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PubMed1999

The physiology of diving in a north-temperate and three tropical turtle species.

We examined changes in blood gases, plasma ions, and acid-base status during prolonged submergence (6 h) of four aquatic turtle species in aerated water at 20 degrees C. Our objective was to determine whether the temperate species, Chrysemys picta bellii, exhibits greater tolerance to submergence apnea than the tropical species, Pelomedusa subrufa, Elseya novaeguineae, and Emydura subglobosa. Blood was sampled from indwelling arterial catheters for measurements of blood PO2, PCO2, pH, and hematocrit and for plasma concentrations of lactate, glucose, Na+, K+, Cl-, total Ca, and total Mg. The pattern of change was similar in all species: a combined respiratory and metabolic acidosis associated with a marked decrease of blood PO2. The severity of the acidosis developed in the temperate species, however, was significantly less than that of the tropical turtles. Lactate rose significantly and HCO3- fell proportionately in all turtles; changes in other plasma ion concentrations were small but were generally in the directions consistent with compensatory exchanges with other body compartments; i.e., cations (K+, Ca, and Mg increased) and anions (Cl- decreased). The results indicate that hypoxia tolerance is a conserved trait in turtles, even in those that do not experience enforced winter submergence, and that the temperate species may be superior in this capacity because of reduced metabolic rate.

Acid-Base Equilibrium↗
PubMed2006

Prolonged residence of temperate natives in the tropics produces a suppression of sweating.

Tropical natives possess heat tolerance due to the ability to off-load endogenous and exogenous heat efficiently using a minimum amount of sweat. On the other hand, exposure of temperate natives to heat results in exaggerated production of sweat, of which part is lost by dripping and, thus, not available for evaporation. How sweating is modified in natives of temperate climate zones by prolonged residence in the tropics is not well-understood. The aim of this study was to investigate possible changes in the peripheral sweating mechanisms. Sweating responses to iontophoretically applied acetylcholine (ACh) were compared between Japanese subjects having either permanently resided in Japan (Japan resident Japanese, JRJ) or having stayed in the tropics for 2 years or longer (Tropics resident Japanese, TRJ). Quantitative sudomotor axon reflex tests by iontophoresis of ACh (10%, 2 mA for 5 min) were applied to determine directly activated (DIR) and axon reflex-mediated sweating during [AXR(1)] and after [AXR(2)] ACh iontophoresis. The sweat onset time of AXR(1) was 0.6 min shorter in JRJ than in TRJ (P<0.0001), and AXR(1) (P<0.0004), AXR(2) (P<0.0001), and DIR (P<0.0001) sweating responses were larger in JRJ than in TRJ. AXR and DIR sweating volumes (P<0.0001) were negatively correlated, and sweat onset times (P<0.0001) were positively correlated with the duration of residence in the tropics (2 to 13 years). The observed attenuation of sweating in TRJ suggests that temperate natives may acquire heat tolerance with improved sweating economy similar to tropical natives after prolonged residence in the tropics.

Acclimatization↗
PubMed2005

Off-season uptake of nitrogen in temperate heath vegetation.

In this field study we show that temperate coastal heath vegetation has a significant off-season uptake potential for nitrogen, both in the form of ammonium and as glycine, throughout winter. We injected 15N-ammonium and 15N 2x(13C)-glycine into the soil twice during winter and once at spring. The winter temperatures were similar to those of an average winter in the northern temperate region of Europe, with only few days of soil temperatures below zero or above 5 degrees C. The vegetation, consisting of the evergreen dwarf shrub Calluna vulgaris, the deciduous dwarf shrub Salix arenaria, and the graminoids Carex arenaria and Deschampsia flexuosa, showed high root uptake of both forms of nitrogen, both 1 day after labelling and after a month, in species specific temporal patterns. Plant uptake of 13C was not significant, providing no further evidence of intact uptake of glycine. Translocation of the labelled nitrogen to shoots was generally evident after 1 month and increased as spring approached, with different translocation strategies in the three plant functional types. Furthermore, only the graminoids showed shoot growth during winter. Increasing plant nitrogen concentration from fall to spring at temperate heaths may, hence, be due to nitrogen uptake. Our results suggest that the potential for nitrogen uptake in plants at winter is of the same order of magnitude as at summer. Hence, winter nitrogen uptake in ecosystems in the temperate/boreal region should be considered when making annual nitrogen budgets of heath ecosystems, and the view of plant nutrient uptake as low in this climatic region during winter should be revised.

Biological Transport, Active↗
PubMed2000

The importance of phenology for the evaluation of impact of climate change on growth of boreal, temperate and Mediterranean forests ecosystems: an overview.

