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1.
In the present study, we investigated the mechanism by which the antidiabetic drug phenformin increases insulin binding to its receptors in IM-9 human cultured lymphocytes. After a 24-hr preincubation, phenformin induced a twofold increase in specific 125I-insulin binding, and removal of phenformin was followed 6 hr later by a return in binding to control levels. This effect of phenformin on insulin binding was not a consequence of either inhibition of cell growth, changes in cellular cyclic adenosine monophosphate (AMP) levels, or changes in guanosine triphosphate (GTP) content. Since phenformin is known to inhibit various aspects of cellular energy metabolism, the relationship between 125I-insulin binding and energy metabolism in IM-9 cells was investigated. The phenformin-induced increase in insulin binding to IM-9 cells was related to a time- and dose-dependent decrease in ATP levels. Other agents that lowered ATP levels, including antimycin, dinitrophenol, and 2-deoxyglucose, also raised insulin binding. These studies indicated, therefore, that phenformin enhances insulin binding to receptors on IM-9 cells and that this effect on insulin receptors may be related to alterations in metabolic functions that are reflected by a lowering of ATP levels. 相似文献
2.
Intrinsic processes are assumed to underlie life history expression and trade‐offs, but extrinsic inputs are theorised to shift trait expression and mask trade‐offs within species. Here, we explore application of this theory across species. We do this based on parentally induced embryo temperature as an extrinsic input, and mass‐specific embryo metabolism as an intrinsic process, underlying embryonic development rate. We found that embryonic metabolism followed intrinsic allometry rules among 49 songbird species from temperate and tropical sites. Extrinsic inputs via parentally induced temperatures explained the majority of variation in development rates and masked a relationship with metabolism; metabolism explained a minor proportion of the variation in development rates among species, and only after accounting for temperature effects. We discuss evidence that temperature further obscures the expected interspecific trade‐off between development rate and offspring quality. These results demonstrate the importance of considering extrinsic inputs to trait expression and trade‐offs across species. 相似文献
3.
G Milazzo G L La Rosa R Catalfamo R Vigneri A Belfiore 《Journal of cellular biochemistry》1992,49(3):231-238
The well-known mitogenic effects of TSH observed in vivo on the thyroid are not always reproducible of human thyroid cells in vitro where conflicting results have been obtained. In order to clarify this issue, we have used primary cultures of human thyroid cells obtained from normal tissue and maintained in serum-free medium for several days. In this in vitro model we have studied the effect of TSH on growth by measuring three different parameters: [3H]-thymidine incorporation, cell counts, and DNA measurement. Monolayer cultures were plated at both low and high cell density (2 x 10(4) and 8 x 10(4) cells/25 mm well, respectively). Although at either cell density cultures were equally able to functionally respond to TSH in terms of cAMP accumulation a significant growth response to TSH was observed only in low density cultures. In high density cultures TSH had an antimitogenic effect. Moreover, TSH potentiated the mitogenic effect of insulin only in low density cultures. In contrast to TSH, FCS induced a similar proliferative response at both high and low cell density. Following TSH stimulation, cAMP content was always increased, paralleling the effect of growth in low density but not in high density cultures. The cAMP analogues dibutyryl-cAMP and 8-bromo-cAMP, as well as cholera toxin and forskolin, did not mimic the mitogenic effect of TSH but had an antiproliferative effect. In addition, these agents blunted the proliferative effect of insulin. These data suggest that in thyroid cells TSH is able to elicit both a mitogenic and an antimitogenic effect depending on the environmental conditions such as cell density.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
4.
Fragments of ascidian eggs, but at random in any plane and ranging in size from 10 to 90% of the total egg volume, displayed the electrical characteristics of the intact egg, having a resting potential of -86 mV and giving rise to an action potential upon stimulation by electrical current injection. Following insemination, the fragments generated fertilization potentials, comparable to those of intact eggs, although the repolarization phase was shorter. Our data show that there are sufficient ion channels throughout the egg surface to generate action potentials and fertilization potentials in excised egg fragments, irrespective of their global origin. Furthermore, the fertilizing spermatozoon is capable of activating fertilization channels in areas of the egg plasma membrane not destined for sperm entry. 相似文献
5.
