Evolution of Hsp70 Gene Expression: A Role for Changes in AT-Richness within Promoters

In disparate organisms adaptation to thermal stress has been linked to changes in the expression of genes encoding heat-shock proteins (Hsp). The underlying genetics, however, remain elusive. We show here that two AT-rich sequence elements in the promoter region of the hsp70 gene of the fly Liriomyza sativae that are absent in the congeneric species, Liriomyza huidobrensis, have marked cis-regulatory consequences. We studied the cis-regulatory consequences of these elements (called ATRS1 and ATRS2) by measuring the constitutive and heat-shock-induced luciferase luminescence that they drive in cells transfected with constructs carrying them modified, deleted, or intact, in the hsp70 promoter fused to the luciferase gene. The elements affected expression level markedly and in different ways: Deleting ATRS1 augmented both the constitutive and the heat-shock-induced luminescence, suggesting that this element represses transcription. Interestingly, replacing the element with random sequences of the same length and A+T content delivered the wild-type luminescence pattern, proving that the element's high A+T content is crucial for its effects. Deleting ATRS2 decreased luminescence dramatically and almost abolished heat-shock inducibility and so did replacing the element with random sequences matching the element's length and A+T content, suggesting that ATRS2's effects on transcription and heat-shock inducibility involve a common mechanism requiring at least in part the element's specific primary structure. Finally, constitutive and heat-shock luminescence were reduced strongly when two putative binding sites for the Zeste transcription factor identified within ATRS2 were altered through site-directed mutagenesis, and the heat-shock-induced luminescence increased when Zeste was over-expressed, indicating that Zeste participates in the effects mapped to ATRS2 at least in part. AT-rich sequences are common in promoters and our results suggest that they should play important roles in regulatory evolution since they can affect expression markedly and constrain promoter DNA in at least two different ways

Laser frequency offset locking via tripod-type electromagnetically induced transparency

We have demonstrated the laser frequency offset locking via the Rb tripod-type double dark resonances electromagnetically induced transparency (EIT) system. The influence of coupling fields power and detuning on the tripod-type EIT profile is detailed studied. In a wide coupling fields detuning range, the narrower EIT dip has an ultranarrow linewidth of 590 KHz, which is about one order narrower than the natural linewidth of Rb. Without the additional frequency stabilization of the coupling lasers, we achieve the relative frequency fluctuation of 60 KHz in a long time of ~2000s, which is narrower than the short-time linewidth of each individual laser

Thermodynamic and kinetic study of CO2 adsorption/desorptionon amine-functionalized sorbents

473-482The thermodynamic and kinetic characteristics of CO2 adsorption of SBA-16 loaded with pentaethylenehexamine (PEHA) have been investigated using adsorption column system. The Langmuir isotherm model fitts the CO2 adsorption isotherms well, and the average isosteric heat of adsorption is 59.6 kJ/mol, indicating that the CO2 adsorption on PEHA-loaded SBA-16 is chemisorption. The Avrami fractional dynamics model is very suitable for illustrating the adsorption behaviour of CO2 adsorption, and the results of kinetic analysis show that increasing the partial pressure of CO2 or the working temperature is beneficial to the adsorption of CO2. Three desorption methods were evaluatedto achieve the optimal desorption method. The results show that VTSA and steam stripping method are effective methods for industrial CO2 desorption. Steam stripping may be more suitable for plants that already have low-cost steam. The activation energy Ea of CO2 adsorption/desorption is calculated using Arrhenius equation. The activation energy Ea of CO2 adsorption/desorption was calculated using the Arrhenius equation. The results show that the absolute value of Ea (adsorption) decreases with the increase of CO2 partial pressure. In addition, the Ea value of vacuum rotary regeneration method and steam stripping method is smaller than the Ea value of temperature swing regeneration

COMPUTATIONAL STUDY OF SIC HALIDE CHEMICAL VAPOR DEPOSITION SYSTEM

ABSTRACT Halide CVD (HCVD) is recently employed to grow SiC epitaxial layers using SiCl 4 /C 3 H 8 /H 2 mixtures in an effort to achieve high deposition rates. The introduction of the chlorinated species allows the formation of more stable species SiCl 2 while maintaining high surface reactivity, thus avoiding the silicon gas phase nucleation that has been widely reported in conventional CVD process using SiH 4 /C 3 H 8 /H 2 . However, the difficulties in reducing defect density and controlling the electrical properties of the material present a significant technical obstacle for HCVD of SiC. In experimental growth, the electrical properties, defect densities and the growth rate of as-deposited SiC epitaxial films are, to a large extent, determined by processing parameters including temperature, pressure, flow rates of precursors and carrier gas. Optimization of growth conditions provides the opportunity to engineer films with desired film properties and qualities at high deposition rate but requires in-depth understanding the deposition process. In this study, we performed computational study to investigate the effects of main processing parameters in HCVD process on film growth. Numerical experiments were performed over a wide range of operational parameters to provide information on distributions of gas velocity, temperature, and chemical species' concentrations in the reactor as well as the deposition rates on the substrate surface. Simulations were also carried out to address hot zone design and operational conditions

ChIP-seq identifies McSLC35E2 as a novel target gene of McNrf2 in Mytilus coruscus, highlighting its role in the regulation of oxidative stress response in marine mollusks

NF-E2-related factor 2 (Nrf2) plays a crucial role in the oxidative regulatory process, which could trigger hundreds of antioxidant elements to confront xenobiotics. In the previous study, we identified Nrf2 from the marine mussel Mytilus coruscus, and the findings demonstrated that McNrf2 effectively protected the mussels against oxidative stress induced by benzopyrene (Bap). In order to delve deeper into the underlying mechanism, we utilized Chromatin Immunoprecipitation followed by sequencing (ChIP-seq) technology to systematically identify potential novel target genes of McNrf2. A total of 3,465 potential target genes were screened, of which 219 owned binding sites located within the promoter region. During subsequent experimental verification, it was found that McSLC35E2, a candidate target gene of McNrf2, exhibited negative regulation by McNrf2, as confirmed through dual luciferase and qRT-PCR detection. Further, the enzyme activity tests demonstrated that McNrf2 could counteract Bap induced oxidative stress by inhibiting McSLC35E2. The current study provides valuable insights into the application of ChIP-seq technology in the research of marine mollusks, advancing our understanding of the key role of Nrf2 in antioxidant defense mechanisms, and highlighting the significance of SLC35E2 in the highly sophisticated regulation of oxidative stress response in marine invertebrates