Influence of quasi-spherical polarization on results of bioelectromagnetic studies

Abstract

One of the most interesting questions in bioelectromagnetic and compatibility studies is differences between results of experiments performed in different labs in “identical” conditions, especially in bioelectromagnetics studies. A reason of these differences may be due to differences in investigated objects, particularly in in vivo experiments. However, the author, as engineer, would like to focus the readers' attention on the technical aspects of exposure systems namely: presence and role of mutual interaction between the object under test and the exposure system, interaction between exposure objects, the role of polarization and the similarity of real-life exposure to those applied in experiments, etc. All these factors may change the results of experiments and lead to false conclusions.     

A new solution for biomedical experiments

This article discusses mutual interactions phenomena especially in the case of Transverse ElectroMagnetic (TEM) cell applications as an exposure system in technical and biomedical studies. Problem of mutual interactions between tested objects placed in the electromagnetic field (EMF) is described. A new device for exposure system is presented. Its role is elimination of mentioned harmful phenomenon that leads to falsifications of results.     

TrackBeam, a simple tool for estimating potential exposure to the solar beam underneath tree canopies

A simple tool, TrackBeam, for rapid in situ estimates of potential exposure to the solar beam of objects underneath tree canopies is presented, tested and demonstrated to be useful in insect conservation studies. The tool can be used whenever accurate data on sun exposure is of use e.g., in ecological studies of saproxylic insects. TrackBeam draws upon the principles behind the analysis of hemispherical photographs but its use is much less dependent on the weather at the time of sampling. It may be used for detecting canopy openings in directions corresponding to the solar path. Based on this, periods of time with potential beam exposure and/or the proportion of sky that is not obscured by canopy for objects such as dead wood may be estimated. The results of using TrackBeam compares well between operators and with the corresponding results of analysed hemispherical photographs. Results are presented which show that TrackBeam was successfully used to characterise the habitat light requirements of the saproxylic beetle Melanotus castanipes (Coleoptera: Elateridae).     

目标和干扰子之间的拓扑性质差异可以削弱拥挤效应

"拥挤效应"被认为是外周视觉物体辨认过程中的一个重要瓶颈.它是指当目标被干扰子包围,在外周视野呈现时,观察者辨认目标的能力被大大削弱,尤其是当目标和干扰子之间存在某种相似性时.许多研究分别试图在不同层次上提出解释这一现象的机制.本文通过三个实验,使用了不同的视觉刺激图形的辨认任务(例如,三角形和箭头的朝向判断、数字和字母的辨认以及S形图形的朝向辨认),测量了目标和干扰子之间中心距离的阈值,结果一致地发现,当目标和干扰子之间存在拓扑性质差异(洞的个数差异)时,拥挤效应会显著降低,并且排除了目标和干扰子之间的主观相似性、形状和面积差异等可能的因素.从知觉组织的角度验证了当目标和干扰子之间存在拓扑性质差异时,拥挤效应会显著降低,这是首次发现的一个影响拥挤效应的新的维度.本文结果不仅为拥挤效应的机制提供了一个新的解释,也为大范围首先拓扑知觉在知觉物体形成中的作用提供了支持性证据.     

Picture processing in tufted capuchin monkeys (Cebus apella)

Although pictures are frequently used in place of real objects to investigate various aspects of cognition in different non-human species, there is little evidence that animals treat pictorial stimuli as representations of the real objects. In the present study, we carried out four experiments designed to assess picture processing in tufted capuchin monkeys (Cebus apella), using a simultaneous Matching-to-Sample (MTS) task. The results of the first three experiments indicate that capuchins are able to match objects with their colour photographs and vice versa, and that object-picture matching in this New World monkey species is not due to picture-object confusion. The results of the fourth experiment show that capuchins are able to recognize objects in their pictures with a high level of accuracy even when less realistic images, such as black-and-white photographs, silhouettes and line drawings, are employed as bi-dimensional stimuli. Overall, these findings indicate that capuchin monkeys are able to establish a correspondence between the real objects and their pictorial representations.     

