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At least 397 records · Page 22Linked to original sources
PubMed1993

Induction of mammalian DNA topoisomerase I-mediated DNA cleavage and DNA winding by bulgarein.

Bulgarein, a fungal metabolite, induced mammalian topoisomerase I-mediated DNA cleavage in vitro. The cleavage activity of bulgarein was comparable to that of camptothecin at a drug concentration range of 0.025-approximately 5 microM. The DNA cleavage induced by bulgarein was suppressed at concentrations above 12.5 microM. Treatment of a reaction mixture containing bulgarein and topoisomerase I with elevated temperature (65 degrees C) resulted in a substantial reduction in DNA cleavage, suggesting that the topoisomerase I-mediated DNA cleavage induced by bulgarein is through the mechanism of stabilizing the reversible enzyme-DNA "cleavable complex." Intensity of cleaved DNA fragments induced by bulgarein with topoisomerase I was different from that induced by camptothecin. Bulgarein inhibited catalytic activities of both topoisomerase I and topoisomerase II. The changes in absorption spectra of bulgarein in the visible region observed upon addition of increasing amounts of calf thymus DNA indicate that bulgarein interacts with DNA. DNA (un)winding assay by two-dimensional gel electrophoresis showed that bulgarein induced the winding of DNA in the opposite direction to that of an intercalator so that positively supercoiled molecules are produced. Thus, bulgarein represents a new class of drugs which stabilizes the cleavable complex of topoisomerase I and alters the structure of DNA in a manner leading to a tightening of the helical twist.

Animals↗
PubMed1995

Sailing with the winds of change.

The theme for the 1994 Operating Room Nurse Week in the United States was, "We cannot change the wind, but we can adjust the sails." For the sailor, the wind is a powerful force. It must be constantly monitored and the sails adjusted to keep the vessel on course. Occasionally, if conditions are severe, the course may have to be altered.

Female↗
PubMed1984

The large fourth abdominal intersegmental interneuron: a new type of wind-sensitive ventral cord interneuron in locusts.

A large interneuron in Locusta migratoria is described that extends from the fourth abdominal ganglion to the brain. The morphology was revealed by injection of cobaltous ions or Lucifer yellow into the cell. As its cell body lies within the fourth abdominal ganglion it is named A4I1, the first-identified intersegmental interneuron of the fourth abdominal ganglion. This neuron receives input from highly flexible, wind-sensitive hairs on the prosternum, the pronotum, and the head (field 1). Sensory connections with A4I1 are made within the prothoracic ganglion. Stimulation of the receptive field initiates spikes in A4I1 which travel anteriorly and posteriorly from the prothoracic ganglion. Intracellular recording from the axon and the soma shows that the cell membrane becomes inactive within the fourth abdominal ganglion. Spikes could be generated within the fourth abdominal ganglion by current injection into the soma. Occasionally excitatory postsynaptic potentials were observed in a soma recording, but up to now there is no evidence for a second spike initiation site. By intracellular current injection into the soma of the left and right A4I1 cell it is shown that the two cells are not electrically coupled.

Afferent Pathways↗
PubMed1990

The solar wind and human birth rate: a possible relationship due to magnetic disturbances.

Data obtained from the literature on the annual pattern of human conceptions and plasma melatonin at high latitudes indicated that simple annual rhythms do not exist. Instead, prominent semiannual rhythms are found, with equinoctial troughs and solsticial peaks. A prominent semiannual environmental event is the magnetic disturbance induced by the solar wind. The semiannual magnetic disturbances are worldwide, but most pronounced in the auroral zones where the corpuscular radiation enters the atmosphere. Magnetic indices that predominantly reflect these events were obtained from the literature and correlated with the melatonin and conception data. Significant and inverse correlations were found for Inuit conceptions and the melatonin data. The correlations obtained for 48 contiguous states of the United States indicated that only the extreme northern states exhibited this relationship. These data were compared with a previous correlational study in the United States which established that sunshine was correlated with conceptions in the middle latitude and southern states. An hypothesis of dual control by electromagnetic and magnetic energies is proposed: melatonin is a progonadal hormone in humans controlled by both factors, depending on their relative strength. Other studies are reviewed regarding the possible factors involved in determining the annual pattern of human conceptions. Demographic studies of geographic variation in temporal patterns of conceptions, with particular regard to variations of the magnetic fields on the earth's surface, may provide some insight into the efficacy of these different factors.

