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PubMed1992

Motor activity and the mesotelencephalic dopamine function. II. Multivariate analysis of genetically segregating generations.

Previous experiments on genetically different inbred strains of mice demonstrated parallel variations between the activity of regional brain tyrosine hydroxylase (TH) and locomotor behavior. Based on these associations, it was hypothesized that genetic variations in mesotelencephalic TH activity, an index of dopamine neurotransmitter function, would correlate positively with exploratory and locomotor behavior. In order to test this hypothesis, open-field motor behaviors and mesencephalic and striatal TH activities were analyzed by multivariate statistical methods in genetically segregating (C57BL/6ByJ X BALB/cJ)F2 and (C57BL/6ByJ X CXBI/ByJ)F2 generations. Factor analysis, based on correlation matrices of variables with significant genetic dominance or additive effects, demonstrated that locomotor activity and frequency of occurrence of various motor patterns were not correlated with mesencephalic and striatal TH activity. These results indicate that the assumption of a positive phenotypic correlation between spontaneous motor activity and mesotelencephalic TH activity does not hold in genetically segregating populations. Strategies and problems in revealing the behavioral consequences of genetically based variations in the mesotelencephalic DA system are briefly discussed.

Analysis of Variance↗
PubMed1997

Replication, expression and segregation of plasmid-borne DNA in genetically transformed malaria parasites.

To fully exploit the transfection technology developed for Plasmodium we investigated the features of replication, expression and segregation of an episomally maintained DNA construct during a sexual blood stage development in genetically transformed parasites of P. berghei. Using DNA in situ hybridisation techniques we were able to show that the introduced DNA construct is located in the nucleus of the parasite and is not segregating uniformly during schizogony. Replication of the construct mainly takes place between 16 and 24 h after invasion of the merozoites, coinciding with chromosomal replication. Furthermore the plasmid-borne DHFR/TS gene is constitutively transcribed throughout the asexual blood stage development. Hence the DHFR/TS promoter would appear to be a useful tool in the study of (over)expression of introduced genes and performing complementation studies in transfected parasites during the complete a sexual blood stage development of P. berghei.

Animals↗
PubMed2000

Relationships between individual behavioural traits and post-weaning growth in segregated early-weaned piglets.

Piglets' individual behavioural traits have been studied in the last decade but no report has linked these traits with growth. This experiment was conducted to determine if behavioural traits of segregated early-weaned piglets could be good predictors of their post-weaning growth and, thus, help to predict their adaptation to early weaning. Following segregated early weaning at 17+/-1 days old, 252 piglets were submitted to three tests between 20 and 25 days of age: open-field, reaction to humans and rank order based on competition for a restricted-access feeder. The body weight of each piglet was measured the day before weaning and once a week for the next 4 weeks. A principal component analysis yielded five factors with an Eigenvalue higher than 0.90 that accounted for 81% of the total variation between individuals: reaction to humans (25%), active response to stress (21%), passive response to stress (14%), feeding behaviour (10%) and rank order (9%). Passive reaction to stress was associated with better weight gain during the first week post-weaning (r=0.18; P=0.01), and a positive correlation was found between social status and weight gain during the 4 weeks following weaning (-0.15</=r</=-0.10); P</=0.10). No relation was found between reaction to humans and growth. These results confirm the relationship between rank order and growth in pigs and may suggest that reacting passively to stress could facilitate adaptation to weaning.

Journal Article↗
PubMed1999

Upheaval in the bacterial nucleoid. An active chromosome segregation mechanism.

Recent advances have completely overturned the classical view of chromosome segregation in bacteria. Far from being a passive process involving gradual separation of the chromosomes, an active, possibly mitotic-like machinery is now known to exist. Soon after the initiation of DNA replication, the newly replicated copies of the oriC region, behaving rather like eukaryotic centromeres, move rapidly apart towards opposite poles of the cell. They then determine the positions that will be taken up by the newly formed sister nucleoids when DNA replication has been completed. Thus, the gradual expansion of the diffuse nucleoid camouflages an underlying active mechanism. Several genes involved in chromosome segregation in bacteria have now been defined; their possible functions are discussed.

Anaphase↗
PubMed1998

Protrusion, contraction and segregation of membrane components associated with passive deformation and shape recovery of Walker carcinosarcoma cells.

