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11.
We screened cryostat sections of tissues from 10 inbred strains of mice with a panel of conjugated lectins, in a search for polymorphisms which could be used as markers in mouse chimeras. In DDK and RIII mice, but not the other strains tested, there are binding sites on the membrane of vascular endothelial cells for Dolichos biflorus agglutinin (DBA), which is specific for terminal nonreducing N-acetyl galactosamine residues. The expression of DBA binding sites on RIII and DDK endothelium is not, however, uniform: there are consistent differences between blood vessels in different organs. These observations provide evidence of an organ-related heterogeneity in vascular endothelium which is open to biochemical analysis, and which raises the possibility that endothelial cells carry a “tissue address.” 相似文献
12.
Maureen Merrett 《Archives of microbiology》1969,69(1):1-11
Summary Eight species of Olpidium are reported from freshwater algae and from soils in Iceland. Similarities between Olpidium endogenum and O. entophytum are discussed. On the basis of the specimens at hand and the substrates in which they occur, O. zygnemicola and O. spirogyrae are reduced to synonymy with O. entophytum and O. endogenum respectively. Olpidioid fungi in Oedogonium and sterilized pine pollen are tentatively assigned to the doubtfully distinct species O. saccatum and O. utriculiforme. Olpidium pendulum, O. luxurians, and O. longicollum occur in pine pollen bait in gross water cultures of soil. These three species are only doubtfully distinct entities. Olpidium rhizophlyctidis is reported for the first time from Iceland. 相似文献
13.
14.
Jeffery R. Cook Barbara E. Crute Laura M. Patrone Joseph Gabriels Maureen E. Lane Robert G. van Buskirk 《In vitro cellular & developmental biology. Plant》1989,25(10):914-922
Summary We have analyzed the ability of the physical substratum to modulate both the ultrastructural and protein synthetic characteristics
of the Madin-Darby canine kidney (MDCK) renal cell line. When MDCK cells were seeded on Millipore Millicell CM microporous
membrane cell culture inserts they demonstrated a more columnar organization with an increase in cell density sixfold greater
than the same cells seeded on conventional plastic substrata. After 1 wk postseeding on the microporous membrane a partial
basal lamina was noted, with a contiguous basement membrane being apparent after 2 wk. One-dimensional sodium dodecyl sulfate
gel electrophoresis was used to analyze detergent-solubilized proteins from MDCK cells maintained on plastic substrata vs.
microporous membranes. When proteins were pulse-labeled with [35S]methionine, a 55 kDa protein was evident in the cytosolic extract of cells grown on collagen, laminin, and nontreated plastic
substrata; but this labeled protein was not evident in similar extracts from cells grown on collagen and laminin-coated microporous
membranes. To test if the polarized, basement-membrane secreting phenotype of the MDCK cells could be generated on a microporous
membrane without pretreatment with any extracellular matrix (ECM) components, cells were seeded on the Millipore Millicell
HA (cellulosic) microporous membrane. This type of substrata does not need a coating of ECM components for cell attachment.
A partial basement membrane was formed below cells where the basal surface of the cell was planar, but not in areas where
the cell formed large cytoplasmic extensions into the filter. This led us to the conclusion that the microporous nature of
the substrata can dictate both ultrastructural and protein synthetic activities of MDCK cells. Furthermore, we suggest that
both the planar nature of the basal surface and the microporosity of the substrate are corequisites for the deposition of
the basement membrane. 相似文献
15.
16.
17.
A. Fitzsimons F. Duffner D. Curtin G. Brophy P. O'Kiely M. O'Connell 《Applied microbiology》1992,58(9):3047-3052
Eighteen Pediococcus strains were screened for their potential as silage inoculants. Pediococcus acidilactici G24 was found to be the most suitable, exhibiting a short lag phase on both glucose and fructose, a rapid rate of acid production, a high sugar-to-lactate conversion efficiency, no detectable breakdown of proteins or lactic acid, and the ability to grow within a broad range of pH and temperature. When tested in laboratory silos using grass with a water-soluble carbohydrate content of 24 g/kg of aqueous extract, P. acidilactici G24 stimulated the natural Lactobacillus plantarum population and accelerated the rates of lactic acid production and pH decrease. After 6 days of fermentation, the inoculated silage exhibited a 12% decrease in ammonia nitrogen and an 11% increase in crude protein levels compared with uninoculated controls. The use of an L. plantarum inoculant at a rate of 104 bacteria per g of grass in conjunction with P. acidilactici G24 produced no additional beneficial effect. Inoculation of grass with a water-soluble carbohydrate level of 8 g/kg of aqueous extract with P. acidilactici G24 led to no acceleration in the rate of L. plantarum growth or pH decrease. However, after 7 days of fermentation the inoculated silage had a 14% lower ammonia nitrogen protein content than did uninoculated controls. The results suggest that P. acidilactici G24 may be useful as a silage inoculant for crops with a sufficiently high water-soluble carbohydrate level. 相似文献
18.
