Specific monitoring of aflatoxin M1 in real samples using aptamer binding to DNFS based on turn‐on method: A novel biosensor

In the present work, a novel biocompatible scaffold was fabricated for the DNA aptamer immobilization. For the first time, amino‐functionalized dendritic fibrous nanosilica (KCC‐1‐nPr‐NH₂) and gold nanoparticle supported by chitosan (AuNPs‐CS) were synthesized and electrodeposited successfully on the surface of the glassy carbon electrode by chronoamperometry technique. Unique oligonucleotide of aflatoxin M1 (5′‐ATC CGT CAC ACC TGC TCT GAC GCT GGG GTC GAC CCG GAG AAA TGC ATT CCC CTG TGG TGT TGG CTC CCG TAT) labeled by toluidine blue was immobilization on the prepared interface. Hence, a novel aptamer‐based bioassay was formed for highly sensitive quantitation of AFM1 using cyclic voltammetry and differential plus voltammetry. The structure and morphology of GQDs‐CS/KCC‐1‐nPr‐NH₂ were investigated by Fourier‐transform infrared spectroscopy, X‐ray diffraction, atomic force, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy. The achieved low limit of quantification of apta‐assay for detection of AFM1 was 10fM. Also, calibration curve was linear from 0.1μM to 10fM in real samples. The proposed apta‐assay has acceptable long‐term stability. Designed aptasensor has a lot of remarkable advantages including excellent selectivity, sensitivity, and stability that could be used as facile bio‐device for the determination of AFM1 in milk samples.     

A novel electroconductive interface based on Fe3O4 magnetic nanoparticle and cysteamine functionalized AuNPs: Preparation and application as signal amplification element to minoring of antigen‐antibody immunocomplex and biosensing of prostate cancer

In this study, a novel electroconductive interface was prepared based on Fe₃O₄ magnetic nanoparticle and cysteamine functionalized gold nanoparticle. The engineered interface was used as signal amplification substrate in the electrochemical analysis of antibody‐antigen binding. For this purpose, biotinilated‐anti‐prostate‐specific antigen (PSA) antibody was bioconjugated with iron oxide magnetic nanoparticles (Fe₃O₄) and drop‐casted on the surface of glassy carbon electrode (GCE). Also, secondary antibody (HRP‐Ab2) encapsulated on gold nanoparticles caped by cysteamine was immobilized on the surface of GCE modified electrode. A transmission electron microscopy images shows that a sandwich immunoreaction was done and binding of Ab1 and Ab2 performed successfully. Various parameters of immunoassay, including the loading of magnetic nanoparticles, the amount of gold nanoparticle conjugate, and the immunoreaction time, were optimized. The detection limit of 0.001 μg. L^?1 of PSA was obtained under optimum experimental conditions. It is found that such magneto‐bioassay could be readily used for simultaneous parallel detection of multiple proteins by using multiple inorganic metal nanoparticle tracers and are expected to open new opportunities for early stage diagnosis of cancer in near future.     

Sensitive monitoring of riboflavin in commercial multivitamins using poly (chitosan)‐based nanocomposite

The rapid and sensitive determination of riboflavin (RF) is important for the treatment of seborrheic and glossitis dermatitis, sunlight sensitivity, mucosal, and skin disorders. In this work, an electrochemical sensor was developed by electrodes modification using poly (chitosan) to sensitive detection of RF in commercial multivitamin. Electrodeposition of chitosan on the surface of glass carbon electrode was performed using cyclic voltammetry technique in the range of ?1 to +1 V. The modified electrode surface morphology was characterized using a high‐resolution field emission scanning electron microscope. The modified electrode was used as an effective electrical interface for the detection of RF using cyclic, differential pulse, and square wave voltammetry techniques. Finally, the sensor was applied to determine RF in commercial multivitamins. In optimum conditions, the linear range for the standard sample of RF and commercial multivitamins 94 to 333μM and 24.6 to 176μM were obtained, respectively. Low limit of quantification (LLOQ) were obtained as 24.6μM.     

