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1.
A genomic clone containing hemoglobin genes was isolated from a species of the chironomid genus Kiefferulus. Eight genes, including an apparent pseudogene, were sequenced and the amino acid sequences of the putative proteins were determined. By comparison to the previously described hemoglobins in the sister-genus Chironomus, they were identified as members of the dimeric Hb VIIB group. The results indicate that the existence of clusters of hemoglobin genes may be a common feature in chironomids and not just confined to Chironomus. The Kiefferulus genes show greatest similarity of amino acid sequence to Hb VIIB-7 from the Chironomus cluster. The results suggest that the ancestral cluster contained at least two gene types, one of which gave rise to VIIB-7 and the Kiefferulus genes while the other gave rise to the other Chironomus VIIB genes. Both clusters appear to have increased in size by duplication or unequal crossing over since the separation of the genera. It also appears that an unrelated gene present in the Chironomus cluster, Hb-Y, arose from a completely independent origin with no apparent equivalent gene anywhere in the genome of Kiefferulus or some other Chironomus species.
Correspondence to: J. Martin 相似文献
2.
Summary We have investigated interspecific divergence in a eucaryotic gene family, the Balbiani ring genes of the dipteran genusChironomus. In general, our data show thatC. pallidivittatus andC. tentans possess virtually identical Balbiani ring gene sequences, whereasC. thummi represents a more distantly related member of the genus. These results are consistent with phylogenetic relationships for the three species based on polytene chromosome banding patterns. However, one Balbiani ring gene sequence displays an evolutionarily anomalous behavior. A 16-kilobase-pair Balbiani ring gene 1 sequence inC. pallidivittatus that we show to be transcribed is absent in the sibling speciesC. tentans. We propose that this sequence was deleted inC. tentans after divergence of the species. Considering the importance of Balbiani ring genes for feeding and protection of theChironomus larvae, we suggest that the pronounced interspecific genetic difference contributes to a difference in ecological niche between the two sympatrically distributed species. 相似文献
3.
Klaus Hägele 《Chromosoma》1977,63(1):79-88
The N-banding patterns of the polytene chromosomes of Drosophila melanogaster, Chironomus melanotus, Ch. th. thummi and Ch. th. thummi x Ch. th. piger were studied. In Chironomus the polytene N-banding patterns correspond to the polytene puffing patterns. This is revealed by comparison of the puffing and N-banding patterns of identical chromosomes. Size and staining intensity of the N-bands reflect the size of the puffs as shown by puff induction. There is no evidence that the N-bands are also located in Chironomus heterochromatin or are restricted to the nucleolar organizer regions. In Drosophila the -heterochromatin is strongly N-positive, whereas the -heterochromatin, as well as the Chironomus heterochromatin is not N-banded. Contrary to Chironomus, the puffs in Drosophila polytene chromosomes do not give rise selectively to well stained N-bands. — The N-banding method is interpreted to stain specifically non-histone protein which is (1) accumulated in genetically active chromosome regions and (2) present in a specific type of heterochromatin (-heterochromatin of Drosophila). 相似文献
4.
5.
Galactose feeding of Chironomus thummi larvae induces the regression of Balbiani ring c (BRc) and the full expansion of BRb, both localized in the IV salivary gland chromosome. This effect coincides with that described on BR2 and BR1 of Ch. pallidivittatus and Ch. tentans. The puffing changes of BRb and BRc throughout development have been studied and also show identical variations as in BR1 and BR2 of Ch. pallidivittatus and Ch. tentans. The similar behaviour of BRb and BR1, and of BRc and BR2 respectively after galactose treatment and throughout development strongly suggests that these BRs play the same physiological role in the three Chironomus species, with BRb = BR1 and BRc=BR2. 相似文献
6.
