Variation in pituitary expression of mRNAs encoding the putative inhibin co-receptor (betaglycan) and type-I and type-II activin receptors during the chicken ovulatory cycle

Secretion of LH and FSH from the anterior pituitary is regulated primarily by hypothalamic GnRH and ovarian steroid hormones. More recent evidence indicates regulatory roles for certain members of the transforming growth factor beta (TGF beta) superfamily including inhibin and activin. The aim of this study was to identify expression of mRNAs encoding key receptors and ligands of the inhibin/activin system in the hen pituitary gland and to monitor their expression throughout the 24-25-h ovulatory cycle. Hens maintained on long days (16 h light/8 h dark) were killed 20, 12, 6 and 2 h before predicted ovulation of a midsequence egg (n = 8 per group). Anterior pituitary glands were removed, RNA extracted and cDNA synthesized. Plasma concentrations of LH, FSH, progesterone and inhibin A were measured. Real-time quantitative PCR was used to quantify pituitary expression of mRNAs encoding betaglycan, activin receptor (ActR) subtypes (type I, IIA), GnRH receptor (GnP,H-R), LH beta subunit, FSH beta subunit and GAPDH. Levels of mRNA for inhibin/activin beta A and beta B subunits, inhibin alpha subunit, follistatin and ActRIIB mRNA in pituitary were undetectable by quantitative PCR (< 2 amol/reaction). Significant changes in expression (P < 0.05) of ActRIIA and betaglycan mRNA were found, both peaking 6 h before ovulation just prior to the preovulatory LH surge and reaching a nadir 2 h before ovulation, just after the LH surge. There were no significant changes in expression of ActRI mRNA throughout the cycle although values were correlated with mRNA levels for both ActRIIA (r=0.77; P < 0.001) and betaglycan (r=0.45; P < 0.01). Expression of GnRH-R mRNA was lowest 20 h before ovulation and highest (P < 0.05) 6 h before ovulation; values were weakly correlated with betaglycan (r=0.33; P=0.06) and ActRIIA (r=0.34; P=0.06) mRNA levels. Expression of mRNAs encoding LH beta and FSH beta subunit were both lowest (P < 0.05) after the LH surge, 2 h before ovulation. These results are consistent with an endocrine, but not a local intrapituitary, role of inhibin-related proteins in modulating gonadotroph function during the ovulatory cycle of the hen, potentially through interaction with betaglycan and ActRIIA. In contrast to mammals, intrapituitary expression of inhibin/activin subunits and follistatin appears to be extremely low or absent in the domestic fowl.

Formation of isopolyoxometallate(VI) anions in the reaction between M(CO)6 (M = W, Mo) and acetic acid: X-ray crystal structure of [W3(μ3-O)2(μ2η2-O2CCH3)6(H2O)3]2[W10O32·solvent

W(CO)6 reacts with a mixture of acetic acid/acetic anhydride to give [W3 (μ3-O)2(μ2η2-O2CCH3)6(H2O)3](CH3CO2)2 (1), which was converted by HClO4 to [W3 (μ3-O)2(μ2η2-O2CCH3)6(H2O)3](ClO4)2 (2). Addition of CH3CO2Na to the above reaction mixture, and prolonged exposure of the solution to air, results in the formation of the WIV/WVI complex salt [W3(μ3-O)2(μ2η2-O2CCH3)6(H2O)3]2[W10O32]·solvent (3). Complex 3 was also prepared by reacting 1 with Na2WO4·2H2O in acetic acid, and it has been characterized by X-ray crystallography. Addition of [CH3(CH2)3]4N(ClO4) to the reaction filtrate remaining after the preparation of [Mo2(μ-O2CCH3)4][from Mo(CO)6, CH3CO2H and (CH3CO)2O], followed by exposure to air, gives ([CH3(CH2)3]4N)2[Mo6O19] (4).

Reaction of (±)-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate {(±)-phosH} with copper(II), cobalt(II) and iron(II) compounds; Identification by x-ray diffraction of [Co(CH3OH)4(H2O)2][(+)-phos][(−)-phos]. 2CH3OH·H2O

[Cu2(μO2CCH3)4(H2O)2], [CuCO3·Cu(OH)2], [CoSO4·7H2O], [Co((+)-tartrate)], and [FeSO4·7H2O] react with excess racemic (±)- 1,1′-binaphthyl-2,2′-diyl hydrogen phosphate {(±)-PhosH} to give mononuclear CuII, CoII and FeII products. The cobalt product, [Co(CH3OH)4(H2O)2]((+)-Phos)((−)-Phos) ·2CH3OH·H2O (7), has been identified by X-ray diffraction. The high-spin, octahedral CoII atom is ligated by four equatorial methanol molecules and two axial water molecules. A (+)- and a (−)-Phos− ion are associated with each molecule of the complex but are not coordinated to the metal centre. For the other CoII, CuII and FeII samples of similar formulation to (7) it is also thought that the Phos− ions are not bonded directly to the metal. When some of the CuII and CoII samples are heated under high vacuum there is evidence that the Phos− ions are coordinated directly to the metals in the products.

