| 1. |
- Barbero-Palacios, Laura, et al.
(författare)
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Herbivore diversity effects on Arctic tundra ecosystems : a systematic review
- 2024
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Ingår i: Environmental Evidence. - : BioMed Central (BMC). - 2047-2382. ; 13:1
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Forskningsöversikt (refereegranskat)abstract
- Background: Northern ecosystems are strongly influenced by herbivores that differ in their impacts on the ecosystem. Yet the role of herbivore diversity in shaping the structure and functioning of tundra ecosystems has been overlooked. With climate and land-use changes causing rapid shifts in Arctic species assemblages, a better understanding of the consequences of herbivore diversity changes for tundra ecosystem functioning is urgently needed. This systematic review synthesizes available evidence on the effects of herbivore diversity on different processes, functions, and properties of tundra ecosystems.Methods: Following a published protocol, our systematic review combined primary field studies retrieved from bibliographic databases, search engines and specialist websites that compared tundra ecosystem responses to different levels of vertebrate and invertebrate herbivore diversity. We used the number of functional groups of herbivores (i.e., functional group richness) as a measure of the diversity of the herbivore assemblage. We screened titles, abstracts, and full texts of studies using pre-defined eligibility criteria. We critically appraised the validity of the studies, tested the influence of different moderators, and conducted sensitivity analyses. Quantitative synthesis (i.e., calculation of effect sizes) was performed for ecosystem responses reported by at least five articles and meta-regressions including the effects of potential modifiers for those reported by at least 10 articles.Review findings: The literature searches retrieved 5944 articles. After screening titles, abstracts, and full texts, 201 articles including 3713 studies (i.e., individual comparisons) were deemed relevant for the systematic review, with 2844 of these studies included in quantitative syntheses. The available evidence base on the effects of herbivore diversity on tundra ecosystems is concentrated around well-established research locations and focuses mainly on the impacts of vertebrate herbivores on vegetation. Overall, greater herbivore diversity led to increased abundance of feeding marks by herbivores and soil temperature, and to reduced total abundance of plants, graminoids, forbs, and litter, plant leaf size, plant height, and moss depth, but the effects of herbivore diversity were difficult to tease apart from those of excluding vertebrate herbivores. The effects of different functional groups of herbivores on graminoid and lichen abundance compensated each other, leading to no net effects when herbivore effects were combined. In turn, smaller herbivores and large-bodied herbivores only reduced plant height when occurring together but not when occurring separately. Greater herbivore diversity increased plant diversity in graminoid tundra but not in other habitat types.Conclusions: This systematic review underscores the importance of herbivore diversity in shaping the structure and function of Arctic ecosystems, with different functional groups of herbivores exerting additive or compensatory effects that can be modulated by environmental conditions. Still, many challenges remain to fully understand the complex impacts of herbivore diversity on tundra ecosystems. Future studies should explicitly address the role of herbivore diversity beyond presence-absence, targeting a broader range of ecosystem responses and explicitly including invertebrate herbivores. A better understanding of the role of herbivore diversity will enhance our ability to predict whether and where shifts in herbivore assemblages might mitigate or further amplify the impacts of environmental change on Arctic ecosystems.
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| 2. |
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| 3. |
- Basaure, P., et al.
(författare)
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Learning, memory and the expression of cholinergic components in mice are modulated by the pesticide chlorpyrifos depending upon age at exposure and apolipoprotein E (APOE) genotype
- 2019
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Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 93:3, s. 693-707
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Tidskriftsartikel (refereegranskat)abstract
- Polymorphisms of the apolipoprotein E (APOE) gene differentially affect neurobiological functions and cognitive performance and confer different vulnerabilities to subclinical exposures to chlorpyrifos (CPF), a pesticide used worldwide. The data reported on this topic suggest a complex interaction between cholinergic signaling and the APOE genotype. To gain greater functional insight into this interaction, we evaluated spatial learning and memory and hippocampal cholinergic expression in young apoE3 and apoE4 transgenic mice exposed to CPF. Male and female mice were exposed to CPF at 0 or 1 mg/kg on postnatal days 10-15 and then, exposed to CPF at 0 or 2 mg/kg for 60 days at 5 months of age. At 6 months of age, mice were tested for spatial skills in a Barnes maze. At the end of the task, animals were killed and gene expression of cholinergic components was assessed in the hippocampus. Our results show that apoE4 female mice performed worse in the spatial task, while postnatal CPF impaired escape strategies and spatial memory in apoE3 mice. In turn, CPF in adulthood improved spatial abilities in apoE4 female mice. Regarding gene expression, choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) expression were increased in apoE4 mice. Postnatal exposure to CPF increased ChAT mRNA levels in apoE4 mice, whereas adult exposure to CPF induced changes in acetylcholinesterase-S, alpha 7- and alpha 4-subunit nicotinic receptor expression in apoE4 females. The current findings provide new insights into APOE-dependent cholinergic signaling, which directly affects the response to CPF cholinergic insult, especially in APOE4 subjects.
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| 4. |
- Basaure, P., et al.
