Idiopathic Male Infertility Is Strongly Associated with Aberrant Promoter Methylation of Methylenetetrahydrofolate Reductase (MTHFR)

Abnormal germline DNA methylation in males has been proposed as a possible mechanism compromising spermatogenesis of some men currently diagnosed with idiopathic infertility. Previous studies have been focused on imprinted genes with DNA methylation in poor quality human sperms. However, recent but limited data have revealed that sperm methylation abnormalities may involve large numbers of genes or shown that genes that are not imprinted are also affected.Using the methylation-specific polymerase chain reaction and bisulfite sequencing method, we examined methylation patterns of the promoter of methylenetetrahydrofolate reductase (MTHFR) gene (NG_013351: 1538-1719) in sperm DNA obtained from 94 idiopathic infertile men and 54 normal fertile controls. Subjects with idiopathic infertility were further divided into groups of normozoospermia and oligozoospermia. Overall, 45% (41/94) of idiopathic infertile males had MTHFR hypermethylation (both hemimethylation and full methylation), compared with 15% of fertile controls (P<0.05). Subjects with higher methylation level of MTHFR were more likely to have idiopathic male infertility (P-value for trend  = 0.0007). Comparing the two groups of idiopathic infertile subjects with different sperm concentrations, a higher methylation pattern was found in the group with oligozoospermia.Hypermethylation of the promoter of MTHFR gene in sperms is associated with idiopathic male infertility. The functional relevance of hypermathylation of MTHFR to male fertility warrants further investigation

The influence of environmental temperature and photoperiod on activity in the red squirrel, Tamiasciurus hudsonicus

The effects of environmental temperature and photoperiod on wheelrunning activity were studied in the diurnal red squirrel, Tamiasciurus hudsonicus. From 1 July to 22 November 1973 eight squirrels were maintained in separate cages in an outdoor shelter. Activity usually began before sunrise in the summer an early fall and after sunrise in the late fall. Wheel-running usually persisted throughout the day and ceased about the time of sunset in the summer and early fall. In late fall cessation frequently occurred after sunset. Neither changes in temperature nor photoperiod were found to separately account for the seasonal changes. Multiparameter analysis of variance was found to be a powerful statistical tool for analyzing the data. Six models for predicting the onset of activity were constructed and tested