Estimation of male-to-female ratios of mutation rate in primates and rodents

Haldane (1935) developed a method for estimating the male-to-female ratio of mutation rate ($\alpha$) by using sex-linked recessive genetic disease, but in six different studies using hemophilia A data the estimates of $\alpha$ varied from 1.2 to 29.3. Direct genomic sequencing is a better approach, but it is laborious and not readily applicable to non-human organisms. To study the sex ratios of mutation rate in various mammals, I used an indirect method proposed by Miyata et al. (1987). This method takes advantage of the fact that different chromosomes segregate differently between males and females, and uses the ratios of mutation rate in sequences on different chromosomes to estimate the male-to-female ratio of mutation rate. I sequenced the last intron of ZFX and ZFY genes in 6 species of primates and 2 species of rodents; I also sequenced the partial genomic sequence of the Ube1x and Ube1y genes of mice and rats. The purposes of my study in addition to estimation of $\alpha$'s in different mammalian species, are to test the hypothesis that most mutations are replication dependent and to examine the generation-time effect on $\alpha$. The $\alpha$ value estimated from the ZFX and ZFY introns of the six primate specise is ${\sim}$6. This estimate is the same as an earlier estimate using only 4 species of primates, but the 95% confidence interval has been reduced from (2, 84) to (2, 33). The estimate of $\alpha$ in the rodents obtained from Zfx and Zfy introns is ${\sim}$1.9, and that deriving from Ube1x and Ube1y introns is ${\sim}$2. Both estimates have a 95% confidence interval from 1 to 3. These two estimates are very close to each other, but are only one-third of that of the primates, suggesting a generation-time effect on $\alpha$. An $\alpha$ of 6 in primates and 2 in rodents are close to the estimates of the male-to-female ratio of the number of germ-cell divisions per generation in humans and mice, which are 6 and 2, respectively, assuming the generation time in humans is 20 years and that in mice is 5 months. These findings suggest that errors during germ-cell DNA replication are the primary source of mutation and that $\alpha$ decreases with decreasing length of generation time. ^

Life and death of the embryonic female reproductive tract

Regardless of genetic sex, amniotes develop two sets of genital ducts, the Wolffian and Müllerian ducts. Normal sexual development requires the differentiation of one duct and the regression of the other. I show that cells in the rostral most region of the coelomic epithelium (CE) are specified to a Müllerian duct fate beginning at Tail Somite Stage 19 (TS19). The Müllerian duct (MD) invaginates from the CE where it extends caudally to and reaches the Wolffian duct (WD) by TS22. Upon contact, the MD elongates to the urogenital sinus separating the WD from the CE and its formation is complete by TS34. During its elongation, the MD is associated with and dependent upon the WD and I have identified the mechanism for MD elongation. Using the Rosa26 reporter to fate map the WD, I show that the WD does not contribute cells to the MD. Using an in vitro recombinant explant culture assay I show that the entire length of the MD is derived from the CE. Furthermore, I analyzed cell proliferation and developed an in vitro assay to show that a small population of cells at the caudal tip proliferates, laying the foundation for the formation of the MD. I also show that during its formation, the MD has a distinctive mesoepithelial character. The MD in males regresses under the influence of Anti-Müllerian Hormone (AMH). Through tissue-specific gene inactivation I have identified that Acvr1 and Bmpr1a and Smad1, Smad5 and Smad8 function redundantly in transducing the AMH signal. In females the MD differentiates into an epithelial tube and eventually the female reproductive tract. However, the exact tissue into which the MD differentiates has not been determined. I therefore generated a MD specific Cre allele that will allow for the fate mapping of the MD in both females males. The MD utilizes a unique form of tubulogenesis during development and to my knowledge is the only tubule that relies upon a signal from and the presence of another distinct epithelial tube for its formation.^

FEMALE SEXUAL MATURATION AND BLOOD PRESSURE (SECONDARY-SEX CHARACTERISTICS, GROWTH, DEVELOPMENT)

