Pollination Ecophysiology of Mercurialis annua L. (Euphorbiaceae), an Anemophilous Species Flowering all Year Round

Mercurialis annua L. is a dioecious anemophilous species thatflowers all year round in central and southern Italy. The flowersof both sexes are dimorphic: the female flower has a vestigialcalyx; the male flower consists only of a calyx that opens atanthesis. The anthers always dehisce after anthesis. The anthesisof male flowers seems to be temperature dependent, whereas antherdehiscence is related to relative humidity. The pollen grainsvary in volume according to the season: they are smaller whenrelative humidity is low and vice versa. They always decreasein volume after anther dehiscence and have the capacity to varyin volume and reach equilibrium with a changing environment.Viability is high, but may drop suddenly during heavy rain orhail that damage the exposed male flowers. The number of pollengrains per stigma varies from 0 to 300. The data is discussedin relation to the type of pollination and environmental characteristics.Copyright1994, 1999 Academic Press Mercurialis annua, dioecism, anthesis, anther dehiscence, pollen volume, pollen viability, anemophilous pollination, pollination ecology     

Preferred conformation of peptides rich in Ac8c,a medium-ring alicyclic Cα,α-disubstituted glycine

A complete series of terminally blocked, monodispersed homo-oligopeptides (to the pentamer level) from the sterically demanding, medium-ring alicyclic C^α,α-disubstituted glycine 1-aminocyclooctane-1-carb oxylic acid (Ac₈c), and two Ala/Ac₈c tripeptides, were synthesized by solution methods and fully characterized. The preferred conformation of all the oligopeptides was determined in deuterochloroform solution by IR absorption and ¹H-NMR. The molecular structures of the amino acid derivative Z-Ac₈c-OH, the dipeptide pBrBz- (Ac₈c)₂-OH and the tripeptide pBrBz-(Ac₈c)₃-OtBu were assessed in the crystal state by X-ray diffraction. Conformational energy computations were performed on the monopeptide Ac-Ac₈c-NHMe. Taken together, the results obtained strongly support the view that the Ac₈c residue is an effective β-turn and helix former. A comparison is also made with the conformational preferences of α-aminoisobutyric acid, the prototype of C^{α, α}-disubstituted glycines, and of the other members of the family of 1-aminocycloalkane-1-carboxylic acids (Ac_nc, with n=3, 5–7) investigated so far. The implications for the use of the Ac₈c residue in peptide conformational design are considered.     

Linear oligopeptides: 65′. Conformational analysis of the N-protected aromatic α-amino acid N-tert-butyloxycarbonyl-l-phenylalanine by X-ray diffraction and infrared absorption

The X-ray diffraction and i.r. absorption conformational analysis of $\text{N}\text{-tert-butyloxycarbonyl-}\text{l}\text{-phenylalanine}$ has showed the absence of intramolecularly hydrogen-bonded peptide conformations in the solid state. The molecules are held together in rows of ‘cyclic dimer’ motifs through intermolecular NH … OC (acid) and OH … OC {urethane} hydrogen bonds, the secondary amide-like group of the urethane moiety being in the unusual cis conformation, whereas the carboxylic acid group in the common syn conformation. The two molecules in the unit cell present a centrosymmetric set of ?, ψ¹, and ψ² values. In polar solvents solvated species largely predominate. In saturated hydrocarbon solution non-associated and associated (mostly involving the carboxylic acid CO as the proton acceptor) species simultaneously occur. The extent of association decreases with dilution. The amount of intramolecularly hydrogen-bonded oxy-C₇ and C₅ forms if any, should be extremely small. The type of association at saturation seems to differ from that found in the crystalline compound obtained by precipitation with saturated aliphatic hydrocarbons (from a diethyl ether solution).     

Collagen and elastin in rabbit fetal lung: ontogeny and effects of steroids.

Ontogeny of lung collagen and elastin were studied in fetal rabbit from day 25 to term. Collagen (isolated by hot trichloroacetic acid treatment) and elastin (contained in the residue) were hydrolyzed and the hydroxyproline and desmosine quantitated by hplc. Hydroxyproline slightly increased from day 25 to day 30 (204 to 244 micrograms/100g dry weight). Over the same period desmosine increased from 2.2 to 5.1 micrograms/100 mg dry weight (P < 0.01). The effect of antenatal corticosteroids on the lung of prematurely-delivered fetuses was also evaluated. Betamethasone (B) was given to pregnant does at a dose of 0.2 mg/kg 24 and 48 h before delivery of the fetuses at 26, 27 and 28 days. In treated animals elastin concentration increased significantly by about 22% on day 26 (P = 0.05), by 29% on day (P < 0.02) and by 47% on day 28 (P < 0.02). Hydroxyproline was not affected by steroid treatment at any gestational age. This suggests that steroids affect fetal lung development also via changes in connective tissue.     

NMR studies of prebiotic polypeptides

Several polypeptides prepared by means of pyrocondensation have been the subject of structural investigations. Attention has been focused on the constitutional characterization of homo-and co-polymers containing Asp and Glu residues, whose role is essential for the formation of the so-called proteinoids. Contrary to the literature data based on chemical degradation, nmr studies show conclusively that in thermal poly-aspartic acid only β-peptide linkages are present. This result casts serious doubt on the role thermal condensation might have played in prebiotic polypeptide syntheses.     

