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Papers by Nisha Singh

Journal of Medicinal Plants Research, Jul 18, 2011

Syzygium cordatum (Myrtaceae), a recalcitrant tree species, commonly known as 'umdoni'or water be... more Syzygium cordatum (Myrtaceae), a recalcitrant tree species, commonly known as 'umdoni'or water berry is known for its medicinal uses. Extracts of the plant are taken as remedies for various ailments including tuberculosis. This study reports on developing a protocol for in vitro propagation of S. cordatum and the detection of important triterpenes in in vitro and field grown plants. A hundred percent seed germination occurred on Murashige and Skoog (MS) medium (Murashige and Skoog, 1962) within 2 to 3 days of culture. In vitro developed Syzigium shoots were cultured on MS medium supplemented with various concentrations of Thidiazuron (TDZ) and Indole butyric acid (IBA) for their multiplication. MS medium supplemented with 0.5 mg L-1 TDZ and 1.0 mg L-1 IBA is proved to be most effective in which 4.3 shoots per explants were obtained. The best rooting medium was ½ MS or ½ woody plant medium (WPM) supplemented with 1 mgL-1 IBA in which 92% rooting with an average of 3.7 roots per plantlet were obtained. In vitro and field leaf materials were oven-dried, grounded into fine powders and extracted sequentially in hexane, dichloromethane, ethyl acetate and methanol. Betulinic acid (BA), oleanolic acid (OA) and ursolic acid (UA) were investigated in vitro and field plants by thinlayer chromatography (TLC), column fractionation using silica gel, and nuclear magnetic resonance (NMR) spectroscopy.

Cancer bush (Sutherlandia frutescens L.) is a medicinally important perennial legume native to so... more Cancer bush (Sutherlandia frutescens L.) is a medicinally important perennial legume native to southern Africa. S. frutescens seeds exhibit dormancy like many other legumes. Experiments using physical, mechanical and chemical pre-sowing treatments were conducted to determine the germination response of this species. Among various treatments, soaking the intact seeds for 30 min in concentrated H2SO4 resulted in a high final germination percentage of 97.5% in day 14 of culture. However, seed dormancy was completely broken by mechanical scarification in which 100% germination was obtained in day 2 of culture. The results indicated that S. frutescens seeds possess exogenous dormancy due to the hard seed coat which is the main inhibitor of germination.

Annals of Proteomics and Bioinformatics, 2021

Pigeonpea is one of the important legume crops with high protein content and nutritional traits. ... more Pigeonpea is one of the important legume crops with high protein content and nutritional traits. It has enormous potency for its widespread adoption by farming communities. It is affected by various kinds of biotic and abiotic stresses. In the context, of biotic stresses Sterility mosaic disease (SMD) is one of the severe diseases in pigeonpea which ultimately lead to the drastic yield loss. The virus belongs to the genus Emaravirus, family- Fimoviridae. SMD is associated with two diverse types of Emaravirus, Pigeonpea sterility mosaic virus1 (PPSMV-1) and Pigeonpea sterility mosaic virus 2 (PPSMV-2). It is transmitted by the mite (Aceria cajani), mainly environmental contributing to the feasibility for the mites for the inoculation of the virus. The SMD is mainly governed by two genes SV1 that includes the dominant allele and serves as an inhibitory action on the resistance of the SV2. Methods for identification of the virus include RT-PCR, DIBA and ELISA using alkaline phosphatase...

