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排序方式: 共有231条查询结果,搜索用时 262 毫秒
21.
Maria Helena Ferreira de Azevedo Tarcízio Antônio Rego de Paula Sérgio Luis Pinto da Matta Cláudio César Fonseca Eduardo Paulino da Costa Deiler Sampaio Costa Juliano Vogas Peixoto 《Animal reproduction science》2010
The intrinsic yield of spermatogenesis and supporting capacity of Sertoli cells are the desirable indicators of sperm production in a species. The objective of the present study was to quantify intrinsic yield and the Sertoli cell index in the spermatogenic process and estimate testicular sperm reserves by histological assessment of fragments obtained by testicular biopsy of five adult jaguars in captivity. The testicular fragments were fixed in 4% glutaric aldehyde, dehydrated at increasing alcohol concentrations, included into hydroxyethyl methacrylate, and were cut into 4 μm thickness. In the seminiferous epithelium of the jaguar, 9.2 primary spermatocytes in pre-leptotene were produced by “A” spermatogonia. During the meiotic divisions only 3.2 spermatids were produced by a primary spermatocyte. The general spermatogenic yield of the jaguar was about 23.4 cells and each Sertoli cell was able to maintain about 19.2 germ cells, 11 of them were round spermatids. In each seminiferous epithelium cycle about 166 million spermatozoa were produced by each gram of testicular tissue. In adult jaguars, the general spermatogenic yield was similar to the yield observed in pumas, greater than that observed for the domestic cat, but less compared to most domestic animals. 相似文献
22.
Rego FG Pedrosa FO Chubatsu LS Yates MG Wassem R Steffens MB Rigo LU Souza EM 《Canadian journal of microbiology》2006,52(12):1199-1207
The putative nifB promoter region of Herbaspirillum seropedicae contained two sequences homologous to NifA-binding site and a -24/-12 type promoter. A nifB::lacZ fusion was assayed in the backgrounds of both Escherichia coli and H. seropedicae. In E. coli, the expression of nifB::lacZ occurred only in the presence of functional rpoN and Klebsiella pneumoniae nifA genes. In addition, the integration host factor (IHF) stimulated the expression of the nifB::lacZ fusion in this background. In H. seropedicae, nifB expression occurred only in the absence of ammonium and under low levels of oxygen, and it was shown to be strictly dependent on NifA. DNA band shift experiments showed that purified K. pneumoniae RpoN and E. coli IHF proteins were capable of binding to the nifB promoter region, and in vivo dimethylsulfate footprinting showed that NifA binds to both NifA-binding sites. These results strongly suggest that the expression of the nifB promoter of H. seropedicae is dependent on the NifA and RpoN proteins and that the IHF protein stimulates NifA activation of nifB promoter. 相似文献
23.
Annalisa Bellu Miguel N. Bugalho Tiago Monteiro-Henriques José C. Costa Francisco C. Rego 《European Journal of Wildlife Research》2012,58(4):645-654
Large mammalian herbivores are keystone species in different ecosystems. To mediate the effects of large mammalian herbivores on ecosystems, it is crucial to understand their habitat selection pattern. At finer scales, herbivore patch selection depends strongly on plant community traits and therefore its understanding is constrained by patch definition criteria. Our aim was to assess which criteria for patch definition best explained use of meadows by wild, free-ranging, red deer (Cervus elaphus) in a study area in Northeast Portugal. We used two clustering criteria types based on floristic composition and gross forage classes, respectively. For the floristic criteria, phytosociological approach was used to classify plant communities, and its objectivity evaluated with a mathematical clustering of the floristic relevés. Cover of dominant plant species was tested as a proxy for the phytosociological method. For the gross forage classes, the graminoids/forbs ratio and the percentage cover of legumes were used. For assessing deer relative use of meadows we used faecal accumulation rates. Patches clustered according to floristic classification better explained selection of patches by deer. Plant community classifications based on phytosociology, or proxies of this, used for characterizing meadow patches resulted useful to understand herbivore selection pattern at fine scales and thus potentially suitable to assist wildlife management decisions. 相似文献
24.
