Antifreeze Levels Research Articles

Antifreeze Evaluation of Two Dehydrin Proteins from Pseudotsuga menziesii and Larix principis-rupprechtii Mayr

Dehydrins exist widely in plants and play an important role in abiotic stress resistance. Two low-temperature-induced dehydrin-like genes, PmCAP and LpCAP, from the pine species Pseudotsuga menziesii and Larix principis-rupprechtii Mayr were cloned and found to contain 576 bp and 687 bp, encoding 191 and 228 amino acids, respectively. Both genes were individually assembled into prokaryotic expression vectors and transferred into E. coli cells. When transgenic stains were cultured at −5 °C, the lethal time 50% (LT50) was 50 h and 54 h for PmCAP and LpCAP, respectively, compared with 32 h for the control. When cultured at −20 °C, the LT50 was 38 h, 41 h, and 25 h for PmCAP, LpCAP, and the control. Thermal hysteresis (TH) testing of PmCAP and LpCAP proteins revealed TH values of 0.27 °C and 0.72 °C, respectively, relative to 0.05 °C for the BSA control. These results indicate that the two pine dehydrin proteins have antifreeze characteristics and that their antifreeze levels were well in relation to the environmental conditions of pine growth (Larix principis-rupprechtii Mayr mostly grows in cold and high-altitude zones, while Pseudotsuga menziesii grows in temperate and low-altitude zones). LpCAP, especially, could be a better gene resource for the molecular breeding of plant cold resistance.

Experimental Study on Frost-Resistance Property of Waste Rubber Aggregate Concrete

The experimental using quick frozen method to study the frost-resistance property of waste rubber concrete. Sand was replaced by waste rubber at equal volume substitution ratio divided into 5%, 10%, 15% and 20%; and rubber particle diameter is divided into 2-4mm, 60-80 mesh and 30-40 mesh. The test results show that: the frost-resistance property of waste rubber concrete could meet the specification of design requirements, the antifreeze level is higher than the matrix concrete, and the frost-resistance property improve with the reduce of rubber particle size, the best substitution ratio of rubber aggregate is about 10%.

Frost Resistance of Low Antifreeze Design Level Hydraulic Concrete

Frost resistance of low antifreeze design level hydraulic concrete was studied with Climate Simulation System. Three temperature of -17°C, -20°C, -30°C were chosen as the inner low temperature of concrete specimen during freezing-thawing. The properties of mass, dynamic elastic modulus, flexural strength and compressive strength of low antifreeze design level hydraulic concrete under different low temperature were compared. And the microscopic property of low antifreeze design level hydraulic concrete was observed by environmental scanning electron microscope (ESEM).

Population differences in antifreeze production cycles of juvenile Atlantic cod (Gadus morhua) reflect adaptations to overwintering environment

Four groups of juvenile Atlantic cod (Gadus morhua) were collected in summer (1992) from four coastal sites of northeast Newfoundland. They were held together at seasonally ambient temperature and photoperiod and monitored over one winter for variation in a biochemical phenotype, antifreeze production capacity. Our results show that population differences in antifreeze production capacity reflect the severity of overwintering conditions faced. Cod from three bays along the northeast coast (49.5°-47.5° N) exhibited very similar patterns of antifreeze production, suggesting that these environments demand from their cod inhabitants approximately the same high level of freeze resistance. However, cod from the most exposed northerly site at the tip of the Great Northern Peninsula (51.5° N) developed antifreeze levels about 50% higher than those of the other three groups, confirming that the more extreme high-latitude environment demands even greater freeze protection for survival. Since 34% of Great Northern Peninsula cod produced antifreeze levels outside the range of all other juveniles, we suggest that the physiological distinctness of this population has evolved by genetic amplification of antifreeze production capacity rather than by selective mortality. The existence of physiological population structure should be factored into strategies for sustainable fishing of this species in northern waters.

Genetic differentiation between inshore and offshore Atlantic cod (Gadus morhua) off Newfoundland: microsatellite DNA variation and antifreeze level

Microsatellite DNA provided evidence that Atlantic cod overwintering in inshore Newfoundland are genetically distinguishable from cod overwintering offshore. We compared variation in five loci in samples from inshore locations around Trinity Bay, Newfoundland, and from an offshore region on the northern Grand Bank (North Cape). Cod collected inshore were divided into two groups on the basis of antifreeze level in blood: those with high antifreeze levels presumed to have overwintered in cold ( 2°C) waters. Fish overwintering inshore differed from offshore fish in allele sharing and in (δμ) 2 distances, while fish with low antifreeze levels did not. Subpopulation structure ( Rst) was detected when offshore cod were compared with inshore cod with high levels of antifreeze but not when compared with those with low levels of antifreeze. These results suggest that cod overwintering inshore are genetically distinct from offshore cod. Inshore and offshore cod from the areas studied remain genetically distinct despite the fact that individuals from the two populations intermingle inshore during the summer and fall feeding migration. Thus, we found evidence of population structure at a finer geographical scale than has been shown to date for this species.

