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West Nile virus (WNV) is a mosquito‐borne emerging virus in Europe with capacity to cause neurological complications such as encephalitis or meningoencephalitis in humans, birds or equids. In Spain, WNV is actively circulating in mosquitoes, birds and horses in different regions, but never has been deeply studied in Extremadura. Therefore, the aim of this study was to evaluate the seroprevalence of WNV in equids of those areas and to analyse the risk factors associated with exposure to the virus. A total of 199 out of 725 equids presented antibodies against WNV by competition ELISA (27.45%), while 22 were doubtful (3.03%). Anti‐WNV IgM antibodies were detected in 16 equids (2.21%), and 3 animals were doubtful (0.41%). All ELISA‐reactive positive/doubtful sera (N = 226) were further tested by micro‐virus neutralization test (VNT), and a total of 143 horses were confirmed as positive for WNV, obtaining a seroprevalence of 19.72% in equids of western Spain. In addition, specific antibodies against USUV were confirmed in 11 equids. In 24 equids, a specific flavivirus species (detected by ELISA test) could not be determined. The generalized linear mixed‐effects models showed that the significant risk factors associated with individual WNV infection in equids were the age (adults) and hair coat colour (light), whereas in USUV infections, it was the breed (pure). Data demonstrated that WNV and USUV are circulating in regions of western Spain. Given the high WNV seroprevalence found in equids from the studied areas, it is important to improve the surveillance programmes of public health to detect undiagnosed human cases and to establish a vaccination programme in equid herds in these regions. [ABSTRACT FROM AUTHOR]

• Low temperature induces CpMYB106-like in the cold-tolerant 'Natura' fruit. • 'Natura' promoter, proMYB106A, shows higher basal expression. • Acclimation after cold stress increases GUS expression driven by proMYB106A. • Salt and MeJA upregulate both promoters, but most prominently proMYB106A. • CREs occurrence and distribution in 'Natura' promoter could lead to higher expression. Zucchini fruit (Cucurbita pepo L.) is susceptible to chilling injury (CI) during its postharvest life, with this response being cultivar-dependent. A previous transcriptomic analysis comparing cold-tolerant fruit from the cultivar 'Natura' with cold-sensitive fruit from the cultivar 'Sinatra', revealed the transcription factor (TF) CpMYB106-like as a relevant candidate gene for the acquisition of postharvest low-temperature tolerance. C. pepo has two CpMYB106-like paralogs, which are differentially present in the 'Natura' (CpMYB106-likeA) and 'Sinatra' (CpMYB106-likeB) cultivars due to gene and promoter deletions. The aim of this study was to investigate the transcriptional regulation of the CpMYB106-like paralogs to unravel their role in the postharvest life of zucchini fruit. For this, gene expression was analyzed and promoter sequences and their activities were studied through reporter β-glucuronidase (GUS) gene analysis in heterologous systems. An expression analysis showed that CpMYB106-like mRNA levels were induced only in the cold-stored fruit of 'Natura'. The analysis of the promoter sequences showed numerous cis -regulatory elements (CREs), many of which have a differential distribution or frequency between the two paralogs. Promoter basal activity was determined by transient transformation of Nicotiana benthamiana leaves, which showed a higher expression driven by the promoter from the cold-tolerant cultivar 'Natura', which could be explained by the presence of three additional copies of the enhancer element EECCRCAH1 in proMYB106A. The tissue-specific expression pattern, and the response to abiotic stresses and phytohormones controlled by CpMYB106-like promoters was analyzed in transgenic Arabidopsis thaliana plants. GUS activity was mainly detected in the vascular system, leaves, and inflorescences, especially in siliques. With respect to abiotic stresses, low temperature decreased GUS expression in Arabidopsis, but increased it in plants carrying the 'Natura' promoter after a 24-h acclimation period at 22 °C. Salt treatment induced GUS activity driven by both promoters in Arabidopsis seedlings, but it was higher with the 'Natura' promoter. Furthermore, methyl jasmonate (MeJA) also induced a sharp increase of GUS controlled by proMYB106A. These results suggest that the regulation of CpMYB106-like TFs in zucchini is promoter-driven, and reveal the involvement of these genes in the acquisition of cold tolerance in fruit during postharvest stress conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract This work examines the effect of a treatment with 1 mM of γ-aminobutyric acid (GABA) on zucchini fruit during postharvest cold storage. Specifically, the effect of GABA on postharvest quality was measured, as well as its implication in the GABA shunt and other related metabolic pathways. The treatments were performed in Sinatra, a variety of zucchini highly sensitive to low-temperature storage. The application of GABA improved the quality of zucchini fruit stored at 4 °C, with a reduction of chilling-injury index, weight loss, and cell death, as well as a lower rate of electrolyte leakage. GABA content was significantly higher in the treated fruit than in the control fruit at all times analyzed. At the end of the storage period, GABA-treated fruit had higher contents of both proline and putrescine. The catabolism of this polyamine was not affected by exogenous GABA. Also, over the long term, the treatment induced the GABA shunt by increasing the activities of the enzymes GABA transaminase (GABA-T) and glutamate decarboxylase (GAD). GABA-treated fruit contained higher levels of fumarate and malate than did non-treated fruit, as well as higher ATP and NADH contents. These results imply that the GABA shunt is involved in providing metabolites to produce energy, reduce power, and help the fruit to cope with cold stress over the long term. Highlights • Exogenous GABA improves cold tolerance in zucchini fruit. • GABA treatment increases the energy status and reduced power by GABA shunt. • GABA treatment increases the putrescine content. • Putrescine catabolism does not change by GABA treatment. • GABA shunt pathway is important in chilling tolerance in zucchini fruit. [ABSTRACT FROM AUTHOR]

