Effect of pps disruption and constitutive expression of srfA on surfactin productivity, spreading and antagonistic properties of Bacillus subtilis 168 derivatives.

AIMS: To analyse the effects of plipastatin operon disruption and constitutive expression of surfactin operon in Bacillus subtilis 168 on surfactin productivity, in vitro invasive growth and antagonism against fungi. METHODS AND RESULTS: The srfA native promoter was replaced by the constitutive promoter P(repU) in B. subtilis 168 after integration of a functional sfp gene. Moreover, the plipastatin synthesis was further disrupted in the B. subtilis 168 derivatives. In liquid media, an earlier and higher expression of P(repU), than that found with P(srfA), led to a specific surfactin production fivefold higher after 6 h of culture. On solid media, not only the invasive growth and the haemolytic activity but also the antifungal activity of the constitutive strains were improved when compared to the parental strain BBG111. As expected, the disruption of the plipastatin operon strongly reduced in vitro antifungal properties but, interestingly, enhanced specific surfactin production (1.47 g g(-1) of biomass), spreading behaviour and haemolytic activity of the strains. CONCLUSIONS: This work demonstrates for the first time the interdependency of surfactin and plipastatin regarding their biosynthesis as well as their influence on the biological activities of the producing strain. SIGNIFICANCE AND IMPACT OF THE STUDY: The constitutive overproduction of surfactin enhances the invasive growth and the in vitro antagonistic activity of the mutant strain. Both properties are known to play an important role in the biocontrol of plant diseases. Plipastatin operon disruption increases the surfactin productivity of mutant strains. These mutants are interesting for use in continuous bioprocesses for surfactin production or in bioremediation.

Modulation of neural stereoscopic processing in primate area V1 by the viewing distance.

Accurate binocular depth perception requires information about both stereopsis (relative depth) and distance (absolute depth). It is unclear how these two types of information are integrated in the visual system. In alert, behaving monkeys the responsiveness of a large majority of neurons in the primary visual cortex (area V1) was modulated by the viewing distance. This phenomenon affected particularly disparity-related activity and background activity and was not dependent on the pattern of retinal stimulation. Therefore, extraretinal factors, probably related to ocular vergence or accommodation, or both, can affect processing early in the visual pathway. Such modulations could be useful for (i) judging true distance and (ii) scaling retinal disparity to give information about three-dimensional shape.

Conformational study of the chromosomal protein MC1 from the archaebacterium Methanosarcina barkeri.

Methanogen chromosomal protein MC1 is a polypeptide of 93 amino acid residues (Mr 10,757) which represents the major protein associated with the DNA of the archaebacterium Methanosarcina barkeri and can protect DNA against thermal denaturation. The conformation of protein MC1 has been investigated by means of predictive methods, infrared spectroscopy, circular dichroism and tryptophan fluorescence studies. Protein MC1 has a low amount of alpha-helix but contains antiparallel beta-sheet strands. The larger hydrophobic cluster which contains tryptophan at position 61 appears buried in the protein. Addition of salts induces the unfolding of the protein and makes the tryptophan indole ring more rigid. With respect to its primary structure and its conformation, protein MC1 appears radically different from the chromosomal DNA-binding protein II (also called HU-type protein) in eubacteria.

New mechanisms of AML1 gene alteration in hematological malignancies.

The human AML1 gene (also named CBFA2 or RUNX1), located in the 21q22 chromosomal band, encodes for one of the two subunits forming a heterodimeric transcription factor, the human core binding factor (CBF). AML1 protein contains a highly evolutionary conserved domain of 128 amino acids called runt domain, responsible for both heterodimerization with the beta subunit of CBF and for DNA binding. AML1 is normally expressed in all hematopoietic lineages and acts to regulate the expression of various genes specific to hematopoiesis playing a pivotal role in myeloid differentiation. AML1 is one of the genes most frequently deregulated in leukemia through different mechanisms including translocation, mutation and amplification. Translocations lead to the formation of fusion genes encoding for chimerical proteins such as AML1-ETO which induces leukemogenesis. Recently, new mechanisms of AML1 deregulation by point mutations or amplification have been reported. To our knowledge, 51 patients (among 805 studied) with AML1 point mutations have been described. Forty of them have acute myeloid leukemia (AML) most often M0 AML. In this subtype of AML, the frequency of AML1 mutation is significantly higher; 21.5% of patients mutated (34/158). Mutations have also been found with lower frequency in other FAB subtype AML (6 cases), in myeloproliferative disorders (6 cases), in myelodysplastic syndrome (3 cases) and rarely in acute lymphoblastic leukemia (1 case). AML1 gene amplification has been found essentially in childhood ALL (12 cases) and more rarely in myeloid malignancies (4 cases). Here, we reviewed all these cases of AML1 point mutations and amplification and focused on the mechanisms of AML1 deregulation induced by these alterations.

