eChapters

Spleen is an elongated solid organ located on the left side along cranial and ventral abdominal wall. The size of spleen is variable in dogs. The spleen is larger in German Shepherds and Greyhounds. In cats the spleen is smaller and has fixed size. It is parallel to greater curvature of stomach within greater omentum. The position of spleen in dogs is variable as it is only attached by gastrosplenic ligament.

Ultrasonographic examination of gastrointestinal tract is not very much rewarding in dogs because of gas in the tract but it is crucial for a correct diagnosis. Imaging of stomach plays a significant role in the diagnosis of gastric diseases such as gastric dilatation, gastric foreign bodies, pyloric outflow obstruction, or gastric tumours.

Ultrasound and survey radiography are two important diagnostic modalities regularly employed in the diagnosis of intestinal diseases. Both modalities are complementary to each other in investigating the problems related to intestines. It is always better to have plain survey radiograph of abdomen first and then ultrasound to rule out obstruction or radio-opaque foreign bodies. Wherever barium meal radiograph is indicated, it should be done after sonographic examination as barium may degrade image quality of the sonogram. Assessment of intestinal motility can be done in real time sonography.

The pancreas is a thin and elongated ‘V’ shaped organ having two lobes (right and left) and body. It lies in the right cranial quadrant of the abdomen. It is difficult to visualize normal pancreas sonographically because of its echogenicity similar to that of adjacent mesentery and fat.

The urinary tract is the body’s drainage system. It includes kidneys, ureters, urinary bladder and urethra. Ultrasound is a most preferred imaging tool for the diagnosis of diseases of urinary tract not only in humans but also in dogs and cats. Little adipose tissue in urinary system of dogs makes the contrast between different planes and anatomical structures poor.

Application of ultrasonography has become a routine practice in canine and feline medicine to detect pregnancy, to ascertain foetal wellbeing, to ascertain live/dead status of the foetus, ovarian dynamics, and to diagnose reproductive ailments (uterine, ovarian,) in females. Sonography is also being preferred in males for the diagnosis of diseases of prostate gland, cryptorchid, and testicular diseases.

Ultrasound has been used to image thyroid and parathyroid glands. It can assist in the diagnosis of hyperthyroidism and hyperparathyroidism in dogs and cats. Recently it has also been used to differentiate cases of primary hypothyroidism or euthyroid syndrome.

Ophthalmic or ocular ultrasound can provide important diagnostic information that is readily not available with other diagnostic techniques. Ocular ultrasound is emerging as an important diagnostic modality in veterinary ophthalmology.

Sonography of the nervous system in dogs dates back to 1972 when it was employed in experimental studies. Thick bony cage of the brain limits the sonographic evaluation of the brain. It has an important place in human paediatric medicine. Sonography of the brain and the nervous system is not very common in veterinary medicine.

Imaging of muscles, tendons, joints and bones is not common practice in canine and feline medicine. However, scanning of tendons and ligaments is extensively done in race horses to see their fitness. Adhesions, ruptures/ tears and inflammation of tendons and ligaments can be detected by sonographic imaging of these structures. These structures are relatively superficial so a high frequency linear or curvilinear transducer (7.5 to 13.0 MHz) is used to scan these structures. For scanning of joints acoustic window is relatively small so micro convex or sector probes are more appropriate.

Cardiac ultrasound is also known as echocardiography and it has a very important place in the diagnosis of cardiac diseases of the humans as well as animals. Echocardiography is an imaging of the heart using ultrasound. The diagnosis of congenital heart diseases, shunts, complex malformations, valvular heart diseases, different cardiomyopathies, endocarditis, pericardial effusion, cor pulmonale and cardiac tumours has been possible by cardiac ultra ultrasound that was otherwise difficult.

Beside heart, ultrasound of the thorax facilitates the imaging of lungs, pleura, mediastinum, chest wall and diaphragm. Sonographic examination of the heart is discussed in chapter16. Because of nearly total reflection of sound waves at gas interfaces (Fig. 176) thoracic ultrasound has limitations. Pulmonary and mediastinal lesions located deep are difficult to image. Peripheral pulmonary lesions and pleural fluid can be visualized.

Abdominal organs in different species of animals have distinctive features with respect to their shape, size, location and echogenicity and echo texture. This is true for dogs and cats also. Therefore, information with respect to sonographic features of dogs cannot be taken for granted for cats in totality

Focused assessment with sonography for trauma (abdominal and thoracic) refers to the limited ultrasound examination with the main focus on quick identification of the presence of free fluid within peritoneal, pleural and pericardial spaces in trauma cases in intensive care units. Despite limitations, findings of FAST are helpful in stabilizing the emergency patients.

