In this study, laboratory bioassays were performed to investigate the impact of sublethal concentrations of Cu (CuCl2: 1000, 100, 10 mg L−1), Pb (PbCl2: 10, 1, 0.1 mg L−1) and Cd (CdCl2: 0.1, 0.01, ...0.001 mg L−1) on honey bee redox status and the activity of the main antioxidative enzymes and their gene expression. Our results show that exposure to these metals led to significant changes of gene expression, the levels of enzyme activity and redox status, but the effects are metal and dose dependent. In general, exposure of 48 h to given concentrations of Cu, Cd and Pb did not change the activity of antioxidative enzymes and the level of lipid peroxidation, with the exception of decreased activity of catalase at the lowest concentration of cadmium. Only lead produced increases in glutathione and thiol groups. Expression of genes for catalase and superoxide dismutase changed with exposure to cadmium and copper, whilst lead induced only expression of superoxide dismutase genes. The results from this study provide basic data for future research regarding the impacts of metal pollution on Apis mellifera and will be an important step towards a comprehensive risk assessment of the environmental stressors on honey bees.
•Insights from laboratory experiments open the way for further field experiments.•Sublethal concentrations of Cu, Pb and Cd were applied.•Cu, Pb and Cd induced gene expression of antioxidant genes in dose dependent manner.•The lowest concentration of cadmium decreased activity of catalase.•Lead induced increases in glutathione and thiol groups.
In the present study, the influence of cadmium, copper, and lead on two enzymes often used as biomarkers in toxicological analysis was investigated. Bees were fed with 1 M sucrose solution containing ...10-fold serial dilutions of CuCl
2
(1000 mg L
−1
, 100 mg L
−1
, and 10 mg L
−1
), CdCl
2
(0.1 mg L
−1
, 0.01 mg L
−1
, and 0.001 mg L
−1
), or PbCl
2
(10 mg L
−1
, 1 mg L
−1
, and 0.1 mg L
−1
) during 48 h. Our results showed that the total glutathione
S-
transferase activity was not changed under the influence of cadmium and lead, and it was decreased with the highest concentration of copper. The level of gene expression of the three analyzed classes of glutathione
S-
transferase was significantly increased with increasing concentrations of copper and cadmium. Lead did not cause significant changes in glutathione
S-
transferase activity and gene expression, while it showed biphasic effect on acetylcholinesterase activity: lower concentration of lead, 0.1 mg L
−1
inhibited and higher dose, 10 mg L
−1
induced acetylcholinesterase activity in honey bees. Furthermore, our results showed a significant decrease of the acetylcholinesterase activity in honey bees treated with 0.001 and 0.01 mg L
−1
CdCl
2
. Our results indicate the influence of cadmium, copper, and lead on GST and AChE in the honey bees. These results form the basis for future research on the impact of metallic trace element pollution on honey bees.
Metallothioneins are ubiquitous proteins important in metal homeostasis and detoxification. However, they have not previously been identified in honey bees or other Hymenoptera, where ...metallothioneins could be of ecophysiological and ecotoxicological significance. Better understanding of the molecular responses to stress induced by toxic metals could contribute to honey bee conservation. In addition, honey bee metallothionein could represent a biomarker for monitoring environmental quality. Here we identify and characterize a metallothionein gene in Apis mellifera (AmMT). AmMT is 1,680 bp long and encodes a 48 amino acids protein with 15 cysteines and no aromatic residues. A metal response element upstream of the start codon, coupled with numerous cis‐regulatory elements indicate the functional context of AmMT. Molecular modelling predicts several transition metal binding sites, and comparative phylogenetic analysis revealed five putative metallothionein proteins in three other hymenoptera species. AmMT was characterized by cloning the full‐length coding sequence of the putative metallothionein. Recombinant AmMT was found to increase metal tolerance upon overexpression in Escherichia coli supplemented with Cd, Cu or Pb. Finally, in laboratory tests on honey bees, gene expression profiles showed a dose‐dependant relationship between Cd, Cu and Pb concentrations present in food and AmMT expression, while field experiments showed induction of AmMT in bees from an industrial site compared to those from an urban area. These studies suggest that AmMT has metal binding properties in agreement with a possible role in metal homeostasis. Further functional and structural characterization of metallothionein in honey bees and other Hymenoptera are necessary.
