NMR evidence for perturbation of the copper coordination sphere upon chemical modification of arginine 141 in bovine Cu,Zn superoxide dismutase.

The reaction of the Cu,Co derivative of bovine Cu,Zn superoxide dismutase with phenylglyoxal or butanedione, which are known to inactivate the enzyme by selectively binding to Arg 141, has been studied by 1H NMR. Several 1H NMR lines of the copper-liganding histidine residues were perturbed, reproducing an effect so far observed only in the case of binding of anions to this protein. The room temperature EPR spectrum of the modified Cu,Zn protein was altered very slightly, indicating that the geometry of the copper site was not grossly affected by the modification. NMR and EPR changes were reversed by dialysis in the case of the reversible butanedione adduct. These data show that the coordination of the copper in Cu,Zn superoxide dismutase can be destabilized by modifications occurring at a neighboring but not a metal-liganding residue. It is suggested that part of the NMR effects seen on copper ligands in the case of anion binding are produced by interaction of anions with Arg 141, rather than by direct ligand replacement.     

Structural determinants of fluoride and formate binding to hemoglobin and myoglobin: crystallographic and 1H-NMR relaxometric study.

The x-ray crystal structure of the fluoride derivative of ferric sperm whale (Physeter catodon) myoglobin (Mb) has been determined at 2.5 A resolution (R = 0.187) by difference Fourier techniques. The fluoride anion, sitting in the central part of the heme distal site and coordinated to the heme iron, is hydrogen bonded to the distal His(64)E7 NE2 atom and to the W195 solvent water molecule. This water molecule also significantly interacts with the same HisE7 residue, which stabilizes the coordinated fluoride ion. Moreover, fluoride and formate binding to ferric Aplysia limacina Mb, sperm whale (Physeter catodon) Mb, horse (Caballus caballus) Mb, loggerhead sea turtle (Caretta caretta) Mb, and human hemoglobin has been investigated by 1H-NMR relaxometry. A strong solvent proton relaxation enhancement is observed for the fluoride derivatives of hemoproteins containing HisE7. Conversely, only a small outer-sphere contribution to the solvent relaxation rate has been observed for all of the formate derivatives considered and for the A. limacina Mb:fluoride derivative, where HisE7 is replaced by Val.     

Intracerebral Sex Differences in the Vasotocin System in Birds: Possible Implication in Behavioral and Autonomic Functions

The brain vasotocinergic system demonstrates clear sexual dimorphism in birds investigated so far. This paper examines the evidence obtained in studies on gallinaceous (domestic fowl, Japanese quail) and passerine (canary, junco, zebra finch) birds. Vasotocin (VT)-immunoreactive parvocellular neurons are present in the nucleus of stria terminalis of males, but they are less abundant or absent in the corresponding structure of females. A similar difference has been observed in the dorsal paraventricular area of domestic fowl. Sex-related differences in VT-gene expression have been confirmed byin situhybridization. Moreover, overall brain content of VT mRNA in cockerels is about twice that of hens, suggesting that VT synthesis may also be sexually dimorphic in other brain areas where morphological sex differences have not yet been revealed. The vasotocinergic system in birds is implicated in body fluid homeostasis, and during ontogeny it starts to respond to osmotic challenges in a sexually dimorphic way. Photoperiod, aging, or castration—all associated with changes in circulating testosterone levels—affect sexually dimorphic VT pathways and cell clusters. Sexually dimorphic vasotocinergic circuits are distributed in regions containing steroid-concentrating cells and are closely intermingled with aromatase-containing neurons that may mediate activational effects of gonadal steroids on this peptidergic system. However, it remains undetermined whether the observed neuroanatomical sex differences are related to sexually dimorphic autonomic and behavioral effects induced by VT. Most likely, VT in birds has a modulatory rather than a specific regulatory function in control of male sexual behavior and vocalization.     

