Within two models of steroid-modulated behavior, sodium appetite and sexual receptivity, novel mechanisms of steroid action have emerged. These include interactions between different types of steroid receptors, plasticity of synapses, activation of unliganded steroid receptors, and rapid effects of steroids. These mechanisms highlight the diversity of steroid action in the central nervous system. 相似文献
The D.M. Raup & A. Michelson model of assessing shell-coiling constitutes a method which simplifies the measuring of spiral-coiling gastropod shells. With, this method the information is obtained by measuring the photograph of the object.The newly developed method has the advantage of dispensing with an exact shell orientation (horizontally located axis) and magnification.Instead of photographing the object with a camera the shell is placed upon photographic paper and in this manner a contact showing the shell outlines can be achieved by exposing and developing the print. Correct information is then obtained by means of the conversion factors (1–3) as outlined in this paper. 相似文献
The ability of amendments to modify the soil properties and influence plants to immobilise Cu and Zn was studied in a naturally contaminated, additionally spiked podzolic soil. Lolium perenne L (perennial rye grass), Festuca rubra L (creeping red fescue) and Poa pratensis L (Kentucky blue grass) were tested in a pot study in the presence of soil amendments (lime, phosphate, and compost, individually and in combination) to assess the effect of soil-plant-amendment interaction on phytostabilisation. The ability of treatments to stabilize metals was assessed on the basis of metal fractionation in soil, partitioning of metals in plants, and metal uptake by the plants. Significant partitioning of Cu into immobile forms occurred as a result of the growth of Festuca rubra, and of Zn by the growth of Poa pratensis. Application of lime significantly reduced the exchangeable fraction of Zn, whereas phosphate application had an accelerating effect on exchangeable Cu. With combined application of amendments, the plant metal concentration decreased by more than 40% for Cu and 70% for Zn, compared to soils receiving no amendments. Combined application of amendments, in conjunction with growth of Festuca and Poa, can be recommended for phytostabilising of Cu and Zn in moderately contaminated acid soils of southwest British Columbia. 相似文献
Chronic airway infection is a hallmark feature of cystic fibrosis (CF) disease. In the present study, sputum samples from CF patients were collected and characterized by 16S rRNA gene-targeted approach, to assess how lung microbiota composition changes following a severe decline in lung function. In particular, we compared the airway microbiota of two groups of patients with CF, i.e. patients with a substantial decline in their lung function (SD) and patients with a stable lung function (S). The two groups showed a different bacterial composition, with SD patients reporting a more heterogeneous community than the S ones. Pseudomonas was the dominant genus in both S and SD patients followed by Staphylococcus and Prevotella. Other than the classical CF pathogens and the most commonly identified non-classical genera in CF, we found the presence of the unusual anaerobic genus Sneathia. Moreover, the oligotyping analysis revealed the presence of other minor genera described in CF, highlighting the polymicrobial nature of CF infection. Finally, the analysis of correlation and anti-correlation networks showed the presence of antagonism and ecological independence between members of Pseudomonas genus and the rest of CF airways microbiota, with S patients showing a more interconnected community in S patients than in SD ones. This population structure suggests a higher resilience of S microbiota with respect to SD, which in turn may hinder the potential adverse impact of aggressive pathogens (e.g. Pseudomonas). In conclusion, our findings shed a new light on CF airway microbiota ecology, improving current knowledge about its composition and polymicrobial interactions in patients with CF. 相似文献
Elevated oxygen tensions are inhibitory to the growth of skin fibroblasts. Skin fibroblasts grow better at oxygen tensions below 137 mm Hg regardless of seeding density. A wide range of oxygen tensions, including those in the physiological range, strongly modulate the growth of human skin fibroblasts. There were no significant differences between the responses of fetal and postnatal cell lines to changes in ambient oxygen tension. In all cases, higher oxygen tensions significantly impeded cell growth. Seeding cells at 10(4) cells/cm(2) afforded some protection from the deleterious effects of hyperoxia. Oxygen tensions exceeding the amount present in ambient room air also impeded cell growth at this higher seeding density, but the effect did not become significant until the oxygen partial pressure reached 241 mm Hg. At lower oxygen tensions, cells seeded at 10(3) cells/cm(2) grew more rapidly than did cells seeded at 10(4) cells/cm(2). These findings may have implications for the treatment of poorly healing wounds with hyperbaric oxygen. 相似文献
