scholarly journals SLC2A12 of SLC2 Gene Family in Bird Provides Functional Compensation for the Loss of SLC2A4 Gene in Other Vertebrates

Author(s):  
Ying Xiong ◽  
Fumin Lei

Abstract Avian genomes are small and lack some genes that are conserved in the genomes of most other vertebrates including nonavian sauropsids. One hypothesis stated that paralogs may provide biochemical or physiological compensation for certain gene losses; however, no functional evidence has been reported to date. By integrating evolutionary analysis, physiological genomics, and experimental gene interference, we clearly demonstrate functional compensation for gene loss. A large-scale phylogenetic analysis of over 1,400 SLC2 gene sequences identifies six new SLC2 genes from nonmammalian vertebrates and divides the SLC2 gene family into four classes. Vertebrates retain class III SLC2 genes but partially lack the more recent duplicates of classes I and II. Birds appear to have completely lost the SLC2A4 gene that encodes an important insulin-sensitive GLUT in mammals. We found strong evidence for positive selection, indicating that the N-termini of SLC2A4 and SLC2A12 have undergone diversifying selection in birds and mammals, and there is a significant correlation between SLC2A12 functionality and basal metabolic rates in endotherms. Physiological genomics have uncovered that SLC2A12 expression and allelic variants are associated with insulin sensitivity and blood glucose levels in wild birds. Functional tests have indicated that SLC2A12 abrogation causes hyperglycemia, insulin resistance, and high relative activity, thus increasing energy expenditures that resemble a diabetic phenotype. These analyses suggest that the SLC2A12 gene not only functionally compensates insulin response for SLC2A4 loss but also affects daily physical behavior and basal metabolic rate during bird evolution, highlighting that older genes retain a higher level of functional diversification.

2020 ◽  
Author(s):  
Peisen Su ◽  
Jun Yan ◽  
Wen Li ◽  
Liang Wang ◽  
Jinxiao Zhao ◽  
...  

Abstract Background: Salt and drought are the main abiotic stresses that restrict the yield of crops. Peroxidases (PRXs) are involved in various abiotic stress responses. Furthermore, only few wheat PRXs have been characterized in the mechanism of the abiotic stress response.Results: In this study, a novel wheat peroxidase (PRX) gene named TaPRX-2A, a member of wheat class III PRX gene family, was cloned and its response to salt stress was characterized. Based on the identification and evolutionary analysis of class III PRXs in 12 plants, we proposed an evolutionary model for TaPRX-2A, suggesting that occurrence of some exon fusion events during evolution. We also detected the positive selection of PRX domain in 13 PRXs involving our evolutionary model, and found 2 or 6 positively selected sites during TaPRX-2A evolution. Quantitative reverse transcription–polymerase chain reaction (qRT–PCR) results showed that TaPRX-2A exhibited relatively higher expression levels in root tissue than those exhibited in leaf and stem tissues. TaPRX-2A expression was also induced by abiotic stresses and hormone treatments such as polyethylene glycol 6000, NaCl, hydrogen peroxide (H2O2), salicylic acid (SA), methyljasmonic acid (MeJA) and abscisic acid (ABA). Transgenic wheat plants with overexpression of TaPRX-2A showed higher tolerance to salt stress than wild-type (WT) plants. Confocal microscopy revealed that TaPRX-2A-eGFP was mainly localized in cell nuclei. Survival rate, relative water content, and shoot length were higher in TaPRX-2A-overexpressing wheat than in the WT wheat, whereas root length was not significantly different. The activities of s superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were enhanced in TaPRX-2A-overexpressing wheat compared with those in the WT wheat, resulting in the reduction of reactive oxygen species (ROS) accumulation and malondialdehyde (MDA) content. The expression levels of downstream stress-related genes showed that RD22, TLP4, ABAI, GST22, FeSOD, and CAT exhibited higher expressions in TaPRX-2A-overexpressing wheat than in WT under salt stress.Conclusions: The results show that TaPRX-2A plays a positive role in the response to salt stress by scavenging ROS and regulating stress-related genes.


