共查询到20条相似文献,搜索用时 15 毫秒
1.
Recombinant human Factor IX (rFIX) was cloned in a mammalian expression vector and transfected into CHO and HEK-293. Treatment
with 10−9 M methyl testosterone increased rFIX production by 30–50% in CHO and HEK clones. However, 10−9 M 17β-oestradiol increased production of rFIX by ~50% in CHO-F7 clone and decreased production by 48% and 37% in CHO-F8 and
HEK-F2-6, respectively. Progesterone treatment inhibited rFIX production in both cell lines. Production of rFIX can thus be
increased by sex hormone treatment and therefore used to enhance biotechnological production in mammalian cells. 相似文献
2.
Summary The MTW9/PL cell line was established by our laboratory in culture from the carcinogen-induced hormone-responsive MT-W9A rat
mammary tumor of a Wistar-Furth (W/Fu) rat. This tumor formed estrogen, androgen, and progesterone responsive tumors in W/Fu
rats (Sirbasku, D. A., Cancer Res. 38:1154–1165; 1978). It was later used to derive the MTW9/PL2 cell population which was
also estrogen-responsive in vivo (Danielpour, D., et al., In Vitro Cell. Dev. Biol. 24∶42–52; 1988). In the study presented
here, we describe serum-supplemented culture conditions in which the MTW9/PL2 cells demonstrate≥80-fold steroid hormone growth
responses. All sera used were steroid hormone-depleted by charcoal-dextran treatment at 34°C. The studies were done with horse
serum as well as serum from other mammalian species. The growth of the MTW9/PL2 cells was biphasic in response to hormone-depleted
serum. Concentrations of ≤5% (v/v) promoted optimum growth. Above this concentration, serum was inhibitory. Concentrations
≥40% (v/v) inhibited growth altogether. Addition of 1.0×10−13−1.0×10−8
M 17β-estradiol (E2) reversed the inhibition completely. At 1.0×10−8
M, estrone, estriol and diethylstilbestrol promoted growth as well as E2. Testosterone and dihydrotestosterone promoted growth only at ≥10−7
M. Progesterone was effective only at≥10−6
M. Cortisol was ineffective. Labeled-hormone-binding analysis and Western immunoblotting documented that MTW9/PL2 cells had
estrogen and progesterone receptors but not androgen or cortisol receptors. Estrogen treatment of MTW9/PL2 cells induced a
concentration and time dependent increase in progesterone receptors. We conclude (1) the MTW9/PL2 population is the first
highly steroid hormone-responsive rat mammary tumor cell line to be established in culture from a carcinogen-induced tumor,
and (2) sera from a number of species including horse, rat and human contain an inhibitor which mediates estrogen sensitive
MTW9/PL2 cell growth in culture. 相似文献
3.
In the present study, it was aimed to investigate the influence of exogenous mammalian sex hormones (MSH) (progesterone, β-estradiol
and androsterone) on the morphological (root and shoot growth) and biochemical parameters (protein and sugar content, antioxidant
enzyme activities, and lipid peroxidation and H2O2 levels) of chickpea (Cicer arietinum L.) plants growing under control conditions. The solutions of hormones prepared at different concentrations (10−4, 10−6, 10−9, 10−12 and 10−15 M) were sprayed once on the leaves of 7-day plants. The plants were harvested on 18 days after the hormone treatment. Although
all of the hormones at the tested concentrations significantly increased plant growth, soluble protein and sugar contents,
and antioxidant enzyme activities [superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT)], they decreased H2O2 content and lipid peroxidation level when compared with control plants. The activities of SOD, POX and CAT reached to the
highest levels at 10−6 M for progesterone, and 10−9 M for β-estradiol and androsterone, which maximum growth, protein and sugar contents were determined. The same concentrations
also resulted in the lowest levels for H2O2 content and lipid peroxidation. It can be interpreted that the MSH improve plant growth and development by affecting some
biochemical parameters including antioxidative system. 相似文献
4.
