Computing simple paths among obstacles

AbstractGiven a set X of points in the plane, two distinguished points s,t∈X, and a set Φ of obstacles represented by line segments, we wish to compute a simple polygonal path from s to t that uses only points in X as vertices and avoids the obstacles in Φ. We present two results: (1) we show that finding such simple paths among arbitrary obstacles is NP-complete, and (2) we give a polynomial-time algorithm that computes simple paths when the obstacles form a simple polygon P and X is inside P. Our algorithm runs in time O(m2n2), where m is the number of vertices of P and n is the number of points in X

CHROMATOGRAPHIC AND SPECTROPHOTOMETRIC ANALYSIS OF BIOACTIVE COMPOUNDS FROM CAYRATIA TRIFOLIA (L.) STEM

Objective: The present study was to analyze the bioactive compounds from stem ethanolic extract of Cayratia trifolia by FTIR, HPTLC and GC-MS techniques.Methods: The FTIR was applied and infrared spectrum in mid-infrared region 4000-400 cm-1 was used, HPTLC fingerprinting profiles was done by using Hamilton syringe and CAMAG LINOMAT 5 instrument and GC-MS analysis of stem ethanolic extract of Cayratia trifolia (L.) was performed using the equipment Agilent technologies 7890 A.Results: The FTIR analysis identified the functional groups such as amine, acid, alkane, ketone acyclic, carbonyl, aromatic, ester and alkene. HPTLC fingerprinting profile proves the presence of alkaloids, flavonoids, glycosides, saponin and steroids. GC-MS revealed the presence of various compounds like hexadecanoic acid-ethylester, phytol, tetratetracontane, stigmasterol, nonacosane and octadecane-1-bromo-in stem ethanolic extract of Cayratia trifolia.Conclusion: In conclusion, Cayratia trifolia plant stems ethanolic extract holds more bioactive compounds that may lead to the development of novel drug against various diseases and disorders.Keywords: Cayrtaia trifolia, FTIR Spectroscopy, HPTLC analysis, GC-MS technique, Bioactive compoun

QUANTITATIVE PHYTOCHEMICAL ANALYSIS, IN VITRO ANTIOXIDANT POTENTIAL AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY STUDIES IN ETHANOLIC EXTRACT OF AZOLLA MICROPHYLLA

ABSTRACTObjective: The study was intended to analyze phytochemicals quantitatively, evaluate in vitro antioxidant properties and to determine the bioactivecompounds in the crude extract of Azolla microphylla (AM) available at the local farms of Coimbatore district in Tamil Nadu.Methods: The quantitative phytochemical and in vitro antioxidant analyses were performed using standard procedures. The bioactive compoundswere analyzed using gas chromatography-mass spectrometry (GC-MS) instrument.Results: The quantitative phytochemical analysis of AM revealed the presence of considerable amounts of phenols (90.2±2.85 mg gallic acidequivalents/g), tannins (82.2±5.25 mg tannic acid equivalents/g), flavonoids (58.5±1.87 mg quercetin equivalents/g), saponins (12.1±3.78 mg/g),and alkaloids (2.2±0.55 mg/g) in decreasing order of concentrations. The in vitro antioxidant analyses suggested that the whole plant extract of AMhas prominent antioxidant prospective against various free radicals such as 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azinobis-3-ethylbenzothialozine-6sulphonicacid,nitric oxide,superoxide,and ferricionswhileascorbicacid being thestandardantioxidantused.The GC-MS analysisdisplayedthepresenceof21 bioactivecompounds, eachbelonging tovariouscategoriesofphytochemicalssuchas chalcones, terpenoids,fattyacids,coumarins,andsteroids.Conclusion: The results indicate that AM present in the local farms of Coimbatore is an effective scavenger of free radicals and has the potential to beused as a natural antioxidant which is attributed to the rich presence of secondary metabolites.Keywords: Azolla microphylla, Chalcones, Coumarins, Saponins

EFFECT OF AQUEOUS EXTRACT OF AZOLLA FILICULOIDES IN GASTRIC MUCOSA OF ULCERATED RATS

Objective: To investigate the anti ulcer effect of aqueous extract of Azolla  filiculoides (AF) in experimentally induced gastric ulceration in male Wistar rats.Methods: Twenty four rats were divided into four groups of six rats in each group. The group I and III rats were fed with standard diet, whereas, group II and IV rats were pre-treated orally with aqueous extract of Azolla microphylla (200 mg/kg body) twice a day for 15 d. Twenty four hours before sacrifice, group III and IV rats were induced with ulcer by pylorus-ligation plus oral administration of a single dose of HCl-ethanol mixture (1.5 ml). The gastric juice and mucosal scraps were collected from all the groups for biochemical analyses.Results: In ulcer induced rats, there observed a significant (P<0.05) increase in the following parameters like ulcer index, gastric output, acid output, lipid peroxides and these levels were significantly (P<0.05) reduced to near normal values in AF pre-treated rats. A significant decrease was also observed in the levels of reduced glutathione, hexose, hexosamine, sialic acid and in the activities of antioxidant enzymes (glutathione-S-transferase and glutathione peroxidase) and antiperoxidative enzymes (catalase and superoxide dismutase) in ulcer induced rats. These values were restored back to near normalcy in AF pre-treated rats.Conclusion: The results reinforce the antisecretory, acid neutralizing and the antioxidant potential of the whole plant extract of AF against experimentally induced gastric ulcer in rats. However, further studies are needed to identify the active principle involved in eliciting the antiulcer activity of the plant.Â

