Background: Elevated temperatures jeopardize plant disease resistance, as mediated by salicylic acid (SA). SA potentiates heat-induced expression of the 70-kDa heat shock protein (Hsp70) in tomato cells. In mammalian cells, Hsp70 suppresses apoptosis. We hypothesized that potentiation of heat-induced Hsp70 by SA contributes to a reduction in apoptosis in tobacco protoplasts. Methods: Tobacco protoplasts (Nicotiana tabacum) were exposed to SA (70 M) at normal temperatures or in combination with heat shock. Hsp70/Hsc70 accumulation and phosphatidylserine (PS) exposure, DNA fragmentation, as well as loss of mitochondrial membrane potential were quantified by flow cytometry. Results and Conclusions: SA at normal temperatures did not influence Hsp70/Hsc70 accumulation, but were

The establishment of the health-promoting benefits of probiotics is challenged by the antimicrobial bio-barriers throughout the host's gastrointestinal (GI) tract after oral administration. Although microencapsulation has been frequently utilised to enhance the delivery of probiotics, microcapsules of sub-100 μm were found to be ineffective and therefore questioned as an effective delivery vehicle for viable probiotics despite the sensory advantage. In this study, four probiotics strains were encapsulated in chitosan-coated alginate microcapsules of sub-100 μm. Only a minor protective effect was observed from this original type of microcapsule. In order to enhance the survival of these probiotics, sucrose, a metabolisable sugar, and lecithin vesicles were added to the wall material. Both of the ingredients could be readily encapsulated with the probiotics, and protected them from stresses in the simulated GI fluids. The metabolisable sugar effectively increased the survival of the probiotics in gastric acid, mainly through energizing the membrane-bound F1F0-ATPases. The lecithin vesicles proved to alleviate the bile salt stress, and hence notably reduced the viability loss at the elevated bile salt concentrations. Overall, three out of the total four probiotics in the reinforced sub-100 μm microencapsules could significantly survive through an 8-h sequential treatment of the simulated GI fluids, giving less than 1-log drop in viable count. The most vulnerable strain of bifidobacteria also yielded a viability increase of 3-logs from this protection. In conclusion, the sub-100 μm microcapsules can be a useful vehicle for the delivery of probiotics, as long as suitable protectants are incorporated in the wall matrix.

Background: We present evidence that in plant cells DNA damage induced by the topoisomerase trapping drug camptothecin induces oxidative stress via the mitochondrial respiratory chain. Methods: Flow cytometry was used to analyse mitochondrial respiratory chain activity by simultaneous measurement of mitochondrial generation of reactive oxygen intermediates (ROI) and mitochondrial membrane potential (⌬⌿ m ), in live functioning sugarbeet protoplasts. The mitochondrial respiratory chain function was assessed by the addition of substrate and inhibitors to the digitonin-permeabilised protoplasts. Mitochondrial activity was also measured in protoplasts at different stages of induced apoptosis by camptothecin. Results: The addition of camptothecin to sugarbeet protoplasts resulted in increased mitochondrial generation of ROI, occurring concurrently with the hyperpolarisation of