ABSTRACT
Mitochondrial genome sequencing is a valuable tool for investigating mitogenome evolution, species phylogeny, and population genetics. Chimonanthus praecox (L.) Link, also known as "La Mei" in Chinese, is a famous ornamental and medical shrub belonging to the order Laurales of the Calycanthaceae family. Although the nuclear genomes and chloroplast genomes of certain Laurales representatives, such as Lindera glauca, Laurus nobilis, and Piper nigrum, have been sequenced, the mitochondrial genome of Laurales members remains unknown. Here, we reported the first complete mitogenome of C. praecox. The mitogenome was 972,347 bp in length and comprised 60 unique coding genes, including 40 protein-coding genes (PCGs), 17 tRNA genes, and three rRNA genes. The skewness of the PCGs showed that the AT skew (-0.0096233) was negative, while the GC skew (0.031656) was positive, indicating higher contents of T's and G's in the mitochondrial genome of C. praecox. The Ka/Ks ratio analysis showed that the Ka/Ks values of most genes were less than one, suggesting that these genes were under purifying selection. Furthermore, there is a substantial abundance of dispersed repeats in C. praecox, constituting 16.98% of the total mitochondrial genome. A total of 731 SSR repeats were identified in the mitogenome, the highest number among the eleven available magnoliids mitogenomes. The mitochondrial phylogenetic analysis based on 29 conserved PCGs placed the C. praecox in Lauraceae, and supported the sister relationship of Laurales with Magnoliales, which was congruent with the nuclear genome evidence. The present study enriches the mitogenome data of C. praecox and promotes further studies on phylogeny and plastid evolution.
ABSTRACT
Myelin sheathes ensure the rapid conduction of neural impulse and provide nutritional support for neurons. Myelin sheathes are formed by differentiated oligodendrocytes (OLs) in the central nervous system. During OL development, the differentiation of oligodendrocyte progenitor cells (OPCs) into mature OLs is controlled by both positive differentiation factors (drivers) and negative regulatory factors (brakes). Previous studies have suggested Id2 and Id4 as the key negative factors for OL differentiation. However, these conclusions were mainly based on in vitro studies and the reported OL phenotype in Id4 mutants appear to be mild. In this study, we systematically investigated the in vivo function of Id2 and Id4 genes in OL differentiation in their genetic mutants and in embryonic chicken spinal cord. Our results showed that disruption of Id4 has no effect on OL differentiation and maturation, whereas Id2 mutants and Id2/Id4 compound mutants display a mild and transient precocity of OL differentiation. In agreement with these loss-of-function studies, Id2, but not Id4, is weakly expressed in OPCs. Despite their minor roles in OL differentiation, forced expression of Id2 and Id4 in embryonic chicken spinal cords strongly inhibit the differentiation of OPCs. Taken together, our detailed functional and expressional studies strongly suggest that Id2 and Id4 are not the major in vivo repressors of OPC differentiation during animal development, shedding new light on the molecular regulation of early OL development.
Subject(s)
Oligodendrocyte Precursor Cells , Oligodendroglia , Animals , Cell Differentiation/physiology , Central Nervous System/metabolism , Neurogenesis , Oligodendrocyte Precursor Cells/metabolism , Oligodendroglia/metabolism , Transcription Factors/metabolismABSTRACT
Hirschsprung disease (HSCR) has a higher incidence in children with Down syndrome (DS), which makes trisomy 21 a predisposing factor to HSCR. DSCAM and BACE2 are close together on the HSCR-associated critical region of chromosome 21. Common variants of DSCAM and rare variants of BACE2 were implicated to be associated with sporadic HSCR. However, the submucosal neuron defect of DS mouse model could not be rescued by normalization of Dscam. We aimed to explore the contribution of DSCAM and BACE2 to the development of the enteric nervous system (ENS) and HSCR susceptibility. We genotyped 133 tag single-nucleotide polymorphisms (SNPs) in DSCAM and BACE2 gene region in 420 HSCR patients and 1,665 controls of Han Chinese. Expression of DSCAM and BACE2 homologs was investigated in the developing gut of zebrafish. Overexpression and knockdown of the homologs were performed in zebrafish to investigate their roles in the development of ENS. Two DSCAM SNPs, rs430255 (P Addtive = 0.0052, OR = 1.36, 95% CI: 1.10-1.68) and rs2837756 (P Addtive = 0.0091, OR = 1.23, 95% CI: 1.05-1.43), showed suggestive association with HSCR risk. Common variants in BACE2 were not associated with HSCR risk. We observed dscama, dscamb, and bace2 expression in the developing gut of zebrafish. Knockdown of dscama, dscamb, and bace2 caused a reduction of enteric neurons in the hindgut of zebrafish. Overexpression of DSCAM and bace2 had no effects on neuron number in the hindgut of zebrafish. Our results suggested that common variation of DSCAM contributed to HSCR risk in Han Chinese. The dysfunction of both dscams and bace2 caused defects in enteric neuron, indicating that DSCAM and BACE2 might play functional roles in the occurrence of HSCR. These novel findings might shed new light on the pathogenesis of HSCR.
