1.
Polymorphisms Of Bovine Tumor Necrosis Factor Alpha Gene And Its Association With Mastitis In Sahiwal Cows
by Huma Sattar (2013-VA-03) | Dr. Sehrish Firyal | Dr. Ali Raza Awan | Dr. Muhammad Tayyab.
Material type: ; Literary form:
not fiction
Publisher: 2015Dissertation note: Mastitis is one of the shocking maladies of milch animals causing high production losses to livestock industry of Pakistan (Kenyanjui et al. 2011). It is an inflammatory condition of udder; represent a major problem in dairy cow management. It is one of the most common and frequent disease of dairy industry. Producers suffer a huge loss due to veterinary treatment costs and necessary culling of the infected animals. It negatively affects the milk production, quality of milk, and farm economics (Fourichon et al. 2005). Increasing the disease resistance among dairy cattle is therefore desirable because without controlling mastitis, the national goals of developing dairy farming on commercial and scientific lines and production of wholesome milk which conforms to the standards of WTO Accord would remain elusive.
Mastitis is inflammation of udder that caused by physiological and metabolical changes (Schalm and Noorlander 1957). There are two main types of mastitis; clinical mastitis (characterized by classical symptoms i.e., swelling of udder, redness, clumps and clots in milk etc) and sub-clinical mastitis (not show any symptoms, Milk appear normal, udder appear normal) (Schrick et al. 2001). Mastitis is ranked as a top disease of dairy herds (Rinaldi et al. 2010). This mammary gland infection caused by pathogenic micro organisms such as Staphylococcus aureus, Streptococcus uberis, and Esherichia coli in the mammary gland (Heringstad et al. 2000).
India, China and United States are the larger producer of milk and Pakistan is on forth number in milk yield. Pakistan almost produces 36.5 million tons of milk yeild per year (Cady et al. 1983).The Sahiwal breed is well known among for its superior dairy qualities (Barker et al. 1998). Both cross and pure breed Sahiwal cows have high milk production rate (Khan et al. 2013).
It is very difficult to comprehend this disease because numerous environmental and genetic factors are involved in the origin and development of mastitis (Bradley 2002; Carvajal et al. 2013). Susceptibility and resistance to mastitis is a complex trait influenced by genetic variation of animals. Among these variations, the polymorphisms in immunity genes are principal key factors in defensive mechanism of mammary gland (Ibeagha-Awemu et al. 2008).
The mammary gland tissue is protected by immune system by two defense system; innate and acquired immunity. Innate immunity response by the host is a quick response of bacterial defense system (Mesquita et al. 2012). Innate system is a rapid and effective mechanism that activated on recognition of antigen (Akira et al. 2006). Innate immune system is activated when specific pattern recognition receptors (PRR) that are present on the surfaces which are attach to the specific pathogen (Shuster et al. 1996). PRR are presnt on leucocytes in milk and on the epithelial cells lining of udder. It is reported that T- lymphocyte subset i.e., CD4+, CD8+ and ɤδT are present in infected bovine mammary glands. (Goldammer et al. 2004; Strandberg et al. 2005).
Innate defense (nonspecific) of the mammary gland is stimulated by the physical barrier such as teat end, natural killer (NK) cells, neutrophils, macrophages and certain other soluble factors. The teat cannals are considering the main line of defense. Microorganisms enter from teat canal in milk. The main roles of teat sphincter muscles are to remain orifice close so that bacteria cannot enter. This teat canal also lined with keratin, whose estrified and non estified fatty acid function as bacteriostatics that provide protection and play role to eliminate bacteria causing mastitis (Oviedo-Boyso et al. 2007).
If a pathogen is not eliminated by the physical barrier, the acquired immune system is triggered. In comparison, this system is much faster than other immune response. The memory response is significantly stronger, long durable and more efficient to kill the pathogen. The acquired immune system (memory response) have ability to differentiate self or nonself cells and produce antibodies only against antigens through membrane bound protein called major histocompatibility complex (MHC) molecules. Specific immune system activate only when antigens bind with an MHC that is present on the surface of certain cells, this process is referred as antigen presentation. Recognition of pathogenic factors for elimination is mediated by macrophages, several lymphoid, and immunoglobulins (Ig) or antibodies (Sordillo and Streicher 2002).
The most acute responding macrophages and T-cell cytokines are TNF-α, LTF, IL1, IL6, IL8, and IFN-ɤ present in intramammary infection in cows. These genes play important role in improvement of immunity to mastitis (Burton and Erskine 2003).
