Two-step cluster procedure after principal component analysis identifies sperm subpopulations in canine ejaculates and its relation to cryoresistance.

A 2-step clustering procedure, using indexes derived from principal component analysis, was used to disclose sperm subpopulations within the canine ejaculate and its relationship to sperm cryoresistance. Semen from 4 dogs was frozen-thawed by a standard protocol: before freezing, computer-assisted sperm analysis of motility and morphometry were performed; after thawing, motility analysis was performed again; and cryoresistance was estimated as the percent changes in progressive motility and sperm velocities after thawing. We used indexes derived from principal component analysis (sperm velocity index [SVI] and sperm motility index [SMI]) and the SPSS 2-step cluster method to disclose sperm subpopulations. The 2-step clustering procedure revealed the existence of 6 subpopulations. Subpopulations 4 and 6 were characterized by high values of both SVI (>200 arbitrary units) and SMI (>90 arbitrary units), subpopulations 2 and 3 were characterized by medium values (SVI 100 to 130; and SMI 30 to 40), and subpopulations 1 and 5 were characterized by low values (SVI < 100; SMI < 30). The distribution of sperm subpopulations was completely different among dogs. Four sperm subpopulations based in morphometric parameters of the sperm head and midpiece were revealed. Models including SVI and SMI indexes explained curvilinear velocity (R(2) = 0.997; P < .001), straight-line velocity (R(2) = 0.98; P < .001), and average velocity (R(2) = 0.99; P < .0001) postthaw.

[1]  W. Holt,et al.  Objectively measured boar sperm motility parameters correlate with the outcomes of on-farm inseminations: results of two fertility trials. , 1997, Journal of andrology.

[2]  P. Mazur,et al.  Is Intracellular Ice Formation the Cause of Death of Mouse Sperm Frozen at High Cooling Rates?1 , 2002, Biology of reproduction.

[3]  P. Mazur.  Freezing of living cells: mechanisms and implications. , 1984, The American journal of physiology.

[4]  K. V. Van Look,et al.  Concepts in sperm heterogeneity, sperm selection and sperm competition as biological foundations for laboratory tests of semen quality. , 2004, Reproduction.

[5]  A. I. P. Martínez,et al.  Canine fresh and cryopreserved semen evaluation. , 2004, Animal reproduction science.

[6]  A. Peña,et al.  Effects of spermatozoal concentration and post-thaw dilution rate on survival after thawing of dog spermatozoa. , 2000, Theriogenology.

[7]  C. Soler,et al.  Morphometric characterization and classification of alpaca sperm heads using the sperm-class analyzer computer-assisted system. , 2002, Theriogenology.

[8]  E. Nieschlag,et al.  Diagnostic accuracy of computer-assisted sperm motion analysis. , 1998, Human reproduction.

[9]  Guidelines on the application of CASA technology in the analysis of spermatozoa. ESHRE Andrology Special Interest Group. European Society for Human Reproduction and Embryology. , 1998, Human reproduction.

[10]  B. Gadella,et al.  Evaluation of In Vitro Capacitation of Stallion Spermatozoa1 , 2001, Biology of reproduction.

[11]  H. Rodríguez-Martínez.  Laboratory semen assessment and prediction of fertility: still utopia? , 2003, Reproduction in domestic animals = Zuchthygiene.

[12]  S T Mortimer,et al.  CASA--practical aspects. , 2000, Journal of andrology.

[13]  H. Rodríguez-Martínez,et al.  Identification of sperm morphometric subpopulations in two different portions of the boar ejaculate and its relation to postthaw quality. , 2005, Journal of andrology.

[14]  J. Rodríguez-Gil,et al.  Identification of sperm subpopulations with specific motility characteristics in stallion ejaculates. , 2003, Theriogenology.

[15]  Ashok Agarwal,et al.  New semen quality scores developed by principal component analysis of semen characteristics. , 2003, Journal of andrology.

[16]  M. Iguer-ouada,et al.  Computer assisted semen analyzers in andrology research and veterinary practice. , 2002, Theriogenology.

[17]  J P Bonde,et al.  Computer-assisted semen analysis parameters as predictors for fertility of men from the general population. The Danish First Pregnancy Planner Study Team. , 2000, Human reproduction.

[18]  P. de Paz,et al.  Sperm Subpopulations in Iberian Red Deer Epididymal Sperm and Their Changes Through the Cryopreservation Process1 , 2005, Biology of reproduction.

[19]  W. Holt.  CAN WE PREDICT FERTILITY RATES? MAKING SENSE OF SPERM MOTILITY , 1995 .

[20]  W. Holt,et al.  Sperm subpopulations in boar (Sus scrofa) and gazelle (Gazella dama mhorr) semen as revealed by pattern analysis of computer-assisted motility assessments. , 1999, Biology of reproduction.

[21]  M. Bajpai,et al.  Involvement of tyrosine kinase and cAMP-dependent kinase cross-talk in the regulation of human sperm motility. , 2003, Reproduction.