Effect of temperature on a voltage-sensitive electrical synapse in crayfish.

1998 ◽  
Vol 201 (4) ◽  
pp. 503-513 ◽  
Author(s):  
W J Heitler ◽  
D H Edwards
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Input Resistance ◽  
Temperature Limit ◽  
Electrical Synapse ◽  
Membrane Properties ◽  
Effect Of Temperature ◽  
Cold Temperatures ◽  
Q10 Values ◽  
Effective Transmission

The effects of temperature on transmission through the voltage-sensitive giant motor synapse (GMS) were investigated in crayfish both experimentally and in computer simulation. The GMS is part of the fast reflex escape pathway of the crayfish and mediates activation from the lateral giant (LG) command neurone to the motor giant (MoG) flexor motoneurone. The investigation was motivated by an apparent mismatch between the temperature sensitivity of the activation time constant of the GMS, with a Q10 reported to be close to 11, and that of the active membrane properties of LG and MoG, which are thought to have Q10 values close to 3. Our initial hypothesis was that at cold temperatures the very slow activation of the GMS conductance would reduce the effectiveness of transmission compared with higher temperatures. However, the reverse was found to be the case. Effective transmission through the GMS was reliable at low temperatures, but failed at an upper temperature limit that varied between 12 degrees C and 25 degrees C in isolated nerve cord preparations. The upper limit was extended above 30 degrees C in semi-intact preparations where the GMS was less disturbed by dissection. The results of experiments and simulations both indicate that transmission becomes more reliable at low temperatures because the longer-duration presynaptic spikes are able to drive more current through the GMS into the MoG, which is more excitable at low temperatures. Conversely, effective transmission is difficult at high temperatures because the transfer of charge through the GMS is reduced and because the input resistance of MoG is lowered as its current threshold is increased. The effect of the high Q10 of the GMS activation is to help preserve effective transmission through the synapse at high temperatures and so extend the temperature range for effective operation of the escape circuit.

Temperature, Size and Egg Production in the Cabbage Butterfly, Pieris Rapae L.

1982 ◽  
Vol 30 (2) ◽  
pp. 223 ◽  
Author(s):  
RE Jones ◽  
JR Hart ◽  
GD Bull
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Egg Production ◽  
Pieris Rapae ◽  
Effect Of Temperature ◽  
Pupal Weight ◽  
Larval Diet ◽  
Young Females ◽  
Rearing Conditions ◽  
High Degree

Larvae reared at low temperatures produce larger pupae and adults than those reared at high temperatures, and pupal weight is linearly related to lifetime egg production; mean egg production in a group reared at 29-3l�C may be twice that of another reared at 17.5-19�C. The number of eggs visible with a dissecting microscope in the ovaries of young females is not proportional to their lifetime production. Once size is taken into account, there is no additional effect of temperature or larval diet on total egg production. The timing of egg production throughout an adult's life is unaffected by its size or by the conditions in which it was reared. but there are marked differences between Australian and Canadian (Vancouver) individuals. The size of eggs is inversely correlated with both the age and the size of the mother. In any particular set of rearing conditions, males tend to be larger than females, and the sexes show an equal and high degree of variation in size.

A thermal adaptation of bacteria to cold temperatures in an enhanced biological phosphorus removal system

2003 ◽  
Vol 47 (11) ◽  
pp. 123-128 ◽  
Author(s):  
U.G. Erdal ◽  
Z.K. Erdal ◽  
C.W. Randall
Keyword(s):  
Fatty Acid ◽  
Low Temperatures ◽  
Phosphorus Removal ◽  
System Performance ◽  
Effect Of Temperature ◽  
Biological Phosphorus Removal ◽  
Homeoviscous Adaptation ◽  
Cold Temperatures ◽  
Temperature Changes ◽  
Biological Phosphorus

