Live Roots Research Articles

Pavel A. Florenskij. Organizzazione dello spazio, arte, cultura come unità

In the early decades of the 20th century, the reflection about the deyatel’ kul’tury is one of the most important chapters of the russian philosophy: the conception of space and time proposed by Pavel A. Florenskij – as his result in the teatrise Analiz prostranstvennosti i vremeni – is a relevant part of it. Science, philosophy and art find their roots in life, and the study of the space is the start to understand themselves. Deyatel’ kul’tury, according Florenskij, does culture: he assumes the task of planting border’s poles, outlining the shortest paths through a system of isopotential lines. Through references to the debate between Symbolists, in the Analiz we can read in a new way the origin of sculpture, theatre, cinema, paint, poetry: the organization of the space can reach man’s consciousness, but the space already exists, as exists the life itself in which the art has its roots.

Fluorescent in situ visualization of sterols in Arabidopsis roots

Sterols are eukaryotic membrane components with crucial roles in diverse cellular processes. Elucidation of sterol function relies on development of tools for in situ sterol visualization. Here we describe protocols for in situ sterol localization in Arabidopsis thaliana root cells, using filipin as a specific probe for detection of fluorescent filipin-sterol complexes. Currently, filipin is the only established tool for sterol visualization in plants. Filipin labeling can be performed on aldehyde-fixed samples, largely preserving fluorescent proteins and being compatible with immunocytochemistry. Filipin can also be applied for probing live cells, taking into account the fact that it inhibits sterol-dependent endocytosis. The experimental procedures described are designed for fluorescence detection by confocal laser-scanning microscopy with excitation of filipin-sterol complexes at 364 nm. The protocols require 1 d for sterol covisualization with fluorescent proteins in fixed or live roots and 2 d for immunocytochemistry on whole-mount roots.

Pre- and postnatal determinants of childhood body size: cohort and sibling analyses

Growing evidence suggests obesity may have its roots in early life but it is still uncertain whether prenatal factors operate primarily though altering early infant growth. It is also still unclear if rapid growth during selected time periods is more important than other time periods in predicting future body size. Using prospectively collected data on 20,523 participants born from 1959 to 1966 (10,327 boys; 10,196 girls) of the Collaborative Perinatal Project, we investigated the associations between pre- and postnatal factors and childhood body size at age 7 years and compared these associations across linear, logistic and quantile regression models. Maternal body mass index (BMI), maternal pregnancy weight gain, birth weight and postnatal weight change for three time periods (birth to 4 months; 4-12 months; 1-4 years) were all positively and independently associated with BMI at age 7 years. Rapid growth during each time period had a similar association BMI at age 7 years. For example, a 10-percentile increase in weight increased the probability of being overweight at age 7 years by approximately two-fold regardless of time period (OR = 1.8-2.2 for boys and girls). Using same-sex siblings (n = 571 boy sets; n = 651 girl sets) from the same cohort, we observed that siblings with higher BMI at age 7 years than their same-sex siblings were more likely to have higher maternal pregnancy weight gain, higher maternal pre-pregnancy BMI, higher birth weight and increased rate of weight gain during the three time periods. These consistent findings both from the overall cohort and the sibling analyses suggest that there are multiple, rather than specific critical periods of influence shaping childhood body size.

Advances in 15N-tracing experiments: new labelling and data analysis approaches

To obtain an in-depth understanding of soil nitrogen dynamics, it is necessary to quantify a variety of simultaneously occurring gross nitrogen transformation processes. In order to do so, most studies apply 15N in a disturbed soil-microbial-root system and quantify gross rates based on the principles of 15N isotope dilution. However, this approach has several shortcomings. First, studying disturbed soil provides only limited information on in situ soil nitrogen dynamics. Secondly, the analytical data analysis allows the quantification of total production and consumption rates of the labelled pool, but does not provide information on process-specific transformation rates. Combining in situ 15N isotope labelling over 1-2weeks with numerical data analysis allows determining process-specific gross nitrogen transformations in undisturbed soils under field conditions in the presence of live roots and their associated microbial communities. This has the potential to increase our understanding of nitrogen dynamics in the soil environment.

