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1.
Alpha-melanotropin (alpha-melanocyte stimulating hormone, alpha-MSH) is a hormone produced by the pituitary gland of most vertebrate animals. This melanotropic peptide, Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2, regulates melanin pigmentation of the skin of some mammals. Although MSH may be absent from the human pituitary gland, this peptide can stimulate pigment formation in human skin. We have synthesized several analogues of alpha-MSH, which are superpotent, prolonged-acting, and resistant to inactivation by serum enzymes. One such analogue, [NLe4, D-Phe7]alpha-MSH, has proven particularly useful in a number of physiological studies. In addition, some [Nle4, D-Phe7]-substituted fragment analogues of MSH are even more active than the native hormone, alpha-MSH. For example, these analogues are 100–1,000 times more active than alpha-MSH in stimulating S-91 mouse melanoma tyrosinase activity in vitro. We have successfully labeled one such peptide to high specific activity; this melanotropin, [3H]-Ac-[Nle4, D-Phe7]alpha-MSH4–11NH2, has been shown by others to bind to B16 melanoma cells. We have also conjugated several ligands (fluorescein and biotin) to [Nle4, D-Phe7]alpha-MSH. These melanotropin conjugates might prove useful for melanotropin receptor studies and for the clinical localization of metastatic melanoma. We have demonstrated that [Nle4, D-Phe4]alpha-MSH can be topically applied and transdermally delivered across the skin of mice and humans in vitro, as determined by bioassay and RIA. Initial toxicologic studies indicate that the analogue is nontoxic to mice and is not mutagenic. Studies are underway to determine whether this analogue may prove useful as a “tanning hormone” for increasing the pigmentation of light-skinned individuals or possibly even for treating people with certain hypopigmentary disorders. 相似文献
2.
Burlini N Iriti M Daghetti A Faoro F Ruggiero A Bernasconi S 《Plant cell reports》2011,30(11):2131-2141
Benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH), a particularly efficient inducer of systemic acquired resistance (SAR), was developed as an immunizing
agent to sensitize various crop species against pathogen infections. Recent works highlighted its activating effect on different
metabolic pathways, concerning both primary and secondary metabolites. In this study, we investigated the effect of BTH treatment
on sterol levels and vitamin D3 metabolism in Solanum malacoxylon cultures. Calli of S. malacoxylon were incubated in Gamborg B5 liquid medium alone or added with 50 μM BTH for different times (one, two or three cycles of
light). Histocytochemical investigations performed on our experimental system using 3,3′-diaminobenzidine (DAB) for hydrogen
peroxide (H2O2) detection and phloroglucinol for lignin staining showed that BTH causes H2O2 accumulation and lignin deposition in treated calli. Gas chromatographic analysis of principal cell membrane sterols (β-sitosterol,
campesterol, stigmasterol) showed that BTH transiently increases their cellular levels. Callus cultures were found to contain
also cholesterol, 7-dehydrocholesterol, the putative precursor of vitamin D3, and the hydroxylated metabolites 25-hydroxyvitamin D3 [25(OH)D3] and 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3]. BTH treatment enhanced 7-dehydrocholesterol while reduced cholesterol. HPLC analysis of sample extracts showed that BTH
does not affect the cell content of vitamin D3, though results of ELISA tests highlighted that this elicitor moderately enhances the levels of 25(OH)D3 and 1α,25(OH)2D3 metabolites. In conclusion, BTH treatment not only causes cell wall strengthening, a typical plant defence response, as just
described in other experimental models, but in the same time increases the cellular level of the main sterols and 7-dehydrocholesterol. 相似文献
3.
The ability of the enzyme subtilisin DY for the synthesis of derivatives of DL-aspartic acid which are differently N and C-terminal protected and semiproducts of the peptide synthesis was investigated. The enzyme reaction was characterized by high yields and a comparatively short reaction time. Two of the substrates, Z-D,L-Asp-(OMe)2 and PhAc-D,L-Asp-(OMe)2, were hydrolyzed for about 15 min; the reaction time for Boc-D,L-Asp-(OMe)2 was 2.5 h. The values for the MICHAELIS constants obtained for Z-D,L-Asp-(OMe)2 (Km = 0.576 mM) and PhAc-D,L-Asp-(OMe)2 (Km = 0.300 mM) showed a high affinity of the enzyme to the substrates. For Boc-D,L-Asp-(OMe)2 the affinity of the enzyme is considerable lower (Km = 14.07 mM). The results of these investigations can be effectively used for the separation of N-protected derivatives of D,L-aspartic acid and with a high probability also for other amino and racemic forms. 相似文献
4.
