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1.
M. Holmstrup L. Sømme 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(3):197-203
Specimens of the Arctic Collembolon Onychiurus arcticus were exposed to desiccation at several subzero temperatures over ice and at 0.5 °C over NaCl solutions. The effects of desiccation
on water content (WC), body fluid melting point (MP), supercooling point (SCP) and survival were studied at several acclimation
temperatures and relative humidities. Exposure to temperatures down to −19.5 °C caused a substantial and increasing dehydration.
At the lowest exposure temperature unfrozen individuals lost 91.6% of the WC at full hydration but more than 80% of the individuals
survived when rehydrated. Exposure at 0.5 °C to decreasing relative humidities (RH) from 100% to 91.3% caused increasing dehydration
and increasing mortality. Survival of equally dehydrated individuals was higher at subzero temperatures than at 0.5 °C. Concurrent
with the decline in WC a lowering of the MP was observed. Animals exposed to −3 °C and −6 °C over ice for 31 days had a MP
of −3.8 and < −7.5 °C, respectively. Specimens from a laboratory culture had a mean SCP of −6.1 °C, and acclimation at 0 or
−3 °C had little effect on SCPs. Exposure at −8.2 °C over ice for 8 days, however, caused the mean SCP to decline to −21.8 °C
due to the severe dehydration of these individuals. Dehydration at 0.5 °C in 95.1 and 93.3% RH also caused a decline in SCPs
to about −18 °C. Individuals that had been acclimated over ice at −12.4 °C or at lower temperatures apparently did not freeze
at all when cooled to −30 °C, probably because all freezeable water had been lost. These results show that O. arcticus will inevitably undergo dehydration when exposed to subzero temperatures in its natural frozen habitat. Consequently, the
MP and SCP of the Collembola are substantially lowered and in this way freezing is avoided. The increased cold hardiness by
dehydration is similar to the protective dehydration mechanism described in earthworm cocoons and Arctic enchytraeids.
Accepted: 5 January 1998 相似文献
2.
Cold tolerance and dehydration in Enchytraeidae from Svalbard 总被引:4,自引:1,他引:3
L. Sømme T. Birkemoe 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(4):264-269
When cooled in contact with moisture, eight species of arctic Enchytraeidae from Svalbard were killed by freezing within
minutes or hours at −3 and −5 °C; an exception was Enchytraeus kincaidi which survived for up to 2 days. When the temperature approached 0 °C the enchytraeids apparently tried to escape from the
moist soil. The supercooling capacity of the enchytraeids was relatively low, with mean supercooling points of −5 to −8 °C.
In contrast, specimens of several species were extracted from soil cores that had been frozen in their intact state at −15 °C
for up to 71 days. Compared to freezing in a moist environment, higher survival rates were obtained during cooling at freezing
temperatures in dry soil. Survival was recorded in species kept at −3 °C for up to 35 days, and in some species kept at −6 °C
for up to 17 days. Slow warming greatly increased survival rates at −6 °C . The results strongly suggest that arctic enchytraeids
avoid freezing by dehydration at subzero temperatures. In agreement with this, weight losses of up to ca. 42% of fresh weight
were recorded in Mesenchytraeus spp. and of up to 55% in Enchytraeus kincaidi at water vapour pressures above ice at −3 to −6 °C. All specimens survived dehydration under these conditions.
Accepted: 12 December 1997 相似文献
3.
Tamotsu Hoshino Fumihiro Terami Oleg B. Tkachenko Motoaki Tojo Naoyuki Matsumoto 《Mycoscience》2010,51(2):98-103
The snow mold fungus, Sclerotinia borealis, shows optimal growth at 4°C on potato dextrose agar (PDA) and can grow even at subzero temperature. Its mycelial growth
was improved on frozen PDA at −1°C and on PDA containing potassium chloride (KCl) (water potential, −4.27 to −0.85 MPa) or
d(−) sorbitol (−3.48 to −0.92 MPa). Its optimal growth temperature shifted from 4 to 10°C on PDA amended with KCl or sorbitol,
indicating that inherent optimal growth occurs at high temperatures. These results suggest that S. borealis uses concentrated nutrients in the frozen environment and that such physiologic characteristics are critical for the fungus
to prevail at subzero temperatures. 相似文献
4.