The Nucleus, 2020

Food and nutritional security are an essential goals for the entire global population during clim... more Food and nutritional security are an essential goals for the entire global population during climate change scenarios. These twin challenges can be addressed by expanding the global cropping system by promoting grain and legume crops, especially pulses in India. Legume seeds are known as "meat for vegetarian diets". Ever-increasing pigeonpea consumption as a major source of protein necessitates the improvement of varieties for more efficient production. Pigeonpea is an important legume crop with high protein content and nutritional attributes for more than a billion people living in South Asia. This hardy legume has a considerable potential positive impact on the lives of poor farmers as compared to other legumes, due to better productivity under extreme environmental conditions such as heat, drought and low soil fertility. However, pigeonpea productivity is still low for decades because of sparse utilization of landraces and wild pigeonpea germplasm as genetic and genomic resources. Recent advances in next-generation sequencing, together with other "omics" technologies have significantly reinforced pigeonpea research. Despite the remarkable progress in these technologies, the analysis and mining of existing seed genomics data are still challenging due to the complexity of genetic inheritance, metabolic partitioning, and developmental regulations. The integration of "omics tools" is an effective strategy to discover critical regulators of various seed traits. To utilize its potential, a coordinated and comprehensive evaluation of germplasm is required. Identification of potential genes/alleles governing complex traits of seed quality and nutritional content such as seed weight, seed size, seed color, total protein content, amino acid, antioxidant, resistant starch and disease resistance are essential in genomic selection for quality trait improvement of pigeonpea. Therefore, we need to understand these complex genetic architectures of qualitative and quantitative traits in pigeonpea for the development of nutrient-dense varieties for value addition. It helps in reducing malnutrition, protein, energy, and amino acid deficiency in food and feed related problems that are common in the majority of the population and more specific to developing countries. In this review, a comprehensive discussion on recent advances in "omics" approaches, their use in pigeonpea seed quality, and nutritional trait investigations are presented along with the available databases and technological platforms and their applicability in the improvement of pigeonpea. This article highlights the catalog of important available resources to improve the knowledge base and its future utilization in pigeonpea crop improvement programs.

The Lancet HIV, 2021

Background Data on vaccine immunogenicity against SARS-CoV-2 are needed for the 40 million people... more Background Data on vaccine immunogenicity against SARS-CoV-2 are needed for the 40 million people globally living with HIV who might have less functional immunity and more associated comorbidities than the general population. We aimed to explore safety and immunogenicity of the ChAdOx1 nCoV-19 (AZD1222) vaccine in people with HIV. Methods In this single-arm open-label vaccination substudy within the protocol of the larger phase 2/3 trial COV002, adults aged 18-55 years with HIV were enrolled at two HIV clinics in London, UK. Eligible participants were required to be on antiretroviral therapy (ART), with undetectable plasma HIV viral loads (<50 copies per mL), and CD4 counts of more than 350 cells per µL. A prime-boost regimen of ChAdOx1 nCoV-19, with two doses was given 4-6 weeks apart. The primary outcomes for this substudy were safety and reactogenicity of the vaccine, as determined by serious adverse events and solicited local and systemic reactions. Humoral responses were measured by anti-spike IgG ELISA and antibody-mediated live virus neutralisation. Cell-mediated immune responses were measured by ex-vivo IFN-γ enzymelinked immunospot assay (ELISpot) and T-cell proliferation. All outcomes were compared with an HIV-uninfected group from the main COV002 study within the same age group and dosing strategy and are reported until day 56 after prime vaccination. Outcomes were analysed in all participants who received both doses and with available samples. The COV002 study is registered with ClinicalTrials.gov, NCT04400838, and is ongoing. Findings Between Nov 5 and Nov 24, 2020, 54 participants with HIV (all male, median age 42•5 years [IQR 37•2-49•8]) were enrolled and received two doses of ChAdOx1 nCoV-19. Median CD4 count at enrolment was 694•0 cells per µL (IQR 573•5-859•5). No serious adverse events occurred. Local and systemic reactions occurring during the first 7 days after prime vaccination included pain at the injection site (26 [49%] of 53 participants with available data), fatigue (25 [47%]), headache (25 [47%]), malaise (18 [34%]), chills (12 [23%]), muscle ache (19 [36%]), joint pain (five [9%]), and nausea (four [8%]), the frequencies of which were similar to the HIV-negative participants. Anti-spike IgG responses by ELISA peaked at day 42 (median 1440 ELISA units [EUs; IQR 704-2728]; n=50) and were sustained until day 56 (median 941 EUs [531-1445]; n=49). We found no correlation between the magnitude of the anti-spike IgG response at day 56 and CD4 cell count (p=0•93) or age (p=0•48). ELISpot and T-cell proliferative responses peaked at day 14 and 28 after prime dose and were sustained to day 56. Compared with participants without HIV, we found no difference in magnitude or persistence of SARS-CoV-2 spike-specific humoral or cellular responses (p>0•05 for all analyses). Interpretation In this study of people with HIV, ChAdOx1 nCoV-19 was safe and immunogenic, supporting vaccination for those well controlled on ART.