Abscisic acid (ABA) plays an important role in the regulation of several stress responses such as drought, high salinity and low temperature being also proved as a key phytohormone for the acquisition of postharvest cold tolerance in zucchini fruit. Therefore, it would be of great interest to unravel the mechanisms implicated in the ABA response, using a metabolomic approach. The aim of this work has been to use a combination of metabolomic tools to identify the main metabolic pathways involved in ABA-mediated regulation of chilling tolerance in zucchini fruit. As a result of this study, it was found that ABA modulates the primary metabolism inducing the accumulation of some sugars, organic acids such as succinic acid and amino acids including histidine, serine, phenylalanine, glutamic acid and γ-aminobutyric acid, and that are involved in low-temperature tolerance. ABA treatment also activates the t-zeatin and riboflavin biosynthesis during the first days of cold storage which can be important signals in the ABA-mediated cold response to induce tolerance in zucchini fruit. [Display omitted] • Abscisic acid (ABA) improves postharvest quality of zucchini fruit. • Targeted metabolomics reveals an ABA modulation of the primary metabolism. • An accumulation of sugars, organic acids and amino acids induced chilling tolerance. • Secondary metabolism was also affected by ABA treatment. • ABA activates the t-zeatin and riboflavin biosynthesis at first day of cold stress. [ABSTRACT FROM AUTHOR]

Abscisic acid (ABA) is a key phytohormone in the regulation of most stress responses, which especially involve dehydration such as drought, high salinity, and low temperature. Under these stress conditions, plants accumulate ABA that triggers a response to cope with the adverse environment. In this study, we investigated the implication of ABA in the acquisition of chilling tolerance in zucchini during fruit postharvest. For that, we have analyzed ABA biosynthesis and response in fruit of two varieties with different chilling tolerance, ‘Natura’ (cold tolerant) and ‘Sinatra’ (cold sensitive). The results have showed that the biosynthesis of ABA was induced in ‘Natura’ fruit, with an increase of the abscisic aldehyde oxidase activity (AAO), and consequently an accumulation of ABA during the first day of exposition to cold. The levels of ABA showed a significant negative correlation with weight loss and chilling damage, and a positive correlation with firmness. Transcriptional analysis of some genes involved in ABA signaling and response, such as the ABA receptors PYL1 and PYL4, the transcription factors AI5L2/ABF3, NAC072/RD26, ATHB7, bHLH112, and the enzymes KAT2 as well as HDA6, a deacetylase involved in histone modification, presented different expression levels between varieties, showing ‘Natura’ the highest expression in most cases at least at short-term storage. Finally, to corroborate the role of ABA in cold tolerance, 5 mM of sodium tungstate (an inhibitor of ABA biosynthesis) was applied to ‘Natura’ fruit and 0.5 mM of ABA was applied to ‘Sinatra’ fruit and their postharvest behaviour at low temperature was followed. The treatment with tungstate induced cold-sensitivity in ‘Natura’ fruit, whereas ABA-treated ‘Sinatra’ fruit improved their quality during the storage at 4 °C. The results obtained point to ABA as a phytohormone responsible for the acquisition of postharvest cold tolerance. [ABSTRACT FROM AUTHOR]

