Research Article |
Corresponding author: Natalya Durnova ( ndurnova@mail.ru ) Academic editor: Paraskeva Michailova
© 2015 Natalya Durnova, Ludmila Sigareva, Olga Sinishkina.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Durnova N, Sigareva L, Sinichkina O (2015) Chromosome analysis of Endochironomus albipennis Meigen, 1830 and morphologically similar Endochironomus sp. (Diptera, Chironomidae) from water bodies of the Volga region, Russia. Comparative Cytogenetics 9(4): 579-593. https://doi.org/10.3897/CompCytogen.v9i4.5172
|
Based upon the detailed chromosome map of polytene chromosomes of the eurybiont species Endochironomus albipennis Meigen, 1830, the localization of the centromere regions using a C-banding technique is defined. Chromosomal polymorphism in populations from two water bodies in the Volga region has been studied, 17 sequences are described. Polytene chromosomes of Endochironomus sp. (2n=6), having larvae morphologically similar to those of E. albipennis Meigen, 1830 (2n=6) are described for the first time.
Diptera , Chironomidae , Endochironomus albipennis , Endochironomus sp., karyotype, polytene chromosomes, chromosomal polymorphism, Volga River
Larvae of Endochironomus albipennis Meigen, 1830 inhabit water bodies of different types. They are typical epibiotic organisms inhabiting submerged objects in the littoral zone, sometimes occurring also inside strongly decomposed plant residues (
The first data about the chromosome number of E. albipennis (2n=6) were reported by
There is neither a unified system of chromosome mapping nor a catalogue of chromosome sequences for E. albipennis. The few available photomaps are partially incomparable with each other. Therefore it is impossible to establish the limits of chromosome rearrangements in the populations of this species.
The main objectives of the present work were to study the chromosome polymorphism in two populations of E. albipennis from the Volga region and to present the list of chromosome sequences of the species. In addition, our aim was to provide the first description of polytene chromosomes of Endochironomus sp., larvae of which are similar in morphology to those of E. albipennis.
The investigations were carried out in three stations in the Volga region (near Saratov). Sixty eight larvae of E. albipennis were collected in Sazanka Lake, Engels (51°29'52"N, 46°4'11"E) and in a pond near Novo-Aleksandrovka village (48°21'00"N, 31°29'00"E). Thirteen larvae of Endochironomus sp. were collected 11.08.2010 in Saratovka River (51°31'9"N, 46°15'57"E) inside decomposing rhizomes of Nuphar luteum (Linnaeus, 1753).
The species were identifying using larval morphology (
Designation of the polythene chromosome arms was made according to
Chromosome I (AD) in the karyotype of E. albipennis: a homozygous for chromosomal sequences in the arms A (A1.1) and D (D1.1) b chromosome I (AD) with two heterozygous inversions – in the arm A (A1.2) and D (D1.2) c chromosome I with two heterozygous inversions – in the arm A (A1.3) and D (D1.2). Chromosome arms after
Chromosome II (BC) in the karyotype of E. albipennis: a homozygous for chromosomal sequences B1 in the arm B (B1.1) and heterozygous for the sequence C3 (C1.3) b chromosome II (BC), for B3 (B3.3) and C1 (C1.1) c chromosome II (BC) with two homozygous inversions (B3.3 and C3.3). The designations are the same as in Fig.
Chromosome III (GEF) in the karyotype of E. albipennis: a homozygous for chromosomal sequences in the arms GE (GE1.1) and in the arm F (F1.1) b homozygous inversion GE2.2 c heterozygous inversion GE1.2 d heterozygous inversion GE1.3. The designations are the same as in Fig.
Chromosome arms and banding sequences in the polytene chromosomes of Endochironomus albipennis.
Chromosome arms ( |
Chromosome arms ( |
Banding sequences ( |
Banding sequences (this study) |
---|---|---|---|
C | A | 1–6a | albA1 (1–16) |
- | albA2 (inversion of section 4–14) | ||
- | albA3 (inversion of section 4–15) | ||
D | D | 6b-15 | albD1 (17–33) |
inversion of section 10–13 | albD2 (inversion of section 24–31) | ||
- | albD3 (inversion of section 22–31) | ||
A | B | 1–5 | albB1 (1–17) |
- | albB2 (inversion of section 9–12?) | ||
- | albB3 (inversion of section 5–8) | ||
B | C | 6–12 | albC1 (19–35) |
- |
albC2 (inversion of section 18–32) |
||
- |
albC3 (inversion of section 24–34) |
||
E | GE | 1–6 | albGE1 (1–16) |
- |
albGE2 (inversion of section 3–10) |
||
- |
albGE3 (some inversion steps) |
||
F | F | 7–12 | albF1 (17–32) |
inversion of section 8–9 | albF2 (inversion of section 21–25) |
Designation of the band patterns conforms to the order of their description: albA1, albA2 etc. Genotypic combinations of banding sequences in every arm were designated as A1.1, A1.2, A2.2, etc., respectively. For analyzing chromosomal polymorphism we calculated the frequencies for every combination of chromosome sequences in each chromosome arm and also the mean number of heterozygous inversions per individual.
