Continence technologies whitepaper: Informing new engineering science research

Advances in healthcare technology for continence have historically been limited compared to other areas of medicine, reflecting the complexities of the condition and social stigma which act as a barrier to participation. This whitepaper has been developed to inspire and direct the engineering science community towards research opportunities that exist for continence technologies that address unmet needs in diagnosis, treatment and long-term management. Our aim is to pinpoint key challenges and highlight related research opportunities for novel technological advances. To do so, we draw on experience and expertise from academics, clinicians, patients and patient groups linked to continence healthcare. This is presented in four areas of consideration: the clinical pathway, patient perspective, research challenges and effective innovation. In each we introduce seminal research, background information and demonstrative case-studies, before discussing their relevance to engineering science researchers who are interested in approaching this overlooked but vital area of healthcare

A suite of sucrose transporters expressed in coats of developing legume seeds includes novel pH-independent facilitators

A suite of newly discovered sucrose transporter genes, PsSUF1, PsSUF4, PvSUT1 and PvSUF1, were isolated from the coats of developing pea (Pisum sativum L.) and bean (Phaseolus vulgaris L.) seeds. Sequence analysis indicated that deduced proteins encoded by PsSUF1, PvSUT1 and PvSUF1 clustered in a separate sub-group under sucrose transporter Clade I, whereas the deduced protein encoded by PsSUF4 clustered in Clade II. When expressed in yeast, these genes were shown to encode sucrose transporters with apparent Michaelis Menten constant (K m) values ranging from 8.9 to 99.8 mm. PvSUT1 exhibited functional characteristics of a sucrose/H + symporter. In contrast, PsSUF1, PvSUF1 and PsSUF4 supported the pH- and energy independent transport of sucrose that was shown to be bi-directional. These transport properties, together with that of counter transport, indicated that PsSUF1, PvSUF1 and PsSUF4 function as carriers that support the facilitated diffusion of sucrose. Carrier function was unaffected by diethylpyrocarbonate and by maltose competition, suggesting that the sucrose binding sites of these transporters differed from those of known sucrose/H + symporters. All sucrose transporters were expressed throughout the plant and, of greatest interest, were co-expressed in cells considered responsible for sucrose efflux from seed coats. The possible roles played by the novel facilitators in sucrose efflux from seed coats are discussed. © 2007 The Authors Journal compilation 2007 Blackwell Publishing Ltd

Hexose uptake by developing cotyledons of Vicia faba: physiological evidence for transporters of differing affinities and specificities

Cotyledons of broad bean (Vicia faba L.) develop in an apoplasmic environment that shifts in composition from one dominated by hexoses to one dominated by sucrose. During the latter phase of development, sucrose / H+ symporter activity and expression is restricted to cotyledon epidermal transfer cell complexes that support sucrose fluxes that are 8.5-fold higher than those exhibited by the storage parenchyma. In contrast, the flux difference between these cotyledon tissues is only 1.7-fold for hexoses. Glucose and fructose uptake was shown to be sensitive to PCMBS and phloridzin, both of which slow H+- sugar transport. A low K-m (or high affinity transporter, HAT) mechanism transports glucose and glucose-analogues exclusively. No HAT system for fructose could be found. A high K-m ( low affinity transporter, LAT) mechanism transports a broader range of hexoses, including glucose and fructose. Consistent with glucose and fructose transport being H+- coupled, their uptake was inhibited by dissipating the proton motive force (pmf) by treating cotyledons with carbonyl cyanide m-chlorophenol hydrazone, propionic acid or tetraphenylphosphonium ion. Erythrosin B inhibited hexose uptake, indicating a role for the P-type H+- ATPase in establishing the pmf. It is concluded that H+- coupled glucose and fructose transport mechanisms occur at plasma membranes of dermal transfer cell complexes and storage parenchyma cells. These transport mechanisms are active during pre- and storage phases of cotyledon development. However, hexose symport only makes a quantitative contribution to cotyledon biomass gain during the pre- storage stage of development

Review: Nutrient loading of developing seeds

Interest in nutrient loading of seeds is fuelled by its central importance to plant reproductive success and human nutrition. Rates of nutrient loading, imported through the phloem, are regulated by transport and transfer processes located in sources (leaves, stems, reproductive structures), phloem pathway and seed sinks. During the early phases of seed development, most control is likely to be imposed by a low conductive pathway of differentiating phloem cells serving developing seeds. Following the onset of storage product accumulation by seeds, and, depending on nutrient species, dominance of path control gives way to regulation by processes located in sources (nitrogen, sulfur, minor minerals), phloem path (transition elements) or seed sinks (sugars and major mineral elements, such as potassium). Nutrients and accompanying water are imported into maternal seed tissues and unloaded from the conducting sieve elements into an extensive post-phloem symplasmic domain. Nutrients are released from this symplasmic domain into the seed apoplasm by poorly understood membrane transport mechanisms. As seed development progresses, increasing volumes of imported phloem water are recycled back to the parent plant by process(es) yet to be discovered. However, aquaporins concentrated in vascular and surrounding parenchyma cells of legume seed coats could provide a gated pathway of water movement in these tissues. Filial cells, abutting the maternal tissues, take up nutrients from the seed apoplasm by membrane proteins that include sucrose and amino acid/H+ symporters functioning in parallel with non-selective cation channels. Filial demand for nutrients, that comprise the major osmotic species, is integrated with their release and phloem import by a turgor-homeostat mechanism located in maternal seed tissues. It is speculated that turgors of maternal unloading cells are sensed by the cytoskeleton and transduced by calcium signalling cascades.Wen-Hao Zhang, Yuchan Zhou, Katherine E. Dibley, Stephen D. Tyerman, Robert T. Furbank and John W. Patric