Warm brain and eye temperatures in sharks

Temperatures in the brain and eyes of mako and porbeagle sharks (Lamnidae) are 5 degrees C warmer than the water while the brain and eye temperatures in six other species of pelagic sharks are within 0.1 degrees C of water temperature. An orbital rete mirabile is present in the porbeagle and mako sharks but absent in the cranial vasculature of eleven other species of pelagic sharks. The orbital rete in the head of the porbeagle and mako sharks acts as a heat exchanger which conserves metabolic heat and raises the local tissue temperatures. This brain and eye warming system should buffer the central nervous system from the effects of rapid temperature change. Warming of the retina may improve the visual sensitivity of these active predators.     

Warm water temperatures and shifts in seasonality increase trout recruitment but only moderately decrease adult size in western North American tailwaters

Dams throughout western North America have altered thermal regimes in rivers, creating cold, clear “tailwaters” in which trout populations thrive. Ongoing drought in the region has led to highly publicized reductions in reservoir storage and raised concerns about potential reductions in downstream flows. Large changes in riverine thermal regimes may also occur as reservoir water levels drop, yet this potential impact has received far less attention. We analyzed historic water temperature and fish population data to anticipate how trout may respond to future changes in the magnitude and seasonality of river temperatures. We found that summer temperatures were inversely related to reservoir water level, with warm temperatures associated with reduced storage and with dams operated as run-of-river units. Variation in rainbow trout (Oncorhynchus mykiss) recruitment was linked to water temperature variation, with a 5-fold increase in recruitment occurring at peak summer temperatures (18 °C vs. 7 °C) and a 2.5-fold increase in recruitment when peak temperatures occurred in summer rather than fall. Conversely, adult trout size was only moderately related to temperature. Rainbow and brown trout (Salmo trutta) size decreased by ~24 mm and 20 mm, respectively, as mean annual and peak summer temperatures increased. Further, rainbow trout size decreased by ~29 mm with an earlier onset of cold winter temperatures. While increased recruitment may be the more likely outcome of a warmer and drier climate, density-dependent growth constraints could exacerbate temperature-dependent growth reductions. As such, managers may consider implementing flows to reduce recruitment or altering infrastructure to maintain coldwater reservoir releases.     

Warm temperatures activate TRPV4 in mouse 308 keratinocytes

Mammalian survival requires constant monitoring of environmental and body temperature. Recently, several members of the transient receptor potential vanilloid (TRPV) subfamily of ion channels have been identified that can be gated by increases in temperature into the warm (TRPV3 and TRPV4) or painfully hot (TRPV1 and TRPV2) range. In rodents, TRPV3 and TRPV4 proteins have not been detected in sensory neurons but are highly expressed in skin epidermal keratinocytes. Here, we show that in response to warm temperatures (>32 degrees C), the mouse 308 keratinocyte cell line exhibits nonselective transmembrane cationic currents and Ca2+ influx. Both TRPV3 and TRPV4 are expressed in 308 cells. However, the warmth-evoked responses we observe most closely resemble those mediated by recombinant TRPV4 on the basis of their electrophysiological properties and sensitivity to osmolarity and the phorbol ester, 4alpha-phorbol-12,13-didecanoate. Together, these data support the notion that keratinocytes are capable of detecting modest temperature elevations, strongly suggest that TRPV4 participates in these responses, and define a system for the cell biological analysis of warmth transduction.     

Decreased growth temperature increases soybean stearoyl-acyl carrier protein desaturase activity

Developing soybean (Glycine max) seeds respond to a change in growth temperature by changing the level of stearoyl acyl carrier protein desaturase activity in the tissue. After 20 hours in liquid culture, seeds grown at 20°C show an increase in activity while seeds grown at 35°C show a decrease in activity, relative to their preculture levels. Analysis of the enzyme from both growth conditions shows the change not to be due to induction of kinetically distinct iosenzymes; desaturase activities from both 20°C and 35°C have identical behavior with regard to pH, temperature optimum, substrate concentration and cofactor requirements. Experiments with boiled extracts indicate that the modulation is not caused by induction of metabolic effectors. From these data, it appears that stearoyl-acyl carrier protein desaturase responds to changes in growth temperature by altering the level of active enzyme present in the tissue. The magnitude of this response is a function of the developmental stage of the seed and not a function of the growth conditions of the parent plant. Changing the age of the seeds from early late R5 changed the ratio of 20:35°C activity from 3.8:1 to 1.2:1. Changing the temperature at which the parent plants were grown over a range from 20/12°C to 34/28°C (day/night) produced only minor, and inconsistent, changes in the ratio of 20:35°C activities.     