Camila Infantosi Vannucchi Marcelo Faustino Mariana Groke Marques Marcílio Nichi Mayra Elena Ortiz D’Ávila Assumpção José Antonio Visintin 《In vitro cellular & developmental biology. Animal》2009,45(7):328-333
During the process of maturation in the oviduct, canine oocytes in the germinal vesicle stage are exposed to decreasing levels
of estradiol-17β and increasing levels of progesterone. However, hormone concentrations in the microenvironments in which
they act are higher than serum concentrations. Therefore, the aim of the present study was to compare the meiotic competence
of canine oocytes harvested from anestrous bitches in culture medium containing high concentrations (20 μg ml−1) of estradiol-17β and/or progesterone in association to gonadotropins (luteinizing hormone and follicle-stimulating hormone)
using three different maturation periods (48, 72, and 96 h). Oocytes were cultured in tissue culture medium (TCM-199) and
arranged in four experimental groups: group control, group E2 (estradiol-17β), group P4 (progesterone), and group E2 + P4.
Regardless of the maturation period, groups P4 and E2 + P4 presented statistically higher rate of germinal vesicle breakdown
oocytes compared to the group control and group E2. There were no significant differences among groups on germinal vesicle,
metaphase I, metaphase II, and degenerated or unidentifiable oocytes rates. The mean percentage of metaphase II oocytes was
higher at 96 h when compared to 72 h. Results of the present research indicate no influence of estradiol-17β supplementation,
unless in association with progesterone. There is an evidence of the positive effect of progesterone on germinal vesicle breakdown.
Results also showed that extended periods of in vitro maturation affect positively maturation rates to metaphase II of low
competent oocytes harvested from anestrous bitches, independent of the maturation media. In conclusion, high concentrations
of steroids, especially progesterone, have positive effect on in vitro oocyte maturation when the oocytes are derived from
the anestrous status. 相似文献
5.
Esfahani A Kendall CW Bashyam B Archer MC Jenkins DJ 《In vitro cellular & developmental biology. Animal》2010,46(10):856-862
The majority of cell culture studies have assessed the effect of hormones on cancer cell growth using media supplemented with
charcoal-treated fetal bovine serum (CTS). We aimed to determine whether using a system more reflective of the human condition
by changing the charcoal-treated serum to an untreated pooled human serum (PHS) resulted in the same hormone responses in
breast and prostate cell lines. MCF-7 breast cancer, MCF-10A non-transformed breast, and LNCaP prostate cancer cell lines
supplemented with PHS were treated with high and low physiological concentrations of six hormones (17β-estradiol, dehydroepiandosterone
(DHEA), dihydrotestosterone (DHT), testosterone, insulin, and glucagon). Cell growth was measured after 72 h of incubation.
All hormones stimulated growth of MCF-7 cells (p < 0.05). MCF-10A cell growth was inhibited by DHEA, DHT, and testosterone (p < 0.05), unaffected by 17β-estradiol and glucagon, and stimulated by insulin (p < 0.05). LNCaP cell growth was stimulated by the highest concentration of DHEA and DHT (p < 0.05) and inhibited by the highest concentration of 17β-estradiol (p < 0.05), while insulin and testosterone, had no effect. Overall, PHS lowered the magnitude of the effect of hormones on cell
growth in comparison to CTS. Due to the presence of all serum constituents, our model represents a more appropriate physiological
environment for determining the effect of hormones on cancer cell growth. Further studies are required to determine the mechanisms
by which added hormones interact with the constituents of untreated human serum. 相似文献
6.
M. Klokker N. H. Secher P. Madsen H. L. Olesen S. Matzen U. Knigge J. Warberg B. K. Pedersen 《European journal of applied physiology and occupational physiology》1997,76(5):415-420
To evaluate a possible role for β-endorphin in the stress-induced modulation of natural killer (NK) cells, immunologically
competent blood cells were followed in eight male volunteers administered either Naloxone or saline (control) during head-up
tilt maintained until the appearance of presyncopal symptoms (PS). The PS appeared more rapidly with Naloxone compared to
control [5.7 (SEM 1.1) vs 22.3 (SEM 5.1) min; P = 0.01]. The NK cell activity increased threefold during PS partly due to an increase in CD16+ and CD56+ NK cells in blood. In support, NK cell activity boosted with interferon-α and interleukin 2 rose in parallel with unboosted
NK cell activity and NK cell concentration and activities returned to the baseline level after 105 min. The total lymphocyte
count and the concentrations of CD3+, CD4+, CD8+, CD16+, and CD56+ cells increased during PS. Head-up tilt also induced an increase in plasma adrenaline concentration during control PS and
a rise in plasma cortisol and adrenocorticotropic hormone concentrations up to 30 min thereafter, whereas no significant changes
were found in plasma concentrations of noradrenaline, growth hormone, or β-endorphin. The results would indicate an influence
of endorphin on the increase in plasma adrenaline concentration during head-up tilt and at the same time contra-indicate a
significant role for adrenaline in the provocation of PS. The influence of head-up tilt on plasma β-endorphin was too small
to influence the modulation of the cellular immune system.
