Rethinking the approach to viability monitoring in seed genebanks.
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ABSTRACT:
SUBMITTER: Hay FR
PROVIDER: S-EPMC5356937 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundSome neotropical, fleshy-fruited plants have fruits structurally similar to paleotropical fruits dispersed by megafauna (mammals > 10(3) kg), yet these dispersers were extinct in South America 10-15 Kyr BP. Anachronic dispersal systems are best explained by interactions with extinct animals and show impaired dispersal resulting in altered seed dispersal dynamics.Methodology/principal findingsWe introduce an operational definition of megafaunal fruits and perform a comparative analysis of 103 Neotropical fruit species fitting this dispersal mode. We define two megafaunal fruit types based on previous analyses of elephant fruits: fruits 4-10 cm in diameter with up to five large seeds, and fruits > 10 cm diameter with numerous small seeds. Megafaunal fruits are well represented in unrelated families such as Sapotaceae, Fabaceae, Solanaceae, Apocynaceae, Malvaceae, Caryocaraceae, and Arecaceae and combine an overbuilt design (large fruit mass and size) with either a single or few (< 3 seeds) extremely large seeds or many small seeds (usually > 100 seeds). Within-family and within-genus contrasts between megafaunal and non-megafaunal groups of species indicate a marked difference in fruit diameter and fruit mass but less so for individual seed mass, with a significant trend for megafaunal fruits to have larger seeds and seediness.Conclusions/significanceMegafaunal fruits allow plants to circumvent the trade-off between seed size and dispersal by relying on frugivores able to disperse enormous seed loads over long-distances. Present-day seed dispersal by scatter-hoarding rodents, introduced livestock, runoff, flooding, gravity, and human-mediated dispersal allowed survival of megafauna-dependent fruit species after extinction of the major seed dispersers. Megafauna extinction had several potential consequences, such as a scale shift reducing the seed dispersal distances, increasingly clumped spatial patterns, reduced geographic ranges and limited genetic variation and increased among-population structuring. These effects could be extended to other plant species dispersed by large vertebrates in present-day, defaunated communities.
| S-EPMC2258420 | biostudies-literature
Project description:Despite considerable advances in pharmacotherapy and self-monitoring technologies in the last decades, a large percentage of adults with diabetes remain unsuccessful in achieving optimal glucose due to suboptimal medication adherence. Contributors to suboptimal adherence to insulin treatment include pain, inconvenience, and regimen complexity; however, a key driver is hypoglycemia. Improvements in the PK/PD characteristics of today's SC insulins provide more physiologic coverage of basal and prandial insulin requirements than regular human insulin; however, they do not achieve the rapid on/rapid off characteristics of endogenously secreted insulin seen in healthy, nondiabetic individuals. Pulmonary administration of prandial insulin represents an attractive option that overcomes limitations of SC insulin by providing more a rapid onset of action and a faster return of action to baseline levels than SC administration of rapid-acting insulin analogs. This article reviews the unique PK/PD properties of a novel inhaled formulation that support its use in patient populations with T1D or T2D.
| S-EPMC5863311 | biostudies-other
Project description:Recent advances in the noninvasive analyses of plant metabolism include stress imaging techniques, mainly developed for vegetative tissues. We explored if infrared thermography can be used to predict whether a quiescent seed will germinate or die upon water uptake. Thermal profiles of viable, aged, and dead Pisum sativum seeds were recorded, and image analysis of 22,000 images per individual seed showed that infrared thermography can detect imbibition- and germination-associated biophysical and biochemical changes. These "thermal fingerprints" vary with viability in this species and in Triticum aestivum and Brassica napus seeds. Thermogenesis of the small individual B. napus seeds was at the limit of the technology. We developed a computer model of "virtual pea seeds," that uses Monte Carlo simulation, based on the heat production of major seed storage compounds to unravel physico-chemical processes of thermogenesis. The simulation suggests that the cooling that dominates the early thermal profiles results from the dissolution of low molecular-weight carbohydrates. Moreover, the kinetics of the production of such "cooling" compounds over the following 100 h is dependent on seed viability. We also developed a deterministic tool that predicts in the first 3 hours of water uptake, when seeds can be redried and stored again, whether or not a pea seed will germinate. We believe that the early separation of individual, ungerminated seeds (live, aged, or dead) before destructive germination assessment creates unique opportunities for integrative studies on cell death, differentiation, and development.
