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171 result(s) for "Mitrović, Aleksandra"
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Phosphorus homeostasis in Populus alba L. under excess phosphate conditions, assessed by 31P nuclear magnetic resonance spectroscopy and X-ray microfluorescence
The phosphates (Pi) are nowadays recognized as pollutants. We studied the effect of Pi (0.625–12.500 mM KH 2 PO 4 ) in the culture medium on in vitro grown 2-month-old Populus alba trees. The levels of sugar phosphates and vacuolar and cytoplasmic Pi in cell compartments of roots and stems were determined using 31 P NMR, while tissue-specific micro- and macroelements mapping on stem cross-sections were performed using synchrotron-based X-ray microfluorescence. Plants grown on 0.625 mM Pi (MS/2 medium) showed a survival rate of 70%. With the increase in Pi concentrations up to 6.250 mM, plant growth and survival increased, without changes in total P content per mass or in the levels of cytoplasmic and vacuolar phosphates, in both stems and roots, while the levels of Fe, Cu, Zn, Ca and Mn in stems increased. Further increase in Pi to 9.375 and 12.500 mM in the medium resulted in inhibited growth comparable with plants grown on MS/2, with the increase in total P content per mass up to 50%, in both stems and roots, but with no changes in cytoplasmic and vacuolar phosphates; 12.500 mM Pi affected even plant survival (70%) and thus might be considered as mildly toxic. 31 P NMR results indicate that the high tolerance of P. alba to increased Pi could result from its ability to maintain an intracellular P homeostasis, despite P accumulation up to 50%, in both stems and roots, indicating P. alba as a promising wood species for dendroremediation.
Differential Polarization Imaging of Plant Cells. Mapping the Anisotropy of Cell Walls and Chloroplasts
Modern light microscopy imaging techniques have substantially advanced our knowledge about the ultrastructure of plant cells and their organelles. Laser-scanning microscopy and digital light microscopy imaging techniques, in general—in addition to their high sensitivity, fast data acquisition, and great versatility of 2D–4D image analyses—also opened the technical possibilities to combine microscopy imaging with spectroscopic measurements. In this review, we focus our attention on differential polarization (DP) imaging techniques and on their applications on plant cell walls and chloroplasts, and show how these techniques provided unique and quantitative information on the anisotropic molecular organization of plant cell constituents: (i) We briefly describe how laser-scanning microscopes (LSMs) and the enhanced-resolution Re-scan Confocal Microscope (RCM of Confocal.nl Ltd. Amsterdam, Netherlands) can be equipped with DP attachments—making them capable of measuring different polarization spectroscopy parameters, parallel with the ‘conventional’ intensity imaging. (ii) We show examples of different faces of the strong anisotropic molecular organization of chloroplast thylakoid membranes. (iii) We illustrate the use of DP imaging of cell walls from a variety of wood samples and demonstrate the use of quantitative analysis. (iv) Finally, we outline the perspectives of further technical developments of micro-spectropolarimetry imaging and its use in plant cell studies.
Parenchyma cell wall structure in twining stem of Dioscorea balcanica
Anatomical adaptation of liana plants includes structural changes in cell walls of different tissues: fibers, vessel elements and tracheids. However, the contribution of parenchyma cells to stem twining in liana plants is mostly unknown. The aim of this investigation is to determine changes in stem parenchyma cell walls that are correlated with the twinning process in liana plants. Parenchyma cell wall structure was studied on the stem cross sections of straight and twisted internodes of monocotyledonous liana Dioscorea balcanica, by different microscopy techniques: light microscopy, scanning electron microscopy, fluorescence detected linear dichroism microscopy and Fourier transform infrared microspectrometry. In addition, chemical analysis of the entire stem internodes was performed using photometric and chromatographic methods. Parenchyma cell walls of twisted D. balcanica internodes are characterized by: lower amounts of cellulose (obtained by FTIR microspectrometry) with different cellulose microfibril orientation (shown by Scanning electron microscopy), but no changes in \"cellulose fibril order\" (obtained by Differential polarization laser scanning microscopy); lower amounts of xyloglucan, higher amounts of xylan, higher amounts of lignin with modified organization-less condensed lignin (obtained by FTIR microspectrometry). At the same time, chemical analysis of the entire internodes did not show significant differences in lignin content and cell wall bound phenols related to stem twining, except for the presence of diferulate cross-links exclusively in twisted internodes. Our results indicate that adaptations to mechanical strain in D. balcanica stems involve modifications in parenchyma cell wall structure and chemistry, which provide decreased stiffness, higher strength and increased elasticity of twisted internodes.
