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41.
Human ovarian surface epithelium in primary culture 总被引:6,自引:0,他引:6
The ovarian surface epithelium (OSE) represents a minute fraction of the cell mass of the ovary but gives rise to over 80% of human ovarian carcinomas. No experimental models for the study of human OSE exist. To characterize OSE cells in culture, explants of ovarian surface from normal ovary of premenopausal women were grown on plastic, glass, and collagen gel in 25% fetal bovine serum/Waymouth's medium 752/1. About 25% of explants produced epithelial outgrowths. Morphologically, these outgrowths resembled OSE in vivo and endothelial and mesothelial cells in culture, but they differed from cultured ovarian stromal, granulosa, and luteal cells. Only OSE among ovarian cell types were intensely keratin positive by immunofluorescence. Keratin also distinguished OSE cells from the keratin-negative endothelial cells. Most but not all OSE colonies tested showed 17 beta-hydroxysteroid dehydrogenase (HSD) activity, which was absent in peritoneal mesothelial cells. Colonies from most patients were limited to a few millimetres and became stationary within a few weeks. Changes that accompanied cessation of growth included senescence, increased keratin content, or the formation of multicellular papillary aggregates. With time, OSE cells tended to assume a fibroblast-like morphology but remained keratin positive and continued to resemble OSE by scanning electron microscopy (SEM). Subcultured OSE cells persisted in a stationary keratin-positive form for many weeks. Throughout this study, all pavementlike epithelial outgrowths that were contiguous with an explant stained for keratin; thus, such colonies can be assumed to be OSE. Conversely, fibroblast-shaped cells may represent OSE as indicated by keratin content and SEM appearance. The methods presented here permit culture of normal human OSE under conditions in which the cells exhibit morphologic plasticity, variable 17 beta-HSD activity, and presence of keratin. 相似文献
42.
G. Geserick G. Mauff I. Siemens H. Waltz Antonia Mayer K. Bender M. Rose S. Goldmann Martina Brenden Helga Schröder 《Human genetics》1989,81(3):252-256
Summary The segregation of factor B(BF)F subtypes was analyzed in conjunction with other MHC markers in 15 families with 89 offspring. Informative data for BF F subtypes were obtained from 11 families, 6 of them with known recombinant individuals for the HLA-B/DR/GLO region. The subtypes did not contribute further to the localization of the cross-overs, but followed the known segregation of conventional BF allotypes. In 2 families of one kinship, the recognition of heterozygous BF*FAFB individuals could be established following the inclusion of three generations. The rarer of the two BF F subtype alleles, BF*FA, is positively associated with the HLA haplotypes BW62, CW3, C4A*3 and A29, CWX, B44, C4A*3, B*1, DR7. BF F subtypes are regarded as a very useful additional tool for studies of MHC organization and disease association. 相似文献
43.
Jan Siemens Andreas Pacholski Katia Heiduk Anette Giesemann Ulrike Schulte René Dechow Martin Kaupenjohann Hans-Joachim Weigel 《Biogeochemistry》2012,107(1-3):135-148
Terrestrial sources of nitrogen (N), particularly N-fixing alder, may be important for sustaining production in headwater streams that typically lack substantial subsidies of marine-derived nutrients from spawning salmon yet support upstream-dispersing juvenile salmonids. However, other physiographic characteristics, such as watershed slope and topographic wetness, also control transport of nutrients to streams and may confound apparent linkages between alder and stream N. Seasonal patterns in precipitation and temperature may interact with watershed characteristics to modulate stream N availability. We empirically modeled the effect of alder cover and other watershed physiographic variables on stream N and contrasted these relationships over the growing season among 25 first-order streams from the lower Kenai Peninsula, Alaska. For each date, percent alder cover, mean topographic wetness, and mean slope were used as watershed predictors of NO x –N concentration (nitrate?+?nitrite) and daily NO x –N yield using Generalized Additive Models (GAM) and compared using Akaike’s Information Criterion (AICc). Alder cover was the only probable model and explained 75–96% of the variation in NO x –N concentration and 83–89% of the variation in daily NO x –N yield. The relationship between alder and both NO x –N concentration and daily NO x –N yield changed from constant inputs in May across the range of alder cover (linear fit) to increasing inputs in July and September (non-linear fits) implying that high-alder watersheds were N-saturated. The strong linkage between alder and stream N coupled with the concurrent timing of maximum stream N from alder in the spring to salmon fry emergence indicates the potential importance of this subsidy to headwater stream ecosystems. 相似文献
44.
