Transient Warming Events Research Articles

Arctic vegetation, temperature, and hydrology during Early Eocene transient global warming events

Early Eocene global climate was warmer than much of the Cenozoic and was punctuated by a series of transient warming events or ‘hyperthermals’ associated with carbon isotope excursions when temperature increased by 4–8 °C. The Paleocene-Eocene Thermal Maximum (PETM, ~55 Ma) and Eocene Thermal Maximum 2 (ETM2, 53.5 Ma) hyperthermals were of short duration (<200 kyr) and dramatically restructured terrestrial vegetation and mammalian faunas at mid-latitudes. Data on the character and magnitude of change in terrestrial vegetation and climate during and after the PETM and ETM2 at high northern latitudes, however, are limited to a small number of stratigraphically restricted records. The Arctic Coring Expedition (ACEX) marine sediment core from the Lomonosov Ridge in the Arctic Basin provides a stratigraphically expanded early Eocene record of Arctic terrestrial vegetation and climates. Using pollen/spore assemblages, palynofacies data, bioclimatic analyses (Nearest Living Relative, or NLR), and lipid biomarker paleothermometry, we present evidence for expansion of mesothermal (Mean Annual Temperatures 13–20 °C) forests to the Arctic during the PETM and ETM2. Our data indicate that PETM mean annual temperatures were ~2° to 3.5 °C warmer than those of the Late Paleocene. Mean winter temperatures in the PETM reached ≥5 °C (~2 °C warmer than the late Paleocene), based on pollen-based bioclimatic reconstructions and the presence of palm and Bombacoideae pollen. Increased runoff of water and nutrients to the ocean during both hyperthermals resulted in greater salinity stratification and hypoxia/anoxia, based on marked increases in concentration of massive Amorphous Organic Matter (AOM) and dominance of low-salinity dinocysts. During the PETM recovery, taxodioid Cupressaceae-dominated swamp forests were important elements of the landscape, representing intermediate climate conditions between the early Eocene hyperthermals and background conditions of the late Paleocene. • Arctic vegetation in the PETM and ETM2 included broadleaf forests, palms, and subtropical taxa. • Taxodioid swamp forests dominated Arctic landmasses during the PETM recovery. • Mixed conifer-broadleaf forests occupied Arctic sites during non-hyperthermals. • Proxy data indicate increased runoff and hypoxia during Eocene hyperthermals. • Bioclimatic and brGDGT indicators show ~2–3.5 °C warming during hyperthermals.

A High‐Fidelity Benthic Stable Isotope Record of Late Cretaceous–Early Eocene Climate Change and Carbon‐Cycling

AbstractThe Late Cretaceous–Early Paleogene is the most recent period in Earth history that experienced sustained global greenhouse warmth on multimillion year timescales. Yet, knowledge of ambient climate conditions and the complex interplay between various forcing mechanisms are still poorly constrained. Here we present a 14.75 million‐year‐long, high‐resolution, orbitally tuned record of paired climate change and carbon‐cycling for this enigmatic period (~67–52 Ma), which we compare to an up‐to‐date compilation of atmospheric pCO2 records. Our climate and carbon‐cycling records, which are the highest resolution stratigraphically complete records to be constructed from a single marine site in the Atlantic Ocean, feature all major transient warming events (termed “hyperthermals”) known from this time period. We identify eccentricity as the dominant pacemaker of climate and the carbon cycle throughout the Late Maastrichtian to Early Eocene, through the modulation of precession. On average, changes in the carbon cycle lagged changes in climate by ~23,000 years at the long eccentricity (405,000‐year) band, and by ~3,000–4,500 years at the short eccentricity (100,000‐year) band, suggesting that light carbon was released as a positive feedback to warming induced by orbital forcing. Our new record places all known hyperthermals of the Late Maastrichtian–Early Eocene into temporal context with regards to evolving ambient climate of the time. We constrain potential carbon cycle influences of Large Igneous Province volcanism associated with the Deccan Traps and North Atlantic Igneous Province, as well as the sensitivity of climate and the carbon‐cycle to the 2.4 million‐year‐long eccentricity cycle.