Differences in biological and behavioural characteristics of Harmonia axyridis (Coleoptera: Coccinellidae) according to colour patterns of elytra

Samples of overwintering populations of Harmonia axyridis were classified into five colour patterns, succinea 1, succinea 2, conspicua, spectabilis and axyridis. Generally, the succinea 1 colour pattern was dominant at six collecting sites in Daejon and Chungnam provinces of Korea and their occurrence proportion was over 50%. Non‐melanic forms such as succinea 1 and 2 were noted in about 90% of collected individuals. On the other hand, conspicua and spectabilis as melanic forms were dominant in the laboratory. One hypothesis is that the difference between field and laboratory populations is related to non‐random mating and environmental conditions. Practically, in mate‐choice experiments, most colour pattern ladybirds seemed to mate with the melanic form, especially the conspicua form. The body size (length) of H. axyridis in colour patterns was slightly different, but in females, there was no significant difference among colour patterns. However, both lengths of males were significantly different among colour patterns. In reproductive ability (fecundity), there was no difference among colour patterns.     

Does plasmolysis increase the drought tolerance of plant cells?

Summary Iljin's experiments withRhoeo discolor, cabbage and red beet which seemed to demonstrate increased drought resistance of plasmolysed tissue have been repeated, but his results could not be confirmed. The tissue plasmolysed in sucrose solutions, died either during stepwise plasmolysis and deplasmolysis or else later on, during exposure to unsaturated air within one or two days, even at the highest humidities. Iljin's error was apparently produced by a wrong interpretation of his tests of viability: the plasma of his dead cells did not disintegrate and retained anthocyanin by tonoplast plasmolysis.Plasmolysis proved harmful to all three objects investigated.In view of these results and earlier criticism of Iljin's analogous experiments on frost resistance by others, all experimental evidence produced in support of Iljin's mechanical theory of drought resistance should be reexamined.     

EFFECTS OF ACIDIC SOLUTIONS ON SEXUAL REPRODUCTION OF PTERIDIUM AQUILINUM

Experiments were performed to determine the effects of acidic solutions on spermatozoid motility and fertilization of gametophytes of Pteridium aquilinum. Buffered solutions (0.0025 m ) were used to simulate exposures to acidic precipitation for up to a 3.5 hr exposure. Experimental results suggest that the spermatozoid population can be subdivided into several groups with respect to pH sensitivity; about 25% spermatozoids are immobile one min after exposure to pH 6.1 buffer while about an equal percentage remain motile after 30 min exposure to buffer of pH 5.1. Between these two response extremes are two other subpopulations. One is quite sensitive to pH but shows some recovery if pH is between 5.6 and 6.1, while the second subpopulation does not seem to exhibit any motility recovery at all but is more resistant to acidity than the first subpopulation. To complement experiments that evaluate spermatozoid responses, experiments were performed to view the process of fertilization under controlled environmental conditions as well as under the canopy of a forest. Fertilization of gametophytes in uncovered petri dishes under a forest canopy was similar to results in aseptic culture after gametophytes were exposed to various pH levels and 86.6 μM sulfate. Although there were some differences between results obtained under aseptic culture conditions and cultures maintained under a forest canopy, it is evident that a lower buffer pH decreased fertilization. Fertilization at pH 4.5 and 3.6 was about one-half that occurring at pH 6.1. Fertilization in gametophytes exposed to pH 3.0 was about 10-20% of that occurring at pH 6.1. Addition of 86.6 μM sulfate decreased fertilization under all culture conditions. These experimental results suggest that fertilization in P. aquilinum may be used as a bioindicator of contaminants in rainwater. The results demonstrate that spermatozoid motility (and the process of fertilization) is more acid sensitive than gametophytic and sporophytic tissues.     

