Steroid control of gonadotropin-releasing hormone secretion: associated changes in pro-opiomelanocortin and preproenkephalin messenger RNA expression in the ovine hypothalamus

The endogenous opioid peptides have been implicated in mediating the actions of estrogen and progesterone on GnRH release. We used in situ hybridization histochemistry to determine whether steroid-induced changes in GnRH/LH release in the female sheep are associated with changes in the cellular mRNA content of the precursors for beta-endorphin (pro-opiomelanocortin; POMC) and met-enkephalin (pre-proenkephalin; PENK). Two specific hypotheses were tested. First, that the inhibitory actions of progesterone are associated with an increase in opioid gene expression in specific hypothalamic nuclei. Our data support this hypothesis. Thus, an increase in progesterone was associated with increased POMC gene expression in the arcuate nucleus and PENK in the paraventricular nucleus. Further, the increase in POMC was restricted to regions of the arcuate nucleus that contain steroid sensitive beta-endorphin neurons. Our second hypothesis, that gene expression for the two opioid precursors would decrease prior to the start of the estradiol-stimulated GnRH surge, was not supported. Rather, POMC (but not PENK) gene expression in the arcuate nucleus was significantly higher in estradiol-treated animals than controls at the peak of the GnRH surge. These data suggest that beta-endorphin neurons in subdivisions of the arcuate nucleus and enkephalin neurons in the paraventricular nucleus are part of the neural network by which progesterone inhibits LH release. While enkephalin neurons may not play a role in estrogen positive feedback, increases in POMC mRNA in the arcuate nucleus at the time of the GnRH peak may be important for replenishing beta-endorphin stores and terminating estrous behavior.     

Sensitivity of yeast strains with long G-tails to levels of telomere-bound telomerase

The Saccharomyces cerevisiae Pif1p helicase is a negative regulator of telomere length that acts by removing telomerase from chromosome ends. The catalytic subunit of yeast telomerase, Est2p, is telomere associated throughout most of the cell cycle, with peaks of association in both G1 phase (when telomerase is not active) and late S/G2 phase (when telomerase is active). The G1 association of Est2p requires a specific interaction between Ku and telomerase RNA. In mutants lacking this interaction, telomeres were longer in the absence of Pif1p than in the presence of wild-type PIF1, indicating that endogenous Pif1p inhibits the active S/G2 form of telomerase. Pif1p abundance was cell cycle regulated, low in G1 and early S phase and peaking late in the cell cycle. Low Pif1p abundance in G1 phase was anaphase-promoting complex dependent. Thus, endogenous Pif1p is unlikely to act on G1 bound Est2p. Overexpression of Pif1p from a non-cell cycle-regulated promoter dramatically reduced viability in five strains with impaired end protection (cdc13–1, yku80Δ, yku70Δ, yku80–1, and yku80–4), all of which have longer single-strand G-tails than wild-type cells. This reduced viability was suppressed by deleting the EXO1 gene, which encodes a nuclease that acts at compromised telomeres, suggesting that the removal of telomerase by Pif1p exposed telomeres to further C-strand degradation. Consistent with this interpretation, depletion of Pif1p, which increases the amount of telomere-bound telomerase, suppressed the temperature sensitivity of yku70Δ and cdc13–1 cells. Furthermore, eliminating the pathway that recruits Est2p to telomeres in G1 phase in a cdc13–1 strain also reduced viability. These data suggest that wild-type levels of telomere-bound telomerase are critical for the viability of strains whose telomeres are already susceptible to degradation.     

Removal of virus from boar semen spiked with porcine circovirus type 2

The virus porcine circovirus type 2 (PCV2) is associated with different disease entities, including reproductive failure. The objective of this study was to investigate the use of a semen processing technique for the elimination of infectious PCV2 in semen. PCV2 was chosen as a model virus because of its small size, high resistance to inactivation and as a known risk factor for boar semen contamination. Aliquots of ejaculates were spiked with PCV2 and processed by a double processing technique, consisting of Single Layer Centrifugation on Androcoll?-P followed by a "swim-up" procedure. Samples were collected from the resulting fractions during the selection process and analyzed for the presence of infectious PCV2. Virus titres were determined by performing a 50% tissue culture infective dose assay (TCID(50)) by end point dilution and with the use of an indirect peroxidise monolayer assay technique. With an initial infectious virus titre of 3.25-3.82 (TCID(50))/50μL the two-step sperm selection method eliminated 2.92±0.23 logs of infectious PCV2, corresponding to more than 99% reduction. Sperm quality was not affected by the selection procedure.     

