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71.
Rafał Krętowski Anna Stypułkowska Marzanna Cechowska-Pasko 《Molecular and cellular biochemistry》2015,398(1-2):165-173
The inhibition of the 26S proteasome evokes endoplasmic reticulum stress, which has been shown to be implicated in the antitumoral effects of proteasome inhibitors. The cellular and molecular effects of the proteasome inhibitor—bortezomib—on human colon cancer cells are as yet poorly characterized. Bortezomib selectively induces apoptosis in some cancer cells. However, the nature of its selectivity remains unknown. Previously, we demonstrated that, in contrast to normal fibroblasts, bortezomib treatment evoked strong effect on apoptosis of breast cancer cells incubated in hypoxic and normoxic conditions. The study presented here provides novel information on the cellular effects of bortezomib in DLD-1 colon cancer cells line. We observe twofold higher percentage of apoptotic cells incubated for 48 h with 25 and 50 nmol/l of bortezomib in hypoxic conditions and four-, fivefold increase in normoxic conditions in comparison to control cells, incubated without bortezomib. It is of interest that bortezomib evokes strong effect on necrosis of DLD-1 colon cancer cell line. We observe the sixfold increase in necrosis of DLD-1 cells incubated with 25 or 50 nmol/l of bortezomib for 48 h in hypoxia and fourfold increase in normoxic conditions in comparison to adequate controls. We suggest that bortezomib may be candidates for further evaluation as chemotherapeutic agents for human colon cancer. 相似文献
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73.
Emmanuelle Fontoura José Darival Ferreira Jamile Bubadué Ana Maria Ribeiro Leonardo Kerber 《Journal of morphology》2020,281(10):1223-1240
A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology. 相似文献
74.
Anna V. Klenova 《PloS one》2015,10(11)
Begging behaviour is an important element in the parent-offspring conflict; it has been studied in many avian species. However, the majority of the studies have been entirely based on the call counts, and they agreed that vocal activity was a good indicator of chick’s nutritional need and/or condition. Fewer researches were dedicated to the temporal-frequency variables of the begging calls themselves and they showed contrary results. Here begging behaviour in three burrow nested, uniparous species of auks (Alcidae) was studied. These objects provide an opportunity to study the signalling value of begging calls in the absence of important confounding factors such as nestling competition and predation pressure. I recorded calls of individual chicks in two conditions: during natural feeding and after experimental four-hour food deprivation. I found that almost all measured acoustic variables contain information about the chick’s state in all studied species. The hungry chicks produced calls higher in fundamental frequency and power variables and at higher calling rate compared to naturally feeding chicks. The effect of food deprivation on most acoustic variables exceeded both the effects of individuality and species. In all studied species, the frequency variables were stronger affected by hunger than the calling rate and call durations. I suppose that such strong change of acoustic variables after food deprivation can be explained by absence of vocal individual identification in these birds. As parents do not need to check individuality of the chick in the burrow, which they find visually during the day time, the chicks could use all of the acoustic variables to communicate about their nutritional needs. 相似文献
75.
76.
Abstract Ultrastructure of the apical cell of Halopteris scoparia (L.) Sauvageau (Phaeophyceae, Sphacelariales). - The ultrastructure of resting apical cells of Halopteris scoparia (L.) Sauvageau from material collected in December is described. The cytoplasm is higly vacuolated with lipids, poliphenolic substances and polisaccharides occurring inside the vacuoles (the classic « physodes »). Two cell organelles are prominently active at this stage: conspicuosly hypertrophic dictyosomes and the budding endoplasmic reticulum. Both light and electron microscope observations show that the cell wall has an outer stratification and inner discontinuous thickenings, the constituent material of which is uniformerly dispersed. The above observations point out that the apical cell of Halopteris scoparia at this stage of its life cycle is engaged in an elaboration of vacuolar and parietal substances which will be therefore readly available at the outset of the growing season. 相似文献
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78.