Report of 34 patients with clonal chromosomal abnormalities in Philadelphia-negative cells during imatinib treatment of Philadelphia-positive chronic myeloid leukemia.

Imatinib mesylate (Gleevec), an inhibitor of the BCR-ABL tyrosine kinase, was introduced recently into the therapy of chronic myeloid leukemia (CML). Several cases of emergence of clonal chromosomal abnormalities after therapy with imatinib have been reported, but their incidence, etiology and prognosis remain to be clarified. We report here a large series of 34 CML patients treated with imatinib who developed Philadelphia (Ph)-negative clones. Among 1001 patients with Ph-positive CML treated with imatinib, 34 (3.4%) developed clonal chromosomal abnormalities in Ph-negative cells. Three patients were treated with imatinib up-front. The most common cytogenetic abnormalities were trisomy 8 and monosomy 7 in twelve and seven patients, respectively. In 15 patients, fluorescent in situ hybridization with specific probes was performed in materials archived before the initiation of imatinib. The Ph-negative clone was related to previous therapy in three patients, and represented a minor pre-existing clone that expanded after the eradication of Ph-positive cells with imatinib in two others. However, in 11 patients, the new clonal chromosomal abnormalities were not detected and imatinib may have had a direct effect. No myelodysplasia was found in our cohort. With a median follow-up of 24 months, one patient showed CML acceleration and two relapsed.

N-methyl-D-aspartate subunit R1 involvement in the postnatal organization of the primary visual cortex of Callithrix jacchus.

It has been demonstrated that the primary visual cortex is highly sensitive to manipulations of the visual environment during a specific, early, postdevelopmental period: the critical period. Pharmacological studies have shown that N-methyl-D-aspartate (NMDA) receptors are involved in the plasticity of the visual cortex just as they are involved in the induction of long-term potentiation (LTP), another activity-dependent form of plasticity. The setting up of synaptic connectivity in the neocortex may rely on LTP-like mechanisms. By using immunohistochemistry techniques, we tested the hypothesis of the role of subunit R1 of NMDA (NMDAR1) receptors in the thalamocortical afferent segregation into ocular-dominance columns in the New World monkey, Callithrix jacchus. We employed early and short (2 weeks) monocular-deprivation periods at different ages of postnatal development (17, 46, 67, 107, and 188 postnatal days). We observed heterogeneous distribution of NMDAR1 in the layer IVC receiving the thalamic inputs if the deprivation was realized between the ages of 46 and 107 days. Layers IVCalpha and IVCbeta were involved differently as a function of the deprivation age. The striped pattern lost its differential intensity with the postnatal age. These results are compared with the ocular-dominance pattern evolution described in other works on this primate. They provide evidence of the NMDAR1 role in the modular organization, within time limits, during the postnatal development of the primary visual cortex.

The ipsilateral optic pathway to the dorsal lateral geniculate nucleus and superior colliculus in mice with prenatal or postnatal loss of one eye.

The projections, and more particularly the ipsilateral projections, from the retina to the dorsal lateral geniculate nucleus (dlGn) and the superior colliculus have been investigated in adult mice of the C57BL/6J strain after rearing in one of four different conditions: 1) after normal visual experience; 2) after unilateral enucleation at birth; 3) in mice with congenital unilateral anophthalmia (in which only one eye develops) 4) in mice with congenital unilateral microphthalmia (in which one eye is of reduced size while the other is normal). In neonatally enucleated and congenitally monocular mice there is an aberrant uncrossed pathway to regions of the dlGn and the superior colliculus which do not normally receive such a projection. This projection is limited in its distribution; in both the neonatally enucleated and the congenitally monocular animals the uncrossed projection does not reach the lateral and dorsal parts of the dlGn and it only innervates the rostral half of the superior colliculus. The density of the uncrossed pathway in these animals is highest in those regions in which the normal uncrossed pathway terminates. In microphthalmic mice the expansion of the uncrossed pathway is less marked than in monocular mice. In the superior colliculus the aberrant uncrossed projections innervate the stratum griseum superficiale where they are often found distributed in small patches. An intertectal crossing of retinal fibers is described from the contralateral superior colliculus to the deprived ipsilateral superior colliculus.