Temperature is one of the key parameters that affects the reaction kinetics and performance of enhanced biological phosphorus removal (EBPR) systems. Although studies agree regarding the effect of temperature on kinetic reaction rates, there are contradictory results in the literature regarding the effect of temperature on EBPR system performance. Early investigators (Sell, Ekama et al., Daigger et al.) reported better performance with lower temperatures, but others have reported partial or complete loss of EBPR functions at low temperatures (McClintock et al., Brdjanovic et al., Beatons et al.). One speculation is that deterioration in the EBPR system performance at cold temperatures can be attributed to rigid-like behavior of the cell membranes. Most cells (not all) on the other hand have the ability to alter their membrane fatty acid composition as temperature changes in order to keep their membrane at nearly the same fluidity despite the temperature changes. This unique ability is known as homeoviscous adaptation. In this study, homeoviscous adaptation by EBPR activated sludge was investigated for a series of temperatures ranging from 20°C to 5°C using a lab scale continuous flow EBPR system fed with acetate and supplemental yeast extract. The fatty acid analysis results suggested that the unsaturated to saturated fatty acid ratio increased from 1.40 to 3.61 as temperature dropped from 20 to 5°C. The increased cis-9-hexadecanoic acid (C16:1) at 5°C strongly indicated the presence of homeoviscous adaptation in the EBPR bacterial community. Thus the cell membranes of the EBPR community were still in a fluid state, and solute transport and proton motive force were operable even at 5°C. It was concluded that loss of EBPR performance at low temperatures is not related to the physical state of the cellular membranes, but is possibly related to the application of unsuitable operational conditions (low SRT, excessive electron acceptors, low anaerobic detention time, non-acclimated sludge, etc.).

The effect of temperature upon the hatching of the eggs of Pediculus humanus corporis de Geer (Anoplura)

Parasitology ◽  
1941 ◽  
Vol 33 (2) ◽  
pp. 243-249 ◽  
Author(s):  
H. S. Leeson
Keyword(s):  
Incubation Period ◽  
High Temperatures ◽  
Constant Temperature ◽  
Low Temperatures ◽  
Effect Of Temperature ◽  
Pediculus Humanus ◽  
Short Time

The hatching of the eggs of Pediculus humanus corporis De Geer is influenced by temperature.High temperatures accelerate and low temperatures delay development.The lowest constant temperature at which eggs will hatch is 24° and the highest 37°.At 24° eggs begin to hatch on the seventeenth day and continue hatching until the twenty-first. At 37° eggs hatch on the sixth and seventh days. The temperature at which eggs hatch in the shortest time is 35° and the time 5 days. At these extremes many eggs are killed so that the percentages of successful hatches are very low. Eggs are killed by 2 days' exposure to 39°.Temperatures at which the maximum number of eggs hatch he between 29 and 32°. In this range of “favourable” temperatures, up to 97% of successful hatches may be recorded. The incubation period is from 7 to 11 days. This is a convenient range of temperatures for laboratory purposes and gives largest numbers in a reasonably short time.Newly deposited eggs will not hatch if kept for 14 days at 23° or for shorter periods at lower temperatures, until at 8° exposure for 7 days is sufficient to ensure that all eggs are dead.If partially developed eggs are exposed to temperatures of 15° or lower, development ceases. If they are restored to a favourable temperature within 7 days, development is resumed and some of the eggs will hatch.Older eggs which have almost reached hatching point at a “favourable” temperature hatch if transferred to temperatures as low as 18°. They do not hatch at 15° or lower if kept at such temperatures for at least 9 days.

Effect of temperature and inoculum size on reproduction and development of Heterorhabditis heliothidis and Steinernema glaseri (Nematoda: Rhabditoidea) in Galleria mellonella

1991 ◽  
Vol 69 (5) ◽  
pp. 1261-1264 ◽  
Author(s):  
S. Zervos ◽  
S. C. Johnson ◽  
J. M. Webster
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Development Time ◽  
Galleria Mellonella ◽  
Inoculum Size ◽  
Effect Of Temperature ◽  
Inoculum Level ◽  
Steinernema Glaseri

Larvae of Galleria mellonella were kept at temperatures of 5, 10, 15, 20, 25, and 30 °C, and exposed to six levels of inocula (5, 10, 25, 50, 100, and 500 infective juveniles/larva) of Heterorhabditis heliothidis and Steinernema glaseri. Temperature and inoculum level significantly affected time to first emergence, duration of emergence, and yield of juveniles. All parameters except emergence of H. heliothidis showed significant interactions between temperature and inoculum level. No juveniles emerged at 5 or 10 °C and development time was most rapid at 25 °C. No juvenile H. heliothidis emerged at 30 °C or with 500 infective juveniles/host, but duration of emergence was shortest at high temperatures with large inocula; yield per host and yield per inoculum were greatest at 20 °C with small inocula. Yields of S. glaseri were half those of H. heliothidis; duration of emergence was shortest at low temperatures; yield per host was greatest at 20 and 25 °C from large inocula; and yield per inoculum level was greatest when the numbers inoculated were small (5–50/host).