ABSTRACT
Unlike the flower of the model monocot rice, which has diverged greatly from the ancestral monocot flower, the pineapple (Ananas comosus) flower is more typical of monocot flowers. Here, we identified 43 pineapple genes containing MADS-box domains, including 11 type I and 32 type II genes. RNA-seq expression data generated from five pineapple floral organs (sepals, petals, stamens, pistils, and ovules) and quantitative real-time PCR revealed tissue-specific expression patterns for some genes. We found that AcAGL6 and AcFUL1 were mainly expressed in sepals and petals, suggesting their involvement in the regulation of these floral organs. A pineapple 'ABCDE' model was proposed based on the phylogenetic analysis and expression patterns of MADS-box genes. Unlike rice and orchid with frequent species-specific gene duplication and subsequent expression divergence, the composition and expression of the ABCDE genes were conserved in pineapple. We also found that AcSEP1/3, AcAG, AcAGL11a/b/c, and AcFUL1 were highly expressed at different stages of fruit development and have similar expression profiles, implicating these genes' role in fruit development and ripening processes. We propose that the pineapple flower can be used as a model for studying the ancestral form of monocot flowers to investigate their development and evolutionary history.
Subject(s)
Ananas/genetics , Flowers/genetics , MADS Domain Proteins/genetics , Amino Acid Sequence , Ananas/metabolism , Biological Evolution , Evolution, Molecular , Flowers/metabolism , Gene Duplication , Gene Expression , Gene Expression Regulation, Plant , MADS Domain Proteins/metabolism , Phylogeny , Protein Domains/genetics , Sequence Alignment/methods , Sequence Homology, Amino Acid , TranscriptomeABSTRACT
BACKGROUND: Hirschsprung's disease (HSCR) is the most common congenital cause of intestinal obstruction in children. Sotos syndrome (SoS) is an overgrowth disorder with constipation and sometimes accompanied by HSCR. NSD1 gene mutation is the main cause of SoS. We aimed to investigate association of NSD1 common single nucleotide polymorphisms (SNPs) with HSCR susceptibility in Chinese Han population. METHOD: We genotyped 15 SNPs encompassing NSD1 gene region in 420 HSCR patients and 1665 controls on Fludigm EP1 platform. Association analysis was performed between cases and controls. RESULT: Rs244709 was the most associated SNP with HSCR susceptibility of the sample set (PAllelic = 9.69 × 10-5, OR = 1.37, 95% CI: 1.17-1.61). Gender stratification analysis revealed that NSD1 SNPs were associated with HSCR in males, but not in females. The nonsynonymous coding SNP rs28932178 in NSD1 exon 5 represented the most significant signal in males (PAllelic = 6.43 × 10-5, OR = 1.42, 95% CI: 1.20-1.69). The associated SNPs were expression quantitative trait loci (eQTLs) of nearby genes in multiple tissues. NSD1 expression levels were higher in aganglionic colon tissues than ganglionic tissues (P = 3.00 × 10-6). CONCLUSION: NSD1 variation conferred risk to HSCR in males, indicating SoS and HSCR may share common genetic factors. IMPACT: This is the first study to reveal that NSD1 variation conferred risk to Hirschsprung's disease susceptibility in males of Chinese Han population, indicating Sotos syndrome and Hirschsprung's disease may share some common genetic background. This study indicates more attention should be paid to the symptom of constipation in patients with Sotos syndrome. Our results raise questions about the role of NSD1 in the development of enteric nervous system and the pathogenesis of Hirschsprung's disease.
