Structural insights into an evolutionary turning-point of photosystem I from prokaryotes to eukaryotes

Photosystem I (PSI) contributes to light-conversion reactions; however, its oligomerization state is variable among photosynthetic organisms. Herein we present a 3.8-Å resolution cryo-electron microscopic structure of tetrameric PSI isolated from a glaucophyte alga Cyanophora paradoxa. The PSI tetramer is organized in a dimer of dimers form with a C2 symmetry. Different from cyanobacterial PSI tetramer, two of the four monomers are rotated around 90°, resulting in a totally different pattern of monomer-monomer interactions. Excitation-energy transfer among chlorophylls differs significantly between Cyanophora and cyanobacterial PSI tetramers. These structural and spectroscopic features reveal characteristic interactions and energy transfer in the Cyanophora PSI tetramer, thus offering an attractive idea for the changes of PSI from prokaryotes to eukaryotes.

The different encapsulants of lileum leaves (Clerodendrum Minahassae L) and Avocado Seed (Persea Americana Mill) extraction on Physical Quality and Microscopic Structure

This research aimed to examine the differences encapsulant of leilem leaves and avocado seed (1 : 1) using a microwave oven to the microcapsule product physical quality and microscopic structure. The method was used laboratory experimental with 5 different encapsulants consist of gum arab (A1), whey (A2), chitosan (A3), maltodextrin (A4) and zeolit (A5) with 4 replications in every treatment, respectively. The Variables observed in this research consist of physical quality (dry matter, density, yield, solubility of solids) and microscopic structure. The data of physical quality was evaluate the size and structure, then the microscopic structure was analysed by analysis of variance (ANOVA) of the experiment using Completely Randomized Design (CRD). The results showed that the use of different encapsulates showed a significant (P < 0.05) effect on density and the solubility of solids in the product but it were not significant effect on dry matter and yield. Furthermore, different encapsulants also showed significantly different on the microscopic structure. Therefore, it can be concluded that the encapsulation process of the mixed extract of leilem leaves and avocado seeds using a microwave oven and chitosan encapsulation can produce the best physical quality and microscopic structure.

Microscopic modelling of nematic elastic constants beyond Straley theory

Recent findings on various classes of nematics, whose microscopic structure differs from the prototypical rod-like shape, evidence unusual elastic properties, which challenge existing theories. Here we develop a theoretical and...

Macroscopic Behavior and Microscopic Structure Evolution of Marine Clay in One-Dimensional Compression Revealed by Discrete Element Simulation

Marine clay has been attracting in-depth research on its mechanical behavior and internal structure evolution, which are crucial to marine infrastructure safety. In the formation process of marine clay, including the sedimentation and consolidation stages, the compression behavior and internal structure evolution are highly dependent on the pore water salinity. Discrete element method (DEM) simulation is a powerful tool to study the microscopic mechanics behind the complicated macroscopic mechanical behavior of marine clay. In this study, a DEM simulation scheme is systematically proposed to numerically study the macroscopic beahvior and microscopic structure evolution of marine clay in one-dimensional compression that mimics the marine clay formation process. First, the proposed calculation scheme for double layer repulsive interaction and van der Waals interaction is introduced. Then, the developed DEM simulation scheme is validated by satisfactorily reproducing the experimentally observed one-dimensional compression curves and internal structure transition from an edge-to-edge/edge-to-face flocculated structure to a face-to-face dispersed structure. Finally, evolutions of coordinate number and fabric anisotropy are quantitatively evaluated in the microscopic view. The noticeable effects of ion concentration on the internal structure evlotion and mechanical behavior of marine clay have been examined and discussed.

Features of the microscopic structure of the adrenal gland of geese

The study of the morphology of the adrenal gland of birds is one of the most critical issues of modern biology and veterinary medicine cause its solution contributes to the scientific justification of technologies for rearing, using, and treating birds. The work aims to clarify the features of the microscopic structure of the adrenal gland of geese. As a peripheral organ of the endocrine system, the adrenal gland affects the growth and differentiation of tissues, regulates water, protein, carbohydrate, fat, and mineral metabolism, the body's resistance to infections, intoxication, stress, and other factors. During research were used histological indagation methods. It was found that blood vessels, clusters of nerve cells are registered in the capsule of the adrenal gland of geese. Nodes of the sympathetic nervous system are registered outside it. Connective tissue septa with hemocapillaries extend from the capsule to the adrenal parenchyma, which is represented by intertwined cell strands of interrenal and suprarenal tissues. The narrow spaces between these cell strands are filled with layers of loose fibrous connective tissue with sinusoidal hemocapillaries and venous sinuses. The subcapsular layer, peripheral and central zones are recorded on the incision of the adrenal gland. The adrenal vein is localized in the central zone. The subcapsular zone is mainly represented by cells of suprarenal tissue, the peripheral and central zone – by cells of interrenal tissue. Suprarenal tissue cells have a polygonal shape, basophilic cytoplasm, and a rounded, centrally located nucleus. Cells of interrenal tissue are columnar or cubic, have eosinophilic colored cytoplasm, a round or oval nucleus placed eccentrically. Venous sinuses are localized in the central and peripheral zones of the adrenal gland. Their wall is thin, formed by flat endotheliocytes, bounded by groups of cells of interrenal and suprarenal tissues. As a result, established microscopic structural features of the adrenal gland of geese can be used to formulate the base of its typical morphological characteristics, which give a possibility to assess the Morpho-functional essential state of the bird adrenal gland of this species by the influence of various factors and pathologies, in perspective of following researches – the exploration of morphometric parameters of the structural components of the adrenal gland of geese.