South African Journal of Botany, 1991

Morphological changes and the associated fungal colonization during decomposition of leaves of a ... more Morphological changes and the associated fungal colonization during decomposition of leaves of a mangrove, Bruguiera gymnorrhiza (Rhizophoraceae)

South African Journal of Botany, 1992

Successive fungal colonization of leaves of Bruguiera gymnorrhiza (L.) Lam. was investigated at B... more Successive fungal colonization of leaves of Bruguiera gymnorrhiza (L.) Lam. was investigated at Beachwood Mangrove Nature Reserve, Durban, using a litterbag technique. Bags of two different mesh sizes were used (1.0 x 0.5 mm and 2.5 x 5 mm), but no significant differences in mass loss were observed over a period of 18 weeks. Fusarium spp., Penicillium spp., Trichoderma sp., Verticillium sp. and Phoma sp., amongst others, colonized the leaves prior to and after submergence. The phylloplane fungi did not break down leaf components whilst the leaf was living. After submergence, microbial colonization increased. Cellulolytic assay demonstrated that all of the isolated fungi, except Mucor sp., were able to degrade cellulose. The C:N ratio of the litter decreased from 143.6:1 to 28.4:1, indicating an increase in nutrient value with decomposition. This work revealed the presence of some fungal taxa, most of which possess in vitro cellulolytic activity. Die rol van fungusse by die ontbinding van die blare van Bruguiera gymnorrhiza (L.) Lam. is met behulp van die afvalsak-tegniek in die Beachwood Mangliet-natuurreservaat, Durban, ondersoek. Sakke met twee verskillende maasgroottes (1.0 x 0.5 mm en 2.5 x 5 mm) is gebruik, maar geen betekenisvolle verskille in massaverlies is oor 'n tydperk van 18 weke waargeneem nie. Fusarium spp., Penicillium spp., Trichoderma sp., Verticillium sp. en Phoma sp. het die blare voor en na onderdompeling gekoloniseer. Die blaarlewende fungusse het blaarkomponente nie afgebreek terwyl die blaar nog lewend was nie. Na onderdompeling het mikrobiese kolonisering toegeneem. Sellulolitiese bepaling het getoon dat al die fungusse wat ge'lsoleer is, behalwe Mucor sp., sellulose kan afbreek. Die C:N-verhouding van die afval het afgeneem van 143.6:1 tot 28.4:1, 'n aanduiding van 'n toename in voedingswaarde met ontbinding. Hierdie werk het die aanwesigheid van swamtaxa, waarvan die meeste oor in vitro-sellulolitiese aktiwiteit beskik, aan die lig gebring.

Plant-mediated synthesis of metallic nanoparticles is a growing area of interest in the fields of... more Plant-mediated synthesis of metallic nanoparticles is a growing area of interest in the fields of green synthesis and nanotechnology. The present work studied the synthesis of nano-gold particles using Tetradenia riparia flower, leaf and stem extracts derived using methanol and water. The synthesized nanoparticles were characterized using UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive x-ray (EDX) analysis and Fourier transform infrared (FTIR) spectroscopy. UV peaks for nano-gold synthesized from methanol and aqueous extracts were observed at 535 nm and 540 nm, respectively. SEM analysis revealed monodispersed spherical nano-gold particles in the diameter range of 10-35 nm. The presence of elemental gold in the nanoparticles was confirmed by EDX. FTIR analysis indicated the presence of terpenoids and pyrones which were responsible for reducing, capping and stabilizing of the nano-gold particles.

