Natural Regeneration Capacity Research Articles

Conserved microRNA program as key to mammalian cardiac regeneration: insights from zebrafish.

The capacity of the adult mammalian heart to repair itself after injury is limited. In contrast, lower vertebrates such as Zebrafish can completely regenerate the organ after damage. A recent article from Aguirre et al1 in Cell Stem Cell shows that this difference is because of a microRNA program that is active in Zebrafish but silent in mammals. Crucially, reactivation of this dormant microRNA program in the murine heart induces regeneration of the myocardium. The adult mammalian heart possesses a limited capacity to regenerate lost or damaged cardiomyocytes after cardiac insult.2 This is, in part, because of the low proliferative capacity of adult cardiomyocytes. Myocardial injury increases cardiomyocyte proliferation3; however, it is clearly insufficient to completely regenerate the myocardium, and many strategies to enhance the weak regenerative response of the mammalian heart to injury are currently under investigation. The neonatal mammalian heart potentially possesses a higher regenerative capacity compared with the adult organ. In one study, cardiac regeneration was observed in 1-day-old neonatal mice after partial surgical resection.4 Using genetic fate mapping techniques, the researchers showed that the regenerated myocardium originated from preexisting cardiomyocytes proliferating in response to injury.4 This regenerative capacity was lost by day 7.4 Other studies have also pointed to an enhanced natural regenerative capacity in neonatal mice.5,6 In contrast to mammals, lower vertebrates such as Zebrafish retain the ability to regenerate their hearts throughout life. In the case of the Zebrafish, this natural ability is particularly robust as complete cardiac regeneration has been observed even when ≈20% of the ventricular myocardium was removed.7 The proliferation of partially dedifferentiated cardiomyocytes underlies this process.8 Specifically, cardiomyocytes that are adjacent to the site of injury break down their sarcomeres, express the embryonic cardiogenesis gene Gata4, and enter …

In vitro germination and direct shoot induction of Yeheb (Cordeauxia edulis Hemsl.)

‘Yeheb’ (Cordeauxia edulis Hemsl) is a multipurpose and evergreen shrub and endemic to southeastern corner of Ethiopia and Somalia. It is adapted to low and irregular rainfall and survives a very long dry season. It has enormous economic and food security role to the pastoralist of Somali in Ethiopia. However, the plant is threatened with extinction due to overexploitation and its’ poor natural regeneration capacity. In addition, ‘yeheb’ is usually reported having limited reproductive capacities and often have very specific and limited conditions for seed germination, flowering and seed shelf life. Therefore, to overcome these propagation challenges, an experiment was conducted with the aim of developing a protocol for the in vitro regeneration of ‘yeheb’ from cotyledonary node. The result of these studies revealed that seed was washed by 5% sodium hypochlorite for ten min in aseptic condition found to be more effective in surface sterilization. The sterilized seed cultured on half strength of Gamborg (B5) medium was found to be the most suitable medium for germination (26.67%).The highest shoot initiation percentage (89 % of explants produces shoots), number of shoots per explant and number of leaf per shoot were obtained from cotyledonary node explants cultured on Murashige and Skoog (MS) media supplemented with 2.00 mg. l-1 N6-benzylaminopurine (BAP) within nine weeks. While, the highest shoot length and shoot fresh weight were recorded from control (free BAP) and 6.00 mg. l-1 BAP, respectively. The highest shoot multiplication (4.56 number of shoot induced) and elongation (2.97cm) were obtained from the induced shoot were cut and placed on MS media supplemented with 2.00 mg. l 1BAP+6.00 mg. l-1of gibberellic acid (GA3) and free BAP+6.00 mg. l-1 of GA3, respectively. The elongated shoots were transferred to different media supplemented with various types and levels of hormones but none of them induced root. As a conclusion, this is the first attempt for direct in vitro regeneration of C. edulis and permissible result for cryopreservation.

A Fine Line Between Healing and Fibrosis

The liver’s microvascular endothelium lies at the crux of regeneration and fibrosis.