Understanding the cellular stress response in honey bees will significantly contribute to their conservation. The aim of this study was to analyze the response of the antioxidative enzymes superoxide ...dismutase and catalase in honey bees related to the presence of toxic metals in different habitats. Three locations were selected: (i) Tunovo on the mountain Golija, as control area, without industry and large human impact, (ii) Belgrade as urban area, and (iii) Zajača, as mining and industrial zone. Our results showed that the concentrations of lead (Pb) in whole body of bees vary according to habitat, but there was very significant increase of Pb in bees from investigated industrial area. Bees from urban and industrial area had increased expression of both Sod1 and Cat genes, suggesting adaptation to increased oxidative stress. However, in spite increased gene expression, the enzyme activity of catalase was lower in bees from industrial area suggesting inhibitory effect of Pb on catalase.
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•GC–MS sugar/polyol pattern for non- vs. diapausing O. nubilalis larvae was analyzed.•Glycerol, trehalose, sorbitol, mio-inositol, glucose and fructose were identified.•Glycerol and ...trehalose are the most abundant compounds in diapausing larvae.•In mid diapause, cold induced elevated glycerol and reduction of other polyols.•Low temperature increased content of all tested sugars at the end of diapause.
The European corn borer (ECB, Ostrinia nubilalis Hbn.) is a major pest in temperate regions of Europe and North America. Fifth instar ECB larvae enter diapause before winter and gradually develop cold hardiness. Here we investigated the combined influence of diapause phase and low temperature on sugar and polyol content in ECB larvae. Larvae in mid-diapause or diapause termination were acclimated at 5 °C, −3°C or −16 °C, and sugar and polyol content was measured using GC–MS. Control GC–MS measurements were conducted on untreated non-diapausing larvae. We detected differences in polyol (glycerol, sorbitol, myo-inositol) and sugar (trehalose, fructose, glucose) levels in diapausing versus non-diapausing larvae. Glycerol and trehalose were the most abundant of all analyzed cryoprotective compounds in diapausing larvae. Exposure of diapausing larvae to decreasing temperatures induced changes in polyol and sugar levels that depended on the phase of diapause. In mid-diapause larvae, decreasing temperatures induced a significant increase in glycerol and a decrease in sorbitol and myo-inositol. In larvae at diapause termination, polyol content was lower and less influenced by decreasing temperatures. In contrast, sugar levels were lower in larvae at mid-diapause versus diapause termination. Exposure of larvae to −16 °C induced a significant increase in the levels of all detected sugars. In particular, glucose levels were significantly higher in larvae at diapause termination following exposure to −16 °C. We propose that this shift toward sugar synthesis following low temperature exposure in larvae at diapause termination is a consequence of NADPH dependent polyol synthesis, and may be a mechanism for preservation of carbon reserves needed for post-diapause development.
The development of new therapeutic options focused on the recovery of patients with schizophrenia is primarily conditioned by elucidating the biological underpinnings of the disorder. The kynurenine ...pathway of tryptophan catabolism is the focus of psychiatric research since its catabolites have neuroactive properties, and one of the most important is the effect of kynurenic acid as the only endogenous NMDA receptor antagonist. According to the kynurenine hypothesis, there is an imbalance of excitatory and neuroprotective metabolites of the kynurenine pathway in patients with schizophrenia. It is postulated that excessive production of kynurenic acid leads to excessive blockade of NMDA glutamate and alpha-7 nicotinic receptors, acting as a trigger for the development of psychotic symptoms and neurocognitive deficits. This paper aims to review the kynurenine hypothesis of schizophrenia, important findings of studies exploring metabolites of the kynurenine pathway in patients with schizophrenia, and findings from the research on the potential impact of proinflammatory cytokines on the kynurenine pathway.
