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Nitrogen (N) is a macronutrient limiting crop productivity with varied requirements across species and genotypes. Understanding the mechanistic basis of N responsiveness by comparing contrasting genotypes could inform the development and selection of varieties with lower N demands, or inform agronomic practices to sustain yields with lower N inputs. Given the established role of millets in ensuring climate-resilient food and nutrition security, we investigated the physiological and genetic basis of nitrogen responsiveness in foxtail millet (Setaria italica L.). We had previously identified genotypic variants linked to N responsiveness, and here, we dissect the mechanistic basis of the trait by examining the physiological and molecular behaviour of N responsive (NRp-SI58) and non-responsive (NNRp-SI114) accessions at high and low N. Under high N, NRp-SI58 allocates significantly more biomass to nodes, internodes and roots, more N to developing grains, and is more effective at remobilising flag leaf N compared to NNRp-SI114. Post anthesis flag leaf gene expression suggests that differences in N induce much higher transcript abundance in NNRp-SI114 than NRp-SI58, a large proportion of which are potentially regulated by APETALA2 (AP2) transcription factors. Overall, the study provides novel insights into the regulation and manipulation of N responsiveness in S. italica.
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This paper is concerned to a mathematical model for the management of hospital beds when a new infection emerges in the population with the existing infections. The study of this joint dynamics presents formidable mathematical challenges due to a limited number of hospital beds. We have derived the invasion reproduction number, which investigates the potential of a newly emerged infectious disease to persist when some infectious diseases are already invaded the host population. We have shown that the proposed system exhibits transcritical, saddle-node, Hopf, and Bogdanov-Takens bifurcations under certain conditions. We have also shown that the total number of infected individuals may increase if the fraction of the total number of hospital beds is not properly allotted to the existing and a newly emerged infectious disease. The analytically obtained results are verified with the help of numerical simulations.
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Doenças Transmissíveis , Modelos Biológicos , Humanos , Modelos Teóricos , Doenças Transmissíveis/epidemiologia , HospitaisRESUMO
KEY MESSAGE: Small RNAs have emerged as key players of gene expression regulation. Several lines of evidences highlight their role in modulating high temperature stress responsiveness in plants. Throughout their life cycle, plants have to regulate their gene expression at various developmental phases, physiological changes, and in response to biotic or environmental stress. High temperature is one the most common abiotic stress for crop plants, that results in impaired morphology, physiology, and yield. However, plants have certain mechanisms that enable them to withstand such conditions by modulating the expression of stress-related genes. Small RNA (sRNA)-regulated gene expression is one such mechanism which is ubiquitous in all eukaryotes. The sRNAs mainly include micro RNAs (miRNAs) and small interfering RNAs (siRNAs). They are primarily associated with the gene silencing either through translation inhibition, mRNA degradation, or DNA methylation. During high temperature stress the increased or decreased level of miRNAs altered the protein accumulation of target transcripts and, therefore, regulate stress responses. Several reports are available in plants which are genetically engineered through expressing artificial miRNAs resulted in thermotolerance. sRNAs have also been reported to bring the epigenetic changes on chromatin region through RNA-dependent DNA methylation (RdDM). The present article draws a brief illustration of sRNA origin, their functional mechanisms, role in high temperature stress, and possible application for developing stress tolerant crop plants.
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MicroRNAs , Plantas , Regulação da Expressão Gênica de Plantas/genética , MicroRNAs/genética , MicroRNAs/metabolismo , Plantas/genética , RNA de Cadeia Dupla , RNA de Plantas/genética , RNA de Plantas/metabolismo , RNA Interferente Pequeno/genética , Estresse Fisiológico/genética , TemperaturaRESUMO
To explore the impact of available and temporarily arranged hospital beds on the prevention and control of an infectious disease, an epidemic model is proposed and investigated. The stability analysis of the associated equilibria is carried out, and a threshold quantity basic reproduction number ( R0) that governs the disease dynamics is derived and observed whether it depends both on available and temporarily arranged hospital beds. We have used the center manifold theory to derive the normal form and have shown that the proposed model undergoes different types of bifurcations including transcritical (backward and forward), Bogdanov-Takens, and Hopf-bifurcation. Bautin bifurcation is obtained at which the first Lyapunov coefficient vanishes. We have taken advantage of Sotomayor's theorem to establish the saddle-node bifurcation. Numerical simulations are performed to support the theoretical findings.
