bluuebunny/crossref_metadata_2025 huggingface dataset:
A multiple beam interferometer for Bose‐Einstein condensates
Authors: Cataliotti F.S.
Published: April 2003

We condense 87Rb atoms in the combined potential of an optical standing wave superimposed on a harmonic magnetic trap. By releasing the atoms from the combined trap we realise a multiple beam atom interferometer. The measured atomic interferogram provides information about macroscopic coherence throughout the sample. The atomic distribution is characterised by interference peaks. The time evolution of the peaks, their relative population, as well as their radial size are in agreement with the predictions of theory. By a perturbation of the magnetic trap we induce an oscillating atomic current related to coherent tunnelling of the Bose‐Einstein condensates through the optical barriers. The frequency and amplitude of the oscillations are in agreement with a model based on the Josephson current‐phase relations.
Experimental demonstration of quantum logic operations using linear optical elements
Authors: Franson J.D. , Jacobs B.C. , Pittman T.B.
Published: April 2003

Probabilistic quantum logic operations can be implemented using linear optical elements, additional photons (ancilla), and post‐selection based on the results of measurements made on the ancilla photons. Here we describe the experimental demonstration of several quantum logic devices of that kind, including a quantum parity check and a destructive controlled‐NOT (CNOT) gate. An experimental demonstration of feed‐forward control for use in quantum logic operations is also reported. The implementation of a conventional CNOT gate using polarizing beam splitters is described, along with a new “high‐fidelity” approach in which the logic gates always produce an output.
Towards high‐fidelity two‐photon quantum communications
Authors: Kurizki G. , Petrosyan D.
Published: April 2003

We propose two alternative scheme for highly efficient nonlinear interaction between weak optical fields. The first scheme is based on the attainment of electromagnetically induced transparency simultaneously for two fields via transitions between magnetically split F = 1 atomic sublevels, in the presence of two driving fields. The second scheme relies on simultaneous electromagnetically‐ and self‐induced transparencies of the two fields. Thereby, equal slow group velocities and giant cross‐phase modulation of the weak fields over long distances are achieved.
Frequency hopping in quantum interferometry
Authors: Mataloni P. , Giorgi G. , De Martini F.
Published: April 2003

We have realized the nonlinear frequency conversion of optical quantum superposition states in a new kind of Mach‐Zehnder interferometer which is terminated at two different frequencies. The information‐preserving character of the relevant unitary transformation represented by the nonlinear process has been experimentally demonstrated in the cases of input qubits and ebits. The theoretical expression of the quantum efficiency of the process is compared with the experimental results. Besides its own intrinsic fundamental interest, the new scheme is expected to find important applications in modern quantum information technology.
On Bell's theorem for N‐qubits
Authors: Żukowski M. , Brukner C.
Published: April 2003

We present a single general Bell inequality that summarizes all possible Bell type constrains on the correlation function for the N‐particle system (i.e., it is a necessary and sufficient condition for the existence of local realistic models for the correlation function). It is applicable in the case when measurements on each particle can be chosen between two arbitrary dichotomic observables. We also obtain a necessary and sufficient condition for an arbitrary N‐qubit mixed state to violate this general Bell inequality.
Full‐length and short forms of utrophin, the dystrophin‐related protein
Authors: Nguyen thi Man  , Helliwell T.R. , Simmons C. , Winder S.J. , Kendrick-Jones J. , Davies K.E. , Morris G.E.
Published: April 2003

All previous studies of the localization of utrophin (the dystrophin‐related protein) in muscle and other tissues have been performed only with antibodies against the C‐terminal region of the protein. Since several short forms of dystrophin, the apodystrophins, are produced from the 3′ end of the dystrophin gene, there is a possibility that similar short forms of utrophin exist and that these could be responsible for some of the many different localizations of ‘utrophin’ in muscle. We have produced a new panel of 15 mAbs against the N‐terminal region of utrophin and we have used it together with mAbs against the C‐terminal region to show that full‐length utrophin is present at neuromuscular junctions, in nerves, blood vessels and capillaries in normal muscle and in the sarcolemma of patients with muscular dystrophy and dermatomyositis. However, two of the 15 mAbs also recognised rat/mouse utrophin and both of these detected an additional 62 kDa protein on Western blots of rat C6 glioma cells. This potential 62 kDa ‘apo‐utrophin’ was not detected in human cerebral cortex, in rat Schwannoma cells nor in any of the non‐nerve cells and tissues tested.
A second nitrogen permease regulator in Saccharomyces cerevisiae
Authors: Rousselet Germain , Simon Matthieu , Ripoche Pierre , Buhler Jean-Marie
Published: April 2003

We describe a Saccharomyces cerevisiae mutant affected in its urea and proline transport capacities, and a gene coding for a protein complementing this mutation. This protein is not membrane‐embedded and contains two PEST sequences, often found in regulatory factors. The mRNA is not down‐regulated under nitrogen catabolite repression, and is induced by urea and proline. In the mutant, the PUT4 mRNA encoding the proline permease is not affected, whereas the DUR3 mRNA, involved in urea active transport, is strongly increased. Our data suggest that this protein is a post‐transcriptional regulator of nitrogen permeases.
Binding of the growth factor glycyl‐l‐histidyl‐l‐lysine by heparin
Authors: Rabenstein Dallas L. , Robert Jan M. , Hari Siva
Published: April 2003