Mild alkaline/oxidative pretreatment of wheat straw

A new mild alkaline/oxidative pretreatment of wheat straw prior to enzymic hydrolysis was carried out. It consists of a first alkaline (1% NaOH for 24 h) step, which mainly solubilises hemicellullose and renders the material more accessible to further chemical attack, and a second alkaline/oxidative step (1% NaOH and 0·3% H₂O₂ for 24 h), which solubilises and oxidises lignin to minor polluting compounds. The entire process was carried out at low temperature (25–40°C) using a low concentration of chemicals, resulting in a relatively low cost and waste liquors containing only trace amounts of dangerous pollutants derived from lignin. Recovery of cellulose after the double pretreatment reached 90% of that contained in the starting material, with a concomitant 81% degradation of lignin. The action of a commercial cellulase on the cellulose obtained produced a syrup with a high concentration of reducing sugars (220 mg/ml), of which a large percentage was glucose.     

The aromatase inhibitor letrozole in advanced breast cancer: Effects on serum insulin-like growth factor (IGF)-I and IGF-binding protein-3 levels

Serum insulin-like growth factor (IGF)-I and IGF-binding protein-3 levels were measured in two groups of postmenopausal women with advanced breast cancer, who received the aromatase inhibitor letrozole 0.5 or 2.5 mg p.o. once daily. Blood samples were obtained from 15 patients in each dose group at baseline, and one and three months after starting therapy. Circulating IGF-I and IGFBP-3 concentrations were determined by means of radioimmunoassay. In both dosage groups a statistically significant increase in the IGF-I levels was observed during three months of letrozole treatment (P = 0.003). In addition, the multiple testing procedure yielded in the whole patient population a significant result in the comparison between mean IGF-I values after three months of therapy and those observed at baseline (P = 0.004), the estimated average increase being of 24%. No significant result was obtained in the analysis for the dose effect (P = 0.077) and for the time × dose interaction (P = 0.208). Circulating IGFBP-3 levels did not appear to be affected by letrozole treatment in either of the dose groups. This is the first report concerning the short-term effects of letrozole on components of the IGF system in breast cancer patients; further investigations are warranted in order to confirm these preliminary data.     

Long Term Feeding Patterns Highlight Preference for Sucrose in the Fruit Fly <Emphasis Type="Italic">Anastrepha serpentina</Emphasis> When Given a Choice over Other More Nutritious Food Sources

Insects are known to be able to regulate food ingestion according to its nutrient composition rather than its energetic content. Several studies have found that individuals can feed selectively when given the opportunity, and balance the intake of different nutrients so as to optimize fitness. However, there are cases in which individuals do not strictly adopt this pattern of optimal nutrient balancing. This study examined the periodicity of feeding on different food substrates and also water by adult individuals of Anastrepha serpentina (Wiedemann) (Diptera: Tephritidae) over a 38-day observation period analyzing daily feeding patterns, feeding time, and sequences of feeding events. Two artificial food substrates, one rich in protein (hydrolyzed yeast) and one rich in carbohydrates (sucrose), and one natural diet (open sapodilla fruit) were offered alone or paired (sucrose vs. open fruit or sucrose vs. yeast) to newly emerged individuals during 38 days or until death. Water was also provided in all cases. Our results provide new and interesting insights on long-term individual dietary preferences and feeding periodicity in a tropical fruit fly, including water consumption. In general, flies exhibited different feeding patterns according to the diet, but preferred to feed on sucrose when offered a choice of sucrose and yeast. This preference was evident from the outset of the trial. When sucrose was offered together with an open fruit, the latter was preferred. However, there were conspicuous individual differences in temporal feeding patterns among flies fed the same diet, including variability in the number of consecutive days some individuals did not consume any food or water (up to five days in some cases). Individuals fed with sucrose only exhibited the lowest survival and those fed with sucrose-open fruit the highest. We discuss these feeding choices and their possible causes, including individual differences in the gut microbiota and nutritional reserves of newly emerged flies.