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Optimization of spectrofluorimetric assay for screening of opine dehydrogenase mutant libraries
No full textOpine dehydrogenase from Desulfohalobium retbaense was identified through a sequence-based
screening of a metagenomic library.1
The gene-encoding enzyme was subsequently heterologously
expressed in Escherichia coli to facilitate its functional characterization. To enhance the enzyme’s
catalytic efficiency, a mutant library was generated via error-prone PCR, to identify variants
exhibiting improved activity. A fluorescent assay was meticulously developed and optimized
to screen these variants, employing L-alanine, pyruvate, and NADH as substrates in a 50mM
sodium phosphate buffer at pH 7.5.2
Initial screening results indicated the presence of several
promising mutants with potential for enhanced specific enzymatic activity. These candidates are
undergoing further validation to confirm the mutations and assess their stability and efficiency.
Future work will focus on a detailed biochemical characterization of these mutants, which may
provide insights into the structure-function relationships governing opine dehydrogenase activity.
These optimized enzymes could also hold potential for industrial applications where enhanced
catalytic properties are desirable
Enhancing seed germination of Ocimum basilicum by Bacillus spp.
No full textBasil (Ocimum basilicum L.) is widely used in traditional medicine, pharmaceuticals, cosmetics, nutraceuticals, and food industries due to its aromatic profile and health benefits from its phenolic and flavonoid compounds. It is also a common spice for enhancing the aroma and flavour of meals in various cultures. Treating seeds with selected PGP (plant growth promoting) bacteria can enhance germination efficiency by inducing a physiological state favourable for seed germination through various mechanisms, such as nutrient solubilisation, production of growth hormones, and biocontrol of pathogens. Also, bio-inoculants based on these beneficial bacteria could reduce the dependency on chemical fertilizers and pesticides, thereby mitigating environmental pollution and promoting soil health. Therefore, the aim of this research was a preliminary evaluation of the effects of Bacillus spp. on seed germination of basil in vitro. Seed germination test was performed by filter paper methods on Petri dishes. Basil seeds were treated by Bacillus spp. soil isolates (BHC 2.3 and BHC 2.4), by soaking seeds in overnight bacterial culture. Bacterial isolates were selected based on their previously determined antifungal activity against different Fusarium phytopathogens and the ability to produce indole-3-acetic acid (IAA). After 10 days of experiment, the relative seed germination index (RSGI%) was determined by comparing the number of germinated seeds in treated seeds and untreated control. Results showed that basil seeds treated by isolate BHC 2.4 and BHC 2.3 had RSGI values of 108.69% and 96.65%, respectively. These results indicate the potential of selected Bacillus spp. isolates to enhance germination of basil seeds. Future research should focus on optimizing the application methods and formulations of bio-inoculants based on Bacillus spp. to maximize their effectiveness under semi-controlled conditions and field experiments in order to offer alternative approaches in sustainable agricultural practices
Spectroscopic Investigation of Tomato Seed Germination Stimulated by Trichoderma spp.
No full textSeed germination is a complex process that can be negatively affected by numerous stresses.
Trichoderma spp. are known as effective biocontrol agents as well as plant growth and germination
stimulators. However, understanding of the early interactions between seeds and Trichoderma spp.
remains limited. In the present paper, Fourier-transform infrared spectroscopy (FTIR) and Raman
spectroscopy were used to reveal the nature of tomato seed germination as stimulated by Trichoderma.
