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At least 415 records · Page 23Linked to original sources
PubMed1993

Optimal digital filters for long-latency components of the event-related brain potential.

A fundamentally important problem for cognitive psychophysiologists is selection of the appropriate off-line digital filter to extract signal from noise in the event-related brain potential (ERP) recorded at the scalp. Investigators in the field typically use a type of finite impulse response (FIR) filter known as moving average or boxcar filter to achieve this end. However, this type of filter can produce significant amplitude diminution and distortion of the shape of the ERP waveform. Thus, there is a need to identify more appropriate filters. In this paper, we compare the performance of another type of FIR filter that, unlike the boxcar filter, is designed with an optimizing algorithm that reduces signal distortion and maximizes signal extraction (referred to here as an optimal FIR filter). We applied several different filters of both types to ERP data containing the P300 component. This comparison revealed that boxcar filters reduced the contribution of high-frequency noise to the ERP but in so doing produced a substantial attenuation of P300 amplitude and, in some cases, substantial distortions of the shape of the waveform, resulting in significant errors in latency estimation. In contrast, the optimal FIR filters preserved P300 amplitude, morphology, and latency and also eliminated high-frequency noise more effectively than did the boxcar filters. The implications of these results for data acquisition and analysis are discussed.

Adult↗
PubMed1990

Application of beat-to-beat techniques.

The focus of this report is to describe a system for recording surface His-Purkinje and ventricular late potentials on a beat-by-beat basis outside of a shielded environment. An AC magnetic field monitoring device was designed for improved site selection, orientation, and quality control of the acquisition. His-Purkinje signals are detected utilizing spatial averaging and specific channel selection algorithms applied to discriminate random noise from signal. Beat-by-beat vectormagnitude complexes were generated from pairs of X, Y, and Z leads. Both infinite impulse response (IIR) filters, modified for beat-by-beat approaches, and finite impulse response (FIR) filters were utilized. Using the IIR filter, beat-by-beat recordings from test subjects were compared to the signal averaged electrocardiogram (SAECG). Measurement parameters from normal test subjects fell within the previously specified normal range for the SAECG. The IIR filter applied to beat-by-beat recordings exhibited sharp frequency response and a precisely defined cutoff frequency allowing maximal attenuation of the low frequency components in the ST segment. While filter ringing was eliminated, discontinuity and distortion of the filtered waveform resulted. The FIR filter with linear phase response retained the integrity and morphology of the complex but because of its flat frequency response, the ST segment was not as well attenuated and it was more difficult to isolate late potentials. A high order FIR filter should be used if the desire is to match the frequency response of the four-pole IIR filter, since the frequency response of the FIR filter is primarily determined by the order of the filter.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed2006

Nuclear factor-kappaB p65 inhibits mitogen-activated protein kinase signaling pathway in radioresistant breast cancer cells.

The molecular mechanism by which tumor cells increase their resistance to therapeutic radiation remains to be elucidated. We have previously reported that activation of nuclear factor-kappaB (NF-kappaB) is causally associated with the enhanced cell survival of MCF+FIR cells derived from breast cancer MCF-7 cells after chronic exposure to fractionated ionizing radiation. The aim of the present study was to reveal the context of NF-kappaB pathways in the adaptive radioresistance. Using cell lines isolated from MCF+FIR populations, we found that the elevated NF-kappaB activity was correlated with enhanced clonogenic survival, and increased NF-kappaB subunit p65 levels were associated with a decrease in phosphorylation of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK in all radioresistant MCF+FIR cell lines. Further irradiation with 30 fractions of radiation also inhibited MEK/ERK phosphorylation in paired cell lines of MCF+FIR and parental MCF-7 cells. Activation of ataxia-telangiectasia mutated (ATM) protein, a sensor to radiation-induced DNA damage, was elevated with increased interaction with NF-kappaB subunits p65 and p50. The interaction between p65 and MEK was also enhanced in the presence of activated ATM. In contrast, both interaction and nuclear translocation of p65/ERK were reduced. Inhibition of NF-kappaB by overexpression of mutant IkappaB increased ERK phosphorylation. In addition, MEK/ERK inhibitor (PD98059) reduced the interaction between p65 and ERK. Taken together, these results suggest that NF-kappaB inhibits ERK activation to enhance cell survival during the development of tumor adaptive radioresistance.

