Aldehyde oxidases of Drosophila: Contributions of several enzymes to observed activity patterns

At least four enzymes contribute to histochemically, electrophoretically, or spectrophotometrically detectable aldehyde oxidase (AO) activity in Drosophila melanogaster. The one we designate AO-1 contributes the majority of activity measured in extracts of whole flies. Pyridoxal oxidase (PO) is also a broad range AO. It is prominent only in midgut and Malpighian tubules, where it apparently accounts for a substantial fraction of total AO activity. The tissue distributions of these enzymes are clearly disparate despite close linkage of their structural loci and parallel dependence on the mal, lxd, and cin loci. A similarly related enzyme, xanthine dehydrogenase (XDH), is detected as an AO only in electrophoretic gels. A fourth broad range AO, not dependent on mal, lxd, and cin, is confined to the ejaculatory bulb. A similar array of AO isozymes is present in phylogenetically distant Drosophila species.This work was supported by NIH Grant 2 RO1 HD 10723.     

Hasty sensorimotor decisions rely on an overlap of broad and selective changes in motor activity

Humans and other animals are able to adjust their speed–accuracy trade-off (SAT) at will depending on the urge to act, favoring either cautious or hasty decision policies in different contexts. An emerging view is that SAT regulation relies on influences exerting broad changes on the motor system, tuning its activity up globally when hastiness is at premium. The present study aimed to test this hypothesis. A total of 50 participants performed a task involving choices between left and right index fingers, in which incorrect choices led either to a high or to a low penalty in 2 contexts, inciting them to emphasize either cautious or hasty policies. We applied transcranial magnetic stimulation (TMS) on multiple motor representations, eliciting motor-evoked potentials (MEPs) in 9 finger and leg muscles. MEP amplitudes allowed us to probe activity changes in the corresponding finger and leg representations, while participants were deliberating about which index to choose. Our data indicate that hastiness entails a broad amplification of motor activity, although this amplification was limited to the chosen side. On top of this effect, we identified a local suppression of motor activity, surrounding the chosen index representation. Hence, a decision policy favoring speed over accuracy appears to rely on overlapping processes producing a broad (but not global) amplification and a surround suppression of motor activity. The latter effect may help to increase the signal-to-noise ratio of the chosen representation, as supported by single-trial correlation analyses indicating a stronger differentiation of activity changes in finger representations in the hasty context.

Many have argued that the regulation of the speed-accuracy tradeoff relies on an urgency signal, which implements "collapsing decision thresholds" by tuning neural activity in a global manner in decision-related structures. This study indicates that the reality is more subtle, with several aspects of "urgency" being specifically targeted to particular corticospinal populations within the motor system.     

Varietal difference in antifungal activity of some species of Agave

Crude leaf extracts of different Agave species were eluted out with the help of 80% methanol for their antifungal activity. The activity of A. americana, A. ferox, A. montana, A. marginata, and A. scabra were evaluated against brown rot fungi Postia placenta, the causal agent of wood decay of some economically important plants using a media poising method. The percent inhibition of hyphal growth was measured after the seventh day of incubation. A. montana shows the highest percent inhibition, 69.31%, of hyphal growth. These data suggested that the different Agave species analyzed have potential as antifungal agents with a broad range of activity. In the future they may be used as biocontrol agents to cure plant diseases without harming them.     

Amidase activity of some bacteria

The amidase activity of bacteria possessing a high nitrilase activity was found to display the same spectrum although the bacteria may belong to different taxonomic groups,Bacillus, Bacteridium, Micrococcus, Brevibacterium. The spectrum of amidase activity, although very broad, is more restricted than that of nitrilase activity. Internal amides as well as vinyl-bound amides are not hydrolyzed.     

Isolation ofCaenorhabditis elegans mutants lacking alcohol dehydrogenase activity

Alcohol dehydrogenase (ADH) and the genes encoding this enzyme have been studied intensively in a broad range of organisms. Little, however, has been reported on ADH in the free-living nematodeCaenorhabiditis elegans. Extracts of wild-typeC. elegans contain ADH activity and display a single band of activity on a native polyacrylamide gel. Reaction rate for alcohol oxidation is more rapid with higher molecular weight alcohols as substrate than with ethanol. Primary alcohols are preferred to secondary alcohols.C. elegans is sensitive to allyl alcohol, a compound that has been used to select for ADH-null mutants of several organisms. Allyl alcohol-resistant mutant strains were selected from ethylmethanesulfonate (EMS)-mutagenized nematode populations. ADH activity was measured in extracts from eight of these strains and was found to be low or nondetectable. These results form a basis for molecular and genetic characterization of ADH expression inC. elegans.     