Asian Pacific Journal of Tropical Disease, 2014

Plants constitute the richest source of natural antioxidants to counteract reactive oxygen specie... more Plants constitute the richest source of natural antioxidants to counteract reactive oxygen species (ROS). ROS are continuously generated inside the human body as a result of contacting with excess of exogenous chemicals in our ambient environment and/or due to a number of endogenous metabolic processes involving redox enzymes [1]. ROS are thought to be harmful to human health and to trigger many diseases arteriosclerosis, inflammatory disorders, cancer, coronary disease and diabetes. Hence natural antioxidants due to their radical scavenging ability are considered as possible protection against many chronic diseases as well as lipid peroxidation (LPO) [2,3]. Many medicinal plants are found useful in treating wounds such as Alternanthera sessilis, Morinda citrifolia, Lycopodium serratum, Sesamum indicum, Catharanthus roseus, Cecropia peltata, Euphorbia hirta, Ginkgo biloba, Clerodendrum serratum, Pterocarpus santalinus, Lawsonia alba, Napoleona imperialis, Kaempferia galangal, Radix paeoniae, Prosopis cineraria and Trigonella foenum-graecum. This study explores the wound healing activity of Curculigo orchioides Gaertn. (Hypoxidaceae) (C.

South African Journal of Botany, 2009

South African Journal of Botany, 2010

This study describes a protocol for rapid and efficient in vitro propagation of Lessertia frutesc... more This study describes a protocol for rapid and efficient in vitro propagation of Lessertia frutescens (cancer bush), a medicinally important plant species native to southern Africa. Single node explants were grown in various culture regimes of MS medium containing 30 g/l sucrose supplemented with various concentrations of cytokinins and auxins and solidified with 8 g/l agar.

Parasitology Research, 2013

Growing incidence of drug resistance against leishmaniasis in endemic areas and limited drug opti... more Growing incidence of drug resistance against leishmaniasis in endemic areas and limited drug options necessitates the need for a vaccine. Notwithstanding significant leishmanial research in the past decades, a vaccine candidate is far from reality. In this study, we report the potential of two urinary leishmanial proteins to induce macrophage effector functions, inflammatory cytokines production and human lymphocytes proliferation. A total four proteins of molecular mass 25, 28, 54 and 60 kDa were identified in human urine samples. The 25 and 28 kDa proteins significantly induced NADPH oxidase (p<0.001), superoxide dismutase (p<0.001) and inducible nitric oxide synthase (p<0.001) activities in stimulated RAW264.7 macrophages. The release of nitric oxide, tumor necrosis factoralpha and interleukin (IL)-12 was also significantly (p< 0.001) higher in 25 and 28 kDa activated macrophages as compared with cells activated with other two proteins. These two proteins also induced significant (p<0.001) proliferation and release of IFN-γ and IL-12 in human peripheral blood mononuclear cells. −*), hydrogen peroxide (H 2 O 2) and nitric oxide (NO), in the parsitophorous vacuole of host macrophages, is a primary mechanism for the parasitic elimination (Engwerda et al. 2004). These metabolites are generated by the enzymes like V

Molecular Cytogenetics, 2013

Background: Myelofibrosis occurs as primary myelofibrosis or as a late occurrence in the evolutio... more Background: Myelofibrosis occurs as primary myelofibrosis or as a late occurrence in the evolution of essential thrombocythaemia and polycythaemia vera. It is the rarest of the three classic myeloproliferative neoplasms (MPN). Polyploidy has only rarely been reported in MPN despite the prominent involvement of abnormal megakaryocytes. The use of peripheral blood samples containing increased numbers of haematopoietic progenitors has improved the output from cytogenetic studies in myelofibrosis and together with the use of single nucleotide polymorphism arrays (SNPa) has contributed to an improved knowledge regarding the diverse genetic landscape of this rare disease. Results: Cytogenetic studies performed on a consecutive cohort of 42 patients with primary or post ET/PV myelofibrosis showed an abnormal karyotype in 24 cases and of these, nine showed a polyploid clone. Six of the nine cases showed a tetraploid (4n) subclone, whereas three showed mixed polyploid subclones with both tetraploid and octoploid (4n/8n) cell lines. The abnormal clone evolved from a near diploid karyotype at the initial investigation to a tetraploid karyotype in follow-up cytogenetic analysis in four cases. In total, six of the nine polyploid cases showed gain of 1q material. The remaining three cases showed polyploid metaphases, but with no detectable structural karyotypic rearrangements. Three of the nine cases showed chromosome abnormalities of 6p, either at diagnosis or later acquired. SNPa analysis on eight polyploid cases showed additional changes not previously recognised by karyotype analysis alone, including recurring changes involving 9p, 14q, 17q and 22q. Except for gain of 1q, SNPa findings from the polyploid group compared to eight non-polyploid cases with myelofibrosis found no significant differences in the type of abnormality detected. Conclusions: The study showed the use of peripheral blood samples to be suitable for standard karyotyping evaluation and DNA based studies. The overall profile of abnormalities found were comparable with that of post-MPN acute myeloid leukaemia or secondary myelodysplastic syndrome and cases in the polyploidy group were associated with features of high risk disease. The above represents the first documented series of polyploid karyotypes in myelofibrosis and shows a high representation of gain of 1q.