Birth Rate↗
PubMed2006

Mating system in a low-density natural population of the dioecious wind-pollinated Patagonian cypress.

The mating system of a species is an essential factor that determines the genotypic frequencies of its populations in each generation. Thus, knowledge in this regard is important in the application of practical measures in conservation and forest tree breeding. Austrocedrus chilensis (D.DON) PIC. SER. ET BIZZARRI: is a member of the Cupressaceae native to the Andean-Patagonian Forest of Argentina and Chile with regional economic importance. It is a dioecious tree with pollen and seeds distributed by wind. Isozyme markers were utilized to study the mating system of this species through the survey of individual effective pollen clouds in a natural low-density population. If random mating occurs, effective pollen clouds that pollinate single seed trees are expected to be genetically homogeneous. The classical HardyWeinberg test of panmixia was also performed. Although it failed to reject random mating, the analysis of the pollen clouds showed that this mating pattern does not occur. Evidence of locally distributed heterogeneous pollen clouds is presented. The two methods are critically compared.

Alleles↗
PubMed1982

Neural basis of wind-receptive fields of cockroach giant interneurons.

The pattern of connectivity between the nine most prominent columns of sensory hairs of one cercus and ipsilateral giant interneurons (GIs) 1 and 2 of the cockroach Periplaneta americana was studied using intracellular methods. GI 1, a somewhat directionally selective interneuron receives excitatory synaptic input from all hair columns of the ipsilateral cercus. GI 2, an omni-directional cell, also receives synaptic input from all ipsilateral hair columns. However, for 2 of the 9 columns of hairs the response in GI 2 is greater than in GI 1. This difference in response magnitude represents a real difference in the functional strength of connection and not the number of synapsing afferents since the response in both GI 1 and 2 declines stepwise as the number of hairs tested was reduced one-by-one. Thus, the difference in the shapes of the wind-receptive fields of GI 1 and 2 can be explained by differences in the functional strength of connection of certain identified afferents.

Air Movements↗
PubMed1983

Transient dispersion of dust by wind from nonpoint sources.

This study is concerned with unsteady dispersion of particulates from a nonpoint source such as a storage pile and has been solved analytically. The effects of the particle sizes, the heights of the emission source, wind velocity, and the ground conditions on the downwind particle concentration distribution and deposition are presented using the dust puff model. Results indicate that a significant amount of particle deposition can occur even at locations far away from the emission source. The effect of the height of emission source on the downwind particle concentration is only significant near the emission source.

Air Movements↗
PubMed1989

[Effect of wind and temperature on concentrations of Pb in urban air. I. Example of a location situated under the direct influence of intense traffic].

A simple mathematical relationship has been established between the Pb concentrations in the ambient air in the vicinity of a heavy-traffic road and some meteorological parameters (wind speed and direction, temperature). The application of this relationship permits the interpretation of the variations in concentrations with respect to the time of day and period of the year.

Air Movements↗
PubMed1990

Rain-, wind-, and touch-induced expression of calmodulin and calmodulin-related genes in Arabidopsis.

In response to water spray, subirrigation, wind, touch, wounding, or darkness, Arabidopsis regulates the expression of at least four touch-induced (TCH) genes. Ten to thirty minutes after stimulation, mRNA levels increase up to 100-fold. Arabidopsis plants stimulated by touch develop shorter petioles and bolts. This developmental response is known as thigmomorphogenesis. TCH 1 cDNA encodes the putative Arabidopsis calmodulin differing in one amino acid from wheat calmodulin. Sequenced regions of TCH 2 and TCH 3 contain 44% and 70% amino acid identities to calmodulin, respectively. The regulation of this calmodulin-related gene family in Arabidopsis suggests that calcium ions and calmodulin are involved in transduction of signals from the environment, enabling plants to sense and respond to environmental changes.

