Effect of 1-methylcyclopropene on postharvest physiological changes of ‘Zaohong’ plum

Plum is a highly perishable fruit and postharvest fruit softening limits its shelf life. The aim of this work was to study the specific effects of 1-methylcyclopropene (1-MCP) treatment on physiological changes in ‘Zaohong’ plums. Plums were treated with 500 nL L⁻¹ 1-MCP at 20°C for 18 h followed by 20°C storage. The results showed that 1-MCP treatment significantly reduced endogenous ethylene production and the activities of ethylene biosynthetic enzymes’ (1-aminocyclopropane-1-carboxylic acid synthase, ACS and 1-aminocyclopropane-1-carboxylic acid oxidase, ACO) in plum fruit during storage when compared with untreated fruit. Although 1-MCP treatment inhibited ethylene production and 1-aminocyclopropane-1-carboxylic acid (ACC) accumulation, it did not inhibit the accumulation of N-malonyl-ACC (MACC). Higher firmness was also found in 1-MCP-treated plums than in controls. During storage, superoxide anion (O₂^−·) and hydrogen peroxide (H₂O₂) levels decreased in 1-MCP-treated fruit. 1-MCP treatment also regulated superoxide dismutase (SOD) and catalase (CAT) activities during storage. Xylanase activity was upregulated while activities of polygalacturonase (PG), pectin methyl esterase (PME) and cellulase enzymes in the fruit were downregulated by 1-MCP treatment. In conclusion, 1-MCP might be a potent compound for extending both storage period and shelf life of ‘Zaohong’ plums by suppressing ethylene biosynthesis, regulating cell wall degradation enzymes and reducing fruit softening.     

Classification of hybrid and altered Vibrio cholerae strains by CTX prophage and RS1 element structure

Analysis of the CTX prophage and RS1 element in hybrid and altered Vibrio cholera O1 strains showed two classifiable groups. Group I strains contain a tandem repeat of classical CTX prophage on the small chromosome. Strains in this group either contain no element(s) or an additional CTX prophage or RS1 element(s) on the large chromosome. Group II strains harbor RS1 and CTX prophage, which has an E1 Tor type rstR and classical ctxB on the large chromosome.     

Identification of three protein disulfide isomerase members from Haemaphysalis longicornis tick

Three genes encoding putative protein disulfide isomerase (PDI) were isolated from the Haemaphysalis longicornis EST database and designed as HlPDI-1, HlPDI-2, and HlPDI-3. All three PDI genes contain two typical PDI active sites CXXC and encode putative 435, 499, and 488 amino acids, respectively. The recombinant proteins expressed in Escherichia coli all show PDI activities, and the activities were inhibited by a PDI-specific inhibitor, zinc bacitracin. Western blot analysis and real-time PCR revealed that three HlPDIs were present in all the developmental stages of the tick as well as in the midgut, salivary glands, ovary, hemolymph, and fatbody of adult female ticks, but the three genes were expressed at the highest level in the egg stage. HlPDI-1 is expressed primarily in the ovary and secondarily in the salivary glands. HlPDI-2 and HlPDI-3 are expressed primarily in the salivary gland, suggesting that the PDI genes are important for tick biology, especially for egg development, and that they play distinct roles in different tissues. Blood feeding induced significantly increased expression of HlPDI-1 and HlPDI-3 in both partially fed nymphs and adults. Babesia gibsoni-infected larval ticks expressed HlPDI-1 and HlPDI-3 2.0 and 4.0 times higher than uninfected normal larval ticks, respectively. The results indicate that HlPDI-1 and HlPDI-3 might be involved in tick blood feeding and Babesia parasite infection in ticks.     

Genome wide association (GWA) study for early onset extreme obesity supports the role of fat mass and obesity associated gene (FTO) variants

Background

Obesity is a major health problem. Although heritability is substantial, genetic mechanisms predisposing to obesity are not very well understood. We have performed a genome wide association study (GWA) for early onset (extreme) obesity.

Methodology/Principal Findings

a) GWA (Genome-Wide Human SNP Array 5.0 comprising 440,794 single nucleotide polymorphisms) for early onset extreme obesity based on 487 extremely obese young German individuals and 442 healthy lean German controls; b) confirmatory analyses on 644 independent families with at least one obese offspring and both parents. We aimed to identify and subsequently confirm the 15 SNPs (minor allele frequency ≥10%) with the lowest p-values of the GWA by four genetic models: additive, recessive, dominant and allelic. Six single nucleotide polymorphisms (SNPs) in FTO (fat mass and obesity associated gene) within one linkage disequilibrium (LD) block including the GWA SNP rendering the lowest p-value (rs1121980; log-additive model: nominal p = 1.13×10⁻⁷, corrected p = 0.0494; odds ratio (OR)_CT 1.67, 95% confidence interval (CI) 1.22–2.27; OR_TT 2.76, 95% CI 1.88–4.03) belonged to the 15 SNPs showing the strongest evidence for association with obesity. For confirmation we genotyped 11 of these in the 644 independent families (of the six FTO SNPs we chose only two representing the LD bock). For both FTO SNPs the initial association was confirmed (both Bonferroni corrected p<0.01). However, none of the nine non-FTO SNPs revealed significant transmission disequilibrium.