Relationships among precipitation regime, nutrient availability, and carbon turnover in tropical rain forests

The effect of high precipitation regime in tropical forests is poorly known despite indications of its potentially negative effects on nutrient availability and carbon (C) cycling. Our goal was to determine if there was an effect of high rainfall on nitrogen (N) and phosphorous (P) availability and indexes of C cycling in lowland tropical rain forests exposed to a broad range of mean annual precipitation (MAP). We predicted that C turnover time would increase with MAP while the availability of N and P would decrease. We studied seven Neotropical lowland forests covering a MAP range between 2,700 and 9,500 mm. We used radiocarbon (∆(14)C) from the atmosphere and respired from soil organic matter to estimate residence time of C in plants and soils. We also used C, N, and P concentrations and the stable isotope ratio of N (δ(15)N) in live and dead plant tissues and in soils as proxies for nutrient availability. Negative δ(15)N values indicated that the wettest forests had N cycles that did not exhibit isotope-fractionating losses and were potentially N-limited. Element ratios (N:P and C:P) in senescent leaves, litter, and live roots showed that P resorption increased considerably with MAP, which points towards increasing P-limitation under high MAP regimes. Soil C content increased with MAP but C turnover time only showed a weak relationship with MAP, probably due to variations in soil parent material and age along the MAP gradient. In contrast, comparing C turnover directly to nutrient availability showed strong relationships between C turnover time, N availability (δ(15)N), and P availability (N:P) in senescent leaves and litter. Thus, an effect of MAP on carbon cycling appeared to be indirectly mediated by nutrient availability. Our results suggest that soil nutrient availability plays a central role in the dynamic of C cycling in tropical rain forests.

Response of “Alamo” switchgrass tissue chemistry and biomass to nitrogen fertilization in West Tennessee, USA

Switchgrass (Panicum virgatum) is a perennial, warm-season grass that has been identified as a potential biofuel feedstock over a large part of North America. We examined above- and belowground responses to nitrogen fertilization in “Alamo” switchgrass grown in West Tennessee, USA. The fertilizer study included a spring and fall sampling of 5-year old switchgrass grown under annual applications of 0, 67, and 202kgNha−1 (as ammonium nitrate). Fertilization changed switchgrass biomass allocation as indicated by root:shoot ratios. End-of-growing season root:shoot ratios (mean±SE) declined significantly (P≤0.05) at the highest fertilizer nitrogen treatment (2.16±0.08, 2.02±0.18, and 0.88±0.14, respectively, at 0, 67, and 202kgNha−1). Fertilization also significantly increased above- and belowground nitrogen concentrations and decreased plant C:N ratios. Data are presented for coarse live roots, fine live roots, coarse dead roots, fine dead roots, and rhizomes. At the end of the growing season, there was more carbon and nitrogen stored in belowground biomass than aboveground biomass. Fertilization impacted switchgrass tissue chemistry and biomass allocation in ways that potentially impact soil carbon cycle processes and soil carbon storage.

Impervious and pervious pavements increase soil CO 2 concentrations and reduce root production of American sweetgum ( Liquidambar styraciflua)

Mature trees with large canopies help reduce problems of excessive heat and surface runoff in urban areas through shading, transpirational cooling, and interception and absorption of precipitation. Trees in paved impervious areas often suffer from a poor root zone environment. The objective of this experiment was to test if use of pervious concrete could be more beneficial for root growth and consequently a better alternative towards preserving existing mature trees during urban development. We measured root activity through CO 2 flux, and also measured root production of American sweetgum under impervious concrete, pervious concrete and no pavement conditions (control). Soil under impervious concrete had lower oxygen concentrations than soil under pervious concrete and control treatments, particularly under wet conditions. Soil under pervious concrete had a 0.020 m 3 m −3 (2% volumetric water content (VWC)) greater volumetric water content than soils paved with impervious concrete. Soil CO 2 efflux rates and soil CO 2 concentrations were extremely high under both concrete treatments. Standing live root length at the end of the experiment was greater under the control treatment than under both concrete treatments and these changes in root production were likely due to high soil CO 2 concentrations under both pervious and impervious concrete. The soil type at our site, which is a Ships clay with a very low permeability rate, may have limited CO 2 exchange through the pervious pavement. On this heavy clay soil, pervious concrete did not convey any measurable root growth benefits over impervious concrete.