Bakermans C Tollaksen SL Giometti CS Wilkerson C Tiedje JM Thomashow MF 《Extremophiles : life under extreme conditions》2007,11(2):343-354
It is crucial to examine the physiological processes of psychrophiles at temperatures below 4°C, particularly to facilitate
extrapolation of laboratory results to in situ activity. Using two dimensional electrophoresis, we examined patterns of protein
abundance during growth at 16, 4, and −4°C of the eurypsychrophile Psychrobacter cryohalolentis K5 and report the first identification of cold inducible proteins (CIPs) present during growth at subzero temperatures. Growth
temperature substantially reprogrammed the proteome; the relative abundance of 303 of the 618 protein spots detected (∼31%
of the proteins at each growth temperature) varied significantly with temperature. Five CIPs were detected specifically at
−4°C; their identities (AtpF, EF-Ts, TolC, Pcryo_1988, and FecA) suggested specific stress on energy production, protein synthesis,
and transport during growth at subzero temperatures. The need for continual relief of low-temperature stress on these cellular
processes was confirmed via identification of 22 additional CIPs whose abundance increased during growth at −4°C (relative
to higher temperatures). Our data suggested that iron may be limiting during growth at subzero temperatures and that a cold-adapted
allele was employed at −4°C for transport of iron. In summary, these data suggest that low-temperature stresses continue to
intensify as growth temperatures decrease to −4°C. 相似文献
5.
Maturation to adulthood and successful reproduction in the Antarctic fairy shrimp, Branchinecta
gaini, must be completed within a physiologically challenging temporal window of ca. 2.5 months in the southern Antarctic Peninsula.
Although adults show considerable metabolic opportunism at positive temperatures, little is known of their tolerance of two
physiological insults potentially typical to pool life in the maritime Antarctic: sub-zero temperatures and salinity. B. gaini are freeze-avoiding crustaceans with temperatures of crystallisation (T
cs) of −5°C. No antifreeze proteins were detected in the haemolymph. Adults osmoregulate in relation to temperature, but rapid
mortality in saline solutions of even low concentration, indicate they cannot osmoregulate in relation to salinity. Survival
of ice encasement at temperatures above their T
c was found to be pressure but not time dependent: at severe inoculative ice pressures, there was little immediate survival
and none survived after 48 h below −2°C; at mild inoculative ice pressures, immediate survival was ca. 100% at −3°C, but <20%
after 48 h. There was no significant difference in survival after 1 and 6 h encasement at −3°C. Observations of ventilation
suggest that it is not low temperature per se, but ice that represents the primary cryo-stress, with ventilatory appendages
physically handcuffed below the freezing point of pool water. Both sub-zero temperatures and salinity represent real physiological
constraints on adult fairy shrimp. 相似文献
6.
Lay CY Mykytczuk NC Niederberger TD Martineau C Greer CW Whyte LG 《Extremophiles : life under extreme conditions》2012,16(2):177-191
Lost Hammer (LH) spring is a unique hypersaline, subzero, perennial high Arctic spring arising through thick permafrost. In
the present study, the microbial and geochemical characteristics of the LH outflow channels, which remain unfrozen at ≥−18°C
and are more aerobic/less reducing than the spring source were examined and compared to the previously characterized spring
source environment. LH channel sediments contained greater microbial biomass (~100-fold) and greater microbial diversity reflected
by the 16S rRNA clone libraries. Phylotypes related to methanogenesis, methanotrophy, sulfur reduction and oxidation were
detected in the bacterial clone libraries while the archaeal community was dominated by phylotypes most closely related to
THE ammonia-oxidizing Thaumarchaeota. The cumulative percent recovery of 14C-acetate mineralization in channel sediment microcosms exceeded ~30% and ~10% at 5 and −5°C, respectively, but sharply decreased
at −10°C (≤1%). Most bacterial isolates (Marinobacter, Planococcus, and Nesterenkonia spp.) were psychrotrophic, halotolerant, and capable of growth at −5°C. Overall, the hypersaline, subzero LH spring channel
has higher microbial diversity and activity than the source, and supports a variety of niches reflecting the more dynamic
and heterogeneous channel environment. 相似文献
7.
