Long-term Low-temperature Storage Research Articles

Acid tolerance response of Salmonella during the squid storage and its amine production capacity analysis.

Salmonella exhibits a strong inducible acid tolerance response (ATR) under weak acid conditions, and can also induce high-risk strains that are highly toxic, acid resistant, and osmotic pressure resistant to aquatic products. However, the induction mechanism is not yet clear. Therefore, this study aims to simulate the slightly acidic, low-temperature, and high-protein environment during squid processing and storage. Through λRed gene knockout, exploring the effects of low-acid induction, long-term low-temperature storage, and two-component regulation on Salmonella ATR. In this study, we found the two-component system, PhoP/PhoQ and PmrA/PmrB in Salmonella regulates the amino acid metabolism system and improves bacterial acid tolerance by controlling arginine and lysine. Compared with the two indicators of total biogenic amine and diamine content, biogenic amine index and quality index were more suitable for evaluating the quality of aquatic products. The result showed that low-temperature treatment could inhibit Salmonella-induced ATR, which further explained the ATR mechanism from the amino acid metabolism.

Assessment of the reliability of serological monitoring results based on biobank materials

Aim. To evaluate the safety of immunoglobulins (Ig) of different classes (IgA, IgM, IgG, IgE) under conditions of long-term low-temperature storage of blood serum samples.Material and methods. The work used samples of blood serum from the collection of the Department of Epidemiology, examined by enzyme immunoassay for antibodies of classes IgA, IgM, IgG, IgE twice as follows: immediately upon receipt in the laboratory and after storage at a temperature of -70о C for 8 years.Results. After the storage of seropositive sera, the level of IgA antibodies did not change significantly (p=0,7). For the remaining classes of immunoglobulins (IgM, IgG, IgE), a small (not >15%) but significant decrease (p<0,05), most pronounced for IgE, was observed. It was shown that the higher the antibody level in the samples during the first study, the more it decreased after long-term storage (correlation at p<0,05). This did not lead to false negative results, which is due to the greater accuracy in measuring small values.Conclusion. Long-term low-temperature storage of serum samples in biobank conditions ensures the safety of antibodies of different classes and is the basis for the reliability of future studies.

Концентрированные молочные модельные системы: изменение качества в процессе низкотемпературного хранения

One of the ways to solve the problem of low storability of raw milk is the use of frozen milk concentrates. A comprehensive understanding of the impact of negative temperatures on the stability and properties of dairy systems during long-term storage and further processing is necessary to assess the potential of their use. The effect of long-term low-temperature storage on the organoleptic, physico-chemical and technological properties of concentrated model milk systems has been studied. Stability of milk systems samples was kept for 3 months, further significant stratification of consistence and formation of protein flakes were registered. Mass fractions of protein, fat, lactose, as well as titratable and active acidity did not change significantly. On the alcohol and heat samples significant changes were noted only after 6 months of storage. Based on the data obtained, the duration of storage after freezing milk systems should not exceed 3 months.

Low temperatures inhibit the pectin degradation of ‘Docteur Jules Guyot’ pear (Pyrus communis L.)

The most remarkable characteristic of European pears is extremely perishable and difficult to store after postharvest softening. Low-temperature storage is one of the most commonly used methods to prolong the shelf life of European pears. However, the regulatory mechanism of the low-temperature delay of the softening of European pears is still unclear. In this study, the fruit firmness, pectin polysaccharide content, pectin-degrading enzyme activity, and pectin degradation gene expression of ‘Docteur Jules Guyot’ pears under low temperature (LT) and room temperature (RT) were analyzed. It was found that water-soluble pectin (WSP) was significantly negatively correlated with fruit flesh firmness, and the activities of several pectin-degrading enzymes were inhibited under LT storage conditions. In addition, it was also found that the gene expression patterns of PcPME2, PcPME3, PcPG1, PcPG2, PcPL, PcGAL1, PcGAL2, PcGAL4, and PcARF1 were inhibited by LT. The C-repeat binding factors PcCBF1 and PcCBF2 were also inhibited by long-term LT storage. Correlation analysis showed that the expression of PcCBFs was positively correlated with pectin-degradation enzyme genes, and we found that the promoters of many pectin-degradation enzyme genes contain the CRT/DRE motif, which CBF can directly bind. Therefore, it is speculated that long-term low-temperature conditions inhibit pectin degradation through PcCBFs.