Effects of cultivation conditions on the uptake of arsenite and arsenic chemical species accumulated by Pteris vittata in hydroponics

The physiological responses of the arsenic-hyperaccumulator, Pteris vittata, such as arsenic uptake and chemical transformation in the fern, have been investigated. However, a few questions remain regarding arsenic treatment in hydroponics. Incubation conditions such as aeration, arsenic concentration, and incubation period might affect those responses of P. vittata in hydroponics. Arsenite uptake was low under anaerobic conditions, as previously reported. However, in an arsenite uptake experiment, phosphorous (P) starvation-dependent uptake of arsenate was observed under aerobic conditions. Time course-dependent analysis of arsenite oxidation showed that arsenite was gradually oxidized to arsenate during incubation. Arsenite oxidation was not observed in any of the control conditions, such as exposure to a nutrient solution or to culture medium only, or with the use of dried root; arsenite oxidation was only observed when live root was used. This result suggests that sufficient aeration allows the rhizosphere system to oxidize arsenite and enables the fern to efficiently take up arsenite as arsenate. X-ray absorption near edge structure (XANES) analyses showed that long-duration exposure to arsenic using a hydroponic system led to the accumulation of arsenate as the dominant species in the root tips, but not in the whole roots, partly because up-regulation of arsenate uptake by P starvation of the fern was caused and retained by long-time incubation. Analysis of concentration-dependent arsenate uptake by P. vittata showed that the uptake switched from a high-affinity transport system to a low-affinity system at high arsenate concentrations, which partially explains the increased arsenate abundance in the whole root.

Islam, Adat, and the State: Matrifocality in Aceh Revisited

Matrifocality has been a rooted tradition in the social history of the community in Aceh. The principles of matrifocality have also affected on how women are positioned in the community, and the socio-gender relation within the community. The fact that Aceh has strongly associated to the Islamic values that claimed to support the paternal traditions. Apparently, the Islamic values and the local matrifocality practices juxtaposed through the roles of adat, which considered as inseparable to Islamic law or teaching, or in local term known as zat ngeun sifeut. Another point in revisiting matrifocality in Aceh in Aceh is an examination of how gender state ideology, particularly during the New Order Regime disregarded some local gender practices across some ethnics in the archipelago. Meanwhile, the state also hegemonied and promoted particular gender state ideology such as state ibuism. Nonetheless, the modernity and social changes have also contributed to the shifting of some matrifocality practices in contemporary Acehnese society. However, since the matrifocality has a strong root in the social life of the community, the principles of the matrifocality still survived until currently, although it transformed into ‘new matrifocality’ practices.

Search for a Methanopyrus-proximal last universal common ancestor based on comparative-genomic analysis

The origin of life is a long-standing mystery puzzling many people. This mystery possesses not only philosophical but also important biological significance. To unveil this mystery, the searches for the root of life, or the last universal common ancestor (LUCA), based on comparative-genomic analysis have been intensively performed on rRNAs, tRNAs and proteins sequences. The current search pointed to a Methanopyrus-proximal LUCA, which opens up the reconstruction of Lucan biology and helps to delineate the evolutionary pathways.

Measuring and modeling the spectrum of fine‐root turnover times in three forests using isotopes, minirhizotrons, and the Radix model

Fine root (<2 mm) cycling rates are important for understanding plant ecology and carbon fluxes in forests, but they are difficult to determine and remain uncertain. This paper synthesizes minirhizotron and isotopic data and a root model and concludes that (1) fine roots have a spectrum of turnover times ranging from months to many years and (2) the mean age of live root biomass (A) and the mean age of roots when they die (i.e., their turnover time (τ)) are not equal. We estimated A and τ of fine roots in three forests using the root model Radix. For short‐lived roots, we constrained τ with existing minirhizotron data; for long‐lived roots, we used new radiocarbon measurements of roots sampled by diameter size class and root branch order. Long‐lived root pools had site mean τ of 8–13 y and 5–9 y when sampled by diameter and branch order, respectively. Mean turnover times across sites were in general not significantly different as a function of branch‐order, size class, or depth. Our modeling results indicate that ∼20% of fine root biomass has turnover times of about a year, and ∼80% has decadal turnover times. This partitioning is reflected in our predicted mean ages of ∼9 y and turnover times of ∼3 y. We estimate that fine root mortality contributes between 38 and 104 g C m−2 y−1 to soil in these forests. These estimates are 20 to 80% of previous estimates in these and similar forests, in part because we explicitly account for the large portion of fine‐root biomass with decadal cycling rates. Our work shows that both fast and slow cycling roots must be modeled jointly to account for the heterogeneous nature of fine‐root dynamics.