An overview is presented of the phenological models relevant for boreal coniferous, temperate-zone deciduous and Mediterranean coniferous forest ecosystems. The phenology of the boreal forests is mainly driven by temperature, affecting the timing of the start of the growing season and thereby its duration, and the level of frost hardiness and thereby the reduction of foliage area and photosynthetic capacity by severe frost events. The phenology of temperate-zone forests is also mainly driven by temperature. Since temperate-zone forests are mostly mixed-species deciduous forests, differences in phenological response may affect competition between tree species. The phenology of Mediterranean coniferous forests is mainly driven by water availability, affecting the development of leaf area, rather than the timing of phenological events. These phenological models were subsequently coupled to the process-based forest model FORGRO to evaluate the effect of different climate change scenarios on growth. The results indicate that the phenology of each of the forest types significantly affects the growth response to a given climate change scenario. The absolute responses presented in this study should, however, be used with caution as there are still uncertainties in the phenological models, the growth models, the parameter values obtained and the climate change scenarios used. Future research should attempt to reduce these uncertainties. It is recommended that phenological models that describe the mechanisms by which seasonality in climatic drivers affects the phenological aspects of trees should be developed and carefully tested. Only by using such models may we make an assessment of the impact of climate change on the functioning and productivity of different forest ecosystems.

Climate↗
PubMed2005

The leaf morphologies of the subtropical rheophyte Solenogyne mikadoi and its temperate relative S. bellioides (Asteraceae) are affected differently by plant hormones and their biosynthesis inhibitors.

Solenogyne mikadoi is a subtropical rheophyte endemic to the Ryukyu Archipelago that develops rosette leaves 2-3 cm in diameter. In contrast, the other three species of this genus all occur in temperate grasslands of Australia and develop rosette leaves about 10 cm in diameter. To examine the involvement of the plant hormones gibberellin and brassinosteroid in the adaptive dwarfism of S. mikadoi, we compared the effects of GA(3) and brassinolide, and their biosynthesis inhibitors on the morphology of the first leaves of S. mikadoi and its temperate relative S. bellioides. In S. mikadoi, one-directional (lengthwise) leaf elongation was strongly facilitated by the application of GA(3) and suppressed by a gibberellin-biosynthetic inhibitor, uniconazole-P, while leaf width (transverse) expansion was insensitive to and was never facilitated by any of the compounds used. Conversely, in S. bellioides, brassinolide facilitated both the elongation and expansion of leaves, while a brassinosteroid-specific biosynthesis inhibitor, brassinazole220, suppressed both. One-directional leaf elongation caused by the reduced sensitivity to brassinolide in S. mikadoi and brassinolide-dependent two-dimensional leaf expansion in S. bellioides both appear to be adaptations to their respective habitats: S. mikadoi has narrow leaves resistant to flowing water, whereas S. bellioides has broad leaves capable of harnessing sufficient light and water in temperate grasslands.

Asteraceae↗
PubMed1984

Pyomyositis. Increasing recognition in temperate climates.

Pyomyositis is common in the tropics yet is rarely reported in temperate climates. A woman in whom pyomyositis developed in a temperate climate is presented. Computed tomography was the key in the diagnosis of the disease involving the muscles of the left lateral chest wall. The patient's condition responded to intravenous antibiotics and open abscess drainage. The 31 cases reported in the United States are reviewed. Unfamiliarity still poses a barrier to early diagnosis, although pyomyositis is being more frequently described in temperate climates.

Adult↗
PubMed2004

Mode of locomotion places selective pressures on Antarctic and temperate labriform swimming fish.

The physiological responses to exercise and stress of the Antarctic labriform swimmer Pagothenia borchgrevinki were compared to the temperate labriform swimmers Notolabrus celidotus and Notolabrus fucicola. Basic swimming characteristics were very similar amongst the three species with P. borchgrevinki showing a reduced capacity for exercise. P. borchgrevinki showed large increases in haematocrit (Hct) following exercise that were not seen in the temperate species. Lactate dehydrogenase (LDH) activities were high in the white myotomal muscle from the Antarctic fish, with a distinct indication of metabolic cold adaptation in this enzyme. Nevertheless, although the temperate fish showed elevated muscle lactate concentrations following either exercise or electrical stimulation the Antarctic fish did not. The data suggest that poor anaerobic performance of white muscle is associated with the labriform mode of locomotion.

Animals↗
PubMed2005

Activities of antioxidant enzymes and cytochrome c oxidase in liver of Arctic and temperate teleosts.