Subject(s)
Genetic Predisposition to Disease , Genetic Variation , Hirschsprung Disease/genetics , Histone-Lysine N-Methyltransferase/genetics , Mutation , Polymorphism, Single Nucleotide , Alleles , Asian People , Biopsy , China/epidemiology , Exons , Female , Genotype , Humans , Linkage Disequilibrium , Male , Quantitative Trait Loci , Risk , Sotos Syndrome/geneticsABSTRACT
Background and Aims: Hirschsprung's disease (HSCR) is a rare genetically heterogeneous congenital disorder. A recent study based on whole genome sequencing demonstrated that common variants at four novel loci, which contained two intronic variants on CASQ2 and PLD1, and intergenic variants located between SLC4A7 and EOMES at 3p24.1, and between LINC01518 and LOC283028 at 10q11.21, were associated with HSCR susceptibility. To validate these associations with HSCR susceptibility, we performed a case-control study in a Han Chinese sample set. Methods: We selected four previously identified single nucleotide polymorphisms (SNPs) for replication, along with tag SNPs to cover the four associated regions. In total, 61 SNPs were genotyped in 420 HSCR patients and 1,665 healthy controls from the Han Chinese population. Results: None of the 14 tag SNPs in the CASQ2 gene region, including the previously associated rs9428225, showed an association with HSCR. Among the 24 tag SNPs from the SLC4A7-EOMES region at 3p24.1, rs2642925 [odds ratio (OR) = 1.41, 95% confidence interval (95% CI) = 1.10-1.79; P Additive = 0.007] and the previously associated SNP rs9851320 showed a suggestive association (OR = 1.22, 95% CI = 1.01-1.47; P Additive = 0.042). A non-synonymous SNP, rs2287579, in PLD1 showed a suggestive association with HSCR susceptibility (OR = 1.71, 95% CI = 1.18-2.46; P Additive = 0.004). Additionally, the previously associated PLD1 SNP rs12632766 showed a suggestive significance (OR = 1.20, 95% CI = 1.01-1.42, P Additive = 0.038). In the LINC01518-LOC283028 region at 10q11.21, three SNPs meet the study-wide significance threshold. Rs17153309 was the most associated SNP (OR = 1.60, 95% CI = 1.34-1.90; P Additive = 1.13 × 10-7). The previously associated SNP rs1414027 also showed significant association (OR = 1.43, 95% CI = 1.20-1.70, P Additive = 3.92 × 10-5). Two associated SNPs at 10q11.21 (rs1414027 and rs624804) were expression quantitative trait loci in digestive tract tissues from GTEx databases. Conclusions: Our results confirmed that variants of the LINC01518-LOC283028 region were associated with HSCR in the Han Chinese population. Additionally, the susceptibility of SNPs in the LINC01518-LOC283028 region were associated with the expression levels of nearby genes. These results provide new insight into the pathogenesis of HSCR.
ABSTRACT
BACKGROUND: Hirschsprung disease (HSCR) is a neurodevelopmental disorder with a strong genetic component. Common variants of NRG1 contributed to HSCR risk in Asians, and rare variants of ERBB2 and ITGB4 were found to be associated with HSCR. ERBB2 and ITGB4 are partners of Nrg1/ErbB pathway, which is important in HSCR pathogenesis. We aimed to investigate whether common variants in NRG1, ERBB2 and ITGB4 were associated with HSCR in Chinese Han population. METHODS: We genotype 17 single nucleotide polymorphisms (SNPs) of NRG1, ERBB2 and ITGB4 in 420 HSCR patients and 1665 controls, and performed association analysis. RESULTS: We validated associations of two NRG1 SNPs rs7835688 (PAllelicâ¯=â¯2.2â¯×â¯10-20, ORâ¯=â¯2.21, 95%CIâ¯=â¯1.86-2.62) and rs16879552 (PAllelicâ¯=â¯5.6â¯×â¯10-9, ORâ¯=â¯1.57, 95%CIâ¯=â¯1.35-1.83) with risk to HSCR. SNP rs3744000 located 5' upstream of ITGB4 showed association with HSCR (PAllelicâ¯=â¯2.4â¯×â¯10-3, ORâ¯=â¯1.27, 95%CIâ¯=â¯1.09-1.49). Four SNPs of ERBB2 exhibited no association. CONCLUSIONS: Our results suggested that common variation of ITGB4 and NRG1 conferred risk to HSCR in Chinese Han population, which further highlighted Nrg-1/ErbB pathway involving in the pathogenesis of HSCR.