Air Movements↗
PubMed1988

Wind-chill and the seasonal variation of cerebrovascular disease.

The hospital admission rates for patients with specific types of stroke were examined for seasonal variation and correlation with meteorological factors. A seasonal variation in admission rates was found for subarachnoid haemorrhage, thrombo-embolic brain infarction and ill-defined cerebrovascular disease. Overall this seasonality was more strongly associated with the computed chilling effect of the atmosphere than with changes in temperature, humidity or wind speed alone. No seasonal variation was observed for admission rates of intracerebral haemorrhage, transient ischaemic attack or occlusion of precerebral arteries. Intracerebral haemorrhage admission rates exhibited a decrease with time. This evidence suggests that seasonal variation in admission rates exists only for certain pathological types of stroke and this is strongly associated with changes in the chilling effect of the atmosphere.

Adult↗
PubMed2005

Response properties of wind-sensitive giant interneurons in the fourth-instar nymphs of the cricket, Gryllus bimaculatus.

The response properties of four wind-sensitive giant interneurons (GIs) 8-1, 9-1, 9-2 and 9-3 in the fourth-instar nymphs of the cricket Gryllus bimaculatus were investigated to clarify the differences and/or similarities of the escape eliciting neural system between nymphs and adults. Air current was presented to the animal from 12 different directions in the horizontal plane, and the intensity-response curves for each GI were obtained at each stimulus direction. The intensity-response curves showed that the response magnitudes of GI 8-1 in the fourth-instar crickets increased with stimulus velocity up to 300 mm/s regardless of the stimulus direction. The response magnitudes of GI 9-1 in the nymphs reached a plateau at a stimulus velocity of 30 mm/s in most stimulus directions. The response magnitudes of GIs 9-2 and 9-3 increased with stimulus velocity up to 300 mm/s regardless of the stimulus direction. The directional sensitivity curves plotted on the basis of threshold velocities revealed that the preferential directions of the GIs were the ipsilateral-side in GI 8-1, the ipsilateral-front and contralateral-rear in GI 9-1, the ipsilateral-rear in GI 9-2 and the ipsilateral-front in GI 9-3, designated with respect to the side of the ventral nerve cord containing the axons. Although the GIs in nymphs occasionally showed higher threshold velocities and larger response magnitudes, the directional sensitivities, i.e., the preferred directions, of the GIs were basically the same with those of adults.

Animals↗
PubMed2005

Estimating fugitive bioaerosol releases from static compost windrows: feasibility of a portable wind tunnel approach.

An assessment of the fugitive release of bioaerosols from static compost piles was conducted at a green waste composting facility in South East England; this representing the initial stage of a programme of research into the influence of process parameters on bioaerosol emission flux. Wind tunnel experiments conducted on the surface of static windrows generated specific bioaerosol emission rates (SBER2s) at ground level of between 13 and 22 x 10(3) cfu/m2/s for mesophilic actinomycetes and between 8 and 11 x 10(3)cfu/m2/s for Aspergillus fumigatus. Air dispersion modelling of these emissions using the SCREEN3 air dispersion model in area source term mode was used to generate source depletion curves downwind of the facility for comparative purposes.

Actinomycetaceae↗
PubMed2003

Postembryonic changes in the response properties of wind-sensitive giant interneurons in cricket.

The intensity-response (I-R) relations for four wind-sensitive giant interneurons (GIs 8-1, 9-1, 9-2 and 9-3) in the fourth-, sixth- and last-instar nymphs of the cricket, Gryllus bimaculatus, were investigated using a unidirectional air current stimulus in order to explore the functional changes of GIs during postembryonic development. Contrary to our expectations, the response properties of GIs in nymphs were largely different from those in adults. The response magnitude of GI 8-1 in an intact cricket decreased during development, i.e. the GI in younger insects showed a larger response magnitude. Although the response magnitudes of GIs 9-1 and 9-2 were almost identical during the nymphal period, a significant decrease was observed after the imaginal ecdysis. During the nymphal period, the response magnitude of GI 9-3 increased according to the developmental stage. However, it decreased significantly after the imaginal ecdysis. We also investigated the response magnitudes of the GIs in nymphs after unilateral cercal ablation. From the results of ablation experiments, the changes in excitatory and/or inhibitory connections between filiform hairs and each GI during postembryonic development were revealed.