In situ localization of two haemoglobin gene clusters in the chromosomes of 13 species of Chironomus
Two haemoglobin (Hb) gene clusters cloned from the genomic DNA of Chironomus thummi were localized in the polytene chromosomes of 13 Chironomus species. The haemoglobin gene cluster containing the genes for the monomeric haemoglobin proteins III and IV (CttG1) hybridized in all species to the end of chromosome arm E. The haemoglobin gene cluster containing the genes for the dimeric HbVIIB proteins (piHb1) could be localized to chromosome arm D. The chromosomal position of the haemoglobin genes was always found in morphologically specified groups of bands and is in agreement with cytological data, which have been used to establish the evolutionary relationships between the species of the genus Chironomus. 相似文献
7.
Ulf Lönn 《Chromosoma》1981,81(5):641-653
The effect of the drug 5-fluorodeoxyuridine on DNA synthesis in Chironomus polytene chromosomes was investigated. The DNA was labelled by injection of radioactive precursor into living animals pre-treated with the drug, extracted with a neutral non-denaturing buffer at 25 ° C and then characterized by gel electrophoresis. After a short pulse a heterogeneous double-stranded DNA population is released from the polytene chromosome. These fragments are later joined together to produce a double-stranded DNA with a size ranging between 8–13 × 106 D. The release of both types of fragments from the polytene chromosome is prevented by lysing the cells at 0 ° C instead of at 25 ° C. The larger double-stranded DNA has the size expected of replicons in Chironomus. The results are discussed in relation to the organization of replication in polytene chromosomes. 相似文献
8.
Shizuo Yagi 《Chromosoma》1984,89(4):274-279
Treatment of Chironomus larvae with dilute (0.5%–1.0%) ethanol results in puffing changes similar to those obtained with galactose in the Balbiani rings (BRs) of the salivary gland chromosomes. A shift in the relative size of BR1 and BR2 in chromosome 4 of C. pallidivittatus or C. tentans was observed within 1–2 days after ethanol treatment. The exceptional Balbiani ring, BR6 in chromosome 3, began to appear within 1 day after ethanol treatment of C. pallidivittatus and was fully developed after 3–4 days. Prepupae appeared to be refractory to the treatment. To localize possible controls of BR puffing in Chironomus, ligatures were made at various positions along the thorax and the anterior abdominal segments of the ethanoltreated larvae. In surviving larvae, ligated anterior to the brain or posterior to the salivary glands, induction of BR6 could be detected. In contrast, little or no BR6 puff induction was found in animals ligated in the middle of the second segment approximately between the brain and the salivary glands. No shift in the BR1/BR2 relation occurred with any of the ligations combined with ethanol treatment. 相似文献
9.
Conventionally, dye-exclusion test for determining cell viability has been restricted only for cells in suspension in tissue
culture. In this paper, salivary gland of Chironomus has been proposed as a simple tissue model system where dye-exclusion test can be reliably employed for the intact gland.
We have compared suitability of commonly used vital dyes and nigrosin was found suitable for the salivary gland cells. Biochemical
tests using tetrazolium salts are also commonly used for determining quantitative indices of cell viability in metabolically
active cells. Ours is the first attempt to extend the same technique for the whole tissue. We standardized the conditions
and prepared a protocol for MTT-based colorimetric assay suitable for the salivary gland of Chironomus. A strong correlation (r2 = 0.9893) was obtained where increasing O.D. correlated linearly with the number of live glands. We concluded that nigrosin
dye-exclusion and MTT metabolic inclusion assays are suitable methods for the viability test of metabolically active intact
salivary gland of Chironomus which can serve as a potential model for the assessment of cytotoxicity in future. 相似文献
10.
11.
Summary InSolanum lycopersicum pachytene chromosomes the gradient in chromomere size, originating on both sides of the kinetochore, reveals the following characteristics: 1. a relatively abrupt decrease in size of the large chromomeres, 2. the gradient is related to arm length in 9 of the 12 chromosomes, 3. the gradient is particularly irregular in the short arm of the nucleolar chromosome and in the long arm is not conspicuous, 4. chromosome 6 shows an abrupt interruption in the gradient close to the kinetochore.
