Purification and partial characterization of serum monocytotropic factor, a platelet-derived cyclooxygenase-inducing polypeptide

It has previously been shown that a heat- and acid-stable component of human and animal sera was capable of stimulating prostanoid biosynthesis in human blood monocytes, very probably by a mechanism involving cyclooxygenase induction. Many physico-chemical characteristics of this factor are similar to those of identified platelet factors. Here we show that human platelets are a rich source of this factor (serum monocytotropic factor) and that results from experiments using arachidonic acid or thrombin as releasers are consistent with its presence in platelet membranes. Serum monocytotropic factor has been purified 1500-fold by three chromatographic steps. Purification was more difficult when starting from platelet releasates or lysates. The purified serum monocytotropic factor had an apparent molecular mass of 70,000 as judged by Sephadex G-75 chromatography and by polyacrylamide gel electrophoresis; however, when subjected to HPLC on a gel permeation column in the presence of 6 M urea, one major peak corresponding to a relative molecular mass (Mr) of 30,000-35,000 was observed, which suggests a homodimeric structure. It is therefore very likely that human platelets store, in addition to the two well-identified polypeptide growth factors, platelet-derived growth factor and transforming growth factor-beta, a third polypeptide capable of regulating prostanoid production in monocytes.     

Regulation of thromboxane A2 biosynthesis in platelet-free human monocytes and the possible role of polypeptide growth factor(s) in the induction of cyclooxygenase system

It has previously been shown that platelet-free human monocytes, when properly incubated in the presence of animal and human sera, became capable of producing large amounts of thromboxane A2 and prostaglandin E2. The characteristics of these processes are reported here. Prostaglandin biosynthesis was time and cell concentration dependent; 24 h of incubation at 37 degrees C and 0.5 X 10(6) cells per ml medium were found to give the most reproducible results. Human monocytes produced thromboxane A2 and prostaglandin E2 in a typical ratio which ranged from 2.0 to 5.0 (28 experiments). Animal and human sera were similarly effective, while serum obtained from platelet-free blood was much less active. The activity of all sera tested was stable to heating (100 degrees C for 2-10 min) and extreme pH values (pH 2 and 11). It was unstable when the serum was heated at pH 11 and after 2-mercaptoethanol treatment. These observations prompted us to check the effect of polypeptide growth factors having properties similar to those reported above, such as platelet-derived growth factor, fibroblast growth factor, epidermal growth factor as well as insulin and transferrin. None of these, alone or in various combinations, was capable of eliciting a stimulation comparable with that of serum. Stimulation due to sera was, as expected, dose dependently inhibited by acetylsalicylic acid and more efficiently by indomethacin; unexpectedly it was also inhibited by protein synthesis inhibitors such as actinomycin D and cycloheximide in conditions under which no toxic effect of the drugs was evident. On the basis of these results we conclude that: (a) polypeptide growth factor(s) with a molecular weight at least 30 000 (as judged by Amicon ultrafiltration) is involved in the regulation of prostaglandin biosynthesis); (b) such a factor(s) acts by inducing rather than by activating the cyclooxygenase system.     

Isolation and characterization of plasma membrane-associated cortical granules from sea urchin eggs