Accepted: 22 May 1997 相似文献
7.
Experimental test of the effect of maternal hormones on larval quality of a coral reef fish 总被引:1,自引:0,他引:1
M. I. McCormick 《Oecologia》1999,118(4):412-422
Maternal hormones can play an important role in the development of fish larvae. Levels of the stress hormone, cortisol, in
females are elevated by social interactions and transferred directly to the yolk of eggs, where they may influence developmental
rates. In some vertebrates, prenatal exposure to high levels of testosterone determine early growth rates, social status and
reproductive success. The present study examined whether post-fertilization exposure of eggs of the tropical damselfish, Pomacentrus amboinensis (Pomacentridae), to natural levels of cortisol or testosterone directly affects larval morphology at hatching. Maternal and
egg levels of cortisol and testosterone varied widely among clutches of eggs from local populations around Lizard Island on
the Great Barrier Reef. The morphology of larvae produced by these local fish populations also varied widely and differed
significantly among sites (e.g., standard length: 2.6–3.4 mm; yolk sac area: 0.01–0.13 × 10−2 mm2). Laboratory experiments showed that elevated cortisol levels in the egg reduced larval length at hatching, while slight
elevations in testosterone increased yolk sac size. The influence of testosterone, and to a smaller extent cortisol, on larval
morphology differed among egg clutches. These differences were partly explained by differences in initial egg hormone levels.
Morphological changes induced by experimental hormonal regimes encompassed the entire range of variability in body attributes
found in field populations. It is unclear whether cortisol influences growth alone or development rate or both. Testosterone
appears to influence yolk utilization rates, and has no significant effect on growth, in contrast to its role in later developmental
stages. Maternally derived cortisol and testosterone are important in regulating growth, development, and nutritive reserves
of the embryo and larvae of this fish species. Factors that influence the maternal levels of cortisol and testosterone may
have a major impact on larval mortality schedules and, therefore, on which breeding individuals contribute to the next generation.
Received: 19 August 1998 / Accepted: 16 November 1998 相似文献
8.
Summary In an accompanying report (Moreno-Cuevas, J. E.; Sirbasku, D. A., In Vitro Cell. Dev. Biol.; 2000), we demonstrated 80-fold
estrogen mitogenic effects with MTW9/PL2 rat mammary tumor cells in cultures supplemented with charcoaldextran-treated serum.
All sera tested contained an estrogen reversible inhibitor(s). The purpose of this report is to extend those observations
to additional sex steroid-responsive human and rodent cell lines. Every line tested showed a biphasic response to hormone-depleted
serum. Concentrations of ≤10% (v/v) promoted substantive growth. At higher concentrations, serum was progressively inhibitory.
With estrogen receptor-positive (ER+) human breast cancer cells, rat pituitary tumor cells, and Syrian hamster kidney tumor cells, 50% (v/v) serum caused significant
inhibition, which was reversed by very low physiologic concentrations of estrogens. This same pattern was observed with the
steroid hormone-responsive LNCaP human prostatic carcinoma cells. Because steroid hormone mitogenic effects are now easily
demonstrable using our new methods, the identification of positive results has nullified our original endocrine estromedin
hypothesis. We also evaluated autocrine/paracrine growth factor models of estrogen-responsive growth. We asked if insulin-like
growth factors I and II, insulin, transforming growth factor alpha, or epidermal growth factor substituted for the positive
effects of estrogens. Growth factors did not reverse the serum-caused inhibition. We asked also if transforming growth factor
beta (TGFβ) substituted for the serum-borne inhibitor. TGFβ did not substitute. Altogether, our results are most consistent
with the concept of a unique serum-borne inhibitor as has been proposed in the estrocolyone model. However, the aspect of
the estrocolyone model related to steroid hormone mechanism of action requires more evaluation. The effects of sex steroids
at picomolar concentrations may reflect mediation via inhibitor “activated” intracellular signaling pathways. 相似文献
9.
