Premature ovarian ageing following heterozygous loss of Senataxin

Premature loss of ovarian activity before 40 years of age is known as primary ovarian insufficiency (POI) and occurs in ∼1% of women. A more subtle decline in ovarian activity, known as premature ovarian ageing (POA), occurs in ∼10% of women. Despite the high prevalence of POA, very little is known regarding its genetic causation. Senataxin (SETX) is an RNA/DNA helicase involved in repair of oxidative stress-induced DNA damage. Homozygous mutation of SETX leads to the neurodegenerative disorder, ataxia oculomotor apraxia type 2 (AOA2). There have been reports of POI in AOA2 females suggesting a link between SETX and ovarian ageing. Here, we studied female mice lacking either one (Setx+/−) or both (Setx−/−) copies of SETX over a 12- to 14-month period. We find that DNA damage is increased in oocytes from 8-month-old Setx+/− and Setx−/− females compared with Setx+/+ oocytes leading to a marked reduction in all classes of ovarian follicles at least 4 months earlier than typically occurs in female mice. Furthermore, during a 12-month long mating trial, Setx+/− and Setx−/− females produced significantly fewer pups than Setx+/+ females from 7 months of age onwards. These data show that SETX is critical for preventing POA in mice, likely by preserving DNA integrity in oocytes. Intriguingly, heterozygous Setx loss causes an equally severe impact on ovarian ageing as homozygous Setx loss. Because heterozygous SETX disruption is less likely to produce systemic effects, SETX compromise could underpin some cases of insidious POA.

Simplified Method to Measure Mouse Fertility

Estimating breeding performance from mouse mating trials has focused on lifetime mating trials, which are too slow and costly for characterizing the many novel genetic mouse lines produced in fertility research, an underpinning of reproductive pathophysiology research. This study introduces the fertility index, defined as the slope of the regression of cumulative number of pups produced by a female over elapsed time in a monogamous mating trial. By using a robust resampling technique, the Theil-Sen estimator (widely available in free or niche statistical software), to estimate the fertility index, the present study of 410 mating trials of mice from 7 genotypes lasting a median of 10 litters shows that it is possible to estimate the fertility index reliably over as few as 4 litters.

Females of a cannibalistic spider control mutilation of their genitalia by males

When females can mate multiply, the interests of both sexes over female remating may not coincide, leading to selection for adaptations and counteradaptations in males and females. In several orb-weaving spiders, males damage external structures of the female genitalia during copulation, which hinders the female from remating. We investigated whether females have control over the mutilation of their genitalia in the orb-weaving spider Larinia jeskovi. We found that female sexual cannibalism during copulation reduced the number of insertions a male was able to perform and hence limited the probability of genital mutilation by the male. Genital mutilation did not differ between treatments in which females experienced different availabilities of other males before the mating trial: males absent, males near the female (“vicinity group”), and males in the female’s web (“web group”). However, traits of the mating male (size, condition) were significantly correlated with the occurrence of cannibalism during mating in “web” and “vicinity” treatments. These results suggest that females have control over mutilation by an early termination of mating, can respond to the availability of potential mates and can alter the probability of mutilation according to certain male traits. Female sexual cannibalism may represent a counteradaptation to genital mutilation allowing females to mate multiply.

Optimal culling strategy in relation to biological and economic efficiency and annualized net revenue in the Japanese Black cow–calf production system

SUMMARYThe objective of the present study was to determine the optimal culling strategy in relation to biological and economic efficiency (BE and EE, respectively) and annualized net revenue (AN) in the Japanese Black cow–calf production system with special reference to the beef quality of culled cows. The herd model focused on two ways of mating: one-mating trial system (ONE) and continuous-mating trial system (CON). ONE assumed that heifers that fail to conceive are culled and cows that fail to conceive are culled at weaning of their calves, while CON assumed that mating continues until all females theoretically conceive. Least square means of carcass data of Japanese Black cows collected from a cooperative farm in Japan were used to estimate the carcass price of a cow by parity and Beef Marbling Standard (BMS) number. The simulation, assuming the current production situation in Japan, indicated that sales of culled cows accounted for 0·10–0·20 of total sales and was an important element in total production. Comparisons between ONE and CON showed that production efficiency in the current situation is higher in CON. The BE, EE and AN were higher in CON than in ONE. The two economic indicators were less sensitive to changes in annual discount rate but highly sensitive to changes in female calf price and BMS number of cows, indicating the importance of considering fluctuations in calf price and potential quality of culled cows’ carcasses when estimating the economically optimal parity of culling. The three indicators derived different optimal solutions even in the same mating trial systems, stressing the importance of choice of production indicators when determining the culling strategy and evaluating animal production.