Insecticidal activity of Poppy (Papaver somniferum L.) seed oil against cowpea weevil (Callosobruchus maculatus F.) in stored cowpea

In this study, the insecticidal effect of Poppy (Papaver somniferum) seed oil was investigated against Callosobruchus maculatus (Bruchidae) in cowpea, at different concentrations and exposure time. The Poppy seed oil at 2, 4, 6, 8 and 10?ml/kg was tested against adults of C. maculatus, and the mortality was counted after 24, 48 and 72?h of exposure. All tests were conducted at 27–30?°C and 65?±?5% r.h. The experiments were carried out based on the factorial experiment by randomized complete design with four replications. Twenty-five insects with 0–24?h old were used for each replication. The effect of Poppy seed oil on the reduction of emergence of insects in next generation (F₁) was also assayed. The results of experiments indicate the significant differences between concentrations and exposure time (p?<?0.0001), and the increase of concentrations and exposure time increased mortality. The amount of mortality at high concentrations was remarkable, and highest mortality rate (96.91%) was recorded at 10?ml/kg, after 72?h of exposure. The application of oil significantly reduced F₁ progeny production and even at lowest concentration (2?ml/kg), the amount of F₁ production was reduced more than 70%, compared with control treatment. Complete (100%) reduction in progeny production was recorded at the rates of 8 and 10?ml/kg. The results of seed germination assay showed no significant differences between control and treated seed, and no harmful effect was observed on the seed germination. These results proved that Poppy seed oil can be used as a controlling agent of storage pests, especially C. maculatus, although more detailed studies are necessary.     

Does enemy release matter for invasive plants? evidence from a comparison of insect herbivore damage among invasive,non-invasive and native congeners

One of the most popular single-factor hypotheses that have been proposed to explain the naturalization and spread of introduced species is the enemy release hypothesis (ERH). One ramification of the ERH is that invasive plants sustain less herbivore damage than their native counterparts in the invaded range. However, introduced plants, invasive or not, may experience less herbivore damage than the natives. Therefore, to test the role of natural enemies in the success of invasive plants, studies should include both invasive as well as non-invasive introduced species. In this study, we employed a novel three-way comparison, in which we compared herbivore damage among native, introduced invasive, and introduced non-invasive Eugenia (Myrtaceae) in South Florida. We found that introduced Eugenia, both invasive and non-invasive, sustained less herbivore damage, especially damage by oligophagous and endophagous insects, than native Eugenia. However, the difference in insect damage between introduced invasive and introduced non-invasive Eugenia was not significant. Escape from herbivores may not account for the spread of invasive Eugenia. We would not have been able to draw this conclusion without inclusion of the non-invasive Eugenia species in the study.     

A nonhuman primate's perception of object relations: experiments on cottontop tamarins, Saguinus oedipus

Objects in nature often have spatial and functional relationships with other objects. For example, fruit may be connected to tree branches, bushes sometimes function as landmarks for home, and stones are functionally associated with nuts when they are used to crack the nuts open. Although animals may use the spatial and functional relationships between specific objects, it is important for ethologists interested in cognitive mechanisms to ask whether animals understand the spatial relationship between objects in a more general and abstract way. In this experiment, we ask whether a small New World monkey, the cottontop tamarin, is capable of perceiving the abstract relational concept of ‘connectedness’. Using a traditional operant paradigm, subjects were required to press one button to images with connected objects, and another button to images with separated objects. In Phase 1 of the experiment, subjects received training with only one connected and one separated image. Following training, probe images were presented in which features such as colour, texture and shape were systematically manipulated to determine which features were more important in stimulus classification. Accuracies and reaction times of responses were recorded. On the basis of their performance, the tamarins appeared to recognize that changes in the colour or texture of two objects plays no functional role in determining whether such objects are connected or separated. In contrast, changes in the shape and distance between two objects does play an important functional role, and the tamarins appeared to be sensitive to such changes. In Phase 2, subjects received training with a larger set of images. After this training, classification accuracy remained significantly above chance with most probes, suggesting that the tamarins had acquired a more general connectedness concept. In Phase 3, novel images were presented. Classification accuracy was significantly above chance for many of the novel images. Overall, results suggest that tamarins perceive spatial relationships between stimuli to some extent and can classify images based in part on their spatial relationship. Other recent experiments have shown that cottontop tamarins respond to spatial relationships even better than in the current experiment when they have to act directly on the objects. The difference between these results suggests that tamarins perceive the spatial relationships between objects more readily in the context of an ecologically valid problem.     

