Phylogenetic Relationships among Holarctic Populations of Chironomus entis and Chironomus plumosus in View of Possible Horisontal Transfer of Mitochondrial Genes

In eight Holarctic populations of two typical chironomid sibling species of the plumosus group, Chironomus entisandChironomus plumosus, nucleotide sequences of mitochondrial (cytb) and nuclear (gb2b) gene regions were examined. The phylogenetic trees reflecting the evolutionary histories of the nuclear and mitochondrial markers exhibited significant differences. On the tree based on the nuclear gene sequences the populations clustered according to their species affiliation, whereas on the tree based on the mitochondrial gene sequences the populations were grouped according to their geographic position. This discrepancy is probably explained by mitochondrial gene flow between sympatric species with incomplete reproductive isolation (sibling species). Based on our results together with the earlier data on nuclear and mitochondrial gene sequences of some other species from the phylogenetic group plumosus, a scheme of phylogenetic relationships within this group is proposed. This scheme is in many ways different from the traditional view on the evolutionary relationships among species of the plumosus group.     

On the validization of the name Chironomus (Camptochironomus) pallidivittatus sensu edwards, 1929 and elimination of the name Chironomus pallidivittatus Malloch, 1915

The name Chironomus pallidivittatus sensu Edwards is widely used by specialists for the European species described by Edwards, whereas the use of the name Ch. tentans var. pallidivittatus Malloch is limited. In the light of the wide use of the name Chironomus pallidivittatus sensu Edwards, particularly in fields outside taxonomy, combined with virtually no publications on the Ch. tentans variety pallidivittatus Malloch, we recommend that the original Malloch’s application of the name should be suppressed in favor of that of Edwards, 1929. At the same time, synonymy of Ch. pallidivittatus s. Malloch with Ch. tentans Fabricius supposed by Townes (1945) is erroneous. Detailed cytogenetic (Kiknadze et al., 1996) and morphological (Shobanov et al., 1999) studies of North American, European, and Asian populations demonstrated the common occurrence of Ch. dilutus Shobanov, Kiknadze et Butler, 1999 in the Nearctic. This species is different from Ch. tentans but identical with Ch. tentans var. pallidivittatus Malloch, 1915 and the “Nearctic Ch. tentans” sensu Townes (1945).     

On the Possibility of Hybridogenesis in the Origin of Midge Chironomus usenicus Loginova et Beljanina (Chironomidae,Diptera)

Hybridogenesis as a possible way of speciation in Chironomidae was considered with special reference to the species Chironomus usenicus resulting from hybridization between C. plumosus and C. behningi. The three species had 2n = 8 and belonged to the thummi cytocomplex with chromosome arm combinations AB, CD, EF, and G. Arm G had a marker chromosome disk sequence (CDS) and was used to demonstrate the hybrid origin of C. usenicus. Most C. usenicus larvae were heterozygous in CDS of arm G. CDS use G2 proved to be identical to CDS beh G1 ofC. behningiand CDS use G1, to CDS plu G1 of C. plumosus. It was assumed that C. usenicus results from hybridization between eurybiont C. plumosus and stenobiont C. behnigni at the boundary of their species areas, in freshwater or brackish water bodies of the southern Saratov oblast and northern Kazakhstan. Morphologically and karyotypically, the hybrid was probably similar to C. plumosus. Crosses with C. plumosus eliminated virtually all C. behningi chromosome sequences from the karyotype of the hybrid. Further chromosome divergence resulting in C. usenicus involved a number of chromosome rearrangements, including duplication of pericentric heterochromatin and other chromosome regions; inversion, which occurred in arm F (regions 13–16) and was fixed in the karyotype; and other paracentric inversions and deletions accumulated in heterozygote in the karyotype pool of the species. Since C. behningi was eliminated from the introgression zone and its species area reduced, the assimilation character was assumed for introgressive hybridization of C. behningi and C. plumosus.     