Effect of predation on male mating behaviour in a unisexual-bisexual mating system

Mate choice for conspecifics is beneficial when closely related species live in sympatry, but mate choice can be costly in the presence of predators. Male sailfin mollies are sexually parasitized by gynogenetic Amazon mollies. Amazon mollies must mate with male sailfin mollies to initiate embryogenesis, but inheritance is maternal. We tested if male sailfin molly mate choice for conspecific females is affected by predation risk. Male mate choice was tested in one of four treatments: (1) predation/no refuge, (2) predation/refuge, (3) no predation/refuge and (4) no predation/no refuge. Predation consisted of dipping the beak of a great blue heron decoy in the aquarium prior to a mating trial. Refuge was provided by java-moss. For each trial the number of mating attempts toward each female was recorded. There was a significant interaction between predation and refuge on strength of preference (SOP) for conspecific females. The highest SOP was in the no predator/no refuge treatment, and the lowest SOP was in the predator/no refuge treatment. These results suggest that the cost of predation is higher than the cost of mating with heterospecifics, and that the presence of a refuge may reduce this cost. This could explain the continued maintenance of Amazon mollies.

Porcine zonae pellucidae immunisation of tammar wallabies (Macropus eugenii): fertility and immune responses

This study looked at the feasibility of targeting the zona pellucida for a contraceptive vaccine as a possible alternative method of control for overabundant macropods. Tammar wallabies, as a model for other macropods, were immunized with porcine zonae pellucidae (PZP) and were found to achieve significant concentrations of antibody to PZP in sera and reproductive tract fluids. Wallabies immunized with PZP exhibited lower ovarian weight with reduced numbers of antral follicles when compared with control animals. Wallabies were placed in a natural mating trial followed by an artificial insemination trial. None of the PZP-immunized wallabies produced offspring in the natural mating trial compared with 67% of control animals. To further assess fertility, a sub-sample of the wallabies were superovulated and artificially inseminated. This resulted in all control wallabies producing fertilized ova and all PZP-immunized wallabies failing to ovulate. These results suggest that immunocontraception based on targeting antigens of the zona pellucida may be an effective strategy for fertility reduction in macropods.

THE RISK OF CANNIBALISM AND MALE MATING BEHAVIOR IN THE MEDITERRANEAN PRAYING MANTID, IRIS ORATORIA

This study examined male behavior in response to the risk of cannibalism in the Mediterranean praying mantid, Iris oratoria (Mantodea: Mantidae). The risk of cannibalism was manipulated by placing males in one of two positions at the start of a mating trial: Frontal, where the males faced the females' fronts (high risk of cannibalism), or Rear, where the males were behind the females, facing their posteriors (lower risk). Three male behaviors were examined in terms of risk-reduction: whether the male attempted to mount the female, the direction of his first mount attempt, and the time taken for him to attempt to mount. Initial position did not have a significant effect on whether males attempted to mount the females. Males showed a preference for non-frontal mount attempts, and males placed Frontally were less likely to mount from their initial direction than were males placed in the Rear. Males placed in the Rear attempted to mount sooner than males placed Frontally, especially if the males could approach and mount while remaining behind the females. While the males approached the females, movements by both sexes resulted in changes in how the males faced the females,