Evidence is presented that the growth factor glycylhistidyl‐lysine (GHK) binds to heparin, and the interaction has been characterized by [1H]NMR spectroscopy. 1H chemical shifts indicate that GHK interacts with both the carboxylic acid and the carboxylate forms of heparin. The chemical shift data are consistent with a weak delocalized binding of the triprotonated (ImH+, GlyNH3
+, LysNH3
+) form of GHK by the carboxylic acid form of heparin. As the pD is increased and the carboxylic acid groups are titrated, chemical shift data indicate that ammonium groups of GHK are hydrogen bonded to heparin carboxylate groups, while the histidyl imidazolium ring occupies the imidazolium‐binding site of heparin. Evidence for site‐specific binding includes displacement of chemical shift titration curves for heparin to lower pD, increased shielding of specific heparin protons by the imidazolium ring current and displacement of chemical shift titration curves for GHK to higher pD. Specific binding constants were determined for binding of the (ImH+, GlyNH3
+), LysNH3
+), (ImH+, GlyNH2, LysNH3
+) and (Im, GlyNH3
+, LysNH3
+) forms of GHK by the carboxylate form of heparin from chemical shift vs. pD titration data.
Antenna size dependent exciton dynamics in the chlorosomal antenna of the green bacterium Chloroflexus aurantiacus
Authors: Fetisova Zoya , Freiberg Arvi , Novoderezhkin Vladimir , Taisova Alexandra , Timpmann Kiu
Published: April 2003

Using picosecond fluorescence spectroscopy, we demonstrated antenna size dependent exciton dynamics in chlorosomal antenna, measured for intact cells of different cultures of the green bacterium Chloroflexus aurantiacus with different chlorosomal antenna size determined by electron microscopic examination of ultrathin sections of the cells. The measured bacteriochlorophyll (BChl) c excitation lifetimes show a quasilinear dependence on chlorosome size as predicted in our model for cylindrical exciton migration within the three‐dimensional chlorosomal antenna. The migration model was developed for the proposed exciton model of chlorosomal BChl c aggregation. The data predict the time constant values for excitation energy transfer between BChl c aggregates as well as to BChl a of the baseplate.
A 45‐bp proximal region containing AACA and GCN4 motif is sufficient to confer endosperm‐specific expression of the rice storage protein glutelin gene,GluA‐3
Authors: Yoshihara Toshihiro , Washida Haruhiko , Takaiwa Fumio
Published: April 2003

A 45‐bp proximal region of the rice glutelin promoter (−104/−60) containing two putativecis‐elements, the AACA motif and GCN4 motifs, was fused to a truncated CaMV 35S promoter (−90/+9; −90Δ35S)/GUS. The 45‐bp fragment specifically enhanced the promoter activity in endosperm tissue of transformed tobacco. A substitution mutation of the GCN4 motif reduced the promoter activity, whereas mutation of the AACA motif increased the activity in the embryo as well as in the endosperm. These results suggest that the GCN4 motif generally enhances the promoter activity but that the combination of the two motifs confers the endosperm specificity. Furthermore, the function of the two motifs was dependent on the orientation and/or distance from a G‐box element in −90Δ35S, suggesting that synergistic interaction between the factors that recognize those motifs and the G‐box element is important for transcriptional regulation.
Functional importance of the dihydropyridine‐sensitive, yet voltage‐insensitive store‐operated Ca2+ influx of U937 cells
Authors: Willmott Nicholas J. , Choudhury Qam , Flower Roderick J.
Published: April 2003

The Ca2+ current activated by Ca2+ store depletion in non‐excitable cells is classically regarded as being dihydropyridine‐insensitive, suggesting that store‐operated Ca2+ channels (SOCs) are dissimilar to voltage‐gated Ca2+ channels (VGCs) of excitable‐cells. Here, we demonstrate dihydropyridine‐sensitivity for the store‐operated Ca2+ influx induced by ATP and thapsigargin (Tg) in the non‐excitable U937 cell‐line. Ca2+ store depletion by prior treatment of cells with either Tg or ATP, stimulated a Ca2+ entry mechanism that was inhibited by nicardipine, nifedipine, and the specific L‐type Ca2+ channel blocker, calciseptine. A functional requirement for this Ca2+ influx mechanism in agonist‐induced mitogenesis seemed likely, since nicardipine, a particularly potent inhibitor of store‐operated Ca2+ influx in these cells, suppressed ATP‐ and Tg‐stimulated cell proliferation. Depolarisation of cells with KCl, or gramicidin failed to elicit an increase in cytosolic Ca2+, suggesting that while the store‐operated Ca2+ influx channel of U937 cells shares pharmacologic properties with the L‐type Ca2+ channel, it is voltage‐insensitive and therefore may resemble an channel lacking a voltage sensor.
Genetic mapping of genes for twelve nuclear‐encoded polypeptides associated with the thylakoid membranes in Beta vulgaris L
Authors: Pillen Klaus , Schondelmaier Jörg , Jung Christian , Herrmann Reinhold G.
Published: April 2003