Enhanced antioxidant status in polar fishes may occur due to high dissolved oxygen levels and membranes rich in peroxidation-sensitive polyunsaturated fatty acids. To evaluate the importance of antioxidant enzymes in polar fishes, activities of catalase (CAT), superoxide dismutase (SOD), and glutathione reductase (GR), as well as the aerobic enzyme cytochrome c oxidase (CCO), were measured at 6 degrees C and 1 degrees C in livers of confamilial Arctic and temperate teleosts: the Arctic fourhorn sculpin Triglopsis quadricornis (Cottidae) and saddled eelpout Lycodes mucosus (Zoarcidae) vs. the temperate longhorn sculpin (Myoxocephalus octodecimspinosus) (Cottidae) and ocean pout (Zoarces americanus) (Zoarcidae), respectively. At both assay temperatures, CAT activities were substantially lower in both Arctic species, SOD was similar in the cottids but lower in the Arctic zoarcid, and GR was similar in temperate and Arctic fishes. Activities at respective habitat temperatures were always significantly lower in the Arctic fishes. The lower antioxidant enzyme activities in the Arctic fishes cannot be attributed to lower aerobic status because CCO activity was similar or higher in the Arctic fishes; significant negative relationships were found between CCO and CAT and GR (but not SOD) when all species were combined, indicating that a higher apparent aerobic status does not necessarily coincide with higher antioxidant enzyme activities. Antioxidant enzyme activities may not be enhanced as part of cold adaptation in Arctic fishes, at least in the liver.

Acclimatization↗
PubMed2005

Long series relationships between global interannual CO2 increment and climate: evidence for stability and change in role of the tropical and boreal-temperate zones.

Interannual variability in global CO2 increment (averaged from the Mauna Loa and South Pole Stations) shows certain strong spatial relationships to both tropical and temperate temperatures. There is a fairly strong positive year-round correlation between tropical mean annual temperatures (leading by 4 months) and annual CO2 throughout the time series since 1960, agreeing with the generally held view that the tropics play a major role in determining inter-annual variability in CO2 increment, with a major CO2 pulse following a warm year in the tropics. This 'almost no lag' climatic response is very strong during winter and relatively stable in time. However, the correlation with tropical temperature appears to have weakened in the first years of the 1990s in correspondence of the Pinatubo eruption and the positive phase of the AO/NAO. A secondary concurrent temperature signal is linked to summer variations of north temperate belt. Northern summer temperatures in the region 30-60 degrees N-and especially in the land area corresponding to the central east USA-have become relatively more closely correlated with CO2 increment. This trend has become increasingly stronger in recent years, suggesting an increasing role for growing season processes in the northern midlatitudes in affecting global CO2 increment. Once non-lagged annual tropical temperature variations are accounted for, terrestrial ecosystems, especially the temperate-boreal biomes, also show a coherent large scale lagged response. This involves an inverse response to annual temperature of preceding years centered at around 2 years before. This lagged response is most likely linked to internal biogeochemical cycles, in particular N cycling. During the study period north boreal ecosystems show a strengthening of the lagged correlation with temperature in recent years, while the lagged correlation with areas of tropical ecosystems has weakened. Residuals from a multiple correlations based on these climatic signals are directly correlated with SO, confirming an additional important role of upwelling in interannual variability of CO2 increment. Cooler summers following the Pinatubo eruption and the possible influence of the North Atlantic Oscillation (NAO/AO) are discussed as factors responsible for the shift in the relative importance of different regions over time during the series of data.

Atmosphere↗
PubMed2005

Tropical and temperate pyomyositis.

Pyomyositis is a primary infection of skeletal muscle not arising from contiguous infection, presumably hematogenous in origin, and often, but not invariably, associated with abscess formation. Classically, pyomyositis is an infection of the tropics, occurring in previously active and healthy young men. Pyomyositis in temperate countries is often regarded as an infection that occurs in hosts who are immunocompromised or otherwise debilitated. However,this distinction may be somewhat artificial, as tropical pyomyositis may be partly related to underlying infection with HIV or parasites, and temperate pyomyositis has been reported in healthy and athletic persons. This article discusses the pathogenesis, clinical presentation, diagnosis, and management of pyomyositis in the tropical and temperate settings.

AIDS-Related Opportunistic Infections↗
PubMed2005

Differences in egg thermotolerance between tropical and temperate populations of the migratory locust Locusta migratoria (Orthoptera: Acridiidae).

