Cold-hardiness in the Antarctic tick, Ixodes uriae.

Ixodes uriae White (Ixodidae, Acarina) is the predominant tick on the Antarctic peninsula.This species has a circumpolar distribution in both hemispheres and is associated with or known to parasitize 48 species of seabirds. Large colonies of 1,000 or more individuals of all life stages were found beneath rocks on the periphery of penguin rookeries near Palmer Station, Anvers Island. All life stages (egg, larva, nymph and adult) were intolerant of freezing. Engorged nymphs and larvae had supercooling points between -18 and -20 C. Eggs had the lowest supercooling points (-28.7 C) white adults had the highest values (from -7 to -13 C). Acclimation to temperatures between -12 and +25 C for 2 weeks had no effect on the supercooling point of engorged immobile nymphs. Desiccation of engorged nymphs to 80% of their initial weight resulted in no change in supercooling points or glycerol levels. In January, engorged nymphs enter a state of apolysis and lose mobility. Correlated with this change is an increase in cold tolerance as evidenced by a decrease in supercooling points from -11.5 to -19.5 C. This species exhibits the greatest range of thermal tolerance, from -30 to 40 C, reported for any Antarctic terrestrial arthropod. Except for a short period associated with feeding, I. uriae remains in a permanent state of cold-hardiness throughout the year

Low temperature acclimation in the desert spider, Agelenopsis aperta.

Agelenopsis aperta (Gertsch) inhabits desert grasslands and lava beds in the southwestern U.S.A. The capacity of this species to cold-harden was assessed by exposing second generation laboratory- reared specimens to an artificial low temperature cycle simulating the "summer-autumn-winter" transition. Low temperature acclimation had no effect on whole body supercooling points, freeze tolerance or rates of oxygen consumption. Elevated levels of cryoprotectants were not detected using high performance liquid chromatographic techniques. Cold tolerance was similar between males, females and immatures. Exposure to temperatures immediately above the whole body supercooling point caused no apparent injury. It is hypothesized that movement into protected overwintering microhabitats may obviate the necessity for the evolution of seasonal mechanisms of cold-hardening in A. aperta

Retrotransposon-Induced Heterochromatin Spreading in the Mouse Revealed by Insertional Polymorphisms

The “arms race” relationship between transposable elements (TEs) and their host has promoted a series of epigenetic silencing mechanisms directed against TEs. Retrotransposons, a class of TEs, are often located in repressed regions and are thought to induce heterochromatin formation and spreading. However, direct evidence for TE–induced local heterochromatin in mammals is surprisingly scarce. To examine this phenomenon, we chose two mouse embryonic stem (ES) cell lines that possess insertionally polymorphic retrotransposons (IAP, ETn/MusD, and LINE elements) at specific loci in one cell line but not the other. Employing ChIP-seq data for these cell lines, we show that IAP elements robustly induce H3K9me3 and H4K20me3 marks in flanking genomic DNA. In contrast, such heterochromatin is not induced by LINE copies and only by a minority of polymorphic ETn/MusD copies. DNA methylation is independent of the presence of IAP copies, since it is present in flanking regions of both full and empty sites. Finally, such spreading into genes appears to be rare, since the transcriptional start sites of very few genes are less than one Kb from an IAP. However, the B3galtl gene is subject to transcriptional silencing via IAP-induced heterochromatin. Hence, although rare, IAP-induced local heterochromatin spreading into nearby genes may influence expression and, in turn, host fitness

Preliminary studies on the isolation of pterins from the wings of Heliconiid butterflies

Volume: 52Start Page: 15End Page: 2

Assessment of the Impact of Post-Thaw Stress Pathway Modulation on Cell Recovery following Cryopreservation in a Hematopoietic Progenitor Cell Model

