The influence of temperature on the post-diapausal development and survival in the aestivating eggs of Halotydeus destructor (Acari : Eupodidae)

1970 ◽  
Vol 18 (3) ◽  
pp. 315 ◽  
Author(s):  
MMH Wallace

After diapause development is complete, moistened aestivating eggs of H. destructor develop successfully within the temperature range 5-20.5C. The rate of development up to the deutovum stage increases with temperature up to about 20C and then rapidly decreases. Eggs will tolerate temperatures between 25 and 31.5C for up to 53 days without undergoing morphogenesis, but this treatment retards subsequent development at 16C. Exposure to alternating temperatures accelerates the rate of development but, if the higher temperature exceeds 20.5C, development is retarded. The effect of temperature on the rate of development within the deutovum stage is similar to that on non-diapause winter eggs throughout their morphogenesis. Air-dry eggs will tolerate temperatures up to 75C but moist eggs are killed by exposure for 1 day to 45C. This high temperature tolerance, together with the limitations on development imposed by temperature, ensures that the aestivating eggs do not hatch before early autumn, even in the event of unseasonal summer rain. The temperature response curve and its ecological significance are discussed briefly.

In muscular contraction the development of tension requires that the contractile component should shorten and stretch the series elastic component. In an isometric twitch the maximum tension is reached as a balance between two opposing processes, internal shortening on the one hand and decay of the active state (relaxation) on the other. The fact that the maximum tension in a twitch is considerably less than in a tetanus has been attributed to oncoming relaxation allowing insufficient time for internal shortening to be completed. The maximum tension in a twitch is considerably reduced by a rise of temperature, while that in a tetanus is somewhat increased. This would require that the temperature coefficient of the velocity of shortening should be substantially less than that of the decay of activity. Evidence for this exists. On this view the effect of a quick stretch, applied during the early stage of a twitch, in increasing the tension ratio, stretch/isometric, should be much greater at a higher temperature. This expectation is confirmed on frogs’ muscles over the range 0 to 20°C. The effect of temperature, therefore, on the size of a twitch can be attributed to the difference between the temperature coefficients of velocity of shortening and rate of relaxation.


Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 112
Author(s):  
Kambham Raja Reddy ◽  
Akanksha Seghal ◽  
Salah Jumaa ◽  
Raju Bheemanahalli ◽  
Naqeebullah Kakar ◽  
...  

Extreme temperatures are considered one of the main constraints that limit the growth and development of rice. We elucidated the root and shoot developmental plasticity of 64 rice genotypes during early seedling establishment, using the sunlit plant growth chambers at 22/14 (low), 30/22 (optimum), and 38/30 °C (high) day/night temperatures. Low temperature severely inhibited 23 traits, such as shoot (68%), root (57%), and physiological (35%) attributes. On the contrary, the high temperature positively affected most of the shoot (48%) and root (31%) traits, except root diameter and root/shoot ratio, compared with the optimum. Alternatively, leaf chlorophyll fluorescence-associated parameters declined under low (34%) and high (8%) temperatures. A weak correlation between cumulative high-temperature response index (CHTRI) and cumulative low-temperature response index (CLTRI) indicates the operation of different low- and high-temperature tolerance mechanisms at the early seedling stage. Groups of distinct rice genotypes associated with low or high-temperature tolerance were selected based on CHTRI and CLTRI. The genotypes that commonly performed well under low and high temperatures (IR65600-81-5-2-3, CT18593-1-7-2-2-5, RU1504114, RU1504122, Bowman, and INIA Tacuari) will be valuable genetic resources for breeders in developing early-season high- and low-temperature-tolerant genotypes for a broad range of both tropical and temperate rice-growing environments.


Botany ◽  
2010 ◽  
Vol 88 (3) ◽  
pp. 286-289 ◽  
Author(s):  
John L. Snider ◽  
John S. Choinski ◽  
William Slaton

We have previously shown that juvenile leaves of Rhus glabra  L. growing in a field setting were consistently 2–3 °C warmer than mature leaves during periods of high irradiance. An experiment was done to test the hypothesis that these differences in leaf temperature lead to increased photosynthetic temperature tolerance in juvenile leaves when compared with cooler, mature leaves. Significant differences were found between the leaf stages with detached juvenile leaves having a slightly higher T15 (the temperature causing a 15% drop in maximum photochemical efficiency) than mature leaves (43.5 vs. 41.1 °C). Additionally, measurement of the effect of temperature on actual quantum yield (ΦPSII) showed maximum activity at 35 °C for mature leaves, whereas juvenile leaves exhibited a broader temperature response with similar activities between 30 and 40 °C. The 2 °C difference in T15 roughly coincided with observed average differences between juvenile and mature leaf temperature we observed in the field, indicating that higher juvenile leaf temperature is a factor in promoting their enhanced temperature tolerance.


Author(s):  
P. R. Swann ◽  
W. R. Duff ◽  
R. M. Fisher

Recently we have investigated the phase equilibria and antiphase domain structures of Fe-Al alloys containing from 18 to 50 at.% Al by transmission electron microscopy and Mössbauer techniques. This study has revealed that none of the published phase diagrams are correct, although the one proposed by Rimlinger agrees most closely with our results to be published separately. In this paper observations by transmission electron microscopy relating to the nucleation of disorder in Fe-24% Al will be described. Figure 1 shows the structure after heating this alloy to 776.6°C and quenching. The white areas are B2 micro-domains corresponding to regions of disorder which form at the annealing temperature and re-order during the quench. By examining specimens heated in a temperature gradient of 2°C/cm it is possible to determine the effect of temperature on the disordering reaction very precisely. It was found that disorder begins at existing antiphase domain boundaries but that at a slightly higher temperature (1°C) it also occurs by homogeneous nucleation within the domains. A small (∼ .01°C) further increase in temperature caused these micro-domains to completely fill the specimen.