A rapid response of tomato seeds to Trichoderma spp. was observed within 48 h on Murashige and
Skoog medium (MS) substrate, preceding any physical contact. Raman analysis indicated that both
Trichoderma species stimulated phenolic compound synthesis by triggering plant-specific responses in
seed radicles. The impact of T. harzianum and T. brevicompactum on two tomato cultivars resulted in
alterations to the middle lamella pectin, cellulose, and xyloglucan in the primary cell wall. The Raman
spectra indicated increased xylan content in NA with T9 treatment as well as increased hemicelluloses
in GZ with T4 treatment. Moreover, T4 treatment resulted in elevated conjugated aldehydes in
lignin in GZ, whereas the trend was reversed in NA. Additionally, FTIR analysis revealed significant
changes in total protein levels in Trichoderma spp.-treated tomato seed radicles, with simultaneous
decreases in pectin and/or xyloglucan. Our results indicate that two complementary spectroscopic
methods, FTIR and Raman spectroscopy, can give valuable information on rapid changes in the plant
cell wall structure of tomato radicles during germination stimulated by Trichoderma spp
High-temperature humidity sensing ability of rare-earth-doped barium cerate
No full textAcceptor-doped perovskites with large lattice constants have been known as proton
conductors. The ability to conduct protons at high temperatures makes them suitable for
humidity sensors in a high-temperature environment. In this study, the rare-earth-doped
barium cerate powders were synthesized by the auto-combustion method and processed into
thick porous films (60 to 70 % porosity) to investigate the water vapor sensing properties in the
400 to 700 °C temperature range. All samples showed a stable sensitivity to water vapor in the
whole temperature range, expressed as impedance ratio in dry and wet argon (ǀZǀdryAr / ǀZǀwetAr),
and were able to detect 0.03 vol.% of water vapor at 550 °C within the impedance range of
10 kΩ at 100 Hz. The sensitivity values increased with the partial pressure of water and
decreased with the temperature, whereas the maximal value of 3.41 reached the BCEu10
sample at 550 °C and pH2O = 4.28 kPa
Da li komunikacija postoji? Pristup informacijama u Srbiji za osobe sa invaliditetom
Get PDFPersons with disabilities often face barriers that hinder their ability to access information effectively. This study presents results of a survey which was conducted in the second half of 2022, on the topic of the accessibility of information for persons with disabilities in Serbia, as well as their means of communication. A convenience sample of 111 individuals with physical and/or sensory disabilities, with basic digital literacy, aged 18 to 59, was surveyed through the mediation of associations of persons with disabilities. The findings reveal the usage patterns, preferences, and challenges faced by individuals with disabilities in accessing information. It has been found that the internet (99.10%), social networks (91.89%), and specialized platforms (79.28%) are prominent sources of information. Although specialized applications for communication and telephone communication are widely used, personal contact communication (96.40% very often or often) is still the prevalent method of communication. Public institutions and state authorities are perceived as inadequately adapted to the needs of individuals with disabilities. The findings underscore the need for continued efforts to improve accessibility infrastructure and implement inclusive design principles to bridge the information gap for individuals with disabilities in Serbia.Uspostavljanje komunikacije predstavlja tranziciju iz individualnog ka kolektivnom, što je važan korak u procesu formiranja uređenog društva. Postizanje zadovoljavajućeg nivoa komunikacije za sve članove društva je imperativ u 21. veku. Poznato je da osobe sa invaliditetom otežano ostvaruju komunikaciju sa okolinom, i da se često suočavaju sa preprekama koje ih sprečavaju da efikasno pristupe informacijama. U tom smislu obaveza svake države je da obezbedi zakonsku regulativu za omogućavanje pristupačnosti informacija. U Republici Srbiji postoji zakonski i tehnološki okvir kojim se reguliše pristupačnost. Ova studija predstavlja rezultate istraživanja o dostupnosti informacija osobama sa invaliditetom u Srbiji, i o obrascima njihove komunikacije. Na osnovu istraživanja koje je izvršeno posredstvom udruženja osoba sa invaliditetom na uzorku od 111 osoba sa fizičkim i/ili senzornim invaliditetom starosti od 18 do 59 godina dat je uvid u obrasce komunikacije i obrasce pristupa informacijama, prioritete koje ove osobe imaju u pogledu komunikacije i pristupa informacijama, i izazove sa kojima se suočavaju. Predstavljeni su rezultati istraživanja o dostupnosti sredstava informisanja, i o mogućnostima da osobe sa invaliditetom poboljšaju svoju situaciju u pogledu pristupa