Cold-induced changes affect survival after exposure to vitrification solution during cryopreservation in the south-west Australian Mediterranean climate species Lomandra sonderi (Asparagaceae)

There is limited knowledge of the effects of exposure to low temperatures in the unique Mediterranean climate plant species of Western Australia. We have thus investigated the effect of low temperature on cryogenic tolerance in Lomandra sonderi, an endemic perennial species of southwest Western Australia. Lomandra sonderi plants were preconditioned in tissue culture at constant 23 °C (12 h light/dark cycle) or alternating 20/?1 °C (16 h light and 8 h dark cycle). Shoot tips from both conditions were analysed for their phospholipid, sterol and soluble sugar compositions. Shoot tips were also cryoexposed via a droplet-vitrification protocol. Survival in both preconditioning regimes for cryoexposed and non-cryoexposed samples was the same, but plants from the 20/?1 °C regime displayed an improved tolerance to the overall cryopreservation process in both cryoexposed and non-cryoexposed samples, thereby eliminating exposure to liquid nitrogen as a primary cause of reduced post-cryogenic viability. Preconditioning of in vitro shoots of L. sonderi at 20/?1 °C induced significant increases in phosphatidylcholine (from 7.30 ± 3.46 to 22.2 ± 7.80 ng mg^?1 FW) and increases in several soluble sugars (fructose, galactose, glucose, sucrose) compared to shoots incubated at 23 °C—changes consistent with known cold acclimation responses in plant species generally—but sterol content remained largely unchanged. Analysis of electrolyte leakage in shoot tips from both preconditioning regimes generated a significantly lower LT₅₀ value in the 20/?1 °C samples (?5.45 ± 0.53 °C) over the 23 °C samples (?2.5 ± 0.08 °C). Increased tolerance to cryoexposure in L. sonderi appears to lie mainly with acclimation-induced changes in membrane composition and promotion of membrane stability and hence increased resistance to freeze damage.     

Seed dormancy and germination in the giant Himalayan lily (Cardiocrinum giganteum var. giganteum): an assessment of its potential for naturalization in northern Japan

Understanding the potential for ornamental plant species to become naturalized in a nonnative habitat requires information on seed germination in order to help predict responses of the species to the natural environmental conditions of its new habitat. Cardiocrinum giganteum var. giganteum, which is native to the Himalayas, has been introduced as an ornamental plant in temperate regions of the world, and was categorized recently as invasive in New Zealand. Seed germination requirements of the species were determined under natural conditions in Hokkaido, Japan, to assess its potential to become naturalized in this region of Japan. Mature seeds were collected from its native range in the Indian Himalayas. At maturity in autumn, seeds had underdeveloped embryos, which grew in the second autumn and winter after exposure to summer temperatures. Radicles and cotyledons emerged in late winter and spring. Thus, an 18?C19?month period was required from dispersal to seed germination. Under laboratory conditions, this period could be shortened to 10?C11?months in a 25/15?°C (120?days)????15/5?°C (90?days)????0?°C (90?days)????15/5?°C (60?days) temperature sequence. GA₃ did not substitute for the above temperature requirements. These temperature requirements for seed germination of C. giganteum var. giganteum are very similar to those of its native Japanese congener C. cordatum var. glehnii. Seeds of both taxa have deep simple morphophysiological dormancy. The close similarity in the requirements for regeneration from seeds of the two taxa suggests that the seed stage of the life cycle is not an impediment to the naturalization of the giant Himalayan lily in northern Japan.     

Cryopreservation of some useful microalgae species for biotechnological exploitation

