Identifying genetic variation associated with environmental gradients and drought-tolerance phenotypes in ponderosa pine.

As climate changes, understanding the genetic basis of local adaptation in plants becomes an ever more pressing issue. Combining genotype-environment association (GEA) with genotype-phenotype association (GPA) analysis has an exciting potential to uncover the genetic basis of environmental responses. We use these approaches to identify genetic variants linked to local adaptation to drought in Pinus ponderosa. Over 4 million Single Nucleotide Polymorphisms (SNPs) were identified using 223 individuals from across the Sierra Nevada of California. 927,740 (22.3%) SNPs were retained after filtering for proximity to genes and used in our association analyses. We found 1374 associated with five major climate variables, with the largest number (1151) associated with April 1st snowpack. We also conducted a greenhouse study with various drought-tolerance traits measured in first-year seedlings of a subset of the genotyped trees grown in the greenhouse. 796 SNPs were associated with control-condition trait values, while 1149 were associated with responsiveness of these traits to drought. While no individual SNPs were associated with both the environmental variables and the measured traits, several annotated genes were associated with both, particularly those involved in cell wall formation, biotic and abiotic stress responses, and ubiquitination. However, the functions of many of the associated genes have not yet been determined due to the lack of gene annotation information for conifers. Future studies are needed to assess the developmental roles and ecological significance of these unknown genes.

Expression quantitative trait loci mapping identified PtrXB38 as a key hub gene in adventitious root development in Populus.

Plant establishment requires the formation and development of an extensive root system with architecture modulated by complex genetic networks. Here, we report the identification of the PtrXB38 gene as an expression quantitative trait loci (eQTL) hotspot, mapped using 390 leaf and 444 xylem Populus trichocarpa transcriptomes. Among predicted targets of this trans-eQTL were genes involved in plant hormone responses and root development. Overexpression of PtrXB38 in Populus led to significant increases in callusing and formation of both stem-born roots and base-born adventitious roots. Omics studies revealed that genes and proteins controlling auxin transport and signaling were involved in PtrXB38-mediated adventitious root formation. Protein-protein interaction assays indicated that PtrXB38 interacts with components of endosomal sorting complexes required for transport machinery, implying that PtrXB38-regulated root development may be mediated by regulating endocytosis pathway. Taken together, this work identified a crucial root development regulator and sheds light on the discovery of other plant developmental regulators through combining eQTL mapping and omics approaches.

Novel candidate genes for lignin structure identified through genome-wide association study of naturally varying Populus trichocarpa.

Populus is a promising lignocellulosic feedstock for biofuels and bioproducts. However, the cell wall biopolymer lignin is a major barrier in conversion of biomass to biofuels. To investigate the variability and underlying genetic basis of the complex structure of lignin, a population of 409 three-year-old, naturally varying Populus trichocarpa genotypes were characterized by heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR). A subsequent genome-wide association study (GWAS) was conducted using approximately 8.3 million single nucleotide polymorphisms (SNPs), which identified 756 genes that were significantly associated (-log10(p-value)>6) with at least one lignin phenotype. Several promising candidate genes were identified, many of which have not previously been reported to be associated with lignin or cell wall biosynthesis. These results provide a resource for gaining insights into the molecular mechanisms of lignin biosynthesis and new targets for future genetic improvement in poplar.

Microwave-Assisted Chitosan-Functionalized Graphene Oxide as Controlled Intracellular Drug Delivery Nanosystem for Synergistic Antitumour Activity.

To achieve better antitumour efficacy, it is urgent to improve anticancer drug delivery efficiency in targeting cancer cells. In this work, chitosan-functionalized graphene oxide (ChrGO) nanosheets were fabricated via microwave-assisted reduction, which were employed to the intracellular delivery nanosystem for anticancer drug agent in breast cancer cells. Drug loading and release research indicated that adriamycin can be efficiently loaded on and released from the ChrGO nanosheets. Less drug release during delivery and better biocompatibility of ChrGO/adriamycin significantly improve its safety and therapeutic efficacy in HER2-overexpressing BT-474 cells. Furthermore, ChrGO/adriamycin in combination with trastuzumab exhibited synergistic antitumour activity in BT-474 cells, which demonstrated superior therapeutic efficacy compared with each drug alone. Cells treated with trastuzumab (5 µg/mL) or equivalent ChrGO/adriamycin (5 µg/mL) each elicited 54.5% and 59.5% cell death, respectively, while the combination treatment with trastuzumab and ChrGO/adriamycin resulted in a dramatic 88.5% cell death. The dual-targeted therapy displayed higher apoptosis, indicating superior therapeutic efficacy due to the presence of different mechanisms of action. The combined treatment of ChrGO/adriamycin and trastuzumab in BT-474 cells induced cell cycle arrest and apoptosis, which ultimately led to the death of augmented cancer cells. This work has provided a facile microwave-assisted fabrication of ChrGO as a controlled and targeted intracellular drug delivery nanosystem, which is expected to be a novel promising therapy for treating HER2-overexpressing breast cancer cells.