Introgression of blast resistance genes into the elite rice variety MR263 through marker-assisted backcrossing

BACKGROUND: Blast caused by the fungus Magnaporthe oryzae is a significant disease threat to rice across the world and is especially prevalent in Malaysia. An elite, early-maturing, high-yielding Malaysian rice variety, MR263, is susceptible to blast and was used as the recurrent parent in this study. To improve MR263 disease resistance, the Pongsu Seribu 1 rice variety was used as donor of the blast resistance Pi-7(t), Pi-d(t)1 and Pir2-3(t) genes and qLN2 quantitative trait locus (QTL). The objective was to introgress these blast resistance genes into the background of MR263 using marker-assisted backcrossing with both foreground and background selection. RESULTS: Improved MR263-BR-3-2, MR263-BR-4-3, MR263-BR-13-1 and MR263-BR-26-4 lines carrying the Pi-7(t), Pi-d(t)1 and Pir2-3(t) genes and qLN2 QTL were developed using the simple sequence repeat (SSR) markers RM5961 and RM263 (linked to the blast resistance genes and QTL) for foreground selection and a collection of 65 polymorphic SSR markers for background selection in backcrossed and selfed generations. A background analysis revealed that the highest rate of recurrent parent genome recovery was 96.1% in MR263-BR-4-3 and 94.3% in MR263-BR-3-2. CONCLUSION: The addition of blast resistance genes can be used to improve several Malaysian rice varieties to combat this major disease

Marker‐assisted introgression of broad‐spectrum blast resistance genes into the cultivated MR219 rice variety

BACKGROUND: The rice cultivar MR219 is famous for its better yield and long and fine grain quality; however, it is susceptible to blast disease. The main objective of this study was to introgress blast resistance genes into MR219 through marker‐assisted selection (MAS). The rice cultivar MR219 was used as the recurrent parent, and Pongsu Seribu 1 was used as the donor. RESULTS: Marker‐assisted foreground selection was performed using RM6836 and RM8225 to identify plants possessing blast resistance genes. Seventy microsatellite markers were used to estimate recurrent parent genome (RPG) recovery. Our analysis led to the development of 13 improved blast resistant lines with Piz, Pi2 and Pi9 broad‐spectrum blast resistance genes and an MR219 genetic background. The RPG recovery of the selected improved lines was up to 97.70% with an average value of 95.98%. Selected improved lines showed a resistance response against the most virulent blast pathogen pathotype, P7.2. The selected improved lines did not express any negative effect on agronomic traits in comparison with MR219. CONCLUSION: The research findings of this study will be a conducive approach for the application of different molecular techniques that may result in accelerating the development of new disease‐resistant rice varieties, which in turn will match rising demand and food security worldwide

Prawn, fish and molluscan seed resources along the Kerala and Tamilnadu coasts

The study detailed about the occurrence and quantitative abundance of prawn, fish and molluscan seed resources, their spatial, seasonal and diurnal variations, abundance in relation to lunar periodicities, influence of environmental features and pollution on them and areas suitable for brackishwater culture along the Kerala and Tamilnadu coasts

Efficacy of Major Plant Extracts/Molecules on Field Insect Pests

Insect pests are considered the major hurdle in enhancing the production and productivity of any farming system. The use of conventional synthetic pesticides has led to the emergence of pesticide-resistant insects, environmental pollution, and negative effects on natural enemies, which have caused an ecological imbalance of the predator-prey ratio and human health hazards; therefore, eco-friendly alternative strategies are required. The plant kingdom, a rich repertoire of secondary metabolites, can be tapped as an alternative for insect pest management strategies. A number of plants have been documented to have insecticidal properties against various orders of insects in vitro by acting as antifeedants, repellents, sterilant and oviposition deterrents, etc. However, only a few plant compounds are applicable at the field level or presently commercialised. Here, we have provided an overview of the broad-spectrum insecticidal activity of plant compounds from neem, Annona, Pongamia, and Jatropha. Additionally, the impact of medicinal plants, herbs, spices, and essential oils has been reviewed briefl

From Mendel’s discovery on pea to today’s plant genetics and breeding

In 2015, we celebrated the 150th anniversary of the presentation of the seminal work of Gregor Johann Mendel. While Darwin’s theory of evolution was based on differential survival and differential reproductive success, Mendel’s theory of heredity relies on equality and stability throughout all stages of the life cycle. Darwin’s concepts were continuous variation and “soft” heredity; Mendel espoused discontinuous variation and “hard” heredity. Thus, the combination of Mendelian genetics with Darwin’s theory of natural selection was the process that resulted in the modern synthesis of evolutionary biology. Although biology, genetics, and genomics have been revolutionized in recent years, modern genetics will forever rely on simple principles founded on pea breeding using seven single gene characters. Purposeful use of mutants to study gene function is one of the essential tools of modern genetics. Today, over 100 plant species genomes have been sequenced. Mapping populations and their use in segregation of molecular markers and marker–trait association to map and isolate genes, were developed on the basis of Mendel's work. Genome-wide or genomic selection is a recent approach for the development of improved breeding lines. The analysis of complex traits has been enhanced by high-throughput phenotyping and developments in statistical and modeling methods for the analysis of phenotypic data. Introgression of novel alleles from landraces and wild relatives widens genetic diversity and improves traits; transgenic methodologies allow for the introduction of novel genes from diverse sources, and gene editing approaches offer possibilities to manipulate gene in a precise manner