Changes in polyadenylation of lactate dehydrogenase-X mRNA during spermatogenesis in mice

The expression of the mRNA for mouse testicular lactate dehydrogenase (LDH-X) was examined by RNA:cDNA hybridization in situ in the testis and by Northern analyses of meiotic and postmeiotic spermatogenic cell populations. Silver grains accumulated in cells inside the second layer from the periphery of the seminiferous tubule, confirming previous findings that LDH-X mRNA first appears in the spermatocyte and continues to accumulate until the late spermatid stage. Northern analyses showed that meiotic and postmeiotic cells contained 1.2 and 1.3 kb classes of hybridizing mRNA, respectively. RNase H digestion of oligo (dT)-hybridized RNA and poly(U)-Sepharose column chromatography with differential elution by formamide revealed that the difference in size of the two classes of mRNAs was due to the poly(A) tail length of the LDH-X mRNA. When the distribution of the LDH-X mRNA was examined across polysome gradients, both mRNAs were partially associated with polysomes. These results suggest that the changes in the polyadenylation of LDH-X mRNA were associated with the meiotic division during spermatogenesis in the mouse. They raise the possibility that the stable accumulation of the LDH-X mRNAs in the postmeiotic cells is enhanced by poly(A) tails of increased length.