Showing papers by "Collège de France published in 1991"
TL;DR: In this paper, the steric repulsion free energy and van der Waals attraction free energy of polyethylene oxide (PEO) chains were calculated as a function of surface density and chain length of PEO.
1,507 citations
TL;DR: Projections of the hippocampal formation to the prefrontal cortex were visualized in the rat by means of the anterograde tracer Phaseolus vulgaris‐leucoagglutinin and the intermediate portion of the subiculum projects more densely and diffusely than its dorsal and ventral portions.
Abstract: Projections of the hippocampal formation to the prefrontal cortex were visualized in the rat by means of the anterograde tracer Phaseolus vulgaris-leucoagglutinin. These projections distribute only to the prelimbic and the medial orbital cortices and arise exclusively from restricted portions of field CA1 of the Ammon's horn and the subiculum. The most dorsal portion of CA1 does not contribute fibers to this projection. In the subiculum, its origin is restricted to the proximal half, i.e., the portion that directly borders field CA1. Fibers from field CA1 and the subiculum have comparable distribution patterns in the prelimbic and medial orbital cortices. The density and distribution in the prefrontal cortex of the projections from the proximal portion of the subiculum depends on the location of the injections along the dorsoventral axis of the hippocampal formation: the intermediate portion of the subiculum projects more densely and diffusely than its dorsal and ventral portions. In the prelimbic cortex, labeled fibers are present in all layers, showing marked morphological differences in deep versus superficial layers. In layers V and VI, most of the fibers are vertically oriented, while in layers II and III they are short and oriented towards the pial surface. Although no clear differences in terminal distribution were observed along the rostrocaudal extent of the prelimbic cortex, its dorsal and ventral portions show different innervation patterns. In the ventral portion of the prelimbic cortex, varicose fibers and terminal arborizations were present in all cortical layers, deep (V and VI) as well as superficial (II and III). In its dorsal part, the innervation was less dense and mostly present in the deep layers (V and VI). The fiber and terminal distribution in the medial orbital cortex was diffuse in all layers with a slight preference for layers deep to layer II.
833 citations
TL;DR: Comparison of the human and rat genetic maps indicates that BP/SP-1 could reside on human chromosome 17q in a region that also contains the angiotensin l-converting enzyme gene (ACE)8, and is therefore a candidate gene in primary hypertension.
Abstract: The spontaneously hypertensive rat and the stroke-prone spontaneously hypertensive rat are useful models for human hypertension. In these strains hypertension is a polygenic trait, in which both autosomal and sex-linked genes can influence blood pressure. Linkage studies in crosses between the stroke-prone spontaneously hypertensive rat and the normotensive control strain Wistar-Kyoto have led to the localization of two genes, BP/SP-1 and BP/SP-2, that contribute significantly to blood pressure variation in the F2 population. BP/SP-1 and BP/SP-2 were assigned to rat chromosomes 10 and X, respectively. Comparison of the human and rat genetic maps indicates that BP/SP-1 could reside on human chromosome 17q in a region that also contains the angiotensin I-converting enzyme gene (ACE). This encodes a key enzyme of the renin-angiotensin system, and is therefore a candidate gene in primary hypertension. A rat microsatellite marker of ACE was mapped to rat chromosome 10 within the region containing BP/SP-1.
611 citations
TL;DR: Results strongly suggest that gap junctions in astrocytes have a 50-60 pS unitary conductance associated with channels composed of Cx43 protein.
358 citations
TL;DR: The results indicate that some of the NMDA receptors involved in the facilitation of DA release are located on DA nerve terminals, and these presynaptic receptors exhibit pharmacological properties similar to those described in electro‐physiological studies for postsynapticNMDA receptors.