《Cryobiology》2020
Cell preservation is an enabling technology for widespread distribution and applications of mammalian cells. Traditional cryopreservation via slow-freezing or vitrification provides long-term storage but requires cytotoxic cryoprotectants (CPA) and tedious CPA loading/unloading, cooling, and recovering procedures. Hypothermic storage around 0–4 °C is an alternative method but only works for a short period due to its high storage temperatures. Here, we report on the deep-supercooling (DSC) preservation of human adipose-derived stem cells at deep subzero temperatures without freezing for extended storage. Enabled by surface sealing with an immiscible oil phase, cell suspension can be preserved in a liquid state at −13 °C and −16 °C for 7 days with high cell viability, retention of stemness, attachment, and multilineage differentiation capacities. These results demonstrate that DSC is an improved short-term preservation approach to provide off-the-shelf cell sources for booming cell-based medicine and bioengineering. 相似文献
8.
《Cryobiology》2016,72(3):384-390
Cryopreservation is a technique that has been extensively used for storage of multipotent mesenchymal stromal cells (MSCs) in regenerative medicine. Therefore, improving current cryopreservation procedures in terms of increasing cell viability and functionality is important. In this study, we optimized the cryopreservation protocol of MSCs derived from the common marmoset Callithrix jacchus (cj), which can be used as a non-human primate model in various pathological and transplantation studies and have a great potential for regenerative medicine. We have investigated the effect of the active control of the nucleation temperature using induced nucleation at a broad range of temperatures and two different dimethylsulfoxide concentrations (Me2SO, 5% (v/v) and 10%, (v/v)) to evaluate the overall effect on the viability, metabolic activity and recovery of cells after thawing. Survival rate and metabolic activity displayed an optimum when ice formation was induced at −10 °C. Cryomicroscopy studies indicated differences in ice crystal morphologies as well as differences in intracellular ice formation with different nucleation temperatures. High subzero nucleation temperatures resulted in larger extracellular ice crystals and cellular dehydration, whereas low subzero nucleation temperatures resulted in smaller ice crystals and intracellular ice formation. 相似文献
9.
Freezing resistance mechanisms were studied in five endemic Hawaiian species growing at high elevations on Haleakala volcano, Hawaii, where nocturnal subzero (°C) air temperatures frequently occur. Extracellular freezing occurred at around -5°C in leaves of Argyroxiphium sandwicense and Sophora chrysophylla, but these leaves can tolerate extracellular ice accumulation to -15°C and -12°C, respectively. Mucilage, which apparently acted as an ice nucleator, comprised 9 to 11% of the dry weight of leaf tissue in these two species. Leaves of Vaccinium reticulatum and Styphelia tameiameiae were also found to tolerate substantial extracellular freezing. Dubautia menziesii, on the other hand, exhibited the characteristics of permanent supercooling; a very rapid decline in liquid water content associated with simultaneous intracellular and extracellular freezing. However, in those species that tolerate extracellular freezing, the decline in liquid water content during freezing is relatively slow. Osmotic potential was lower at pre-dawn than at midday in four of the species studied. Nocturnal production of osmotically active solutes may have helped to prevent intracellular freeze dehydration as well as to provide non-colligative protection of cell membranes. Styphelia tameiameiae supercooled to -9·3°C and tolerated tissue freezing to below -15°C, a unique combination of physiological characteristics related to freezing. Tolerance of extracellular ice formation after considerable supercooling may have resulted from low tissue water content and a high degree of intracellular water binding in this species, as determined by nuclear magnetic resonance studies. The climate at high elevations in Hawaii is relatively unpredictable in terms of the duration of subzero temperatures and the lowest subzero temperature reached during the night. It appears that plants growing in this tropical alpine habitat have been under selective pressures for the evolution of freezing tolerance mechanisms. 相似文献
10.
