scholarly journals Molybdenum in forests-A short review

2020 ◽  
Keyword(s):  
Tropical Forests ◽  
Boreal Forests ◽  
Forest Ecosystems ◽  
Short Review ◽  
Limiting Factor ◽  
N Fixation ◽  
Biological Processes ◽  
Tree Leaves ◽  
Predominant Role ◽  
Throughfall Deposition

<p>This review deals with the importance of molybdenum (Mo) in nitrogen fixation in forests as well as the distribution of Mo in the various components of a forest ecosystems and its cycling. With regard to nitrogen (N) fixation in tropical forests, the limiting factor is the availability of phosphorus in soils. For the temperate and boreal forests, the Mo availability is more crucial. The canopies of the tropical forests retain Mo from precipitation, which is used for N fixation by the microorganisms living there. There is also retention of Mo in throughfall deposition by the canopy of temperate forests but so far, there has been no information as to the biological processes taking place there. The contribution of Mo in bulk and throughfall deposition in the Mo cycling is more important than once thought. There is great variability in Mo concentrations in tree leaves either conifers or broadleaves and even within the same species. In soils, the organic matter, clay and the oxides of Al, Fe and Mn play a predominant role in preventing Mo from leaching.</p>

scholarly journals Methane emissions from boreal and tropical forest ecosystems derived from in-situ measurements

2007 ◽  
Vol 7 (5) ◽  
pp. 14011-14039 ◽  
Author(s):  
V. Sinha ◽  
J. Williams ◽  
P. J. Crutzen ◽  
J. Lelieveld
Keyword(s):  
Boreal Forest ◽  
Tropical Forest ◽  
Tropical Forests ◽  
Forest Ecosystem ◽  
Boreal Forests ◽  
Forest Ecosystems ◽  
Global Budget ◽  
Night Time ◽  
Mixing Ratios ◽  
The Impact

Abstract. Methane is a climatologically important greenhouse gas, which plays a key role in regulating water vapour in the stratosphere and hydroxyl radicals in the troposphere. Recent findings that vegetation emits methane have stimulated efforts to ascertain the impact of this source on the global budget. In this work, we present the results of high frequency (ca. 1 min−1) methane measurements conducted in the boreal forests of Finland and the tropical forests of Suriname, in April–May, 2005 and October 2005 respectively. The measurements were performed using a gas chromatograph – flame ionization detector (GC-FID). The average of the median mixing ratios during a typical diel cycle were 1.83 μmol mol−1 and 1.74 μmol mol−1 for the boreal forest ecosystem and tropical forest ecosystem respectively, with remarkable similarity in the time series of both the boreal and tropical diel profiles. Night time methane emission flux of the boreal forest ecosystem, calculated from the increase of methane during the night and measured nocturnal boundary layer heights yields a flux of (3.62±0.87)×1011 molecules cm−2 s−1(or 45.5±11 Tg CH4 yr−1 for global boreal forest area). This is a source contribution of circa 8% of the global methane budget. These results highlight the importance of the boreal and tropical forest ecosystems for the global budget of methane. The results are also discussed in the context of recent work reporting high methane mixing ratios over tropical forests using space borne near infra-red spectroscopy measurements.

scholarly journals Silencing Antibiotic Resistance with Antisense Oligonucleotides

Biomedicines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 416
Author(s):  
Saumya Jani ◽  
Maria Soledad Ramirez ◽  
Marcelo E. Tolmasky
Keyword(s):  
Antibiotic Resistance ◽  
Nucleic Acids ◽  
Antisense Oligonucleotides ◽  
Bacterial Infections ◽  
Genetic Disorders ◽  
Antibiotic Resistance Genes ◽  
Short Review ◽  
Rnase H ◽  
Biological Processes ◽  
Locked Nucleic Acids