Architecture of the organ is affected in the primary or secondary diseases of the organs. Ultrasonography plays a significant role in detecting the changes in the organs in various diseases.

For the sake of convenience ruminants are broadly divided into two categories as large ruminants and small ruminants. Large ruminants consist of cattle and buffaloes and small ruminants consist of goats and sheep. Sonography is becoming an important part of diagnostic modalities in ruminants also. Its major use in ruminants is in reproduction and lameness.

During last two decades significant advances have been made in diagnostic ultrasound .These advances have positively impacted on diagnostic imaging across all species of animals and have made ultrasound as an indispensable diagnostic modality in veterinary medicine. Since equines have been more a sport and pack animals, the ultrasound technique has long been utilized in the diagnosis of equine musculo-skeletal disorders. Recent years have witnessed its utility in the management of equine reproduction beside its use in the diagnosis of colic and other diseases.

Ultrasonography is being routinely practiced in canine and feline medicine for the diagnosis of diseases of the organs and also to confirm pregnancy. Its routine use in ruminant medicine is mainly restricted to pregnancy diagnosis. Recently the potential of ultrasonography is also being explored in zoo and wild animals as well as in exotic pets. Information available in companion and other domestic animals cannot be applied blindly to zoo and wild animals.

Utility of ultrasound has extended from diagnostic realm to alternate therapies. Therapeutic ultrasound is also known as ultrasound physiotherapy. It is a commonly used modality for the rehabilitation of the soft tissues of the musculoskeletal system.

Sonograms of animals suffering from different diseases are presented along with other investigations as case studies to provide a comprehensive picture of the disease.

A. Define / Explain the following

1. Mitosis: The multiplication of a body cell into two daughter cells of equal size and containing the same number of chromosomes as in the parent cell is called mitosis or somatic division.

2. Meiosis: Meiosis occurs only in gonads (in germ mother cells) during the formation of gametes like sperm and ovum. Meiosis is a process by means of which double number or 2N or diploid chromosomes is reduced to its half number or n or haploid. It is also called reduction process.

2.1 Introduction in Plant Breeding

A. Define/Explain the followings

1. Plant breeding: Plant breeding is defined as the art, science and technology of improving the genetic make-up of crop plants in relation to their economic use for mankind.

A. Define/Explain the followings

1. Mutation: Sudden heritable change in the phenotype of an individual.

2. Macro-mutations: Mutations with distinct morphological changes in the phenotype are called macro-mutations. Such mutations are found in qualitative character and, therefore, are also called oligogenic mutations.

A. Define/Explain the following

1. Heteroploidy: Any change in chromosome number from the diploid state.

2. Euploidy: Numerical change in the entire genome.

1. Agricultural biotechnology: Agricultural biotechnology is a collection of scientific techniques used to improve plants, animals and microorganisms.

2. Gel electrophoresis: Analytical technique by which usually large biomolecules (proteins, DNA) are separated through a gel by application of an electric field.

1. Ideotype : It is a biological model which is expected to perform in a predicted manner in a defined environment.

2. Shuttle breeding: Growing of segregating generation in different environments.

1. Nucleus seed: It is the handful of original seed obtained from selected individual plants of a particular variety. It has the highest genetic purity and physical purity.

Biometrical genetics: This is a branches of genetics which uses the statistical concept and procedures for the study of genetic principles.

Intellectual property : Refers to creations of the mind: inventions, literary and artistic works, and symbols, names, images, and designs.