Postharvest cold storage in zucchini fruit extends the commercial life but causes the appearance of chilling injury (CI), characterized by the development of pits and damaged areas at the surface of the fruit. This physiological disorder has been related to alterations of the cell wall metabolism in several fruit. We have analyzed the relationship between the development of CI and the changes that take place at the cell wall due to cold storage in zucchini fruit, as well as the effect of a preconditioning treatment on these changes. Microscopical observations have shown that the surface depressions detected in chilling injured fruit were caused by cell death and cell collapse. Low temperature induced the solubilization of the more soluble pectins, as evidenced by the highest levels of neutral sugars and uronic acids found in control fruit after the cold storage in water-soluble fraction (WSF) and CDTA-soluble fraction (CSF). The results obtained in Na 2 CO 3 -soluble fraction (NSF) for both parameters was opposite; higher levels were detected in preconditioned fruit and lower in more damaged fruit. The same behaviour was found in the base soluble hemicelluloses, 1 M KOH- and 4 M KOH-soluble fractions (1KSF and 4KSF), and in the insoluble cellulose content. Zucchini fruit stored at low temperature showed an increase of the enzymatic activities pectin methylesterase (PME), polygalacturonase (PG), and cellulase (CEL), and an accumulation of mRNA corresponding to a expansin (EXP) gene. Preconditioned fruit showed the lowest levels of these enzymatic activities. Microscopic analysis of CI fruit correlated with the biochemical changes observed in cell wall. Lignin content was higher in control than preconditioned fruit, suggesting a possible role of the lignification process in CI development in zucchini. [ABSTRACT FROM AUTHOR]

Polyamine metabolism has been suggested to be a crucial factor in the response of plants to several abiotic stresses, including low temperature. Zucchini fruit is susceptible to develop chilling injury when stored at low temperature. In this study, the effects of putrescine, spermidine and spermine treatment (1 mM) on the physiological behavior of zucchini fruit during cold storage were investigated, focusing on the changes in polyamine metabolism and in alterations of polyamine-related nitrogen metabolites and hormones. Among the polyamines used, exogenous application of putrescine was found to be the best treatment to improve postharvest cold tolerance. Treated fruit were of better quality, and in general after cold storage they showed reduced weight loss, chilling injury, and malondialdehyde and hydrogen peroxide contents. Putrescine treatment induced betaine and proline accumulation, fatty acid desaturase expression, and also changes in the biochemical GABA shunt pathway during cold storage. These responses may contribute to increased energy production in fruit treated with putrescine. In general, the putrescine treatment induced different pathways that are considered stress defense mechanisms, and we hypothesize that they could contribute to improve postharvest quality of zucchini fruit after storage at 4 °C. [ABSTRACT FROM AUTHOR]

In order to investigate the contribution of polyamines and related amino acids in the maintenance of zucchini fruit quality during cold storage, two varieties of Cucurbita pepo with different degrees of chilling tolerance were used, Natura (more tolerant) and Sinatra (moresensitive). After harvest, free putrescine levels decreased during storage at 20 °C, whereas in fruit kept at 4 °C this polyamine accumulated in both varieties, but with higher levels in the sensitive variety (Sinatra). This behavior suggests that putrescine is accumulated as a response to low temperature in zucchini fruit by stress-induced chilling injury, and not due to the postharvest storage itself. ADC activity responds quickly to chilling but sharply decreases after 14 days, whereas its expression remains high in both varieties. ODC activity takes over when the cold stress is relatively severe, as this activity was found to be much higher in Sinatra. ODCexpression also correlated with ODC activity. DAO activity increased in Natura fruit, and conversely decreased in Sinatra fruit during storage at 4 °C, whereas the proline content was higher in Natura and lower in Sinatra. Therefore, we suggest that putrescine degradation and proline accumulation contribute to the acquisition of chilling tolerance in zucchini fruit. GABA content decreased in both varieties, with a greater reduction in Natura fruit and less in Sinatra fruit. In addition, GABA transaminase showed a higher activity in Natura fruit than in Sinatra fruit during cold storage, suggesting that GABA catabolism could be involved in the tolerance to postharvest cold storage in zucchini fruit. [ABSTRACT FROM AUTHOR]

