HRI Core Projects Completed 2003
Please click on the project title to view the project summary:
Regulation of tone in ruminant and rat mammary arteries
Regulation of hepatic metabolism
Function and expression of rat mammary gland amino acid transporters under different physiological conditions
Intercellular signalling in mammary tissue morphogenesis and function
Fundamental biology underpinning extended lactation in dairy cattle
Control and manipulation of lipogenic gene expression
Control and manipulation of mammary gland involution
Developing science and technology platforms for the food & drink industries: Exploration of the functionality of novel proteins derived from fish by-products
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HRI/004/01
Regulation of tone in ruminant and rat mammary arteries
Final Project costs: £256,100
Blood flow to the lactating mammary gland not only supplies the organ with nutrients and other factors required to maintain its own integrity, but also the precursors and components required for milk production. Furthermore, inappropriate blood vessel proliferation occurs during tumour growth in breast cancer. Studying the normal function and control of blood vessels supplying the mammary gland (i.e. mammary arteries) will give a better insight into the regulation of substrate supply to the gland, as well as providing aetiological insight into pathological mammary development. We used animal models (bovine and rat) to study the pharmacological characteristics of the mammary artery, and carry out preliminary experiments in culturing endothelial and vascular smooth muscle cells from mammary arteries. We found that the adrenergic receptors responsible for contraction in bovine mammary arteries (BMAs) were predominantly a 1B/a 1A subtypes, which is similar to the profile proposed for human mammary arteries; there was very little functional activity of a 2 receptors. We developed a unique, isolated rat mammary artery (RMA) preparation, and limited experiments with this suggested a similar profile of adrenergic receptors also exists in this preparation. This model has great potential for further studies relating to the physiology of mammary arteries during different reproductive states. The RMA preparation also showed that vessels from lactating animals generated greater force, and were more sensitive to noradrenaline and serotonin than those from control animals. Inhibitors of type III (Milrinone) or type V phosphodiesterases (Zaprinast) were able to relax pre-contracted rings of BMA, suggesting that these compounds could be used to attenuate vasospasms occurring in the human mammary artery during coronary artery bypass grafting. Finally we also demonstrated that vascular smooth muscle cells could be cultured from explants of both bovine and rat mammary arteries.
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HRI/101/99 Regulation of hepatic metabolism
Final Project costs: £921,500
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HRI/102/01 Function and expression of rat mammary gland amino acid transporters under different physiological conditions
Final Project costs: £1,026,800
The mammary gland is a secretory epithelium that needs an abundant supply of amino acids to meet the requirements of protein synthesis. In addition, it has been established that mammary cells require amino acids for regulating their volume which in turn is important for controlling cellular metabolism. It therefore follows that a thorough knowledge of amino acid transport and metabolism is required to fully understand the process of mammary secretion. Work at the Hannah Research Institute has focussed on identifying and characterising the amino acid transport systems which mediate the movement of amino acids across the plasma membrane of mammary epithelial cells.
The transport system L was studied and characterised in perfused lactating rat mammary tissue culture demonstrating a neutral amino acid carrier at the functional level. In addition the molecular identity of the system was explored using RT-PCR. The project has also confirmed the presence of a volume-activated transport pathway in lactating tissue. Radiolabelling and fluorescent pharmacological studies have however indicated the existence of more than one volume-activated amino acid efflux pathway which has important implications for cell volume regulation and cell survival.
This project focussed on identifying the major factors which regulate amino acid transport mechanisms in the rat mammary gland. Knowledge generated from this project will be of benefit to those interested in nutrition and human health and those working in the biotechnology industry who are attempting to use the mammary gland as a bioreactor.
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HRI/126/00 Intercellular signalling in mammary tissue morphogenesis and function
Final Project costs: £668,400
Mammary development and function is modulated within the tissue by paracrine signalling between different cell types, and by autocrine communication between cells of the same type. This intercellular communication affects gene expression and secretory mechanisms or it may change mammary cell number by affecting cell proliferation or cell death by apoptosis. This project aimed to further the understanding of such intercellular communications to provide new insight into the mechanisms of normal and aberrant mammary tissue development and inform the generation of novel strategies for sustainable production.
Three inter-related project themes were studied;
1) Mammary Apoptosis: Studies using mammosphere and tissue culture focused on the signalling that selectively removes cells to form hollow alveoli in pregnancy, and on the autocrine signal that controls cell number according to milking frequency during lactation,
2) Genetic control of casein gene expression: The regulation and transcription factors of the murine gamma casein gene promoter were determined and published
3) Autocrine control of secretion & cellular differentiation: The active constituent in a specific milk fraction that had been shown to control milk secretion, was structurally characterised and key features of the control mechanism defined.
The results have significantly advanced the understanding of the factors that control mammary apoptosis and tissue remodelling after lactation. Results have provided the basis for new hypotheses about the control of the mammary cell population. They are also the foundation of externally funded projects now in progress aimed at the study of mammary developmental mechanisms and their relation to breast cancer progression, and of proposals to cancer charities for research to study the cell biological mechanism whereby lactation protects against breast cancer. Successful conclusion of studies to characterise the feedback control of milk secretion, and the filing of a UK patent application, will enable commercial development of the technology.
