School of BioSciences - Research Publications
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ItemCytogenetic differentiation between Palearctic and Nearctic populations of Chironomus plumosus L-(Diptera, Chironomidae)(NRC Research Press, 1999-10-01)Macrogeographic patterns of chromosomal banding sequences were studied in natural populations of the Holarctic species Chironomus plumosus. Of the 31 inversion sequences now known, 16 are endemic to the Palearctic, 7 are endemic to the Nearctic, and 8 are Holarctic sequences common to both zoogeographic zones. Differences in the sets of inversion sequences found on each continent, plus differing frequencies of Holarctic sequences, result in great overall divergence of karyotypes on the two continents. The karyotype of Nearctic C. plumosus differs from that of Palearctic populations primarily by the presence of a homozygous Nearctic sequence in arm A (n'plu A9), along with fixation (h'plu C2, h'plu E2, and h'plu F1), or high frequency (h'plu D2), of Holarctic sequences which are present but less frequent in the Palearctic. Although long continental isolation has led to great divergence of karyotypes on opposite sides of the Atlantic Ocean, all populations of C. plumosus show sufficient cytogenetic similarity to constitute a single Holarctic species.
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ItemReview of the genus Chironomus (Diptera: Chironomidae). VI. Cytology of the Chironomus maturus complex.(Natural Sciences Research Institute, Eastern New Mexico University, 1974)Two species, Chironomus maturus Johannsen and Chiron- omus whitsell Sublette and Sublette, having the chromosome arm combination AF, BE, CD, and G, are described. An evolutionary relationship to an ancestral group of the thummi- and pseudothummi- complexes as well as the parathummi-complex is postulated.
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ItemYama tahitiensis n.gen., n.sp. from Tahiti (Diptera: Chironomidae).(California Academy of Sciences, 1980)Describes the morphology of the adult male and female, pupa, larva and polytene chromosomes of a new species and genus of chironomid from Tahiti
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ItemNo Preview AvailableOn the Origin of Inversion Polymorphism(University of Chicago Press, 1969-05)
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ItemNo Preview AvailableA variable intron distribution in globin genes of Chironomus:: evidence for recent intron gain(ELSEVIER SCIENCE BV, 1997-12-31)The intron positions found in globin genes of plants, protozoa and invertebrates have been interpreted as evidence for a three-intron-four-exon structure of the ancestral globin gene. In particular, the so-called 'central' introns, which are not found in vertebrate globin genes but are present in a variety of invertebrate and plant species, have been used as an argument for an ancestral gene structure featuring three introns. We have analyzed the presence or absence of central introns in the Gb genes 2beta, 9 and 7A of various European and Australasian species of the insect Chironomus. We find unrelated central introns at different positions in some of the species investigated, while other species completely lack introns in these genes. This variable distribution of introns is parsimoniously explained by independent intron additions. Such a gain of introns may occur convergently at identical positions in unrelated taxa. Insertion by gene conversion may be a viable mechanism to explain intron gain.
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ItemNo Preview AvailableExtraordinary conservation of cysteines among homologous Chironomus silk proteins sp185 and sp220(SPRINGER VERLAG, 1997-04)Aquatic larvae of the midge, Chironomus tentans, synthesize a 185-kDa silk protein (sp185) with the cysteine-containing motif Cys-X-Cys-X-Cys (where X is any residue) every 20-28 residues. We report here the cloning and full-length sequence of cDNAs encoding homologous silk proteins from Chironomus pallidivittatus (sp185) and Chironomus thummi (sp220). Deduced amino acid sequences reveal proteins of nearly identical mass composed of 72 blocks of 20-28 residues, 61% of which can be described by the motif X5-8-Cys-X5-(Trp/Phe/Tyr)-X4-Cys-X-Cys-X-Cys. Spatial arrangement of these residues is preserved more than surrounding sequences. cDNA clones enabled us to map the genes on polytene chromosomes and identify for the first time the homolog of the Camptochironomus Balbiani ring 3 locus in Chironomus thummi. The apparent molecular weight difference between these proteins (185 vs 220 kDa) is not attributable to primary structure and may be due to differential N-linked glycosylation. DNA distances and codon substitutions indicate that the C. tentans and C. pallidivittatus genes are more related to each other than either is to C. thummi; however, substitution rates for the 5'- and 3'-halves of these genes are different. Blockwise sequence comparisons suggest intragenic variation in that some regions evolved slower or faster than the mean and may have been subjected to different selective pressures.
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ItemAn annotated bibliography of the cytogenetics of the Chironomidae (Diptera)(The Natural History Museum, 1996)Bibliography of 1313 references pertaining to the cytogenetics of Chironomidae up to the end of 1990
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ItemNo Preview AvailablePart III. Karyosystematics of selected Chironominae of New Mexico(New Mexico Energy Institute, New Mexico State University, 1979)Karyotypes are described for Chironomus decorum group species 3a, Chironomus utahensis, Chironomus stigmaterus, Stictochironomus new species 1, Stictochironomus new species 2, Stictochironomus marmoreus, Tanytarsus new species 8, Dicrotendipes fumidus, Dicrotendipes neomodestus, Dicrotendipes californicus and Phaenopsectra new species 1. The Chjironomus decorum group offers great promise in water quality assessment through analyses of chromosomal rearrangements and inversion frequencies as related to water quality parameters.
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ItemNo Preview AvailableA review of the genus Chironomus (Diptera: Chironomidae). II. Added descriptions of Chironomus cloacalis Atchley and Martin from Australia.(Natural Sciences Research Institute, University of Eastern New Mexico, 1971)