Salvia viridis andZea mays chromosomes represent intermediate conditions between species with well defined and species without gradients. InSalvia the intermediate condition is manifested by the presence of a very large chromomere on each side of the kinetochore followed by very small chromomeres. In two chromosomes the intermediate condition is particularly apparent. In these chromosomes two chromomeres of intermediate size are present in the proximal region of the long arm. The nucleolar organizing arm has also an irregular pattern in this species.Maize has a less distinct gradient than tomato in all its chromosomes. Chromosomes 3, 4, 5 and 8 are those where the gradient is the least sharp. The nucleolar organizing arm of chromosome 6 has also an irregular pattern.In a translocation between chromosomes 5 and 6 of maize, a segment composed of very small chromomeres from the distal region of 5 which was moved to the right of the kinetochore of chromosome 6, did not change appreciably its phenotype after ten years of cultivation. During the period of cultivation a selection was made for plants where the original phenotype was preserved so that this result cannot be considered as demonstrating an absence of change in chromomere phenotype with changed position.InDrosophila andChironomus salivary gland chromosomes where chromomeres are large, and no selection has been carried out with such a purpose, the pattern and nucleic acid content of the bands is known to change when rearrangements occur within the chromosome.Supported by a grant from the Swedish Natural Science Research Council toA. Lima-De-Faria. This work was partly carried out at the Department of Botany, University of Illinois, U.S.A. during a visit to this department byA. Lima-De-Faria.P. Sarvella's collaboration in this work was done during her stay at the University of Lund. 相似文献
12.
Prey switching in four species of carnivorous stoneflies 总被引:1,自引:0,他引:1
J. M. Elliott 《Freshwater Biology》2004,49(6):709-720
1. Previous studies compared the functional responses to their prey, and both intraspecific and interspecific interference, in mature larvae of Dinocras cephalotes, Perla bipunctata, Isoperla grammatica and Perlodes microcephalus. The present study examines switching by larvae of the same species presented with different proportions of two contrasting prey types; larvae of Baetis rhodani and Chironomus sp. In each experiment, 200 prey were arranged in nine different combinations of the two prey types (20 : 180, 40 : 160, 60 : 140, 80 : 120, 100 : 100, 120 : 80, 140 : 60, 160 : 40, 180 : 20). Prey were replaced as they were eaten. A model predicted the functional response in the absence of switching and provided a null hypothesis against which any tendency for switching could be tested. 2. No evidence for prey switching by Dinocras and Perla was obtained, both species showing a slight preference for Baetis over Chironomus. Prey switching occurred in Isoperla and Perlodes. As the relative abundance of one prey type increased in relation to the alternative, the proportion eaten of the former prey changed from less to more than expected from its availability, the relationship being described by an S‐shaped curve. Isoperla and Perlodes switched to a preference for Baetis when its percentage of the total available prey exceeded 57 and 42%, respectively. Equivalent values for Chironomus were 43 and 58% for Isoperla and Perlodes, respectively. Switching was strongest in Perlodes. 3. Non‐switching in Dinocras and Perla was related to their feeding strategy, both species being more successful when using a non‐selective ambush strategy at dusk and dawn rather than a search strategy during the night. Both Isoperla and Perlodes used a search strategy. The smaller Isoperla fed chiefly at dusk and dawn, and preferred Chironomus larvae, whereas most of the larger Perlodes fed continuously from dusk to dawn and preferred Baetis larvae. 相似文献
13.