2019 ◽  
Vol 4 ◽  
pp. 193 ◽  
Author(s):  
Thomas D. Otto ◽  
Sammy A. Assefa ◽  
Ulrike Böhme ◽  
Mandy J. Sanders ◽  
Dominic Kwiatkowski ◽  
...  

The var gene family of the human malaria parasite Plasmodium falciparum encode proteins that are crucial determinants of both pathogenesis and immune evasion and are highly polymorphic. Here we have assembled nearly complete var gene repertoires from 2398 field isolates and analysed a normalised set of 714 from across 12 countries. This therefore represents the first large scale attempt to catalogue the worldwide distribution of var gene sequences We confirm the extreme polymorphism of this gene family but also demonstrate an unexpected level of sequence sharing both within and between continents. We show that this is likely due to both the remnants of selective sweeps as well as a worrying degree of recent gene flow across continents with implications for the spread of drug resistance. We also address the evolution of the var repertoire with respect to the ancestral genes within the Laverania and show that diversity generated by recombination is concentrated in a number of hotspots. An analysis of the subdomain structure indicates that some existing definitions may need to be revised From the analysis of this data, we can now understand the way in which the family has evolved and how the diversity is continuously being generated. Finally, we demonstrate that because the genes are distributed across the genome, sequence sharing between genotypes acts as a useful population genetic marker.


2020 ◽  
Author(s):  
Peisen Su ◽  
Jun Yan ◽  
Wen Li ◽  
Liang Wang ◽  
Jinxiao Zhao ◽  
...  

Abstract Background: Salt and drought are the main abiotic stresses that restrict the yield of crops. Peroxidases (PRXs) are involved in various abiotic stress responses. Furthermore, only few wheat PRXs have been characterized in the mechanism of the abiotic stress response.Results: In this study, a novel wheat peroxidase (PRX) gene named TaPRX-2A, a member of wheat class III PRX gene family, was cloned and its response to salt stress was characterized. Based on the identification and evolutionary analysis of class III PRXs in 12 plants, we proposed an evolutionary model for TaPRX-2A, suggesting that occurrence of some exon fusion events during evolution. We also detected the positive selection of PRX domain in 13 PRXs involving our evolutionary model, and found 2 or 6 positively selected sites during TaPRX-2A evolution. Quantitative reverse transcription–polymerase chain reaction (qRT–PCR) results showed that TaPRX-2A exhibited relatively higher expression levels in root tissue than those exhibited in leaf and stem tissues. TaPRX-2A expression was also induced by abiotic stresses and hormone treatments such as polyethylene glycol 6000, NaCl, hydrogen peroxide (H2O2), salicylic acid (SA), methyljasmonic acid (MeJA) and abscisic acid (ABA). Transgenic wheat plants with overexpression of TaPRX-2A showed higher tolerance to salt stress than wild-type (WT) plants. Confocal microscopy revealed that TaPRX-2A-eGFP was mainly localized in cell nuclei. Survival rate, relative water content, and shoot length were higher in TaPRX-2A-overexpressing wheat than in the WT wheat, whereas root length was not significantly different. The activities of s superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were enhanced in TaPRX-2A-overexpressing wheat compared with those in the WT wheat, resulting in the reduction of reactive oxygen species (ROS) accumulation and malondialdehyde (MDA) content. The expression levels of downstream stress-related genes showed that RD22, TLP4, ABAI, GST22, FeSOD, and CAT exhibited higher expressions in TaPRX-2A-overexpressing wheat than in WT under salt stress.Conclusions: The results show that TaPRX-2A plays a positive role in the response to salt stress by scavenging ROS and regulating stress-related genes.


2020 ◽  
Author(s):  
Peisen Su ◽  
Jun Yan ◽  
Wen Li ◽  
Liang Wang ◽  
Jinxiao Zhao ◽  
...  