Highlights: [•] Carbohydrate content was determined in zucchini fruits during postharvest storage. [•] The raffinose is more likely related to dehydration than to chilling susceptibility. [•] Glucose, fructose, and pinitol could be involved in the adaptation to cold storage. [ABSTRACT FROM AUTHOR]

Zucchini fruit are marketed at an immature stage. Its subtropical origin makes zucchini fruit susceptible to chilling disorders when stored at low non-freezing temperatures. In this study, we have investigated the implication of treatment with putrescine (1 mM), that improves cold storage resistance, on the antioxidant mechanisms and carbohydrate content, and its correlation with the mechanisms that alleviate cold stress in zucchini fruit. Fruit treated with putrescine exhibited higher ascorbate peroxidase, catalase and glutathione reductase activities, and contained higher amounts of ascorbate, FRAP, glucose, fructose and raffinose than control fruit during cold storage. Furthermore, the treatment with putrescine reduced lipoxygenase activity. Our results show that a putrescine treatment, that alleviates chilling injury, also modulates antioxidant system and carbohydrate content in zucchini fruit under cold stress. This response could be due to the degradation of putrescine, and the induction of the γ‐aminobutyric acid (GABA) shunt pathway. [ABSTRACT FROM AUTHOR]

Vector-borne diseases like West Nile virus (WNV) pose a global health challenge, with rising incidence and distribution. Culex mosquitoes are crucial WNV vectors. Avian species composition and bird community diversity, along with vector communities, influence WNV transmission patterns. However, limited knowledge exists on their impact in southwestern Spain, an area with active WNV circulation in wild birds, mosquitoes, and humans. To address this, we conducted a comprehensive study investigating the contributions of migratory and exotic bird species to WNV transmission and the influence of mosquito community composition. Analysing 1194 serum samples from 44 avian species, we detected WNV antibodies in 32 samples from 11 species, four for the first time in Europe. Migratory birds had higher WNV exposure likelihood than native and exotic species, and higher phylogenetic diversity in bird communities correlated with lower exposure rates. Moreover, in 5859 female mosquitoes belonging to 12 species, we identified WNV competent vectors like Cx. pipiens s.l. and the Univittatus subgroup. Birds with WNV antibodies were positively associated with competent vector abundance, but negatively with overall mosquito species richness. These findings highlight the complex interactions between bird species, their phylogenetics, and mosquito vectors in WNV transmission. Understanding these dynamics will help to implement effective disease control strategies in southwestern Spain. [ABSTRACT FROM AUTHOR]

Usutu virus (USUV) is an emerging zoonotic arbovirus that has caused an increasing number of animal and human cases in Europe in recent years. Understanding the vector species and avian hosts involved in the USUV enzootic cycle in an area of active circulation is vital to anticipate potential outbreaks. Mosquitoes were captured in 2020, while wild birds were sampled in both 2020 and 2021 in Extremadura, southwestern Spain. The presence of USUV in the mosquito vectors was assessed by a real-time reverse transcription-polymerase chain reaction (rRT-PCR) assay and confirmed by sequencing amplicons from two generic RT-PCR sets for flaviviruses. Sequences were analysed phylogenetically. Bird sera were screened for flavivirus antibodies with a blocking ELISA kit and subsequently tested for virus-specific antibodies with a micro-virus-neutralization test. Overall, 6,004 mosquitoes belonging to 13 species were captured, including some well-known flavivirus vectors (Culex pipiens, Cx. perexiguus, and Cx. univittatus). Of the 438 pools tested, USUV was detected in two pools of Cx. pipiens. Phylogenetic analysis using a fragment of the NS5 gene assigned the USUV detected the Africa 3 lineage. Out of 1,413 wild birds tested, USUV-specific antibodies were detected in 17 birds (1.2%, 10 males and 7 females) from eight species. The first detection of USUV Africa 3 lineage in mosquitoes from Spain, together with serologically positive resident wild birds in urban and rural areas, indicates active circulation and a possible risk of exposure for the human population, with necessity to establish specific surveillance plans. [ABSTRACT FROM AUTHOR]

