Untying the regulatory roles of miRNAs in CuO-NPs stress response mechanism in maize: A genome-wide sRNA transcriptome analysis

MicroRNAs (miRNAs), a group of tiny non-coding RNAs play pivotal role in plant responses to environmental stress. The present small RNA transcriptome study aims to untie the role of miRNAs in CuO-NPs stress adaptation in maize seedlings. Restricted seedling growth, enhanced ROS generation and higher membrane damage were recorded under CuO-NPs [<50 nm, 8 mM] treatment. Deep sequencing reveals 7 up- and 36 down-regulated known miRNAs from CuO-NPs challenged leaves. Gene ontology study demonstrates involvement of CuO-NPs responsive miRNAs in a variety of biological processes including plant growth (miR159a, miR159b), redox homeostasis (miR156e, miR395a), detoxification of heavy metals (miR156e, miR827), signal transduction (miR156e, miR156d), and cell signalling (miR167b-3p, miR393a). Enhanced transcriptional abundance of ABC transporter G family member 41 isoform X2 and HM-associated isoprenylated plant protein 45 isoform X1 might be involved in sequestration and detoxification of excess Cu, essential for metal homeostasis in maize. The miR528-5p mediated up-regulation of superoxide dismutase does not give much protection against CuO-NPs induced oxidative stress damages as evident after histochemical staining with NBT. Moreover, CuO-NPs stress mediated down regulation of miR396 could be an underlying cause of the restricted seedling growth. Taken together, our findings provide insights into the miRNA-guided stress regulatory networks involved in plant's adaptive responses to CuO-NPs stress.

The role of bacterial exopolysaccharides (EPS) in the synthesis of antimicrobial silver nanomaterials: A state-of-the-art review

The emergence of multi-drug resistant (MDR) pathogens poses a significant global health concern due to the failure of conventional medical treatment. As a result, the development of several metallic (Ag, Au, Zn, Ti, etc.) nanoparticles, has gained prominence as an alternative to conventional antimicrobial therapies. Among these, green-synthesized silver nanoparticles (AgNPs) have gained significant attention due to their notable efficiency and broad spectrum of antimicrobial activity. Bacterial exopolysaccharides (EPS) have recently emerged as a promising biological substrate for the green synthesis of AgNPs. EPS possess polyanionic functional groups (hydroxyl, carboxylic, sulfate, and phosphate) that effectively reduce and stabilize AgNPs. EPS-mediated AgNPs exhibit a wide range of antimicrobial activity against various pathogenic microbes, including Gram-positive and Gram-negative bacteria, as well as fungi. The extraction and purification of bacterial EPS play a vital role in obtaining high-quality and -quantity EPS for industrial applications. This study focuses on the comprehensive methodology of EPS extraction and purification, encompassing screening, fermentation optimization, pretreatment, protein elimination, precipitation, and purification. The review specifically highlights the utilization of bacterial EPS-mediated AgNPs, covering EPS extraction, the synthesis mechanism of green EPS-mediated AgNPs, their characterization, and their potential applications as antimicrobial agents against pathogens. These EPS-mediated AgNPs offer numerous advantages, including biocompatibility, biodegradability, non-toxicity, and eco-friendliness, making them a promising alternative to traditional antimicrobials and opening new avenues in nanotechnology-based approaches to combat microbial infections.

microRNAomic profiling of maize root reveals multifaceted mechanisms to cope with Cr (VI) stress

Chromium (Cr) contamination of soil and water poses serious threats to agricultural crop production. MicroRNAs (miRNAs) are conserved, non-coding small RNAs that play pivotal roles in plant growth, development and stress responses through fine-tuning of post-transcriptional gene expression. To better understand the molecular circuit of Cr-responsive miRNAs, two sRNA libraries were prepared from control and Cr (VI) [100 ppm] exposed maize roots. Using deep sequencing, we identified 80 known (1 up and 79 down) and 18 downregulated novel miRNAs from Cr (VI) challenged roots. Gene ontology (GO) analysis reveals that predicted target genes of Cr (VI) responsive miRNAs are potentially involved in diverse cellular and biological processes including plant growth and development (miR159c, miR164d, miR319b-3p and zma_25.145), redox homeostasis (miR528-5p, miR396a-5p and zma_9.132), heavy metal uptake and detoxification (miR159f-5p, 164e-5p, miR408a, miR444f and zma_2.127), signal transduction (miR159f, miR160a-5p, miR393a-5p, miR408-5p and zma_43.158), cell signalling (miR156j, 159c-5p, miR166c-5p and miR398b). Higher accumulation of Cr in maize roots might be due to upregulation of ABC transporter G family member 29 targeted by miR444f. Instead of isolated increase in SOD expression, significant decline in GSH:GSSH ratio and histochemical staining strongly suggest Cr (VI) stress mediated disruption of ROS scavenging machinery thus unbalancing normal cellular homeostasis. Moreover, miR159c-mediated enhanced expression of GAMYB might be a reason for impaired root growth under Cr (VI) stress. In a nutshell, the present microRNAomic study sheds light on the miRNA-target gene regulatory network involved in adaptive responses of maize seedlings to Cr (VI) stress.