Anna E. Goodroe Casey Fitz Michael L. Power Ricki J. Colman Saverio Capuano III Toni E. Ziegler 《American journal of primatology》2020,82(6):e23131
Vitamin D3 (cholecalciferol) is endogenously produced in the skin of primates when exposed to the appropriate wavelengths of ultraviolet light (UV-B). Common marmosets (Callithrix jacchus) maintained indoors require dietary provision of vitamin D3 due to lack of sunlight exposure. The minimum dietary vitamin D3 requirement and the maximum amount of vitamin D3 that can be metabolized by marmosets is unknown. Observations of metabolic bone disease and gastrointestinal malabsorption have led to wide variation in dietary vitamin D3 provision amongst research institutions, with resulting variation in circulating 25-hydroxyvitamin D3 (25(OH)D3), the accepted marker for vitamin D sufficiency/deficiency. Multiple studies have reported serum 25(OH)D3 in captive marmosets, but 25(OH)D3 is not the final product of vitamin D3 metabolism. In addition to serum 25(OH)D3, we measured the most physiologically active metabolite, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), and the less well understood metabolite, 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) to characterize the marmoset's ability to metabolize dietary vitamin D3. We present vitamin D3 metabolite and related serum chemistry value colony reference ranges in marmosets provided diets with 26,367 (Colony A, N = 113) or 8,888 (Colony B, N = 52) international units (IU) of dietary vitamin D3 per kilogram of dry matter. Colony A marmosets had higher serum 25(OH)D3 (426 ng/ml [SD 200] vs. 215 ng/ml [SD 113]) and 24,25(OH)2D3 (53 ng/ml [SD 35] vs. 7 ng/ml [SD 5]). There was no difference in serum 1,25(OH)2D3 between the colonies. Serum 1,25(OH)2D3 increased and 25(OH)D3 decreased with age, but the effect was weak. Marmosets tightly regulate metabolism of dietary vitamin D3 into the active metabolite 1,25(OH)2D3; excess 25(OH)D3 is metabolized into 24,25(OH)2D3. This ability explains the tolerance of high levels of dietary vitamin D3 by marmosets, however, our data suggest that these high dietary levels are not required. 相似文献
79.
80.
George V. Sharonov Eduard V. Bocharov Peter M. Kolosov Maria V. Astapova Alexander S. Arseniev Alexey V. Feofanov 《The Journal of biological chemistry》2014,289(21):14955-14964
The EphA2 receptor tyrosine kinase plays a central role in the regulation of cell adhesion and guidance in many human tissues. The activation of EphA2 occurs after proper dimerization/oligomerization in the plasma membrane, which occurs with the participation of extracellular and cytoplasmic domains. Our study revealed that the isolated transmembrane domain (TMD) of EphA2 embedded into the lipid bicelle dimerized via the heptad repeat motif L535X3G539X2A542X3V546X2L549 rather than through the alternative glycine zipper motif A536X3G540X3G544 (typical for TMD dimerization in many proteins). To evaluate the significance of TMD interactions for full-length EphA2, we substituted key residues in the heptad repeat motif (HR variant: G539I, A542I, G553I) or in the glycine zipper motif (GZ variant: G540I, G544I) and expressed YFP-tagged EphA2 (WT, HR, and GZ variants) in HEK293T cells. Confocal microscopy revealed a similar distribution of all EphA2-YFP variants in cells. The expression of EphA2-YFP variants and their kinase activity (phosphorylation of Tyr588 and/or Tyr594) and ephrin-A3 binding were analyzed with flow cytometry on a single cell basis. Activation of any EphA2 variant is found to occur even without ephrin stimulation when the EphA2 content in cells is sufficiently high. Ephrin-A3 binding is not affected in mutant variants. Mutations in the TMD have a significant effect on EphA2 activity. Both ligand-dependent and ligand-independent activities are enhanced for the HR variant and reduced for the GZ variant compared with the WT. These findings allow us to suggest TMD dimerization switching between the heptad repeat and glycine zipper motifs, corresponding to inactive and active receptor states, respectively, as a mechanism underlying EphA2 signal transduction. 相似文献