Coincidence of familial systemic lupus erythematosus and the fragile X syndrome

The coincidence of fragile X syndrome (fra(X] and systemic lupus erythematosus (SLE) in the same family is reported here for the first time. A 16-year-old boy with typical fra(X) had a severe SLE with multiple organ involvement. His 12-year-old sister of normal intelligence had circulating antinuclear antibodies and proliferative glomerulonephritis. The fra(X) was not found in her karyotype. Except for abnormalities due to immunosuppressive treatment during pregnancy, the association of SLE and chromosome abnormalities has been only reported in Klinefelter's syndrome. The possible pathogenic role of sex hormonal abnormalities due to an extra X chromosome has been suggested in the occurrence of SLE.     

Myelin Basic Protein Deposition in the Optic and Sciatic Nerves of Dysmyelinating Mutants Quaking, Jimpy, Trembler, MLD, and Shiverer During Development

An ontogenetic survey of the basic protein of myelin, common to both central and peripheral nervous systems, was carried out on normal C57Bl and five dysmyelinating mutant mice. Myelin basic protein (MBP) was quantified by radioimmunoassay in the optic and sciatic nerves of mice from birth to adult stages, giving special attention to the premyelinating and early myelination periods. In the optic nerves of normal mice, MBP was already detectable at birth but the active period of myelin deposition was shown to occur after day 10 postnatal. The timing and rate of accumulation of MBP were normal in Trembler. In contrast, they were abnormal in the other mutants. In the quaking mouse, the active period of MBP deposition was delayed, and its final concentration represented no more than 12% of normal in the adult. No active period of MBP deposition was observed in the other mutants. In the jimpy mouse, a slow accumulation of MBP resulted in a final concentration reaching 2% of the normal value at 25 days. In mild and shiverer mice, the MBP was hardly detectable. In the sciatic nerves of normal mice, the active period of MBP deposition occurred between days 3 and 12 postnatal. No substantial changes occurred in the period of 2 months--2 years.(ABSTRACT TRUNCATED AT 250 WORDS)     

Partial Transcription of Murine Type C Viral Genomes in BALB/c Cell Lines

The mouse cell line, BALB/c 3T3, and its derivatives transformed either spontaneously or by treatment with a variety of external agents, were analyzed for cytoplasmic RNA complementary to DNA products prepared from the Kirsten strain of murine sarcoma-leukemia virus, and from an endogenous type C virus of BALB/c 3T3. Although none of these cell lines spontaneously releases complete type C virions, they all contain RNA which is partially homologous to a portion of the 35S RNA isolated from these viruses. The parental cell line, BALB/c 3T3, contains a low level of viral-related RNA, and there is an increased amount of this RNA in some of the transformed cells. The RNA detected represents only a fraction of the viral RNA found in virus-producing cells. The formation of RNA:DNA hybrids was detected by equilibrium centrifugation in Cs(2)SO(4) density gradients and by analysis with a single-strand-specific nuclease from Aspergillus oryzae. Viral DNA products prepared either from an endogenous reaction with whole virus in the presence of actinomycin D or from purified 70S viral RNA as template using avian myeloblastosis virus DNA polymerase yield comparable data. In addition, all of the BALB/c lines examined produce detectable levels of murine type C virus group-specific antigen.     

The meiotic stage of nondisjunction in trisomy 21: Determination by using DNA polymorphisms

We have studied DNA polymorphisms at loci in the pericentromeric region on the long arm of chromosome 21 in 200 families with trisomy 21, in order to determine the meiotic origin of nondisjunction. Maintenance of heterozygosity for parental markers in the individual with trisomy 21 was interpreted as resulting from a meiosis I error, while reduction to homozygosity was attributed to a meiosis II error. Nondisjunction was paternal in 9 cases and was maternal in 188 cases, as reported earlier. Among the 188 maternal cases, nondisjunction occurred in meiosis I in 128 cases and in meiosis II in 38 cases; in 22 cases the DNA markers used were uninformative. Therefore meiosis I was responsible for 77.1% and meiosis II for 22.9% of maternal nondisjunction. Among the 9 paternal nondisjunction cases the error occurred in meiosis I in 2 cases (22.2%) and in meiosis II in 7 (77.8%) cases. Since there was no significant difference in the distribution of maternal ages between maternal I error versus maternal II error, it is unlikely that an error at a particular of maternal ages between maternal I error versus maternal II error, it is unlikely that an error at a particular meiotic stage contributes significantly to the increasing incidence of Down syndrome with advancing maternal age. Although the DNA polymorphisms used were at loci which map close to the centromere, it is likely that rare errors in meiotic-origin assignments may have occurred because of a small number of crossovers between the markers and the centromere.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nuclear genes coding for four subunits of the yeast ubiquinol-cytochrome c reductase complex are present in single copies in the haploid genome and at least two of these are located on different chromosomes

