Landscape genetics and spatial pattern of phenotypic variation of Eristalis tenax across Europe

A study of population connectivity of the migratory insect species, such as dronefly Eristalis tenax (Diptera, Syrphidae), has an essential importance in understanding the relative influence of the evolutionary forces and environmental features that interact in the spatial distribution of molecular and morphological diversity. However, specific study aiming to understand spatial genetic structure of dronefly populations and its migratory potential is lacking. Hence, we studied a spatial pattern of genetic and phenotypic variation of seven European populations of E. tenax incorporating landscape genetic methods using allozyme data, wing size and shape and abdominal colour pattern. Based on the observed lack of genotypic structuring, we suggested that there has been sufficient long‐distance gene flow to effectively homogenize population structuring at a broader geographical scale. Wing shape similarity among populations and an overlap of abdominal colour variation showed no clear clustering related to geography, which is in congruence with genetic data. However, genetic (F_ST values) and phenotypic (wing size) data and landscape genetics indicated subdivision between the Balkan populations (four Serbian samples) and populations from Central (Germany and Switzerland) and Northern (Finland) Europe. These findings indicated a potential connection between the Central and Northern Europe supporting the Central European origin of the flies caught in Finland. Thus, by performing spatial analysis and combining genetic–morphological approach, we shed light on the movement pattern in complex landscapes and thus provided the necessary guidelines to a broad‐scale analysis of this widespread generalist pollinator.     

Den 1, Den2 and Den3, ATP-inhibited deoxyribonucleases from Dropsophila embryonic nuclei

Three Drosophila embryonic deoxyribonucleases, designated den1, den2 and den3, are identified in nuclear extracts separated by glycerol density gradient centrifugation. Den1, removes short products from the 5-ends of single-stranded DNA or double-stranded DNA with either blunt or 5-recessed termini. Den2 is inactive with single-stranded DNA and acts as 3-exonuclease with double-stranded DNA possessing either blunt or 3-recessed termini. Den3 preferentially uses partial duplex DNA containing single-stranded gap and it catalyzes hydrolysis, in 3-5 direction, of one of the shorter strands that flank the gap. Nucleolytic activities of den1, den2 and den3 are inhibited with ATP.     

Non-secretory solitary plasmacytoma of the spleen

A case of primary nonsecretory plasmacytoma of the spleen is reported. On laparotomy and splenectomy a 920 g spleen was removed, measuring 16×14×6 cm. The cut surface of the entire spleen showed that the tumour occupied most of the splenic tissue. A bone marrow aspirate and trephine, skeletal survey showed no signs of myeloma. Biopsy of the liver and regional lymph nodes was normal. Immunocytochemistry of the splenic tumour showed positivity for pan-B and plasma cell markers. After splenectomy the patient was treated with chemotherapy according to protocol VBCMP (M2).     

Genetic and phenotypic variation in central and northern European populations of Aedes (Aedimorphus) vexans (Meigen, 1830) (Diptera,Culicidae)

The floodwater mosquito Aedes vexans can be a massive nuisance in the flood plain areas of mainland Europe, and is the vector of Tahyna virus and a potential vector of Dirofilaria immitis. This epidemiologically important species forms three subspecies worldwide, of which Aedes vexans arabiensis has a wide distribution in Europe and Africa. We quantified the genetic and phenotypic variation in Ae. vexans arabiensis in populations from Sweden (northern Europe), Hungary, and Serbia (central Europe). A landscape genetics approach (F_ST, STRUCTURE, BAPS, GENELAND) revealed significant differentiation between northern and southern populations. Similar to genetic data, wing geometric morphometrics revealed two different clusters, one made by Swedish populations, while another included Hungarian and Serbian populations. Moreover, integrated genetic and morphometric data from the spatial analysis suggested groupings of populations into three clusters, one of which was from Swedish and Hungarian populations. Data on spatial analysis regarding an intermediate status of the Hungarian population was supported by observed Isolation‐by‐Distance patterns. Furthermore, a low proportion of interpopulation vs intrapopulation variance revealed by AMOVA and low‐to‐moderate F_ST values on a broader geographical scale indicate a continuous between‐population exchange of individuals, including considerable gene flow on the regional scale, are likely to be responsible for the maintenance of the observed population similarity in Aе. vexans. We discussed data considering population structure in the light of vector control strategies of the mosquito from public health importance.     