Dual-targeted therapy in HER2-positive breast cancer cells with the combination of carbon dots/HER3 siRNA and trastuzumab.

Dual-targeted therapy in HER2-positive breast cancer cells with the combination of carbon dots/HER3 siRNA and trastuzumab resulted in enhanced antitumor activity, which overcomes the resistance to trastuzumab monotherapy. Herein, we have developed branched polyethylenimine-functionalized carbon dot (BP-CD) nanocarriers, which exhibited efficient green fluorescent protein gene delivery and expression. The positively charged BP-CDs allowed for effective nucleic acid binding and displayed a highly efficient small interfering RNA (siRNA)-mediated delivery targeting of cancer cells. The transfection of BP-CDs and HER3 siRNA complexes down-regulated HER3 protein expression and induced significant cell growth inhibition in BT-474 cells. BP-CDs/HER3 siRNA complexes induced cell death of BT-474 cells through G0/G1 cell cycle arrest and apoptosis. The combined treatment of BP-CDs/HER3 siRNA complexes and trastuzumab caused greater cell growth suppression in BT-474 cells when compared to either agent alone. The findings suggest that this dual-targeted therapy with the combination of BP-CDs/HER3 siRNA and trastuzumab represents a promising approach in breast cancer.

A novel anti-HER2 antibody GB235 reverses Trastuzumab resistance in HER2-expressing tumor cells in vitro and in vivo.

HER2 overexpression is frequently associated with tumor metastasis and poor prognosis of breast cancer. More evidence indicates that HER3 is involved in HER2-resistant therapies. Combination treatments with two or more different monoclonal antibodies are a promising strategy to overcome resistance to HER2 therapies. We presented a novel fully human HER2-targeted monoclonal antibody, GB235, screened from a phage-display library against the HER2 antigen. GB235 in combination with Trastuzumab overcomes resistance in HER2-positive tumors and results in more sustained inhibition of tumor growth over time. The competition binding assay showed that the epitopes of GB235 do not overlap with those of Pertuzumab and Trastuzumab on HER2. Further HER2 mutagenesis results revealed that the binding epitopes of GB235 were located in the domain III of HER2. The mechanism of action of GB235 in blocking HER2-driven tumors is different from the mechanisms of Trastuzumab or Pertuzumab. GB235 does not affect the heterodimerization of HER2 and HER3, whereas the GB235 combined treatment with Trastuzumab significantly inhibited heregulin-induced HER3 phosphorylation and downstream signaling. Moreover, GB235 in combination with Trastuzumab reversed the resistance to heregulin-induced proliferation in HER2-overexpressing cancer cell lines. GB235 combined with Trastuzumab treatment in xenograft models resulted in improved antitumor activity. Complete tumor suppression was observed in the HER2-positive NCI-N87 xenograft model treated with the combination treatment with GB235 and Trastuzumab. In a Trastuzumab-resistant patient-derived tumor xenograft model GA0060, GB235 plus Trastuzumab reversed the resistance to Trastuzumab monotherapy. Because GB235 showed a different working mechanism with Pertuzumab and Trastuzumab, these agents can be considered complementary therapy against HER2 overexpression tumors.

Biosynthesis and Antibacterial Activity of Silver Nanoparticles Using Yeast Extract as Reducing and Capping Agents.

Biosynthesis for the preparation of antimicrobial silver nanoparticles (Ag NPs) is a green method without the use of cytotoxic reducing and surfactant agents. Herein, shape-controlled and well-dispersed Ag NPs were biosynthesized using yeast extract as reducing and capping agents. The synthesized Ag NPs exhibited a uniform spherical shape and fine size, with an average size of 13.8 nm. The biomolecules of reductive amino acids, alpha-linolenic acid, and carbohydrates in yeast extract have a significant role in the formation of Ag NPs, which was proved by the Fourier transform infrared spectroscopy analysis. In addition, amino acids on the surface of Ag NPs carry net negative charges which maximize the electrostatic repulsion interactions in alkaline solution, providing favorable stability for more than a year without precipitation. The Ag NPs in combination treatment with ampicillin reversed the resistance in ampicillin-resistant E. coli cells. These monodispersed Ag NPs could be a promising alternative for the disinfection of multidrug-resistant bacterial strains, and they showed negligible cytotoxicity and good biocompatibility toward Cos-7 cells.

The genetics of drought tolerance in conifers.

