A mechanochemical study of MgDNA fibers in ethanol-water solutions

Highly oriented calf-thymus MgDNA fibers, prepared by a wet spinning method, were studied with a simple mechanochemical set-up. The relative fiber length, L/Lo, was measured with the fibers submerged in ethanol-water solutions. In one type of experiment L/Lo was measured as a function of ethanol concentration at room temperature. No substantial decrease in L/Lo with increasing ethanol concentration was observed, indicating that MgDNA fibers stay in the B form even when the water activity is very low. For low ethanol concentrations the fiber structure is stable and does not dissolve even at very high water activities. In a second type of experiment, the heat-induced helix-coil transition was manifested by a marked contraction of the fibers. The transition temperature decreases linearly with increasing ethanol concentration between 52 and 68% ethanol. At higher ethanol concentrations the helix-coil transition temperature increases due to strong aggregation within the DNA fibers, and above 77% ethanol the fibers do not contract at all, not even at the upper temperature limit of the experiments, approximately 80 degrees C. This behavior is discussed with reference to dried DNA and the P form of DNA. The helix-coil transition temperature of the MgDNA fibers in 70% ethanol does not show any dependence on the MgCl2 concentration. It is shown that the Poisson-Boltzmann cylindrical cell model can account qualitatively for this lack of salt dependence.

Differences in cell surface carbohydrates, and in laminin and fibronectin synthesis, between adherent and non-adherent Ehrlich ascites tumor cells

Differences in cell surface carbohydrates and in laminin and fibronectin synthesis between 2 Ehrlich ascites tumor (EAT) cell lines, the adherent and non-adherent EAT cells, have been studied. The adherent EAT (a-EAT) cells grow in monolayer in vitro in the presence of fetal bovine serum. The classical, or non-adherent EAT (na-EAT), cells grow in suspension in ascites form in the peritoneal cavity of mice, and they do not adhere when cultured in vitro. Both EAT cell lines express surface glycoproteins reactive with Maackia amurensis lectin (MAL) and Griffonia simplicifolia isolectin GS I-B4. However, only a-EAT cells react with elderberry (Sambucus nigra) bark lectin (SNA), suggesting that there are some differences in the sialylation of cell surface carbohydrate moieties between these 2 EAT cell lines. Removal of cell surface sialic acid by treating a-EAT cells with Vibrio cholerae neuraminidase did not abolish the ability of these cells to adhere to laminin- or fibronectin-coated plates, indicating that the sialic acid of the cell surface glycoproteins is not essential for their adhesion to these extracellular matrices. Therefore, the difference in sialylation of cell surface glycoproteins is not responsible for the difference in cell adhesion between these 2 lines of EAT cells. Both EAT cell lines express detectable amounts of laminin but not fibronectin on their surfaces; they both secrete fibronectin and entactin into the medium. The na-EAT cells (but not the a-EAT cells) also secrete laminin A chain into the culture medium; however, no B chain was detected in the culture medium of either cell line. The laminin isolated from the cell surface of na-EAT cells reacts with GS I and MAL lectins, but not with SNA, whereas the laminin isolated from a-EAT cells reacts with SNA, as well as GS I and MAL.

The isolation of a yeast artificial chromosome (YAC) contig extending for 2 megabases in the vicinity of the von Hippel Lindau disease gene

Von Hippel Lindau disease (VHL) is a rare autosomal dominant disease associated with tumors and cysts in multiple organ systems. The VHL disease gene is tightly linked to the polymorphic DNA marker 233E2 (D3S720) and flanked by 479H4 (D3S719) on its telomeric and RAF1 on its centromeric side. Two additional markers, D3S1038 and D3S601, have also been identified, and these markers, like D3S720, are very tightly linked to VHL. Previously 93 cosmid clones were mapped to the larger region, 3p24.2-pter, surrounding the VHL disease gene. Using a Southern-based screening strategy on pools of YAC clones we have isolated a contig of overlapping YAC clones that extends about 0.7 megabase centromeric, and about 1.3 megabases telomeric of D3S720 and contains all three tightly linked VHL markers. Individual YACs in this contig were hybridized to grids containing cosmids localized between 3p24.2-pter and to several cosmids localized by fluorescent in situ hybridization (FISH) to 3p25. A total of 28 cosmids were positioned on this contig of overlapping YAC clones. We have also identified homologous YAC clones to many additional cosmid clones localized between 3p24.2-p25, although these have not yet been precisely localized relative to the contig of YAC clones. This contig of YAC clones probably contains the VHL disease gene and should facilitate the isolation and characterization of this gene.