We mimicked essential elements of the cortical-contraction model of cell locomotion by exposing Walker carcinosarcoma cells to passive deformation and to hydrostatic pressure changes within micropipettes followed by shape recovery after release. Protrusion, contraction and segregation of cell surface membrane components were observed. Regardless of the initial shape (spherical, polarized with lamellipodia or blebs) cells tended to produce blebs during uptake into the pipette and during and after release from the pipette, but usually not during the short time they were held within the pipette. Bleb formation depended on the deformation stress, extracellular hydrostatic pressure and cell structure (initial shape). In polarized cells, blebs were much more readily induced at the front as compared to the tail. Cells undergoing large deformations formed constriction rings and large hyaline caps. Deformation resulted in segregation of membrane components. Equatorial constriction rings divided the cell into two parts which differed with respect to Con A binding and their role in shape recovery. Spherical and polarized cells usually recover the respective initial shape. Polarized cells reacquired the same type of protrusions (blebs or lamellipodia) which they exhibited before deformation. Shape recovery of spherical cells was characterized by a rapid recoil by about 20% followed by a slow asymptotic recovery.

Animals↗
PubMed1997

HLA-G gene polymorphism segregation within CEPH reference families.

HLA-G, a nonclassical HLA class I antigen, presents tissue-restricted expression on human trophoblasts and may play an important role in immune tolerance of mother-versus-fetus. In this work we have demonstrated extensive HLA-G genomic polymorphism within three CEPH reference families, by PCR-SSCP analysis and direct sequencing. Among six unrelated parents we assigned eight HLA-G alleles, seven of which are new. We observed the segregation of HLA-G alleles of heterozygous parents among their offspring that matched the segregation of the HLA class I haplotypes. Only one of the mutations observed was found to be nonsynonymous indicating low polymorphism of the HLA-G molecule.

Alleles↗
PubMed1998

HLA-DRB4 gene encoded HLA-DR53 specificity segregating with the HLA-DR7, -DQ9 haplotype: unusual association.

HLA phenotyping of a leukemia patient of Caucasoid origin revealed the presence of the serological HLA-DR53 specificity. Comprehensive pedigree analysis demonstrated that the HLA-DR53 specificity segregated with the HLA-DR7, -DQ3 haplotype. High resolution PCR- SSP genotyping of the HLA class II genes revealed the presence of the HLA-DRB4*0101101 allele segregating together with the HLA-DRB1*0701, -DQA1*0201 and DQB1*03032 alleles. This finding is in contrast to known linkages in that thus far, the HLA-DR7, -DQ9 haplotype has only been described in association with the non-expressed HLA-DRB4*0103102N allele. The existence of this "novel" haplotype may be explained by a homologous recombinational event that occurred between the HLA-DR7, -DR53, -DQ2 and the HLA-DR7, -DQ9 haplotypes.

Female↗
PubMed2001

alpha7-Containing nicotinic receptors are segregated to the somatodendritic membrane of the cholinergic neurons in the avian nucleus semilunaris.

Segregation of ion channels and neurotransmitter receptors is an important mechanism for determining the functionality of the nervous system. In the case of nicotinic acetylcholine receptors, electrophysiological and anatomical studies have demonstrated that these receptors can be located at the somatodendritic and the axon terminal portions of neurons. Functionally, somatodendritic nicotinic receptors mediate fast excitatory transmission and possibly regulate other cell functions, while presynaptic nicotinic receptors enhance the release of neurotransmitters from axon terminals. Neurons in the mesencephalic lateral spiriform nucleus of the chick do not appear to restrict the localization of nicotinic receptors to specific membrane compartments, since receptors containing alpha5 and/or beta2 subunits are found both on the cell bodies and on the axonal projections of these neurons [Torrao A. S. et al. (1996) Brain Res. 743, 154-161]. We report here that, in contrast to lateral spiriform neurons, neurons in the nucleus semilunaris do appear to compartmentalize nicotinic receptors. The cholinergic nucleus semilunaris neurons express a high density of alpha7-containing nicotinic receptors on their somas [Britto L. R. G. et al. (1992) J. comp. Neurol. 317, 325-340]. However, when we examined the projections of these neurons in the lateral spiriform nucleus, we found no evidence for expression of alpha7-containing receptors on the cholinergic fibers from nucleus semilunaris neurons. Furthermore, patch-clamp electrophysiological recording from lateral spiriform neurons indicated an absence of presynaptic alpha7-containing nicotinic receptors capable of modulating the release of acetylcholine. We conclude that neurons are capable of segregating alpha7-containing nicotinic receptors to specific areas of their plasma membrane. Such targeting of nicotinic receptors would play an important role in determining their functional role in neurons.

