共查询到20条相似文献,搜索用时 15 毫秒
1.
The developmental profile of the firing patterns and construction of synapse connection were studied in LTS interneurons of
prefrontal cortex (PFC) in rats with age (from P7 to P30). We used whole cell patch-clamp recordings to characterize electrophysiological
properties of LTS interneurons in PFC at different age stages, including the action potentials (APs), short-term plasticity
(STP), evoked excitatory postsynaptic currents (eEPSCs), spontaneous excitatory postsynaptic currents (sEPSC), and spontaneous
inhibitory postsynaptic current (sIPSC). The developmental profile of LTS interneurons in our research showed two phases changes.
The early phase from P7–P11 to P16–P19 during which the development of individual LTS interneuron dominated and just some
simple synaptic connections formed, the synaptic inputs from pyramidal cells play a promoting role for the maturation of LTS
interneurons to some extent. This was based on the changes of APs, eEPSCs, and STP such as the curtailment of time course
of APs, the increasing facilitation of STP before P16–P19 group. The late phase from P20–P23 to P > 27 during which the function
of inhibitory cortex network enhanced and the characters of this inhibitory cortex network continually changed although in
the oldest age group (P > 27) in our research. The frequency and amplitude of sIPSC showed continually changes, and at the
same age group, the frequency ratios and amplitude ratios of sIPSC was higher than that of sEPSC. Our study showed a foundation
to clarify mechanisms underlying the evolution in time of intrinsic neuronal membrane properties and their important roles
in balancing the cortex network, providing an academic foundation for the pathological researching on some psychiatric and
neurological disorders. 相似文献
2.
G N Elston R Tweedale M G Rosa 《Proceedings. Biological sciences / The Royal Society》1999,266(1426):1367-1374
Layer III pyramidal neurons were injected with Lucifer yellow in tangential cortical slices taken from the inferior temporal cortex (area TE) and the superior temporal polysensory (STP) area of the macaque monkey. Basal dendritic field areas of layer III pyramidal neurons in area STP are significantly larger, and their dendritic arborizations more complex, than those of cells in area TE. Moreover, the dendritic fields of layer III pyramidal neurons in both STP and TE are many times larger and more complex than those in areas forming 'lower' stages in cortical visual processing, such as the first (V1), second (V2), fourth (V4) and middle temporal (MT) visual areas. By combining data on spine density with those of Sholl analyses, we were able to estimate the average number of spines in the basal dendritic field of layer III pyramidal neurons in each area. These calculations revealed a 13-fold difference in the number of spines in the basal dendritic field between areas STP and V1 in animals of similar age. The large differences in complexity of the same kind of neuron in different visual areas go against arguments for isopotentiality of different cortical regions and provide a basis that allows pyramidal neurons in temporal areas TE and STP to integrate more inputs than neurons in more caudal visual areas. 相似文献
3.
As is known, an increase in the concentration of Са2+ in the nuclei of nerve cells leads to activation of genes responsible for the formation of long-lasting postsynaptic changes;
mechanisms of memory and learning are based on such changes. The pathways necessary for the entry of calcium into the nuclei
of hippocampal pyramidal neurons remained unstudied. Using a patch-clamp technique, we studied what types of calcium channels
exist in the membranes of isolated nuclei of pyramidal neurons of the hippocampal СА1 area. In the inner nuclear membrane of these cells, we, for the first time, found inositol trisphosphate receptors (IP3Rs) activated by inositol trisphosphate applied in the concentration of ≥0.1 μM. The conductivity of single channels of such
receptors was, on average, 366 pS; these channels were permeable for both monovalent and bivalent cations. Our data indicate
that the nuclear envelope of pyramidal neurons of the hippocampal СА1 area can play the role of the calcium store from which Са2+ enter the cell nucleus directly.
Neirofiziologiya/Neurophysiology, Vol. 40, No. 4, pp. 288–292, July–August, 2008. 相似文献
4.