Nerve growth factor-induced decrease in the calpain activity of PC12 cells

PC12 cells are a nerve growth factor-responsive clone derived from a rat pheochromocytoma. Treatment with nerve growth factor causes the cells to differentiate. One of the hallmarks of this differentiation is the generation of neurites. PC12 cells contain both calpain I and calpain II; about 90% of the total calpain activity is due to calpain II. Treatment of the cells with nerve growth factor causes a time-dependent decrease in calpain activity, more than 50% being lost over a 5-day period. Both the decrease in calpain activity and the growth of neurites are reversible upon the removal of nerve growth factor from the cultures. Agents other than nerve growth factor that cause neurite outgrowth, such as fibroblast growth factor and dibutyryl cyclic AMP, also cause a decrease in calpain activity. Calpain levels, as detected with immunoblotting or immunohistochemistry, show no decrease. Removal of calpastatin, the endogenous inhibitor of the calpains, by phenyl-Sepharose chromatography increases the calpain activity of extracts from both control and nerve growth factor-treated cells and brings the activity in the extracts from treated cells up to the activity in those from controls. Calpastatin-containing fractions from extracts of nerve growth factor-treated cells inhibit more calpain activity than do comparable fractions from control cells. These studies suggest that nerve growth factor causes a decrease in the activity of calpain in morphologically differentiating PC12 cells by causing an increase in the activity of calpastatin.     

Effects of aging on cholinephosphotransferase activity on guinea pig lung mitochondria and microsomes

It is known that the composition of phospholipids in lung changes with age. The final step in thede novo synthesis of phosphatidylcholine, a major component of lung surfactant, by the CDP-choline pathway, requires the enzyme cholinephosphotransferase (CPT). Even though CPT has earlier been proposed to be located exclusively in the endoplasmic reticulum, we have recently demonstrated its presence also in the mitochondria. We have earlier reported a gestational variation of CPT activity in fetal mitochondria and microsomes. In the present study we examined the subcellular distribution of CPT activity in lung as a function of age. After birth, the microsomal CPT activity continued to increase until adulthood (24 wks of age), thereafter it gradually decreased. On the otherhand, the CPT activity of mitochondria continued to increase with the advancement of age and beyond 72 wks of age, it was approximately 2-fold higher than that of the microsomal fraction.     

Localization of an alkyl-acetyl-glycerol-CDP-choline: cholinephosphotransferase activity in submitochondrial fractions of Tetrahymena pyriformis

Tetrahymena pyriformis contains platelet-activating factor (PAF) as a minor lipid, which is biosynthesized de novo. A dithiothreitol-insensitive CDP-choline:cholinephosphotransferase (AAG-CPT), which utilizes alkyl-acetyl-glycerol as a substrate, had been detected in both the mitochondrial and microsomal fractions of the protozoan. In the present report, localization of this enzyme in submitochondrial fractions was studied. Cell fractionation was evaluated with enzyme and morphological markers. In this respect, succinate dehydrogenase, NADPH:cytochrome c reductase, glucose-6-phosphatase, alkaline phosphatase, monoaminoxidase, and cytochrome c oxidase activities were investigated. In the presence of antimycin A, mitochondrial activity of NADPH-cytochrome c reductase, was increased, while the microsomal one was reduced. Cardiolipin was distributed in the inner mitochondrial membrane. Alkaline phosphatase was found exclusively in the cytosol of the protozoan. The main portion of the dithiothreitol-insensitive AAG-CPT was localized in the inner mitochondrial membrane. Our data indicate that mitochondria are able to produce PAF, which might be associated with their function.     

Influence of different soil temperatures on water use,growth and internal water status of soybean

Studies on the effect of soil temperature on internal water relations of well watered soybean (Glycine max L.) at constant air temperature under controlled conditions were carried out. A specially designed thermogradient tank was used for obtaining a range of soil temperatures. Data on shoot height, shoot weight, root length, root weight, leaf area and leaf water potential were obtained at 41 days after sowing and the highest values of these parameters were recorded at 28.6°C. The air temperature during the course of these investigations was 25±1°C and it may be concluded that slightly warmer soil temperatures than air temperatures were optimal for soybean with regard to the above measured parameters.     

