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, Gerharden_ZA
dc.contributor.authorMaree, Lianaen_ZA
dc.contributor.authorKotze, Saneten_ZA
dc.contributor.authorO'Riain, M Justinen_ZA
dc.date.accessioned2015-10-30T09:38:04Z
dc.date.available2015-10-30T09:38:04Z
dc.date.issued2011en_ZA
dc.description.abstractBACKGROUND: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.identifier.apacitationVan der Horst, G., Maree, L., Kotze, S., & O'Riain, 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?. <i>BMC Evolutionary Biology</i>, http://hdl.handle.net/11427/14550en_ZA
dc.identifier.chicagocitationVan der Horst, Gerhard, Liana Maree, Sanet Kotze, and M Justin O'Riain "Sperm structure and motility in the eusocial naked mole-rat, Heterocephalus glaber: a case of degenerative orthogenesis in the absence of sperm competition?." <i>BMC Evolutionary Biology</i> (2011) http://hdl.handle.net/11427/14550en_ZA
dc.identifier.citationVan Der Horst, G., Maree, L., Kotzé, S. H., & O'Riain, 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), 351.en_ZA
dc.identifier.ris TY - Journal Article AU - Van der Horst, Gerhard AU - Maree, Liana AU - Kotze, Sanet AU - O'Riain, M Justin AB - 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. DA - 2011 DB - OpenUCT DO - 10.1186/1471-2148-11-351 DP - University of Cape Town J1 - BMC Evolutionary Biology LK - https://open.uct.ac.za PB - University of Cape Town PY - 2011 T1 - Sperm structure and motility in the eusocial naked mole-rat, Heterocephalus glaber: a case of degenerative orthogenesis in the absence of sperm competition? TI - Sperm structure and motility in the eusocial naked mole-rat, Heterocephalus glaber: a case of degenerative orthogenesis in the absence of sperm competition? UR - http://hdl.handle.net/11427/14550 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/14550
dc.identifier.urihttp://dx.doi.org/10.1186/1471-2148-11-351
dc.identifier.vancouvercitationVan der Horst G, Maree L, Kotze S, O'Riain MJ. 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. 2011; http://hdl.handle.net/11427/14550.en_ZA
dc.language.isoengen_ZA
dc.publisherBioMed Central Ltden_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an Open Access article distributed under the terms of the Creative Commons Attribution Licenseen_ZA
dc.rights.holder2011 van der Horst et al; licensee BioMed Central Ltd.en_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/2.0en_ZA
dc.sourceBMC Evolutionary Biologyen_ZA
dc.source.urihttp://www.biomedcentral.com/bmcevolbiol/en_ZA
dc.subject.otherMole Ratsen_ZA
dc.subject.otherPair Bonden_ZA
dc.subject.otherSperm Motilityen_ZA
dc.subject.otherSpermatozoaen_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.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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