Cloning and localization of rgpr85 encoding rat G-protein-coupled receptor

In an attempt to isolate genes involved in the brain development using ordered differential display PCR, we cloned rgpr85 which encodes rat G-protein-coupled receptor with high degree of identity to the amine-like neurotransmitter receptors. This gene was found to be localized at rat chromosome 4q21. In situ hybridization demonstrated that rgpr85 was predominantly expressed in the developing brain and spinal cord. Hybridization signal was especially abundant within the embryonic cortical plates where postmitotic cortical neurons are localized. In the cerebral cortex, the expression of rgpr85 was gradually decreased postnatally and became undetectable by P18. However, weak but significant expression of rgpr85 was maintained in the adult hippocampal formation, olfactory bulb, and cerebellum. Interestingly, rgpr85 expression was transiently induced in the adult hippocampal formation, piriform cortex, and amygdaloid complex by kainic acid (KA) treatment. Thus, dynamic regulation of rgpr85 expression suggests an importance of rgpr85-mediated signaling in the development of cerebral cortex and in the KA-induced responses in the adult brain.     

Learning deficits and agenesis of synapses and myelinated axons in phosphoinositide-3 kinase-deficient mice

Although previous studies have reported a role for phosphoinositide-3 kinase (PI3K) in axonal definition and growth in vitro, it is not clear whether PI3K regulates axonal formation and synaptogenesis in vivo. The goal of the present study was to clarify the role of PI3K in behavioral functions and some underlying neuroanatomical structures. Immunohistochemistry, an electron-microscopic analysis and behavioral tests were carried out. Knockout mice lacking the p85alpha regulatory subunit of PI3K (p85alpha-/- mice) significantly showed learning deficits, restlessness and motivation deficit. Expression of phosphorylated Akt, which indirectly shows the activity of PI3K, was high in myelinated axons, especially in axonal bundles in the striatum of wild-type mice, but was significantly low in the striatum, cerebral cortex and the hippocampal CA3 of p85alpha-/- mice. The axonal marker protein level decreased mainly in the striatum and cerebral cortex of p85alpha-/- mice. In these two regions, myelinated axons are rich in the wild-type mice. However, the density of myelinated axons and myelin thickness were significantly low in the striatum and cerebral cortex of p85alpha-/- mice. Synaptic protein level was clearly decreased in the striatum, cerebral cortex, and hippocampus of p85alpha-/- mice when compared with wild mice. The present results suggest that PI3K plays a role in the generation and/or maintenance of synapses and myelinated axons in the brain and that deficiencies in PI3K activity result in abnormalities in several neuronal functions, including learning, restlessness and motivation.     

Comparison of in vitro- and chorioallantoic membrane (CAM)-culture systems for cryopreserved medulla-contained human ovarian tissue

At present, there are three ways to determine effectively the quality of the cryopreservation procedure using ovarian tissue before the re-implantation treatment: evaluation of follicles after post-thawing xenotransplantation to SCID mouse, in-vitro culture in a large volume of culture medium under constant agitation and culture on embryonic chorio-allantoic membrane within a hen's eggs. The aim of this study was to compare the two methods, culture in vitro and culture on embryonic chorioallantoic membrane (CAM) of cryopreserved human ovarian medulla-contained and medulla-free cortex. Ovarian fragments were divided into small pieces (1.5-2.0×1.0-1.2×0.8-1.5) of two types, cortex with medulla and medulla-free cortex, frozen, thawed and randomly divided into the following four groups. Group 1: medulla-free cortex cultured in vitro for 8 days in large volume of medium with mechanical agitation, Group 2: medulla-containing cortex cultured in vitro, Group 3: medulla-free cortex cultured in CAM-system for 5 days, Group 4: medulla-containing cortex cultured in CAM-system. The efficacy of the tissue culture was evaluated by the development of follicles and by intensiveness of angiogenesis in the tissue (von Willebrand factor and Desmin). For Group 1, 2, 3 and 4, respectively 85%, 85%, 87% and 84% of the follicles were morphologically normal (P>0.1). The immunohistochemical analysis showed that angiogenesis detected by von Willebrand factor was lower in groups 1 and 3 (medulla-free cortex). Neo-vascularisation (by Desmin) was observed only in ovarian tissue of Group 4 (medulla-contained cortex after CAM-culture). It appears that the presence of medulla in ovarian pieces is beneficial for post-thaw development of cryopreserved human ovarian tissue. For medical practice it is recommended for evaluation of post-warming ovarian tissue to use the CAM-system as a valuable alternative to xenotransplantation and for cryopreservation of these tissues to prepare ovarian medulla-contained strips.     

