首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
We studied morphological relationships within three guilds of gerbillid rodents in Israel. We found a nonrandom pattern of overdispersed means (community-wide character displacement) for upper incisor widths among the species in these three guilds. Upper tooth-row lengths, condylo-basal skull lengths, and tooth-row surfaces displayed similar patterns. We also studied seed-size selection by two well-studied gerbil species, which have previously been found to compete, in order to test whether specializing on husking seeds of different sizes as a mechanism of coexistence may underlie the morphological patterns. The seed-size selection experiments took place in two large aviaries with artificial lighting simulating full-moon nights, which is when predation risk is perceived as high. Seeds of different sizes (commercial seeds in one experiment and husked wheat particles in the other) mixed with sand were offered in trays. The larger Gerbillus pyramidum took significantly larger commercial seeds and marginally larger wheat particles than the smaller Gerbillus allenbyi. The patterns attest to ecomorphological convergence at the guild level; we previously demonstrated size structuring in several North American heteromyid rodent guilds, and we now report similar size structuring among Israeli gerbillid guilds. The occurrence of convergent community structure strongly indicates general rules governing ecological communities or guilds.  相似文献   

4.
The rat broncho-alveolar macrophages, subjected to gamma-irradiation, were incubated for 4 hours with irradiated (4 Gy) thymocytes. Following the total 24 hour incubation, some morphological features of macrophages were revealed in addition to their influence on survival, autologous rosetting and mitotic index of intact thymocytes. The increase in macrophage spreading was shown which was dose-dependent in the 1 to 4 Gy scale. Enhanced viability of thymocytes was revealed in the presence of macrophages irradiated at the dose of 1-2 Gy. Addition of 24 hour cultures of intact or irradiated macrophages elicited a significant decrease in rosette-forming capacity among thymocytes. Gamma-irradiation of 2 to 4 Gy inhibited the ability of macrophages to suppress the mitotic activity of thymic cells. A possibility of postradiational modification of some specific functions and properties of macrophages, including their thymotropic effects, is discussed.  相似文献   

5.
The lung responds to a variety of insults in a remarkably consistent fashion but with inconsistent outcomes that vary from complete resolution and return to normal to the destruction of normal architecture and progressive fibrosis. Increasing evidence indicates that diffuse lung disease results from an imbalance between the pro-inflammatory and anti-inflammatory mechanisms, with a persistent imbalance that favors pro-inflammatory mediators dictating the development of chronic diffuse lung disease. This review focuses on the mediators that influence this imbalance.  相似文献   

6.
Asthma is a leading cause of morbidity and mortality among children worldwide, as is respiratory syncytial virus (RSV). This report reviews controlled retrospective and prospective studies conducted to investigate whether there is an association between RSV bronchiolitis in infancy and subsequent development of reactive airway disease or allergic sensitization. Findings indicate that such a link to bronchial obstructive symptoms does exist and is strongest for children who experienced severe RSV illness that requires hospitalization. However, it is not yet clear what roles genetic predisposition and environmental or other risk factors may play in the interaction between RSV bronchiolitis and reactive airway disease or allergic sensitization. Randomized, prospective studies utilizing an intervention against RSV, such as a passive immunoprophylactic agent, may determine whether preventing RSV bronchiolitis reduces the incidence of asthma.  相似文献   

7.
We present a study of the hemolymph vascular system of the marbled crayfish, Procambarus fallax f. virginalis, the only crayfish species known to be parthenogenetic. To identify potential evolutionary patterns, we compared data from a total of 48 specimens of P. fallax with 22 specimens of Orconectes limosus. Visualizations (2D and 3D) were carried out using a combination of classical and modern morphological techniques. Our data were compared to the existing literature.Like all Decapoda, both P. fallax and O. limosus have a hemolymph vascular system, consisting of a globular heart with seven off-branching arteries. We were able to visualize in detail the heart of crayfish for the first time, i.e., the myocard with its clusters of muscles running through the lumen of the heart, the valves and flaps of ostia and arteries. Furthermore, the branching patterns of the seven artery systems were analyzed. Anatomical structures identified to be consistent in all specimens of both species were combined as ground pattern of hemolymph vascular system features for Astacida.  相似文献   

