Lovastatin inhibits the extracellular-signal-regulated kinase pathway in immortalized rat brain neuroblasts

Arachidonic acid is a potential paracrine agent released by the uterine endometrial epithelium to induce PTGS2 [PG (prostaglandin)-endoperoxide synthase 2] in the stroma. In the present study, bovine endometrial stromal cells were used to determine whether PTGS2 is induced by arachidonic acid in stromal cells, and to investigate the potential role of PPARs (peroxisome-proliferator-activated receptors) in this effect. Arachidonic acid increased PTGS2 levels up to 7.5-fold within 6 h. The cells expressed PPARalpha and PPARdelta (also known as PPARbeta) (but not PPARgamma). PTGS2 protein level was increased by PPAR agonists, including polyunsaturated fatty acids, synthetic PPAR ligands, PGA1 and NSAIDs (non-steroidal anti-inflammatory drugs) with a time course resembling that of arachidonic acid. Use of agonists and antagonists indicated PPARalpha (but not PPARdelta or PPARgamma) was responsible for PTGS2 induction. PTGS2 induction by arachidonic acid did not require PG synthesis. PTGS2 levels were increased by the PKC (protein kinase C) activators 4beta-PMA and PGF(2alpha), and the effects of arachidonic acid, NSAIDs, synthetic PPAR ligands and 4beta-PMA were blocked by PKC inhibitors. This is consistent with PPAR phosphorylation by PKC. Induction of PTGS2 protein by 4beta-PMA in the absence of a PPAR ligand was decreased by the NF-kappaB (nuclear factor kappaB) inhibitors MG132 and parthenolide, suggesting that PKC acted through NF-kappaB in addition to PPAR phosphorylation. Use of NF-kappaB inhibitors allowed the action of arachidonic acid as a PPAR agonist to be dissociated from an effect through PKC. The results are consistent with the hypothesis that arachidonic acid acts via PPARalpha to increase PTGS2 levels in bovine endometrial stromal cells.     

Cluster root formation and function vary in two species with contrasting geographic ranges

Plant and Soil - Southern South American Proteaceae can occupy soils that are rich in total phosphorus (P) but poor in available P (for example volcanic soils) thanks to their cluster roots (CR),...     

Understorey plant community assemblage of Australian Eucalyptus woodlands under elevated CO2 is modulated by water and phosphorus availability

水分和磷调控的澳大利亚桉树林林下植物群落组合对二氧化碳浓度升高的响应 鉴于林下植物群落具有的关键性功能作用和全球范围内巨大的森林覆盖面积,研究林下群落对 CO₂浓度升高(eCO₂)的响应以及土壤资源在这些响应中的作用,对于了解CO₂浓度升高对森林生态系统造成的影响非常重要。本研究评估了在澳大利亚东部磷有限的桉树林林下群落中,两种限制性的资源(即水分和磷)在发芽、物候、覆盖率、群落组成和叶片性状等方面对eCO₂响应的作用。我们收集了含有当地土壤种子库的土壤,在温室条件下种植实验性的林下植物群落。研究结果表明,添加磷提高了植物的总体覆盖率,特别是在生长期的最初4 周以及水分含量高的条件下,而且该响应是由植物群落中的类禾本科植物所驱动。然而,随着实验的进行,不同处理方法之间的差异逐渐减小,所有处理在大约11周后均达到了80%左右的植物覆盖率。相反,植物覆盖率并未受到eCO₂ 的影响。多元分析结果反映出植物群落组成随时间的变化,盆栽从以裸土为主变为以高覆盖率的多样化群落为主。但是在实验过程中,磷的添加以及水分可利用性和CO₂之间的相互作用都对植物群落随时间的变化轨迹有所影响。CO₂浓度的升高也增加了群落水平的比叶面积,这表明植物群落对eCO₂的功能适应可能发生在成分响应开始之前。鉴于我们用种子库培育的林下群落对eCO₂ 的响应随着时间的推移而有 所变化,并且受到与磷和水分可利用性的相互作用的调节。我们的结果表明,在水分含量有限的系统中, 特别是在土壤养分可利用性低所导致的生产力响应受限的情况下,CO₂浓度的升高在塑造植物群落方面作用有限。     