Tumor necrosis factor alpha is main pro-inflammatory adipokine that is part of systematic immune defense. The main function of TNF-α gene is responsible for proliferation, differentiation and activity of many immune system cells; B lymphocytes, NK (natural killer). It also induces the production and release of many other cytokines (Wojdak Maksymiec et al. 2013) and also enhances the chemotactic and phagocytic effects of immune response. TNF-α gene contains four exons and three introns that are present on chromosome BTA23q22 (Bannerman 2009; Moyes et al. 2009).
TNF-α is a member of a group of cytokines that stimulate the specific immune system. TNF consist of 212 amino acid arranged in stable homotrimers (Kriegler et al. 1988; Tang et al. 1996). The 17-kilodalton (kDa) TNF protomers are composed of two β-pleated sheets and β-strands, joined together antiparallel (Tang et al. 1996).
TNF-α is a component of natural protection systems of humans and animals. Milk gives nourishment and disease resistance to the new born. Various cellular and soluble immune components are important for protecting the mammary gland from infectious diseases like mastitis. Mastitis affects one third of all dairy cows and cost the dairy industry about 2 million dollars annually (National Mastitis Council (1996). Dairy cattle are especially susceptible to mastitis due to diminished mammary gland defense mechanisms (Sordillo and Streicher 2002).
TNF-α is not only produced by activation of macrophages, but also other cell types such as CD4+ lymphocytes, NK cells, neutrophils, mast cells, eosinophils, and neurons. Large amounts of TNF are released in response to lipopolysaccharide, other bacterial products, and Interleukin-1 (IL-1).TNF-α stimulates the proliferation, differentiation and activity of many immune system cells; B lymphocytes, NK (natural killer). TNF-α induces the release of many other cytokines (Wojdak-Maksymiec and Mikolajczyk 2012). TNF-α also enhance the chemotactic and phagocytic effects of immune response.
. The present study is designed to determine the genetic polymorphism in exon 4 of TNF-α gene of mastitic cows and its association resistance and susceptibility towards mastitis.
Availability: Items available for loan: UVAS Library [Call number: 2224-T] (1).
2.
DNA Based Characterization Of Arginase Gene From Geobacillus Sp. SBS-4s
by Raabia Bibi (2012-VA-537) | Dr. Muhammad Tayyab | Dr. Abu Saeed Hashmi | Dr. Muhammad Imran.
Material type: ; Literary form:
not fiction
Publisher: 2015Dissertation note: Geobacillus is a group gram-positive, rod-shaped, aerobic, endospore-forming and obligate thermophilic bacteria, isolated from the diverse habitats, hot springs, thermal environments, terrestrial soils, deep sea sediments (Zeigler, 2014), petroleum and soil of desserts (Claus and Berkeley 1986). It grows at a wide range of temperature from 45 to 75°C and pH ranging from 6.2 to 7.8 (Nazina et al. 2001). These bacteria survives at higher temperature where most of other living species fail to survive (Claus and Berkeley 1986). Geobacillus have achieved a significant population with a worldwide distribution, probably in large part due to adaptive features of their spores (Zeigler, 2014). These can be found singly or in short chains and motile by means of peritrichous flagella and is capable of secreting a wide variety of extracellular and intracellular enzymes i.e amylase, lipase, carboxypeptidase, cellulase, xylanase, protease and galactosidase (Fogarth et al. 1974; Obeidat et al. 2012).
Geobacillus sp. SBS-4S was isolated from hot spring located in Gilgit, Northern areas of Pakistan. It was found to be an aerobic, gram-positive and rod-shaped bacteria having ability to hydrolyze a variety of sugars, carboxylic acids and hydrocarbons at elevated temperatures from 45 to 75°C. SBS-4S was found to be involved in the production of various intra and extra cellular enzymes (Tayyab et al. 2011).
Arginase is the enzyme responsible for the degradation of arginine resulting in the production of urea and ornithine (Kaur et al. 2009). It is accomplished by the cleaving of the guanidinium group from arginine which yields urea (Turras et al. 2008). Arginase present in many mammals (Homo sapiens), Bacilli (cyanobacteria), protozoa (Entamoeba histolytica), yeast (Saccharomyces cerevisiae), fungi (Neurospora crassa) and plants (Lathyrus sativus) etc (Kaur et al. 2009). The crystal structure of arginases have been determined by X ray crystallographic studies. This is a manganese dependent enzyme. The enzyme shows its activity through the metal ion. Metal ion is actively responsible for the incorporation of water molecules essential for the activity of the enzyme. A second proposed mechanism, based on electron paramagnetic resonance (EPR) studies postulates direct coordination of the substrate to manganese and disruption of the aqua bridge. Arginases are homo-oligomers, with a typical subunit mass of 32 to 36 kDa (Bewley et al. 1999).