Hemodynamic responses to warming in euryhaline rainbow trout: implications of the osmo-respiratory compromise.

In seawater, rainbow trout (Oncorhynchus mykiss) drink and absorb water through the gastrointestinal tract to compensate for water passively lost to the hyperosmotic environment. Concomitantly, they exhibit elevated cardiac output and a doubling of gastrointestinal blood flow to provide additional O2 to the gut and increase convective flux of absorbed ions and water. Yet, it is unknown how warming waters, which elevate tissue O2 demand and the rate of diffusion of ions and water across the gills (i.e. the osmo-respiratory compromise), affects these processes. We measured cardiovascular and blood variables of rainbow trout acclimated to freshwater and seawater during acute warming from 11 to 17°C. Relative to freshwater-acclimated trout, cardiac output was 34% and 55% higher in seawater-acclimated trout at 11 and 17°C, respectively, which allowed them to increase gastrointestinal blood flow significantly more during warming (increases of 75% in seawater vs. 31% in freshwater). These adjustments likely served to mitigate the impact of warming on osmotic balance, as changes in ionic and osmotic blood composition were minor. Furthermore, seawater-acclimated trout seemingly had a lower tissue O2 extraction, explaining why trout acclimated to freshwater and seawater often exhibit similar metabolic rates, despite a higher cardiac output in seawater. Our results highlight a novel role of gastrointestinal blood perfusion in the osmo-respiratory compromise in fish, and improve our understanding of the physiological changes euryhaline fishes must undergo when faced with interacting environmental challenges such as transient warming events.

Orbitally Paced Carbon and Deep‐Sea Temperature Changes at the Peak of the Early Eocene Climatic Optimum

AbstractThe late Paleocene to early Eocene warming trend was punctuated by a series of orbitally paced transient warming events, associated with the release of isotopically light carbon into the ocean‐atmosphere system. These events occurred throughout the early Eocene, critically persisting during onset, peak, and termination of the early Eocene climatic optimum (EECO) and the onset of the middle Eocene cooling. Here we present a ~5.2‐Myr‐long high‐resolution benthic foraminiferal stable‐isotope record spanning the peak of the early Eocene “hothouse” from Ocean Drilling Program Leg 208 Site 1263. Our new oxygen isotope record confirms the presence of short‐term warming events during the peak and termination of the EECO, previously described in coeval bulk carbonate records. The degree of change between deep‐sea temperature and concurrent carbon release during these events is consistent with previous findings for Eocene thermal maximum 2 to 3, suggesting that the orbitally forced processes that triggered these perturbations in the exogenic carbon pool were similar. Additionally, the long‐term background carbon isotope signature reveals a rapid enrichment of up to ~1.0‰ across the peak warmth of the EECO, ~51.6 Ma, without a corresponding shift in the oxygen record, suggesting a decoupling from climate. We speculate that this carbon shift reflects a non‐recurrent adjustment in the mean (steady) state of the deep‐ocean carbon reservoir due to a significant change in carbon source/sink, the biological pump, and/or ocean circulation during the extreme greenhouse conditions of the EECO.

Transient Warming Events in Cord Blood Units and the Impact on Product Quality

Transient Warming Events in Cord Blood Units and the Impact on Product Quality

Functional impairment of MSC induced by transient warming events: Correlation with loss of adhesion and altered cell size

BackgroundWe recently showed that transient warming effects decreased the functional and adhesion properties of mesenchymal stromal cells (MSC) while post-thaw viability remained high. In an attempt to better predict functional impairment of cryopreserved MSC, we further analysed the correlation between viability, immunosuppressive activity and adhesion of cells exposed or not to warming events. MethodsMSC prepared from six umbilical cords were frozen to −130°C and immediately transferred in a dry ice container or exposed to room temperature for 2 to 10 min (warming events) prior to storage in liquid nitrogen. Viability, functionality (inhibition of T-cell proliferation), adhesion and expression of various integrins were evaluated. ResultsThe monotonic loss of functional activity with time was proportional to the length of warming events to which MSC were subjected and correlated with the monotonic loss of adhesion capacity. In contrast, post-thaw viability assessment did not predict functional impairment. Interestingly, flow cytometry analyses revealed the emergence of a FSClow population present in the viable cell fraction of freshly thawed MSC, which displayed poor adhesion capacity and expressed low levels of integrin β5. The prevalence of this FSClow population increased with the length of warming events and correlated with impaired functional and adhesion properties. DiscussionOur results reveal that loss of functional activity (4-day test) induced by transient warming events could be predicted by evaluating adhesion (2-hr test) or FSC profile (10-min test) of MSC immediately post-thaw. These observations could lead to the development of surrogate tests for rapidly assessing the functional quality of cryopreserved MSC.