Antimicrobial peptides derived from heme-containing proteins: Hemocidins

Deprived of heme and partially unfolded hemoglobin, myoglobin and cytochrome c display microbicidal activity against a broad spectrum of microorganisms with half maximal lethal dose estimated at micromolar concentrations. The intact proteins were ineffective. Antibacterial activity of these apohemoproteins was also sustained after digestion to approximately 50 amino acids long peptides but further fragmentation abolished microbicidal properties. The most active fragment of apomyoglobin (corresponding to 56–131 region) showed a pronounced effect on the E. coli membrane permeabilization and its action was sensitive to salt as well as to divalent cations concentrations. The membrane-directed effect was specific toward bacteria but no lipopolysaccharide binding properties were observed. No hemolytic properties, even at high peptide concentrations were found; however, a slight but dose-independent cytotoxic effect was observed on fibroblasts and hepatoma cells. The presented data suggest a `carpet-like' mechanism of the membrane-directed activity and may result from exceptional abilities of hemoprotein-derived peptides to form alpha-helical structures. We postulate that the antimicrobial peptides obtained from the heme-containing proteins should be named hemocidins, in contrast to, e.g., hemorphins displaying opioid-like activity.     

Seasonal activity and abundance of Orosius orientalis (Hemiptera: Cicadellidae) at agricultural sites in Southeastern Australia

Orosius orientalis is a leafhopper vector of several viruses and phytoplasmas affecting a broad range of agricultural crops. Sweep net, yellow pan trap and yellow sticky trap collection techniques were evaluated. Seasonal distribution of O. orientalis was surveyed over two successive growing seasons around the borders of commercially grown tobacco crops. Orosius orientalis seasonal activity as assessed using pan and sticky traps was characterised by a trimodal peak and relative abundance as assessed using sweep nets differed between field sites with peak activity occurring in spring and summer months. Yellow pan traps consistently trapped a higher number of O. orientalis than yellow sticky traps.     

Fictive chewing activity in motor neurons and interneurons of the suboesophageal ganglion of Manduca sexta larvae

Alternating antiphasic rhythmic activity was observed in opener and closer mandibular motor neurons in the isolated suboesophageal ganglion of the larva of Manduca sexta (Lepidoptera: Sphingidae). This was interpreted provisionally as fictive chewing; the pattern is similar to that seen in semiintact animals but of lower frequency. Additionally, a variety of associated rhythmic activities were observed in suboesophageal interneurons. These could be classified into several different physiological types by their activity patterns in relation to the chewing cycle. Some of these neurons can modulate the rhythm when injected with current. It seems likely that they are part of or associated with a central pattern generator circuit for chewing.Abbreviations A anterior - CEC circumoesophageal connective - Cl-MN closer motor neuron - IN interneuron - MdN mandibular nerve - MN motor neuron - O-MN opener motor neuron     

Isolation and distribution ofStreptomyces populations with heat-resistant collagenolytic activity from two protein-rich areas in Bulgarian soils

Two sites in Northeastern of Bulgaria were investigated as a source ofStreptomyces populations to screen for production of heat-resistant collagenase. The distribution and diversity of collagenolytic activity inStreptomyces populations from protein-rich residue were studied. Collagenolytic activity was found in 14% of the 350 tested strains. Poor collagenase producers generally dominated (70%). Highly active collagenase producers were rarely found (12%) and they were mainly fromAlbus andRoseus groups. The isolatedStreptomyces cultures developed a constitutive collagenase activity. Two promising, highly active, producers of heat-resistant collagenase were selected and identified asStreptomyces candidus 91 andS. cremeus 3. The investigatedStreptomyces collagenases were active over a broad range of temperature (40–80°C) and a narrow range of pH values (6.5–8.5), with optima at 40°C and pH 7.5.     