Breast Neoplasms↗
PubMed2002

Cellulase adsorption and an evaluation of enzyme recycle during hydrolysis of steam-exploded softwood residues.

The sugar yield and enzyme adsorption profile obtained during the hydrolysis of SO2-catalyzed steam-exploded Douglas-fir and posttreated steam-exploded Douglas-fir substrates were determined. After hot alkali peroxide posttreatment, the rates and yield of hydrolysis attained from the posttreated Douglas-fir were significantly higher, even at lower enzyme loadings, than those obtained with the corresponding steam-exploded Douglas-fir. The enzymatic adsorption profiles observed during hydrolysis of the two substrates were significantly different. Ultrafiltration was employed to recover enzyme in solution (supernatant) and reused in subsequent hydrolysis reactions with added, fresh substrate. These recycle findings suggested that the enzyme remained relatively active for three rounds of recycle. It is likely that enzyme recovery and reuse during the hydrolysis of posttreated softwood substrates could lead to reductions in the need for the addition of fresh enzyme during softwood-based bioconversion processes.

Adsorption↗
PubMed2006

Forest dynamics after successive spruce budworm outbreaks in mixedwood forests.

In order to assess the long-term spatiotemporal influence of the spruce budworm in sub-boreal mixedwood forests, we studied the effect of three successive outbreaks in a region of western Quebec, Canada. We used dendrochronology to detect past outbreaks in three areas (111-185 ha), based on the recruitment age of balsam fir (Abies balsamea) and on growth patterns of white spruce (Picea glauca), the two main host species of this defoliating insect. We also used a series of aerial photographs taken between 1935 and 2003 to evaluate overstory mortality and post-outbreak succession patterns in these same areas. Individual outbreaks had a spatially homogenous impact on host species throughout the region, but successive outbreaks differed in intensity: the two outbreaks around 1910 and 1980 caused widespread mortality in the overstory, but an outbreak around 1945 had little impact, probably because the forest mosaic had not yet recuperated from the 1910 outbreak. No clear outbreak was detected in the later part of the 19th century. In portions of the study areas where the 1910 outbreak had a major impact, between 36% and 50% of the stands were reoccupied by balsam fir stands in the period up to the 1980 outbreak (cyclic succession), the rest being at least partly replaced by nonhost species such as Betula spp. Changes in forest composition after the 1910 outbreak were mostly associated with upper-slope positions in all study areas. The 1980 outbreak also had a higher impact than earlier outbreaks in lower-slope positions dominated by black spruce (Picea mariana)-balsam fir mixtures. These results suggest that, at the regional scale, the abundance of mature or over-mature balsam fir stands does not determine the outbreak cycle. When an outbreak occurs, however, its impact will be strongly constrained by forest characteristics such as stand composition and structure, which are themselves influenced by previous disturbances and slope position.

Abies↗
PubMed1986

Transovarial maintenance of San Angelo virus in sequential generations of Aedes albopictus.

An Aedes albopictus line originally selected for efficient transovarial transmission (TOT) of San Angelo (SA) virus displayed a progressive decline in filial infection rate (FIR) whenever artificial selection pressure was relaxed. This observation brought into question whether the efficiency of TOT in this vector-virus model was sufficiently high to permit persistent vertical transmission over numerous freely reproducing generations. By tracing descendants of individual transovarially infected females for several generations, it was found in the present study that this decline in FIR resulted not only from the spontaneous appearance of uninfected females, but also from an accumulation of transovarially infected females which were themselves inefficient transovarial transmitters. Some efficient transovarial transmitters continued to be produced even when FIR had declined to low levels, assuring transmission of virus to subsequent generations, irrespective of the overall infection rate. Outcrossing experiments suggested that a "refractory" genetic factor or factors had been selected out of the TOT-efficient line during its long history of inbreeding. New TOT-efficient lines were more readily established from parenterally infected Ae. albopictus of a Taiwan strain than had been the original TOT-efficient line from a Hawaiian mosquito strain. One of the newly selected lines differed from the others in producing progenies with FIRs no higher than 36% in the third and fourth generations of transovarial passage. The familial and strain variation revealed by these studies suggests a genetic influence on both the establishment and maintenance of persistent oogonial infections.

Aedes↗
PubMed1998

[Magnetic resonance findings in chronic osteomyelitis fistula].