Subject(s)
Hirschsprung Disease , Integrin beta4/genetics , Neuregulin-1/genetics , Asian People/genetics , Case-Control Studies , China/epidemiology , Genetic Predisposition to Disease , Hirschsprung Disease/genetics , Humans , Polymorphism, Single NucleotideABSTRACT
Biliary atresia (BA) is an idiopathic neonatal cholestatic disease. Recent genome-wide association study (GWAS) revealed that common variation of ADD3, GPC1, ARF6, and EFEMP1 gene was associated with BA susceptibility. We aimed to evaluate the association of these genes with BA in Chinese population. Twenty single nucleotide polymorphisms (SNPs) in these four genes were genotyped in 340 BA patients and 1,665 controls. Three SNPs in ADD3 were significantly associated with BA, and rs17095355 was the top SNP (PAllele = 3.23×10-6). Meta-analysis of published data and current data indicated that rs17095355 was associated with BA susceptibility in Asians and Caucasians. Three associated SNPs were expression quantitative trait loci (eQTL) for ADD3. Two GPC1 SNPs in high linkage disequilibrium (LD) showed nominal association with BA susceptibility (PAllele = 0.03 for rs6707262 and PAllele = 0.04 for rs6750380), and were eQTL of GPC1. Haplotype harboring these two SNPs almost reached the study-wide significance (P = 0.0035). No association for ARF6 and EFEMP1 was found with BA risk in the current population. Our study validated associations of ADD3 and GPC1 SNPs with BA risk in Chinese population and provided evidence of epistatic contributions of genetic factors to BA susceptibility.
Subject(s)
Biliary Atresia/genetics , Calmodulin-Binding Proteins/genetics , DNA/genetics , Glypicans/genetics , Polymorphism, Single Nucleotide , Biliary Atresia/metabolism , Calmodulin-Binding Proteins/metabolism , Case-Control Studies , Female , Genetic Predisposition to Disease , Genome-Wide Association Study , Genotype , Glypicans/metabolism , Humans , Infant , Male , Quantitative Trait LociABSTRACT
Currently, exploring effective measures to reduce multiple toxic metals accumulation in rice grains is an urgent issue to be tackled. Pot experiments were thus conducted to explore the effects and mechanisms of foliar spraying with composite sols of silicon (Si) and selenium (Se) during tillering to booting stage on diminishing cadmium (Cd) and lead (Pb) translocation to rice grains and affiliated physiological and biochemical responses in rice seedlings grown in Cd + Pb-polluted soils (positive control). Results showed that Cd and Pb contents in leaves or grains were distinctly below the positive control by the sols. Compared to the positive control, transcriptions of Cd transporter-related genes including OsLCT1, OsCCX2, OsHMA2 and OsPCR1 genes in leaves, and OsLCT1, OsCCX2, TaCNR2 and OSPCR1 in peduncles were downregulated by the increasing sols. Meanwhile, Se-binding protein 1 was evidently upregulated, together to retard Cd and Pb translocation to rice grains. The sols not only upregulated transcriptions of Lhcb1, RbcL, and OsBTF3 genes and production of psbA, Lhcb1 and RbcL proteins, but also increased the chlorophylls contents and RuBP carboxylase activities in the leaves, improving photosynthesis. The sols restrained ROS production from NADPH oxidases, but activated glutathione peroxidase, alleviating oxidative stress and damage. Additionally, Se was significantly enriched and was existed as selenomethionine in the rice grains. However, Pb transporter-related genes remain to be specified. Thus, the composite sols have potential to reduce Cd and Pb accumulation, mitigate oxidative damage, and promote photosynthesis and organic Se enrichment in rice plants under Cd and Pb combined pollution.