TGF-β1 modifications in nuclear matrix proteins of osteoblasts during differentiation

Nuclear matrix protein (NMP) composition of osteoblasts shows distinct two-dimensional gel electrophoretic profiles of labeled proteins as a function of stages of cellular differentiation. Because NMPs are involved in the control of gene expression, we examined modifications in the representation of NMPs induced by TGF-β1 treatment of osteoblasts to gain insight into the effects of TGF-β on development of the osteoblast phenotype. Exposure of proliferating fetal rat calvarial derived primary cells in culture to TGF-β1 for 48 h (day 4–6) modifies osteoblast cell morphology and proliferation and blocks subsequent formation of mineralized nodules. Nuclear matrix protein profiles were very similar between control and TGF-β–treated cultures until day 14, but subsequently differences in nuclear matrix proteins were apparent in TGF-β–treated cultures. These findings support the concept that TGF-β1 modifies the final stage of osteoblast mineralization and alters the composition of the osteoblast nuclear matrix as reflected by selective and TGF-β–dependent modifications in the levels of specific nuclear matrix proteins. The specific changes induced by TGF-β in nuclear matrix associated proteins may reflect specialized mechanisms by which TGF-β signalling mediates the alterations in cell organization and nodule formation and/or the consequential block in extracellular mineralization. J. Cell. Biochem. 69:291–303, 1998. © 1998 Wiley-Liss, Inc.     

The Wnt antagonist secreted frizzled-related protein-1 is a negative regulator of trabecular bone formation in adult mice

Previous studies have associated activation of canonical Wnt signaling in osteoblasts with elevated bone formation. Here we report that deletion of the murine Wnt antagonist, secreted frizzled-related protein (sFRP)-1, prolongs and enhances trabecular bone accrual in adult animals. sFRP-1 mRNA was expressed in bones and other tissues of +/+ mice but was not observed in -/- animals. Despite its broad tissue distribution, ablation of sFRP-1 did not affect blood and urine chemistries, most nonskeletal organs, or cortical bone. However, sFRP-1-/- mice exhibited increased trabecular bone mineral density, volume, and mineral apposition rate when compared with +/+ controls. The heightened trabecular bone mass of sFRP-1-/- mice was observed in adult animals between the ages of 13-52 wk, occurred in multiple skeletal sites, and was seen in both sexes. Mechanistically, loss of sFRP-1 reduced osteoblast and osteocyte apoptosis in vivo. In addition, deletion of sFRP-1 inhibited osteoblast lineage cell apoptosis while enhancing the proliferation and differentiation of these cells in vitro. Ablation of sFRP-1 also increased osteoclastogenesis in vitro, although changes in bone resorption were not observed in intact animals in vivo. Our findings demonstrate that deletion of sFRP-1 preferentially activates Wnt signaling in osteoblasts, leading to enhanced trabecular bone formation in adults.     

Paleocene benthonic foraminiferal biostratigraphy,paleobiogeography and paleoecology of Atlantic—Tethyan regions: Midway-type fauna