Thylakoid membranes of chloroplasts are composed of approx. 75 polypeptide species. Nearly 60% originate in nuclear genes, the remainder in plastid genes. In order to localize representatives of the nuclear‐encoded gene complement in a eukaryotic plant genome (sugar beet, Beta vulgaris L.), we have investigated the RFLP patterns of 21 cDNAs from spinach that code for thylakoid proteins or proteins peripherally associated with thylakoid membranes. Differences in gene dosage were noted between both related species. Polymorphism was found for 12 cDNA loci in a segregating sugar beet F2 population. These loci were mapped along with genomic RFLP, isozyme, and morphological markers, and shown to be distributed in six of the nine sugar beet linkage groups. The lack of positional clustering even of genes that encode components of the same supramolecular membrane assembly is commensurate with phylogenetically independent gene translocations from the plastid (endosymbiont), and raises the question of the functional integration of various translocated genes into common signal transduction chains.
Crystallization and X‐ray analysis of the reaction center from the thermophilic green bacterium Chloroflexus aurantiacus
Authors: Feick R. , Ertlmaier A. , Ermler Ulrich
Published: April 2003

The photochemical reaction center of Chloroflexus (Cf.) aurantiacus, a membrane bound pigment‐protein complex, has been crystallized in the presence of monodisperse polyoxyethylene detergents. The crystals possessed a pronounced polymorphism. Three different crystal forms belonging to triclinic, monoclinic and orthorhombic space groups have been characterized by X‐ray analysis. The triclinic crystal form, with unit cell dimensions of , diffracts up to 3.2 Å in two directions and to 4.0 Å in the third direction.
Stimulation of ouabain‐sensitive 86Rb+ uptake and Na+,K+‐ATPase α‐subunit phosphorylation by a cAMP‐dependent signalling pathway in intact cells from rat kidney cortex
Authors: Carranza Maria Luisa , Féraille Eric , Kiroytcheva Militza , Rousselot Martine , Favre Hervé
Published: April 2003

We investigated in intact cortical kidney tubules the role of PKA‐mediated phosphorylation in the short‐term control of Na+,K+‐ATPase activity. The phosphorylation level of Na+,K+‐ATPase was evaluated after immunoprecipitation of the enzyme from 32P‐labelled cortical tubules and the cation transport activity of Na+,K+‐ATPase was measured by ouabain‐sensitive 86Rb+ uptake. Incubation of cells with CAMP analogues (8‐bromo‐cAMP, dibutyryl‐cAMP) or with forskolin plus 3‐isobutyl‐1‐methylxanthine increased the phosphorylation level of the Na+,K+‐ATPase α‐subunit and stimulated ouabain‐sensitive 86Rb+ uptake. Inhibition of PKA by H‐89 blocked the effects of dibutyryl‐cAMP on both phosphorylation and 86Rb+ uptake processes. The results suggest that phosphorylation by PKA stimulates the Na+,K+‐ATPase activity.
Postnatal development of rat alpha‐ and beta‐adrenergic receptors: A comparison between tissues
Authors: Morris Margaret J. , Woodcock Elizabeth A.
Published: April 2003

The rates of development of rat kidney α‐ and β‐adrenoceptors were compared with those of heart and lung adrenoceptors in the same animals by direct binding studies using [3H]WB4101 (α1), [3H]yohimbine (α2) and [125I]HYP (β). Kidney α1 and β‐adrenoceptors had reached adult concentrations 7 days after birth, while the α2‐adrenoceptor concentration plateaued at 21 days. Lung β‐adrenoceptor concentration was stable initially, then increased rapidly to adult levels by 18 days. In contrast, heart α1‐and β‐adrenoceptor concentrations were at mature levels at birth. In all tissues studied the increase in noradrenaline concentration was slower than the increases in adrenoceptor concentrations.
Developing rat cerebellum: Glutamine and glutamate influx correlated to the cellular distribution of glutamine synthetase
Authors: de Barry J. , Ghandour M. S. , Gombos G.
Published: April 2003

Glutamate has been suggested to be the neurotransmitter of the granule cells in cerebellar cortex. Autoradiographic studies using very low concentrations (1μM range) of 2‐3‐[3H]l‐glutamate or 2‐3‐[3H]l‐glutamine have shown that both amino acids were preferentially taken up in the molecular layer of the cerebellar cortex of adult rats, but [3H]Glu accumulated essentially in glial cells, while Gln did not show a cellular preference (de Barry et al., Neuroscience 7,1289–1297,1982).

In this paper we show that during development the preferential accumulation of [3H]Glu and [3H]Gln are the same as in the adult but, in addition, at young ages (7–10 days) [3H]Gln accumulated in replicating cells of the external granular layer (EGL). The absence of glutamine synthetase in the EGL cells suggests that this accumulation of exogenous Gln might be used for the synthesis of purines and pyrimidines required for the active multiplication of these cells and is not correlated to neurotransmission. The metabolism of [3H]Gln was slow at young ages and changed during development. The metabolism of the Glu taken up was constant throughout development which is consistent with the hypothesis that high affinity Glu uptake is mainly a glial cell property and that the increasing accumulation rate during development reflects glial maturation.
Intraocular transplants of olfactory neuroepithelium in rat
Authors: Heckroth John A. , Graziadei G. A. Monti , Graziadei Pasquale P. C.
Published: April 2003