Subject(s)
Cadmium/toxicity , Lead/toxicity , Oryza/physiology , Soil Pollutants/toxicity , Antioxidants/metabolism , Cadmium/analysis , Chlorophyll/metabolism , Environmental Pollution , Lead/analysis , Oryza/chemistry , Oxidative Stress/drug effects , Photosynthesis , Plant Leaves/metabolism , Seedlings/drug effects , Selenium/chemistry , Selenium/metabolism , Silicon/chemistry , Silicon/metabolism , Soil/chemistry , Soil Pollutants/analysisABSTRACT
Carboxyl ester lipase (Cel), is a lipolytic enzyme secreted by the pancreas, which hydrolyzes various species of lipids in the gut. Cel is also secreted by mammary gland during lactation and exists in breast milk. It facilitates dietary fat digestion and absorption, thus contributing to normal infant development. This study aimed to examine whether the Cel in zebrafish embryos has a similar role of maternal lipid utilization as in human infants, and how Cel contributes to the utilization of yolk lipids in zebrafish. The cel1 and cel2 genes were expressed ubiquitously in the blastodisc and yolk syncytial layer before 24 hpf, and in the exocrine pancreas after 72 hpf. The cel1 and cel2 morphants exhibited developmental retardation and yolk sac retention. The total cholesterol, cholesterol ester, free cholesterol, and triglyceride were reduced in the morphants' body while accumulated in the yolk (except triglyceride). The FFA content of whole embryos was much lower in morphants than in standard controls. Moreover, the delayed development in cel (cel1/cel2) double morphants was partially rescued by FFA and cholesterol supplementation. Delayed and weakened cholesterol ester transport to the brain and eyes was observed in cel morphants. Correspondingly, shrunken midbrain tectum, microphthalmia, pigmentation-delayed eyes as well as down-regulated Shh target genes were observed in the CNS of double morphants. Interestingly, cholesterol injections reversed these CNS alterations. Our findings suggested that cel genes participate in the lipid releasing from yolk sac to developing body, thereby contributing to the normal growth rate and CNS development in zebrafish.
Subject(s)
Carboxylesterase/metabolism , Gene Expression Regulation, Developmental , Growth Disorders/genetics , Yolk Sac/enzymology , Zebrafish Proteins/metabolism , Zebrafish/embryology , Animals , Animals, Genetically Modified , Carboxylesterase/genetics , Central Nervous System/embryology , Cholesterol/metabolism , Cholesterol Esters/metabolism , Disease Models, Animal , Embryo, Nonmammalian , Embryonic Development , Gene Knockdown Techniques , Growth Disorders/embryology , Growth Disorders/enzymology , Hedgehog Proteins/metabolism , Humans , Lipid Metabolism , Morpholinos/administration & dosage , Morpholinos/genetics , Pancreas, Exocrine/embryology , Pancreas, Exocrine/enzymology , Triglycerides/metabolism , Yolk Sac/embryology , Zebrafish/genetics , Zebrafish/metabolism , Zebrafish Proteins/geneticsABSTRACT
Water lilies belong to the angiosperm order Nymphaeales. Amborellales, Nymphaeales and Austrobaileyales together form the so-called ANA-grade of angiosperms, which are extant representatives of lineages that diverged the earliest from the lineage leading to the extant mesangiosperms1-3. Here we report the 409-megabase genome sequence of the blue-petal water lily (Nymphaea colorata). Our phylogenomic analyses support Amborellales and Nymphaeales as successive sister lineages to all other extant angiosperms. The N. colorata genome and 19 other water lily transcriptomes reveal a Nymphaealean whole-genome duplication event, which is shared by Nymphaeaceae and possibly Cabombaceae. Among the genes retained from this whole-genome duplication are homologues of genes that regulate flowering transition and flower development. The broad expression of homologues of floral ABCE genes in N. colorata might support a similarly broadly active ancestral ABCE model of floral organ determination in early angiosperms. Water lilies have evolved attractive floral scents and colours, which are features shared with mesangiosperms, and we identified their putative biosynthetic genes in N. colorata. The chemical compounds and biosynthetic genes behind floral scents suggest that they have evolved in parallel to those in mesangiosperms. Because of its unique phylogenetic position, the N. colorata genome sheds light on the early evolution of angiosperms.
