Apoptosis Detection Kits from IMGENEX: pSIVA: A polarity sensitive probe for the kinetic analysis of apoptosis
pSIVA™: Polarity Sensitive Indicator of Viability & Apoptosis New Tool for Apoptosis, Flow Cytometry & Microscopy
IMGENEX introduces pSIVA, the first reversible apoptosis probe for detecting phosphatidylserine (PS) exposure on plasma membranes. Exclusively available from IMGENEX.
pSIVA (Annexin XII) is an Annexin based, polarity sensitive probe for the spatiotemporal or kinetic analysis of apoptosis and other forms of cell death. pSIVA (Annexin XII) binding is reversible enabling researchers, for the first time, to detect transient PS exposure which is associated with normal physiological processes as well as with reversible or rescuable apoptosis cell death events.
pSIVA (Annexin XII) is conjugated to IANBD, a polarity sensitive dye that fluoresces only when pSIVA is bound to the cell membrane. pSIVA’s membrane-bound dependent fluorescence and reversible binding properties are a technological leap for detecting PS exposure and offer additional information on the apoptosis pathway and cell survival compared to Annexin V conjugates. Annexin V binding is nonreversible.
Detect early apoptosis
in vivo imaging
No washing required
Ephemeral or fleeting pSIVA-IANBD fluorescence signals accompany transient PS exposures associated with normal physiological or homeostatic events, artist's rendition as well as apoptosis. When PS flips back to the inner membrane following transient PS exposure, pSIVA-IANBD will be released back into the medium and fluorescence lost. Potential areas of study are shown in the cartoon. Note: The phenomenon of transient pSIVA-IANBD fluorescence exposure has been observed in unperturbed cultures as rapid on/off fluorescence, and is thought to represent normal membrane event. However, this is a wide open area of study and details remain to be elucidated.
pSIVA and the Kinetics of Apoptosis
Time-lapse imaging of primary rat dorsal ganglion (DRG) sensory neurons induced to undergo apoptosis by NGF deprivation. Images were taken from 9 hr after NGF withdrawal, and the movies were compiled at 6 frames per second with 20 min intervals between image frames. Movies 1 and 2 are of different neurons. pSIVA-IANBD (detects PS exposure): green. PI (detects loss of membrane integrity): red. Note that pSIVA-IANBD labels the axon prior to the cell body, and that pSIVA-IANBD fluorescence appears prior to PI staining.
Time-lapse imaging of rat DRG recovery from the brink of death showing reversibility of apoptosis for the first time. Neurons were deprived of NGF for 10 h to induce apoptosis. After 10 h, NGF was added back to the culture to induce rescue. Images were taken from 7.5 h after NGF withdrawal and the movie was compiled at 4 frames per second with a 30 min interval between image frames. pSIVA-IANBD: green. PI: red. Boxes highlight specific areas where the intensity of pSIVA-IANBD fluorescence reverses.
pSIVA and the Kinetics of Apoptosis Applications
• Toxicology Testing • High-Throughput Screening of Apoptosis Pathways and Processes • Confocal Microscopy • Flow Cytometry • In-vivo Imaging of Apoptosis
pSIVA (Apoptosis Pathway Kinetics) Product Citations 1. Engineering a polarity–sensitive biosensor for time-lapse imaging of apoptotic processes and degeneration. Kim YE, J Chen, JR Chan, R Langen. Nat Methods 7:67-73 (2010). Real-time live-cell imaging and time-lapse microscopy of apoptosis: Fig 2 (Cos-7 cells), Fig 3 (neuronal degeneration), Fig 4 (axonal degeneration), Fig 5 (rescue of neuronal degeneration as visualized by pSIVA) 2. Monitoring apoptosis and neuronal degeneration by real-time detection of phosphatidylserine externalization using a polarity-sensitive indicator of viability of apoptosis. Kim YE, J Chen, R Langen, JR Chan. Nature Protocols 5:1396-1405 (2010). Fig 2: Time-lapse microscopy of neurons in normal survival conditions and after NGF deprivation. pSIVA demonstrated transient exposure of PS associated with homeostasis. 3. Zhang CQ, Yeh T-l, A Leyva, LG Frank, J Miller, YE Kim, R Langen, S Finkbeiner, ML Amzel, CA Ross, MA Poirier. A compact B model of huntingtin toxicity. JBC 286:8188-8196 (2011). A pSIVA-IANBD based cell suspension toxicity assay was used to determine cell viability in mouse Neuro2A (neuroblastoma) overexpressing huntingtin proteins (Fig 4).