The impact of variations in temperature on early Plasmodium falciparum development in Anopheles stephensi

Parasitology ◽  
1995 ◽  
Vol 111 (5) ◽  
pp. 539-545 ◽  
Author(s):  
B. H. Noden ◽  
M. D. Kent ◽  
J. C. Beier
Keyword(s):  
Plasmodium Falciparum ◽  
High Temperatures ◽  
Low Temperatures ◽  
Anopheles Stephensi ◽  
Development Stage ◽  
Effect Of Temperature ◽  
Infection Rates ◽  
Developmental Processes ◽  
The Impact ◽  
Kinetics Of

SUMMARYThe effect of temperature on early Plasmodium falciparum development was examined in Anopheles stephensi. The rates of both ookinete development and bloodmeal digestion were lengthened as temperatures decreased from 27 to 21 °. However, low temperatures (21–27 °) did not significantly influence infection rates or densities of either ookinetes or oocysts. In contrast, high temperatures (30 and 32 °) significantly impacted parasite densities and infection rates by interfering with developmental processes occurring between parasite fertilization and ookinete formation, especially during zygote and early ookinete maturation. This study demonstrates clearly that temperature affects the sporogonic development of P. falciparum in anophelines by altering the kinetics of ookinete maturation. These studies not only confirm the ookinete as the key development stage affecting the probability of vector infectivity, they provide new insights into the epidemiology of P. falciparum infections.

scholarly journals Brassinosteroids and the Tolerance of Cereals to Low and High Temperature Stress: Photosynthesis and the Physicochemical Properties of Cell Membranes

2021 ◽  
Vol 23 (1) ◽  
pp. 342
Author(s):  
Iwona Sadura ◽  
Anna Janeczko
Keyword(s):  
High Temperature ◽  
Temperature Stress ◽  
High Temperatures ◽  
Low Temperatures ◽  
Sugar Content ◽  
Frost Tolerance ◽  
Plant Production ◽  
Membrane Properties ◽  
Winter Rye ◽  
The Impact

Cereals, which belong to the Poaceae family, are the most economically important group of plants. Among abiotic stresses, temperature stresses are a serious and at the same time unpredictable problem for plant production. Both frost (in the case of winter cereals) and high temperatures in summer (especially combined with a water deficit in the soil) can result in significant yield losses. Plants have developed various adaptive mechanisms that have enabled them to survive periods of extreme temperatures. The processes of acclimation to low and high temperatures are controlled, among others, by phytohormones. The current review is devoted to the role of brassinosteroids (BR) in cereal acclimation to temperature stress with special attention being paid to the impact of BR on photosynthesis and the membrane properties. In cereals, the exogenous application of BR increases frost tolerance (winter rye, winter wheat), tolerance to cold (maize) and tolerance to a high temperature (rice). Disturbances in BR biosynthesis and signaling are accompanied by a decrease in frost tolerance but unexpectedly an improvement of tolerance to high temperature (barley). BR exogenous treatment increases the efficiency of the photosynthetic light reactions under various temperature conditions (winter rye, barley, rice), but interestingly, BR mutants with disturbances in BR biosynthesis are also characterized by an increased efficiency of PSII (barley). BR regulate the sugar metabolism including an increase in the sugar content, which is of key importance for acclimation, especially to low temperatures (winter rye, barley, maize). BR either participate in the temperature-dependent regulation of fatty acid biosynthesis or control the processes that are responsible for the transport or incorporation of the fatty acids into the membranes, which influences membrane fluidity (and subsequently the tolerance to high/low temperatures) (barley). BR may be one of the players, along with gibberellins or ABA, in acquiring tolerance to temperature stress in cereals (particularly important for the acclimation of cereals to low temperature).