Enzyme Composition Modeling and Its Application in the Baking Cryotechnology

Cryotechnologies are widely used in the production of bakery products, including dough. The study aim is to optimize the enzyme composition and evaluate its application effectiveness in the technology of rye-wheat bread based on frozen dough. To solve nonlinear problems and the fractional factor experiment method a man applied algorithms of the generalized reduced gradient method. As a result of data analysis using MS Office Excel, the maximum possible concentrations of the enzyme complex components are, wt. %: “Pentopan 500 BG” – 12.0, “Novamil 1500 MG” – 5.0 and “Neutrase 1.5 MG” – 2.0; the optimal ratio is 6:2.5:1. The authors run the recipe optimization of rye-wheat bread based on frozen dough using Statgraphics 18.1 and constructing mathematical models based on multifactorial analysis. The variables were the dosages of the enzyme composition 4–10 % by weight of flour and dry starter culture of lactic acid bacteria 0.05–0.15 % by weight of flour; the required functions were porosity and specific volume of rye-wheat bread. As the mathematical data processing result, a man received regression dependence equations of rye-wheat bread porosity and specific volume on the components concentrations; optimal dry starter concentrations and enzyme composition – 0.12 and 7.5 % by weight of flour, respectively. The thesis provides physicochemical, organoleptic and structural-mechanical characteristics of rye-wheat bread developed on the cryotechnology basis after long-term low-temperature storage of test dough at a temperature of minus 18–20 ° C for 150 days, confirming the enzyme composition effectiveness.

Characterization and expression analysis of basic leucine zipper (bZIP) transcription factors responsive to chilling injury in peach fruit.

Peach (Prunus persica L.) is prone to chilling injury as exhibited by inhibition of the ethylene production, failure in softening, and the manifestation of internal browning. The basic leucine zipper (bZIP) transcription factors play an essential role in regulatory networks that control many processes associated with physiological, abiotic and biotic stress responses in fruits. Formerly, the underlying molecular and regulatory mechanism of (bZIP) transcription factors responsive to chilling injury in peach fruit is still elusive. In the current experiment, the solute peach 'Zhongyou Peach No. 13' was used as the test material and cold storage at low temperature (4°C). It was found that long-term low-temperature storage induced the production of ethylene, the hardness of the pulp decreased, and the low temperature also induced ABA accumulation. The changes of ABA and ethylene in peach fruits during low-temperature storage were clarified. Since the bZIP transcription factor is involved in the regulation of downstream pathways of ABA signals, 47 peach bZIP transcription factor family genes were identified through bioinformatics analysis. Further based on RT-qPCR analysis, 18 PpbZIP genes were discovered to be expressed in refrigerated peach fruits. Among them, the expression of PpbZIP23 and PpbZIP25 was significantly reduced during the refrigeration process, the promoter analysis of these genes found that this region contains the MYC/MYB/ABRES binding element, but not the DRES/CBFS element, indicating that the expression may be regulated by the ABA-dependent cold induction pathway, thereby responding to chilling injury in peach fruit. Over investigation will provide new insights for further postharvest protocols related to molecular changes during cold storage and will prove a better cope for chilling injury.

Dependence of the content of starch and reducing sugars on the level of expression of the genes of β-amylases StBAM1 and StBAM9 and the amylase inhibitor StAI during long-term low-temperature storage of potato tubers.

Solanum tuberosum L. is the most important non-grain starch crop with a potential yield of 38–48 t/ha and a starch content of 13.2–18.7 %. Potato tubers are stored at a low temperature (2–4 °C) in a state of physiological dormancy. A disadvantage of this type of storage is the degradation of starch and the accumulation of reducing sugars (cold-induced sweetening), including due to an increase in the activity of β-amylases that hydrolyze starch to maltose. In this study, a comparative analysis of the β-amylase (StBAM1, StBAM9) and amylase inhibitor (StAI ) gene expression, as well as starch and reducing sugar content in tubers during long-term low-temperature storage (September, February, April) was performed using potato cultivars Nadezhda, Barin, Krasavchik, Severnoe siyanie and Utro. The β-amylase genes, StBAM9 and one of the two StBAM1 homologs (with the highest degree of homology with AtBAM1), were selected based on phylogenetic analysis data. Evaluation of the expression of these genes and the amylase inhibitor gene showed a tendency to decrease in transcription for all analyzed cultivars. The starch content also significantly decreased during tuber storage. The amount of reducing sugars increased in the September–April period, while in February–April, their content did not change (Krasavchik), decreased (Barin, Severnoe siyanie) or continued to grow (Utro, Nadezhda). It can be assumed that the gene activity of StBAM1 and StBAM9 correlates with the amount of starch (positively) and monosaccharides (negatively). The level of StAI expression, in turn, may be directly dependent on the level of StBAM1 expression. At the same time, there is no relationship between the degree of cultivar predisposition to cold-induced sweetening and the expression profile of the StBAM1, StBAM9, and StAI genes.