The vapor pressure deficit (D) of the atmosphere can negatively affect plant growth as plants reduce stomatal conductance to water vapor (gwv) in response to increasing D, limiting the ability of plants to assimilate carbon. The sensitivity of gwv to changes in D varies among species and has been correlated with the hydraulic conductance of leaves (Kleaf), but the hydraulic conductance of other tissues has also been implicated in plant responses to changing D. Among the 19 grass species, we found that Kleaf was correlated with the hydraulic conductance of large longitudinal veins (Klv, r2 = 0.81), but was not related to Kroot (r2 = 0.01). Stomatal sensitivity to D was correlated with Kleaf relative to total leaf area (r2 = 0.50), and did not differ between C3 and C4 species. Transpiration (E) increased in response to D, but 8 of the 19 plants showed a decline in E at high D, indicative of an ‘apparent feedforward’ response. For these individuals, E began to decline at lower values of D in plants with low Kroot (r2 = 0.72). These results show the significance of both leaf and root hydraulic conductance as drivers of plant responses to evaporative demand. 相似文献
5.
Static and dynamic light-scattering measurements are reported on zinc-insulin at room temperature (21 ± l°C) and pH = 6.88 in 0.1M NaCl aqueous solution. The experiments were performed at very low concentration, in the range 0.12 × 10?4 to 0.90 × 10?4 g cm?3. Within experimental error, we find no evidence for a critical micellar concentration in this system. The aggregation phenomenon starts immediately after preparation of the solutions, and takes several days to come to stable equilibrium. The concentration dependence of the diffusion coefficients, D z, = Do (1 — kDC), is negative, and kD was observed to decrease as a function of time, while the aggregate size was found to increase. The equivalent concentration coefficient, ?2BM W, obtained from static light scattering, showed a similar behavior, and, within experimental error, was found to be numerically equal to kD. From the relation found between the diffusion coefficient at infinite dilution and the molecular weight of the aggregates, log D0 = ?0.240 log M w ? 5.077, we deduce that the insulin aggregates are compact structures with a characteristic radius of 0.71 Å/(dalton)1/3, surrounded by a hydration layer of a thickness of 8.0 Å. The equilibrium aggregation number is approximately 10. 相似文献
6.
Maria Kozowska 《Biometrical journal. Biometrische Zeitschrift》1999,41(4):427-430
A class of incomplete block designs called C-design, was considered by Caliński (1971), Saha (1976), Ceranka (1983) and Ceranka , Kozłowska (1983, 1984). In this paper we extend the theory of block designs having the C-property. We consider optimality of C-designs with respect to any criterion of a described form. Das and Kageyama (1991) considered a class of E-optimal proper efficiency balanced designs (strictly speaking, Das and Kageyama considered ER-optimality of some class of block designs). Hence we consider ER, AR, DR optimality of C-designs. 相似文献
7.
Grażyna Chłoń-Rzepa Adam Bucki Marcin Kołaczkowski Anna Partyka Magdalena Jastrzębska-Więsek Grzegorz Satała 《Journal of enzyme inhibition and medicinal chemistry》2016,31(6):1048-1062
A series of new 7-arylpiperazinylalkyl-1,3-dimethyl-purine-2,6-dione derivatives with diversified 8-amino substituent in 8 position was synthesized and their 5-HT1A, 5-HT2A, 5-HT6, 5-HT7, and D2 receptor affinities were determined. The binding study allowed identifying some potent 5-HT1A/5-HT2A/5-HT7/D2 ligands. The most interesting because of their multireceptor profile were 8-piperidine (30–35) and 8-dipropylamine (45–47) analogs with four and five carbon aliphatic linkers. The selected compounds 24, 31, 34, 39, 41, 43, 45, and 46 in the functional in vitro evaluation for all targeted receptors showed significant partial D2 agonist, partial 5-HT1A agonist, and 5-HT2A antagonist properties. The advantageous in vitro affinity of compound 34 for 5-HT1A and D2 receptors has been explained by means of molecular modeling, taking into consideration its partial agonist activity towards the latter one. In behavioral studies, compounds 32 and 34 revealed antipsychotic-like properties, significantly decreasing d-amphetamine-induced hyperactivity in mice. 相似文献
8.