A review of research on the Lemanea genus in Serbia
The first data on the genus in Serbia come from the late 20th century. Only one species, , was reported from 10 localities in Serbian riverine ecosystems between 1991 and 2017. Extensive research on this genus was performed in April–November 2017–2019, surveying 150 localities in 97 upland and mountain rivers. During this study period, the genus was recorded at 14 localities in 12 rivers, while it disappeared from five previously reported localities. A total of four taxa were identified: , , sp. and and were recorded in Serbia for the first time. was the most common taxon. Our research confirmed that species prefer similar specific environmental conditions. These species were found in temperate, soft or moderately hard, well-oxygenated and weakly alkaline waters, with low, moderate or high conductivity, and in waters with low content of inorganic nutrients. Due to their sensitivity to changes in environmental conditions, species are exposed to negative anthropogenic impact leading to the degradation of their habitats. Intensive construction of small hydropower plants has threatened most habitats of the Rhodophyta species in the last few years.
Correction to: Parenchyma cell wall structure in twining stem of Dioscorea balcanica
In the original publication of the article, one of the project numbers was omitted in the Acknowledgments. The correct version is provided below.
Automatic image processing morphometric method for the analysis of tracheid double wall thickness tested on juvenile Picea omorika trees exposed to static bending
Key message We present and test an automatic image processing morphometric method for the analysis of tracheid double wall thickness. Measurements of various anatomical characteristics of wood cells are of great importance in research of wood structure, either for the evaluation of environmental influences or for estimation of wood quality. We present and test an automatic image processing morphometric method for the analysis of tracheid double wall thickness. A new algorithm of image analysis was developed. It uses morphological processing of structural elements with the different orientations from distance maps to analyze tracheid double wall thickness distribution separately for radial walls, tangential walls, and cell corners. For testing the performance of the method, we used confocal laser scanning microscopy images of stem cross-sections of juvenile Picea omorika trees exposed to long-term static bending. As a response to mechanical stress, conifers form compression wood (CW), which occurs in a range of gradations from near normal wood (NW) to severe CW. However, visual detection of compression wood severity, more precisely the determination of mild CW, is difficult. One of the anatomic features that characterize CW is increased wall thickness. After testing proposed automatic image processing morphometric method for the analysis of tracheid double wall thickness separately for radial walls, tangential walls and cell corners, combined with statistical analysis, we could suggest it as a tool for estimation of compression wood severity, or for estimation and gradation of changes in tracheid cell wall thickness as a response to environmental influences during growth and developmental process.
Influence of Aging on the Flexural Strength of PLA and PLA-X 3D-Printed Materials
The three-point bending test is a valuable method for evaluating the mechanical properties of 3D-printed biomaterials, which can be used in various applications. The use of 3D printing in specimen preparation enables precise control over material composition and microstructure, facilitating the investigation of different printing parameters and advanced materials. The traditional approach to analyzing the mechanical properties of a material using a three-point bending test has the disadvantage that it provides only global information about the material’s behavior. This means that it does not provide detailed insight into the local strain distribution within the material. However, the 2D Digital Image Correlation (DIC) method offers additional insight, especially in terms of strain localization. DIC is an optical technique that measures full-field displacements and strains on the surface of a sample. PLA and enhanced PLA-X material were utilized to create three-point bending samples. The aim of this paper was to analyze and compare the influence of aging on the mechanical properties of PLA and enhanced PLA-X materials using three-point bending coupled with the DIC method. The results showed statistically significant differences between the PLA and PLA-X, for both the new and aged materials. The aged PLA samples had the highest average value of maximal force around 68 N, which was an increase of 8.8% compared to the new PLA samples. On the other hand, the aged PLA-X material had an increase of 7.7% in the average maximal force compared to the new PLA-X samples. When comparing the two materials, the PLA samples had higher maximal force values, 6.2% for the new samples, and 7.3% for the aged samples. The DIC results showed that both the new PLA and PLA-X samples endured higher strain values at Points 1 and 2 than the aged ones, except for the aged PLA-X sample at Point 2, where the new sample had higher strain values. However, for the first 5 min of the experiment, both materials exhibited identical behavior, after which point significant differences started to occur for both materials, as well as at Points 1 and 2. A more profound comprehension of the biomechanical characteristics of both PLA and PLA-X material is essential to enhance the knowledge for potential biomedical applications. The DIC method was found to be a powerful tool for analyzing the deformation and failure behavior of samples and for complementing the traditional approach to material testing.