Sohn Y Yoo KY Park OK Kwon SH Lee CH Choi JH Hwang IK Seo JY Cho JH Won MH 《Neurochemical research》2011,36(12):2459-2469
The maintenance of intracellular pH is important in neuronal function. Na+/HCO3
− cotransporter (NBC), a bicarbonate-dependent acid–base transport protein, may contribute to cellular acid–base homeostasis
in pathophysiological processes. We examined the alterations of NBC immunoreactivity and its protein levels in the hippocampal
CA1 region after transient cerebral ischemia in gerbils. In the sham-operated group, moderate NBC immunoreactivity was detected
in CA1 pyramidal neurons, and, 12 h after I/R, the immunoreactivity in the pyramidal neurons was markedly increased over controls.
Three days after I/R, NBC immunoreactivity nearly disappeared in the CA1 pyramidal neurons. However, NBC immunoreactivity
was detected in the non-pyramidal neurons of the ischemic CA1 region at 3 days after I/R. From double immunofluorescence study
with glial markers, NBC immunoreactivity was detected in astrocytes, not in microglia, at 4 days after I/R. NBC protein level
in the CA1 region was significantly increased at 12 h post-ischemia and significantly decreased at 2 days post-ischemia. Thereafter,
NBC protein level was again increased and returned to the level of the sham-operated group at 4 days post-ischemia. On the
other hand, treatment with 4,4′-diisothiocyanatostilbene-2,2′-disulfonate (DIDS), an inorganic anion exchanger blocker including
Cl-bicarbonate exchanger, protected CA1 pyramidal neurons from I/R injury at 4 days post-ischemia. These results indicate
that changes in NBC expressions may play an important role in neuronal damage and astrocytosis induced by transient cerebral
ischemia. 相似文献
5.
Our previous study revealed that the exposure of the drug 5-Azacytidine and ethanol to the cultured cortical neurons of mice
causes demethylation of cytosine residues in the CpG island of the NMDA receptor NR2B gene (Marutha Ravindran and Ticku, Mol
Brain Res 121:19-27, 2004). In the present study, we further analyzed methylation in the CpG island with various concentration
frame and time frame of exposure of the cultured cortical neurons with 5-azacytidine to identify whether methylation in the
NR2B gene is site specific or region specific. Methylation was studied by digesting the genomic DNA with methylation sensitive
HpaII, MspI, AciI or HhaI enzyme following the exposure of cultured cortical neurons of mice with 5-azacytidine by performing PCR and Southern hybridization.
We observed demethylation of DNA at 1, 3 and 5 μM concentrations of 5-azacytidine in the regions (5982–6155), (6743–7466)
and at 3 and 5 μM concentrations of 5-azacytidine used in the region (6477–6763). Similarly in the time frame study with 5-azacytidine,
demethylation of DNA was observed at 24 h and 36 h of incubation with 5-azacytidine in the regions (5982–6155), (6743–7466)
and at 36 h of incubation with 5-azacytidine used in the region (6477–6763). Our experimental results demonstrate that the
methylation in the CpG islands of the NR2B gene may not be site specific or region specific in the cultured cortical neurons
of mice. 相似文献
6.
Emily Graves Allen Sallie B. Freeman Charlotte Druschel Charlotte A. Hobbs Leslie A. O’Leary Paul A. Romitti Marjorie H. Royle Claudine P. Torfs Stephanie L. Sherman 《Human genetics》2009,125(1):41-52
We examined the association between maternal age and chromosome 21 nondisjunction by origin of the meiotic error. We analyzed
data from two population-based, case–control studies: Atlanta Down Syndrome Project (1989–1999) and National Down Syndrome
Project (2001–2004). Cases were live born infants with trisomy 21 and controls were infants without trisomy 21 delivered in
the same geographical regions. We enrolled 1,215 of 1,881 eligible case families and 1,375 of 2,293 controls. We report four
primary findings. First, the significant association between advanced maternal age and chromosome 21 nondisjunction was restricted
to meiotic errors in the egg; the association was not observed in sperm or in post-zygotic mitotic errors. Second, advanced
maternal age was significantly associated with both meiosis I (MI) and meiosis II (MII). For example, compared to mothers
of controls, mothers of infants with trisomy 21 due to MI nondisjunction were 8.5 times more likely to be ≥40 years old than
20–24 years old at the birth of the index case (95% CI = 5.6–12.9). Where nondisjunction occurred in MII, mothers were 15.1
times more likely to be ≥40 years (95% CI = 8.4–27.3). Third, the ratio of MI to MII errors differed by maternal age. The
ratio was lower among women <19 years of age and those ≥40 years (2.1, 2.3, respectively) and higher in the middle age group
(3.6). Lastly, we found no effect of grand-maternal age on the risk for maternal nondisjunction. This study emphasizes the
complex association between advanced maternal age and nondisjunction of chromosome 21 during oogenesis.
