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A monosaccharide transporter is localized to sieve plate and plasmodesmal channel in developing apple fruit
Lingyun Zhang,Changcao Peng,Keqin Zou,Xiuling Wang,Renchun Fan,Xiangchun Yu,Xiaoyan Zhang,Yuanyue Shen,Dapeng Zhang
Chinese Science Bulletin , 2005, DOI: 10.1007/BF02897458
Abstract: Two major classes of plant sugar transporters, sucrose and monosaccharide transporters, may be localized to tonoplast or plasma membrane. The monosaccharide transporters may also be localized in plastid. However, whether these transporters reside in other subcellular compartments remains unclear. We recently detected in apple fruit a 52 kD plasma membrane-localized monosaccharide transporter, and showed that this transporter may be functional in phloem unloading in the fruit. In this paper, we report that this monosaccharide transporter is also localized to sieve plate and plasmodesmal channel in apple fruit. The amount of this sieve plate- and plasmodesma-associated transporter changes during fruit development. This amount of the transporter expression may be altered in the phloem sieve elements but not in the parenchyma cells by a photoassimilate deficiency applied by the shoot girdling treatment, suggesting that the monosaccharide transporter of the special sub-cellular localization may be of biological significance.
A monosaccharide transporter is localized to sieve plate and plasmodesmal channel in developing apple fruit
Lingyun Zhang,Changcao Peng,Keqin Zou,Xiuling Wang,Renchun Fan,Xiangchun Yu,Xiaoyan Zhang,Yuanyue Shen,Dapeng Zhang,
ZHANGLingyun
,PENGChangcao,ZOUKeqin,WANGXiuling,FANRenchun,YUXiangchun,ZHANGXiaoyan,SHENYuanyue,ZHANGDapeng

科学通报(英文版) , 2005,
Abstract: Two major classes of plant sugar transporters, sucrose and monosaccharide transporters, may be localized to tonoplast or plasma membrane. The monosaccharide transporters may also be localized in plastid. However, whether these transporters reside in other subcellular compartments remains unclear. We recently detected in apple fruit a 52 kD plasma membrane-localized monosaccharide transporter, and showed that this transporter may be functional in phloem unloading in the fruit. In this paper, we report that this monosaccharide transporter is also localized to sieve plate and plasmodesmal channel in apple fruit. The amount of this sieve plate- and plasmodesma-associated transporter changes during fruit development. This amount of the transporter expression may be altered in the phloem sieve elements but not in the parenchyma cells by a photoas-similate deficiency applied by the shoot girdling treatment, suggesting that the monosaccharide transporter of the special sub-cellular localization may be of biological significance.
Structural Evolution of the ABC Transporter Subfamily B
Flanagan, J.U.,Huber, T.
Evolutionary Bioinformatics , 2007,
Abstract: The ATP binding cassette containing transporters are a superfamily of integral membrane proteins that translocate a wide range of substrates. The subfamily B members include the biologically important multidrug resistant (MDR) protein and the transporter associated with antigen processing (TAP) complex. Substrates translocated by this subfamily include drugs, lipids, peptides and iron. We have constructed a comprehensive set of comparative models for the transporters from eukaryotes and used these to study the effects of sequence divergence on the substrate translocation pathway. Notably, there is very little structural divergence between the bacterial template structure and the more distantly related eukaryotic proteins illustrating a need to conserve transporter structure. By contrast different properties have been adopted for the translocation pathway depending on the substrate type. A greater level of divergence in electrostatic properties is seen with transporters that have a broad substrate range both within and between species, while a high level of conservation is observed when the substrate range is narrow. This study represents the first effort towards understanding effect of evolution on subfamily B ABC transporters in the context of protein structure and biophysical properties.
Insect Resistance to Bacillus thuringiensis Toxin Cry2Ab Is Conferred by Mutations in an ABC Transporter Subfamily A Protein  [PDF]
Wee Tek Tay?,Rod J. Mahon?,David G. Heckel?,Thomas K. Walsh?,Sharon Downes?,William J. James?,Sui-Fai Lee?,Annette Reineke?,Adam K. Williams?,Karl H. J. Gordon
PLOS Genetics , 2015, DOI: 10.1371/journal.pgen.1005534
Abstract: The use of conventional chemical insecticides and bacterial toxins to control lepidopteran pests of global agriculture has imposed significant selection pressure leading to the rapid evolution of insecticide resistance. Transgenic crops (e.g., cotton) expressing the Bt Cry toxins are now used world wide to control these pests, including the highly polyphagous and invasive cotton bollworm Helicoverpa armigera. Since 2004, the Cry2Ab toxin has become widely used for controlling H. armigera, often used in combination with Cry1Ac to delay resistance evolution. Isolation of H. armigera and H. punctigera individuals heterozygous for Cry2Ab resistance in 2002 and 2004, respectively, allowed aspects of Cry2Ab resistance (level, fitness costs, genetic dominance, complementation tests) to be characterised in both species. However, the gene identity and genetic changes conferring this resistance were unknown, as was the detailed Cry2Ab mode of action. No cross-resistance to Cry1Ac was observed in mutant lines. Biphasic linkage analysis of a Cry2Ab-resistant H. armigera family followed by exon-primed intron-crossing (EPIC) marker mapping and candidate gene sequencing identified three independent resistance-associated INDEL mutations in an ATP-Binding Cassette (ABC) transporter gene we named HaABCA2. A deletion mutation was also identified in the H. punctigera homolog from the resistant line. All mutations truncate the ABCA2 protein. Isolation of further Cry2Ab resistance alleles in the same gene from field H. armigera populations indicates unequal resistance allele frequencies and the potential for Bt resistance evolution. Identification of the gene involved in resistance as an ABC transporter of the A subfamily adds to the body of evidence on the crucial role this gene family plays in the mode of action of the Bt Cry toxins. The structural differences between the ABCA2, and that of the C subfamily required for Cry1Ac toxicity, indicate differences in the detailed mode-of-action of the two Bt Cry toxins.