Cortical granules, which are specialized secretory organelles found in ova of many organisms, have been isolated from the eggs of the sea urchins Arbacia punctulata and Strongylocentrtus pupuratus by a simple, rapid procedure. Electron micropscope examination of cortical granules prepared by this procedure reveals that they are tightly attached to large segments of the plasma membrane and its associated vitelline layer. Further evidence that he cortical granules were associated with these cell surface layers was obtained by (125)I-labeling techniques. The cortical granule preparations were found to be rich in proteoesterase, which was purified 32-fold over that detected in a crude homogenate. Similarly, the specific radioactivity of a (125)I-labeled, surface glycoprotein was increased 40-fold. These facts, coupled with electron microscope observations, indicate the isolation procedure yields a preparation in which both the cortical granules and the plasma membrane-vitelline layer are purified to the same extent. Gel electrophoresis of the membrane-associated cortical granule preparation reveals the presence of at least eight polypeptides. The major polypeptide, which is a glycotprotein of apparent mol wt of 100,000, contains most of the radioactivity introduced by (125)I-labeling of the intact eggs. Lysis of the cortical granules is observed under hypotonic conditions, or under isotonic conditions if Ca(2+) ion is present. When lysis is under isotonic conditions is induced by addition of Ca(2+) ion, the electron-dense contents of the granules remain insoluble. In contrast, hypotonic lysis results in release of the contents of the granule in a soluble form. However, in both cases the (125)I-labeled glycoprotein remains insoluble, presumably because it is a component of either the plasma membrane or the vitelline layer. All these findings indicate that, using this purified preparation, it should be possible to carry out in vitro studies to better define some of the initial, surface-related events observed in vivo upon fertilization.     

Optimizing canopy‐forming algae conservation and restoration with a new herbivorous fish deterrent device

The role of herbivorous fish in threatening marine forests of temperate seas has been generally overlooked. Only recently, the scientific community has highlighted that high fish herbivory can lead to regime shifts from canopy‐forming algae to less complex turf communities. Here, we present an innovative herbivorous fish deterrent device (DeFish), which can be used for conservation and restoration of marine forests. Compared to most traditional fish exclusion systems, such as cages, the DeFish system does not need regular cleaning and maintenance, making it more cost‐efficient. Resistance of DeFish was tested by installing prototypes at different depths in the French Riviera and in Montenegro: more than 60% of the devices endured several years without maintenance, even if most of them were slightly damaged in the exposed site in Montenegro. The efficacy of DeFish in limiting fish herbivory was tested by an exclusion experiment on Cystoseira amentacea in the French Riviera. In a few months, the number of fish bite marks on the seaweed was decreased, causing a consequent increase in algal length. The device here presented has been conceived for Mediterranean canopy‐forming algae, but the same concept can be applied to other species vulnerable to fish herbivory, such as kelps or seagrasses. In particular, the DeFish design could be improved using more robust and biodegradable materials. Innovative engineering systems, such as DeFish, are expected to become useful tools in the conservation and restoration of marine forests, to complement other practices including active reforestation, herbivore regulation, and regular monitoring of their status.     

Collective Response of Zebrafish Shoals to a Free-Swimming Robotic Fish

In this work, we explore the feasibility of regulating the collective behavior of zebrafish with a free-swimming robotic fish. The visual cues elicited by the robot are inspired by salient features of attraction in zebrafish and include enhanced coloration, aspect ratio of a fertile female, and carangiform/subcarangiform locomotion. The robot is autonomously controlled with an online multi-target tracking system and swims in circular trajectories in the presence of groups of zebrafish. We investigate the collective response of zebrafish to changes in robot speed, achieved by varying its tail-beat frequency. Our results show that the speed of the robot is a determinant of group cohesion, quantified through zebrafish nearest-neighbor distance, which increases with the speed of the robot until it reaches . We also find that the presence of the robot causes a significant decrease in the group speed, which is not accompanied by an increase in the freezing response of the subjects. Findings of this study are expected to inform the design of experimental protocols that leverage the use of robots to study the zebrafish animal model.     

Quinones bearing non-steroidal anti-inflammatory fragments as multitarget ligands for Alzheimer’s disease

The anti-amyloid properties shared by several quinones inspired the design of a new series of hybrids derived from the multi-target drug candidate memoquin (1). The hybrids consist of a central benzoquinone core and a fragment taken from non-steroidal anti-inflammatory drugs, connected through polyamine linkers. The new hybrids retain the potent anti-aggregating activity of the parent 1, while exhibiting micromolar AChE inhibitory activities. Remarkably, 2, 4, (R)-6 and (S)-6 were Aβ aggregation inhibitors even more potent than 1. The balanced amyloid/cholinesterase inhibitory profile is an added value that makes the present series of compounds promising leads against Alzheimer’s disease.     