Polytene chromosomes of Chironomus thummi were stretched to their rupture in a pronase solution. A 176±26-fold elongation was achieved. The DNA compaction ratio, defined as the ratio of DNA length in a haploid set (85±5 mm) to the length of a polytene chromosome set (520±40 m), was 164±22. Closeness of these two values demonstrates the uninemy of the chromatids of Chironomus chromosomes. The effect of ethidium bromide on the elastic properties of chromosomes prestretched in a pronase solution and the lengthening of these chromosomes after ethidium staining suggest that DNA molecules are double-stranded and supercoiled to the moment of the chromosome rupture. It is concluded that a Chironomus chromatid consists of a single DNA molecule (or of a single chain of linked DNA molecules) both ends of which are located in the telomeres.To the memory of Prof. Vera V. Khvostova 相似文献
14.
Cis-dichlorodiammine platinum (II) has been reacted with synthetic polynucleotides either in B or in Z conformation. The binding
of cis-dichlorodiammine platinum (II) stabilizes the Z conformation when reacted with poly (dG-m5dC) ·poly (dG-m5dC) in the Z conformation as shown by circular dichroism and by the antibodies to Z-DNA. On the other hand, the binding of
cis-dichlorodiammine platinum (II) stabilizes a new conformation when reacted with poly(dG-dC)·poly(dG-dC) or poly (dG-m5dC)·poly(dG-m5dC) in the B conformation. The antibodies to Z-DNA bind to these platinated polynucleotides. In rabbits, the
injection of platinated poly (dG-dC) poly (dG-dC) induces the synthesis of antibodies which recognize Z-DNA. In low salt conditions,
the circular dichroism spectra of these platinated polynucleotides differ from those of B-DNA or Z-DNA. The characteristic31P nuclear magnetic resonance spectrum of Z-DNA is not detected. It appears only at high ionic strength, as a component of
a more complex spectrum. 相似文献
15.
Drosophila salivary chromosomes have been isolated at neutral pH and physiological ionic strength. They display only background level binding of antibodies against Z-DNA. Following exposure to the commonly used fixative 45% acetic acid all of the polytene chromosomes, X and autosomes, show a massive increase in anti-Z-DNA antibody binding. The enhancement from background to intense fluorescence occurs whether the chromosomes are stabilised by two orders of magnitude lower concentration of formaldehyde than that used to minimise protein extraction in classical acid squash preparations, or by physiological concentrations of spermine and spermidine. Nicking of acetic acid-treated chromosomes by DNase I dramatically reduces their Z-DNA immunoreactivity. The histones and non-histones extracted by 45% acetic acid from unfixed and formaldehyde-fixed Drosophila chromatin have been analysed. Exposure of isolated salivary chromosomes to the non-protein-extracting fixative 95% ethanol also enhances Z-DNA immunoreactivity. All of these phenomena must be taken into account in the search for the Z-DNA conformation in cells by cytological techniques. 相似文献
16.
J.M. ELLIOTT 《Freshwater Biology》2006,51(5):913-924
1. Ontogenetic shifts in predator behaviour can affect the assessment of food‐web structure and the development of predator–prey models. Previous studies have shown that the diel activity pattern and functional response differed between larval instars of the carnivorous caddis, Rhyacophila dorsalis. The present study examines switching by larvae of R. dorsalis presented with different proportions of two prey types; either small (length 2–4 mm) and large (5–8 mm) Chironomus larvae for second, third, fourth and fifth instars of R. dorsalis; or Baetis rhodani (9–12 mm) and large Chironomus larvae for fourth and fifth instars. Experiments were performed in stream tanks with one Rhyacophila larva per tank and 200 prey arranged in nine different combinations of the two prey types (20 : 180, 40 : 160, 60 : 140, 80 : 120, 100 : 100, 120 : 80, 140 : 60, 160 : 40 and 180 : 20). Prey were replaced as they were eaten. A model predicted the functional response in the absence of switching and provided a null hypothesis against which any tendency to switch could be tested. 2. There was no prey switching in the second and third instars, with both instars always showing a preference for small over large Chironomus larvae. Prey switching occurred in the fourth and fifth instars. As the relative abundance of one prey type increased in relation to the alternative, the proportion eaten of the former prey changed from less to more than expected from its availability, the relationship being described by an S‐shaped curve. In the experiments with small and large Chironomus, the two instars switched to large larvae when their percentage of the total available prey exceeded 29% and 37% for fourth and fifth instars, respectively. In the experiments with Baetis and large Chironomus, both instars switched to Baetis larvae when their percentage of the total available prey exceeded 36%. 3. Non‐switching in second and third instars was related to their feeding strategies, both instars preferring smaller prey items. When the fourth and fifth instars foraged actively at night, they preferred larger over small Chironomus larvae, but when they behaved as ambush predators at dusk, they captured the more active Baetis larvae in preference to the more sedentary large Chironomus larvae and only switched to the latter when they were >64% of the available prey. 相似文献
17.