Abstract: The N-methyl-D-aspartate (NMDA) receptor-mediated regulation of the release of newly synthesized [3H]dopamine [( 3H]DA) was studied in vitro, both on rat striatal slices using a new microsuperfusion device and on rat striatal synaptosomes. Under Mg2(+)-free medium conditions, the NMDA (5 X 10(-5) M)-evoked release of [3H]DA from slices was found to be partly insensitive to tetrodotoxin (TTX). This TTX-resistant stimulatory effect of NMDA was blocked by either Mg2+ (10(-3) M) or the noncompetitive antagonist MK-801 (10(-6) M). In addition, the TTX-resistant NMDA-evoked response could be potentiated by glycine (10(-6) M) in the presence of strychnine (10(-6) M). The coapplication of NMDA (5 X 10(-5) M) and glycine (10(-6) M) stimulated the release of [3H]DA from striatal synaptosomes. This effect was blocked by Mg2+ (10(-3) M) or MK-801 (10(-5) M). These results indicate that some of the NMDA receptors involved in the facilitation of DA release are located on DA nerve terminals. These presynaptic receptors exhibit pharmacological properties similar to those described in electrophysiological studies for postsynaptic NMDA receptors.
331 citations
TL;DR: In this article, the authors argue that science is a social field of forces, struggles, and relationships that is defined at every moment by the relations of power among the protagonists, and that scientific choices are guided by taken-for-granted assumptions, interactive with practices, as to what constitutes real and important problems, valid methods, and authentic knowledge.
Abstract: Science is a social field of forces, struggles, and relationships that is defined at every moment by the relations of power among the protagonists. Scientific choices are guided by taken-for-granted assumptions, interactive with practices, as to what constitutes real and important problems, valid methods, and authentic knowledge. Such choices also are shaped by the social capital controlled by various positions and stances within the field. This complex and dynamic representation thus simultaneously rejects both the absolutist-idealist conception of the immanent development of science and the historicist relativism of those who consider science as purely a conventional social construct. The strategies used in science are at once social and intellectual; for example, strategies that are founded on implicit agreement with the established scientific order are thereby in affinity with the positions of power within the field itself. In established scientific fields of high autonomy, “revolutions” no longer are necessarily at the same time political ruptures but rather are generated within the field themselves: the field becomes the site of a permanent revolution. Under certain conditions, then, strategies used in struggles for symbolic power transcend themselves as they are subjected to the crisscrossing censorship that represents the constitutive reason of the field. The necessary and sufficient condition for this critical correction is a social organization such that each participant can realize specific interest only by mobilizing all the scientific resources available for overcoming the obstacles shared by all his or her competitors. Thus, the type of analysis here illustrated does not lead to reductive bias or sociologism that would undermine its own foundations. Rather it points to a comprehensive and reflexive objectivism that opens up a liberating collective self-analysis.
300 citations
TL;DR: There is no good reason to believe that enlarged browridges in living and/or fossil primates are structural adaptations to counter intense masticatory forces.
Abstract: The purpose of this study is to test various masticatory-stress hypotheses about the evolution and function of well-developed browridges of higher primates. This was done by measuring and analyzing patterns of in vivo bone strain recorded from three-element rosette strain gages bonded to the supraorbital region and to other portions of the bony face of Macaca fascicularis and Papio anubis during mastication and incision. The magnitude and direction of the principal strains recorded support Endo's hypothesis that the supraorbital region during mastication and incision is bent in the frontal plane (Endo, 1966). Our data do not, however, support his hypothesis that the supraorbital region is bent more during incision than during mastication. The data also demonstrate that overall levels of supraorbital strain are not larger in more prognathic subjects. Most importantly, the data indicate that the supraorbital region of nonhuman catarrhines is strained very little during mastication and incision. This indicates that there is much more supraorbital bone than is necessary both to counter masticatory loads and to provide an adequate safety factor to failure for these loads. This in turn suggests that the macaque and baboon browridges can be considerably reduced in size and still maintain these required structural characteristics. Thus, our experiments provide no support whatsoever for those hypotheses that directly link browridge morphology to masticatory stress (cf. Endo, 1966; Russell, 1983, 1985). A recent review of Endo's original work indicates that this latter statement is also true for humans (Picq and Hylander, 1989). We conclude, therefore, that there is no good reason to believe that enlarged browridges in living and/or fossil primates are structural adaptations to counter intense masticatory forces. The evolution of browridge morphology in primates is best explained on the basis of factors related to the position of the brain relative to the orbits (Moss and Young, 1960). When these structures are widely separated, as in gorillas, the large intervening space must be bridged with bone. In addition, enough bone must be present within the supraorbital and bridged regions to prevent structural failure due to non-masticatory external forces associated with highly active primates (e.g., accidental traumatic forces applied to the orbits and neurocranium). This requirement results in both pronounced browridges and in much more supraorbital bone than is necessary to counter routine cyclical stress during mastication and incision. This in turn explains why bone strains recorded from the supraorbital region are extremely small relative to other portions of the primate face during mastication and incision.