Effects of water and nutrient availability on fine root growth in eastern Amazonian forest regrowth, Brazil

*Fine root dynamics is widely recognized as an important biogeochemical process, but there are few data on fine root growth and its response to soil resource availability, especially for tropical forests. *We evaluated the response of fine root dynamics to altered availability of soil water and nutrients in a 20-yr-old forest regrowth in eastern Amazonia. In one experiment the dry season reduction in soil moisture was alleviated by irrigation. In the other experiment, nutrient supply was reduced by litter removal. We used the ingrowth core technique to measure fine root mass growth, length growth, mortality and specific root length. *Dry-season irrigation had no significant effect on mass and length of live and dead roots, whereas litter removal reduced mass and length of live roots. For both irrigation and litter removal experiments, root growth was significantly greater in the dry season than in the wet season. *Increased root growth was associated with decreased soil water availability. However, root growth did not increase in response to nutrient reduction in litter removal plots. Overall, our results suggest that belowground allocation may differ according to the type of soil resource limitation.

Link between defoliation and light treatments on root vitality of five understory shrubs with different resistance to insect herbivory

Understory shrubs are frequently attacked by insect herbivores. However, very little is known regarding possible interactions between light condition, defoliation (D) and fine root vitality (% live roots) and metabolic activity, and whether different plant strategies (compensation, trade-off and equilibrium) to defoliation depend on individual species light requirements. To explore the response of roots to such conditions, an experiment was established in which we experimentally removed 50% of leaves in 1-year-old seedlings of Sambucus nigra, Cornus sanguinea, Prunus serotina, Frangula alnus and Corylus avellana grown in 15% and full sunlight. On average, defoliation leads to a 15% reduction in fine root (< 2 mm) vitality (% live roots). However, a statistically significant reduction in root vitality after defoliation was detected only in those species that are less herbivorized in nature (48% in S. nigra and 5% in C. sanguinea). On average, shade conditions (L) resulted in 18% decline in root vitality, and the effects of defoliation were also 22% higher than for plants grown in full light. Root vitality in both treatments (D and L) was significantly correlated with their dry mass, concentration of total phenol (TPh) and carbon to nitrogen ratio, and negatively correlated with nitrogen, soluble carbohydrates, starch and total non-structural carbohydrates (TNC). To a large extent, root vitality and chemistry varied by species. Higher root vitality was related to higher concentrations of phenolics, more than to N and TNC concentrations. Concentrations of phenolics also differed significantly between defoliated plants and controls. However, in defoliated plants, an increase in TPh was observed only in two species, which belong to two different groups in light requirements and susceptibility to insect grazing (C. sanguinea and P. serotina). This study indicated that higher vitality of roots occurred in species that are characterized by higher insect defoliation under natural conditions. It is likely that higher root vitality of these species was related to their high level of TPh and tannins. This was especially noticeable for the reduced light treatment, which represents natural conditions under which insect defoliation is highest. Our results suggest that varied strategies of resource allocation were used by the different species in response to variations in light and defoliation.

DETERMINAÇÃO DO PONTO DE AMOSTRAGEM PARA A QUANTIFICAÇÃO DE MACRONUTRIENTES EM Acacia mearnsii DE WILD.