The effect of 100 mT SMF on activation of the hsp70 promoter in a heat shock/luciferase reporter system

Human exposure to magnetic fields, increased through use of new technologies like magnetic resonance imaging (MRI), has prompted investigations into possible effects of static magnetic fields (SMFs) on cellular processes. However, controversy still remains between many studies, which likely results from a lack of uniformity across experimental parameters, including the length of magnetic field exposure, the strength of the magnetic field, and the cell type or organism under investigation. The purpose of this research was to monitor effects of SMF exposure using real‐time luminescence photometry. The study investigated the potential interaction of a 100 mT SMF on a heat shock protein (hsp70)/luciferase reporter construct in stably transfected NIH3T3 cells. Changes in heat shock promoter activation following 100 mT SMF exposure were analyzed and detected as bioluminescence in real‐time. Two heat parameters were considered in combination with sham‐ and 100 mT‐exposed experiments: no heat or 1,800 s heat. As expected, there was a significant increase in bioluminescence in response to 1,800 s of heat alone. However, no significant difference in average hsp70 promoter activation between sham and 100 mT experiments was observed for no heat or 1,800 s heat experiments. Therefore, a 100 mT SMF was shown to have no effect on the activation of the heat shock protein promoter during SMF exposure or when SMF exposure was combined with a heat insult. J. Cell. Biochem. 108: 956–962, 2009. © 2009 Wiley‐Liss, Inc.     

Exploratory behavior and learning in laboratory marmosets (Callithrix jacchus jacchus): Comparisons between experimental-cage and home-cage activity

In this paper I examine exploratory behavior and learning in two groups of common marmosets (Callithrix jacchus jacchus), both living under laboratory conditions. The main aim of my studies was to compare behavior occurring in an experimental testing situation with home-cage behavior, and to assess conditions under which exploration is enhanced. One group of marmosets was tested individually in an experimental room away from a larger animal holding room, and a second group was observed in their own home cages, surrounded by other marmosets. Marmosets in both groups were given the opportunity to learn simple tasks, such as pressing a lever for food or jumping on to a wire grid to open a door and see a neighbouring marmoset, and were provided with sets of novel or familiar objects to encourage play and exploration. In the isolated experimental cage, marmosets which learnt a lever-pressing task showed higher general activity levels than controls; in the home cages the mere addition of novel objects resulted in enhancements in exploratory behavior (measured in terms of contacts with the objects). Although the activities associated with learning tended to decline over time, the novel objects remained a constant interest throughout the experiment. The results have implications for maintaining marmosets in captivity, especially in situations when they are housed separately.     

Prodigiosin from <Emphasis Type="BoldItalic">Vibrio</Emphasis> sp. DSM 14379; A New UV-Protective Pigment

Pigments such as melanin, scytonemin and carotenoids protect microbial cells against the harmful effects of ultraviolet (UV) radiation. The role in UV protection has never been assigned to the prodigiosin pigment. In this work, we demonstrate that prodigiosin provides a significant level of protection against UV stress in Vibrio sp. DSM 14379. In the absence of pigment production, Vibrio sp. was significantly more susceptible to UV stress, and there was no difference in UV survival between the wild-type strain and non-pigmented mutant. The pigment’s protective role was more important at higher doses of UV irradiation and correlated with pigment concentration in the cell. Pigmented cells survived high UV exposure (324 J/m²) around 1,000-fold more successfully compared to the non-pigmented mutant cells. Resistance to UV stress was conferred to the non-pigmented mutant by addition of exogenous pigment extract to the growth medium. A level of UV protection equivalent to that exhibited by the wild-type strain was attained by the non-pigmented mutant once the prodigiosin concentration had reached comparable levels to those found in the wild-type strain. In co-culture experiments, prodigiosin acted as a UV screen, protecting both the wild-type and non-pigmented mutants. Our results suggest a new ecophysiological role for prodigiosin.     

