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31.
Cattle pastures established in areas previously covered by tropical rainforest can be abandoned in unproductive and degraded conditions. Transplanting native tree species to pastures is one common practice among rainforest restoration techniques, but several environmental barriers compromise transplant success. We assessed whether the presence of isolated trees and the removal of pasture grasses affect survival, growth, and allometry of transplanted saplings of the pioneer tree Trema micrantha (L.) Blume (Ulmaceae) into abandoned pastures in southeast Mexico. An isolated tree was selected in the center of each of four pasture sites of one hectare, and grass treatments were applied under the tree's canopy (0–10 m from the trunk) and in open pasture (15–48 m from the trunk). Grass removal treatments were control (grass present), cut with machete, herbicide application, and total grass removal with a gardening hoe. After 1 year, sapling survival was not different between the canopy and pasture areas (53%). Saplings showed higher survival probability (p < 0.05) in the hoe treatment (63 ± 9%) than in the control treatment (38 ± 9%). Height and crown cover growth rates were faster under the canopy of isolated trees compared with the open pasture. Saplings showed significantly greater crown area/height ratios under the canopy of isolated trees. Stressful environmental conditions restricted sapling growth in the open pasture. We conclude that complete removal of grasses and transplanting T. micrantha saplings in the vicinity of isolated trees can improve transplant success. 相似文献
32.
Cortes-Bratti X Bassères E Herrera-Rodriguez F Botero-Kleiven S Coppotelli G Andersen JB Masucci MG Holmgren A Chaves-Olarte E Frisan T Avila-Cariño J 《PloS one》2011,6(2):e16960
Background
Thioredoxin 80 (Trx80) is an 80 amino acid natural cleavage product of Trx, produced primarily by monocytes. Trx80 induces differentiation of human monocytes into a novel cell type, named Trx80-activated-monocytes (TAMs).Principal Findings
In this investigation we present evidence for a role of TAMs in the control of intracellular bacterial infections. As model pathogens we have chosen Listeria monocytogenes and Brucella abortus which replicate in the cytosol and the endoplasmic reticulum respectively. Our data indicate that TAMs efficiently inhibit intracellular growth of both L. monocytogenes and B. abortus. Further analysis shows that Trx80 activation prevents the escape of GFP-tagged L. monocytogenes into the cytosol, and induces accumulation of the bacteria within the lysosomes. Inhibition of the lysosomal activity by chloroquine treatment resulted in higher replication of bacteria in TAMs compared to that observed in control cells 24 h post-infection, indicating that TAMs kill bacteria by preventing their escape from the endosomal compartments, which progress into a highly degradative phagolysosome.Significance
Our results show that Trx80 potentiates the bactericidal activities of professional phagocytes, and contributes to the first line of defense against intracellular bacteria. 相似文献33.
34.
Godoy A Ulloa V Rodríguez F Reinicke K Yañez AJ García Mde L Medina RA Carrasco M Barberis S Castro T Martínez F Koch X Vera JC Poblete MT Figueroa CD Peruzzo B Pérez F Nualart F 《Journal of cellular physiology》2006,207(3):614-627
It has been proposed that the enhanced metabolic activity of tumor cells is accompanied by an increased expression of facilitative hexose transporters (GLUTs). However, a previous immunohistochemical analysis of GLUT1 expression in 154 malignant human neoplasms failed to detect the GLUT1 isoform in 87 tumors. We used 146 normal human tissues and 215 tumor samples to reassess GLUT1 expression. A similar number of samples were used to compare the expression of GLUT2-6 and 9. The classical expression of GLUT1-5 in different normal human tissues was confirmed, however, we were unable to detect GLUT2 in human pancreatic islet cells. GLUT6 was principally detected in testis germinal cells and GLUT9 was localized in kidney, liver, heart, and adrenal. In tumor samples, GLUT1, 2, and 5 were the main transporters detected. GLUT1 was the most widely expressed transporter, however, 42% of the samples had very low-to-negative expression levels. GLUT2 was detected in 31% of the samples, being mainly expressed in breast, colon, and liver carcinoma. GLUT5 was detected in 27% of breast and colon adenocarcinoma, liver carcinoma, lymphomas, and testis seminoma samples. In situ RT-PCR and ultrastructural immunohistochemistry confirmed GLUT5 expression in breast cancer. GLUT6 and 9 are not clearly over-expressed in human cancer. The extensive expression of GLUT2 and 5 (glucose/fructose and fructose transporters, respectively) in malignant human tissues indicates that fructose may be a good energy substrate in tumor cells. Our functional data obtained in vitro in different tumor cells support this hypothesis. Additionally, these results suggest that fructose uptake could be used for positron emission tomography imaging and, may possibly represent a novel target for the development of therapeutic agents in different human cancers. 相似文献
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37.
