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C. E. Ford and E. P. Evans

Summary. Testicular preparations were obtained from 7 bulls, twins of freemartins, and 1 male marmoset, all proved XX/XY chimaeras. X and Y sex chromosomes were confidently identified in nearly all the 87 spermatogonia at mitotic metaphase and 1052 primary spermatocytes at diakinesis–metaphase examined: no cell was identified as containing two X chromosomes. The germ cell chimaerism previously reported in these species is therefore not confirmed. Cultures grown from presumptive somatic cells in the testes of two of the bulls yielded 248 identifiable mitotic spreads, all XY-type; cultures from the gonads of their freemartin twins yielded 442 mitotic spreads, all XX-type. Direct preparations from one freemartin gonad, however, yielded 3 XY mitotic spreads out of 18 examined. The conflicting evidence concerning germ cell chimaerism in cattle and marmosets is discussed, particularly in relation to reports of XX/XY bulls that have sired a great excess of daughters. The possibility that XX germ cells contributed to the functional spermatozoa of these bulls is not favoured by present information, but is not excluded.

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P. S. Burgoyne, P. P. L. Tam, and E. P. Evans

Summary. The growth and development of XO and XX mice were compared from 7¼ to 18½ days of gestation. The 7¼-day XO egg cylinders were retarded in development (and consequently small) when compared with XX egg cylinders, and this lag in development remained until 10½ days. By 12¼ days there was a considerable degree of 'catch-up', but this was not fully maintained. A subgroup of very severely retarded XO fetuses were preferentially located near the cervix. The placentas of XO fetuses were of normal size until 18½ days when they were significantly larger than those of XX controls.

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M. J. Harris, M. E. Wallace, and E. P. Evans

Summary. The spontaneous appearance of a Robertsonian translocation in a laboratory colony of genetically wild Peru—Coppock mice gave the opportunity to study potential meiotic nondisjunction soon after the formation of the new chromosome and also in a hitherto untested combination of genotype and environment. Metaphase II scores from the progenitor male had indicated a nondisjunction rate of approximately 10%, a figure that was confirmed by the finding of an estimated 12–16% total trisomic and probable monosomic zygotes in chromosomal studies of Day 9 embryos from heterozygous females. The chromosome studies also showed the presence of a significant excess of normal embryos that were heterozygous for the Robertsonian chromosome.

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P. S. Burgoyne, E. P. Evans, and Karen Holland

Summary. The growth of XO mice and their XX sisters was followed from the day of birth up to 15 weeks post partum. XO mice were underweight at birth, and grew more slowly than XX mice in the preweaning period. Some, but not all, of this decrease in growth rate was attributable to an effect of the reduced birth weight.

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D. B. Whitehouse, E. P. Evans, A. M. George, and W. Putt

Summary. A fibroblast culture from the skin of a zebra abortus recovered from a pedigree known, in part, to be segregating for a chromosome centric fission was karyotypically mosaic. Some cells were balanced for the fission and the others unbalanced, being deficient for the shorter fission product. Initially, the latter were in the majority but after continued culture (101 days) they were outgrown by the former. This finding either suggests a differential in-vivo/in-vitro fitness of the two cell types or a change in proportions resulting from some other mechanism.

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A L Hempfling, S L Lim, D L Adelson, J Evans, A E O’Connor, Z P Qu, S Kliesch, W Weidner, M K O’Bryan, and M Bergmann

