In recent decades, the attention of scientists has been drawn towards nanoparticles (NPs) of metals and metalloids. Traditional methods for the manufacturing of NPs are now being extensively studied. However, disadvantages such as the use of toxic agents and high energy consumption associated with chemical and physical processes impede their continued use in various fields. In this article, we analyse the relevance of the use of living systems and their components for the development of "green" synthesis of nano-objects with exceptional properties and a wide range of applications. The use of nano-biotechnological methods for the synthesis of nanoparticles has the potential of large-scale application and high commercial potential. Bacteria are an extremely convenient target for green nanoparticle synthesis due to their variety and ability to adapt to different environmental conditions. Synthesis of nanoparticles by microorganisms can occur both intracellularly and extracellularly. It is known that individual bacteria are able to bind and concentrate dissolved metal ions and metalloids, thereby detoxifying their environment. There are various bacteria cellular components such as enzymes, proteins, peptides, pigments, which are involved in the formation of nanoparticles. Bio-intensive manufacturing of NPs is environmentally friendly and inexpensive and requires low energy consumption. Some biosynthetic NPs are used as heterogeneous catalysts for environmental restoration, exhibiting higher catalytic efficiency due to their stability and increased biocompatibility. Bacteria used as nanofactories can provide a new approach to the removal of metal or metalloid ions and the production of materials with unique properties. Although a wide range of NPs have been biosynthetic and their synthetic mechanisms have been proposed, some of these mechanisms are not known in detail. This review focuses on the synthesis and catalytic applications of NPs obtained using bacteria. Known mechanisms of bioreduction and prospects for the development of NPs for catalytic applications are discussed.
Respiratory organs and cardiovascular system are interconnected and perform extremely vital functions of the organism, the main goals being performing gas exchange with the environment and emitting carbon dioxide produced in the organism into the environment. Therefore, we carried out comparative histo- and cytomorphometric evaluation of morphological structures of the heart and lungs of cattle, sheep and horses. Using complex methods of research, we determined specifics of microscopic structure and histometric parameters of parenchyma of the lungs and myocardium of the ventricles of the hearts of clinically healthy animals in species aspect – cattle, sheep and horses. The studies revealed that the histoarchitectonics of the studied animals were similar in structure, characteristic of other species of agricultural mammals, and distinct morphometric peculiarities of their histostructures. The study indicated that the respiratory zone of the lungs is most developed in horses. This parameter was lower in ruminants – cattle and sheep. Connective tissue septum of parenchyma of lungs was better expressed in cattle and sheep, and less in horses. At the same time, mean volume of lung alveoli in clinically healthy animals varied: being highest in horses – 699 ± 106 thou µm3, then cattle – 337 ± 43 thou µm3 and sheep – 158 ± 37 thou µm3. Such variation in histometric parameters of parenchyma of the lungs in experimental animals indicates adaptive specifics of the organism of animals in terms of living conditions. Therefore, the respiratory zone was most developed in the lungs of horses, animals that experience significant physical and physiological load on corresponding organs and systems. As a result of histometric studies of myocardium, we determined patterns of sizes of thickness of its cardiomyocytes and volume of their nuclei. We determined that in myocardium of the heart ventricles, in the same microscope field of view, cardiomyocytes of varying thicknesses occur. At the same time, thickness of cardiomyocytes, their mean volume of nuclei in the ventricle myocardium were expressed the most in cattle, then in horses and sheep, and their histometric parameters in myocardium of the left ventricle of the heart in the experimental animals were higher than in the right one. Therefore, thickness of cardiomyocytes of the left ventricle in cattle equaled 14.06 ± 0.41 µm, and volume of nuclei of cardiomyocytes respectively 124.55 ± 7.99 µm3. Similar changes in such parameters of histometry were found in sheep and horses. We attribute such varying histometric parameters of the thickness of cardiomyocytes and volume of their nuclei in myocardium of the left ventricle of the heart in experimental animals, compared with such parameters in the right ventricle, to the activities of the ventricles (the left one generally functions as a pump, right one – as a volumetric) and functional specifics of this myocardium tissue, which is capable of spontaneous rhythmic contractions, resulting in blood flow in the vessels: cardiomyocytes of the left ventricle carry greater load, promoting blood flow in vessels of greater (somatic) blood circulation, respectively cardiomyocytes of the right ventricle – less load, promoting blood flow in vessels of lesser (pulmonary) blood circulation.
The spinal ganglia, which perform the function of the first link on the afferent impulses’ way from the receptors to the central nervous system, recognize internal and external irritations, and are the first to transform them into a nervous impulse. As the representatives of the peripheral nervous system, they are some of the main objects of the studies in contemporary neuromorphology. Based on the results of anatomic, neurohistological, histochemical, morphometric and statistical methods of the studies, we conducted a complex survey, revealing the morphology of spinal ganglia of different segmental levels in the domestic dog. In particular, we determined the differences in the microscopic structure and morphometric parameters of cervical, thoracic, lumbar and sacral spinal ganglia and the ganglia of the cervical and lumbar enlargements in mature domestic dogs. The study showed that the spinal ganglia of domestic dogs can have different skeletotopy, different shape and sizes due to their species peculiarity. Also, the surveyed animals, according to the results of our studies, had the cervical and thoracic spinal ganglia of oval, while the lumbar and sacral – spindle-like shapes. According to the results of morphometry, the area of the spinal ganglia in lengthwise section differed: the smallest area belonged to the thoracic, the largest to the sacral spinal ganglia. The density of neuronal arrangement per 0.1 mm2 of the area of the spinal ganglia correlated with their sizes: the highest parameter was identified for the thoracic spinal ganglia, the lowest – for the sacral. The conducted studies revealed that histo- and cyto-structure of the spinal ganglia is characteristic of notable differentiation of the nervous cells of small sizes. Therefore, we differentiated neurons of the spinal ganglia into large, medium and small. The highest quantity of large neurons was found in the sacral ganglia, and largest amount of medium-sized neurons – in the ganglia of the lumbar enlargement. In other ganglia, small neurons dominated. Correspondingly, different nuclear-cytoplasmic ratio in these neurons was determined, indicating different extent of morphofunctional condition of nervous cells. We determined content of localization and separation of nucleic acids in histostructure of the spinal cord at the tissue and cellular levels.