Olfactory neuroepithelium of neonatal rat pups has been transplanted in the anterior chamber of the eye of adult rats. Structural and ultrastructural observations at 5, 10, 30, 50, 90 and 120 days show that mature neurons degenerate rapidly in the expiant (before 5 days) while the basal elements proliferate and produce a new population of young neurons between 1 and 10 days. At longer survivals (30–120 days) it is seen that the neurons acquire morphological maturity, and positivity to the olfactory marker protein, as demonstrated by immunohistochemical methods. Our observations show that new neurons can be generated in the transplanted neuroepithelium and that their generation and maturation occurs in the absence of connections with a brain target.
Effects of extended periods of reserpine and α‐methyl‐p‐tyrosine treatment on the development of the putamen in fetal rabbits
Authors: Tennyson Virginia M. , Gershon Perry , Budininkas‐Schoenebeck Mary , Rothman Taube P.
Published: April 2003

Developing nigrostriatal neuroblasts exhibit catecholamine‐induced fluorescence before their axons have left the vicinity of the cell bodies. To evaluate possible developmental effects of dopamine, we have used reserpine and α‐methyl‐p‐tyrosine to deplete dopamine chronically during the development of these axons. We found that dopamine‐induced fluorescence was either absent or markedly decreased in the fetal putamens. To determine whether the absence of fluorescence was due to a reduction of dopamine terminals, the uptake of tritium‐labeled dopamine was measured in the putamen. Uptake of labeled dopamine was significantly depressed in reserpine‐treated fetuses to 70% of that of controls; however, no depression of labeled dopamine was found in the α‐methyl‐p‐tyrosine‐treated fetuses. After both drug treatments, the striatal perikarya were less mature than those of controls. Although we cannot rule out possible non‐specific or toxic effects of the drugs, these observations support the conclusion that presynaptic dopamine may be important for development of target neurons in the neostriatum.
Neurogenesis in the rat neostriatum
Authors: Bayer Shirley A.
Published: April 2003

Neurogenesis in the rat neostriatum was examined with [3H]thymidine autoradiography. For the animals in the prenatal groups, the initial [3H]thymidine exposures were separated by 24 h; they were the offspring of pregnant females given two injections on consecutive embryonic (E) days (E13–E14, E14–E15, … E21–E22). For the animals in the postnatal (P) groups, the initial [3H]thymidine exposures were separated by 48 h, each group receiving four consecutive injections (P0–P3, P2–P5, P4–P7). On P60, the percentage of labeled cells and the proportion of cells originating during either 24 or 48 h periods were quantified at several anatomical levels for both the large and medium‐sized neurons. Neurogenesis of the large neurons occurs mainly between E13 and E16 in a strong caudal‐to‐rostral gradient. The medium‐sized neurons throughout the neostriatum are generated in a prominent ventrolateral‐to‐dorsomedial gradient so that ventrolateral cells originate mainly between E14 and E18, dorsomedial cells between E18 and E21–22 (fewer than 10% originate between P0 and P4). Medium‐sized neurons also show two other gradients. First, there is a superficial‐to‐deep gradient in the anterior part of the caudoputamen, while more posterior levels have a deep‐to‐superficial gradient. Second, anterior parts have a caudal‐to‐rostral gradient while posterior parts have a gradient in the opposite direction. This shift in neurogenetic gradients along both superficial‐deep and rostrocaudal directions is developmental evidence that an anterior ‘caudate’ can be separated from a posterior ‘putamen’ in the rat. Finally, neurogenetic gradients in the medium‐sized caudoputamen neurons can be linked to the patterns of their anatomical interconnections with the substantia nigra.
The influence of neurite‐inducing agents on cholinergic activity in human neuroblastoma cells
Authors: Sternberg Hal , Cole Gregory , Timiras Paola S.
Published: April 2003

Various factors capable of inducing morphological differentiation of neuroblastoma cells were studied to determine whether they may also specifically regulate cholinergic function in human cholinergic neuroblastoma cells MC‐IXC. Choline acetyltransferase (CAT) activity was monitored to reflect cholinergic function while Mg2+ ATPase activity was monitored to reflect effects which are not related specifically to neuronal function. Among the agents, dimethylsulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMA), D‐α‐tocopherol, ascorbic acid and dibutyryl‐cAMP, only low doses of DMSO were found to selectively inhibit CAT activity while Mg2+ ATPase activity along with population growth remained unaffected. Of the three chemically related organic compounds tested (DMSO, DMF, DMA), DMSO was the least potent with regard to inhibition of population growth and Mg2+ ATPase activity while DMA was the most potent inhibitor. Sodium butyrate caused a decline in CAT activity while retinoic acid induced an enhancement. The combination of sodium butyrate with retinoic acid caused an enhancement of CAT activity similar in magnitude to that observed with retinoic acid alone. Lastly, CAT activity was found to be independent of population density unlike that in different neuroblastoma cell lines.8,12,19
Comparison of taurine, hypotaurine and β‐alanine uptake in brain synaptosomal preparations from developing and adult mouse
Authors: Kontro Pirjo
Published: April 2003

The properties of taurine, hypotaurine and β‐alanine uptakes were compared in brain synaptosomal preparations from 6‐day‐old and adult mice. The uptakes of these structurally related amino acids resembled each other, being concentrative, sodium‐dependent and inhibited by the same analogues. The absolute sodium requirement of uptake was already evident in developing brain. The affinity of the lowaffinity uptake for taurine was higher in immature than in adult brain. Both affinity and maximal velocity increased in hypotaurine uptake during development, whereas in β‐alanine uptake only the maximal velocity did so. The efficient synaptosomal taurine and hypotaurine transport systems in immature brain could contribute to the high taurine level in developing brain.
Hypomyelination and recovery of the myelin deficit in heterozygous jimpy mice
Authors: Rosenfeld Jeffrey , Friedrich Victor L.
Published: April 2003

The myelin content of the anterior commissure in female carriers of the jimpy gene (X+Xjp) and in normal male mice (X+Y) was determined using morphometric methods. Young jimpy heterozygotes (X+Xjp), 42–43 days old, exhibit a 33% reduction in myelin area fraction in the anterior limb of the anterior commissure. At older ages (⩾ 145 days), the myelin area fraction in the heterozygotes is not different from control values in the anterior limb and the posterior limb of the anterior commissure. In comparing the young and old jimpy heterozygotes, a significant increase occurs in the myelin area fraction after 43 days of age.