Experimental evidence for real-time song frequency shift in response to urban noise in a passerine bird

Research has shown that bird songs are modified in different ways to deal with urban noise and promote signal transmission through noisy environments. Urban noise is composed of low frequencies, thus the observation that songs have a higher minimum frequency in noisy places suggests this is a way of avoiding noise masking. Most studies are correlative and there is as yet little experimental evidence that this is a short-term mechanism owing to individual plasticity. Here we experimentally test if house finches (Carpodacus mexicanus) can modulate the minimum frequency of their songs in response to different noise levels. We exposed singing males to three continuous treatments: low–high–low noise levels. We found a significant increase in minimum frequency from low to high and a decrement from high to low treatments. We also found that this was mostly achieved by modifying the frequency of the same low-frequency syllable types used in the different treatments. When different low-frequency syllables were used, those sung during the noisy condition were longer than the ones sang during the quiet condition. We conclude that house finches modify their songs in several ways in response to urban noise, thus providing evidence of a short-term acoustic adaptation.     

Oviposition pattern of the predator Podisus nigrispinus (Heteroptera: Pentatomidae) under different temperatures

The daily reproductive rate of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) fed with Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) larvae was studied at constant temperatures of 20, 23, 25, 28, 30 and 33±0.2°C, relative humidity of 60±10% and photoperiod of L:D 14:10. Daily reproductive rate of P. nigripinus was affected by age of this predator. Each P. nigrispinus female laid 5.3 (20°C) to 19.9 eggs/day (28°C) which developed into 4.3–16.5 nymphs, respectively. Highest daily reproductive rate of P. nigrispinus was recorded at 28 and 30°C for 5–30-day-old females. This predator showed higher daily reproductive rate than its prey A. argillacea at 25°C. It was also able to reproduce at temperatures from 20 to 33°C with maximum daily reproductive rate between 25 and 30°C. These results are important for optimizing mass rearing of P. nigrispinus in the laboratory.     

Chromosomal diversity in two synchronopatric species of Hoffmannseggella (Orchidaceae)

Hoffmannseggella viridiflora Verola & Semir (Laeliinae, Orchidaceae) is a recently discovered species in the campos rupestres vegetation of the Espinhaço Range, MG, Brazil, in synchronopatry with H. bradei (Pabst) V. P. Castro & Chiron. Both morphological and phenological studies indicate that these species are closely related. To substantiate the differentiation of these two species we examined their chromosome numbers and morphologies. The two species had different chromosome numbers, with H. bradei having 2n = 40 and H. viridiflora having 2n = 44 chromosomes, an aneuploid number not previously documented in the genus. Meiotic behavioral studies undertaken with H. bradei revealed many abnormalities related to bivalent numbers and chromosome migration, suggesting that meiotic abnormalities could generate aneuploid gametes and perhaps aneuploid zygotes. Karyotype formulas and chromosome morphologies are quite different between the species, so H. viridiflora was not directly derived from H. bradei through simple chromosome additions. Complementary analyses are necessary to understand the process and species involved in the origin of H. viridiflora.     

Formation of compound I and compound II ferryl species in the reaction of hemoglobin I from Lucina pectinata with hydrogen peroxide

The formation of ferryl heme (Fe(IV) = O) species, i.e., compound I and compound II, has been identified as the main intermediates in heme protein peroxidative reactions. We report stopped-flow kinetic measurements which illustrate that the reaction of hemoglobin I (HbI) from Lucina pectinata with hydrogen peroxide produce ferryl intermediates compound I and compound II. Compound I appears relatively stable displaying an absorption at 648 nm. The rate constant value (k'(2)) for the conversion of compound I to compound II is 3.0 x 10(-2) s(-1), more than 100 times smaller than that reported for myoglobin. The rate constant value for the oxidation of the ferric heme (k'(12) + k'(13)) is 2.0 x 10(2) M(-1) s(-1). These values suggest an alternate route for the formation of compound II (by k'(13)) avoiding the step from compound I to compound II (k'(2)). In HbI from L. pectinata the stabilization of compound I is attribute to the unusual collection of amino acids residues (Q64, F29, F43, F68) in the heme pocket active site of the protein.