The Platyfish, Xiphophorus maculatus

Kallman, Klaus D.

doi:10.1007/978-1-4613-4470-4_6

Cited by 163 publications

(117 citation statements)

References 44 publications

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“…The genus Xiphophorus is characterized by internal fertilization, in which males produce sperm in packages (spermatophores) and females store sperm in the receptaculum seminis or "Delle" of the genital tract for as long as several months after insemination [21,26,46,47]. Inside the sperm package or within the female genital tract, the sperm seem to not move freely.…”

Section: Discussionmentioning

confidence: 99%

“…Development of sperm cryopreservation protocols for Xiphophorus is also complicated by their small body sizes [26,27] and limited sperm volume [28,29]. Work with live-bearers is further hampered because specialized devices and technical skill are required to inseminate females, and embryonic development in the female is not easily monitored [30].…”

Section: Introductionmentioning

confidence: 99%

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Initial studies on sperm cryopreservation of a live-bearing fish, the green swordtail Xiphophorus helleri

et al. 2004

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Swordtails and platyfish of the genus Xiphophorus are valuable models for biomedical research and are also commercially raised as ornamental fish valued by aquarists. While research use and commercial interest increases yearly in these fish, cryopreservation of sperm is unexplored in this genus. Xiphophorus are live-bearing fishes characterized by small body sizes, limited sperm volumes, and internal fertilization, an atypical reproductive mode for fish. These attributes make research involving cryopreservation of Xiphophorus germplasm challenging. To explore methods for sperm cryopreservation, this study evaluated the effect of different loading volumes of sperm suspension in 0.25-ml French straws, different dilution ratios of sperm to extender, an osmolality range of extender without cryoprotectant and with dimethyl sulfoxide (DMSO) as cryoprotectant, and short-term storage at room temperature and 4 °C after thawing. No significant difference in sperm motility due to straw loading volume was observed after thawing. Sperm motility was observed to decrease with increasing dilution. The osmolality of Hanks' balanced salt solution (HBSS) without cryoprotectant in which the highest sperm motility (67%) was observed was 320 ± 3 mOsm/kg, which was also the osmolality of X. helleri blood plasma. When cryopreserved with 10% DMSO, however, the highest motilities within 10 min after thawing were observed with HBSS in the range of 240-300 mOsm/kg. Sperm suspended in HBSS at 320 mOsm/kg with a dilution factor of 100 maintained motility for 24 h at room temperature, but persisted for 10 days when stored at 4 °C. These results provided the first evidence that cryopreservation may be applied to conservation of genetic resources in live-bearing fishes.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Initial studies on sperm cryopreservation of a live-bearing fish, the green swordtail Xiphophorus helleri

et al. 2004

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“…Published studies of sperm cryopreservation of small livebearing fish are completely lacking except for our initial research on swordtail sperm [12]. Live-bearing fishes as a group are distinct from other fishes for many reasons, most notably for internal fertilization in which males transfer sperm in packages (spermatophores) to females which store the sperm in the receptaculum seminis or "Delle" of the genital tract for as long as several months after insemination [14,22,24,32]. …”

mentioning

confidence: 99%

Sperm cryopreservation of green swordtail Xiphophorus helleri, a fish with internal fertilization