DNA hypomethylation is the plausible driver of heat stress adaptation in Linum usitatissimum

Heat stress has a significant impact on the climatic adaptation of flax, a cool-season economic crop. Genome-wide DNA methylation patterns are crucial for understanding how flax cultivars respond to heat adversities. It is worth noting that the DNA methylome in flax has yet to be investigated at the nucleotide level. Although heat stress above 40°C caused oxidative damage in flax leaves, 5-azacytidine, a hypomethylating agent, reduced this effect by 15%-24%. Differences in the expression of the LuMET1 (DNA methyltransferase) gene suggested that DNA methylation/demethylation may play a major role in the flax heat stress response. Thus, whole-genome bisulfite sequencing-derived DNA methylation profiles in flax, with or without heat stress and 5-azaC, were developed and analyzed here. In response to heat stress, a high percentage of significant differentially methylated regions (DMRs), particularly hypomethylated DMRs, were identified in the CHH nucleotide sequence context (H = A/T/C). Some of these DMRs overlapped with transposable element insertions. The majority of DMRs were discovered in intergenic regions, but several DMR loci were also found near genes relevant to heat stress response and epigenetic processes. These DMRs, in particular, are linked to CpG islands, implying a possible role in promoter methylation and gene silencing. The DMRs discovered in this study are crucial for understanding and identifying the key players in heat stress response in flax, which will help in developing climate-smart flax varieties.

Sweet Potato Peels and Cancer Prevention

A bioassay-guided fractionation of an alcoholic extract from the peels of Ipomoea batatas Lam has been carried out. Sulforhodamine B and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays were used to evaluate the anticancer and antioxidant potential, respectively, while silica gel column chromatography (CC) was used to isolate compounds that were characterized using 1D- and 2D-NMR (Nuclear Magnetic Resonance) and mass spectrometry. The alcoholic extract was fractionated into n-hexane, ethyl acetate, n-butanol, and water. The n-hexane fraction which showed the most promising anticancer activity was further fractionated via silica gel CC into IB-F002A, IB-F002B, and IB-F002C. Of these, IB-F002C was the most active with IC₅₀ values 24.75, 47.91, 52.37, 34.17, 46.07, and 25.89 μg/ml against breast, colon-1, colon-2, ovary, lung, and head/neck cancer cell lines, respectively. The bioassay-guided isolation from IB-F002C afforded a glucocerebroside, which showed 10.51%, 12.19%, 16.14%, and 34.05% inhibition of head and neck, breast-1, colon-1, and ovarian cancer cell lines, respectively. Octadecyl coumarate, 7-hydroxycoumarin, and 6-methoxy-7-hydroxycoumarin that showed different antioxidant potentials were also identified in this study. Sweet potato peel, which is usually discarded as waste, contains constituents that can serve as dietary components to prevent the development of different types of cancer.

Impact of nano-CuO stress on rice (Oryza sativa L.) seedlings

Indiscriminate release of metal oxide nanoparticles (NPs) into the environment due to anthropogenic activities has become a serious threat to the ecological system including plants. The present study assesses the toxicity of nano-CuO on rice (Oryza sativa cv. Swarna) seedlings. Three different levels of stress (0.5 mM, 1.0 mM and 1.5 mM suspensions of copper II oxide, <50 nm particle size) were imposed and seedling growth performance was studied along control at 7 and 14 d of experiment. Modulation of ascorbate-glutathione cycle, membrane damage, in vivo ROS detection, foliar H₂O₂ and proline accumulation under nano-CuO stress were investigated in detail to get an overview of nano-stress response of rice. Seed germination percentage was significantly reduced under stress. Higher uptake of Evans blue by nano-CuO stressed roots over control indicates loss of root cells viability. Presence of dark blue and deep brown spots on leaves evident after histochemical staining with NBT and DAB respectively indicate severe oxidative burst under nano-copper stress. APX activity was found to be significantly increased in 1.0 and 1.5 mM CuO treatments. Nevertheless, elevated APX activity might be insufficient to scavenge all H₂O₂ produced in excess under nano-CuO stress. That may be the reason why stressed leaves accumulated significantly higher H₂O₂ instead of having enhanced APX activity. In addition, increased GR activity coupled with isolated increase in GSH/GSSG ratio does not seem to prevent cells from oxidative damages, as evident from higher MDA level in leaves of nano-CuO stressed seedlings over control. Enhanced proline accumulation also does not give much protection against nano-CuO stress. Decline in carotenoids level might be another determining factor of meager performance of rice seedlings in combating nano-CuO stress induced oxidative damages.

