Sperm structure and motility in the eusocial naked mole-rat, Heterocephalus glaber : a case of degenerative orthogenesis in the absence of sperm competition?

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dc.contributor.authorVan Der Horst, Gerhard
dc.contributor.authorMaree, Liana
dc.contributor.authorKotze, Sanet H.
dc.contributor.authorO Riain, M. Justin
dc.date.accessioned2012-01-24T13:32:06Z
dc.date.available2012-01-24T13:32:06Z
dc.date.issued2011-12
dc.date.updated2011-12-28T20:05:33Z
dc.descriptionThe original publication is available at http://www.biomedcentral.com/1471-2148/11/351en_ZA
dc.description.abstractABSTRACT: Background We have studied sperm structure and motility in a eusocial rodent where reproduction is typically restricted to a single male and behaviourally dominant queen. Males rarely compete for access to the queen during her estrus cycle, suggesting little or no role for sperm competition. Results Our results revealed an atypical mammalian sperm structure with spermatozoa from breeding, subordinate and disperser males being degenerate and almost completely lacking a "mammalian phylogenetic stamp". Sperm structure is characterized by extreme polymorphism with most spermatozoa classified as abnormal. Sperm head shapes include round, oval, elongated, lobed, asymmetrical and amorphous. At the ultrastructural level, the sperm head contains condensed to granular chromatin with large open spaces between the chromatin. Nuclear chromatin seems disorganized since chromatin condensation is irregular and extremely inconsistent. The acrosome forms a cap (ca 35%) over the anterior part of the head. A well defined nuclear fossa and neck with five minor sets of banded protein structures are present. The midpiece is poorly organized and contains only 5 to 7 round to oval mitochondria. The flagellar pattern is 9+9+2. A distinct degenerative feature of the tail principal piece is the absence of the fibrous sheath. Only 7% motile spermatozoa were observed which had exceptionally slow swimming speeds. Conclusion In this species, sperm form has simplified and degenerated in many aspects and represents a specialised form of degenerative orthogenesis at the cellular level.en_ZA
dc.description.versionPeer Revieweden_ZA
dc.format.extent11 p. : ill.
dc.identifier.citationVan Der Horst, G., Maree, L., Kotze, S. H. & O'rian, M. J. 2011. Sperm structure and motility in the eusocial naked mole-rat, Heterocephalus glaber: a case of degenerative orthogenesis in the absence of sperm competition?, BMC Evolutionary Biology. 11(1):351en_ZA
dc.identifier.issn1471-2148
dc.identifier.urihttp://dx.doi.org/10.1186/1471-2148-11-351
dc.identifier.urihttp://hdl.handle.net/10019.1/19376
dc.language.isoen_ZAen_ZA
dc.language.rfc3066en
dc.publisherBioMed Centralen_ZA
dc.rights.holdervan der Horst et al.; licensee BioMed Central Ltd.en_ZA
dc.subjectSperm structureen_ZA
dc.subjectHeterocephalus glaberen_ZA
dc.subjectDegenerative orthogenesisen_ZA
dc.subjectRodentsen_ZA
dc.subjectHeterocephalus glaberen_ZA
dc.subjectNaked mole rat -- Semen analysisen_ZA
dc.subjectSperm -- Motilityen_ZA
dc.subject.lcshNaked mole rat -- Reproductionen_ZA
dc.subject.lcshNaked mole rat -- Spermatozoa -- Motilty -- Researchen_ZA
dc.titleSperm structure and motility in the eusocial naked mole-rat, Heterocephalus glaber : a case of degenerative orthogenesis in the absence of sperm competition?en_ZA
dc.typeArticleen_ZA
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