ethic committee should be well defined.

An animal ethic committee should include: a senior biological scientist of the institute, two scientists from different biological disciplines, a veterinarian involved in care of animals, the scientist in charge of animal facility, a scientist from outside the institute & a nonscientific socially aware member. A specialist may be co-opted while reviewing special projects using hazardous agents such as radioactive substance and deadly micro-organisms etc. The investigator may be called in for any clarification if required.

The ethics committee has to examine all projects involving use of animals before implementation, to ensure that minimum number of animals is used in the project and the ethical guidelines are strictly adhered to. It will also examine that the scientists and technicians handling animals possess adequate skill to perform the experiment. All animals should be maintained under standard living conditions and experiments will be conducted under proper anesthesia and termination of an experiment, the animal will be humanely sacrificed under anesthesia. Before disposal it must be ensured that the animal is clinically dead.