Effects of Chestnut Tannin Extract on Enteric Methane Emissions, Blood Metabolites and Lactation Performance in Mid-Lactation Cows
Dietary tannin supplementation represents a potential strategy to modulate rumen fermentation and enhance lactation performance in dairy cows, though responses remain inconsistent. A 21-day feeding trial was conducted to evaluate the effect of chestnut tannin (CNT) extract on the enteric methane emissions (EME), blood metabolites, and milk production traits in mid-lactation dairy cows. Thirty-six Holstein cows were allocated to three homogeneous treatment groups: control (CNT0, 0 g/d CNT), CNT40 (40 g/d CNT), and CNT80 (80 g/d CNT). Measurements of EME, dry matter intake (DMI), milk yield (MY), and blood and milk parameters were carried out pre- and post-21-day supplementation period. Compared with the no-additive group, the CNT extract reduced methane production, methane yield, and methane intensity in CNT40 and CNT80 (p < 0.001). CNT40 and CNT80 cows exhibited lower blood urea nitrogen (p = 0.019 and p = 0.002) and elevated serum insulin (p = 0.003 and p < 0.001) and growth hormone concentrations (p = 0.046 and p = 0.034), coinciding with reduced aspartate aminotransferase (p = 0.016 and p = 0.045), and lactate dehydrogenase (p = 0.011 and p = 0.008) activities compared to control. However, CNT80 had higher circulating NEFA and BHBA than CNT0 (p = 0.003 and p = 0.004) and CNT40 (p = 0.035 and p = 0.019). The blood glucose, albumin, and total bilirubin concentrations were not affected. MY and fat- and protein-corrected milk (FPCM), MY/DMI, and FPCM/DMI were higher in both CNT40 (p = 0.004, p = 0.003, p = 0.014, p = 0.010) and CNT80 (p = 0.002, p = 0.003, p = 0.008, p = 0.013) cows compared with controls. Feeding CNT80 resulted in higher protein content (p = 0.015) but lower fat percentage in milk (p = 0.004) compared to CNT0. Milk urea nitrogen and somatic cell counts were significantly lower in both CNT40 (p < 0.001, p = 0.009) and CNT80 (p < 0.001 for both) compared to CNT0, while milk lactose did not differ between treatments. These findings demonstrate that chestnut tannin extract effectively mitigates EME while enhancing lactation performance in mid-lactation dairy cows.
Effects of liking on visual attention in faces and paintings
The visual aesthetics of an object increases visual attention towards the object. It is argued that this relation between liking and attention is an evolutionary adaptation in sexual and natural selection. If this is the case, we would expect this relation to be domain specific, and thus, stronger for biological than for non-biological objects. To test this hypothesis, we conducted two eye-tracking studies, in which we compared the relation between liking and gaze patterns in images of biological (faces) and non-biological (paintings) stimuli. In Study 1, we presented randomly combined image pairs for 20 s in a free-viewing paradigm. Participants then selected the image they liked more in a 2-AFC task and rated the liking of each image on a Likert-scale. In Study 2, we employed the same paradigm but this time, images were combined based on pre-rated liking to ensure that images in each pair were clearly different. In both studies, we found a strong relation between liking and visual attention. Against our expectations, these effects were of similar magnitude for faces as for paintings. We conclude that the relation between liking and visual attention is not limited to biological objects but that its effects are domain general. The evolutionary function of the relation between liking and visual attention might stem from evolutionary adaptations, nonetheless, this link seems to be a rather basic phenomenon that applies across domains.
Specifics of reporting on cash flows in insurance companies
The activity of insurance and operation of insurance companies is very important in the context of development of financial organizations that operate in the territory of many countries, including the Republic of Serbia. A report that is of crucial importance for insurance companies in the context of an adequate cash flow management is a cash flow statement. Bearing in mind the specificity of the insurance industry, as well as the risks associated with it, cash flow is the basic focus of financial management. For insurance companies, it presents an overview of cash flows that occurred during the previous accounting period. The aim of the paper is to show the importance of efficient cash flow management in insurance companies from the aspect of their planning, and to this effect, the paper provides the simulation of the internal report on cash flows that is done monthly for domestic insurance companies in the function of efficient liquidity management of the insurance company.