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51.
Rameshwar Sharma Enrique López-Juez Akira Nagatani Masaki Furuya 《The Plant journal : for cell and molecular biology》1993,4(6):1035-1042
The contents of spectrophotometrically measurable phytochrome A (PhyA) and phytochrome B (PhyB) and the corresponding immunochemically detectable apoproteins (PHYA and PHYB) were examined in dark- and light-grown tissues of the aurea mutant of tomato and its wild-type (WT). The amount of PHYA in etiolated aurea seedlings was found to be about 20% of that in the WT; this PHYA showed no photoreversible changes in absorbance, no downregulation of the level of PHYA in light-grown seedlings, and no differential proteolysis of Pr and Pfr species in vitro which was seen in the case of the WT. By contrast, the amount of PHYB in aurea seedlings was not significantly different from that in WT seedlings. Phytochrome isolated from green leaves of the aurea mutant and purified by ion-exchange chromatography showed a red/far-red reversible spectral change, and its elution profile during chromatography was essentially similar to that of PHYB. The results indicate that aurea is a mutant that is deficient in photoactive PhyA at the etiolated stage, when it contains a spectrally inactive PHYA. However, the mutant contains spectrally active PhyB in its green tissue as does the WT. 相似文献
52.
Douglas Maciel Reisla Oliveira Paulo Enrique Cardoso Peixoto 《Ethology : formerly Zeitschrift fur Tierpsychologie》2023,129(2):99-106
Sexually selected traits, such as male weapons, are highly variable in shape and size across species. However, little is known about the mechanisms that may govern this variation. Because males with greater investment in weapon size tend to win more fights, but also pay higher costs related to weapon development and maintenance, larger weapons should be expected only in species in which victory in male–male fights generate reproductive benefits that outweigh investment costs. Here, we hypothesized that the reproductive characteristics that increase the chances of winners to access females or to fertilize eggs will favor the evolution of larger weapons. To evaluate this hypothesis, we conducted a meta-analysis using arthropods as model organisms. To measure investment in weapon size, we gathered both Pearson correlation coefficient and the standardized (but non centralized) slope values for the relationship between weapon size and body size. We found that none of the reproductive characteristics we investigated was related to male weapon size. Thus, it seems that greater certainty of accessing a female or fertilizing female eggs with a victory does not modulate the investment in male weapon size. Perhaps the cost–benefit ratio between weapon size investment and reproductive success is not the main factor driving the variation in weapon size. 相似文献
53.
The immunogenicity of recombinant interleukin-2 (rIL-2, EuroCetus, Amsterdam, Netherlands) was studied in seventy-six patients receiving different subcutaneous immunotherapy regimens. Patients presented with progressive metastatic renal cell carcinoma, malignant melanoma, colorectal cancer, B-cell lymphoma, and Hodgkin's disease. An enzyme immunoassay (EIA) was employed to screen patients for development of non-neutralizing antibodies against rIL-2, antibody specificity was confirmed by a standard Western blot. Neutralizing serum activity against rIL-2 was detected using a standard CTLL mouse proliferation assay. Additionally, serum levels of soluble interleukin-2 receptors and lymphocyte subsets expressing the CD56 natural killer (NK) associated antigen were measured.In a proportion of approximately 35% to 90% of the patients treated, non-neutralizing antibodies against rIL-2 could be detected after all treatment courses were evaluated. Antibodies were of the IgG, IgM, IgA and IgD subtypes. None of the 76 patients exhibited serum neutralizing activity after one treatment course. Five patients exhibited neutralizing anti-rIL-2 serum activity after two or more treatment courses of systemic rIL-2. In three of these patients, antibodies neutralized both recombinant and natural IL-2. Patients developing neutralizing anti-rIL-2 antibodies, exhibited significantly lower serum sIL-2 receptor levels upon the emergence of serum neutralizing activity than patients without antibody. Additionally, NK cell associated CD56 positivity was significantly lower in patients who exhibited neutralizing anti-rIL-2 serum activity than in patients who did not. A significant decrease in levels of soluble IL-2 receptors and CD56 NK cell positivity was observed, when comparing values prior to and after onset of serum neutralizing activity against rIL-2. However, while emergence of neutralizing antibodies to rIL-2 diminished rIL-2 induced biological activation, it did not coincide with abrogation of treatment response.Abbreviations rIL-2
recombinant interleukin-2
- EIA
enzyme immuno assay
- rIFN-2
recombinant interferon- 2 相似文献
54.