1. ICAR-Central Island Agricultural Research Institute, Port Blair

2. ICAR-Central Arid Zone Research Institute, Jodhpur

3. ICAR-Central Avian Research Institute, Izatnagar

1. ICAR-National Research Centre for Banana, Trichi

2. ICAR-National Research Centre for Grapes, Pune

3. ICAR-National Research Centre for Litchi, Muzaffarpur

1. ICAR-National Bureau of Plant Genetics Resources, New Delhi

2. ICAR-National Bureau of Agriculturally Important Micro-organisms, Mau, Uttar Pradesh

Directorates/Project Directorates

1. ICAR-Directorate of Groundnut Research, Junagarh, Gujarat

2. ICAR-Directorate of Soybean Research, Indore, Madhya Pradesh

All India Coordinated Research Projects

1. AICRP on Nematodes, New Delhi

2. AICRP on Maize, New Delhi

3. AICRP Rice, Hyderabad

4. AICRP on Chickpea, Kanpur

Agricultural Research Centers in World

1. Consultative Group on International Agricultural Research (CGIAR Centers)- Montpellier, France (1971)

2. International Center For Tropical Agriculture (CIAT)-Colombia (1969)

Agricultural University

17.1 Central Agricultural Universities

1. Central Agricultural University, Imphal Manipur

2. Rani Laxmi Bai Central Agricultural University, Jhansi Uttar Pradesh

3. Dr. Rajendra Prasad Central Agricultural University, Pusa (Samastipur)

Unique Achievement in Plant Breeding

Rice

TN-1: First dwarf variety of rice developed in world

IR-8: Second dwarf and first high yielding variety of rice developed in world

Jaya: First dwarf variety of rice developed in India

Plant biotechnology can be defined as the introduction of desirable traits into plants through plant tissue culture and genetic engineering techniques. The recombinant DNA technology is used to modify the expression of genes already present in the plants or to introduce new genes of other species with which the plant cannot be bred conventionally.

Plasmid is a double stranded, self replicating, circular extra chromosomal DNA of bacterium. It is used in recombinant DNA experiments to clone genes from other organisms and make large quantities of their DNA. Plasmid can be transferred between same species or between different species. The sizes of plasmids range from 1-1000 kbps. Plasmids are part of mobilomes (total of all mobile genetic elements in a genome) like transposons or prophages and are associated with conjugation.

This is a procedure for transforming bacterial cells with circular DNA plasmids containing an origin of autonomous DNA replication and a selective marker (antibiotic resistance). Logarithmically growing cells are made permeable to DNA by incubation in CaCl2 and the DNA is taken up from the surrounding buffer.

Enterobacteria phage ? is a bacterial virus, or bacteriophage, that infects the bacterial species Escherichia coli (E.coli). It was discovered by Esther Lederberg in 1950. The wild type of this virus has a temperate life cycle that allows it to either reside within the genome of its host through lysogeny or enter into a lytic phase, during which it kills and lyses the cell to produce offspring. Lambda strains, mutated at specific sites, are unable to lysogenize cells; instead, they grow and enter the lytic cycle after superinfecting an already lysogenized cell.

There are various methods available for isolation of high molecular weight genomic DNA from plants. The basic steps involved in all these methods are removal of cell wall, nuclear membrane, proteins, lipids, carbohydrates, cell debris, RNA without affecting the integrity of DNA. The two major factors that affect DNA integrity are action of endogenous nucleases and impact of mechanical shearing.

RNA is transcriptional product of DNA. The total RNA includes three classes, rRNA, tRNA and mRNA. The ribonucleic acids exists as ribonucleo protein particles in intact cells. The ribonucleo protein complex is dissociated by SDS in to RNA and protein deproutinised by phenol and the free RNA left in the aqueous solution is precipitated in cold by adding alcohol. 

Polysomes consist of two or more ribosome traversing a strand of mRNA, translating the nucleotide sequence into the corresponding amino acid sequence. Usually at any time, many ribosomes are translating an mRNA simultaneously forming a structure called a polyribosome or polysomes. One reason for isolating polyribosomes is to resolve them on sucrose gradients to determine the extent of ribosome loading. The second main reason is to provide a source of mRNA for in vitro translation.

DNA fragment to be used as a probe should be purified by gel electrophoresis. The band can be located after staining with ethidium bromide and electroeluted.

The in vitro radioactive labeling of DNA fragment is accomplished by the incorporation of a radioactive nucleotide during strand synthesis with Klenow enzyme (large subunit of DNA polymerase-I).

Nucleic acid hybridization requires denaturation i.e. the breakage of H-bridges between the complementary strands of the DNA either by heating at high temperatures or by treatment with denaturing chemicals like formamide. The restricted DNA, therefore, is denatured before transfer from the gel onto synthetic membrane since only single stranded DNA binds to nitrocellulose.

Exchange of genetic material rarely occurs between unreleated organisms and even similar species may not exchange chromosomal genes. A certain degree of DNA sequence homology is a prerequisite for genetic recombination in vivo. However, recombination between DNA molecules in vitro is not subject to such taxonomic restrictions.

Recombinant DNA is advancement in molecular technology which allows manipulation of genomes of higher organisms and dissection of their complex regulatory circuits. This new methodology is being used to understand the biochemistry of living organisms. The isolation of gene begins with the cloning of fragmented DNA of the organism into appropriate vector. 

Complementary DNA (cDNA) is a double stranded DNA which is an exact copy of the mRNA, i.e. it consists of group of molecules possessing the information contained in various mRNAs but with termini equivalent to or related to those produced by restriction endonucleases. The use of cDNA is an absolute prerequisite for the expression of eukaryotic proteins in bacteria.