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Doenças Transmissíveis , Epidemias , Número Básico de Reprodução , Doenças Transmissíveis/epidemiologia , Simulação por Computador , Hospitais , Humanos , Modelos BiológicosRESUMO
The unprecedented scale and rapidity of dissemination of re-emerging and emerging infectious diseases impose new challenges for regulators and health authorities. To curb the dispersal of such diseases, proper management of healthcare facilities and vaccines are core drivers. In the present work, we assess the unified impact of healthcare facilities and vaccination on the control of an infectious disease by formulating a mathematical model. To formulate the model for any region, we consider four classes of human population; namely, susceptible, infected, hospitalized, and vaccinated. It is assumed that the increment in number of beds in hospitals is continuously made in proportion to the number of infected individuals. To ensure the occurrence of transcritical, saddle-node and Hopf bifurcations, the conditions are derived. The normal form is obtained to show the existence of Bogdanov-Takens bifurcation. To validate the analytically obtained results, we have conducted some numerical simulations. These results will be useful to public health authorities for planning appropriate health care resources and vaccination programs to diminish prevalence of infectious diseases.
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Doenças Transmissíveis , Modelos Biológicos , Humanos , Doenças Transmissíveis/epidemiologia , Modelos Teóricos , Vacinação , HospitaisRESUMO
Different environmental cues lead to changes in physiology, biochemistry and molecular status of plant's growth. Till date, various genes have been accounted for their role in regulating plant development and response to abiotic stress. Excluding genes that code for a functional protein in a cell, a large chunk of the eukaryotic transcriptome consists of non-coding RNAs (ncRNAs) which lack protein coding capacity but are still functional. Recent advancements in Next Generation Sequencing (NGS) technology have led to the unearthing of different types of small and large non-coding RNAs in plants. Non-coding RNAs are broadly categorised into housekeeping ncRNAs and regulatory ncRNAs which work at transcriptional, post-transcriptional and epigenetic levels. Diverse ncRNAs play different regulatory roles in nearly all biological processes including growth, development and response to changing environments. This response can be perceived and counteracted by plants using diverse evolutionarily conserved ncRNAs like miRNAs, siRNAs and lncRNAs to participate in complex molecular regimes by activating gene-ncRNA-mRNA regulatory modules to perform the downstream function. Here, we review the current understanding with a focus on recent advancements in the functional studies of the regulatory ncRNAs at the nexus of abiotic stresses and development. Also, the potential roles of ncRNAs in imparting abiotic stress tolerance and yield improvement in crop plants are also discussed with their future prospects.
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MicroRNAs , RNA Longo não Codificante , Regulação da Expressão Gênica de Plantas , RNA não Traduzido/genética , RNA não Traduzido/metabolismo , Estresse Fisiológico/genética , RNA Longo não Codificante/genética , Plantas/genética , Plantas/metabolismo , MicroRNAs/genéticaRESUMO
Marketers and entrepreneurs need to keep up with the fast-paced changes that are happening in the business environment, or they might face the risk of becoming obsolete in the rapidly changing business environment. It is long gone the days when a conventional business model used to help grow fast and get success. With the emergence of social media, the role of consumer-to-consumer communication about the new products and the firms that produce them has been highly magnified in the marketplace. Social media advertisements are promising tools that affect the adoption of a new product. In this paper, a non-linear mathematical model is introduced for this study. To perceive the impact of social media advertisements on the adoption of a new product, we have considered three dynamic variables; namely, (i) non-adopting population, (ii) adopting population, and (iii) social media advertisements. The stability theory of differential equations has been used to study the model analytically. The computer generated figures are drawn in support of derived analytical results for a particular set of parameter values.â¢We have proposed and analyzed an nonlinear mathematical model to study the impact of social media advertisements on adoption of new product.â¢We have considered three dynamical variables; namely, non-adopting population, adopting population, and social media advertisements.â¢The stability theory of differential equations has been used to study the model analytically.