Soil protists are increasingly studied due to a release from previous methodological constraints and the acknowledgement of their immense diversity and functional importance in ecosystems. However, these studies often lack sufficient depth in knowledge, which is visible in the form of falsely used terms and false- or over-interpreted data with conclusions that cannot be drawn from the data obtained. As we welcome that also non-experts include protists in their still mostly bacterial and/or fungal-focused studies, our aim here is to help avoid some common errors. We provide suggestions for current terms to use when working on soil protists, like protist instead of protozoa, predator instead of grazer, microorganisms rather than microflora and other terms to be used to describe the prey spectrum of protists. We then highlight some dos and don'ts in soil protist ecology including challenges related to interpreting 18S rRNA gene amplicon sequencing data. We caution against the use of standard bioinformatic settings optimized for bacteria and the uncritical reliance on incomplete and partly erroneous reference databases. We also show why causal inferences cannot be drawn from sequence-based correlation analyses or any sampling/monitoring, study in the field without thorough experimental confirmation and sound understanding of the biology of taxa. Together, we envision this work to help non-experts to more easily include protists in their soil ecology analyses and obtain more reliable interpretations from their protist data and other biodiversity data that, in the end, will contribute to a better understanding of soil ecology. 相似文献
55.
A. Townsend Peterson Enrique Martínez-Meyer† Constantino González-Salazar† 《Diversity & distributions》2004,10(4):237-246
Understanding historical distributions of species and evolving lineages has been a topic of considerable interest, yet methods used to date have not provided detailed, quantitative distributional hypotheses. Here, we present a technique based on models of species’ ecological niches and Pleistocene climate reconstructions that provides such hypotheses, providing the example of reconstructions for the Aphelocoma jays. We demonstrate in general a greater degree than expected of stability in jay species’ distributional areas back through at least the most recent glaciation event, and that existing patterns of genetic differentiation may date to before the Late Pleistocene glaciations. More generally, the method offers the potential for reconstructing historical distributions of species or lineages, and providing a detailed geographic framework for addressing many biogeographic and systematic questions. 相似文献
56.
Sílvia Bronsoms Josep Villanueva Francesc Canals Enrique Querol Francesc X Aviles 《European journal of biochemistry》2003,270(17):3641-3650
Protein folding can be modulated in vivo by many factors. While chaperones act as folding catalysts and show broad substrate specificity, some pro-peptides specifically facilitate the folding of the mature protein to which they are bound. Potato carboxypeptidase inhibitor (PCI), a 39-residue protein carboxypeptidase inhibitor, is synthesized in vivo as a precursor protein that includes a 27-residue N-terminal and a seven-residue C-terminal pro-regions. In this work the disulfide-coupled folding of mature PCI in vitro has been compared with that of the same protein extended with either the N-terminal pro-sequence (ProNtPCI) or both N- and C-terminal pro-sequences (ProPCI), and also with the N-terminal pro-sequence in trans (ProNt + PCI). No significant differences can be observed in the folding kinetics or efficiencies of all these molecules. In addition, in vivo folding studies in Escherichia coli have been performed using wild-type PCI and three PCI mutant forms with and without the N-terminal pro-sequence, the mutations had been previously reported to affect folding of the PCI mature form. The extent to which the 'native-like' form was secreted to the media by each construction was not affected by the presence of the N-terminal pro-sequence. These results indicate that PCI does not depend on the N-terminal pro-sequence for its folding in both, in vitro and in vivo in E. coli. However, structural analysis by spectroscopy, hydrogen exchange and limited proteolysis by mass spectrometry, indicate the capability of such N-terminal pro-sequence to fold within the precursor form. 相似文献
57.
Leirla Salazar Hafida Fsihi Edda de Rossi Giovanna Riccardi Carmen Rios Stewart T. Cole Howard E. Takiff 《Molecular microbiology》1996,20(2):283-293
The genus Mycobacterium is composed of species with widely differing growth rates ranging from approximately three hours in Mycobacterium smegmatis to two weeks in Mycobacterium leprae. As DNA replication is coupled to cell duplication, it may be regulated by common mechanisms. The chromosomal regions surrounding the origins of DNA replication from M. smegmatis, M. tuberculosis, and M. leprae have been sequenced, and show very few differences. The gene order, rnpA-rpmH-dnaA-dnaN-recF-orf-gyrB-gyrA, is the same as in other Gram-positive organisms. Although the general organization in M. smegmatis is very similar to that of Streptomyces spp., a closely related genus, M. tuberculosis and M. leprae differ as they lack an open reading frame, between dnaN and recF, which is similar to the gnd gene of Escherichia coli. Within the three mycobacterial species, there is extensive sequence conservation in the intergenic regions flanking dnaA, but more variation from the consensus DnaA box sequence was seen than in other bacteria. By means of subcloning experiments, the putative chromosomal origin of replication of M. smegmatis, containing the dnaA-dnaN region, was shown to promote autonomous replication in M. smegmatis, unlike the corresponding regions from M. tuberculosis or M. leprae. 相似文献
58.