et al. 2004

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Sperm cryopreservation for fishes with internal fertilization is essentially unexplored although many species of these fishes are valuable biomedical research models. To explore methods for sperm cryopreservation within the live-bearing genus Xiphophorus, this study used X. helleri to evaluate the effects of cryoprotectant, osmotic pressure, cooling rate, equilibration time, and sperm-to-extender ratio. Sperm motility and survival duration after thawing showed significant differences among different cryoprotectants with the highest motility at 10 min after thawing obtained with 14% glycerol. With subsequent use of 14% glycerol as the cryoprotectant, the highest motility after thawing was observed with Hanks' balanced salt solution (HBSS) at 300 mOsmol/kg. Samples cooled from 5 to −80 °C at 20 °C/min yielded the highest post-thaw motility although no significant difference was found in the first 4 h after thawing for cooling rates across the range of 20-35 °C/min. Evaluation of equilibration time revealed no significant difference between 20 min and 2 h, but the highest motility at 10 min after thawing was found with a 20-min equilibration. Dilution ratios of sperm-to-extender at 1:20, 1:60, and 1:120 showed no significant differences in motility and survival duration after thawing, but the dilution of sperm solutions with HBSS (320 mOsmol/kg) immediately after thawing reduced the decline of sperm motility, and significantly prolonged the survival duration. Based on these findings, the highest average sperm motility (77%) at 10 min after thawing was obtained when sperm were suspended in HBSS at 300 mOsmol/kg with 14% glycerol as cryoprotectant, diluted at a ratio of sperm to HBSS-glycerol of 1:20, equilibrated for 10 min, cooled at 20 °C/min from 5 to −80 °C before being plunged in liquid nitrogen, and thawed in a 40 °C water bath for 7 s. If diluted immediately after thawing, sperm frozen by the protocol above retained continuous motility after thawing for more than 8 days when stored at 4 °C. The first studies of fish sperm cryopreservation were published 50 years ago [5], and since then more than 200 fish species have been studied [26,39]. This research effort has yielded techniques that are being applied with varying levels of success for fishes around the world. However, most work has focused on large-bodied culture and sport fishes, such as salmon and trout of the family salmonidae [29], carps of the family cyprinidae [11], and catfishes of the families claridae, ictaluridae, pangasiidae, and siluridae [35]. Small teleost fishes are studied much less except for the research models zebrafish (Danio rerio) and Japanese medaka (Oryzias latipes) [1]. Published studies of sperm cryopreservation of small livebearing fish are completely lacking except for our initial research on swordtail sperm [12]. Live-bearing fishes as a group are distinct from other fishes for many reasons, most notably for internal fertilization in which males transfer sperm in packages (spermatophores) to females which store the sp...

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“…Animals: All fish were raised and maintained under standard conditions (Kallman 1975) in the aquarium of the Biocenter at the University of Würzburg. Fish from the following strains were used: Black Amazon I (WLC 533): Animals of this clonal line exhibit a black spotted pigmentation phenotype because of the presence of a microchromosome derived from a black molly (see description below).…”

Section: Methodsmentioning

confidence: 99%

Stable Inheritance of Host Species-Derived Microchromosomes in the Gynogenetic Fish Poecilia formosa

et al. 2007

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B chromosomes are additional, usually unstable constituents of the genome of many organisms. Their origin, however, is often unclear and their evolutionary relevance is not well understood. They may range from being deleterious to neutral or even beneficial. We have followed the genetic fate of B chromosomes in the asexual, all-female fish Poecilia formosa over eight generations. In this species, B chromosomes come in the form of one to three tiny microchromosomes derived from males of the host species that serve as sperm donors for this gynogenetic species. All microchromosomes have centromeric heterochromatin but usually only one has a telomere. Such microchromosomes are stably inherited, while the telomereless are prone to be lost in both the soma and germline. In some cases the stable microchromosome carries a functional gene lending support to the hypothesis that the B chromosomes in P. formosa could increase the genetic diversity of the clonal lineage in this ameiotic organism and to some degree counteract the genomic decay that is supposed to be connected with the lack of recombination.

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The Platyfish, Xiphophorus maculatus

Cited by 163 publications

References 44 publications

Initial studies on sperm cryopreservation of a live-bearing fish, the green swordtail Xiphophorus helleri

Initial studies on sperm cryopreservation of a live-bearing fish, the green swordtail Xiphophorus helleri

Sperm cryopreservation of green swordtail Xiphophorus helleri, a fish with internal fertilization

Stable Inheritance of Host Species-Derived Microchromosomes in the Gynogenetic Fish Poecilia formosa

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