Effects of phosphorus and iron fertilizers on the growth of two soybean varieties at two soil temperatures

The influence of FeEDDHA (0, 0.2 and 2 μg Fe g⁻¹ soil) and NaH₂PO₄·H₂O (0 and 120 μg Pg⁻¹ soil) on the growth of two Fe-ineffective soybean (Glycine max L. Merr.) varieties (anoka and T203) on a calcareous soil at two soil temperatures (16 and 24°C) was compared under greenhouse conditions. The two soybean varieties differed in the following respects: (a) T203 accumulated smaller concentrations of Fe in washed tops than Anoka under comparable conditions; (b) T203 was more susceptible to Fe deficiency and its accentuation by high levels of fertilizer P than Anoka; (c) T203 accumulated lower quantities of Mn in tops than Anoka under comparable conditions; (d) T203, but not Anoka, developed Mn deficiency symptoms when treated with P and 2 μg Fe g⁻¹ at 16°C. Fe deficiency was more severe in both varieties at the higher soil temperature due apparently to: (a) greater plant concentration of P in tops at 24°C; and/or (b) an increased rate of plant growth and greater dilution of Fe in young tissue at 24°C. Foliar P concentration was increased much more than foliar Fe concentration by an increase in soil temperature. Severely Fe deficient T203 plants grown without FeEDDHA at 24°C accumulated less foliar Mn than their FeEDDHA counterparts. Comparisons of Fe effectiveness of various soybean cultivars based on relative responses to FeEDDHA can be influenced by differential effects on Mn nutrition.     

Quick and reversible inhibition of soybean root nodule growth by nitrate involves a decrease in sucrose supply to nodules

The upper part of a nodulated soybean root hydroponically cultured in a glass bottle was monitored using a computer microscope under controlled environmental conditions, and the diameter of individual nodules was measured from 10-24 d after planting. The diameter of a root nodule attached to the primary root increased from 1 mm to 6 mm for 2 weeks under nitrogen-free conditions. The increase in diameter of the nodules was almost completely stopped after 1 d of supplying 5 mM nitrate, and was due to the cessation of nodule cell expansion. However, nodule growth quickly returned to the normal growth rate following withdrawal of nitrate from the solution. The reversible depression of nodule growth by nitrate was similar to the restriction of photoassimilate supply by continuous dark treatment for 2 d followed by normal light/dark conditions. In addition, the inhibitory effect of nitrate was partially alleviated by the addition of 3% (w/v) sucrose to the medium. Plant leaves were exposed to (11)C or (14)C-labelled carbon dioxide to investigate the effects of 5 mM nitrate on the translocation and distribution of photosynthates to nodules and roots. Supplying 5 mM nitrate stimulated the translocation rate and the distribution of labelled C in nitrate-fed parts of the roots. However, the (14)C partitioning to nodules decreased from 9% to 4% of total (14)C under conditions of 5 mM nitrate supply. These results indicate that the decrease in photoassimilate supply to nodules may be involved in the quick and reversible nitrate inhibition of soybean nodule growth.     

Suboptimal growth temperatures enhance the biological activity of cultured cyanobacterium Gloeocapsa sp.

The cytotoxic, antibacterial, and antifungal activities of cyanobacterium Gloeocapsa sp. strain Gacheva 2007/R-06/1 were investigated and the possibility for an enhancement of these activities by changing the culture conditions evaluated. Fatty acids of this cyanobacterium were found to be active against Streptococcus pyogenes. Exopolysaccharides inhibited the growth of both Gram-positive and Gram-negative bacteria and the fungus Candida albicans. Both exopolysaccharides and fatty acid mixtures also significantly decreased the viability of human cervical carcinoma cells, HeLa. Greater biological activities were exhibited by Gloeocapsa sp., cultured at suboptimal temperatures (15–26°C) than at optimal and supraoptimal ones. In comparison with higher light intensity, the low-light cultivation stimulated the cytotoxicity of the fatty acids. In general, low temperatures decreased the growth of Gloeocapsa sp., but promoted its biological activity. Prolonged cultivation also had a beneficial impact on the bioactivity. Compared to 4 days, the 17-day cultivation resulted in fourfold higher antibacterial and antifungal activities of exopolysaccharides and more than twice increases in their cytotoxicity. The study revealed that this cyanobacterial isolate is a new source of natural products with potential for pharmacological and medical applications.     