101 - The effect of cryomedia selection and transient warming events on post-cryopreservation human MSC function

101 - The effect of cryomedia selection and transient warming events on post-cryopreservation human MSC function

A new high-resolution chronology for the late Maastrichtian warming event: Establishing robust temporal links with the onset of Deccan volcanism

The late Maastrichtian warming event was defined by a global temperature increase of ∼2.5–5 °C that occurred ∼150–300 k.y. before the Cretaceous-Paleogene (K-Pg) mass extinction. This transient warming event has traditionally been associated with a major pulse of Deccan Traps (west-central India) volcanism; however, large uncertainties associated with radiogenic dating methods have long hampered a definitive correlation. Here we present a new high-resolution, single species, benthic stable isotope record from the South Atlantic, calibrated to an updated orbitally tuned age model, to provide a revised chronology of the event, which we then correlate to the latest radiogenic dates of the main Deccan Traps eruption phases. Our data reveal that the initiation of deep-sea warming coincides, within uncertainty, with the onset of the main phase of Deccan volcanism, strongly suggesting a causal link. The onset of deep-sea warming is synchronous with a 405 k.y. eccentricity minimum, excluding a control by orbital forcing alone, although amplified carbon cycle sensitivity to orbital precession is evident during the greenhouse warming. A more precise understanding of Deccan-induced climate change paves the way for future work focusing on the fundamental role of these precursor climate shifts in the K-Pg mass extinction.

Tectonic forcing to global cooling and aridification at the Eocene-Oligocene transition in the Iranian plateau

Abstract The transition from the extreme global warmth of the early Eocene ‘greenhouse’ climate to the present glaciated state is one of the most fundamental reorganizations of global climate known in the geologic record. The Middle to Late Eocene interval between 49 and 33 Ma was a globally important transition period from greenhouse to initial icehouse conditions. The Middle Eocene Climatic Optimum (MECO, ~ 40 Ma) was a transient period of global warming that interrupted the secular Cenozoic cooling trend. The Eocene-Oligocene transition (ca. 33.5 Ma) marks the first major decline in Cenozoic global temperatures and the initiation of Antarctic glaciation. However, a major challenge comes from recent investigations of plateau uplift processes and resulting environmental changes. The tectonic evolution of the Iranian plateau offers an explanation for global cooling during the Cenozoic, as a result of the gradual closure of the Neotethyan Sea, which led to the disappearance of the Indian Ocean-Mediterranean Sea connection, mountain building, extensional collapse, rifting, and flare-up type volcanism, erosion, and exhumation. Increasing topography by shortening as a result of subduction of the distal Arabian margin beneath the Iranian Plateau and contemporaneous exhumation of a metamorphic core complex between 49 and 33 Myr ago led to aridification of Iranian plateau and to the some elevation of the plateau. This rise in elevation is roughly contemporaneous with the emplacement of flare-up-type volcanics in the Urumiyeh-Dokhtar zone and over large portions of Central Iran. Peak volcanism occurred during the transient warming event MECO. New findings suggest that this global transition is linked to significant aridification and cooling in southwest Asia, and thus support the idea that global cooling is associated with the Eocene-Oligocene transition. The good match of tectonic deformation and uplift of the Iranian Plateau with climatic changes is significant.

