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At least 19 recordsLinked to original sources

Bioassessment of streams using macroinvertebrates: are the chironomidae necessary?

We compared the sensitivity of commonly used bioassessment metrics to detect organic impairment of streams using data sets that varied only in the inclusion or exclusion of Chironomidae identified to genus. We evaluated situations in two contrasting ecoregions of Missouri, U.S.A., the Ozark ecoregion and the Prairie ecoregion where Chironomidae comprise an average of 32 and 42%, respectively, of the total number of individuals. The without-Chironomidae data showed either identical or greater sensitivity than with Chironomidae data in every case when using the metrics total taxa, biotic index. Shannon's diversity index, and % dominant taxon. We conclude that bioassessment programs employing commonly-used metrics that usually incorporate Chironomidae may become more efficient by eliminating Chironomidae from the protocols and using those resources for analyzing additional sites.

Animals↗

Purification and properties of ferrochelatase from Chironomidae larvae.

Ferrochelatase with an Mr of 42,700 Da and a pI of 7.35 has been purified to homogeneity from chironomidae larvae. The activity of the enzyme reached maximum at pH 7.8 and decreased with the increase of pH. The enzyme activity varied with temperature and showed maximum activity around 37 degrees C. The purified enzyme was active towards protoporphyrin but inactive towards other porphyrins. The specific enzyme activity of ferrochelatase from chironomidae is about 10-fold higher than that of the rat. Electrophoresis of the purified fractions shows that the enzyme contains only one single polypeptide. The soluble ferrochelatase contained one mole of iron in each mole of the enzyme. The N-terminal sequence analysis of the enzyme shows a high percentage of conserved regions of the enzyme among other species. The enzyme properties are similar to those of the mammalian ferrochelatases except with slightly higher specific activity. Chironomidae ferrochelatase appeared to be more heat resistant and less susceptible than its mammalian equivalent to inhibition by lead.

Amino Acid Sequence↗

Allergens of non-biting midges (Diptera: Chironomidae): a systematic survey of chironomid haemoglobins.

Various genera of non-biting midges (Diptera: Chironomidae) possess haemoglobins in larvae and adults. For certain species, these haemoglobins have been implicated in human allergic disease in several countries. The present study confirms and extends observations that haemoglobin is present in many species of Chironomidae, establishes that it is retained from the larval to the adult stage and shows that haemoglobin persists both in live and in dead dry flies. Previous suggestions that Chironomidae should be seen as important environmental and occupational allergens are clearly substantiated.

Allergens↗

Chironomidae as a cause of IgE-mediated histamine release in patients with asthma.

The present study was undertaken to assess the importance of Chironomidae as an allergen causing bronchial asthma in Japan, and to evaluate histamine release as an allergy test in chironomid-midge allergic patients. Extracts of Chironomidae (T. akamusi and C. Yoshimatsui) caused the release of histamine in six out of 13 allergic patients with positive skin tests. In contrast, histamine release induced by these allergens was not observed in leukocytes from two asthmatic patients and five control subjects without IgE antibody as evidenced by negative skin tests and RAST. There was a significant correlation between maximal histamine release and IgE antibody levels. Furthermore, a significant inverse relationship between the concentration of allergen causing 25% histamine release (HR25) and IgE antibody levels was observed. The correlation coefficients, however, between histamine release and RAST were not high, and there were discrepancies between the two tests in some cases. These results suggest that Chironomidae induce histamine release from leukocytes via IgE-mediated mechanism but histamine release cannot be replaced by RAST and also suggest that chironomid midge is one of the important allergens in Japan.

Allergens↗

Allergenicity of Chironomidae in asthmatic patients.

In order to clarify the relation between asthma and Chironomidae, we examined the cross-reactivity between Chironomidae and other common allergens. We noted significant correlations between positive skin tests with Chironomidae and with other allergens. The radioallergosorbent inhibition test, however, suggested that there may be no cross-reactivity or, if any, only very low cross-reactivity between midge allergens and mite, house dust (HD), silk, shrimp, or mosquito allergens.

