Chromosome behaviour during male meioses has been studied in two bisexual amphimictic populations of two tardigrade species, namely Richtersius coronifer and Macrobiotus richtersi (Eutardigrada, Macrobiotidae). Both bisexual populations exhibit a diploid chromosome number 2n = 12 and no sex chromosomes were identified. DAPI staining and C-banding data indicate that all chromosomes of the bisexual population of R. coronifer are acrocentric. In both species, at male meiotic prophase, all six bivalent homologous chromosomes are aligned side by side along their length and show no evidence of chiasmata. However, in the oocytes of both species a chiasma is generally present in each bivalent at diplotene stage. Lack of recombination is previously unknown in tardigrades, but is a well known phenomenon in many other metazoans where it is always restricted to the heterogametic sex. In tardigrades there is no evidence of heterochromosomes, but it does not mean that in tardigrades, the heterogametic sex does not exist. The adaptive and evolutionary significance of achiasmatic meiosis is discussed.

First evidence of achiasmatic male meiosis in the water bears Richtersius coronifer and Macrobiotus richtersi (Eutardigrada, Macrobiotidae) / Altiero, Tiziana; Rebecchi, Lorena. - In: HEREDITAS. - ISSN 0018-0661. - STAMPA. - 139:2(2003), pp. 116-120. [10.1111/j.1601-5223.2003.01719.x]

First evidence of achiasmatic male meiosis in the water bears Richtersius coronifer and Macrobiotus richtersi (Eutardigrada, Macrobiotidae)

ALTIERO, Tiziana;REBECCHI, Lorena
2003

Abstract

Chromosome behaviour during male meioses has been studied in two bisexual amphimictic populations of two tardigrade species, namely Richtersius coronifer and Macrobiotus richtersi (Eutardigrada, Macrobiotidae). Both bisexual populations exhibit a diploid chromosome number 2n = 12 and no sex chromosomes were identified. DAPI staining and C-banding data indicate that all chromosomes of the bisexual population of R. coronifer are acrocentric. In both species, at male meiotic prophase, all six bivalent homologous chromosomes are aligned side by side along their length and show no evidence of chiasmata. However, in the oocytes of both species a chiasma is generally present in each bivalent at diplotene stage. Lack of recombination is previously unknown in tardigrades, but is a well known phenomenon in many other metazoans where it is always restricted to the heterogametic sex. In tardigrades there is no evidence of heterochromosomes, but it does not mean that in tardigrades, the heterogametic sex does not exist. The adaptive and evolutionary significance of achiasmatic meiosis is discussed.
2003
139
2
116
120
First evidence of achiasmatic male meiosis in the water bears Richtersius coronifer and Macrobiotus richtersi (Eutardigrada, Macrobiotidae) / Altiero, Tiziana; Rebecchi, Lorena. - In: HEREDITAS. - ISSN 0018-0661. - STAMPA. - 139:2(2003), pp. 116-120. [10.1111/j.1601-5223.2003.01719.x]
Altiero, Tiziana; Rebecchi, Lorena
File in questo prodotto:
File Dimensione Formato  
j.1601-5223.2003.01719.x.pdf

Open access

Tipologia: Versione pubblicata dall'editore
Dimensione 86.44 kB
Formato Adobe PDF
86.44 kB Adobe PDF Visualizza/Apri
Pubblicazioni consigliate

Licenza Creative Commons
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/305248
Citazioni
  • ???jsp.display-item.citation.pmc??? 1
  • Scopus 9
  • ???jsp.display-item.citation.isi??? 8
social impact