8.
Cyclic nucleotide metabolism and reactive oxygen production by macrophages   总被引:2,自引:0,他引:2  
The production of reactive oxygen species by elicited rat peritoneal macrophages was assessed by in vitro measurement of chemiluminescence in the presence of luminol. The divalent ion ionophore A23187 stimulated the production of reactive oxygen species. This action was inhibited by monobutyryl and dibutyryl derivatives of cyclic AMP but was not affected by derivates of cyclic GMP. Cyclic AMP and cyclic GMP concentrations increased rapidly in macrophages exposed to A23187 or zymosan. Indomethacin (20 μmol/1) inhibited the increase in cyclic AMP concentration but not the increase in cyclic GMP concentration. Neither A23187 nor zymosan stimulated adenylate cyclase activity in broken cell preparations of macrophages. The observations are consistent with the hypothesis that PGE produced by macrophages after phagocytotic stimuli may inhibit certain macrophage functions and perform a regulatory role in these cells. This action of PGE may be mediated by cyclic AMP.  相似文献   

9.
We demonstrated that the production of reactive oxygen species (ROS) by U937 macrophage-like cells was suppressed upon infection with a wild type Legionella pneumophila strain, whereas such suppression was not observed in the case of infection with intracellular growth-deficient mutants. This was supported not only by measuring ROS released into the supernatants of cell cultures by chemiluminescence assaying but also by detecting intracellular ROS with a fluorescent probe, 2-[6-(4'-amino)phenoxy-3H-xanthen-3-on-9-yl]benzoic acid (APF), under a confocal laser scanning microscope. Furthermore, more than 60% of the phagosomes containing intracellular growth-deficient mutants were colocalized with p47(phox), which is the cytosolic subunit of NADPH oxidase, consistently throughout the observation period in an early stage of bacterial infection. In contrast, the colocalization of p47(phox) was suppressed after infection with the wild type strain. These results suggest that the interference with ROS production by U937 cells infected with wild type L. pneumophila is due to a failure of NADPH oxidase activation through inhibition of p47(phox) recruitment to phagosomes harboring bacteria. The results also highlighted the difference in the nature of phagosomes between ones harboring the wild type and ones the intracellular growth-deficient strains.  相似文献   

10.
Spontaneous autoimmunity and involution of the lymphoid system   总被引:1,自引:0,他引:1  
  相似文献   

11.
12.
Giant cells containing S-100 protein of the lymphoid tissues in the guinea pig were studied by immunohistochemistry using S-100 antiserum. S-100-immunoreactive giant cells were dendritic in shape, contained one or two irregular-shaped, euchromatic nuclei, phagosomes of various diameter, numerous mitochondria and microfilaments in the perikaryon, and extended cell processes free of cell organelles. These cells predominantly lined the superficial cortex facing the subcapsular sinus, were less numerously scattered in the medulla of lymph nodes and located at the marginal zone of the spleen. They also stained with S-100 alpha monoclonal antiserum and showed active phagocytosis for aldehyde-fixed red cells or colloidal carbon in the popliteal lymph node and spleen. S-100-immunoreactive giant cells also appeared in the corticomedullary zone of the thymus and in the interfollicular area of the Peyer's patches of the gut. Small sinus macrophages, which exhibited active phagocytosis for colloidal carbon but were less active for red cells in the popliteal lymph node and spleen, were not stained with S-100 antiserum. These findings indicate that S-100-immunoreactive giant cells of the lymph node and spleen are a subpopulation of macrophages different from S-100-negative cells of the small type.  相似文献   