O objetivo deste estudo foi determinar o ponto ótimo de amostragem para a quantificação de nutrientes em árvores de Acacia mearnsii com quatro anos de idade. O trabalho foi realizado em um povoamento de acácia-negra localizado na cidade de Arroio dos Ratos/RS, em uma fazenda pertencente à empresa SETA S/A, nas coordenadas 30°07’12” de latitude sul e 51°57’45” de longitude, com altitude média de 90 m. O primeiro passo foi a realização do inventário florestal no povoamento, onde foram derrubadas 21 árvores, distribuídas em 7 classes diamétricas, sendo determinados a biomassa e o teor de nutrientes dos componentes folha, galho vivo, galho morto, raiz, madeira e casca. Para os componentes madeira e casca, foram retiradas amostras ao longo de fuste nas posições de 1, 3, 10, 20, 30, 40, 50, 60, 70, 80 e 90% da altura total das árvores. O ponto ótimo de amostragem para quantificação dos nutrientes (N, P, K, Ca, Mg e S) no fuste deve situar-se a 50% da altura total das árvores de Acacia mearnsii. É possível a estimativa do estoque de macronutrientes por amostras coletadas no DAP aos 4 anos de idade. Recomenda-se para isso a utilização de trado para não ser necessário derrubar as árvores amostradas. Palavras-chave: Acácia-negra; ponto de amostragem; nutriente. Abstract Sampling point determination for macronutrients quantification on Acacia mearnsii De Wild. The objective of this study was to quantify the biomass and to determine the optimal sampling point for nutrients quantification in four year old Acacia mearnsii trees. It was conducted in black wattle stand, located in Arroio dos Ratos city in a farm belonging to SETA S/A, having as coordinates 30° 07’ 12” of south latitude and 51° 57” 45” of longitude, with 90 m of average altitude. The first step was the forest inventory, where 30 trees were felled, distributed in 7 diametric classes, to cover the stand heterogeneity, then the biomass and the nutrients amount in the leaves, live branches, dead branches, roots, wood and bark were determined. Samples of wood and bark were taken along the stem in the positions of: 1, 3, 10, 20, 30, 40, 50, 60, 70, 80 and 90% of the total height. The optimal sampling point for nutrients (N, P, K, Ca, Mg, and S) quantification along the stem should be 50% from the total height in Acacia mearnsii trees. It’s possible to estimate the stock of macronutrients by samples collected at DBH at 4 years of age. For this it’s recommended to use the borer, for not to be necessary to fell the sampled trees.Keywords: Black wattle; sampling point; nutrient.

Political Hesychasm? Vladimir Petrunin’s Neo-Byzantine Interpretation of the Social Doctrine of the Russian Orthodox Church

Hesychasm is a Christian Orthodox mystical and ascetic tradition that has its roots in the monastic life of early Byzantium. It denotes a method of prayer and a way of life in monastic community, and it describes the overall process of orienting a person's entire being towards an experience of the Divine.1 Asceticism and experiences of self- transcendence are phenomena we encounter in every religion; suffice to think about Sufi Islam, Zen Buddhism or Yoga. Orthodoxy knows the practice of hesychasm, and what is indeed noteworthy about this is that Orthodoxy preserves a Christian ascetic and mystical tradition throughout history, whereas in Western Christianity forms of spiritual exercises and mysticism come to play a minor role. The twentieth century brings about a revival of interest in hesychasm both in Eastern as well as Western Christian theology, a revival that Sergej Khoruzij describes as "anthropological turn in Christian theology" and connects with the names of Georgij Florovskij, Sergej Bulgakov and John Meyendorff on the part of Orthodoxy, Hans Urs von Balthasar and Yves Congar on the part of Catholicism.2 From this theological perspective, hesychasm stands for a form of religious experience and becomes indicative of an anthropological discourse that preserves a sensibility for experiences of self-transcendence.3 If this is the theological and practical meaning of hesychasm, what is political hesychasm? I first encountered the term in the title of the book Politiceskij isikhazm i ego tradicii v social' noj koncepcii Moskovskogo Patriarkha, published by the Aleteija publishing house in Saint Petersburg in 2009 in the series Library of

Intra-annual changes in biomass, carbon, and nitrogen dynamics at 4-year old switchgrass field trials in west Tennessee, USA