This study described the relationship of sexual maturation and blood pressure in a sample (n = 361) of white females, ages seven through 18, attending public schools in a defined area of Central Texas during October through December, 1984. Other correlates of blood pressure were also described for this sample.^ A survey was performed to obtain the data on height, weight, body mass, pulse rate, upper arm circumference and length, and blood pressure. Each subject self-assessed her secondary sex characteristics (breast and pubic hair) according to drawings of the Tanner stages of maturation. The subjects were interviewed to obtain data on personal health habits and menstrual status. Student age, ethnic group and place of residence were abstracted from school records. Parents or guardians of the subjects responded to a questionnaire pertaining to parental and subject health history and parents' occupation and educational attainment.^ In the simple linear regression analysis, sexual maturation and variables of body size were significantly (p < 0.001) and positively associated with systolic and fourth- and fifth-phase diastolic blood pressure. The demographic and socioeconomic variables were not sufficiently variant in this population to have differential effects on the relation between blood pressure and maturation. Stepwise multiple regression was used to assess the contribution of sexual maturation to the variance of blood pressure after accounting for the variables of body size. Sexual maturation (breast stage) along with weight, height and body mass remained in the multiple regression models for fourth- and fifth-phase diastolic blood pressure. Only height and body mass remained in the regression model for systolic blood pressure; sexual maturation did not contribute more to the explanation of the systolic blood pressure variance.^ The association of sexual maturation with blood pressure level was established in this sample of young white females. More research is needed first, to determine if this relationship prevails in other populations of young females, and second, to determine the relationship of sexual maturation sequence and change with the change of blood pressure during childhood and adolescence. ^

Immobilisation data of juvenile and adult male and female Weddell seals at Drescher Inlet from expeditions DRE1990 and DRE1992

Fourten Weddell seals (Leptonychotes weddellii) and two crabeater seals (Lobodon carcinophaga) were immobilised at Drescher Inlet (Riiser Larsen Ice Shelf), eastern Weddell Sea coast, between January and February 1990 using a combination of ketamine, xylazine, and diazepam. Eleven Weddell seals were drugged once, and two and one were drugged two and three times each, coming to a total of 18 immobilisation procedures. Another 16 seals were immobilised between January and February 1992. Ten seals were drugged once, and three and two were drugged two and three times each, coming to a total of 25 immobilisation procedures. Narcoses were terminated with yohimbine. Data as given by doi:10.1594/PANGAEA.438920 were selected for publication. Data sets doi:10.1594/PANGAEA.438921 and doi:10.1594/PANGAEA.438926 followed the same methods and dose regimes.

Dive depth and dive duration data of subadult and adult, male and female southern elephant seals from Marion Island between 2004 and 2008 with links to datasets

Sexual segregation in habitat use occurs in a number of animal species, including southern elephant seals, where differences in migration localities and dive behaviour between sexes have been recorded. Due to the extreme sexual size dimorphism exhibited by southern elephant seals, it is unclear whether observed differences in dive behaviour are due to increased physiological capacity of males, compared to females, or differences in activity budgets and foraging behaviour. Here we use a mixed-effects modelling approach to investigate the effects of sex, size, age and individual variation on a number of dive parameters measured on southern elephant seals from Marion Island. Although individual variation accounted for substantial portions of total model variance for many response variables, differences in maximum and targeted dive depths were always influenced by sex, and only partly by body length. Conversely, dive durations were always influenced by body length, while sex was not identified as a significant influence. These results support hypotheses that physiological capability associated with body size is a limiting factor on dive durations. However, differences in vertical depth use appear to be the result of differences in forage selection between sexes, rather than a by-product of the size dimorphism displayed by this species. This provides further support for resource partitioning and possible avoidance of inter-sexual competition in southern elephant seals.

Characteristics of eggs and female adults of Calanus finmarchicus, C. glacialis and C. hyperboreus from Disko Bay, western Greenland

This is the first high temporal-resolution study in Disko Bay covering population dynamics, grazing, reproduction, and biochemical composition of 3 dominating copepod species (Calanus finmarchicus, C. glacialis and C. hyperboreus) from late winter to midsummer in 2008. C. finmarchicus and C. glacialis ascended to the surface layer at the onset of the spring phytoplankton bloom, followed by C. hyperboreus 2 wk later. C. finmarchicus spawning occurred during the bloom and postbloom period, partially fueled by wax esters. C. glacialis commenced spawning before the bloom, yet it was greatly stimulated when food became available. However, feeding and reproduction was terminated after the main bloom despite the presence of food. In terms of feeding, this was also the strategy for C. hyperboreus. Between pre-bloom and post-bloom, C. finmarchicus showed an increase in carbon, nitrogen, and phospholipid content but a decrease in total lipid content. This was likely the result of protein synthesis, oocyte maturation, and spawning fueled by wax esters and by feeding. C. glacialis showed a similar pattern, although with an increasing total lipid content from pre-bloom to post-bloom, and an increasing wax ester and decreasing phospholipid content after reproduction was terminated. C. hyperboreus showed greatly increased content of carbon, nitrogen, and all lipid classes between the pre- and post-bloom periods. Hence, C. finmarchicus commenced feeding and spawning at the onset of the bloom and continued throughout the remaining study period. Both C. glacialis and C. hyperboreus females refueled their storage lipids (wax esters) during the bloom and post-bloom period, suggesting that they may spawn in an additional year.

