Response of Archaeal and Bacterial Soil Communities to Changes Associated with Outdoor Cattle Overwintering

Archaea and bacteria are important drivers for nutrient transformations in soils and catalyse the production and consumption of important greenhouse gases. In this study, we investigate changes in archaeal and bacterial communities of four Czech grassland soils affected by outdoor cattle husbandry. Two show short-term (3 years; STI) and long-term impact (17 years; LTI), one is regenerating from cattle impact (REG) and a control is unaffected by cattle (CON). Cattle manure (CMN), the source of allochthonous microbes, was collected from the same area. We used pyrosequencing of 16S rRNA genes to assess the composition of archaeal and bacterial communities in each soil type and CMN. Both short- and long- term cattle impact negatively altered archaeal and bacterial diversity, leading to increase of homogenization of microbial communities in overwintering soils over time. Moreover, strong shifts in the prokaryotic communities were observed in response to cattle overwintering, with the greatest impact on archaea. Oligotrophic and acidophilic microorganisms (e.g. Thaumarchaeota, Acidobacteria, and α-Proteobacteria) dominated in CON and expressed strong negative response to increased pH, total C and N. Whereas copiotrophic and alkalophilic microbes (e.g. methanogenic Euryarchaeota, Firmicutes, Chloroflexi, Actinobacteria, and Bacteroidetes) were common in LTI showing opposite trends. Crenarchaeota were also found in LTI, though their trophic interactions remain cryptic. Firmicutes, Bacteroidetes, Methanobacteriaceae, and Methanomicrobiaceae indicated the introduction and establishment of faecal microbes into the impacted soils, while Chloroflexi and Methanosarcinaceae suggested increased abundance of soil-borne microbes under altered environmental conditions. The observed changes in prokaryotic community composition may have driven corresponding changes in soil functioning.     

Neural Activity Changes Associated with Impulsive Responding in the Sustained Attention to Response Task

Humans can anticipate and prepare for uncertainties to achieve a goal. However, it is difficult to maintain this effort over a prolonged period of time. Inappropriate behavior is impulsively (or mindlessly) activated by an external trigger, which can result in serious consequences such as traffic crashes. Thus, we examined the neural mechanisms underlying such impulsive responding using functional magnetic resonance imaging (fMRI). Twenty-two participants performed a block-designed sustained attention to response task (SART), where each task block was composed of consecutive Go trials followed by a NoGo trial at the end. This task configuration enabled us to measure compromised preparation for NoGo trials during Go responses using reduced Go reaction times. Accordingly, parametric modulation analysis was conducted on fMRI data using block-based mean Go reaction times as an online marker of impulsive responding in the SART. We found that activity in the right dorsolateral prefrontal cortex (DLPFC) and the bilateral intraparietal sulcus (IPS) was positively modulated with mean Go reaction times. In addition, activity in the medial prefrontal cortex (MPFC) and the posterior cingulate cortex (PCC) was negatively modulated with mean Go reaction times, albeit statistically weakly. Taken together, spontaneously reduced activity in the right DLPFC and the IPS and spontaneously elevated activity in the MPFC and the PCC were associated with impulsive responding in the SART. These results suggest that such a spontaneous transition of brain activity pattern results in impulsive responding in monotonous situations, which in turn, might cause human errors in actual work environments.     

Regulation of the Cytoplasmic pH of Chara corallina: Response to Changes in External pH

Effects of external pH (pH_o) on the cytoplasmic pH (pH_c) ofChara corallina have been measured with the weak acid 5, 5-dimethyloxazolidine-2,4-dione (DMO) following standardized pretreatment of cells insolutions at pHo 4.5, 6.3 and 8.3. Irrespective of pH_c duringpretreatment, pH_o responded to pHo during the experimental periodsof 150–180 min or (in one experiment) 90–110 min.There were increases or decreases of about 0.5 in pHo when cellswere transferred from pH_o 4.5 to 8.3 or vice versa. In the darkpH_c was 0.2–0.3 units lower than the corresponding valuein the light. The results are discussed in relation to the factorsinvolved in the regulation of pH_c in C. corallina, which maybegin to break down below about pH_o4.5, as indicated by relativelylarge decreases in pH_c at low pH_o. Key words: Chara corallina, Cytoplasmic pH, External pH, DMO     

Changes in Microbial Communities Associated with the Sea Anemone Anemonia viridis in a Natural pH Gradient