13.
BACKGROUND AND AIMS: Hybridization is an important evolutionary phenomenon, and therefore a detailed understanding of the dynamics of interspecific gene flow and resulting morphological and genetic patterns is of widespread interest. Here hybridization between the polyploids Cardamine pratensis and C. raphanifolia at four localities is explored. Using different types of data, the aim is to provide simultaneous and direct comparisons between genotype and phenotype variation patterns in the studied hybrid populations. METHODS: Evidence of hybridization has been gathered from morphology, molecular markers (amplified fragment length polymorphism and chloroplast DNA sequences), pollen viability, karyology and nuclear DNA content. KEY RESULTS: All data support extensive gene flow occurring in the hybrid populations. A wide range of morphological and genetic variation is observed, which includes both parental and intermediate types. Unbalanced pollen fertility and several ploidy levels are recorded. CONCLUSIONS: Incongruence reported between genotype and phenotype suggests that parental phenotypes are affected by introgression, and intermediate hybrid phenotypes can be genetically closer to one of the parents. Thus, it is evident that morphology, when used alone, can be misleading for interpreting hybridization, and critical evaluation of other data is needed.  相似文献   

14.
This study focused on three species that occur disjunctly between western North America and the Mediterranean region of southern Europe, northern Africa, and western Asia, forming the so-called Madrean-Tethyan distribution pattern. Quantitative morphological characters were measured in New and Old World plants to find any subtle phenotypic differentiation between the disjunct populations. Sequences from the nuclear ribosomal internal transcribed spacer region were obtained from the same populations to assess differentiation at the molecular level and to compare molecular diversity with patterns of morphological similarity among plants. Little or no morphological differentiation existed between New and Old World plants in any of the species, but internal transcribed spacer (ITS) sequences revealed some phylogeographic structure. Patterns of morphological similarity in all three species were incongruent with phylogeographic structure revealed by sequence data. New World populations were more variable than Old World populations at the molecular level in the three species. Despite some evidence for differentiation between disjunct plants, no plausible mutation rate would date the divergence at ≥20 million years ago (MYA), as implied by the Madrean-Tethyan hypothesis. Recent long-distance dispersal is a more likely explanation for intercontinental disjunctions in these species.  相似文献   

15.
The caecum has been studied at the light optic and electron microscopical levels. Amount of immune-competent cells and lymphoid nodules in the distal part of the mice caecum and in the human appendix vermiformis are essentially similar. It is possible to consider the distal (blindly closed) part of the caecum in the mice of the BALB/C line as a morphofunctional equivalent to the human appendix vermiformis and use it as an experimental model in studying diseases of the appendix.  相似文献   

16.
AbstractFerroptosis, a newly discovered iron-dependent cell death pathway, is characterized by lipid peroxidation and GSH depletion mediated by iron metabolism and is morphologically, biologically and genetically different from other programmed cell deaths. Besides, ferroptosis is usually found accompanied by inflammatory reactions. So far, it has been found participating in the development of many kinds of diseases. Macrophages are a group of immune cells that widely exist in our body for host defense and play an important role in tissue homeostasis by mediating inflammation and regulating iron, lipid and amino acid metabolisms through their unique functions like phagocytosis and efferocytosis, cytokines secretion and ROS production under different polarization. According to these common points in ferroptosis characteristics and macrophages functions, it’s obvious that there must be relationship between macrophages and ferroptosis. Therefore, our review aims at revealing the interaction between macrophages and ferroptosis concerning three metabolisms and integrating the application of certain relationship in curing diseases, mostly cancer. Finally, we also provide inspirations for further studies in therapy for some diseases by targeting certain resident macrophages in distinct tissues to regulate ferroptosis.Facts
  • Ferroptosis is considered as a newly discovered form characterized by its nonapoptotic and iron-dependent lipid hydroperoxide, concerning iron, lipid and amino acid metabolisms.
  • Ferroptosis has been widely found playing a crucial part in various diseases, including hepatic diseases, neurological diseases, cancer, etc.
  • Macrophages are phagocytic immune cells, widely existing and owning various functions such as phagocytosis and efferocytosis, cytokines secretion and ROS production.
  • Macrophages are proved to participate in mediating metabolisms and initiating immune reactions to maintain balance in our body.
  • Recent studies try to treat cancer by altering macrophages’ polarization which damages tumor microenvironment and induces ferroptosis of cancer cells.
Open questions
  • How do macrophages regulate ferroptosis of other tissue cells specifically?
  • Can we use the interaction between macrophages and ferroptosis in treating diseases other than cancer?
  • What can we do to treat diseases related to ferroptosis by targeting macrophages?
  • Is the use of the relationship between macrophages and ferroptosis more effective than other therapies when treating diseases?
Subject terms: Cell death and immune response, Cytokines, Cancer immunotherapy  相似文献   