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position
of the Centers for Disease Control and Prevention. 相似文献
7.
Phosphorus speciation in Myall Lake sediment, NSW, Australia 总被引:1,自引:0,他引:1
Daniel Abel Shilla Takashi Asaeda Martin Kalibbala 《Wetlands Ecology and Management》2009,17(2):85-91
The amount of phosphorus and its fractions in the sediment of Lake Myall, NSW, Australia, was assessed using a sequential
extraction technique. Five sedimentary phosphorus reservoirs were measured, namely loosely sorbed phosphorus (NH4Cl–P), iron associated phosphorus (BD–P), calcium bound phosphorus (HCl–P), metal oxide bound phosphorus (NaOH–P) and residual
phosphorus (organic and refractory P, Res-P). Samples were taken from the deep and shallow sites of the lake. During the analysis,
the average concentrations of each fraction of phosphorus was calculated. The results depicted that the total phosphorus (TP)
content and chemically extractable phosphorus in both fine and coarse sediment fractions from the deep sites of the lake were
significantly higher than those of the shallow sites, except for HCl–P extracted from the fine sediment fraction. Sediment
TP was also strongly and positively correlated to sediment Fe. The phosphorus in the sediment mainly consisted of BD–P and
Res-P, while NH4Cl–P and HCl–P only contributed a minor part. The rank order of the different phosphorus extracts was similar for the two
sites, namely Residual-P > BD–P > NaOH–P > HCl–P > NH4Cl–P. 相似文献
8.
Tan EK Tan LC Lim HQ Li R Tang M Yih Y Pavanni R Prakash KM Fook-Chong S Zhao Y 《Human genetics》2008,124(3):287-288
We showed that the frequency of a LRRK2 variant (c.4883G > C, R1628P) was higher in Parkinson’s disease (PD) compared to controls
(8.4 vs. 3.4%, P = 0.046, OR 2.5, 95% CI 1.1–5.6). In the multivariate logistic regression (with adjustments made for the effect of age, age
of onset, and gender), the heterozygous R1628P genotype was associated with an increased risk of PD compared to controls (OR
3.3, 95% CI 1.4– 7.9, P = 0.007). We provided an independent confirmation that the R1628P variant increases the risk of PD among Chinese. 相似文献
9.
Background Two single nucleotide polymorphisms (SNPs, rs10757278 and rs2383207) on chromosome 9p21 have been proved to be associated
with myocardial infarction. We investigated whether these two genetic markers are determinants of early-onset coronary artery
disease. Methods and results A total of 444 consecutive patients were studied including 212 cases with coronary stenosis ≥50% or previous myocardial infarction and 232 controls without documented coronary artery disease. Ligase detection reaction
was performed to detect two SNPs. After adjustment of clinical parameters, significant associations were identified for the
rs2383207 and rs10757278 SNPs, with A/G and G/G genetypes at rs10757278 and G/G genetype carriers at rs2383207 having a higher
risk of early-onset coronary artery disease than carriers of A/A genotype (odds ratio [OR] 2.207, 95% CI: 1.069–4.394, P = 0.028; OR 3.051, 95% CI: 1.086–8.567, P = 0.004; OR 2.964, 95% CI: 1.063–8.265, P = 0.038, respectively). There were no associations between rs10757278 and rs2383207 genotypes and the severity of coronary
artery disease (both P > 0.05). Conclusions The rs10757278 and rs2383207 variants are determinants for early-onset coronary artery disease. These markers may help the
identification of patients at increased risk for early-onset coronary artery disease.
