Androgen-induced mineralization by MC3T3-E1 osteoblastic cells reveals a critical window of hormone responsiveness

Despite their clinical importance for skeletal growth and homeostasis, the actions of androgens on osteoblastic cells are not well understood. MC3T3-E1 cells, a nontransformed murine preosteoblastic cell line, that traverse the stages of osteoblastic differentiation within 30 days in vitro, were exposed to mibolerone (an androgen receptor (AR) agonist) or 5alpha-dihydroxytestosterone (DHT) from days 3 to 30 post-plating. Cells exposed to this hormonal regimen exhibited a significant increase in mineralization (calcium deposition) compared to vehicle-treated cells. Delaying treatment for 4-11 days (treatment still completed on day 30 post-plating) enhanced mineralization further. Within 2 days post-plating, AR protein increased 7.2-fold in androgen-treated cells and 2.5-fold in vehicle-treated cells. MC3T3-E1 cells transfected with an androgen- and glucocorticoid-responsive reporter construct on day 1 post-plating followed by a 2 day exposure to DHT, mibolerone, or dexamethasone (dex; a glucocorticoid receptor agonist) exhibited reporter gene activation only with dex treatment. In contrast, delaying transfection and treatment for at least 1 day resulted in comparable androgen- and dex-mediated reporter gene transactivation. Therefore, the ability of MC3T3-E1 cells to respond to androgens is dependent on the timing of androgen administration.     

"In vitro" protection of DNA from Fenton reaction by plant polyphenol verbascoside

The protection effect of verbascoside (Ver) against Fenton reaction on plasmid pBR322 DNA was studied using agarose gel electrophoresis and UV-visible spectroscopy. The pBR322 plasmid DNA is damaged by hydroxyl radical (OH*) generated from the Fenton reaction with H2O2 and Fe(II) or Fe(III). This DNA damage is characterized by the diminution of supercoiled DNA forms or by the increase of relaxed or linear DNA forms after oxidative attack. The UV spectrum study showed that verbascoside can form complexes with Fe(II) or Fe(III), and the complexation can be reversed by the addition of EDTA. The formation constants of verbascoside-Fe complexes were estimated as 10(21.03) and 10(31.94) M(-2) for Fe(II) and Fe(III) respectively. The inhibition of Fenton reaction by verbascoside could be partially explained by the sequestration of Fe ions.     

UNC-98 and UNC-96 interact with paramyosin to promote its incorporation into thick filaments of Caenorhabditis elegans

Mutations in unc-96 or -98 cause reduced motility and a characteristic defect in muscle structure: by polarized light microscopy birefringent needles are found at the ends of muscle cells. Anti-paramyosin stains the needles in unc-96 and -98 mutant muscle. However there is no difference in the overall level of paramyosin in wild-type, unc-96, and -98 animals. Anti-UNC-98 and anti-paramyosin colocalize in the paramyosin accumulations of missense alleles of unc-15 (encodes paramyosin). Anti-UNC-96 and anti-UNC-98 have diffuse localization within muscles of unc-15 null mutants. By immunoblot, in the absence of paramyosin, UNC-98 is diminished, whereas in paramyosin missense mutants, UNC-98 is increased. unc-98 and -15 or unc-96 and -15 interact genetically either as double heterozygotes or as double homozygotes. By yeast two-hybrid assay and ELISAs using purified proteins, UNC-98 interacts with paramyosin residues 31-693, whereas UNC-96 interacts with a separate region of paramyosin, residues 699-798. The importance of surface charge of this 99 residue region for UNC-96 binding was shown. Paramyosin lacking the C-terminal UNC-96 binding region fails to localize throughout A-bands. We propose a model in which UNC-98 and -96 may act as chaperones to promote the incorporation of paramyosin into thick filaments.     

Regulating inflammation through the anti-inflammatory enzyme platelet-activating factor-acetylhydrolase

Platelet-activating factor (PAF) is one of the most potent lipid mediators involved in inflammatory events. The acetyl group at the sn-2 position of its glycerol backbone is essential for its biological activity. Deacetylation induces the formation of the inactive metabolite lyso-PAF. This deacetylation reaction is catalyzed by PAF-acetylhydrolase (PAF-AH), a calcium independent phospholipase A2 that also degrades a family of PAF-like oxidized phospholipids with short sn-2 residues. Biochemical and enzymological evaluations revealed that at least three types of PAF-AH exist in mammals, namely the intracellular types I and II and a plasma type. Many observations indicate that plasma PAF AH terminates signals by PAF and oxidized PAF-like lipids and thereby regulates inflammatory responses. In this review, we will focus on the potential of PAF-AH as a modulator of diseases of dysregulated inflammation.     

Functions of the segment polarity genes midline and H15 in Drosophila melanogaster neurogenesis

The Drosophila melanogaster ventral nerve cord derives from neural progenitor cells called neuroblasts. Individual neuroblasts have unique gene expression profiles and give rise to distinct clones of neurons and glia. The specification of neuroblast identity provides a cell intrinsic mechanism which ultimately results in the generation of progeny which are different from each other. Segment polarity genes have a dual function in early neurogenesis: within distinct regions of the neuroectoderm, they are required both for neuroblast formation and for the specification of neuroblast identity. Previous studies of segment polarity gene function largely focused on neuroblasts that arise within the posterior part of the segment. Here we show that the segment polarity gene midline is required for neuroblast formation in the anterior-most part of the segment. Moreover, midline contributes to the specification of anterior neuroblast identity by negatively regulating the expression of Wingless and positively regulating the expression of Mirror. In the posterior-most part of the segment, midline and its paralog, H15, have partially redundant functions in the regulation of the NB marker Eagle. Hence, the segment polarity genes midline and H15 play an important role in the development of the ventral nerve cord in the anterior- and posterior-most part of the segment.     

