482 research outputs found

    Influence of genotype and age of explant source on the capacity for somatic embryogenesis of two Cavendish banana cultivars (Musa acuminata Colla, AAA)

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    The embryogenic capacities of flower explants from one- and two-week-old male inflorescence buds from Musa acuminata Cavendish, AAA, genotypes ‘Williams’ and ‘Grand Naine’ were investigated. Explants of hands with immature flowers were excised and induced for embryogenesis. Highlysignificant differences were found in the embryogenic response, depending on the genotype and the developmental stage of the buds from which the explants were excised. After four months of induction, the total percentage of callus formed ranged from 97.81% in explants of two-week-old ‘Williams’ buds to 52.11% in explants of two-week-old ‘Grand Naine’ buds. Embryogenic callus formation was, on average, higher in the two-week-old ‘Williams’ explants (10.01%) than in the one-week-old explants (0.78%). The opposite was true for ‘Grand Naine’, with 7.51% embryogenic callus produced in explants of one-week-old buds compared to 2.49% in two-week-old buds. Selected embryogenic calluses that were successfully established on proliferation medium led to embryogenic cell suspensions with good regeneration capacities. Fifteen to thirty-five percent of the embryos germinated, demonstrated high plant-conversion capacity (99%). The effect of the interaction between the developmental age ofexplant and the genotype on the embryogenesis response is discussed

    Experimental investigation of steel building gravity framing systems under strong earthquake shaking

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    Hybrid simulations were conducted to evaluate the system-level seismic response of a 4-story steel moment frame building and its gravity framing system through various levels of ground motion shaking. The experimental substructure examined in detail corresponds to a half-scale 1½-bay by 1½-story subassembly of the steel gravity frame. Unlike typical beam-to-column connection tests, the subassembly, which represented typical gravity framing steel construction, captured the redistribution of force demands in beams, columns, panel zones, and the composite floor slab while exhibiting inelastic behavior. Horizontal as well as varying vertical forces were applied on the test specimen to mimic realistic boundary and loading conditions. This paper focuses on the experimental response of the gravity framing system and its contribution to the lateral resistance of a steel frame building. In particular, the lateral resistance and failure mechanisms of the test frame are described and compared to numerical simulations based on state-of-the-art modeling approaches. The data generated from these experiments provides valuable insight on gravity frame behavior towards improvement and verification of frame models at the system level

    Screening of bacterial endophytes able to promote plant growth and increase salinity tolerance

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    Bacterial endophytes can colonize plant tissues without harming the plant. Instead, they are often able to increase plant growth and tolerance to environmental stresses. In this work, new strains of bacterial endophytes were isolated from three economically important crop plants (sorghum, cucumber and tomato) grown in three different regions in soils with different management. All bacterial strains were identified by 16S rRNA sequencing and characterized for plant beneficial traits. Based on physiological activities, we selected eight strains that were further tested for their antibiotic resistance profile and for the ability to efficiently colonize the interior of sorghum plants. According to the results of the re-inoculation test, five strains were used to inoculate sorghum seeds. Then, plant growth promotion activity was assessed on sorghum plants exposed to salinity stress. Only two bacterial endophytes increased plant biomass, but three of them delayed or reduced plant salinity stress symptoms. These five strains were then characterized for the ability to produce the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which is involved in the increase of stress tolerance. Pseudomonas brassicacearum SVB6R1 was the only strain that was able to produce this enzyme, suggesting that ACC deaminase is not the only physiological trait involved in conferring plant tolerance to salt stress in these bacterial strains

    Microbiome engineering to improve biocontrol and plant growth-promoting mechanisms

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    The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.micres.2018.01.005 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/A plant microbiome includes a microbial community that typically interacts extensively with a plant. The plant microbiome can survive either inside or outside of plant tissues, performing various plant beneficial activities including biocontrol of potential phytopathogens and promotion of plant growth. An important part of the plant microbiome includes plant growth-promoting bacteria (PGPB) that commonly reside in the rhizosphere and phyllosphere, and as endophytic bacteria (inside of plant tissues). As new plant microbiome-manipulating strategies have emerged in recent years, we have critically reviewed relevant literature, chiefly from the last decade. We have analysed and compared the rhizosphere, phyllosphere and endosphere as potential ecosystems for manipulation, in order to improve positive interactions with the plant. In addition, many studies on the bioengineering of the endophyte microbiome and its potential impact on the core microbiome were analysed with respect to five different strategies, including host mediated and multi-generation microbiome selection, inoculation into soil and rhizosphere, inoculations into seeds or seedlings, tissue atomisation and direct injection into tissues or wounds. Finally, microbiome engineering presents a feasible strategy to solve multiple agriculture-associated problems in an eco-friendly way.Fundación Santoy

