The Mfsd14a gene, previously called Hiat1, encodes a transmembrane protein of unknown function with homology to the solute carrier protein family. To study the function of the MFSD14A protein, mutant mice (Mus musculus, strain 129S6Sv/Ev) were generated with the Mfsd14a gene disrupted with a LacZ reporter gene. Homozygous mutant mice are viable and healthy, but males are sterile due to a 100-fold reduction in the number of spermatozoa in the vas deferens. Male mice have adequate levels of testosterone and show normal copulatory behaviour. The few spermatozoa that are formed show rounded head defects similar to those found in humans with globozoospermia. Spermatogenesis proceeds normally up to the round spermatid stage, but the subsequent structural changes associated with spermiogenesis are severely disrupted with failure of acrosome formation, sperm head condensation and mitochondrial localization to the mid-piece of the sperm. Staining for β-galactosidase activity as a surrogate for Mfsd14a expression indicates expression in Sertoli cells, suggesting that MFSD14A may transport a solute from the bloodstream that is required for spermiogenesis. Reproduction (2016) 152 91-99 IntroductionSpermatogenesis is the developmental process by which spermatozoa are produced from spermatogonial germ cells in the gonads (Grootegoed et al. 1995, Jan et al. 2012. At the start of this process, spermatogonial cells give rise to primary spermatocytes, which progress through meiosis to produce haploid spermatids. The spermatids subsequently undergo spermiogenesis, a complex series of morphological changes to form spermatozoa (Toshimori & Ito 2003). During spermiogenesis, chromatin condensation and nuclear remodelling occur, and also formation of the acrosome that contains glycosylated enzymes essential for egg fertilization. The acrosome is formed by the fusion of proacrosomal vesicles derived from the Golgi apparatus, which fuse to form a cap structure over the nucleus. A flagellum with the central 9 + 2 microtubular axoneme is also formed during spermiogenesis and contains a mid-piece packed with mitochondria to provide energy for motility.Defects in spermiogenesis contribute to male infertility problems in humans. Globozoospermia is one such syndrome that is found in around 0.1% of infertile men (Dam et al. 2007a). The disorder is characterized by round-headed sperm with a disrupted acrosome and abnormal mitochondrial localization. Genes that cause globozoospermia have been identified in mutant mice, www.reproduction-online.org transmembrane domains and a region similar to the facilitative glucose transporter specific P-E-S-P-R motif at the end of the 6th transmembrane domain. These characte ristics suggest that the Mfsd14a gene may encode a novel sugar transporter, but the solute specificity of the protein is not known.To establish the physiological function of the MFSD14A protein in vivo, we generated a transgenic mouse line with a LacZ gene insertion that disrupts the expression of the Mfsd14a gene. Phenotypic charac...

Mice with mutations in the kisspeptin signaling pathway (Kiss1 K/K or Gpr54) have low gonadotrophic hormone levels, small testes, and impaired spermatogenesis. Between 2 and 7 months of age, however, the testes of the mutant mice increase in weight and in Gpr54 K/K mice, the number of seminiferous tubules containing spermatids/spermatozoa increases from 17 to 78%. In contrast, the Kiss1 K/K mice have a less severe defect in spermatogenesis and larger testes than Gpr54 K/K mice at both 2 and 7 months of age. The reason for the improved spermatogenesis was investigated. Plasma testosterone and FSH levels did not increase with age in the mutant mice and remained much lower than in wild-type (WT) mice. In contrast, intratesticular testosterone levels were similar between mutant and WT mice. These data indicate that age-related spermatogenesis can be completed under conditions of low plasma testosterone and FSH and that intratesticular testosterone may contribute to this process. In addition, however, when the Gpr54 K/K mice were fed a phytoestrogen-free diet, they showed no age-related increase in testes weight or improved spermatogenesis. Thus, both genetic and environmental factors are involved in the improved spermatogenesis in the mutant mice as they age although the mice still remain infertile. These data show that the possible impact of dietary phytoestrogens should be taken into account when studying the phenotype of mutant mice with defects in the reproductive axis.

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Glucose-6-phosphate dehydrogenase (Zwischerfferment) and 6-phosphogluconate dehydrogenase, first studied in y e a s t by Warburg and his coworkers (1, 2), have since been found in a number of cells and tissues. These have received extensive study because they provide a pathway for formation of pentose phosphate from hexose phosphate and because of the possibility that oxidation of glucose-6-phosphate by this means may provide energy for function. (See references 3--6.)The present experiments deal with the occurrence, the properties, and the relation to over-all metabolism of these two enzymes in eggs of the sea urchin, Arbacia punctulata; they are part of a general survey of the enzymes of Arbacia eggs (7). Experimental MethodsThe eggs were obtained and handled as previously described (8, 9). Homogenates were prepared as before (9), except that citrate was omitted from, and 0.004 ~ ethylenediamine tetraacetic acid included in, the homogenizing medium to minimize breakdown of the echinochrome granules; the homogenates were a light orange-pink and the supernatant fractions obtained therefrom by centrifugation at 20,000 g for 30 minutes were clear and of a straw yellow color. The homogenates and other fractions to be tested were kept at ice water temperature; full activity was retained for 6 to 8 hours; 20 to 40 per cent of the initial activity of the homogenate or supematant fractions was lost by a single freezing and thawing; this procedure appeared relatively more damaging to the phosphogluconate dehydrogenase than to glucose-6-phosphate dehydrogenase. The values recorded in the tables and figures were calculated by use of the conversion factors previously derived (10).The sources of the special reagents were: Sigma Chemical Company, triphosphopyridine nucleotide (TPN), 83 per cent purity (assayed by yeast Zwischenferment), barium glucose-l-phosphate, and yeast Zwischenferment (lot No. 54-137, virtually free of phosphogluconate dehydrogenase);