Action Potentials↗
PubMed2003

Size-dependent ESS sex allocation in wind-pollinated cosexual plants: fecundity vs. stature effects.

To theoretically investigate the single and compound effects of relative fecundity and relative stature of plants on size-dependent sex allocation (SDS) in wind-pollinated cosexual species, we developed a game model and analysed ESS sex allocation of large and small plants having totally or partially different reproductive resources and different pollen and seed dispersal areas in a population. We found that e.g. when both sized plants have large pollen dispersal areas relative to their seed dispersal areas, which plants are male-biased is largely determined by relative fecundity (t) and relative size of seed dispersal area (k) of the large plants to the small plants: If t >k, large plants tend to be more male-biased even if relative size of pollen dispersal area of large to small plants (l) is smaller than k. If t<k, large plants tend to be more female-biased even if with very large l, e.g. infinity l. Comprehensively, neither very large relative size of pollen to seed dispersal area, nor great expansion of pollen dispersal area with plant size, such as previous models assumed, is important for the increasing maleness with plant size in our model.

Biometry↗
PubMed2003

Various flying modes of wind-dispersal seeds.

The flight behavior of two kinds of seeds dispersed by wind, pappose seeds and winged seeds is observed and the aero- and flight-dynamics of these seeds are analysed. There are four flight modes: parachuting flight by pappi and gliding, rocking and spinning (or auto-rotational) flights utilizing a wing or wings. A bundle of pappi is applied to small seeds of flowering plants, whereas the wing is widely utilized for flowering trees. Various flight modes of winged seeds are strongly dependent on their plan form and the location of their center-of-gravity (CG). Performances as well as flight modes, specifically the rate of descent, are considered to be selective so as to depend on their environmental conditions and their way of life in their own environments.

Models, Biological↗
PubMed2004

Receptor model comparisons and wind direction analyses of volatile organic compounds and submicrometer particles in an arid, binational, urban air shed.

The relationship between continuous measurements of volatile organic compounds sources and particle number was evaluated at a Photochemical Assessment Monitoring Station Network (PAMS) site located near the U.S.-Mexico Border in central El Paso, TX. Sources of volatile organic compounds (VOCs) were investigated using the multivariate receptor model UNMIX and the effective variance least squares receptor model known as Chemical Mass Balance (CMB, Version 8.0). As expected from PAMS measurements, overall findings from data screening as well as both receptor models confirmed that mobile sources were the major source of VOCs. Comparison of hourly source contribution estimates (SCEs) from the two receptor models revealed significant differences in motor vehicle exhaust and evaporative gasoline contributions. However, the motor vehicle exhaust contributions were highly correlated with each other. Motor vehicle exhaust was also correlated with the ultrafine and accumulation mode particle count, which suggests that motor vehicle exhaust is a source of these particles at the measurement site. Wind sector analyses were performed using the SCE and pollutant data to assess source location of VOCs, particle count, and criteria pollutants. Results from this study have application to source apportionment studies and mobile source emission control strategies that are ongoing in this air shed.

Air Pollutants↗
PubMed2001

High light intensity: a critical factor in the wind-tunnel flight of two scarabs, the rose chafer and Japanese beetle.

We analyzed the flight of the rose chafer Macrodactylus subspinosus (F.) (Melolonthinae: Scarabaeidae) and the Japanese beetle Popillia japonica Newman (Rutelinae: Scarabaeidae) in a wind tunnel with controlled humidity, temperature, light, and airflow. The data indicate that an optimum combination of light and temperature dramatically improves their response to lures. Both species took off upwind, oriented to, and contacted the odor source well (40-60%) when light intensity was > 50% of a clear day, temperature was 26-27 degrees C, and relative humidity was 65-75%.

Animals↗