Detection of Effects on Male Reproduction—A Literature Survey

The 1CH (International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use) Guideline for Detection of Toxicity to Reproduction for Medicinal Products, adopted at the Second ICH Conference in Orlando, FL, U.S.A., emphasized the need for research into the suitability of various methods for the detection of effects on fertility in males. The current project was undertaken to compare the efficiency of methods by evaluating reports in the open literature. The results of the examination of 117 substances or substance classes support the view that histopathology and organ weight analysis provide the best general-purpose means of detecting substances with the potential to affect male fertility. Examinations at up to 4 weeks of treatment appear to be as effective as examinations conducted at later times. Mating with females for detection of effects unrelated to interference with sperm production appears to provide an optimal combination because adding other methodologies does not materially improve the detection rate. As to the timing of the mating trial, a 2-week premating period is as efficient as mating at 4 weeks and apparently more efficient than mating after prolonged premating treatment.

Evaluation of a New Reproductive Toxicology Protocol Using Diethylstilbestrol (DES) as a Positive Control Compound

A new National Toxicology Program (NTP) reproductive toxicology assay designated Fertility Assessment by Continuous Breeding was evaluated using trans-diethylstilbestrol (DES) as a positive control compound. The testing scheme employs young adult CD-1 male and female mice and is comprised of 5 possible tasks: task 1, 14-day dose-finding (repeated or continuous dosing); task 2, continuous breeding; task 3, determination of affected sex; task 4, offspring assessment; task 5, hormone patterns. Only tasks 2 and 3 were performed in the present study. Task 2 employed dietary levels of 0, 1, 10, and 50 ppb DES (99% pure). Task 3 used the control and high dose parental mice from task 2 in a crossover mating trial (control x treated) to determine whether one or both sexes in the F0 generation were adversely affected. Continuous exposure of F0 mice to 50 ppb DES in the diet during task 2 significantly decreased (P < 0.01) the proportion of pairs that produced at least 1 litter as compared to pairs continuously exposed to dietary levels of 0, 1, and 10 ppb DES. In addition, continuous exposure to 50 ppb DES in the diet had a cumulative adverse effect on the production and viability of litters. Thus, the pairs fed 50 ppb DES produced significantly fewer litters (P < 0.01), had fewer live pups per litter (P < 0.01), and tended toward a lower proportion of pups born alive per litter than did pairs in the 0, 1, and 10 ppb DES groups. In the crossover mating trial (task 3) the proportion of F0 females that mated (number with copulatory plugs/number cohabited) and that were fecund (number delivering litters/number with copulatory plugs) did not differ significantly among the 3 different combinations of paired mice. It was noted, however, that the proportion of cohabited F0 females delivering litters (number delivering litters/number cohabited) was significantly reduced (P < 0.05) in the control male x 50 ppb DES female group vs. the control male x control female group. The proportion of cohabited F0 females delivering litters in the 50 ppb DES male x control female group did not differ significantly from either of the above groups. Further, the number of live pups per litter and the proportion of pups born alive were significantly lower (P < 0.01) in the F0 control male x 50 ppb DES female group than in the other 2 groups. The proportion of male pups born alive (males/total) and the live pup weights, however, did not differ significantly among the 3 combinations of paired mice. Collectively, these results indicated that DES interfered with ovulation, conception, pre- and postimplantational processes in female mice. Thus, this new assay readily discriminated DES as a reproductive toxicant in CD-1 mice.

Sustained colonization of the black fly Simulium decorum Walker (Diptera: Simuliidae)

The black fly Simulium decorum Walker has been colonized for 16 generations (18 months) using an inexpensive larval rearing system. More than 90% of the females are induced with simulated twilight to oviposit on floating cork substrates. Eggs on corks have been successfully stored for up to 2 months at 0.5–1.5 °C. Female survival averages 87% for 4 days at 22 °C and 90–95% relative humidity. Mating in aspirator tubes results in nearly 100% insemination, whereas a cage mating trial resulted in only 26% insemination. Under crowded conditions where larvae are underfed, emerging males are smaller and mature fewer eggs. Though autogenous, nulliparous females readily blood feed on humans but do not mature additional eggs.