Journal of Biological Chemistry, 2011

The human bitter taste receptors (T2Rs) are non-Class A members of the G-protein-coupled receptor... more The human bitter taste receptors (T2Rs) are non-Class A members of the G-protein-coupled receptor (GPCR) superfamily, with very limited structural information. Amino acid sequence analysis reveals that most of the important motifs present in the transmembrane helices (TM1-TM7) of the well studied Class A GPCRs are absent in T2Rs, raising fundamental questions regarding the mechanisms of activation and how T2Rs recognize bitter ligands with diverse chemical structures. In this study, the bitter receptor T2R1 was used to systematically investigate the role of 15 transmembrane amino acids in T2Rs, including 13 highly conserved residues, by amino acid replacements guided by molecular modeling. Functional analysis of the mutants by calcium imaging analysis revealed that replacement of Asn-66 2.65 and the highly conserved Asn-24 1.50 resulted in greater than 90% loss of agonist-induced signaling. Our results show that Asn-24 1.50 plays a crucial role in receptor activation by mediating an hydrogen bond network connecting TM1-TM2-TM7, whereas Asn-66 2.65 is essential for binding to the agonist dextromethorphan. The interhelical hydrogen bond between Asn-24 1.50 and Arg-55 2.54 restrains T2R receptor activity because loss of this bond in I27A and R55A mutants results in hyperactive receptor. The conserved amino acids Leu-197 5.50 , Ser-200 5.53 , and Leu-201 5.54 form a putative LXXSL motif which performs predominantly a structural role by stabilizing the helical conformation of TM5 at the cytoplasmic end. This study provides for the first time mechanistic insights into the roles of the conserved transmembrane residues in T2Rs and allows comparison of the activation mechanisms of T2Rs with the Class A GPCRs.

International Microbiology, 2003

Ustilago maydis was specifically detected in infected maize plants by means of the polymerase cha... more Ustilago maydis was specifically detected in infected maize plants by means of the polymerase chain reaction (PCR) using oligonucleotides corresponding to a specific region downstream of the homeodomain of the bE genes of the pathogen. The reaction gave rise to amplification of a ca. 500-bp product when tested with U. maydis DNA, but no amplification was detected with DNA from fungi not related to U. maydis. Using these primers, U. maydis was detected in infected maize plants from differentially susceptible cultivars as early as 4 days after inoculation with strains of variable degrees of virulence. Detection of U. maydis at early stages of infection, or in asymptomatic infected plants should assist in studies on plant-pathogen interactions.

In Vitro Cellular & Developmental Biology - Plant, 2009

The present study reports a simple protocol for indirect shoot organogenesis and plant regenerati... more The present study reports a simple protocol for indirect shoot organogenesis and plant regeneration of Sutherlandia using rachis and stem segments. Different concentrations (0.0-68.08 μmol l −1) of thidiazuron (TDZ) were used for callus induction and shoot organogenesis. The highest percentage of callus formation (97.5%) and the highest percentage of explants forming shoots (88.8%) were obtained from rachis explants cultured onto Murashige and Skoog (MS) medium (Murashige and Skoog, Physiol. Plant. 15:473-495, 1962) supplemented with 45.41 μmol l −1 TDZ. Scanning electron microscopy demonstrated the early development of adventitious shoots derived from callus cultures. Shoot clusters were further developed and grown in MS hormone-free medium. The presence of L-canavanine was determined by thin-layer chromatography and confirmed after column fractionation using silica gel and nuclear magnetic resonance spectroscopy. Individual shoots were rooted on different concentrations and combinations of MS salt strength and IBA. Half-strength MS salt medium supplemented with 24.6 μmol l −1 IBA was optimal for root induction in which 78% of shoots were rooted. The in vitro plants were successfully acclimatized in a growth chamber with a 90% survival rate.

