Vergleichende Analyse der Gene und der Genomstruktur der geschlechtsbestimmenden Chromosomenregion von Chironomus und Camptochironomus

Im Rahmen der vorliegenden Arbeit wurde ein Bereich aus der geschlechtsbestimmenden Chromosomenregion, der „Contig SDR“, von C. tentans mit einer Größe von ~87 kb untersucht. Zur Erstellung des Contigs wurden 8 BAC-Klone aus C. tentans isoliert, teilweise subkloniert und sequenziert. Innerhalb des Contigs SDR konnten insgesamt 13 Gene sowie ein Teilbereich des Gens rpS5-like im distalen Bereich des Contigs SDR identifiziert werden. Hierbei handelt es sich um dieselben Gene, welche schon im Contig SDR von C. thummi identifiziert werden konnten. Ein Vergleich der beiden Contigs zeigt, dass die Abfolge der Gene zwischen den beiden Arten C. thummi und C. tentans identisch ist. Weiterhin konnten im Contig SDR von C. tentans sechs Bereiche lokalisiert werden, in denen repetitive oder transposable Elemente zu finden sind. Ein Vergleich der larvalen Transkripte (L4-Stadium) von 11 Genen des Contigs SDR aus C. thummi ♂ und C. thummi ♀ per RT-PCR und Hochdurchsatz-Sequenzierung zeigte mit Ausnahme der Gene luc7(p)-like sowie fs(1)K10-like bislang keine weiteren geschlechtsspezifischen Unterschiede. Im Gen luc7(p)-like konnte in C. thummi ♀ und C. piger ♀ ein alternativ gespleißtes Intron im eigentlichen Exon 2 identifiziert werden. Bei fs(1)K10-like konnte in C. thummi ♂ eine Duplikation des Gens nachgewiesen werden. Weiterhin wurden mit Hilfe des RACE-Verfahrens die 5’UTR- und 3’UTR-Bereiche der Transkripte analysiert. Hierdurch konnten differentielle Spleißprodukte identifiziert werden, welche jedoch nicht geschlechtsspezifisch auftreten. Die bioinformatische Bearbeitung der von den Genen der SDR kodierten Proteine auf konservierte Domänen zeigt vier Proteine, die möglicherweise als Transkriptions- oder Spleißfaktoren wirken können. Hierbei handelt es sich um die Proteine der Gene mi-er1-like, luc7(p)-like, polyhomeotic-like sowie rpn5-like. Für das auf Grund der männchenspezifischen Duplikation in C. thummi in den Fokus geratene Genprodukt von fs(1)K10-like konnten keine Domänen vorhergesagt werden. Somit kann nicht gesagt werden, ob das Protein im Rahmen der Geschlechtsdetermination eine Funktion haben könnte. Die Sequenzidentität der abgeleiteten AS-Sequenz liegt für alle Gene außer mi-er1-like (87,6 %) zwischen den beiden Arten C. tentans und C. thummi bei 93,3 %.

Unexpected homology between inducible cell wall protein QID74 of filamentous fungi and BR3 salivary protein of the insect Chironomus

A gene, qid74, of mycoparasitic filamentous fungus Trichoderma harzianum and its allies encodes a cell wall protein that is induced by replacing glucose in the culture medium with chitin (simulated mycoparasitism conditions). Because no trace of this gene can be detected in related species such as Gibberella fujikuroi and Saccharomyces cerevisiae, the qid74 gene appears to have arisen de novo within the genus Trichoderma. Qid74 protein, 687 residues long, is now seen as highly conserved tandem repeats of the 59-residue-long unit. This unit itself, however, may have arisen as tandem repeats of the shorter 13-residue-long basic unit. Within the genus Trichoderma, the amino acid sequence of Qid74 proteins has been conserved in toto. The most striking is the fact that Qid74 shares 25.3% sequence identity with the carboxyl-terminal half of the 1,572-residue-long BR3 protein of the dipteran insect Chironomus tentans. BR3 protein is secreted by the salivary gland of each aquatic larva of Chironomus to form a tube to house itself. Furthermore, the consensus sequence derived from these 59-residue-long repeating units resembles those of epidermal growth factor-like domains found in divergent invertebrate and vertebrate proteins as to the positions of critical cysteine residues and homology of residues surrounding these cysteines.