Produtos florestais não-madeiráveis e respectivo potencial de exploração sustentável, associados à remanescente florestal ripário do alto rio Paraná, Brasil

The results of a survey of non-timber forest products (NTFP) associated with tree species (CBH ≥ 15 cm) of riparian forest remnants in the upper Paraná river (Mata do Araldo) are presented. The species examined were ranked according to their potential value for sustainable exploitation (PVSE) of NTFP, applying the following information obtained from literature review: density, parts used, capacity for natural regeneration and growth, knowledge about reproductive biology and population dynamic, required processing and level of injury or toxicity. For a total of 58 species, 29 reached PVSE higher than 10, being considered of high potential for sustainable exploitation of NTFP. Among these, the most important were Inga vera and Lonchocarpus cultratus, with VPES = 14 as beekeeping, and with PVSE = 13, for ecological use, ornamental and food. In addition, Parapiptadenia rigida, also has PVSE = 13 as beekeeping and medicinal. The results show a promising basis for achieving goals of conservation and regional development, from sustainable alternative use of forest resources. In particular, the use of species as sources of medicinal, ecological, ornamental, beekeeping and biochemical resources was recorded as the primary vocation for the study area.

The regenerative capacity of zebrafish reverses cardiac failure caused by genetic cardiomyocyte depletion

Natural models of heart regeneration in lower vertebrates such as zebrafish are based on invasive surgeries causing mechanical injuries that are limited in size. Here, we created a genetic cell ablation model in zebrafish that facilitates inducible destruction of a high percentage of cardiomyocytes. Cell-specific depletion of over 60% of the ventricular myocardium triggered signs of cardiac failure that were not observed after partial ventricular resection, including reduced animal exercise tolerance and sudden death in the setting of stressors. Massive myocardial loss activated robust cellular and molecular responses by endocardial, immune, epicardial and vascular cells. Destroyed cardiomyocytes fully regenerated within several days, restoring cardiac anatomy, physiology and performance. Regenerated muscle originated from spared cardiomyocytes that acquired ultrastructural and electrophysiological characteristics of de-differentiation and underwent vigorous proliferation. Our study indicates that genetic depletion of cardiomyocytes, even at levels so extreme as to elicit signs of cardiac failure, can be reversed by natural regenerative capacity in lower vertebrates such as zebrafish.

Can Eucalyptus invade native forest fragments close to commercial stands?

Some Eucalyptus species are widely used as a plantation crop in tropical and subtropical regions. One reason for this is the diversity of end uses, but the main reason is the high level of wood production obtained from commercial plantings. With the advancement of biotechnology it will be possible to expand the geographical area in which eucalypts can be used as commercial plantation crops, especially in regions with current climatic restrictions. Despite the popularity of eucalypts and their increasing range, questions still exist, in both traditional planting areas and in the new regions: Can eucalypts invade areas of native vegetation, causing damage to natural ecosystems biodiversity? The objective of this study it was to assess whether eucalypts can invade native vegetation fragments in proximity to commercial stands, and what factors promote this invasive growth. Thus, three experiments were established in forest fragments located in three different regions of Brazil. Each experiment was composed of 40 plots (1 m 2 each one), 20 plots located at the border between the forest fragment and eucalypts plantation, and 20 plots in the interior of the forest fragments. In each experimental site, the plots were paired by two soil exposure conditions, 10 plots in natural conditions and 10 plots with soil exposure (no plant and no litter). During the rainy season, 2 g of eucalypts seeds were sown in each plot, including Eucalyptus grandis or a hybrid of E. urophylla × E. grandis, the most common commercial eucalypt species planted in the three region. At 15, 30, 45, 90, 180, 270 and 360 days after sowing, we assessed the number of seedlings of eucalypts and the number of seedlings of native species resulting from natural regeneration. Fifteen days after sowing, the greatest number of eucalypts seedlings (37 m −2) was observed in the plots with lower luminosity and exposed soil. Also, for native species, it was observed that exposed soil improved natural germination reaching the highest number of 163 seedlings per square meter. Site and soil exposure were the factors that have the greatest influence on seed germination of both eucalypt and native species. However, 270 days after sowing, eucalypt seedlings were not observed at any of the three experimental sites. The result shows the inability of eucalypts to adapt to condition outside of their natural range. However, native species demonstrated their strong capacity for natural regeneration in forest fragments under the same conditions where eucalypts were seeded.

