Morphological,phytochemical and genetic diversity of threatened Polygonatum verticillatum (L.) All. populations of different altitudes and habitat types in Himalayan region

Polygonatum verticillatum (L.) All. is an important medicinal herb that belongs to the family Asparagaceae. The rhizome of the species is used in Chyavanprash preparation and several other ayurvedic formulations. Numerous active constituents like saponins, alkaloids, phytohormones, flavonoids, antioxidants, lysine, serine, aspartic acid, diosgenin, β-sitosterol, etc. have been reported from this species. In this study, morphological, phytochemical, antioxidant and genetic variations of 11 distant populations of P. verticillatum were measured. Considerably (P < 0.05) higher variations were recorded among different populations of P. verticillatum using morphological, phytochemical and genetic diversity parameters. AGFW (above ground fresh weights); flavonols, FRAP (Ferric ion reducing antioxidant power) and NO (Nitric Oxide scavenging activity) were recorded maximum in Kafni population. Similarly, a significantly higher above and below ground dry weight was recorded in Mayawati and Surmoli populations respectively. Maximum phenolic content, tannins, and DPPH (2,2-diphenyl-1-picrylhydrazyl) activity were recorded in Milam population. A total of 165 individuals from 11 populations were assessed for genetic diversity using inter-simple sequence repeats (ISSR) marker. High genetic diversity (He = 0.35) was recorded in Himkhola and Surmoli populations while it was observed minimum (0.28) in the Mayawati population. Altitude showed a significant positive correlation with tannins (r = 0.674; P < 005) and DPPH (r = 0.820; P < 0.01). Phenol content exhibited a considerably positive relationship with He (r = 0.606; P < 0.05) and BGFW (r = 0.620; P < 0.05), flavonol displayed a positive correlation with Pp% (r = 0.606; P < 0.05). The population structure of P. verticillatum, exhibited that the optimal value of the K was 3 for its populations as determined by the ΔK statistic structure. Among populations, the amount of gene flow is higher (Nm = 1.717) among all sites. Hence, it can be concluded that P. verticillatum populations possess considerable variability in the collected populations. Likewise, the populations from Kafni, Satbunga and Himkhola with higher morphological, phytochemicals and genetic variability were prioritized and therefore recommended for cultivation and mass multiplication to meet the industrial demand for target species.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12298-021-01044-9.     

Lowering of intraocular pressure by topical application of Daucus carota seed extract in rabbits

In normotensive rabbits topical application of Daucus carota seed extract at the concentration of 0.3, 0.6 and 1.2% resulted in mean IOP reduction of 19.33. 23.20 and 25.61% respectively from baseline. As no significant difference was observed between the change in IOP in 0.6 and 1.2% extract treated groups, 0.6% concentration was chosen for further evaluation in rabbits with experimentally elevated IOP. In water loaded rabbits, maximum mean IOP reduction with 0.6% extract was 29.39%, which was comparable to pilocarpine. In steroid pretreated rabbits, maximum mean IOP reduction was 30.27% from baseline, which was significantly higher than pilocarpine. The extract showed a comparatively slower onset of action however, the duration of action was comparable to pilocarpine in all the experimental models.     

Genotoxic stress in plants: shedding light on DNA damage, repair and DNA repair helicases

Plant cells are constantly exposed to environmental agents and endogenous processes that inflict damage to DNA and cause genotoxic stress, which can reduce plant genome stability, growth and productivity. Plants are most affected by solar UV-B radiation, which damage the DNA by inducing the formation of two main UV photoproducts such as cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts (6-4PPs). Reactive oxygen species (ROS) are also generated extra- or intra-cellularly, which constitute yet another source of genotoxic stress. As a result of this stress, the cellular DNA-damage responses (DDR) are activated, which transiently arrest the cell cycle and allow cells to repair DNA before proceeding into mitosis. DDR requires the activation of Ataxia telangiectasia-mutated (ATM) and Rad3-related (ATR) genes, which regulate the cell cycle and transmit the damage signals to downstream effectors of cell-cycle progression. Since genomic protection and stability are fundamental to ensure and sustain plant diversity and productivity, therefore, repair of DNA damages is essential. In plants the bulky DNA lesions, CPDs and 6-4PPs, are repaired by a simple and error-free mechanism: photoreactivation, which is a light-dependent mechanism and requires CPD or 6-4PP specific photolyases. In addition to this direct repair process, the plants also have sophisticated light-independent general repair mechanisms, such as the nucleotide excision repair (NER) and base excision repair (BER). The completed plant genome sequences reveal that most of the genes involved in NER and BER are present in higher plants, which suggests that the network of in-built DNA-damage repair mechanisms is conserved. This article describes the insight underlying the DNA damage and repair pathways in plants. The comet assay to measure the DNA damage and the role of DNA repair helicases such as XPD and XPB are also covered.     