Ocean acidification, resulting from rising atmospheric carbon dioxide concentrations, is a pervasive stressor that can affect many marine organisms and their symbionts. Studies which examine the host physiology and microbial communities have shown a variety of responses to the ocean acidification process. Recently, several studies were conducted based on field experiments, which take place in natural CO₂ vents, exposing the host to natural environmental conditions of varying pH. This study examines the sea anemone Anemonia viridis which is found naturally along the pH gradient in Ischia, Italy, with an aim to characterize whether exposure to pH impacts the holobiont. The physiological parameters of A. viridis (Symbiodinium density, protein, and chlorophyll a+c concentration) and its microbial community were monitored. Although reduction in pH was seen to have had an impact on composition and diversity of associated microbial communities, no significant changes were observed in A. viridis physiology, and no microbial stress indicators (i.e., pathogens, antibacterial activity, etc.) were detected. In light of these results, it appears that elevated CO₂ does not have a negative influence on A. viridis that live naturally in the site. This suggests that natural long-term exposure and dynamic diverse microbial communities may contribute to the acclimation process of the host in a changing pH environment.     

Ionic Current Changes Associated with the Gravity-Induced Bending Response in Roots of Zea mays L

A vibrating probe was used to measure the changes in ionic currents around gravistimulated roots of Zea mays L. in an effort to determine whether these currents are involved in stimulus transduction from the root cap to the elongation zone. We did not observe a migration of the previously reported auxin-insensitive current efflux associated with gravity sensing (T. Björkman, A.C. Leopold [1987] Plant Physiol 84:841-846) back from the root cap. Instead, beginning 10 to 15 min after gravistimulation, an asymmetry in current developed simultaneously along the root around the meristem and apical regions of the elongation zone. This asymmetry comprised a proton efflux from the upper surface, which was superimposed on the symmetrical pattern around the vertical root. The gravity-induced proton efflux was inhibited by the application of the auxin transport inhibitor, 2,3,5-triiodobenzoic acid, whereas the calcium channel blocker, lanthanum, had little effect. Because the onset of the gravity-induced current asymmetry coincided both spatially and temporally with the onset of the differential growth response, we suggest that this current efflux may result from auxin-requiring acid-growth phenomena in the upper root tissue. The implications of this simultaneous onset of both proton efflux and elongation for theories about gravity stimulus transduction are discussed.     

Enhanced BDNF Signaling is Associated with an Antidepressant-like Behavioral Response and Changes in Brain Monoamines

1. Neurotrophins and serotonin have both been implicated in the pathophysiology of depression and in the mechanisms of antidepressant treatments. 2. Brain-derived neurotrophic factor (BDNF) influences the growth and plasticity of serotonergic (5-HT) neurons via the activation of trkB receptor. 3. Transgenic mice overexpressing the full-length trkB receptor (TrkB.TK+) and showing increased trkB activity in brain, and their wild type (WT) littermates, were injected with the antidepressant fluoxetine or saline, and analyzed behaviorally in the forced swimming test paradigm and biochemically for the concentrations of brain monoamines and their metabolites. 4. The TrkB.TK+ mice displayed increased latency to immobility in the forced swim test, suggesting resistance to behavioral despair. 5. Fluoxetine increased the latency to immobility in wild-type mice to a similar level as seen in the trkB.TK+ mice after saline treatment, but had no further behavioral effect in the swimming behavior of the trkB.TK+ mice. 6. Only minor differences in the levels of brain monoamines and their metabolites were observed between the transgenic and wild-type mice. 7. These data, together with other recent observations, suggest that trkB activation may play a critical role in the behavioral responses to antidepressant drugs in mice.     

植物磷胁迫蛋白和铁胁迫蛋白研究进展

综述了近十年来国内外有关研究植物磷胁迫蛋白和铁胁迫蛋白的文献,着重阐述了磷胁迫和铁胁迫条件下的植物蛋白质变化,如新的蛋白和新的多肽的特异产生,以及相关的分子生物学进展。     

Pathologies Associated with the p53 Response

Although p53 is a major cancer preventive factor, under certain extreme stress conditions it may induce severe pathologies. Analyses of animal models indicate that p53 is largely responsible for the toxicity of ionizing radiation or DNA damaging drugs contributing to hematopoietic component of acute radiation syndrome and largely determining severe adverse effects of cancer treatment. p53-mediated damage is strictly tissue specific and occurs in tissues prone to p53-dependent apoptosis (e.g., hematopoietic system and hair follicles); on the contrary, p53 can serve as a survival factor in tissues that respond to p53 activation by cell cycle arrest (e.g., endothelium of small intestine). There are multiple experimental indications that p53 contributes to pathogenicity of acute ischemic diseases. Temporary reversible suppression of p53 by small molecules can be an effective and safe approach to reduce severity of p53-associated pathologies.     

Mast Cell Dependent Vascular Changes Associated with an Acute Response to Cold Immersion in Primary Contact Urticaria

Background

While a number of the consequences of mast cell degranulation within tissues have been documented including tissue-specific changes such as bronchospasm and the subsequent cellular infiltrate, there is little known about the immediate effects of mast cell degranulation on the associated vasculature, critical to understanding the evolution of mast cell dependent inflammation.