Two temperate mushroom cultures namely Agaricus bisporus (U-3) and Pleurotus florida (PAU-5) were evaluated for their physiological (linear growth and biomass production), biochemical (β-1,4 endoglucanase production)
and fruiting behaviour after preservation in 10% (v/v) glycerol and storage at room temperature (25–35°C), −20°C and −196°C
for 6 months with the objective of establishing the recovery/changes in these fungi after storage. Studies indicated that
the viability and recovery of A. bisporus and P. florida is affected by the storage conditions. Both the fungi could be best stored in liquid nitrogen for longer durations but for
regular use, conventional sub-culturing was appropriate. 相似文献
11.
Abstract-Four species of slugs have been identified in the vicinity of Magadan: Deroceras laeve, D. altaicum, D. reticulatum, and D. agreste. They exemplify three different life cycle schemes, with D. reticulatum and D. altaicum wintering at the egg phase; D. laeve, at the slug phase; and D. agreste, at either phase. The D. altaicum and D. reticulatum slugs and D. laeve eggs are intolerant of subzero temperatures. D. laeve’s tolerate freezing and survive at temperatures below −28°C. The eggs of other species, which lose up to 35% of water upon
cooling, can withstand temperatures as low as −15 to −17°C (D. altaicum), −25°C (D. agreste), and −35°C (D. reticulatum). According to preliminary data, D. agreste slugs survive at temperatures down to −10°C. The almost ubiquitous distribution of D. laeve in regions with cool summers (including zonal tundras) is accounted for not so much by the high rate of ontogeny as by its
significant cold hardiness and ability to winter at different phases of the life cycle (except for the egg phase), which allows
the period of development to be prolonged for the next seasons. The last is confirmed by the fact that the slugs collected
before and after hibernation proved to have identical patterns of distribution by body weight. Three species of slugs introduced
in the vicinity of Magadan fail to spread inland. In the case of D. reticulatum, this is explained primarily by the fact that the frost-free season in inland areas is too short to allow these slugs to
complete ontogeny and lay eggs. The barriers to their expansion appear to be insuperable, since this process remains unsuccessful
over no less than 75–80 years. 相似文献
12.
Evaluating chondrocytes in situ to document the effectiveness of cartilage preservation techniques has proven exceedingly
difficult. This study was conducted to determine the effectiveness of WST-1 on porcine chondrocytes in situ after cooling
to −10°C (without ice formation) compared to membrane integrity stains (MIS). Osteochondral dowels (10 mm in diameter) were
harvested from sexually mature pigs within 24 h of sacrifice and randomized into three groups: (1) untreated control, (2)
one day storage at −10°C (in cryoprotectant solution to prevent ice formation), and (3) seven day storage at −10°C (in cryoprotectant
solution). Fluorescent MISs (Syto 13 and ethidium bromide) were used on 70 μm slices. Representative images were digitized
and green and red pixel numbers determined the percent recovery of intact cells. Mitochondrial activity (WST-1) was determined
using 20 slices of 70 μm thickness per sample to obtain reliable readings using a spectrophotometer at 450 nm. All samples
underwent repeated measures of membrane integrity and metabolic activity obtained after 0, 3, 24, 48, 72, and 144 h incubation
in growth media. WST-1 consistently overestimated cell recovery with results greater than fresh controls. After hypothermic
storage for 7 days, the WST-1 measurement demonstrated decreased mitochondrial activity that recovered by 48 h. MIS was most
accurate when “absolute” cell recovery was compared to original controls, taking into account cell density. In conclusion,
WST-1 can track metabolic activity of chondrocytes in situ over time but “absolute” cell recovery determined by MISs after
48 h incubation may be the most accurate determination of the number of live chondrocytes in situ. 相似文献
13.
