排序方式: 共有41条查询结果,搜索用时 15 毫秒
1.
A Emami-Khoyi DA Hartley RH Cruickshank LJ Boren JG Ross 《New Zealand journal of zoology.》2016,43(4):322-335
New Zealand fur seals are one of many pinniped species that survived the commercial sealing of the eighteenth and nineteenth centuries in dangerously low numbers. After the enforcement of a series of protection measures in the early twentieth century, New Zealand fur seals began to recover from the brink of extinction. We examined the New Zealand fur seal populations of Banks Peninsula, South Island, New Zealand using the mitochondrial DNA control region. We identified a panmictic population structure around Banks Peninsula. The most abundant haplotype in the area showed a slight significant aggregated structure. The Horseshoe Bay colony showed the least number of shared haplotypes with other colonies, suggesting a different origin of re-colonisation of this specific colony. The effective population size of the New Zealand fur seal population at Banks Peninsula was estimated at approximately 2500 individuals. The exponential population growth rate parameter for the area was 35, which corresponds to an expanding population. In general, samples from adjacent colonies shared 4.4 haplotypes while samples collected from colonies separated by between five and eight bays shared 1.9 haplotypes. The genetic data support the spill-over dynamics of colony expansion already suggested for this species. Approximate Bayesian computations analysis suggests re-colonisation of the area from two main clades identified across New Zealand with a most likely admixture coefficient of 0.41 to form the Banks Peninsula population. Approximate Bayesian computations analysis estimated a founder population size of approximately 372 breeding individuals for the area, which then rapidly increased in size with successive waves of external recruitment. The population of fur seals in the area is probably in the late phase of maturity in the colony expansion dynamic. 相似文献
2.
3.
Verhoeven CH Gloudemans RH Groothuis GM Rietjens IM Vos RM 《The Journal of steroid biochemistry and molecular biology》2000,73(1-2):39-48
Metabolism of Org 30659 ((17alpha)-17-hydroxy-11-methylene-19-norpregna-4, 15-dien-20-yn-3-one), a new potent progestagen currently under clinical development by NV Organon for use in oral contraception and hormone replacement therapy, was studied in vivo after oral administration to healthy postmenopausal women. After oral administration of [14C]-Org 30659 to postmenopausal women, the compound was extensively metabolized. The dosed radioactivity was predominantly excreted via urine. Org 30659 was to a large extent metabolized at the C3- and the C17-positions. Phase II metabolism, and in particular conjugation with glucuronic acid at the 17beta-hydroxy group, is the major metabolic route for Org 30659 in vivo. Not only phase II metabolism was observed for Org 30659 after oral administration to postmenopausal volunteers, but also metabolism in the A-ring occurred, especially reduction of the 3-keto-Delta(4) moiety to give 3alpha-hydroxy, 5alpha(beta)-dihydro and 3beta-hydroxy, 5alpha-dihydro derivatives. Oxidative metabolism (6beta-hydroxylation) observed in human liver preparations in vitro, was not observed to a significant extent in vivo. So, in vitro human metabolism is different from the in vivo metabolism, indicating that the in vitro-in vivo extrapolation is far from straightforward, at least when only liver preparations are used. The proper choice of the in vitro system (e.g., microsomes, hepatocytes, slices or individually expressed enzymes) and the substrate concentration can be very important determinative factors for the predictability of the in vitro system for the in vivo situation. Species comparison of the metabolic routes of Org 30659 after oral administration indicated that the monkey seems to be a better representative species than the rat for the metabolism of Org 30659 in humans. 相似文献
4.
Identification of the omega4406 regulatory region, a developmental promoter of Myxococcus xanthus, and a DNA segment responsible for chromosomal position-dependent inhibition of gene expression 下载免费PDF全文
Loconto J Viswanathan P Nowak SJ Gloudemans M Kroos L 《Journal of bacteriology》2005,187(12):4149-4162
5.