The increase in the myelin area fraction in the anterior limb of the heterozygote may occur in response to the myelin deficit caused by the jimpy mutation and may involve the formation of new myelin. A further study of cellular interactions in the central nervous system of the jimpy heterozygote may provide new insight into mechanisms of myelin formation and remyelination.
Regulation of the amino acid availability in the developing brain. No physiological significance of amino acid competition in experimental hyperphenylalaninemia
Authors: Huether Gerald , Schott Klaus , Sprotte Uwe , Thoemke Frank , Neuhoff Volker
Published: April 2003

Chronic experimental hyperphenylalaninemia in suckling rats causes a depletion of amino acids in the blood and in the brain, and an accumulation of amino acids in the peripheral tissues. The amino acid depletion in the blood is greater than that in the brain. The amino acid accumulating potency of all body tissues is increased by the excess of phenylalanine, most pronounced in the gut, least pronounced in the brain. All body tissues compete for the amino acids circulating in the blood. This competition is enhanced in hyperphenylalaninemia. The brain is at a disadvantage in the competition of the various body tissues for the amino acids available from the common pool. Brain tissue is increasingly depleted of amino acids as the accumulation of amino acids in the peripheral tissues is stimulated in hyperphenylalaninemia.

The depletion of amino acids in the blood and the simultaneous rise of the free amino acid concentrations in the various developing tissues indicates tissue‐specific shifts in the balance between protein synthesis and protein degradation in hyperphenylalaninemia.

There is no indication that amino acid competition at the blood‐brain barrier contributes importantly to the depletion of amino acids in the brain tissue in hyperphenylalaninemic rats. Instead, brain amino acid pools under in vivo steady‐state conditions appear to be primarily regulated by the rate of amino acid utilization by the peripheral tissues.
Changes in ganglioside profile in chick embryo retina: Studies on tissue and cell cultures
Authors: Landa C. A. , Moscona A. A.
Published: April 2003

The developmental profile of gangliosides in the neural retina of the chick embryo is characterized by a progressive decrease in the concentration of GD3 complex from a high level on day 6; by a continuous increase in GD1a concentration; and by less striking increases in GD1b and GT1b concentrations during the growth phase; GM1 increases in the post‐mitotic retina. Gangliosides were analyzed by thin layer chromatography and by densitometry of the TLC plates. (Ganglioside nomenclature is according to Svennerholm.37)

We have examined comparatively ganglioside changes in organ cultures of retina tissue from 6 day embryos (R36), in cell aggregates and in primary monolayer cultures of R26 cells, all maintained for 6 days in vitro. In all cases, the pattern of ganglioside changes was qualitatively similar to that in the retina in vivo. These results suggest that, unlike some other aspects of retina differentiation, the progression of ganglioside changes in the 6–12 day embryonic retina is not critically dependent on histotypic cell organization or on specific contact‐dependent cell interactions; these changes appear to be largely preprogrammed in the cells at some earlier phase of development.
Extracellular matrix glycoprotein (hyaluronectin) in early cerebral development
Authors: Bignami Amico , Delpech Bertrand
Published: April 2003

The distribution of hyaluronectin, an extracellular matrix glycoprotein binding specifically to hyaluronate, was studied by indirect immunofluorescence in the cerebral cortex of the rat embryo. On days 11 and 12 thin strands of immunofluorescent material spanning the entire thickness of the telencephalon were seen. The appearance was similar to that observed with vimentin antisera decorating radial glia. On days 13–15 the primordial plexiform layer of the cerebral cortex was intensely hyaluronectin positive. On day 16 hyaluronectin immunoreactivity was mainly confined to Layer I above and to the intermediate layer below the newly formed cortical plate. It is suggested that in embryonal rat brain HN immunoreactivity is first distributed along radial glia and then accumulates in regions of axonal growth and neuropil formation.
Histogenesis of the vestibular sensory epithelium in organotypic culture of mouse embryo otocysts: A tritiated thymidine autoradiographic study
Authors: Desmadryl Gilles , Raymond Jacqueline , Sans Alain
Published: April 2003

The cytogenesis in the vestibular sensory epithelium of mouse embryo otocysts grown in organ culture was examined using tritiated thymidine autoradiography. Pulse‐labeling with [3H]‐thymidine was applied either in vivo, at various intervals before explantation, or in vitro at specific stages of development. Observations of the development in vitro showed that the cytogenesis and cytodifferentiation of vestibular sensory cells were disturbed by explantation. By varying the intervals between the [3H]thymidine exposure and the date of explantation, we were able to demonstrate that explantation itself caused a significant decrease in the mitotic and the postmitotic phases of the hair cell precursors. Labeling of the expiants excised on day 13 of gestation revealed that precursors of the hair cells were progressively losing their mitotic capacity in vitro. In contrast with this finding, precursors of the supporting cells were less affected by explantation and culture conditions and they retained the capacity for survival, proliferation and differentiation.
Developmental changes of putreanine in vertebrate brains
Authors: Seiler N. , Sarhan S. , Knodgen B.
Published: April 2003