Invited Commentary

Invited Commentary

Methodology for Location of Shorelines using 3D-GPS Positioning: A Case Study at Sauaçui Beach, Northeast Brazil

Many research studies have tried to improve the techniques for effective control of changes in coastal spaces caused by natural or human-induced phenomena. Such alterations modify the capacity for natural regeneration of beaches, and because of the growing population in these areas coastal management must pay close attention to the subject. The method used in this study case at Sauaçui Beach establishes a terrestrial digital model using topographic software fed by a georeferenced data bank generated by a three-dimensional global positioning system (GPS) whose vertical coordinates are referred to as tidal datum. The GPS technology can be used for the accommodation dynamic of the earth's crust of tectonic displacements. This method is able to identify the level curve equivalent to the maximum elevation of the wave run-up line, as well as the position of the waterline, during any stage of tidal elevation through curves of higher or lower levels of elevation, depending on the specific need of the study. Besides determining a baseline for future observations at Sauaçui Beach, this study allows us to evaluate the occurrence of alterations in the volume of sediments at the beach through differences among the generated land surfaces during different periods of time, as well as the risk of substantial variations in the shoreline position caused by eventual sea-level changes.

Responses of a fringing Cyperus papyrus L. swamp to changes in water level

Over a 9-year period (1993–2001), the land-water width of a papyrus fringe on the southern shore of Lake Naivasha, Kenya, varied between 40 and 60 m. Increases in width via rhizome spreading into open water followed the 1997/1998 El Niño flood when water depths rose by about 2 m. Germination of papyrus seeds also responded to water depth with a mean ± S.E. rate in experiments of 23 ± 6% after 21 days when water level was 5 cm below the sediment surface. No germination occurred when sediment was flooded or allowed to desiccate. Rhizome spreading from floating mats appeared to be favoured by deep water with seedling spread favoured on newly inundated, low-gradient slopes in shallow water. Although natural regenerative capacity was influenced by water depth, the height, density, biomass and chemical content of papyrus were not. Total average biomass along a land-water transect was 6950 ± 860 g m −2 which was large in relation to nutrient and mineral contents. Culms contained 0.47 ± 0.14% N and 0.06 ± 0.05% P and rhizomes 0.71 ± 0.21% and 0.10 ± 0.06%. Sediment underlying the swamp was aerobic and there were small land-water gradients in the BOD of swamp water and sediment. However, chemical gradients were weak compared with wider papyrus swamps elsewhere. Lake and swamp water mixed in the narrow fringe studied and residence times for organic matter may not have been long enough for organic material to mineralise before entering lake water.

The river Ganga of northern India: an appraisal of its geomorphic and ecological changes

The Ganga is the most important perennial river originating from Gangotri in the snow-bound Himalayas about 3,900 m above mean sea level. Gorging a distance of about 220 km in the Himalayas, it enters the plain at Hardwar and after meandering and braiding over a distance of about 2,525 km through the Indo-Gangetic plains, ultimately joins the Bay of Bengal. The course of this river has been changed due to: (i) subsurface geotectonic movement leading to change in slope of the deltaic plain and subsidence of the Bengal basin; (ii) changing pattern of water discharge with time; (iii) variations in sediment load. The environment of Ganga basin is also deteriorating with time due to severe natural episodes of periodic floods and storms as well as anthropogenic factors such as population growth, deforestation, agricultural activities, urbanisation, fertiliser and fossil fuel consumption and construction activities such as dams and bridges. All these have inconceivable adverse impacts on the health and natural regeneration capacity of the river basin. The presence of micropollutants in water and sediments of this river turns the system into being unsustainable to the biota. The present study synthesises the available information on the changes of its geological, geomorphological and ecological aspects and suggests some remedial measures to be adopted now and in future.

Sustainable development issues and strategies for Alberta's oil industry

This paper discusses the sustainable development issues for the Alberta oil industry and suggests strategies for its long-term survival. While oil and gas are finite resources, Alberta's massive non-conventional reserves are a virtual assurance that it can meet all the fossil fuel demands for Canada and its export market in the foreseeable future. This makes it a sustainable resource in practical terms. Despite its large economic contribution, this industry will face many challenges to remain viable over the next 50 years. Large investments will be required and it must improve its public consultation process and environmental record if it is to become sustainable. In recent years, stakeholder pressure, tougher regulations and better enforcement has made the industry more environmentally friendly, but its track record suggests that continued regulation will still be required. There is a growing realisation that sustainable development can no longer remain a low priority for those organisations with aspirations for long-term survival, and this makes it a bone fide strategic issue. Concern over environmental protection has become a critical issue for the industry, and must be addressed in terms of the natural regenerative capacity of the environment, and the legitimate need for an economically viable sector. As such, sustainable development inextricably links environmental protection with economics and stakeholder interests. In the longer term, competition from less polluting alternate fuels is likely to intensify and this will force contraction of the industry and a loss of market share. This smaller, more competitive environment of the future will likely favour those companies that can best integrate growth with a low cost strategy and environmental protection. As such, size is likely to be important insofar that it usually correlates with financial resources and the ability to achieve economies of scale.

