39 research outputs found

    In vitro Culture of Several Rice Cultivars

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    Tissue culture methods have been established to regenerate certain rice (Oryza sativa L) cultivars, but regeneration of the rice cultivars widely grown in Arkansas has not been reported. This study has established an in vitroculture for the rice cultivars \u27Nortai\u27, \u27Starbonnet\u27, \u27Mars\u27, Tebonnet\u27, \u27Newbonnet\u27, and \u27Lemont\u27. Callus was induced in the dark at either 20 or 28 C from dehusked seeds cultured on Murashige and Skoog (MS) medium (Murashige and Skoog, 1962) containing 40 g L^-1 sucrose, 10 g L^1 agar, 0.5, 1.0, or 2.0 mg L^-1 1 2,4-dichlorophenoxyacetic acid (2,4-D) and adjusted to pH 5.7. After four weeks the calli were weighed, transferred onto MS medium containing no 2,4-D, and maintained in a 1 2-h photoperiod (65 uE m^-2 s^-1) at 25 ± 2 C to induce plant regeneration. Callus production was best when cultured on a medium containing 1.0 mg L^-1 2,4-D and incubated at 28 C. Plant regeneration was observed two to four weeks later. The percentage of calli regenerating platlets varied with the cultivar and the callus induction treatment. Callus induction at 20 C on a medium with a 2,4-D level less than 2.0 mg L^-1 enhanced the regenerability of most cultivars. Regenerates were transplanted to soil and grow normally to maturity. This system can be helpful in improving rice cultivars with tissue culture techniques such as somaclonal variant selection and somatic hybridization

    Potential of Iranian wild barley (Hordeum vulgare ssp. spontaneum) in breeding for drought tolerance

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    The vast genetic resources of wild barley (Hordeum vulgare ssp. spontaneum, hereafter WB) may hold unique assets for improving barley (H. vulgare ssp. vulgare) cultivars for drought stress. To evaluate genetic potential and characterization of variation among a diverse collection of barley and WB genotypes, mostly originated from Iran, a field experiment was performed under three moisture environments (control, mild and intense drought stress) during two years (2012–2014). Considerable variation was observed among the wild and cultivated genotypes for drought tolerance and agronomic traits. Principal component analysis (PCA) grouped genotypes studied into three groups (WB, two-row barley and sixrow barley groups). However, Iranian and foreign WB genotypes were not completely separated, showing a high variation within both gene pools. The high significance of genotype by environment interaction, confirms importance of using accurate target environments for drought stress breeding. A number of WB genotypes with the highest values of the number of tillers, number of seed per spike, seed weight, grain yield and yield stability index under stressed environments were identified as superior genotypes. Most of these genotypes originate from Iran, highlighting the importance of this germplasm in barley breeding

    Golpayegan metamorphic complex (Sanandaj–Sirjan Zone, Iran) as evidence for Cadomian back-arc magmatism: structure, geochemistry and isotopic data

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    The Golpayegan metamorphic complex is located in the Sanandaj-Sirjan Zone, Iran. This complex consists of various metamorphic rocks including schists, marbles, slates, gneisses, and amphibolites, most of them have Neoproterozoic age. The presence of structures such as sigma fabrics, boudinage, folded boudinage and interfering fold patterns indicates the occurrence of more than two deformation phases in the Golpayegan metamorphic complex. The measurement of strain intensity in the folds indicated deep immersion of structures and old Precambrian settings that had been influenced by orogenic events in the Neoproterozoic. These deformed rocks were exposed during extensional movements and, subsequently, sheared. The results based on field works shown geochemical relations and initial εNd(600 Ma) values of amphibolites in three sampling points located in Golpayegan region manifested that the protolith of the first (a') and second (b') sampling points had mantle origin (ortho-amphibolite), whilst protolith of the third (c') sampling point had sedimentary origin (para-amphibolite). Geochemically, the Golpayegan ortho-amphibolites showed subalkaline basalt-basaltic andesite compositions of tholeiitic affinity. The negative anomalies of Nb and Ti relative to Pb, La, and Ce in the primitive mantle-normalized spider-diagram and εNd(600 Ma) values revealed the subduction environment for ortho-amphibolites. The ortho-amphibolites exhibited the intermediate chemistry between the normal mid-ocean ridge basalt and island-arc tholeiitic basalt. Enrichment in large ion lithophile elements (LILE), light rare earth elements (LREE), and relative depletion in high field strength elements (HFSE) suggest the back-arc basin setting for the Golpayegan ortho-amphibolites. The primitive magma of the ortho-amphibolites was produced by 8–20% melting of spinel lherzolite. According to the Neoproterozoic age of the Golpayegan ortho-amphibolites and their relationship with the Golpayegan granitic gneiss (596‒578 Ma), it shows that they can be related to the Cadomian back-arc basin in the north of Peri-Gondwana at the Neoproterozoic. The high values of 87Sr/86Sr (0.708450‒0.714986) interpreted as result of seawater hydrothermal alteration.publishe