18.
Larvae of Axarus andLipiniella share several apparantly apomorphic features of the mouth-part structure, however adults ofLipiniella show possible relationships toDemeijerea andChironomus. In order to assist in refining the relationships ofAxarus toLipiniella the karyotype ofAxarus festivus was determined and compared to the karyotypes ofLipiniella arenicola andL. moderata. Larvae ofA. festivus from a population in Kansas were monomorphous, with 2n=8, the Ist, IInd and IIIrd chromosomes metacentric, and IVth acrocentric.Axarus festivus therefore differs fromL. arenicola in chromosome number (2n=6), however homologous sections of all chromosomes were identified. Inversions were detected in the Ist, IInd and IIIrd chromosomes ofA. festivus relative toL. arenicola. It was determined that both species have high functional activity, as indicated by the presence of three Balbiani rings, and more than one nucleolus per genome. Differing degrees of polyteny, a feature previously described forL. arenicola, were observed in the salivary glands, with highest degrees of polyteny in cells near the salivary duct. These similarities of chromosome structure indicate close genetic relationships betweenA. festivus andL. arenicola. However, we did not find evidence for similarity ofA. festivus toL. moderata, which supports the previous conclusions byKiknadze
et al. (1989) regardingL. arenicola andL. moderata. 相似文献
19.
The morphology of the larval ventromental plates of Y. tahitiensis Sublette & Martin and four Oceanian species of Chironomus Meigen, C. hawaiiensis Grimshaw, C. javanus Kieffer, C. magnivalva Kieffer and C. samoensis Edwards, has been studied by scanning electron micrography. Data on ventromental plate ultrastructure are used in phenetic and cladistic analyses of the relationships of T. tahitiensis and the Oceanian Chironomus to other species in Chironomus and additional genera. The results of these analyses support the current generic status of T. tahitiensis but indicate that Yama is less closely related to Chironomus than previously supposed, a finding that is supported by a reexamination of ‘traditional’ morphological features. 相似文献
20.
L. I. Gunderina I. I. Kiknadze A. G. Istomina V. D. Gusev L. A. Miroshnichenko 《Russian Journal of Genetics》2005,41(2):130-137
Banding sequences of five chromosomal arms (A, C, D, E, and F), accounting for about 70% of the total genome size in 63 Chironomus species, were used as markers to analyze divergence patterns of the linear genome structure during the evolution. The number of chromosomal breakpoints between the pairs of banding sequences compared served as a measure of divergence. It was demonstrated that the greater the divergence between the species compared, the higher the number of chromosomal breakpoints and the smaller the size of the conserved chromosomal segments. A banding sequences comparison in sibling species demonstrated a lower number of chromosomal breakpoints; the breakpoint number was maximum in a comparison of the banding sequences in the subgenera Chironomus and Camptochironomus. The use of the number of chromosomal breakpoints as a genome divergence measure provided establishment of phylogenetic relationships between 63 Chironomus species and discrimination of sibling species groups and cytocomplexes on a phylogenetic tree.Translated from Genetika, Vol. 41, No. 2, 2005, pp. 187–195.Original Russian Text Copyright © 2005 by Gunderina, Kiknadze, Istomina, Gusev, Miroshnichenko. 相似文献