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81.
F Rabanal I Haro F Reig J M García-Antón 《International journal of peptide and protein research》1990,36(1):26-30
The synthesis of three hepatitis B surface antigens derived from S and pre-S proteins (adw S(140-147), [Tyr148] adw S(139-148), and adw pre-S(120-145)) has been accomplished by the continuous flow Fmoc-polyamide solid phase method. The use of different scavengers and trimethylsilyl bromide (TMSBr) in trifluoroacetic acid as deprotecting procedures is discussed. 相似文献
82.
Development of the visual system of anchovy larvae,Engraulis anchoita: A microanatomical description
Valeria Miranda Stefanía Cohen Alcira O. Díaz Marina V. Diaz 《Journal of morphology》2020,281(4-5):465-475
During the early ontogeny of fish larvae, the accurate development of the visual system plays a key role, because it is involved in locating food, orientation, selection of favorable habitat, and evasion of predators. The structure of the eye of the fish is typical of vertebrates, with some modifications related to the aquatic environment. In the present work, we describe the development of the larval eye of Engraulis anchoita for the first time. Larvae were collected at the Permanent Station of Environmental Studies (EPEA) in coastal waters of the Southwestern Atlantic Ocean during research cruises in 2015 and 2016. We describe the histology of the retina layers, determine the beginning of the functionality of the eye, and discuss a possible synchronization with the development of the digestive tract. This study provides information about the biology of E. anchoita, the most abundant fish species in the southwestern Atlantic Ocean. Also, recent studies have shown responses of the retina and other tissues to the increase in environmental acidity. Therefore, results of this study are also discussed with respect to the possible effect of acidification on the larvae of this species. The continuity of the time series developed at the EPEA will allow monitoring the effect of long-term environmental and biological variables on the early ontogeny of anchovy in the context of climate change. The high commercial fishing potential of E. anchoita due to its high abundance, as well as its essential role in the trophic web of other commercially valuable fishing resources of Argentina, reinforce the need to continue deepening knowledge about this species. Research highlights:
- Eyes of Engraulis anchoita larvae are functional from early larval stages.
- At hatching, the retina is formed by only few layers from which the other layers differentiates during ontogeny.
- Focal distance increases with larval growth.
83.
Mutations in the human homolog of the Vhlh gene [encoding the von-Hippel Lindau (VHL) protein] lead to tumor development. In mice, depletion of Vhlh in pancreatic ß-cells causes perturbed glucose homeostasis, but the role of this gene in other pancreatic cells is poorly understood. To investigate the function of VHL/HIF pathway in pancreatic cells, we inactivated Vhlh in the pancreatic epithelium as well as in the endocrine and exocrine lineages. Our results show that embryonic depletion of Vhlh within the pancreatic epithelium causes postnatal lethality due to severe hypoglycemia. The hypoglycemia is recapitulated in mice with endocrine-specific removal of Vhlh, while animals with loss of Vhlh predominantly in the exocrine compartment survive to adulthood with no overt defects in glucose metabolism. Mice with hypoglycemia display diminished insulin release in response to elevated glucose. Significantly, the glucagon response is impaired both in vivo (circulating glucagon levels) as well as in an in vitro secretion assay in isolated islets. Hypoxia also impairs glucagon secretion in a glucagon-expressing cell line in culture. Our results reveal a novel role for the hypoxia/HIF pathway in islet hormone secretion and maintenance of the fine balance that allows for the establishment of normoglycemia. 相似文献
84.
