Controls of Litter Size—Do Conclusions Drawn from Institutional Research Herds Always Have Relevance to Commercial Swine Production?

Increasing litter size in pigs has been an ongoing concern of many producers because it has the greatest impact on profitability of the swine enterprise. To study the biology of conceptus growth and survival, many models have been used by researchers. It was determined that a major component in limiting litter size results from the impacts of limitations in uterine space (i.e. uterine capacity). Placental efficiency, which is the ratio of a fetus’s weight compared with that of its placenta, has been shown to impact litter size, and is heritable. Selection for breeding animals having a high placental efficiency at term, has been shown to increase litter size. Furthermore, although piglet weight was only slightly decreased in offspring of boars and gilts selected for increased placental efficiency, placental size was profoundly reduced. This reduction in placental size was coupled with an increase in vascularity, thus nutrient and oxygen uptake by the conceptus could be accomplished over a decreased surface area of attachment to the uterine wall. Reproductive data obtained to date have been gathered largely from university swine herds that may have little relevance to commercially used US pig breeds. In contrast to the constant evaluations of physiological changes associated with increased litter size at universities, swine seed stock producers have selected for many generations simply on increased litter size and have not bothered to evaluate the resulting physiological changes associated with increased fecundity. Therefore, it was the objective of this study to investigate the reproductive characteristics of a commercially relevant swine herd in Iowa (PIC Camborough Line) at selected gestational ages. Multiparous sows (ranging from 1 to 14 parities) were slaughtered on days 25, 36, and 44 of gestation, time periods corresponding to intervals which are before, during, and after the time when uterine capacity becomes limiting. At the laboratory, the uterine horns were measured and ovulation rate was determined. Conceptuses were removed and fetal and placental weights were determined. Uterine horn length and ovulation rate did not differ between the three gestational groups. Conceptus number decreased from 15.8 ± 0.6 on day 25 to 12.9 ± 0.5 and 12.1 ± 0.4 on day 36 and day 44 (litter size in this population averages ~11.5 liveborn piglets/litter). Conceptus survival to day 25 was 60.2 ± 0.1%, which then decreased to 50.1 ± 0.1% on day 36 and 46.3 ± 0.1% on day 44. There was a positive correlation between conceptus number and ovulation rate on day 25 but by day 36 this association was lost. Conceptus number was not associated with uterine length on day 25, but by day 36 there was a positive association that remained through day 44. On all three gestation days there was a negative association between conceptus number and placental weight, but no association between conceptus number and fetal weight was observed, indicating that larger litters are comprised of conceptuses having small placentae, but the same sized fetuses. These data indicate that, compared with commonly reported values for university herds (16-18 ovulations), ovulation rate in these mixed parity production animals is extremely high, whereas conceptus survival as estimated from the number of conceptuses divided by the number of ovulations was very low. Additionally, although conceptus number was related to the ovulation rate on day 25, by day 36 the limitations of uterine size began to reduce conceptus number irrespective of ovulation rate. These data suggest that ovulation rate is not a limiting factor in litter size in this line of commercially relevant pigs. In contrast, the higher than expected ovulation rate observed in these pigs resulted in significant embryo losses and early uterine crowding. The consequences of this early conceptus crowding may have detrimental impacts on prenatal and postnatal growth rate and survival

Controls of Litter Size—Do Conclusions Drawn from Institutional Research Herds Always Have Relevance to Commercial Swine Production?