Complex evolution of the DAL5 transporter family
Linda Hellborg, Megan Woolfit, Mattias Arthursson-Hellborg, Jure Pi?kur
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-164
Abstract: We identified numerous gene duplications creating sets of orthologous and paralogous genes. In different lineages the DAL5 subfamily members expanded or contracted and in some lineages a specific member could not be found at all. We also observed a close relationship between the gene YIL166C and its homologs in the Saccharomyces sensu stricto species and two "wine spoiler" yeasts, Dekkera bruxellensis and Candida guilliermondi, which could possibly be the result of horizontal gene transfer between these distantly related species. In the analyses we detect several well defined groups without S. cerevisiae representation suggesting new gene members in this subfamily with perhaps altered specialization or function.The transmembrane DAL5 subfamily was found to have a very complex evolution in yeast with intra- and interspecific duplications and unusual relationships indicating specialization, specific deletions and maybe even horizontal gene transfer. We believe that this group will be important in future investigations of evolution in fungi and especially the evolution of transmembrane proteins and their specialization.Transmembrane transporters of unicellular organisms, like yeast, are one of the primary links between the outer world and the metabolic pathways inside the cell. The importance of these genes is seen in the substantial proportion of transporter genes within the yeast genome (10%) [1]. In Saccharomyces cerevisiae, for example, over 400 genes encoding transporter proteins have been found [2].Different species of yeast require different substrates to be transported, and the number and kind of transporters present in the genome therefore vary between species. The presence or absence of a transporter may provide insight into the niche preference and metabolic ability of a yeast [3-6]. An example is seen in the loss or inactivation of the galactose transporter Gal2p (and six other genes of the galactose metabolism) in several Hemiascomycete species [7]. Simila
The Vitis vinifera sugar transporter gene family: phylogenetic overview and macroarray expression profiling
Damien Afoufa-Bastien, Anna Medici, Julien Jeauffre, Pierre Coutos-Thévenot, Rémi Lemoine, Rossitza Atanassova, Maryse Laloi
BMC Plant Biology , 2010, DOI: 10.1186/1471-2229-10-245
Abstract: In grapevine, one of the most economically important fruit crop in the world, it appeared that sucrose and monosaccharide transporter genes are present in 4 and 59 loci, respectively and that the monosaccharide transporter family can be divided into 7 subfamilies. Phylogenetic analysis of protein sequences has indicated that orthologs exist between Vitis and Arabidospis. A search for cis-regulatory elements in the promoter sequences of the most characterized transporter gene families (sucrose, hexoses and polyols transporters), has revealed that some of them might probably be regulated by sugars. To profile several genes simultaneously, we created a macroarray bearing cDNA fragments specific to 20 sugar transporter genes. This macroarray analysis has revealed that two hexose (VvHT1, VvHT3), one polyol (VvPMT5) and one sucrose (VvSUC27) transporter genes, are highly expressed in most vegetative organs. The expression of one hexose transporter (VvHT2) and two tonoplastic monosaccharide transporter (VvTMT1, VvTMT2) genes are regulated during berry development. Finally, three putative hexose transporter genes show a preferential organ specificity being highly expressed in seeds (VvHT3, VvHT5), in roots (VvHT2) or in mature leaves (VvHT5).This study provides an exhaustive survey of sugar transporter genes in Vitis vinifera and revealed that sugar transporter gene families in this woody plant are strongly comparable to those of herbaceous species. Dedicated macroarrays have provided a Vitis sugar transporter genes expression profiling, which will likely contribute to understand their physiological functions in plant and berry development. The present results might also have a significant impact on our knowledge on plant sugar transporters.In plants, sugars (sucrose, monosaccharides, polyols) are important molecules that constitute not only metabolites but also nutrients, osmotic and signal molecules. In numerous species, sucrose is the most prevalent sugar produced in pho
Epicardial Lineages  [PDF]
Franziska Greulich,Andreas Kispert
Journal of Developmental Biology , 2013, DOI: 10.3390/jdb1010032
Abstract: The epicardium is the mono-layered epithelium that covers the outer surface of the myocardium from early in cardiac development. Long thought to act merely passively to protect the myocardium from frictional forces in the pericardial cavity during the enduring contraction and expansion cycles of the heart, it is now considered to be a crucial source of cells and signals that direct myocardial growth and formation of the coronary vasculature during development and regeneration. Lineage tracing efforts in the chick, the mouse and the zebrafish unambiguously identified fibroblasts in interstitial and perivascular locations as well as coronary smooth muscle cells as the two major lineages that derive from epithelial-mesenchymal transition and subsequent differentiation from individual epicardial cells. However, controversies exist about an additional endothelial and myocardial fate of epicardial progenitor cells. Here, we review epicardial fate mapping efforts in three vertebrate model systems, describe their conceptual differences and discuss their methodological limitations to reach a consensus of the potential of (pro-)epicardial cells in vitro and in vivo.