informacijama. Utvrđeno je da su internet (99,10%), društvene mreže (91,89%) i specijalizovane platforme (79,28%) prominentni izvori informacija. Iako su specijalizovane aplikacije za komunikaciju i telefonska komunikacija u širokoj upotrebi, lični kontakt (96,40% je odgovorilo sa vrlo često i često) je i dalje preovlađujući način komunikacije. Javne institucije i državni organi se percipiraju kao neadekvatno prilagođeni potrebama osoba sa invaliditetom. Ovi rezultati naglašavaju potrebu za sprovođenjem kontinuiranih napora sa ciljem poboljšanja infrastrukture u Srbiji u cilju obezbeđivanja pristupačnosti, i potrebu za primenom principa inkluzivnog dizajna kako bi se premostio jaz između osoba sa invaliditetom i osoba koje nemaju invaliditet, u pogledu pristupa informacijama
The European perch (Perca fluviatilis) as an indicator of OCPs pollution in different types of reservoirs in Serbia
Get PDFThe aim of this study was to determine the concentrations of 17 organochlorine pesticides (OCPs) in muscle tissue of the European perch from six reservoirs in Serbia with different properties and used for different purposes: electricity generation (Vlasina, Zaovine, and Perućac), recreation (Lake Sava), and water supply (Garaši). A gas chromatography with mass spectrometric detection (GC-MS) was used for OCPs detections. The concentrations of aldrin, dieldrin, endrin, endrin aldehyde, α-HCH, β-HCH, γ-HCH, δ-HCH, endosulfan I, endosulfan II, endosulfan sulfate, 4,4′-DDT, heptachlor epoxide, and metoxychlor were not detected at any studied reservoir. On the other hand, we detected concentrations of 4,4′-DDE in one individual (17 μg kg-1) from Garaši, 4,4′-DDD in one individual (15 μg kg-1) from Garaši and two individuals (15 μg kg-1, 17 μg kg-1) from Zaovine, as well as heptachlor in two individuals (12 μg kg-1, 15 μg kg-1) from Zaovine and three individuals (9 μg kg-1, 11 μg kg-1, 12 μg kg-1) from Lake Sava. Concentrations of analyzed OCPs did not exceed the proscribed maximum residue levels (MRLs). Therefore, we can conclude that meat of European perch from all investigated reservoirs is safe for human consumption regarding these pesticides
Are the invasive alien species suitable as bioindicators for the assessment of the genotoxic potential in aquatic ecosystems?
No full textDue to their wide distribution in ecosystems, invasive alien species draw attention as potential sentinel organisms. The Chinese pond mussel Sinanodonta woodiana is an invasive alien species distributed throughout the Danube catchment. Our previous passive biomonitoring study has shown that S. woodiana is less sensitive in the detection of water genotoxicity using the comet assay compared to the native representatives of Unio sp. The sensitivity in response of invasive and native mussels to pollution was further investigated by comet test in active biomonitoring studies at highly contaminated sites in the Belgrade area. First, it was found that exposure of the native species U. tumidus and U. pictorum to sites contaminated with untreated wastewater increased DNA damage in hemocytes. In the current study, the genotoxic effect of untreated wastewater on the haemocytes of S. woodiana was evaluated. Specimens were exposed to one uncontaminated site (Ada) and two sites close to wastewater outlets but with different
levels of pollution (Sajam-highly polluted site and Belgrade Waterfront-less polluted site). The basic chemical parameters and Escherichia coli in the water were analysed as indicators of pollution. A statistically significant increase in DNA damage was found only between the laboratory group and the Belgrade Waterfront site. An increase in highly damaged nuclei was also observed at this site. The lack of response at the Sajam site indicates that this species may have certain adaptations to overcome environmental stress at overpolluted sites and that they may include valve closure or filtration rate reduction. Therefore, the E. coli concentration in the visceral mass and the intervalvular fluid of mussels at these two sites was quantified and compared. The number of E. coli was lower in the specimens at the Sajam site, suggesting that valve closure may indeed be a mechanism of protection against environmental stress
Structural, ferroelectric and magnetic properties of Bi5Ti3FeO15 Aurivillius-based multiferroic materials
No full textLately, considerable attention has been given to developing magnetoelectric-active materials in microelectronics and spintronics [1]. Among many structures from the Aurivillius family, BisFeTb01s (BFT) provides the development of ferro electricity and magnetism and allows different site substitutions to improve the material's properties [2]. The main motivation was to investigate the influence of partial substitution of isovalent y3+ and rare-earth Gd3+ ions on A-site bismuth ions, and Co2+ on B-site iron ions to improve magnetic and electric properties [3].