Culture collections of microalgae represent a biological resource for scientific research and biotechnological applications. When compared to the current methods of maintenance and sub-culturing, cryopreservation minimizes labor costs and is an effective method for maintaining a large range of species over long periods with high stability. In order to determine the best cryopreservation method for microalgae species with great biotechnological potential, three freezing protocols were employed using different cryoprotectants (dimethyl sulfoxide—Me₂SO; methanol—MeOH). Three marine microalgae species (Thalassiosira weissflogii; Nannochloropsis oculata, and Skeletonema sp.) were cooled by directly plunging into liquid nitrogen (?196°C) and with two-step controlled cooling protocols (?18°C and ?80°C pre-treatments). After storage periods ranging from 10 to 120 days, viability was determined by the ability of cells to actively grow again. Results obtained for T. weissflogii showed that this species could be preserved at ultra-low temperature (?196°C) for 10 and 30 days with 10?% Me₂SO and 5?% MeOH when employed a controlled cooling protocol (?80°C). N. oculata was successfully cryopreserved either by direct freezing or with controlled cooling protocols. N. oculata samples presented good responses when treated with 5?% Me₂SO, 10?% Me₂SO, 5?% MeOH and even without any cryoprotectant. Skeletonema sp. did not survive cryopreservation in any of the tested conditions. The results indicate the difficulty in establishing common protocols for different microalgae species, being necessary further studies for a better understanding of cell damages during freezing and thawing conditions for each species.     

Temperature effects on hyphal growth of wood-decay basidiomycetes isolated from Pinus densiflora deadwood

Hyphal growth rates were tested on malt extract agar plates at eight different temperatures (5–40?°C) using 36 isolates of 17 basidiomycete species obtained from Pinus densiflora deadwood in Japan. All isolates of four brown rot species showed optimum growth at 30?°C, whereas the optimum growth temperature of white rot species varied from 20?°C to 30?°C. Analysis using a dataset from four cooler sites showed that brown rot fungi grew more rapidly than white rot fungi at higher temperatures (25?°C, 30?°C, and 35?°C). These results suggest that the hyphal growth of brown rot fungi might be physiologically adapted to higher temperatures than those of white rot fungi among the fungal species inhabiting deadwood of P. densiflora in Japan.     

Effects of temperature and irradiance on quantum yield of PSII photochemistry and xanthophyll cycle in a tropical and a temperate species

The effect of a wide range of temperatures (?15 and 60°C) in darkness or under strong irradiation [1,600 μmol(photon) m^?2 s^?1] on quantum yield of photosystem II photochemistry and xanthophyll cycle pigments was investigated in a tropical fruit crop (Musa sp.) and a temperate spring flowering plant (Allium ursinum L.). In darkness within the nonlethal thermal window of A. ursinum (from ?6.7 to 47.7°C; 54.5 K) and of Musa sp. (from ?2.2°C to 49.5°C; 51.7 K) maximal quantum yield of PSII photochemistry (F_v/F_m) was fairly unaffected by temperature over more than 40 K. At low temperature F_v/F_m started to drop with ice nucleation but significantly only with initial frost injuries (temperature at 10% frost damage; LT₁₀). The critical high temperature threshold for PSII (T_c) was 43.8°C in A. ursinum and 44.7°C in Musa sp. Under strong irradiation, exposure to temperatures exceeding the growth ones but being still nonlethal caused photoinhibition in both species. Severity of photoinhibition increased with increasing distance to the growth temperature range. ΔF/F_m′ revealed distinctly different optimum temperature ranges: 27–36°C for Musa sp. and 18–27°C for A. ursinum exceeding maximum growth temperature by 2–7 K. In both species only at temperatures > 30°C zeaxanthin increased and violaxanthin decreased significantly. At nonlethal low temperature relative amounts of xanthophylls remained unchanged. At temperatures > 40°C β-carotene increased significantly in both species. In Musa sp. lutein and neoxanthin were significantly increased at 45°C, in A. ursinum lutein remained unchanged, neoxanthin levels decreased in the supraoptimal temperature range. In darkness, F_v/F_m was highly temperature-insensitive in both species. Under strong irradiation, whenever growth temperature was exceeded, photoinhibition occurred with xanthophylls being changed only under supraoptimal temperature conditions as an antiradical defence mechanism.     