INCENP binds directly to tubulin and requires dynamic microtubules to target to the cleavage furrow

Inner centromere protein (INCENP) is a chromosomal passenger protein with an essential role in mitosis. At the metaphase/anaphase transition, some INCENP transfers from the centromeres to the central spindle; the remainder then transfers to the equatorial cortex prior to cleavage furrow formation. The molecular associations dictating INCENP behavior during mitosis are currently unknown. Here we show that targeting INCENP to the cleavage plane requires dynamic microtubules, but not F-actin. When microtubules are eliminated, INCENP is dispersed across the entire cell cortex. Yeast two-hybrid and in vitro binding data demonstrate that INCENP binds directly to beta-tubulin via a conserved domain encompassing residues 48-85. Furthermore, INCENP binds to microtubules polymerized from purified tubulin in vitro and appears to bundle microtubules when expressed in the interphase cytoplasm. These data indicate that INCENP is a microtubule-binding protein that targets to the equatorial cortex through interactions requiring microtubules.     

Cochleotopic organization of the primary auditory cortex in cats

The cochleotopic organization of the primary auditory cortex was studied by the evoked potentials method in cats anesthetized with pentobarbital. Two foci of maximal activity (dorsal and ventral) were found in the primary auditory cortex of 85% of animals during local electrical stimulation of different areas of the cochlea. Analysis of projection maps of the primary auditory cortex of the cats showed that different areas of the cochlea are presented in this region disproportionately. The basal portion projects to a larger cortical surface than the middle and apical portions together, evidence of inequality of representation of different parts of the receptor apparatus of the cochlea in the primary auditory area. Considerable differences were observed in the arrangement of projections of the cochlea in the primary auditory cortex of different animals.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 11, No. 2, pp. 117–124, March–April, 1979.     

Perinatal inflammation results in decreased oligodendrocyte numbers in adulthood

Aims

Maternal inflammation is a risk factor for preterm birth, and premature infants are often exposed to supplemental oxygen as a life-sustaining therapy. While more immature neonates are surviving, rates of neurodevelopmental impairment are not improving. We developed a novel mouse model with clinically relevant exposures to test the hypothesis that systemic maternal inflammation with transient neonatal hyperoxia exposure will induce a phenotype similar to diffuse periventricular leukomalacia (PVL) like that observed in premature human infants.

Main methods

Timed-pregnant C3H/HeN mice received intraperitoneal injections of lipopolysaccharide (LPS) or saline on embryonic day 16. Newborn pups were placed in room air (RA) or 85% oxygen (O₂) for 14 days, followed by 14 days in RA recovery. Oligodendroglial and microglial populations were evaluated at 14 and 28 days.

Key findings

Brain weight to body weight ratios were lower in mice exposed to LPS. Oligodendrocyte numbers were decreased significantly in the cerebral cortex and hippocampus in groups exposed to LPS or LPS/O₂ at 14 days, and persisted in the cerebral cortex at 28 days for LPS/O₂ mice. At day 14, cleaved caspase 3 was increased and numbers of microglia were elevated in the cerebral cortex and hippocampus of LPS/O₂ animals.

Significance

These data indicate that combining systemic maternal LPS and neonatal hyperoxic exposure impairs myelination, and suggests that this novel mouse model may represent a subtle, diffuse form of periventricular white matter injury that could provide a clinically relevant platform for further study of perinatal brain injury.     