Luz Miriam Leiva Hamilton Delgado Leidy Viviana Holguín Christian Rojas 《Biomédica : revista del Instituto Nacional de Salud》2021,41(2):218
Otitis media is a frequent infection during childhood. Complications may be present in up to 4 of 100 children including serious neurological complications, particularly in developing countries.We report the case of a 9-year-old girl with no disease history who presented with otitis media, otorrhea, intracranial hypertension syndrome, and paralysis of the VI cranial nerve contralateral to the lesion. A computed tomography scan of the skull and a brain magnetic resonance imaging revealed chronic otomastoiditis, petrous apicitis, and thrombosis of the transverse and sigmoid sinus, the jugular bulb, and the right internal jugular vein. She received antibiotics and surgical treatment.This case shows the spectrum of intra and extracranial complications associated with acute otitis media in the antibiotic era. The physical examination allows early identification of intracranial hypertension with signs such as papilledema and sixth contralateral nerve palsy as an unusual finding. 相似文献
38.
María Elisa Mariani Marcos Ariel Villarreal Foo Cheung Ezequiel Pedro Marcos Leiva Ricardo Román Madoery Gerardo Daniel Fidelio 《Biochimie》2012
At the present, no secreted phospholipase A2 (sPLA2) from soybean (Glycine max) was investigated in detail. In this work we identified five sequences of putative secreted sPLA2 from soybean after a BLAST search in G. max database. Sequence analysis showed a conserved PA2c domain bearing the Ca2+ binding loop and the active site motif. All the five mature proteins contain 12 cysteine residues, which are commonly conserved in plant sPLA2s. We propose a phylogenetic tree based on sequence alignment of reported plant sPLA2s including the novel enzymes from G. max. According to PLA2 superfamily, two of G. max sPLA2s are grouped as XIA and the rest of sequences as XIB, on the basis of differences found in their molecular weights and deviating sequences especially in the N- and C-terminal regions of the isoenzymes. Furthermore, we report the cloning, expression and purification of one of the putative isoenzyme denoted as GmsPLA2-XIA-1. We demonstrate that this mature sPLA2 of 114 residues had PLA2 activity on Triton:phospholipid mixed micelles and determine the kinetic parameters for this system. We generate a model based on the known crystal structure of sPLA2 from rice (isoform II), giving first insights into the three-dimensional structure of folded GmsPLA2-XIA-1. Besides describing the spatial arrangement of highly conserved pair HIS-49/ASP-50 and the Ca+2 loop domains, we propose the putative amino acids involved in the interfacial recognition surface. Additionally, molecular dynamics simulations indicate that calcium ion, besides its key function in the catalytic cycle, plays an important role in the overall stability of GmsPLA2-XIA-1 structure. 相似文献
39.
Martinez-Micaelo N González-Abuín N Terra X Richart C Ardèvol A Pinent M Blay M 《The Biochemical journal》2012,441(2):653-663
40.
Bustamante-Marín X Quiroga C Lavandero S Reyes JG Moreno RD 《Apoptosis : an international journal on programmed cell death》2012,17(6):539-550
Apoptosis, necrosis and autophagy are mechanistically related processes that control tissue homeostasis and cell survival.
In the testis, germ cell death is important for controlling sperm output, but it is unknown whether or not germ cells can
switch from apoptosis to necrosis, as has been reported in other tissues. Furthermore, autophagy has not been reported in
spermatogenesis. Spermatocytes (meiotic cells) and spermatids (haploid cells) use lactate rather than glucose as their primary
substrate for producing ATP. The metabolism of glucose, but not lactate, reduces ATP levels and increases intracellular [H+] and [Ca2+], both of which are associated with apoptosis and/or necrosis in somatic cells. In this work, we evaluated whether different
energy sources, such as lactate or glucose, can influence spermatocyte death type and/or survival in primary cultures. Spermatocytes
cultured for 12 h without an energy source died by necrosis, while spermatocytes cultured with 5 mM glucose showed a significant
increase in apoptosis, as evidenced by caspase activity, TUNEL assay and phosphatidylserine exposure. Apoptosis was not observed
in spermatocytes cultured with 5 mM lactate or deoxyglucose. Authophagy markers, such as LC3-II and autophagosomes, were detected
after 12 h of culture, regardless the culture conditions. These results suggest that the availability of glucose and/or lactate
affect the type of death or the survival of primary spermatocytes, where glucose can induce apoptosis, while lactate is a
protective factor. 相似文献