Tissue specific gene activities and proteins in the Chironomus salivary gland

Summary The secretory proteins of the larval salivary gland of some Chironomus species were analysed according to a method developed by Grossbach (1969). After reduction of the disulphide bonds and alkylation the secretion of Chironomus thummi was separated by disc electrophoresis at acrylamide concentrations of 4.8 to 9.5% into seven main and some minor fractions. By increasing the acrylamide concentration up to 20% nine main fractions could be resolved. In addition to these high molecular weight structural proteins a number of proteins soluble in simple buffer solutions and separable at pH 8.8 in a 15% acrylamide gel are present in the secretion but only to a very small amount.The electrophoretic pattern of the secretory proteins of Chironomus strenzkei, Ch. luridus and Ch. obtusidens are qualitatively the same as the Ch. thummi pattern. Some quantitative differences may exist. In the secretion of Chironomus plumosus at least eleven main fractions were detected in 20% acrylamide gels. A comparison between the number of Balbiani rings of the salivary gland chromosomes and the number of main protein fractions in the salivary gland secretion yielded no direct correlation.The results are discussed in respect to the question wether the major puffs of the gland, the Balbiani rings, encode the major products of the gland, the secretory proteins.Abbreviations used BR Balbiani ring - bis N,N-Methylenebisacrylamide     

Phylogenetic relationships of the Baikal endemic Paratanytarsus baicalensis (Tshern.) with representatives of genera Paratanytarsus Thien. et Bause and Micropsectra Kieff. (Diptera, Chironomidae)

The phylogenetic relationships of the Baikal endemic chironomid Paratanytarsus baicalensis (Tshern.) and other representatives of the tribe Tanytarsini were studied using 117 partial sequences of the mitochondrial COI gene from 33 species of the genera Paratanytarsus and Micropsectra. The results show that the Baikal species is close in origin to two geographically distant European species, P. austriacus and P. hyperboreus, and itself splits into two genetically distinct clades.     

C-banding in the polytene chromosomes of species of the plumosus group (Diptera,Chironomidae) and their experimental hybrids

The localization and amount of heterochromatin in the plumosus group were studied, including the species Chironomus plumosus L., C. vancouveri and C. balatonicus. The appearance of C bands of Chironomus plumosus in several European populations is traced. The role of the C heterochromatin in the differentiation of this species is discussed. From the evolutionary point of view the Swiss populations, in which large centromere heterochromatin blocks have been discovered, are more varied as to the amount of heterochromatin. The importance of duplications for this process is pointed out. The chromosomes of the individuals from C. vancouveri and C. balatonicus have centromeric, telomeric and interstitial heterochromatin. The centromeric heterochromatin is represented by thin C-bands. The particularities in the appearance of C heterochromatin in C. vancouveri and C. balatonicus reflect the structural peculiarities of their chromosomes. The change in the euchromatin regions in these forms is discussed in the light of transformation of euchromatin to heterochromatin in the process of evolution.The appearance of heterochromatin in hybrids (between populations and between species) created experimentally is traced. A change has been discovered in the appearance of heterochromatin in the hybrids compared to the initial parent forms. This difference is expressed more strongly in inter-species hybrids than in interpopulation hybrids of C. plumosus.     

B-Chromosomen beiChironomus

In the population “Herrenmühle” ofChironomus plumosus 11% of the individuals contain one supernumerary chromosome. This B-chromosome is present both in germ-line and somatic cells. — InChironomus melanotus 6% of the larvae of the population “Falkau” carry supernumerary chromosomes. These B-chromosomes cannot be found in all nuclei of testis and soma, their number varies between cells within the individual. In both species the B-chromosomes represent centromeric fragments of chromosome IV as can be shown by their structure and pairing behaviour. — The polytene B-chromosome ofCh. plumosus exhibits a banding pattern in the salivary gland nuclei. Furthermore it is able to form an additional nucleolus in the nuclei of the malpighian tubules. InCh. melanotus band structures can be seen only in the B-chromosome of malpighian tubules. The larvae ofCh. melanotus, carrying B-chromosomes, show heterochromatic bodies in the salivary gland nuclei, varying in number and size in the nuclei of the same gland. These bodies are interpreted to be polytenic B-chromosomes divided into subunits.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Identification of left-handed Z-DNA by indirect immunofluorescence in polytene chromosomes of Chironomus thummi thummi