Total length, and lipid and toxaphene content in blubber of minke whales (B. acutorostrata) from the North Atlantic

Toxaphene contamination of minke whales (Balaenoptera acutorostrata) from North Atlantic waters was examined for the first time. Total toxaphene and SumCHB (sum of 11 chlorobornanes) concentrations in blubber samples ranged from 170 ± 110 and 41 ± 39 ng/g lipid weight (l.w.) for female minke whales from southeastern Greenland to 5800 ± 4100 and 1100 ± 780 ng/g l.w. for males from the North Sea, respectively. Very large variations in toxaphene concentrations among sampling areas were observed suggesting a spatial segregation of minke whales. However, much of the apparent geographical discrimination was explained by the seasonal fluctuation of animal fat mass. Patterns of CHBs in males revealed that recalcitrant CHBs were in higher proportions in animals from the more easterly areas than in animals from the more westerly areas. This trend may be influenced by the predominance of the US, over the European, input of toxaphene to North Atlantic waters.

Dive track profile, intermandibular angel sensor profile and immobilisation data of adult female Weddell seals at Drescher Inlet from expedition DRE2003

Determination of when and where animals feed and how much they consume is fundamental to understand their ecology and role in ecosystems. However, the lack of reliable data on feeding habits of wild animals, and particularly in marine endotherms, attests to the difficulty in doing this. A promising recent development proposes using a Hall sensor-magnet System - the inter-mandibular angle sensor (IMASEN) attached to animals' jaws to elucidate feeding events. We conducted trials on captive pinnipeds by feeding IMASEN-equipped animals with prey to examine the utility of this system. Most feeding events were clearly distinguishable from other jaw movements; only small prey items might not be resolved adequately. Based on the results of this study we examined feeding events from free-ranging Weddell seals fitted with IMASENs and dead-reckoners during December 2003 at Drescher Inlet (Riiser Larsen Ice Shelf, eastern Weddell Sea coast), and present data on prey capture and ingestion in relation to the three-dimensionalmovement patterns of the seals. A total of 19 Weddell seals were immobilised by using a combination of ketamine, xylazine, and diazepam. Eight seals were drugged once, six two times, and two and three were drugged three and four times each, coming to a total of 38 immobilisation procedures. Narcoses were terminated with yohimbine (doi:10.1594/PANGAEA.438931).

Dive depth profile and immobilisation data of adult male and female Weddell seals at Drescher Inlet from expedition DRE1998

Adult male and female Weddell seals (Leptonychotes weddellii) were fitted with Time-depth recorders (TDR) at Drescher Inlet (Riiser Larsen Ice Shelf), eastern Weddell Sea coast, in February 1998. Eight of 15 data sets were selected for analyses to investigate the seals' foraging behaviour (doi:10.1594/PANGAEA.511465, doi:10.1594/PANGAEA.511454, doi:10.1594/PANGAEA.511456, doi:10.1594/PANGAEA.511457, doi:10.1594/PANGAEA.511459, doi:10.1594/PANGAEA.511462, doi:10.1594/PANGAEA.511466, doi:10.1594/PANGAEA.511467). These data sets provided simultaneous dive records of eight seals over eight days. The seals primarily foraged within two depth layers, these being from the sea surface to 160 m where temperature and salinity varied considerably, and from 340 to 450 m near the bottom where temperature was lowest and salinity highest, with little variation. While pelagic and benthic diving occurred during daylight, the seals foraged almost exclusively in the upper water column at night. Trawling during daytime confirmed that Pleuragramma antarcticum were by far the most abundant fish both in the pelagial and close to the bottom. Pelagic night-hauls at 110-170 m depth showed highly variable biomass of P. antarcticum with a peak at around midnight. The temporal changes in the local abundance of P. antarcticum, particularly in the pelagial, may explain the trends in the seals' pelagic and benthic foraging activities. This is the first study which describes the jaw movements of a hunting seal which are presumably indicative of feeding events. Trophic links from the Weddell seal to fish, zooplankton and krill, Euphausia superba, are discussed. Another seven data sets did not overlap substantially with the selected time frame (doi:10.1594/PANGAEA.511458, doi:10.1594/PANGAEA.511460, doi:10.1594/PANGAEA.511464, doi:10.1594/PANGAEA.511468, doi:10.1594/PANGAEA.511469, doi:10.1594/PANGAEA.511453, doi:10.1594/PANGAEA.511463). A total of 25 Weddell seals were immobilised during the study period using a combination of ketamine, xylazine, and diazepam. Seven seals were drugged once, 15 seals two times, and three were drugged three times, coming to a total of 46 immobilisation procedures. Narcoses were terminated with yohimbine (doi:10.1594/PANGAEA.438933).

