1000 resultados para Seed regeneration


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A protease inhibitor from the seeds of Butea monosperma (BmPI) was purified, characterized and studied for its influence on developmental physiology of Helicover-pa armigera. BmPI on two-dimensional separations indicated the presence of a 14 kDa protein with an isoelectric point in the acidic region (pl 5.6). Multiple Sequence Analysis data suggested that the BmPI contains a sequence motif which is conserved in various trypsin and chymotrypsin inhibitors of Kunitz-type. The inhibitor exhibited trypsin inhibitory activity in a broad range of pH (4-10) and temperature (10-80 degrees C). The enzyme kinetic studies revealed BmPI as a competitive inhibitor with a K-i value of 1.2 x 10(-9) M. In vitro studies with BmPI indicated measurable inhibitory activity on total gut proteolytic enzymes of H. armigera (IC(50)2.0 mu g/ml) and bovine trypsin. BmPI supplemented artificial diet caused dose dependent mortality and reduction in growth and weight. The fertility and fecundity of H. armigera, declined whereas the larval-pupal duration of the insect life cycle extended. These detrimental effects on H. armigera suggest the usefulness of BmPl in insect pest management of food crops. (C) 2014 Elsevier Ltd. All rights reserved.

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Logging and hunting are two key direct threats to the survival of wildlife in the tropics, and also disrupt important ecosystem processes. We investigated the impacts of these two factors on the different stages of the seed dispersal cycle, including abundance of plants and their dispersers and dispersal of seeds and recruitment, in a tropical forest in north-east India. We focused on hornbills, which are important seed dispersers in these forests, and their food tree species. We compared abundances of hornbill food tree species in a site with high logging and hunting pressures (heavily disturbed) with a site that had no logging and relatively low levels of hunting (less disturbed) to understand logging impacts on hornbill food tree abundance. We compared hornbill abundances across these two sites. We, then, compared the scatter-dispersed seed arrival of five large-seeded tree species and the recruitment of four of those species. Abundances of hornbill food trees that are preferentially targeted by logging were two times higher in the less disturbed site as compared to the heavily disturbed site while that of hornbills was 22 times higher. The arrival of scatter-dispersed seeds was seven times higher in the less disturbed site. Abundances of recruits of two tree species were significantly higher in the less disturbed site. For another species, abundances of younger recruits were significantly lower while that of older recruits were higher in the heavily disturbed site. Our findings suggest that logging reduces food plant abundance for an important frugivore-seed disperser group, while hunting diminishes disperser abundances, with an associated reduction in seed arrival and altered recruitment of animal-dispersed tree species in the disturbed site. Based on our results, we present a conceptual model depicting the relationships and pathways between vertebrate-dispersed trees, their dispersers, and the impacts of hunting and logging on these pathways.

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AimBiodiversity outcomes under global change will be influenced by a range of ecological processes, and these processes are increasingly being considered in models of biodiversity change. However, the level of model complexity required to adequately account for important ecological processes often remains unclear. Here we assess how considering realistically complex frugivore-mediated seed dispersal influences the projected climate change outcomes for plant diversity in the Australian Wet Tropics (all 4313 species). LocationThe Australian Wet Tropics, Queensland, Australia. MethodsWe applied a metacommunity model (M-SET) to project biodiversity outcomes using seed dispersal models that varied in complexity, combined with alternative climate change scenarios and habitat restoration scenarios. ResultsWe found that the complexity of the dispersal model had a larger effect on projected biodiversity outcomes than did dramatically different climate change scenarios. Applying a simple dispersal model that ignored spatial, temporal and taxonomic variation due to frugivore-mediated seed dispersal underestimated the reduction in the area of occurrence of plant species under climate change and overestimated the loss of diversity in fragmented tropical forest remnants. The complexity of the dispersal model also changed the habitat restoration approach identified as the best for promoting persistence of biodiversity under climate change. Main conclusionsThe consideration of complex processes such as frugivore-mediated seed dispersal can make an important difference in how we understand and respond to the influence of climate change on biodiversity.