214 citations
TL;DR: The results suggest that brain macrophages could favour the appearance of neuroregressive events which occur either during neurogenesis or in neurodegenerative diseases, implying intracerebral recruitment of mononuclear phagocytes.
Abstract: Brain macrophages are transiently present in different regions of the central nervous system during development or in the course of tissue remodelling following various types of injuries. To investigate the influence of these phagocytes on neuronal growth and survival, brain macrophages stemming from the cerebral cortex of rat embryos were added to neuronal primary cultures. A neurotoxic effect of brain macrophages was demonstrated by the reduction of the number of neurons bearing neurites within two days of contact between the two cell types. Neuronal death and phagocytosis were also directly observed in video recordings of living cultures. This toxicity involved the production by brain macrophages of reactive oxygen intermediates, as shown by the protective effect of catalase, a scavenger of H2O2. In addition, the respiratory bursts of brain macrophages were stimulated in the presence of neurons. These results suggest that brain macrophages could favour the appearance of neuroregressive events which occur either during neurogenesis or in neurodegenerative diseases, implying intracerebral recruitment of mononuclear phagocytes.
202 citations
TL;DR: The observed laws of the scaling laws between the thickness of a grafted polymer layer h, its graft density \ensuremath{\sigma}, and the molecular weight of the grafted chains M have been determined for polydimethylsiloxane chains end grafted on porous silica.
Abstract: Using small-angle neutron-scattering techniques, the scaling laws between the thickness of a grafted polymer layer h, its graft density \ensuremath{\sigma}, and the molecular weight of the grafted chains M have been determined for polydimethylsiloxane chains end grafted on porous silica The observed laws h\ensuremath{\approxeq}M\ensuremath{\sigma} in bad solvent and h\ensuremath{\approxeq}M${\mathrm{\ensuremath{\sigma}}}^{1/3}$ in good solvent provide the first experimental evidence of the ``brush'' regime, where the grafted chains, confined by their neighbors, are stretched normal to the surface
182 citations
TL;DR: A new, simple model is suggested, which features four hydrophobic α-helices spanning the whole thickness of the lipid bilayer and the effect or absence of various PLP mutations is discussed in the frame, of the proposed 4-helix topology.
Abstract: Several conflicting models have been proposed for the membrane arrangement of the major myelin proteolipid (PLP) We have compared features of the sequence of PLP with those of other eukaryotic integral membrane proteins, with the view of identifying the most likely transmembrane topology A new, simple model is suggested, which features four hydrophobic α-helices spanning the whole thickness of the lipid bilayer Its orientation may be such that both the N-and C-termini face the cytosol None of the biochemical, biophysical or immunological experiments hitherto reported provides incontrovertible evidence against the model The effect or absence thereof of various PLP mutations is discussed in the frame, of the proposed 4-helix topology
138 citations
TL;DR: It is demonstrated in rats that acute increases in dopamine transmission in this site by local injections of Amphetamine inhibit the known locomotor‐activating effects of amphetamine in the nucleus accumbens (N.Acc), and suggested that it is acting at D‐1 dopamine receptors in this sites.
Abstract: The possibility that the dopaminergic neurons innervating the medial prefrontal cortex (mPFC) can inhibit locomotor behaviour has been suggested in several studies. The evidence remains indirect, however, because the manipulations tested aimed exclusively at permanently depleting mPFC dopamine. Here we demonstrate in rats that acute increases in dopamine transmission in this site by local injections of amphetamine inhibit the known locomotor-activating effects of amphetamine in the nucleus accumbens (N.Acc.). Further, intra-mPFC injections of the D-1 dopamine receptor antagonist SCH-23390, but not other dopamine antagonists with greater affinities for noradrenergic, serotonergic and D-2 dopamine receptors, enhanced the locomotion induced by intra-N.Acc. amphetamine. These findings provide direct evidence for the inhibition of locomotor activity by mPFC dopamine and suggest that it is acting at D-1 dopamine receptors in this site.