Mycophenolate mofetil versus azathioprine in kidney transplant recipients on steroid-free,low-dose cyclosporine immunosuppression (ATHENA): A pragmatic randomized trial

BackgroundWe compared protection of mycophenolate mofetil (MMF) and azathioprine (AZA) against acute cellular rejection (ACR) and chronic allograft nephropathy (CAN) in kidney transplant recipients on steroid-free, low-dose cyclosporine (CsA) microemulsion maintenance immunosuppression.Methods and findingsATHENA, a pragmatic, prospective, multicenter trial conducted by 6 Italian transplant centers, compared the outcomes of 233 consenting recipients of a first deceased donor kidney transplant induced with low-dose thymoglobulin and basiliximab and randomized to MMF (750 mg twice/day, n = 119) or AZA (75 to 125 mg/day, n = 114) added-on maintenance low-dose CsA microemulsion and 1-week steroid. In patients without acute clinical or subclinical rejections, CsA dose was progressively halved. Primary endpoint was biopsy-proven CAN. Analysis was by intention to treat.Participants were included between June 2007 and July 2012 and followed up to August 2016. Between-group donor and recipient characteristics, donor/recipient mismatches, and follow-up CsA blood levels were similar. During a median (interquartile range (IQR)) follow-up of 47.7 (44.2 to 48.9) months, 29 of 87 biopsied patients on MMF (33.3%) versus 31 of 88 on AZA (35.2%) developed CAN (hazard ratio (HR) [95% confidence interval (CI)]: 1.147 (0.691 to 1.904, p = 0.595). Twenty and 21 patients on MMF versus 34 and 14 on AZA had clinical [HR (95% CI): 0.58 (0.34 to 1.02); p = 0.057) or biopsy-proven subclinical [HR (95% CI): 1.49 (0.76 to 2.92); p = 0.249] ACR, respectively. Combined events [HR (95% CI): 0.85 (0.56 to 1.29); p = 0.438], patient and graft survival, delayed graft function (DGF), 3-year glomerular filtration rate (GFR) [53.8 (40.6;65.7) versus 49.8 (36.8;62.5) mL/min/1.73 m², p = 0.50], and adverse events (AEs) were not significantly different between groups.Chronicity scores other than CAN predict long-term graft outcome. Study limitations include small sample size and unblinded design.ConclusionsIn this study, we found that in deceased donor kidney transplant recipients on low-dose CsA and no steroids, MMF had no significant benefits over AZA. This finding suggests that AZA, due to its lower costs, could safely replace MMF in combination with minimized immunosuppression.Trial registrationClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00494741","term_id":"NCT00494741"}}NCT00494741; EUDRACT 2006-005604-14.

Piero Ruggenenti and co-workers study maintenance immunosuppression in deceased-donor kidney transplantation.     

Effect of positive charges in the structural interaction of crabrolin isoforms with lipopolysaccharide

Antimicrobial peptides (AMPs) appear as chemical compounds of increasing interest for their role in killing bacteria and, more recently, for their ability to bind endotoxin (lipopolysaccharide, LPS) that is released during bacterial infection and that may lead to septic shock. This dual role in the mechanism of action can further be enhanced in a synergistic way when two or more AMPs are combined together. Not all AMPs are able to bind LPS, suggesting that several modes of binding to the bacterial surface may exist. Here we analyze a natural AMP, crabrolin, and two mutated forms, one with increased positive charge (Crabrolin Plus) and the other with null charge (Crabrolin Minus), and compare their binding abilities to LPS. While Crabrolin WT as well Crabrolin Minus do not show binding to LPS, the mutated Crabrolin Plus exhibits binding and forms a well defined structure in the presence of LPS. The results strengthen the importance of positive charges for the binding to LPS and suggest the mutated form with increased positive charge as a promising candidate for antimicrobial and antiseptic activity.     

Breeding systems in two species of the genus Helleborus (Ranunculaceae)

ABSTRACT

The results of various types of manual and free pollination are reported in Helleborus bocconei and Helleborus foetidus, two sympatric species of the understorey of submediterranean woods that flower in January–March and are pollinated by bumble-bees of the genus Bombus. Both species were found to be partially self-compatible even if at different rates; geitonogamy seems to be more frequent in H. foetidus and spontaneous self-pollination does not usually occur for morphological reasons, and the species are not apomictic. Efficiency in seed production after free pollination was very high indicating that in spite of harsh climatic condition, there were no limitations imposed by pollen or pollinators.     

CARD14/CARMA2sh and TANK differentially regulate poly(I:C)–induced inflammatory reaction in keratinocytes

CARD14/CARMA2sh (CARMA2sh) is a scaffold protein whose mutations are associated with the onset of human genetic psoriasis and other inflammatory skin disorders. Here we show that the immunomodulatory adapter protein TRAF family member-associated NF-κB activator (TANK) forms a complex with CARMA2sh and MALT1 in a human keratinocytic cell line. We also show that CARMA2 and TANK are individually required to activate the nuclear factor κB (NF-κB) response following exposure to polyinosinic-polycytidylic (poly [I:C]), an agonist of toll-like receptor 3. Finally, we present data indicating that TANK is essential for activation of the TBK1/IRF3 pathway following poly (I:C) stimulation, whereas CARMA2sh functions as a repressor of it. More important, we report that two CARMA2sh mutants associated with psoriasis bind less efficiently to TANK and are therefore less effective in suppressing the TBK1/IRF3 pathway. Overall, our data indicate that TANK and CARMA2sh regulate TLR3 signaling in human keratinocytes, which could play a role in the pathophysiology of psoriasis.