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121.
Alonso A Fernández Y Fernández R Ordóñez P Moreno M Díaz F Patterson AM González C 《The Journal of nutritional biochemistry》2005,16(10):602-609
We tried to elucidate the effects of a brief and severe model of food restriction on insulin sensitivity in female rats, focusing on key proteins involved in the insulin signalling pathway in skeletal muscle and adipose tissue after 5, 10 and 15 days of food restriction. Using euglycemic clamp, we detected that food-restricted rats are significantly less sensitive to insulin action than control rats. However, the time of restriction promotes a progressive increase on insulin sensitivity. The analysis of the insulin signalling pathway showed a tissue-specific regulation of several proteins involved in insulin signalling. In skeletal muscle, insulin receptor substrate 1 and Glut4 are up-regulated at the end of the food restriction period, just the opposite of what we found in adipose tissue. In conclusion, a 50% reduction of food intake modulates insulin sensitivity through a tissue-specific regulation of the insulin signalling pathway in the main target tissues for this hormone. 相似文献
122.
Dengue is the most common mosquito-borne viral disease in humans. The spread of both mosquito vectors and viruses has led to the resurgence of epidemic dengue fever (a self-limited flu-like syndrome) and the emergence of dengue hemorrhagic fever (severe dengue with bleeding abnormalities) in urban centers of the tropics. There are no animal or laboratory models of dengue disease; indirect evidence suggests that dengue viruses differ in virulence, including their pathogenicities for humans and epidemic potential. We developed two assay systems (using human dendritic cells and Aedes aegypti mosquitoes) for measuring differences in virus replication that correlate with the potential to cause hemorrhagic dengue and increased virus transmission. Infection and growth experiments showed that dengue serotype 2 viruses causing dengue hemorrhagic fever epidemics (Southeast Asian genotype) can outcompete viruses that cause dengue fever only (American genotype). This fact implies that Southeast Asian genotype viruses will continue to displace other viruses, causing more hemorrhagic dengue epidemics. 相似文献
123.
Iron deficiency changed markedly the shape of the leaf chlorophyll fluorescence induction kinetics during a dark-light transition,
the so-called Kautsky effect. Changes in chlorophyll fluorescence lifetime and yield were observed, increasing largely the
minimal and the intermediate chlorophyll fluorescence levels, with a marked dip between the intermediate and the maximum levels
and loss of the secondary peak after the maximum. During the slow changes, the lifetime-yield relationship was found to be
linear and curvilinear (towards positive lifetime values) in control and Fe-deficient leaves, respectively. These results
suggested that part of the Photosystem II antenna in Fe-deficient leaves emits fluorescence with a long lifetime. In dark-adapted
Fe-deficient leaves, measurements in the picosecond-nanosecond time domain confirmed the presence of a 3.3-ns component, contributing
to 15% of the total fluorescence. Computer simulations revealed that upon illumination such contribution is also present and
remains constant, indicating that energy transfer is partially interrupted in Fe-deficient leaves. Photosystem II-enriched
membrane fractions containing different pigment-protein complexes were isolated from control and Fe-deficient leaves and characterized
spectrophotometrically. The photosynthetic pigment composition of the fractions was also determined. Data revealed the presence
of a novel pigment-protein complex induced by Fe deficiency and an enrichment of internal relative to peripheral antenna complexes.
The data suggest a partial disconnection between internal Photosystem II antenna complexes and the reaction center, which
could lead to an underestimation of the Photosystem II efficiency in dark-adapted, low chlorophyll Fe-deficient leaves, using
chlorophyll fluorescence.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
124.
Diana Dennys Gandarilla-Esparza Esperanza Yasmin Calleros-Rincn Hortensia Moreno Macias María Fernanda Gonzlez-Delgado Gonzalo García Vargas Jaime Duarte Sustaita Alberto Gonzlez-Zamora Efraín Ríos-Snchez Rebeca Prez-Morales 《Genetics and molecular biology》2021,44(3)
Nitrates in drinking water has been associated to adverse health effects, including changes in glucose and lipid levels, thyroid hormone imbalance and adverse reproductive effects. We analyzed metabolic and thyroid hormone alterations and genotoxic damage in women with chronic exposure to nitrates in drinking water. The concentration of nitrates in drinking water was quantified and according to this parameter, participants were divided into three exposure scenarios. Blood and urine samples were collected from 420 women living in Durango, Mexico and biomarkers were determined. We found nitrates concentrations in drinking water above the permissible limit (>50 mg/L), and an increase in the percentage of methemoglobin (p=0.0001), nitrite in blood plasma and urine (p=0.0001), glucose (p=0.0001), total cholesterol (p=0.001), LDL (p=0.001) and triglycerides (p=0.0001). We also found alterations in TSH (p=0.01), fT3 (p=0.0003), T4T (p=0.01) and fT4 (p=0.0004) hormones. Frequency of subclinical hypothyroidism was 8.33%; differences in FOXE1 (rs965513, rs1867277) genotypes distribution were found and both polymorphisms were associated with a decrease in TSH. A high percentage of micronucleus in binucleate lymphocyte cells was found (35%, p=0.0001). In conclusion, the chronic exposure to nitrates in water for human consumption caused metabolic and hormonal alterations and genotoxic damage in women. 相似文献
125.
