Добірка наукової літератури з теми "Fixable components"

Combining ability for grain yield, panicle length, panicle weight and number of grains was estimated through a full diallel analysis involving 6 parents of sorghum viz. Co.18, 148, Co.23, Co,22, CSV.3 and AS.3880 under four environments. The variances due to GCA and SCA were significant, the former being predominant. The operation of both additive and non-additive gene actions in the inheritance of the four characters studied was inferred. Among the parents P3 (Co.23) exhibited high positive and significant gea effects with high per se performance. The hybrid P4 X P5, F1 X P3 and P2 X P3 showed high positive significant sea effects for grain yield. The hybrids involving P3 as one of the parents were generally better in per se performance and sea effects for economic traits observed. Considering the gene actions (fixable and non-fixable) involved, a recurrent selection programme for the improvement of grain yield and its components is suggested.

Parental, F1, F2, BC1, BC2, BC11, BC12, BC21, BC22, BC1 self-pollinated and BC2 self-pollinated generations of three crosses involving six cultivars of durum wheat (Triticum turgidum var. durum) were studied for flag leaf length under normal and late sown environments to analyse the nature of gene effects. For most crosses the 10-parameter model was the best descriptor of the data to account for the variability in generation means of this trait but in cross HI 8062×JNK-4W-128 the 6-parameter model was the best (normal sown) while in cross Raj 911×DWL 5002 the 3-parameter model was the best (late sown). Of the epistatic interactions, dominance×dominance (l) and dominance×dominance×dominance (z) played significantly greater roles in controlling the inheritance of this trait. Absolute totals of non-fixable gene effects were much higher than the fixable gene effects in all the crosses in both the environments, indicating the greater roles of non-additive effects in controlling the inheritance of flag leaf length in durum wheat cultivars. Significant partial dominance was observed frequently in most of the crosses. Significant heterosis was attributed to combined effects of dominance×dominance (l), additive×additive×dominance (x) and dominance×dominance×dominance (z) epistatic interactions in the cross Cocorit 71×A-9-30-1 under late sown environment. Biparental mating and/or diallel selective mating, which exploit both fixable and non-fixable components, have been suggested for the improvement of this trait in durum wheat cultivars.

Generation mean analysis of cross NB-5x58/1 and its reciprocal cross was carried out to understand the nature of gene action in opium poppy. The significance of A, B, C and D scaling tests indicated presence of non-allelic interaction in the inheritance of traits except capsule size and husk yield/plant for reciprocal cross. Additive as well as dominance components of gene action were found in both the crosses. Most of the traits had greater non fixable dominance ?h? and dominance x dominance effects ?l? than fixable additive (d) and additive x additive effects (i) except leaves/plant, branches/plant, capsules/plant, stem diameter, capsule weight/plant, husk yield/plant, opium yield/plant, codeine and narcotine content which showed greater importance of additive (d) and additive x additive effects (i) effects. Inter-mating of the best parents, diallel selective mating or biparental mating in early segregating generations followed by recurrent selections were suggested for genetic improvement of opium poppy.

<p class="042abstractstekst">Plant height, straw mass and flag leaf area are recognized by physiologists as morphological markers of drought stress tolerance. Developing varieties intended for arid and semi-arid zones need to select for these traits. Understanding the genetic control of a given trait helps breeder to handle the segregating populations under study in a more efficient and consistent manner by choosing the best breeding method available to realize significant genetic advance. For this purpose, six generations: parents, F1, F2, BC1, BC2, derived from MBB x ‘Gaviota’ durum wheat (<em>Triticum durum </em>Desf.) cross were grown to investigate the nature of gene action involved in the inheritance pattern of the three traits. The results indicated that the six-parameter model fitted the best the data related to the variability present in the generation means of the studied traits. Generation mean analysis indicated that non-allelic interactions were important factors controlling the expression of these characters with complementary type of gene action governing FLA and STW inheritance. High heritability estimates, moderate to high expected responses to selection, significant genetic correlations with grain yield and greater role of non-additive effects in controlling the inheritance of the three studied traits suggested that breeding methods exploiting both fixable and non-fixable components be applied to break unfavorable linkage and to accumulate useful genes in the base population, followed by mono-trait or index based selection in late advanced generations.</p>

Genetic parameters such as leaf relative water content, leaf chlorophyll content, plant height, above-ground biomass, harvest index, grain yield, and grain yield components of Bousselam/Mrb5 durum wheat (Triticum durum Desf.) cross were estimated based on generation means analysis. A, B, C, and D scaling and Chi-square (χ2) tests revealed the inadequacy of the simple additive-dominance model. This result suggests the presence of digenic epistasis for most studied traits; the duplicate epistasis was present for relative water content, above-ground biomass, and grain yield; and complementary epistasis was observed for chlorophyll content. Significant genotypic correlation coefficients appeared among grain yield, relative water content, and above-ground biomass. This suggests useful indirect selection criteria to improve simultaneously these traits, which showed significant heritability. It can be concluded that the traits investigated show a complex genetic behavior, which implies that early selection would be less efficient; therefore, it is recommended delaying the selection to advanced generations to benefit from the reduction of non-fixable genetic variation and exploit transgressive segregators due to the significant interaction additivity×additivity (i) of the gene and duplicated epistasis.