C. H. J. Verhoeven R. H. M. Gloudemans P. A. M. Peeters J. J. van Lier F. T. M. Verheggen G. M. M. Groothuis I. M. C. M. Rietjens R. M. E. Vos 《The Journal of steroid biochemistry and molecular biology》2001,78(5):3485-480
The metabolism of desogestrel (13-ethyl-11-methylene-18,19-dinor-17-pregn-4-en-20-yn-17-ol), a progestagen used in oral contraceptives and hormone replacement therapy, was studied in vivo after a single oral administration of 150 μg [14C]-labeled desogestrel and 30 μg ethinylestradiol under steady state conditions to healthy postmenopausal women. After this oral administration, desogestrel was extensively metabolized. The dosed radioactivity was predominantly (60%) excreted via urine, while about 35% was excreted via the feces. Desogestrel was metabolized mainly at the C3-, C5-, C6- and C13-CH2CH3 positions. At the C3-position, the 3-keto moiety was found and in addition, 3β-hydroxy and 3-hydroxy groups were observed in combination with a reduced Δ4-double bond (5-H). Hydroxy groups were introduced at the C6- (6β-OH), the C13-ethyl (C13-CH2CH2OH) and possibly the C15- (15-OH) position of desogestrel. Conjugation of the 3-hydroxy moiety with sulfonic acid and conjugation with glucuronic acid were also major metabolic routes found for desogestrel in postmenopausal women. The 3-keto metabolite of desogestrel (the biologically active metabolite) was the major compound present in plasma at least up to 24 h after administration of the radioactive dose. Species comparison of the metabolic routes of desogestrel after oral administration indicates that in rats and dogs desogestrel is also mainly metabolized at the C3-position, similar to what is now found for postmenopausal women. Most other metabolic routes of desogestrel were found to differ between species. Finally, major metabolic routes found in the present study in postmenopausal women are in line with outcome of previous in vitro metabolism studies with human liver tissue (microsomes and postmitochondrial liver fractions) and intestinal mucosa. 相似文献
6.
7.
8.
In this study, the relationship between the concentration of extra-heavy crude petroleum in a clayey material and the toxicity, field capacity, temperature, and growth of a tropical forage grass (Brachiara humidicola) was determined empirically. For this type of petroleum the acute toxicity (Microtox®) was slight (CE50 = 63200 - 76400 mg/kg) even at high hydrocarbon concentrations (29279 mg/kg). Nonetheless, serious impacts were encountered in terms of an increase in soil temperature (+ 1.3 °C), reduction in field capacity (-10.7%) and reduction in aerial biomass (-97%). The relationship between hydrocarbon concentration and biomass resulted in a typical dose-response curve (r = 0.99), where a concentration of 2626 mg/kg of hydrocarbons corresponds to a maintenance of 90% biomass. Furthermore, during the duration of this study (one year) the biodegradation was proportional to the pasture biomass production (r = 0.997) indicating a synergistic relationship between the petroleum biodegrading microorganisms in the rhizosphere and the pasture. 相似文献
9.
We used ethylenediaminetetraacetic acid dianhydride (EDTAD) to modify oxalate decarboxylase (OXDC) to improve its adsorption on calcium oxalate stones. The modified sites were identified by Ultra performance liquid chromatography-mass spectrometry (UPLC-MS) and the adsorption mechanism of the EDTAD-modified OXDC on calcium oxalate (CaOx) was investigated. We investigated adsorption time, initial enzyme concentration, temperature and solution pH on the adsorption process. Data were analyzed using kinetics, thermodynamics and isotherm adsorption models. UPLC-MS showed that EDTAD was attached to OXDC covalently and suggested that the chemical modification occurred at both the free amino of the side chain and the α-NH2 of the peptide. The adsorption capacity of the EDTAD-OXDC on calcium oxalate was 53.37% greater than that of OXDC at the initial enzyme concentration of 5 mg/ml, pH = 7.0, at 37° C. The modified enzyme (EDTAD-OXDC) demonstrated improved oxalate degradation activity at pH 4.5?6.0. Kinetic data fitting analysis suggested a pseudo second order kinetic model. Estimates of the thermodynamic parameters including ΔG0, ΔH0 and ΔS0 of the adsorption process showed it to be feasible, spontaneous and endothermic. Isotherm data fitting analysis indicated that the adsorption process is reduced to monolayer adsorption at a low enzyme concentration and to multilayer adsorption at a high enzyme concentration. It may be possible to apply OXDC to degradation of calcium oxalate stones. 相似文献
10.
Yunjiao Wang Pawel Paszek Caroline A Horton Douglas B Kell Michael RH White David S Broomhead Mark R Muldoon 《BMC systems biology》2011,5(1):23