Seed germination and seedling growth of Zostera marina L. (eelgrass) in the chesapeake bay

Seed germination and seedling growth of Zostera marina L. were monitored in the Chesapeake Bay in 1979 and 1980. Harvested seeds were placed in small acrylic tubes at several sites representing the salinity range of Z. marina distribution. Seed germination was observed first in late September and continued through May, with peaks in the fall and spring. The majority of seeds that germinated (66%) did so between December and March when water temperatures ranged from 0–10°C. There was no correlation between sites (different salinity regimes) and frequency of germination rates, indicating that salinity was not a major factor in the germination process in this study. Additional information on seed germination was available for seeds collected in 1977 and 1980 and subsequently monitored for germination at only one site. These data were similar to germination frequency recorded in 1979–1980.Seedling growth was measured from individuals collected from an existing Zostera marina bed. Seedlings were collected from November through May, at which time we could no longer distinguish seedlings from existing vegetative stock. Growth was characterized by the increased length of the primary shoot, number of leaves per shoot and numbers of shoots per plant. Seedling growth was slow during the winter months (water temperature ? 10°C) but rapidly increased in the spring (temperatures > 10°C). The size range of the harvested seedlings indicated that seed germination in the field probably occurred from October through April, corroborating evidence from the seed germination experiments.     

The effect of temperature on the self-association of S5 and on the association of S5 with S8 as determined by sedimentation equilibrium

Solutions of proteins S5 and S8 from the Escherichia coli 30 S ribosomal subunit have been examined by sedimentation equilibrium methods as a function of temperature for their behavior in solution as isolated components and in mixtures. The standard enthalpy and entropy at 4 °C for the isodesmic self-association of S5 were determined from a study over the temperature range of 3 to 33 °C to be 0.1 ± 0.9 kcal/mol and 18 ± 3 cal/(mol × deg), respectively. The protein S8 remained monomeric over the same range of temperature. The standard enthalpy and entropy at 4 °C for the association of S5 and S8 were determined on mixtures from a study over the temperature range of 3 to 27 °C to be ?0.4 ± 1.6 kcal/mol and 20 ± 6 cal/(mol × deg), respectively. Based on these values and the previously determined standard Gibbs free energies (S. H. Tindall and K. C. Aune, 1981, Biochemistry20, 4861–4866), the driving force for the self-association of S5 and the association of S5 with S8 could be interpreted as being derived from the expulsion of water upon ion pair formation at the interaction sites.     

Insecticidal effect of high carbon dioxide atmospheres on thrips eggs oviposited in plant tissue

Thrips are damaging crop pests, but their eggs are difficult to detect for farmers and agricultural inspectors. We investigated the insecticidal effects of an elevated carbon dioxide atmosphere on thrips eggs oviposited within plant tissues. Percent mortality of Frankliniella occidentalis (Pergande), Frankliniella intonsa (Trybom), Thrips tabaci Lindeman, and Thrips palmi Karny exposed to 60?% CO₂ was evaluated at different temperatures (20, 25, 30, and 34?°C) and durations. Egg mortality of all four species increased with CO₂ exposure duration at each temperature, and the time required to achieve 100?% mortality decreased as the temperature increased between 20?C30?°C. Exposure to 60?% CO₂ at 30?°C for 12?h is considered to be 100?% lethal to most thrips pests of fresh agricultural produce. Our findings suggested that CO₂ treatment could be used to propagate thrips-free plants in horticultural nurseries.     

Effect of low and high temperatures on the photosynthetic performance of Lantana camara L. Leaves in darkness

Low and high temperatures are known as most important factors influencing plant performance and distribution. Plants of Lantana camara L. coming from two distinct geographical populations (Iberian Peninsula and Galápagos Islands) were cultivated in a common garden experiment, and their leaves were subjected to thermal treatments (from +20.0 to ?7.5°C during the winter and from +20.0 to +50.0°C during the summer) in a programmable water bath in darkness. Their photosynthetic performance and their recovery capacity after the thermal treatment were evaluated by measuring chlorophyll fluorescence, net photosynthesis rate, and leaf necrosis. In general, L. camara photosynthetic apparatus showed a wide range of temperature tolerance in darkness, showing optimal functioning of its photosystem II just after exposure to temperatures between ?2.5 and +35.0°C for the Iberian population and between +10.0 and +25.0°C for the Galápagos population. Just after exposure to low and high temperatures, gradual cold and heat-induced photoinhibition was recorded for both populations. After 24 h, leaves of L. camara demonstrated a great recovery capacity from ?2.5 to +42.5°C. However, leaves of the treatments from ?5.0°C down and +47.50°C up showed permanent damages to the photosynthetic apparatus and to the leaf tissues. Slight interpopulation differences were found only at extreme temperatures.     