The scientific article presents the results of investigating the spinal cord`s morphology of a domestic bull (Bos Taurus). Data on the histo- and cytostructure of the spinal cord are given according to the results of histological, neurohistological, and morphometric studies. For their implementation, the selected material (spinal cord n = 8) was subjected to fixation in 10–12 % neutral formalin solution, followed by pouring into paraffin. Histological sections were made from paraffin blocks on a sliding microtome MS-2 with a thickness of not more than ten μm. Staining of sections with hematoxylin and eosin, according to Van Gieson's methods, as well as neuro-histological methods of impregnation of nerve tissue with silver nitrate according to the Bilshovskym-Gross method, was used for the morphometric studies, investigating the morphology of the cell, conducting and obtaining the review histological preparations. The histostructure of the spinal cord, the localization of neurons in the gray matter, and morphometric studies of structural elements were examined on histological specimens by light microscopy. The entire experimental part of the research was conducted following the requirements of the international principles of the "European Convention for the Protection of Vertebrate Animals for Experimental and Other Scientific Purposes" (Strasbourg, 1986). The spinal cord, medulla spinalis, an organ of the central nervous system of vertebrates, is located in the spinal canal. The spinal cord is protected externally by soft, arachnoid, and hard meninges. The space between the membranes and the spinal canal is filled with cerebrospinal fluid. It is well known that groups of multipolar nerve cells with the same functional value form the nuclei of the gray matter of the spinal cord. According to the results of our histological studies, a pronounced differentiation of nerve cells, which have different shapes and sizes. Among them are large, medium, and small nerve cells. The shape of nerve cells is different, which, in turn, depends on their location in certain areas of the gray matter of the spinal cord and the size of the cell. In general, there are multifaceted, stellate, spindle-shaped, elongated, rounded, and oval neurons. Small nerve cells have an oval or round, less often – irregularly rounded shape, medium – round, oval, spindle-shaped. Large nerve cells are dominated by a multifaceted shape with distinct processes. The nuclei of large nerve cells, in most cases, have a rounded shape, less often – oval, mostly in the center of the cells, seldom – eccentrically. According to the results of morphological studies, it is noted that the neurons of the gray matter of the spinal cord have different shapes and sizes. Consequently, in the gray matter, small cells are the highest quantity (47.91 ± 0.32 %) of the total number of nerve cells. The second place is occupied by average neurons (33.70 ± 0.46 %). The large cells are detected in the smallest amount (18.37 ± 0.50 %).
From among a great number of digestive system diseases in domestic animals there is pancreatitis which is caused by an early zymogenesis in the acinar cells. The problem of studying the structural organization of a pancreata in sick cats is topical because of a progressive spreading of pancreatitis in domestic animals. Thus, the purpose of the research was to study out the morphological changes of cats pancreata under acute pancreatitis. Working with vertebrate animals we were guided by “European Convention for the Protection of Vertebtate Animals used for Experimental and other Scientific Purposes” (Strasbourg, 1986). The results of the histological examination of cats pancreata under acute pancreatitis show some pathological changes both in endocrine and exocrine pancreas. Such changes were manifested in necrosis of exocrine pancreatitis as well as in spreading and swelling of acinar space, that testified to the infancy of an inflammatory process. Some dystrophic changes, followed by karyolysis, were found in the focus of tissue nicrosis. Pancreatocyte cytoplasm was cloudy, its basal and apical zones were obscure, clearly defined interstitial tissue swelling was found between the particles and unequal swelling was found inside the particles. Intercellular space was exaggerated. Morphometrically in a group of sick animals was detected an increase in specific weihgt of stromal component (р<0,05),which equalled 22,44±0,24 %, in a control group it equalled 17,78±0,15 %. Some hemorrhage and distrophicvally changed hormone- active cells as well as nonregular distribution of cells were detected under a histological examination of Langerhans islets. In most islets the cells had swelled vacuolar cytoplasm. While analyzing the morphometric indices it was stated that the cats exocrine pancreas under acute pancreatitis was 1.12 as large and occupied 48258,05±135,07 mkm2, (97,88±0,05 %). The cats endocrine pancreas under this pathology occupied 6858,85±315,05 mkm2, (2,12±0,05 %). In cats of a control group this index equalled 6784,71±285,04 mkm2 (1,95±0,06 %). The diameter of sick cats acinus as well as of Langerhans islets equalled respectively 31,85±0,05 and 71,81±2,45 mkm, which reliably (р<0,001) was 1.13 and 1.15 as large. In clinically healhty cats these indices are 28,12±0,11; 70,20±2,48 mkm.
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