Antisense technologies consist of the utilization of oligonucleotides or oligonucleotide analogs to interfere with undesirable biological processes, commonly through inhibition of expression of selected genes. This field holds a lot of promise for the treatment of a very diverse group of diseases including viral and bacterial infections, genetic disorders, and cancer. To date, drugs approved for utilization in clinics or in clinical trials target diseases other than bacterial infections. Although several groups and companies are working on different strategies, the application of antisense technologies to prokaryotes still lags with respect to those that target other human diseases. In those cases where the focus is on bacterial pathogens, a subset of the research is dedicated to produce antisense compounds that silence or reduce expression of antibiotic resistance genes. Therefore, these compounds will be adjuvants administered with the antibiotic to which they reduce resistance levels. A varied group of oligonucleotide analogs like phosphorothioate or phosphorodiamidate morpholino residues, as well as peptide nucleic acids, locked nucleic acids and bridge nucleic acids, the latter two in gapmer configuration, have been utilized to reduce resistance levels. The major mechanisms of inhibition include eliciting cleavage of the target mRNA by the host’s RNase H or RNase P, and steric hindrance. The different approaches targeting resistance to β-lactams include carbapenems, aminoglycosides, chloramphenicol, macrolides, and fluoroquinolones. The purpose of this short review is to summarize the attempts to develop antisense compounds that inhibit expression of resistance to antibiotics.

Is temperature still the most limiting factor for growth in northern boreal forests?

The Holocene ◽  
2021 ◽  
pp. 095968362110116
Author(s):  
Jeroen DM Schreel
Keyword(s):  
Tree Ring ◽  
Boreal Forests ◽  
Ring Width ◽  
Temperature Fluctuations ◽  
Limiting Factor ◽  
Tree Ring Width ◽  
Climate Reconstructions ◽  
Latewood Density

Over the last few decades – at a range of northern sites – changes in tree-ring width and latewood density have not followed mean summertime temperature fluctuations. This discrepancy sharply contrasts an earlier correlation between those variables. As the origin of this inconsistency has not been fully deciphered, questions have emerged regarding the use of tree-ring width and latewood density as a proxy in dendrochronological climate reconstructions. I suggest that temperature is no longer the most limiting factor in certain boreal areas, which might explain the observed divergence.

scholarly journals Evaluating the Performance of a Forest Succession Model to Predict the Long-Term Dynamics of Tree Species in Mixed Boreal Forests Using Historical Data in Northern Ontario, Canada

Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1181
Author(s):  
Guy R. Larocque ◽  
F. Wayne Bell
Keyword(s):  
Populus Tremuloides ◽  
Boreal Forests ◽  
Forest Ecosystems ◽  
Forest Succession ◽  
Regional Scale ◽  
Abies Balsamea ◽  
Forest Growth ◽  
Northern Ontario ◽  
Phase Dynamics

Environmental concerns and economic pressures on forest ecosystems have led to the development of sustainable forest management practices. As a consequence, forest managers must evaluate the long-term effects of their management decisions on potential forest successional pathways. As changes in forest ecosystems occur very slowly, simulation models are logical and efficient tools to predict the patterns of forest growth and succession. However, as models are an imperfect representation of reality, it is desirable to evaluate them with historical long-term forest data. Using remeasured tree and stand data from three data sets from two ecoregions in northern Ontario, the succession gap model ZELIG-CFS was evaluated for mixed boreal forests composed of black spruce (Picea mariana [Mill.] B.S.P.), balsam fir (Abies balsamea [L.] Mill.), jack pine (Pinus banksiana L.), white spruce (Picea glauca [Moench] Voss), trembling aspen (Populus tremuloides Michx.), white birch (Betula papyrifera Marsh.), northern white cedar (Thuja occidentalis L.), American larch (Larix laricina [Du Roi] K. Koch), and balsam poplar (Populus balsamefera L.). The comparison of observed and predicted basal areas and stand densities indicated that ZELIG-CFS predicted the dynamics of most species consistently for periods varying between 5 and 57 simulation years. The patterns of forest succession observed in this study support gap phase dynamics at the plot scale and shade-tolerance complementarity hypotheses at the regional scale.

scholarly journals The evolution of natural floodplain forests in South Moravia between 1973 and 2005

2008 ◽  
Vol 54 (No. 8) ◽  
pp. 340-354 ◽  
Author(s):  
P. Unar ◽  
P. Šamonil
Keyword(s):  
Forest Ecosystems ◽  
Woody Species ◽  
Limiting Factor ◽  
Herb Layer ◽  
Ellenberg Indicator Values ◽  
Indicator Values ◽  
Management Measures ◽  
South Moravia ◽  
The Impact ◽  
The Given