Klaus Wirthensohn Christian A. Barth 《In vitro cellular & developmental biology. Plant》1985,21(10):546-552
Summary The survival of adult rat hepatocytes in monolayer culture was studied in the presence of different hormones (neurotensin,
oxytocin, thyrotropin releasing hormone, luteinizing hormone releasing hormone, cholecalciferol, bradykinin, substance P,
aldosterone, melanocyte stimulating hormone, 3,3′,5-triiodo-1-thyronine, corticosterone, human growth hormone, glucagon, insulin,
progesterone, testosterone, estradiol, and dexamethasone phosphate) or growth factors (fetal bovine serum). For this purpose
trypan blue exclusion, lactate dehydrogenase, and DNA and protein content were measured at 24 and 72 h of culture. 10−7
M Dexamethasone, a mixture of eight hormones, 10% fetal bovine serum, and a combination of the latter two supplements caused
a more than 64% higher DNA content at 72 h when compared to control cultures. A striking agreement of these results with changes
of lactate dehydrogenase leakage was observed, whereas trypan blue exclusion gave erratic results. Considerable changes of
cell arrangement apparently specific for each supplement were ovserved by low magnification microscopy. It is concluded that
glucocorticoids and fetal bovine serum have an outstanding effect on cell viability and that DNA or protein content or both
are reliable indicators of cell viability in amitotic cultures. 相似文献
10.
Dumlupinar R Genisel M Erdal S Korkut T Taspinar MS Taskin M 《Biological trace element research》2011,143(3):1740-1745
The present study was performed to determine the changes in inorganic element content in barley leaves of mammalian sex hormones
(MSH). Barley leaves were sprayed with 10−4, 10−6, 10−9, 10−12, 10−15 M concentrations of progesterone, β-estradiol, and androsterone at 7th day after sowing. The plants were harvested at the
end of 18 days after treatment with MSH solutions. The inorganic element concentrations were determined using wavelength dispersive
X-ray fluorescence spectroscopy technique. Although the all MSH concentrations significantly (p < 0.05) increased the concentrations of calcium, magnesium, phosphorus, sulfur, copper, manganese, aluminum, zinc, iron,
potassium, and chlorine, it decreased those of sodium concentration in barley leaves. The maximum changes in the element concentrations
were obtained at 10−9 M for plant leaves treated with progesterone, 10−6 M for plant leaves treated with β-estradiol and androsterone. The present study elucidated that MSH significantly (p < 0.05) affected the inorganic element concentrations in barley leaves. 相似文献
11.
Summary Cultured cells from the bovine endosalpinx were used to evaluate effects of estradiol-17β, progesterone, epidermal growth
factor, and insulinlike growth factors I and II on [3H]thymidine incorporation. Cells were treated with hormones and growth factors when approximately 50% confluent. After 24
h, DNA synthesis was quantified by pulsing cells with [3H]thymidine for 12 h and determining uptake into DNA. Cells prepared by mechanical dispersal incorporated more [3H]thymidine than cells dispersed with collagenase. However, hormonal responses were the same for both types of cells. As compared
to plastic, cells on a Matrigel substratum exhibited lower incorporation of [3H]thymidine and were unresponsive to hormones. Estradiol-17β increased [3H]thymidine incorporation slightly at 10−10 mol/liter and higher. Epidermal growth factor, insulinlike growth factor-I, and insulinlike growth factor-II also stimulated
[3H]thymidine incorporation. Effects of insulinlike growth factor-I were greater for cells treated with estradiol-17β. In the
absence of estradiol, progesterone inhibited [3H]thymidine incorporation at 1, 10, and 100 ng/ml. When estradiol-17β was present, progesterone stimulated [3H]thymidine incorporation at 1 ng/ml and reduced incorporation at 100 ng/ml. In conclusion, [3H]thymidine incorporation by cultured oviductal endosalpingeal cells can be regulated by ovarian steroids and growth factors.