The development and use of complex cell-based products in clinical and discovery science continues to grow at an unprecedented pace. To this end, cryopreservation plays a critical role, serving as an enabling process, providing on-demand access to biological material, facilitating large scale production, storage, and distribution of living materials. Despite serving a critical role and substantial improvements over the last several decades, cryopreservation often remains a bottleneck impacting numerous areas including cell therapy, tissue engineering, and tissue banking. Studies have illustrated the impact and benefit of controlling cryopreservation-induced delayed-onset cell death (CIDOCD) through various “front end” strategies, such as specialized media, new cryoprotective agents, and molecular control during cryopreservation. While proving highly successful, a substantial level of cell death and loss of cell function remains associated with cryopreservation. Recently, we focused on developing technologies (RevitalICE™) designed to reduce the impact of CIDOCD through buffering the cell stress response during the post-thaw recovery phase in an effort to improve the recovery of previously cryopreserved samples. In this study, we investigated the impact of modulating apoptotic caspase activation, oxidative stress, unfolded protein response, and free radical damage in the initial 24 h post-thaw on overall cell survival. Human hematopoietic progenitor cells in vitro cryopreserved in both traditional extracellular-type and intracellular-type cryopreservation freeze media were utilized as a model cell system to assess impact on survival. Our findings demonstrated that through the modulation of several of these pathways, improvements in cell recovery were obtained, regardless of the freeze media and dimethyl sulfoxide concentration utilized. Specifically, through the use of oxidative stress inhibitors, an average increase of 20% in overall viability was observed. Furthermore, the results demonstrated that by using the post-thaw recovery reagent on samples cryopreserved in intracellular-type media (Unisol™), improvements in overall cell survival approaching 80% of non-frozen controls were attained. While improvements in overall survival were obtained, an assessment on the impact of specific cell subpopulations and functionality remains to be completed. While work remains, these results represent an important step forward in the development of improved cryopreservation processes for use in discovery science, and commercial and clinical settings

Characterization of canine mastocytoma cell response to cryoablation

Introduction: Mastocytoma Tumors (MCT) represent 16%-21% of all skin cancers in dogs, making it the most common form of cutaneous cancer. Solitary MCT are typically treated with wide surgical excision margins. While effective, MCT excision can cause the release of a large amount of histamine and other cytokines resulting in complications such as systemic shock or anaphylaxis. Treatments such as chemotherapy and radiotherapy have been considered to achieve complete remission. Cryoablation also represents a potential treatment option for MCT. While studies have shown cryoablation to be beneficial for the treatment of numerous cancers in animals and humans, few studies have described the use of cryoablation to treat MCT’s. The limited use of cryoablation is due to a number of factors including a lack of basic information pertaining to dosing (minimal lethal temperature) necessary to destroy MCT cancer. As such, in this study we conducted a series of in vitro studies using the C2 cell line and a pilot ex vivo fine needle aspirate tissue sample in an effort to detail the effects of freezing of canine MCT.&nbsp;Methods: Samples were exposed to temperatures ranging from -5°C to -25°C, modeling the periphery of a cryogenic lesion for 3, 5 and 10minutes, and various markers of viability and modes of cell death were assessed daily over a 3 days recovery period. Additionally, investigation of the involvement of apoptosis in MCT cell death flowing freezing was conducted via immunoblotting and caspase inhibition studies.&nbsp;Results: Viability studies revealed the -25°C isotherm as the critical minimal lethal temperature to achieve complete MCT cell death regardless of hold time. As the hold time at temperatures of -15°C and -20°C increased from 3 to 10minutes the level of cell death was also found to increase. Fluorescence microscopy, caspase inhibition and protein analysis revealed necrosis to be the primary mode of cell death following freezing. These studies, however, also revealed a significant level of apoptotic cell death post-freeze. Molecular analysis suggested that freezing to -15°C to -20°C resulted in the activation of mitochondrial mediated apoptosis 4 to 8 hours post freeze.&nbsp;Conclusions: In summary, this in vitro study was designed as a first step investigation into the sensitivity of MCT cancer to freezing. These in vitro results suggest that freezing to temperatures of ≤-20°C results in a high degree of MCT cell destruction. Further the data suggest that both apoptosis and necrosis play an important role in cell death following cryoablation. These data may have translational application to MCT treatment in vivo.</p

Low Temperature Acclimation in the Desert Spider, Agelenopsis aperta (Araneae, Agelenidae)

Volume: 13Start Page: 129End Page: 13