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991.
Sulfite-oxidizing enzyme activities were analyzed in cell-free extracts of aerobically grown cells of Acidianus ambivalens, an extremely thermophilic and chemolithoautotrophic archaeon. In the membrane and cytoplasmic fractions, two distinct enzyme
activities were found. In the membrane fraction, a sulfite:acceptor oxidoreductase activity was found [530 mU (mg protein)–1; apparent K
m for sulfite, 3.6 mM]. In the cytoplasmic fraction the following enzyme activities were found and are indicative of an oxidative
adenylylsulfate pathway: adenylylsulfate reductase [138 mU (mg protein)–1], adenylylsulfate:phosphate adenyltransferase [“ADP sulfurylase”; 86 mU (mg protein)–1], adenylate kinase [650 mU (mg protein)–1], and rhodanese [thiosulfate sulfur transferase, 9.2 mU (mg protein)–1]. In addition, 5′,5′′′-P1,P4-di(adenosine-5′) tetraphosphate (Ap4A) synthase and Ap4A pyrophosphohydrolase activities were detected.
Received: 17 August 1998 / Accepted: 29 April 1999 相似文献
992.
Carla I. Tasca Luciana F. Cardoso Deusa Vendite Diogo O. Souza 《Neurochemical research》1999,24(8):1067-1074
Binding properties of the subtypes of adenosine A2 receptors in membrane preparations and the effects of adenosine receptor ligands on cAMP accumulation in slices from the optic tectum of neonatal chicks have been investigated. [3H]2-[4-(2-p-carboxyethyl)phenylamino]-5'-N-ethylcarboxaminoadenosine (CGS 21680), a selective ligand for adenosine A2a receptors, did not bind to optic tectal membranes, as observed with rat striatal membranes. CGS 21680 also did not induce cyclic AMP accumulation in optic tectum slices. However, 5'-N-ethylcarboxamidoadenosine (NECA), 2-chloro-adenosine or adenosine induced a 2.5- to 3-fold increase on cyclic AMP accumulation in this preparation. [3H]NECA binds to fresh non-washed-membranes obtained from optic tectum of chicks, displaying one population of binding sites, which can be displaced by NECA, 8-phenyltheophylline, 2-chloro-adenosine, but is not affected by CGS 21680. The estimated KD value was 400.90 ± 80.50 nM and the Bmax was estimated to be 2.51 ± 0.54 pmol/mg protein. Guanine nucleotides, which modulate G-proteins activity intracellularly, are also involved in the inhibition of glutamate responses by acting extracellularly. Moreover, we have previously reported that guanine nucleotides potentiate, while glutamate inhibits, adenosine-induced cyclic AMP accumulation in slices from optic tectum of chicks. However, the guanine nucleotides, GMP or GppNHp and the metabotropic glutamate receptors agonist, 1S,3R-ACPD did not alter the [3H]NECA binding observed in fresh non-washed-membranes. Therefore, the adenosine A2 receptor found in the optic tectum must be the adenosine A2b receptor which is available only in fresh membrane preparations, and its not modulated by guanine nucleotides or glutamate analogs. 相似文献
993.
Myrna G. Serrano Marta Campaner Gregory A. Buck Marta M.G. Teixeira Erney Plessmann Camargo 《FEMS microbiology letters》1999,176(1):241-246
A PCR-based method was adapted for the amplification of DNA from methanol-fixed smears of insects and plants parasitized by trypanosomatids. The PCR target was the multicopy spliced leader (SL) gene. Amplicons were hybridized with an oligonucleotide probe (SL3') specific for Phytomonas. The method has the advantage of dispensing with the cultivation of parasites, many of which are very fastidious or non-cultivable. The technique was applied to archival glass slides and to newly collected material. It proved to specific for Phytomonas spp., enabling their detection in plants and insects. Sequence comparison of the amplicons obtained revealed the existence of different strains/species of Phytomonas circulating among diseased palsms and fruit. 相似文献
994.
Maria de Fátima Silva Lopes Ana Lúcia Leitão J.J. Figueiredo Marques Manuel José Teixeira Carrondo Maria Teresa Barreto Crespo 《FEMS microbiology letters》1999,176(2):483-487
The hypothesis of a proteolytic involvement in the extracellular lipase processing of a strain of Lactobacillus plantarum was considered and tested, in vitro assays with acid proteases, cathepsin D and renin revealed that both did affect lipolytic activity positively. In vivo assays with growth in the presence of the protease inhibitors pepstatin, phenylmethylsulfonyl fluoride, transepoxysuccinyl-L-leucylamido-(4-guanidino)butane and ethylenediaminetetraacetic acid showed that ethylenediaminetetraacetic acid did affect the pattern of the proteins that possess lipolytic activity. Therefore, it is suggested that a metalloprotease is involved in the processing of the extracellular lipases of L. plantarum, although other proteases can also be important. 相似文献
995.