Aconitine↗
PubMed2002

Spatial segregation within the sacral parasympathetic nucleus of neurons innervating the bladder or the penis of the rat as revealed by three-dimensional reconstruction.

The purpose of the present investigations was (1) to examine the spatial organization of preganglionic neurons of the sacral parasympathetic nucleus in the lumbosacral spinal cord of male adult rats and (2) to search, in this nucleus, for a possible segregation of sub-populations of neurons innervating the penis or the bladder, respectively. To estimate their spatial organization, neurons of the sacral parasympathetic nucleus were retrogradely labeled by wheat germ agglutinin coupled to horseradish peroxidase applied to the central end of the sectioned pelvic nerve. The sub-populations of lumbosacral neurons innervating the corpus cavernosum of the penis or the dome of the bladder were identified using transsynaptic retrograde labeling by pseudorabies virus injected into these organs in different rats. In both wheat germ agglutinin-labeled and pseudorabies virus-labeled rats, serial coronal sections were cut through the spinal L5-S1 segments. Labeled neurons were revealed by histochemistry (peroxidase experiments) or immunohistochemistry (pseudorabies virus experiments). By means of a three-dimensional reconstruction software developed in our laboratory, three-dimensional models were calculated from each spinal section image series. They revealed the spatial organization of (i) preganglionic neurons and (ii) neurons innervating the bladder or the penis. The different three-dimensional models were subsequently merged into a single one which revealed the segregation, within the sacral parasympathetic nucleus, of the sub-populations of neurons. Neurons labeled by virus injected into the penis extended predominantly from the rostral part of the L6 segment to the rostral part of the S1 segment while those labeled by bladder injections were distributed predominantly from the caudal part of the L6 segment to the caudal part of the S1 segment. These results support the hypothesis of a viscerotopic organization of sacral neurons providing the spinal control of pelvic organs.

Animals↗
PubMed1997

Molecular engineering with the FRT sequence of the yeast 2 microm plasmid: [cir0] segregant enrichment by counterselection for 2 microm site-specific recombination.

Site-specific recombination systems from bacteriophage and yeasts are becoming precious tools for manipulating DNA both in vitro and in living organisms. In this work we describe the isolation of yeast Saccharomyces cerevisiae segregants which have lost the highly stable 2 microm DNA plasmid, exploiting the site-specific recombination system of 2 microm itself. We efficiently isolated [cir0] segregants from two haploid yeast strains and also a diploid. Moreover, the effect of mutations in the core region of the FRT (Flp Recognition Target) sequence was investigated in vivo, studying the result of the recombination event between several mutated and wild-type FRT sequences. From our result it seems that the identity between the core regions of two FRT sites is necessary but not sufficient, indicating that the core sequence itself has a relevant function in the recombination mechanism in vivo.

Cloning, Molecular↗
PubMed2004

Results of a collaborative study of the EDNAP group regarding mitochondrial DNA heteroplasmy and segregation in hair shafts.

A collaborative exercise was carried out by the European DNA Profiling Group (EDNAP) in order to evaluate the distribution of mitochondrial DNA (mtDNA) heteroplasmy amongst the hairs of an individual who displays point heteroplasmy in blood and buccal cells. A second aim of the exercise was to study reproducibility of mtDNA sequencing of hairs between laboratories using differing chemistries, further to the first mtDNA reproducibility study carried out by the EDNAP group. Laboratories were asked to type 2 sections from each of 10 hairs, such that each hair was typed by at least two laboratories. Ten laboratories participated in the study, and a total of 55 hairs were typed. The results showed that the C/T point heteroplasmy observed in blood and buccal cells at position 16234 segregated differentially between hairs, such that some hairs showed only C, others only T and the remainder, C/T heteroplasmy at varying ratios. Additionally, differential segregation of heteroplasmic variants was confirmed in independent extracts at positions 16093 and the poly(C) tract at 302-309, whilst a complete A-G transition was confirmed at position 16129 in one hair. Heteroplasmy was observed at position 16195 on both strands of a single extract from one hair segment, but was not observed in the extracts from any other segment of the same hair. Similarly, heteroplasmy at position 16304 was observed on both strands of a single extract from one hair. Additional variants at positions 73, 249 and the HVII poly(C) region were reported by one laboratory; as these were not confirmed in independent extracts, the possibility of contamination cannot be excluded. Additionally, the electrophoresis and detection equipment used by this laboratory was different to those of the other laboratories, and the discrepancies at position 249 and the HVII poly(C) region appear to be due to reading errors that may be associated with this technology. The results, and their implications for forensic mtDNA typing, are discussed in the light of the biology of hair formation.