INTRODUCTION: Osteomyelitis is a common inflammatory process caused by an infection which is usually from gram-positive germs. Acute, subacute and chronic forms can be distinguished both clinically and radiographically, each of them presenting different patterns but which are not always easy to recognize. Besides clinical-laboratory data, imaging methods are also useful to make the diagnosis; in chronic forms, MRI has higher sensitivity in recognizing the active foci and the presence of sinus tracts than the other techniques. MATERIAL AND METHODS: We examined nine patients with suspected chronic osteomyelitis with a sinus tract, all of them submitted to radiographic and MR examinations. MRI was performed with a .5 T magnet using a surface coil for joint studies; T1-weighted SE (TR 300-500, TE 20), T2-weighted GE (TR 500-700, TE 20, FA 35 degrees) and FIR sequences with fat suppression (TR 3000, TE 20, TI 100) were performed on the axial, sagittal and coronal planes. Three patients underwent CT too. RESULTS: Radiography showed the osteostructural changes as osteolytic and osteosclerotic areas. CT depicted not only the changes seen radiographically, but also increased bone marrow density. MRI demonstrated active foci of bone marrow appearing as low-intensity areas in T1, with increased intensity in T2 GE and fat-suppressed FIR images; it also depicted the sinus tracts as areas of decreased signal on T1 and of increased signal on FIR images. CONCLUSIONS: Based on our experience and in agreement with the literature data, we believe that MRI is more useful to diagnose the active foci of bone marrow and the sinus tracts in chronic osteomyelitis, especially with T1-weighted SE and fat-suppressed FIR sequences.

Adult↗
PubMed1998

[Observation of inducing effect of five kinds of soft wood dust in micronucleus test].

The authors investigated the micronucleus frequencies (MP) in peripheral lymphocytes in 584 workers exposed to five kinds of soft wood dust and found that all kinds of soft wood dust could increase the micronucleus frequency. As the control's 95% confidential upper limit > or = 0.4% is defined as the standard for positivity the micronucleus positive frequency (MPF) in the exposure group is much higher than that in the control group (P < 0.01). Meanwhile the increase of exposure years may increase the MP, and the time-response relationship is evident (r = 0.90, P < 0.01). For different exposures, the MPFs are: 36.2% for linden, 26.3% for fir. 15.7% for lacebark pine, 9.6% for birch and 2.1% for polar. The positive rate of linden and fir exposure are significantly higher than that of the control group (P < 0.01). Water extract of these five kinds of soft wood dust can increase the frequencies of micronucleus in polychromatic red blood cell in mice's sternum marrow, which also showed a dose-response. The correlation coefficients are: 0.86 for linden 0.6 for fir, 0.39 for lacebark pine, 0.76 for birch and 0.73 for polar. All but the lacebark pine have the P value less than 0.01 (P < 0.01). At the dose of 15 g/kg body weight, micronucleus frequency induced by linden was the highest (0.8%), next were fir (0.71%), birch (0.65%), lacebark pine (0.63%), and polar (0.43%). The results from animal test are consistent with those from the exposure workers. These results suggest that there are some substances in soft wood which can induce chromosome aberration.

Adolescent↗
PubMedDate not supplied

Food restriction and spontaneous motor activity in male mice: effects of feeding pattern, far-infrared ray and bamboo grass leaf extract.

The effects on spontaneous motor activity of the pattern of restricted feeding, far-infrared ray (FIR) irradiation or free access in drinking water containing Sasa Health, a bamboo grass leafextract, were examined in SHN male mice at 2-3 months of age. In mice whose diet was restricted to 60% of the control, fed at 9:00 or 17:00 hours, the level of spontaneous behaviour was elevated 1 hour before the respective feeding time (8:00 or 16:00 hours). The activity was stimulated by FIR in both the control and food-restricted mice, but to a much higher degree in the latter. Treatment with Sasa Health in drinking water lowered the elevated activity level in food-restricted mice. Plasma component levels and organ weights were modulated by FIR or Sasa Health. The findings revealed that, not only the restricted feeding itsel, but also its pattern, significantly affected behaviour and that FIR and Sasa Health modified the deleterious effects of restricted feeding.

Administration, Oral↗
PubMed2002

A novel FERM domain including guanine nucleotide exchange factor is involved in Rac signaling and regulates neurite remodeling.