Andréa Baldasso-Zanon Andrew Oliveira Silva Nayara Franco Rafael V. Picon Guido Lenz Patrícia Luciana da Costa Lopez Eduardo C. Filippi-Chiela 《Journal of cellular biochemistry》2024,125(2):e30517
Colorectal cancer (CRC) is the third most common and deadliest cancer globally. Regimens using 5-fluorouracil (5FU) and Oxaliplatin (OXA) are the first-line treatment for CRC, but tumor recurrence is frequent. It is plausible to hypothesize that differential cellular responses are triggered after treatments depending on the genetic background of CRC cells and that the rational modulation of cell tolerance mechanisms like autophagy may reduce the regrowth of CRC cells. This study proposes investigating the cellular mechanisms triggered by CRC cells exposed to 5FU and OXA using a preclinical experimental design mimicking one cycle of the clinical regimen (i.e., 48 h of treatment repeated every 2 weeks). To test this, we treated CRC human cell lines HCT116 and HT29 with the 5FU and OXA, combined or not, for 48 h, followed by analysis for two additional weeks. Compared to single-drug treatments, the co-treatment reduced tumor cell regrowth, clonogenicity and stemness, phenotypes associated with tumor aggressiveness and poor prognosis in clinics. This effect was exerted by the induction of apoptosis and senescence only in the co-treatment. However, a week after treatment, cells that tolerated the treatment had high levels of autophagy features and restored the proliferative phenotype, resembling tumor recurrence. The pharmacologic suppression of early autophagy during its peak of occurrence, but not concomitant with chemotherapeutics, strongly reduced cell regrowth. Overall, our experimental model provides new insights into the cellular mechanisms that underlie the response and tolerance of CRC cells to 5FU and OXA, suggesting optimized, time-specific autophagy inhibition as a new avenue for improving the efficacy of current treatments. 相似文献
996.
G. Correia‐da‐Silva S.C. Bell J.H. Pringle N. Teixeira 《Molecular reproduction and development》1999,53(3):294-305
The uterus and the placenta synthesize insulin‐like growth factors (IGFs) and insulin‐like binding proteins (IGFBPs). These growth factors are implicated in processes of proliferation and differentiation that occur in the uterus. To determine the patterns of expression of IGFs during rat pregnancy we used in situ hybridization with digoxigenin labeled probes on uterus from day 7 to day 16 of pregnancy. In early gestation days (7–8) both IGF mRNAs showed similar tissue distribution with relative abundance in the stroma and circular muscle layer. On days 11 and 12 expression for IGF‐I mRNA was found in the mesometrial decidua and metrial gland and in the ectoplacental cone while clear expression of IGF‐II mRNA could only be found in the latter. On days 13 and 14, expression for IGF‐I mRNA could be detected in the mesometrial decidua and metrial gland but no expression was observed for IGF‐II mRNA. A gradient of IGF‐I mRNA expression could be observed in the placenta on day 16, with the trophoblastic cells of the basal zone expressing the signal with stronger intensity than in the labyrinthine zone. For IGF‐II mRNA the highest expression was associated with the labyrinthine zone. Endovascular trophoblast was positive for both mRNAs. The spatial and temporal patterns of expression suggests a role for IGFs in the process of decidualization as well as in the establishment, growth and differentiation of the various trophoblast cells of the placenta. Mol. Reprod. Dev. 53:294–305, 1999. © 1999 Wiley‐Liss, Inc. 相似文献
997.
Marlies Knipper Lika Gestwa Wouter‐Jan Ten Cate Jürgen Lautermann Heribert Brugger Hannes Maier Ulrike Zimmermann Karin Rohbock Iris Kpschall Barbara Wiechers Hans‐Peter Zenner 《Developmental neurobiology》1999,38(3):338-356
Analyzing the thyroid hromone (TH)‐dependent period of the inner ear, we observed that the presence of triiodothyronine (T3) between postnatal day 3 (P3) and P12 is sufficient for functional maturation of the auditory system. Within this short time period, an unusual transient TH‐dependent expression of nonneuronal neurotrophin receptors (NT‐R) trkB and p75NGFR was observed in correlation with neuronal and morphogenetic processes. The availability of thyroid hormone was revealed to be invariably correlated with (a) a transient expression of full‐length trkB in TRα1‐, TRα2‐ and TRβ1‐expressing hair cells concomitant to the segregation of afferent fibers and the synaptogenesis of efferent fibers; and (b) a transient expression of p75NGFR in TRα1‐ and TRβ1‐expressing great epithelia ridge cells in direct spatiotemporal correlation with the appearance of apoptotic cells and morphogenetic maturation of the organ. For the first time, these data suggest a TH dependency of the expression of neurotrophin receptors in nonneuronal cells. A potential role of these peculiar neurotrophin receptor expression for the conversion of the biological function of TH on innervation patterning and morphogenesis during the critical TH‐dependent period of the inner ear may be considered. © 1999 John Wiley & Sons, Inc. J Neurobiol 38: 338–356, 1999 相似文献
998.