Ectonucleotidases in the kidney

Members of all four families of ectonucleotidases, namely ectonucleoside triphosphate diphosphohydrolases (NTPDases), ectonucleotide pyrophosphatase/phosphodiesterases (NPPs), ecto-5′-nucleotidase and alkaline phosphatases, have been identified in the renal vasculature and/or tubular structures. In rats and mice, NTPDase1, which hydrolyses ATP through to AMP, is prominent throughout most of the renal vasculature and is also present in the thin ascending limb of Henle and medullary collecting duct. NTPDase2 and NTPDase3, which both prefer ATP over ADP as a substrate, are found in most nephron segments beyond the proximal tubule. NPPs catalyse not only the hydrolysis of ATP and ADP, but also of diadenosine polyphosphates. NPP1 has been identified in proximal and distal tubules of the mouse, while NPP3 is expressed in the rat glomerulus and pars recta, but not in more distal segments. Ecto-5′-nucleotidase, which catalyses the conversion of AMP to adenosine, is found in apical membranes of rat proximal convoluted tubule and intercalated cells of the distal nephron, as well as in the peritubular space. Finally, an alkaline phosphatase, which can theoretically catalyse the entire hydrolysis chain from nucleoside triphosphate to nucleoside, has been identified in apical membranes of rat proximal tubules; however, this enzyme exhibits relatively high K _m values for adenine nucleotides. Although information on renal ectonucleotidases is still incomplete, the enzymes’ varied distribution in the vasculature and along the nephron suggests that they can profoundly influence purinoceptor activity through the hydrolysis, and generation, of agonists of the various purinoceptor subtypes. This review provides an update on renal ectonucleotidases and speculates on the functional significance of these enzymes in terms of glomerular and tubular physiology and pathophysiology.     

Nevirapine Resistance and Breast-Milk HIV Transmission: Effects of Single and Extended-Dose Nevirapine Prophylaxis in Subtype C HIV-Infected Infants

Background

Daily nevirapine (NVP) prophylaxis to HIV-exposed infants significantly reduces breast-milk HIV transmission. We assessed NVP-resistance in Indian infants enrolled in the “six-week extended-dose nevirapine” (SWEN) trial who received single-dose NVP (SD-NVP) or SWEN for prevention of breast-milk HIV transmission but who also acquired subtype C HIV infection during the first year of life.

Methods/Findings

Standard population sequencing and cloning for viral subpopulations present at ≥5% frequency were used to determine HIV genotypes from 94% of the 79 infected Indian infants studied. Timing of infection was defined based on when an infant''s blood sample first tested positive for HIV DNA. SWEN-exposed infants diagnosed with HIV by six weeks of age had a significantly higher prevalence of NVP-resistance than those who received SD-NVP, by both standard population sequencing (92% of 12 vs. 38% of 29; p = 0.002) and low frequency clonal analysis (92% of 12 vs. 59% of 29; p = 0.06). Likelihood of infection with NVP-resistant HIV through breast-milk among infants infected after age six weeks was substantial, but prevalence of NVP-resistance did not differ among SWEN or SD-NVP exposed infants by standard population sequencing (15% of 13 vs. 15% of 20; p = 1.00) and clonal analysis (31% of 13 vs. 40% of 20; p = 0.72). Types of NVP-resistance mutations and patterns of persistence at one year of age were similar between the two groups. NVP-resistance mutations did differ by timing of HIV infection; the Y181C variant was predominant among infants diagnosed in the first six weeks of life, compared to Y188C/H during late breast-milk transmission.

Conclusions/Significance

Use of SWEN to prevent breast-milk HIV transmission carries a high likelihood of resistance if infection occurs in the first six weeks of life. Moreover, there was a continued risk of transmission of NVP-resistant HIV through breastfeeding during the first year of life, but did not differ between SD-NVP and SWEN groups. As with SD-NVP, the value of preventing HIV infection in a large number of infants should be considered alongside the high risk of resistance associated with extended NVP prophylaxis.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00061321","term_id":"NCT00061321"}}NCT00061321     

Silver Fused Conducting Fiber Formation of Au–Ag Core-Shell Nanoparticles Mediated by Ascorbic Acid

In this paper, we report the spontaneous formation of fibrous structures consisting of assemblies of Au–Ag core-shell nanoparticles (NPs) from a solution consisting of Au–Ag core-shell NPs and l-ascorbic acid (AA). AA acted both as the reducing agent for the generation of NPs and also as the mediator for the formation of fibers. The process of fiber formation involved three steps—reduction of HAuCl₄ to Au NPs by AA, subsequent formation of Au–Ag core-shell NPs after addition of AgNO₃, and spontaneous formation of fibers from the mixtures in water. It took typically about 30 days to form complete fibers that are of lengths of several hundred micrometers to millimeters, although nanofibers started forming from the first day of solution preparation. The width of each of these fibers was typically about 1–4 μm with length of each segment of fiber bundle, on the order of 40 μm. Formation of fibers was also observed in absence of AgNO₃. These fibers consisted of Au NPs and polymer of AA degradation products and were not electrically conducting. Also, low concentrations of AgNO₃ produced fibers with low electrical conductivity. However, it was observed that increase in the amount of AgNO₃ leads to the formation of fibers that were electrically conducting with conductivity values in the range of metallic conductivity. Spectroscopic and electron microscopic investigations were carried out to establish the formation of fibers. The details of fiber formation mechanism under different conditions and electrical conductivities of the fibers are discussed in the article.     

Oily sludge degradation by bacteria from Ankleshwar, India

Three bacterial strains, Bacillus sp. SV9, Acinetobacter sp. SV4 and Pseudomonas sp., SV17 from contaminated soil in Ankleshwar, India were tested for their ability to degrade the complex mixture of petroleum hydrocarbons (such as alkanes, aromatics, resins and asphaltenes), sediments, heavy metals and water known as oily sludge. Gravimetric analysis showed that Bacillus sp. SV9 degraded approx. 59% of the oily sludge in 5 days at 30 °C whereas Acinetobacter sp. SV4 and Pseudomonas sp. SV17 degraded 37% and 35%. Capillary gas chromatographic analysis revealed that after 5 days the Bacillus strain was able to degrade oily sludge components of chain length C₁₂–C₃₀ and aromatics more effectively than the other two strains. Maximum drop in surface tension (from 70 to 28.4 mN/m) was accompanied by maximum biosurfactant production (6.7 g l⁻¹) in Bacillus sp. SV9 after 72 h, these results collectively indicating that this bacterial strain has considerable potential for bioremediation of oily sludge.