Non-destructive DNA extraction from Chironomidae, including of fragile pupal exuviae, extends analysable collections and enhances vouchering

It is well established that the traditional taxonomy and nomenclature of Chironomidae relies on adult males whose usually characteristic genitalia provide evidence of species distinction. In the early days some names were based on female adults of variable distinctiveness – but females are difficult to identify (Ekrem et al. 2010) and many of these names remain dubious. In Russia especially, a system based on larval morphology grew in parallel to the conventional adult-based system. The systems became reconciled with the studies that underlay the production of the Holarctic generic keys to Chironomidae, commencing notably with the larval volume (Wiederholm, 1983). Ever since Thienemann’s pioneering studies, it has been evident that the pupa, notably the cast skins (exuviae) provide a wealth of features that can aid in identification (e.g. Wiederholm, 1986). Furthermore, the pupae can be readily associated with name-bearing adults when a pharate (‘cloaked’) adult stage is visible within the pupa. Association of larvae with the name-bearing later stages has been much more difficult, time-consuming and fraught with risk of failure. Yet it is identification of the larval stage that is needed by most applied researchers due to the value of the immature stages of the family in aquatic monitoring for water quality, although the pupal stage also has advocates (reviewed by Sinclair & Gresens, 2008). Few use the adult stage for such purposes as their provenance and association with the water body can be verified only by emergence trapping, and sampling of adults lies outside regular aquatic monitoring protocols.

A note on sampling chironomids for RNA-based studies of natural populations that retains critical morphological vouchers

The rapid uptake of transcriptomic approaches in freshwater ecology has seen a wealth of data produced concerning the ways in which organisms interact with their environment on a molecular level. Typically, such studies focus either at the community level and so don’t require species identifications, or on laboratory strains of known species identity or natural populations of large, easily identifiable taxa. For chironomids, impediments still exist for applying these technologies to natural populations because they are small-bodied and often require time-consuming secondary sorting of stream material and morphological voucher preparation to confirm species diagnosis. These procedures limit the ability to maintain RNA quantity and quality in such organisms because RNA degrades rapidly and gene expression can be altered rapidly in organisms; thereby limiting the inclusion of such taxa in transcriptomic studies. Here, we demonstrate that these limitations can be overcome and outline an optimised protocol for collecting, sorting and preserving chironomid larvae that enables retention of both morphological vouchers and RNA for subsequent transcriptomics purposes. By ensuring that sorting and voucher preparation are completed within <4 hours after collection and that samples are kept cold at all times, we successfully retained both RNA and morphological vouchers from all specimens. Although not prescriptive in specific methodology, we anticipate that this paper will assist in promoting transcriptomic investigations of the sublethal impact on chironomid gene expression of changes to aquatic environments.

On the feeding of the larvae of Chironomidae during the planktonic period of life [Translation from: Nauch.Dokl.vyssh.Shk.Biol.Nauk 1 19-21, 1965]

It is known that the larvae of Chironomidae in the first stages of life after leaving the egg case, swim for a long time in a body of water. Positive reaction in light, the capability of directed swimming and passive floating in suspension allow the larvae to temporarily carry out a planktonic way of life. This study describes the behaviour of Chironomus dorsalis larvae after leaving the egg case. The feeding of chironomid larvae in the first stages of development was also described.

Some data on the predacious behaviour of tendipidae larvae [Translation from: C. R. Acad. Sci. U.R.S.S. 111, 466-4, 1956]

A study has been made primarily of the food of the chironomid Procladius nigriventris: this includes Alona affinis, Bosmina coregoni, Camptocercus, Eucyclops serrulatus, Paracyclops fimbriatus, Acanthocyclops viridis, Harpacticoida, Diaptomus graciloides, Ostracods, Chironomus sp, Polypedilum sp and Tanytarsus sp. Chironomus larvae usually found in the gut are in their 1st or 2nd instars , though occasional 3rd instars are present. The study summarises other findings on the feeding behaviour of Procladius nigriventris.

The effect of oxygen concentration in water on the growth and nitrogen metabolism in the fry of rainbow trout [Translation from: Rybnoe Khoziaistvo,V.33, 74-75, 1957]

To ascertain the effect of various concentrations of oxygen in water on the fry of rainbow trout experiments were made with aquaria at various concentrations of oxygen. The food supplied was chironomid larvae (Chironomus plumosus). A surplus of food was supplied to the fry. Indices are given of the reaction of the fry to different temperatures.