Zhong Chen and Qi Qian contributed equally to this paper. 相似文献
10.
The association between the polymorphic CAG repeat in androgen receptor gene (AR) and prostate cancer susceptibility has been studied extensively. However, the results are contradictory. The purpose of
our meta-analysis was to investigate whether CAG repeat related to prostate cancer risk and had genetic heterogeneity across
different geographic regions and study designs. Random-effects model was performed irrespective of between-study heterogeneity.
Data and study quality were assessed in duplicate. Publication bias was assessed by the fail-safe number and Egger’s test.
There were 16 (patients/controls: 2972/3792), 19 (3835/4908) and 12 (3372/2631) study groups for comparisons of ≥20, 22 and
23 repeats of CAG sequence, respectively. Compared with CAG repeat <20, 22 or 23, carriers of ≥20, 22 or 23 repeats had 21%
(95% CI: 0.61–1.02; P = 0.076), 5% (95% CI: 0.81–1.11; P = 0.508) and 5% (95% CI: 0.76–1.20; P = 0.681) decreased risk of prostate cancer. After classifying studies by geographic areas, carriers of ≥20 repeats had 11%
decreased risk in populations from USA, 53% from Europe, and 20% from Asia (P > 0.05), whereas comparison of ≥23 repeats with others generated a significant prediction in European populations (OR = 1.17;
P = 0.039). Stratification by study designs revealed no material changes in risk estimation. Meta-regression analysis found
no significant sources of between-study heterogeneity for age, study design and geographic region for all comparisons. There
was no identified publication bias. Taken together, our results demonstrated that AR CAG repeat polymorphism with ≥20 repeats might confer a protective effect among the prostate cancer patients with 45 years
older but not all the prostate cancer patients. 相似文献
11.
T T?mb?l 《Acta biologica Academiae Scientiarum Hungaricae》1980,31(1-3):341-365
This paper describes the neurons in different cortical areas and traces their postnatal changes. Rapid Golgi and Golgi--Kopsch impregnation were carried out in 1-day-old and 9-day-old kittens. The maturation of the pyramidal neurons can be observed mainly on their basal dendritic orientation and on development of the dendritic spines. The differentiation of the interneurons (non-pyramidal) also proceeds on the first postnatal days. These, though slightly less mature than the associated pyramidal neurons, are identifiable already on the first postnatal day. It is concluded that there are significant differences in the maturation of the neurons in the various cortical areas. 相似文献
12.
Development of spruce needles starts with high levels of starch. These are derived from imported sucrose, and, with some
fluctuation, largely vanish during sink/source transition (Hampp et al. 1994, Physiol Plant 90: 299 – 306). In order to get
more information about starch metabolism during this period, we collected current year needles of approximately 25-year-old
Norway spruce trees [Picea abies (L.) Karst.] for up to 100 days starting from bud break. Levels of extractable activities of α-amylase (EC 3.2.1.1), ADP-glucose
pyrophosphorylase (AGP, EC 2.7.7.27), D-enzyme (4-α-D-glucotransferase; EC 2.4.1.25), and of starch phosphorylase (STP, EC
2.4.1.1.) exhibited specific development-related responses. Insoluble starch dissolving α-amylase was close to the limit of
detection for up to 70 days after bud break. At this stage, which marked the start of sink/source transition, α-amylase showed
a rise in activity which could be related to the activity of sucrose phosphate synthase, a key enzyme of sucrose formation
(correlation coefficient r = + 0.93). Similarly, the activity of AGP, a key enzyme of starch synthesis, was low during the initial phase of needle development
and started to increase from about 60 days onwards. STP and D-enzyme, both involved in starch cycling, differed from each
other. While STP activity changed in parallel to that of AGP, it was only the D-enzyme which showed appreciable rates shortly
after bud break. We thus assume that in spruce needles D-enzyme is mainly responsible for starch turnover during the early
period of development, whereas needle maturation, i. e. the acquisition of the ability to export photoassimilates, is characterized
by an increased turnover of transitory starch – both synthesis (AGP) and degradation (α-amylase, STP) – and this is closely
connected to the emergence of activity of the key enzyme of sucrose synthesis, sucrose phosphate synthase.