The effects of dopamine on root growth and enzyme activity in soybean seedlings

In the present study, we investigated the effects of dopamine, an allelochemical exuded from the velvetbean (Mucuna pruriens L DC. var utilis), on the growth and cell viability of soybean (Glycine max L. Merrill) roots. We analyzed the effects of dopamine on superoxide dismutase, phenylalanine ammonia-lyase and cell wall-bound peroxidase activities as well as its effects on lignin contents in the roots. Three-day-old seedlings were cultivated in half-strength Hoagland nutrient solution (pH 6.0), without or with 0.25 to 1.0 mM dopamine, in a growth chamber (25°C, 12L:12D photoperiod, irradiance of 280 μmol m⁻² s⁻¹) for 24 h. In general, the length, fresh weight and dry weight of roots, cell viability, PAL and POD activities decreased, while SOD activities increased after dopamine treatment. The content of lignin was not altered. The data demonstrate the susceptibility of soybean to dopamine and reinforce the role of this catecholamine as a strong allelochemical. The results also suggest that dopamine-induced inhibition in soybean roots is not related to the production of lignin, but may be related to damage caused by reactive oxygen species.     

Warm spring temperatures induce persistent season-long changes in shoot development in grapevines

Background and Aims

The influence of temperature on the timing of budbreak in woody perennials is well known, but its effect on subsequent shoot growth and architecture has received little attention because it is understood that growth is determined by current temperature. Seasonal shoot development of grapevines (Vitis vinifera) was evaluated following differences in temperature near budbreak while minimizing the effects of other microclimatic variables.

Methods

Dormant buds and emerging shoots of field-grown grapevines were heated above or cooled below the temperature of ambient buds from before budbreak until individual flowers were visible on inflorescences, at which stage the shoots had four to eight unfolded leaves. Multiple treatments were imposed randomly on individual plants and replicated across plants. Shoot growth and development were monitored during two growing seasons.

Key Results

Higher bud temperatures advanced the date of budbreak and accelerated shoot growth and leaf area development. Differences were due to higher rates of shoot elongation, leaf appearance, leaf-area expansion and axillary-bud outgrowth. Although shoots arising from heated buds grew most vigorously, apical dominance in these shoots was reduced, as their axillary buds broke earlier and gave rise to more vigorous lateral shoots. In contrast, axillary-bud outgrowth was minimal on the slow-growing shoots emerging from buds cooled below ambient. Variation in shoot development persisted or increased during the growing season, well after temperature treatments were terminated and despite an imposed soil water deficit.

Conclusions

The data indicate that bud-level differences in budbreak temperature may lead to marked differences in shoot growth, shoot architecture and leaf-area development that are maintained or amplified during the growing season. Although growth rates commonly are understood to reflect current temperatures, these results demonstrate a persistent effect of early-season temperatures, which should be considered in future growth models.     

Increases in summer temperatures decrease the survival of an invasive forest insect

Higher temperatures projected under current climate change models are generally predicted to exert an overall positive effect on the success of invasive insects through increased survivability, developmental rates and fecundity, and by facilitating geographic range expansion. However, these effects have primarily focused on the shifts in winter temperatures with limited attention to the role that summer heat may play in shaping species ranges or fitness. We examined the thermal ecology of an ecologically important invasive forest insect, the hemlock woolly adelgid (Adelges tsugae), by determining survival during its summer dormancy phase under increasing temperature regimens. From laboratory and field experiments, we documented a positive association between increased temperatures and duration of exposure, and A. tsugae mortality. Adelges tsugae mortality was minimal (<20%) when exposed to summer temperatures characteristic to its native range (<25 °C), but markedly increased (up to 100%) when exposed to temperatures that occur occasionally or rarely in natural settings (>30 °C). At the warmest, southernmost edge of their range, field mortality of A. tsugae ranged from 8.5 to 81.9% and was strongly correlated with site temperature regimens. Further, we found no significant differences in A. tsugae survival between populations collected from Maine and Georgia, and over a 3-year period within Georgia, indicating that A. tsugae may not be acclimating to heat. These results highlight the importance of including summer temperatures in studies regarding increased temperatures on insect dynamics, and may alter historical predictions of climate change impacts on invasive insects and the conservation of forest ecosystems.     