Allergens↗

Environmental variation and the predator-specific responses of tropical stream insects: effects of temperature and predation on survival and development of Australian Chironomidae (Diptera).

The threat posed by predation varies among predator species and with environmental context, and prey species often adjust their responses accordingly. We investigated such effects within an insect assemblage from a tropical Australian stream. These systems are frequently subjected to catastrophic floods, often suggested to reduce the importance of predation in streams, and invertebrate faunas are characterised by relatively broad environmental tolerances. Impacts of the hunting predator Australopelopia prionoptera (Diptera: Chironomidae) and an undescribed ambush predator from the Polycentropodidae (Trichoptera) on survival and development of two species of tubicolous Chironomidae, Echinocladius martini (Orthocladiinae) and Polypedilum australotropicus (Chironominae), were assessed in laboratory microcosms. A further experiment investigated how impacts of Australopelopia varied over a broad range of temperatures, exceeding that experienced annually by the studied populations. Neither predator impacted survivorship for E. martini, but the presence of the polycentropodid caused E. martini to spend longer as larvae and reduced adult longevity, and adult females were smaller-sized and had smaller oocytes. In contrast, both predators reduced survivorship of P. australotropicus, but only Australopelopia affected its development, causing reductions in pupal duration and oocyte size. The observed non-lethal impacts of predation reflect the threat each predator is known to pose to each prey species in situ. Impacts of predation varied little with temperature, reflecting the broad thermal tolerances of all study species. The predator-specific responses of the prey species imply that predation is a significant selective force in tropical Australian streams, although fluctuation in intensity of predation associated with flooding may limit its importance for community structure and prey diversity at larger scales. Our results indicate a more limited scope for environmental modification of predator-prey relationships in faunas characterised by broad physiological tolerances.

Animals↗

Purification and characterization of multiple glutathione S-transferase isozymes from Chironomidae larvae.

Glutathione S-transferase (GST) has been implicated in the process of biotransformation of polycyclic aromatic hydrocarbons and of other organic pollutants by Chironomidae larvae. We have purified and characterized GST from cytosolic fractions of Chironomidae larvae. GST with an M(r) of 23 kDa has been purified to homogeneity from larvae by centrifugation, size exclusion chromatography on Sephadex G25, and glutathione affinity and anion exchange chromatography. The purified enzyme exhibited moderate activity towards 1,2-dichloro-4-nitrobenzene, 1-chloro-2,4-dinitrobenzene, 4-nitropyridine-N-oxide, p-nitrobenzyl chloride, ethacrynic acid, and cumene hydroperoxide. The enzyme was homogeneous on gel isoelectric focusing and on SDS gel electrophoresis. Its isoelectric point was estimated to be 5.5. The enzyme had a maximum activity at approximately pH 8 and showed activity between 30 and 40 degrees C. It became inactive at higher temperature (>50 degrees C) for 5 min. The N-terminal sequence analysis of the amino acids shows a high % of conserved regions in the enzyme. The enzyme activity was comparable to levels of metabolism observed by animal GST involved in the detoxification of xenobiotics.

Amino Acid Sequence↗

IgG and IgE antibodies to Chironomidae in asthmatic patients.

IgG antibodies to Chironomidae and its correlations to radioallergosorbent and skin reactions were examined with the aim of clarifying the relationship between asthma and Chironomidae. The level of specific IgG antibody in asthmatic patients (0.698 +/- 0.034, n = 104) was significantly greater than that in normal subjects (0.367 +/- 0.032, n = 52) (P less than 0.01). The specific IgG level was not correlated to skin reaction, nor to IgE RAST scores. Specific IgG1 and IgG4 levels in asthmatic patients were significantly greater than in control subjects (n = 14) (P less than 0.01).

Animals↗

Phytophilous chironomidae (Diptera) and other macroinvertebrates in the ox-bow Infernão Lake (Jatai Ecological Station, Luiz Antonio, SP, Brazil).

