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Bees are vitally important in natural and agricultural ecosystems, providing key pollination services to wild plants and crops. Increasing reports of regional declines of bee populations have attracted intense attention worldwide. Challenges to bee health are multifactorial and include poor nutrition, heat stress, agrochemicals, and pathogens. The impact of heat stress is a relatively minor factor in current bee declines compared with agrochemicals and pathogens. However, heat stress has adverse impacts on foraging activity, pollination services, task-related physiology, immunocompetence, reproductive capacity, growth, and development of bees, and these adverse impacts are variable in different bee species. Heat stress–related damage to bees receives extra attention when it is accompanied by climate change. Heat-tolerance mechanisms are key enablers for bee survival under high-temperature stress conditions, and we now understand that both behavior and molecular regulation strongly impact the ability of bees to reduce damage from heat stress. In this review, we summarize and synthesize previous findings about the detrimental effects of heat stress to bees and discuss the strategies bees use to cope with heat stress. Bee species mentioned here are mainly honeybees, bumblebees, and stingless bees, with a focus on the honeybee Apis mellifera. [ABSTRACT FROM AUTHOR]

As predominant pollinators, honeybees are important for crop production and terrestrial ecosystems. Recently, various environmental stresses have led to large declines in honeybee populations in many regions. The ability of honeybees to respond to these stresses is critical for their survival. However, the details of the stress defense mechanisms of honeybees have remained elusive. Here, we found that the Nuclear Factor Y (NF-Y) family (containing NF-YA, NF-YB, and NF-YC) is a novel stress mediator family that regulates honeybee environmental stress resistance. NF-YA localized in the nucleus, NF-YB accumulated in the cytoplasm, and NF-YC presented in both the nucleus and cytoplasm. NF-YC interacted with NF-YA and NF-YB in vitro and in vivo, and the nuclear import of NF-YB relied on its interaction with NF-YC. We further found that the expression of NF-Y was induced under multiple stress conditions. In addition, NF-Y regulated many stress responses and antioxidant genes at the transcriptome-wide level, and knockdown of NF-Y repressed the expression of stress-inducible genes, particularly LOC108003540 and LOC107994062, under adverse circumstances. Silencing NF-Y lowered honeybee stress resistance by reducing total antioxidant capacity and enhancing oxidative impairment. Collectively, these results indicate that NF-Y plays important roles in stress responses. Our study sheds light on the underlying defense mechanisms of honeybees under environmental stress. [ABSTRACT FROM AUTHOR]

Apis cerana cerana is a native bee species in China and plays a key role in agricultural production and ecological balance. However, the growth and development of Apis cerana cerana has not been smooth, and pesticide and heavy metal stress are key factors that have forced a dramatic decline in population size. This study was performed with the objective of investigating the role of AccCDK20 and AccCDKN1 in honey bee resistance to pesticide and heavy metal stress. RT–qPCR analysis revealed that AccCDK20 transcript levels were highest in brown-eyed pupae and AccCDKN1 transcript levels were highest in 1-day-old worker bees. In different tissues and body parts of adult bees, AccCDK20 transcript levels were highest in the head, and AccCDKN1 transcript levels were highest in the thorax. It was further observed that environmental stress can affect the transcript levels of the AccCDK20 and AccCDKN1 genes. Silencing of the AccCDK20 and AccCDKN1 genes resulted in altered activities of antioxidant-related genes and antioxidant-related enzymes. AccCDK20 and AccCDKN1 transcript levels were upregulated under glyphosate stress, and silencing of the genes resulted in reduced resistance to glyphosate and greatly increased mortality in Apis cerana cerana. In addition, gene function was verified by in vitro repression assays. Overexpression of the AccCDK20 and AccCDKN1 proteins in E. coli cells increased the resistance to ROS damage induced by CHP. In conclusion, AccCDK20 and AccCDKN1 play an indispensable role in honey bee resistance to pesticide and heavy metal stress. [Display omitted] • Silencing AccCDK20 and AccCDKN1 affects the oxidative system. • AccCDK20 and AccCDKN1 promote honey bee resistance to glyphosate stress. • Overexpression of AccCDK20 and AccCDKN1 enhances the antioxidant capacity of E. coli. [ABSTRACT FROM AUTHOR]