Joji Sasaki Akiko Miyazaki Mika Saito Takashi Adachi Kazutoshi Mizoue Kazunori Hanada Sadafumi Omura 《Applied microbiology and biotechnology》1992,38(2):152-157
To enzymatically synthesize active metabolites of vitamin D3, we screened about 500 bacterial strains and 450 fungal strains, of which 12 strains were able to convert vitamin D3 to 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] via 25-hyroxyvitamin D3 [25(OH)D3]. The conversion activity was only detected in strains belonging to the genus Amycolata among all the organisms tested. A preparative-scale conversion of vitamin D3 to 25(OH)D3 and 1,25(OH)2D3 in a 200-1 tank fermentor using A. autotrophica FERM BP-1573 was accomplished, yielding 8.3 mg 25(OH)D3/l culture and 0.17 mg 1,25(OH)2D3/l culture. A related compound, vitamin D2, could be also converted to 25-hydroxyvitamin D2 and 1,25-dihydroxyvitamin D2 using the same strain. The cytochrome P-450 of FERM BP-1573 was detected by reduced CO difference spectra in whole-cell suspensions. Vitamin D3 in the culture induced cytochrome P-450 and the conversion activity simultaneously, suggesting that the hydroxylation at C-25 of vitamin D3 and at C-1 of 25(OH)D3 originates from cytochrome P-450.Correspondence to: J. Sasaki 相似文献
9.
C. Tony Liang Janice Barnes Richard A. Balakir Bertram Sacktor 《The Journal of membrane biology》1986,90(2):145-156
Summary Thein vivo andin vitro effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on calcium uptake by isolated chick duodenal cells were studied.In vivo, 1,25-(OH)2D3 given orally to vitamin D-deficient chicks increased the initial rate of calcium uptake by cells prepared 1 hr after administration of the hormone. The rate was stimulated approximately 100%, 17 to 24 hr after repletion.In vitro, pre-incubation of 1,25-(OH)2D3 with cells from D-deficient chicks increased the cellular rate of calcium uptake in a concentration-dependent relationship. Enhancement was found with 10–15
m, was maximal at 10–13
m, and was diminished at higher (10–11
m) concentrations. Stimulation was observed after a pre-incubation period as brief as 1 hr. The potency order for vitamin D3 analogs was 1,25-(OH)2D3=1-(OH)D3>25-(OH)D3>1,24,25-(OH)3D3>24,25-(OH)2D3>D3. The maximal enhancement in calcium uptake induced by the analogs was the same, only the concentration at which the cell responded was different. The effectiveness of 1,25-(OH)2D3 was five orders of magnitude greater than D3. Kinetically, 1,25-(OH)2D3 increased theV
max of calcium uptake; the affinity for calcium (K
m=0.54mm) was unchanged. The enhanced uptake found after the cells were pre-incubated for 2 hr with the hormone was completely blocked by inhibitors of protein synthesis. 1,25-(OH)2D3,in vitro, also increased calcium uptake in cells isolated from D-replete chicks. The maximal rates of uptake were the same in cells from D-deficient and D-replete animals. The hormone had no effect of calcium efflux from cells. Calcium uptake in microvillar brush-border membrane vesicles was increased by 1,25-(OH)2D3. These findings suggest that thein vitro cell system described in this paper represents an appropriate model to examine the temporal relationships between 1,25-(OH)2D3 induction of calcium transport and specific biochemical correlates. 相似文献
10.