Contents 1034 I. 1034 II. 1035 III. 1037 IV. 1038 V. 1042 VI. 1043 VII. 1045 References 1045 SUMMARY: As temperatures warm and precipitation patterns shift as a result of climate change, interest in the identification of tree genotypes that will thrive under more arid conditions has grown. In this review, we discuss the multiple definitions of 'drought tolerance' and the biological processes involved in drought responses. We describe the three major approaches taken in the study of genetic variation in drought responses, the advantages and shortcomings of each, and what each of these approaches has revealed about the genetic basis of adaptation to drought in conifers. Finally, we discuss how a greater knowledge of the genetics of drought tolerance may aid forest management, and provide recommendations for how future studies may overcome the limitations of past approaches. In particular, we urge a more direct focus on survival, growth and the traits that directly predict them (rather than on proxies, such as water use efficiency), combining research approaches with complementary strengths and weaknesses, and the inclusion of a wider range of taxa and life stages.

Rapid solid-phase microwave synthesis of highly photoluminescent nitrogen-doped carbon dots for Fe(3+) detection and cellular bioimaging.

Recently, carbon dots (CDs) have been playing an increasingly important role in industrial production and biomedical field because of their excellent properties. As such, finding an efficient method to quickly synthesize a large scale of relatively high purity CDs is of great interest. Herein, a facile and novel microwave method has been applied to prepare nitrogen doped CDs (N-doped CDs) within 8 min using L-glutamic acid as the sole reaction precursor in the solid phase condition. The as-prepared N-doped CDs with an average size of 1.64 nm are well dispersed in aqueous solution. The photoluminescence of N-doped CDs is pH-sensitive and excitation-dependent. The N-doped CDs show a strong blue fluorescence with relatively high fluorescent quantum yield of 41.2%, which remains stable even under high ionic strength. Since the surface is rich in oxygen-containing functional groups, N-doped CDs can be applied to selectively detect Fe(3+) with the limit of detection of 10(-5) M. In addition, they are also used for cellular bioimaging because of their high fluorescent intensity and nearly zero cytotoxicity. The solid-phase microwave method seems to be an effective strategy to rapidly obtain high quality N-doped CDs and expands their applications in ion detection and cellular bioimaging.

Hydrophilic and blue fluorescent N-doped carbon dots from tartaric acid and various alkylol amines under microwave irradiation.

The desired control of particle size, doping element composition, and surface structure of carbon dots (CDs) are vital for understanding the fluorescence mechanism and exploring their potential applications. Herein, nitrogen-doped CDs (N-doped CDs) have been synthesized with tartaric acid and various alkylol amines (monoethanolamine, biethanolamine and triethanolamine) under microwave irradiation. A systematic investigation was performed to characterize the N-doped CDs. It is found that with increasing nitrogen proportion, the fluorescent quantum yield and lifetime of N-doped CDs increases, whereas cell toxicity decreases. In other words, N-doped CDs synthesized by tartaric acid and monoethanolamine have the highest nitrogen content, the highest fluorescent quantum yield, the longest lifetime and the lowest cell toxicity. A corresponding mechanism has been proposed. Moreover, as-synthesized N-doped CDs have been applied for selectively detecting the Fe(3+) ion and writing letters as a fluorescent ink.

A novel lead compound CM-118: antitumor activity and new insight into the molecular mechanism and combination therapy strategy in c-Met- and ALK-dependent cancers.

The anaplastic lymphoma kinase (ALK) and the c-Met receptor tyrosine kinase play essential roles in the pathogenesis in multiple human cancers and present emerging targets for cancer treatment. Here, we describe CM-118, a novel lead compound displaying low nanomolar biochemical potency against both ALK and c-Met with selectivity over>90 human kinases. CM-118 potently abrogated hepatocyte growth factor (HGF)-induced c-Met phosphorylation and cell migration, phosphorylation of ALK, EML4-ALK, and ALK resistance mutants in transfected cells. CM-118 inhibited proliferation and/or induced apoptosis in multiple c-Met- and ALK-addicted cancer lines with dose response profile correlating target blockade. We show that the CM-118-induced apoptosis in c-Met-amplified H1993 NSCLC cells involved a rapid suppression of c-Met activity and c-Met-to-EGFR cross-talk, and was profoundly potentiated by EGFR inhibitors as shown by the increased levels of apoptotic proteins cleaved-PARP and Bim as well as reduction of the survival protein Mcl-1. Bim-knockdown or Mcl-1 overexpression each significantly attenuated apoptosis. We also revealed a key role by mTOR in mediating CM-118 action against the EML4-ALK-dependent NSCLC cells. Abrogation of EML4-ALK in H2228 cells profoundly reduced signaling capacity of the rapamycin-sensitive mTOR pathway leading to G 1 cell cycle arrest and mitochondrial hyperpolarization, a metabolic perturbation linked to mTOR inhibition. Depletion of mTOR or mTORC1 inhibited H2228 cell growth, and mTOR inhibitors potentiated CM-118's antitumor activity in vitro and in vivo. Oral administration of CM-118 at a wide range of well tolerated dosages diminished c-Met- and ALK phosphorylation in vivo, and caused tumor regression or growth inhibition in multiple c-Met- and ALK-dependent tumor xenografts in mice. CM-118 exhibits favorable pharmacokinetic and drug metabolism properties hence presents a candidate for clinical evaluation.