Frank P. Zemlan Anne Zieleniewski-Murphy R. Maureen Murphy Michael M. Behbehani 《Neurochemistry international》1990,16(4):515-522
Recent data indicate that BMY 7378 demonstrates high affinity, selectivity and low intrinsic activity at hippocampal 5-HT1A receptors, suggesting that BMY 7378 may represent the first selective 5-HT1A functional antagonist. The present study examined the agonist and antagonist properties of BMY 7378 at spinal cord 5-HT1A receptors. In electrophysiological studies, iontophoretic administration of either the 5-HT1A agonist 8-OH-DPAT (43.8 ± 5.4 nA) or BMY 7378 (46.3 ± 5.2 nA) significantly inhibited the firing rate of wide-dynamic-range dorsal horn units indicating that BMY 7378 demonstrates significant intrinsic activity at spinal cord 5-HT1A receptors. Concomitant BMY 7378 and 8-OH-DPAT administration identified no BMY 7378 ejection current (20–100 nA) which antagonized the 8-OH-DPAT induced inhibition of dorsal horn unit activity. In behavioral studies in the spinal rat, 8-OH-DPAT increased the animals' sensitivity to noxious levels of mechanical stimulation (ED50 = 269 ± 24 nmol/kg) as did BMY 7378 (ED50 = 295 ± 70 nmol/kg) with no statistically significant difference in the maximal response (Ymax) observed. Concomitant BMY 7378 and 8-OH-DPAT administration identified no BMY 7378 dose (10–1100 nmol/kg) which blocked the hyperalgesic effect of 8-OH-DPAT, rather, each drug produced similar effects which were additive. Further, the 5-HT1A agonist effects of BMY 7378 were blocked by the 5-HT1A antagonist, spiperone. Therefore, both the electrophysiologic and reflex data indicate that BMY 7378 possesses significant intrinsic activity at spinal cord 5-HT1A receptors, and like 8-OH-DPAT is a partial agonist at these receptors. Differences in BMY 7378 intrinsic activity at spinal cord as opposed to hippocampal 5-HT1A receptors are discussed in terms of regional differences in G-proteins coupled to 5-HT1A receptors in these two CNS regions. 相似文献
19.
Alessandro Pintar Meike Hensmann Kornelia Jumel Maureen Pitkeathly Stephen E. Harding Iain D. Campbell 《European biophysics journal : EBJ》1996,24(6):371-380
The SH2 domain from Fyn tyrosine kinase, corresponding to residues 155–270 of the human enzyme, was expressed as a GST-fusion protein in a pGEX-E. coli system. After thrombin cleavage and removal of GST, the protein was studied by heteronuclear NMR. Two different phosphotyrosyl-peptides were synthesized and added to the SH2 domain. One peptide corresponded to the regulatory C-terminal tail region of Fyn. Sequence-specific assignment of NMR spectra was achieved using a combination of1H-15N-correlated 2D HSQC,15N-edited 3D TOCSY-HMQC, and15N-edited 3D NOESY-HMQC spectra. By analysis of the -proton chemical shifts and NOE intensities, the positions of secondary structural elements were determined and found to correspond closely to that seen in the crystal structure of the, homologous, Src-SH2 domain.To investigate the internal dynamics of the protein backbone, T1 and T2 relaxation parameters were measured on the free protein, as well as on both peptide complexes. Analytical ultracentrifugation and dynamic light scattering were employed to measure the effect of concentration and peptide-binding on self-association. The results suggest that, at NMR-sample concentrations, the free protein is present in at least dimeric form. Phosphopeptide binding and lower concentration significantly, but not completely, shift the equilibrium towards monomers. The possible role of this protein association in the regulation of the Src-family tyrosine kinases is discussed.Abbreviations SH
Src homology
- GST
glutathione-S-transferase
- IPTG
isopropyl--D-galactopyranoside
- DTT
dithiothreitol
- PMSF
phenyl-methyl-sulphonyl-fluoride
- TBS
50 mM Tris, 150 mM NaCl, 5 mM DTT, pH 8.0
- MWCO
molecular weight cut off
- NMR
nuclear magnetic resonance
- HSQC
heteronuclear single-quantum correlation
- NOESY
nuclear Overhauser effect spectroscopy 相似文献
20.
Given the current interest in potential carcinogenic and developmental effects of exposure to extremely-low-frequency electromagnetic fields, there is a need to identify cohorts of exposed female workers for future epidemiologic investigations. This study was designed to test the hypothesis that nurses working in neonatal intensive care units (NICU) may be significantly exposed to power-frequency magnetic fields. An electromagnetic field monitor was used to measure magnetic fields at distances of 5, 15, 30, and 60 cm from the surfaces of each device used in the NICU. Six female nurses assigned to the NICU (the “exposed” group) and six female nurses working in the normal newborn nursery (the “referent” group) wore EMDEX dosimeters for the entire duration of their 12 h shifts. An investigator kept a detailed log of each NICU subject's whereabouts for the first one-third of her shift. Magnetic fields at 5 cm from the front (defined by the nurses' usual work area) of the NICU devices ranged from less than 0.1 to 114 μT and in all cases decreased considerably with increasing distance. The geometric mean of the shift-time-weighted average exposure of the NICU nurses was 0.17 μT compared with 0.11 μT for the normal newborn nurses. The percentage of time when subjects were exposed to magnetic fields of 0.4 μT or greater ranged from 5.8% to 15.6% for the NICU nurses, 0.4% to 2.9% for five of the comparison group nurses, and was 9.4% for one of the normal newborn nurses with unidentified aberrantly high exposures. Log data revealed that the vast majority of observed peaks among NICU nurses occurred while subjects were in close proximity to infant bed units. We conclude that NICU nurses represent one female-intensive job sector with intermittent high exposures to ELF magnetic fields and encourage larger exposure studies of nurses in a variety of medical settings. © 1994 Wiley-Liss, Inc. 相似文献