| S-EPMC2840516 | biostudies-literature
Project description:Hydration?dehydration cycles can frequently cause stress to seeds, but can also be used to improve germination. However, the molecular basis of the stress caused is poorly understood. Herein, we examine the effects of hydration?dehydration cycles on seed viability and profile the membrane glycerolipid molecular species. We find that seed viability was not affected during the first two cycles, but significantly decreased as further cycles were applied, until all viability was lost. The abundances of seven glycerolipid classes increased and decreased through hydration and dehydration, respectively, but the phosphatidic acid and diacylglycerol abundances changed in the opposite sense, while total glycerolipid contents remained constant. This suggests that during hydration?dehydration cycles, turnover of glycerolipid metabolite pools take place, while no significant lipid synthesis or degradation is involved. As further hydration?dehydration cycles occurred, lipid unsaturation increased, plastidic lipids decreased, and phosphatidylserine acyl chains lengthened. The latter two could be lethal for seeds. Our findings reveal a novel model of membrane lipid changes, and provide new insights into the responses of seeds to hydration?dehydration cycles.
| S-EPMC5983817 | biostudies-other
Project description:Mercury (Hg) has been identified as one of the most toxic nonradioactive materials known to man. Although mercury is a naturally occurring element, anthropogenic mercury is now a major worldwide concern and is an international priority toxic pollutant. It also comprises one of the primary constituents of dental amalgam fillings. Even though dental mercury amalgams have been used for almost two centuries, its safety has never been tested or proven in the United States by any regulatory agency. There has been an ongoing debate regarding the safety of its use since 1845, and many studies conclude that its use exposes patients to troublesome toxicity. In this review, we present in an objective way the danger of dental amalgam to human health based on current knowledge. This dilemma is addressed in terms of an integrated toxicological approach by focusing on four mayor issues to show how these interrelate to create the whole picture: (1) the irrefutable constant release of mercury vapor from dental amalgams which is responsible for individual chronic exposure, (2) the evidence of organic mercury formation from dental amalgam in the oral cavity, (3) the effect of mercury exposure on gene regulation in human cells which supports the intrinsic genetic susceptibility to toxicant and, finally, (4) the availability of recent epidemiological data supporting the link of dental amalgams to diseases such as Alzheimer's and Parkinson.
| S-EPMC6466133 | biostudies-literature
Project description:BackgroundCurrent definitions of 'global health' lack specificity about the term 'global'. This debate presents and discusses existing definitions of 'global health' and a common problem inherent therein. It aims to provide a way forward towards an understanding of 'global health' while avoiding redundancy. The attention is concentrated on the dialectics of different concepts of 'global' in their application to malnutrition; HIV, tuberculosis & malaria; and maternal mortality. Further attention is payed to normative objectives attached to 'global health' definitions and to paradoxes involved in attempts to define the field.DiscussionThe manuscript identifies denotations of 'global' as 'worldwide', as 'transcending national boundaries' and as 'holistic'. A fourth concept of 'global' as 'supraterritorial' is presented and defined as 'links between the social determinants of health anywhere in the world'. The rhetorical power of the denotations impacts considerably on the object of 'global health', exemplified in the context of malnutrition; HIV, tuberculosis & malaria; and maternal mortality. The 'global' as 'worldwide', as 'transcending national boundaries' and as 'holistic' house contradictions which can be overcome by the fourth concept of 'global' as 'supraterritorial'. The 'global-local-relationship' inherent in the proposed concept coheres with influential anthropological and sociological views despite the use of different terminology. At the same time, it may be assembled with other views on 'global' or amend apparently conflicting ones. The author argues for detaching normative objectives from 'global health' definitions to avoid so called 'entanglement-problems'. Instead, it is argued that the proposed concept constitutes an un-euphemistical approach to describe the inherently politicised field of 'global health'.SummaryWhile global-as-worldwide and global-as-transcending-national-boundaries are misleading and produce redundancy with public and international health, global-as-supraterritorial provides 'new' objects for research, education and practice while avoiding redundancy. Linked with 'health' as a human right, this concept preserves the rhetorical power of the term 'global health' for more innovative forms of study, research and practice. The dialectic approach reveals that the contradictions involved in the different notions of the term 'global' are only of apparent nature and not exclusive, but have to be seen as complementary to each other if expected to be useful in the final step.
| S-EPMC2987787 | biostudies-literature
Project description:Desiccation tolerance appeared as the key adaptation feature of photoautotrophic organisms for survival in terrestrial habitats. During the further evolution, vascular plants developed complex anatomy structures and molecular mechanisms to maintain the hydrated state of cell environment and sustain dehydration. However, the role of the genes encoding the mechanisms behind this adaptive feature of terrestrial plants changed with their evolution. Thus, in higher vascular plants it is restricted to protection of spores, seeds and pollen from dehydration, whereas the mature vegetative stages became sensitive to desiccation. During maturation, orthodox seeds lose up to 95% of water and successfully enter dormancy. This feature allows seeds maintaining their viability even under strongly fluctuating environmental conditions. The mechanisms behind the desiccation tolerance are activated at the late seed maturation stage and are associated with the accumulation of late embryogenesis abundant (LEA) proteins, small heat shock proteins (sHSP), non-reducing oligosaccharides, and antioxidants of different chemical nature. The main regulators of maturation and desiccation tolerance are abscisic acid and protein DOG1, which control the network of transcription factors, represented by LEC1, LEC2, FUS3, ABI3, ABI5, AGL67, PLATZ1, PLATZ2. This network is complemented by epigenetic regulation of gene expression via methylation of DNA, post-translational modifications of histones and chromatin remodeling. These fine regulatory mechanisms allow orthodox seeds maintaining desiccation tolerance during the whole period of germination up to the stage of radicle protrusion. This time point, in which seeds lose desiccation tolerance, is critical for the whole process of seed development.