A comparison of fecal steroid metabolite concentrations between harem and bachelor stallions in a free‐Ranging population of przewalski's horses (Equus ferus przewalskii)
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999.
Overcoming phylogenetic and geographic uncertainties to test for correlates of range size evolution in gymnophthalmid lizards
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Agustín Camacho Renato Recoder Mauro Teixeira Jr Tiana Kohlsdorf Miguel Trefaut Rodrigues Michael S. Y. Lee 《Ecography》2017,40(6):764-773
Patterns of range size evolution are important for developing an evolutionary biogeographical theory and supporting conservation actions. Determining those patterns is however hampered by multiple factors acting on range size and by our uncertainty with regard to species' phylogenetic relationships and geographic distribution. In addition, given the diversity of analytic approaches existing in the literature, there are concerns regarding whether different methods might lead to different patterns. Here, we addressed these uncertainties in order to test for correlations between the evolution of morphology (body size and shape) and range size. We studied lizards of the family Gymnophthalmidae, representing changes of an order of magnitude in body size and also two independent lineages with limb‐reduced (snake‐like) morphs. We used phylogenetic multivariate methods (pPCA) to control for allometric effects of body size over shape. Then, we performed multiple regressions under three approaches: ‘naive’ least squares, Bayesian comparative methods that accounted for uncertainties in trait optimization, tree topology and branch length, and a novel permutative procedure based on phylogenetic generalized least squares (pGLS) to assess the robustness of our relationships to uncertainties in the range sizes of the species studied. All approaches led to the same answer: only body size was related to range size. While bigger gymnophthalmids tend to have relatively large ranges, small species can have either small or large ones. Our results’ robustness to strong uncertainties in both phylogenetic relationships and range sizes shows there are opportunities for overcoming those problems and produce reliable patterns of range size evolution. However, interpretation of the processes driving patterns of range size evolution will still require advances in phylogenetic and taxonomic knowledge. We discuss the application of morphology–range size relationships to conservation planning in the light of existing uncertainties in the geographic knowledge of our studied species group and workarounds for data availability. 相似文献
1000.
Caroline de Souza Barros Valeria Garrido Vanessa Melchiades Rafaela Gomes Max Willian Lisboa Gomes Valeria Laneuville Teixeira Izabel Christina Nunes de Palmer Paixão 《Journal of applied phycology》2017,29(2):769-773
Studies with diterpenes from marine brown alga Canistrocarpus cervicornis showed the antiviral potential of the products from this alga in controlling the replication of HSV-1 and maintaining low cytotoxicity. Hence, the aim of this work was to evaluate the anti-herpetic efficacy of C. cervicornis extract ointment in BALB/c mice. To test the anti-herpetic efficacy in vivo, four groups of BALB/c mice (n?=?5) were used: 1—untreated, 2—extract ointment (2 % or 0.4 mg cm?2 dose?1), 3—Acyclovir cream (5 % or 1.0 mg cm?2 dose?1), and 4—ointment base. The right midflank of each mouse was clipped and depilated with a chemical depilatory. After 2 days, the skin area was scratched and inoculated with HSV-1. The ointments and cream were applied three times a day over a 16-day period, beginning 1 h after virus inoculation. The development of skin lesions was continuously monitored and scored. To evaluate the effect of C. cervicornis topical treatment on biochemical parameters and on body weight, two uninfected groups were formed: an untreated group and a group treated with ointment C. cervicornis extract (2 %). The signs of infection appeared from the second day after infection, while on the 10th day of the experiment, the ointment base and untreated groups had significantly more severe lesions than did the groups that were treated with extract (p?<?0.05) or acyclovir (p?<?0,01). The topical application of extract ointment did not change body weight, hepatic, or renal function suggesting that the extract has a low toxicity in this route of administration. These results suggest that the extract may be useful in reducing the severity of HSV-1 cutaneous lesions. 相似文献