Assessment of seed- and seedling-related traits in Santalum album (Indian sandalwood) reveals high adaptive potential.

Seed and seedling traits govern plant fitness and persistence and are influenced by the interaction between the plant and its environment. Changing climatic and edaphic conditions will drastically affect early fitnessrelated traits and can alter the demography and species distribution range. It is widely documented that trait variation among populations may increase resilience of tree communities and reduce the risk of extinction under future climates. In the present study, variation in seed and seedling traits were documented from seven populations of Santalum album representing the natural distribution range of the species in the Indian subcontinent. Significant intra-specific variation was documented in seed and seedling traits, indicating high adaptive potential of the species. Further, the measured traits were correlated with climatic variables. No significant correlation was predicted for seed-related traits, while seedling-related traits like shoot and root weight, photochemical reflectance index, relative water content, and root-shoot ratio correlated with different climatic parameters. Variance partitioning revealed predominant combined effect of environment and genotype on seed traits except seed weight, which was governed by genotypic effect. The dominance of genotypic effect was documented for all seed leachate parameters, while seedling-related traits were predominantly affected by the environment. Conservation of sandalwood genetic resources will benefit from the insights gained from the variability recorded in these fitness-related traits, which are likely to affect the adaptive potential of the species.

Integrated mRNA and small RNA sequencing reveals post-transcriptional regulation of the sesquiterpene pathway in Santalum album L. (Indian sandalwood).

Key message: In sandalwood, negative pattern of regulation by miRNAs was documented in key genes from the sesquiterpene pathway, with cytochrome P450 reductase showing maximum miRNA targets, followed by sesquisabianene synthase 1. Abstract: A comprehensive knowledge of the molecular regulation of sesquiterpene biosynthetic pathway through transcriptomic studies is well established in Santalum album (Indian Sandalwood). However, the post-transcriptional regulation of the genes regulating the pathway is still elusive in this genus. In the present study, an integrated analysis of wood transcriptome and small RNA datasets was conducted to investigate the role of miRNAs in regulating the expression of transcripts involved in santalol production mediated by the sesquiterpene biosynthesis pathway. A total of 24,237 transcripts were annotated from the wood transcriptome, and 45 transcripts were mapped to the sesquiterpenoid pathway. Small RNA data analysis identified 257 conserved miRNAs belonging to 50 families and 7 novel putative miRNAs. Sa-miR156, Sa-miR396, Sa-miR166, and Sa-miR319 had the most number of members among the miRNA families. An integrated analysis predicted 69 miRNA members belonging to 12 families that targeted 12 transcripts from the sesquiterpene pathway, with a maximum of 24 miRNAs regulating cytochrome P450 reductase, followed by sesquisabianene synthase 1, which was targeted by 23 miRNAs. Validation of miRNA-mRNA interaction by qRT-PCR revealed a negative pattern of regulation in six miRNA-mRNA target pairs across wood tissues sourced from four genotypes. The present study provides the first crucial insight into the post-transcriptional regulation of the sesquiterpene pathway genes in the genus Santalum and opens up a new perspective in metabolite engineering for enhanced essential oil production in sandalwood. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03816-4.

Effects of early childhood lead exposure on academic performance and behaviour of school age children.

AIM: To determine whether early lead exposure at levels below 10 microg/dl has an impact on educational and behavioural outcomes at school. METHODS: Venous samples were taken from a subgroup of the Avon Longitudinal Study of Parents and Children (ALSPAC) attending a research clinic at 30 months of age (n = 582), and lead levels were measured by atomic absorption spectrometry. Developmental, behavioural and standardised educational outcomes (Standard Assessment Tests, SATs) were collected on these children at age 7-8 years. In the analysis, blood lead concentration was investigated both as a continuous covariate and as a categorical variable. RESULTS: 488 cases (84%) had complete data on confounders and outcomes. After adjustment for confounders and using a log dose-response model for lead concentration, blood lead levels showed significant associations with reading, writing and spelling grades on SATs, and antisocial behaviour. A doubling in lead concentration was associated with a 0.3 point (95% CI -0.5 to -0.1) decline in SATs grades. Treating lead levels categorically, with the reference group 0-2 microg/dl, no effects on outcomes were apparent at 2-5 microg/dl, but levels of 5-10 microg/dl were associated with a reduction in scores for reading (OR 0.51, p = 0.006) and writing (OR 0.49, p = 0.003). Lead levels >10 microg/dl were also associated with increased scores for antisocial behaviour (OR 2.9, p = 0.040) and hyperactivity (OR 2.82, p = 0.034). CONCLUSIONS: Exposure to lead early in childhood has effects on subsequent educational attainment, even at blood levels below 10 microg/dl. These data suggest that the threshold for clinical concern should be reduced to 5 microg/dl.

Plasmid loss in plasmid-carrying strains of Escherichia coli treated with phenoxazines and an approach to study their DNA binding properties.