Abstract Background: Salt and drought are the main abiotic stresses that restrict the yield of crops. Peroxidases (PRXs) are involved in various abiotic stress responses. Furthermore, only few wheat PRXs have been characterized in the mechanism of the abiotic stress response.Results: In this study, a novel wheat peroxidase (PRX) gene named TaPRX-2A, a member of wheat class III PRX gene family, was cloned and its response to salt stress was characterized. Based on the identification and evolutionary analysis of class III PRXs in 12 plants, we proposed an evolutionary model for TaPRX-2A, suggesting that occurrence of some exon fusion events during evolution. We also detected the positive selection of PRX domain in 13 PRXs involving our evolutionary model, and found 2 or 6 positively selected sites during TaPRX-2A evolution. Quantitative reverse transcription–polymerase chain reaction (qRT–PCR) results showed that TaPRX-2A exhibited relatively higher expression levels in root tissue than those exhibited in leaf and stem tissues. TaPRX-2A expression was also induced by abiotic stresses and hormone treatments such as polyethylene glycol 6000, NaCl, hydrogen peroxide (H2O2), salicylic acid (SA), methyljasmonic acid (MeJA) and abscisic acid (ABA). Transgenic wheat plants with overexpression of TaPRX-2A showed higher tolerance to salt stress than wild-type (WT) plants. Confocal microscopy revealed that TaPRX-2A-eGFP was mainly localized in cell nuclei. Survival rate, relative water content, and shoot length were higher in TaPRX-2A-overexpressing wheat than in the WT wheat, whereas root length was not significantly different. The activities of s superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were enhanced in TaPRX-2A-overexpressing wheat compared with those in the WT wheat, resulting in the reduction of reactive oxygen species (ROS) accumulation and malondialdehyde (MDA) content. The expression levels of downstream stress-related genes showed that RD22, TLP4, ABAI, GST22, FeSOD, and CAT exhibited higher expressions in TaPRX-2A-overexpressing wheat than in WT under salt stress.Conclusions: The results show that TaPRX-2A plays a positive role in the response to salt stress by scavenging ROS and regulating stress-related genes.


2020 ◽  
Author(s):  
Huilin Xiao ◽  
Chaoping Wang ◽  
Nadeem Khan ◽  
Mengxia Chen ◽  
Weihong Fu ◽  
...  

Abstract Background : The class III peroxidases (PODs) are involved in a broad range of physiological activities, such as the formation of lignin, cell wall components, defense against pathogenicity or herbivore, and abiotic stress tolerance. The POD family members have been well-studied and characterized by bioinformatics analysis in several plant species, but no previous genome-wide analysis has been carried out of this gene family in grapevine to date. Results : We comprehensively identified 47 PODs in the grapevine genome and are further classified into 7 subgroups based on their phylogenetic analysis. Results of motif composition and gene structure organization analysis revealed that PODs in the same subgroup shared similar conjunction while the protein sequences were highly conserved. Intriguingly, the integrated analysis of chromosomal mapping and gene collinearity analysis proposed that both dispersed and tandem duplication events contributed to the expansion of PODs in grapevine. Also, the gene duplication analysis suggested that most of the genes (20) were dispersed followed by (15) tandem, (9) segmental or whole-genome duplication, and (3) proximal, respectively. The evolutionary analysis of PODs, such as Ka/Ks ratio of the 15 duplicated gene pairs were less than 1.00, indicated that most of the gene pairs exhibiting purifying selection and 7 pairs underwent positive selection with value greater than 1.00. The Gene Ontology Enrichment (GO), Kyoto Encyclopedia of Genes Genomics (KEGG) analysis, and cis-elements prediction also revealed the positive functions of PODs in plant growth and developmental activities, and response to stress stimuli. Further, based on the publically available RNA-sequence data, the expression patterns of PODs in tissue-specific response during several developmental stages revealed diverged expression patterns. Subsequently, 30 genes were selected for RT-PCR validation in response to (NaCl, drought, and ABA), which showed their critical role in grapevine. Conclusions : In conclusion, we predict that these results will lead to novel insights regarding genetic improvement of grapevine.