Christina Brahe Isabella Velonà Gerrit van der Steege Stefania Zappata Anneke Y. van de Veen Jan Osinga Carli M. J. Tops Riccardo Fodde P. Meera Khan Charles H. C. M. Buys Giovanni Neri 《Human genetics》1994,93(5):494-501
The locus responsible for the childhood-onset proximal spinal muscular atrophies (SMA) has recently been mapped to an area of 2–3 Mb in the region q12–13.3 of chromosome 5. We have used a series of radiation hybrids (RHs) containing distinct parts of the SMA region as defined by reference markers. A cosmid library was constructed from one RH. Thirteen clones were isolated and five of these were mapped within the SMA region. Both RH mapping and fluorescence in situ hybridization analysis showed that two clones map in the region between loci D5S125 and D5S351. One of the cosmids contains expressed sequences. Polymorphic dinucleotide repeats were identified in both clones and used for segregation analysis of key recombinant SMA families. One recombination between the SMA locus and the new marker 9Ic (D5S685) indicates that 9Ic is probably the closest distal marker. The absence of recombination between the SMA locus and marker Fc (D5S684) suggests that Fc is located close to the disease gene. These new loci should refine linkage analysis in SMA family studies and may facilitate the isolation of the disease gene. 相似文献
6.
Riccardo Fedeli Andrea Vannini Martina Grattacaso Stefano Loppi 《The Annals of applied biology》2023,183(2):135-140
Potato is the fourth most widely consumed staple food in the world. This study investigated the effectiveness of 0.2% wood distillate (WD), a biostimulant derived from the pyrolysis of waste plant biomass, in boosting the nutritional quality of potato tubers. The results showed that application of WD significantly increased the content of soluble sugars (sucrose +56.3%; glucose +44.9%; fructose +62.2%), starch (+35.1%) and total carbohydrates (+16.8%). Antioxidants (total antioxidant power, polyphenols, flavonoids) and most mineral elements (K, Mg, Ca, Na, Fe, Zn) were not affected. A lower content of Cu (−17.8%) and P (−24.5%) was found in WD-treated potato. 相似文献
7.
Stefania Motta Marcello Monti Silvia Sesana Ruggero Caputo Stephana Carelli Riccardo Ghidoni 《生物化学与生物物理学报:疾病的分子基础》1993,1182(2):147-151
This paper investigates the ceramide composition of the psoriatic scale compared with that of normal human SC. A method was optimalized, based on TLC separation followed by densitometry, allowing the provision of good resolution and quantification of ceramide fractions from both normal and pathological specimens. Seven ceramide fractions were isolated and submitted to compositional analysis. The obtained results suggested a revisitation of previous ceramide designation. Therefore a simple classification is suggested, based on grouping ceramides carrying structural similarities under common codes. According to these rules, ceramides were grouped into five classes designated as: (1) Cer[EOS], which contains ester-linked fatty acids, ω-OH fatty acids and sphingosines; (2) Cer[NS], which contains non-OH fatty acids and sphingosines; (3) Cer[NP], which contains non-OH fatty acids and phytosphingosines; (4) Cer[AS], which contains α-OH fatty acids and sphingosines; (5) Cer[AP], which contains α-OH fatty acids and phytosphingosines. Analysis of ceramides from the psoriatic scale, compared to those from normal human SC, resulted in an impairment of the Cer[EOS] content as well as of the ceramides containing phytosphingosine, with concurrent increase in ceramides containing sphingosine, being the total amount maintained identical. Since one of the suggested pathways for phytosphingosine biosynthesis involves the water addition to the corresponding sphingosine double bond, we can speculate that the observed alterarion is due to a deranged water bioavailability, associated with psoriaris. 相似文献
8.
9.
APC mutation in the alternatively spliced region of exon 9 associated with late onset familial adenomatous polyposis 总被引:11,自引:0,他引:11
Rob B. van der Luijt Hans F. A. Vasen Carli M. J. Tops Cor Breukel Riccardo Fodde P. Meera Khan 《Human genetics》1995,96(6):705-710
Germ-line mutations in the adenomatous polyposis coli (APC) gene are responsible for familial adenomatous polyposis (FAP). Genotype-phenotype correlation studies in patients with FAP have demonstrated associations of certain variants of the disease with mutations at specific sites within the APC gene. In a large FAP family, we identified a frameshift mutation located in the alternatively spliced region of exon 9. Phenotypic studies of affected family members showed that the clinical course of FAP was delayed, with gastrointestinal symptoms and death from colorectal carcinoma occurring on average 25 and 20 years later than usual, respectively. The numbers of colorectal adenomas differed markedly among affected individuals and the location of colorectal cancer lay frequently in the proximal colon. Our findings suggest that the exon 9 mutation identified in the pedigree is associated with late onset of FAP. The atypical phenotype may be explained by the site of the mutation in the APC gene. Analysis of the APC protein product indicated that the exon 9 mutation did not result in a detectable truncated APC protein. Given the location of the mutation within an alternatively spliced exon of APC, it is conceivable that normal APC proteins are produced from the mutant allele by alternative splicing. 相似文献
10.
Riccardo Cerri Francesco De Simone Felice Senatore 《Biochemical Systematics and Ecology》1981,9(4):247-248
The sterol composition of three fungi was determined. Ergosterol is the major sterol, accompanied by other closely related sterols. 相似文献