Salomé C. Vilchez Larrea Mariana Schlesinger María L. Kevorkian Mirtha M. Flawiá Guillermo D. Alonso Silvia H. Fernández Villamil 《PloS one》2013,8(6)
Trypanosoma cruzi, etiological agent of Chagas’ disease, has a complex life cycle which involves the invasion of mammalian host cells, differentiation and intracellular replication. Here we report the first insights into the biological role of a poly(ADP-ribose) glycohydrolase in a trypanosomatid (TcPARG). In silico analysis of the TcPARG gene pointed out the conservation of key residues involved in the catalytic process and, by Western blot, we demonstrated that it is expressed in a life stage-dependant manner. Indirect immunofluorescence assays and electron microscopy using an anti-TcPARG antibody showed that this enzyme is localized in the nucleus independently of the presence of DNA damage or cell cycle stage. The addition of poly(ADP-ribose) glycohydrolase inhibitors ADP-HPD (adenosine diphosphate (hydroxymethyl) pyrrolidinediol) or DEA (6,9-diamino-2-ethoxyacridine lactate monohydrate) to the culture media, both at a 1 µM concentration, reduced in vitro epimastigote growth by 35% and 37% respectively, when compared to control cultures. We also showed that ADP-HPD 1 µM can lead to an alteration in the progression of the cell cycle in hydroxyurea synchronized cultures of T. cruzi epimastigotes. Outstandingly, here we demonstrate that the lack of poly(ADP-ribose) glycohydrolase activity in Vero and A549 host cells, achieved by chemical inhibition or iRNA, produces the reduction of the percentage of infected cells as well as the number of amastigotes per cell and trypomastigotes released, leading to a nearly complete abrogation of the infection process. We conclude that both, T. cruzi and the host, poly(ADP-ribose) glycohydrolase activities are important players in the life cycle of Trypanosoma cruzi, emerging as a promising therapeutic target for the treatment of Chagas’ disease. 相似文献
85.
Sylvie Cablé Michèle Kedinger Michel Dauça 《Differentiation; research in biological diversity》1993,54(2):99-108
Abstract. The development of peroxisomes and expression of their enzymes were investigated in differentiating intestinal epithelial cells during their migration along the crypt-villus axis. Sequential cell populations harvested by a low-temperature method were identified by microscopy, determination of alkaline phosphatase and sucrase activities and incorporation of [3 H]-thymidine into DNA. Ultrastructural cytochemistry after staining for catalase activity, revealed the presence of peroxisomes in undifferentiated stem cells located in the crypt region. Morphometry indicated that the number of these organelles increased as intestinal epithelial cells differentiate. Catalase activity was higher in the crypt cells than in the mature enterocytes harvested from villus tips. On the other hand, an increasing gradient of activity was observed from crypts to villus tips for peroxisomal oxidases, i.e. fatty acyl coA oxidase, D-amino acid oxidase and polyamine oxidase. These findings indicate that biogenesis of peroxisomes occurs during migration of intestinal epithelial cells along the crypt-villus axis and that peroxisomal oxidases contribute substantially to the biochemical maturation of enterocytes. 相似文献
86.
Three different fluorochrome and specific counterstain combination (DAPI/AMD, DA/DAPI and CMA/DA) treatments were applied to the chromosomes of four Microtidae (Rodentia) species. The results complete the data obtained in our previous paper (Burgos, M., Jiménez, R., & Dìaz de la Guardia, R., Genome 30:540–546, 1988) and prove that the changes in the constitutive heterochromatin in the evolution of the karyotypes of these species are not only due to gain or loss of heterochromatin, but are qualitative with respect to their nucleotide composition, repeated base pair organization or DNA-protein complex modification. These variations lead to the differential response to the fluorescence dye combinations used. 相似文献
87.