2021 ◽  
Vol 9 (1) ◽  
pp. e001939
Author(s):  
Francesco Franchi ◽  
Dmitry M Yaranov ◽  
Fabiana Rollini ◽  
Andrea Rivas ◽  
Jose Rivas Rios ◽  
...  

IntroductionCurrent dietary guidelines recommend limiting sugar intake for the prevention of diabetes mellitus (DM). Reduction in sugar intake may require sugar substitutes. Among these, D-allulose is a non-calorie rare monosaccharide with 70% sweetness of sucrose, which has shown anti-DM effects in Asian populations. However, there is limited data on the effects of D-allulose in other populations, including Westerners.Research design and methodsThis was a prospective, randomized, double-blind, placebo-controlled, crossover study conducted in 30 subjects without DM. Study participants were given a standard oral (50 g) sucrose load and randomized to placebo or escalating doses of D-allulose (2.5, 5.0, 7.5, 10.0 g). Subjects crossed-over to the alternate study treatment after 7–14 days of wash out. Plasma glucose and insulin levels were measured at five time points: before and at 30, 60, 90 and 120 min after ingestion.ResultsD-allulose was associated with a dose-dependent reduction of plasma glucose at 30 min compared with placebo. In particular, glucose was significantly lower with the 7.5 g (mean difference: 11; 95% CI 3 to 19; p=0.005) and 10 g (mean difference: 12; 95% CI 4 to 20; p=0.002) doses. Although glucose was not reduced at the other time points, there was a dose-dependent reduction in glucose excursion compared with placebo, which was significant with the 10 g dose (p=0.023). Accordingly, at 30 min D-allulose was associated with a trend towards lower insulin levels compared with placebo, which was significant with the 10 g dose (mean difference: 14; 95% CI 4 to 25; p=0.006). D-allulose did not reduce insulin at any other time point, but there was a significant dose-dependent reduction in insulin excursion compared with placebo (p=0.028), which was significant with the 10 g dose (p=0.002).ConclusionsThis is the largest study assessing the effects of D-allulose in Westerners demonstrating an early dose-dependent reduction in plasma glucose and insulin levels as well as decreased postprandial glucose and insulin excursion in subjects without DM. These pilot observations set the basis for large-scale investigations to support the anti-DM effects of D-allulose.Trial registration numberNCT02714413.


Author(s):  
Yongxian Tian ◽  
Qigang Wang ◽  
Hao Zhang ◽  
Ningning Zhou ◽  
Huijun Yan ◽  
...  

1981 ◽  
Vol 59 (8) ◽  
pp. 818-823 ◽  
Author(s):  
Gen Yoshino ◽  
Tsutomu Kazumi ◽  
Soichiro Morita ◽  
Shighaki Baba

Plasma insulin and glucagon responses to oral glucose loading were examined in rats with islet cell tumors induced by a single intravenous injection of streptozotocin (30 or 40 mg/kg body weight). Twenty-four macroscopic and six microscopic tumors occurred in 21 rats. In 15 of 21 tumor-bearing rats, there was exaggerated insulin release in response to oral glucose. Plasma glucose levels did not rise with the oral glucose load and were comparable to those seen in normal animals. Hence these rats are described as having "responsive tumors." In six rats with "nonresponsive tumors" there was no insulin response and the plasma glucose levels rose. No significant differences in plasma glucagon levels were observed between the two groups. Nonresponsive tumors as well as responsive tumors contained a significant amount of extractable insulin (17.68 ± 8.60 and 35.07 ± 10.05 mg/g wet weight, respectively) and detectable amounts of immunoreactive glucagon (1.47 ± 0.61 and 2.24 ± 0.67 μg/g wet weight, respectively).These results suggest that a small dose of streptozotocin produces two types of islet cell tumors. One is insulin producing and insulin secreting whereas the other is insulin producing but not insulin secreting.


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