Analysis of slides was performed under the microscope MBI-11У4.2. For photomicrography a digital photographic camera Panasonic LS80 LUMIX was used. In the description of the larval morphology the terminology by
Karyotype. Centromeres are not distinct morphologically. Based on the C-banding patterns, chromosomes I (AD) and II (BC) are metacentric, whereas chromosome III (GEF) is acrocentric (Fig.
Localization of the centromere regions in the polythene chromosomes of E. albipennis by C band staining: a chromosome I (AD) b chromosome II (BC) c chromosome III (GEF). The designations are the same as in Fig.
Frequencies (%) of chromosome inversions in the polytene chromosomes of Endochironomus albipennis.
Genotypic combinations | Frequencies (%) | ||
---|---|---|---|
Sazanka Lake, Engels, 12.10.2008, 51 individuals (Present data) | Pond near Novo- Aleksandrovka village, 10.05.2009, 17 individuals (Present data) | Volga River, Saratov, 1971–1972, 1976–1979; 126 individuals ( |
|
A1.1 | 22.7 | 52.9 | 39.7 |
A1.2 | 46.0 | 23.5 | 60.3 (C/C1) |
A2.2 | 3.9 | - | - |
A1.3 | 27.4 | 23.5 | - |
D1.1 | 60.7 | 88.2 | 71.4 |
D1.2 | 23.5 | 5.8 | 28.6 (D/D1) |
D2.2 | 1.9 | 5.8 | - |
D1.3 | 11.7 | - | - |
B1.1 | 37.2 | 29.4 | 85.7 |
B1.2 | - | - | 14.3 (A/A1) |
B3.3 | 43.1 | 58.8 | - |
B1.3 | 17.6 | 11.7 | - |
C1.1 | 43.1 | 29.4 | 25.4 |
C1.2 | - | - | 74.6 (B/B1) |
C1.3 | 23.5 | 17.6 | - |
C3.3 | 27.4 | 47.0 | - |
EG1.1 | 25.4 | 58.8 | - |
EG1.2 | 43.1 | 23.5 | - |
EG2.2 | 9.8 | - | - |
EG1.3 | 19.6 | 17.6 | - |
F1.1 | 98.1 | 100 | - |
F1.2 | 1.9 | - | - |
Number of heterozygous inversions per individual | 1.6 | 1.3 | 3.2 |
Chromosome I (AD).The centromere region was detected using C-banding technique (Fig.
Arm A (Fig.
Arm D (Fig.
Chromosome II (BC).The centromere region is detected using C-banding (Fig.
Arm B (Fig.
Arm C (Fig.
Chromosome III (GEF). Previously it was suggested that this chromosome is the result of tandem fusion of the short chromosome IV with arm E of chromosome EF but the division into arms «GE» and F was made without using C-staining (
Arm GE (Fig.
Arm F (Fig.
Analysis of chromosome polymorphism was performed in comparison with the data of
Larva. Body is yellow, maximal length - 10 mm. The head capsule is light yellow. Submentum of Endochironomus sp. (Fig.
Larvae of E. albipennis (a, c, e, g) and Endochironomus sp. with 2n=6 (b, d, f, h): a, b head capsule (ventral view) c, d mentum e, fVmP (ventromental plates)g, hSSd (seta subdentalis).
Karyotype. Centromeres are not distinct morphologically. Chromosome arms were designated in accordance with the photomap of E. albipennis: I (AD), II (BC), III (GEF), I<II=III.
Arm A (Fig.
Karyotype of Endochironomus sp. (2n=6): a chromosome I (AD) b chromosome II (BC) c chromosome III (GEF). The designations are the same as in Fig.
Arm D (Fig.
Arm B (Fig.
Arm C (Fig.
Arm GE (Fig.
Arm F (Fig.
Among all Endochironomus species detailed cytophotomaps of polytene chromosomes have been earlier compiled only for E. tendens Fabricius, 1775 (
The evolution of E. tendens apparently proceeded as a narrow specialization because larvae of this species are the typical miners in the tissues of littoral macrophytes (
Larvae of Endochironomus sp. (2n=6) are morphologically similar to those of E. albipennis (
Thus, Endochironomus sp. distinctly differs from E. albipennis by the polytene chromosome band patterns, which undoubtedly argues for its separate species status. The chromosome differentiation of these two species was evidently accompanied not only by inversions, but also by duplications of chromosome material (in chromosome I and chromosome II), as indicated by larger number of discs in chromosomes of Endochironomus sp. as compared to E. albipennis.