TL;DR: Two novel glial‐specific markers, expressed earlier than any previously described myelin components, have been identified and partly characterised and are related to the divergence of glial and neuronal cell lineages.
Abstract: We have been studying how and when the different peripheral glial cell lineages individualize during avian embryonic development. Three different and complementary experimental approaches were used for this purpose: (1) the quail/chick chimera system allowed the tracing in vivo of the origin of the various types of peripheral glial cells (Schwann cells of nerves, satellite glial cells of sensory and autonomic ganglia, and enteric glial cells), and the analysis of the non-neuronal cell population of ganglia; (2) characterisation of early cell-type specific markers that discriminate between the different glial cell subpopulations; and (3) analysis of the progeny of neural crest cells in clonal cultures. As a result of these approaches, two novel glial-specific markers, expressed earlier than any previously described myelin components, have been identified and partly characterised. The divergence of glial and neuronal cell lineages is a process that is not completely terminated during the phase of neural crest migration. Whereas some cells are apparently already totally committed to a glial fate at this stage, others retain dual neuronal/glial potentialities.
TL;DR: The modulation of DA release by cortical glutamate and/or aspartate-containing inputs through NMDA receptors in the matrix appears to be partly distinct from that observed in the striosomes, providing some functional basis for the histochemical striatal heterogeneity.
Abstract: Striosome- and matrix-enriched striatal zones were defined in coronal and sagittal brain sections of the rat, on the basis of 3H-naloxone binding to mu-opiate receptors (a striosome-specific marker). Then, using a new in vitro microsuperfusion device, the NMDA (50 microM)- evoked release of newly synthesized 3H-dopamine (3H-DA) was examined in these four striatal areas under Mg(2+)-free conditions. The amplitudes of the responses were different in striosomal (171 +/- 6% and 161 +/- 5% of the spontaneous release) than in matrix areas (223 +/- 6% and 248 +/- 12%), even when glycine (1 or 100 microM) was coapplied (in the presence of 1 microM strychnine). In the four areas, the NMDA-evoked release of 3H-DA was blocked completely by Mg2+ (1 mM) or (+)-5-methyl- 10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine maleate (MK-801; 1 microM) and almost totally abolished by kynurenate (100 microM). Because the tetrodotoxin (TTX)-resistant NMDA-evoked release of 3H-DA was similar in striosome- (148 +/- 5% and 152 +/- 6%) or matrix- enriched (161 +/- 5% and 156 +/- 7%) areas, the indirect (TTX- sensitive) component of NMDA-evoked responses, which involves striatal neurons and/or afferent fibers, seems more important in the matrix- than in the striosome-enriched areas. The modulation of DA release by cortical glutamate and/or aspartate-containing inputs through NMDA receptors in the matrix appears thus to be partly distinct from that observed in the striosomes, providing some functional basis for the histochemical striatal heterogeneity.
TL;DR: In this paper, the authors report measurements of b-quark and B-hadron production in pp collisions at √s=630 GeV and use muon samples to extract beauty production cross-sections over a wide range of transverse momentum in the central rapidity range |y| < 1.5.
TL;DR: The results demonstrate antagonist effects of fibronectin and laminin on the in vitro differentiation of brain macrophages towards a "resting" phenotype, which shares several properties with the ramified microglia present in the adult brain.
TL;DR: It is shown here that isolated peripherin binds selectively to mammalian lamin B under in vitro conditions, and it is demonstrated that a synthetic peptide, representing the proximal part of peripherin's tail domain (P1), also associates with mammalian lamination B in a saturable, cooperative, and specific fashion.
TL;DR: The immunohistochemical analyses carried out on chimeras generated in experiment V revealed the existence of fibers in marginal zones prior to the onset of the migration of cell bodies, and support the suggestion that such tangential fibers serve as guidance substrates for the subpial migrations of cells in the medulla oblongata.