A method for the determination of putreanine has been developed, based on the separation of ion pairs with octanesulfonic acid on a reversed phase column. The method has been used to determine the developmental pattern of this amino acid in chick and rat brain.
The postnatal development of glial fibrillary acidic protein and neurofilament triplet proteins in rat brain stem
Authors: Harry G. Jean , Goodrum Jeffry F. , Morell Pierre
Published: April 2003

Cytoskeletal preparations containing both the glial fibrillary acidic protein and the neurofilament triplet proteins were prepared from brain stems of rats at different ages and the individual peptides separated in polyacrylamide gels. Stained peptide bands were quantitated as the area under peaks generated by densitometric scanning. Peak areas were converted to grams of protein based on total gel dye binding and total protein applied to the gels. Between 5 and 30 days, the concentration of the peptide (g of peptide/mg of tissue protein) of apparent molecular weight 51,000 (corresponding to the glial fibrillary acidic protein), increased 3 fold. The corresponding increase in total concentration of the three peptides corresponding to the neurofilament proteins was 4.5 fold. However, the increase in concentration of the individual neurofilament peptides was each different. Very little of the apparent molecular weight 210,000 neurofilament peptide was present at 5 days and its concentration increased 11 fold by 30 days compared to about 3.5 fold for the other two neurofilament peptides. These results are in general agreement with studies using immunological techniques and the methods have the advantages of using readily available techniques and allowing the simultaneous comparison of both neuronal and glial specific filaments during development.
Transient expression of neurofilament protein without filament formation in purkinje cell development
Authors: Bignami Amico , Grossi Milena , Dahl Doris
Published: April 2003

Purkinje cell bodies and dendrites in the chick embryo stained intensely by immunofluorescence and by the Avidin‐Biotin Complex (ABC) method using monoclonal and polyclonal antibodies to the neurofilament (NF) proteins. On day 20 (the day before hatching) NF immunoreactivity markedly decreased concomitant with the first appearance of NF‐positive basket axons in the molecular and Purkinje cell layers. On postnatal day 3, as in mature avian cerebellum, NF‐negative Purkinje cells were surrounded by NF‐positive baskets. Cytoplasmic 10 nm filaments were not observed in immature and mature Purkinje cells by electron microscopy. Basket axons in the hen were packed with 10 nm filaments.
Development of specificity and stereoselectivity of rat brain dopamine receptors
Authors: Miller Jeannette C. , Friedhoff Arnold J.
Published: April 2003

Prenatal exposure to the neuroleptic haloperidol has been reported to produce an enduring decrement in the number of dopamine D2 receptors in rat striatum and a persistent diminution of a dopamine dependent behavior, stereotypy.17 The ontogeny of rat brain dopamine binding sites has been studied in terms of the kinetic properties and phenotypic specificity in rat fetal brain through early postnatal development. Sites showing some properties of the D2 binding site can be found prior to gestational day (GD) 18, can be labeled with [3H]dopamine or [3H]spiroperidol and can he displaced with dopaminergic agonists and antagonists.5 Saturation kinetics for specific [3H]spiroperidol has previously been found to occur on or about GD 18.1.5 It is of interest that the critical period for the prenatal effect of haloperidol to reduce striatal D2 binding sites. CD's 15–18.18 coincides with the period during which dopamine binding sites lack true specificity, but can be labeled with dopaminergic ligands.

In these experiments the development of stereoselectivity of brain dopamine binding sites has been examined. When rat mothers were given either the neuroleptic (+)‐butaclamol or its therapeutically inactive isomer (−)‐butaclamol during the critical period CD's 15–18. the number of [3H]spiroperidol binding sites in striata of offspring was significantly reduced by both stereoisomers. This is in marked contrast to the postnatal treatment effect by a neuroleptic in which upregulation of striatal D2 binding sites occurs only by treatment with the therapeutically active isomer (+)‐butaclamol. In vitro studies of the direct effect of the stereoisomers of butaclamol indicate that the recognition sites detected during fetal brain development with [3H]spiroperidol do not distinguish between the isomers of butaclamol. The point at which stereoselectivity is apparent also appears to be the point at which the prenatal neuroleptic effect is no longer operative and the mature response to increase the number of dopamine binding sites occurs.
Regulation of sympathetic trophic factors in smooth muscle
Authors: Rush R.A. , Abrahamson I.K. , Belford D.A. , Murdoch S.Y. , Wilson P.A.
Published: April 2003

The level and nature of trophic activity present in the chicken expansor secundariorum muscle has been shown to he altered by denervation. This muscle receives a dense, sympathetic innervation and contains high concentrations of trophic factors, which were found to be immunologically and functionally distinct from mouse Nerve Growth Factor. In young birds, denervation increased the number of neurons which could be supported by muscle extract. This difference was apparent with regard to E8 to E16 sympathetic neurons. Innervated but not denervated extract was additive with NGF in promoting neurite outgrowth. In contrast, when extracts of denervated and innervated muscle from mature birds were examined, no difference was seen in the number of neurons supported by each extract. However when the denervated and innervated extracts from mature birds were combined more neurons were supported than by a saturating dose of either extract alone. Furthermore, muscle from mature birds responded to denervation only between 2 and 9 days, whereas in young birds the effect was apparent for at least 3 weeks. Analysis of intact, control muscles during the tirst 8 weeks posthatch demonstrated that the number of neurons that could be supported by the individual extracts varied with the age of the bird.