In this work, antibodies against Z-DNA were used to stain polytene chromosomes of Chironomus thummi thummi. By indirect immunofluorescence we report the first identification of left-handed conformation of DNA in a band region. The Chironomus pattern also contrasts with the general staining observed in Drosophila. In Chironomus the antibodies to Z-DNA bind to one interband region of the chromosome II and two bands regions of the chromosome IV.     

DNA sequences of the mitochondrial COI gene have low levels of divergence among deep-sea octocorals (Cnidaria: Anthozoa)

We are analyzing genetic diversity in deep-seamount octocorals with the ultimate goal of studying the effect of retention and dispersal of larvae on genetic population structure. Here we report on the sequence diversity of the mitochondrial cytochrome oxidase I (COI) gene among 11 species. Uncorrected pairwise sequence divergences ranged from 0.4–10.3% for comparisons among species spanning the intrageneric to interordinal levels. Relative to other invertebrates, these divergences are very low, suggesting that COI may not be useful as a genetic marker for studying dispersal among deep-sea octocoral populations. Possible explanations for the reduced rates of divergence observed include a lower rate of evolution for octocoral mitochondrial genomes and the presence of a gene, mtMSH, which may code for a mitochondrial DNA mismatch-repair system. We report the finding of mtMSH in three deep-sea octocorals (Acanthogorgia sp., Corallium ducale, and Paramuricea sp.), which brings the total published observations of this gene to six species, all in the subclass Octocorallia.     

Reliable molecular identification of nine tropical whitefly species

The identification of whitefly species in adult stage is problematic. Morphological differentiation of pupae is one of the better methods for determining identity of species, but it may vary depending on the host plant on which they develop which can lead to misidentifications and erroneous naming of new species. Polymerase chain reaction (PCR) fragment amplified from the mitochondrial cytochrome oxidase I (COI) gene is often used for mitochondrial haplotype identification that can be associated with specific species. Our objective was to compare morphometric traits against DNA barcode sequences to develop and implement a diagnostic molecular kit based on a RFLP‐PCR method using the COI gene for the rapid identification of whiteflies. This study will allow for the rapid diagnosis of the diverse community of whiteflies attacking plants of economic interest in Colombia. It also provides access to the COI sequence that can be used to develop predator conservation techniques by establishing which predators have a trophic linkage with the focal whitefly pest species.     

Non xenopus-like DNA sequence organization in the Chironomus tentans genome

Summary We have examined the sequence organization of Chironomus tentans DNA by means of optical and hydroxyapatite renaturation kinetics of total DNA fragment sizes of 0.36, 2.6 and 13.5 kilobases (kb) as well as isolated middle repeat DNA at sizes of 0.36 and 13.5 kb. 90% of the DNA renatured as unique sequences of a genome of 0.20 pg with the balance of DNA renaturing as middle repetitive sequences present on average 90 times per haploid genome. At a DNA fragment length of 13.5 kb, 35% of the DNA was trapped on the hydroxyapatite as middle repetitive fraction. We concluded C. tentans DNA to have a mean repeat length of about 4.3 kb distributed through out at least 35% of the genome with an inter repeat spacing of at least 13.5 kb but possibly being distributed throughout the whole genome with an inter repeat spacing of 36 kb. This shows C. tentans DNA organization not to follow the almost ubiquitous Xenopus model but to be similar to the organization of Drosophila melanogaster DNA.     

