Evidence for the existence of psychrophilic methanogenic communities in anoxic sediments of deep lakes

In order to obtain evidence for the existence of psychrophilic methanogenic communities in sediments of deep lakes that are low-temperature environments (4 to 5 degrees C), slurries were first incubated at temperatures between 4 and 60 degrees C for several weeks, at which time they were amended, or not, with an additional substrate, such as cellulose, butyrate, propionate, acetate, or hydrogen, and further incubated at 6 degrees C. Initial methane production rates were highest in slurries preincubated at temperatures between 4 and 15 degrees C, with maximal rates in slurries kept at 6 degrees C. Hydrogen-amended cultures were the only exceptions, with the highest methane production rates at 6 degrees C after preincubation at 30 degrees C.     

Somatotropic axis in hypocretin-deficient narcoleptic humans: altered circadian distribution of GH-secretory events

Narcolepsy is a sleep disorder caused by impaired hypocretin (orexin) neurotransmission. Growth hormone (GH) secretion may be altered in narcolepsy for various reasons. Slow-wave sleep episodes, which are closely associated with GH-secretory events, are more randomly dispersed over 24 h in narcoleptics. Furthermore, hypocretins may inhibit pituitary GH release. We assessed the function of the somatotropic axis in narcolepsy by deconvolving 24-h (10-min sampling interval) plasma GH concentration profiles in seven hypocretin-deficient narcoleptic patients and in seven healthy controls matched for age, sex, and body weight. Both basal and pulsatile GH secretion rate and secretagogue-induced GH release were similar in patients and controls. However, narcoleptics secreted approximately 50% of their total production during the daytime, whereas controls secreted only 25% during the day. Also, the GH output pattern of narcoleptics was significantly less regular. We propose that hypocretin deficiency disrupts the circadian distribution of hypothalamic GH-releasing hormone release in narcoleptic patients to simultaneously cause daytime GH release and promote their propensity to fall asleep during the day.     

Probing protein-DNA interactions by unzipping a single DNA double helix

We present unzipping force analysis of protein association (UFAPA) as a novel and versatile method for detection of the position and dynamic nature of protein-DNA interactions. A single DNA double helix was unzipped in the presence of DNA-binding proteins using a feedback-enhanced optical trap. When the unzipping fork in a DNA reached a bound protein molecule we observed a dramatic increase in the tension in the DNA, followed by a sudden tension reduction. Analysis of the unzipping force throughout an unbinding "event" revealed information about the spatial location and dynamic nature of the protein-DNA complex. The capacity of UFAPA to spatially locate protein-DNA interactions is demonstrated by noncatalytic restriction mapping on a 4-kb DNA with three restriction enzymes (BsoBI, XhoI, and EcoRI). A restriction map for a given restriction enzyme was generated with an accuracy of approximately 25 bp. UFAPA also allows direct determination of the site-specific equilibrium association constant (K(A)) for a DNA-binding protein. This capability is demonstrated by measuring the cation concentration dependence of K(A) for EcoRI binding. The measured values are in good agreement with previous measurements of K(A) over an intermediate range of cation concentration. These results demonstrate the potential utility of UFAPA for future studies of site-specific protein-DNA interactions.     

Explaining variability in the production of seed and allergenic pollen by invasive <Emphasis Type="Italic">Ambrosia artemisiifolia</Emphasis> across Europe

To better manage invasive populations, it is vital to understand the environmental drivers underlying spatial variation in demographic performance of invasive individuals and populations. The invasive common ragweed, Ambrosia artemisiifolia, has severe adverse effects on agriculture and human health, due to its vast production of seeds and allergenic pollen. Here, we identify the scale and nature of environmental factors driving individual performance of A. artemisiifolia, and assess their relative importance. We studied 39 populations across the European continent, covering different climatic and habitat conditions. We found that plant size is the most important determinant in variation of per-capita seed and pollen production. Using plant volume as a measure of individual performance, we found that the local environment (i.e. the site) is far more influential for plant volume (explaining 25% of all spatial variation) than geographic position (regional level; 8%) or the neighbouring vegetation (at the plot level; 4%). An overall model including environmental factors at all scales performed better (27%), including the weather (bigger plants in warm and wet conditions), soil type (smaller plants on soils with more sand), and highlighting the negative effects of altitude, neighbouring vegetation and bare soil. Pollen and seed densities varied more than 200-fold between sites, with highest estimates in Croatia, Romania and Hungary. Pollen densities were highest on arable fields, while highest seed densities were found along infrastructure, both significantly higher than on ruderal sites. We discuss implications of these findings for the spatial scale of management interventions against A. artemisiifolia.     

A novel task scheduling approach based on dynamic queues and hybrid meta-heuristic algorithms for cloud computing environment

Task scheduling is one of the most challenging aspects to improve the overall performance of cloud computing and optimize cloud utilization and Quality of Service (QoS). This paper focuses on Task Scheduling optimization using a novel approach based on Dynamic dispatch Queues (TSDQ) and hybrid meta-heuristic algorithms. We propose two hybrid meta-heuristic algorithms, the first one using Fuzzy Logic with Particle Swarm Optimization algorithm (TSDQ-FLPSO), the second one using Simulated Annealing with Particle Swarm Optimization algorithm (TSDQ-SAPSO). Several experiments have been carried out based on an open source simulator (CloudSim) using synthetic and real data sets from real systems. The experimental results demonstrate the effectiveness of the proposed approach and the optimal results is provided using TSDQ-FLPSO compared to TSDQ-SAPSO and other existing scheduling algorithms especially in a high dimensional problem. The TSDQ-FLPSO algorithm shows a great advantage in terms of waiting time, queue length, makespan, cost, resource utilization, degree of imbalance, and load balancing.     