Silver nitrate stains the intercellular junctions of the endothelium and other cytoplasmic or membrane components. Two protocols are described for the silver staining of rat carotid endothelium that exclude the use of pressurized fixatives and simplify the technique previously described for rat aorta. The entire surface of the carotid endothelium was examined and several parameters (stigmata, granularity, clustering of anionic sites, transversal lines, weakening of silver lines and leukocyte adhesion) were evaluated. We studied the pattern of silver staining in two situations: (1) endothelial activation and (2) neurogenic inflammation. Endothelial activation was produced by the intravenous administration of a proinflammatory albumin or polyinosinic acid. Both products cause a marked increase in leukocyte adhesion concomitant with a decrease in argyrophilia and a weakness or loss of silver lines. Neurogenic inflammation, which is mediated by substances released from sensory nerves, was induced by the intravenous administration of substance P or capsaicin. Both stimuli produced an increase in argyrophilia and weakness or loss of silver lines. Substance P caused a clustering of anionic sites, whereas this phenomenon was more discrete with capsaicin. Nearly 80% of all examined rats (controls and inflammatory stimuli treated) showed endothelial membrane disruptions formed by clusters of cells often in the shape of streaks aligned with the long axis of the vessel. The detection of these discontinuities is important, as loss of endothelial integrity is central in the initiation of pathological events. 相似文献
88.
G. N. Reiner L. Delgado-Marín N. Olguín S. Sánchez-Redondo M. Sánchez-Borzone E. Rodríguez-Farré C. Suñol D. A. García 《Cell biochemistry and biophysics》2013,67(2):515-525
Phenol compounds, such as propofol and thymol, have been shown to act on the GABAA receptor through interaction with specific sites of this receptor. In addition, considering the high lipophilicity of phenols, it is possible that their pharmacological activity may also be the result of the interaction of phenol molecules with the surrounding lipid molecules, modulating the supramolecular organization of the receptor environment. Thus, in the present study, we study the pharmacological activity of some propofol- and thymol-related phenols on the native GABAA receptor using primary cultures of cortical neurons and investigate the effects of these compounds on the micro viscosity of artificial membranes by means of fluorescence anisotropy. The phenol compounds analyzed in this article are carvacrol, chlorothymol, and eugenol. All compounds were able to enhance the binding of [3H]flunitrazepam with EC50 values in the micromolar range and to increase the GABA-evoked Cl? influx in a concentration-dependent manner, both effects being inhibited by the competitive GABAA antagonist bicuculline. These results strongly suggest that the phenols studied are positive allosteric modulators of this receptor. Chlorothymol showed a bell-type effect, reducing its positive effect at concentrations >100 μM. The concentrations necessary to induce positive allosteric modulation of GABAA receptor were not cytotoxic. Although all compounds were able to decrease the micro viscosity of artificial membranes, chlorothymol displayed a larger effect which could explain its effects on [3H]flunitrazepam binding and on cell viability at high concentrations. Finally, it is suggested that these compounds may exert depressant activity on the central nervous system and potentiate the effects of general anesthetics. 相似文献
89.
Laura Miralles Santiago Lens Antonio Rodríguez-Folgar Manuel Carrillo Vidal Martín Bjarni Mikkelsen Eva Garcia-Vazquez 《PloS one》2013,8(8)
Visual species identification of cetacean strandings is difficult, especially when dead specimens are degraded and/or species are morphologically similar. The two recognised pilot whale species (Globicephala melas and Globicephala macrorhynchus) are sympatric in the North Atlantic Ocean. These species are very similar in external appearance and their morphometric characteristics partially overlap; thus visual identification is not always reliable. Genetic species identification ensures correct identification of specimens. Here we have employed one mitochondrial (D-Loop region) and eight nuclear loci (microsatellites) as genetic markers to identify six stranded pilot whales found in Galicia (Northwest Spain), one of them of ambiguous phenotype. DNA analyses yielded positive amplification of all loci and enabled species identification. Nuclear microsatellite DNA genotypes revealed mixed ancestry for one individual, identified as a post-F1 interspecific hybrid employing two different Bayesian methods. From the mitochondrial sequence the maternal species was Globicephala melas. This is the first hybrid documented between Globicephala melas and G. macrorhynchus, and the first post-F1 hybrid genetically identified between cetaceans, revealing interspecific genetic introgression in marine mammals. We propose to add nuclear loci to genetic databases for cetacean species identification in order to detect hybrid individuals. 相似文献
90.
Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect. 相似文献