CaCl2 mitigates chilling injury in loquat fruit via the CAMTA5-mediated transcriptional repression of membrane lipid degradation genes

Loquat fruit is vulnerable to chilling injury (CI) under long-term low temperature storage. The application of calciumchloride (CaCl2) can alleviate CI in loquat fruit, however, the molecular mechanisms remain unclear. In this study, the loquat fruit were immersed in 1 % CaCl2 solution for 10 min and then stored at 1 ± 1 ℃ for 35 d. The results showed that CaCl2 treatment suppressed the increases in internal browning index, electrolyte leakage, and malonaldehyde content in loquat fruit under chilling stress. The internal browning index in CaCl2-treated loquat fruit was 33.34 % lower than that in the control at the end of storage. Meanwhile, CaCl2 treatment delayed the phospholipids degradation, and retained high level of unsaturated/saturated fatty acid ratio, which was 15.21 % higher than that in the control fruit at the end of storage. The CaCl2 treatment also decreased the enzymatic activities and gene expressions of phospholipase D (PLD), phospholipase C (PLC), and lipoxygenase (LOX) in loquat fruit during cold storage. Moreover, a calmodulin-binding transcription activator (CAMTA) transcription factor (TF), EjCAMTA5, was cloned from loquat fruit. The EjCAMTA5 expression was up-regulated by cold stress and CaCl2 treatment. Further investigation revealed that EjCAMTA5 directly bound to the promoters of EjPLC6-like and EjLOX5 to repress their transcription. Taken together, these findings implied that CaCl2 application could activate the EjCAMTA5-mediated transcriptional repression of EjPLC6-like and EjLOX5 genes, which contributed to delaying the degradation of membrane lipid and maintaining the integrity of cell membrane, thereby inhibiting the occurrence of browning in loquat fruit under chilling stress.

Successive mycelial subculturing decreased lignocellulase activity and increased ROS accumulation in Volvariella volvacea.

Strain degradation is a common problem in many artificially-cultivated edible mushrooms. As a fungus with poor tolerance to low-temperature, Volvariella volvacea cannot delay its degradation by long-term low temperature storage like other fungi, so its degradation is particularly severe, which hinders industrial applications. Periodic mycelial subculture is a common storage method for V. volvacea, but excessive subculturing can also lead to strain degeneration. After 20 months of continuous subculturing every 3 days, V. volvacea strains S1–S20 were obtained, and their characteristics throughout the subculture process were analyzed. With increasing number of subculture, the growth rate, mycelial biomass, the number of fruiting bodies and biological efficiency gradually decreased while the production cycle and the time to primordium formation was lengthened. Strains S13–S20, obtained after 13–20 months of mycelial subculturing, also lacked the ability to produce fruiting bodies during cultivation experiments. Determination of reactive oxygen species (ROS) content as well as enzyme activity showed that decreased lignocellulase activity, along with excessive accumulation of ROS, was concomitant with the subculture-associated degeneration of V. volvacea. Reverse transcription polymerase chain reaction (RT-PCR) was eventually used to analyze the gene expression for lignocellulase and antioxidant enzymes in subcultured V. volvacea strains, with the results found to be consistent with prior observations regarding enzyme activities. These findings could form the basis of further studies on the degeneration mechanism of V. volvacea and other fungi.

Subspecific Features in Maintaining the Viability of Rice Seeds and the Productivity of Their Progeny after Long-Term Low-Temperature Storage of Oryza Sativa L Germplasm

To save genetic diversity of rice (Oryza sativa L.), accumulated in the collections of genebanks and scientific institutions, various methods and modes of seed storage are used. However, in the process of long-term low-temperature storage, there is a loss of seed viability among rice samples. With the aim of a differentiated approach to the choice of conditions, methods and terms of preservation of the gene pool of "Federal Scientific Rice Centre" (Krasnodar), the viability of seeds after operational and long-term storage was studied in 1252 samples of indica and japonica subspecies of 37 varieties. The influence of the temperature regime of seed storage for 3, 5, 10 and 35 years on the viability of the intraspecific diversity of rice is shown. In uncontrolled conditions for three years the seeds lost their germination by varieties by 20-68%, and at a temperature of +4.5 ° C - by 5-13%. After 25 years of storage, the seeds of long-grain samples of the indica subspecies, as well as red-grain and awned forms, had the greatest viability. A clear relationship between grain size and its durability has not been identified. After 10 years of low-temperature storage, rice seeds give full-fledged progeny and retain plant productivity at the level of freshly harvested seeds. From the gene pool of the world rice collection, varieties with greater biological longevity of seeds were isolated.