These molecules may represent signals through which the ovary, embryo, and oviduct regulate oviductal growth.
Work conducted while on a sabbatical leave supported by the Deutsche Forschungsgemeinschaft. 相似文献
12.
A group of 138 B cell chronic lymphocytic leukaemia (B-CLL) patients, 83 with active disease and 53 having the indolent form
of the disease, were evaluated. The aim of the study was to clarify whether indolent and active B-CLL differ in their immune
and hormonal characteristics. Peripheral blood lymphocyte proliferation in response to phytohaemagglutinin, concanavalin A,
recombinant interleukin-2, dextran sulphate, Pisum sativatum agglutinin and wheat germ agglutinin was investigated. Serum immunoglobulin and β2 microglobulin levels were determined. Adrenocorticotropic hormone (ACTH), cortisol, follicle-stimulating hormone luteinizing
hormone, 17β-oestradiol, testosterone, triiodothyronine, thyroxine, thyroglobulin and thyrotropic hormone levels were determined
by radioimmunoassay. Active and indolent CLL presented differences in immunological characteristics, as demonstrated by the
more severe suppression of T lymphocyte function, reduced IgA level and considerably higher serum β2-microglobulin values
in active disease. Immune disturbances were accompanied by hormonal imbalance, depending on disease status: lower ACTH, cortisol
and triiodothyronine levels were established to occur in active CLL compared to indolent disease. Male patients demonstrated
striking changes in sex hormones, which were more evident in active disease. The findings point to the complexity of immuno-hormonal
disturbances in CLL with differences in the active and indolent state of the disease.
Received: 19 June 1997 / Accepted: 14 August 1997 相似文献
13.
The present study was undertaken to reveal the changes in inorganic constituents of plants exposed to mammalian sex hormones
(MSH). Chickpea leaves were sprayed with 10−4, 10−6, 10−9, 10−12, and 10−15 M concentrations of progesterone, β-estradiol, and androsterone at 7th day after sowing. The plants were harvested at the
end of 18 days after treatment of MSH solutions and the inorganic components determined using a wavelength-dispersive X-ray
fluorescence spectroscopy technique. At all of the concentrations tested, MSH significantly increased the contents of K, S,
Na, Ca, Mg, Zn, Fe, P, Cu, and Ni. Interestingly, only Mn and Cl contents decreased. The maximum changes in the inorganic
composition were recorded at 10−6 M for plants treated with progesterone and 10−9 M for plants treated with β-estradiol and androsterone. 相似文献
14.
Studies were conducted to characterize the effect of gene amplification and foreign gene expression on recombinant CHO cell
growth. Chinese hamster ovary (CHO) cells were transfected with an expression vector containing the gene for dihydrofolate
reductase (dhfr) and the gene for human β-interferon (β-IFN) or thelac Z gene which codes for β-galactosidase (β-gal). The recombinant genes in these CHO cells were amplified stepwise by growth
in 0, 10−7, and 10−6 M methotrexate (MTX), and the β-gal expressing cells were adapted to suspension culture. Flow cytometric methods (FCM) were
used to measure the distribution of amplifieddhfr gene content and foreign β-gal gene expression in the cell populations. A biochemical assay for β-gal was also used. Beta-gal
expression was found to increase with increasing gene amplification. The growth rate of recombinant CHO cells at 10−7 M MTX was found to be 20% lower than that of recombinant CHO cells in MTX-free medium, and the cell growth rate at 10−6 M MTX was 20% lower than that of recombinant CHO cells at 10−7 M MTX. There was no effect of 10−5 M MTX on the growth of CHO-DG44 (dhfr-) cells. The reduction of growth rate in recombinant CHO cells is therefore thought to be mainly due to the effect ofdhfr and foreign gene amplification and increased β-galactosidase expression. 相似文献
15.