| S-EPMC7795748 | biostudies-literature
Project description:In recent years, the pressure for replanting and resetting huanglongbing (HLB or citrus greening) affected citrus groves has led to an inadequate seed supply for the most popular rootstock cultivars in the State of Florida, United States. Early fruit harvesting of citrus rootstock source trees might reduce fruit losses and enhance seed availability, especially in HLB-endemic and hurricane susceptible areas, if the physiological quality of the seeds is adequate. The effects of fruit maturity on seed quality and seedling performance of US-802, US-897, and US-942 citrus rootstocks were investigated for two consecutive growing seasons. The study included the evaluation of seed germination and nursery performance of the citrus rootstock seedlings. The germination test was performed in vitro, where seeds were hand-peeled, surface-sterilized and placed in culture tubes containing basal Murashige and Skoog medium. For the emergence test, seeds were sown in seedling trays containing sterilized growing substrate in a greenhouse with controlled-environment conditions. Rootstock fruits from all three varieties harvested in August and September had seeds with higher germination potential, as more than 90% of the seeds generated seedlings. US-942 had more % of emergence than US-802 and US-897, resulting in faster seed germination; in contrast, US-802 had the faster shoot growth rate. Assays on fruit abscission response showed that by August, fruit from all three varieties were responsive to ethylene and abscised, although response varied and was higher in US-942, suggesting the seeds were mature enough. Taken together, our findings indicate that fruits these three rootstocks can be harvested as early as August in contrast to the current procedures without losing germination potential. This will result in an increase in available seeds for nurseries in Florida.
| S-EPMC8641648 | biostudies-literature
Project description:Changes in phospholipid composition and consequent loss of membrane integrity are correlated with loss of seed viability. Furthermore, phospholipid compositional changes affect the composition of the triacylglycerols (TAG), i.e. the storage lipids. Phospholipase D (PLD) catalyses the hydrolysis of phospholipids to phosphatidic acid, and PLD? is an abundant PLD isoform. Although wild-type (WT) seeds stored for 33?months were non-viable, 30%-50% of PLD?-knockdown (PLD-KD) soybean seeds stored for 33?months germinated. WT and PLD-KD seeds increased in lysophospholipid levels and in TAG fatty acid unsaturation during ageing, but the levels of lysophospholipids increased more in WT than in PLD-KD seeds. The loss of viability of WT seeds was correlated with alterations in ultrastructure, including detachment of the plasma membrane from the cell wall complex and disorganization of oil bodies. The data demonstrate that, during natural ageing, PLD? affects the soybean phospholipid profile and the TAG profile. Suppression of PLD activity in soybean seed has potential for improving seed quality during long-term storage.
| S-EPMC3728994 | biostudies-literature
Project description:Physical activity is important for children's health. However, evidence suggests that many children and adults do not meet international physical activity recommendations. Current school-based interventions have had limited effect on physical activity and alternative approaches are needed. Context, which includes school setting, ethos, staff, and sociodemographic factors, is a key and largely ignored contributing factor to school-based physical activity intervention effectiveness, impacting in several interacting ways.ConceptualizationCurrent programs focus on tightly-constructed content that ignores the context in which the program will be delivered, thereby limiting effectiveness. We propose a move away from uniform interventions that maximize internal validity toward a flexible approach that enables schools to tailor content to their specific context.Evaluation designsEvaluation of context-specific interventions should explicitly consider context. This is challenging in cluster randomized controlled trial designs. Thus, alternative designs such as natural experiment and stepped-wedge designs warrant further consideration.Primary outcomeA collective focus on average minutes of moderate-to-vigorous intensity physical activity may not always be the most appropriate choice. A wider range of outcomes may improve children's physical activity and health in the long-term. In this paper, we argue that greater consideration of school context is key in the design and analysis of school-based physical activity interventions and may help overcome existing limitations in the design of effective interventions and thus progress the field. While this focus on context-specific interventions and evaluation is untested, we hope to stimulate debate of the key issues to improve future physical activity intervention development and implementation.
| S-EPMC10133698 | biostudies-literature