Sideband suppression in magic-angle-spinning NMR by a sequence of 5 pi pulses

We report a symmetrical sequence of 5 pi pulses for total sideband suppression in magic-angle-spinning NMR. The sequence is almost evenly spaced and shorter than previous 4 and 6 pi pulse methods.

[The multi-channel VEPs topography in optic neuritis]

The multi-channel VEPs topographies of 20 normal persons and 22 patients suffered from optic neuritis were recorded. In normal subjects, the topography showed symmetric distribution by full-field stimulation and paradoxical lateralization by half-field stimulation. In patients with optic neuritis, it showed asymmetric distribution most on the temperal side, some on the nasal side and occasionally in the middle by full-field stimulation. The result suggests that the optic nerve may be damaged on either temperal or nasal. The effect of the early diagnosis and evaluating treatment using topography is also discussed.

[Formation of mouse chimeras from early embryonic pluripotential stem cell]

Three chimeric mice were produced by injecting the embryonic stem cell-CCE cells into the cavity of 3.5 day host blastocysts from Kunming and C57BL/6J mice. By analyses of glucose phosphate isomerase (GPI-1), the results show a contribution from CCE cells in heart tissue of female Kunming chimera. Breeding experiments demonstrated that all chimeric mice were fertile but none of 3 chimeras produced germ line transmission.

Detection of bovine leukemia virus RNA in serum using the polymerase chain reaction

A method was developed for detecting bovine leukemia virus (BLV) RNA in serum samples using a pair of primers from the BLV polymerase gene in the polymerase chain reaction (PCR). The PCR was able to detect 3800-7600 molecules of BLV RNA. At this level of sensitivity eleven pools of adult and one fetal bovine serum appeared free from BLV contamination.

Proviral detection and serology in bovine leukemia virus-exposed normal cattle and cattle with lymphoma

Twenty-seven cattle with lymphoma and 46 cows from a known bovine leukemia virus (BLV)-infected herd were tested for anti-BLV antibody by the agar gel immunodiffusion (AGID) test and an enzyme-linked immunosorbent assay (ELISA). The polymerase chain reaction (PCR) and Southern hybridization were used to detect BLV provirus in the tumor DNA of the 27 cattle with lymphoma. The PCR was used to detect BLV provirus in the peripheral blood mononuclear cell DNA of the 46 normal known-exposed cattle. Two presumed false negative AGID test results compared to ELISA were found. Of ten cattle three years of age or less with "sporadic" forms of lymphoma, four had BLV provirus in tumor DNA, detectable by PCR. In two of these four, BLV provirus was clonally integrated based on digestion of tumor DNA with restriction enzymes followed by Southern hybridization. The BLV provirus was not detected by PCR in 5 of 17 cattle with "enzootic" lymphoma and two of these five were seronegative. Among normal BLV-exposed cows, 6.5% (3 of 46) were serologically positive and PCR negative; serologically negative and PCR positive cows occurred with the same frequency. Serological and PCR test results, when considered in all cattle (n = 73), had a concordance rate of 83.6%. Discordant test results occurred with approximately equal frequency between serologically positive and PCR negative (7 of 73, 9.6%) and serologically negative and PCR positive (5 of 73, 6.8%) groups. These data suggest that the role of BLV in some "sporadic" bovine lymphomas, previously unassociated with BLV, should be reexamined. The BLV provirus was not demonstrable in the tumor DNA from five adult cattle with lymphoma, suggesting that BLV may not be the etiological agent in all adult bovine lymphomas. The findings of persistently seronegative PCR positive and seropositive PCR negative cattle indicate that further work is needed to more fully understand the host-virus interaction. Present serological screening methods may not have sufficient sensitivity for determining BLV status in some circumstances.