Optimization of UC-MSCs cold-chain storage by minimizing temperature fluctuations using an automatic cryopreservation system

The effective long-term cryopreservation of human mesenchymal stem cells is an essential prerequisite step and represents a critical approach for their sustained supply in basic research, regenerative medicine, and tissue engineering applications. Off-the-shelf availability of human umbilical cord-derived mesenchymal stromal cells (UC-MSCs) for regenerative medicine application requires the development of nontoxic, safe, and efficient protocols for cryopreservation. In the long-term low-temperature storage process of cells, traditional manual storage has a great impact on cell activity, recovery, and function due to repeated exposure of cells to room temperature. To minimize the effect of fluctuation in ambient temperature on stored cells, we designed an automatic cryopreservation system that handles cells under controlled temperatures. In this work, UC-MSCs were utilized to investigate and compare the influence of manual and automatic cryopreservation approaches. To simulate the manual process, the UC-MSCs were transferred back and forth repeatedly (up to 400 times) between the liquid nitrogen (LN2) tank (−150 °C) and room temperature by a robotic arm. Similarly, the UC-MSCs from the same batch were collected and transferred repeatedly between two storage units by the automatic cryopreservation system, where the cells were maintained below-150 °C throughout the cold chain process. Viability, percent recovery, adherence capability, cell proliferation, and multilineage differentiation ability were assessed for UC-MSCs. Compared to the manual approach, UC-MSCs handled by the automatic system demonstrated higher viability, percent recovery, and cell proliferation, as well as improved adherence to culture plate with greater potential in multilineage differentiation after 400 temperature cycles. The described entire cold chain system may provide a powerful tool to develop safe, reliable and efficient protocols for manufacturing and banking of UC-MSCs, improving their off-the-shelf availability for regenerative medicine applications.

Effects of harvest maturity stage on postharvest quality of winter jujube (Zizyphus jujuba Mill. cv. Dongzao) fruit during cold storage

Fruit maturity stage at harvest is a fundamental factor for successful storage and final quality of post-harvest fruit. The current study planned to investigate the changes in postharvest quality in winter jujube at three maturity stages (white maturity, half-red maturity, and red maturity stages) under cold storage (0 ± 1 °C). The results showed that there was significant effect among the maturity stage at harvest on storage quality parameters in winter jujube during cold storage. Fruit firmness, titratable acid (TA), L*, and b* in winter jujube fruit significantly declined from white maturity stage to red maturity stage, and decreased significantly with the extension of cold storage time. Decay incidence, ratio of sugar and acid (TSS/TA), a*, ethanol content increased from white maturity stage to red maturity stage, and rose significantly with increasing of cold storage time. At the end of storage, the white maturity stage showed the highest fruit firmness, TA content, L*, b* as well as the lowest decay incidence, a*, ethanol content, while the half-red maturity stage displayed the highest content of total soluble solid (TSS), ascorbic acid (AsA), total phenolics and total flavonoids as well as the lowest weight loss, respiration rate. In addition, the half-red maturity stage fruit maintained better sensory quality during the shelf life. Considering the results of all quality parameters mentioned above, the winter jujube fruit harvested at half-red maturity stages were the ideal harvest maturity for long-term low temperature storage attributing to its stable storability and a higher consumer acceptability after cold storage.

THE INFLUENCE OF PHYSICAL METHODS OF VEGETABLES PROCESSING ON THE QUALITY OF FROZEN PRODUCTS

The indicators of quality and microbiological safety of frozen vegetable semi-finished products (for example, cut beet) processed in a microwave field for subsequent storage for 18 months at a temperature of minus 20±2 °C. Treatment with a microwave field was carried out under the following conditions: power 600 W and duration 5 min (180 kJ); power 1000 W and duration 4 min (240 kJ). It is established that treatment in the microwave field contributes to the preservation of consumer qualities of the product (total solids content, mass fraction of soluble solids, bound moisture content, microbiological effect) in the process of long-term low-temperature storage.