Michael J. Seckl Richard H. Newman Paul S. Freemont Enrique Rozengurt 《Journal of cellular physiology》1995,163(1):87-95
The substance P (SP) analogues [DArg1, DPhe5, DTrp7,9, Leu11] SP (AntD) and [Arg6, DTrp7,9, MePhe8] SP (6–11) (AntG) inhibit the action of many different neuropeptides including SP. These analogues might be useful in the treatment of small cell lung cancer but their mechanism of action is unclear. Here, we analyzed the effect of AntD and AntG on neuropeptide vs. guanosine 5′-3-O-(thio) triphosphate (GTPγS) stimulated inositol phosphate generation in permeabilized Swiss 3T3 cells. AntD inhibited vasopressin and bombesin stimulated inositol phosphate formation (IC50 of 0.75 μM and 2 μM, respectively). Similarly, AntG inhibited vasopressin-stimulated inositol phosphate generation with an IC50 of 1 μM. Strikingly, neither AntD up to 10 μM nor AntG up to 20 μM was able to inhibit GTPγS-stimulated inositol phosphate generation. Dose-response curves of neuropeptide-induced inositol phosphate generation were dramatically displaced to the right by either 10 μM AntD or 20 μM AntG. However, neither antagonist affected the dose response of GTPγS-stimulated inositol phosphate generation. Furthermore, 20 μM AntD had no effect on AIF?4-induced inositol phosphates in COS-1 cells transfected with Gαq. AntD inhibited [3H]vasopressin binding competitively in intact Swiss 3T3 cells and both AntD and AntG inhibited [3H]vasopressin binding in Swiss 3T3 and rat liver membranes. Scatchard analysis revealed that AntD inhibited vasopressin binding by reducing receptor affinity without affecting receptor number in both intact and membrane preparations of Swiss 3T3 cells. The results strongly suggest that SP analogues AntD and AntG block the action of the Ca2+ mobilizing neuropeptides at the receptor level, rather than inhibiting G protein-stimulated inositol phosphate production. © 1995 Wiley-Liss, Inc. 相似文献
59.
Abstract: Different neurotransmitter receptor agonists [carbachol, serotonin, noradrenaline, histamine, endothelin-1, and trans -(1 S ,3 R )-aminocyclopentyl-1,3-dicarboxylic acid ( trans -ACPD)], known as stimuli of phospholipase C in brain tissue, were tested for phospholipase D stimulation in [32 P]Pi -prelabeled rat brain cortical and hippocampal slices. The accumulation of [32 P]phosphatidylethanol was measured as an index of phospholipase D-catalyzed transphosphatidylation in the presence of ethanol. Among the six neurotransmitter receptor agonists tested, only noradrenaline, histamine, endothelin-1, and trans -ACPD stimulated phospholipase D in hippocampus and cortex, an effect that was strictly dependent of the presence of millimolar extracellular calcium concentrations. The effect of histamine (EC50 18 µ M ) was inhibited by the H1 receptor antagonist mepyramine with a K i constant of 0.7 n M and was resistant to H2 and H3 receptor antagonists (ranitidine and tioperamide, respectively). Endothelin-1-stimulated phospholipase D (EC50 44 n M ) was not blocked by BQ-123, a specific antagonist of the ETA receptor. Endothelin-3 and the specific ETB receptor agonist safarotoxin 6c were also able to stimulate phospholipase D with efficacies similar to that of endothelin-1, and EC50 values of 16 and 3 n M , respectively. These results show that histamine and endothelin-1 stimulate phospholipase D in rat brain through H1 and ETB receptors, respectively. 相似文献
60.
Jesús Mateo Enrique Castro Jean Zwiller Dominique Aunis M. T. Miras-Portugal 《Journal of neurochemistry》1995,64(1):77-84
Abstract: We investigated the effect of the adenosine receptor agonist 5'-( N -ethylcarboxamido)adenosine (NECA) in catecholamine secretion from adrenal chromaffin cells that exhibit only the A2b subtype adenosine receptor. NECA reduced catecholamine release evoked by the nicotinic agonist 1,1-dimethyl-4-phenylpiperazinium (DMPP) in a time-dependent manner. Inhibition reached 25% after 30–40-min exposure to NECA. This effect on DMPP-evoked catecholamine secretion was mirrored by a similar (27.7 ± 3.3%), slowly developing inhibition of [Ca2+ ]i transients induced by DMPP that peaked at 30-min preincubation with NECA. The capacity of the chromaffin cells to buffer Ca2+ load was not affected by the treatment with NECA. Short-term treatment with NECA failed both to modify [Ca2+ ]i levels and to increase endogenous diacylglycerol production, showing that NECA does not activate the intracellular Ca2+ /protein kinase C signaling pathway. The inhibitory effects of NECA were accompanied by a 30% increase of protein phosphatase activity in chromaffin cell cytosol. We suggest that dephosphorylation of a protein involved in DMPP-evoked Ca2+ influx pathway (e.g., L-type Ca2+ channels) could be the mechanism of the inhibitory action of adenosine receptor stimulation on catecholamine secretion from adrenal chromaffin cells. 相似文献