How Does Bacillus thuringiensis Crystallize Such a Large Diversity of Toxins?

Bacillus thuringiensis (Bt) is a natural crystal-making bacterium. Bt diversified into many subspecies that have evolved to produce crystals of hundreds of pesticidal proteins with radically different structures. Their crystalline form ensures stability and controlled release of these major virulence factors. They are responsible for the toxicity and host specificity of Bt, explaining its worldwide use as a biological insecticide. Most research has been devoted to understanding the mechanisms of toxicity of these toxins while the features driving their crystallization have long remained elusive, essentially due to technical limitations. The evolution of methods in structural biology, pushing back the limits of the resolution attainable, now allows access to be gained to structural information hidden within natural crystals of such toxins. In this review, I present the main parameters that have been identified as key drivers of toxin crystallization in Bt, notably in the light of recent discoveries driven by structural biology studies. Then, I develop how the future evolution of structural biology will hopefully unveil new mechanisms of Bt toxin crystallization, opening the door to their hijacking with the aim of developing a versatile in vivo crystallization platform of high academic and industrial interest.

Can (We Make) Bacillus thuringiensis Crystallize More Than Its Toxins?

The development of finely tuned and reliable crystallization processes to obtain crystalline formulations of proteins has received growing interest from different scientific fields, including toxinology and structural biology, as well as from industry, notably for biotechnological and medical applications. As a natural crystal-making bacterium, Bacillus thuringiensis (Bt) has evolved through millions of years to produce hundreds of highly structurally diverse pesticidal proteins as micrometer-sized crystals. The long-term stability of Bt protein crystals in aqueous environments and their specific and controlled dissolution are characteristics that are particularly sought after. In this article, I explore whether the crystallization machinery of Bt can be hijacked as a means to produce (micro)crystalline formulations of proteins for three different applications: (i) to develop new bioinsecticidal formulations based on rationally improved crystalline toxins, (ii) to functionalize crystals with specific characteristics for biotechnological and medical applications, and (iii) to produce microcrystals of custom proteins for structural biology. By developing the needs of these different fields to figure out if and how Bt could meet each specific requirement, I discuss the already published and/or patented attempts and provide guidelines for future investigations in some underexplored yet promising domains.

Differences of the Luminous Principle between Laser devices and LED devices

The concept of luminescence has been a fascinating concept to mankind. The goal of this paper is to provide insights into the mysterious phenomenon of photoluminescence occurring from natural crystal lattice materials through electron radiation processes. The research methods used in the study involve the detection, identification, and interpretation of the structure, the working principle of the luminescence concept, and the application of the concept of luminescence from written materials. The methods extracted from the materials involve biological and biochemical lab methods based on the existence of phosphorescence, chemiluminescence, bioluminescence, and finally fluorescence. The study paper also highlights the differences between LEDs and LASERS, which are the main types of luminescence producing semiconductor devices. Their variations are presented in aspects of their working principle, the type of luminescence they produce, the respective output power, and the speed, transmitting distance & cost of each. Photoluminescence is a concept whose applications are widespread in the physical and chemical processes of our daily activities. Therefore, it is important to have a sufficient understanding of the successful applications of luminescent enhancement.

Significant artefactual noise in 90Y TOF-PET imaging of low specific activity phantoms arises despite increased acquisition time

Volumes of usual PET phantoms are about four to sixfold that of a human liver. In order to avoid count rate saturation and handling of very high 90Y activity, reported TOF-PET phantom studies are performed using specific activities lower than those observed in liver radioembolization.However, due to the constant random coincidence rate induced by the natural crystal radioactivity, reduction of 90Y specific activity in TOF-PET imaging cannot be counterbalanced by increasing the acquisition time. As a result, most 90Y phantom studies reported images noisier than those obtained in whole-body 18F-FDG, and thus advised to use dedicated noise control in TOF-PET imaging post 90Y liver radioembolization.We performed acquisitions of the Jaszczak Deluxe phantom in which the hot rod insert was only partially filled with 2.6 GBq of 90Y. Standard reconstruction parameters recommended by the manufacturer for whole-body 18F-FDG PET were used.Low specific activity setups, although exactly compensated by increasing the acquisition time in order to get the same number of detected true coincidences per millilitre, were impacted by significant noise. On the other hand, specific activity and acquisition time setup similar to that used in post 90Y liver radioembolization provided image quality very close to that of whole-body 18F-FDG.This result clearly discards the use of low specific activity phantoms intended to TOF-PET reconstruction parameter optimization. Volume reduction of large phantoms can be achieved by vertically setting the phantoms or by adding Styrofoam inserts.

Polarization and Electromagnetic Emissions of Natural Crystalline Structures upon Acoustic Excitation

A surface charge density distribution on natural crystal samples is investigated in the paper. Here are revealed regularities of electromagnetic signal amplitude changes upon acoustic excitation of electrified calcite samples depending on the size of the crystals.

Фотолюминесценция кристаллов Cu-=SUB=-2-=/SUB=-O различного происхождения

The low-temperature luminescence spectra of Cu2O crystals grown by the different methods (copper oxidation, induction melting, magnetron sputtering, hydrothermal synthesis) and of natural crystal are compared. It was concluded that the high quality of natural crystals and crystals grown by the hydrothermal method is due to the low temperature process of their formation which minimizes the strains.

Spectroscopic Methods Used for Structural Analysis of Natural Crystals

Most of the natural crystal color distribution are more uniform, different shades, pastel colors, while in manual control is relatively stable under the conditions of the synthesis of crystal growth, its internal characteristics exhibited excessive uniformity, color uniform, uniform, gaudy, dull, colorant concentration is too high or too low, make crystal color appears too deep or too shallow phenomenon. This paper studies the characteristics of natural crystal detection methods.

Study on Optimization Quartz Mine for Removal Gas-Liquid Inclusions in Quartz Sand under Microwave and Acid Corrosion

Using Gas Chromatography and Fourier Transform Infrared Spectroscopy (FT-IR), the content of metal impurity element and gas-liquid inclusions in natural crystal and ordinary silica mine of different mining area had been studied. The characteristics of silica mine which was suitable for microwave-acid etching process to remove gas fluid inclusion in quartz sand had been discussed.Our results showed that the silica mine which had low content of impurity, less content of gas-fluid inclusion and high water filling degree was suitable for the microwave-acid etching process to remove gas-liquid inclusion in quartz sand; the content of metal element impurities in quartz sand from Madagascar was nearly close to the primary natural crystal, had less content of gas-fluid inclusion and high water filling degree, and was suitable for the microwave-acid etching process to remove.