Prenatal and postnatal development of retinogeniculate and retinocollicular projections in the mouse.

The development of retinal projections to the dorsal lateral geniculate nucleus (dLGN) and superior colliculus (SC) has been studied in fetal and neonatal mice of the pigmented C57BL/6 strain, using the anterograde transport of tritiated proline and horseradish peroxidase (HRP). Retinal efferents are present contralaterally just beyond the chiasm at E14. By E16 they have grown into both dLGN and SC. Ipsilateral fibers are limited to the proximal optic tract at E16; their growth into dLGN and SC is delayed until E18-birth. During the first 2 postnatal days, an early population of ipsilateral fibers invades the dLGN. Most of these fibers grow in or around the medio-dorsal sector of the dLGN, i.e., the future binocular segment. Fibers are also present, but at lower densities, in the ventral half of the nucleus and thereafter become dispersed or are lost, without at any stage becoming dense. Some denser labeling is also present ipsilaterally in the outer rim of dLGN, just below the optic tract, and later disappears. On the third postnatal day, the ipsilateral fibers establish a deep and denser projection along the medial and dorsal borders of dLGN; this projection overlaps part of the crossed projection, which at this age extends to the whole nucleus. The segregation of each projection starts on the fourth postnatal day, when crossed fibers begin to disappear from the small region of uncrossed projection. This process goes on for another 4 days. During this period, the ipsilateral fibers withdraw from the deepest layer of dLGN, and their terminal density increases gradually; by the eighth postnatal day, both projections are already well separated. Dense crossed projections first appear near the surface of the SC at birth. Prior to this, retinal fibers course throughout neurons of the collicular plate and underneath the pia. The uncrossed fibers invade the SC between birth and P3. They are located preferentially in the anterior and medial aspect of the SC. Subsequently, there occurs a diminution in the laminar and tangential extent of these projections, simultaneously with an intensification of the ipsilateral input to several small, longitudinally oriented clusters located deep to the crossed projections.

Variations of the egocentric reference among normal subjects and a patient with unilateral neglect.

Thirty normal subjects and a patient with a left unilateral neglect were submitted to a straight-ahead pointing task in the three following trunk orientations: head and trunk aligned at 0 degree, and trunk rotated 15 degrees to the left or to the right relative to the head. The position of the egocentric reference was found to be dependent upon the trunk orientation, lateralization of the motor response and starting position, and thus on motor direction. The results are discussed with regard to egocentric hypotheses of neglect, spatio-motor cueing and scanning direction.

Egocentric reference and asymmetric perception of space.

Normal dextrals performed tactilo-kinesthetic bisection tasks in a median position, at three directions of gaze: 30 degrees to the left, 30 degrees to the right, 0 degree. Instead of pseudoneglect phenomenon, a deviation of the subjective middle to the side opposite to the direction of gaze and hand use was found, whichever hand was used. The results are interpreted in terms of displacement of the position of the egocentric reference and are discussed with respect to activation theory. It is argued that pseudoneglect is part of a more general asymmetric perception of space phenomenon which depends on the position of the egocentric reference.

Morphological aspects of the placenta in HIV pregnancies.

Forty-nine placentae from HIV-seropositive mothers were collected in various hospitals in France and Belgium. Twenty [corrected] placentae with seven fetuses from interrupted pregnancies and 29 [corrected] placentae from spontaneous deliveries, including two stillborns and a set of twins, were studied morphologically. No significant abnormalities were observed in the aborted material. The placentae corresponding to deliveries presented no significant gross abnormalities but the ratio of fetal to placental weight was significantly decreased in the study group compared with the control group (6.13 versus 7.41; P less than 0.001), associated with a congestive and mature aspect of the parenchyma. Histologically a high incidence of chorioamnionitis (43 per cent) was found, contrasting with the absence of villitis. A relative villous hypercellularity was observed in the study group compared with the control group. Ultrastructural studies of 13 placentae corresponding to gestations of 10 to 40 weeks are presented. In six cases, retrovirus-like particles were found at various sites, such as villous fibroblasts, syncytiotrophoblast and endothelial cells, and in the free membranes.

Myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML) with myelofibrosis.

Acute myeloid leukemias (AML) and myelodysplastic syndromes (MDS) enter rarely in the differential diagnosis of myelofibrosis (MF). MF of marked intensity, resulting in either "dry taps" or non-representative smears, is encountered in approximately 10% of cases. MF may be observed in any type of AML, most frequently in acute megakaryoblastic leukemia (M7). Apart from some typical cases of MDS, MF is associated with cases of acute myelodysplasia with myelofibrosis (and a major megakaryocytic component). This syndrome has been described under various headings: acute or malignant myelosclerosis, and acute MF. It should be distinguished from M7 and from myeloproliferative syndromes.

Three new cases of the Schinzel-Giedion syndrome and review of the literature.

Three fetuses with normal chromosomes were found to have uni- or bilateral hydronephrosis during the third trimester of pregnancy. At birth, they presented with coarse face, hypertelorism, and a deep groove under the eyes. Fontanelles and sutures were wide open. Genital abnormalities were present in 2 cases. Skeletal radiographs showed delayed bone maturation, broad and dense ribs, and a wide synchondrosis between the exoccipital and supraoccipital bones. The combination of such findings suggested the diagnosis of Schinzel-Giedion syndrome. Two patients died soon after birth, whereas the third one developed severe mental and motor retardation with seizures and spasticity, and died at 18 months. Schinzel-Giedion syndrome is rare and likely to be inherited as an autosomal recessive trait. So far, 13 well-documented cases have been reported allowing major and minor traits of the syndrome to be distinguished. Since no genetic marker is available, the prenatal diagnosis of Schinzel-Giedion syndrome relies on ultrasound examination, especially detection of renal abnormalities.

Trisomy 16p in a liveborn offspring due to maternal translocation t(16;21)(q11;p11) and review of the literature.

We report on a case of dup(16p) and review previous cases. The triplicated chromosome region leading to this specific syndrome lies in 16p13.1 p13.3. Most of the cases are inherited and the mode of segregation was found to be 3:1 in half of the cases, but these observations might be due to biases. The other chromosomes involved in the translocations as well as the breakpoints in these chromosomes do not appear to be random.

The cell cycle gene SKP1 is regulated by light in postnatal rat brain.

During the early postnatal phase of high neuronal plasticity, an altered visual input leads to great modifications of visual cortex organization [Y. Frégnac, M. Imbert, Development of neuronal selectivity in primary visual cortex of cat, Physiol. Rev., 64 (1984) 375-434; D.H. Hubel, T.N. Wiesel, S. LeVay, Plasticity of ocular dominance columns in monkey striate cortex, Philos. Trans. R. Soc. London, Ser. B, 278 (1977) 377-409.]. We used refined differential screening of an organized cDNA library to identify the genes that may participate in this plasticity. We isolated a candidate plasticity gene encoding for a 163 aa protein that is closely related to the human and yeast Skp1p, a key factor in cell cycle progression [C. Baï, K. Hofman, L. Ma, M. Goebl, J.W. Harper, S.J. Elledge, SKP1 connects cell cycle regulators to the ubiquitin proteolysis machinery through a novel motif, the F-box, Cell, 86 (1996) 263-274; C. Connelly, P. Hieter, Budding yeast SKP1 encodes an evolutionary conserved kinetochore protein required for cell cycle progression, Cell, 86 (1996) 275-285; H. Zhang, R. Kobayashi, K. Galaktionov, D. Beach, p19Skp1 and p45Skp2 are essential elements of the cyclin A-CDK2 S phase kinase, Cell, 82 (1995) 915-925.]. Northern blot analysis showed that the expression of SKP1 (Skp1p gene) dramatically decreased after 2 h of light stimulation in the visual cortex of young dark-reared rats. This down regulation lasted at least 72 h. It was specific for the critical period as we did not observe any significant regulation of SKP1 mRNA by light in adult dark-reared rat brain. The down regulation was observed in the superior colliculus but also in the frontal cortex and in the hippocampus. The fact that this down regulation was not restricted to the visual system, suggested that it could be produced by dark rearing-induced hormonal changes. The significance of SKP1 expression in the brain and its regulation are discussed.