The Rho family of small GTPases, key regulators of the actin cytoskeleton in eukaryotic cells from yeast to human, is implicated in the control of neuronal morphology. Guanine nucleotide exchange factors (GEFs) are upstream positive regulators of Rho GTPases and integrate extracellular signaling for appropriate activation of Rho GTPases at specific subcellular regions. Here we describe the identification of a novel Dbl family GEF for Rho GTPases in Homo sapiens and Mus musculus. It contains a tandem Dbl homology-pleckstrin homology domain and FERM domain, characteristic of the plasma membrane proteins linker. This gene, termed FERM domain including RhoGEF (FIR), was abundantly expressed in brain, lung, and testis, as well as embryonic hippocampal and cortical neurons. FIR was found to activate the biochemical pathway specific for Rac1 but not for RhoA or Cdc42. Ectopic expression of FIR in the cortical neurons resulted in significantly shortened neurites and excessive growth cones, presumably mediated by Rac1. These results suggest that FIR may regulate neurite remodeling by mediating the signaling pathways from membrane proteins to Rac.

3T3 Cells↗
PubMedDate not supplied

Response of cyclin B1 to ionizing radiation: regulation by NF-kappaB and mitochondrial antioxidant enzyme MnSOD.

BACKGROUND: To understand the molecular response of tumor cells to therapeutic ionizing radiation (IR), we previously reported that human breast cancer cells derived following chronic exposure to fractionated ionizing radiation (MCF+FIR) showed a transient radioresistance. MCF+FIR cells also demonstrated increased activity of NF-kappaB, increased expression of the mitochondrial antioxidant enzyme (MnSOD), and increased expression of a cell cycle regulatory protein (Cyclin B1). The present studies were designed to determine the relationship of NF-kappaB, MnSOD and Cyclin B1 expression in cellular adaptive responses to ionizing radiation. MATERIALS AND METHODS: The first intron of the cyclin B1 gene with a putative NF-kappaB element was cloned into the pGL3 luciferase reporter (pGL3CB1EI1). PGL3CB1EI1 and control NF-kappaB luciferase activities were determined in MCF-7 and MCF+FIR cells treated with a single dose of radiation, over expression of the dominant negative mutant IkB (mIkB) or over expression of the SOD2 gene. RESULTS: MCF+FIR cells derived from fractionated IR demonstrated increased transactivation of the pGL3CB1EI1 and NF-kappaB controlled reporter activities, relative to the parental cell line. Transfection of dominant negative mutant IkB that inhibits NF-kappaB nuclear translocation, inhibited pGL3CB1EI1 and NF-kappaB activity, indicating the NF-kappaB dependence of pGL3CB1EI1 mediated transcription. In addition, over expression of the human SOD2 gene (MnSOD) inhibited NF-kappaB and pGL3CB1EI1 activity, indicating that superoxide or some species derived from superoxide may have participated in the up-regulation of reporter activity in response to chronic exposure to fractionated ionizing radiation. These results provide evidence suggesting that a signaling pathway involving NF-kappaB and Cyclin B1 may contribute to adaptive radioresistance induced by chronic exposure to fractionated IR and support the conclusion that MnSOD appears to be a negative regulator of this pathway.

Amino Acid Sequence↗
PubMedDate not supplied

Fractionated ionizing radiation exposure induces apoptosis through caspase-3 activation and reactive oxygen species generation.

BACKGROUND: Radiation therapy (RT) is a well established therapeutic modality for the treatment of solid tumors. In particular, post-operative RT is considered the standard treatment adjuvant to surgery since its ability to prolong median survival of patients with malignant astrocytoma has been shown; nevertheless the ionizing radiation (IR) treatment fails in a considerable number of astrocytoma patients. MATERIALS AND METHODS: Using an ADF human astrocytoma cell line the molecular mechanisms involved in the DNA damage induced by fractionated irradiation (FIR) and single IR treatment have been investigated. RESULTS: FIR and single IR treatment inhibited the growth of the ADF human astrocytoma cell line. FACS analysis revealed that FIR treatment, but not single IR treatment, induced growth inhibition associated with the induction of apoptosis. Apoptosis was related to caspase-3 activation and reactive oxygen species (ROS) generation. ROS formation depends on the up-regulation of the cytochrome P450 enzyme gene. On the contrary, 12.5 Gy induced necrotic cell death up-regulating the HSPD1, HSPCB, HSPCA and HSPB1 genes. CONCLUSION: FIR treatment induced cell death through caspase-3 and ROS-mediated apoptosis.