Middle Pleistocene Steppe Lion Remains from Grotte de la Carrière (Têt Valley,Eastern Pyrenees)

Journal of Mammalian Evolution - Late Pleistocene cave lions are one of the most iconic species of Northern Hemisphere Quaternary taphocoenoses. Despite their often-scarce record in cave...     

Synthesis and enantioselectivity of the enantiomers of PG9 and SM21, new potent analgesic and cognition-enhancing drugs

The enantiomers of two α-tropanyl esters, SM₂₁ (1) and PG₉ (2), derived from (+)-R-hyoscyamine, that act by increasing the central cholinergic tone, were obtained by esterification after resolution of the corresponding racemic acids [(−)-S-1, (−)-R-2 and (+)-S-2] and by stereospecific synthesis [(+)-R-1]. Their analgesic and cognition-enhancing activities were tested in mice and their ACh-releasing properties determined on rat parietal cortex. These compounds show enantioselectivity in analgesic and cognition-enhancing tests on mice, the eutomers being the isomers which possess the same spatial arrangement of the groups on the chiral atom as (+)-R hyoscyamine [(+)-R-SM₂₁, (+)-S-PG₉]. The ACh-releasing effect of the enantiomers of SM₂₁ in rats is in agreement with the results in mice, while PG₉ enantiomers do not show any appreciable enantioselectivity in this test. On the basis of the different effects of the 5-HT₄ antagonist SDZ 205557 on analgesia induced by the enantiomers of 1 and 2 and by (+)-R-hyoscyamine and the α-tropanyl ester of 2-phenylpropionic acid 3, a mechanism of action is proposed for this class of compounds. © 1996 Wiley-Liss, Inc.     

Endogenous morphine modulates acute thermonociception in mice

The endogenous synthesis of morphine has been clearly demonstrated throughout the phylogenesis of the nervous system of mammals and lower animals. Endogenous morphine, serving as either a neurotransmitter or neurohormone, has been demonstrated in the nervous system of both vertebrates and invertebrates. As one of the effects of exogenous morphine is the modulation of pain perception, we investigated the effects that the depletion of endogenous morphine had on nociceptive transmission. The immunoneutralization of endogenous morphine from brain extracellular spaces was obtained through the intracerebroventricular administration of affinity purified anti-morphine IgG to mice, which then underwent the hot plate test. Endogenous morphine immunoneutralization decreased thermal response latency and attenuated the anti-nociceptive effect of the mu selective agonist DAMGO in hot plate test suggesting that endogenous morphine is involved in pain modulation.     

Phylogenetic utility of the nuclear gene arginine decarboxylase: an example from Brassicaceae

Arginine decarboxylase (ADC) is an important enzyme in the production of putrescine and polyamines in plants. It is encoded by a single or low-copy nuclear gene that lacks introns in sequences studied to date. The rate of Adc amino acid sequence evolution is similar to that of ndhF for the angiosperm family studied. Highly conserved regions provide several target sites for PCR priming and sequencing and aid in nucleotide and amino acid sequence alignment across a range of taxonomic levels, while a variable region provides an increased number of potentially informative characters relative to ndhF for the taxa surveyed. The utility of the Adc gene in plant molecular systematic studies is demonstrated by analysis of its partial nucleotide sequences obtained from 13 representatives of Brassicaceae and 3 outgroup taxa, 2 from the mustard oil clade (order Capparales) and 1 from the related order Malvales. Two copies of the Adc gene, Adc1 and Adc2, are found in all members of the Brassicaceae studied to data except the basal genus Aethionema. The resulting Adc gene tree provides robust phylogenetic data regarding relationships within the complex mustard family, as well as independent support for proposed tribal realignments based on other molecular data sets such as those from chloroplast DNA.