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One of the key factors to control the spread of any infectious disease is the health care facilities, especially the number of hospital beds. To assess the impact of number of hospital beds and control of an emerged infectious disease, we have formulated a mathematical model by considering population (susceptible, infected, hospitalized) and newly created hospital beds as dynamic variables. In formulating the model, we have assumed that the number of hospital beds increases proportionally to the number of infected individuals. It is shown that on a slight change in parameter values, the model enters to different kinds of bifurcations, e.g., saddle-node, transcritical (backward and forward), and Hopf bifurcation. Also, the explicit conditions for these bifurcations are obtained. We have also shown the occurrence of Bogdanov-Takens (BT) bifurcation using the Normal form. To set up a new hospital bed takes time, and so we have also analyzed our proposed model by incorporating time delay in the increment of newly created hospital beds. It is observed that the incorporation of time delay destabilizes the system, and multiple stability switches arise through Hopf-bifurcation. To validate the results of the analytical analysis, we have carried out some numerical simulations.
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Doenças Transmissíveis , Doenças Transmissíveis/epidemiologia , Suscetibilidade a Doenças , Hospitais , Humanos , Modelos TeóricosRESUMO
INTRODUCTION: N responsiveness is the capacity to perceive and induce morpho-physiological adaptation to external and internal Nitrogen (N). Crop productivity is propelled by N fertilizer and requires the breeding/selection of cultivars with intrinsically high N responsiveness. This trait has many advantages in being more meaningful in commercial/environmental context, facilitating in-season N management and not being inversely correlated with N availability over processes regulating NUE. Current lack of its understanding at the physio-genetic basis is an impediment to select for cultivars with a predictably high N response. OBJECTIVES: To dissect physio-genetic basis of N responsiveness in 142 diverse population of foxtail millet, Setaria italica (L.) by employing contrasting N fertilizer nutrition regimes. METHODS: We phenotyped S. italica accessions for major yield related traits under low (N10, N25) and optimal (N100) growth conditions and genotyped them to subsequently perform a genome-wide association study to identify genetic loci associated with nitrogen responsiveness trait. Groups of accessions showing contrasting trait performance and allelic forms of specific linked genetic loci (showing haplotypes) were further accessed for N dependent transcript abundances of their proximal genes. RESULTS: Our study show that N dependent yield rise in S. italica is driven by grain number whose responsiveness to N availability is genetically underlined. We identify 22 unique SNP loci strongly associated with this trait out of which six exhibit haplotypes and consistent allelic variation between lines with contrasting N dependent grain number response and panicle architectures. Furthermore, differential transcript abundances of specific genes proximally linked to these SNPs in same lines is indicative of their N dependence in a genotype specific manner. CONCLUSION: The study demonstrates the value/ potential of N responsiveness as a selection trait and identifies key genetic components underlying the trait in S. italica. This has major implications for improving crop N sustainability and food security.
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Setaria (Planta) , Setaria (Planta)/genética , Estudo de Associação Genômica Ampla , Nitrogênio , Fertilizantes , Melhoramento Vegetal , Locos de Características Quantitativas , Grão Comestível/genéticaRESUMO
Green revolution has boosted crop yields by the development of varieties which rely on high fertilizer application. Since then, higher productivity has largely witnessed excessive nitrogen (N) fertilizer application resulting in many environmentally and agronomically unsustainable consequences. One possible solution to this problem is to develop varieties with efficient N use endowed with genetically superior N metabolizing machinery, thereby significantly reducing N loss in soil and facilitating gainful yield performance at lower N conditions. Nitrate (NO3-) is the major form of N acquired by plants in aerobic soils. Hence, its efficient acquisition, transport, assimilation into complex organic compounds, and overall homeostasis is crucial to ensure productivity under optimal and suboptimal N conditions. Transcription factors are prime regulators of these processes, and insights into their mechanism of action and the resultant effect on N metabolism are crucial to generating crops with efficient and durable nitrogen use efficiency. The present review, therefore, presents a comprehensive updated account of major N responsive transcription factor families, their cross-talk with other growth factors, and explores existing and potential areas of their biotechnological application to maximize crop yields.