Zero Magnetic Field Effect Observed in Human Cognitive Processes

In our previous works, we reported that compensation of the geomagnetic field to a level less than 0.4?μT (“zero magnetic field,” or ZMF) affected human cognitive processes. ZMF exposure increased the number of errors and the task processing time by 2.4% in average. However, in the array of the magnetic effects calculated from the experimental data, some readings have been found to deviate from the mean magnetic effect by more than three standard deviations. This finding could give rise to doubt as to whether the magnetic effect observed was a mere sequence of the presence of such unlikely data values. In the present work we examine the results of the unlikely data elimination and show that the corrected magnetic effect in tested humans remains statistically significant, though at a reduced magnitude 1.5%.     

LIFE IN ZERO MAGNETIC FIELD. III. EFFECT ON ZINC AND COPPER IN HUMAN BLOOD SERUM DURING IN VITRO AGING

The purpose of the work was to further investigate the effect of zero magnetic field (ZMF) on the concentration of ions in the human blood compared to the effect of the normal geomagnetic field (GMF). We have investigated the total Zn and Cu concentrations in the blood serum during in vitro aging of blood. The investigation was carried out both on blood from healthy donors as well as from chronic bronchial asthma (BA) patients. Blood samples were kept for 48 hours in a Helmholtz coil compensating system to remove the static component of the geomagnetic field, at room temperature. We found that zinc concentrations in the plasma were not significantly influenced by the exposure to ZMF compared to GMF for both healthy and pathological samples. In contrast, copper concentration was found to be significantly sensitive to the magnetic environment. Healthy blood showed a slight loss of copper from the blood serum in GMF, which further increased in ZMF. BA pathology is characterized by four distinct types of disease, which showed both qualitative and quantitative distinctive sensitivity to the magnetic environment, as compared to healthy blood. The aging effect appeared to be slowed down for most of the BA types of pathologies. These results point to the sensitivity of ion binding to serum proteins and/or transport through cell membranes in the magnetic environment, in our case in the absence of the normal geomagnetic field.     

LIFE IN ZERO MAGNETIC FIELD. III. ACTIVITY OF ASPARTATE AMINOTRANSFERASE AND ALANINE AMINOTRANSFERASE DURING IN VITRO AGING OF HUMAN BLOOD

We investigated the activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the serum of human blood during in vitro aging in normal and zero magnetic field (ZMF) for up to 72 hr at room temperature. We found a 24–31% apparent decrease of the enzymes' activities in ZMF conditions compared to controls aging in the normal geomagnetic field. The presence of these enzymes in the serum is mainly due to hemolysis. However, hemolysis is stronger in ZMF conditions. Therefore, the amount of enzymes released into the serum is correspondingly higher in these conditions. This leads to the conclusion that AST and ALT activities diminished by ZMF to a much greater extent than the apparent effect. For example, a 72-hr aging leads to a minimum five times reduction in the enzymatic activity in the blood serum. The loss of activity could be explained by denaturation and degradation processes, which proceeded more rapidly in ZMF conditions.     

Alcohol tolerance: An ecological parameter in the relative success of Drosophila melanogaster and Drosophila simulans

Summary Laboratory experiments have shown D. melanogaster adults to be more tolerant to alcohol in the environment than D. simulans, with the females being more tolerant than the males of their species. Larval development on alcohol supplemented media also demonstrated an increased tolerance by D. melanogaster although the effect was not as clear cut as for the adult survival. Oviposition choice experiments demonstrated a marked rejection of alcohol impregnated laying sites by D. simulans when compared to standard medium sites. D. melanogaster showed a slight preference for alcohol supplemented sites.Collections in the maturation cellar of a vineyard produced, with the exception of a single D. simulans fly, entirely D. melanogaster adults while larvae and pupae from the cellar were also all D. melanogaster. Away from the alcohol resource, outside the cellar, both species were collected with D. simulans being the more common. However, the outside distribution of the two species was affected by alcohol fumes during vintage, as was the distribution of the sexes of D. melanogaster, with the more tolerant species or sex being closer to the source. The field results were thus in agreement with the laboratory predictions that D. melanogaster is better able to utilize an alcohol resource than D. simulans.     