Movements of farmed and wild Atlantic cod (Gadus morhua) released in Trinity Bay, Newfoundland

Fishery scientists and managers are investigating the feasibility of enhancing annual recruitment to the northern Atlantic cod (Gadus morhua L.) stock complex off Labrador and northeastern Newfoundland through the release of farmed fish back into the sea. Release of newly matured fish and adults with farm-advanced fecundity would increase the spawning biomass. Enhancement efforts might be measurably successful in major bays that are year-round habitats for cod. To determine if farmed cod would remain and spawn in Trinity Bay, 14 fish with surgically implanted transmitters were released in November 1992. Sonic tracking confirmed that farmed cod released on the western side of Trinity Bay overwintered within the bay, and integrated with wild cod approaching spawning condition in April 1993. Blood plasma antifreeze levels confirmed that these wild cod had overwintered inshore in subzero waters. A spawning aggregation was found in July 1993, providing evidence that northern cod reproduce in Newfoundland bays. These findings suggest that it may be possible to increase the number of cod spawning inshore through the release of farmed fish.

Genetic differentiation between inshore and offshore Atlantic cod (<I>Gadus morhua</I>) off Newfoundland: microsatellite DNA variation and antifreeze level

Microsatellite DNA provided evidence that Atlantic cod overwintering in inshore Newfoundland are genetically distinguishable from cod overwintering offshore. We compared variation in five loci in samples from inshore locations around Trinity Bay, Newfoundland, and from an offshore region on the northern Grand Bank (North Cape). Cod collected inshore were divided into two groups on the basis of antifreeze level in blood: those with high antifreeze levels presumed to have overwintered in cold ( 2°C) waters. Fish overwintering inshore differed from offshore fish in allele sharing and in (δμ) 2 distances, while fish with low antifreeze levels did not. Subpopulation structure ( Rst) was detected when offshore cod were compared with inshore cod with high levels of antifreeze but not when compared with those with low levels of antifreeze. These results suggest that cod overwintering inshore are genetically distinct from offshore cod. Inshore and offshore cod from the areas studied remain genetically distinct despite the fact that individuals from the two populations intermingle inshore during the summer and fall feeding migration. Thus, we found evidence of population structure at a finer geographical scale than has been shown to date for this species.

Antifreeze Production, Freeze Resistance, and Overwintering of Juvenile Northern Atlantic Cod (Gadus morhua)

Four size groups of northern Atlantic cod (Gadus morhua) (juveniles < 15, 15–25, and 26–40 cm and adults > 50 cm) were investigated over a winter cycle for their ability to increase freeze resistance by producing plasma antifreeze glycoproteins. All juveniles had significantly higher plasma antifreeze levels than adults during the winter (January–March) under similar conditions of cycling temperature and ambient photoperiod. Highest winter plasma antifreeze levels and lowest plasma freezing temperatures were consistently found in the 15–25 cm group. Fish length and plasma antifreeze levels were inversely related from January to April, with the exception of the 0 + cod. All juvenile groups developed considerable freeze protection early in the winter cycle before the onset of freezing temperatures. However, the adults were not significantly protected until the end of January, when ambient temperatures had fallen below 0 °C. The 15–25 cm cod were held in three cycling temperature regimes. Induction temperatures for antifreeze production in this size group appeared to be between 2 and 3 °C, as compared with between 1 and 0 °C for the adults. We suggest that these patterns of antifreeze production may have direct bearing on habitat selection and overwintering behaviour of the northern Atlantic cod at different stages of development.

Seasonal and Phenotypic Variations in Plasma Protein Antifreeze Levels in a Population of Marine Fish, Sea Raven (Hemitripterus americanus)

The annual cycle of plasma antifreeze polypeptide levels and Na+and Cl−concentrations were measured in sea raven (Hemitripterus americanus) from a New Brunswick population. Both Na+and Cl−concentrations showed a distinct seasonal cycle, with the highest concentration of both ions occurring during the winter months. Mean plasma antifreeze levels also showed a significant seasonal cycle, with the highest values occurring during winter. Two features of the annual plasma antifreeze cycle differed considerably from the annual cycles observed in other temperate water fish: antifreeze polypeptides were present throughout the year and, during the winter, 40–50% of the fish had antifreeze levels that were the same as those observed during the summer. Thus, our results modify the generally accepted view that the presence of plasma antifreeze proteins correlates with the seasonal period of low water temperatures and that only fish inhabiting polar oceans maintain high levels of antifreeze peptides in their blood all year round.