Limnology and fishery biology of the streams at Horton Plains, Sri Lanka (Ceylon)

The present study deals with the chemical, algal and faunal characteristics of the stream system at Horton Plains, the highest plains in Ceylon (altitude 2'225 m). The cultivation of seed potatoes and subsequent use of fertilizers have caused extensive silting and severe eutrophication of the stream systems. Since there are no indigenous fish, the trout Salmo gairdnerii has been introduced and it is the only fish found in these streams. The commonest fauna in the streams are crabs (Paratelphusa sp.), shrimps (Caridimr sp.), Simulium sp. and Chironomus sp. Their increase in number is probably correlated with increase in organic and detritus matter. The most important food items of the trout are the crabs living abundantly in the stream, insect larvae and terrestrial insects were also commonly found in the guts. Records of stocking and taking of trout in the Horton plains streams have shown that now less trout are taken relatively to the numbers stocked. This decrease may be possibly due to the eutrophication of the stream and also due to the possible use of pollutants in connection with the cultivation of seed potatoes.

Benthic diversity of River Gomti in relation to the prevailing environmental conditions in Lucknow

To evaluate the benthic diversity of River Gomti in relation to the prevailing environmental conditions, four stations, viz., Maa Chandrika Devi, Daliganj, Ambedkar Park and Aquaduct, were identified from upstream to downstream along the course of the river in Lucknow. Dissolved oxygen was low on many occasions at all the stations except Maa Chandrika Devi and chemical oxygen demand values were high. There was a gradual increase in mean nitrite and phosphate values from up to downstream. Benthic fauna was dominated by oligochaetes and chironomus larvae. Other groups reported were leeches, nematodes, sponges, crustaceans, pelycypodes, gastropods and fish fry. Population density was exceptionally high at Daliganj (20,135 m sub(-1) ) followed by Ambedkar Park (5,199 m sub(-1)) and Aquaduct (3,287 m sub(-1)), and low at Maa Chandrika Devi (264 m sub(-1)). Oligochaete genera common at all the four stations were Lumbricillus, Limnodrillus, Branchiura, Chaetogaster, Nais and Tubifex. Odonates were reported only from Maa Chandrika Devi while sponges were encountered at Daliganj and Aquaduct. On some occasions, fish fry were also found at Ambedkar Park and Aquaduct. Seasonally, maxima for population density were observed during pre-monsoon and minima during monsoon. The organic pollution indicator benthic species reported were tubificids, chironomids, culicoid larvae, Lamellidens sp., Corbicula sp., Lymnaea sp. and leech. Branchiurans, Tubifex sp. and Chironomus larvae were reported at all the stations. Filthy condition with foul smell throughout the length of the river coupled with poor water quality and appearance of indicator organisms at all the stations indicate that the river is under severe pollution stress due to anthropogenic discharges and it has reached an alarming stage.

Study of density, distribution and yield on benthic fauna and brown trout (Salmo trutta fario) feeding in Laar reservoirs

Lar lake, with the international UTM specification of 39S 579680 3976567 & 39S 589930 3976184 is Situated in Lar national Park with an aerial distance of 55 Km of Tehran along Haraz road. The present research is carried out as part of a comprehensives Plan for assessment of bioresearches of Lar lake & the rivers flowing into it. This research includes examination of there benthic Samplings performed in Lar lake and each of the related rivers including Delichaee, Ab-e-sefid , Alarm & Lar (Kamardasht).Tubifex and Chironomus genus were found to have the highest frequencies of occurrence in the lake with %77.117 & %21.823 respectively followed by Chironomidae and Simulidae from the Diptera order which accounted for %72.328 and %13.812 occurrences in four rivers examined in the Study. The benthic biomass at various examined Sites and the average wet weight of the benthic biomass in station No one in the lake Was 17.397g and the figure for the examined site in Alarm was 20.242 g which were the highest level among Other examination stations the index for the abundance of species in Alarm river was greater than the rest of the examined rivers with 12.57. A sum of 354 Pieces of brown trouts was caught in the course of sampling which were closely investigated in terms of their digestive tract Content. It was identified that Daphniidae and Chironomus constituted the bulk of eaten items from the lake with %17.985 and %63.973 respectively. Meanwhile, Chironomidae and Simuladae were the most frequently eanten benthos by the fish with %81.47 and %7.93 respectively.The index for the relative length of gut was recorded at 0.49± 0.08 which is well indicative of the carnivorous diet of the fish.The index for the feeding intensity amounted to 138  83 showing that the one year old fish were of more feeding intensity.The coefficient of condition (K) was estimated at 1.02  0.142 for all the caught fish. The average wet weight of the benthos was 10.348 g per square meter which if extended to 700ha surface area of the lake, the total macrobenthic production in the lake would amount to 72730Kg of wet weight or 6510 Kg of dry weight. Since the Secondary Production of macrobenthos have always been double that of their biomass, it is reasonable to assume that the Secondary Production of macrobenthos amount to 145640 Kg by their wet weight and Since the energy transfer in the food chain of the lake from benthos to fish is 10 percent, the fish production Capacity Coming from benthic resources of the lake (Lar) would be 14.5 MT, half of which (7000-8000MT) could annually be harvested. Further more, the actual fish Production Capacity might exceed the projected level Since Daphnia, Rotifers and Ostracoda which belong to Zooplanktons, play a part in the natural diet of trout. Meanwhile, rivers Play a major role in fish nutrition and the annual fish production in Delichaee river is about 4481.8Kg while the figures for Ab-e-sefid, Alerm and Lar rivers are 2370.7 4848.7 and 2586.2 Kg respectively, that further increase fish Production in the area and every year half of these resources can be exploitable from the river & the lake.Nevertheless, due to ecological & biological importance of rivers and the probability of environmental Pollution, devastation of natural fish habitats & their nursery grounds, Sport fishing is not recommended at all.