Marco Antonio Moro-García Rebeca Alonso-Arias Carlos López-Larrea 《Current Genomics》2012,13(8):589-602
T-lymphocytes play a central role in the effector and regulatory mechanisms of the adaptive immune response. Upon exiting the thymus they begin to undergo a series of phenotypic and functional changes that continue throughout the lifetime and being most pronounced in the elderly. The reason postulated for this is that the dynamic processes of repeated interaction with cognate antigens lead to multiple division cycles involving a high degree of cell differentiation, senescence, restriction of the T-cell receptor (TCR) repertoire, and cell cycle arrest. This cell cycle arrest is associated with the loss of telomere sequences from the ends of chromosomes. Telomere length is reduced at each cell cycle, and critically short telomeres recruit components of the DNA repair machinery and trigger replicative senescence or apoptosis. Repetitively stimulated T-cells become refractory to telomerase induction, suffer telomere erosion and enter replicative senescence. The latter is characterized by the accumulation of highly differentiated T-cells with new acquired functional capabilities, which can be caused by aberrant expression of genes normally suppressed by epigenetic mechanisms in CD4+ or CD8+ T-cells. Age-dependent demethylation and overexpression of genes normally suppressed by DNA methylation have been demonstrated in senescent subsets of T-lymphocytes. Thus, T-cells, principally CD4+CD28null T-cells, aberrantly express genes, including those of the KIR gene family and cytotoxic proteins such as perforin, and overexpress CD70, IFN-γ, LFA-1 and others. In summary, owing to a lifetime of exposure to and proliferation against a variety of pathogens, highly differentiated T-cells suffer molecular modifications that alter their cellular homeostasis mechanisms. 相似文献
126.
Stefan Toepfer Guillermo Cabrera Walsh Astrid Eben Rebeca Alvarez-Zagoya Tim Haye Feng Zhang 《Biocontrol Science and Technology》2008,18(5):483-504
The subtribe Diabroticina is a large group of New World Chrysomelidae that includes corn rootworms, cucumber beetles and other pests. Recent introductions of Diabrotica virgifera virgifera LeConte into Europe, and the development of resistances to current management practices of rootworms in the USA have increased interest in new sustainable options for managing those pests. The only parasitoids that have been shown to consistently target and develop inside the beetle adults are Centistes gasseni Shaw, Centistes diabroticae Gahan (both Hym.: Braconidae), and Celatoria diabroticae Shimer, Celatoria compressa (Wulp), Celatoria bosqi Blanchard, and Celatoria setosa Coquillett (all Diptera: Tachinidae). This review improves our understanding of the realised and potential host range of these known parasitoids by rectifying erroneous references in light of new host records and from laboratory host range tests. Based on this critical review, all tachinid and braconid species studied are considered to be specific at least to the level of subtribe, i.e. Diabroticina. Celatoria setosa, Celatoria diabroticae and C. bosqi, have a narrow realized and potential host range; the former is restricted to the genus Acalymma and the last two to the fucata and virgifera groups of the genus Diabrotica. The braconids Centistes gasseni and C. diabroticae are also specific. The realized host range of C. gasseni includes species in the Diabrotica fucata and virgifera groups; while its potential host range also includes Acalymma species. The realized and potential host range of Centistes diabroticae includes Acalymma species as well as species in the fucata and virgifera groups of Diabrotica. Celatoria compressa has the broadest realised range compared to the other species studied, since it was obtained from species in several genera of Diabroticina; and its potential host range may also include Old World Aulacophora species. 相似文献
127.
128.
Parental care and division of labor in male and female primary reproductives in incipient colonies of the dampwood termite Zootermopsis angusticolliswere studied by recording repertory sizes, behavior frequencies, time budgets, and transition probabilities of acts. Repertory sizes for males and females were identical, and behaviors were performed at similar frequencies. Time budget data also suggested equal participation in parental care by both sexes. Transition probability analysis suggested that males and females did not organize their behavior in roles. We therefore found no indication of sex-based division of labor during colony foundation and the incipient stages of colony growth. The lack of behavioral specialization may be due to the fact that acts might be related and/or have more than one function, and different tasks are not spatially associated. Our observations are consistent with the hypothesis that monogamous mating systems in termites involve mate assistance. 相似文献
129.
130.
Fabrícia Alvisi de Oliveira Aline Silva Barreto Lays G. S. Bomfim Talita Rebeca S. Leite Priscila Lima dos Santos Roque Pacheco de Almeida ?ngela Maria da Silva Malcolm S. Duthie Steven G. Reed Tatiana Rodrigues de Moura Amélia Ribeiro de Jesus 《PloS one》2015,10(10)