Summary Genes coding for the 40 kilodaltons (kDa), 17-kDa, 14-kDa and 11-kDa subunits of the ubiquinol-cytochrome c reductase in yeast are present in single copies in the haploid genome. We have mapped each gene to a unique genomic environment and demonstrate that integration of cloned segments into nuclear DNA by homologous crossing-over with the endogenous gene results in the replacement of the corresponding chromosomal restriction fragment by fragments of predicted sizes. Chromosomal mapping, carried out by the procedure of Falco and Botstein 1983, indicates that the gene for the 17-kDa subunit lies on chromosome VI and that for the 11-kDa subunit on chromosome XII.     

No enhanced recognition memory,but better source memory for faces of cheaters

Previous studies sought to test for the existence of a “cheater-detection module” by testing for enhanced memory for the faces of cheaters, but past results have been inconclusive. Here, we present four experiments showing that old–new discrimination was not affected by whether a face was associated with a history of cheating, trustworthy or irrelevant behavior. In contrast, source memory for faces associated with a history of cheating (i.e., memory for the cheating context in which the face was encountered) was consistently better than source memory for other types of faces. This pattern held under a variety of conditions, including different types of judgments participants made about the stimulus persons (attractiveness in Experiment 1; likeability in Experiments 2–4), different retention intervals (a few minutes in Experiments 1, 2 and 4; 1 week in Experiment 3), whether the behaviors were exceptional or ordinary (Experiments 1–3) and whether the social status of the characters was low or high (Experiment 4). Given no differences in old–new discrimination, enhanced source memory for faces of cheaters may be useful for avoiding cheaters in future interactions.     

The Role of Free Radicals in Paraquat-Induced Corneal Lesions

Paraquat is a synthetic bipyridylium salt widely used as herbicide and defoliant. Enzyme-catalyzed redox-cycling of paraquat generates oxygen radicals. The toxic, even lethal, effects of paraquat are due to free radical-mediated tissue injury. Ocular lesions, sometimes quite severe, have been observed following accidental splashing of paraquat solutions onto the eyes.

These studies were designed to document the generation of paraquat free radicals in corneal tissue, and to describe the histological nature of the corneal injuries in experimental animals (rabbits and monkeys). The EPR spectrum of rabbit corneas, 30 min. after intrastromal injection of paraquat, showed the signal of the free radical of paraquat. Ultrastructural studies of corneas 8 days after intrastromal injections (100μl) of paraquat solutions showed that the initial lesions occur at the epithelium/basement membrane interface. In rabbit cornea, dose dependent lesions were observed, i.e. whereas 50 mM paraquat caused only minimal damage to the epithelial basement membrane, 75 mM caused complete dissolution to the basement membrane with some damage to stromal collagen, and loss of epithelium with stromal ulceration and severe inflammatory response were observed with 150 mM paraquat. Monkey corneas were less susceptible than those of rabbits to the effects of paraquat. No lesions were observed following intrastromal injections of 50 mM or 75 mM paraquat. With higher concentrations of paraquat (100 mM and 150 mM) the primary injuries were to the proximal and lateral plasma membranes of basal epithelial cells; basement membrane alterations were detected only adjacent to areas of significant plasma membrane damage. The underlying Bowman's membrane and stroma were not affected. Anatomical differences between the corneas of rabbit and monkeys as well as possible biochemical differences may account for the species differences observed.     

Characterization of a binding site for chemically synthesized lipo-oligosaccharidic NodRm factors in particulate fractions prepared from roots

This paper describes the characteristics of a binding site for the major, lipo-oligosaccharide Nod factor of Rhizobium meliloti in roots of the symbiotic host plant, Medicago truncatula. Chemically synthesized NodRm-IV(Ac, S, C16:2) was labelled by tritiation to a specific activity of 56 Ci mmol^?1 and this ligand was shown to be biologically active in the root hair deformation assay at 10^?11 M. Binding of the ligand to a particulate fraction from roots of M. truncatula was found to be saturable and reversible with an affinity (K_d) of 86 nM and the binding characteristics were consistent with a single class of binding sites. Competition with modified Nod factors showed that the binding was independent of both the O-acetyl and the sulphyl group and did not depend on the unsaturation of the fatty acid. However, both moieties of the lipo-oligosaccharide are required for high-affinity binding since tetra-N-acetyl-chitotetraose and palmitate were found to be poor competitors of ligand binding. A binding site with analogous characteristics was also found in a similarly prepared particulate fraction of tomato roots. This binding site for Nod factors, termed NFBS1, which is present in both a leguminous and a non-leguminous plant, may have a more general role than symbiosis.