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Woody tree species in seasonally dry tropical forests are known to have traits that help them to recover from recurring disturbances such as fire. Two such traits are resprouting and rapid post-fire growth. We compared survival and growth rates of regenerating small-sized individuals (juveniles) of woody tree species after dry season fire (February-March) at eight adjacent pairs of burnt and unburnt transects in a seasonally dry tropical forest in southern India. Juveniles were monitored at 3-mo intervals between August 2009 and August 2010. High juvenile survivorship (>95%) was observed in both burnt and unburnt areas. Growth rates of juveniles, analyzed at the community level as well as for a few species individually (especially fast-growing ones), were distinctly higher in burnt areas compared to unburnt areas after a fire event, particularly during the pre-monsoon season immediately after a fire. Rapid growth by juveniles soon after a fire may be due to lowered competition from other vegetative forms such as grasses, possibly aided by the availability of resources stored belowground. Such an adaptation would allow a juvenile bank to be retained in the understory of a dry forest, from where individuals can grow to a possible fire-tolerant size during favorable conditions.

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As populations of the world's largest animal species decline, it is unclear how ecosystems will react to their local extirpation. Due to the unique ecological characteristics of megaherbivores such as elephants, seed dispersal is one ecosystem process that may be affected as populations of large animals are decimated. In typically disturbed South Asian ecosystems, domestic bovids (cattle, Bos primigenius, and buffalo, Bubalus bubalis) may often be the species most available to replace Asian elephants (Elephas maximus) as endozoochorous dispersers of large-fruited mammal-dispersed species. We use feeding trials, germination trials, and movement data from the tropical moist forests of Buxa Tiger Reserve (India) to examine whether domestic bovids are viable replacements for elephants in the dispersal of three largefruited species: Dillenia indica, Artocarpus chaplasha, and Careya arborea. We find that (1) once consumed, seeds are between 2.5 (C. arborea) and 26.5 (D. indica) times more likely to pass undigested into elephant dung than domestic bovid dung; and (2) seeds from elephant dung germinated as well as or better than seeds taken from bovid dung for all plant species, with D. indica seeds from elephant dung 1.5 times more likely to germinate. Furthermore, since wild elephants have less constrained movements than even free-roaming domestic bovids, we calculate that maximum dispersal by elephants is between 9.5 and 11.2 times farther than that of domestic bovids, with about 20% of elephant-dispersed seeds being moved farther than the maximum distance seeds are moved by bovids. Our findings suggest that, while bovids are able to disperse substantial numbers of seeds over moderate distances for two of the three study species, domestic bovids will be unable to routinely emulate the reliable, long-distance dispersal of seeds executed by elephants in this tropical moist forest. Thus while domestic bovids can attenuate the effects of losing elephants as dispersers, they may not be able to prevent the decline of various mammal-dispersed fruiting species in the face of overhunting, habitat fragmentation, and climate change.

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Primates constitute 25-40 % of the frugivore biomass of tropical forests. Primate fruit preference, as a determinant of seed dispersal, can therefore have a significant impact on these ecosystems. Although the traits of fruits included in primate diets have been described, fruit trait preference has been less studied with respect to fruit availability. We examined fruit trait preference and its implications for seed dispersal in the rhesus macaque (Macaca mulatta), a dietarily flexible species and important seed disperser, at the Buxa Tiger Reserve, India. Over a year, we monitored the phenology of selected trees in the study area, observed the feeding behavior of rhesus macaques using scans and focal animal sampling, and documented morphological traits of the fruits/seeds consumed. Using generalized linear modeling, we found that the kind of edible tissue was the chief determinant of fruit consumption, with M. mulatta feeding primarily on fruits with juicy-soft pulp and acting as seed predators for those with no discernible pulp. Overall, the preferred traits were external covers that could be easily pierced by a fingernail, medium to large seeds, true stone-like seeds, and juicy-soft edible tissue, thereby implying that fruit taxa with these traits had a higher probability of being dispersed. Macaques were more selective during the high fruit availability period than the low fruit availability period, preferentially feeding on soft-skinned fruits with juicy-soft pulp. We suggest that further studies be conducted across habitats and time to understand the consistency of interactions between primates and fruits with specific traits to determine the degree of selective pressure (if any) that is exerted by primates on fruit traits.