Effects of Alginate Hydrogels and TGF-β1 on Human Dental Pulp Repair In Vitro

The objective of this study was to investigate the use of alginate hydrogels to present either exogenous or endogenous transforming growth factor (TGF)- g 1 to the dentin-pulp complex to signal reparative processes. Hydrogels were prepared, applied to cultured human tooth slices and the effects on tertiary dentinogenesis examined histologically. Both TGF- g 1-containing and acid-treated alginate hydrogels, but not untreated hydrogels, upregulated dentin matrix secretion and induced odontoblast-like cell differentiation with subsequent secretion of regular tubular dentin matrix on cut pulpal surfaces. It is concluded that TGF- g 1 can signal both induction of odontoblast-like cell differentiation and upregulation of their matrix secretion in the human dentin-pulp complex. Alginate hydrogels provide an appropriate matrix in which dental regeneration can take place and may also be useful for delivery of growth factors, including TGF- g s, to enhance the natural regenerative capacity of the dental pulp.

A model for evaluating injectable bone replacements in the vertebrae of sheep: radiological and histological study.

We developed a bone-defect model in the vertebrae of sheep. Forty four cavities were prepared in the upper lumbar vertebrae of 11 sheep using a biopsy trocar via a posterior-lateral extracanal percutaneous route and the location was monitored by radiology with a brilliance amplifier. The cavities were 3 mm in diameter. The histological study was performed on 15 cavities which were left empty to give reference data for the model. Histological and histomorphometry results showed that 67% of the surface area of the empty cavities was still empty 3 months after their preparation. Thus, the natural regenerative capacity of vertebral trabecular bone is limited. We performed preliminary percutaneous injections of polymethylmethacrylate (PMMA) and nacre powder to assess whether this bone-defect model would be suitable for further studies on bone repair. Cavities were successfully filled with nacre powder (21 cavities) or PMMA (8 cavities) while monitoring the process by interventional radiology. The experimental sheep vertebrae defect system is reproducible and appears to be a suitable model for testing injectable biomaterials for treating bone loss.

Setting priorities for conservation of the conifer genetic resources of British Columbia

Gene conservation of native conifer species in British Columbia is considered necessary primarily to safeguard the future evolutionary potential of species to climate change, new biotic challenges and for commercial genetic improvement programs. The tactical options include: (i) maintaining existing protected areas, (ii) creating new reserves for in situ management, and (iii) ex situ collections of various types.A two-part strategy is presented, with emphasis on technical justifications, for the conservation of conifer tree genetic resources of 23 British Columbia species. Part I is a survey of the frequency of each species in current land reserves in BC. Part II outlines an approach that will aid in setting priorities for additional gene conservation activities for specific species. This process attempts to use information on: (i) levels of in situ protection, (ii) the status of each species in current provenance research and breeding programs, and (iii) the relative capabilities for natural regeneration for each species.Representation of the 23 native conifer species in the current network of protected areas is generally complete. For instance, western hemlock is under little threat, as extensive ex situ collections are in field tests; it is well protected in the current reserve network, and it has a great capacity for natural regeneration. At the other extreme, whitebark pine has no ex situ collections made to date, needs additional protection in some ecoregions of the province, and generally has poor natural regeneration potential. While implementation of our strategy will be an ongoing process (i.e. updating information from both new and old in situ reserves, and setting new priorities among species), several immediate issues have been noted. These include; (i) follow-up work in the area of population sampling for ex situ collections, (ii) "ground truthing" of current reserves where data are weak, and (iii) examining the merit of certain populations not located in BC (as they could be as important as those currently protected in BC).For the future, various broad management questions will need to be resolved, such as: (i) whether existing reserves will perpetuate the various gene pools, and what management will be appropriate for such areas, (ii) the impact of pollen migration from genetically improved production stands on reserve stands, and (iii) the role of commercially improved stands and the breeding populations themselves to meet gene conservation objectives. Key words: gene conservation, native conifers, British Columbia, tree genetics