Non-disjunction mutations inDrosophila exposed to magnetic fields

The frequency of XO mutations inDrosophila melanogaster was significantly higher than normal in magnetic field exposed, immature males, than in exposed, mature males. Mutation levels increased with magnetic field strength. Intercellular rings of black magnetic particles were formed in the high magnetic flux region of dorsally exposed, early stage pupae and to a lesser degree in the abdomen of young adult females. Orientation of minute, chromosome associated, magnetic domains within the microenvironment of the developing organism was believed to alter oxidative processes within maturing X⁺ sperm which during fertilization were incompatible with and destructive to an X^w chromosome in the zygote.     

The neuro-ecology of resource localization in Drosophila: Behavioral components of perception and search

From the moment an adult fruit fly ecloses, its primary objective in life is to disperse and locate the source of an attractive food odor upon which to feed and reproduce. The evolution of flight has greatly enhanced the success of fruit flies specifically and insects more generally.1 Control of flight by Drosophila melanogaster is unequivocally visual. Strong optomotor reflexes towards translatory and rotational visual flow stabilize forward flight trajectory, altitude, and speed. 2, 3 The steering responses to translatory and rotational flow in particular are mediated by computationally separate neural circuits in the fly’s visual system,4 and gaze-stabilizing body saccades are elicited by threshold integration of expanding visual flow .5 However, visual information is not alone sufficient to enable a fruit fly to recognize and locate an appropriately smelly object due in part to the relatively poor resolution of its compound eyes. Rather, the animal uses an acute sense of smell to actively track odors during flight. Without a finely adapted olfactory system, the fly’s remarkable visual capabilities are for naught. The relative importance of vision is apparent in the cross-modal fusion of the two modalities for stable active odor tracking.6, 7 Olfactory processing in Drosophila is shaped by ecological and functional forces which are inextricably linked. Thus physiologists seeking the functional determinants of olfactory coding as well as ecologists seeking to understand the mechanisms of speciation do well to consider each others’ point of view. Here we synthesize a broad perspective that integrates across ultimate and proximate mechanisms of odor tracking in Drosophila.     

The Ability of Coptera haywardi (Ogloblin) (Hymenoptera: Diapriidae) to Locate and Attack the Pupae of the Mediterranean Fruit Fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), under Seminatural Conditions

In Latin America, the diapriid Coptera haywardi (Ogloblin) attacks the pupae of tephritid fruit flies. Anastrepha spp. are among its natural hosts, but in the laboratory it also develops in the exotic Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Field cage tests demonstrated that C. haywardi could locate and parasitize Mediterranean fruit fly pupae under seminatural conditions as found in a Guatemalan coffee plantation. A mean of 18.3% of the pupae buried artificially at depths of 5 mm were parasitized by C. haywardi, while those buried at 15 mm suffered 3.2% parasitism. In a laboratory experiment, larvae that buried themselves to pupate were not significantly more likely to be parasitized than artificially buried pupae, although they may have left a physical or chemical trail that betrayed their presence. Thus, the artificial burial of pupae is unlikely to grossly underestimate C. haywardi efficacy in the field. Another field cage test found that mortality levels due to unsuccessful parasitoid attacks were similar to those resulting from successful parasitism. Thus, the actual effect of a mass-release might be considerably greater than that suggested from parasitism data alone. The results are considered sufficiently positive to encourage further testing of C. haywardi as a biological control agent of the Mediterranean fruit fly.     

