Linkage analysis of chromosome 17 markers in British and South African families with neurofibromatosis type 1

Nine markers from the pericentromeric region of chromosome 17 were typed in 16 British and five South African families with neurofibromatosis type 1 (NF1). The markers--p17H8, pHHH202, and EW204--were linked to NF1 at recombination fractions less than 1%. No evidence of locus heterogeneity was detected. Inspection of recombinant events in families informative for several markers suggests that the NF1 gene is located between the markers EW301 (cen-p11.2) and EW206 (cen-q12) and possibly distal to pHHH202 (q11.2-q12).     

Solution conformation of d-CTCGAGCTCGAG by two-dimensional NMR: conformational heterogeneity at XhoI cleavage site

Nonexchangeable proton resonances in the 500-MHz NMR spectrum of d-CTCGAGCTCGAG have been assigned by using two-dimensional correlated spectroscopy (COSY) and nuclear Overhauser enhancement spectroscopy (NOESY). 1H-1H coupling constants (J) in the deoxyribose rings have been measured by analyzing intensity and multiplet patterns in the phase-sensitive omega 1-scaled COSY spectra. A modification of the J-resolved technique, called amplitude-modulated J-resolved spectroscopy, has been described and used to increase the accuracy of J measurements. Absorption mode omega 1-scaled NOESY spectra at mixing times in the range 50-200 ms have been analyzed to monitor spin diffusion. A 50-ms spectrum has been used to estimate several interproton distances. The coupling constant and distance data have been used to arrive at sequence-specific sugar geometries and glycosidic torsion angles. The backbone structure has been refined by model building using the FRODO program, employing the sugar geometries and glycosidic torsion angles discussed above. The molecule shows interesting sequence-dependent variations in the structure. The cleavage site of the restriction enzyme XhoI exhibits unique differences in the sugar geometry and backbone torsion angles.     

Detection of surface charge-related properties in model membrane systems by aqueous two-phase partition

Unilamellar vesicles composed of phosphatidylcholine (PC) and either phosphatidic acid (PA) or phosphatidylglycerol (PG) partition to the upper poly(ethylene glycol) (PEG)-rich phase of a charge-sensitive 5%:5% (w/w) PEG 8000/Dextran T-500 phase system containing 10 mM sodium phosphate at pH 7, consistent with the vesicles bearing a net negative charge. When prepared in the presence of a pH gradient (interior acidic), PC/PA vesicles exhibit an increased partition to the top PEG-rich phase, consistent with a redistribution of the PA from the inner to the outer monolayer of the vesicle bilayer. Conversely, when prepared in the presence of a pH gradient (interior basic), PC/PG vesicles exhibit a decreased top-phase partition, consistent with a redistribution of the PG from the outer to the inner monolayer of the vesicle bilayer. Unilamellar vesicles composed of PC and stearylamine partition to the lower dextran-rich phase of a 5%:5% (w/w) PEG 8000/Dextran T-500 phase system containing 10 mM sodium phosphate at pH 8.5, consistent with the vesicles bearing a net positive charge. When prepared in the presence of a pH gradient (interior acidic), conditions under which the stearylamine is trapped on the inner monolayer of the bilayer, the vesicles now partition predominantly to the interface in a manner similar to vesicles composed of PC alone. These results demonstrate that partitioning in aqueous two-phase polymer systems is a sensitive method for monitoring the asymmetry of charged lipids in model membrane systems and also suggests that partitioning in charge-sensitive systems depends only on the physical nature of the exterior surface of the membrane.     

Tasmania revisited: rotifer communities and habitat heterogeneity

The results of four field surveys for Rotifera in Tasmania are summarized. Most new species and records in a 1987 survey were from acid waters (pH < 4.0) of dune lakes on the west coast (42° S). Marked intra- and interhabitat differences in rotifer communities of lakes and ponds were demonstrated by cluster analysis and related to habitat heterogeneity.     

Establishment and characterization of a human chorionic gonadotropin (hCG) producing cell line (RTSG) from an ovarian epithelial cancer

A new cell line designated RTSG established in vitro from the pleural effusion of a patient with metastatic ovarian epithelial cancer has been subcultured 46 times for more than 2 years. The cells grew in a monolayered sheet, showing a tendency to pile up, with the population doubling in 48 hrs. Electron-microscopically, desmosomes were characteristically observed, suggesting the cells were of epithelial origin. Chromosomal analysis revealed aneuploidy with a tetraploid mode. The heterotransplanted tumors in nude mice were histopathologically classified as a poorly differentiated adenocarcinoma, whereas the original tumor consisted mainly of mucinous and serous cystadenocarcinoma and only partly of poorly differentiated adenocarcinoma. The cells secreted hCG (38.8 mIU/day/10(6) cells) and beta-hCG (6.1 ng/day/10(6) cells) in spent medium. Immunocytologic +-and-histochemical staining for tumor markers of the original tumor, the cultured cells and the transplanted tumors also revealed the localization of not only hCG and beta-hCG but also CA19-9 and CA-125 whose values had been elevated in the preoperative serum (hCG: 10 mIU/ml, CA19-9: 6,400 U/ml, CA-125: 225 U/ml). Results of PAS, Alcian-blue and Mucicarmine strains indicated that most of the PAS-positive substances in the cultured cells and the transplanted tumors were consistent with glycogen while the original tumor mainly contained mucin except for the lesion of poorly differentiated adenocarcinoma with glycogen. These results suggested that the cultured cells might originate from poorly differentiated adenocarcinoma cells in the original tumor.     