Calabria G Dolgova O Rego C Castañeda LE Rezende EL Balanyà J Pascual M Sørensen JG Loeschcke V Santos M 《Journal of evolutionary biology》2012,25(4):691-700
Theory predicts that geographic variation in traits and genes associated with climatic adaptation may be initially driven by the correlated evolution of thermal preference and thermal sensitivity. This assumes that an organism's preferred body temperature corresponds with the thermal optimum in which performance is maximized; hence, shifts in thermal preferences affect the subsequent evolution of thermal-related traits. Drosophila subobscura evolved worldwide latitudinal clines in several traits including chromosome inversion frequencies, with some polymorphic inversions being apparently associated with thermal preference and thermal tolerance. Here we show that flies carrying the warm-climate chromosome arrangement O(3+4) have higher basal protein levels of Hsp70 than their cold-climate O(st) counterparts, but this difference disappears after heat hardening. O(3+4) carriers are also more heat tolerant, although it is difficult to conclude from our results that this is causally linked to their higher basal levels of Hsp70. The observed patterns are consistent with the thermal co-adaptation hypothesis and suggest that the interplay between behaviour and physiology underlies latitudinal and seasonal shifts in inversion frequencies. 相似文献
25.
Insulin neuroprotection against oxidative stress is mediated by Akt and GSK-3beta signaling pathways and changes in protein expression 总被引:1,自引:0,他引:1
Duarte AI Santos P Oliveira CR Santos MS Rego AC 《Biochimica et biophysica acta》2008,1783(6):994-1002
Previously we demonstrated that insulin protects against neuronal oxidative stress by restoring antioxidants and energy metabolism. In this study, we analysed how insulin influences insulin-(IR) and insulin growth factor-1 receptor (IGF-1R) intracellular signaling pathways after oxidative stress caused by ascorbate/Fe2+ in rat cortical neurons. Insulin prevented oxidative stress-induced decrease in tyrosine phosphorylation of IR and IGF-1R and Akt inactivation. Insulin also decreased the active form of glycogen synthase kinase-3beta (GSK-3beta) upon oxidation. Since phosphatidylinositol 3-kinase (PI-3K)/Akt-mediated inhibition of GSK-3beta may stimulate protein synthesis and decrease apoptosis, we analysed mRNA and protein expression of "candidate" proteins involved in antioxidant defense, glucose metabolism and apoptosis. Insulin prevented oxidative stress-induced increase in glutathione peroxidase-1 and decrease in hexokinase-II expression, supporting previous findings of changes in glutathione redox cycle and glycolysis. Moreover, insulin precluded Bcl-2 decrease and caspase-3 increased expression. Concordantly, insulin abolished caspase-3 activity and DNA fragmentation caused by oxidative stress. Thus, insulin-mediated activation of IR/IGF-1R stimulates PI-3K/Akt and inhibits GSK-3beta signaling pathways, modifying neuronal antioxidant defense-, glucose metabolism- and anti-apoptotic-associated protein synthesis. These and previous data implicate insulin as a promising neuroprotective agent against oxidative stress associated with neurodegenerative diseases. 相似文献
26.
Colonic Mucosal Proteome Signature Reveals Reduced Energy Metabolism and Protein Synthesis but Activated Autophagy during Anorexia‐Induced Malnutrition in Mice
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Séverine Nobis Najate Achamrah Alexis Goichon Clément L'Huillier Aline Morin Charlène Guérin Philippe Chan Jean Luc do Rego Jean Claude do Rego David Vaudry Pierre Déchelotte Liliana Belmonte Moïse Coëffier 《Proteomics》2018,18(15)
Anorexia nervosa is an eating disorder often associated with intestinal disorders. To explore the underlying mechanisms of these disorders, the colonic proteome was evaluated during activity‐based anorexia. Female C57Bl/6 mice were randomized into three groups: Control, Limited Food Access (LFA) and Activity‐Based Anorexia (ABA). LFA and ABA mice had a progressive limited access to food but only ABA mice had access to an activity wheel. On colonic mucosal protein extracts, a 2D PAGE‐based comparative proteomic analysis was then performed and differentially expressed proteins were identified by LC‐ESI‐MS/MS. Twenty‐seven nonredundant proteins that were differentially expressed between Control, LFA, and ABA groups were identified. ABA mice exhibited alteration of several mitochondrial proteins involved in energy metabolism such as dihydrolipoyl dehydrogenase and 3‐mercaptopyruvate sulfurtransferase. In addition, a downregulation of mammalian target of rapamycin (mTOR) pathway was observed leading, on the one hand, to the inhibition of protein synthesis, evaluated by puromycin incorporation and mediated by the increased phosphorylation of eukaryotic elongation factor 2, and on the other hand, to the activation of autophagy, assessed by the increase of the marker of autophagy, form LC3‐phosphatidylethanolamine conjugate/Cytosolic form of Microtubule‐associated protein 1A/1B light chain 3 (LC3II/LC3I) ratio. Colonic mucosal proteome is altered during ABA suggesting a downregulation of energy metabolism. A decrease of protein synthesis and an activation of autophagy were also observed mediated by mTOR pathway. 相似文献
27.