Reini W Bretveld Chris MG Thomas Paul TJ Scheepers Gerhard A Zielhuis Nel Roeleveld 《Reproductive biology and endocrinology : RB&E》2006,4(1):30
Some pesticides may interfere with the female hormonal function, which may lead to negative effects on the reproductive system
through disruption of the hormonal balance necessary for proper functioning. Previous studies primarily focused on interference
with the estrogen and/or androgen receptor, but the hormonal function may be disrupted in many more ways through pesticide
exposure. The aim of this review is to give an overview of the various ways in which pesticides may disrupt the hormonal function
of the female reproductive system and in particular the ovarian cycle. Disruption can occur in all stages of hormonal regulation:
1. hormone synthesis; 2. hormone release and storage; 3. hormone transport and clearance; 4. hormone receptor recognition
and binding; 5. hormone postreceptor activation; 6. the thyroid function; and 7. the central nervous system. These mechanisms
are described for effects of pesticide exposure in vitro and on experimental animals in vivo. For the latter, potential effects of endocrine disrupting pesticides on the female reproductive system, i.e. modulation
of hormone concentrations, ovarian cycle irregularities, and impaired fertility, are also reviewed. In epidemiological studies,
exposure to pesticides has been associated with menstrual cycle disturbances, reduced fertility, prolonged time-to-pregnancy,
spontaneous abortion, stillbirths, and developmental defects, which may or may not be due to disruption of the female hormonal
function. Because pesticides comprise a large number of distinct substances with dissimilar structures and diverse toxicity,
it is most likely that several of the above-mentioned mechanisms are involved in the pathophysiological pathways explaining
the role of pesticide exposure in ovarian cycle disturbances, ultimately leading to fertility problems and other reproductive
effects. In future research, information on the ways in which pesticides may disrupt the hormonal function as described in
this review, can be used to generate specific hypotheses for studies on the effects of pesticides on the ovarian cycle, both
in toxicological and epidemiological settings. 相似文献
45.
R S English J S Lampel TJ Vanden Boom 《Journal of industrial microbiology & biotechnology》1998,21(4-5):219-224
The introduction of plasmid DNA into germinating spores of an industrially improved strain of Saccharopolyspora erythraea was accomplished by electroporation. Various parameters affecting the efficiency of electroporation were examined. The most
critical factor was the extent of spore germination. Electrocompetence was limited to a 4-h period following the initial emergence
of the germ tube. Electroporation efficiencies as high as 2 × 105 CFU μg−1 of plasmid DNA were obtained using electrocompetent germlings. The optimal field strength was 12–14 kV cm−1 with a pulse duration of 15–20 ms. Electrocompetent germlings were stored at −80°C without a significant decrease in transformation
efficiency. The utility of this protocol was demonstrated by isolating a propionyl-CoA carboxylase mutant through targeted
gene disruption and replacement.
Received 3 April 1998/ Accepted in revised form 28 September 1998 相似文献
46.
Ivo R. Siemens Daniel K. Yee Lawrence P. Reagan Stever J. Fluharty 《Journal of neurochemistry》1994,62(1):257-264
Abstract: The murine neuroblastoma N1E-115 cell line possesses type 1 and type 2 angiotensin II (Angll) receptor subtypes. In vitro differentiation of these cells substantially increases the density of the AT2-receptor subtype, whereas the density of the AT1 receptors remains unchanged. In the present study, we report that the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]- 1-propanesulfonate (CHAPS) selectively solubilized AT2receptors from N1E-115 cell membranes and that these receptors could be purified further to near homogeneity by affinity chromatography. More specifically, the presence of an agonist (Angll) during affinity purification of AT2 receptors resulted in the elution of high (110-kDa) and low (66-kDa) molecular mass proteins as determined by gel electrophoresis under nonreducing conditions. In contrast, when the nonselective antagonist Sar1, lle8-Angll was used during purification, only the lower 66-kDa protein was observed. Affinity purification in the presence of the peptide and nonpeptide AT2-receptor antagonists CGP42112A and PD123319 also resulted in elution of the same 66-kDa protein, but unlike that in the presence of Sar1, lle8-Angll, some of the high molecular weight site was observed as well. On the other hand, Losartan, an AT1-receptor antagonist, was completely ineffective in eluting any Angll receptors from the affinity column, further confirming their AT2 identity. After agonist elution, the 110-kDa band dissociated into two low molecular mass bands of 66 kDa and 54 kDa when sodium dodecyl sulfate-gel electrophoresis was run under reducing conditions. The 110-kDa and 66-kDa proteins, but not smaller, affinity-purified proteins, specifically bound 125l-Angll as determined by covalent cross-linking of 125l-Angll to the receptors with the homobifunctional cross-linker disuccinimidyl suberate, or by size exclusion chromatography on a TSK 3000 SW column. Lastly, immunoblot analysis of affinity- purified material with antibodies selective for AT2 receptors revealed major immunoreactive proteins of 110 kDa and 66 kDa in the presence of an agonist, whereas the same 66-kDa protein, as well as a smaller (54-kDa) immunoreactive protein, was detected under reducing conditions. Collectively, these data suggest that CHAPS-solubilized AT2 receptors from N1E-115 cells may consist of a binding protein of approximately 66 kDa, which in the presence of an agonist readily associates with other smaller proteins to form larger multimeric complexes. 相似文献
47.
