BackgroundHeat shock proteins (Hsps) are essential components in plant tolerance mechanism under various abiotic stresses. Hsp20 is the major family of heat shock proteins, but little of Hsp20 family is known in potato (Solanum tuberosum), which is an important vegetable crop that is thermosensitive.ResultsTo reveal the mechanisms of potato Hsp20s coping with abiotic stresses, analyses of the potato Hsp20 gene family were conducted using bioinformatics-based methods. In total, 48 putative potato Hsp20 genes (StHsp20s) were identified and named according to their chromosomal locations. A sequence analysis revealed that most StHsp20 genes (89.6%) possessed no, or only one, intron. A phylogenetic analysis indicated that all of the StHsp20 genes, except 10, were grouped into 12 subfamilies. The 48 StHsp20 genes were randomly distributed on 12 chromosomes. Nineteen tandem duplicated StHsp20s and one pair of segmental duplicated genes (StHsp20-15 and StHsp20-48) were identified. A cis-element analysis inferred that StHsp20s, except for StHsp20-41, possessed at least one stress response cis-element. A heatmap of the StHsp20 gene family showed that the genes, except for StHsp20-2 and StHsp20-45, were expressed in various tissues and organs. Real-time quantitative PCR was used to detect the expression level of StHsp20 genes and demonstrated that the genes responded to multiple abiotic stresses, such as heat, salt or drought stress. The relative expression levels of 14 StHsp20 genes (StHsp20-4, 6, 7, 9, 20, 21, 33, 34, 35, 37, 41, 43, 44 and 46) were significantly up-regulated (more than 100-fold) under heat stress.ConclusionsThese results provide valuable information for clarifying the evolutionary relationship of the StHsp20 family and in aiding functional characterization of StHsp20 genes in further research.Electronic supplementary materialThe online version of this article (dio: 10.1186/s12864-018-4443-1) contains supplementary material, which is available to authorized users.

Rainbow trout were fed a diet containing phytase-sprayed and phytasepretreated soybean meal with different phytase levels. The single factor random block design was used to analyze the effects on rainbow trout of dietary phytase supplementation on growth performance, nutritional ingredient digestibility and nutrient excretion. After 90 days, the results showed that feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly improved and specific growth rate (SGR) was not affected by spraying phytase, but SGR, FCR and PER were not significantly improved by phytase pretreatment. A digestibility trial conducted after the feeding trial showed that apparent digestibility coefficient (ADC) of diet protein and minerals was increased with phytase supplementation. However, there was a negative effect of phytase on the ADC of lipid. The excretion experiment showed that the supplementation of phytase resulted in decreased nutrient excretion in feces, but lipid excretion was slightly increased with phytase supplementation. In addition, the results of P excretion and ADC of P analyzed by t-test showed that phytase pre-treatment method should be a more rational method than the spraying method. The results of SGR, ADC of P and P excretion analyzed by quadratic regression indicated that 2,000-3,000 U/kg levels by the spraying method could be a rational range of phytase supplementation, and about 1,000 U/kg should be an optimal level by the pretreatment method. Thus, use of phytase in rainbow trout feeds can have economic and environmental benefits.

WRKY transcription factors play pivotal roles in regulation of stress responses. This study identified 79 WRKY genes in potato (Solanum tuberosum). Based on multiple sequence alignment and phylogenetic relationships, WRKY genes were classified into three major groups. The majority of WRKY genes belonged to Group II (52 StWRKYs), Group III had 14 and Group I consisted of 13. The phylogenetic tree further classified Group II into five sub-groups. All StWRKY genes except StWRKY79 were mapped on potato chromosomes, with eight tandem duplication gene pairs and seven segmental duplication gene pairs found from StWRKY family genes. The expression analysis of 22 StWRKYs showed their differential expression levels under various stress conditions. Cis-element prediction showed that a large number of elements related to drought, heat and salicylic acid were present in the promotor regions of StWRKY genes. The expression analysis indicated that seven StWRKYs seemed to respond to stress (heat, drought and salinity) and salicylic acid treatment. These genes are candidates for abiotic stress signaling for further research.

RNA-cleaving DNAzymes have been demonstrated as a promising platform for sensing metal ions. However, the poor biological imaging performance of RNA-cleaving DNAzyme-based fluorescent probes has limited their intracellular applications. Compared with traditional one-photon fluorescence imaging, two-photon (TP) fluorescent probes have shown advantages such as increased penetration depth, lower tissue autofluorescence, and reduced photodamage. Herein, for the first time, we developed an RNA-cleaving DNAzyme-based TP imaging probe (TP-8-17ES-AuNP) for Zn detection in living cells by modifying a Zn-specific DNAzyme (8-17) with a TP fluorophore (TP-8-17ES) and using gold nanoparticles (AuNPs) for intracellular delivery. The modified TP-8-17ES exhibits good two-photon properties and excellent photostability. For the TP-8-17ES-AuNP, in the absence of Zn, the TP fluorophore is quenched by both AuNPs and the molecular quencher. Only in the presence of Zn does the DNAzyme cleave the TP fluorophore-labeled substrate strand, resulting in fluorescence enhancement and TP imaging. Such probe shows remarkable selectivity of Zn over other metal ions existing in the biological environment. Benefiting from the labeled TP fluorophore, the near-infrared (NIR) excited probe has the capability of TP imaging of Zn in living cells and tissue with a deep tissue penetration up to 160 μm. This method can be generally applied to detect other metal ions in biological systems under TP imaging with higher tissue penetration ability and lower phototoxicity.

Photodynamic therapy (PDT) has been applied in clinical cancer treatment. Here we report an aptamer-functionalized nanoscale metal-organic framework for targeted PDT. Our nanosystem can be easily prepared and successfully used for targeted PDT with a significantly enhanced therapeutic efficacy in vitro and in vivo.Methods: By combining the strong binding ability between phosphate-terminated aptamers and Zr-based nanoscale metal-organic frameworks (Zr-NMOFs) and the intercalation of photosensitizer TMPyP4 within the G-quadruplex DNA structure, TMPyP4-G4-aptamer-NMOFs were prepared. The characteristics and photodynamic performance of TMPyP4-G4-aptamer-NMOFs were examined after preparation. Then, we studied their stability, specific recognition ability, and phototoxicity in vitro. For in vivo experiments, the nanosystem was intratumorally injected into a HeLa subcutaneous xenograft tumor mouse model. After irradiation on day 0, mice were further injected with the nanosystem on day 5 and were again subjected to laser irradiation for 30 min. Tumor volumes and body weights of all mice were measured by caliper every 2 days after the treatment.Results: The nanosystem induced 90% cell death of targeted cells. In contrast, the control cells maintained about 40% cell viability at the same concentration of nanosystem. For the in vivo experiments, the nanosystem-treated group maintained more than 76% inhibition within the entire experimental period.Conclusion: We have demonstrated that our smart TMPyP4-G4-sgc8-NMOFs nanosystem can be used for targeted cancer therapy with high efficiency.