Received: 16 October 1995 / Accepted: 20 February 1996 相似文献
13.
Yu. V. Kirichok Ya. A. Boychuk M. V. Kopanitsa T. Sh. Tsintsadze N. A. Lozovaya O. A. Krishtal 《Neurophysiology》2000,32(1):12-16
The effects of a novel anti-hypertensive drug, mibefradil, on voltage-dependent currents in isolated thalamic and hippocampal
neurons, as well as on synaptic transmission in the hippocampus have been studied. Mibefradil exerted a potent inhibitory
action on low-threshold calcium currents in thalamic neurons (IC50=160 nM). In higher concentrations (1–20 μM), this drug blocked not only low-threshold calcium current but also voltage-dependent
sodium and delayed potassium currents in pyramidal hippocampal neurons. The amplitude of population action potentials in hippocampal
slices decreased by 55% in the presence of 20μM mibefradil. All of the effects of mibefradil were almost completely reversible.
In our experiments, the sensitivity of low-threshold calcium channels in thalamic neurons to mibefradil was higher than that
observed on other objects. The ability of mibefradil to block not only calcium currents but also other types of voltage-dependent
ion conductances in hippocampal neurons may be considered an essential factor that determines the specificity of the pharmacological
profile of this drug. 相似文献
14.
Ki-Yeon Yoo Ok Kyu Park Jiatian Yu Bingchun Yan Hua Li Choong Hyun Lee Jung Hoon Choi Dae Won Kim In Koo Hwang Moo-Ho Won 《Cellular and molecular neurobiology》2009,29(3):413-421
Oxidative stress is one of predisposing factors to age-related neurodegeneration in the brain. In particular, thiol-containing
groups are susceptible to oxidative stress, which induces the formation of the disulfide bond and/or hyperoxidized form of
thiol-containing proteins. We observed the protein thiol levels in the hippocampal homogenates and also investigated changes
in hyperoxidized form of peroxiredoxin (Prx–SO3) immunoreactivity and proteins levels in the gerbil hippocampal subregions during normal aging. Levels of total thiol, non-protein
thiol, and protein thiol were decreased in the hippocampal homogenates with age. At post-natal month 1 (PM 1), pyramidal and
non-pyramidal cells in the hippocampal CA1 region (CA1) showed Prx–SO3 immunoreactivity. Prx–SO3 immunoreactivity in the cells was decreased by PM 12, thereafter, Prx–SO3 immunoreactivity in the cells increased again with age. In the CA2/3, Prx–SO3 immunoreactivity in pyramidal cells was not significantly changed; however, the immunoreactivity in pyramidal cells was very
low at PM 12. Prx–SO3 immunoreactivity in the dentate gyrus (DG) was distinctly changed during aging. At PM 1, Prx–SO3 immunoreactivity in granule and polymorphic cells was weak and strong, respectively. The immunoreactivity in the neurons
was decreased with age, not shown in any neurons at PM 12. Thereafter, Prx–SO3 immunoreactivity increased again with age. In addition, Prx–SO3 protein level in the hippocampus was lowest at PM 12. These results suggest that thiol-containing proteins are changed during
aging and Prx–SO3 immunoreactivity was different according to cells in the hippocampal subregion during aging. 相似文献
15.