The study of ecological condition on productivity of Tajan River estuary in Mazandaran Province Caspian Sea

This project was done during a one-year period (2006-2007) with the aim of assessing and evaluating the susceptible and vulnerable habitat of Tajan River estuarine region as well as identifying its ecological features. This region consists of Tajan estuarine region as one of the sub-basins of the Caspian Sea basin which covers a surface of 2km2. In this assessment, 6 riverine estuarine and marine stations were chosen in which non-biotic parameters such as temperature, salinity, dissolved oxygen, pH and nutrients, and biotic parameters such as variation, density, plankton, primary production by chlorophyll-a. Benthos variation density, silt and the organic materials of the sediments were sampled and measured monthly. The amount of chlorophyll-a concentration and primary production showed a lot of seasonal changes at these stations which ranged from0.3 to 96 mg/m3. The results from the primary productions indicated that the eastern station of the estuary had high concentrations of chlorophyll-a during all seasons (96mg/m3). The most important and dominant planktonic groups in this region included Bacillariophyta from plankton and copepoda from zooplankton. The most important Benthos communities consisted of Driessena polymorpha.Cerastoderma lamarki in estuarine region,Chironomus plumosus in riverine region and Hypaniola sp. In marine region. Assessing the annual variation in these three riverine, estuarine and marine regions, phytoplankton with 3.1, Zooplankton with 2.7 and Benthos with 1.9 Showed the most density in the estuarine region. Assessing the annual density, phytoplanktonic (6118967 no . in m3) and zooplanktonic (7272 no . in m3) communities showed the most density in the marine region. Assessing the statistical tests showed that the estuarine and riverine regions had a significant difference in planktonic density (p<0.005) compared with the marine region. Moreover, The zeoplanktonic density in the marine region had a significant difference (p<0.005) with estuarine and riverine regions. Tooki test and one-way variance Analysis showed that in assessing the planktonic groups (p<0.005) and Benthos (p<0.005), there was a significant difference in variation index between river with estuary, and estuary with the sea. The amount of the total annual live biomass of the Benthos resource in Tajan river estuarine region was estimated 757.66 g/m2.

Ecology of macrozoobenthic communities in two plateau lakes of Southwest China

Ecological studies on macrozoobenthos were conducted in two small plateau lakes in the Yunnan-Guizhou Plateau, Southwest China: Xingyun Lake (XL), a eutrophic lake whose main source of primary production was phytoplankton (Chl a=99.76 +/- 24.01 mu g/L), and Yangzong Lake (YL), a mesotrophic lake. Sampling was carried out from October 2002 to May 2004. Altogether 23 benthic taxa were identified in XL and 21 taxa in YL. The density of benthos in XL was much lower than that in YL, but the biomass was about equal in the two lakes, being 1 423 ind/m(2) and 8.71 g/m(2) in XL and 4 249 ind/m(2) and 8.60 g/m(2) in YL. The dominant species were Limnodrilus hoffmeisteri, Branchiura sowerbyi, Aulodrilus pluriseta and Chironomus sp. in XL and Limnodrilus hoffmeisteri, Aulodrilus pluriseta and Bellamya sp. in YL. Seasonal fluctuation occurred, showing richer species in summer and winter, but the density and biomass varied in different ways in the two lakes. Analyses on functional feeding groups indicate that collector-gatherers were predominant, but the relative abundances of other groups were different. Stepwise multiple regression analysis demonstrated that the water depth, conductivity and chlorophyll a were the key factors affecting macrozoobenthic abundance in the lakes.