Apis iridescent virus and "clustering disease" of Apis cerana

NPV of Spodoptera littoralis was completely inactivated in vitro following 10 min of exposure to a temperature higher than 90°C, but survived 3 weeks at ?20°C. At pH 12, some 75% of the infectivity was lost. Measurable proteolysis in vitro of the polyhedral protein by a larval midgut extract could be obtained only when the pH of the reaction mixture was raised to an unnatural level of 10.5, the natural pH of the midgut content being 8.5 or 9.5 according to different authors. The plant growth retardant Phosfon synergized mortality caused by the NPV. The virus could be cross-transmitted to two congeneric species of Spodoptera (S. exigua and S. litura), but could not infect any of four tested species belonging to other genera of the Moctuid family.     

Environmental induction of larval diapause and life-history consequences of post-diapause development in the Large Copper butterfly,Lycaena dispar (Lepidoptera: Lycaenidae)

Many insects in temperate zones withstand the adverse conditions of winter through entering diapause and the two most important environmental stimuli that induce diapause are photoperiod and ambient temperature. The Large Copper butterfly, Lycaena dispar Haworth (Lepidoptera: Lycaenidae), is a Palearctic butterfly that hibernates as larvae. Since this butterfly is a near threatened species in some regions, there has been a growing need for a standardized protocol for mass rearing of this butterfly based on the adequate knowledge of its ecology. In the present study, we first identified that L. dispar larvae were sensitive to the photoperiodic induction of diapause during their first larval instar. We then investigated to what extent the diapause-inducing effects of photoperiod could be modified by ambient temperatures in L. dispar larvae by exposing them to the range of day-lengths (L:D 14:10, 12:12, 10:14 and 8:16) at three different temperatures (15, 20 and 25 °C). All larvae were induced to enter diapause at low ambient temperature (15 °C) regardless of photoperiod, whereas most of them (86 %) exhibited direct development when temperature was high (25 °C). The photoperiodic induction of diapause was evident when day-length was shorter than 14 h at intermediate temperature (20 °C). Pre-diapause development was prolonged at low temperatures. Finally, we found that post-diapause development of L. dispar larvae was determined by both the chilling temperature experienced by diapausing larvae and the duration of larval diapause. Adult emergence was enhanced when larvae were chilled at 8 °C and when they had been under the state of diapause for 20 days before they were treated to terminate diapause.     

Multi-locus DNA fingerprinting and genetic diversity in jute (Corchorus spp.) based on sequence-related amplified polymorphism

Sequence-Related Amplified Polymorphism (SRAP) markers were used for genetic diversity assessment and cultivar identification among 31 cultivars of jute belonging to two cultivated species Corchours olitorius L. and C. capsularis L. Forty-three primer-pairs produced a total of 394 bands with an average of 9 bands per primer pair and 89% bands were polymorphic across the genotypes of two species. Average genetic diversity in the cultivars of C. olitorius and C. capsularis was 7.2% (range 2.8–12.3%) and 7.6% (range 2.2–13.1%), respectively. Jute cultivars JRC 698, JRC 7447, TJ 40, S19 and JRO 3690 were more diverse compared to rest of the cultivars. UPGMA cluster analysis grouped all cultivars into two clusters which were representative of C. olitorius and C. capsularis species. All the cultivars could be unequivocally differentiated from one another based on the pooled profile of 43 primer-pairs, however, 24 of 31 cultivars could be identified uniquely. The probability of chance identity of any two cultivars based on SRAP markers was very low and was 6.95?×?10^?07 and 2.23?×?10^?07 for cultivars of C. capsularis and C. olitorius, respectively. Primer-pairs EM1-ME5, EM4-ME1, EM8-ME1 and EM10-ME1 were found to be useful for genetic diversity and cultivar identification. Our results show that SRAP markers could be effectively used for genetic diversity analyses in jute. For poor genetic diversity and resulting narrow genetic base, these markers will prove to be highly useful for identifying elite germplasm in a jute breeding program.     

