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Karyotypical characteristics of two allopatric African populations of anhydrobiotic Polypedilum Kieffer, 1912 (Diptera, Chironomidae) originating from Nigeria and Malawi.

Petrova NA, Cornette R, Shimura S, Gusev OA, Pemba D, Kikawada T, Zhirov SV, Okuda T - Comp Cytogenet (2015)

Bottom Line: The African chironomid Polypedilumvanderplanki Hinton, 1951 is the only chironomid able to withstand almost complete desiccation in an ametabolic state known as anhydrobiosis.Both populations, Nigerian and Malawian, showed the same number of chromosomes (2n=8), but important differences were found in the band sequences of polytene chromosomes, and in the number and the arrangement of active regions between the two populations.Such important differences raise the possibility that the Malawian population could constitute a distinct new species of anhydrobiotic chironomid.

View Article: PubMed Central - PubMed

Affiliation: Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg 199034, Russia.

ABSTRACT
The African chironomid Polypedilumvanderplanki Hinton, 1951 is the only chironomid able to withstand almost complete desiccation in an ametabolic state known as anhydrobiosis. The karyotypes of two allopatric populations of this anhydrobiotic chironomid, one from Nigeria and another from Malawi, were described according to the polytene giant chromosomes. The karyotype from the Nigerian population was presented as the reference chromosome map for Polypedilumvanderplanki. Both populations, Nigerian and Malawian, showed the same number of chromosomes (2n=8), but important differences were found in the band sequences of polytene chromosomes, and in the number and the arrangement of active regions between the two populations. Such important differences raise the possibility that the Malawian population could constitute a distinct new species of anhydrobiotic chironomid.

No MeSH data available.


Related in: MedlinePlus

Representative karyotype of the population from Malawi. Chromosome numbers are indicated as I, II, III and IV. Chromosome arms are labeled A–B, C–D, E–F, and G. The expected locations of the centromeres are indicated by arrows and each section is numbered and delimited by short lines. N: nucleolus. BR1, BR2, BR3, BR4: Balbiani rings, P: puff.
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Figure 4: Representative karyotype of the population from Malawi. Chromosome numbers are indicated as I, II, III and IV. Chromosome arms are labeled A–B, C–D, E–F, and G. The expected locations of the centromeres are indicated by arrows and each section is numbered and delimited by short lines. N: nucleolus. BR1, BR2, BR3, BR4: Balbiani rings, P: puff.

Mentions: As a whole, the morphology of the salivary glands was similar to those from the Nigerian population. They also contained 16–20 cells. However, the distinction between populations of cells with different sizes was not so obvious. The diploid chromosome number was also 2n=8 (Fig. 4). The combination of chromosomal arms was AB, CD, EF and G. Chromosomes were denominated from their respective lengths: I=II>III>IV. Chromosomes I and II were metacentrics, chromosome III submetacentric, and chromosome IV telocentric. Putative centromeres appeared as distinct dark heterochromatic blocks. The karyotype was mononucleolar: one obligatory nucleolus (N) was well developed in sec. 3, near the centromere and the telomere in arm G. Apart from the nucleolus N, four Balbiani rings (BR) were localized in chromosome IV. BR1 was close to N in sec. 4, and the three other BR followed one after another: BR2 in sec. 7, BR3 in sec. 8, BR4 in sec.9.


Karyotypical characteristics of two allopatric African populations of anhydrobiotic Polypedilum Kieffer, 1912 (Diptera, Chironomidae) originating from Nigeria and Malawi.

Petrova NA, Cornette R, Shimura S, Gusev OA, Pemba D, Kikawada T, Zhirov SV, Okuda T - Comp Cytogenet (2015)

Representative karyotype of the population from Malawi. Chromosome numbers are indicated as I, II, III and IV. Chromosome arms are labeled A–B, C–D, E–F, and G. The expected locations of the centromeres are indicated by arrows and each section is numbered and delimited by short lines. N: nucleolus. BR1, BR2, BR3, BR4: Balbiani rings, P: puff.
© Copyright Policy - creative-commons-attribution
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4488965&req=5

Figure 4: Representative karyotype of the population from Malawi. Chromosome numbers are indicated as I, II, III and IV. Chromosome arms are labeled A–B, C–D, E–F, and G. The expected locations of the centromeres are indicated by arrows and each section is numbered and delimited by short lines. N: nucleolus. BR1, BR2, BR3, BR4: Balbiani rings, P: puff.
Mentions: As a whole, the morphology of the salivary glands was similar to those from the Nigerian population. They also contained 16–20 cells. However, the distinction between populations of cells with different sizes was not so obvious. The diploid chromosome number was also 2n=8 (Fig. 4). The combination of chromosomal arms was AB, CD, EF and G. Chromosomes were denominated from their respective lengths: I=II>III>IV. Chromosomes I and II were metacentrics, chromosome III submetacentric, and chromosome IV telocentric. Putative centromeres appeared as distinct dark heterochromatic blocks. The karyotype was mononucleolar: one obligatory nucleolus (N) was well developed in sec. 3, near the centromere and the telomere in arm G. Apart from the nucleolus N, four Balbiani rings (BR) were localized in chromosome IV. BR1 was close to N in sec. 4, and the three other BR followed one after another: BR2 in sec. 7, BR3 in sec. 8, BR4 in sec.9.

Bottom Line: The African chironomid Polypedilumvanderplanki Hinton, 1951 is the only chironomid able to withstand almost complete desiccation in an ametabolic state known as anhydrobiosis.Both populations, Nigerian and Malawian, showed the same number of chromosomes (2n=8), but important differences were found in the band sequences of polytene chromosomes, and in the number and the arrangement of active regions between the two populations.Such important differences raise the possibility that the Malawian population could constitute a distinct new species of anhydrobiotic chironomid.

View Article: PubMed Central - PubMed

Affiliation: Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg 199034, Russia.

ABSTRACT
The African chironomid Polypedilumvanderplanki Hinton, 1951 is the only chironomid able to withstand almost complete desiccation in an ametabolic state known as anhydrobiosis. The karyotypes of two allopatric populations of this anhydrobiotic chironomid, one from Nigeria and another from Malawi, were described according to the polytene giant chromosomes. The karyotype from the Nigerian population was presented as the reference chromosome map for Polypedilumvanderplanki. Both populations, Nigerian and Malawian, showed the same number of chromosomes (2n=8), but important differences were found in the band sequences of polytene chromosomes, and in the number and the arrangement of active regions between the two populations. Such important differences raise the possibility that the Malawian population could constitute a distinct new species of anhydrobiotic chironomid.

No MeSH data available.


Related in: MedlinePlus