Molecular Weight and Monosaccharide Composition of Astragalus Polysaccharides  [PDF]
Du-Juan Xu,Quan Xia,Jia-Jia Wang,Pei-Pei Wang
Molecules , 2008, DOI: 10.3390/molecules13102408
Abstract: Two polysaccharides (APS-I and APS-II) were isolated from the water extract of Radix Astragali and purified through ethanol precipitation, deproteination and by ion-exchange and gel-filtration chromatography. Their molecular weight was determined using high performance liquid chromatography and gel permeation chromatography (HPLC-GPC) and their monosaccharide composition was analyzed by TLC and HPLC methods, using a refractive index detector (RID) and an NH2 column. It was shown that APS-I consisted of arabinose and glucose and APS-II consisted of rhamnose, arabinose and glucose, in a molar ratio of 1:3.45 and 1:6.25:17.86, respectively. The molecular weights (Mw) of APS-I and APS-II were 1,699,100 Da and 1,197,600 Da, respectively.
Molecular Weight and Monosaccharide Composition of Astragalus Polysaccharides
Du-Juan Xu,Quan Xia,Jia-Jia Wang,Pei-Pei Wang
Molecules , 2008,
Abstract: Two polysaccharides (APS-I and APS-II) were isolated from the water extract of Radix Astragali and purified through ethanol precipitation, deproteination and by ion-exchange and gel-filtration chromatography. Their molecular weight was determined using high performance liquid chromatography and gel permeation chromatography (HPLC-GPC) and their monosaccharide composition was analyzed by TLC and HPLC methods, using a refractive index detector (RID) and an NH2 column. It was shown that APS-I consisted of arabinose and glucose and APS-II consisted of rhamnose, arabinose and glucose, in a molar ratio of 1:3.45 and 1:6.25:17.86, respectively. The molecular weights (Mw) of APS-I and APS-II were 1,699,100 Da and 1,197,600 Da, respectively.
Vanishing native American dog lineages
Santiago Castroviejo-Fisher, Pontus Skoglund, Raúl Valadez, Carles Vilà, Jennifer A Leonard
BMC Evolutionary Biology , 2011, DOI: 10.1186/1471-2148-11-73
Abstract: We identified many previously undescribed mitochondrial control region sequences in 400 dogs from rural and isolated areas as well as street dogs from across the Americas. However, sequences of native American origin proved to be exceedingly rare, and we estimate that the native population contributed only a minor fraction of the gene pool that constitutes the modern population.The high number of previously unidentified haplotypes in our sample suggests that a lot of unsampled genetic variation exists in non-breed dogs. Our results also suggest that the arrival of European colonists to the Americas may have led to an extensive replacement of the native American dog population by the dogs of the invaders.Dogs colonized the Americas with early human groups from Asia [1] and were widespread by the time Europeans arrived late in the 15th century [2]. Most of the dogs around the world today have mitochondrial DNA (mtDNA) control region sequences that form a well-defined phylogenetic clade (Clade I) [3]. Genetic characterization of ancient American dogs (samples obtained from human settlements that had not been in contact with Europeans, hereafter referred to as native American dogs) revealed a unique set of mtDNA sequences that clustered within this clade, but have not been observed in extant dogs [e.g. [3-6]]. Most notably, a subclade (Ia) has so far only been identified in ancient American dogs and had a frequency of 62% in ancient Latin American animals [1]. However, most genetic studies are based on purebred dogs, and since most internationally recognized breeds today are primarily European or Asian in origin, it is possible that American dog lineages have been excluded.To determine contemporary distribution and frequency of the native American dog lineages in the Americas (both North America and South America), we analyzed the fragment of the mtDNA control region comparable to available genetic data for ancient native American dogs in 400 village and non-breed dogs
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