PubMed · 10802567
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A G de Castro, J Lapinski, A Tunnacliffe. 2000. Anhydrobiotic engineering.. https://doi.org/10.1038/75237
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We utilized a proteomic approach to investigate seed development in Medicago truncatula, cv Jemalong, line J5 at specific stages of seed filling corresponding to the acquisition of germination capacity and protein deposition. One hundred twenty proteins differing in kinetics of appearance were subjected to matrix-assisted laser desorption ionization time of flight mass spectrometry. These analyses provided peptide mass fingerprint data that identified 84 of them. Some of these proteins had previously been shown to accumulate during seed development in legumes (e.g. legumins, vicilins, convicilins, and lipoxygenases), confirming the validity of M. truncatula as a model for analysis of legume seed filling. The study also revealed proteins presumably involved in cell division during embryogenesis (beta-tubulin and annexin). Their abundance decreased before the accumulation of the major storage protein families, which itself occurs in a specific temporal order: vicilins (14 d after pollination [DAP]), legumins (16 DAP), and convicilins (18 DAP). Furthermore, the study showed an accumulation of enzymes of carbon metabolism (e.g. sucrose synthase, starch synthase) and of proteins involved in embryonic photosynthesis (e.g. chlorophyll a/b binding), which may play a role in providing cofactors for protein/lipid synthesis or for CO2 refixation during seed filling. Correlated with the reserve deposition phase was the accumulation of proteins associated with cell expansion (actin 7 and reversibly glycosylated polypeptide) and of components of the precursor accumulating vesicles, which give rise to a trypsin inhibitor on maturation. Finally, we revealed a differential accumulation of enzymes involved in methionine metabolism (S-adenosyl-methionine synthetase and S-adenosylhomo-cysteine hydrolase) and propose a role for these enzymes in the transition from a highly active to a quiescent state during seed development.
Folate concentrations in rosehips and commercial rosehip products and factors affecting folate retention during drying were investigated. On the basis of the raw material studied during 3 years, rosehips were shown to be a rich folate source, 400-600 microg/100 g based on dry matter and 160-185 microg/100 g based on the fresh weight (edible part). Rosehips are not often consumed fresh; therefore, drying to produce stable semimanufactures is a crucial step. The degradation of folate was shown to be dependent on the drying time until the water activity was below 0.75. The required drying time was reduced by cutting the rosehips in slices and to some extent also by increasing the temperature. Retention of folate and ascorbic acid was affected by the same factors, and high content of ascorbic acid could provide a possible protection for folate degradation.
Raffinose family oligosaccharides (RFO) have been implicated as protective agents in the cellular dehydration tolerance, especially of many plant seeds. However, their efficacy in stabilizing membranes during dehydration has never been systematically investigated. We have analyzed the effects of sucrose, raffinose, stachyose, and verbascose on liposome stability during air-drying. With increasing degree of polymerization (DP), the RFO were progressively better able to stabilize liposomes against leakage of aqueous content and against membrane fusion after rehydration. Indeed, there was a very tight linear correlation between fusion and leakage for all RFO. These data indicate that increased protection of liposomes against leakage with increasing DP is due to better protection against fusion. This is in accord with the higher glass transition temperature of the longer chain oligosaccharides. Further evidence for the influence of glass transitions on membrane stability in the dry state was provided by experiments testing the temperature dependence of membrane fusion. During incubation at temperatures up to 95 degrees C for 2 h, fusion increased less with temperature in the presence of higher DP sugars. This indicates that RFO with a higher glass transition temperature are better able to protect dry membranes at elevated temperatures. In addition, Fourier-transform infrared (FTIR) spectroscopy showed a reduction of the gel to liquid-crystalline phase transition temperature of dry liposomes in the presence of all investigated sugars. However, the RFO became slightly less effective with increasing chain length, again pointing to a decisive role for preventing fusion. A direct interaction of the RFO with the lipids was indicated by a strong effect of the sugars on the phosphate asymmetric stretch region of the infrared spectrum.