Accumulation of hepatotoxic microcystins in freshwater mussels, aquatic insect larvae and oligochaetes in a large, shallow eutrophic lake (Lake Chaohu) of subtropical China

This paper studied the seasonal changes of two common microcystins (MCs), MC-RR and -LR, in the commercially important mussel Corbicula fluminea in Lake Chaohu, where there occurred dense cyanobacteria. Occasional measurements were also made for MC in the mussel Arconaia lanceolat, the oligochaete Limnodilus hoffineisteri and the insect larva Chironomus sp. Mean MC of C. fluminea was much higher in hepatopancreas than in intestine and foot. Our study is the first to report accumulation of MCs in oligochaetes and aquatic insect larvae. The hi-h contents of MCs in the insect larvae suggest a great possibility for the transfer of MCs to benthos-feeding omnivores like common carp. According to the provisional standard by the WHO, 28.6% of the collected C. fluminea were harmful for human consumption, assuming a daily consumption of 300 by a person. It is recommended that edible mussels should not be collected for human consumption during toxic cyanobacterial blooms in Lake Chaohu.

New Zealand chironomids as proxies for human-induced and natural environmental change: Transfer functionsfor temperature and lake production (chlorophyll a)

The analysis of chironomid taxa and environmental datasets from 46 New Zealand lakes identified temperature (February mean air temperature) and lake production (chlorophyll a (Chl a)) as the main drivers of chironomid distribution. Temperature was the strongest driver of chironomid distribution and consequently produced the most robust inference models. We present two possible temperature transfer functions from this dataset. The most robust model (weighted averaging-partial least squares (WA-PLS), n = 36) was based on a dataset with the most productive (Chl a > 10 lg l)1) lakes removed. This model produced a coefficient of determination (r2 jack) of 0.77, and a root mean squared error of prediction (RMSEPjack) of 1.31C. The Chl a transfer function (partial least squares (PLS), n = 37) was far less reliable, with an r2 jack of 0.49 and an RMSEPjack of 0.46 Log10lg l)1. Both of these transfer functions could be improved by a revision of the taxonomy for the New Zealand chironomid taxa, particularly the genus Chironomus. The Chironomus morphotype was common in high altitude, cool, oligotrophic lakes and lowland, warm, eutrophic lakes. This could reflect the widespread distribution of one eurythermic species, or the collective distribution of a number of different Chironomus species with more limited tolerances. The Chl a transfer function could also be improved by inputting mean Chl a values into the inference model rather than the spot measurements that were available for this study.

Chlorophyll-a concentrations and macroinvertebrate declines coincide with the collapse of overwintering diving duck populations in a large eutrophic lake

1. Lough Neagh is one of the most important non-estuarine sites in the British Isles for overwinteringwildfowl. A change in the waterbird assemblage following the winter of 2000/2001 was drivenmainly by a rapid decline in the population of overwintering diving ducks. Sudden and discretechanges in resident as well as migratory waterbirds may suggest an intrinsic cause.
2. We compared the density and biomass of benthic macroinvertebrates, the food of overwinteringdiving ducks, in 2010 (following the diving duck population decline) with values from a baselinesurvey conducted in 1997/1998 (before the decline in diving ducks).
3. The mean total density of macroinvertebrates declined significantly by c. 65% from 15 300 m2in1997/1998 to 5136 m2in 2010. There was a concomitant c. 70% decline in mean macroinvertebratebiomass from 15 667 mg m2to 5112 mg m2. In terms of taxonomic composition, the relativecontribution of Tanypodinae, Glyptotendipes spp . and Tanytarsini declined, while the relativecontribution of Chironomus spp. increased.
4. We describe a shift in chlorophyll-a concentration, a proxy of phytoplankton biomass, in thelargest freshwater lake in the British Isles coincident with a significant reduction in macroinverte-brate density and biomass, with potential implications for ecosystem processes and ecologically andeconomically important consumer populations, including waterbirds and fishes