Influence of stage of lactation and milk production on conception rates after timed artificial insemination following Ovsynch

Conception rates after timed artificial insemination (TAI) are of paramount importance for the success of protocols based on synchronization of ovulation. Stage of lactation and milk production level are known factors that influence dairy cow fertility. It was the objective of this study to analyse the effect of stage of lactation and milk production level on conception rates and pregnancy rates by 200 days in milk (DIM) in dairy cows synchronized with the Ovsynch protocol (Day -10, Day -1: 0.1 mg of D-Phe6-gonadorelin, Day -3: 0.5 mg of cloprostenol, Day 0: AI). A total of 1,288 dairy cows were assigned to two groups and classified in three production levels (high, average, low). Cows of all milk production levels in Group 1 (Simultaneous Ovsynch, SO) were synchronized with the Ovsynch protocol simultaneously for TAI between 73 and 81 DIM. In Group 2 cows with average milk production were synchronized at the same time as Group 1, while low producing cows were synchronized 3 weeks earlier and high producing cows were synchronized 3 weeks later than Group 1, respectively. First service conception rates (FSCRs) were lower (P<0.05) in cows synchronized earlier than in cows of the same production level synchronized later (low production: 14.4% (22/153) versus 34.5% (51/148); high production: 28.2% (40/142) versus 41.4% (53/128)). Milk production level had no significant impact on conception rates after TAI in cows synchronized at the same stage of lactation. At 200 DIM fewer cows with high production level were pregnant than cows with average or low production (P<0.05). This effect was independent of the stage of lactation at the initiation of Ovsynch. Endometritis at a postpartum examination did not influence conception rates after TAI. In conclusion, stage of lactation, but not milk production level, has a major influence on conception rates after TAI. Early AI after Ovsynch is less efficient and therefore its return on investment should be evaluated carefully.     

Prevalence of Abdominal Obesity in Spanish Children and Adolescents. Do We Need Waist Circumference Measurements in Pediatric Practice?

Background

Evidence indicates that central adiposity has increased to a higher degree than general adiposity in children and adolescents in recent decades. However, waist circumference is not a routine measurement in clinical practice.

Objective

This study aimed to determine the prevalence of abdominal obesity based on waist circumferences (WC) and waist to height ratio (WHtR) in Spanish children and adolescents aged 6 to 17 years. Further, the prevalence of abdominal obesity (AO) among normal and overweight individuals was analyzed.

Design

Data were obtained from a study conducted from 1998 to 2000 in a representative national sample of 1521 children and adolescents aged 6 to 17 years (50.0% female) in Spain. WC and WHtR measurements were obtained in addition to BMI. AO was defined as WHtR ≥0.50 (WHtR-AO), sex and age specific WC≥90^th percentile (WC-AO1), and sex and age specific WC cut-off values associated with high trunk fat measured by by dual-energy X-ray absorptiometry (WC-AO2).

Results

IOTF- based overweight and obsity prevalence was 21.5% and 6.6% in children and 17.4% and 5.2% in adolescents, respectively. Abdominal obesity (AO) was defined as WHtR≥0.50 (WHtR-AO), sex- and age-specific WC≥90th percentile (WC-AO1), and sex- and age-specific WC cut-off values associated with high trunk fat measured by dual-energy X-ray absorptiometry (WC-AO2). The respective prevalence of WHtR-AO, WC-AO1, and WC-AO2 was 21.3% (24.6% boys; 17.9% girls), 9.4% (9.1% boys; 9.7% girls), and 26.8% (30.6% boys;22.9% girls) in children and 14.3% (20.0% boys; 8.7% girls), 9.6% (9.8% boys; 9.5% girls), and 21.1% (28.8% boys; 13.7% girls) in adolescents.

Conclusion

The prevalence of AO in Spanish children and adolescents is of concern. The high proportion of AO observed in young patients who are normal weight or overweight indicates a need to include waist circumference measurements in routine clinical practice.     

Nucleosome Spacing Generated by ISWI and CHD1 Remodelers Is Constant Regardless of Nucleosome Density

Arrays of regularly spaced nucleosomes are a hallmark of chromatin, but it remains unclear how they are generated. Recent genome-wide studies, in vitro and in vivo, showed constant nucleosome spacing even if the histone concentration was experimentally reduced. This counters the long-held assumption that nucleosome density determines spacing and calls for factors keeping spacing constant regardless of nucleosome density. We call this a clamping activity. Here, we show in a purified system that ISWI- and CHD1-type nucleosome remodelers have a clamping activity such that they not only generate regularly spaced nucleosome arrays but also generate constant spacing regardless of nucleosome density. This points to a functionally attractive nucleosome interaction that could be mediated either directly by nucleosome-nucleosome contacts or indirectly through the remodelers. Mutant Drosophila melanogaster ISWI without the HAND-SANT-SLIDE (HSS) domain had no detectable spacing activity even though it is known to remodel and slide nucleosomes. This suggests that the role of ISWI remodelers in generating constant spacing is not just to mediate nucleosome sliding; they actively contribute to the attractive interaction. Additional factors are necessary to set physiological spacing in absolute terms.     