Subject(s)
Genome, Plant , Nymphaea/genetics , Phylogeny , Flowers/genetics , Flowers/metabolism , Nymphaea/metabolism , Odorants/analysisABSTRACT
Schisandra sphenanthera (Austrobaileyales) is a famous traditional Chinese medicine being long-history used, is also one of early-diverging angiosperms and important links to uncover the early evolution of angiosperms. Here the complete mitochondrial genome of S. sphenanthera was obtained for the first time. It is 1,106,521 bp in length with 46.4% GC content. It contains 58 genes, including 41 protein coding genes, three ribosomal RNA genes and 14 transfer RNA genes. Phylogenetic analysis indicated that S. sphenanthera was placed in the basal angiosperm just after Amborella and Nuphar. The mitogenome of S. sphenanthera would provide a reliable genetic and evolutionary resource.
ABSTRACT
The aim of the present study was to determine the effects of emodin, a natural compound with antioxidant properties, on oxidative stress and apoptosis induced by hypoxia/reoxygenation (H/R) in HK-2 human renal tubular cells. In HK-2 cells subjected to H/R, it was observed that pre-treatment with emodin lead to an increase in cellular viability and a reduction in the rate of apoptosis and the B-cell lymphoma 2 (Bcl-2)-associated X protein/Bcl-2 ratio. H/R alone caused a significant increase in the levels of reactive oxygen species and malondialdehyde (P<0.05) and a significant decrease in the activities of superoxide dismutase, catalase and glutathione peroxidase (P<0.05), relative to normoxic cells. In turn, parameters of oxidative stress were improved by emodin pre-treatment. In addition, emodin pre-treatment significantly inhibited the phosphorylation of extracellular signal-regulated protein kinase and c-Jun N-terminal kinase mitogen-activated protein kinases (MAPKs) induced by H/R (P<0.05). These data suggest that emodin may prevent H/R-induced apoptosis in human renal tubular cells through the regulation of cellular oxidative stress, MAPK activation and restoration of the Bax/Bcl-2 ratio.
ABSTRACT
Brassinosteroids (BRs) play key roles in plant growth and development, and regulate various agricultural traits. Enhanced BR signaling leads to increased seed number and yield in Arabidopsis bzr1-1D (AtBZR1(P234L), gain-of-function mutant of the important transcription factor in BR signaling/effects). BR signal transduction pathway is well elucidated in Arabidopsis but less known in other species. Soybean is an important dicot crop producing edible oil and protein. Phylogenetic analysis reveals AtBZR1-like genes are highly conserved in angiosperm and there are 4 orthologues in soybean (GmBZL1-4). We here report the functional characterization of GmBZL2 (relatively highly expresses in flowers). The P234 site in AtBZR1 is conserved in GmBZL2 (P216) and mutation of GmBZL2(P216L) leads to GmBZL2 accumulation. GmBZL2(P216L) (GmBZL2*) in Arabidopsis results in enhanced BR signaling; including increased seed number per silique. GmBZL2* partially rescued the defects of bri1-5, further demonstrating the conserved function of GmBZL2 with AtBZR1. BR treatment promotes the accumulation, nuclear localization and dephosphorylation/phosphorylation ratio of GmBZL2, revealing that GmBZL2 activity is regulated conservatively by BR signaling. Our studies not only indicate the conserved regulatory mechanism of GmBZL2 and BR signaling pathway in soybean, but also suggest the potential application of GmBZL2 in soybean seed yield.