scholarly journals Ecological implications of metabolic compensation at low temperatures in salamanders

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2072 ◽  
Author(s):  
Alessandro Catenazzi
Keyword(s):  
Heart Rate ◽  
Metabolic Rate ◽  
High Temperatures ◽  
Low Temperatures ◽  
Behavioral Activity ◽  
Compensatory Mechanism ◽  
Resting Heart Rate ◽  
Cold Temperatures ◽  
Metabolic Compensation ◽  
Ecological Implications

Global warming is influencing the biology of the world’s biota. Temperature increases are occurring at a faster pace than that experienced by organisms in their evolutionary histories, limiting the organisms’ response to new conditions. Mechanistic models that include physiological traits can help predict species’ responses to warming. Changes in metabolism at high temperatures are often examined; yet many species are behaviorally shielded from high temperatures. Salamanders generally favor cold temperatures and are one of few groups of metazoans to be most species-rich in temperate regions. I examined variation in body temperature, behavioral activity, and temperature dependence of resting heart rate, used as a proxy for standard metabolic rate, in fire salamanders (Salamandra salamandra). Over 26 years, I found that salamanders are behaviorally active at temperatures as low as 1 °C, and aestivate at temperatures above 16 °C. Infrared thermography indicates limited thermoregulation opportunities for these nocturnal amphibians. Temperature affects resting heart rate, causing metabolic depression above 11 °C, and metabolic compensation below 8 °C: heart rate at 3 °C is 224% the expected heart rate. Thus, salamanders operating at low temperatures during periods of peak behavioral activity are able to maintain a higher metabolic rate than the rate expected in absence of compensation. This compensatory mechanism has important ecological implications, because it increases estimated seasonal heart rates. Increased heart rate, and thus metabolism, will require higher caloric intake for field-active salamanders. Thus, it is important to consider a species performance breadth over the entire temperature range, and particularly low temperatures that are ecologically relevant for cold tolerant species such as salamanders.

Low solubility of alumina in enstatite and uncertainties in estimated palaeogeotherms

1978 ◽  
Vol 288 (1355) ◽  
pp. 471-486 ◽  
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Alumina Content ◽  
Equilibrium Solubility ◽  
Low Solubility

Spurious kinks in estimated palaeogeotherms may result from small errors in the calibration of the geothermometers and geobarometers. New data indicate that the equilibrium solubility of alumina in enstatite is even less than shown by recent studies, and that the slopes (d T /d P ) of the isopleths of equal alumina content are steeper than hitherto believed. Consequently, pressures of equilibration estimated from current formulations of the orthopyroxene-garnet geobarometer will be too high at high temperatures (> 1200 °C) and too low at low temperatures.

scholarly journals Effect of extreme cold temperatures on quasi-static indentation and impact behavior of woven carbon fiber epoxy composite sandwich panels with nomex honeycomb core

2021 ◽  
pp. 109963622199387
Author(s):  
Mathilde Jean-St-Laurent ◽  
Marie-Laure Dano ◽  
Marie-Josée Potvin
Keyword(s):  
Epoxy Composite ◽  
Impact Behavior ◽  
Effect Of Temperature ◽  
Cold Temperatures ◽  
Composite Sandwich Panels ◽  
Composite Sandwich ◽  
Static Indentation ◽  
Nomex Honeycomb ◽  
Extreme Cold ◽  
The Impact

The effect of extreme cold temperatures on the quasi-static indentation and the low velocity impact behavior of woven carbon/epoxy composite sandwich panels with Nomex honeycomb core was investigated. Impact tests were performed at room temperature, –70°C, and –150°C. Two sizes of hemispherical impactor were used combined to three different impactor masses. All the impact tests were performed at the same initial impact velocity. The effect of temperature on the impact behavior is investigated by studying the load history, load-displacement curves and transmitted energy as a function of time curves. Impact damage induced at various temperatures was studied using different non-destructive and destructive techniques. Globally, more damages are induced with impact temperature decreasing. The results also show that the effect of temperature on the impact behavior is function of the impactor size.

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