Pure acute monocytic leukemia. A study of 12 cases.

Twelve cases of pure acute monocytic leukemia in adults were studied. They were selected on the basis of the morphology of the blast cells on Romanowsky-stained smears of blood and bone marrow, as well as positivity of the cells for the naphthol ASD acetate esterase reaction specifically inhibited by sodium fluoride. There was no sex predominance. Neoplastic involvement of the skin and/or gingiva was very frequent. The leukemic proliferation in blood and bone marrow consisted of monoblasts, promonocytes and monocytes. The peroxidase reaction was negative or only faintly positive. Serum and urinary lysozyme levels were increased. The blast cells retained their ability to stimulate, in vitro, colony formation by normal bone marrow cells used as targets. All of these characteristics permit specific identification of this type of acute leukemia. The prognosis is grim: only five of 12 patients achieved complete remission, and four of these five had relapses in less than 14 months; the median survival was five months.

Prevalence and distribution of ringed sideroblasts in primary myelodysplastic syndromes.

In order to determine the prevalence and percentage distribution of ringed sideroblasts in primary myelodysplastic syndromes, the results of Prussian blue staining were analysed in 133 cases. Ringed sideroblasts ranging from 1 to 86% of cells were found in 76 (57%) cases. The cases of primary myelodysplastic syndrome corresponding to the group entitled "acquired idiopathic sideroblastic anaemia" had between 21 and 86% ringed sideroblasts; these were also found in 40% (26/65) cases corresponding to refractory anaemia with excess of blasts. Seven of the 22 cases having morphological features of refractory anaemia with excess of blasts in transformation had ringed sideroblasts. It would appear that cases of acquired idiopathic sideroblastic anaemia have at least 20% ringed sideroblasts; they also seem to occur frequently in refractory anaemia with excess of blasts.

Platelet peroxidase deficiency in a case of myelodysplastic syndrome with myelofibrosis.

Morphological and functional abnormalities of the megakaryocytic series have been well described in myelodysplastic syndromes. Platelet peroxidase has always been demonstrated in abnormal megakaryocytes and early megakaryoblasts in such syndromes. We have studied a case of myelodysplastic syndrome with marked morphological abnormalities of megakaryocytes in which ultrastructural studies showed the coexistence of platelet peroxidase positive and platelet peroxidase negative megakaryocytes. This enzymatic deficiency was confirmed by the ultrastructural study of circulating platelets. This case appears to be the first report of a partial platelet peroxidase deficiency. It adds to the enzymatic abnormalities in myelodysplastic syndrome already described for the red cells and the granulocytic cells.

Haematological features of primary myelodysplastic syndromes (PMDS) at initial presentation: a study of 118 cases.

The haematological features of 118 cases of primary myelodysplastic syndromes (PMDS) were reviewed to see how these could be related and classified according to the recent FAB proposals. A majority of the cases were elderly who presented with a macrocytic or normocytic anaemia and reticulocytopenia. Cases of acquired idiopathic sideroblastic anaemia (AISA) usually had normal leucocyte and platelet counts, erythroid hyperplasia, marked dyserythropoiesis and more than 20% ringed sideroblasts. Cases of refractory anaemia with excess of blasts (RAEB) had frequent neutropenia and thrombopenia usually with prominent dysgranulopoiesis and dysthrombopoiesis. Refractory anaemia or refractory cytopenia appeared morphologically to be a heterogeneous group. Leukaemic transformation did not occur in any of these 16 cases of AISA whereas six of the 34 cases of RAEB transformed into acute leukaemia. It appears that the cases of PMDS present with well defined haematological features which permit recognition of different groups; these latter groups appear to be morphologically and prognostically distinct.

Influence of reading habits on line bisection.

The effect of scanning direction on perception of space is studied with a visuo-motor bisection task, among 120 normal dextrals with opposite reading habits (60 French subjects, 60 Israeli subjects). Bisection is found to depend upon subject's reading habits. Israeli bisected the line to the right of the objective centre, while French subjects placed their subjective middle to the left of the objective one. Results are discussed with respect to hemispheric activation theories, directional hypotheses and the neglect syndrome.