Johannes Siemens María Torres Marion Morgner María Dolores Sacristán 《Plant cell reports》1993,12(10):569-572
A protocol for obtaining regenerated fertile plants from mesophyll protoplasts of four ecotypes (Col C24, Per-1, Bur-0, Landsberg erecta) and two marker lines (M4 and M10) of Ardbidopsis thaliana is described. The different lines showed plating efficiencies between 1.0 and 3.9% using Nitsch medium or this medium supplemented with coconut water. For the differentiation of callus into normal shoots a single shoot regeneration medium was applicable to all ecotypes, but depending on the line other regeneration media showed to be more suitable. The results indicated that the protoplast culture procedure is applicable, with minor modifications, to all tested genotypes but the most suitable shoot regeneration medium should be established for each A. thaliana line.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- BAP
6-benzyl-aminopurine
- IAA
indole-3-acetic acid
- IPA
isopentenyladenine
- IPAR
isopentenyladenosine
- MES
2-[N Morpholino]ethanesulfonic acid
- MS
Murashige and Skoog
- NAA
naphthaleneacetic acid 相似文献
48.
David H. Siemens 《American journal of botany》1994,81(11):1403-1409
On palo verde trees, nearly 80% of potential offspring were lost during flower bud development. Flower buds at the base of racemes developed earliest and were more likely to survive depredations of gelechiid larvae or abortion from putative limited resources. Herbivory accounted for greater cumulative losses than putative resources; however, an herbivore exclusion experiment suggested that buds damaged by herbivores would have aborted anyway without damage. In a natural experiment, plants that received water runoff had significantly higher densities of racemes, with only slight increases in numbers of buds, flowers, or pods per raceme. Similarly, thinning racemes experimentally to assess limited resources among potentially competing racemes increased the number of viable flower buds per raceme only slightly, with negligible herbivore damage. The production of more racemes rather than more reproductive structures per raceme may be a mechanism to allocate limited resources more efficiently. Alternatively, in studies with animals, similar patterns in the production of broods are thought to be mechanisms to avoid nest predation. Thus, while putative limited resources and resource allocation patterns reduced the proximate effects of larvae, herbivory must be considered as a possible ultimate factor in the patterns observed here because limited resources may be allocated in ways to reduce herbivory. 相似文献
49.
Sequence variations in small-subunit ribosomal RNAs of Hartmannella vermiformis and their phylogenetic implications 总被引:1,自引:0,他引:1
Evidence of associations between free-living amoebas and human disease has
been increasing in recent years. Knowledge about phylogenetic relationships
that may be important for the understanding of pathogenicity in the genera
involved is very limited at present. Consequently, we have begun to study
these relationships and report here on the phylogeny of Hartmannella
vermiformis, a free-living amoeba that can harbor the etiologic agent of
Legionnaires' disease. Our analysis is based on studies of small-subunit
ribosomal RNA genes (srDNA). Nucleotide sequences were determined for
nuclear srDNA from three strains of H. vermiformis isolated from the United
Kingdom, Germany, and the United States. These sequences then were compared
with a sequence previously obtained for a North American isolate by J. H.
Gunderson and M. L. Sogin. The four genes are 1,840 bp long, with an
average GC content of 49.6%. Sequence differences among the strains range
are 0.38%-0.76%. Variation occurs at 19 positions and includes 2
single-base indels plus 14 monotypic and 3 ditypic single-base
substitutions. Variation is limited to eight helix/loop structures
according to a current model for srRNA secondary structure. Parsimony,
distance, and bootstrap analyses used to examine phylogenetic relationships
between the srDNA sequences of H. vermiformis and other eukaryotes
indicated that Hartmannella sequences were most closely related to those of
Acanthamoeba and the alga Cryptomonas. All ditypic sites were consistent
with a separation between European and North American strains of
Hartmannella, but results of other tests of this relationship were
statistically inconclusive.
相似文献
50.
Ouabain-insensitive salt and water movements in duck red cells. I. Kinetics of cation transport under hypertonic conditions 总被引:10,自引:6,他引:4 下载免费PDF全文
Duck red cells in hypertonic media experience rapid osmotic shrinkage followed by gradual reswelling back toward their original volume. This uptake of salt and water is self limiting and demands a specific ionic composition of the external solution. Although ouabain (10(-4)M) alters the pattern of cation accumulation from predominantly potassium to sodium, it does not affect the rate of the reaction, or the total amount of salt or water taken up. To study the response without the complications of active Na-K transport, ouabain was added to most incubations. All water accumulated by the cells can be accounted for by net salt uptake. Specific external cation requirements for reswelling include: sufficient sodium (more than 23 mM), and elevated potassium (more than 7 mM). In the absence of external potassium cells lose potassium without gaining sodium and continue to shrink instead of reswelling. Adding rubidium to the potassium- free solution promotes an even greater loss of cell potassium, yet causes swelling due to a net uptake of sodium and rubidium followed by chloride. The diuretic furosemide (10(-3)M) inhibits net sodium uptake which depends on potassium (or rubidium), as well as inhibits net sodium uptake which depends on sodium. As a result, cell volume is stabilized in the presence of this drug by inhibition of shrinkage, at low, and of swelling at high external potassium. The response has a high apparent energy of activation (15-20 kcal/mol). We propose that net salt and water movements in hypertonic solutions containing ouabain are mediated by direct coupling or cis-interaction, between sodium and potassium so that the uphill movement of one is driven by the downhill movement of the other in the same direction. 相似文献