Bioremediation potential of Chondrus crispus (Basin Head) and Palmaria palmata: effect of temperature and high nitrate on nutrient removal

To evaluate the nutrient removal capabilities of two red macroalgae, apical blades were cultured in the lab for 4?weeks at either 6, 10, or 17°C and nitrate at either 30 or 300?μM, typical of the seasonal range of conditions at a land-based Atlantic halibut farm. Stocking density was 2.0?g?L^?1, irradiance 125?μmol?photons?m^?2?s^?1, photoperiod 16:8 (L:D), and nitrogen to phosphorus ratio 10:1. For both species, the highest growth rate was at 300?μM NO ₃ ^? with Palmaria palmata growing fastest at 6°C, 5.8%?day^?1, and Chondrus crispus growing best at 17°C, 5.5%?day^?1. Nitrogen and carbon removal by P. palmata was inversely related to temperature, the highest rate at 6°C and 300?μM NO ₃ ^? of 0.47?mg N and 6.3?mg C per gram dry weight per day. In contrast, C. crispus removal of N was independent of temperature, with mean removal of 0.49?mgN?gDW^?1?day^?1 at 300?μM NO ₃ ^? . The highest carbon removal by C. crispus was 4.4?mgC?gDW^?1?day^?1 at 10°C and 300?μM nitrate, though not significantly different from either 6 or 17°C and 300?μM nitrate. Tissue carbon:nitrogen ratios were >20 in both species at 30?μM nitrate, and all temperatures indicating nitrogen limitation in these treatments. Phycoerythrin content of P. palmata was independent of temperature, with means of 23.6?mg?gFW^?1 at 300?μM nitrate. In C. crispus, phycoerythrin was different only between 6°C and 17°C at 300?μM nitrate, with the highest phycoerythrin content of 12.6?mg?gFW^?1 at 17°C. Morphological changes were observed in P. palmata at high NO ₃ ^? concentration as curling of the fronds, whilst C. crispus exhibited the formation of bladelets as an effect of high temperature.     

Tolerance response of Lessonia flavicans from the sub-Antarctic ecoregion of Magallanes under controlled environmental conditions

Environmental heterogeneity plays a key role in spatio-temporal distribution of organisms, their ecology and their evolutionary biology, with their physiological response, or tolerance to the environment defining their distributional range. The macroalgae of the sub-Antarctic ecoregion of Magallanes are subject to a wide range of environments, resulting from geomorphological processes (glacial erosion in the Quaternary), oceanographic gradients, and drastic seasonal variations of photoperiod and irradiance (winter <8 h of light, summer >17 h). We examined the tolerance response of the brown alga Lessonia flavicans to contrasting environments (three salinities, two temperatures, and two photoperiods) under controlled laboratory conditions. Our results suggest that L. flavicans has limited salinity tolerance that is affected by temperature and photoperiod. Summer temperature (9 °C?±?0.02) and photoperiod (18:6 h L:D) and salinity 32 psu seem optimal conditions for L. flavicans sporophyte development. Results of the present study provide key information for culturing a species of high economic and biological value, and could aid in predicting the species potential tolerance response to environmental fluctuations in the wake of global changes.     

Thermal phase transitions in the polar lipids of plant membranes. Their induction by disaturated phospholipids and their possible relation to chilling injury