Abstract: We have tried to obtain new insight into the development of the medulla oblongata by using the quail-to-chick chimera system. Five types of isotopic and isochrome grafts were carried out, between quail and chick embryos, at the 10- to 12-somite stage: exchanges of (I) the entire myelencephalon, (II) the dorsal half of the myelencephalon, (III) the ventral half of the myelencephalon, (IV) the right half of the myelencephalon and (V) the dorsal quarter of the myelencephalon. Before analyzing the chimeric embryos, we studied the ontogeny of the various nuclei in the medulla oblongata of normal birds. The first appearance of nuclei in quail embryos preceded in many cases that of their chick counterpart by 12 to 24 h. The adult pattern of the nuclei was established by E8 in quail and E9 in chick. Similarly, during early development of chimeras, the migration of quail cells began earlier than that of chick cells. This shows that the species specific temporal sequence of proliferation and migration is not significantly altered by transplantation into the host. The possibility of grafting selectively the ventral or dorsal half of the neural tube allowed us to distinguish the fate of the cells belonging respectively to the alar and the basal plate. The nuclei with a total or partial motor function, such as the nucleus nervi abducentis, the nucleus nervi facialis, the nucleus nervi glossopharyngei and the nucleus motorius dorsalis nervi vagi, have either an exclusive or predominant origin from the basal plate. In contrast, the nuclei with essentially or exclusively sensory components (i.e., nucleus angularis, nucleus laminaris, nucleus magnocellularis) arise from the alar plate. The reticular formation such as the nucleus reticularis gigantocellularis and the nucleus reticularis subtrigeminalis was strikingly mixed, with both alar and basal plate origin of neurons. Active dorsoventral migrations of cells originating migrations from the dorsal neural tube, the “rhombic lip”, contribute the ventral nuclei (i.e., nuclei pontis medialis, lateralis and olivaris inferior), whose functions are essentially associative. This study shows different types of cell migration. Dorsoventral and ventrodorsal movements are essentially active from E5 to E8. In the medulla oblongata, the dorsoventral stream is highly predominant. From E8 to E9, cells belonging to the marginal stream cross the midline laterally in both directions. Beyond E12, longitudinal migrations occur ventrally in both rostrocaudal and caudorostral directions. The immunohistochemical analyses carried out on chimeras generated in experiment V revealed the existence of fibers in marginal zones prior to the onset of the migration of cell bodies. These observations support the suggestion that such tangential fibers serve as guidance substrates for the subpial migrations of cells in the medulla oblongata.
TL;DR: The first stages of testicular differentiation in the rat are described, with special emphasis on the ultrastructural aspects, and a possible role of the Sertoli cells in the subsequent organogenesis of the testis is suggested.
Abstract: The fetal testis is not merely a precursor of the adult organ: it is indeed an endocrine gland whose function is the masculinization of the fetus. It differs physiologically and morphologically from the adult testis. In this paper, the first stages of testicular differentiation in the rat are described, with special emphasis on the ultrastructural aspects. At the stage of 13.5 days after fertilization, the first Sertoli cells differentiate; they are characterized by a voluminous and little electron dense cytoplasm, a well-developed RER formed by vesicles and short cisternae filled with a flocculent material. Progressively, they polarize and adhere to one another by adherens-like junctions and cytoplasmic interdigitations to form the differentiating seminiferous cords. In the basal part of the Sertoli cells, a mat of microfilaments differentiates under the plasmalemma, while cytoplasmic blebs protruding in the extracellular space tend to disappear. A continuous basal lamina delineating the seminiferous cords begins to appear on day 14.5 and becomes widespread on day 15.5. These observations, when compared with other data from the literature, emphasize the fact that the differentiation of the Sertoli cells is the first morphological event during testicular differentiation. A possible role of the Sertoli cells in the subsequent organogenesis of the testis is suggested.
TL;DR: The results strongly suggest that the epithelio‐mesenchymal interactions have an essential role on the regulation of Quox 7 gene, the product of which seems to be, in turn, necessary for the execution of the skeletal developmental program in the facial area.