Increasing litter size in pigs has been an ongoing concern of many producers because it has the greatest impact on profitability of the swine enterprise. To study the biology of conceptus growth and survival, many models have been used by researchers. It was determined that a major component in limiting litter size results from the impacts of limitations in uterine space (i.e. uterine capacity). Placental efficiency, which is the ratio of a fetus’s weight compared with that of its placenta, has been shown to impact litter size, and is heritable. Selection for breeding animals having a high placental efficiency at term, has been shown to increase litter size. Furthermore, although piglet weight was only slightly decreased in offspring of boars and gilts selected for increased placental efficiency, placental size was profoundly reduced. This reduction in placental size was coupled with an increase in vascularity, thus nutrient and oxygen uptake by the conceptus could be accomplished over a decreased surface area of attachment to the uterine wall. Reproductive data obtained to date have been gathered largely from university swine herds that may have little relevance to commercially used US pig breeds. In contrast to the constant evaluations of physiological changes associated with increased litter size at universities, swine seed stock producers have selected for many generations simply on increased litter size and have not bothered to evaluate the resulting physiological changes associated with increased fecundity. Therefore, it was the objective of this study to investigate the reproductive characteristics of a commercially relevant swine herd in Iowa (PIC Camborough Line) at selected gestational ages. Multiparous sows (ranging from 1 to 14 parities) were slaughtered on days 25, 36, and 44 of gestation, time periods corresponding to intervals which are before, during, and after the time when uterine capacity becomes limiting. At the laboratory, the uterine horns were measured and ovulation rate was determined. Conceptuses were removed and fetal and placental weights were determined. Uterine horn length and ovulation rate did not differ between the three gestational groups. Conceptus number decreased from 15.8 ± 0.6 on day 25 to 12.9 ± 0.5 and 12.1 ± 0.4 on day 36 and day 44 (litter size in this population averages ~11.5 liveborn piglets/litter). Conceptus survival to day 25 was 60.2 ± 0.1%, which then decreased to 50.1 ± 0.1% on day 36 and 46.3 ± 0.1% on day 44. There was a positive correlation between conceptus number and ovulation rate on day 25 but by day 36 this association was lost. Conceptus number was not associated with uterine length on day 25, but by day 36 there was a positive association that remained through day 44. On all three gestation days there was a negative association between conceptus number and placental weight, but no association between conceptus number and fetal weight was observed, indicating that larger litters are comprised of conceptuses having small placentae, but the same sized fetuses. These data indicate that, compared with commonly reported values for university herds (16-18 ovulations), ovulation rate in these mixed parity production animals is extremely high, whereas conceptus survival as estimated from the number of conceptuses divided by the number of ovulations was very low. Additionally, although conceptus number was related to the ovulation rate on day 25, by day 36 the limitations of uterine size began to reduce conceptus number irrespective of ovulation rate. These data suggest that ovulation rate is not a limiting factor in litter size in this line of commercially relevant pigs. In contrast, the higher than expected ovulation rate observed in these pigs resulted in significant embryo losses and early uterine crowding. The consequences of this early conceptus crowding may have detrimental impacts on prenatal and postnatal growth rate and survival.</p

A recombination hotspot leads to sequence variability within a novel gene (AK005651) and contributes to type 1 diabetes susceptibility

More than 25 loci have been linked to type 1 diabetes (T1D) in the nonobese diabetic (NOD) mouse, but identification of the underlying genes remains challenging. We describe here the positional cloning of a T1D susceptibility locus, Idd11, located on mouse chromosome 4. Sequence analysis of a series of congenic NOD mouse strains over a critical 6.9-kb interval in these mice and in 25 inbred strains identified several haplotypes, including a unique NOD haplotype, associated with varying levels of T1D susceptibility. Haplotype diversity within this interval between congenic NOD mouse strains was due to a recombination hotspot that generated four crossover breakpoints, including one with a complex conversion tract. The Idd11 haplotype and recombination hotspot are located within a predicted gene of unknown function, which exhibits decreased expression in relevant tissues of NOD mice. Notably, it was the recombination hotspot that aided our mapping of Idd11 and confirms that recombination hotspots can create genetic variation affecting a common polygenic disease. This finding has implications for human genetic association studies, which may be affected by the approximately 33,000 estimated hotspots in the genome