Extraordinarily conserved chromosomal synteny of Citrus species revealed by chromosome‐specific painting

Reliable identification of individual chromosomes in eukaryotic species is the foundation for comparative chromosome synteny and evolutionary studies. Unfortunately, chromosome identification has been a major challenge for plants with small chromosomes, such as the Citrus species. We developed oligonucleotide‐based chromosome painting probes for all nine chromosomes in Citrus maxima (Pummelo). We were able to identify all C. maxima chromosomes in the same metaphase cells using multiple rounds of sequential fluorescence in situ hybridization with the painting probes. We conducted comparative chromosome painting analysis in six different Citrus and related species. We found that each painting probe hybridized to only a single chromosome in all other five species, suggesting that the six species have maintained a complete chromosomal synteny after more than 9 million years of divergence. No interchromosomal rearrangement was identified in any species. These results support the hypothesis that karyotypes of woody species are more stable than herbaceous plants because woody plants need a longer period to fix chromosome structural variants in natural populations.     

Overexpression of the persimmon abscisic acid β‐glucosidase gene (DkBG1) alters fruit ripening in transgenic tomato

β‐Glucosidases (BG) are present in many plant tissues. Among these, abscisic acid (ABA) β‐glucosidases are thought to take part in the adjustment of cellular ABA levels, however the role of ABA‐BG in fruits is still unclear. In this study, through RNA‐seq analysis of persimmon fruit, 10 full‐length DkBG genes were isolated and were all found to be expressed. In particular, DkBG1 was highly expressed in persimmon fruits with a maximum expression 95 days after full bloom (DAFD). We verified that, in vitro, DkBG1 protein can hydrolyze ABA‐glucose ester (ABA‐GE) to release free ABA. Compared with wild‐type, tomato plants that overexpressed DkBG1 significantly upregulated the expression of ABA receptor PYL3/7 genes and showed typical symptoms of ABA hypersensitivity in fruits. DkBG1 overexpression (DkBG1‐OE) accelerated fruit ripening onset by 3–4 days by increasing ABA levels at the pre‐breaker stage and induced early ethylene release compared with wild‐type fruits. DkBG1‐OE altered the expression of ripening regulator NON‐RIPENING (NOR) and its target genes; this in turn altered fruit quality traits such as coloration. Our results demonstrated that DkBG1 plays an important role in fruit ripening and quality by adjusting ABA levels via hydrolysis of ABA‐GE.     

ATP binding cassette transporters ABCG1 and ABCG16 affect reproductive development via auxin signalling in Arabidopsis

Angiosperm reproductive development is a complex event that includes floral organ development, male and female gametophyte formation and interaction between the male and female reproductive organs for successful fertilization. Previous studies have revealed the redundant function of ATP binding cassette subfamily G (ABCG) transporters ABCG1 and ABCG16 in pollen development, but whether they are involved in other reproductive processes is unknown. Here we show that ABCG1 and ABCG16 were not only expressed in anthers and stamen filaments but also enriched in pistil tissues, including the stigma, style, transmitting tract and ovule. We further demonstrated that pistil‐expressed ABCG1 and ABCG16 promoted rapid pollen tube growth through their effects on auxin distribution and auxin flow in the pistil. Moreover, disrupted auxin homeostasis in stamen filaments was associated with defective filament elongation. Our work reveals the key functions of ABCG1 and ABCG16 in reproductive development and provides clues for identifying ABCG1 and ABCG16 substrates in Arabidopsis.     

Genetic assessment of the internal transcribed spacer region (ITS1.2) in Mangifera indica L. landraces

Mango (Mangifera indica) is one of the most important tropical fruits in the world. Twenty-two genotypes of native mangoes from different regions of southern Iran (Hormozgan and Kerman) were collected and analyzed for the ribosomal genes. GC content was found to be 55.5%. Fu and Li’s D* test statistic (0.437), Fu and Li’s F* test statistic (0.500) and Tajima’s D (1.801) were positive and nonsignificant. A total of 769 positions were identified (319 with insertion or deletion including 250 polymorphic and 69 monomorphic loci; 450 loci without any insertion or deletion including 35 Singletons and 22 haplotypes). Nucleotide diversity of 0.309 and a high genetic differentiation including Chi square of 79.8; P value of 0.3605 and df value of 76 was observed among mango genotypes studied. The numerical value of the ratio dN/dS (0.45) indicated a pure selection in the examined gene and the absence of any key changes. Cluster analysis differentiated the mango used in this research (M. indica L.) into two genotypes but could not differentiate their geographical locations. The results of this study indicated that a high genetic distance exists between HajiGholam (Manojan) and Arbabi (Rodan) genotypes and showed higher genetic diversity in mango of Rodan region. Results of present study suggested that for successful breeding, the genotypes of Rodan region mango especially Arbabi mango can be used as a gene donor and ITS can be a suitable tool for genetic evaluations of inter and intra species.