Infernão Lake, located within the Jataí Ecological Station in Luiz Ant nio Municipal district (São Paulo State, Brazil), is one of the most typical ox-bow lake of the Mogi-Guaçu River, and it presents, as the main feature, its great quantity of aquatic macrophytes, whose intensive development, in the last years practically covered the whole mirror of water. With the purpose to point out the composition and to establish the relative participation of the phytophilic zoocoenosis that inhabits the different macrophytes of that lake, a collection program of the main vegetation stands was established. The collections, were carried out randomly, during dry season (1994), in stands of Salvinia auriculata, Utricularia sp., Cabomba piauhyensis, Eichhornia azurea and Scirpus cubensis being used specific methodology for each vegetable type. The analysis of the different macrophytes showed the presence of 4,130 macroinvertebrates of 28 families, in which Chironomidae (Diptera) and Naididae (Oligochaeta) were the most representative, contributing on the average with 51% and 25% of the total fauna. Asheum, Beardius, Chironomus, Goeldichironomus, Parachironomus and Polypedilum were the most abundant Chironomidae genera. Species of the genus Dero (Dero) and D. (Aulophorus) represented the most typical Naididac of the phytofauna. With clear faunistic gradient from the shore to the center of the lake, the taxocoenosis indicated low similarity (PSc < 50%), evidencing its own characteristics of each biotope. On the contrary, there was a high similarity (PSc > 60%) among the associated communities on different vegetables, when grouped into feeding guilds, with expressive participation, in most of the macrophytes, of the collector-gatherers category, except on S. auriculata, whose predators (> 50%) and collector-filterers (> 20%) dominance turned that zoocoenosis distinct from the others.

Animals↗

Effects of Nosema algerae infections on the gene activity of the salivary gland chromosomes of Acricotopus lucidus (Diptera, Chironomidae).

Larvae of Acricotopus lucidus (Diptera, Chironomidae) were successfully infected with Nosema algerae (Microsporidia, Nosematidae). Treatment of newly hatched larvae with 2-3 x 10(5) spores/ml produced a 59.7%-83.8% rate of microsporidia-infected animals within 6 weeks. One of the host tissues infected was the polytene salivary gland; 31.3%-35.3% of the larvae showed infections in the gland cells. This made it possible to investigate the reaction of the puffing pattern of the polytene host-cell chromosomes to the presence of an intracellular parasite. In slightly or moderately infected salivary gland cells, no change in the regular puffing patterns was observed. Only in heavily infected cells did an inactivation of cell-type-specific Balbiani rings and puffs occur, resulting in a change in the cell-type-specific genetic programme.

Animals↗

The potential association between menta deformities and trace elements in Chironomidae (Diptera) taken from a heavy metal contaminated river.

Elevated morphological deformity rates in Chironomidae larvae have been attributed to such pollutants as oil tars, pesticides, organochlorines, and heavy metals. The potential of chironomids as biological indicators of heavy metal contamination and bioavailability in a contaminated ecosystem was assessed. Chironomid larvae and river sediment were collected from the Coeur d' Alene River system, Idaho, USA, contaminated with heavy metals from mining activities. Chironomid larvae collected at contaminated sites exhibited mouthpart deformity proportions between 3.8 and 10.3% compared to the control site of 0.9%. As, Cd, Cu, Ni, Pb, and Zn were determined in both larvae and sediment samples. Significant correlation between metal concentrations and deformity rates were observed for all metals except Ni. The data also suggests that feeding habits may influence differences in pollution tolerance among genera.

Animals↗

A common epitope on major allergens from non-biting midges (Chironomidae).