• A high prevalence and wide distribution of WNV were evidenced in wild birds from Spain. • Flavivirus specific antibodies were detected in 19 different species. • WNV was reported for the first time in Europe in a black stork (Ciconia nigra). • USUV was reported for the first time in Europe in a great bustard (Otis tarda). West Nile virus (WNV) is an emerging flavivirus transmitted generally by mosquitoes of Culex genus. It is maintained in an enzootic life cycle where birds act as reservoir hosts. Humans and horses are also susceptible to infection, and occasionally, they suffer from neurological complications. However, they do not transmit the virus to other vectors, behaving as dead-end hosts. Sporadic WNV outbreaks observed in horses and wild birds from Extremadura (western Spain) during 2016 and 2017 seasons prompted to carry out this survey in wild birds, focused on specimens coming from two wildlife rehabilitation centres. Between October 2017 and December 2019, samples from 391 wild birds, belonging to 56 different species were collected and analysed in search of evidence of WNV infection. The analysis of serum samples for WNV-specific antibodies by ELISA, whose specificity was subsequently confirmed by virus-neutralisation test (VNT) showed positive results in 18.23 % birds belonging to 18 different species. Pelecaniformes (33.33 %), Accipitriformes (25.77 %) and Strigiformes (22.92 %) orders had the higher seroprevalences. Remarkably, WNV-specific antibodies were found in a black stork for the first time in Europe. Analysis by real time RT-PCR in symptomatic birds confirmed the presence of WNV lineage 1 RNA in griffon vulture and little owls. Specificity analysis of ELISA positive and doubtful sera was performed by differential VNT titration against WNV and two other cross-reacting avian flaviviruses found in Spain: Usutu virus (USUV) and Bagaza virus (BAGV). Only four samples showed USUV-specific antibodies (1.04 %) corresponding to three species: Eurasian eagle-owl, griffon vulture and great bustard (first detection in Europe) whereas no samples were found reactive to BAGV. Differential VNT yielded undetermined flavivirus result in 16 samples (4.17 %). This is the first study carried out on wild birds from Extremadura (western Spain). It highlights the widespread circulation of WNV in the region and its co-circulation with USUV. [ABSTRACT FROM AUTHOR]

Background: The evaluation of quality of life related to health (HRQOL) has become an important prognostic indicator in HIV/AIDS. The aim of this study was to determine the impact of socio-demographic, clinical and psychological factors in HRQOL in a group of subjects with HIV/AIDS in northwestern Mexico and determine which variables best predict HRQOL. Methods: In a cross-sectional study with a sample of 87% of patients receiving care at a clinic for HIV/AIDS in northwestern Mexico between November 2010 to June 2011, we measure the HRQOL using the Tool Medical Outcomes Study HIV Health Survey (MOS-HIV). A model of multiple linear regression was performed to identify variables that allow us to predict HRQOL in this population. Results: In a sample of 54 subjects with HIV/AIDS. Patients had an average age of 43 ± 9 years, 83% were men with a mean time of 6.5 ± 4.5 years from diagnosis. HRQOL scores of physical and mental health of the participants were 57 ± 6 and 57 ± 13 respectively. In multivariate analysis, the variables that influenced the physical health punctuation were gender, marital status, sexual orientation, time since diagnosis and viral load (log). Conclusions: Prospective studies are needed to better explain the influence of the factors that predict changes or trends in HRQOL in patients with HIV/AIDS. [ABSTRACT FROM AUTHOR]