Evoked impulse activity in neuronally isolated cortex

The reactions of neurons of the isolated cortex of one hemisphere to direct cortical stimulation were investigated in cats under Nembutal anesthesia. Isolation of the cortex was carried out by Khananashvili's method [10]. It is shown that phasic reactions develop in the isolated cortex in response to such stimulation: initial discharge, initial pause, first after-discharge, first after-pause, late after-discharges and pauses, as well as reactions of presumably inhibitory neurons. A majority of the cells (85%) which manifest background activity respond to direct electrical stimulation, and the frequency of the late after-reactions is twice as great as in the intact cortex. It is concluded that cortical elements of the isolated cortex retain their principal neurophysiological properties.Institute of Experimental Medicine, Academy of Medical Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 3, No. 3, pp. 236–244, May–June, 1971.     

Characterization and expression profile of two UDP-glucosyltransferases, UGT85K4 and UGT85K5, catalyzing the last step in cyanogenic glucoside biosynthesis in cassava

Manihot esculenta (cassava) contains two cyanogenic glucosides, linamarin and lotaustralin, biosynthesized from l ‐valine and l ‐isoleucine, respectively. In this study, cDNAs encoding two uridine diphosphate glycosyltransferase (UGT) paralogs, assigned the names UGT85K4 and UGT85K5, have been isolated from cassava. The paralogs display 96% amino acid identity, and belong to a family containing cyanogenic glucoside‐specific UGTs from Sorghum bicolor and Prunus dulcis. Recombinant UGT85K4 and UGT85K5 produced in Escherichia coli were able to glucosylate acetone cyanohydrin and 2‐hydroxy‐2‐methylbutyronitrile, forming linamarin and lotaustralin. UGT85K4 and UGT85K5 show broad in vitro substrate specificity, as documented by their ability to glucosylate other hydroxynitriles, some flavonoids and simple alcohols. Immunolocalization studies indicated that UGT85K4 and UGT85K5 co‐occur with CYP79D1/D2 and CYP71E7 paralogs, which catalyze earlier steps in cyanogenic glucoside synthesis in cassava. These enzymes are all found in mesophyll and xylem parenchyma cells in the first unfolded cassava leaf. In situ PCR showed that UGT85K4 and UGT85K5 are co‐expressed with CYP79D1 and both CYP71E7 paralogs in the cortex, xylem and phloem parenchyma, and in specific cells in the endodermis of the petiole of the first unfolded leaf. Based on the data obtained, UGT85K4 and UGT85K5 are concluded to be the UGTs catalyzing in planta synthesis of cyanogenic glucosides. The localization of the biosynthetic enzymes suggests that cyanogenic glucosides may play a role in both defense reactions and in fine‐tuning nitrogen assimilation in cassava.     

Propagating waves in visual cortex: a large-scale model of turtle visual cortex

This article describes a large-scale model of turtle visual cortex that simulates the propagating waves of activity seen in real turtle cortex. The cortex model contains 744 multicompartment models of pyramidal cells, stellate cells, and horizontal cells. Input is provided by an array of 201 geniculate neurons modeled as single compartments with spike-generating mechanisms and axons modeled as delay lines. Diffuse retinal flashes or presentation of spots of light to the retina are simulated by activating groups of geniculate neurons. The model is limited in that it does not have a retina to provide realistic input to the geniculate, and the cortex and does not incorporate all of the biophysical details of real cortical neurons. However, the model does reproduce the fundamental features of planar propagating waves. Activation of geniculate neurons produces a wave of activity that originates at the rostrolateral pole of the cortex at the point where a high density of geniculate afferents enter the cortex. Waves propagate across the cortex with velocities of 4 m/ms to 70 m/ms and occasionally reflect from the caudolateral border of the cortex.     

Neural field model of seizure-like activity in isolated cortex

Epileptiform discharges on an isolated cortex are explored using neural field theory. A neural field model of the isolated cortex is used that consists of three neural populations, excitatory, inhibitory, and excitatory bursting. Mechanisms by which an isolated cortex gives rise to seizure-like waveforms thought to underly pathological EEG waveforms on the deafferented cortex are explored. It is shown that the model reproduces similar time series and oscillatory frequencies for paroxysmal discharges when compared with physiological recordings both during acute and chronic deafferentation states. Furthermore, within our model ictal activity arises from perturbations to steady-states very close to the dynamical system’s instability boundary; hence, these are distinct from corticothalamic seizures observed in the model for the intact brain which involved limit-cycle dynamics. The results are applied to experiments in deafferented cats.     