17.
Hierarchical patterns inSilene sect.Sedoideae were investigated using random amplified polymorphic DNA (RAPD), nucleotide sequences of the internal transcribed spacer (ITS) regions of the 18S–28S nuclear ribosomal DNA, and discrete morphological characters. All data sets firmly supported the species recognized. The RAPD data offered the best resolution at the intraspecific level, supporting the current intraspecific classifications ofS. sedoides andS. integripetala. The ITS sequences and the morphological data gave poor resolution within species, and the three data sets disagreed about the relationships among species. The signal from the RAPD data was strongest and remained when the total data set was analysed. The three data sets all support an amphiploid origin ofS. aegaea, with the strongest evidence from the ITS sequences. Incongruences among data sets as well as merits and shortcomings of each are discussed. The robustness of the results can be evaluated using perturbations of data, i.e., bootstrap and jackknife of taxa and characters. These methods should not be taken as methods of statistical inference at the taxonomic level, because unbiased sampling appears impossible. RAPD data, however, come close to being suitable for statistical estimation of hierarchies at the genome level, but several methodological problems have to be solved.  相似文献   

18.
This paper explores two possible connections between the diagnostics for morphological and semantic markedness. One possibility, a positive correlation, predicts that if a grammatical feature is diagnosed as being morphologically marked then it should also be semantically marked. This possibility follows from the assumption that features are interpreted as restrictions on denotations. The second possibility, a negative correlation, predicts that if a grammatical feature is diagnosed as being morphologically marked then it should be semantically unmarked. This systematic inconsistency follows from the assumption that features are interpreted as augmenting functions. In our exploration of number marking, we find that the negative correlation is not only theoretically consistent with the semantic literature (in particular Link, in: Bartsch et al. (eds.) Semantics and contextual expressions, 1983), but it is also more consistent with the empirical landscape (as noted by Sauerland, in: Young and Zhou (eds.) Proceedings of Semantics and linguistic theory SALT XIII 2008). As a result, the morphological diagnostics lend support to the view that plural features are interpreted as augmenting functions.  相似文献   

19.
Summary Lysozyme has, until recently, been accepted as the only reliable immunohistochemical marker of benign and malignant histiocytes. Using this marker, very few lymphoreticular neoplasms of histiocytic origin are recognized and more recently -1-anti-trypsin has been shown to be a better marker of malignant histiocytes. By immunizing rabbits with highly purified human blood monocytes we have obtained an antiserum (S22) which stains histiocytes and neutrophils in paraffin sections with a high degree of specificity. Using this antiserum and antisera to lysozyme and -1-anti-trypsin we have stained paraffin sections of tissues containing reactive histiocytes, histiocytic proliferations, leukaemic infiltrates and lymphoreticular tumours of histiocytic and T-cell origin. Our results show that -1-anti-trypsin is the most reliable marker of malignant histiocytes but that the as yet uncharacterized antigen defined by S22 may offer a promising alternative.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号