The migratory locust Locusta migratoria L., which is widely distributed throughout the world, exhibits within- and between-population variation in cold tolerance. To understand physiological adaptation in populations, we studied the genetic basis of thermotolerance in Hainan (tropical) and Liaoning (temperate) populations and measured expression of Hsp70 and Hsp90 mRNA in both populations at low (0 degrees C) and high temperatures (40 degrees C). Phenotypic variation of thermotolerance is heritable. Heritable characteristics differed among different stages of locust egg development, as well as among different measures of thermotolerance. Nuclear genetic factors, rather than cytoplasmic factors, contribute to differences in cold tolerance between the tropical and temperate populations of the migratory locust; for heat tolerance, maternal effects were involved in three stages of egg development. Expression of Hsp90 mRNA was induced in temperate population after heat shock (40 degrees C x 12h), whereas expression of Hsp70 and 90 was induced in tropical population after cold shock (0 degrees C x 12h). We suggest that thermotolerance of locust eggs has a complex genetic basis and heat shock proteins may be involved in differences of thermotolerance between locust populations.

Acclimatization↗
PubMed2006

Ultrasonic evaluation of residual stresses in flat glass tempering by an original double interferometric detection.

In industrial thermal tempering of glass, the knowledge of the homogeneity of compressive residual stress field on the glass product is fundamental to guarantee the quality of the tempered glass product. In this paper, we use the acoustoelasticity phenomenon in order to estimate the residual stress distribution by using acoustic surface wave. We present an experimental setup based on a double interferometric detection in which an aspheric lens is associated with a beam splitter and a YAG laser whose power is 100 mW. This relative high power enables us to carry out measurements on surface flat glass although optical reflection coefficient is typically weak (< 10%). Using these two points of detection, the evolution of relative surface wave velocity is obtained with a good accuracy. At last, a comparison between the numerical modeling and experimental results shows the potentiality of an ultrasonic method to estimate stress distribution in flat glass tempering.

Algorithms↗
PubMed2000

Temperature tolerance of the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae) in tropical and temperate regions of Asia.

Temperature tolerance was investigated in nine populations of Plutella xylostella Linnaeus from tropical and temperate regions of Asia. At all rearing temperatures between 15 and 35 degrees C, no clear differences were observed in female egg production or larval development between tropical and temperate populations. Thus, tropical populations did not show a high-temperature tolerance superior to that of the temperate populations. In all populations, the net reproductive rate (number of new females born per female) largely depended on the number of eggs laid per female, and egg production significantly decreased with increasing temperature (P < 0.001). Larval developmental rate also showed a significant positive correlation with temperature (P < 0.001). Per cent hatch of eggs and larval survival did not show a significant correlation with temperature: hatching was constant between 15 and 32.5 degrees C, but considerably lower at 35 degrees C. Larval survival was similar between 15 and 30 degrees C, appreciably lower at 32.5 degrees C and declined to 0% at 35 degrees C. Based on these results, environmental conditions under which P. xylostella can maintain a high population density throughout the year in tropical and subtropical regions are discussed.

Animals↗
PubMed2006

Free-energy landscape for beta hairpin folding from combined parallel tempering and metadynamics.

We develop a new free-energy method, based on the combination of parallel tempering and metadynamics, and apply this method to the calculation of the free-energy landscape of the folding beta hairpin in explicit water. We show that the combined method greatly improves the performance of both parallel tempering and metadynamics. In particular, we are able to sample the high free-energy regions, which are not accessible with conventional parallel tempering. We use our results to calculate the difference in entropy and enthalpy between the folded and the unfolded state and to characterize the most populated configurations in the relevant free-energy basins.

Algorithms↗
PubMedDate not supplied

Evidence of two temperate episodes in late Pleistocene deposits at Marsworth, UK.

In the British Quaternary, two post-Cromerian interglacials, the Hoxnian and the Ipswichian, are recognized. Evidence of additional interglacials in this interval is widely accepted in the oceanic record of Quaternary events, and the possibility that at least one additional interglacial of this age is represented in Britain has been discussed. However, in the absence of datable interglacial deposits which are seen to overlie one another, the issue has remained controversial. We describe here deposits at Marsworth, UK (Fig. 1) where there is evidence of two temperate episodes, and of intervening periglacial conditions. Stratigraphical superposition is established beyond any reasonable doubt. The later deposit relates to the temperate woodland stage of the Ipswichian Interglacial. Dating of the earlier temperate material by the 230Th/234U disequilibrium method indicates an interglacial episode not previously established in the British Quaternary.

Animals↗
PubMed2005

Measurements of biogenic hydrocarbons and carbonyl compounds emitted by trees from temperate warm Atlantic rainforest, Brazil.

