Sperm quality assessments for endangered razorback suckers Xyrauchen texanus.
Flow cytometry (FCM) and computer-assisted sperm motion analysis (CASA) methods were developed and validated for use with endangered razorback suckers Xyrauchen texanus collected (n=64) during the 2006 spawning season. Sperm motility could be activated within osmolality ranges noted during milt collections (here 167-343 mOsm/kg). We hypothesized that sperm quality of milt collected into isoosmotic (302 mOsm/kg) or hyperosmotic (500 mOsm/kg) Hanks' balanced salt solution would not differ. Pre-freeze viabilities were similar between osmolalities (79%±6 (s.e.m.) and 76%±7); however, post-thaw values were greater in hyperosmotic buffer (27%±3 and 12%±2; P=0.0065), as was mitochondrial membrane potential (33%±4 and 13%±2; P=0.0048). Visual estimates of pre-freeze motility correlated with total (r=0.7589; range 23-82%) and progressive motility (r=0.7449) by CASA and were associated with greater viability (r=0.5985; P<0.0001). Count (FCM) was negatively correlated with post-thaw viability (r=-0.83; P=0.0116) and mitochondrial function (r=-0.91; P=0.0016). By FCM-based assessments of DNA integrity, whereby increased fluorochrome binding indicated more fragmentation, higher levels were negatively correlated with count (r=-0.77; P<0.0001) and pre-freeze viabilities (r=-0.66; P=0.0004). Fragmentation was higher in isotonic buffer (P=0.0234). To increase reproductive capacity of natural populations, the strategy and protocols developed can serve as a template for use with other imperiled fish species, biomonitoring, and genome banking.
US Geological Survey, National Wetlands Research Center, 700 Cajundome Boulevard, Lafayette, LA 70506, USA. jenkinsj@usgs.gov
Jill A
JA
Jenkins
Bruce E
BE
Eilts
Amy M
AM
Guitreau
Chester R
CR
Figiel
Rassa O
RO
Draugelis-Dale
Terrence R
TR
Tiersch
D000818:Animals; D048430:Cell Shape; D002470:Cell Survival; D015925:Cryopreservation / Q000662:veterinary*; D003531:Cypriniformes; D053938:DNA Fragmentation; D056727:Endangered Species; D005434:Flow Cytometry; D008297:Male; D053078:Membrane Potential, Mitochondrial; D027724:Reproductive Techniques, Assisted / Q000662:veterinary*; D012621:Seasons; D013076:Sperm Count; D013081:Sperm Motility; D013094:Spermatozoa / Q000473:pathology*