Molecular phylogeny and historical biogeography of the genus Platycerus (Coleoptera,Lucanidae) in East Asia

The genus Platycerus is a cool temperature zone taxon widely distributed in the Northern Hemisphere. In East Asia, 10, one and 28 species are known in Japan, Korea and China, respectively. Recent studies of Platycerus have revealed the divergence pattern in Japan and South Korea, but that of Chinese Platycerus is unknown. We conducted a phylogenetic and biogeographical study of Platycerus in East Asia, including China, using 68, 87 and 296 sequence data of the nuclear wingless gene, internal transcribed spacer (ITS) region and mitochondrial COI gene, respectively. Although the introgression of mitochondrial genes had been known in Japanese Platycerus, the essential contradiction was not recognized between the phylogenetic trees of nuclear genes and COI in Chinese Platycerus. In the COI tree, the Japanese clade and Asian continental clade diverged around 10.84 million years ago, and four major clades were recognized in the latter. For the shape of the posterolateral corner of the Platycerus pronotum, sharp (S)-type species are distributed in higher latitudinal and lower altitudinal areas than round (R)-type species in the Asian continent. S-type species have evolved from R-type species at least three times in more northerly areas, where the annual amplitude of temperature change is large. The genus Platycerus has been differentiated and speciated by a process unique to South Korea, Japan and China, according to regional topography. Thus, genetic differentiation and speciation in Platycerus are related to latitudinal and altitudinal gradients, as well as the site topographical profile and niche differentiation.     

Composition and distribution of sibling species of <Emphasis Type="Italic">Chironomus</Emphasis> Meigen, 1803 (Diptera,Chironomidae) in Curonian Lagoon of the Baltic Sea

The species composition of Chironomus in the Curonian Lagoon has been investigated. It was shown that three sibling species of the plumosus group, namely, Ch. plumosus, Ch. balatonicus, and Ch. muratensis, and a first-generation interspecific hybrid Ch. muratensis × Ch. plumosus lived here. The occurrence frequency in the lagoon was 87, 19, 6, and 3% for Ch. plumosus, Ch. balatonicus, Ch. muratensis × Ch. plumosus, and Ch. muratensis, respectively. The species Ch. plumosus was recorded in all the areas (southern, central, and northern), while Ch. balatonicus was found only in the northern area in the village of Juodkrante near the city of Klaipeda. Presumably, the distribution of these sibling species is due to the presence of a salinity gradient in the lagoon.     

MEC: A transposable element from Chironomus thummi (Diptera)

Summary Two genomic clones, pC1.2 and p20D (containing inserts of 2.0 and 1.6 kb, respectively) were isolated from the A2b region to polytene chromosome IV of Chironomus thummi thummi salivary gland cells. Upon in situ hybridization to polytene chromosomes of C. thummi thummi and C. thummi piger, p20D DNA hybridized mainly over the A2b region of chromosome IV, whereas pC1.2 DNA hybridized to at least 90 sites distributed over all the chromosomes. A partial nucleotide sequence analysis showed that these clones were very similar and allowed the detection of a 596 by insert in the pC1.2 clone. This insert possesses all of the essential features of a Class II transposable element and was called MEC. It carries a nearly perfect 107 by terminal inverted repeat containing one mismatch and is flanked by a 5 by direct repeat. The 372 by central region contains a short open reading frame with a coding capacity of 58 amino acids.     

Analysis of mitochondrial COI sequences of the Diachasmimorpha longicaudata (Hymenoptera: Braconidae) species complex in Thailand

