Restriction of PGK‐B to spermatogenic cells: Evidence from experimentally cryptorchid mice

Abstract

The hypothesis that PGK-B, like LDH-C4, is restricted to spermatogenic cells was explored by examining isozyme patterns in testes from mice depleted of germinal cells by surgical cryptorchism. In experimentally cryptorchized C57BL/10Sn males, decline in PGK-B activity paralleled decline in LDH-C4 activity and was correlated with degeneration of spermatocytes, spermatids, and spermatozoa. Trace amounts of these sperm isozymes found in cryptorchid testes after the depletion of maturing germ cells probably came from degenerated spermatids and spermatocytes and not from somatic testicular cells.

Spermatogenesis and sperm-specific phosphoglycerate kinase B and lactate dehydrogenase C4 isoenzymes in sex-reversed mice

“…The absence of PGK-B from most Sxr/+,XX testes also supports our hypothesis that the residual sperm isoenzyme activity observed in some cryptorchid testes depleted of germ cells (Rudolph & VandeBerg, 1980) probably arose from degenerated spermatids and spermatozoa retained in the seminiferous tubules, and not from somatic elements in those testes. The one Sxr/+,XX testis that contained PGK-B may have contained tubules with more advanced spermatogenic cells than its contralateral testis, which appeared to lack meiotic cells when examined histologically.…”

“…However, testes from mature Sxr/+,XX mice and from the 5xr/+,XO mouse exhibited slightly increased activity of isoenzymes containing A subunits. A similar alteration was noted in testes from cryptorchid mice (Hawtrey & Goldberg, 1968;Rudolph & VandeBerg, 1980) and can be seen in published zymograms of testes from sex-reversed mice and mice that are heterozygous for male-sterile translocations (Holmes, Andrews & Jones, 1979). Translocation hétérozygotes whose testes lack spermatids, spermatozoa and LDH-C4 have increased activities of isoenzymes containing LDH-A subunits, whereas those whose testes contain spermatids have the normal LDH isoenzyme proportions.…”

“…Because of insufficient sample volume, 5 of the Sxr/+,XX mice were not assayed for LDH isoenzymes. The activities of PGK-B and LDH-C4 were estimated by serial dilution electrophoresis (Rudolph & VandeBerg, 1980); a testis extract from each Sxr mouse was co-electrophoresed with a 6-step 2-fold serial dilution of a testis extract from a B6CBA mouse, and the staining intensities were compared visually.…”

“…Gels were sandwiched between cooling plates and run at 30 V/cm for 3 h, then stained as described previously (Rudolph & VandeBerg, 1980) and examined under long-wave ultraviolet light. LDH isoenzymes were separated by electrophoresis on Cellogel in barbitone sodium (8-24 g/1) at 16 V/cm, 4°C, and stained as described by Meera Khan (1971).…”

“…It is encoded by an autosomal locus, which in mice is designated Pgk-2 and is closely linked to the major histocompatibility complex (Eicher, Cherry & Flaherty, 1978;VandeBerg & Klein, 1978). Several lines of evidence indicate that PGK-B activity may be localized to spermatogenic testicular cells: (1) PGK-B is the prédominent or only PGK isoenzyme in human, bull, ram, and mouse spermatozoa (VandeBerg et al, 1973;N. S. Rudolph & J. L. VandeBerg, unpublished); (2) the initial electrophoretic detection of PGK-B in pubescent mice is correlated with the appearance of spermatids in testes and of spermatozoa in epididymides (VandeBerg et al, 1976); and (3) testicular PGK-B activity is lost as spermatocytes, spermatids, and spermatozoa degenerate in experimentally cryptorchid mice (Rudolph & VandeBerg, 1980). In this study we have determined the PGK phenotypes of testes from sex-reversed (Sxr) mice.…”