It is concluded that denervation does not in all instances lead to an increase in trophic activity, but does produce a change in the nature of the activity present, such that a different neuronal subpopulation may be supported. In addition, the response of the muscle depends on the age of the birds at the time of denervation. and this may be due to an alteration in the type of activity present in the muscle during the first few weeks after hatch.
Expression of cholinergic markers in the developing chick embryo spinal cord
Authors: Thiriet G. , Kempf J. , Ebel A.
Published: April 2003

The expression of cholinergic neurotransmission in the developing spinal cord was followed with pre‐ and postsynaptic cholinergic markers and histoautoradiographic determinations of cholinergic receptors and ultrastructural studies.

Two distinct steps in the development of cholinergic markers were evident. The first step of cholinergic expression occurs early in development and is characterized by a sudden and large increase in choline acetyltransferase activity, whereas the high affinity choline uptake mechanism remains undetectable and few muscarinic receptors are detectable. This phenomenon possibly reflects the expression of high choline acetyltransferase gene activity in developing neurons which are still not synaptically connected. The second step is also characterized by a sharp rise of choline acetyltransferase activity. This rise parallels an active development of high affinity choline uptake and big increase in both number and density of muscarinic receptors. Also nicotinic receptors increase, as revealed by histoautoradiography. Specific morphogenetic events, such as the increase of synaptic junctions with postsynaptic thickenings and numerous presynaptic clear vesicles, occur at the same time. Such interactions may contribute to the full maturity of cholinergic neurotransmission of the spinal cord.
Influence of various growth factors and conditions on development of resting membrane potential and its electrogenic pump component of cultured rat skeletal myotubes
Authors: Brodie Chaya , Sampson S.R.
Published: April 2003

The effects of different growth factors and growth conditions were studied on the development of resting membrane potential and its electrogenic—ouabain‐sensitive—pump component in cultured rat myotubes. Resting potential and its electrogenic pump component were dependent on the initial plating density of the myotubes, both values increasing with increasing density. Medium from cells plated at high density, when used to replace the medium of low density cells, increased both the resting potential and its electrogenic pump component of low density myotubes. Treatment of myotubes with cytosine‐arabinoside delayed the appearance of [3H]ouabain binding sites and electrogenic pump component of resting potential, but by 8 days in culture there was no difference between treated and control cells. Similarly, cells plated initially in 5% horse serum developed resting potential and its electrogenic pump component more slowly than those in 15% horse serum, but by 8–10 days in vitro, the differences were no longer apparent. Chick embryo extract was found to have little, if any, influence on development of resting potential and its electrogenic pump component. We conclude that the different growth conditions and factors to the extent that they influence membrane potential, do so by altering the time of appearance of Na‐K ATPase, the activity of which contributes a considerable component to resting potential.
Effects of opiates on the growth of neuron‐enriched cultures from chick embryonic brain
Authors: Sakellaridis Nikos , Mangoura Dimitra , Vernadakis Antonia
Published: April 2003

Neuron‐enriched cultures derived from 6‐day‐old chick embryo cerebral hemispheres were treated with morphine or methadone, 10−5 M or 10−6 M, on days 4–6 or 6–8 in culture and were evaluated morphologically and biochemically at day 9 using phase contrast microscopy and choline acetyltransferase activity (ChAT) as a cholinergic marker. The treatment of the cultures with morphine markedly affected their growth pattern; specifically, we observed an increased number of flat cells presumptively glia, and aggregates sided by flat cells and devoid of thick bundles of neuritic processes that normally characterize neuron‐enriched cultures. These morphologic changes were reflected in a drastic decrease of ChAT activity in cultures treated from day 4 to day 6 but not from 6 to 8. In contrast to morphine, exposure to 10−6 M methadone from day 4 to day 6 resulted in reduced ChAT activity but the growth pattern of the cultures remained morphologically intact. We suggest that morphine exerts a general neurotoxic effect whereas methadone may affect some specific cholinergic function.
Sex differences in nerve growth factor levels in superior cervical ganglia and pineals
Authors: Wright L. L. , Beck C. , Perez‐Polo J. R.
Published: April 2003

The current studies were undertaken to determine whether males or neonatally testosterone‐treated rats of either gender have elevated endogenous levels of NGF in the SCG and one of its targets, the pineal gland. The ages studied were 5 days postnatal, which is at the peak of normal neuron death in the SCG but before a significant gender difference is present; 15 days, when normal neuron death is largely complete and males have more SCG neurons than females; and 30 days, when target innervation has matured.

At 5 days, while neuron death is occurring, but before there is a significant gender difference in neuron number in the SCG, pineal glands and SCGs of males had higher NGF content than those of females. The increased NGF in the ganglia of males at the time that these neurons are undergoing neuron death may play a role in the development of the sex difference in SCG neuron numbers. At 15 days, females had more NGF in their pineal glands and SCGs than did males, even though males have significantly more SCG neurons at this age than do females. This gender difference in the developmental course of NGF content could promote the survival of different populations of neurons in males and females. By 30 days, SCG and pineal NGF content of males was almost twice that of females. This is consistent with the presence of more neurons in the SCGs of males at this age.