Гіпотермічне та низькотемпературне зберігання рослин-регенерантів і меристем часнику (Allium sativum L.) для створення in vitro колекцій

New methods to establish various types of plant genetic collection are developed in Ukraine in order to preserve the existing species and varieties. This research deals with the effects of short-term hypothermic (4°C) and long-term low temperature (–196°C) storage on viability of the collection samples of garlic ( Allium sativum L. ). In the first case the culture of garlic sprout of Duchess variety was stored in vitro at the temperature of 4°C in the Murashige-Skoog (MS) medium with different mineral composition (1/2 MS and MS) in the dark for 3, 6, 9 and 12 months as well as in MS medium with various concentrations of sucrose (4.5, 6, 9 and 12%) at 22°C. The material for long-term low temperature storage of the garlic samples in liquid nitrogen were the meristems of different development type, Duchess (winter) and Manuilivskyy (spring) varieties. The apices were dehydrated in plant vitrification solution (1 M sucrose + 2 M glycerol + 2.5 M ethylene glycol) for 120 min, placed into cryovials and immersed into liquid nitrogen. The samples were stored at the temperature of –196°C for 5 years. The storage at 4°C in 1/2 MS medium provided the maximum preservation of the regenerated plants during a year (94.4%). During culturing at 22°C the highest viability (85%) was observed in the medium, containig 12% sucrose. Long-term storage of garlic meristem at –196°C did not affect the viability and growth rate if compared to the apices, thawed an hour after plunging into liquid nitrogen. The viability of vitrified-warmed garlic meristems of Duchess and Manuilivskyy varieties was about 60%. Probl Cryobiol Cryomed 2017; 27(2): 110–120

Intermittent warming improves postharvest quality of bell peppers and reduces chilling injury

The long-term low temperature storage of pepper fruit is currently risky because of the likelihood of chilling injury (CI), which reduces shelf-life. Intermittent warming (IW) has been proposed as a potential solution to enhance successful long-term pepper fruit storage. To understand the influence of IW in alleviating CI in peppers, the effects of 3 IW cycles were tested on the organic acid content, firmness, and relative enzyme content of pepper fruit (namely, 1–3 IW cycles to 20°C for 24h every 7 days for fruit stored at 4°C for 27 days). Subsequently, the effects of 2 IW cycles were tested on the organizational structure of pepper fruit cells and potential odor changes. The results showed that IW effectively reduces the CI index and maintains pepper firmness. Following 2 IW cycles after 6 and 13 days storage, pepper integrity was retained, with no shrinkage or decay. Furthermore, partial least squares analysis of odor changes showed that both 1 IW cycle after 20 days storage and 2 IW cycles after 6 and 13 days storage extended storage time to over 10 days. The appropriate IW cycles effectively delay the decline in unsaturated fatty acid content and maintain a higher index of unsaturated fatty acids (IUFA), which helps retain the integrity of the pepper cell membranes.

A Method of Low-Temperature Storing of Agarose Slides with Lysed Cells

A method has been developed for a long-term low-temperature storage (-10 to -15°C) of the agarose slides with nucleoids (lysed eukaryotic cells). After lysis of agarose-immobilized cells, the slides were incubated for 30 min in phosphate buffer with 50% glycerol and 100 mM EDTA, thereupon they were stored in a freezer at -10 to -15°C. After long-term storage, the slides were re-incubated for 30 min in lysing solution. The measurements of the baseline and in vitro induced DNA damage in nucleoids of the human and mouse leukocytes, which had been stored in agarose slides at low temperature, showed that DNA damage level determined after a 40-day storage did not significantly differ from that of the fresh slides. The advanced storage method is simple and reliable; it opens the way to avoid cryopreservation of the biological samples and to process little by little a great number of the identically prepared slides.

Cold Storage of Culex pipiens in the Absence of Diapause

A major expenditure in vector biology laboratories is the rearing of mosquitoes. Most mosquito colonies require substantial effort to maintain, including frequent bloodmeals for optimal performance. Successful cryopreservation of mosquitoes continues to be elusive. Although using diapause as a storage mechanism is an option for mosquito preservation, several obstacles include the lack of a well-characterized diapause or the inability of some species to enter diapause. Thus, other options for preservation are needed. To address this issue, we investigated the use of long-term low-temperature storage in the absence of diapause for adults of the northern house mosquito, Culex pipiens L. Our results indicate that although male longevity is not substantially increased by cold storage, female longevity is dramatically increased by storage at lower temperatures. When mated before storage, females remain reproductively viable after at least 10 wk of storage, although at reduced levels. These results indicate that cold storage without diapause induction is a viable option for colony maintenance in vector biology laboratories.

