An immediate increase in the cytosolic free calcium concentration ([Ca2+]cyt) is elicited by cold shock in Arabidopsis. This cold-induced [Ca2+]cyt increase is partially mediated by two calcium-permeable mechanosensitive channels, MCA1 and MCA2 (mid1-complementing activity 1 and 2) that are localized in the plasma membrane. In the mca1 and mca2 mutants, the cold-induced [Ca2+]cyt increase was significantly reduced. Furthermore, The mca1mca2 plants were hypersensitive to cold stress. These results suggest that MCA1 and MCA2 are involved in the cold-induced [Ca2+]cyt increase and the acquisition of tolerance to cold stress.
Embryonic diapause is induced transgenerationally as a maternal effect in the bivoltine strain of the silkworm, Bombyx mori. Progeny diapause is determined by the environmental temperature during embryonic development of the mother. Here, we review the molecular mechanism responsible for diapause induction in Bombyx mori. Recent studies have elucidated the molecular pathway of reception of environmental temperature and neuroendocrine signaling by the diapause hormone. Furthermore, we propose that the environmental adaptation, termed 'in hand', was acquired during the domestication of the silkworm, Bombyx mori from the wild silkworm, Bombyx mandarina.
We investigated the effect of seven ionic liquids (ILs) on the hatching of Artemia salina hydrated cysts upon rapid cooling to －196℃. We found that the effect of an IL on the hatching of Artemia salina strongly depends on the specific combination of cation and anion. Of the ILs tested, choline acetate and choline bromide had an effect of significantly lowering the freezing damage, which may be a new promising way for the protection of freezing damage using choline-based ILs.
We have investigated the effect of applying cryogenic temperature (–196℃) on three amyloid aggregates (human α-synuclein, bovine insulin, and hen egg lysozyme) using Fourier-transform infrared (FTIR) spectroscopy. The peak at ~1620 cm–1 indicating the intermolecular β-sheet structure of lysozyme amyloid structure increases after cooling, and those of the α-synuclein and insulin amyloid structures slightly decrease. These results mean that cryogenic temperature promoted the formation of lysozyme amyloid and led to a slight dissociation of α-synuclein and insulin amyloid. Our results indicate that the cryogenic temperature effect on the amyloid aggregates is small.
Raffinose pentahydrate (R5W) was dehydrated at 30oC under a KOH saturated solution environment to prepare raffinose tetrahydrate (R4W). During the dehydration, the sample was measured by differential scanning calorimeter (DSC) and peak distortion was observed. Thus, an intermediate between R5W and R4W was detected. Even during the water absorption of R4W to R5W, DSC peak distortion was observed, indicating that an intermediate between R5W and R4W was generated. However, the intermediates of the dehydration and water absorption processes were considered to be different hydrates, named R4'W and R5'W, respectively. Moreover, the melting points of the hydrates from R5W to raffinose low hydrate were measured. These results suggest the existence of raffinose hydrate lower than R3W.
Hexagonal and cubic phases have been observed under atmospheric pressure as an ice crystalline phase. No study has reported the preparation of a cubic phase by directly freezing bulk water or by directly cooling the hexagonal phase. We hypothesize that the cubic phase is initially formed upon the crystallization of water and that it subsequently transitions to a hexagonal phase at a momentary rate. When pure water was used, it was not possible to capture the process of transferring to the hexagonal phase through the cubic phase at an integration interval of one second. However, when a 40 wt% aqueous glucose solution was used, it was possible to capture the process of transitioning from the supercooled liquid to the hexagonal phase through the cubic phase with an integration time of one second. This result is considered to indicate that the pure water may be instantaneously transferred from the supercooled liquid through the cubic phase to the hexagonal phase.
In Tokachi area, the coldest wine-grape-growing region in Japan, canes, cordons and trunks of grapevines of 'Kiyomi' cultivar are buried during fall to prevent freezing damage due to insufficient snow cover during the winter months to protect vines. However, this management is extremely labor intensive as it requires burying and unburying the vines in fall and spring, respectively. The objective of this study was to evaluate seasonal changes in bud cold hardiness of Kiyomi during the dormant season (fall-winter) of 2018/2019, and to identify environmental conditions, i.e. timing and ambient temperature, that could cause freezing damage of unprotected grapevines. During the cold acclimation period in the fall, buds gain cold hardiness and by late November bud cold hardiness exceeded −20oC. However, historical daily minimum temperature data for this region has recorded much lower air temperature during early December than what Kiyomi grapevine buds can tolerate. In fact, on 9th December, 2018, the daily minimum temperature reached −22.1oC. Given the bud cold hardiness of Kiyomi, vines should be protected so that they do not experience temperature below −20oC during mid-winter.
Suspension-cultured cells of Oryza sativa, were cryopreserved by the pre-freezing method. Dimethyl sulfoxide (DMSO), which is often used as a cryoprotectant, is cytotoxic. In this study, we examined the effect of carboxylate polylysine (PLL) as a cryoprotectant in replacement of DMSO. It was found that cryopreservation with 5% ethylene glycol and 3.5% PLL resulted in significantly higher survival rates than that with 5% DMSO and 10% glucose. Our results indicate that PLL is effective as a cryoprotectant for cryopreservation of cultured plant cells.
Recently, the glass-forming ability of glycolipids has attracted attention owing to their specific potent applications based on their high glass transition temperature (Tg). In this study, we investigated on the temperature dependence of layer spacing of liquid crystalline (LC) phase made from a 6-O-hexadecanoyl trehalose monoester (TME16) across temperatures straddling Tg. We found that the effect of thermal history disappeared and the longest layer spacing were observed above the Tg of TME16. Thus, several novel insights into the glass transition behavior of glycolipids were shown.