Astro2020 Science White Paper: Construction of an L* Galaxy: the Transformative Power of Wide Fields for Revealing the Past, Present and Future of the Great Andromeda System

Submitted as a science white paper to the Astro2020 Decadal SurveyThe Great Andromeda Galaxy (M31) is the nexus of the near-far galaxy evolution connection and a principal data point for near-field cosmology. Due to its proximity (780 kpc), M31 can be resolved into individual stars like the Milky Way (MW). Unlike the MW, we have the advantage of a global view of M31, enabling M31 to be observed with techniques that also apply to more distant galaxies. Moreover, recent evidence suggests that M31 may have survived a major merger within the last several Gyr, shaping the morphology of its stellar halo and triggering a starburst, while leaving the stellar disk largely intact. The MW and M31 thus provide complementary opportunities for in-depth studies of the disks, halos, and satellites of L* galaxies. Our understanding of the M31 system will be transformed in the 2020s if they include wide field facilities for both photometry (HST-like sensitivity and resolution) and spectroscopy (10-m class telescope, >1 sq. deg. field, highly multiplexed, R~ 3000 to 6000). We focus here on the power of these facilities to constrain the past, present, and future merger history of M31, via chemo-dynamical analyses and star formation histories of phase-mixed stars accreted at early times, as well as stars in surviving tidal debris features, M31's extended disk, and intact satellite galaxies that will eventually be tidally incorporated into the halo. This will yield an unprecedented view of the hierarchical formation of the M31 system and the subhalos that built it into the L* galaxy we observe today

Astro2020 Science White Paper: Construction of an L* Galaxy: the Transformative Power of Wide Fields for Revealing the Past, Present and Future of the Great Andromeda System

The Great Andromeda Galaxy (M31) is the nexus of the near-far galaxy evolution connection and a principal data point for near-field cosmology. Due to its proximity (780 kpc), M31 can be resolved into individual stars like the Milky Way (MW). Unlike the MW, we have the advantage of a global view of M31, enabling M31 to be observed with techniques that also apply to more distant galaxies. Moreover, recent evidence suggests that M31 may have survived a major merger within the last several Gyr, shaping the morphology of its stellar halo and triggering a starburst, while leaving the stellar disk largely intact. The MW and M31 thus provide complementary opportunities for in-depth studies of the disks, halos, and satellites of L* galaxies. Our understanding of the M31 system will be transformed in the 2020s if they include wide field facilities for both photometry (HST-like sensitivity and resolution) and spectroscopy (10-m class telescope, &gt;1 sq. deg. field, highly multiplexed, R~ 3000 to 6000). We focus here on the power of these facilities to constrain the past, present, and future merger history of M31, via chemo-dynamical analyses and star formation histories of phase-mixed stars accreted at early times, as well as stars in surviving tidal debris features, M31's extended disk, and intact satellite galaxies that will eventually be tidally incorporated into the halo. This will yield an unprecedented view of the hierarchical formation of the M31 system and the subhalos that built it into the L* galaxy we observe today

Critical Discourse Analysis: Definition, Approaches, Relation to Pragmatics, Critique, and Trends

This chapter introduces the transdisciplinary research movement of critical discourse analysis (CDA) beginning with its definition and recent examples of CDA work. In addition, approaches to CDA such as the dialectical relational (Fairclough), sociocognitive (van Dijk), discourse historical (Wodak), social actors (van Leeuwen), and the Foucauldian dispositive analysis (Jager and Maier) are outlined, as well as the complex relation of CDA to pragmatics. Next, the chapter provides a brief mention of the extensive critique of CDA, the creation of critical discourse studies (CDS), and new trends in CDA, including positive discourse analysis (PDA), CDA with multimodality, CDA and cognitive linguistics, critical applied linguistics, and other areas (rhetoric, education, anthropology/ethnography, sociolinguistics, culture, feminism/gender, and corpus studies). It ends with new directions aiming towards social action for social justice