de Magalhães Lima K Machado Barbosa de Castro CM Fonsêca Nogueira Cambuim II Carvalhaes de Oliveira J Delgado M Sette de Melo Rego R 《Revista iberoamericana de micología》2008,25(1):45-49
Patients infected with human immunodeficiency virus (HIV) are a risk group for onychomycosis, fungal infections caused mainly by dermatophytes and yeast. However, non-dermatohytic moulds are becoming common agents for nail infections in this population of patients. We report four cases of onychomycosis caused by non-dermatophytic moulds (Aspergillus niger, Scytalidium hyalinum, Scytalidium dimidiatum and Fusarium solani) in patients infected with HIV from Recife, Pernambuco, Brazil. Onychomicosis by non-dermatophytic species in HIV-positive patients requires special attention in the clinical and the laboratory. A proper diagnosis is necessary to establish the specific and adequate treatment, preventing fungal invasion. 相似文献
28.
Angelo PC Nunes-Silva CG Brígido MM Azevedo JS Assunção EN Sousa AR Patrício FJ Rego MM Peixoto JC Oliveira WP Freitas DV Almeida ER Viana AM Souza AF Andrade EV Acosta PO Batista JS Walter ME Leomil L Anjos DA Coimbra RC Barbosa MH Honda E Pereira SS Silva A Pereira JO Silva ML Marins M Holanda FJ Abreu RM Pando SC Gonçalves JF Carvalho ML Leal-Mesquita ER da Silveira MA Batista WC Atroch AL França SC Porto JI Schneider MP 《Plant cell reports》2008,27(1):117-124
Guarana (Paullinia cupana var. sorbilis) is a plant native to the central Amazon basin. Roasted seed extracts have been used as medicinal beverages since pre-Colombian
times, due to their reputation as stimulants, aphrodisiacs, tonics, as well as protectors of the gastrointestinal tract. Guarana
plants are commercially cultivated exclusively in Brazil to supply the national carbonated soft-drink industry and natural
product stores around the world. In this report, we describe and discuss the annotation of 15,387 ESTs from guarana seeded-fruits,
highlighting sequences from the flavonoid and purine alkaloid pathways, and those related to biotic stress avoidance. This
is the largest set of sequences registered for the Sapindaceae family. 相似文献
29.
Olga Dolgova Carla Rego Gemma Calabria Joan Balanyà Marta Pascual Enrico L Rezende Mauro Santos 《BMC evolutionary biology》2010,10(1):363
Background
Behaviour has been traditionally viewed as a driver of subsequent evolution because behavioural adjustments expose organisms to novel environments, which may result in a correlated evolution on other traits. In Drosophila subobscura, thermal preference and heat tolerance are linked to chromosomal inversion polymorphisms that show parallel latitudinal clines worldwide, such that "cold-climate" ("warm-climate") chromosome arrangements collectively favour a coherent response to colder (warmer) settings as flies carrying them prefer colder (warmer) conditions and have lower (higher) knock out temperatures. Yet, it is not clear whether a genetic correlation between thermal preference and heat tolerance can partially underlie such response. 相似文献30.
Rego D Kumar A Nilchi L Wright K Huang S Kozlowski M 《Journal of immunology (Baltimore, Md. : 1950)》2011,186(9):5443-5456