DNA, Mitochondrial↗
PubMed2000

Co-segregation of benign infantile convulsions and paroxysmal kinesigenic choreoathetosis.

We report seven families and two sporadic cases in which benign infantile convulsions and paroxysmal kinesigenic choreoathetosis were co-segregated. Clinical investigations included physical and neurological examinations, blood electrolyte values, interictal and ictal electroencephalograms, and computed tomography or magnetic resonance imaging of the brain. The family pedigree was confirmed and the clinical history of the relatives was obtained. Seventeen individuals developed infantile convulsions followed by paroxysmal dyskinesias during childhood or adolescence. Six had only infantile convulsions, and two had only paroxysmal dyskinesias. The seizures never persisted into childhood or recurred in adulthood. The seizure type was a complex partial seizure, with or without secondary generalization, in nine of 14 patients. Paroxysmal dyskinesias, a subgroup of paroxysmal kinesigenic choreoathetosis, occurred for less than 5 min. The attacks of dyskinesias began at age 5-12 years in most patients, and tended to remit in adulthood. The mode of inheritance was apparently autosomal dominant in four of the families (17 affected individuals), who were diagnosed with ICCA syndrome (infantile convulsions and paroxysmal choreoathetosis). However, the condition occurred only among siblings in three families (six patients), and sporadically in two patients, suggesting genetic heterogeneity in this distinct co-segregation.

Adolescent↗
PubMed2003

Providing affordable family housing and reducing residential segregation by income. A systematic review.

The inadequate supply of affordable housing for low-income families and the increasing spatial segregation of some households by income, race, ethnicity, or social class into unsafe neighborhoods are among the most prevalent community health concerns related to family housing. When affordable housing is not available to low-income households, family resources needed for food, medical or dental care, and other necessities are diverted to housing costs. Two housing programs intended to provide affordable housing and, concurrently, reduce the residential segregation of low-income families into unsafe neighborhoods of concentrated poverty, are reviewed: the creation of mixed-income housing developments and the Department of Housing and Urban Development (HUD) Section 8 Rental Voucher Program. The effectiveness of mixed-income housing developments could not be ascertained by this systematic review because of a lack of comparative research. Scientific evidence was sufficient to conclude that rental voucher programs improve household safety as measured by reduced exposure to crimes against person and property and decreased neighborhood social disorder. Effectiveness of rental voucher programs on youth health risk behaviors, mental health status, and physical health status could not be determined because too few studies of adequate design and execution reported these outcomes.

Family↗
PubMedDate not supplied

Regulation of chromosome segregation in Escherichia coli.

Cell division is tightly coupled to DNA replication in Escherichia coli, as evidenced by the rarity of anucleate cells in steady state cultures. When DNA synthesis is arrested, cell division also comes to a halt and filamentous growth ensues, again with little formation of anucleate cells. To test the precise role of the SfiA division inhibitor during filamentous growth, we compared sfiA+ and sfiA- strains in their response to thymine starvation. More residual division was observed in the sfiA mutant culture, and autoradiographic analysis revealed that 13% of the final population consisted of cells of normal size containing no DNA compared to 0.9% in the thymine-starved sfiA+ culture. The SfiA division inhibitor is known to be synthesized massively during thymine starvation as part of the inducible SOS response. We conclude that it prevents aberrant division and formation of anucleate cells, thus assuring proper segregation when DNA synthesis is perturbed. The SfiC division inhibition mechanism, also associated with the SOS response, does not affect cell division during thymine starvation. On the other hand, an SOS-independent mechanism of division arrest clearly comes into play during thymine starvation of a sfiA sfiC mutant: although considerable aberrant division took place, the majority of the cells formed long filaments with 1 or 2 masses of DNA. Thus, E. coli assures proper chromosome segregation by two systems when DNA replication is perturbed: the rapid, efficient SfiA division inhibitor and a less stringent SOS-independent mechanism.

Cell Division↗
PubMed1999

Integration and segregation of limbic cortico-striatal loops at the thalamic level: an experimental tracing study in rats.