Hurricane disturbances produce significant changes in forest microclimates, creating opportunities for seedling regeneration of native and invasive plant species alike. However, there is limited information on how changes in microclimates and pre-existing forest conditions affect native and invasive plants responses to hurricane disturbances. In this manipulative study, we examined the responses of three common shrub/small stature tree species, two of which are native to the coastal region of the southeastern USA (Baccharis halimifolia and Morella cerifera) and one that is invasive (Triadica sebifera), to two key components of hurricane disturbance (canopy damage and saline storm surge). In a greenhouse, we grew seedlings of these species under a range of shade levels that mimicked pre-and post-hurricane canopy conditions for wet pine forest and mixed hardwood forest, two forest communities common in coastal areas of the southeastern USA. Seedlings were subjected to saline storm surges equivalent to full strength sea water for 3 days. Seedling responses (mortality and growth) to the treatments were monitored for 16 months. All species benefitted from higher canopy openness. Storm surge effects were short-lived and seedlings readily recovered under high light conditions. The storm surge had stronger negative effects on survival and growth of all species when coupled with high shade, suggesting storm surge has greater negative impacts on seedlings where hurricane winds cause minimal or no canopy damage. The invasive T. sebifera was by far more shade tolerant than the natives. Survival of T. sebifera seedlings under highly shaded conditions may provide it a competitive edge over native species during community reassembly following tropical storms. Differential responses of native and invasive species to hurricane disturbances will have profound consequences on community structure across coastal forest stands, and may be regulated by legacies of prior disturbances, community structure, extent of canopy damage, and species’ tolerance to specific microclimates.
This is the second of two articles reporting the results of a study by the author regarding the status of elementary music education in the state of Utah. This article focuses on the qualifications of Utah's elementary music teachers (music certified, elementary classroom certified, artists-in-residence, volunteers, and paraprofessionals) and the conditions under which they teach. Interactions among teacher qualifications and teaching status are explored. Paraprofessionals play a significant role in Utah's elementary music programs. While over 90 percent of elementary schools in the United States provide regular music instruction taught by certified music specialists, less than 10 percent of Utah's elementary population receives such instruction. Nearly half of the elementary students in the state receive no designated music instruction beyond that provided by their regular elementary classroom teacher. The influence of school funding, No Child Left Behind and other accountability measures, high-stakes testing, urban/rural populations, and leadership are highlighted. Policy considerations are discussed. 相似文献
Soil solarization, alone or combined with organic amendment, is an increasingly attractive approach for managing soil-borne
plant pathogens in agricultural soils. Even though it consists in a relatively mild heating treatment, the increased soil
temperature may strongly affect soil microbial processes and nutrients dynamics. This study aimed to investigate the impact
of solarization, either with or without addition of farmyard manure, in soil dynamics of various C, N and P pools. Changes
in total C, N and P contents and in some functionally-related labile pools (soil microbial biomass C and N, K2SO4-extractable C and N, basal respiration, KCl-exchangeable ammonium and nitrate, and water-soluble P) were followed across
a 72-day field soil solarization experiment carried out during a summer period on a clay loam soil in Southern Italy. Soil
physico-chemical properties (temperature, moisture content and pH) were also monitored. The average soil temperature at 8-cm
depth in solarized soils approached 55 °C as compared to 35 °C found in nonsolarized soil. Two-way ANOVA (solarization×organic
amendment) showed that both factors significantly affected most of the above variables, being the highest influence exerted
by the organic amendment. With no manure addition, solarization did not significantly affect soil total C, N and P pools.