The phase behaviour of leaf polar lipids from three plants, varying in their sensitivity to chilling, was investigated by differential scanning calorimetry. For the lipids from mung bean (Vigna radiata L. var. Berken), a chilling-sensitive plant, a transition exotherm was detected beginning at $\text{10 ± 2°}\text{C}$. No exotherm was evident above 0°C with polar lipids from wheat (Triticum aestivum cv. Falcon) or pea (Pisum sativum cv. Massey Gem), plants which are insensitive to chilling. The enthalpy for the transition in the mung bean polar lipids indicated that only about 7% w/w of the lipid was in the gel phase at ?8°C. The thermal transition of the mung bean lipids was mimicked by wheat and pea polar lipids after the addition of 1 to 2% w/w of a relatively high melting-point lipid such as dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylglycerol or dimyristoylphosphatidylcholine. Analysis of the polar lipids from the three plants showed that a dipalmitoylphosphatidylglycerol was present in mung bean (1.7% w/w) and pea (0.3% w/w) but undetected in wheat, indicating that the transition exotherm temperature of 10°C in mung bean, 0°C in pea and about ?3°C in wheat correlates with the proportion of the high melting-point disaturated component in the polar lipids. The results indicate that the transition exotherm, observed at temperatures above 0°C in the membranes of chilling-sensitive plants, could be induced by small amounts of high melting-point lipids and involves only a small proportion of the membrane polar lipids.     

Overwintering temperatures affect freezing temperatures of turions of aquatic plants

The effect of different overwintering temperatures (2.5 ± 1 °C in a refrigerator or outdoor natural overwintering on wet topsoil with weak frosts) on the freezing temperature and survival rate of turions of 10 aquatic plant species with different ecological traits (free-floating habit or bottom rooting) was studied using mini thermocouples. Dormant, non-hardened turions of 9 species exhibited freezing within a narrow temperature range of ?7.0 to ?10.2 °C, while Hydrocharis morsus-ranae froze at ?3.6 °C. The survival rate of the turions after the measurements was, however, very low (0–38%). In several species, the freezing temperature of turions at the beginning of germination was not significantly different (at p < 0.05) from the dormant ones. The mean freezing temperature of outdoor hardened turions of 6 species was within a very narrow range of ?2.8 to ?3.3 °C and was thus significantly higher by 4–7 °C (p < 0.0002) than that for the non-hardened turions. It is assumed that the freezing temperatures indicate freezing of the extracellular water. The hardened turions of all 7 species were able to survive mild winter frosts under the topsoil conditions at a rate of 76–100%. These characteristics suggest that the turions of aquatic species can be hardened by weak frosts and that their frost hardiness is based on the shift from frost avoidance in non-hardened turions to frost tolerance.     

Incubation temperature critical to successful stimulation of in vitro zygotic embryo growth in four Australian native Cyperaceae species

Many species of Western Australian Cyperaceae (sedges) are vital components of the indigenous flora but commonly display low seed set, poor seed quality and intractable seed dormancy. We report the effects of incubation temperature and in vitro growth media on whole seed germination compared with extracted zygotic embryo growth in Tetraria capillaris, T. octandra, Lepidosperma drummondii and L. tenue. No germination was observed from intact whole seeds of all test species regardless of the treatment evaluated. In contrast, excised zygotic embryos of all study species exhibited significant increases in growth when cultured at 15°C compared to embryos incubated at 25°C; however, optimal media for embryo growth were genera specific. Extracted embryos of T. capillaris and T. octandra exhibited maximum percentage growth (30 and 40%, respectively) at 15°C on ½ MS medium with no plant growth regulators required. In the case of L. drummondii and L. tenue 1 μM thidiazuron was a necessary addition to the ½ MS medium resulting in 40 and 77% growth of embryos (at 15°C), respectively. Incubation of extracted embryos at 25°C (regardless of medium treatment) resulted in <10% embryo growth for T. octandra and L. tenue, while the remaining two species (L. drummondii, T. capillaris) showed no embryo growth at 25°C on any medium treatment.     