The study investigated the relationship between five moult stages and the osmoregulatory capacities (OC), moisture content of hepatopancreas (HM%), hepatosomatic indices (HIwet, HIdry) and growth of 6 weight classes of 235 marron (Cherax cainii) and 235 yabbies (Cherax destructor) under laboratory conditions. In each moult stage, OC increased linearly with the increase in wet body weight. Intermoult stage C showed the highest OC significantly lower than premoult stages D0, D1, D2 and postmoult stage AB in every weight class in both crayfish. HM% decreased from AB to D2, while both HIwet and HIdry reduced from C to D2. Percentage dry matter of whole body carcass was highest in stage C and lowest during the AB stage with a significant difference between the two species. Larger than 15-g marron and yabbies differ with each other in OC, HIwet, and HIdry, moult intervals and growth rates. 相似文献
11.
Sahlholm K Marcellino D Nilsson J Fuxe K Arhem P 《Biochemical and biophysical research communications》2008,374(3):496-501
Agonist potency at some neurotransmitter receptors has been shown to be regulated by transmembrane voltage, a mechanism which has been suggested to play a crucial role in the regulation of neurotransmitter release by autoreceptors and in synaptic plasticity. We have recently described the voltage-sensitivity of the dopamine D2L receptor and we now extend our studies to include the other members of the D2-like receptor subfamily; the D2S, D3, and D4 dopamine receptors. Electrophysiological recordings were performed on Xenopus oocytes coexpressing human dopamine D2S, D3, or D4 receptors with G protein-coupled potassium (GIRK) channels. Comparison of concentration-response relationships at −80 mV and at 0 mV for dopamine-mediated GIRK activation revealed significant rightward shifts for both D2S and D4 upon depolarization. In contrast, the concentration-response relationships for D3-mediated GIRK activation were not appreciably different at the two voltages. Our findings provide new insight into the functional differences of these closely related receptors. 相似文献
12.
Houle 《Journal of evolutionary biology》2000,13(4):720-730
The relationship between developmental stability and morphological asymmetry is derived under the standard view that structures on each side of an individual develop independently and are normally distributed. I use developmental variance of sizes of parts, VD, as the converse of developmental stability, and assume that VD follows a gamma distribution. Repeatability of asymmetry, a measure of how informative asymmetry is about VD, is quite insensitive to the variance in VD, for example only reaching 20% when the coefficient of variation of VD is 100%. The coefficient of variation of asymmetry, CVFA, also increases very slowly with increasing population variation in VD. CVFA values from empirical data are sometimes over 100%, implying that developmental stability is sometimes more variable than any previously studied type of trait. This result suggests that alternatives to this model may be needed. 相似文献
13.
We show that explicit mathematical and biological relationships exist among the scaling exponents and the allometric constants (α and β, respectively) of log–log linear tree‐community size frequency distributions, plant density NT, and minimum, maximum and average stem diameters (Dmin, Dmax, and , respectively). As individuals grow in size and Dmax increases, NT is predicted to decrease as reflected by a decrease in the numerical value of α and an increase in the value of β. Our derivations further show that NT decreases as increases even if Dmin or Dmax remain unchanged. Because Dmax and the age of the largest individuals in a community are correlated, albeit weakly, we argue that the interdependent relationships among the numerical values of α, β, NT, and shed light on the extent to which communities have experienced recent global disturbance. These predicted relationships receive strong statistical support using two large datasets spanning a broad spectrum of tree‐dominated communities. 相似文献
14.