Conclusions/Significance

Our GWA for extreme early onset obesity substantiates that variation in FTO strongly contributes to early onset obesity. This is a further proof of concept for GWA to detect genes relevant for highly complex phenotypes. We concurrently show that nine additional SNPs with initially low p-values in the GWA were not confirmed in our family study, thus suggesting that of the best 15 SNPs in the GWA only the FTO SNPs represent true positive findings.     

Domains of estrogen receptor alpha (ERalpha) required for ERalpha/Sp1-mediated activation of GC-rich promoters by estrogens and antiestrogens in breast cancer cells

Estrogen receptor alpha (ERalpha)/Sp1 activation of GC-rich gene promoters in breast cancer cells is dependent, in part, on activation function 1 (AF1) of ERalpha, and this study investigates contributions of the DNA binding domain (C) and AF2 (DEF) regions of ERalpha on activation of ERalpha/Sp1. 17Beta-estradiol (E2) and the antiestrogens 4-hydroxytamoxifen and ICI 182,780 induced reporter gene activity in MCF-7 and MDA-MB-231 cells cotransfected with human or mouse ERalpha (hERalpha or MOR), but not ERbeta and GC-rich constructs containing three tandem Sp1 binding sites (pSp13) or other E2-responsive GC-rich promoters. Estrogen and antiestrogen activation of hERalpha/Sp1 was dependent on overlapping and different regions of the C, D, E, and F domains of ERalpha. Antiestrogen-induced activation of hERalpha/Sp1 was lost using hERalpha mutants deleted in zinc finger 1 [amino acids (aa) 185-205], zinc finger 2 (aa 218-245), and the hinge/helix 1 (aa 265-330) domains. In contrast with antiestrogens, E2-dependent activation of hERalpha/Sp1 required the C-terminal F domain (aa 579-595), which contains a beta-strand structural motif. Moreover, in peptide competition experiments overexpression of a C-terminal (aa 575-595) F domain peptide specifically blocked E2-dependent activation of hERalpha/Sp1, suggesting that F domain interactions with nuclear cofactors are required for ERalpha/Sp1 action.     

Biochemical and electrochemical characterization of two variant human short-chain acyl-CoA dehydrogenases

Short-chain acyl-CoA dehydrogenase (hSCAD) catalyzes the first matrix step in the mitochondrial beta-oxidation cycle with optimal activity toward butyryl- and hexanoyl-CoA. Two common variants of this enzyme encoding G185S and R147W substitutions have been identified at an increased frequency compared to the general population in patients with a wide variety of clinical problems, but functional studies of the purified mutant enzymes have shown only modestly changed kinetic properties. Moreover, both amino acid residues are located quite far from the catalytic pocket and the essential FAD cofactor. To clarify the potential relationship of these variants to clinical disease, we have further investigated their thermodynamic properties using spectroscopic and electrochemical techniques. Purified R147W hSCAD exhibited almost identical physical and redox properties to wild-type but only half of the specific activity and substrate activation shifts observed in wild-type enzyme. In contrast, the G185S mutant proved to have impairments of both its kinetic and electron transfer properties. Spectroelectrochemical studies reveal that G185S binding to the substrate/product couple produces an enzyme potential shift of only +88 mV, which is not enough to make the reaction thermodynamically favorable. For wild-type hSCAD, this barrier is overcome by a negative shift in the substrate/product couple midpoint potential, but in G185S this activation was not observed. When G185S was substrate bound, the midpoint potential of the enzyme actually shifted more negative. These results provide valuable insight into the mechanistic basis for dysfunction of the common variant hSCADs and demonstrate that mutations, regardless of their position in the protein structure, can have a large impact on the redox properties of the enzyme.     

Morphological and ecological similarities: wood-boring beetles associated with novel xylose-fermenting yeasts, Spathaspora passalidarum gen. sp. nov. and Candida jeffriesii sp. nov.

Ascomycete yeasts that both ferment and assimilate xylose were reported previously as associates of insects living in woody substrates. Most notable have been reports of Pichia stipitis-like yeasts that are widely associated with the wood-boring beetle, Odontotaenius disjunctus (Coleoptera: Passalidae), in the eastern United States. Our continuing investigation of insect gut yeasts has lead to the discovery of two new xylose-fermenting yeasts that phylogenetic analysis places as sister taxa. The beetle hosts, O. disjunctus and Phrenapates bennetti (Coleoptera: Tenebrionidae), are similar in habitat and appearance, and the presence of similar gut yeasts is an additional common feature between them. Here we describe the new yeast genus Spathaspora, the type species S. passalidarum, and its sister taxon Candida jeffriesii and discuss their natural history, including a comparison with Pichia stipitis, another member of a guild of xylose-fermenting yeasts with similar metabolic traits. In addition a morphologically distinct yeast ascospore type is described for Spathaspora.