Immature, vegetable-like fruits are produced by crops of great economic importance, including cucumbers, zucchini, eggplants and bell peppers, among others. Because of their high respiration rates, associated with high rates of dehydration and metabolism, and their susceptibility to chilling injury (CI), vegetable fruits are highly perishable commodities, requiring particular storage conditions to avoid postharvest losses. This review focuses on the oxidative stress that affects the postharvest quality of vegetable fruits under chilling storage. We define the physiological and biochemical factors that are associated with the oxidative stress and the development of CI symptoms in these commodities, and discuss the different physical, chemical and biotechnological approaches that have been proposed to reduce oxidative stress while enhancing the chilling tolerance of vegetable fruits. [ABSTRACT FROM AUTHOR]

• Polysaccharidic coatings improve postharvest quality of zucchini fruit. • Dextrin enhances antioxidant defence diminishing chilling injury during storage. • Additives olive oil and oleuropein increase the ascorbate and phenolics content. • Dextrin-based coatings improve the nutraceutical properties of zucchini fruit. The use of edible coatings has surged as a response to the ever-increasing demand for ecologically-friendly methods for maintaining fruit quality during storage. This study analyses the application of different polysaccharide-based coatings, carboxymethylcellulose, chitosan, dextrin and starch, and the use of a plasticizer agent, glycerol, with dextrin shown to be the most effective in maintaining the postharvest quality of zucchini fruit during cold storage. Subsequently, to improve these results, the nutraceutical additives oleuropein and olive oil, were tested in combination with dextrin. Results showed that dextrin coatings reduced weight loss, chilling injury, and oxidative stress in zucchini fruit at low temperature, maintaining fruit quality. The natural additives obtained from the olive tree showed a higher induction of antioxidant enzymes as well as a greater accumulation of ascorbate and total phenolics, with the dextrin coating with olive oil being even more effective in maintaining the chilling injury low until the end of storage, associated to phenolic metabolism. This type of preservation could be implemented for extending postharvest life and enhancing the overall quality of zucchini fruit. [ABSTRACT FROM AUTHOR]

Given that external treatments with ABA had been proved to alleviate chilling injury in the immature zucchini fruit, an RNAseq analysis was conducted to gain insight into the molecular mechanisms that are involved in ABA-induced postharvest cold tolerance. Fruit from the cold sensitive cultivar Sinatra were treated with ABA and then stored for 14 d at 4 ºC. Exocarp samples from control and ABA-treated fruit were taken at 1, 5 and 14 d of cold storage, assessing the transcriptional changes during postharvest storage relative to freshly harvested fruit. The RNAseq analysis produced 229 million high-quality reads from a total of about 23,000 unigenes. Pairwise comparisons of differentially expressed genes (DEGs) in treated and untreated samples at each cold storage time resulted in 852, 793 and 1120 DEGs that were specifically found in the ABA-treated but not in the control fruit at either 1, 5 or 14 d of cold storage. This ABA-specific DEG list was subjected to a GO and KEGG enrichment analysis, as well as to a clusterization of gene expression profiles. This revealed the significance of certain metabolic and signaling pathways participating in ABA-induced postharvest cold tolerance, highlighting the relevance of the Ca2+ signaling pathway, as well as the positive regulation mediated by certain hormones such as ethylene and jasmonate, and the negative regulation mediated by others like auxins and brassinosteroids. A number of DEGs were also found in the ABA-treated fruit that code for transcription factors, as well as for genes involved in oxidative stress response and in membrane and cell wall metabolism. Data indicates that ABA-induced cold tolerance is not mediated by CBF-like genes but involve the up- and down-regulation of several transcription factors in the BZIP , GRAS , MYB , MYC , NAC and ZAT families that are known to participate as positive and negative regulators in the cold defensive response. Moreover, ABA regulates different genes responsible for reducing oxidative stress damage, inducing the biosynthesis of cuticular wax and repressing the biosynthesis of lignin, as well as protecting membrane and cell wall integrity in fruit cells during postharvest cold storage. • ABA induces postharvest cold tolerance in zucchini fruit independently of CBF pathway. • Specific roles of TFs and membrane and cell wall enzymes in postharvest cold response. • Ethylene, jasmonate, auxin and brassinosteroid mediate the ABA-induced cold tolerance. • Signaling genes for Ca2+ and MAPK are regulating zucchini postharvest cold tolerance. • Revealed genes could improve postharvest cold tolerance in zucchini fruit. [ABSTRACT FROM AUTHOR]