The influence of glutathione oxidation on renal cortex taurine transport

The interaction of diamide, a rapidly reversible thioloxidizing re reagent, with the taurine accumulation system was examined in rat kidney cortex slices from animals of different ages. Diamide at 10 mM lowered renal cortex glutathione content by 80% at a time that taurine accumulation was inhibited by 65%. Although the addition of equimolar GSH overcame diamide inhibition of taurine uptake, GSH per se inhibited taurine accumulation at 0.01 mM, but not at 0.2 or 1.0 mM. Dithiothreitol (DTT) also overcame diamide inhibition of uptake. As previously shown by Pillion et al (Eur. J. Biochem. $\text{79}$, 73, 1977) diamide inhibited gluconeogenesis by cortex slices.Diamide inhibited taurine accumulation by 85% by the low Km taurine transport site in cortex from newborn, 2 week, 4 week and adult animals, but only 50% at the high Km site. In contrast to the situation in adult tissue, efflux of taurine from preloaded slices of immature animals was not increased by diamide. Accordingly, one maturational event identified by these studies is that diamide-enhanced efflux was found only in mature cortex.     

白鲜根的发育解剖学研究

应用半薄切片、常规石蜡切片并结合离析法,对药用植物白鲜(Dictamnus dasycarpus Turcz.)根的发生发育过程进行了研究。结果表明:白鲜根的发生发育过程包括4个阶段,即原分生组织阶段、初生分生组织阶段、初生结构阶段以及次生结构阶段。原分生组织位于根冠内侧及初生分生组织之间,衍生细胞分化为初生分生组织。初生分生组织由原表皮、基本分生组织以及中柱原组成。原表皮分化为表皮,基本分生组织分化为皮层,中柱原分化为维管柱,共同组成根的初生结构;在初生结构中,部分表皮细胞外壁向外延伸形成根毛,皮层中分布有油细胞,内皮层有凯氏带,初生木质部为二原型或偶见三原型,外始式;根初生结构有髓或无。次生结构来源于原形成层起源的维管形成层的活动以及中柱鞘起源的木栓形成层的活动;白鲜次生韧皮部宽广,其中多年生根中可占根横切面积的85%,另外除基本组成分子外,还分布有油细胞;周皮发达,木栓层厚;初生皮层、次生木质部和次生韧皮部薄壁细胞中常充满丰富的淀粉粒。     

A multi-stage model for fundamental functional properties in primary visual cortex

Many neurons in mammalian primary visual cortex have properties such as sharp tuning for contour orientation, strong selectivity for motion direction, and insensitivity to stimulus polarity, that are not shared with their sub-cortical counterparts. Successful models have been developed for a number of these properties but in one case, direction selectivity, there is no consensus about underlying mechanisms. We here define a model that accounts for many of the empirical observations concerning direction selectivity. The model describes a single column of cat primary visual cortex and comprises a series of processing stages. Each neuron in the first cortical stage receives input from a small number of on-centre and off-centre relay cells in the lateral geniculate nucleus. Consistent with recent physiological evidence, the off-centre inputs to cortex precede the on-centre inputs by a small (～4 ms) interval, and it is this difference that confers direction selectivity on model neurons. We show that the resulting model successfully matches the following empirical data: the proportion of cells that are direction selective; tilted spatiotemporal receptive fields; phase advance in the response to a stationary contrast-reversing grating stepped across the receptive field. The model also accounts for several other fundamental properties. Receptive fields have elongated subregions, orientation selectivity is strong, and the distribution of orientation tuning bandwidth across neurons is similar to that seen in the laboratory. Finally, neurons in the first stage have properties corresponding to simple cells, and more complex-like cells emerge in later stages. The results therefore show that a simple feed-forward model can account for a number of the fundamental properties of primary visual cortex.     