Neural and non‐neural contributions to sexual dimorphism of mid‐day sleep in Drosophila melanogaster: a pilot study

Many of the characteristics associated with mammalian sleep are also observed in Drosophila melanogaster Meigen, making the fruit fly a powerful model organism for studying the genetics of this important process. Included among the similarities is the presence of sexual dimorphic sleep patterns, which, in flies, are manifested as increased mid‐day sleep (‘siesta’) in males compared with females. In the present study, targeted mis‐expression of the genes transformer (tra) and tra2 is used to either feminize or masculinize specific neural and non‐neural tissues in the fly. Feminization of male D. melanogaster using three different GAL4 drivers that are expressed in the mushroom bodies induces a female‐like reduced siesta, whereas the masculinization of females using these drivers triggers the male‐like increased siesta. A similar reversal of sex‐specific sleep is also observed by mis‐expressing tra in the fat body, which is a key tissue in energy metabolism and hormone secretion. In addition, the daily expression levels of takeout, an important circadian clock output gene, are sexually dimorphic. Taken together, these experiments suggest that sleep sexual dimorphism in D. melanogaster is driven by multiple neural and non‐neural circuits, within and outside the brain.     

Multispectral imaging for quality control of laboratory‐reared Anastrepha fraterculus (Diptera: Tephritidae) pupae

The sterile insect technique (SIT) has been widely used to suppress several fruit fly species. In southern Brazil, millions of sterile flies of the South American fruit fly, Anastrepha fraterculus Wiedemann (Dipetra: Tephritidae), will be produced in a mass‐rearing facility called MOSCASUL to suppress wild populations from commercial apple orchards. In spite of standard rearing conditions, the quality of pupal batches can be inconsistent due to various factors. The quantification of poor quality material (e.g. empty pupae, dead pupae or larvae) is necessary to track down rearing issues, and pupal samples must be taken randomly and evaluated individually. To speed up the inspection of pupal samples by replacing the manual testing with the mechanized one, this study assessed a multispectral imaging (MSI) system to distinguish the variations in quality of A. fraterculus pupae and to quantify the variations based on reflectance patterns. Image acquisition and analyses were performed by the VideometerLab4 system on 7‐d‐old pupae by using 19 wavelengths ranging from 375 to 970 nm. The image representing the near infrared wavelength of 880 nm clearly distinguished among high‐quality pupae and the other four classes (i.e. low‐quality pupae, empty pupae, dead pupae and larvae). The blind validation test indicated that the MSI system can classify the fruit fly pupae with high accuracy. Therefore, MSI‐based classification of A. fraterculus pupae can be used for future pupal quality assessments of fruit flies in mass‐rearing facilities.     

Ecological differences and competitive interaction between Drosophila melanogaster and Drosophila simulans in small laboratory populations

Summary In interspecific competition studies, some cases of apparent change in competitive ability have been reported. But the change in competitive outcome could equally well be due to character displacement. As a preliminary to studies of the effects of association of D. melanogaster (yellow white mutant strain) and D. simulans (vermilion mutant strain), the nature and extent of ecological differences between them, and the nature of their competitive interaction was studied. Differences between the strains were shown for oviposition site preferences, and for larval and pupal distribution. In pure species cultures, simulans showed a greater preference than melanogaster for oviposition in the center of the medium surface. In mixed populations, simulans had an increased preference for this oviposition site, where melanogaster was at low frequency. D. simulans larvae utilized the lower half of the medium to a significantly greater extent than did melanogaster. At low density (5 pairs of parents) in pure species cultures, 68.7% of simulans pupae were on the medium surface. As parental numbers increased, this proportion decreased. The distribution of melanogaster pupae was quite different, with only 8 to 12% on the medium at all densities. But the remaining pupae tended to occur higher on the cylinder wall as parental numbers increased. The competitive interaction changed during the developmental period. At four and eight days after culture initiation, simulans appeared superior, while for total adult progeny production, melanogaster was slightly superior. These strans of the two species were not ecologically equivalent.     