The work on the control of casein gene expression has attracted the interest of several potential end-users mainly in the biotech industry leading to the filing of a patent application in the near future.
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HRI/127/00 Fundamental biology underpinning extended lactation in dairy cattle
Final Project costs: £759,000
The objective of the project was to extend understanding of developmental changes in the mammary gland of lactating dairy animals so as to enable extended lactation, a welfare friendly and potentially economic alternative to intensive dairying.
This objective has been achieved. The fundamental investigations of mammary development central to this Core Project were complemented by additional funding from DEFRA to investigate more applied aspects of management, product quality and economic competitiveness. The overall result is that we have shown that extended lactation can be achieved by the simple manipulations of milking more frequently and feeding additional concentrate feed. Biologically, it is accomplished through increased cell proliferation combined with decreased apoptosis, the latter probably mediated through a mechanism compatible with the IGFBP5 hypothesis developed in other HRI core funded work. Economically, it is competitive. Knowledge transfer has been achieved through considerable farming press exposure, BBC TV and radio features, MDC workshops and other farmer seminars as well as through international; scientific meetings and peer reviewed articles. Practically, the concept of extended lactation is becoming accepted and practised by progressive dairy farmers in the UK and elsewhere.
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HRI/157/00 Control and manipulation of lipogenic gene expression
Final Project costs: £1,348,700
The increased metabolic demands of milk synthesis by the mammary gland are met by increased food intake and by various tissue-specific adaptations to increase the flow of metabolic precursors to the mammary epithelial cell. Suppression of lipid synthesis in adipose tissue is an important example of such whole body metabolic adaptation to ensure that lipogenic precursors are used for milk fat rather than body fat synthesis, and is concomitant with alterations in the expression of genes encoding key enzymes of the pathway of fat synthesis in adipose tissue and mammary gland. Acetyl-CoA carboxylase-alpha is a key enzyme of fat synthesis, and to reflect its crucial role is controlled at multiple points including complex gene regulation and acute regulation of enzyme activity.
This project has investigated the molecular mechanisms for the reciprocal regulation of the Acetyl-CoA carboxylase-alpha gene in adipose tissue and mammary gland during lactation, and has provided insight into how these pathways could be manipulated to effect alterations in milk and carcass fat.
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HRI/185/00 Control and manipulation of mammary gland involution
Final Project costs: £832,100
This project aimed to identify the major mechanisms involved in the death of cells which occurs naturally at the end of lactation. Cells require 2 kinds of signals to survive; soluble hormones or growth factors and physical contact with specialised proteins in the extracellular space. We identified a protein which is produced by the cells which are about to die at the end of lactation, in effect a suicide protein, and showed that hormones which prevented cell death also prevented the production of this protein, known as IGFBP-5. We generated a transgenic mouse producing this protein at inappropriate times in the mammary gland and showed that it could induce premature death of the cells. IGFBP-5 therefore offers potential as an anti-tumour therapy. Furthermore we were able to show that this protein could also induce proteases which could disrupt the cell's contact with the extracellular environment. This effect can also induce cell death but, under certain circumstances this can also "free" the cell from its environment and thereby allow it to escape and potentially initiate tumours at distal sites (metastasis). For this reason we have been developing novel forms of IGFBP-5 (mutants) which exhibit individual effects on either inhibition of growth factor survival or physical interaction with the extracellular environment. These proteins are currently under evaluation. We believe that these studies have much wider implications and we have, for example, shown that IGFBP-5 is important in development of the digits and that its expression is deranged during defective development of the limbs.
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HRI/265/01 Developing science and technology platforms for the food & drink industries: Exploration of the functionality of novel proteins derived from fish by-products
Final Projects costs: £64,600
The general objective of this project is to develop science and technology platforms that will be exploited by the food & drink industries. This activity will help facilitate new and improved methods of manufacture of both traditional and new products with improved functionality. The major goal of this short study was to assess the nature, functionality and evaluate potential uses of by-products from fish. Research concentrated on gelatine extracted from the skeleton and the skin of fish. Yields of gelatine from fish skeleton were too low to be of commercial significance. In contrast, higher yields are possible from fish skin.
New HRI patented techniques were used to fractionate protein on a large scale and functionality was assessed using a range of tests to measure and screen stability, particle size, viscosity and resistance to spoilage.
Gelatine isolated from the fish skin source has interesting properties that distinguish it from comparable protein of bovine or porcine origin. In particular, piscine gelatine forms soft three-dimensional structures that are capable of stabilising creaming of lipid emulsions with large particle diameters. This finding has provided opportunities for the manufacture of lipid emulsions that may act as carriers for large inclusions containing bioactive material including protection of probiotic bacteria. New IP has been generated from this project and is currently being protected.
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