Whereas soil pH, microbial biomass and, at a greater extent, K2SO4-extractable N and KCl-exchangeable ammonium were greatly affected. An increased release of water-soluble P was also found
in solarized soils. Yet, solarization altered the quality of soluble organic residues released in soil as it lowered the C-to-N
ratio of both soil microbial biomass and K2SO4-extractable organic substrates. Additionally, in solarized soils the metabolic quotient (qCO2) significantly increased while the microbial biomass C-to-total organic C ratio (microbial quotient) decreased over the whole
time course. We argued that soil solarization promoted the mineralization of readily decomposable pools of the native soil
organic matter (e.g. the microbial biomass) thus rendering larger, at least over a short-term, the available fraction of some
soil mineral nutrients, namely N and P forms. However, over a longer prospective solarization may lead to an over-exploitation
of labile organic resources in agricultural soils. Manure addition greatly increased the levels of both total and labile C,
N and P pools. Thus, addition of organic amendments could represent an important strategy to protect agricultural lands from
excessive soil resources exploitation and to maintain soil fertility while enhancing pest control. 相似文献
Macrophage foam cell is the predominant cell type in atherosclerotic lesions. Removal of excess cholesterol from macrophages thus offers effective protection against atherosclerosis. Here we report that a protein kinase A (PKA)-anchoring inhibitor, st-Ht31, induces robust cholesterol/phospholipid efflux, and ATP-binding cassette transporter A1 (ABCA1) greatly facilitates this process. Remarkably, we found that st-Ht31 completely reverses foam cell formation, and this process is ABCA1-dependent. The reversal is also accompanied by the restoration of well modulated inflammatory response to LPS. There is no detectable toxicity associated with st-Ht31, even when cells export up to 20% cellular cholesterol per hour. Using FRET-based PKA biosensors in live cells, we provide evidence that st-Ht31 drives cholesterol efflux by elevating PKA activity specifically in the cytoplasm. Furthermore, ABCA1 facilitates st-Ht31 uptake. This allows st-Ht31 to effectively remove cholesterol from ABCA1-expressing cells. We speculate that de-anchoring of PKA offers a novel therapeutic strategy to remove excess cholesterol from lipid-laden lesion macrophages. 相似文献
Few studies have compared the relative benefits of moderate- vs. higher intensity exercise training on improving insulin sensitivity in older people while holding exercise volume constant. Healthy older (73 +/- 10 yr) women (N = 25) who were inactive, but not obese, were randomized into one of three training programs (9-mo duration): 1) high-intensity [80% peak aerobic capacity (V(O2)peak); T(H)] aerobic training; 2) moderate-intensity (65% V(O2)peak; T(M)) aerobic training; or 3) low-intensity (stretching) placebo control (50% V(O2)peak); C(TB)). Importantly, exercise volume (300 kcal/session) was held constant for subjects in both the T(H) and the T(M) groups. V(O2)peak was determined by using a graded exercise challenge on a treadmill. Total body fat and lean mass were determined with dual-energy X-ray absorptiometry. The rate of insulin-stimulated glucose utilization as well as the suppression of lipolysis were determined approximately 72 h after the final exercise bout by using a two-step euglycemic-hyperinsulinemic clamp. We observed improved glucose utilization at the higher insulin dose with training, but these improvements were statistically significant only in the T(H) (21%; P = 0.02) compared with the T(M) (16%; P = 0.17) and C(TB) (8%; P = 0.37) groups and were observed without changes in either body composition or V(O2)peak. Likewise in the T(H) group, we detected a significant improvement in insulin-stimulated suppression (%) of adipose tissue lipolysis at the low-insulin dose (38-55%, P < 0.05). Our findings suggest that long-term higher intensity exercise training provides more enduring benefits to insulin action compared with moderate- or low-intensity exercise, likely due to greater transient effects. 相似文献