A synthetic peptide corresponding to sequence 91-101 of the Chironomus thummi thummi haemoglobins (Chi t I) components III and IV was used to investigate binding and cross-reactivity with polyclonal human IgE and rabbit IgG antibodies and murine IgG1 subclass monoclonal antibodies (MABs). The synthetic peptide reacted with antibodies from all three mammals. The specificity of the reaction, especially that with IgE antibodies was shown by dose dependent inhibition with native Chi t I component III. Epitope(s) reacting with these antibodies were also found in haemoglobins from 14 of the 15 chironomid species analyzed. The synthetic peptide III/IV 91-101 enabled the identification of an important antigenic/allergenic determinant of the broadly distributed insect family Chironomidae. The antigenic potency of this synthetic peptide as shown by testing with human IgE, rabbit IgG and mouse MABs, and the widespread occurrence of the epitope in an identical or homologous sequence and/or superficial location, qualifies the peptide for therapeutic applications in medicine.

Allergens↗

Expression of heat shock protein and hemoglobin genes in Chironomus tentans (Diptera, chironomidae) larvae exposed to various environmental pollutants: a potential biomarker of freshwater monitoring.

To identify a sensitive biomarker of freshwater monitoring, we evaluated pollutant-induced expression of heat shock proteins (HSPs) and hemoglobins (Hbs) genes in the larvae of the aquatic midge Chironomus tentans (Diptera, Chironomidae). As pollutants, we examined nonylphenol, bisphenol-A, 17alpha-ethynyl estradiol, bis(2-ethylhexyl) phthalate, endosulfan, paraquat dichloride, chloropyriphos, fenitrothion, cadmium chloride, lead nitrate, potassium dichromate, benzo[a]pyrene and carbon tetrachloride. We also investigated larval growth as a physiological descriptor by measuring changes in the body fresh weight and dry weight after chemical exposure. The response of the HSPs gene expression by chemical exposure was rapid and sensitive to low chemical concentrations but it was not stressor specific. Interestingly, an increase in the expression of HSPs genes was observed not only in a stress inducible form (HSP70), but also in a constitutively (HSC70) expressed form. The expression of Hb genes showed chemical-specific responses: that is, alkyl phenolic compounds increased the expression of hemoglobin genes, whereas pesticides decreased the expression. As expected, molecular-level markers were more sensitive than physiological endpoints, suggesting that gene expression could be developed as an early warning biomarker in this animal. The overall results suggest that the expression of HSP and Hb genes in Chironomus could give useful information for diagnosing general health conditions in fresh water ecosystem. The expression of Hb genes, in particular, seems to be a promising biomarker, especially in view of the potential of Chironomus larvae as a biomonitoring species and of the physiological particularities of their respiratory pigments.

Animals↗

Acute and chronic life cycle toxicity of acenaphthene and 2,4,6-trichlorophenol to the midge Paratanytarsus parthenogeneticus (Diptera: Chironomidae).

The acute and life cycle toxicities of acenaphthene and 2,4,6-trichlorophenol (2,4,6-TCP) were evaluated using the parthenogenic dipteran larva, Paratanytarsus parthenogeneticus, of the family Chironomidae. Static 48 h acute toxicity tests employed third instar larvae, and the flow-through 20-day life cycle tests were initiated with eggs. No acute lethal effect was observed in the saturated concentration (2.1 mg/l) of acenaphthene in water, and the median lethal concentration of 2,4,6-TCP was approximately 40 mg/l. In the life cycle toxicity test with acenaphthene, hatchability of the midge was affected by 50% at an exposure concentration of approximately 0.17 mg/l. The median effective concentration for larval, pupal and adult development was found between 0.06 and 0.07 mg/l, respectively, and these were significantly lower than the effective concentration for hatching success. With regard to 2,4,6-TCP toxicity, the median effective concentration for midge hatchability was 4.23 mg/l. The larval development, pupal formation and adult emergence, however were impeded at 1.60, 1.46 and 1.33 mg/l, respectively. Each level was noticeably lower than the median effective concentration for hatchability. The concentrations for each compound that interfered with the development to fourth instar, pupa and adult were not significantly different. These results indicate that larval developments after hatching were the most sensitive stages and affected the success of midge growth.

Acenaphthenes↗

Comparative larvicidal activities of the four Bacillus thuringiensis serovars against a chironomid midge, Paratanytarsus grimmii (Diptera: Chironomidae).