(författare)
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Postnatal chlorpyrifos exposure and apolipoprotein E (APOE) genotype differentially affect cholinergic expression and developmental parameters in transgenic mice
- 2018
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Ingår i: Food and Chemical Toxicology. - : Elsevier BV. - 0278-6915. ; 118, s. 42-52
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Tidskriftsartikel (refereegranskat)abstract
- Chlorpyrifos (CPF) is one of the most commonly used organophosphate pesticides in the world. Our previous results described that apolipoprotein E (APOE) polymorphisms are a source of individual differences in susceptibility to CPF. The aim of this study was to assess the physical and biochemical effects of postnatal exposure to CPF in the apoE targeted replacement mouse model. Mice were exposed to CPF at 0 or 1 mg/kg/day from postnatal day 10–15. Physical development, plasma and forebrain cholinesterase (ChE) activity and gene expression in liver and forebrain were evaluated. CPF exposure delays physical maturation and decreases the expression of choline acetyltransferase, α4-subunit and the α7 receptor. CPF decreases the expression of vesicular acetylcholine transporter (VAChT) mRNA in the forebrain only in apoE3 mice. The expression of paraoxonase-2 in the forebrain was also influenced by APOE genotype and CPF. Differences between genotypes were observed in litter size, ChE activity, expression of butyrylcholinesterase and paraoxonase-1 in liver and variants of acetylcholinesterase, VAChT and the α7 receptor in the forebrain. These results support that there are different vulnerabilities to postnatal CPF exposure according to the APOE polymorphism, which in turn affects the cholinergic system and defenses to oxidative stress. © 2018 Elsevier Ltd
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| 5. |
- Guardia-Escote, L., et al.
(författare)
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APOE genetic background and sex confer different vulnerabilities to postnatal chlorpyrifos exposure and modulate the response to cholinergic drugs
- 2019
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Ingår i: Behavioural Brain Research. - : Elsevier BV. - 0166-4328. ; 376
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Tidskriftsartikel (refereegranskat)abstract
- Chlorpyrifos (CPF) is an extensively used organophosphate pesticide. Exposure to CPF has been related to neurobehavioral disorders, particularly during neurodevelopment. Apolipoprotein E (apoE) is a lipid and cholesterol carrier and a susceptibility factor for cognitive impairment which can influence the response to toxic exposures. The study was aimed at assessing the effects of postnatal exposure to CPF on object recognition memory and its modulation by sex and APOE genotype. Human apoE3 and apoE4 targeted replacement mice and C57BL/6 mice were postnatally exposed to 0 or 1 mg/kg/day of CPF. Recognition memory was evaluated in an Object Recognition Test (ORT). In order to study the contribution of cholinergic and GABAergic neurotransmitter systems to recognition memory, a pharmacological challenge was included. Sex, genotype and postnatal exposure to CPF were key factors throughout the testing period. Specifically, CPF increased exploratory behavior and impaired discrimination performance. We observed that administering scopolamine, a cholinergic antagonist, was detrimental to recognition memory. However, discrimination in C57BL/6 and apoE4 males improved with the administration of the cholinergic agonist rivastigmine, but the same drug worsened retention in apoE4 females. Finally, the GABAergic agonist alprazolam altered performance in a sex- and genotype-dependent manner. Overall, these results suggest complex interactions between sex, APOE genotype and postnatal CPF exposure and indicate a different functioning of both the cholinergic and GABAergic neurotransmitter system between groups. © 2019 Elsevier B.V.
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| 6. |
- Guardia-Escote, L., et al.
(författare)
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Sex and Exposure to Postnatal Chlorpyrifos Influence the Epigenetics of Feeding-Related Genes in a Transgenic APOE Mouse Model: Long-Term Implications on Body Weight after a High-Fat Diet
- 2021
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- Developmental exposure to toxicants and diet can interact with an individual's genetics and produce long-lasting metabolic adaptations. The different isoforms of the apolipoprotein E (APOE) are an important source of variability in metabolic disorders and influence the response to the pesticide chlorpyrifos (CPF). We aimed to study the epigenetic regulation on feeding control genes and the influence of postnatal CPF exposure, APOE genotype, and sex, and how these modifications impact on the metabolic response to a high-fat diet (HFD). Both male and female apoE3- and apoE4-TR mice were exposed to CPF on postnatal days 10-15. The DNA methylation pattern of proopiomelanocortin, neuropeptide Y, leptin receptor, and insulin-like growth factor 2 was studied in the hypothalamus. At adulthood, the mice were given a HFD for eight weeks. The results highlight the importance of sex in the epigenetic regulation and the implication of CPF treatment and APOE genotype. The body weight progression exhibited sex-dimorphic differences, apoE4-TR males being the most susceptible to the effects induced by CPF and HFD. Overall, these results underscore the pivotal role of sex, APOE genotype, and developmental exposure to CPF on subsequent metabolic disturbances later in life and show that sex is a key variable in epigenetic regulation.
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| 7. |
- Hernández-Alvarez, María Isabel, et al.