Trends in incidence of childhood cancer in Canada, 1992-2006

INTRODUCTION

Cancer is the leading cause of disease-related death in children aged 1 to 14 years in Canada. Despite the importance to public health of childhood cancer, there have been few reports on Canadian trends published in the peer-reviewed literature. This study examines childhood cancer trends by age, sex, and province of residence using the most current cancer registration data.

METHODS

Data from the population-based Canadian Cancer Registry were used to compute incidence trends in primary cancers diagnosed between 1992 and 2006 in children (0-14 years) for the 12 major diagnostic groups of the International Classification of Childhood Cancer, 3rd Edition.

RESULTS

Between 1992 and 2006, incidence rates for all cancers remained stable, although trends varied by cancer type. We observed a significant decrease in retinoblastoma in boys for the entire period (-6.5% per year) and an increase in leukemia from 1992 to 1999 (+3.5% per year). In girls, there was a significant decrease in renal tumours from 1998 to 2006 (-5.7% per year) and an increase in hepatic tumours from 1997 to 2006 (+8.1% per year). Differences by age and province were also apparent. Some caution should be exercised when interpreting trends involving a small number of cases per year and those with wide 95% confidence intervals.

CONCLUSIONS

Our findings suggest an ongoing need for population-based surveillance and etiologic research.

Use of paediatric versus adult oncology treatment centres by adolescents 15-19 years old: the Canadian Childhood Cancer Surveillance and Control Program

The aim of this study was to evaluate the treatment patterns of adolescents with cancer in Canada to ensure this population is receiving the most appropriate care. The Treatment and Outcome Surveillance (TOS) system was compared with the Canadian Cancer Registry (CCR) to estimate the proportion of adolescents (15-19 years) treated in Canadian paediatric oncology centres from 1995 to 2000 inclusive. Using TOS, the demographic, disease, and clinical characteristics of adolescents treated in paediatric versus adult centres in the Prairies were compared and differences were tested statistically. Approximately 30% of Canadian adolescents with cancer were treated in a paediatric centre. Adolescents treated in an adult centre were older at diagnosis and more likely to have carcinoma or germ cell tumours. The time between symptom onset and first treatment was longer for these adolescents, primarily due to the time between first health-care contact and assessment by a treating oncologist or surgeon. They were less likely to be enrolled in a clinical trial. These results suggest that care for adolescents with cancer in Canada is less satisfactory than for younger children, and can be improved.

Tandem mass spectra of ammonium ion, metal ion and ligated metal ion adducts of acyclic sugar derivatives

The tandem mass (MS/MS) spectra of ammonium ion, metal ion and ligated metal ion adducts of chain-extended acyclic nitro-containing deoxyglucose and deoxygalactose derivatives have been studied. The ammonium adducts fragment primarily by elimination of ammonia followed by acetic acid, thus not giving much structural information. In contrast, cationization of these compounds by metal ions and ligated metal ions gave structurally informative and useful fragment ions on MS/MS. The metal ions and ligated metal ions play an important role in controlling and directing fragmentation. Retro-aldol fragmentation is facilitated by metal ions such as Li(+), Na(+), Ag(+) and Cu(+), whereas the adducts with higher alkali metal ions such as Rb(+) and Cs(+) fragment to give only the corresponding metal ions. The divalent metal ions such as Cu(2+) and Ba(2+) also induce retro-aldol fragmentation. However, the charge is carried by the aldehyde fragment in the case of Cu(2+) adducts, whereas the nitroalkane fragment carries the charge in the case of Ba(2+) adducts. Ligated metal ions such as ZnCl(+), CuCl(+), InCl(2) (+) and BaCl(+) also behave similarly and induce retro-aldol fragmentation in these acyclic sugars. Both the metal ion and ligated metal ion adducts can fragment by elimination of metal-containing neutral molecules.