Collapse of an avifauna: climate change appears to exacerbate habitat loss and degradation

Aim  We characterized changes in reporting rates and abundances of bird species over a period of severe rainfall deficiency and increasing average temperatures. We also measured flowering in eucalypts, which support large numbers of nectarivores characteristic of the region.
Location  A 30,000-km² region of northern Victoria, Australia, consisting of limited amounts of remnant native woodlands embedded in largely agricultural landscapes.
Methods  There were three sets of monitoring studies, pitched at regional (survey programmes in 1995–97, 2004–05 and 2006–08), landscape (2002–03 and 2006–07) and site (1997–2008 continuously) scales. Bird survey techniques used a standard 2-ha, 20-min count method. We used Bayesian analyses of reporting rates to document statistically changes in the avifauna through time at each spatial scale.
Results  Bird populations in the largest remnants of native vegetation (up to 40,000 ha), some of which have been declared as national parks in the past decade, experienced similar declines to those in heavily cleared landscapes. All categories of birds (guilds based on foraging substrate, diet, nest site; relative mobility; geographical distributions) were affected similarly. We detected virtually no bird breeding in the latest survey periods. Eucalypt flowering has declined significantly over the past 12 years of drought.
Main conclusions  Declines in the largest woodland remnants commensurate with those in cleared landscapes suggest that reserve systems may not be relied upon to sustain species under climate change. We attribute population declines to low breeding success due to reduced food. Resilience of bird populations in this woodland system might be increased by active management to enhance habitat quality in existing vegetation and restoration of woodland in the more fertile parts of landscapes.     

Total syntheses of iso-, neuro- and phytoprostanes: new insight in lipid chemistry

Isoprostanes (IsoPs) are a complex family of compounds produced, in vivo, from peroxidation of polyunsaturated fatty acids (AA, DHA, EPA, alpha-linolenic) via a free-radical-catalyzed mechanism. Carbocyclic annulations are extremely important reactions and the stereocontrolled intramolecular free-radical cyclization has emerged as a powerful tool for carbon-carbon bond formation in synthetic chemistry. The hex-5-enyl radical cyclization is the most well-known for the synthesis of cyclopentane rings. After a short review of the literature, concerning the total synthesis of isoprostanes and intermediates, we will present our own contributions on the preparation of chiral cyclopentane rings from glucose leading to new isoprostanes. This study allowed us to control the cyclization outcome to yield the all-syn and/or syn-anti-syn precursors which permit us to the total synthesis of a large set of iso-, neuro-, and phytoprostanes.     

Structural investigation of the capsular polysaccharide of Klebsiella serotype k23

Klebsiella K23 capsular polysaccharide has been investigated by the techniques of hydrolysis, methylation, Smith degradation-periodate oxidation, and base-catalysed degradation, either on the original or the carboxyl-reduced polysaccharide. The structure was found to consist of a tetrasaccharide repeating-unit, as shown below. The anomeric configurations of the sugar residues were determined by ₁H-and ¹³C-n.m.r. spectroscopy on the original and degraded polysaccharides.

     

Influence of the blood concentration of prolactin on the length of the sensitive period for establishing maternal behavior in sheep at parturition

The fading of postpartum maternal interest for the neonate (sensitive period) in ewes separated from their young at lambing is delayed when parturition is induced with 20 mg of estradiol benzoate (EB). An experiment was carried out to investigate the role of prolactin in this phenomenon. The sensitive period was studied in three groups of parturient ewes. In all groups lambs were removed at birth and reintroduced to their mothers 24 hr later. Maternal acceptance was tested at this time. In group 1 (dexamethasone D), ewes were induced to lamb with dexamethasone (15 mg im). In group 2 (EB), ewes were treated with 20 mg of estradiol benzoate (im). In group 3 (EB + CB 154) ewes received 20 mg of EB as in group 2 and 1 mg of CB 154 (sc) every 12 hr to prevent the enhanced secretion of prolactin which normally occurs after EB injection. The concentration of prolactin was highest in group 2 (EB), lowest in group 3 (EB + CB), and intermediate in group 1 (D) (p ? 0.001 between groups). By contrast, the proportion of ewes showing maternal behavior was similar in groups 2 and 3 ($\text{15}\text{23}$ and $\text{17}\text{22}$), both of which differed from group 1 ($\text{3}\text{22}\text{; p ? 0.005}$). It is concluded that the lengthening of the sensitive period for establishing maternal behavior in sheep following EB induced parturition is not related with high levels of prolactin in the peripheral circulation.     

Mitochondrial fragmentation in neurodegeneration

Mitochondria are remarkably dynamic organelles that migrate, divide and fuse. Cycles of mitochondrial fission and fusion ensure metabolite and mitochondrial DNA mixing and dictate organelle shape, number and bioenergetic functionality. There is mounting evidence that mitochondrial dysfunction is an early and causal event in neurodegeneration. Mutations in the mitochondrial fusion GTPases mitofusin 2 and optic atrophy 1, neurotoxins and oxidative stress all disrupt the cable-like morphology of functional mitochondria. This results in impaired bioenergetics and mitochondrial migration, and can trigger neurodegeneration. These findings suggest potential new treatment avenues for neurodegenerative diseases.