Quality comparison of umbilical cord blood cryopreserved with conventional versus automated systems

Umbilical cord blood (CB) banks usually freeze and store CB for clinical transplantation using conventional controlled-rate freezer or the automated BioArchive system. The aim of this study is to compare the quality of CB cryopreserved with conventional and automated methods and to make clear the cause of the quality difference between the two methods. The experiment used 80 CB units: 40 were conventionally cryopreserved and the remainder were cryopreserved with a BioArchive. After thawing, the following measures of CB quality were compared: recovery rates of cell count, cell viability of total nucleated cells (TNCs), mononuclear cells (MNCs), and CD34+ cells, as well as colony-forming unit-granulocyte/macrophage (CFU-GM) content. Additionally, processing and storage records were reviewed to quantify the number of exposures of CB units at room temperature (transient warming event, TWE), which was analyzed in relation to CB quality. MNC and CD34+ cell viability were as follows: MNC, 78.2% ± 6.8% (conventional), 81.7% ± 7.2% (automated); CD34+ cell, 90.6% ± 6.9% (conventional), 94.7% ± 3.5% (automated). The absolute CFU-GM content per CB unit was 7.1 × 105 ± 5.9 × 105 with conventional cryopreservation and 12.3 × 105 ± 12.0 × 105 with automated cryopreservation. CBs cryopreserved with BioArchive showed significantly higher MNC and CD34+ cell viability, and CFU-GM content than those conventionally cryopreserved. The CB quality comparison depending on the amount of TWEs showed no significant quality difference between groups that were more exposed to TWEs and groups that were less exposed. CBs cryopreserved with BioArchive were of higher quality than conventionally cryopreserved CBs, and the cause of quality difference might be due to the difference of freezing conditions rather than the TWE effect.

Transient warming events occurring after freezing impairs umbilical cord–derived mesenchymal stromal cells functionality

BackgroundMesenchymal stromal cells (MSCs) have shown promising results for the treatment of refractory acute graft-versus-host disease. While safety of MSC infusion has been demonstrated, the use of cryopreserved MSCs in clinical trials has raised concerns regarding the retention of their functional activity. This has led to the recommendation by experts in the field to use freshly harvested MSCs, even though this approach is much less practical from a logistic point of view. In the present study, we revisited the impact of cryopreservation on MSC functionality and addressed the possibility that warming events on frozen cells rather than cryopreservation per se could impact MSC functionality. MethodsFollowing controlled-rate freezing to −130°C, umbilical cord–derived MSCs were left at room temperature (RT) for 2–10 min or on dry ice for 10 min, before being transferred into liquid nitrogen (LqN2). MSCs of each group were subsequently tested (viability, functionality and cellular damage) and compared with their freshly harvested counterparts. ResultsWe demonstrated that freshly harvested MSCs as well as cryopreserved MSCs that were left on dry ice following step-down freezing have comparable viability, functionality and integrity. In contrast, cryopreserved MSCs that were left at RT before being transferred into LqN2 were functionally impaired and showed cellular damage upon thawing even though they exhibited high viability. DiscussionWarming events after freezing and not cryopreservation per se significantly impair MSC functionality, indicating that cryopreserved MSCs can be an advantageous alternative to freshly harvested cells for therapeutic purposes.

LB33 - Transient warming events occurring after freezing impairs umbilical cord-derived mesenchymal stromal cell functionality

Mesenchymal stromal cells (MSC) have shown promising results for the treatment of refractory acute graft-versus-host-disease and are considered for many other therapeutic applications. While safety of MSC infusion has been demonstrated, the use of cryopreserved MSC in clinical trials has raised concerns about the retention of their functional activity. This has led to the recommendation by several experts in the field to use freshly harvested MSC, even though this approach is much less practical from a logistic point of view. In the present study, we revisited the impact of cryopreservation on MSC and addressed the possibility that warming events on frozen cells rather than cryopreservation per se could impair MSC functionality and affect cell integrity. Following controlled-rate freezing to −130°C, umbilical cord-derived MSC were left at room temperature for 2 to 10 minutes (group 1) or on dry ice for 10 minutes (group 2), before being transferred into liquid nitrogen. MSC of each experimental group were subsequently thawed and tested together with their freshly harvested counterpart. We first determined viability by DAPI staining and found a slight (<10%) albeit significant decrease in post-thaw viability of cells from groups 1 and 2 compared to freshly harvested cells. We next determined the ability of MSC to inhibit the proliferation of CD3/CD28 activated T cells as a measure of their immunosuppressive effect. MSC from group 1 had a dramatically reduced immunosuppressive effect (>75%) while MSC from group 2 were as efficient as their freshly harvested counterpart. IFN-γ-induced IDO expression was also impaired in group 1 MSC. Post-thaw cell integrity was evaluated by adhesion to fibronectin-coated dishes, lactate dehydrogenase release and actin filament staining. Group 1 MSC had a reduced ability to bind to fibronectin and exhibited a higher level of lactate dehydrogenase release compared to MSC from group 2. Defects in actin cytoskeleton were observed in thawed MSC from group 1 but not group 2. We thus conclude that warming events after freezing and not cryopreservation per se significantly impair MSC functionality and induce cellular damage upon thawing indicating that properly cryopreserved MSC can be an advantageous alternative to freshly harvested cells for therapeutic purposes.