Switchgrass is a potential bioenergy crop that could promote soil C sequestration in some environments. We compared four switchgrass cultivars on a well-drained Alfisol to test for differences in biomass, C, and N dynamics during the fourth growing season. There was no difference ( P > 0.05) among cultivars and no significant cultivar × time interaction in analyses of dry mass, C stocks, or N stocks in aboveground biomass and surface litter. At the end of the growing season, mean (±SE) aboveground biomass was 2.1 ± 0.13 kg m −2, and surface litter dry mass was approximately 50% of aboveground biomass. Prior to harvest, the live root:shoot biomass ratio was 0.77. There was no difference ( P > 0.05) among cultivars for total biomass, C, and N stocks belowground. Total belowground biomass (90 cm soil depth) as well as coarse (≥1 mm diameter) and fine (<1 mm diameter) live root biomass increased from April to October. Dead roots were <10% of live root biomass to a depth of 90 cm. Net production of total belowground biomass (505 ± 132 g m −2) occurred in the last half of the growing season. The increase in total live belowground biomass (426 ± 139 g m −2) was more or less evenly divided among rhizomes, coarse, and fine roots. The N budget for annual switchgrass production was closely balanced with 6.3 g N m −2 removed by harvest of aboveground biomass and 6.7 g N m −2 supplied by fertilization. At the location of our study in west Tennessee, intra-annual changes in biomass, C, and N stocks belowground were potentially important to crop management for soil C sequestration.

Chemical stimulation of the Arabidopsis thaliana root using multi-laminar flow on a microfluidic chip

In this article, we developed a "plant on a chip" microfluidic platform that can control the local chemical environment around live roots of Arabidopsis thaliana with high spatial resolution using multi-laminar flow. We characterized the flow profile around the Arabidopsis root, and verified that the shear forces within the device ( approximately 10 dyne cm(-2)) did not impede growth of the roots. Our platform was able to deliver stimuli to the root at a spatial resolution of 10-800 microm. Further, the platform was validated by exposing desired regions of the root with a synthetic auxin derivative, 2,4-dichlorophenoxyacetic acid (2,4-D), and its inhibitor N-1-naphthylphthalamic acid (NPA). The response to the stimuli was observed using a DR5::GFP Arabidopsis line, where GFP expression is coupled to the auxin response regulator DR5. GFP expression in the root matched the position of the flow-focused stream containing 2,4-D. When the regions around the 2,4-D stimulus were exposed to the auxin transport inhibitor NPA, the active and passive transport mechanisms of auxin could be differentiated, as NPA blocks active cell-to-cell transport of auxin. Finally, we demonstrated that local 2,4-D stimulation in a approximately 10 microm root segment enhanced morphological changes such as epidermal hair growth. These experiments were proof-of-concept and agreed with the results expected based on known root biology, demonstrating that this "root on a chip" platform can be used to test how root development is affected by any chemical component of interest, including nitrogen, phosphate, salts, and other plant hormones.

TREE ROOT DAMAGE TO DOMESTIC PROPERTY: A BUILDING SURVEYOR'S PERSPECTIVE

The action of tree roots can damage shallow foundations and cause structural movement in domestic property. This can be either as a result of direct or indirect action by the roots acting upon the foundations. The Building Surveyor engaged to remedy such action must first look to stabilise the property, by first stabilising the site. Only then can the work to repair the damage and prevent future occurrence begin. Whilst engaged in this work the surveyor will use rules of thumb to assess potential for tree root related damage. However, when direct action to a mature tree is proposed reference to a qualified arboriculture specialist is essential. Stabilisation of a site can often be achieved using a regime of regular crown control. Ill-advised removal of mature trees can result in the creation of worse problems than those posed by live tree roots. Three different case studies are used to illustrate the nature of a Building Surveyor's tree root work. These show how neighbours' trees can quickly, and sometimes wrongly, be blamed for structural cracking, the dangers of unqualified tree removal, and that there is a need for professional people from the disciplines of surveying, structural engineering and arboriculture to make appropriate decisions.

Drilling for the Archean Roots of Life and Tetonic Earth in the Barberton Mountains

No abstract available. doi:10.2204/iodp.sd.8.03.2009

Drilling for the Archean Roots of Life and Tectonic Earth in the Barberton Mountains

No abstract available. &lt;br&gt;&lt;br&gt; doi:&lt;a href="http://dx.doi.org/10.2204/iodp.sd.8.03.2009" target="_blank"&gt;10.2204/iodp.sd.8.03.2009&lt;/a&gt;