Subject(s)
Brassinosteroids/metabolism , Glycine max/metabolism , Magnoliopsida/metabolism , Nuclear Proteins/metabolism , Plant Proteins/metabolism , Signal Transduction/physiology , Arabidopsis/genetics , Arabidopsis/metabolism , Magnoliopsida/genetics , Nuclear Proteins/genetics , Plant Proteins/genetics , Glycine max/geneticsABSTRACT
AP1/FUL, SEP, AGL6, and FLC subfamily genes play important roles in flower development. The phylogenetic relationships among them, however, have been controversial, which impedes our understanding of the origin and functional divergence of these genes. One possible reason for the controversy may be the problems caused by changes in the exon-intron structure of genes, which, according to recent studies, may generate non-homologous sites and hamper the homology-based sequence alignment. In this study, we first performed exon-by-exon alignments of these and three outgroup subfamilies (SOC1, AG, and STK). Phylogenetic trees reconstructed based on these matrices show improved resolution and better congruence with species phylogeny. In the context of these phylogenies, we traced evolutionary changes of exon-intron structures in each subfamily. We found that structural changes have occurred frequently following gene duplication and speciation events. Notably, exons 7 and 8 (if present) suffered more structural changes than others. With the knowledge of exon-intron structural changes, we generated more reasonable alignments containing all the focal subfamilies. The resulting trees showed that the SEP subfamily is sister to the monophyletic group formed by AP1/FUL and FLC subfamily genes and that the AGL6 subfamily forms a sister group to the three abovementioned subfamilies. Based on this topology, we inferred the evolutionary history of exon-intron structural changes among different subfamilies. Particularly, we found that the eighth exon originated before the divergence of AP1/FUL, FLC, SEP, and AGL6 subfamilies and degenerated in the ancestral FLC-like gene. These results provide new insights into the origin and evolution of the AP1/FUL, FLC, SEP, and AGL6 subfamilies.
ABSTRACT
Spiral flowers usually bear a variable number of organs, suggestive of the flexibility in structure. The mechanisms underlying the flexibility, however, remain unclear. Here we show that in Nigella damascena, a species with spiral flowers, different types of floral organs show different ranges of variation in number. We also show that the total number of organs per flower is largely dependent on the initial size of the floral meristem, whereas the respective numbers of different types of floral organs are determined by the functional domains of corresponding genetic programmes. By conducting extensive expression and functional studies, we further elucidate the genetic programmes that specify the identities of different types of floral organs. Notably, the AGL6-lineage member NdAGL6, rather than the AP1-lineage members NdFL1/2, is an A-function gene, whereas petaloidy of sepals is not controlled by AP3- or PI-lineage members. Moreover, owing to the formation of a regulatory network, some floral organ identity genes also regulate the boundaries between different types of floral organs. On the basis of these results, we propose that the floral organ identity determination programme is highly dynamic and shows considerable flexibility. Transitions from spiral to whorled flowers, therefore, may be explained by evolution of the mechanisms that reduce the flexibility.
Subject(s)
Flowers/anatomy & histology , Flowers/physiology , Nigella damascena/anatomy & histology , Nigella damascena/physiology , Flowers/genetics , Gene Expression Regulation, Plant , Gene Knockdown Techniques , Nigella damascena/genetics , Phylogeny , Plant Proteins/geneticsABSTRACT
The treatment of anaerobically digested swine wastewater (ADSW) is problematic due to its high nutrient concentration. This study investigated the simultaneous sequestration of ammonium (N) and phosphate (P) from ADSW using nano-zeolites synthesized from fly ash (ZFA). The nanometer-scale crystalline structures plentiful of zeolite-NaP1 coating on ZFA particle increased the levels of specific surface area and cation exchange capacity at times of 40 and 104, compared to raw fly ash. Kinetic N and P sorption experiments with ZFA were well described by both the Langmuir and Freundlich models, suggesting the co-existence of homogeneous and heterogeneous sorption mechanisms. N and P removal efficiencies ranged from 41% to 95% and 75% to 98%, respectively, across a range of ZFA doses (from 0.25 to 8g/100ml). Collectively, application of the laboratory-synthesized ZFA can alleviate the nutrient loads in ADSW and therefore modify the ratio of N:P in wastewater beneficial for subsequent biological treatment.