LB23 - Analysis of transient warming events for gene modified virus specific T cells and hematopoietic progenitor cells manufactured in the center for cell and gene therapy at baylor college of medicine

LB23 - Analysis of transient warming events for gene modified virus specific T cells and hematopoietic progenitor cells manufactured in the center for cell and gene therapy at baylor college of medicine

163 - The effect of common transient warming events on post thaw recovery and functionality of human mesenchymal stem cells stored in LN2 vapour environment

163 - The effect of common transient warming events on post thaw recovery and functionality of human mesenchymal stem cells stored in LN2 vapour environment

Structure and magnitude of the carbon isotope excursion during the Paleocene-Eocene thermal maximum

The Paleocene-Eocene Thermal Maximum (PETM) was a geologically rapid and transient warming event that occurred ca. 56 million years ago (Ma). It was associated with a pronounced negative carbon isotope excursion (CIE) and with profound changes in the atmosphere, hydrosphere and biosphere. This event reflects injections of large amounts of carbon into the atmosphere-ocean system, but, whether single or multiple episodes of carbon release caused this event is uncertain. Here, we present carbon isotope data of bulk carbonate from two parallel limestone sections at Tingri (south Tibet), where the limestone was deposited on a tropical carbonate ramp during the PETM. Carbon isotope data of bulk carbonate from both sections are almost identical, displaying an expanded stepped CIE profile with large magnitude. The stepped CIE profile consists of three discrete intervals of decreasing carbon isotope values, which can be correlated on an inter-regional scale between sections from different depositional environments (lake, carbonate ramp, continental slope, and open ocean). The consistency of these correlations implies occurrence of at least three carbon releases within the CIE and indicates complex processes of carbon injection during the PETM. Moreover, the CIE magnitude of ~7‰ recorded at Tingri is tentatively interpreted to reflect carbon isotope changes in the atmosphere and the surface ocean, which is larger than the generally accepted value of ~4‰ but is still within the range of some previous records.

Rapid Middle Eocene temperature change in western North America

Eocene hyperthermals are among the most enigmatic phenomena of Cenozoic climate dynamics. These hyperthermals represent temperature extremes superimposed on an already warm Eocene climate and dramatically affected the marine and terrestrial biosphere, yet our knowledge of temperature and rainfall in continental interiors is still rather limited. We present stable isotope (δ18O) and clumped isotope temperature (Δ47) records from a middle Eocene (41 to 40 Ma) high-elevation mammal fossil locality in the North American continental interior (Montana, USA). Δ47 paleotemperatures of soil carbonates delineate a rapid +9/−11 °C temperature excursion in the paleosol record. Δ47 temperatures progressively increase from 23 °C ± 3 °C to peak temperatures of 32 °C ± 3 °C and subsequently drop by 11 °C. This hyperthermal event in the middle Eocene is accompanied by low δ18O values and reduced pedogenic carbonate concentrations in paleosols. Based on laser ablation U/Pb geochronology of paleosol carbonates in combination with magnetostratigraphy, biostratigraphy, stable isotope, and Δ47 evidence, we suggest that this pronounced warming event reflects the Middle Eocene Climatic Optimum (MECO) in western North America. The terrestrial expression of northern hemisphere MECO in western North America appears to be characterized by warmer and wetter (sub-humid) conditions, compared to the post-MECO phase. Large and rapid shifts in δ18O values of precipitation and pedogenic CaCO3 contents parallel temperature changes, indicating the profound impact of the MECO on atmospheric circulation and rainfall patterns in the western North American continental interior during this transient warming event.