The formation of A-DNA in NaDNA films is suppressed by netropsin

Oriented films of NaDNA complexed with netropsin were studied with deuterium nuclear magnetic resonance (2H NMR), X-ray diffraction and ultraviolet (UV) linear dichroism to obtain information about the influence of netropsin on the structural arrangement of the DNA bases and on the B-A transition. The results of these studies clearly demonstrate a strong suppression of the formation of A-DNA at relative humidities (RHs) down to about 50%. The suppression was complete in the NaDNA-netropsin complex studied with 2H NMR which had a netropsin input ratio, r, of 0.22 drug/base pair. The sample used for UV linear dichroism had a similar input ratio while the X-ray diffraction samples had input ratios between 0.033 and 0.39 drug/base pair. Together, the results of these studies are in agreement with previous infrared (IR) linear dichroism studies of the conformation of the sugar-phosphate backbone in NaDNA-netropsin complexes, which showed that the B-A transition is suppressed for r-values down to approximately 0.1 drug/base pair (Fritzsche, H., Rupprecht, A. and Richter, M., Nucleic Acids Res. 12 (1984) 9165-9177).

[Report of 4 cases of Chlamydia infection in the urogenital tract]

Four cases of Chlamydia infection of the urogenital tract were received-recently in our out-patient clinic for foreign patients. The 4 patients were two couples. Both male patients had histories of coitus with other partners: among these two, one had suffered gonorrhea and the other was suspected of having had gonorrhea. Urogenital tract symptoms or sustained abnormal urine analysis results are characteristic of this disease, but in females often no obvious symptoms present. Measurements with fluorescence-labeled Chlamydia trachomatis monoclonal antibody provided a simple and accurate method and was used in the diagnosis of this disease. All the 4 cases were cured by tetracycline. Finally, current epidemics, infectious features, diagnosis and treatment for this disease are discussed.

[Quantitative analysis of calcium bilirubin in calculus bovis by infrared spectrometry]

This paper reports the method of quantitative analysis of calcium bilirubin in calculus bovis by infrared spectrometry. This method is simple and quick, requiring no separation and only small amount of sample, not destroying the sample and having few interferences.

Lithium stimulation of murine hematopoiesis in liquid culture: an effect mediated by marrow stromal cells

Lithium has previously been observed to stimulate in vitro Dexter culture hemopoiesis with increases in granulocytes, megakaryocytes, and pluripotent stem cells (CFU-S). In the present study, a two-phase murine Dexter culture system was established to study the mechanism of lithium-mediated stem cell stimulation. Different lots of horse sera or fetal calf sera were found to have markedly different effects on Dexter culture growth; given the appropriate sera supplementation, supernatant cells from Dexter cultures established from C57BL/6J mice 3 wk previously were free of stromal-forming capacity, but had stem cells and could grow on 900-950 R irradiated stroma. Conversely, in vitro irradiation (900-950 R) of 3-wk cultures resulted in a stem-cell-free adherent monolayer that could support growth for up to 9 wk in culture. The stroma from Dexter cultures preexposed to lithium chloride (1.0 mmole/liter) for 3 wk, irradiated (900 R), and then refed with 3-wk Dexter supernatant cells has an enhanced capacity to support cell production, CFU-S, and probably granulocyte-macrophage colony-forming cell (GM-CFU-C) production, as compared to stroma not preexposed to lithium. Lithium carryover was ruled out in these experiments. These data indicate that lithium stimulates CFU-S and in vitro granulopoiesis by an indirect effect on a radioresistant adherent stromal cell.