Morphology of the pupal heart,adult heart,and associated tissues in the fruit fly,Drosophila melanogaster

The early pupal heart of the fruit fly Drosophila melanogaster has recently been the subject of intense physiological and molecular work, yet it has not been well described, nor has it been compared with the heart of the adult fly. In the work reported here, the hearts of adults and early pupae of D. melanogaster were studied by scanning and transmission electron microscopy and by light microscopy. The hearts of adults and early pupae both consist of a tube of circular striated muscle one cell in thickness. The alary muscles, which suspend the heart, are more delicate in the adult compared to the early pupa. The pericardial cells in both early pupae and adults are connected to the heart by connective tissue radiating from the alary muscles or dorsal diaphragm. We confirm that four major changes occur in the heart during metamorphosis: 1) a conical chamber is formed de novo in the first and second abdominal segments; 2) the adult heart curves to conform to the contour of the abdomen; 3) a layer of longitudinal striated muscle appears on the ventral surface of the heart; 4) a fourth pair of ostia is added to the three already present in the early pupa; and note additionally that 5) the ostia appear as simple openings in the heart of the early pupa but are valve‐like in the adult. J. Morphol. 240:225–235, 1999. © 1999 Wiley‐Liss, Inc.     

Host-plant susceptibility to the carrot fly, Psila rosae. 2. Suitability of various host species for larval development

Several apiaceous and two asteraceous species were tested for their suitability to support larval development of the carrot fly. Plants grown in pots or transplanted from seed beds into pots, were inoculated with a specific number of eggs. Pupae and non-pupated larvae were collected 6–7 wk after inoculation. Both the number and weights of pupae produced varied widely among the species. Cultivated carrots Daucus carota sativus often gave rise to only moderate numbers of pupae, but these invariably attained the highest weights. Pimpinella major was the only apiaceous plant tested that did not yield any carrot flies. The two asteraceous plants Cichorium intybus and Tanacetum vulgare failed to support larval development. Total carrot fly biomass produced per plant was influenced by both the host species and the root weight. Emergence rates of adult flies were positively correlated with pupal weights. Small individuals tended to have a longer total developmental time from egg to adult fly.     

Distinct Acute Zones for Visual Stimuli in Different Visual Tasks in Drosophila

The fruit fly Drosophila melanogaster has a sophisticated visual system and exhibits complex visual behaviors. Visual responses, vision processing and higher cognitive processes in Drosophila have been studied extensively. However, little is known about whether the retinal location of visual stimuli can affect fruit fly performance in various visual tasks. We tested the response of wild-type Berlin flies to visual stimuli at several vertical locations. Three paradigms were used in our study: visual operant conditioning, visual object fixation and optomotor response. We observed an acute zone for visual feature memorization in the upper visual field when visual patterns were presented with a black background. However, when a white background was used, the acute zone was in the lower visual field. Similar to visual feature memorization, the best locations for visual object fixation and optomotor response to a single moving stripe were in the lower visual field with a white background and the upper visual field with a black background. The preferred location for the optomotor response to moving gratings was around the equator of the visual field. Our results suggest that different visual processing pathways are involved in different visual tasks and that there is a certain degree of overlap between the pathways for visual feature memorization, visual object fixation and optomotor response.     

Diapause, pupation sites and parasitism of the horn fly, Haematobia irritans, in south-eastern Brazil

In order to verify the occurrence of diapause, preference for pupation sites and hymenopteran parasitism, the pupae of the horn fly, Haematobia irritans (Diptera: Muscidae), were collected from undisturbed cattle dung pats in pastures, and adults of the fly were sampled from cattle in São Paulo State, south-eastern Brazil, from April 1993 to July 1994. Diapause was verified in 7.7% of pupae sampled from pastures in June and July of 1993 and in 9.9% of those sampled in May, June and July of 1994 (overall rate of 9.1%). Approximately 8.3% of the pupae were parasitized by microhymenopterans, mostly Spalangia nigroaenea and S.cameroni (Hymenoptera: Pteromalidae). Horn fly pupae were found almost exclusively inside the pat or in the soil immediately beneath and adjacent to it, and very few were collected elsewhere. Pupa mortality was 54.4% and did not change significantly during the year, but mortality was greater among pupae collected in pastures when compared to those obtained from experimental pats, lacking natural enemies.     