Photoperiodic and thermal regulation of antifreeze protein levels in the beetle Dendroides canadensis

The importance of photoperiod, temperature and their interaction in controlling the seasonal pattern of haemolymph antifreeze protein levels in larvae of the beetle Dendroides canadensis was investigated. A complete photoperiodic response curve for antifreeze protein production was generated at 20°C with larvae collected in early fall. Individuals exposed to a 10-h photoperiod or less, including constant darkness, had significantly elevated antifreeze levels over those maintained in an 11-h photoperiod or more, including constant light. The critical daylength resulting in 50% population response lies between LD 11:13 and LD 10:14. This photoperiodic response was masked at sufficiently low (threshold between 15 and 10°C) and high (threshold between 25 and 30°C) temperatures. Partial photoperiodic response curves (at 17 and 25°C) obtained within this specified temperature range indicate that the position of the critical photoperiod (between 10 and 11 h) is stable while the amplitude of the response curve is temperature dependent. Experiments investigating the mechanisms controlling the spring depletion of protein antifreeze levels suggest that both photoperiod and temperature are important. The dominant response of photoperiod in the fall along with the modifying effects of temperature are considered to provide the necessary precision to assure adequate cold tolerance early in the fall and the flexibility to protect the species from yearly variation in weather conditions.

Preparatory adaptations for winter survival in the cold hardy beetles,Dendroides canadensis andDendroides concolor

Thermal hysteresis (indicative of macromolecular antifreeze levels) was measured in hemolymph samples from the beetle,Dendroides canadensis, after acclimation to a short (8 h) photoperiod at 20 °C, or long (16 h) photoperiod at temperatures of 10 and 20 °C. Both the short photoperiod and low temperature (10 °C) treatment caused a significant elevation of thermal hysteresis, thereby implicating increased antifreeze protein production. Oxygen consumption rates of animals in each acclimation treatment were measured and no significant differences in metabolic rates were noted between treatments when measured at a high (20 °C) temperature. Thus, conditions which initiate antifreeze protein production fail to induce a diapause condition, characterized by a drop in metabolic rates. Likewise, natural populations sampled in mid-winter possess elevated levels of thermal hysteresis, and accumulated glycerol and sorbitol, but do not show a depressed metabolic rate. Therefore,D. canadensis do not enter a diapause during the winter, but are fully capable of achieving a high level of cold hardiness through the accumulation of antifreeze proteins and polyhydroxy alcohols.

Antifreeze agents of terrestrial arthropods

1. 1. Many insects and other terrestrial arthropods which overwinter in exposed sites in temperate and polar regions are freeze-susceptible (unable to survive freezing) and therefore the seasonal production of antifreezes is critical for their survival. 2. 2. Many of these freeze-susceptible terrestrial arthropods employ low molecular weight antifreezes. such as polyols and sugars. These solutes lower the supercooling point of the insect approximately 2 × more than they lower the melting point. 3. 3. Proteins, similar to the antifreeze proteins and glycoproteins of polar marine fishes, which produce a thermal hysteresis (differences between freezing and melting points) of several degrees function as antifreezes in a number of insects, spiders and a centipede. In some species these proteins are the only identifiable antifreezes, while in other species polyols are also produced. 4. 4. Temperature and photoperiod are the most important environmental cues used to trigger the production and loss of the thermal hysteresis proteins (THP's). The physiological timing processes which control antifreeze levels involve the insect's circadian system. 5. 5. Several insect THP's have now been purified and their compositions analyzed. In general, these insect THP's have more hydrophilic amino acids and a much lower alanine content than fish THP's. Perhaps the most interesting of the insect THP's is one from Tenebrio molitor, which contains 28% cysteine residues.

Environmental effects on antifreeze levels in larvae of the darkling beetle, Meracantha contracta

AbstractAcclimation of Meracantha contracta larvae collected in late summer to low temperatures, short photoperiods or low relative humidities induces production of a macromolecular antifreeze which functions to depress the freezing and supercooling points of the larvae. Overwintering larvae must be exposed to a combination of high temperature and long photoperiod before the antifreeze is lost.

Variations in macromolecular antifreeze levels in larvae of the darkling beetle, Meracantha contracta.

Overwintering larvae of the darkling beetle, Meracantha contracta, produce a macromolecular antifreeze that is similar in activity to the glycoproteinaceous and proteinaceous antifreezes found in some cold-water, marine teleost fishes. The antifreeze is not present in the hemolymph of the Meracantha larvae in summer, but its production begins by late September in the wild population. The antifreeze reaches a maximum concentration in February, decreases slowly through spring, and disappears by early June. The supercooling points of the larvae are lowest in February, when the antifreeze levels are highest, and increase as the antifreeze concentrations in the hemolymph decrease in the spring. Larvae collected in mid-February and warm-acclimated lost the antifreeze with-in 12 days. Larvae collected in early September and cold-acclimated required nearly two months to produce concentrations of antifreeze comparable to those of overwintering larvae. Temperature seems to be the major environmental factor responsible for the control of antifreeze levels in Meracantha; however, other environmental factors may also be involved.