Since the mid-1970’s, the landscape around the confluence of the Morava and Dyje rivers has undergone substantial changes related to the drop of water table caused by water management measures undertaken on both ri-vers. Periodical spring floods are among the phenomena lost due to ameliorations. In this study, the reaction of forest ecosystems to the decrease in soil moisture is assessed on the basis of changes in species composition of the herb layer as well as of the known requirements of individual recorded taxa and the entire herb synusiae for the water content of soils. The results confirm that the species with the greatest demand for water disappear over time. The tendency of decreasing Ellenberg indicator values of the herb layers within the phytocoenological relevés is obvious also with the consideration of the influence of different numbers of species recorded on the same plots in different years of the survey. The changes are most visible in the dampest habitats, while elevated sites, so-called “hrudy”, tend to be most stable. The intensity of vegetation changes increases in direct proportion to the altitude of the sites. The process of changes in some habitats caused by the alteration of the water regime has to be separated from the changes in the vegetation structure, which are easier to observe optically. The limiting factor of their development in the given conditions is the forest wildlife. After the elimination of wildlife’s influence, the woody species synusia differentiates in height. A qualitative shift is represented by the recession of the formerly dominant <I>Quercus robur</I> on the main level, and its gradual replacement by other species. The impact of changes going on in the woody synusia on selected characteristics of the herb layer are included in the analyses.

scholarly journals Dental Pulp Regeneration: Insights from Biological Processes

2017 ◽  
Vol 20 (1) ◽  
pp. 10-16
Author(s):  
Cristina Retana-Lobo DDS, MSD
Keyword(s):  
Tissue Engineering ◽  
Dental Pulp ◽  
Short Review ◽  
Biological Processes ◽  
Pulp Tissue ◽  
Pulp Regeneration ◽  
Dental Tissues ◽  
Current State ◽  
Signaling Mechanisms ◽  
Dental Pulp Tissue

One of the major approaches on dentistry research in this century is the development of biological strategies (tissue engineering) to regenerate/ biomineralize lost dental tissues. During dentin-pulp regeneration, the interaction between stem cells, signaling molecules, biomaterials and the microenvironment in the periapical area drives the process for dental pulp tissue engineering.  Understanding the signaling mechanisms and interactions involved with the biological process for the formation of a new tissue, is essential. The knowledge of the micro-environment is the key for the application of tissue engineering.  The present article is a short review of the current state of this topic, with the purpose of showing insights of pulp regeneration.

scholarly journals Good Agreement Between Modeled and Measured Sulfur and Nitrogen Deposition in Europe, in Spite of Marked Differences in Some Sites

2021 ◽  
Vol 9 ◽  
Author(s):  
Aldo Marchetto ◽  
David Simpson ◽  
Wenche Aas ◽  
Hilde Fagerli ◽  
Karin Hansen ◽  
...  
Keyword(s):  
Nitrogen Deposition ◽  
Forest Ecosystems ◽  
Tree Canopy ◽  
Atmospheric Nitrogen ◽  
Eulerian Model ◽  
Deposition Amount ◽  
Pollutant Deposition ◽  
Negative Impacts ◽  
Throughfall Deposition ◽  
Good Agreement

Atmospheric nitrogen and sulfur deposition is an important effect of atmospheric pollution and may affect forest ecosystems positively, for example enhancing tree growth, or negatively, for example causing acidification, eutrophication, cation depletion in soil or nutritional imbalances in trees. To assess and design measures to reduce the negative impacts of deposition, a good estimate of the deposition amount is needed, either by direct measurement or by modeling. In order to evaluate the precision of both approaches and to identify possible improvements, we compared the deposition estimates obtained using an Eulerian model with the measurements performed by two large independent networks covering most of Europe. The results are in good agreement (bias &lt;25%) for sulfate and nitrate open field deposition, while larger differences are more evident for ammonium deposition, likely due to the greater influence of local ammonia sources. Modeled sulfur total deposition compares well with throughfall deposition measured in forest plots, while the estimate of nitrogen deposition is affected by the tree canopy. The geographical distribution of pollutant deposition and of outlier sites where model and measurements show larger differences are discussed.