Objective

To characterize the microcirculatory events that follow mast cell degranulation.

Methodology/Principal Findings

Perturbations in dermal blood flow, temperature and skin color were analyzed using laser-speckle contrast imaging, infrared and polarized-light colorimetry following cold-hand immersion (CHI) challenge in patients with cold-induced urticaria compared to the response in healthy controls. Evidence for mast cell degranulation was established by documentation of serum histamine levels and the localized release of tryptase in post-challenge urticarial biopsies. Laser-speckle contrast imaging quantified the attenuated response to cold challenge in patients on cetirizine. We found that the histamine-associated vascular response accompanying mast cell degranulation is rapid and extensive. At the tissue level, it is characterized by a uniform pattern of increased blood flow, thermal warming, vasodilation, and recruitment of collateral circulation. These vascular responses are modified by the administration of an antihistamine.

Conclusions/Significance

Monitoring the hemodynamic responses within tissues that are associated with mast cell degranulation provides additional insight into the evolution of the acute inflammatory response and offers a unique approach to assess the effectiveness of treatment intervention.     

Soil pH Effects on Nematode Populations Associated with Soybeans

''Amsoy'' soybeans were grown for 2 months in nonsterilized Jackson silt loam amended to pH 4.0, 6.0, and 8.0. Nematodes were extracted biweekly from soil and roots. The greatest numbers of Pratylenchus alleni colonized soybean roots at pH 6.0. Hoplolaimus galeatus and members of the Tylenchinae-Psilenchinae survived best at pH 6.0, while numbers o f the Dorylaimoidea were greatest at both pH 6.0 and 8.0. The non-stylet nematodes were recovered in greater numbers from pH 8.0 soil. Potassium, manganese, and phenols were highest in soybean plants grown in pH 4.0 soil, the pH at which there were the fewest nematodes. A thicker suberized outer layer o f root tissue occurred in plants grown at pH 4.0.     

microRNA多态性与肿瘤发生和药物反应相关

microRNA(miRNA)是进化保守的、非编码单链小RNA,长度约为18-25个核苷酸.作为基因表达的微观管理者,miRNA通过结合在mRNA的3′-UTR抑制翻译过程或使其降解.miRNA多态性是指一类能够干扰miRNA功能的新多态性或单核苷酸的多态性.这种多态性不仅出现在pri-miRNA、pre-miRNA和成熟的miRNA序列中;也可以出现在靶基因3′-UTR;还可以呈现在miRNA基因表观遗传学的改变.miRNA多态性可能导致疾病的产生,也可以判断临床用药疗效及预后监测.目前miRNA多态性正在作为疾病（尤其是肿瘤）生物学研究的强有力工具,而且已应用于疾病的诊断和预后.     

Iron-Stress Response in Tomato (Lycopersicon esculentum) 1. Sites of Fe Reduction, Absorption and Transport

T3238fer (Fe-inefficient) and T3238FER (Fe-efficient) tomato plants differ in their ability to utilize Fe and therefore can be used as test genotypes to locate sites of Fe uptake or to characterize changes that occur in roots in response to Fe stress (Fe deficiency). T3238fer does not respond to Fe stress. Release of hydrogen ions and reduction of Fe³⁺ to Fe²⁺ are two primary responses of T3238FER roots to Fe stress. Fe reduction sites were predominately in the young lateral roots, and between the regions of root elongation and maturation of the primary root. The use of BDPS (bathophenanthrolinedisulfonate) to trap Fe²⁺ did not affect the release of H⁺ ions or reduction by T3238FER roots. BPDS did not decrease Fe uptake until it exceeded the Fe concentration in the nutrient solution. A sevenfold increase in BPDS caused a threefold decrease in Fe taken up by the plant. Fe³⁺ is reduced to Fe²⁺ at root sites accessible to BPDS. Adding Zn decreased the response to Fe stress. Iron stress initiates the development of lateral roots, and we propose that most Fe enters the plant through these roots. The iron moves through protoxylem into the metaxylem of the primary root and then to the top of the plant as Fe citrate. Root environmental factors that are competitive or inhibit Fe-stress response, or genotypes that fail to respond to Fe stress, contribute to the development of Fe deficiency in plants.     

