Effect of Sucrose on Phase Behavior of Membranes in Intact Pollen of Typha latifolia L., as Measured with Fourier Transform Infrared Spectroscopy

Abstract

In previous studies, we have shown that the temperature dependent vibrational frequency of the CH2 stretch in hydrocarbons in intact pollen grains can be recorded with Fourier transform infrared spectroscopy and used to measure phase transition temperatures (Tm) in these hydrocarbons. Circumstantial evidence was provided that the major contribution to the signal seen in these samples was from membrane phospholipids, and that sucrose in the dry pollen grains reduced Tm of those phospholipids. In the current study, we clarify why a major constituent of the pollen grains, neutral lipids contained in discrete lipid droplets, does not contribute significantly to the signal. Further, we have isolated membranes from the pollen and show that Tm in the isolated membranes rises from -60C in the hydrated membranes to 580C when the membranes are dried without the addition of sucrose. However, when the isolated membranes are dried in the presence of increasing amounts of sucrose, Tm fell steadily, reaching a minimal value of 310C, a figure in good agreement with that seen in the intact pollen grains. The amount of sucrose required to depress Tm maximally in these membranes is also apparently in agreement with that found in the intact pollen, suggesting that sucrose depresses Tm in the pollen.Certain disaccharides, such as trehalose and sucrose, apparently play a role in the acquisition of desiccation tolerance in living organisms. This suggestion was based on the occurrence of high levels of disaccharides in desiccation-tolerant organisms (1,8,24,25,28) and on studies in vitro of their protective effect on isolated membranes (7), liposomal membranes (15, 31), and proteins (4, 5) during drying and rehydration. Trehalose is the predominant disaccharide in organisms such as yeasts, fungi, the desert resurrection plant Selaginella (19), and microscopic animals (8), whereas anhydrobiotic organs of higher plants accumulate mainly sucrose (1,24,25)

Effect of disaccharides on survival during storage of freeze dried probiotics

“…On the other hand, an inverse relationship exists between the T g of a substance and the % RVP, with higher RVPs resulting in reduced T g -values and potential crystallisation. The ideal cryoprotective additive for stabilisation of probiotic microorganisms in a food product must maintain a high T g at humidity values recorded under normal storage conditions (22)(23)(24)(25) • C). We conclude that the disaccharides, trehalose, lactose, and lactose + maltose can provide a sufficient level of protection, ensuring minimum loss in cell viability especially at RVP values of 0.0 and 11.4%.…”

“…Freeze-dried samples (9 to 15 mg) were prepared in pre-weighed DSC aluminum pans (40 μL; Mettler Toledo-27331, Schwerzenbach, Switzerland) and stored in open pans for 144 h at [22][23][24][25] • C in evacuated desiccators over P 2 O 5 and different saturated salt solutions, as described previously, giving a water activity, a w , of 0.01 × RVP at equilibrium [27]. RVP of the saturated salt solutions were confirmed with an AquaLab CX-2 water activity meter.…”

“…Accumulation of disaccharides, especially sucrose and trehalose appears to be a common feature in such organisms [24,27,34]. Major research efforts have thus focused on the use of these and other disaccharides as additives to promote dessication tolerance during the drying process [4,8,29,36,40].…”

Environmental pollution changes in membrane lipids, antioxidants and vitality of Scots pine (Pinus sylvestris L.) pollen

“…Numerous stress factors such as low and high temperature, desiccation or imbibition (Hoekstra et al 1991 andSowa et al 1991), and industrial pollution, (Mulcahy and Mulcahy 1987), cause serious changes in the cytoplasmic membranes which affect vitality of the pollen grains. Most sensitive to injuries are water transportation and enzymes as well as the lipid-protein structure of membranes which carry the receptors of light, transmitters of signals, and channels of ions.…”

Drying Increases Intracellular Partitioning of Amphiphilic Substances into the Lipid Phase

“…The distribution of TEMPONE over the aqueous and lipidic environments depends on the partitioning coefficient of this spin probe and the volume of both environments available. Lipid is present in T. latifolia pollen as approximately 13.3% of the dry matter and consists of 8.0% neutral lipids and 5.3% polar lipids (Hoekstra et al, 1991). Drying of the pollen to 0.8 g water g Ϫ1 DW caused a considerable decrease in the polar peak and an increase in the lipid peak (Fig.…”