There are two types of arginases, arginase-I and arginase-II, located in the cytoplasm and mitochondria, respectively. The principal ureagenic enzyme activity arginase-I is most abundant in normal mammalian liver and acts in coordination with the other enzymes of the urea cycle to sequester and eliminate excess nitrogen from the body. The second form arginase-II can be found in many organs, with the highest levels found in kidney and prostate where as lower levels in macrophages and lactating mammary glands (Iyer et al. 2002).
Important role of arginase in controlling the cellular levels of arginine and ornithine, which are required for various critical metabolic processes, including protein synthesis and the production of creatine, polyamines, proline and nitric oxide (NO). Type II arginase is found in a variety of different tissues and have a key role in the regulation of urea cycle arginine metabolism by regulating levels of arginine in the cell (Bewley et al. 1999). The enzyme arginase plays key role in the pathogenesis of pulmonary disorders such as asthma through dysregulation of L-arginine metabolism and modulation of nitric oxide (NO) homeostasis and it also play role in the development of chronic airway remodeling through formation of ornithine with downstream production of polyamines and L-proline, which are involved in processes of cellular proliferation and collagen deposition (Benson et al. 2011). Arginase involved in tissue repair processes by the synthesis of L-ornithine, which is the precursor of polyamines and proline that are involved in cell proliferation and collagen synthesis (Maarsingh et al. 2009).
Genetically engineered arginase as fusion protein with prolonged half-life and increased efficacy are used to treat different tumor lines that inhibit cell proliferation and impaired cellular migration in vitro and in vivo (Li et al. 2013). This is a arginine-degrading and ornithine producing enzyme and is used to treat arginine-dependent cancers (Yu et al. 2013). Chemically modified arginase-II has been employed for the treatment of taper liver tumor and L5178Y murine leukemia (Kaur et al. 2009). The enzyme was cloned and expressed in E. coli and subsequently conjugated to polyethylene glycol to increase the circulating half-life and decrease the immunogenicity of the recombinant mycoplasma enzyme. The human hepatocellular carcinoma, melanoma cell lines and tissue samples do not express argininosuccinate synthetase (ASS), making them auxotrophic for arginine and thus reasonable candidates for arginine deprivation (Yang et al. 2010).
Arginase is induced in murine myeloid cells mainly by T-helper 2 cells cytokines and inflammatory agents and participates in a variety of inflammatory diseases by down-regulation of nitric oxide synthesis, induction of fibrosis and tissue regeneration. In humans, arginase I is constitutively expressed in polymorphonuclear neutrophils and is liberated during inflammation. Myeloid cell arginase-mediated L-arginine depletion profoundly suppresses T cell immune responses and this is a fundamental mechanism of inflammation-associated immunosuppression. Pharmacological interference with L-arginine metabolism is a novel promising strategy in the treatment of cancer, autoimmunity or unwanted immune deviation (Munder, 2009).
Arginase has very important role in nitrogen fixation and fruit ripening (Yu et al. 2013). Putrescine (1,4-butanediamine) is the product obtained from arginine with the highest market value and it is used as an intermediate in a large number of industries, including the pharmaceutical industry, agrochemical industry and textile industry (Turras et al. 2008).
Arginine is a semi-essential amino acid and is the precursor for the formation of nitric oxide (NO) by nitric oxide synthases (Getz and Reardon, 2006). One of the major functions of arginine within the body is as an intermediate in the urea cycle. In the cytosol of hepatocytes, arginase-I removes the guanidine group from arginine to produce urea and ornithine. Urea is then transported from the hepatocyte into the bloodstream and ornithine is used to regenerate arginine within the hepatocyte. Arginine deficiency causes several disorder like, hyper cholesterolemia, hypertension, diabetes mellitus, kidney failure, hyper homo-cysteinemia, smoking, and aging (Alvares et al. 2012). Arginine is used to modulate the cellular immune response during infection. The generation of nitric oxide from arginine is responsible for efficient immune response (Das et al. 2010).
Arginine is synthesised in humans and other mammals from citrulline in two steps through the urea cycle enzymes, argininosuccinate synthetase (ASS) and argininosuccinate lyase (ASL). ASS catalyses the conversion of citrulline and aspartic acid to argininosuccinate, which is then converted to arginine and fumaric acid by ASL (Yang et al. 2010).
Ararinase play important role in conversion of arginine to 1,4–butanediamine (a building block for nylon-4,6), through two main transformations: the hydrolysis of arginine to ornithine and urea; and the decarboxylation of ornithine to 1,4–butanediamine and carbon dioxide. Both steps can be catalyzed chemically or enzymatically (Turras et al. 2008).
The present study deals with the characterization of arginase gene.
Availability: Items available for loan: UVAS Library [Call number: 2244-T] (1).