Changes in Chromatin Structure Associated with Alzheimer's Disease

Abstract— The enzyme micrococcal nuclease was used to examine the accessibility of chromatin extracted from brains of 13 patients with senile and presenile dementia of the Alzheimer type. Compared with chromatin extracted from brains of 8 patients without neurological signs or brain pathology and brains of 7 patients with nonAlzheimer dementia, Alzheimer chromatin was less accessible to this enzyme-. Reduced accessibility was reflected by a reduced yield of mononucleosomes in comparison with dinucleosomes and larger oligomers. Both neuronal and glial chromatin were found to be similarly affected. The reduced yield of mononucleosomes from Alzheimer chromatin is not due to their increased breakdown, but is probably related to protein associated with the internucleosomal linker region that retards nuclease action. Dinucleosomes isolated from control and Alzheimer nuclease digests were examined for their protein complement. Three perchloric acid-soluble proteins situated in the histone HI region of sodium dodecyl sulfate (SDS) gels were present in elevated levels in Alzheimer dinucleosomes. These results represent the first example of altered chromosomal proteins associated with a diseased state of the brain.     

Dynamic Changes of Intracellular pH in Individual Lactic Acid Bacterium Cells in Response to a Rapid Drop in Extracellular pH

We describe the dynamics of changes in the intracellular pH (pH_i) values of a number of lactic acid bacteria in response to a rapid drop in the extracellular pH (pH_ex). Strains of Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and Lactococcus lactis were investigated. Listeria innocua, a gram-positive, non-lactic acid bacterium, was included for comparison. The method which we used was based on fluorescence ratio imaging of single cells, and it was therefore possible to describe variations in pH_i within a population. The bacteria were immobilized on a membrane filter, placed in a closed perfusion chamber, and analyzed during a rapid decrease in the pH_ex from 7.0 to 5.0. Under these conditions, the pH_i of L. innocua remained neutral (between 7 and 8). In contrast, the pH_i values of all of the strains of lactic acid bacteria investigated decreased to approximately 5.5 as the pH_ex was decreased. No pronounced differences were observed between cells of the same strain harvested from the exponential and stationary phases. Small differences between species were observed with regard to the initial pH_i at pH_ex 7.0, while different kinetics of pH_i regulation were observed in different species and also in different strains of S. thermophilus.     

Biochemical Changes Associated with Zygotic Pine Embryo Development

Johnson, M. A., Carlson, J. A., Conkey, J. H. and Noland, T.L. 1987. Biochemical changes associated with zygotic pine embryodevelopment.—J. exp. Bot. 38: 518–524. At intervals during the period from pre-fertilization to nearmaturation, pine (Pinus resinosa Ait. and Pinus strobus L.)ovules were analysed for several biochemical constituents, andthe results were expressed on a fresh weight basis. Lipid accumulatedin parallel with the growth of the developing seeds. Solubleprotein also accumulated but only in the initial stages of development.ATP content peaked approximately 2 weeks after fertilization,followed about one week later by the energy charge; these peakswere associated with maximal growth stages of the developingembryos. Likewise, peaks of glutathione (GSH) and ascorbic acid(AA), two water-soluble reductants, preceded or coincided withthe ATP maximum. At late stages of seed development, dissectionof the more mature ovules into embryos and gametophytes foranalysis revealed that the ATP, GSH, and AA were more concentratedin the embryonic tissue. On the other hand, this segregationshowed that virtually no proanthocyanidin was located in thedeveloping embryos proper, although they contained other reductants,some of which were probably phenolics. Also, general stainingwith reagents for phenolics and thiols indicated that the formeroccurred primarily in non-embryonic tissue, whereas GSH wasin the embryo per se. These findings are consistent with rolesfor ATP, GSH, and AA in the growth and development of zygoticpine embryos; however, it would appear that lipid and proteinare being stored for subsequent germination events and thatmuch of the phenolic component is segregated from the developingembryo. Key words: Pine, embryogenesis, biochemistry     

Short-term Changes in CO2 Evolution Associated with Nitrogenase Activity in White Clover in Response to Defoliation and Photosynthesis

Direct, continuous measurements of the CO₂ evolution of rootnodules, calibrated by direct measurements of rate of ethyleneproduction, were utilized to determine the short-term responseof nitrogenase activity to defoliation and photosynthesis inwhite clover. Defoliation (removal of all expanded leaflets) generally resultedin a fall in nodulated root respiration within 10 min; mostrespiration associated with nitrogenase activity ceased within1–2 h. Darkening of the shoot also reduced nodulated root respirationwithin 10 min, but the subsequent fall in respiration, althoughof the same magnitude, was slower. The re-illumination of shootslargely reversed these effects. The inhibition of photosynthesisby DCMU largely simulated the effects of darkening the shoots. It is concluded that, in these white clover plants of 100 mgto 2.0 g total weight, current photosynthate provides the primarysource of energy for N₂ fixation. The mobilization of reserveenergy substrate appeared to play only a small role. The minimumtime interval of 10 min between onset of treatment and fallin nodule respiration probably reflects the time taken to exhaustthe assimilate in transit between leaf and nodule. Key words: White clover, N₂ fixation, Defoliation, Photosynthesis