Neurogenesis in the water flea Daphnia magna (Crustacea, Branchiopoda) suggests different mechanisms of neuroblast formation in insects and crustaceans

Within euarthropods, the morphological and molecular mechanisms of early nervous system development have been analysed in insects and several representatives of chelicerates and myriapods, while data on crustaceans are fragmentary. Neural stem cells (neuroblasts) generate the nervous system in insects and in higher crustaceans (malacostracans); in the remaining euarthropod groups, the chelicerates (e.g. spiders) and myriapods (e.g. millipedes), neuroblasts are missing. In the latter taxa, groups of neural precursors segregate from the neuroectoderm and directly differentiate into neurons and glial cells. In all euarthropod groups, achaete–scute homologues are required for neuroblast/neural precursor group formation. In the insects Drosophila melanogaster and Tribolium castaneum achaete–scute homologues are initially expressed in clusters of cells (proneural clusters) in the neuroepithelium but expression becomes restricted to the future neuroblast. Subsequently genes such as snail and prospero are expressed in the neuroblasts which are required for asymmetric division and differentiation. In contrast to insects, malacostracan neuroblasts do not segregate into the embryo but remain in the outer neuroepithelium, similar to vertebrate neural stem cells. It has been suggested that neuroblasts are present in another crustacean group, the branchiopods, and that they also remain in the neuroepithelium. This raises the questions how the molecular mechanisms of neuroblast selection have been modified during crustacean and insect evolution and if the segregation or the maintenance of neuroblasts in the neuroepithelium represents the ancestral state. Here we take advantage of the recently published Daphnia pulex (branchiopod) genome and identify genes in Daphnia magna that are known to be required for the selection and asymmetric division of neuroblasts in the fruit fly D. melanogaster. We unambiguously identify neuroblasts in D. magna by molecular marker gene expression and division pattern. We show for the first time that branchiopod neuroblasts divide in the same pattern as insect and malacostracan neuroblasts. Furthermore, in contrast to D. melanogaster, neuroblasts are not selected from proneural clusters in the branchiopod. Snail rather than ASH is the first gene to be expressed in the nascent neuroblasts suggesting that ASH is not required for the selection of neuroblasts as in D. melanogaster. The prolonged expression of ASH in D. magna furthermore suggests that it is involved in the maintenance of the neuroblasts in the neuroepithelium. Based on these and additional data from various representatives of arthropods we conclude that the selection of neural precursors from proneural clusters as well as the segregation of neural precursors represents the ancestral state of neurogenesis in arthropods. We discuss that the derived characters of malacostracans and branchiopods – the absence of neuroblast segregation and proneural clusters – might be used to support or reject the possible groupings of paraphyletic crustaceans.     

Positive and negative signals between interacting cells for establishing neural fate

Specifying multiple cell types from a population of initially equivalent cells is a fundamental process in the development of all multicellular organisms. Neural development in the fruit fly Drosophila melanogaster provides an excellent venue in which to examine mechanisms of cell fate specification. Inhibitory cell–cell interactions mediated by genes of the Notch-Delta signaling pathway govern the selection of neural and epidermal fates among cells with equivalent developmental potential in a process termed lateral inhibition. Recent data on the roles of genes such as Notch, Delta, and kuzbanian warrant a rethinking of the lateral inhibition model. Furthermore, evidence for a positive signaling pathway promoting the neural fate among equivalent cells suggests that this mechanism acts in addition to lateral inhibition to specify cell fate. A balance of opposing signals may be necessary to correctly partition cells of different types from an initially homogeneous population of cells. BioEssays 20 :209-214, 1998. © 1998 John Wiley & Sons, Inc.     

Rapid thermal adaptation during field temperature variations in Drosophila melanogaster

Under natural conditions, the fruit fly (Drosophila melanogaster) is constantly exposed to variations in temperature and light. Laboratory investigations have demonstrated that D. melanogaster and other insects adapt quickly to temperature variations, but only few studies have investigated this ability under natural temperature variations. Here we placed laboratory raised female D. melanogaster in field cages and exposed them to natural variations in light and temperature over a 2 day period (temperature range: 12–25 °C). During this period we sampled flies every 6 h and measured their ability to survive heat and cold shock. There was a significant positive correlation between field temperature and heat shock survival and a significant negative correlation between field temperature and cold shock survival indicating that D. melanogaster are constantly adapting to their surrounding environment. The results also suggest that heat and cold resistance are obtained at a cost as these two traits were negatively correlated.     