Photoinhibition of photosynthesis at low temperatures was investigated in two species of subalpine eucalypt, Eucalypts nitens (Deane and Maiden) Maiden and E. pauciflora Sieb. ex Spreng. Imposition of an artificial cold-hardening treatment increased the frost tolerance of leaf tissue and increased
tolerance to excess light. Cold-hardened seedlings of both species had a higher photosynthetic capacity than non-hardened
seedlings at 6 and 16°C and lower levels of non-photochemical quenching (NPQ) at 20 and 5°C. Furthermore, hardened seedlings
had faster rates of NPQ development at 5 and −3.5°C. An increase in minimal fluorescence, which indicates slowly reversible
photoinhibition, was evident in all seedlings at −1.5 and −3.5°C but was less pronounced in hardened seedlings, with a threefold
faster rate of development of NPQ, at −3.5°C than non-hardened seedlings. Hardened seedlings also recovered faster from photoinhibition
at −3.5°C. Thus cold hardening increased tolerance to high light in these species. Differences between E. nitens and E. pauciflora in their response to excess light were small and significant only at −3.5°C. Faster recovery from photoinhibition of E. pauciflora was consistent with its occurrence in colder habitats than E. nitens.
Received: 27 April 1997 / Accepted: 9 September 1997 相似文献
14.
G. Rapatz 《Cryobiology》1973,10(2):181-184
It has been shown that frog hearts, perfused with gradually increasing concentrations of ethylene glycol (to 11 m) as the temperature was gradually lowered to ?55 °C and then cooled abruptly to ?78 °C, resumed spontaneous contractions when rewarmed. The thin-walled sinus venosus and atria showed significantly better recovery than the thick-walled ventricle. It was suggested that the difference in recovery of the various parts of the heart might be related to the degree of penetration of the glycol into the tissue. In an attempt to achieve better penetration during perfusion, in particular at subzero temperatures, methanol was substituted for glycol in the perfusate. Hearts equilibrated at room temperature in nontoxic concentrations of methanol were perfused with gradually increasing concentrations as the specimen was gradually cooled to various temperatures. The hearts were gradually rewarmed, and during the rewarming the concentrations of methanol in the perfusate was gradually reduced. All hearts resumed spontaneous rhythmic contractions providing they were not cooled to below ?30 °C or perfused with methanol solutions exceeding 10 m concentration. Cooling to lower temperatures and exposure to higher concentrations of methanol did not permit recovery. These results show that at temperatures as low as ?30 °C methanol in concentrations up to 10 m is comparable to ethylene glycol in its ability to protect hearts from cryoinjury. Its failure to protect at lower temperatures may be related to the development of toxic concentrations when water is removed in the form of ice. 相似文献
15.
N. Čeřovská H. Hoffmeisterová T. Moravec H. Plchová J. Folwarczna R. Hadámková 《Biologia Plantarum》2008,52(1):184-186
We describe the optimized storage conditions of recombinant Potato virus A coat protein (ACP) carrying two different epitopes from Human papillomavirus type 16 (HPV-16). Epitope derived from minor capsid protein L2 was expressed as N-terminal fusion with ACP while an epitope
derived from E7 oncoprotein was fused to its C-termini. The construct was cloned into Potato X potexvirus (PVX) based vector and transiently expressed in plants using Agrobacterium tumefaciens mediated inoculation. The effect of storage conditions on the serological activity of L2ACPE7 was studied by ELISA using
IgG anti PVX, PVA and L2. Purified L2ACPE7 stored freeze-dried (at −20 °C), frozen at various temperatures (−20 °C, −70 °C)
and at +4 °C were tested. Purified L2ACPE7 was most stable as lyophilized material stored at −20 °C. Our study demonstrates
suitable way for the storage of plant material containing foreign viral epitopes for the purposes of edible vaccination. 相似文献
16.