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Elephants are thought to be effective seed dispersers, but research on whether elephant dung effectively protects seeds from seed predation is lacking. Quantifying rates of seed predation from elephant dung will facilitate comparisons between elephants and alternative dispersers, helping us understand the functional role of megaherbivores in ecosystems. We conducted an experiment to quantify the predation of Dillenia indica seeds from elephant dung in Buxa Reserve, India from December 2012 to April 2013. Using dung boluses from the same dung pile, we compared the number of seeds in boluses that are a) opened immediately upon detection (control boluses), b) made available only to small seed predators (<= 3 mm wide) for 1-4 months, and c) made available to all seed predators and secondary dispersers for 1-4 months. Using a model built on this experiment, we estimated that seed predation by small seed predators (most likely ants and termites) destroys between 82.9% and 96.4% of seeds in elephant dung between the time of defecation and the median germination date for D. indica. Exposure to larger seed predators and secondary dispersers did not lead to a significant additional reduction in the number of seeds per dung bolus. Our findings suggest that post-dispersal seed predation by small insects (<3 mm) substantially reduces but does not eliminate the success of elephants as dispersers of D. indica in a tropical moist forest habitat. (C) 2015 Elsevier Masson SAS. All rights reserved.

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Toward preparing strong multi-biofunctional materials, poly(ethylenimine) (PEI) conjugated graphene oxide (GO_PEI) was synthesized using poly(acrylic acid) (PAA) as a spacer and incorporated in poly( e-caprolactone) (PCL) at different fractions. GO_PEI significantly promoted the proliferation and formation of focal adhesions in human mesenchymal stem cells (hMSCs) on PCL. GO_PEI was highly potent in inducing stem cell osteogenesis leading to near doubling of alkaline phosphatase expression and mineralization over neat PCL with 5% filler content and was approximate to 50% better than GO. Remarkably, 5% GO_ PEI was as potent as soluble osteoinductive factors. Increased adsorption of osteogenic factors due to the amine and oxygen containing functional groups on GO_ PEI augment stem cell differentiation. GO_ PEI was also highly efficient in imparting bactericidal activity with 85% reduction in counts of E. coli colonies compared to neat PCL at 5% filler content and was more than twice as efficient as GO. This may be attributed to the synergistic effect of the sharp edges of the particles along with the presence of the different chemical moieties. Thus, GO_ PEI based polymer composites can be utilized to prepare bioactive resorbable biomaterials as an alternative to using labile biomolecules for fabricating orthopedic devices for fracture fixation and tissue engineering.

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We have recently developed image processing techniques for measuring the cortical thicknesses of skeletal structures in vivo, with resolution surpassing that of the underlying computed tomography system. The resulting thickness maps can be analysed across cohorts by statistical parametric mapping. Applying these methods to the proximal femurs of osteoporotic women, we discover targeted and apparently synergistic effects of pharmaceutical osteoporosis therapy and habitual mechanical load in enhancing bone thickness. © 2011 Poole et al.

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Controlling the growth of ZnO nanostructures for photovoltaic applications will ensure greater device efficiency and parameter control. This paper reports on methods to engineer the morphology and tailor the nanostructure growth direction through the hydrothermal synthesis method. Effective control is achieved through the use of a sputtered zinc layer together with modifications of the growth solution. These nanostructures have been developed with a view to incorporation into excitonic solar cells, and methods to improve surface stability using a fully aqueous synthesis method will be discussed. © by Oldenbourg Wissenschaftsverlag, München.

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Feeding trial was conducted in static water to assess the growth of H. longifilis fingerlings fed different I inclusion levels of mucuna seed meal (MSM). Raw and boiled MSM were used in the diets at 10%, 20%, 30% and 40% inclusion levels and the performance of fish fed these diets was compared with fish fed a fishmeal-based diet which contained 40% protein. All diets were prepared to be isonitrogenous and isocaloric A two by five factorial experiment with three replicates using ten fish of average initial weight 1 .46g was carried out. Daily fish ration of five percent body weight was administered two times for eight weeks. The specific growth rate in diets 1 (control) and 6(10% boiled MSM) were similar and significantly (P<0.05) higher than the other dietary groups. The significantly lower growth performance of fish fed diets containing higher inclusion levels of both raw and boiled MSM might be due to incomplete elimination of the antinutritional factors present in MSM by boiling. Other methods of processing MSM to improve its nutritive value should be investigated. (7 page document)

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Document contains 4 pages.