    Social Alignment Contagion in Online Social Networks

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    Researchers have already observed social contagion effects in both in-person and online interactions. However, such studies have primarily focused on users’ beliefs, mental states, and interests. In this article, we expand the state of the art by exploring the impact of social contagion on social alignment, i.e., whether the decision to socially align oneself with the general opinion of the users on the social network is contagious to one’s connections on the network or not. The novelty of our work in this article includes: 1) unlike earlier work, this article is among the first to explore the contagiousness of the concept of social alignment on social networks; 2) our work adopts an instrumental variable approach to determine reliable causal relations between observed social contagion effects on the social network; and 3) our work expands beyond the mere presence of contagion in social alignment and also explores the role of population heterogeneity on social alignment contagion. Based on the systematic collection and analysis of data from two large social network platforms, namely, Twitter and Foursquare, we find that a user’s decision to socially align or distance from social topics and sentiments influences the social alignment decisions of their connections on the social network. We further find that such social alignment decisions are significantly impacted by population heterogeneity

    Sustainable Agriculture Reviews

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     The Epichloë fungal endophytes that inhabit grasses have potentially large-scale consequences for macro- and micro-organisms and food chains in agriculture. Over 40 years of study on the benefits of symbiotic Epichloë fungal endophytes for host grasses, investigations have focused on the major agricultural species, tall fescue and perennial ryegrass. However, many other grass species remain to be evaluated for the effects of Epichloë endophytes. Animal toxicity due to accumulation of nitrogenous compounds, e.g. endophyte-dervived alkaloids, particularly in areas and periods under abiotic stress, still prevent widespread application of endophyte-infected grasses in agroecosystems. Here we review Epichloë endophyte-ecosystem relationships. The major points are: (1) Epichloë endophytes protect their host plants from vertebrate and invertebrate herbivory and allow plants to persist under water shortage, salinity, low light, mineral deficiencies and metal toxicity. Data suggests that the concentration of endophyte-derived anti-herbviore compounds increases with rising temperatures. This trend thus suggests that the strength of mutualistic interactions may increase in future climates with possible consequences for animal toxicity. (2) The benefits of endophyte infection for the host grass are context-dependent, varying with  environmental conditions, grass species and cultivar, and are also highly influenced by interactions between both host and endophyte genetic combinations. (3) The benefits of fungal endophytes extend to neighboring grass species with respect to their protection from diseases and herbivores. (4) Novel grass-endophyte associations that produce alkaloids reducing herbivory insects, but do not produce alkaloids that are toxic to grazing vertebrates have been found. Such associations are therefore useful to control plant pests and diseases.</p

    Levels and variables associated with psychological distress during confinement due to the coronavirus pandemic in a community sample of Spanish adults