Effect of photoperiod and cold acclimation on survival of mice in cold

Male albino mice (Swiss-Webster) were raised at 5 °C under short (8L:16D) and long (16L:8D) light periods. All mice were housed in groups of three to five individuals in plastic mouse cages (16 × 12 × 28 cm) until 42 days of age with food and water ad libitum and cold exposed to ?40 °C between 10:00 am and 4:00 pm to determine survival time or time until loss of righting response occurred (CT min). Under short photo-periods, survival time was 49.3 ± 4.4 min and under long photoperiods it was 38.7 ± 1.9 min (P < 0.05). A second group of mice was maintained from birth at thermoneutral temperature (22 °C) under constant darkness, short day lengths (4L:20D), or constant light in the same fashion as mentioned above. When exposed to ?20 °C survival time was found to be 80.0 ± 5.0 min for the animals kept in constant darkness, 61.1 ± 2.3 min for animals raised in short photo-periods (4L:20D) (P < 0.01), and 52.4 ± 2.3 min for mice raised in constant light (P < 0.05). After 30 min mean rectal temperature was 32.1 ± 0.47 °C for constant-darkness animals, 30.5 ± 0.43 °C for short-day animals (P < 0.02), and 28.5 ± 0.74 °C for animals raised in constant light (P < 0.05). After 60 min mean rectal temperatures for constant-dark, 4L:20D, and constant-light animals were compared and body temperature was found to be 23.7 ± 1.6, 17.3 ± 1.5 (P < 0.01), and 12.8 ± 0.87 °C (P < 0.05), respectively. From these data, it is obvious that photoperiod influences cold resistance at both cold and thermoneutral acclimation temperatures although when considered individually, cold acclimation enhances cold survival to a greater degree than does reduced light exposure.     

Physiological performance of the cold-water coral Dendrophyllia cornigera reveals its preference for temperate environments

Cold-water corals (CWCs) are key ecosystem engineers in deep-sea benthic communities around the world. Their distribution patterns are related to several abiotic and biotic factors, of which seawater temperature is arguably one of the most important due to its role in coral physiological processes. The CWC Dendrophyllia cornigera has the particular ability to thrive in several locations in which temperatures range from 11 to 17 °C, but to be apparently absent from most CWC reefs at temperatures constantly below 11 °C. This study thus aimed to assess the thermal tolerance of this CWC species, collected in the Mediterranean Sea at 12 °C, and grown at the three relevant temperatures of 8, 12, and 16 °C. This species displayed thermal tolerance to the large range of seawater temperatures investigated, but growth, calcification, respiration, and total organic carbon (TOC) fluxes severely decreased at 8 °C compared to the in situ temperature of 12 °C. Conversely, no significant differences in calcification, respiration, and TOC fluxes were observed between corals maintained at 12 and 16 °C, suggesting that the fitness of this CWC is higher in temperate rather than cold environments. The capacity to maintain physiological functions between 12 and 16 °C allows D. cornigera to be the most abundant CWC species in deep-sea ecosystems where temperatures are too warm for other CWC species (e.g., Canary Islands). This study also shows that not all CWC species occurring in the Mediterranean Sea (at deep-water temperatures of 12–14 °C) are currently living at their upper thermal tolerance limit.     

Winter survival of an adult bark beetle Ips acuminatus Gyll

Freezing-susceptible adult Ips acuminatus hibernate underneath bark of Scots pine. The beetles lower their supercooling points from ?20 to ?34°C due to accumulation of low molecular weight antifreezes. The capability of specimens to supercool to about ?20°C in the absence of cryoprotective solutes during winter, seemed to be at least partially attributable to the presence of a thermal hysteresis factor at 3–4°C.Using a GC-MS-COM technique, a unique combination of accumulated solutes present only in specimens demonstrating supercooling points below ?20°C was identified as ethylene glycol, mannitol, sorbitol and dulcitol. Not previously found in nature, ethylene glycol was the major solute (90%) synthesized at sub-zero temperatures. Exposure to ?10°C was an effective cue to accumulation of ethylene glycol and nearly 5 times as effective in promoting sorbitol synthesis than was ?5°C. When low molecular weight substances were lost at high temperatures, they were not re-synthesized in beetles re-exposed to sub-zero temperature. The supercooling point was closely related to both the concentration of ethylene glycol and to the haemolymph melting point. Attempts to correlate changes in sorbitol concentrations to changes in supercooling points were not conclusive.Proliferation of thermal hysteresis was observed in the beginning of November. A melting-hysteresis freezing point differential of about 3.6°C was demonstrated in the haemolymph of beetles during December. No thermal hysteresis was demonstrated in the haemolymph of positive phototactic beetles or in the outdoor beetles in May. The combination of high temperature and long photoperiod appeared to be a more effective cue to the final loss of thermal hysteresis than was high temperature alone.