Cold storage and cryopreservation of tick cell lines

BackgroundTick cell lines are now available from fifteen ixodid and argasid species of medical and veterinary importance. However, some tick cell lines can be difficult to cryopreserve, and improved protocols for short- and long-term low temperature storage will greatly enhance their use as tools in tick and tick-borne pathogen research. In the present study, different protocols were evaluated for cold storage and cryopreservation of tick cell lines derived from Rhipicephalus (Boophilus) decoloratus, Rhipicephalus (Boophilus) microplus, Ixodes ricinus and Ixodes scapularis. For short-term cold storage, cells were kept under refrigeration at 6°C for 15, 30 and 45 days. For cryopreservation in liquid nitrogen, use of a sucrose-phosphate-glutamate freezing buffer (SPG) as cryoprotectant was compared with dimethylsulfoxide (DMSO) supplemented with sucrose. Cell viability was determined by the trypan blue exclusion test and cell morphology was evaluated in Giemsa-stained cytocentrifuge smears.ResultsCold storage at 6°C for up to 30 days was successful in preserving R. (B.) microplus, R. (B.) decoloratus, I. ricinus and I. scapularis cell lines; lines from the latter three species could be easily re-cultivated after 45 days under refrigeration. While cell lines from all four tick species cryopreserved with 6% DMSO were successfully resuscitated, the R. (B.) decoloratus cells did not survive freezing in SPG and of the other three species, only the R. (B.) microplus cells resumed growth during the observation period.ConclusionsThis constitutes the first report on successful short-term refrigeration of cells derived from R. (B.) decoloratus, R. (B.) microplus, and I. ricinus, and use of SPG as an alternative to DMSO for cryopreservation, thus making an important contribution to more reliable and convenient tick cell culture maintenance.

Diapause in the egg parasitoid Trichogramma cordubensis: role of temperature

The role of temperature in the induction of diapause in Trichogramma cordubensis (Hymenoptera: Trichogrammatidae), under controlled laboratory conditions, was investigated using Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs as hosts. Results indicate that prestorage temperatures and the duration of exposure of the parasitoids to these temperatures affected the induction of diapause. It was possible to induce diapause in prepupae of T. cordubensis by exposing the preimaginal stages (prior to the prepupal stage) to 10°C for at least 30 days, but adults emerged without diapause when the duration of exposure was of only 10 or 20 days. Parasitoids failed to enter diapause when prestorage temperatures were 7 or 12°C, regardless of the duration of exposure. However, at these two temperatures, preimaginal development of T. cordubensis was delayed, allowing short-term storage (40 days at induction temperatures followed by 30 days at 3°C) by keeping parasitoids in quiescence without reducing the percentages of adult emergence. Good percentages of adult emergence after long-term low-temperature storage (30 or 40 days at 10°C followed by six months at 3°C) occurred only when T. cordubensis was in diapause. The long-term storage of parasitoids in diapause allows an enlargement in the mass rearing potentialities of this species for future biological control releases by allowing producers to stockpile the parasitoids for release in the field season.

Membrane phase transition of intact human platelets: correlation with cold-induced activation.

Using Fourier transform infrared spectroscopy (FTIR), we have determined the phase transition temperature (Tm) of lipids in intact human platelets and have shown that it occurs between 15 and 18 degrees C, the temperature at which cold activation of platelets has previously been reported (Zucker and Borrelli, 1954, Blood, 28:602-608; White and Krivit, 1967, Blood, 30:625-635). The temperature at which the platelets pass through Tm is highly correlated with initial platelet shape change. However, shape change continues after the cells have passed through the phase transition. Cold-induced activation has previously prevented long-term storage of platelets at 4 degrees C. Antifreeze glycoproteins (AFGPs) isolated from polar fishes previously have been used to prevent ice crystal growth during freezing of tissues as well as leakage of solutes from liposomes as they were chilled through their Tm. We sought to determine if these AFGPs were able to stabilize platelets for long-term storage at 4 degrees C. Incubating platelets with antifreeze glycoproteins during long-term storage and rapid rewarming to 37 degrees C abrogated granule secretion associated with cold activation in a dose-dependent manner. This work suggests that AFGPs may be a possible solute for use in long-term low temperature storage of platelets.