Dale Sanders | |
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Born | [1] | 13 May 1953
Alma mater |
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Awards | FRS (2001) |
Scientific career | |
Institutions | |
Thesis | The regulation of ion transport in characean cells (1978) |
Website |
Dale Sanders, FRS (born 13 May 1953) is a plant biologist and former Director of the John Innes Centre. [2] The centre is an institute for research in plant sciences and microbiology, in Norwich, England.
Sanders was educated at The Hemel Hempstead School. He gained a Bachelor of Arts degree from the University of York reading Biology from 1971 to 1974, graduating with 1st Class Honours. [1]
Sanders did his PhD alongside Professor Enid AC MacRobbie FRS at Darwin College, Cambridge in 1978, in the Department of Plant Sciences. In 1993, Sanders earned his Sc.D. from the University of Cambridge.
Sanders’ research explores the transport of ions across plant cell membranes [3] and the roles of ions in signalling and nutrient status.
Sanders’ first significant finding during his PhD was to provide unequivocal evidence that inorganic anion uptake in plants is powered by a proton gradient [4] and showed how transport is regulated through intracellular ion concentrations. [5]
In subsequent research as a post-doc at Yale University School of Medicine he pioneered the first methods to measure and interpret the interplay between control of intracellular pH and activity of the plasma membrane proton pump. Showing how the regulation of the proton pump is controlled by – and in turn controls – intracellular pH. [6] This work on a fungus served as a paradigm for understanding the interplay of membrane transport and cellular homeostasis in fungal and plant cells.
On taking an academic position at the University of York, Sanders developed novel electrophysiological approaches to plant cellular signalling and membrane transport.
The Sanders lab demonstrated a key link between changes in cytosolic free calcium and photosynthetic activity, and through many technical developments showed how membrane transport at the plant vacuole is energised and regulated in response to physiological demand.
Sanders also developed a unified mathematical theory that explained complex kinetics of solute uptake in plants, [7] [8] along with having created the first methodology to measure transient changes in intracellular calcium levels in higher plants, and discovered that light/dark changes in photosynthetic activity were highly dependent on cytosolic changes in calcium. [9]
In the days before extensive molecular biology, Sanders discovered that the vacuolar proton pump of plants was essentially similar to mitochondrial ATPases. [10] He also adapted electrophysiological techniques first developed for exploration of neuronal channel properties to determine that pumps at vacuolar membranes exhibit kinetic responses to ion gradients that would not be predicted through biochemical means. [11] [12] [13] Parallel to this, he discovered that vacuolar membranes exhibit electrically-driven ion release. [14]
Using both electrophysiological and biochemical approaches, Sanders was able to establish for the first time in plants that metabolites can act as triggers for release of calcium (a cellular signal) from vacuoles. [15] [16] [17] [18] [19] [20]
Sanders established principles for biofortification of cereal crops with essential human mineral nutrients, [21] and molecularly characterised calcium permeable channels. [22] Sanders also discovered and characterised the first (and only) yeast calcium channel [23] [24] and demonstrated how cell marking can be used to distinguish cell types for patch clamp studies. [25]
Sanders also had influence in the investigation into the roles of plant cyclic nucleotide-gated channels that were explored at an early stage of discovery [26] and resulted in a major collaborative publication with another lab demonstrating a key role in plant-bacterial symbiosis signalling. [27]
On top of his extensive discoveries, he has also written influential reviews on calcium signalling in plants, which have 3,300 combined citations on Google Scholar. [28] [29] [30]
To further his work on calcium channels, he then discovered that the TPC1 channel is the major pathway for ion exchange across plant vacuolar membranes. [31] Their speculations that the TPC1 channel is involved in Calcium-induced calcium release were proven for the first time in plants in work from Sanders’ lab. [32] He then established the principal molecular and cellular mechanisms for plant tolerance to manganese toxicity. [33]
Sanders has discovered the major mechanism of zinc accumulation in plant vacuoles, [34] and more recently characterised the molecular properties of the transporter [35] and showed how the transporter could be used for nutritional benefit for human consumption of cereal grains. [36] On top of further collaborating with a Chinese lab to establish more generally the important role of zinc nutrition in rice. [37]
Sander’s current research focuses on how plant cells respond to changes in their environment [38] and how they store the nutrients they acquire. In particular, his group work on how transport of chemical elements across cell membranes in plants is integrated with cellular signalling and nutritional status. [21]
Sanders' research career began at the Yale University School of Medicine, first as a postdoctoral research fellow (1978–79) and then as a postdoctoral research associate (1979–83).
