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31.
32.
Stepwise assembly of functional C‐terminal REST/NRSF transcriptional repressor complexes as a drug target 下载免费PDF全文
33.
Kowalczyk AE Kaczmarek MM Schams D Ziecik AJ 《Molecular reproduction and development》2008,75(10):1558-1566
The purpose of the present study was to investigate the effects of prostaglandin (PG) E(2) and tumor necrosis factor (TNF) alpha on expression of vascular endothelial growth factor (VEGF) and its receptors, fms-like tyrosine kinase (Flt-1) and fetal liver kinase-1/kinase insert domain-containing receptor (Flk-1/KDR), in cultured porcine luteal cells. Real-time PCR was used for quantification of VEGF and its receptors mRNA, whereas VEGF release by luteal cells was determined by radioimmunoassay (RIA). Only the highest dose of PGE(2) (1 microM) after 6 hr of incubation stimulated VEGF release by luteal cells collected in the mid-luteal phase (P < 0.05). Moreover, PGE(2) (100 nM, 1 microM) significantly stimulated VEGF secretion by luteal cells in the late phase and during pregnancy on Days 10-12 (P < 0.05). Elevated mRNA expression of both VEGF 120 and VEGF 164 isoforms was found in luteal cells cultured with PGE(2). The lack of an effect of PGE(2) on VEGF receptors mRNA expression was observed. TNFalpha was able to significantly stimulate VEGF release from cells obtained in the mid- and late luteal phase or during early pregnancy. All tested doses enhanced mRNA levels of VEGF 120 isoform, but not VEGF 164. Additionally, TNFalpha was able to decrease Flk-1/KDR mRNA expression, whereas Flt-1 mRNA levels were not affected. These results indicated that PGE(2) and TNFalpha influenced VEGF ligand-receptor system expression in porcine luteal cells and may therefore play an important role in regulation of luteal functions during the estrous cycle and pregnancy in pigs. 相似文献
34.
Albrecht E Kolisek M Viergutz T Zitnan R Schweigel M 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2008,178(3):285-295
In this study, we have studied the expression, localization, and functionality of vacuolar-type H+-ATPase (vH+-ATPase) and Na+/K+-ATPase in the bovine rumen epithelium. Compared with the intracellular pH (pHi) of control rumen epithelial cells (REC; 7.06 ± 0.07), application of inhibitors selective for vH+-ATPase (foliomycin) and Na+/K+-ATPase (ouabain) reduced pHi by 0.10 ± 0.03 and 0.18 ± 0.03 pH-units, respectively, thereby verifying the existence of both functional proteins. Results
from qRT-PCR and immunoblotting clearly confirm the expression of vH+-ATPase B subunit in REC. However, the amount of Na+/K+-ATPase mRNA and protein is tenfold and 11-fold of those of vH+-ATPase subunit B, respectively, reflecting a lower overall abundance of the latter in REC. Na+/K+-ATPase immunostaining has revealed the protein in the plasma membrane of all REC from the stratum basale to stratum granulosum,
with the highest abundance in basal cells. In contrast, the vH+-ATPase B subunit has been detected in groups of cells only, mainly localized in the stratum spinosum and stratum granulosum
of the epithelium. Furthermore, vH+-ATPase has been detected in the cell membrane and in intracellular pools. Thus, functional vacuolar-type H+ pumps are expressed in REC and probably play a role in the adaptation of epithelial transport processes. 相似文献
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In the cultures of the alga Chlamydomonas reinhardtii, division rhythms of any length from 12 to 75 h were found at a range of different growth rates that were set by the intensity
of light as the sole source of energy. The responses to light intensity differed in terms of altered duration of the phase
from the beginning of the cell cycle to the commitment to divide, and of the phase after commitment to cell division. The
duration of the pre-commitment phase was determined by the time required to attain critical cell size and sufficient energy
reserves (starch), and thus was inversely proportional to growth rate. If growth was stopped by interposing a period of darkness,
the pre-commitment phase was prolonged corresponding to the duration of the dark interval. The duration of the post-commitment
phase, during which the processes leading to cell division occurred, was constant and independent of growth rate (light intensity)
in the cells of the same division number, or prolonged with increasing division number. It appeared that different regulatory
mechanisms operated through these two phases, both of which were inconsistent with gating of cell division at any constant
time interval. No evidence was found to support any hypothetical timer, suggested to be triggered at the time of daughter
cell release. 相似文献
38.