The purpose of this paper isto identify the scope of Generation Z's participation in the process of collaboration with brands in Serbia and to study the potentials in the future. Collaboration ...between Generation Z (GenZ) and brands in the digital world and intensive era of social media marketing has two roles: GenZ as co-creators and influencers. The aim of the research isto measure statistically significant differences in the answers of the respondents in relation to the examined opinions, needs, attitudes and intentions of the members of GenZ regarding the process of collaboration (co-creators and influencers). In January & February 2021 the research was conducted with 303 respondents of GenZ in the online survey. The results show that almost 70% of members of GenZ believe that organizations should more often organize activities in which consumers participate. By involving GenZ in the process of collaboration with brand, product and service development, receiving regular feedback from them and engaging influencers, marketing and brand managers could work on creating unique solutions, added values and personalized experience. Serbian marketing and brand managers, working to strengthen the customer centricity approach, could apply research results, insights and recommendations to design more effective and efficient collaboration for their brands together with GenZ.
Diapause is a state of arrested development during which insects cope with many external and internal stressful factors. European corn borer, Ostrinia nubilalis, overwinters as a fifth instar ...freeze-tolerant diapausing larva. In order to explore diapause-linked stress tolerance processes, the expression of selected genes coding for stress-related proteins—glutathione S-transferase (Gst), thioredoxin (Trx), glutaredoxin (Grx), ferritin (Fer), metallothionein (Mtn), and heat shock proteins Hsp90, Hsc70, Hsp20.4, and Hsp20.1—was assessed in the fat body of diapause-destined, warm (22°C) and cold (5°C) acclimated diapausing larvae using the quantitative real-time PCR. Gene expression was normalised to mRNA transcripts for Actin and Rps03, and relative expression was calculated using non-diapausing larvae as a control group. During the initiation phase of diapause, the abundance of mRNA transcripts of Grx, Hsp90, Hsc70, and Hsp20.1 was significantly upregulated, Trx, Fer, Mtn, and Hsp20.1 were unchanged, while only Gst was clearly downregulated in comparison to non-diapause control. Later, in the early phase of diapause, the expression of most genes (except Trx and Hsp20.1) was upregulated in warm-acclimated larvae, while only Trx and Hsp90 were upregulated in cold-acclimated larvae. Furthermore, the relative expression of all genes (except Trx) increased gradually throughout the diapause in cold-acclimated larvae. This result indicates that the half-life of mRNAs is prolonged during diapause at low temperature, which may lead to a gradual accumulation of mRNA transcripts. Our results show that both diapause programming and temperatures affect the expression of stress-related genes in Ostrinia nubilalis.
The influence of VUCA (Volatility, Uncertainty, Complexity, Ambiguity) world and COVID-19 pandemic on micro, small and medium enterprises (MSMEs) sector has been significant. The objective of this ...paper is to analyze the consumer buying behavior during the COVID-19 crisis and its implications on future intentions, so as to propose the potential options for the development of new strategies according to the customers’ needs. Changes in consumer habits in the world and in Serbia are reviewed. The online consumer survey was conducted in Serbia April 23-29, 2020. The survey sample included 510 respondents. Quantitative statistical methods were used for analysis: descriptive and comparative statistics (χ2 test, regression, correlation). The survey data are comparable, in some segments, with the results of the McKinsey & Company survey conducted in 22 countries across the world. The results of empirical research indicate that consumer buying habits have changed in terms of consumption structure and purchasing methods. MSMEs with the strategic marketing orientation, aware of the customers’ needs in turbulent environment, are more capable to be innovative and have more chances to be competitive. Doing business in the time of the pandemic has opened new opportunities for business renovation via e-commerce. The contribution of the paper is a set of recommendations for MSMEs on how to gain competitiveness and visibility in the digital market. It is recommended to improve e-commerce in Serbia, based on the research results. They confirm that consumers are increasingly adopting new technologies and that the processes of innovation and digital transformation are in general getting significantly faster, so they represent an opportunity and condition for the work of Serbian MSMEs in the future new normal.
The paper deals with the value-based segmentation conducted on Millennials generation in Serbia. It presents the research findings of the five segments of the Serbian Millennials according to their ...values and life style. The subject of defining the set of segments was processed by conducting a cluster and factor analysis on the representative national sample of Millennials in Serbia. Once the cluster analysis discovered the segments, the next step was to understand the essence of the clusters or segments. The sample is consisted of 1000 respondents, reflecting the population structure of the Serbian generation Y according to gender, age, region and type of settlement (urban / rural). The analysis showed some quite interesting and in some parts contradictory results. The results of this survey are relevant for sociologists, strategists, communications professionals and managers who are interested in this generation of voters, consumers, employees, leaders and entrepreneurs.
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