An analysis of genes involved in pea compound leaf development

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The actin cytoskeleton: a key regulator of apoptosis and ageing?

Evidence from many organisms has shown that the accumulation of reactive oxygen species (ROS) has a detrimental effect on cell well-being. High levels of ROS have been linked to programmed cell death pathways and to ageing. Recent reports have implicated changes to the dynamics of the actin cytoskeleton in the release of ROS from mitochondria and subsequent cell death

Sla1p couples the yeast endocytic machinery to proteins regulating actin dynamics

Sla1p is a protein required for cortical actin patch structure and organisation in budding yeast. Here we use a combination of immunofluorescence microscopy and biochemical approaches to demonstrate interactions of Sla1p both with proteins regulating actin dynamics and with proteins required for endocytosis. Using Sla1p-binding studies we reveal association of Sla1p with two proteins known to be important for activation of the Arp2/3 complex in yeast, Abp1p and the yeast WASP homologue Las17p/Bee1p. A recent report of Sla1p association with Pan1p puts Sla1p in the currently unique position of being the only yeast protein known to interact with all three known Arp2/3-activating proteins in yeast. Localisation of Sla1p at the cell cortex is, however, dependent on the EH-domain-containing protein End3p, which is part of the yeast endocytic machinery. Using spectral variants of GFP on Sla1p (YFP) and on Abp1p (CFP) we show for the first time that these proteins can exist in discrete complexes at the cell cortex. However, the detection of a significant FRET signal means that these proteins also come close together in a single complex, and it is in this larger complex that we propose that Sla1p binding to Abp1p and Las17p/Bee1p is able to link actin dynamics to the endocytic machinery. Finally, we demonstrate marked defects in both fluid-phase and receptor-mediated endocytosis in cells that do not express SLA1, indicating that Sla1p is central to the requirement in yeast to couple endocytosis with the actin cytoskeleton

A passive UHF RFID pH sensor (smart polymers for wireless medical sensing devices)

A functionalised variant of polydimethylsiloxane (PDMS) was applicated atop an RFMicron RFM2100-AER UHF RFID tag and used in a series of depositions of pH buffer solutions, to observe changes in a sensor code generated by the tag. Averaged values of the sensor code data were used between 800-860MHz from 8-20dBm to compare pH buffers between 8.8 and 7.2 which consistently showed a significant degree of change in averaged sensor intensity readout. pH buffers outside the effective buffering range did not show a significant difference in averaged sensor code intensity

Miniature on skin passive UHF RFID antenna sticker

Passive Radio Frequency Identification (RFID) in recent years has been more widely suggested for medical use with different types of wearable antenna designs. However, wearable passive RFID technology has always been limited by a few key constraints (primarily size) when trying to overcome the variable human body's dielectric properties to produce a high read range antenna design. Here we present an on skin passive RFID antenna design, three centimetres in diameter with a read range near two meters on the human body. With slight adjustments to the polyutherane thickness, the original sticker design can negate the difference between the variable human body dielectric properties within subject groups with only slight loses in antenna read range. It was more cost effective to vary the thickness of the breathable polyutherane used as the tag substrate to achieve a resonance within the European UHF RFID frequency range (as well as to increase the read range capability) than to redesign the antenna. Most variability was seen in subjects with high muscle to fat ratio; if the subject was highly muscular then the antenna polyutherane layer was increased to accommodate the increase in the subject's dielectric properties. This has led to a single passive RFID antenna design (two different polyutherane thicknesses) that can accommodate most people as a wearable design with numerous possible applications

An interaction between Sla1p and Sla2p plays a role in regulating actin dynamics and endocytosis in budding yeast

The importance of a dynamic actin cytoskeleton for facilitating endocytosis has been recognised for many years in budding yeast and is increasingly recognised in mammalian cells. However, the mechanism for actin recruitment and the role it plays in endocytosis is unclear. Here we show the importance of two yeast proteins in this process. We demonstrate that Sla1p and Sla2p interact in vitro and in vivo and that this interaction is mediated by the central domain of Sla2p, which includes its coiled-coil region, and by a domain of Sla1p between residues 118 and 361. Overexpression of the interacting fragment of Sla1p causes reduced fluid-phase endocytosis and, interestingly, defects in subsequent trafficking to vacuoles. We show that Sla2p is required for the polarised localisation of Sla1p in cells but not for its cortical localisation or for its overlapping localisation with actin. Generation of an Δsla1Δsla2 double mutant demonstrates that Sla2p is likely to act upstream of Sla1p in endocytosis, whereas sensitivity to latrunculin-A suggests that the proteins have opposite effects on actin dynamics. We propose that Sla2p recruits Sla1p to endocytic sites. Sla1p and its associated protein Pan1p then regulate actin assembly through interactions with Arp2/3 and Arp2/3-activating proteins Abp1p and Las17/Bee1p

A role for actin in aging and apoptosis

The actin cytoskeleton is central to many cell processes including membrane trafficking and generation of cell polarity. We have identified a role for actin in cell death and in promoting longevity of the budding yeast, Saccharomyces cerevisiae. Aging in yeast appears to occur via an apoptotic-like pathway with changes including DNA fragmentation, loss of mitochondrial membrane permeability, increase in levels of ROS (reactive oxygen species) and exposure of phosphatidylserine in the outer leaflet of the plasma membrane. This pathway can be induced by alterations in actin dynamics, such that reduced dynamics correlates with increased levels of ROS and decreased viability. Conversely, increased actin dynamics correlates with low ROS levels and increased survival. Our current studies have focused on identifying pathways which couple changes in actin dynamics to cell death

The actin cytoskeleton in ageing and apoptosis.

Regulated cell death, or apoptosis, has evolved to fulfil a myriad of functions amongst multicellular organisms. It is now apparent that programmed cell death occurs in unicellular organisms such as yeast. In yeast, as in higher eukaryotes, the actin cytoskeleton is an essential component of a number of cellular activities, and many of the regulatory proteins involved are highly conserved. Recent evidence from diverse eukaryotic systems suggests that the actin cytoskeleton has a role in regulating apoptosis via interactions with the mitochondria. This interaction also appears to have a significant impact on the management of oxidative stress and so cellular ageing. In this mini-review we summarise some of the work, which suggests that actin is a key regulator of apoptosis and ageing in eukaryotic cells

A new Canterbury tale: the eighth International Meeting on Yeast Apoptosis in Canterbury, UK, 2–6 May 2011

This spring, more than a hundred scientists from around the world gathered in Canterbury, the historic city in the county of Kent in South East England, to attend the eighth International Meeting on Yeast Apoptosis (IMYA). As with every IMYA conference since its inception in 2002, the feeling of being part of a community that is almost a family was evident. In addition, this year's meeting has shown that the field of yeast programmed cell death (PCD) is growing, not only in numbers, but also in its thematic scope