Distribution and function of prophage phiRv1 and phiRv2 among Mycobacterium tuberculosis complex

Mycobacterium tuberculosis complex (MTBC) is notorious for causing diseases, such as tuberculosis. Tuberculosis caused by M. tuberculosis remains a global public health concern. Two prophages, phiRv1 and phiRv2, can be found among most MTBC genomes. However, no precise functions have been assigned for the two prophages. In this paper, to find out the function of these two prophages, the distribution and function of phiRv1 and phiRv2 in MTBC genomes were analyzed from multiple omics data. We found that complex insertion, deletion, and reorganization appeared on the locus of two prophages in MTBC genomes; some genes of the two prophages can be translated and are functional from proteomic data; the expression of other prophage genes, such as Rv1577c, Rv2650c, Rv2652c, Rv2659c, and Rv2658c, can vary with environmental stresses and might enhance the fitness of MTBC. These data will facilitate our in-depth understanding of their function.     

Poly(alpha-alkyl gamma-glutamate)s of microbial origin. 2. On the microstructure and crystal structure of poly(alpha-ethyl gamma-glutamate)s

The stereochemical microstructure and crystalline structure of nearly racemic poly(alpha-ethyl gamma,DL-glutamate) obtained by esterification of biosynthetic poly(gamma-glutamic acid) were examined by NMR, DSC, and powder X-ray diffraction. The two enantiomerically pure poly(alpha-ethyl gamma-glutamate)s, as well as the racemic stereocopolymers with random and alternating microstructure, were prepared by chemical synthesis and studied in parallel to help in the interpretation of the data. The (13)C NMR analysis revealed that biosynthetic poly(alpha-ethyl gamma,DL-glutamate) consists of a block stereocopolymer accompanied by minor amounts of a mixture of the two optically pure homopolymers. The polymer is crystalline, with a degree of crystallinity and crystal structure essentially similar to those displayed by the optically pure polymers but clearly different from the alternating copolymer. Conversely, the racemic stereocopolymer with a random microstructure prepared by chemical synthesis is amorphous. The crystal structure of the racemic mixture of the D- and L-homopolymers seems to be very close to that of the biosynthetic stereocopolymer, although some indications suggesting the existence of a stereocomplex were found.     

Cadmium,nickel, copper,and zinc influence on microfilament organization in Arabidopsis root cells

The plant cytoskeleton orchestrates such fundamental processes in cells as division, growth and development, polymer cross-linking, membrane anchorage, etc. Here, we describe the influence of Cd²⁺, Ni²⁺, Zn²⁺, and Cu²⁺ on root development and vital organization of actin filaments into different cells of Arabidopsis thaliana line expressing GFP-FABD2. CdSO₄, NiSO₄, CuSO₄, and ZnSO₄ were used in concentrations of 5–20 µM in this study. It was found that Cd, Ni, and Cu cause dose-dependent primary root growth inhibition and alteration of the root morphology, whereas Zn slightly stimulates root growth and does not affect the morphology of Arabidopsis roots. This growth inhibition/stimulation correlated with the various sensitivities of microfilaments to Cd, Ni, Cu, and Zn action. It was established that Cd, Ni, and Cu affected predominantly the actin filaments of meristematic cells. Cells of transition and elongation zones demonstrated strong actin filament sensitivity to Cd and Cu. Microfilaments of elongating root cells were more sensitive to Ni and Cu. Although Cd, Ni, and Cu stimulated root hair growth after long-term treatment, actin filaments were destroyed after 1 h exposure with these metals. Zn did not disrupt native actin filament organization in root cells. Thus, our investigation shows that microfilaments act as sensitive cellular targets for Cd, Ni, and Cu. More data on effects on native actin filaments organization would contribute to a better understanding of plant tolerance mechanisms to the action of these metals.     

Abscisic acid accumulation in the roots of nutrient-limited plants: its impact on the differential growth of roots and shoots

We describe the involvement of abscisic acid (ABA) in the control of differential growth of roots and shoots of nutrient limited durum wheat plants. A ten-fold dilution of the optimal concentration of nutrient solution inhibited shoot growth, while root growth remained unchanged, resulting in a decreased shoot/root ratio. Addition of fluridone (inhibitor of ABA synthesis) prevented growth allocation in favour of the roots. This suggests the involvement of ABA in the redirecting of growth in favour of roots under limited nutrient supply. The ABA content was greater in shoots and growing apical root parts of starved plants than in nutrient sufficient plants. Accumulation of ABA in shoots of nutrient deficient plants was linked to a decrease in leaf turgor. Increased flow of ABA in the phloem apparently contributed to the accumulation of ABA in the apical part of the roots. Thus, partitioning of growth between roots and shoots of wheat plants limited in mineral nutrients appears to be modulated by accumulation of ABA in roots. This ABA may originate in the shoots, where its synthesis is stimulated by the loss of leaf turgor.