A controlled study of the effects of EEG biofeedback on cognition and behavior of children with attention deficit disorder and learning disabilities

Eighteen children with ADD/ADHD, some of whom were also LD, ranging in ages from 5 through 15 were randomly assigned to one of two conditions. The experimental condition consisted of 40 45-minute sessions of training in enhancing beta activity and suppressing theta activity, spaced over 6 months. The control condition, waiting list group, received no EEG biofeedback. No other psychological treatment or medication was administered to any subjects. All subjects were measured at pretreatment and at posttreatment on an IQ test and parent behavior rating scales for inattention, hyperactivity, and aggressive/defiant (oppositional) behaviors. At posttreatment the experimental group demonstrated a significant increase (mean of 9 points) on the K-Bit IQ Composite as compared to the control group (p<.05). The experimental group also significantly reduced inattentive behaviors as rated by parents (p<.05). The significant improvements in intellectual functioning and attentive behaviors might be explained as a result of the attentional enhancement affected by EEG biofeedback training. Further research utilizing improved data collection and analysis, more stringent control groups, and larger sample sizes are needed to support and replicate these findings.This research was supported by an equipment grant by Autogenics Systems. Portions of this paper were presented at the annual convention of the Association of Applied Psychophysiology and Biofeedback, March, 1993 in Los Angeles and at the annual meeting of the Biofeedback Society of California, November, 1992 in Monterey, California. The authors gratefully acknowledge Todd Fischer and Paul Clopton for their valuable assistance in statistical analysis for this article.     

Membrane localization of motility,signaling, and polyketide synthetase proteins in Myxococcus xanthus

Myxococcus xanthus cells coordinate cellular motility, biofilm formation, and development through the use of cell signaling pathways. In an effort to understand the mechanisms underlying these processes, the inner membrane (IM) and outer membrane (OM) of strain DK1622 were fractionated to examine protein localization. Membranes were enriched from spheroplasts of vegetative cells and then separated into three peaks on a three-step sucrose gradient. The high-density fraction corresponded to the putative IM, the medium-density fraction corresponded to a putative hybrid membrane (HM), and the low-density fraction corresponded to the putative OM. Each fraction was subjected to further separation on discontinuous sucrose gradients, which resulted in discrete protein peaks for each major fraction. The purity and origin of each peak were assessed by using succinate dehydrogenase (SDH) activity as the IM marker and reactivities to lipopolysaccharide core and O-antigen monoclonal antibodies as the OM markers. As previously reported, the OM markers localized to the low-density membrane fractions, while SDH localized to high-density fractions. Immunoblotting was used to localize important motility and signaling proteins within the protein peaks. CsgA, the C-signal-producing protein, and FibA, a fibril-associated protease, were localized in the IM (density, 1.17 to 1.24 g cm(-3)). Tgl and Cgl lipoproteins were localized in the OM, which contained areas of high buoyant density (1.21 to 1.24 g cm(-3)) and low buoyant density (1.169 to 1.171 g cm(-3)). FrzCD, a methyl-accepting chemotaxis protein, was predominantly located in the IM, although smaller amounts were found in the OM. The HM peaks showed twofold enrichment for the type IV pilin protein PilA, suggesting that this fraction contained cell poles. Two-dimensional polyacrylamide gel electrophoresis revealed the presence of proteins that were unique to the IM and OM. Characterization of proteins in an unusually low-density membrane peak (1.072 to 1.094 g cm(-3)) showed the presence of Ta-1 polyketide synthetase, which synthesizes the antibiotic myxovirescin A.     

The in vivo genotoxicity of cisplatin,isoflurane and halothane evaluated by alkaline comet assay in Swiss albino mice

The aim of this study was to evaluate the genotoxicity of repeated exposure to isoflurane or halothane and compare it with the genotoxicity of repeated exposure to cisplatin. We also determined the genotoxicity of combined treatment with inhalation anaesthetics and cisplatin on peripheral blood leucocytes (PBL), brain, liver and kidney cells of mice. The mice were divided into six groups as follows: control, cisplatin, isoflurane, cisplatin–isoflurane, halothane and cisplatin–halothane, and were exposed respectively for three consecutive days. The mice were treated with cisplatin or exposed to inhalation anaesthetic; the combined groups were exposed to inhalation anaesthetic after treatment with cisplatin. The alkaline comet assay was performed. All drugs had a strong genotoxicity (P < 0.05 vs. control group) in all of the observed cells. Isoflurane caused stronger DNA damage on the PBL and kidney cells, in contrast to halothane, which had stronger genotoxicity on brain and liver cells. The combination of cisplatin and isoflurane induced lower genotoxicity on PBL than isoflurane alone (P < 0.05). Halothane had the strongest effect on brain cells, but in the combined treatment with cisplatin, the effect decreased to the level of cisplatin alone. Halothane also induced the strongest DNA damage of the liver cells, while the combination with cisplatin increased its genotoxicity even more. The genotoxicity of cisplatin and isoflurane on kidney cells were nearly at the same level, but halothane caused a significantly lower effect. The combinations of inhalation anaesthetics with cisplatin had stronger effects on kidney cells than inhalation anaesthetics alone. The observed drugs and their combinations induced strong genotoxicity on all of the mentioned cells.     