Jung-Shi Wang Shu-Man Chen Shu-Ping Lee Shin-Da Lee Chih-Yang Huang City C. Hsieh Chia-Hua Kuo 《Steroids》2009,74(12):945-949
The steroid dehydroepiandrosterone sulfate (DHEA-S) is associated with longevity and adaptation against external stress in humans. The aim of the study was to investigate the acute effect of a 30-min hot spring immersion at 41 °C on insulin resistance measures of 16 male subjects, in relation to DHEA-S level. To elucidate the role of DHEA-S in the coping against the heat stress, all subjects were evenly divided into lower and upper halves according to their baseline DHEA-S concentrations. The levels of glucose, insulin, blood pressure, and stress hormones (growth hormone, testosterone, and cortisol) in both groups were compared before and after hot spring immersion. The result shows that hot spring immersion significantly increased heart rate and reduced diastolic blood pressure, both of which were paralleled with a drop of DHEA-S concentration. Homeostasis model assessment for insulin resistance (HOMA-IR) and area under curve of glucose (GAUC) of oral glucose tolerance test were significantly increased by the hot spring immersion only in the Low DHEA-S group. Likewise, hot spring immersion caused an opposing effect on cortisol changes for the Low and High DHEA-S groups (+95% vs. −33%, p < 0.05), respectively. In conclusion, hot spring bathing induced insulin resistance confined only to those Low DHEA-S individuals. This response may be associated with a stress response such as increased cortisol levels. 相似文献
16.
The influence of selected animal steroid sex hormones, on generative development of winter wheat var. Grana was investigated. Wheat plants of this variety necessitate 63-day long vernalization.
Mature, isolated embryos of wheat were cultured in vitro on media containing androsterone, androstenedione, estriol, estrone, 17β-estradiol and progesterone in concentrations 10−5 and 10−6 M. They were not vernalized or vernalized for 7, 14, 21 and 28 days (5 °C, 8 h photoperiod).
Investigated steroids stimulated the generative development of winter wheat by an increasing in the percentage of heading
plants and accelerating the heading. The strongest effect was observed when plants were treated with steroids during the suboptimal,
21 and 28 day, vernalization. After 28 days of vernalization, 100 % heading were observed in plants obtained on the media
containing androsterone and androstenedione in concentrations 10−5 and 10−6 M or estrone, 17β-estradiol and progesterone in concentration 10−5 M. Control plants showed only 8 % heading.
An erratum to this article is available at . 相似文献
17.
Paula Klevjer-Anderson Gertrude Case Buehring 《In vitro cellular & developmental biology. Plant》1980,16(6):491-501
Summary The individual effects of seven hormones on the in vitro growth rate of different classifications of human mammary epithelium
were compared. Hormones used were: 17β-estradiol, estriol, progesterone, hydrocortisone, testosterone, prolactin, and growth
hormone. Cell cultures included three established breast cell lines and primary monolayer cultures established form breast
fluids and excised mammary tissue from 40 women and 4 men. Specimens comprised three classifications: normal, nonmalignant
atypical, and malignant. Growth was quantitated in situ and expressed as population doubling time. Principal findings were:
(a) estrogens, prolactin, and growth hormone stimulated growth of normal cells more frequently than growth of malignant cells,
whereas testosterone and hydrocortisone stimulated growth of malignant cells more frequently than growth of normal cells;
(b) cells cultured from nonmalignant atypias generally showed hormone response profiles intermediate between those of normal
and malignant cells; (c) progesterone stimulated the growth of cells from malignant specimens but not the growth of cells
from normal and nonmalignant atypical samples.
This research was supported by NIAID Research Training Grant 5-TO1-A1-00332-06. 相似文献
18.
One-year-old apple cuttings (Malus pumila var.domestica cv. M26) were grown for 6 months in pot culture with and without inoculum of the VA-mycorrhizal fungus (VAMF)Glomus macrocarpum in soil from a long-term fertilizer field experiment with different P availability (20, 210, and 280 mg CAL-extractable P
kg−1). The indigenous VAMF propagule density was reduced by 0.5 Mrad X-irradiation. At harvest, non-inoculated and inoculated
plants had similar proportions of root length bearing vesicles. Net dry weight of tree cuttings was significantly increased
by inoculation only at 20 mg P kg−1 (+62%). Increasing P availability from 210 to 280 mg P kg−1 led to a 4-week depression of shoot elongation rate only in the inoculated plants. Uptake of P was significantly enhanced
by inoculation at 20 and 210 mg P kg−1 (+64 and +12%, respectively). On average, inoculated plants had significantly higher concentrations of Zn in leaves and in
roots (+16 and +14%, respectively) and of copper in stems and in roots (+13 and +126%, respectively). Proportion of vesicle
bearing root length was significantly correlated with root caloric content. A lipid content of 0.9–4.5% in the root dry matter
was attributed to the presence of vesicles corresponding to 1.6–8.2% of total root caloric content.