Apoptosis↗
PubMed2001

Antimicrobial activity of some Pacific Northwest woods against anaerobic bacteria and yeast.

Extracts of woods commonly used for animal bedding were tested for antimicrobial activity. Essential oils from Alaska cedar (Chamaecyparis nootkatensis), western juniper (Juniperus occidentalis) and old growth Douglas fir (Pseudotsuga menziesii) as well as methanol extracts of wood from these trees plus western red cedar (Thuja plicata) and ponderosa pine (Pinus ponderosa) were tested for antimicrobial activity against anaerobic bacteria and yeast. The test microbes included Fusobacterium necrophorum, Clostridium perfringens, Actinomyces bovis and Candida albicans which are common to foot diseases and other infections in animals. The essential oils and methanol extracts were tested using a standardized broth assay. Only extracts of Alaska cedar and western juniper showed significant antimicrobial activity against each of the microbes tested. The essential oil of Douglas fir did show antimicrobial activity against A. bovis at the concentrations tested. The methanol extracts of the heartwood of Douglas fir and the sapwood of ponderosa pine showed no antimicrobial activity. The major chemical components of western juniper (cedrol and alpha- and beta-cedrene) and Alaska cedar (nootkatin) were also tested. In western juniper, alpha- and beta-cedrene were found to be active components. Nootkatin showed activity only against C. albicans. The inhibitory activity in Alaska cedar oil was high enough to justify further efforts to define the other chemical components responsible for the antimicrobial activity.

Anti-Bacterial Agents↗
PubMed1994

Diterpenoid resin acid biosynthesis in conifers: characterization of two cytochrome P450-dependent monooxygenases and an aldehyde dehydrogenase involved in abietic acid biosynthesis.

Abietic acid is a major component of the rosin fraction of oleoresin synthesized by grand fir (Abies grandis), lodgepole pine (Pinus contorta), and many other conifer species as a defensive secretion against insect and pathogen attack. The diterpenoid resin acid is derived from geranylgeranyl pyrophosphate via abietadiene, with subsequent oxidation of the C18-methyl of this olefin to abietadienol, abietadienal, and abietic acid. The pathway was confirmed by administering [1,2-14C]acetic acid to grand fir stems which incorporated the radiolabel into abietadiene, the corresponding alcohol and aldehyde, as well as abietic acid. Three different enzymatic activities, catalyzing the sequential oxidation of the olefin to abietic acid, were demonstrated in cell-free stem extracts of both grand fir and lodgepole pine. The first two oxidation steps were catalyzed by the microsomal fraction and required both oxygen and a reduced pyridine nucleotide (NADPH preferred). Both activities were strongly inhibited by CO (blue light reversible) and were differentially sensitive to several substituted N-heterocyclic inhibitors, suggesting that these two enzymes are distinct, microsomal cytochrome P450-dependent monooxygenases. A third enzymatic activity, catalyzing the oxidation of abietadienal to abietic acid, was located in the soluble protein fraction. This oxidation reaction employed NAD+ as cofactor, but did not require oxygen and was not inhibited by CO, indicating that this last step of abietic acid biosynthesis is catalyzed by an operationally soluble aldehyde dehydrogenase.

Abietanes↗
PubMed1994

Diterpenoid resin acid biosynthesis in conifers: enzymatic cyclization of geranylgeranyl pyrophosphate to abietadiene, the precursor of abietic acid.

Abietic acid is a major component of the rosin fraction of oleoresin synthesized by conifer species, such as grand fir (Abies grandis) and lodgepole pine (Pinus contorta), as a defensive secretion against insect and pathogen attack. This diterpenoid resin acid is derived from geranylgeranyl pyrophosphate by conversion to abietadiene and sequential oxidation of the C18-methyl group of the precursor olefin to a carboxyl function. Resin acid biosynthesis is constitutively expressed at high levels in lodgepole pine stem and is induced to these levels by stem wounding in grand fir. Soluble enzyme extracts of lodgepole pine stem and of mechanically wounded grand fir stem catalyzed the divalent metal ion-dependent cyclization of [1-3H]geranylgeranyl pyrophosphate to (-)-abieta-7(8),13(14)-diene. The wound-inducible enzyme was partially purified and identified as an 80-kDa protein with general characteristics typical of those of other terpenoid cyclases. Although the enzymatic cyclization sequence almost certainly involves the formation of copalyl pyrophosphate and a pimaradiene as stable intermediates, no evidence for the separation of the corresponding partial activities was obtained. A pathway involving the production of various pimaradiene and abietadiene isomers is proposed to account for the origin of several common resin acids.