    Mapping the structure of mixed seagrass meadows in the Mexican Caribbean

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    The physical and ecological importance of seagrass meadows in coastal processes is widely recognized, and the development of tools facilitating characterization of their structure and distribution is important for improving our understanding of these processes. Mixed (multi-specific) meadows in a Mexican Caribbean reef lagoon were mapped employing a multiparameter approach, using PlanetScope remote sensing images, and supervised classification based on parameters related to the structure of the seagrasses meadows, including the cover percentages of seagrass/algae/sediment, algae thalli and seagrass shoot densities, canopy heights and estimated leaf area index (LAI). The cover, seagrass and algae densities, and seagrass canopy heights were obtained using ground truth sampling, while the LAI was estimated using data obtained from long-term monitoring programs. The maps do not show the differentiation of seagrass species, but ground truthing contemplated characterization of the density of Thalassia testudinum, Syringodium filiforme and Halodule wrightii and their respective LAIs. S. filiforme was the dominant species in terms of shoot density, and T. testudinum was dominant in terms of LAI. In the multiparameter-based map four classes were defined, based on the cover and structural characteristics, and its overall accuracy was very high (~90%). Maps based on sediment cover and LAI alone also had 4 classes, but they were less accurate than the multiparameter-based map (~70% and ~80%, respectively). The multiparameter-based seagrass map provided spatially-explicit data on the abundance and structure of seagrasses, useful for future monitoring of the changes in the meadows, and also for studies of that require data of large-scale meadow structure, such as inventories of associated biota, blue carbon storage, or modelling of the local hydrodynamics

    Reflecting Back to Forge the Path Forward

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    The JUME editorial team provides an update of the journal\u27s health and progress during the 2021 calendar year and discusses coming changes and opportunities for growth

    The End or Beginning? Either Way, the Credits Are Not Rolling Yet!

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    (First paragraph) Thank you to all our reviewers, editorial board members, authors, and those who chose the Journal of Urban Mathematics Education (JUME) as their outlet of choice this past year. JUME has had many recent successes, and we in the editorial team plan to release the salient performance data for the journal. For JUME to advance its mission, we believe that accountability and transparency are essential. To this end, our readers will from now on receive an annual progress report about JUME in our first issue of each year

    Engaging Undergraduates in Science Research: Not Just About Faculty Willingness.

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    Despite the many benefits of involving undergraduates in research and the growing number of undergraduate research programs, few scholars have investigated the factors that affect faculty members' decisions to involve undergraduates in their research projects. We investigated the individual factors and institutional contexts that predict faculty members' likelihood of engaging undergraduates in their research project(s). Using data from the Higher Education Research Institute's 2007-2008 Faculty Survey, we employ hierarchical generalized linear modeling to analyze data from 4,832 science, technology, engineering, and mathematics (STEM) faculty across 194 institutions to examine how organizational citizenship behavior theory and social exchange theory relate to mentoring students in research. Key findings show that faculty who work in the life sciences and those who receive government funding for their research are more likely to involve undergraduates in their research project(s). In addition, faculty at liberal arts or historically Black colleges are significantly more likely to involve undergraduate students in research. Implications for advancing undergraduate research opportunities are discussed

    Oral Melanoacanthoma And Oral Melanotic Macule: A Report Of 8 Cases, Review Of The Literature, And Immunohistochemical Analysis

