Protamine-like sperm nuclear basic proteins in the primitive frogAscaphus trueiand histone reversions among more advanced frogs

Kasinsky, Harold E.; Gutovich, L.; Kulak, David; Mackay, Melanie; Green, D.M.; Hunt, J.; Ausió, Juan

doi:10.1002/(sici)1097-010x(19991201)284:7<717::aid-jez1>3.0.co;2-s

Cited by 11 publications

(1 citation statement)

References 43 publications

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“…These highly basic proteins have been described as an evolutionary precursor to protamines and are highly heterogeneous, but typically have a high combined arginine-lysine content of at least 35 -50%, albeit not as high as in protamines (Kasinsky et al 1999;Lewis and Ausio et al 2002;Ausio et al 2007). Since protamine-like proteins usually coexist with histones in the mature amphibian spermatozoon, it is possible that protamine-like proteins may play a role in the maintenance of the condensed chromatin structure (Itoh et al 1997).…”

Section: Amphibian Sperm Nuclear Basic Proteins (Snbps)mentioning

confidence: 99%

Amphibian sperm DNA fragmentation

Pollock¹

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There are extremely limited studies that have investigated DNA fragmentation in amphibians and even less information exists pertaining to DNA fragmentation in the spermatozoa.A DNA fragmentation assay applied and validated for amphibian spermatozoa would not only provide the first evidence of this phenomenon in a new major taxon, but also prove a valuable tool for developing improvements in ART used in the captive propagation of threatened and endangered species. Consequently, the fundamental aim of this project was the development and validation of the sperm chromatin dispersion (SCD) test for amphibian spermatozoa with the purpose of investigating the dynamic behaviour of amphibian sperm DNA in response to cryopreservation.The SCD test was first applied to African clawed frog (Xenopus laevis) as an amphibian sperm model using a species-specific modified lysing solution for protein depletion. Sperm DNA fragmentation (SDF) was assessed immediately following activation of sperm motility (T0) and again after one hour and 24 hours of incubation in order to produce a range of spermatozoa with differing levels of DNA damage. The SCD procedure resulted in the production of three nuclear morphotypes; amphibian sperm morphotype 1 (ASM-1) and ASM-2 showed no evidence of DNA damage, whereas ASM-3 spermatozoa were highly fragmented with large halos of dispersed DNA fragments and a reduced nuclear core. Levels of SDF revealed by the SCD test were highly correlated with results produced using in situ nick hybridisation with DNA-specific molecular probes (ISNT) and the double comet assay (r = 0.9613). The alkaline step of the double-comet assay revealed the extensive presence of structural single-stranded DNA breaks (SSB) and provided grounds for the suggestion that alkali labile sites (ALS) are a constitutive feature of African clawed frog sperm chromatin.SDF is a dynamic process and has been shown to increase with incubation at room temperature as well as following cryopreservation. However, the mechanisms of DNA cryoinjury and the resulting effect on the potential reproductive output of ART remain open to interpretation.Consequently, dynamic changes to the basal level of DNA fragmentation were examined in fresh African clawed frog spermatozoa in comparison with the post-thaw integrity of cryopreserved (-80 °C) and frozen (-20 °C) sperm DNA. SDF was examined initially at T0 and over incubation of up to 60 minutes. The difference in SDF was only marginal for fresh, frozen (-20 °C) and cryopreserved (-80 °C) spermatozoa examined at the onset of the experiment immediately upon thawing, however, a significant increase (p = 0.004) in SDF, albeit of a low magnitude, was observed in activated ii cryopreserved (-80 °C) spermatozoa following incubation. Although African clawed frog spermatozoa appeared to be highly resistant to cryopreservation-induced DNA damage, cryopreserved-thawed spermatozoa yielded a significantly lower (p = 0.0065) fertilisation rate than fresh spermatozoa.In order to provide further insight into cryo...

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Section: Amphibian Sperm Nuclear Basic Proteins (Snbps)mentioning

confidence: 99%

Amphibian sperm DNA fragmentation

Pollock¹

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Histones are the major chromosomal protein components of the sperm of the nemerteans Cerebratulus californiensis and Cerebratulus lacteus

Wang

Ausió

2001

J. Exp. Zool.

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We have characterized for the first time the sperm nuclear basic proteins (SNBP) from two species of nemerteans: Cerebratulus californiensis and Cerebratulus lacteus. Gel electrophoretic and chromatographic (RP-HPLC) analysis of the nuclear sperm extracts indicate that histones are the major protein components which are present. The linker histones (histones of the H1 family) exhibit a rather unusual composition and some of them contain cysteine. Several histone H1 isoforms are present, one of which has a composition similar to that of other H1 histones found in the sperm chromatin of other groups of lower invertebrates.

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Spermiogenic nuclear protein transitions and chromatin condensation. Proposal for an ancestral model of nuclear spermiogenesis

et al. 2009

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We have chosen three species (Sparus aurata, Dicentrarchus labrax, and Monodonta turbinata) that represent different transition patterns in the composition and structure of spermiogenic nuclei. The transition patterns of these species are representative of spermiogenesis in a large number of animal species. We analyze: (a) nuclear protein exchange; (b) chromatin condensation pattern; and (c) histone acetylation during spermiogenic development. In the simplest spermiogenesis histones and nucleosomes remain in mature sperm. Chromatin of spermatids is organized into 20 nm granules, simultaneous with a nuclear volume reduction. The granules coalesce in the final stage of spermiogenesis. Granular chromatin is correlated with acetylation of histones H3 and H4, whereas final coalescence is associated with histone deacetylation. We also studied two other spermiogenesis where a basic protein substitutes histones. Each species has a very different substituting protein. One has a typical protamine of 34 amino acids; the other has a sperm nuclear basic proteins (SNBP) of 106 amino acids. In both, the structural transitions and histone acetylation pattern are similar: in early spermiogenesis chromatin is organized into 20 nm granules, and histones are significantly acetylated, while the nuclear volume decreases. Subsequently, acetylated histones are displaced by the protamine or SNBP. Histone substitution causes chromatin remodelling and additional reduction in nuclear volume. We analyze these three cases together with earlier works and propose that the formation of 20 nm granules containing acetylated H3 and H4 accomplishes the minimum functional requirement to be considered the most evolutionarily ancestral chromatin conformation preceding condensation in animal spermiogenesis.

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Protamine-like sperm nuclear basic proteins in the primitive frogAscaphus trueiand histone reversions among more advanced frogs

Cited by 11 publications

References 43 publications

Amphibian sperm DNA fragmentation

Amphibian sperm DNA fragmentation

Histones are the major chromosomal protein components of the sperm of the nemerteans Cerebratulus californiensis and Cerebratulus lacteus

Spermiogenic nuclear protein transitions and chromatin condensation. Proposal for an ancestral model of nuclear spermiogenesis

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