Abietanes↗
PubMed1997

Investigation of C-O Stretching Band of CD3OH: Assignments of Far-Infrared Laser Lines

We have investigated the high-resolution Fourier transform spectrum of the C-O stretching fundamental band of CD3OH in order to assign far-infrared (FIR) laser transitions. The absorption spectrum was analyzed by means of the "Ritz" program, which calculates the energy level values directly from the Rydberg-Ritz combination principle. We have also used the "LaseRitz" program to facilitate the assignment of the FIR laser lines. As a consequence we could determine 12 new assignments, confirming 4 previously proposed ones and predicting new FIR laser emissions. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed2000

Absolute nu(2) Line Intensities of HOCl by Simultaneous Measurements in the Infrared with a Tunable Diode Laser and Far-Infrared Region Using a Fourier Transform Spectrometer.

We have measured absolute line intensities in the nu(2) fundamental band at 1238 cm(-1) of both isotopomers of hypochlorous acid, HOCl. To obtain the partial pressure of the species in the sample mixture, unavailable through direct measurement since HOCl exists only in equilibrium with H(2)O and Cl(2)O and may decay by secondary reactions, we relied on known absolute line intensities in the pure rotational far-infrared (FIR) spectrum determined from Stark effect measurements. We have thus recorded simultaneously the FIR pure rotation spectrum of HOCl using a Bruker IFS120HR interferometer and the spectrum of a few vibration-rotation lines in the infrared (IR) nu(2) band using a tunable diode laser spectrometer. The absolute intensities of these IR lines thus determined allowed us to "calibrate" the intensities of vibration-rotation lines in the whole nu(2) band, measured previously using Fourier transform spectroscopy. The treatment of the data took into account the blackbody emission contribution in the FIR and the evolution of the HOCl amount during the recording of the spectra. The latter was found to be almost constant over hours after conditioning of the cell. The square of the nu(2) band vibrational transition dipole moment was determined to be 0.013947(23) D(2) and 0.013870(51) D(2) for HO(35)Cl and HO(37)Cl, respectively, that is, 29 to 73% lower than previous measurements. A linear Herman-Wallis factor was also determined for both isotopomers. Finally, the line intensities were least-squares fitted using a model that takes into account a weak resonance between the (010) and (002) levels. Copyright 2000 Academic Press.

Journal Article↗
PubMed2005

Microbial community structure and density under different tree species in an acid forest soil (Morvan, France).

Overexploitation of forests to increase wood production has led to the replacement of native forest by large areas of monospecific tree plantations. In the present study, the effects of different monospecific tree cover plantations on density and composition of the indigenous soil microbial community are described. The experimental site of "Breuil-Chenue" in the Morvan (France) was the site of a comparison of a similar mineral soil under Norway spruce (Picea abies), Douglas fir (Pseudotuga menziesii), oak (Quercus sessiflora), and native forest [mixed stand dominated by oak and beech (Fagus sylvatica)]. Sampling was performed during winter (February) at three depths (0-5, 5-10, and 10-15 cm). Abundance of microorganisms was estimated via microbial biomass measurements, using the fumigation-extraction method. The genetic structure of microbial communities was investigated using the bacterial- and fungal-automated ribosomal intergenic spacer analysis (B-ARISA and F-ARISA, respectively) DNA fingerprint. Only small differences in microbial biomass were observed between tree species, the highest values being recorded under oak forest and the lowest under Douglas fir. B- and F-ARISA community profiles of the different tree covers clustered separately, but noticeable similarities were observed for soils under Douglas fir and oak. A significant stratification was revealed under each tree species by a decrease in microbial biomass with increasing depths and by distinct microbial communities for each soil layer. Differences in density and community composition according to tree species and depth were related to soil physicochemical characteristics and organic matter composition.

Bacteria↗