Female preference for swords in Xiphophorus helleri reflects a bias for large apparent size

Swordtail fish (Poeciliidae: genus Xiphophorus) are a paradigmatic case of sexual selection by sensory exploitation. Female preference for males with a conspicuous “sword” ornament is ancestral, suggesting that male morphology has evolved in response to a preexisting bias. The perceptual mechanisms underlying female mate choice have not been identified, complicating efforts to understand the selection pressures acting on ornament design. We consider two alternative models of receiver behavior, each consistent with previous results. Females could respond either to specific characteristics of the sword or to more general cues, such as the apparent size of potential mates. We showed female swordtails a series of computer-altered video sequences depicting a courting male. Footage of an intact male was preferred strongly to otherwise identical sequences in which portions of the sword had been deleted selectively, but a disembodied courting sword was less attractive than an intact male. There was no difference between responses to an isolated sword and to a swordless male of comparable length, or between an isolated sword and a homogenous background. Female preference for a sworded male was abolished by enlarging the image of a swordless male to compensate for the reduction in length caused by removing the ornament. This pattern of results is consistent with mate choice being mediated by a general preference for large males rather than by specific characters. Similar processes may account for the evolution of exaggerated traits in other systems.

Restriction fragment length polymorphism-coupled domain-directed differential display: a highly efficient technique for expression analysis of multigene families.

In this paper, a reverse-transcriptase PCR-based protocol suitable for efficient expression analysis of multigene families is presented. The method combines restriction fragment length polymorphism (RFLP) technology with a gene family-specific version of mRNA differential display and hence is called "RFLP-coupled domain-directed differential display. "With this method, expression of all members of a multigene family at many different developmental stages, in diverse tissues and even in different organisms, can be displayed on one gel. Moreover, bands of interest, representing gene family members, are directly accessible to sequence analysis, without the need for subcloning. The method thus enables a detailed, high-resolution expression analysis of known gene family members as well as the identification and characterization of new ones. Here the technique was used to analyze differential expression of MADS-box genes in male and female inflorescences of maize (Zea mays ssp. mays). Six different MADS-box genes could be identified, being either specifically expressed in the female sex or preferentially expressed in male or female inflorescences, respectively. Other possible applications of the method are discussed.

Shift Work and the United States Female Workforce: The Relationship Between Shift-Work and Ill-Health Effects

The present study was designed to determine the magnitude of the relationship between amount, frequency, and length of shift work completed by female transportation employees and the number, degree, and extent of problems related to physical, menstrual and psychological health including depression. It was hypothesized that workers that are employed in areas such as transportation who are working shift work on a regular basis place themselves at higher risk for developing health or psychosocial related effects. These health related outcomes can have a profound impact on an employee’s job performance, daily functioning, and personal life. The present study sought to understand the potential relationship between working shift work and higher disturbances to the bodies’ natural functioning. The present study has the potential for explaining new ways to decrease the risk factors for those working shift work by contributing to the overall understanding of this multifaceted relationship. This study has many important findings and implications. This study has implications for explaining that the effects of disturbances to the circadian rhythm as a result of certain shift work schedules can result in ill-related health effects. Additionally, this study sought to challenge limitations to current research that has been conducted on the topic as the majority of studies have been performed on men. The overall purpose of the study was to gain a better understanding of the negative effects of shift work on females working within the transportation industry. This study sought to explain the health implications specifically for female workers as fewer studies have been conducted with gender as a main effect in the analysis. The present study suggests that due to the circadian rhythm controlling hormone secretion within the body, disturbances to its natural rhythm can have additional effects on female cycles such as menstruation. Overall, this study offers implications for further research on females working shift work and highlights the continued importance for further exploration into recent developments. These implications have the potential to further our current understanding of the relationship between shift work and ill-health effects, particularly the factors that women face.