The four reference strains of Bacillus thuringiensis, known to be pathogenic for mosquito larvae of the family Culicidae (Diptera), were examined for their larvicidal activities against a chironomid species, Paratanytarsus grimmii (Diptera: Chironomidae). Of the four, the type strain of B. thuringiensis serovar israelensis (H14) exhibited the highest activity against both early- and late-instar larvae, while the type strain of serovar kyushuensis (H11ac) and the strain 73-E-10-2 (H10, serovar darmstadiensis) showed relatively moderate toxicities. The strain HD-1 of serovar kurstaki (H3abc) had no larvicidal activity on this chironomid midge.

Animals↗

Phylogeny of the endemic Baikalian Sergentia (Chironomidae, Diptera).

Fragments of two mitochondrial genes, cytochrome b (CytB) and Cytochrome c oxidase subunit I (COI) have been used as phylogenetic markers in Sergentia (Chironomidae, Diptera). The concatenated (1241 bp) sequences from both genes were used to infer the phylogenetic relationships among seven Sergentia species. Five of the species belong to the endemic fauna of Lake Baikal. Alignments of the nucleotide sequences were used for the construction of trees using Neighbor-Joining and maximum parsimony methods. Both methods yielded similar results. Monophyly of both Sergentia and the Baikalian endemic species was well supported. The date of origin of the endemic group of Sergentia was estimated as 25.7 MYA which closely coincides with the start of geological changes in the Baikal area. A cytological tree, based on 12 chromosomal characteristics, for the same set of Sergentia species showed a great similarity to the molecular phylogeny.

Animals↗

Chironomidae (Diptera, Nematocera) fauna in three small streams of Skania, Sweden.

Two unpolluted streams and one chemically and thermally polluted stream in Skania, Sweden, were investigated in summer 1995 for their temporary chironomid fauna and the occurrence of buccal deformities. The unpolluted streams 'Ovedsan' and 'Skäralidbäcken' each contained, respectively, 13 and 16 taxa, with a dominance of Microtendipes pedellus group and Micropsectra spp., respectively. Most taxa were found in the pebbles and the submerged vegetation. Deformities were insignificant. The degraded stream Ybbarpsan in Perstorp contained 5 taxa, dominated by Procladius choreus. This species had 14% deformed larvae, interpreted as an effect of the chemical pollution. Shannon H and equitability J reflected the differences in chironomid community structure between the two unpolluted and the polluted sites. The Belgian Biotic Index scored maximally '10' in Skäralid, however only '6' in Oved and '5' in Perstorp. The combination of rapid assessment of macrobenthos and description of communities of Chironomidae, with mention of deformed larvae, adds a bonus of information about the temporary state of a stream.

Animals↗

Effect of potassium dichromate and fenitrothion on hemoglobins of Chironomus riparius Mg. (Diptera, Chironomidae) larvae: potential biomarker of environmental monitoring.

In an attempt to identify Chironomus hemoglobins as biomarkers for environmental monitoring, alterations in the hemoglobins in Chironomus riparius Mg. (Diptera: Chironomidae) larvae, exposed to potassium dichromate and fenitrothion, were investigated under laboratory conditions. The hemoglobins were evaluated in terms of their total contents by a cyanomethemoglobin procedure, individual components by electrophoresis of isoelectric focusing, and their oxidation by multi wavelength rapid-scanning spectrophotometry. The total hemoglobin contents increased at the high level of fenitrothion exposure. No variations in the individual hemoglobin component levels were found, by exposure to either fenitrothion or potassium dichromate. Whereas, the absorption spectra of the hemoglobins showed decreases in the peaks corresponding to the oxyhemoglobins by exposure to both compounds, but more sensitively by the chromium, which probably reflects the increase of the autoxidation of the oxyhemoglobins to methemoglobins by these compounds. These results suggest that autoxidation of the hemoglobins in Chironomus riparius seems to be a sensitive parameter in response to redox-active chemical exposure, and this biochemical parameter could be developed as a biomarker in environmental monitoring.

Animals↗