Evolution of the larval peripheral nervous system in <Emphasis Type="Italic">Drosophila</Emphasis> species has involved a change in sensory cell lineage

A key challenge in evolutionary biology is to identify developmental events responsible for morphological changes. To determine the cellular basis that underlies changes in the larval peripheral nervous system (PNS) of flies, we first described the PNS pattern of the abdominal segments A1–A7 in late embryos of several fly species using antibody staining. In contrast to the many variations reported previously for the adult PNS pattern, we found that the larval PNS pattern has remained very stable during evolution. Indeed, our observation that most of the analysed Drosophilinae species exhibit exactly the same pattern as Drosophila melanogaster reveals that the pattern observed in D. melanogaster embryos has remained constant for at least 40 million years. Furthermore, we observed that the PNS pattern in more distantly related flies (Calliphoridae and Phoridae) is only slightly different from the one in D. melanogaster. A single difference relative to D. melanogaster was identified in the PNS pattern of the Drosophilinae fly D. busckii, the absence of a specific external sensory organ. Our analysis of sensory organ development in D. busckii suggests that this specific loss resulted from a transformation in cell lineage, from a multidendritic-neuron-external-sensory-organ lineage to a multidendritic-neuron-solo lineage.Edited by P. Simpson     

Eradication of the melon fly,Dacus cucurbitae,from Kume is., Okinawa with the sterile insect release method

The sterile insect release method was applied to eradicate the melon fly, Dacus cucurbitae, from the 58.5 km² island of Kume, in the Okinawa Islands group. Weekly releases of 1 to 1.5 million flies irradiated as pupae with 6–7 kR from a cobalt-60 source did not decrease the wild melon fly population. Releases of 1.5–2 million pupae per week made from September, 1975 to January, 1976 decreased the percent egg-hatch of females caught on Kume Is., but did not decrease the percent infestation significantly. The number of pupae released was increased from February, 1976 to accelerate the eradication process. When the number of pupae released exceeded 3.5 million per week, a rapid increase in the ratio of marked (sterile) to unmarked (wild) flies, a remarkable decrease in percent egg-hatch, and a decrease in percent infestation of fruits were observed. There has been no sign of melon fly infestation in wild cucurbit fruits from October, 1976 to the present time (April, 1977), despite the fact that more than 70,000 fruits were carefully examined. The eradication of the melon fly from Kume Is. was thus achieved by April, 1977, after the release of 264 million sterile fly pupae.     

Seasonal variation in generation time, diapause and cold hardiness in a central Ohio population of the flesh fly, Sarcophaga bullata

Abstract.

• 1 Generation time, diapause phenology and cold tolerance of the flesh fly, Sarcophaga bullata, were examined under confined natural conditions in central Ohio. In this locality, the fly can complete a maximum of four generations annually.
• 2 Very few pupae entered diapause in the first and second generations (May to July in 1988). In the third generation (August) 37% of the pupae entered an overwintering diapause, as did all pupae from the fourth generation (September).
• 3 The adult eclosion date in the spring and annual generation time can be predicted accurately from degree day data.
• 4 Cold tolerance of the field-overwintering portion of the population was high. After 30 days under field conditions, diapausing pupae readily survived a 7-day exposure to — 17°C. Glycerol appears to be the major cryoprotectant in S.bullata, and glycerol concentrations in the field population (95–142 mm ) remained high throughout the winter.
• 5 In contrast, diapausing flies reared under laboratory conditions (20°C, 12:12 LD) were less cold tolerant, and glycerol concentrations were lower (6.9–21.2 mm ). Field conditions thus promote the acquisition of high levels of cold tolerance, presumably as a consequence of the accumulation of higher concentrations of glycerol.
• 6 In spite of differences in the cold tolerance of laboratory and field flies, the supercooling points of the two groups of flies were nearly the same, thus implying that the supercooling point is not a good indicator of cold tolerance.