Interactive effects of pests increase seed yield

Loss in seed yield and therefore decrease in plant fitness due to simultaneous attacks by multiple herbivores is not necessarily additive, as demonstrated in evolutionary studies on wild plants. However, it is not clear how this transfers to crop plants that grow in very different conditions compared to wild plants. Nevertheless, loss in crop seed yield caused by any single pest is most often studied in isolation although crop plants are attacked by many pests that can cause substantial yield losses. This is especially important for crops able to compensate and even overcompensate for the damage. We investigated the interactive impacts on crop yield of four insect pests attacking different plant parts at different times during the cropping season. In 15 oilseed rape fields in Sweden, we estimated the damage caused by seed and stem weevils, pollen beetles, and pod midges. Pest pressure varied drastically among fields with very low correlation among pests, allowing us to explore interactive impacts on yield from attacks by multiple species. The plant damage caused by each pest species individually had, as expected, either no, or a negative impact on seed yield and the strongest negative effect was caused by pollen beetles. However, seed yield increased when plant damage caused by both seed and stem weevils was high, presumably due to the joint plant compensatory reaction to insect attack leading to overcompensation. Hence, attacks by several pests can change the impact on yield of individual pest species. Economic thresholds based on single species, on which pest management decisions currently rely, may therefore result in economically suboptimal choices being made and unnecessary excessive use of insecticides.     

Internal Binding of Halogenated Phenols in Dehaloperoxidase-Hemoglobin Inhibits Peroxidase Function

Dehaloperoxidase (DHP) from the annelid Amphitrite ornata is a catalytically active hemoglobin-peroxidase that possesses a unique internal binding cavity in the distal pocket above the heme. The previously published crystal structure of DHP shows 4-iodophenol bound internally. This led to the proposal that the internal binding site is the active site for phenol oxidation. However, the native substrate for DHP is 2,4,6-tribromophenol, and all attempts to bind 2,4,6-tribromophenol in the internal site under physiological conditions have failed. Herein, we show that the binding of 4-halophenols in the internal pocket inhibits enzymatic function. Furthermore, we demonstrate that DHP has a unique two-site competitive binding mechanism in which the internal and external binding sites communicate through two conformations of the distal histidine of the enzyme, resulting in nonclassical competitive inhibition. The same distal histidine conformations involved in DHP function regulate oxygen binding and release during transport and storage by hemoglobins and myoglobins. This work provides further support for the hypothesis that DHP possesses an external binding site for substrate oxidation, as is typical for the peroxidase family of enzymes.     

Functional studies of aegerolysin and MACPF‐like proteins in Aspergillus niger

Proteins of the aegerolysin family have a high abundance in Fungi. Due to their specific binding to membrane lipids, and their membrane‐permeabilization potential in concert with protein partner(s) belonging to a membrane‐attack‐complex/perforin (MACPF) superfamily, they were proposed as useful tools in different biotechnological and biomedical applications. In this work, we performed functional studies on expression of the genes encoding aegerolysin and MACPF‐like proteins in Aspergillus niger. Our results suggest the sporulation process being crucial for strong induction of the expression of all these genes. However, deletion of either of the aegerolysin genes did not influence the growth, development, sporulation efficiency and phenotype of the mutants, indicating that aegerolysins are not key factors in the sporulation process. In all our expression studies we noticed a strong correlation in the expression of one aegerolysin and MACPF‐like gene. Aegerolysins were confirmed to be secreted from the fungus. We also showed the specific interaction of a recombinant A. niger aegerolysin with an invertebrate‐specific membrane sphingolipid. Moreover, using this protein labelled with mCherry we successfully stained insect cells membranes containing this particular sphingolipid. Our combined results suggest, that aegerolysins in this species, and probably also in other aspergilli, could be involved in defence against predators.