This study is part of a three-year project on biogenic volatile organic compound (VOC) emissions from trees of the temperate warm Atlantic rainforest found in the metropolitan area of Sao Paulo City (MASP). No study of VOC emission rates from plant species has been carried out in the temperate warm Atlantic rainforest of Brazil prior to this work. Eleven species were selected (Alchornea sidifolia, Cupania oblongifolia, Cecropia pachystachia, Syagrus romanzoffiana, Casearia sylvestris, Machaerium villosum, Trema micrantha, Croton floribundus, Myrcia rostrata, Solanum erianthum and Ficus insipida) and some of them were studied in urban, sub-urban and forest areas inside the MASP in order to evaluate biogenic VOC composition at sites characterized by different emission sources. Biogenic VOC emissions were determined by placing branches of plants in a dynamic enclosure system, an all-Teflon cuvette, and by sampling the compounds in the air leaving the cuvette. Pre-concentration using adsorbents to retain the VOC, followed by GC-MS after thermal desorption of the sample, was employed to determine the amount of biogenic hydrocarbons. The collection of carbonyl compounds on a 2,4-dinitrophenylhydrazine coated silica followed by HPLC-UV was used to analyze low molecular weight carbonyl compounds. Emission rates of isoprene, alpha-pinene, camphene and limonene ranged from 0.01 to 2.16 microg C h(-1) g(-1) and emission rates of aldehydes (C(2)-C(6)), acrolein, methacrolein and 2-butanone ranged from 1.5 x 10(-2) to 2.3 micro g C h(-1) g (-1). Ambient and leaf temperatures, relative humidity, light intensity, O(3) and NO(x) levels in the local atmosphere were monitored during experiments. It was possible to identify different biogenic VOCs emitted from typical plants of temperate warm Atlantic rainforest. The emission rates were reported as a function of the type of site investigated and were only provided for compounds for which quantification was feasible. Other biogenic compounds were only identified.

Brazil↗
PubMed1999

Climatic influence on mesophilic Bacillus cereus and psychrotolerant Bacillus weihenstephanensis populations in tropical, temperate and alpine soil.

Bacillus weihenstephanensis strains are psychrotolerant and grow from below 7 degrees C to 38 degrees C. Closely related mesophilic Bacillus cereus strains can grow from above 7 degrees C to 46 degrees C. We classified 1060 B. cereus group isolates from different soil samples with respect to their psychrotolerant and mesophilic genotypes by polymerase chain reaction (PCR) targeting of specific 16S rDNA and cold shock protein A gene signatures. In parallel, growth tests at 7 degrees C were carried out to determine the thermal phenotype. The geographic distribution of psychrotolerant and mesophilic isolates was found to depend significantly on the prevalent annual average temperature. In one tropical, one temperate and two alpine habitats, the proportion of psychrotolerant cspA genotypes was found to be 0%, 45% and 86% and 98%, respectively, with the corresponding annual average temperatures being 28 degrees C, 7 degrees C, 4 degrees C and 1 degrees C. In the tropical habitat, only the mesophilic B. cereus was found, characterized by correspondence of thermal genotype and phenotype. In the alpine habitat, almost only the psychrotolerant B. weihenstephanensis was isolated. In the temperate habitat, mesophilic B. cereus and psychrotolerant B. weihenstephanensis as well as 'intermediate thermal types' occurred, the latter having opposite thermal genotypes and phenotypes or opposing sets of thermal DNA signatures, characterized by the coexistence of mesophilic and psychrotolerant 16S rDNA operon copies within a single isolate. Both sugar utilization and DNA fingerprinting patterns revealed a high, probably non-clonal microsite diversity within the population of the temperate habitat. We interpret our observations in terms of a temperature-dependent selection regime, acting on recombining B. cereus/ B. weihenstephanensis populations in soil.

Bacillus↗
PubMed2004

The incomplete beta function law for parallel tempering sampling of classical canonical systems.

We show that the acceptance probability for swaps in the parallel tempering Monte Carlo method for classical canonical systems is given by a universal function that depends on the average statistical fluctuations of the potential and on the ratio of the temperatures. The law, called the incomplete beta function law, is valid in the limit that the two temperatures involved in swaps are close to one another. An empirical version of the law, which involves the heat capacity of the system, is developed and tested on a Lennard-Jones cluster. We argue that the best initial guess for the distribution of intermediate temperatures for parallel tempering is a geometric progression and we also propose a technique for the computation of optimal temperature schedules. Finally, we demonstrate that the swap efficiency of the parallel tempering method for condensed-phase systems decreases naturally to zero at least as fast as the inverse square root of the dimensionality of the physical system.

Journal Article↗