Sexual difference in the photoperiodic induction of pupal diapause in the flesh fly Sarcophaga similis

The flesh fly Sarcophaga similis enters pupal diapause in response to short days, but averts diapause under long days. This species shows a sexual difference in the photoperiodic induction of diapause, with females having shorter critical daylength than males. Here, we proposed two hypotheses to explain this sexual difference. First, we proposed a sexual difference in the qualitative evaluation of photoperiods. This hypothesis assumes under the external coincidence model that although the photoinducible phase of both sexes locates at late scotophase, in males, it locates at a slightly earlier phase. However, the results of night interruption experiments clearly ruled out this hypothesis. Because we verified that S. similis evaluated photoperiods quantitatively, we next proposed a sexual difference in the quantitative evaluation of photoperiods. This hypothesis incorporates concepts of a hypothetical substance accumulation that shows a diapause‐inducing effect and an internal threshold that serves as a reference to determine the diapause/nondiapause developmental program. In long‐day exposure experiments and night interruption experiments, females consistently showed a lower incidence of diapause than males. Thus, the present study data satisfactorily meet the second hypothesis, that is a sexual difference in the quantitative evaluation of photoperiods exists in S. similis.     

ROS and pentose phosphate pathway: mathematical modelling of the metabolic regulation in response to xenobiotic-induced oxidative stress and the proposed Impact of the gluconate shunt

Abstract

Elevated intracellular levels of reactive oxygen species (ROS), e.g. resulting from exposure to xenobiotics, can cause severe damages. Antioxidant defence mechanisms, which involve regulation of enzyme activities, protect cells to a certain extent. Nevertheless, continuous or increased exposure can overwhelm this system resulting in an adverse cellular state. To simulate exposure scenarios and to investigate the transition to an adverse cellular state, a mathematical model for the dynamics of ROS in response to xenobiotic-induced oxidative stress has been developed. It is based on exposure experiments of human urothelial cells (RT4) to the nitrated polycyclic aromatic hydrocarbon 3-nitrobenzanthrone (3-NBA), a component of diesel engine exhaust, and takes into account the following metabolic pathways of the antioxidant defence system: glutathione redox cycle scavenging directly ROS, the pentose phosphate pathway and the gluconate shunt as NADPH supplier and the beginning of glycolysis. In addition, ROS generation due to the bioactivation of 3-NBA has been implemented. The regulation of enzyme activities plays an important role in the presented mathematical model. The in silico model consists of ordinary differential equations on the basis of enzyme kinetics and mass action for the metabolism of 3-NBA. Parameters are either estimated from performed in vitro experiments via least-squares fitting or obtained from the literature. The results underline the importance of the pentose phosphate pathway to cope with oxidative stress and suggest an important role of the gluconate shunt during low-dose exposure.     

Guild structure in water mites (Unionicola spp.) inhabiting freshwater mussels: choice,competitive exclusion and sex

Summary Unionicolid water mites inhabit freshwater unionid mussels during the nymphal and adult stages of their life-cycle. Regular sampling of mussels from two sites in St. Mark's River, Fl. established that each of four species of water mite (Unionicola abnormipes, U. fossulata, U. serrata and U. formosa) occurred mainly in one or two of the mussel species available at each site.The role of preference for particular mussel species during host location was assessed for the first three mite species by choice experiments, in which mites were offered different mussel species simultaneously. In five out of six experiments, mites entered normally unused mussels as often as they did normally used ones. Additionally, a sexual difference in choice was found for U. fossulata, with males preferring one mussel species and females showing no preference. One mussel species, (Anodonta imbecilis), normally unused but chosen by mite species during the lab. experiments, is inhabited exclusively by the fourth mite species, U. formosa, in the field. An experiment showed that U. formosa excludes other mite species aggressively from Anodonta imbecilis.The results illustrate the sometimes misleading nature of simple sampling data as an indication of host specificity or host preference in parasites. They suggest also that the population dynamics of some parasites might be more fruitfully compared to unrelated, free-living species than to other parasites.     

Mind the gap: the minimal detectable separation distance between two objects during active electrolocation

In a food‐rewarded two‐alternative forced‐choice procedure, it was determined how well the weakly electric elephantnose fish Gnathonemus petersii can sense gaps between two objects, some of which were placed in front of complex backgrounds. The results show that at close distances, G. petersii is able to detect gaps between two small metal cubes (2 cm × 2 cm × 2 cm) down to a width of c. 1·5 mm. When larger objects (3 cm × 3 cm × 3 cm) were used, gaps with a width of 2–3 mm could still be detected. Discrimination performance was better (c. 1 mm gap size) when the objects were placed in front of a moving background consisting of plastic stripes or plant leaves, indicating that movement in the environment plays an important role for object identification. In addition, the smallest gap size that could be detected at increasing distances was determined. A linear relationship between object distance and gap size existed. Minimal detectable gap sizes increased from c. 1·5 mm at a distance of 1 cm, to 20 mm at a distance of 7 cm. Measurements and simulations of the electric stimuli occurring during gap detection revealed that the electric images of two close objects influence each other and superimpose. A large gap of 20 mm between two objects induced two clearly separated peaks in the electric image, while a 2 mm gap caused just a slight indentation in the image. Therefore, the fusion of electric images limits spatial resolution during active electrolocation. Relative movements either between the fish and the objects or between object and background might improve spatial resolution by accentuating the fine details of the electric images.     