Both the pineal gland and the SCG showed a loss of approximately 80% content of NGF during the first postnatal month. In males, this loss occurred between postnatal days 5 and 15, while in females, the drop in NGF content occurred between postnatal days 15 and 30. Treatment with testosterone from birth reduced NGF content in the SCGs of both males and females at 5 days of age. The depression of NGF levels by testosterone treatment may reflect a further acceleration of the developmental fall of NGC levels.
Effects of triiodothyronine on the development of GFAP‐immunoreactivity and cat‐activity in monolayer cultures of embryonal rat forebrain cells
Authors: Madarász Emilia
Published: April 2003

Dose‐dependent actions of triiodothyronine were studied in serum‐containing primary cultures of embryonal rat forebrain cells. Triiodothyronine at concentrations exceeding the normal medium concentration by 2 and 5 nM failed to cause significant changes in the development of CAT‐activity and GFAP‐immunoreactivity. In the presence of additional 10 and 20 nM T3, however, CAT‐activity was increased and GFAP‐immunoreactivity was decreased in comparison to cultures maintained with ‘normal’ (10% FCS‐containing) media.
Correlation of clustering peak density and total amount of acetylcholine receptor on cultured mouse myotubes
Authors: Shikada K. , Kimura I. , Kimura M.
Published: April 2003

The development of acetylcholine receptor (AChR) and its clustering were studied quantitatively on mouse myotubes in nerve‐muscle co‐cultures. AChR was visualized by fluorescence‐labeled antibodies (F‐Ab) against crude AChR or fluorescence‐labeled α‐bungarotoxin (F‐α‐BuTX). The F‐Ab stain was observed throughout the entire surface of the myotube at day 8 and appeared clustered at day 13. Both peak density and total amount of fluorescence in F‐Ab stained myotubes were plotted against days in culture. Both fluorescence indices markedly increased from days 8 to 13 of culture were greater in extent in myotubes incubated in the presence of spinal cord explant, as compared with its absence. Similar results were observed in myotubes stained with F‐α‐BuTX. d‐Tubocurarine (d‐TC, 0.1 mg/ml) and native α‐BuTX (1 μg/ml) clearly inhibited both the total amount of fluorescence and the development of peak fluorescence density in the F‐Ab stained myotubes. But the inhibition by d‐TC appeared at the later day in culture than α‐BuTX did. Low temperature (28°c) and cholesterol (1 μg/ml) treatment inhibited peak fluorescence density without affecting total amount of fluorescence. These results show that the development of ACh can be characterized both by clustering peak density (indicating the lateral mobility of AChR) and by total amount of fluorescence.
Development of serotoninergic neurons from ventricular cells of the mouse neural plate in vitro
Authors: Buse Eberhard
Published: April 2003

Cephalic neural plates and neural tubes of mice (pros‐ and rhombencephalic anlagen), developmental stages Theiler 11–18 [Th 11–18; embryonic day –11 (E–11)], were prepared and cultured in a plasma clot with horse serum‐containing MEM medium. Differentiation of the ventricular cells was studied in order to investigate the expression of serotoninergic properties. Serotoninergic neurons were not detected in preparations derived from neural plates of stage Th 11 (E), but were demonstrated in increasing numbers from the early stage Th 12 (E8) onwards. They exclusively originated from the rhombencephalic floor caudal to the mesencephalic flexure. The serotoninergic neurons developed from these areas, irrespective of whether being cultured in their natural position within the neural plate, or separated as microcultures, or transplanted into the prosencephalic anlage. Every other region of the neural plate remained free of serotoninergic neurons.

The in vitro findings are highly reproducible due to the following properties: the morphological and immunocytochemical peculiarities of the serotoninergic neurons, their tendency to appear in increasing numbers with age, their localization within the cultured neural plates and their appearance in all cultures from stage Th 12 (E8) on. Due to these findings it is considered possible that the progenitor cells of serotoninergic neurons might already have been determined within distinct areas in the mouse neural plates as early as stage Th 12 (E8).
Ganglioside potentiation of NGF‐independent conditioned medium enhancement of neuritic outgrowth from spinal cord and ciliary ganglia explants
Authors: Spoerri P. E. , Roisen F. J.
Published: April 2003

Culture medium conditioned (CM) by embryonic chick skeletal muscle or RN22 Schwannoma cells enhanced dramatically the neuritic development of chick embryonic spinal cord slices explanted onto a collagen substratum. The addition of a mixture of bovine brain gangliosides (BBG) or the monosialoganglioside GM1 to this medium potentiated the nerve growth factor (NGF)‐independent CM‐mediated neuritogenesis. A 3–4 fold increase in spinal cord outgrowth was due to increased neurite number, length and branching. The ability of the gangliosides to potentiate the positive neuritogenic action of CM was not limited solely to spinal cord cultures since similar results were obtained in parallel studies employing organized cultures of embryonic chick ciliary ganglia. These studies demonstrate the ability of gangliosides to enhance the trophic action of factor(s) present in CM. They suggest further that gangliosides may play a modulatory role in the development of the nervous system.