Effects of ozone on cell organelles of alfalfa (Medicago sativa L.) seedlings

Seedlings of alfalfa (Medicago sativa L.) were exposed to different concentrations of atmospheric ozone (20–30 (control), 40–60, 65–80, and 85–120 ppb) in four distinct areas in the Riyadh region, so as to decide how ozone affected some of the seedling cellular organelles. Results acquired utilizing transmission electron microscopy demonstrated certifiable impacts to exist on the cell organelles in the tissues of both the leaf mesophyll and stem cortex; contrasted with control plants, the chloroplasts seemed enlarged, irregular, different sizes, decomposed, and possibly dissolved, while the plastoglobules seemed deformed, more widely spaced, and enlarged, also the vacuoles contained no clear non-living components. Moreover, some parts of the cytoplasmic membranes were ruptured, with only a few vesicles created at all concentrations, particularly in plants exposed to concentrations of 65–80 and 85–120 ppb, while no effects were noted in these organelles in control plants or plants exposed to 40–60 ppb. High concentrations (85–120 ppb) led to enlarged, irregularly shaped nuclei and chromatin intensification; however, no clear effects of ozone were noted on the shapes of chloroplast starch grains or the mitochondria in leaf mesophyll and cortex cells in the stem. The high ozone concentrations can cause negative effects on the growth of alfalfa seedlings, leading to imbalances in their vital functions and acceleration of aging, thus potentially decreasing the total plant yield. The discoveries hence propose that alfalfa plants should not be planted near polluted areas, and that they can be utilized as bioindicators of air pollution by ozone.     

A Dendritic Mechanism for Decoding Traveling Waves: Principles and Applications to Motor Cortex

Traveling waves of neuronal oscillations have been observed in many cortical regions, including the motor and sensory cortex. Such waves are often modulated in a task-dependent fashion although their precise functional role remains a matter of debate. Here we conjecture that the cortex can utilize the direction and wavelength of traveling waves to encode information. We present a novel neural mechanism by which such information may be decoded by the spatial arrangement of receptors within the dendritic receptor field. In particular, we show how the density distributions of excitatory and inhibitory receptors can combine to act as a spatial filter of wave patterns. The proposed dendritic mechanism ensures that the neuron selectively responds to specific wave patterns, thus constituting a neural basis of pattern decoding. We validate this proposal in the descending motor system, where we model the large receptor fields of the pyramidal tract neurons — the principle outputs of the motor cortex — decoding motor commands encoded in the direction of traveling wave patterns in motor cortex. We use an existing model of field oscillations in motor cortex to investigate how the topology of the pyramidal cell receptor field acts to tune the cells responses to specific oscillatory wave patterns, even when those patterns are highly degraded. The model replicates key findings of the descending motor system during simple motor tasks, including variable interspike intervals and weak corticospinal coherence. By additionally showing how the nature of the wave patterns can be controlled by modulating the topology of local intra-cortical connections, we hence propose a novel integrated neuronal model of encoding and decoding motor commands.     

Paradoxical effects of two oximes on nitric oxide production by purified NO synthases, in cell culture and in animals.

We have studied the impact of two novel compounds TO-85 (2,6-di-(alpha-aziridino-alpha-hydroxyiminomethyl)pyridine and TO-133 (bis-(diaziridinoglyoximato)copper), designed as NO donors, on nitrite production by cell cultures, NO production in rat tissues and their ability to inhibit purified NO synthases (NOS). Both substances induced considerable increase of nitrite production in cell cultures. When NO production was assayed in rat organs by means of ESR using Fe(DETC) as a spin trap the anticipated NO-increasing activity of TO-85 was observed only in kidneys; the NO level increasing almost 10-fold. Treatment of rats with TO-133, decreased the NO concentration in brain cortex, cerebellum and liver. When the drugs were administered to animals with high level of iNOS expression induced by LPS, TO-85 did not significantly modify the LPS-induced NO production; administration of TO-133 caused a significant decrease of NO production in blood, brain cortex and cerebellum. Only high concentrations of TO-85 were capable of inhibiting iNOS (IC50=7 mM), the substance inhibited eNOS at lower concentrations (IC50=250 microM). Inhibitory activities of TO-85 on nNOS were dependent on BH4 concentrations, suggesting eventual competition of TO-85 with BH4 when the substance interacts with nNOS. TO-133 reduced eNOS activity with IC50=200 microM, nNOS activity with IC50=200 microM, iNOS activity was not much affected by this substance. Thus, the two tested compounds manifest opposite effects on NO production by purified enzymes and in cell culture. The pattern of the NO synthesis modification in a living animal appears to be even more complex. Our results stress the importance of direct measurements of NO in the tissues using the ESR method.     