Cellular Distribution of Innexin 1 and 2 Gap Junctional Channel Proteins in Epithelia of the Drosophila Embryo

Invertebrate gap junctions are composed of Innexin channel proteins that are structurally and functionally analogous to the connexins in vertebrates. In situ hybridization experiments have shown that most of the eight known innexin genes in Drosophila are expressed in a complex and overlapping temporal and spatial profile, with several members showing high levels of expression in developing epithelia of the embryo. To further study the cellular roles of Innexins, we have generated antibodies against Innexins 1 and 2 and studied their protein distribution in the developing embryo. We find that both Innexins are co-expressed in a number of epithelial tissues including the epidermis, the gut and the salivary glands. On the cellular level, we find both proteins localized to the membranes of epithelial cells. Immunohistochemical analysis using cell polarity markers indicates that Innexin 1 is predominantly localized to the baso-lateral domain of epithelial cells, basal to septate junctions. In contrast, we find a variable positioning of Innexin 2 along the apico-basal axis of epithelial cells depending on the type of tissue and organ. Our findings suggest that the distribution of Innexin channel proteins to specific membrane domains of epithelial cells is regulated by tissue specific factors during the development of epithelia in the fly embryo.     

The G2/M checkpoint phosphatase cdc25C is located within centrosomes

cdc25C is a phosphatase which regulates the activity of the mitosis promoting factor cyclin B/cdk1 by dephosphorylation, thus triggering G(2)/M transition. The activity and the sub-cellular localisation of cdc25C are regulated by phosphorylation. It is well accepted that cdc25C has to enter the nucleus to activate the cyclin B/cdk1 complex at G(2)/M transition. Here, we will show that cdc25C is located in the cytoplasm at defined dense structures, which according to immunofluorescence analysis, electron microscopy as well as biochemical subfractionation, are proven to be the centrosomes. Since cyclin B and cdk1 are also located at the centrosomes, this subfraction of cdc25C might participate in the control of the onset of mitosis suggesting a further role for cdc25C at the centrosomes.     

PRMT1 promotes the tumor suppressor function of p14ARF and is indicative for pancreatic cancer prognosis

The p14^ARF protein is a well‐known regulator of p53‐dependent and p53‐independent tumor‐suppressive activities. In unstressed cells, p14^ARF is predominantly sequestered in the nucleoli, bound to its nucleolar interaction partner NPM. Upon genotoxic stress, p14^ARF undergoes an immediate redistribution to the nucleo‐ and cytoplasm, where it promotes activation of cell cycle arrest and apoptosis. Here, we identify p14^ARF as a novel interaction partner and substrate of PRMT1 (protein arginine methyltransferase 1). PRMT1 methylates several arginine residues in the C‐terminal nuclear/nucleolar localization sequence (NLS/NoLS) of p14^ARF. In the absence of cellular stress, these arginines are crucial for nucleolar localization of p14^ARF. Genotoxic stress causes augmented interaction between PRMT1 and p14^ARF, accompanied by arginine methylation of p14^ARF. PRMT1‐dependent NLS/NoLS methylation promotes the release of p14^ARF from NPM and nucleolar sequestration, subsequently leading to p53‐independent apoptosis. This PRMT1‐p14^ARF cooperation is cancer‐relevant and indicative for PDAC (pancreatic ductal adenocarcinoma) prognosis and chemotherapy response of pancreatic tumor cells. Our data reveal that PRMT1‐mediated arginine methylation is an important trigger for p14^ARF’s stress‐induced tumor‐suppressive function.     

Two Tickets to Paradise: Multiple Dispersal Events in the Founding of Hoary Bat Populations in Hawai'i

The Hawaiian islands are an extremely isolated oceanic archipelago, and their fauna has long served as models of dispersal in island biogeography. While molecular data have recently been applied to investigate the timing and origin of dispersal events for several animal groups including birds, insects, and snails, these questions have been largely unaddressed in Hawai''i’s only native terrestrial mammal, the Hawaiian hoary bat, Lasiurus cinereus semotus. Here, we use molecular data to test the hypotheses that (1) Hawaiian L. c. semotus originated via dispersal from North American populations of L. c. cinereus rather than from South American L. c. villosissimus, and (2) modern Hawaiian populations were founded from a single dispersal event. Contrary to the latter hypothesis, our mitochondrial data support a biogeographic history of multiple, relatively recent dispersals of hoary bats from North America to the Hawaiian islands. Coalescent demographic analyses of multilocus data suggest that modern populations of Hawaiian hoary bats were founded no more than 10 kya. Our finding of multiple evolutionarily significant units in Hawai''i highlights information that should be useful for re-evaluation of the conservation status of hoary bats in Hawai''i.