Peroxisomal proteomic approach for protein profiling in blue mussels (Mytilus edulis) exposed to crude oil

Peroxisomal proteomic protein profiles of exposure to marine pollution have been recently introduced in biomonitoring experiments. However, laboratory experiments to study the independent effect of common pollutants are needed to define a minimal protein expression signature (PES) of exposure to a specific pollutant. The aim of this study was to obtain PESs in blue mussels (Mytilus edulis) exposed to two different crude oil mixtures for future application in biomonitoring areas affected by oil spills. In the study, peroxisome-enriched fractions from digestive gland of M. edulis (L., 1758) were analysed by two-dimensional fluorescence difference electrophoresis (DIGE) and mass spectrometry (MS) after 3 weeks of exposure to crude oil mixtures: crude oil or crude oil spiked with alkylated phenols (AP) and extra polycyclic aromatic hydrocarbons (PAH) in a laboratory flow-through system. A minimal PES composed by 13 protein spots and unique PESs of exposure to the two different mixtures were identified. A total of 22 spots from the two-dimensional maps that had shown a significant increase or decrease in abundance in each of the exposed groups exposed were analysed. The hierarchical clustering analysis succeeded in discriminating the exposed groups from the control groups based on the unique PES. The PESs obtained were consistent with protein patterns obtained in previous field experiments. The results suggest that the protein profiles obtained by peroxisomal proteomics could be used to assess oil exposure in marine pollution assessments.     

Meta-analyses of studies on the association between electromagnetic fields and childhood cancer

During the last 15 years several studies have investigated a possible relationship between exposure to electromagnetic fields (EMF) and childhood cancer. There is considerable variation between these studies with respect to methods of exposure assessment and reported results. Methods of exposure assessment range from simple visual criteria to costly and time consuming measurements or estimations of electric flux density. Additional individual refinements further hinder the comparability of results. We carried out several meta-analyses of data published so far taking into account the heterogeneity between studies as far as possible. Our particular interest was to investigate a potential dose-response-like relationship by comparing analyses for different cut-off points of exposure. Our meta-analyses suggest a marginal association between all cancer diagnoses combined and EMF exposure assessed by the two-level wire code (odds ratio, OR= 1.37, 95% confidence interval, CI: 0.94–2.00). Based on this criterion a significant effect was found for cases of leukemia (OR= 1.66, CI: 1.11–2.49) but not for central nervous system (CNS) tumors (OR= 1.5, CI: 0.69–3.26) or lymphomas (OR= 1.32, CI: 0.52–3.37). A significant increase in overall cancer risk with increasing stages of the four-level wire code (P=0.003) could not be confirmed when data of the initial study performed by Wertheimer and Leeper were excluded (P=0.17). When the exposure criterion was based on distance to the transmission line, estimated ORs for all cancers combined and for leukemias increased with distances decreasing from 100 to 25 m. Those analyses incorporating data on measured or calculated EMFs demonstrated also an increase of overall cancer risk with higher cut-off points. However, regarding individual diagnoses, this finding was reflected only in the group of brain tumors. One possible explanation for the high degree of heterogeneity between studies - especially with respect to methods of exposure assessment and choice of the respective cutpoint relevant for an increase in cancer risk - could be that published cut-off points were not always chosen in advance, but were selected because in exploratory analyses the most striking results were obtained with these specific cut-off values. Should this speculation be true at least partially, any meta-analysis will yield a false-positive finding. Further results of comparable studies with strictly a priori planned analyses are necessary to properly investigate a possible link between EMF and childhood cancer.