Diachasmimorpha longicaudata is an Opiinae parasitoid used to control tephritid fruit flies, which cause tremendous economic losses of fruits worldwide. In Thailand, D. longicaudata is classified as three sibling species, DLA, DLB and DLBB, based on the morphological and biological species concepts but their genetic variation has not been studied. Therefore, we investigated the genetic differentiation of the mitochondrial COI gene to clarify the ambiguous taxonomy of this species complex. The 603‐bp COI region was sequenced from laboratory‐bred colonies and field‐collected specimens from seven locations representing five geographical regions in Thailand. DLA was associated with the host Bactrocera correcta while DLB and DLBB were associated with Bactrocera dorsalis. The interspecific nucleotide differences of COI sequences among the three groups ranged from 6.70% to 7.62% (Kimura 2‐parameter distance), which adequately separates species complexes within the order Hymenoptera and supports the current sibling species classification. The neighbor joining, maximum likelihood and consensus Bayesian phylogenetic trees constructed from COI sequences revealed that the three sibling species of laboratory and field‐collected D. longicaudata are monophyletic with 100% support. The high genetic variation and molecular phylogeny of the COI sequences were shown to discriminate between the D. longicaudata species examined in this study.     

Delineating geographic boundaries of the woolly mouse opossums, Micoureusdemerarae and Micoureus paraguayanus (Didelphimorphia: Didelphidae)

This paper reports on molecular classification of the woolly mouse opossum, Micoureus spp., in the southeastern Atlantic Forest in Brazil, a hotspot of critically threatened biodiversity. Phylogenetic analysis and character-based diagnosis were done using DNA sequences from the mitochondrial cytochrome b gene and cytochrome c oxidase subunit I genes, and exon 6 of the nuclear dentine matrix protein 1 gene (DMP1). Although the nuclear DMP1 gene showed insufficient genetic variation for species diagnosis, the mtDNA analyses resulted in the robust grouping of samples of the M. paraguayanus/M. demerarae complex into three clades with distinct DNA sequence diagnostics for the species units in this study. The results support the species status of M. paraguayanus (Tate in Am Mus Novit 493: 1–13, 1931), which has a geographic distribution in the Atlantic Forest from the North and Northeast of Minas Gerais state in Brazil, going south along the coastal region of Brazil, to Paraguay and Argentina. Evidence of the boundary for this species and the provided diagnostics should facilitate and improve accuracy of studies that have been done in critical threatened fragments of the Atlantic Forest, especially in Minas Gerais and Bahia states, Brazil.     

Peculiarities of structural organization of hemoglobin of <Emphasis Type="Italic">Chiromonus plumosus</Emphasis> L. (Diptera: Chironomidae)

In Ch. plumosus and Ch. riparius there were revealed various structural hemoglobin variants including monomers, dimers, trimers, tetramers, hexamers, and octamers. The multitude of the protein organization ways seems to be based on diversity of monomers with the approximately equal molecular mass from 12 to 16 kDa in Ch. plumosus and from 11.8 to 15.2 kDa in C. riparus. In PAAG with 8 M urea, the hemoglobins were aggregated into high molecular complexes with mol. masses about 260 and 180 kDa in Ch. plumosus and about 523 and 174 kDa in C. riparus.     

Homology of Balbiani rings among chironomid species and localization of a new mobile element on the polytene chromosomes

The results ofin situ cross-hybridization of the cloned DNA fragments of BRa, BRb and BRc fromChironomus thummi to the polytene chromosomes of 14Chironomus species andCamptochironomus tentans are presented. BRs of the species studied were demonstrated to contain the homologus DNA sequences. The cloned fragment from the BRa ofC. thummi hybridized with the BRa ofC. piger and with a region on the arm G ofC. tentans andC. plumosus, the latter species had no extra BR. The clone 16 from the BRb ofC. thummi hybridized only with the developed BR on the arm G of all species studied. The sequence from the BRc ofC. thummi was located in the BRc ofC. piger and in the developed BR ofC. plumosus andC. nuditarsis, which were located at the most distal end of arm G. These clones can be used as markers of homologous BRs. The new mobile elements C6.10 fromC. thummi genome were localized on the polytene chromosomes of 10Chironomus species andCamptochironomus tentans. The species of the generaLipiniella, Cryptochironomus andGlyptotendipes did not contain the sequences homologous to ME C6.10.