This study aimed to define the expression patterns of HENMT1 and PIWI proteins in human testis and investigate their association with transposon expression, infertility sub-type or development of testicular germ cell tumours (TGCTs). Testis biopsies showing normal spermatogenesis were used to identify normal localisation patterns of HENMT1 and PIWIL1 by immunolocalisation and RT-PCR after laser microdissection. 222 testis biopsies representing normal spermatogenesis, hypospermatogenesis, spermatogenic arrests, Sertoli cell-only (SCO) tumours and TGCTs were analysed by RT-qPCR for expression of HENMT1/PIWIL1/PIWIL2/PIWIL3/PIWIL4 and LINE-1. Additionally, HENMT1-overexpressing TCam2 seminoma cell lines were analysed for the same parameters by RT-qPCR. We found that HENMT1 and PIWIL1 are coexpressed in pachytene spermatocytes and spermatids. Expression of HENMT1, PIWIL1 and PIWIL2 was mainly dependent on germ cell content but low levels of expression were also detected in some SCO samples. Levels of HENMT1, PIWIL1 and PIWIL2 expression were low in TGCT. Samples with HENMT1, PIWIL2 and PIWIL4 expression showed significantly (P < 0.05) lower transposon expression compared to samples without expression in the same histological group. HENMT1-overexpressing TCam2 cells showed lower LINE-1 expression than empty vector-transfected control lines. Our findings support that the transposon-regulating function of the piRNA pathway found in the mouse is conserved in adult human testis. HENMT1 and PIWI proteins are expressed in a germ-cell-specific manner and required for transposon control.

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R. W. Brown, J. W. Hungerford, P. E. Greenwood, R. J. Bloor, D. F. Evans, C. G. Tsonis, and R. G. Forage

Summary. Immunization of gilts in a commercial piggery against a fusion protein of the α subunit of bovine inhibin, produced by recombinant DNA methods, resulted in mean ovulation rate increases of 35% at the oestrus at which, under the piggery's management practices, they would have been mated. Sera from two immunized groups showed mean binding of 6·6% and 4·9% when assayed, at 1:800 final dilution, against iodinated bovine inhibin (M r 31 000). Ovulation rates of immunized gilts were highly correlated with the ability of serum to bind iodinated native inhibin (r = 0·62; P < 0·001), particularly when weight and age were included in the correlation (r = 0·72; P = 0·001), and inhibin binding accounted for 38% of the total variation in ovulation rate. Immunization caused no deleterious effects on growth rate or onset of oestrus. These results demonstrate the potential for use of such immunization to increase prolificacy in gilts and young sows.

Keywords: inhibin; fusion protein; immunization; ovulation rate; gilts

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K Alkhodair, H Almhanna, J McGetrick, S Gedair, M E Gallagher, B Fernandez-Fuertes, T Tharmalingam, P B Larsen, E Fitzpatrick, P Lonergan, A C O Evans, S D Carrington, and C J Reid

Sialic acid (Sia) is a major constituent of both the sperm glycocalyx and female reproductive mucosal surface and is involved in regulating sperm migration, uterotubal reservoir formation and oocyte binding. Siglecs (sialic acid-binding immunoglobulin – like lectins) commonly found on immune cells, bind to Sia in a linkage- and sugar-specific manner and often mediate cell-to-cell interactions and signalling. Proteomic and transcriptomic analysis of human and bovine sperm have listed Siglecs, but to date, their presence and/or localisation on sperm has not been studied. Therefore, the aim of this study was to characterise the presence of Siglecs on the surface of bovine, human and ovine sperm using both immunostaining and Western blotting. Siglec 1, 2, 5, 6, 10 and 14 were identified and displayed both species- and regional-specific expression on sperm. Almost universal expression across Siglecs and species was evident in the sperm neck and midpiece region while variable expression among Siglecs, similar among species, was detected in the head and tail regions of the sperm. The possible role for these proteins on sperm is discussed.

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Lucinda C Aulsebrook, Michael G Bertram, Jake M Martin, Anne E Aulsebrook, Tomas Brodin, Jonathan P Evans, Matthew D Hall, Moira K O’Bryan, Andrew J Pask, Charles R Tyler, and Bob B M Wong

Environmental pollution is an increasing problem for wildlife globally. Animals are confronted with many different forms of pollution, including chemicals, light, noise, and heat, and these can disrupt critical biological processes such as reproduction. Impacts on reproductive processes can dramatically reduce the number and quality of offspring produced by exposed individuals, and this can have further repercussions on the ecology and evolution of affected populations. Here, we illustrate how environmental pollutants can affect various components of reproduction in wildlife, including direct impacts on reproductive physiology and development, consequences for gamete quality and function, as well as effects on sexual communication, sexual selection, and parental care. We follow with a discussion of the broader ecological and evolutionary consequences of these effects on reproduction and suggest future directions that may enable us to better understand and address the effects of environmental pollution.