125 - Off the Shelf Cellular Therapeutics: Factors to Consider During Cryopreservation and Storage of Human Cells for Clinical Use

The field of cellular therapeutics has immense potential, affording an exciting array of applications in unmet medical needs. One of several key issues is an emphasis on getting these therapies from bench to bedside without compromising safety and efficacy. The successful commercialization of cellular therapeutics will require many to extend the shelf-life of these therapies beyond shipping “fresh” at ambient or chilled temperatures for “just in time” infusion. Cryopreservation is an attractive option and offers potential advantages such as storing and retaining patient samples in case of a relapse, banking large quantities of allogeneic cells for broader distribution and use, and retaining testing samples for leukocyte antigen typing and matching. However, cryopreservation is only useful if cells can be reanimated to physiological life with negligible loss of viability and functionality. Also critical is the logistics of storing, processing and transporting cells in clinically appropriate packaging systems and storage devices consistent with Quality and Regulatory standards. Rationalized approaches to develop commercial-scale cell therapies require an efficient cryopreservation system that provides the ability to inventory standardized products with maximized shelf life for later on-demand distribution and use, as well as a method that is scientifically sound and optimized for the cell of interest. The objective of this paper is to bridge this gap between the basic science of cryobiology and its application in this context by identifying several key aspects of cryopreservation science in a format that may be easily integrated into mainstream cell therapy manufacture. Some of the key damage mechanisms and associated factors to consider described above are summarized in Table I. It is important to also consider that in developing a cryopreservation process, variables should be adjusted not just based on total cell recovery and gross viability, but on functional recovery, with the specific product efficacy requirements in mind to define what “functional” means to that specific cellular therapeutic product. If a robust cryopreservation and post-thaw processing system is developed, the product shelf life is essentially indefinite so long as temperature is maintained. Table ISummary of definitions of damage mechanisms and factors to consider associated with a cryopreservation process. Damage Mechanism Description and Factors to Consider Osmotic Injury or Toxic injury Injury due to the addition and removal of cryoprotective agents; cell specific characteristics such as biophysical parameters (size, shape, membrane permeability to water and cryoprotectants, osmotically inactive water, osmotic and volumetric tolerance limits) should be considered. Cold-Shock Injury Injury due to an abrupt change in temperature; cooling rate should be considered, with very slow (<0.5°C/min) cooling rates applied to cold-shock sensitive cells. Chilling Injury Injury due to prolonged exposure to cold (but above cryogenic) temperatures; absolute exposure time is the most critical factor to consider. If cells appear to be chilling sensitive but are tolerant of a cryoprotectant such as DMSO at warmer temperatures, strategies can be employed to perform cryoprotectant additions at or near room temperature and reduce the amount of time “chilled”. Cooling Injury Injury associated with extracellular and intracellular ice formation; factors to consider can be cell-type specific and include cooling rate, ice nucleation regimen, supercooling, end temperature prior to transfer to storage, cellular dehydration, intracellular ice formation, and hypertonic solute toxicity. Storage Injury Injury due to unwanted thermal fluctuations (transient warming events), cosmic rays and free radical formation; factors to consider include the glass transition temperature of the cryoptrotectant and careful maintenance of the storage temperature at all times. Properly cryopreserved and stored cells are viable indefinitely. While practically challenging, if at all possible a sample should never be removed from cryostorage until it is to be used, otherwise temperature of the sample should be monitored throughout any temporary removal (such as removing a rack of vials or frame of bags). Additional considerations should include the use of closed system containers for storage (in vapor or liquid). Thawing injury Injury associated with warming sample from LN2 storage temperature to above phase change temperature; potential recrystallization during warming should be considered. If slow cooling is used, a wide range of warming rates are likely acceptable, however in general faster warming may result in less intracellular recrystallization. Post-cryopreservation Processing Upon thaw, cells are in a potentially compromised state, care must be given to appropriately prepare them for use. If a permeable cryoprotectant is used (such as DMSO), knowledge of cell-specific osmotic characteristics is important. Cells swell and may lyse upon removal of permeable cryoprotectants and may not survive 1-step dilution. If cells are administered directly from thaw without dilution or a washing step, this is effectively a 1-step dilution and may result in significant cell loss in vivo. Open table in a new tab