Emmer wheat (Triticum turgidum ssp. dicoccum) is an important gene source for wheat improvement but less studied in crosses with its descendant species durum (Triticum turgidum ssp. durum), especially in respect to the type of genetic components, intergenic interactions and the genetic mechanisms governing responses to drought. In this study, generation means analysis was performed using F1, F2, BC1P1 and BC1P2 from two different crosses of emmer×durum. Seeds were planted in a RCBD design with three replications under two water regimes. Results showed that there was a highly considerable difference between generations for all studied traits. The presence of significant mean parameter for all the traits, indicated the quantitative inheritance of the traits. Estimating the number of effective genes, polygenic control of the traits were confirmed. In moisture stress condition, epistatic effect for grain yield and yield-related traits illustrated the importance of epistasis in plant adaptation and performance stability. The additive×additive effect, which is fixable, was remarkable in both crosses. Under both water regimes, narrow-sense heritability was relatively high and estimates of gain from selection were positive for most of the traits. Among generations studied, the backcrosses were superior for drought tolerant indices. Based on the results, emmer wheat seems to have genetic potential for durum improvement.

The knowledge of genetic variability among the genotypes for yield and quality attributes is the utmost requirement for any crop improvement work. The eighteen Annona genotypes of two species were studied for five leaves and fruit morphological attributes and twenty-nine components related to growth, yield and fruit quality. The experiment was arranged in a randomized block design in two replicates. A vast variability among the genotypes was revealed as seen based on the significant difference from ANOVA for all the quantitative traits. For morphological traits, genotypes showed variations for leaf shape, base and apex also for fruit shape and segmentation. The high magnitude of heritability and genetic advance as per cent mean was noted for most of the traits indicated presence of fixable genes and least influence of environment for inheritance. The results of the association analysis presented significant and positive association of fruit yield with growth and fruit morphology and fruit quality attributes at both genotypic and phenotypic levels. A strong influence of fruit traits and fruit quality related traits on yield observed owing to their positive and significant direct effects. The pulp/seed ratio, fruit weight, fruit per plant, total soluble solids, sugar content could be emphasize to discriminate the various Annona genotypes so as to utilize them for future hybridization programme to generate desirable genotypes for yield and quality.

Jasione montana L. (Campanulaceae) is used in traditional Belarusian herbal medicine for sleep disorders in children, but the chemical composition and biological activity have not been investigated. In this study, the activities of J. montana extracts, their fractions and main compounds were evaluated in amelanotic melanoma C32 (CRL-1585) cells and normal fibroblasts (PCS-201-012). The extracts and fractions were analyzed using liquid chromatography–photodiode array detection–electrospray ionization–mass spectrometry (LC–PDA–ESI–MS/TOF) to characterize 25 compounds. Further, three major and known constituents, luteolin (22) and its derivatives such as 7-O-glucoside (12) and 7-O-sambubioside (9) were isolated and identified. The cytotoxic activities against fibroblasts and the amelanotic melanoma cell line were determined using the fixable viability stain (FVS) assay. The influence of diethyl ether (Et2O) fraction (JM4) and 22 on apoptosis induction was investigated using an annexin V binding assay. The obtained results showed significant cytotoxicity of JM4 and 22 with IC50 values of 119.7 ± 3.2 and 95.1 ± 7.2 μg/mL, respectively. The proapoptotic potential after 22 treatment in the C32 human amelanotic melanoma cell line was comparable to that of vinblastine sulfate (VLB), detecting 29.2 ± 3.0% apoptotic cells. Moreover, 22 displayed less necrotic potential against melanoma cells than VLB. In addition, the influences of JM4 and 22 on the dysfunction of the mitochondrial membrane potential (MMP), cell cycle and activity of caspases 3, 8, 9, and 10 were established. The effects of JM4 on MMP change (74.5 ± 3.0% of the cells showed a reduced MMP) corresponded to the results obtained from the annexin V binding assay and activation of caspase-9. JM4 and 22 displayed a significant impact on caspase-9 (40.9 ± 2.4% of the cells contained active caspase-9 after JM4 treatment and 16.6 ± 0.8% after incubation with 22) and the intrinsic (mitochondrial) apoptotic pathway. Moreover, studies have shown that JM4 and 22 affect the activation of external apoptosis pathways by inducing the caspase-8 and caspase-10 cascades. Thus, activation of caspase-3 and DNA damage via external and internal apoptotic pathways were observed after treatment with JM4 and 22. The obtained results suggest that J. montana extracts could be developed as new topical preparations with potential anticancer properties due to their promising cytotoxic and proapoptotic potential.