Recovery of functional DNA inserts by electroendosmotic elution during gel electrophoresis

In contrast to all previous preparative electrophoresis apparatus which used a pump, electroendosmotic elution uses bound electrical charges at the end of the separating gel to generate a buffer flow. The electroendosmotic flow increased with increasing currents and decreasing buffer concentrations: its exact characteristics for the built apparatus were determined. The electroendosmotic device was able to separate two DNA fragments differing in size by only 5% with a recovery over 95%. As demonstrated in practical examples of recovery and uses of DNA inserts, up to 10 micrograms of DNA per band can be loaded at a time. The recovered DNA can be used directly for nick-translation, ligation... without further treatment. The performances of the method are expected to improve still further if the charge density and pores of the electroendosmotic medium can be "made-to-order" to provide a better flow profile of the eluting buffer.     

The T cell receptor V alpha 3 gene segment is associated with reactivity to p-azobenzenearsonate

The murine T cell receptor V alpha 3 gene segment is associated with reactivity to p-azobenzenearsonate, as indicated by several independent lines of evidence. First, three out of four arsonate-reactive T cell clones tested (two I-Ad-and one I-Ak-restricted) utilized V alpha 3. Second, bulk splenic cultures enriched for arsonate/H-2d and arsonate/H-2k responsive T cells showed increased expression of V alpha 3 mRNA. Third, a V alpha 3-containing alpha chain (Ar-5: arsonate/I-Ad) transferred arsonate responsiveness to an appropriate recipient T cell (O3: ovalbumin/I-Ad). Fourth, an independently derived V alpha 3-expressing T cell clone (2C: alloreactive to Ld) showed a response to arsonate/Ld. Thus, a V alpha 3 gene segment, in conjunction with at least two different J alpha segments (J alpha 20'(Ar-5) and J alpha pHDS58(2C)) and at least three different beta chains (V beta 2(Ar-5), V beta 6(O3), and V beta 8(2C], confers reactivity to arsonate in association with at least three different MHC proteins (I-Ad, I-Ak, and Ld). We suggest that V alpha 3 encodes a protein sequence with a binding site for the arsonate hapten.     

Selective solubilization of xylan in pulp using a purified xylanase fromTrichoderma harzianum

Summary The specificity of action of a cellulase-free xylanase preparation on pulp fibers was revealed by the composition of the solubilized products after enzyme treatment. The neutral carbohydrates released by the treatment of two hardwood kraft pulps were composed exclusively of xylooligomers. A similar treatment of Solka Floc showed no detrimental effect on the degree of polymerization of the cellulose fibers, as determined by size exclusion chromatographic analysis.     

Selective failure of androgens to regulate follicle stimulating hormone beta messenger ribonucleic acid levels in the male rat

FSH beta, as well as LH beta, and alpha-subunit mRNA levels were examined in the pituitary glands of male rats after sex steroid replacement at various times (7, 28, or 90 days) after orchiectomy. Testosterone propionate, dihydrotestosterone propionate, or 17 beta-estradiol benzoate (E) were administered daily for 7 days before killing, to assess the role of different gonadal steroids on gonadotropin subunit mRNA levels. Subunit mRNAs were determined by blot hybridization using rat FSH beta genomic DNA, and alpha and LH beta cDNAs. At all time points, alpha and LH beta mRNAs increased after gonadectomy and fell toward normal levels with either androgen or estrogen replacement. FSH beta mRNA levels increased variably postcastration: 4-fold at 7 days, 2-fold at 28 days, and 4- to 5-fold at 90 days. Although E replacement uniformly suppressed FSH beta mRNAs, neither testosterone propionate nor dihydrotestosterone propionate administration suppressed FSH beta mRNA levels at any time point after orchiectomy. These data demonstrate that there is a relative lack of negative regulation of FSH beta mRNA levels by androgens in a paradigm in which E administration results in marked negative regulation of FSH beta mRNA levels. Thus, in the male rat, estrogens negatively regulate all three gonadotropin subunit mRNA levels while androgens negative regulate LH beta and alpha-subunit but fail to suppress FSH beta mRNAs.     

Maternal fatness and viability of preterm infants

To investigate the effect of maternal fatness on the mortality of infants born preterm up to the corrected age of 18 months 795 mother-infant pairs were studied. Maternal fatness was defined by Quetelet''s index (weight/(height²)) and all infants weighed less than 1850 g at birth. In 771 mother-infant pairs maternal age, complications of pregnancy, mode of delivery, parity, social class, and the baby''s sex and gestation were analysed by a logistic regression model for associations with infant mortality (but deaths from severe congenital abnormalities and those occurring during the first 48 hours after birth were excluded). In a subgroup of 284 mother-infant pairs all infant deaths except those from severe congenital abnormalities were analysed in association with the infant''s birth weight and gestation and the mother''s height and weight; this second analysis included another 24 infants who had died within 48 hours after birth. In the first analysis mortality overall was 7% (55/771), rising from 4% (71/173) in thin mothers (Quetelet''s index <20) to 15% (6/40) in mothers with grades II and III obesity (Quetelet''s index >30). After adjusting for major demographic and antenatal factors, including serious complications of pregnancy, maternal fatness was second in importance only to length of gestation in predicting death of infants born preterm. In the second analysis mortality overall was 15% (44/284), rising from 9% (5/53) in thin mothers to 47% (8/17) in mothers with grades II and III obesity. In both analyses the relative risk of death by 18 months post-term was nearly four times greater in infants born to obese mothers than in those born to thin mothers. In addition, maternal fatness was associated with reduced birth weight, whereas it is associated with macrosomia in term infants.These data differ fundamentally from those reported in full term babies of obese mothers. It is speculated that the altered metabolic milieu in obesity may reduce the ability of the fetus to adapt to extrauterine life if it is born preterm.