The frontal lobe and the basal ganglia are involved in a number of parallel, functionally segregated circuits. Information is thought to pass from distinct parts of the (pre)frontal cortex, via the striatum, the pallidum/substantia nigra and the thalamus, back to the premotor/prefrontal cortices. Currently, different views exist as to whether these circuits are to be considered as open or closed loops, as well as to the degree of interconnection between different circuits. The main goal of the present study is to answer some of these questions for the limbic corticostriatal circuits. The latter circuits involve the nucleus accumbens, the ventral pallidum/dorsomedial substantia nigra pars reticulata, the medial parts of the mediodorsal and ventromedial thalamic nuclei and the prefrontal cortex. Within the nucleus accumbens, a core and a shell region are recognized on the basis of anatomical and functional criteria. The shell of the nucleus accumbens projects predominantly to the mediodorsal, the midline and the reticular thalamic nuclei via the ventral pallidum, whereas the core reaches primarily the medial part of the ventromedial thalamic nucleus, the intralaminar and mediodorsal thalamic nuclei via a relay in the dorsomedial substantia nigra pars reticulata. By means of double labeling experiments with injections of anterograde tracers in both the ventral pallidum and the substantia nigra of rats, we were able to demonstrate that circuits involving the shell and the core of the nucleus accumbens remain largely segregated at the level of the thalamus. Only restricted areas of overlap of ventral pallidal and reticular nigral projections occur in the mediodorsal and ventromedial thalamic nuclei, which allows for a limited degree of integration, at the thalamic level, of information passing through the two circuits.

Animals↗
PubMedDate not supplied

Segregation of COPI-rich and anterograde-cargo-rich domains in endoplasmic-reticulum-to-Golgi transport complexes.

Membrane traffic between the endoplasmic reticulum (ER) and the Golgi complex is regulated by two vesicular coat complexes, COPII and COPI. COPII has been implicated in the selective packaging of anterograde cargo into coated transport vesicles budding from the ER [1]. In mammalian cells, these vesicles coalesce to form tubulo-vesicular transport complexes (TCs), which shuttle anterograde cargo from the ER to the Golgi complex [2] [3] [4]. In contrast, COPI-coated vesicles are proposed to mediate recycling of proteins from the Golgi complex to the ER [1] [5] [6] [7]. The binding of COPI to COPII-coated TCs [3] [8] [9], however, has led to the proposal that COPI binds to TCs and specifically packages recycling proteins into retrograde vesicles for return to the ER [3] [9]. To test this hypothesis, we tracked fluorescently tagged COPI and anterograde-transport markers simultaneously in living cells. COPI predominated on TCs shuttling anterograde cargo to the Golgi complex and was rarely observed on structures moving in directions consistent with retrograde transport. Furthermore, a progressive segregation of COPI-rich domains and anterograde-cargo-rich domains was observed in the TCs. This segregation and the directed motility of COPI-containing TCs were inhibited by antibodies that blocked COPI function. These observations, which are consistent with previous biochemical data [2] [9], suggest a role for COPI within TCs en route to the Golgi complex. By sequestering retrograde cargo in the anterograde-directed TCs, COPI couples the sorting of ER recycling proteins [10] to the transport of anterograde cargo.

Animals↗
PubMed1998

Segregation of minichromosomes in trypanosomes: implications for mitotic mechanisms.

In addition to 11 pairs of housekeeping chromosomes, the genome of Trypanosoma brucei contains approximately 100 minichromosomes that are probably involved in the ability of the parasite to evade the host's immune response. This minichromosomal population is segregated on the mitotic spindle. How this is achieved provides insight into potential segregation mechanisms for small DNA molecules in eukaryotic microorganisms.

Animals↗
PubMed2003

Unequal segregation of Neuralized biases Notch activation during asymmetric cell division.

In Drosophila, Notch signaling regulates binary fate decisions at each asymmetric division in sensory organ lineages. Following division of the sensory organ precursor cell (pI), Notch is activated in one daughter cell (pIIa) and inhibited in the other (pIIb). We report that the E3 ubiquitin ligase Neuralized localizes asymmetrically in the dividing pI cell and unequally segregates into the pIIb cell, like the Notch inhibitor Numb. Furthermore, Neuralized upregulates endocytosis of the Notch ligand Delta in the pIIb cell and acts in the pIIb cell to promote activation of Notch in the pIIa cell. Thus, Neuralized is a conserved regulator of Notch signaling that acts as a cell fate determinant. Polarization of the pI cell directs the unequal segregation of both Neuralized and Numb. We propose that coordinated upregulation of ligand activity by Neuralized and inhibition of receptor activity by Numb results in a robust bias in Notch signaling.

Animals↗