Cornelia Hagemann Marianne Vater Manfred Kössl 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2011,197(5):605-613
Target-distance computation by cortical neurons sensitive to echo delay is an essential characteristic of the auditory system
of insectivorous bats. To assess if functional requirements such as detection of small insects versus larger stationary surfaces
of plants are reflected in cortical properties, we compare delay-tuned neurons in a frugivorous (C. perspicillata, CP) and an insectivorous (P. parnellii, PP) bat species that belong to related families within the superfamily of Noctilionoidea. The bandwidth and shape of delay-tuning
curves and the range of characteristic delays are similar in both species and hence are not related to different echolocation
strategies. Most units respond at 2–6 ms echo delay with most sensitive thresholds of 20–30 dB SPL. In CP, units tuned to delays >12 ms are slightly more abundant and are more sensitive than in PP. All delay-tuned neurons in CP reliably respond to single pure-tone stimuli, whereas such responses are only observed in 49% of delay-tuned units in PP. The cortical representation of echo delay (chronotopy) covers a larger area in CP but is less precise than described in PP. Since chronotopy is absent in certain other insectivorous bat species, it is open if these differences in topography are
related to echolocation behaviour. 相似文献
16.
Networks of synchronized fast-spiking interneurons are thought to be key elements in the generation of gamma (γ) oscillations
(30–80 Hz) in the brain. We examined how such γ-oscillatory inhibition regulates the output of a cortical pyramidal cell.
Specifically, we modeled a situation where a pyramidal cell receives inputs from γ-synchronized fast-spiking inhibitory interneurons.
This model successfully reproduced several important aspects of a recent experimental result regarding the γ-inhibitory regulation
of pyramidal cellular firing that is presumably associated with the sensation of whisker stimuli. Through an in-depth analysis
of this model system, we show that there is an obvious rhythmic gating effect of the γ-oscillated interneuron networks on
the pyramidal neuron’s signal transmission. This effect is further illustrated by the interactions of this interneuron network
and the pyramidal neuron. Prominent power in the γ frequency range can emerge provided that there are appropriate delays on
the excitatory connections and inhibitory synaptic conductance between interneurons. These results indicate that interactions
between excitation and inhibition are critical for the modulation of coherence and oscillation frequency of network activities. 相似文献
17.
Trace element content in hair is affected by the age of the donor. Hair samples of subjects from four counties in China where
people are known to have long lifespan (“longevity counties”) were collected and the trace element content determined. Samples
were subdivided into three age groups based on the age of the donors from whom these were taken: children (0–15 years); elderly
(80–99 years); and centenarians (≥100 years). We compared the trace element content in hair of different age groups of subjects.
Support vector machine classification results showed that a non-linear polynomial kernel function could be used to classify
the three age groups of people. Age did not have a significant effect on the content of Ca and Cd in human hair. The content
of Li, Mg, Mn, Zn, Cr, Cu, and Ni in human hair changed significantly with age. The magnitude of the age effect on trace element
content in hair was in the order Cu > Zn > Ni > Mg > Mn > Cr > Li. Cu content in hair decreased significantly with increasing
age. The hair of centenarians had higher levels of Li and Mn, and lower levels of Cr, Cu, and Ni comparing with that of the
children and elderly subjects. This could be a beneficial factor of their long lifespan. 相似文献
18.
In some plant species, various arsenic (As) species have been reported to efflux from the roots. However, the details of As
efflux by the As hyperaccumulator Pteris vittata remain unknown. In this study, root As efflux was investigated for different phosphorus (P) supply conditions during or after
a 24-h arsenate uptake experiment under hydroponic growth conditions. During an 8-h arsenate uptake experiment, P-supplied
(P+) P. vittata exhibited much greater arsenite efflux relative to arsenate uptake when compared with P-deprived (P–) P. vittata, indicating that arsenite efflux was not proportional to arsenate uptake. In the As efflux experiment following 24 h of arsenate
uptake, arsenate efflux was also observed with arsenite efflux in the external solution. All the results showed relatively
low rates of arsenate efflux, ranging from 5.4 to 16.1% of the previously absorbed As, indicating that a low rate of arsenate
efflux to the external solution is also a characteristic of P. vittata, as was reported with arsenite efflux. In conclusion, after 24 h of arsenate uptake, both P+ and P– P. vittata loaded/effluxed similar amounts of arsenite to the fronds and the external solution, indicating a similar process of xylem
loading and efflux for arsenite, with the order of the arsenite concentrations being solution ≪ roots ≪ fronds. 相似文献
19.