Hartley LM Packard MJ Packard GC 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(1):45-50
Hatchlings of the North American painted turtle (Chrysemys picta) typically spend their first winter of life inside the shallow, subterranean nest where they completed embryogenesis the
preceding summer. Neonates at northern localities consequently may be exposed during winter to subzero temperatures and frozen
soil. Hatchlings apparently survive exposure to such conditions by supercooling, but the physiological consequences of this
adaptive strategy have not been examined. We measured lactate in hatchling painted turtles after exposure to each of three
temperatures (0 °C, −4 °C, and −8 °C) for three time periods (5 days, 15 days, and 25 days) to determine the extent to which
overwintering hatchlings might rely on anaerobic metabolism to regenerate ATP. Whole-body lactate increased with increasing
duration of exposure and decreasing temperature, and the highest levels were associated with the group that experienced the
highest mortality. These results indicate that animals may develop a considerable lactic acidosis during a winter in which
temperatures fall below 0 °C for weeks or months and that accumulation of lactate may contribute to mortality of overwintering
animals.
Accepted: 20 October 1999 相似文献
17.
In the autumn of 2007, marine mucilage caused by the diatom Coscinodiscus granii occurred in the central area of Ariake Sound, Japan, and resulted in damage to fishery. To elucidate the mechanism underlying
the outbreak of marine mucilage, we examined the effect of temperature on cell growth and production of transparent exopolymer
particles (TEPs) in a culture of this species. Growth and TEP production of C. granii are influenced by temperature. The maximum growth rate (1.63 divisions day−1) and cell yield (1,280 cells mL−1) at all temperatures were obtained at 30°C. Optimal growth rates (>1.15 divisions day−1: ca. 70% of maximum) and cell yield (>900 cells mL−1: ca. 70% of maximum) were observed at temperatures of 25–30°C. TEP production by C. granii depended on whether volume- or cell-related values were considered. The maximum volume-normalized increase rates and concentrations
of TEP at all temperatures were observed at 25°C. However, when production rates and concentrations of TEP were normalized
to cell numbers, optimal values were measured at 10–15°C. In Ariake Sound, when marine mucilage caused by C. granii occurred, the temperature ranged from 25.0 to 25.4°C. This suggests that growth conditions of C. granii are important factors for production of marine mucilage. 相似文献
18.
Michael J. Price Ian G. Campbell 《European journal of applied physiology and occupational physiology》1997,76(6):552-560
The thermoregulatory responses of ten paraplegic (PA; T3/4-L4) and nine able-bodied (AB) upper body trained athletes were
examined at rest and during prolonged arm-cranking exercise and passive recovery. Exercise was performed for 90 min at 80%
peak heart rate, and at 21.5 (1.7)°C and 47.0 (7.8)% relative humidity on a Monark cycle ergometer (Ergomedic 814E) adapted
for arm exercise. Mean peak oxygen uptake values for the PA and AB athlete groups were 2.12 (0.41) min−1 and 3.19 (0.38) l · min−1, respectively (P<0.05). At rest, there was no difference in aural temperature between groups [36.2 (0.4)°C for both groups]. However, upper
body skin temperatures for the PA athletes were approximately 1.0 °C warmer than for the AB athletes, whereas lower body skin
temperatures were cooler than those for the AB athletes (1.3 °C and 2.7 °C for the thigh and calf, respectively). Upper and
lower body skin temperatures for the AB athletes were similar. During exercise, blood lactate peaked after 15 min of exercise
for both groups [3.33 (1.26) mmol · l−1 and 4.30 (1.03) mmol · l−1 for the PA and AB athletes, respectively, P<0.05] and decreased throughout the remainder of the exercise period. Aural temperature increased by 0.7 (0.5)°C and 0.6 (0.4)°C
for the AB and PA athletes, respectively. Calf skin temperature for the PA athletes increased during exercise by 1.4 (2.8)°C
(P<0.05), whereas a decrease of 0.8 (2.0)°C (P<0.05) was observed for the AB athletes. During the first 20 min of recovery from exercise, the calf skin temperature of the
AB athletes decreased further [−2.6 (1.3)°C; P<0.05]. Weight losses and changes in plasma volume were similar for both groups [0.7 (0.5) kg and 0.7 (0.4) kg; 5.4 (4.9)%
and 9.7 (6.2)% for the PA and AB athletes, respectively]. In conclusion, the results of this study suggest that the PA athletes
exhibit different thermoregulatory responses at rest and during exercise and passive recovery to those of upper body trained
AB athletes. Despite this, during 90 min of arm-crank exercise in a cool environment, the PA athletes appeared to be at no
greater thermal risk than the AB athletes.