Author(s):  
T. Geipel ◽  
W. Mader ◽  
P. Pirouz

Temperature affects both elastic and inelastic scattering of electrons in a crystal. The Debye-Waller factor, B, describes the influence of temperature on the elastic scattering of electrons, whereas the imaginary part of the (complex) atomic form factor, fc = fr + ifi, describes the influence of temperature on the inelastic scattering of electrons (i.e. absorption). In HRTEM simulations, two possible ways to include absorption are: (i) an approximate method in which absorption is described by a phenomenological constant, μ, i.e. fi; - μfr, with the real part of the atomic form factor, fr, obtained from Hartree-Fock calculations, (ii) a more accurate method in which the absorptive components, fi of the atomic form factor are explicitly calculated. In this contribution, the inclusion of both the Debye-Waller factor and absorption on HRTEM images of a (Oll)-oriented GaAs crystal are presented (using the EMS software.Fig. 1 shows the the amplitudes and phases of the dominant 111 beams as a function of the specimen thickness, t, for the cases when μ = 0 (i.e. no absorption, solid line) and μ = 0.1 (with absorption, dashed line).


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tânia Pinheiro ◽  
Ka Ying Florence Lip ◽  
Estéfani García-Ríos ◽  
Amparo Querol ◽  
José Teixeira ◽  
...  

AbstractElucidation of temperature tolerance mechanisms in yeast is essential for enhancing cellular robustness of strains, providing more economically and sustainable processes. We investigated the differential responses of three distinct Saccharomyces cerevisiae strains, an industrial wine strain, ADY5, a laboratory strain, CEN.PK113-7D and an industrial bioethanol strain, Ethanol Red, grown at sub- and supra-optimal temperatures under chemostat conditions. We employed anaerobic conditions, mimicking the industrial processes. The proteomic profile of these strains in all conditions was performed by sequential window acquisition of all theoretical spectra-mass spectrometry (SWATH-MS), allowing the quantification of 997 proteins, data available via ProteomeXchange (PXD016567). Our analysis demonstrated that temperature responses differ between the strains; however, we also found some common responsive proteins, revealing that the response to temperature involves general stress and specific mechanisms. Overall, sub-optimal temperature conditions involved a higher remodeling of the proteome. The proteomic data evidenced that the cold response involves strong repression of translation-related proteins as well as induction of amino acid metabolism, together with components related to protein folding and degradation while, the high temperature response mainly recruits amino acid metabolism. Our study provides a global and thorough insight into how growth temperature affects the yeast proteome, which can be a step forward in the comprehension and improvement of yeast thermotolerance.


2020 ◽  
pp. 100287
Author(s):  
Nating Yang ◽  
Yonghui Zhao ◽  
Hao Zhang ◽  
Weikai Xiang ◽  
Yuhan Sun ◽  
...  

Author(s):  
Juliane Rafaele Alves Barros ◽  
Miguel Julio Machado Guimarães ◽  
Rodrigo Moura e Silva ◽  
Maydara Thaylla Cavalcanti Rêgo ◽  
Natoniel Franklin de Melo ◽  
...  

2021 ◽  
pp. 107754632110026
Author(s):  
Zhou Sun ◽  
Siyu Chen ◽  
Xuan Tao ◽  
Zehua Hu

Under high-speed and heavy-load conditions, the influence of temperature on the gear system is extremely important. Basically, the current work on the effect of temperature mostly considers the flash temperature or the overall temperature field to cause expansion at the meshing point and then affects nonlinear factors such as time-varying meshing stiffness, which lead to the deterioration of the dynamic transmission. This work considers the effect of temperature on the material’s elastic modulus and Poisson’s ratio and relates the temperature to the time-varying meshing stiffness. The effects of temperature on the elastic modulus and Poisson’s ratio are expressed as functions and brought into the improved energy method stiffness calculation formula. Then, the dynamic characteristics of the gear system are analyzed. With the bifurcation diagram, phase, Poincaré, and fast Fourier transform plots of the gear system, the influence of temperature on the nonlinear dynamics of the gear system is discussed. The numerical analysis results show that as the temperature increases, the dynamic response of the system in the middle-speed region gradually changes from periodic motion to chaos.


Author(s):  
Yiqun Huang ◽  
Pawan Singh Takhar ◽  
Juming Tang ◽  
Barry G Swanson

Rheological behaviors of high acyl (HA) gellan are not well understood partially because of its relatively late commercialization compared to low acyl gellan. The objective of this study was to investigate the effect of temperature (5-30 °C), calcium (0, 1 and 10 mM) and gellan concentrations (0.0044-0.1000% w/v) on the flow behaviors of high acyl gellan aqueous solutions using rheological tests. Gellan solutions with 0 or 1 mM added Ca++ exhibited shear thinning behavior at gellan concentrations above 0.0125%. The influence of temperature on apparent viscosity (shear rate, 100 s-1) of gellan solutions can be described with an Arrhenius relationship. The apparent viscosity of gellan solution at low concentrations was more sensitive to temperature changes. The addition of Ca++ led to a decrease in flow resistance for a dilute gellan solution (<0.0125%), but an increased resistance for a relatively concentrated gellan solution (>0.0125%).


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