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    Oral melanoacanthoma (MA) is a rare, benign pigmented lesion, similar to cutaneous MA, characterized by hyperplasia of spinous keratinocytes and dendritic melanocytes. The pathogenesis of oral MA remains uncertain, although its clinical behavior is suggestive of a reactive origin. The most common intraoral sites are the buccal mucosa, lip, palate and gingiva. The average age of presentation is 28 years, mainly in blacks, with a strong female predilection. The oral melanotic macule (MM) is a small, well-circumscribed brown-to-black macule that occurs on the lips and mucous membranes. The etiology is not clear and it may represent a physiologic or reactive process. The average age of presentation is 43 years, with a female predilection. A biopsy is recommended to distinguish these lesions from each other and from other oral melanocytic lesions. We depict four cases each of oral MA and MM, affecting Caucasian and Latin American mestizo patients. The clinicopathological features of these cases reflect its ample spectrum, and to the best of our knowledge, it is the first example of oral MA affecting a Caucasian boy reported in the English literature. Therefore oral MA and MM should be considered in the differential diagnosis of pigmented lesions in the oral mucosa in these populations. © Medicina Oral.125E374E379Mishima, Y., Pinkus, H., Benign mixed tumor of melanocytes and malpighian cells. Melanoacanthoma: Its relationship to Bloch's benign non-nevoid melanoepithelioma (1960) Arch Dermatol, 81, pp. 539-550Buchner, A., Merrell, P.W., Carpenter, W.M., Relative frequency of solitary melanocytic lesions of the oral mucosa (2004) J Oral Pathol Med, 33, pp. 550-557Wright, J.M., Binnie, W.H., Byrd, D.L., Dunsworth, A.R., Intraoral melanoacanthomas (1983) J Periodontol, 54, pp. 107-111Buchner, A., Merrell, P., Hanson, L., Leider, A., Melanocytic hyperplasia of the oral mucosa (1991) Oral Surg, Oral Med Oral Pathol, 71, pp. 58-62Wright, J.M., Intraoral melanoacanthoma: A reactive melanocytic hyperplasia. Case report (1988) J Periodontol, 59, pp. 53-55Tomich, C., Zunt, S.L., Melanoacanthosis (melanoacanthoma) of the oral mucosa (1990) J Dermatol Surg Oncol, 16, pp. 231-236Contreras, E., Carlos, R., Oral melanoacanthosis (melanoachantoma): Report of a case and review of the literature (2005) Med Oral Patol Oral Cir Bucal, 10 (1), pp. 11-12,9-11Fornatora, M.L., Reich, R.F., Haber, S., Solomon, F., Freedman, P.D., Oral melanoacanthomas: A report of 10 cases, review of the literature, and immunohistochemical analysis for HMB-45 reactivity (2003) Am J Dermatopathol, 25, pp. 12-15Matsuoka, L.Y., Glasser, S., Barsky, S., Melanoacanthoma of the lip (1979) Arch Dermatol, 115, pp. 1116-1117Goode, R.K., Crawford, B.E., Callihan, M.D., Neville, B.W., Oral melanoacanthoma. Review of the literature and report of ten cases (1983) Oral Surg Oral Med Oral Pathol, 56, pp. 622-628Scheneider, L.C., Mesa, M.L., Haber, S.M., Melanoacanthoma of the oral mucosa (1981) Oral Surg Oral Med Oral Pathol, 52, pp. 284-287Fatahzadeh, M., Sirois, D.A., Multiple intraoral melanoacanthomas: A case report with unusual findings (2002) Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 94, pp. 54-56Ho, K.K., Dervan, P., O'Loughlin, S., Powell, F.C., Labial melanotic macule: A clinical, histopathologic, and ultrastructural study (1993) J Am Acad of Dermatol, 28, pp. 33-39Sexton, F.M., Maize, J.C., Melanotic macules and melanoacanthomas of the lip. A comparative study with census of the basal melanocyte population (1987) Am J Dermatopathol, 9, pp. 438-444Horlick, H.P., Walther, R.R., Zegarelli, D.J., Silvers, D.N., Eliezri, Y.D., Mucosal melanotic macule, reactive type: A simulation of melanoma (1988) J Am Acad Dermatol, 19, pp. 786-791Buchner, A., Hansen, L.S., Pigmented nevi of the oral mucosa: A clinicopathologic study of 32 new cases and review of 75 cases from the literature: Part I. A clinicopathologic study of 32 new cases (1979) Oral Surg Oral Med Oral Pathol, 48, pp. 131-142Barker, B.F., Carpenter, W.M., Daniels, T.E., Kahn, M.A., Leider, A.S., Lozada-Nur, F., (1997) Oral mucosal melanomas: The WESTOP Banff workshop proceedings, 83, pp. 672-679. , Western Society of Teachers of Oral Pathology. Oral Surg Oral Med Oral Pathol Oral Radiol EndodBarrett, A.W., Raja, A.M., The immunohistochemical identification of human oral mucosal melanocytes (1997) Arch Oral Biol, 42, pp. 77-8
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