Polycrystalline ceramics of pure and doped BFT were prepared by conventional solid-state reaction (according to formulas: Bis-xYxTbFe01s, Bis-xGdxFeTb01s; x = 0.1, 0.2, 0.3 and BisTbFe1-yCoy01s, y = 0.1, 0.3, 0.5). Crystal structure, phase purity, and structural evaluation were investigated via X-ray diffraction, Rietveld refinement, and Raman spectroscopy. The size of unmodified BFT plate-like grains was approximately 3-5 µm in length and 0.5 µm in thickness. With Y, Gd, and Co incorporation, the grain size decreased while the size reduction was more pronounced for Co substitution than for the other two dopants. Ferroelectric measurements show unsaturated leaky hysteresis loops in all samples. However, the decrease of the leakage current by Y and Gd doping implies a decrease in electrical conductivity. On the other hand, this substitution at A-site is not capable of inducing any magnetic ordering while Co2+ substitution enhanced the magnetic response of BFT.
Finally, it can be proposed that the best multiferroic properties at room temperature can only be achieved by co-substitution with aliovalent transition-metal ions in the B-sites ions (Fe and Ti) of the perovskite block of Aurivillius structure
A Phytopharmacological Properties of the Essential Oil of Lavender (Lavandula angustifolia Mill.) against Gastrointestinal Nematodes of Sheep
No full textGastrointestinal nematodes represent parasites of great importance in veterinary medicine, especially in grazing animals such as small ruminants. In most cases, these parasites cause subclinical diseases with losses in body weight, reduced feed intake and decreased production. However, high worm burdens may lead to severe clinical signs such as anorexia, anemia, diarrhea, protein loss, edema, decreased immunity and fertility, which can lead to fatal outcomes. Therefore, gastrointestinal nematodes hinder sheep farming in different ways leading to high economic losses that are estimated at several hundred million euros in Europe, although it is difficult to quantify it precisely. An additional problem is the development of anthelmintic resistance in nematodes that occur as a result of irrational use of commercial drugs, whereby the main risk factors are overfrequent treatments, underdosing, the use of only one drug without combination or rotation etc. This leads to a decrease in their effectiveness, and consequently to even higher economic losses (an additional 35-40 million euros). Moreover, these costs will tend to increase in the future due to widespread of resistance and the occurrence of multiresistant strains. For these reasons, the focus of nowadays research is finding alternative solutions including genetic selection of naturally resistant animals, pasture management, dietary manipulation, biological control (use of nematophagous fungi, bacteria or earthworms and dung beetles) and the use of plant-based formulations such as extracts and essential oils. All of the above strategies have shown promise, although it appears that none of them could be used independently. Therefore, future strategies for the control of gastrointestinal nematodes should be based on an integrated approach. This implies the combination of mentioned alternatives with rational use of anthelmintics based on refugia strategies (target treatments and target selective treatments)
The curious case of a hybrid common swift (Apus apus)
No full textSwifts are highly specialized birds, with three species breeding in Europe and migrating to Africa in winter: the common swift (Apus apus), the alpine swift (Apus melba), and the pallid swift (Apus pallidus). In southern Europe, local breeders include the little swift (Apus affinis) and the white-rumped swift (Apus caffer). The common swift has a broad breeding range from Spain and Ireland across Europe to Norway and sub-Arctic Russia, extending to China, Siberia, North Africa, and the Middle East, with its migration to Equatorial and sub-Equatorial Africa. DNA was extracted from the feathers of common swift nestlings in Belgrade, Serbia in 2023 to assess genetic diversity. Genotyping was performed by amplifying and sequencing the mitochondrial NADH dehydrogenase subunit 2 (ND2) gene and introns of three autosomal genes (locus 12884, β-fibrinogen intron 7 - fib7, and GAPDH). The ND2 sequence confirmed the maternal ancestry of Apus apus. Unexpectedly, the analysis of the 12884 intron sequence pointed to possible hybridization, with two different copies detected: one from A. apus and a longer copy suggesting potential hybridization with A. affinis, A. horus, or A. pacificus. The fib7 and GAPDH intron sequences were not informative due to the lack of interspecies differentiation. Given the species distribution, hybridization most likely involved A. affinis, whose breeding range overlaps with A. apus in southern Europe, North Africa, and parts of the Middle East. This information gives valuable new insights into the swift population dynamics and interspecies relationships