Reetz J Wiedemann M Aue A Wittstatt U Ochs A Thomschke A Manke H Schwebs M Rinder H 《Parasitology international》2004,53(1):29-34
For the first time, Encephalitozoon (E.) cuniculi genotype III ('dog strain') was verified in two cotton-top tamarins (Oedipomidas oedipus) by light microscopy, immunohistochemistry, electron microscopy, PCR and sequencing. The animals had a disseminated lethal infection with this protist. In earlier reports, genotype III had been found only in domestic dogs, man, emperor tamarins (Saguinus imperator) and golden lion tamarins (Leontopithecus rosalia). This investigation establishes now that the 'dog strain' can occur in cotton-top tamarins too. This is further evidence for the zoonotic potential of E. cuniculi. Furthermore, free E. cuniculi spores were identified also in blood vessels of several tissues. These findings indicate that during a disseminated infection E. cuniculi spores can occur in peripheral blood, too. We propose that blood should also be included in the investigations for the detection of microsporidia, so that a possible disseminated course of an infection can be detected. 相似文献
39.
Andrea Polle Lars O. Baumbusch Christa Oschinski Monika Eiblmeier Vivian Kuhlenkamp Birgit Vollrath Florian Scholz Heinz Rennenberg 《Oecologia》1999,121(2):149-156
Clones of Norway spruce (Picea abies L.) were grown for several years on an altitudinal gradient (1750 m, 1150 m and 800 m above sea level) to study the effects
of environmental × genetic interactions on growth and foliar metabolites (protein, pigments, antioxidants). Clones at the
tree line showed 4.3-fold lower growth rates and contained 60% less chlorophyll (per gram of dry matter) than those at valley
level. The extent of growth reduction was clone-dependent. The mortality of the clones was low and not altitude-dependent.
At valley level, but not at high altitude, needles of mature spruce trees showed lower pigment and protein concentrations
than clones. In general, antioxidative systems in needles of the mature trees and young clones did not increase with increasing
altitude. Needles of all trees at high altitude showed higher concentrations of dehydroascorbate than at lower altitudes,
indicating higher oxidative stress. In one clone, previously identified as sensitive to acute ozone doses, this increase was
significantly higher and the growth reduction was stronger than in the other genotypes. This clone also displayed a significant
reduction in glutathione reductase activity at high altitude. These results suggest that induction of antioxidative systems
is apparently not a general prerequisite to cope with altitude in clones whose mother plants originated from higher altitudes
(about 650–1100 m above sea level, Hercycnic-Carpathian distribution area), but that the genetic constitution for maintenance
of high antioxidative protection is important for stress compensation at the tree line.
Received: 13 October 1998 / Accepted: 22 June 1999 相似文献
40.
Summary Growth of hydroponically cultivated birch seedlings (Betula pendula Roth.) at sub- and supra-optimum potassium supply rates was investigated. Potassium was supplied either as a relative addition rate (r
k = 5, 10, 15 and 20% increase day-1) or as fixed concentrations (0.2, 3, 6, 12 and 15 mM) in the culture solution. After an acclimation period the growth rate of the seedlings in the suboptimum treatments reached values close to the treatment variable, the relative rate of K-addition. Deficiency symptoms, in the form of chlorosis and necroses along the leaf margins, developed initially in all suboptimum treatments, but very few new symptoms appeared once the seedlings had reached the phase of steady-state nutrition and growth. At supra-optimum K-supply levels, i.e. at 0.2–15 mM K in the culture solution, no symptoms of deficiency or toxicity developed, and the relative growth rate of the seedlings remained maximum. The relative growth rate of the seedlings was linearly related to the plant K-status for K contents ranging from 0.2 to 1.0% of dry weight (DW). At higher internal K-concentrations, 1.0–3.0% DW, no further increase in relative growth rate was achieved. A shortage of K resulted in a decrease in the net assimilation rate. This effect was counterbalanced by the absence of shift in he leaf weight ratio as well as by the production of relatively thin leaves. The fraction of dry matter allocated to roots decreased in K-limited plants, as did the leaf contents of soluble carbohydrates and starch. 相似文献