The effects of l-DOPA on root growth, lignification and enzyme activity in soybean seedlings

In the present study, we investigated the effects of l-DOPA (l-3,4-dihydroxyphenylalanine), an allelochemical exuded from the velvetbean (Mucuna pruriens L DC. var. utilis), on the growth and cell viability of soybean (Glycine max L. Merrill) roots. We analyzed the effects of l-DOPA on phenylalanine ammonia lyase (PAL), cinnamyl-alcohol dehydrogenase (CAD) and cell wall-bound peroxidase (POD) activities as well as its effects on phenylalanine, tyrosine and lignin contents in the roots. 3-day-old seedlings were cultivated in half-strength Hoagland nutrient solution (pH 6.0), with or without 0.5?mM l-DOPA, in a growth chamber at 25?°C for 6, 12, 18 or 24?h with a day/night regime of 1:1, and a photon flux density of 280???mol?m^?2 s^?1. In general, the length, fresh weight and dry weight of the roots decreased followed by a significant loss of cell viability. Phenylalanine, tyrosine and lignin contents as well as PAL, CAD and cell wall-bound POD activities increased after l-DOPA treatment. These results reinforce the susceptibility of soybean to l-DOPA, which increases the enzyme activity in the phenylpropanoid pathway and, therefore, provides precursors for the polymerization of lignin. In brief, these findings suggest that the inhibition of soybean root growth induced by exogenously applied l-DOPA may be due to excessive production of lignin in the cell wall.     

Active plant growth at freezing temperatures

As a foundation for speculations in exobiology, we are attempting to understand plant responses to extreme environments on Earth. We have emphasized active plant growth at low temperatures and in response to ultraviolet light. We have studied the winter environment in the mountains near Logan, Utah and have found several plants that grow under the snow. We have measured chlorophyll synthesis, carbohydrate levels, and ion balances in these plants and established field experiments with hardy and nonhardy varieties of wheat. In the laboratory we have studied characteristics of three enzymes in two wheat varieties, finding a number of interesting differences in response to ultraviolet and low-temperature treatments. We have also examined cell ultrastructures of three grass species subjected to a range of temperatures. Chloroplasts were most affected at low temperatures, but other organelles were also influenced. Studies of ion balances substantiate the suggestion from ultrastructure work that membranes may exhibit the primary responses to low temperatures. Cytokinins are also implicated in the cold response. We are presently emphasizing the investigation of membranes. Lunar Science Institute Contribution.     

Experimental and theoretical analyses of nano-silver for antibacterial activity based on differential crystal growth temperatures

The modulation of antimicrobial properties of nanomaterials can be achieved through various physical and chemical processes, which ultimately affect subsequent properties. In this study, the antibacterial potential of nano-silver was investigated at 0.5, 1.0, 2.0, and 3.0 g/L, and its differential temperature synthesis was achieved at 20, 50, and 70 °C using the solvent evaporation method. Nano-silver particles exhibited FCC (octahedral) crystalline structure with crystallite sizes ranging between 28 and 39 nm calculated using XRD analysis. Moreover, irregular and non-uniform surface morphology was evident from SEM micrographs. The UV–Vis absorbance spectrum of nano-silver exhibited wave maxima at 433 nm, while the FTIR analysis depicted different modes of vibration indicating the CH, OH, C≡C, C-Cl, and CH₂ functional groups attached to the surface. Lastly, nano-silver caused prominent inhibition (12.5 mm) in the Escherichia coli growth, particularly at 70 °C synthesis temperature and 3.0 g/L dose. It is concluded that both the nano-silver crystal growth temperature and dose contributed substantially to bacterial growth inhibition linked with subsequent size, shape-dependent properties.     

Warm developmental temperatures induce non-adaptive plasticity in the intrasexually selected colouration of a dragonfly

1. When the breeding environment fluctuates across generations, reproductive traits may evolve plasticity that optimises the balance between survival and mating success for the prevailing environment. 2. For sexually selected colouration, this balance can depend on environmental temperatures. Accordingly, breeding colouration often co-varies with temperature through space and time. However, whether such traits exhibit plasticity in response to environmental temperatures is poorly understood. 3. In the present study, a dragonfly (Pachydiplax longipennis) was reared under ambient or experimentally warmed conditions and tested for plasticity in its intrasexually selected wing colouration. Although wing colouration improves male territorial success, these advantages are smaller under warmer conditions than cooler conditions. It was therefore predicted that males reared under the ambient thermal conditions of the study site (Cleveland, Ohio) would develop more wing colouration than those reared under experimentally warmed conditions. 4. Contrary to this prediction, males reared in warm larval temperatures produced more wing colouration. Thus, although the secondary sexual colouration of this species displays some thermal plasticity, it does not appear to be adaptive relative to the known thermal variation of intrasexual selection in this population. 5. Given that the environment often determines the strength and direction of sexual selection, future studies should consider the potential for non-adaptive, and even maladaptive, developmental plasticity in the sexually selected traits of insects.