Emergence of orientation-selective inhibition in the primary visual cortex: a Bayes–Markov computational model

The recent consensus is that virtually all aspects of response selectivity exhibited by the primary visual cortex are either created or sharpened by cortical inhibitory interneurons. Experimental studies have shown that there are cortical inhibitory cells that are driven by geniculate cells and that, like their cortical excitatory counterparts, are orientation selective, though less sharply tuned. The main goal of this article is to demonstrate how orientation-selective inhibition might be created by the circuitry of the primary visual cortex (striate cortex, V1) from its nonoriented geniculate inputs. To fulfill this goal, first, a Bayes–Markov computational model is developed for the V1 area dedicated to foveal vision. The developed model consists of three parts: (i) a two-layered hierarchical Markov random field that is assumed to generate the activity patterns of the geniculate and cortical inhibitory cells, (ii) a Bayesian computational goal that is formulated based on the maximum a posteriori (MAP) estimation principle, and (iii) an iterative, deterministic, parallel algorithm that leads the cortical circuitry to achieve its assigned computational goal. The developed model is not fully LGN driven and it is not implementable by the neural machinery of V1. The model, then, is transformed into a fully LGN-driven and physiologically plausible form. Computer simulation is used to demonstrate the performance of the developed models.     

Mathematical modeling and parameter estimation of axonal cargo transport

This paper is about how cortical recurrent interactions in primary visual cortex (V1) together with feedback from extrastriate cortex can account for spectral peaks in the V1 local field potential (LFP). Recent studies showed that visual stimulation enhances the γ-band (25–90 Hz) of the LFP power spectrum in macaque V1. The height and location of the γ-band peak in the LFP spectrum were correlated with visual stimulus size. Extensive spatial summation, possibly mediated by feedback connections from extrastriate cortex and long-range horizontal connections in V1, must play a crucial role in the size dependence of the LFP. To analyze stimulus-effects on the LFP of V1 cortex, we propose a network model for the visual cortex that includes two populations of V1 neurons, excitatory and inhibitory, and also includes feedback to V1 from extrastriate cortex. The neural network model for V1 was a resonant system. The model’s resonance frequency (ResF) was in the γ-band and varied up or down in frequency depending on cortical feedback. The model’s ResF shifted downward with stimulus size, as in the real cortex, because increased size recruited more activity in extrastriate cortex and V1 thereby causing stronger feedback. The model needed to have strong local recurrent inhibition within V1 to obtain ResFs that agree with cortical data. Network resonance as a consequence of recurrent excitation and inhibition appears to be a likely explanation for γ-band peaks in the LFP power spectrum of the primary visual cortex.     

Dissociation of temporal and frontal components in the human auditory N1 wave: a scalp current density and dipole model analysis

This study reports a combined scalp current density (SCD) and dipole model analysis of the N1 wave of the auditory event-related potentials evoked by 1 kHz tone bursts delivered every second. The SCD distributions revealed: (i) a sink and a source of current reversing in polarity at the inferotemporal level of each hemiscalp, compatible with neural generators in and around the supratemporal plane of the auditory cortex, as previously reported; and (ii) bilateral current sinks over frontal areas. Consistently, dynamic dipole model analysis showed that generators in and outside the auditory cortex are necessary to account for the observed current fields between 65 and 140 msec post stimulus. The frontal currents could originate from the motor cortex, the supplementary motor area and/or the cingulate gyrus. The dissociation of an exogenous, obligatory frontal component from the sensory-specific response in the auditory N1 suggests that parallel processes served by distinct neural systems are activated during acoustic stimulation. Implications for recent models of auditory processing are discussed.