After a stint as a visiting research fellow in the University of Biological Sciences at the University of Sydney (1983), Sanders moved into the biology department at the University of York in 1983, first as a lecturer (1983–89), a reader (1989–1992), a professor (1992–2010), also acting as the head of department (2004–2010). [39]
In 2010 Sanders moved to the John Innes Centre, Norwich, as director and group leader, [40] establishing new collaborations with the Chinese Academy of Sciences. [41]
Sanders was elected a Fellow of the Royal Society in 2001. [42]
Throughout his career Sanders has received a number of additional awards and honours, including:
A vacuole is a membrane-bound organelle which is present in plant and fungal cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution, though in certain cases they may contain solids which have been engulfed. Vacuoles are formed by the fusion of multiple membrane vesicles and are effectively just larger forms of these. The organelle has no basic shape or size; its structure varies according to the requirements of the cell.
In cellular biology, active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement. There are two types of active transport: primary active transport that uses adenosine triphosphate (ATP), and secondary active transport that uses an electrochemical gradient. This process is in contrast to passive transport, which allows molecules or ions to move down their concentration gradient, from an area of high concentration to an area of low concentration, without energy.
Aquaporins, also called water channels, are channel proteins from a larger family of major intrinsic proteins that form pores in the membrane of biological cells, mainly facilitating transport of water between cells. The cell membranes of a variety of different bacteria, fungi, animal and plant cells contain aquaporins through which water can flow more rapidly into and out of the cell than by diffusing through the phospholipid bilayer. Aquaporins have six membrane-spanning alpha helical domains with both carboxylic and amino terminals on the cytoplasmic side. Two hydrophobic loops contain conserved asparagine–proline–alanine which form a barrel surrounding a central pore-like region that contains additional protein density. Because aquaporins are usually always open and are prevalent in just about every cell type, this leads to a misconception that water readily passes through the cell membrane down its concentration gradient. Water can pass through the cell membrane through simple diffusion because it is a small molecule, and through osmosis, in cases where the concentration of water outside of the cell is greater than that of the inside. However, because water is a polar molecule this process of simple diffusion is relatively slow, and in tissues with high water permeability the majority of water passes through aquaporin.
A membrane transport protein is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembrane proteins; that is they exist permanently within and span the membrane across which they transport substances. The proteins may assist in the movement of substances by facilitated diffusion, active transport, osmosis, or reverse diffusion. The two main types of proteins involved in such transport are broadly categorized as either channels or carriers. Examples of channel/carrier proteins include the GLUT 1 uniporter, sodium channels, and potassium channels. The solute carriers and atypical SLCs are secondary active or facilitative transporters in humans. Collectively membrane transporters and channels are known as the transportome. Transportomes govern cellular influx and efflux of not only ions and nutrients but drugs as well.
An antiporter is an integral membrane protein that uses secondary active transport to move two or more molecules in opposite directions across a phospholipid membrane. It is a type of cotransporter, which means that uses the energetically favorable movement of one molecule down its electrochemical gradient to power the energetically unfavorable movement of another molecule up its electrochemical gradient. This is in contrast to symporters, which are another type of cotransporter that moves two or more ions in the same direction, and primary active transport, which is directly powered by ATP.
Cotransporters are a subcategory of membrane transport proteins (transporters) that couple the favorable movement of one molecule with its concentration gradient and unfavorable movement of another molecule against its concentration gradient. They enable coupled or cotransport and include antiporters and symporters. In general, cotransporters consist of two out of the three classes of integral membrane proteins known as transporters that move molecules and ions across biomembranes. Uniporters are also transporters but move only one type of molecule down its concentration gradient and are not classified as cotransporters.
An electrochemical gradient is a gradient of electrochemical potential, usually for an ion that can move across a membrane. The gradient consists of two parts:
Vacuolar-type ATPase (V-ATPase) is a highly conserved evolutionarily ancient enzyme with remarkably diverse functions in eukaryotic organisms. V-ATPases acidify a wide array of intracellular organelles and pumps protons across the plasma membranes of numerous cell types. V-ATPases couple the energy of ATP hydrolysis to proton transport across intracellular and plasma membranes of eukaryotic cells. It is generally seen as the polar opposite of ATP synthase because ATP synthase is a proton channel that uses the energy from a proton gradient to produce ATP. V-ATPase however, is a proton pump that uses the energy from ATP hydrolysis to produce a proton gradient.