The cyclin-dependent kinase (CDK) protein family plays an important role in regulating life functions, such as the cell cycle and metabolism. This study reports the first cloning and functional analysis of A. cerana cerana CDK1 (AccCDK1). The distribution profile of AccCDK1 in different developmental periods and different tissues was determined. The experimental results showed that the distribution of AccCDK1 was tissue-specific. AccCDK1 distribution at the transcriptional and translational levels was affected by stress conditions induced by H 2 O 2 , UV, HgCl 2 , CdCl 2 , extreme temperatures (4 °C, 44 °C) and pesticides (avermectin, lambda-cyhalothrin, haloxyfop- R -methyl, and glyphosate), which resulted in changes in the expression levels. These results suggest that AccCDK1 may have an important part to play in honey bee resistance to stress. The expression of a recombinant AccCDK1 protein in vitro enhanced the antistress capacities of E. coli and yeast, which suggests that AccCDK1 is related to the stress response. When AccCDK1 was silenced, the expression of some antioxidant genes was downregulated, and the enzymatic potencies of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were reduced, which suggests that AccCDK1 takes part in the body's resistance to oxidative stress upon external stimulation by influencing relevant antioxidants. Notably, the survival rate of A. cerana cerana under high-temperature-induced stress decreased after AccCDK1 silencing, which verifies our results. In conclusion, we found that AccCDK1 played an indispensable function in resisting oxidative stress and maintaining normal cellular functions. [Display omitted] • Oxidative stress can affect the expression of cyclin-dependent kinase1. • AccCDK1 silencing affects cellular antioxidant genes and enzymes. • AccCDK1 promotes the survival of eukaryotic and prokaryotic cells under stress. • AccCDK1 promotes bees to resist high temperature stress. [ABSTRACT FROM AUTHOR]

Honeybees show an important pollination ability and play vital roles in improving crop yields and increasing plant genetic diversity, thereby generating tremendous economic benefits for humans. However, honeybee survival is affected by a number of biological and abiotic stresses, including the effects of fungi, bacteria, viruses, parasites, and especially agrochemicals. Glyphosate, a broad-spectrum herbicide that is primarily used for weed control in agriculture, has been reported to have lethal and sublethal effects on honeybees. Here, we summarize recent advances in research on the effects of glyphosate on honeybees, including effects on their behaviors, growth and development, metabolic processes, and immune defense, providing a detailed reference for studying the mechanism of action of pesticides. Furthermore, we provide possible directions for future research on glyphosate toxicity to honeybees. [ABSTRACT FROM AUTHOR]

Abstract: Glutathione S-transferases (GSTs) are multifunctional enzymes that are mainly involved in detoxification of endogenous and xenobiotic compounds and oxidative stress resistance in insects. In this study, we identified a sigma class GST from Apis cerana cerana (AccGSTs4). The open reading frame of cDNA was 612bp and encoded a 203 amino acid polypeptide, which exhibited the structural motif and domain organization characteristic of GST. Homology and evolutionary analysis indicated that the induced amino acid sequence of AccGSTs4 belonged to an insect sigma class group. Expression analysis indicated that AccGSTs4 was presented in all stages of development with high level in 4th instar larvae. Immunolocalization further revealed the distribution of AccGSTs4 in 4th instar larvae. RT-qPCR showed that the transcripts of AccGSTs4 from the larvae were upregulated under dietary HgCl2. The GST activity under stress was higher than the controls fed on HgCl2-free diet. Disc diffusion assay provided evidence of recAccGSTs4 resistance to long-term exposure of HgCl2 stress. Additionally, analysis of 5′-flanking region further clarified the probable expression patterns of AccGSTs4. Taken together, our findings indicate that the larvae AccGSTs4 may play a role in mercury stress response, and it will help to protect honeybees from heavy metals. [Copyright &y& Elsevier]

Nucleoside diphosphate kinases (NDPKs) are widespread nucleotide-metabolizing enzymes that are involved in a variety of biological processes, including responses to oxidative stress. Although studies have been conducted on NDPKs in mammals and some plants, there is scant research on insect NDPKs, especially in honey bees. In the present study, we isolated AccNDPK from Apis cerana cerana. Sequence analysis showed that AccNDPK has high homology with many NDPKs and contains a highly conserved NDPK active site motif. Based on phylogenetic analysis, AccNDPK has a relatively recent evolutionary relationship with NDPKs in other hymenopteran insects. AccNDPK was found to be highly expressed in newly emerged honey bees and muscle tissues, and RT-qPCR analysis and bacteriostatic assays showed that the expression level of AccNDPK is affected by abnormal temperature, UV light, H 2 O 2 , heavy metals, and various pesticides. After AccNDPK knockdown, antioxidant-related genes, including AccCAT , AccCYP4G11 , AccGSTS4 , AccTpx1 and AccMsrA , were upregulated, whereas AccGSTD , AccGST1 , AccHSP22.6 and AccTrx1 were downregulated. Furthermore, catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) activities were significantly increased, and the tolerance of bees to oxidative stress caused by cyhalothrin was reduced by silencing of AccNDPK. Given these findings, we speculate that AccNDPK plays an important role in the oxidative stress response of A. cerana cerana. [Display omitted] • AccNDPK was induced by various environmental stresses. • Expression of recombinant AccNDPK enhances resistance of E. coli to oxidative stress. • Knockdown of AccNDPK affected several antioxidant-related genes and the activities of antioxidant-related enzymes. • The tolerance to cyhalothrin of A. cerana cerana was reduced after AccNDPK knockdown. [ABSTRACT FROM AUTHOR]