Genetic studies were conducted to examine the heritage of resistant to cotton leaf curl virus. Genetic components of variance revealed higher σ2GCA and Additive (σ2A) than σ2SCA and Dominance (σ2D), which indicated additive genes were more reliable for inheritance of resistance to CLCV. The ratio of variances σ2gca/σ2sca was higher than unity (one) and further proved from degree of dominance [σ2A/σ2D]0.5 which was greater than one and confirmed supremacy of additive genes at both locations and generations. The heritability narrow sense (h2) and broad sense (H2) was found higher which suggested role of additive genes, which are fixable. Therefore selection would be effective in early segregating generation according to the symptoms of cotton leaf curl virus. The GCA effects for CLCV showed that among the parents, Mac-7 found as good general combiner with highest significant negative GCA effects at both locations in F1 and F2 which considered as CLCV resistant parent. The SCA effects exhibited that hybrid, Mac-7 x USD16-3058, CIM-602 x Mac-7 and NIA-Noori x Mac-7 showed significant negative SCA effect in both generations and locations. It was noted that cross combinations involved good x poor and poor x good general combiner with significant SCA effect was due to complementary gene action which produce desirable transgressive segregants, these can be further studies through bi-parental mating of diallel selective mating or any other form of recurrent selection in early generation with single plant selection to exploited both additive an non-additive gene action.

The paper is a contribution to the LINK 2021 Special Track: Informing design and practice-led research from the epistemology of the Santiago school of cognition. It presents a general ecological model of student learning in higher education, weaving together different threads from student learning research, Bateson’s work on the ecology of mind, and the concepts of autopoiesis and enactivism that emerge from the work of Maturana and Varela in the Santiago school. The paper takes as its starting point the seminal research on deep and surface approaches to student learning, developed inter alia by Marton, Biggs, Ramsden, Prosser and Trigwell during the 80s and 90s. While other neoliberal understandings of student learning as ‘engagement’ or ‘employability’ tend to dominate current discourse, the deep/surface literature is still widely cited and forms the basis of many courses in teaching in higher education. What is less explored are the ways in which the deep/surface learning research resonates with Bateson’s ecological views on mind and learning, and the idea of the embodied mind as developed from the pioneering work of Maturana and Varela. This research also emerged in the 80s and 90s. By tracing the patterns that connect these earlier ideas with current advances in 4E cognition and biosemiotics, the paper develops an ecological model of student learning based on concepts of non-linearity, emergence, complexity, embodiment, cognition as biological, learning as dialogical enquiry, communities of learning and practice, and the shaping influences of power circulating through information networks. The model visually depicts a process of learning informed by key principles: • Both the cognizing agent and everything with which it is associated are in constant flux, each adapting to the other in the same way that the environment evolves simultaneously with the species that inhabit it. • Learning (and similarly teaching) cannot be understood in monologic terms; there is no direct causal, linear, fixable relationship among the various components of any community. Rather, all the contributing factors in any teaching/learning situation are intricately, ecologically and complexly related. • Cognition is thus not the passive representation of a pre-existing world ‘out there’ but rather the ongoing bringing forth or enactment of a world through the biological processes of living. • Learning/teaching is a process of mutually enacting meaning—the student and teacher bringing forth a world together. • Cognition is not located within the abstractions of a decontextualised individual consciousness, but rather in the processes of shared action. • Knowledge is not separate from the world but embedded within it in a series of interrelated systems. • The individual self is thus constituted in a network of relationships. • Enactivism is an ecological epistemology where individual mind is an emergent property of interactions between organism and environment. • An enactivist view of the teaching/learning ecology sees teachers and learners embedded in a dynamic system of relationships between people, information, knowledge, and the institutional structures and processes that form the context of learning. The system acts to generate knowledge by transforming information into understanding.

Abstract Risk assessments are an important part of HAZOPs, root cause analysis studies, and other process safety evaluations. But process risk assessments, as typically performed, suffer from several identifiable and fixable flaws. These include: The assumption that accidents have a root cause, such as a component failure or human error,Ambiguous risk matrices that yield questionable and non-repeatable results,Flawed concepts of how people in the ‘line of fire’ make decisions. Failure to identify/acknowledge common failure modes when they exist at a hierarchical level above the component level. This paper addresses all these flaws and suggests solutions. The solutions are based on several schools of thought, including: Nancy Leveson's System Theoretic Accident Model and Processes (STAMP)Gary Klein's work on Naturalistic Decision Making (NDM)James Reasons’ work on human error,Level of Protection Analysis (LOPA) and Safety Integrity Level (SIL)Complexity science and Hierarchy Theory Three cases studies are used to illustrate the implications of these flaws in practice and the power of improved approaches. Evaluation of a root cause analysis (conducted by others) of a fatal accident involving loss of containment of sour water.Comparison of the use of a typical color-coded risk matrix vs. LOPA-based risk matrix for process risk assessment.A risk assessment study used to determine which valves on a sour gas platform should be locked open or locked closed.