Mei-Ling Siu-Caldera Jeffrey W. Clark Anabela Santos-Moore Sara Peleg Yan Yun Liu Milan R. Uskokovi Surendra Sharma G. Satyanarayana Reddy 《The Journal of steroid biochemistry and molecular biology》1996,59(5-6)
1α,25(OH)2-16-ene-D3, a synthetic analog of the steroid hormone, 1α,25(OH)2D3, has great potential to become a drug in the treatment of leukemia and other proliferative disorders, because of its minimal in vivo calcemic activity associated with a potent inhibitory effect on cell growth. However, at present, the mechanisms through which 1α,25(OH)2-16-ene-D3 expresses its biological activities are still not completely understood. Our previous in vitro study in a perfused rat kidney indicated for the first time that 1α,25(OH)2-16-ene-D3 and 1α,25(OH)2D3 are metabolized differently. 1α,25(OH)2-24-oxo-16-ene-D3, an intermediary metabolite of 1α,25(OH)2-16-ene-D3 formed through the C-24 oxidation pathway, accumulated significantly in the perfusate when compared to 1α,25(OH)2-24-oxo-D3, the corresponding intermediary metabolite of 1α,25(OH)2D3. In a subsequent in vivo study, we also reported that 1α,25(OH)2-24-oxo-16-ene-D3 exerted immunosuppressive activity equal to its parent, without causing significant hypercalcemia. In order to establish further the critical role of 1α,25(OH)2-24-oxo-16-ene-D3, in generating some of the key biological activities ascribed to its parent, we performed the present in vitro study using a human myeloid leukemic cell line (RWLeu-4) as a model. Comparative target tissue metabolism studies indicated that 1α,25(OH)2-16-ene-D3 and 1α,25(OH)2D3 are metabolized differently in RWLeu-4 cells, and the differences were similar to the ones we previously observed in the rat kidney. The significant finding was the accumulation of 1α,25(OH)2-24-oxo-16-ene-D3 in RWLeu-4 cells because of its resistance to further metabolism. Biological activity studies indicated that both 1α,25(OH)2-16-ene-D3 and its 24-oxo metabolite produced growth inhibition and promoted differentiation of RWLeu-4 cells to the same extent, and these activities were several fold higher than those exerted by 1α,25(OH)2D3. In addition, the genomic action of each vitamin D compound was assessed in a rat osteosarcoma cell line (ROS 17/2.8) by measuring its ability to transactivate a gene construct containing the vitamin D response element of the osteocalcin gene linked to the growth hormone reporter gene. In these studies, both 1α,25(OH)2-16-ene-D3 and its 24-oxo metabolite exerted similar but potent transactivation activity which was several fold greater than that exerted by 1α,25(OH)2D3 itself. In summary, our results indicate that the production and slow clearance of the bioactive intermediary metabolite, 1α,25(OH)2-24-oxo-16-ene-D3, in RWLeu-4 cells contributes significantly to the final expression of the enhanced biological activities ascribed to its parent analog, 1α,25(OH)2-16-ene-D3. 相似文献
15.
The product, Doα, of the oxygen diffusion coefficient, Do, and the oxygen solubility, α, is determined in phosphatidylcholine bilayers at temperatures above the lipid phase transitions from ESR spin-exchange measurements. The resulting values of Doα are in good agreement with those obtained from fluorescence-quenching experiments. The use of fatty acid spin labels makes it possible to measure Doα as a function of the coordinate perpendicular to the bilayer surface. The results indicate that Doα is a strong function of this coordinate; it is greatest in the bilayer center and least near the bilayer head groups. 相似文献
16.
Carbohydrate uptake in Advenella mimigardefordensis strain DPN7T is mediated by periplasmic sugar oxidation and a TRAP‐transport system
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Christina Meinert Jana Senger Marco Witthohn Jan Hendrik Wübbeler Alexander Steinbüchel 《Molecular microbiology》2017,104(6):916-930
In this study, we investigated an SBP (DctPAm) of a tripartite ATP‐independent periplasmic transport system (TRAP) in Advenella mimigardefordensis strain DPN7T. Deletion of dctPAm as well as of the two transmembrane compounds of the tripartite transporter, dctQ and dctM, impaired growth of A. mimigardefordensis strain DPN7T, if cultivated on mineral salt medium supplemented with d ‐glucose, d ‐galactose, l ‐arabinose, d ‐fucose, d ‐xylose or d ‐gluconic acid, respectively. The wild type phenotype was restored during complementation studies of A. mimigardefordensis ΔdctPAm using the broad host vector pBBR1MCS‐5::dctPAm. Furthermore, an uptake assay with radiolabeled [14C(U)]‐d ‐glucose clearly showed that the deletion of dctPAm, dctQ and dctM, respectively, disabled the uptake of this aldoses in cells of either mutant strain. Determination of KD performing thermal shift assays showed a shift in the melting temperature of DctPAm in the presence of d ‐gluconic acid (KD 11.76 ± 1.3 µM) and the corresponding aldonic acids to the above‐mentioned carbohydrates d ‐galactonate (KD 10.72 ± 1.4 µM), d ‐fuconic acid (KD 13.50 ± 1.6 µM) and d ‐xylonic acid (KD 8.44 ± 1.0 µM). The sugar (glucose) dehydrogenase activity (E.C.1.1.5.2) in the membrane fraction was shown for all relevant sugars, proving oxidation of the molecules in the periplasm, prior to transport. 相似文献
17.