The effect of subinhibitory concentrations of 2-trifluoromethyl-N(10)-substituted phenoxazines on plasmid-coded antibiotic resistance in Escherichia coli was investigated. Phenoxazine treatment resulted in the loss of resistance markers to an extent of 8-63% in all the strains tested, and the disappearance of plasmid DNA in phenoxazine sensitive colonies was evidenced by agarose gel electrophoresis. The resistant strains were sensitized in the presence of phenoxazines with a concomitant reduction in the MIC (minimum inhibitory concentration) values. The UV, fluorescence spectral, and ethidium bromide displacement agarose gel assay methods revealed that phenoxazines are intercalated with plasmid DNA. Progressive addition of DNA led to a significant reduction in the peak intensity of the absorption maximum of phenoxazine derivative. Further, destabilization of ethidium bromide-DNA complex as seen from fluorescence microscopy in the presence of phenoxazines was observed. The potency of phenoxazines to sensitize the resistant organisms follows the order butyl > propyl > acetyl derivatives.

Sensitization of multidrug resistant (MDR) cancer cells to vinblastine by novel acridones: correlation between anti-calmodulin activity and anti-MDR activity.

Multidrug resistance (MDR) of cancer cells remains to be an important cause of chemotherapy failure. Search for the new MDR reversal agents is still an unceasing challenge for the scientists. In an attempt to find clinically useful modulators of MDR, a series of 19 N(10)-substituted-2-bromoacridones has been synthesized. Parent compound 1, prepared by the Ullmann condensation of o-chlorobenzoic acid and p-bromoaniline, undergoes N-alkylation in the presence of a phase transfer catalyst. N-(omega-Chloroalkyl) analogues were subjected to iodide catalyzed nucleophilic substitution reaction with various secondary amines to get the products 3-10 and 12-19, which increased the uptake of vinblastine (VLB) in MDR KBCh(R)-8-5 cells to a greater extent (1.25 to 1.9-fold) than did a similar concentration of the standard modulator, verapamil (VRP). Results of the efflux experiment showed that each modulator significantly inhibited the efflux of VLB, suggesting that they may be competitors for P-gp. All the compounds effectively compete with [(3)H] azidopine for binding to P-gp, pointed out this transport membrane protein as their likely site of action. Compounds at IC(10) were evaluated for their efficacy to modulate the cytotoxicity of VLB in KBCh(R)-8-5 cells and found that the modulators enhanced the cytotoxicity of VLB by 3.8 to 34-fold. The study on the structure-activity relationship revealed that substitution of hydrogen atom at position C-2 in acridone nucleus by a bromine atom increased the cytotoxic and anti-MDR activities. The ability of acridones to inhibit calmodulin-dependent cyclic AMP phosphodiesterase has been determined and the results have shown a strong positive correlation between anti-calmodulin activity and cytotoxicity in KBCh(R)-8-5 cells or anti-MDR activity.

Inhibition of calmodulin-dependent cyclic AMP phosphodiesterase by phenoxazines.

Phenoxazine derivatives were examined for their ability to inhibit the calmodulin-mediated activation of phosphodiesterase, which is based on the hydrolysis of cAMP to AMP by phosphodiesterase in the presence or absence of inhibitor, followed by quantitative analysis by HPLC method. Anticalmodulin activity of phenoxazines with respect to substitution at C-2 position follows the order: 2-trifluoromethyl>2-chloro>unsubstituted phenoxazines. The interaction of phenoxazines with calmodulin using fluorescence spectroscopy has been performed. Binding study showed that calmodulin has two types of binding sites for phenoxazines. One is high affinity binding site (Kd value 0.07-0.46 microM) and the other, a low affinity binding site (Kd value 0.7-34.5 microM). The change in secondary structure of calmodulin upon binding to phenoxazines was studied by circular dichroism (CD) method, which showed that the percentage of helicity decreased with an extensive change in tertiary structure of calmodulin. Kinetic analysis of the phenoxazine-calmodulin interaction showed that phenoxazines competitively inhibited the activation of phosphodiesterase without affecting Vmax. Thus, these studies showed a good correlation between the ability of phenoxazines to block the activation of phosphodiesterase and their ability to bind to the activator.

Interaction of 2-chloro-N10-substituted phenoxazine with DNA and effect on DNA melting.

Five N10-substituted phenoxazines having different R groups and -Cl substitution at C-2 were found to bind to calf -thymus DNA and plasmid DNA with high affinity as seen from by UV and CD spectroscopy. The effect of phenoxazines on DNA were studied using DNA-ethidium bromide complexes. Upon addition of phenoxazines, the ethidium bromide dissociated from the complex with DNA. The binding of phenoxazines to plasmid PUC18 reduced ethidium bromide binding as seen from the agarose gel electrophoresis. Butyl, and propyl substituted phenoxazines were able to release more ethidium bromide compared with that of acetyl substitution. Addition of phenoxazines also enhanced melting temperature of DNA.

Evaluation of oral, pharyngeal, laryngeal and esophageal cancer risk in reverse smokers of chuttas.

Reverse smoking of chuttas seems to have no significance for the development of cancer of the hypopharynx, esophagus, larynx and nasopharynx. The conventional chutta smoker runs a slight risk of developing hypopharyngeal cancer. Other smoking and chewing habits do not seem to play any role in our area as these habits are very uncommon.