Metal cluster expansion by addition of low valent group 14 reagents: III. Reaction of bis[bis(trimethylsilyl)methyl]tin with M3(CO)12 or its derivatives (M = Fe, Ru, or Os): the crystal and molecular structures of M3(μ-SnR2)2(CO)10(R = CH(SiMe3)2; M = Ru or Os)

The stannylene [SnR2] (R = CH(SiMe3)2) reacts in different ways with the three dodecacarbonyls of the iron triad: [Fe3(CO)12] gives [Fe2(CO)8(μ-SnR2)], [Ru3(CO)12] gives the planar pentametallic cluster [Ru3(CO)10(μ-SnR2)2], for which a full structural analysis is reported, while [Os3(CO)12] fails to react. Different products are also obtained from three nitrile derivatives: [Fe3-(CO)11(MeCN)] gives [Fe2(CO)6(μ-SnR2)2], which has a structure significantly different from that of known Fe2Sn2 clusters, [Ru3(CO)10(MeCN)2] gives the pentametallic cluster described above, while [Os3(CO)10(MeCN)2] gives the isostructural osmium analogue, which shows the unusual feature of a CO group bridging two osmium atoms.

Crystal design approaches for the synthesis of paracetamol co-crystals

Crystal engineering principles were used to design three new co-crystals of paracetamol. A variety of potential cocrystal formers were initially identified from a search of the Cambridge Structural Database for molecules with complementary hydrogen-bond forming functionalities. Subsequent screening by powder X-ray diffraction of the products of the reaction of this library of molecules with paracetamol led to the discovery of new binary crystalline phases of paracetamol with trans-1,4- diaminocyclohexane (1); trans-1,4-di(4-pyridyl)ethylene (2); and 1,2-bis(4-pyridyl)ethane (3). The co-crystals were characterized by IR spectroscopy, differential scanning calorimetry, and 1H NMR spectroscopy. Single crystal X-ray structure analysis reveals that in all three co-crystals the co-crystal formers (CCF) are hydrogen bonded to the paracetamol molecules through O−H···N interactions. In co-crystals (1) and (2) the CCFs are interleaved between the chains of paracetamol molecules, while in co-crystal (3) there is an additional N−H···N hydrogen bond between the two components. A hierarchy of hydrogen bond formation is observed in which the best donor in the system, the phenolic O−H group of paracetamol, is preferentially hydrogen bonded to the best acceptor, the basic nitrogen atom of the co-crystal former. The geometric aspects of the hydrogen bonds in co-crystals 1−3 are discussed in terms of their electrostatic and charge-transfer components.

Spectroelectrochemical study of complexes [Mo(CO)2(h3-allyl)(adiimine)(NCS)] (a-diimine ¼ bis(2,6-dimethylphenyl)- acenaphthenequinonediimine and 2,20-bipyridine) exhibiting different molecular structure and redox reactivity

The redox properties and reactivity of [Mo(CO)2(η3-allyl)(α-diimine)(NCS)] (α-diimine = bis(2,6-dimethylphenyl)-acenaphthenequinonediimine (2,6-xylyl-BIAN) and 2,2′-bipyridine (bpy)) were studied using cyclic voltammetry and IR/UV–Vis spectroelectrochemistry. [Mo(CO)2(η3-allyl)(2,6-xylyl-BIAN)(NCS)] was shown by X-ray crystallography to have an asymmetric (B-type) conformation. The extended aromatic system of the strong π-acceptor 2,6-xylyl-BIAN ligand stabilises the primary 1e−-reduced radical anion, [Mo(CO)2(η3-allyl)(2,6-xylyl-BIAN•−)(NCS)]−, that can be reduced further to give the solvento anion [Mo(CO)2(η3-allyl)(2,6-xylyl-BIAN)(THF)]−. The initial reduction of [Mo(CO)2(η3-allyl)(bpy)(NCS)] in THF at ambient temperature results in the formation of [Mo(CO)2(η3-allyl)(bpy)]2 by reaction of the remaining parent complex with [Mo(CO)2(η3-allyl)(bpy)]− produced by dissociation of NCS− from [Mo(CO)2(η3-allyl)(bpy•−)(NCS)]−. Further reduction of the dimer [Mo(CO)2(η3-allyl)(bpy)]2 restores [Mo(CO)2(η3-allyl)(bpy)]−. In PrCN at 183 K, [Mo(CO)2(η3-allyl)(2,6-xylyl-BIAN•−)(NCS)]− converts slowly to 2e−-reduced [Mo(CO)2(η3-allyl)(2,6-xylyl-BIAN)(PrCN)]− and free NCS−. At room temperature, the reduction path in PrCN involves mainly the dimer [Mo(CO)2(η3-allyl)(bpy)]2; however, the detailed course of the reduction within the spectroelectrochemical cell is complicated and involves a mixture of several unassigned products. Finally, it has been shown that the five-coordinate anion [Mo(CO)2(η3-allyl)(bpy)]− promotes in THF reduction of CO2 to CO and formate via the formation of the intermediate [Mo(CO)2(η3-allyl)(bpy)(O2CH)] and its subsequent reduction.