18.
Saswati Chatterjee-Das Erik P. Lillehoj Diana M. Hernandez John E. Coligan David H. Sachs 《Immunogenetics》1987,25(1):7-14
To analyze how many D-region-encoded molecules could be detected inH-2
q
, we produced a panel of nine monoclonal antibodies from AKR (KkDk) anti-AKR.M (KkDq) immunizations. All of the Dq region antibodies cross-reacted on Dd and/or Ld, and all except one cross-reacted on Db, confirming the previously observed serologic and amino acid sequence homology between theD-region products ofH-2
d
,H-2
b
, andH-2
q
. All of these monoclonal antibodies precipitated 46 000 dalton molecules from both cell-surface-labeled and biosynthetically labeled BIO.AKM spleen cells, indicating that all were reactive with class I-like molecules. Sequential immunoprecipitation analysis with one of these antibodies, 66-3-5, reveals the presence of a previously unidentified class I-like molecule. Tryptic peptide map analysis reveals that this molecule may be the product of a newly describedH-2D
q
-region gene. 相似文献
19.
Mello EO Ribeiro SF Carvalho AO Santos IS Da Cunha M Santa-Catarina C Gomes VM 《Current microbiology》2011,62(4):1209-1217
In recent years, studies have demonstrated the function of many antimicrobial peptides against an extensive number of microorganisms
that have been isolated from different plant species and that have been used as models for the study of various cellular processes
linked to these peptides’ activities. Recently, a new defensin from Phaseolus vulgaris (L.) seeds, named PvD1, was isolated and characterized. PvD1 was purified through anion exchange and phase-reverse chromatography. PvD1’s antifungal activity was tested. A SYTOX Green uptake assay revealed that the defensin PvD1 is capable of causing membrane permeabilization in the filamentous fungi Fusarium oxysporum, Fusarium solani, and Fusarium laterithium and in yeast strains Candida parapsilosis, Pichia membranifaciens, Candida tropicalis, Candida albicans, Kluyveromyces marxiannus, and Saccharomyces cerevisiae at a concentration of 100 μg/ml. Ultrastructural analysis of C. albicans and C. guilliermondii cells treated with this defensin revealed disorganization of both cytoplasmic content and the plasma membrane. PvD1 is also able to inhibit glucose-stimulated acidification of the medium by yeast cells and filamentous fungi, as well as to
induce the production of reactive oxygen species and nitric oxide in C. albicans and F. oxysporum cells. 相似文献
20.
Dynamic light scattering (DLS) studies are carried out on native ΦW-14 DNA, which has putrescines covalently attached at the methyl groups of half its thymines, and on a chemically modified form of the same DNA in which the ammonium groups of its putrescines are almost completely acetylated. From neutrality to pH 9.6, both forms of ΦW-14 DNA exhibit the same curve of Dapp vs K2 over the range K2 = 0.5 × 1010 to K2 = 20 × 1010 cm?2, and this coincides with curves that we have observed for other DNAs. (Dapp, apparent diffusion coefficient; K, scattering vector). However, when the pH is raised to pH 10.0–10.2, native ΦW-14 exhibits a spectacular decrease in Dapp at large wave vector, whereas the acetylated form shows no sign of such behavior. It is inferred that bound ammonium groups make an essential contribution to the stabilization of titratable joints. Comparing the pH profiles of the absorbance (A260) for these two DNAs gives some evidence that base unstacking may be involved in titratable joint formation. 相似文献