Abstract: In higher vertebrates, branchial arch mesenchyme (ectomesenchyme) is derived from the cephalic neural crest The ectomesenchyme of the mandibular arch yields the Meckel's cartilage and several membrane bones We previously reported the isolation of a quail homeobox gene, Quox 7 In common with its mouse counterpart Hox 7, Quox 7 is highly expressed in the medioventral part of the mandibular arch and later in the precursor cells of the membrane bones Since bone differentiation from ectomesenchyme is strictly dependent upon a signal provided by the mandibular epithelium, we decided to see whether the regulation of Quox 7 gene activity might be correlated with epithelio--mesenchymal interactions Quox 7 expression was studied in E3 mandibular ectomesenchyme cultured in vitro or grafted on the chick chorioallantoic membrane either alone or recombined with the homotopic and heterotopic epithelia We found that Quox 7 mRNA was undetectable after 48 h in cultures of mesenchyme alone while it remained abundant in non-cartilaginous tissue of the mandibular arch ectomesenchyme recombined with its own epithelium The signal provided by the mandibular epithelium for Quox 7 expression can also arise from various heterotopic epithelia, eg of dorsal or ventral body wall and of limb bud Thus the effect of the epithelium on Quox 7 expression in mesenchymal cells strictly parallels that on bone formation These results strongly suggest that the epithelio-mesenchymal interactions have an essential role on the regulation of Quox 7 gene, the product of which seems to be, in turn, necessary for the execution of the skeletal developmental program in the facial area
TL;DR: High‐affinity specific receptors of endothelin ( ET‐1) were identified on primary cultures of mouse embryo striatal astrocytes by binding experiments performed with 125I‐ET‐1, suggesting that they are mediated by multiple transduction pathways, possibly involving several guanine nucleotide‐binding proteins.
Abstract: High-affinity specific receptors of endothelin (ET-1) were identified on primary cultures of mouse embryo striatal astrocytes by binding experiments performed with 125I-ET-1. Stimulation of production of inositol phosphates, a biphasic increase of the intracellular calcium concentration, and inhibition of cyclic AMP accumulation were observed in the same cells under ET-1 stimulation. Pretreatment of these cells with Bordetella pertussis toxin affected these effects to different extends, an observation suggesting that they are mediated by multiple transduction pathways, possibly involving several guanine nucleotide-binding proteins.
TL;DR: This chapter focuses on the influence of the ascending monoaminergic systems on the activity of the rat prefrontal cortex (PFC), which has a determining influence in the regulation of emotional states, the control of motor activity, and in cognitive processes, such as representational memory.
Abstract: Publisher Summary This chapter focuses on the influence of the ascending monoaminergic systems on the activity of the rat prefrontal cortex (PFC). The analysis of the influence of the aminergic ascending systems on cerebral functions has generated considerable interest because several psychoactive drugs are known to interfere with dopaminergic (DA), noradrenergic (NA), or serotoninergic (5HT) neurotransmission. The PFC has a determining influence in the regulation of emotional states, in the control of motor activity, and in cognitive processes, such as representational memory. The inhibition of the spontaneous firing is the most common effect reported in the cerebral cortex. Ascending DA, 5HT, and NA neurons, which originate respectively from the ventral tegmental area (VTA), the raphe nuclei, and the locus coeruleus markedly modulate neuronal activity in the PFC. The main differences in the influence of DA and 5HT as compared to NA afferents on the spontaneous activity or evoked responses of PFC cells are reviewed in the chapter. The influence of the three aminergic systems— DA, NA, and 5HT—is observed on efferent PFC neurons. A characteristic of the output PFC neurons in the rat is the extensive collateralization of their axons.
TL;DR: In this article, an analysis of the multiplicity distributions of charged particles produced in Z0 hadronic decays in the DELPHI detector is presented based on a sample of 25364 events.
Abstract: This paper presents an analysis of the multiplicity distributions of charged particles produced inZ0 hadronic decays in the DELPHI detector. It is based on a sample of 25364 events. The average multiplicity is =20.71±0.04(stat)±0.77(syst) and the dispersionD=6.28±0.03(stat)±0.43(syst). The data are compared with the results at lower energies and with the predictions of phenomenological models. The Lund parton shower model describes the data reasonably well. The multiplicity distributions show approximate KNO-scaling. They also show positive forward-backward correlations that are strongest in the central region of rapidity and for particles of opposite charge.