The stratigraphic, geographic and bathymetric distribution of some Paleocene benthonic foraminiferal assemblages have been studied in the Tethyan and circum-Atlantic regions within the framework of planktonic foraminiferal zones. Although some species appear to be restricted to either the Tethyan-European area or to the western Atlantic, the majority of species are amphi-Atlantic and Tethyan in distribution. The cosmopolitan distribution is attributed to more equitable climatic conditions (lower polar—equatorial thermal gradient) and warmer, more uniform thermal structure of the oceans and different paleogeographic and paleo-oceanographic conditions.Two main distinct depth-controlled benthonic foraminiferal assemblages (exclusive of the shallow-warm water Tethyan carbonate assemblage) have been recognized in the Paleocene. The continental shelf fauna, termed here the “Midway-type fauna” (MF) is characterized by species of Cibicidoides alleni (Plummer) = propria Brotzen, howelli (Toulmin), succedens (Brotzen), Anomalinoides [acuta (Plummer), midwayensis (Plummer)], Gavelinella [danica (Brotzen), neelyi (Jennings)], and Osangularia plummerae Brotzen, as well as various lagenids (nodosariids, lenticulinids, vaginulinids), polymorphinids and textulariids. A lower continental slope and abyssal plain fauna, termed here the “Velasco-type fauna” (VF), is characterized by, amongst others, Gavalinella [beccariiformis (White), rubiginosa (Cushman), velascoensis (Cushman)], Nuttallides truempy (Nuttall), Nuttallinella florealis (Cushman), velascoensisZ (Cushman)], (Cushman), Aragonia velascoensis (Cushman), nodosariids (N. velascoensis Cushman, Dentalina limbata d'Orbigny), various agglutinated forms [Gaudryina pyramidata Cushman, Tritaxia aspera (Cushman), Dorothia ex. gr. oxycona trinitatensis (Cushman and Renz)], and various gyroidinids and buliminids. Pleuriostomellids and stilostomellids are quantitatively rare and unimportant until the Middle—Late Eocene.This paper discusses the biostratigraphy and biogeography of the “Midway-type fauna”.     

Inhibitory effects of Eucalyptus globulus on understorey plant growth and species richness are greater in non‐native regions

Aim

We studied the novel weapons hypothesis in the context of the broadly distributed tree species Eucalyptus globulus. We evaluated the hypothesis that this Australian species would produce stronger inhibitory effects on species from its non‐native range than on species from its native range.

Location

We worked in four countries where this species is exotic (U.S.A., Chile, India, Portugal) and one country where it is native (Australia).

Time period

2009–2012.

Major taxa studied

Plants.

Methods

We compared species composition, richness and height of plant communities in 20 paired plots underneath E. globulus individuals and open areas in two sites within its native range and each non‐native region. We also compared effects of litter leachates of E. globulus on root growth of seedlings in species from Australia, Chile, the U.S.A. and India.

Results

In all sites and countries, the plant community under E. globulus canopies had lower species richness than did the plant community in open areas. However, the reduction was much greater in the non‐native ranges: species richness declined by an average of 51% in the eight non‐native sites versus 8% in the two native Australian sites. The root growth of 15 out of 21 species from the non‐native range were highly suppressed by E. globulus litter leachates, whereas the effect of litter leachate varied from facilitation to suppression for six species native to Australia. The mean reduction in root growth for Australian plants was significantly lower than for plants from the U.S.A., Chile and India.

Main conclusions

Our results show biogeographical differences in the impact of an exotic species on understorey plant communities. Consistent with the novel weapons hypothesis, our findings suggest that different adaptations of species from the native and non‐native ranges to biochemical compounds produced by an exotic species may play a role in these biogeographical differences.     

Hydroxyurea Use and Hospitalization Trends in a Comprehensive Pediatric Sickle Cell Program

Background

A decline in hospitalizations and pain episodes among those with sickle cell disease (SCD) who take hydroxyurea (HU) has been shown when compared to pre-HU patterns but paradoxically, when compared to those who have never been treated, HU recipients often have more frequent hospitalizations. This analysis evaluates the impact of increasing usage of HU on trends in hospitalizations and blood transfusions within a large SCD treatment program.

Methods

Eligibility was restricted to patients with Hb SS or Hb Sβ⁰-thalassemia who were 2–18 years old between 2006–2010 and received care at St. Jude Children''s Research Hospital (N = 508). Hospitalizations and blood transfusions were calculated for each of the years under study for those exposed and never exposed to HU. Differences in number of hospitalizations before and after HU initiation were compared.

Results

The proportion of patients receiving HU increased by 4% per year on average. In the HU exposed group, a modest decline in mean per-patient hospitalizations and per-patient hospital days occurred, while those never exposed to HU trended toward a slight increase over time. Rates of blood transfusions declined among those on HU but not in patients never exposed to HU. Patients on HU had a median of one fewer hospital admission in the year after initiation of HU, compared to the year prior. Two deaths occurred in the patient population, both of whom were not exposed to HU.

Conclusions

Increasing usage of HU was concurrent with decreased hospitalization rates and blood transfusions. Our results support the utility of HU on decreasing hospitalizations and transfusions for patients with SCD outside of the clinical trial setting.