Breast Cancer Research and Treatment, 2011

This two-arm randomized clinical study aimed to evaluate the efficacy and safety of neoadjuvant c... more This two-arm randomized clinical study aimed to evaluate the efficacy and safety of neoadjuvant concurrent chemotherapy and letrozole in postmenopausal women with locally advanced breast carcinoma. One hundred and one postmenopausal women aged 50-83 years with pathologically proven locally advanced (clinical stage T3, T4 and/or N2, N3) breast cancer were randomly assigned to receive neoadjuvant chemotherapy alone (control arm, n = 51) or neoadjuvant chemotherapy concurrent with letrozole 2.5 mg (study arm, n = 50). Chemotherapy consisted of a median 4 (range 3-5) cycles of intravenous 5-fluorouracil 600 mg/m(2), doxorubicin 60 mg/m(2), and cyclophosphamide 600 mg/m(2), every three weeks. All patients subsequently underwent modified radical mastectomy approximately two weeks after the last cycle of chemotherapy. Pathologic complete response rates were 25.5% and 10.2% in the study and the control group, respectively (P = 0.049). Similarly, clinical complete response rates were 27.6% and 10.2% in the study and the control group, respectively (P = 0.037). In the subgroup analysis of hormone receptor-positive cases, the complete response rates were more prominent in study group compared with control group. Common treatment-related side effects such as nausea, vomiting, bone marrow suppression, and mucositis were similar in both groups, but hot flush was more prevalent in study group compared with control group (P = 0.023). The addition of letrozole concurrently with neoadjuvant chemotherapy provides a higher clinical and pathologic response rates with acceptable toxicity compared with chemotherapy alone in postmenopausal women with locally advanced sensitive breast cancer.

International Journal of Molecular Sciences, 2021

Bitter-taste receptors (T2Rs) have emerged as key players in host–pathogen interactions and impor... more Bitter-taste receptors (T2Rs) have emerged as key players in host–pathogen interactions and important modulators of oral innate immunity. Previously, we reported that T2R14 is expressed in gingival epithelial cells (GECs) and interacts with competence stimulating peptides (CSPs) secreted by the cariogenic Streptococcus mutans. The underlying mechanisms of the innate immune responses and physiological effects of T2R14 on Gram-positive bacteria are not well characterized. In this study, we examined the role of T2R14 in internalization and growth inhibitory effects on Gram-positive bacteria, namely Staphylococcus aureus and S. mutans. We utilized CRISPR-Cas9 T2R14 knockdown (KD) GECs as the study model to address these key physiological mechanisms. Our data reveal that the internalization of S. aureus is significantly decreased, while the internalization of S. mutans remains unaffected upon knockdown of T2R14 in GECs. Surprisingly, GECs primed with S. mutans CSP-1 resulted in an inhibi...

Agriculture

This study investigates the incidence of Escherichia coli in cauliflower, bitter gourd and soil p... more This study investigates the incidence of Escherichia coli in cauliflower, bitter gourd and soil profile drip-irrigated with municipal wastewater in a semi-arid peri-urban area in India. There were four treatments: drip irrigation with primarily treated municipal wastewater through inline (non-pressure compensating) surface drip (T1), inline subsurface drip (T2), bioline (pressure compensating) subsurface drip (T3) and bioline surface drip (T4). Results revealed that T1 had the highest concentration of E.coli (35 ± 2.66 and 25 ± 2.26 colony forming unit (CFU) g˗1) and T3 had the lowest concentration of E. coli (29 ± 2.29 and 18.9 ± 2.04 CFU g˗1) for cauliflower and bitter gourd, respectively. In bitter gourd top fruits (1 m above the ground level), the E. coli count was significantly lower (p < 0.05) than in the surface level fruits. There was also a considerable reduction of E. coli counts in bioline drip lateral as compared to the inline drip. A higher concentration of E. coli (...