scholarly journals Dental Pulp Regeneration: Insights from Biological Processes

2017 ◽  
Vol 20 (1) ◽  
pp. 10-16
Author(s):  
Cristina Retana-Lobo DDS, MSD
Keyword(s):  
Tissue Engineering ◽  
Dental Pulp ◽  
Short Review ◽  
Biological Processes ◽  
Pulp Tissue ◽  
Pulp Regeneration ◽  
Dental Tissues ◽  
Current State ◽  
Signaling Mechanisms ◽  
Dental Pulp Tissue

One of the major approaches on dentistry research in this century is the development of biological strategies (tissue engineering) to regenerate/ biomineralize lost dental tissues. During dentin-pulp regeneration, the interaction between stem cells, signaling molecules, biomaterials and the microenvironment in the periapical area drives the process for dental pulp tissue engineering.  Understanding the signaling mechanisms and interactions involved with the biological process for the formation of a new tissue, is essential. The knowledge of the micro-environment is the key for the application of tissue engineering.  The present article is a short review of the current state of this topic, with the purpose of showing insights of pulp regeneration.

Tropical Forests in Prehistory, History, and Modernity

2019 ◽  
Author(s):  
Patrick Roberts
Keyword(s):  
Tropical Forest ◽  
Tropical Forests ◽  
Forest Ecosystems ◽  
Global Scale ◽  
Modern World ◽  
Human Adaptation ◽  
Popular Discourse ◽  
Urban Networks ◽  
Human Interactions

In popular discourse, tropical forests are synonymous with 'nature' and 'wilderness'; battlegrounds between apparently pristine floral, faunal, and human communities, and the unrelenting industrial and urban powers of the modern world. It is rarely publicly understood that the extent of human adaptation to, and alteration of, tropical forest environments extends across archaeological, historical, and anthropological timescales. This book is the first attempt to bring together evidence for the nature of human interactions with tropical forests on a global scale, from the emergence of hominins in the tropical forests of Africa to modern conservation issues. Following a review of the natural history and variability of tropical forest ecosystems, this book takes a tour of human, and human ancestor, occupation and use of tropical forest environments through time. Far from being pristine, primordial ecosystems, this book illustrates how our species has inhabited and modified tropical forests from the earliest stages of its evolution. While agricultural strategies and vast urban networks emerged in tropical forests long prior to the arrival of European colonial powers and later industrialization, this should not be taken as justification for the massive deforestation and biodiversity threats imposed on tropical forest ecosystems in the 21st century. Rather, such a long-term perspective highlights the ongoing challenges of sustainability faced by forager, agricultural, and urban societies in these environments, setting the stage for more integrated approaches to conservation and policy-making, and the protection of millennia of ecological and cultural heritage bound up in these habitats.

scholarly journals Experimental approaches for addressing fundamental biological questions in living, functioning cells with single molecule precision

Open Biology ◽  
2012 ◽  
Vol 2 (6) ◽  
pp. 120090 ◽  
Author(s):  
Tchern Lenn ◽  
Mark C. Leake
Keyword(s):  
Single Molecule ◽  
Molecular Basis ◽  
Life Sciences ◽  
Short Review ◽  
Living Cells ◽  
Cellular Systems ◽  
Biological Processes ◽  
Sensitivity Level ◽  
Experimental Approaches ◽  
The Impact

In recent years, single molecule experimentation has allowed researchers to observe biological processes at the sensitivity level of single molecules in actual functioning, living cells, thereby allowing us to observe the molecular basis of the key mechanistic processes in question in a very direct way, rather than inferring these from ensemble average data gained from traditional molecular and biochemical techniques. In this short review, we demonstrate the impact that the application of single molecule bioscience experimentation has had on our understanding of various cellular systems and processes, and the potential that this approach has for the future to really address very challenging and fundamental questions in the life sciences.

Sign in / Sign up

Export Citation Format

Share Document