Guard cells are specialized plant cells in the epidermis of leaves, stems and other organs that are used to control gas exchange. They are produced in pairs with a gap between them that forms a stomatal pore. The stomatal pores are largest when water is freely available and the guard cells become turgid, and closed when water availability is critically low and the guard cells become flaccid. Photosynthesis depends on the diffusion of carbon dioxide (CO2) from the air through the stomata into the mesophyll tissues. Oxygen (O2), produced as a byproduct of photosynthesis, exits the plant via the stomata. When the stomata are open, water is lost by evaporation and must be replaced via the transpiration stream, with water taken up by the roots. Plants must balance the amount of CO2 absorbed from the air with the water loss through the stomatal pores, and this is achieved by both active and passive control of guard cell turgor pressure and stomatal pore size.
The sodium-calcium exchanger (often denoted Na+/Ca2+ exchanger, exchange protein, or NCX) is an antiporter membrane protein that removes calcium from cells. It uses the energy that is stored in the electrochemical gradient of sodium (Na+) by allowing Na+ to flow down its gradient across the plasma membrane in exchange for the countertransport of calcium ions (Ca2+). A single calcium ion is exported for the import of three sodium ions. The exchanger exists in many different cell types and animal species. The NCX is considered one of the most important cellular mechanisms for removing Ca2+.
Inorganic pyrophosphatase is an enzyme that catalyzes the conversion of one ion of pyrophosphate to two phosphate ions. This is a highly exergonic reaction, and therefore can be coupled to unfavorable biochemical transformations in order to drive these transformations to completion. The functionality of this enzyme plays a critical role in lipid metabolism, calcium absorption and bone formation, and DNA synthesis, as well as other biochemical transformations.
The P-type ATPases, also known as E1-E2 ATPases, are a large group of evolutionarily related ion and lipid pumps that are found in bacteria, archaea, and eukaryotes. P-type ATPases are α-helical bundle primary transporters named based upon their ability to catalyze auto- (or self-) phosphorylation (hence P) of a key conserved aspartate residue within the pump and their energy source, adenosine triphosphate (ATP). In addition, they all appear to interconvert between at least two different conformations, denoted by E1 and E2. P-type ATPases fall under the P-type ATPase (P-ATPase) Superfamily (TC# 3.A.3) which, as of early 2016, includes 20 different protein families.
V-type proton ATPase 16 kDa proteolipid subunit is an enzyme that in humans is encoded by the ATP6V0C gene.
V-type proton ATPase subunit G 2 is an enzyme that in humans is encoded by the ATP6V1G2 gene.
V-type proton ATPase subunit G 1 is an enzyme that in humans is encoded by the ATP6V1G1 gene.
In the field of enzymology, a proton ATPase, or H+-ATPase, is an enzyme that catalyzes the following chemical reaction:
Calcium pumps are a family of ion transporters found in the cell membrane of all animal cells. They are responsible for the active transport of calcium out of the cell for the maintenance of the steep Ca2+ electrochemical gradient across the cell membrane. Calcium pumps play a crucial role in proper cell signalling by keeping the intracellular calcium concentration roughly 10,000 times lower than the extracellular concentration. Failure to do so is one cause of muscle cramps.
Members of the H+, Na+-translocating Pyrophosphatase (M+-PPase) Family (TC# 3.A.10) are found in the vacuolar (tonoplast) membranes of higher plants, algae, and protozoa, and in both bacteria and archaea. They are therefore ancient enzymes.
Roger Morgan Spanswick was a Professor of Biological and Environmental Engineering at Cornell University and an important figure in the history of plant membrane biology.
Philip A. Rea is a British biochemist, science writer and educator, who is currently Professor of Biology and Rebecka and Arie Belldegrun Distinguished Director of the Vagelos Program in Life Sciences & Management at the University of Pennsylvania. His major contributions as a biochemist have been in the areas of membrane transport and xenobiotic detoxification, and as a science writer and educator in understanding the intersection between the life sciences and their implementation. In 2005, he and Mark V. Pauly founded the Roy and Diana Vagelos Program in Life Sciences & Management between the School of Arts and Sciences and Wharton School at the University of Pennsylvania, which he continues to co-direct in his capacity as Belldegrun Distinguished Director. Rea's work on serendipity in science has been featured in The Wall Street Journal. Additionally, he has served as a subject matter expert for 'The Scientist.
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