A comparative study of mmunoreactivity with respect to c-Fos protein in the motor (zones М1 and М2), medial prefrontal (PrL and IL), and cingular (Cg1 and Cg2) cortices allowed us to find significant differences between the intensities of expression of gene c-fos in these cortical regions in control rats (group 1) and animals trained to perform catching of food globules by the forelimb
(i.e., realizing an operant food-procuring reflex, group 2). The density of distribution of Fos-immunoreactive (Fos-ir) neurons
in rats of group 2 in motor and limbic cortical zones at +2.2 to +0.2 levels rostrally from the bregma were significantly
lower than in control rats (Р < 0.05). In animals of group 2, we also found significantly greater numbers of Fos-ir neurons in the contralateral (with respect
to the active extremity) zones of the cortex at all examined levels. These changes are probably related to functional changes
in the cortex resulting from learning of motor habits in the course of training sessions for stabilization of the operant
reflex. Histochemical estimation of the NADPH-diaphorase (NADPH-d) activity in the motor and limbic cortex showed that, in
rats of both groups, the maximum number of labeled interneurons per slice in the М1 zone were observed in layers II/III, V, and VI (5.6 ± 0.4, 6.4 ± 0.5, and 14.0 ± 0.8, respectively, within 200 × 200 μm2 areas). In the limbic cortex, NADPH-d-reactive (NADPH-d-r) interneurons were also met in layers II/III, V, and VI. Cortical
NADPHd-r neurons with the Fos-ir nuclei were not found. The presence of spatial associations of the somata or processes of
NADPH-d-r neurons with intraparenchimal arterioles and microvessels was a typical feature of the distribution of NADPH-d-reactivity
in the М1 and М2 zones, as well as in Cg1, Cg2, PrL, and IL. The following succession of the density of neurovascular associations was observed: Cg1 > Cg2 > М1 > М2 > > PrL. As is supposed, NADPH-d-r neurons (i.e., cells generating NO) are involved in the control of regional blood flow in the
studied cortical regions.
Neirofiziologiya/Neurophysiology, Vol. 40, No. 4, pp. 348–358, July–August, 2008. 相似文献
20.
Characterization of phosphorus fractions in the sediments of a tropical intertidal mangrove ecosystem 总被引:2,自引:0,他引:2
Solid phases of phosphorus fractions in the surface and core sediments were studied to understand the biogeochemical cycling
and bioavailability of phosphorus in the Pichavaram intertidal mangrove sediments of India. Total P in surface and core sediments
ranged between 451–552 and 459–736 μg g−1 respectively and Fe bound P was the dominant fraction. Low levels of Fe bound P in the mangrove zone than the two estuarine
zones may be because of high salinity inhibition of phosphate adsorption onto the Fe-oxides/hydroxides. Post-depositional
reorganization of P was observed in surface sediments, converting organic P and Fe bound P into the authigenic P. High levels
of organic P in the mangrove zone is primarily due to intensive cycling and degradation of organic matter and adsorption of
phosphate on the organic molecules. The burial rates and regeneration efficiency of P in the intertidal mangrove ecosystem
ranged from 5.41 to 7.27 μmol P cm−2 year−1 and 0.122 to 0.233 μmol P cm−2 year−1, respectively. High burial efficiency (≈99%) of P proves the earlier observation of limiting nature of P for the biological
productivity. Further, bioavailable P (exchangeable P + Fe bound P + organic P) constituted a considerable proportion of sedimentary
P pool of which an average accounted for 55 and 50% in surface and core sediments respectively. The results indicate that
significant amount of P is locked in sediments in the form of authigenic P and detrital P which makes P as a limiting nutrient
for the biological productivity. 相似文献