TL;DR: A relationship between gestational age and feta‐maternal transfer of NRBC is suggested as a source of fetal nucleated erythrocytes (NRBC) and single copy Y chromosomal DNA sequences were detected in samples obtained from six pregnant women.
Abstract: Maternal venous blood samples, obtained from six pregnant women, were used as a source of fetal nucleated erythrocytes (NRBC). Fetal cell enrichment was potentiated by flow sorting with the monoclonal antibodies TfR, Leu-4, and Leu-M3. Single copy Y chromosomal DNA sequences were detected in samples obtained from two women at 11 and 12 weeks' gestation. Y DNA sequences were absent in a subsequent sample from one of these women at 19 weeks and in two other women at 16 and 20 weeks. All four women delivered males. Y DNA sequences were not detected in two women who delivered females. By combining these results with prior data on the detection of Y chromosomal DNA sequences in maternal blood from male-bearing pregnancies, a relationship between gestational age and feto-maternal transfer of NRBC is suggested.
TL;DR: In this article, the presence of alpha-tubulin and MAP2 acetyltransferase activities in mouse brain was described, and a unique radioactive peptide was detected and purified by HPLC, which showed that this peptide contained epsilon N-acetyllysine at position 40 of the alpha tubulin molecule.
Abstract: We describe the presence of alpha-tubulin and MAP2 acetyltransferase activities in mouse brain. The enzyme(s) copurified with microtubules through two cycles of assembly-disassembly. Incubation of microtubule proteins with [3H]acetyl CoA resulted in a strong labeling of both alpha-tubulin and MAP2. To determine the site of the modification, tubulin was purified and digested with Glu-C endoproteinase. A unique radioactive peptide was detected and purified by HPLC. Edman degradation sequencing showed that this peptide contained epsilon N-acetyllysine at position 40 of the alpha-tubulin molecule. This result demonstrates that mouse brain alpha-tubulin was acetylated at the same site as in Chlamydomonas. Isoelectric focusing analysis showed that acetylated alpha-tubulin was resolved into five isoelectric variants, denoted alpha 3 and alpha 5 to alpha 8. This heterogeneity is not due to acetylation of other sites but results from a single acetylation of Lys40 of an heterogeneous population of alpha-tubulin isoforms. These isoforms are produced by posttranslational addition of one to five glutamyl units. Thus, neuronal alpha-tubulin is extensively modified by a combination of modifications including acetylation, glutamylation, tyrosylation, and other yet unknown modifications.
TL;DR: In this paper, the spreading of a nonvolatile wetting liquid on a flat solid surface was investigated. And the authors showed that the spreading process can be divided into two contributions, from the advancing wedge and from the central part (squashed under gravity).
TL;DR: It was found that the supraorbital region is strained relatively little during mastication and incision, which indicates that in macaques and baboons there is much more supraorbitals bone than is needed to counter masticatory loads, which in turn suggests that their brow-ridges could be considerably smaller yet still countermasticatory stress without structural failure.
TL;DR: The first observation of the beauty baryon Λb in an exclusive decay channel at the CERN p p p collider was reported in this paper, with a significance of about five standard deviations.
TL;DR: In this paper, the transverse mass distributions of negative particles, Λ' s, Λ's and Ξ −'s produced in sulphur-tungsten interactions at 200 GeV/c per nucleon were given.
TL;DR: ET-1, which has been generally reported to have a mitogenic effect on a variety of target cells including primary rat astrocytes, is shown to stimulate or inhibit DNA synthesis in C6 cells, depending on the subclone considered.
TL;DR: Comparison of the activities of NKA C-terminal analogues on the guinea-pig ileum suggests that 1) only a small population of NK-2 receptors are present in this tissue and 2) beside NK-1,NK-2 and NK-3 receptors, another type of receptor sensitive to C-Terminal sequences might be present in the guineaspig tissue.