Accepted: 7 May 1997 相似文献
19.
Cryoprotective and osmotic responses to cold acclimation and freezing in freeze-tolerant and freeze-intolerant earthworms 总被引:3,自引:3,他引:0
M. Holmstrup J. P. Costanzo R. E. Lee Jr 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(3):207-214
In this paper we present the results of physiological responses to winter acclimation and tissue freezing in a freeze-tolerant
Siberian earthworm, Eisenia nordenskioeldi, and two freeze-intolerant, temperate earthworm species, Lumbricus rubellus and Aporrectodea caliginosa. By analysing the physiological responses to freezing of both types we sought to identify some key factors promoting freeze
tolerance in earthworms. Winter acclimation was followed by a significant increase in osmolality of body fluids in E. nordenskioeldi, from 197 mosmol kg−1 in 10 °C-acclimated animals to 365 mosmol kg−1 in animals acclimated to 0 °C. Cold acclimation did not cause any change in body fluid osmolality in the two freeze-intolerant
species. As a response to ice formation in the body, the freeze-intolerant species produced copious amounts of slime and expulsion
of coelomic fluids, and thereby lost 10–30% of their total water content. Contrary to this, the freeze-tolerant species did
not lose water upon freezing. At temperatures down to −6.5 °C, the ice content in the freeze-tolerant E. nordenskioeldi was significantly lower than in L. rubellus. At lower temperatures there were no differences in ice content between the two species. Cold acclimated, but unfrozen, specimens
of all three species had low levels of ammonia, urea, lactate, glycerol and glucose. As a response to ice formation, glucose
levels significantly increased within the first 24 h of freezing. This was most pronounced in E. nordenskioeldi where a 153-fold increase of glucose was seen (94 mmol · l−1). In L. rubellus and A. caliginosa a 19-fold and 17-fold increase in glucose was seen. This is the first study on physiological mechanisms promoting freeze
tolerance in E. nordenskioeldi, or any other oligochaete. Our results suggest that the cryoprotective system of this species more closely resembles that
of freeze-tolerant anurans, which synthesize cryoprotectants only after tissues begin to freeze, than that of cold-hardy invertebrates
which exhibit a preparatory accumulation of cryoprotectants during seasonal exposure to low temperature.
Accepted: 10 February 1999 相似文献
20.
K. Škrlep M. Bergant G. M. De Winter B. Bohanec J. Žel R. Verpoorte F. Van Iren M. Camloh 《Biologia Plantarum》2008,52(2):329-333
Different lines of cell suspension cultures of Taxus × media Rehd. and Taxus floridana Nutt. were cryopreserved with a two-step freezing method using a simple and inexpensive freezing container instead of a programmable
freezer. Four to seven days old suspension cell cultures were precultured in growth medium supplemented with 0.5 M mannitol
for 2 d. The medium was then replaced with cryoprotectant solution (1 M sucrose, 0.5 M glycerol and 0.5 M dimethylsulfoxide)
and the cells incubated on ice for 1 h. Before being plunged into liquid nitrogen, cells were frozen with a cooling rate of
approximately −1 °C per min to −80 °C. The highest post-thaw cell viability was 90 %. The recovery was line dependent. The
cryopreservation procedure did not alter the nuclear DNA content of the cell lines. The results indicate that cryopreservation
of Taxus cell suspension cultures using inexpensive freezing container is possible. 相似文献