Role of non-timber forest products in the economy of peripheral communities of knuckles national wilderness area of Sri Lanka: A farming systems approach

The Knuckles range of forests has been identified as a unique biological resource in Sri Lanka with much biodiversity. It is also important as a watershed which feeds the Mahaweli reservoir system. Having considered the present hazardous land-use practices such as cardamum production and shifting cultivation, the Knuckles range has been declared a national wilderness area. The Forest Department is in the process of preparing the management plan for the area. There are about 48 villages in the vicinity of the forest. This study attempts to estimate the composition of income in the peripheral communities, ticularly the extraction of non-timber forest products (NTFP) from this range of forests. Data were collected using structured questionnaires from 60 households in three villages in the vicinity of the forest. The rural economy is described using a farming systems approach and the net income contributed by each activity in the farming system was estimated. Results show that nine components of the farming system use resources from the village and the forest, with at least 47 plant species used by the villagers for different purposes. Cardamum production and shifting cultivation contribute significantly to the total income of the household, but the majority of households in the study depend upon forest resources to supply some portion of their income. Nevertheless, the monetary value of the annual income generated by NTFP is much lower than income from either cardamum production or shifting cultivation. If cardamum production and shifting cultivation are to be restricted under the conservation program, there could be additional pressure put on NTFP. Therefore, we suggest a study of the natural regen-eration capacity of selected NTFP; such information should be used in finalizing the management plan in the Knuckles range of forests.

Studies on Regeneration Capacity of Hibiscus schizopetalous L Cuttings Under Intermittent Mist, as Influenced by Maturity of Wood and Indolebutyric Acid

Regenerative capacity of maturity of Hibiscus schizopetalous cuttings was studied under intermittent mist with the aid of IBA at 4000 ppm. Treated sub-terminal, semi-hardwood and hardwood cuttings induced 100 per cent rooting; it was 60 per cent in terminal cuttings. The natural regenerative capacity of semi. -hardwood cuttings was highest. Treated cuttings of all the four types produced signifi- cantly very high number of roots than untreated ones. Treated torminal and sub-terminal cuttings produced smaller roots than those of untreated. However, treated and untreated hardwood cuttings produced longer roots. Untreated cuttings produced roots from their very basal cut portion whereas treated cuttings produced roots covering 12 to 40mm area in length on the cutting. Under intermittent mist, semi-hardwood cuttings proved superior even without IBA treatment to terminal, sub-terminal and hardwood cuttings. Terminal cuttings showed poor response to niist as well as IBA treatment.

Site Specific Burial of Unfixated Flue Gas Sludge

Detailed studies of unfixated Flue Gas Desulfurization Sludge are presented together with the prevailing edaphic conditions of a proposed site. Considering the geological-stratigraphic characteristics of the site and the pedological values of the soils, it was concluded that about 0.028% of the leachates will reach the closest aquifer through lateral migration. This quantity is insignificant relative to the present ground-water quality which exceeds Public Health Standards for Drinking Water. Ion exchange capacity calculations of fine clays underlying the burial site provide 10 yr saturation of these strata would occur, not considering its natural regenerative capacity. Economic comparisons indicate the cost effectiveness of burying unfixated sludge material. Thorough investigations of the burial site should be carried out since the FGD sludge could be feasibly buried without fixation.

Regeneration research in the Soviet Union

AbstractOver the past 20 years Soviet research in regeneration has undergone a shift in emphasis from work on amphibians to mammals. In that period several distinct schools of thought have arisen, and often there has been considerable controversy as to the nature of certain regenerative processes. At present most mammalian tissues and organs are being studied with respect to natural regenerative capacity and means of stimulating further regeneration. The most striking results have been obtained in the areas of muscle and bone regeneration. Progress in other areas has been less spectacular. Considerable effort has been put into devising means of regenerating functional tissue from pathologically changed or irradiated organs. The field of regeneration research in the Soviet Union is quite highly organized and includes a relatively large number of workers. Progress has, to some extent, been impeded by shortages of equipment and biochemical preparations.