(författare)
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Deficient Endoplasmic Reticulum-Mitochondrial Phosphatidylserine Transfer Causes Liver Disease
- 2019
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Ingår i: Cell. - : Cell Press. - 0092-8674 .- 1097-4172. ; 177:4, s. 881-895.e17
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Tidskriftsartikel (refereegranskat)abstract
- Non-alcoholic fatty liver is the most common liver disease worldwide. Here, we show that the mitochondrial protein mitofusin 2 (Mfn2) protects against liver disease. Reduced Mfn2 expression was detected in liver biopsies from patients with non-alcoholic steatohepatitis (NASH). Moreover, reduced Mfn2 levels were detected in mouse models of steatosis or NASH, and its re-expression in a NASH mouse model ameliorated the disease. Liver-specific ablation of Mfn2 in mice provoked inflammation, triglyceride accumulation, fibrosis, and liver cancer. We demonstrate that Mfn2 binds phosphatidylserine (PS) and can specifically extract PS into membrane domains, favoring PS transfer to mitochondria and mitochondrial phosphatidylethanolamine (PE) synthesis. Consequently, hepatic Mfn2 deficiency reduces PS transfer and phospholipid synthesis, leading to endoplasmic reticulum (ER) stress and the development of a NASH-like phenotype and liver cancer. Ablation of Mfn2 in liver reveals that disruption of ER-mitochondrial PS transfer is a new mechanism involved in the development of liver disease.
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| 8. |
- Olsen, Laura K., et al.
(författare)
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Viral mimetic priming enhances α-synuclein-induced degeneration : implications for Parkinson's disease
- 2019
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Ingår i: Brain, behavior, and immunity. - : Elsevier. - 0889-1591 .- 1090-2139. ; 80, s. 525-535
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Tidskriftsartikel (refereegranskat)abstract
- Evidence is accumulating to suggest that viral infections and consequent viral-mediated neuroinflammation may contribute to the etiology of idiopathic Parkinson’s disease. Moreover, viruses have been shown to influence α-synuclein oligomerization as well as the autophagic clearance of abnormal intra-cellular proteins aggregations, both of which are key neuropathological events in Parkinson’s disease pathogenesis. To further investigate the interaction between viral-mediated neuroinflammation and α-synuclein aggregation in the context of Parkinson’s disease, this study sought to determine the impact of viral neuroinflammatory priming on α-synuclein aggregate-induced neuroinflammation and neurotoxicity in the rat nigrostriatal pathway. To do so, male Sprague-Dawley rats were intra-nigrally injected with a synthetic mimetic of viral dsRNA (poly I:C) followed two weeks later by a peptidomimetic small molecule which accelerates α-synuclein fibril formation (FN075). The impact of the viral priming on α-synuclein aggregation-induced neuroinflammation, neurodegeneration and motor dysfunction was assessed. We found that prior administration of the viral mimetic poly I:C significantly exacerbated or precipitated the α-synuclein aggregate induced neuropathological and behavioral effects. Specifically, sequential exposure to the two challenges caused a significant increase in nigral microgliosis (p < 0.001) and astrocytosis (p < 0.01); precipitated a significant degeneration of the nigrostriatal cell bodies (p < 0.05); and precipitated a significant impairment in forelimb kinesis (p < 0.01) and sensorimotor integration (p < 0.01). The enhanced sensitivity of the nigrostriatal neurons to pathological α-synuclein aggregation after viral neuroinflammatory priming further suggests that viral infections may contribute to the etiology and pathogenesis of Parkinson’s disease.
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| 9. |
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| 10. |
- Peris-Sampedro, Fiona, et al.
(författare)
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New mechanistic insights on the metabolic-disruptor role of chlorpyrifos in apoE mice: a focus on insulin- and leptin-signalling pathways
- 2018
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Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 92:5, s. 1717-1728
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Tidskriftsartikel (refereegranskat)abstract
- Recently, we have provided evidence, suggesting that mice expressing the human apolipoprotein E3 (apoE3) are more prone to develop an obesity-like phenotype and a diabetic profile when subchronically fed a chlorpyrifos (CPF)-supplemented diet. The aim of the current study was to examine the underlying mechanisms through which CPF alters both insulin- and leptin-signalling pathways in an APOE-dependent manner. Both adult apoE3- and E4-targeted replacement and C57BL/6 mice were exposed to CPF at 0 or 2 mg/kg body weight/day through the diet for 8 consecutive weeks. We determined the expression of JAK2, p-JAK2, STAT3, p-STAT3, SOCS3, IRS-1, p-IRS-1, AKT, p-AKT, GSK3 beta, p-GSK3 beta, and apoE in the liver, as well as hepatic mRNA levels of pon1, pon2, and pon3. CPF markedly disrupted both leptin and insulin homeostasis, particularly in apoE3 mice. Indeed, only CPF-fed apoE3 mice exhibited an increased phosphorylation ratio of STAT3, as well as increased total SOCS3 protein levels. Similarly, the exposure to CPF drastically reduced the phosphorylation ratio of both AKT and GSK3 beta, especially in apoE3 mice. Overall, CPF reduced the expression of the three pon genes, principally in C57BL/6 and apoE3 mice. These results provide notable mechanistic insights on the metabolic effects of the pesticide CPF, and attest the increased vulnerability of apoE3 carriers to its metabolic-disruptor role.
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