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    Due to the COVID-19 pandemic's consequences and the state of alarm, literature has shown that people worldwide have experienced severe stressors that have been associated with increased prevalence of emotional distress. In this study, we explored psychological distress (depression, anxiety, and somatization symptoms) using an online survey platform in a sample of 1,781 Spanish adults during the confinement due to COVID-19, relationships between distress and sleep problems, affect, pain, sleep, emotional regulation, gender, type of housing, history of psychopathology, and living alone during the confinement, and differences depending on demographic and psychological variables. Results showed that between 25% and 39% of the sample referred to clinically significant levels of distress. In addition, women showed higher levels of distress, negative affect, perception of pain, and cognitive reappraisal and lower levels of emotional suppression and sleep quality than men. A history of psychopathology, being younger, living alone or in a flat was associated with higher distress. Finally, the variables most strongly related to distress were negative and positive affect, levels of pain, sleep quality, and emotional suppression. Our results highlight the important role of emotional suppression, cognitive reappraisal, and loneliness and the impact of being a woman and younger in Spain during the COVID-19 pandemic. Therefore, it would be necessary to provide assessments of distress levels in these population groups and focus psychological preventive and therapeutic online interventions on expressing emotions and preventing loneliness

    Genome-wide efficient attribute selection for purely epistatic models via Shannon entropy

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    Epistasis plays an important role in the genetic architecture of common human diseases. Most complex diseases are believed to have multiple contributing loci that often have subtle patterns which make them fairly difficult to find in large data sets. Disorders that follow purely epistatic models cannot be detected by cases/control studies based on individual analysis of susceptible loci. The computational complexity of performing exhaustive searches for detecting such models in genome-wide applications is practically unfeasible. Furthermore, with ever-increasing number of both genotypes and individuals on one side, and little knowledge of complex traits on the other, it is becoming fairly difficult and time consuming to perform systematic genome-wide studies on such traits. We present and discuss a convenient framework for modelling epistasis using information theoretic concepts and algorithms inspired by such an approach. These generalised algorithms, which are especially in favour of purely epistatic models, are applied to both simulated and real data. The real data represents the genotype-phenotype values for Age-Related Macular Degeneration (AMD) disease. Many two-locus purely epistatic patterns were found for AMD. A new visualisation approach is also presented for the purpose of better illustrating epistasy for cases where the number of loci is more than two or three

    Assessment of Yield and Drought Tolerance in Iranian Sainfoin Cultivars

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    This research was conducted to evaluate 30 sainfoin cultivars in terms of yield, agronomic and morphological traits under water stress condition, using different drought tolerannce indices. A randomized complete block design with three replications was employed during two years at Isfahan University of Technology Research Farm, Isfahan, Iran. Effect of cultivars were significant for all of the measured traits at p<0.01. Also, the interactions of cultivars by moisture environment were significant for number of days to 50% flowering; inflorescence length, fresh and dry matter yield and leaf to stem ratio, indicating that different genotypes had different responses to moisture environments. Among different drought tolerance and susceptibility indices STI, GMP and MP had high correlation coefficients with yield under stress and non stress conditions, indicating that these indices are more suitable as criterion for selection of drought-tolerant cultivars. According to the studied indices and principle component analysis, cultivars 16 (Bardsir), 21 (Fereydunshahr 2), 23 (Najafabad 2) and 27 (Borujerd) were found to be the most desirable ones and can be considered as drought tolerant genotypes for future studies

    Effect of conventional cooking methods on lipid oxidation indices in lamb meat

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    Lipid oxidation is one of the most deteriorative reactions occurred in foodstuff which has harmful impacts on the both food quality and consumer's health. This study was designed to speculate the influence of three conventional cooking methods including boiling, frying and grilling on lipid oxidation parameters in cooked lamb meat. Sections of lamb meat from longissimus dorsi muscle, taken from native Lori-Bakhtiary sheep species were cut into uniform pieces and cooked using boiling, frying and roasting methods according to the cooking routine and tradition in Iranian society, in terms of temperature and time. Proximate compositions (moisture, lipid, ash and protein) in the raw and cooked meat were determined using the standard methods of analysis. Moreover, weight loss was measured after each treatment. Lipid oxidation parameters such as peroxide value, conjugated diene and TBARS indices were measured in the raw and cooked samples. Evaluation of lipid oxidation parameters showed that peroxide value was significantly decreased in all cooked samples. In contrast, conjugated diene value was significantly increased in the fried and grilled samples (
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