As the control plants were also infected, the beneficial effect of VA-mycorrhiza on nutrient uptake and growth of apple cuttings
was underestimated at all P levels. Furthermore, VAM-potential at the lowest P level was not fully exploited as onset of infection
was most certainly delayed because of a decreased photosynthetic rate due to P deficiency. Energy drain by VAMF-infection
was most probably underestimated considerably, due to, among others, loss of infected root cortex during root growth, sampling
and staining.
It is concluded that apple cuttings rely on VA-mycorrhizal P-uptake at least in low P soils. In high P soils, apple cuttings
may profit predominantly from the uptake of Zn and Cu by the fungal symbionts. 相似文献
19.
Koji Ishida Tatsuya Hayashi Toshio Moritani Miharu Miyamura 《European journal of applied physiology and occupational physiology》1997,76(3):230-235
To elucidate whether combined adrenergic and parasympathetic blockade would affect the ventilatory response to exercise,
especially at the initial stage (phase I), six healthy subjects performed a brief and light voluntary bilateral leg extension
exercise and passive movements under the conditions of control (before the blockade) and after intravenous administration
of combined β-adrenergic (propranolol, 0.2 mg · kg−1) and muscarinic (atropine, 0.04 mg · kg−1) receptor antagonists. The movements were continued only within two breaths after the onset of the motion. Ventilation increased
immediately and significantly (P<0.05) within the first breath at the onset of voluntary exercise in all conditions as compared with at rest. However, the
magnitude of increase in mean ventilation within two breaths at the start of exercise as against the resting value (delta
ventilation) was significantly less (P<0.05) after the combined blockades (2.5 l · min−1) than in the control condition (3.7 l · min−1). Passive movements showed a similar but smaller change as compared with voluntary exercise. The heart rate response to exercise
was attenuated by the combined blockade while cardiac output showed a slight change at the onset of exercise. It is concluded
that phase I should occur despite the inhibited activity of the β-adrenergic and the cholinergic systems; nevertheless, the
response was attenuated by the combined blockade. These results suggest a possible role of the β-adrenergic and/or cholinergic
systems in the rapid increase in ventilation that occurs at the start of exercise.
Accepted: 2 March 1997 相似文献
20.
Five isolates belonging to three species of the genusHumicola were tested in this study for their ability to transform progesterone. An oxidative splitting of the side chain of progesterone
with the formation of androst-4-ene-3,17-dione, testosterone and testololactone was achieved by all isolates tested ofH. fuscoatra andH. grisea. H. hyalothermophila transformed progesterone to 11α-, 11β-, 17α- and 21-hydroxyprogesterone and a dihydroxyl product (11α, 17α-dihydroxyprogesterone)
with the addition of two trihydroxyl products,viz. cortisol and epicortisol. Qualitative and quantitative analysis of the different products obtained when a selective isolate
of each species acted on progesterone were conducted. The chromatographic resolution of the mixture products obtained when
the selective isolate of each ofH. fuscoatra andH. grisea had acted individually on 1 g progesterone revealed the presence of 25 and 20% unchanged progesterone, 20 and 22% androst-4-ene-3,17-dione,
25 and 23% testosterone and 30 and 35% testololactone, respectively. Seventy-four % of progesterone were bioconverted byH. hyalothermophila into 21-hydroxyprogesterone (6%), 17α-hydroxyprogesterone (5%), 11α-hydroxyprogesterone (11%), 11β-hydroxyprogesterone (12%),
11α,17α-dihydroxyprogesterone (5%), cortisol (21%) and epicortisol (13%). This is the first record of conversion of progesterone
to both cortisol and epicortisol byH. hyalothermophila. 相似文献