Cold chain management – Understanding transient warming events and best practices for storage, automation and transport

Cold chain management – Understanding transient warming events and best practices for storage, automation and transport

25. Ice recrystallization inhibitors – Mitigating cellular damage during freezing, transient warming and thawing

Cryopreservation is a common strategy for the preservation of various cells, tissues and biomaterials. Unfortunately, in the absence of a cryoprotective agent (CPA) significant cellular damage occurs. While the use of CPAs such as dimethyl sulfoxide (DMSO) and glycerol mitigate this damage, their toxic nature necessitates removal after thawing and this can adversely affect the functionality and integrity of the recovered cells, tissues or material. During the past decade, our laboratory has studied various classes of naturally occurring biological antifreezes (BAs) found in organisms that inhabit sub-zero environments. BAs control the growth of ice and protect organisms against the cellular damage associated with freezing. Our early work has lead to the development of carbon-linked antifreeze glycoprotein (C-AFGP) analogues that exhibit “custom-tailored” antifreeze activity. In particular, these C-AFGPs are potent inhibitors of ice recrystallization and have been shown to effectively cryopreserve human liver cells in the presence of reduced concentrations of DMSO. Extensive structure-function studies with the C-AFGPs have led to the discovery that small carbohydrate-based molecules (molecular masses 300 AMU) are very effective inhibitors of ice recrystallization at concentrations in the millimolar to sub-millimolar range and that these molecules my have unrealized potential as novel cryoprotectants. Freezing of Human red blood cells (RBCs) requires a cell permeating cryoprotectant to ensure adequate post-thaw recoveries. Typically in North America 40% glycerol is utilized and the sample is frozen slowly, while in many European countries smaller quantities of glycerol are utilized in conjunction with very fast freezing rates. After thawing, the glycerol must be removed prior to transfusion in order to avoid intravascular hemolysis. The automated process of removing the 40% glycerol solution from RBC units can take up to 1 h or more. We have examined a number of small molecule ice recrystallization inhibitors (IRIs) for their ability to freeze human RBCs using only 10–15% glycerol and slow freezing rates. Three IRIs, pBrPhGlc, PMPGlc and 4ClA have proven to be very effective cryoprotectants as evidenced by the amount of post-thaw hemolysis. In addition, some of these molecules are able to protect RBCs from cryoinjury associated with transient warming events (TWEs). This presentation will describe the rational design of small molecule IRIs, assessment of their ability to function as novel cryoprotectants for human RBCs and preliminary investigations into their mechanism of action.

Environmental magnetic implications of magnetofossil occurrence during the Middle Eocene Climatic Optimum (MECO) in pelagic sediments from the equatorial Indian Ocean

Magnetic properties of pelagic marine sediments that record the Middle Eocene Climatic Optimum (MECO) at ~40Ma provide information about major environmental changes. The main variations observed during this transient warming event reflect a bacterial magnetofossil signal, but the cause of the linkage between bacterial production and climate remains unclear. We present an environmental magnetic study of middle Eocene deep-sea sediments from the northern edge of Madingley Rise (Ocean Drilling Program Hole 711A, equatorial Indian Ocean) to investigate the origin of the increased magnetic mineral concentration concomitant with subchron C18n.2n, which corresponds to the MECO interval in ODP Hole 711A. This magnetic mineral peak also coincides with a change in lithofacies from calcareous nannofossils to radiolarian ooze, and a slight increase in clay concentration. Magnetite is the main magnetic mineral in the MECO sediments, which occurs as magnetically non-interacting single domain biogenic particles. The increased magnetic mineral concentration across the MECO event is likely to have been caused by increased eolian iron fertilization. This is interpreted to have given rise to increased surface ocean productivity, where increased delivery of iron and nutrients to the seafloor enhanced magnetotactic bacterial populations during the MECO event.