Modulation of TRPA1 channel activity by Cdk5 in sensory neurons

Transient receptor potential cation channel, subfamily A, member 1 (TRPA1), is activated by a broad range of noxious stimuli. Cdk5, a member of the Cdk family, has recently been identified as a modulator of pain signaling pathways. In the current study, we investigated the extent to which Cdk5 modulates TRPA1 activity. Cdk5 inhibition was found to attenuate TRPA1 response to agonist in mouse DRG sensory neurons. Additionally, the presence of active Cdk5 was associated with increased TRPA1 phosphorylation in transfected HEK293 cells that was roscovitine-sensitive and absent in the mouse mutant S449A full-length channel. Immunopurified Cdk5 was observed to phosphorylate human TRPA1 peptide substrate at S448A in vitro. Our results point to a role for Cdk5 in modulating TRPA1 activity.     

Multiple modes of cytoplasmic dynein regulation

In performing its multiple cellular functions, the cytoplasmic dynein motor is subject to complex regulation involving allosteric mechanisms within the dynein complex, as well as numerous extramolecular interactions controlling subcellular targeting and motor activity. Recent work has distinguished high- and low-load regulatory modes for cytoplasmic dynein, which, combined with a diversity of targeting mechanisms, accounts for a very broad range of functions.     

Antimodification activity of the ArdA and Ocr proteins

The ArdA and Ocr antirestriction proteins, whose genes are in transmissible plasmids (ardA) and bacteriophage genomes (0.3 (ocr)), specifically inhibit type I restriction-modification enzymes. The Ocr protein (T7 bacteriophage) was shown to inhibit both restriction (endonuclease) and modification (methylase) activities of the EcoKI enzyme in a broad range of intracellular concentrations (starting from 10–20 molecules per cell). In contrast to Ocr, the ArdA protein (ColIb-P9 transmissible plasmid) inhibited both of the EcoKI activities only at high intracellular concentrations (30000–40000 molecules per cell). When the ArdA concentration was several fold lower, only endonuclease activity of EcoKI was inhibited. It was assumed that a poorer ArdA ability to inhibit EcoKI modification activity is related to the substantial difference in life cycle between transmissible plasmids (symbiosis with the bacterial cell) and bacteriophages (infection and lysis of bacteria). The Ocr and ArdA mutants that inhibited exclusively endonuclease activity of EcoKI were obtained. Antirestriction proteins incapable of homodimerization were assumed to inhibit only endonuclease activity of type I restriction-modification enzymes.     

Antimicrobial activity of AOT-isooctane reverse micelle as a bioseparation and biocatalysis tool

Abstract

The antimicrobial activity of different reverse micelles on microorganisms is been compared using the disc diffusion method. The bis (2-ethylhexyl) sodium sulfosuccinate (AOT) reverse micelle showed a more significant inhibitory effect than do other reverse. micelles, and it had an antimicrobial activity against a broad range of microorganisms. Results from an antimicrobial activity test of isooctane and a forward extraction containing soybean protein suggest that the surfactant was chiefly responsible for inhibiting microbes in AOT/isooctane reverse micelle, while isooctane hardly inhibited the microbial growth. The properties of S. aureus, cultured in the TSB with AOT reverse micellar solution, were identified by the SEM and SDS-PAGE fingerprinting of cell-wall proteins. It is concluded that the cell-wall of the S. aureus decreased in the TSB with AOT reverse micellar solution, and some cell protein subunits of the S. aureus did not occurr, especially between 14.4 and 42.7 kDa, while one new protein subunit at near 97.4 kDa occurred     

Killer yeasts of Kluyveromyces and Hansenula genera with potential application in fermentation and therapy

The killing/immunity interactions among killer strains of the genera Kluyveromyces, Hansenula and Saccharomyces from the Czechoslovak Collection of Yeasts were studied with the aim to find the strains with broad specificity and killer activity targeted against a range of undesirable wild yeasts causing stuck fermentations. Among 49 tested Kluyveromyces strains, five strains were found, and among 55 Hansenula strains, ten yeast strains were found with activity against a sensitive strain of Saccharomyces. Hansenula mrakii CCY 38-7-1 and Hansenula saturnus var. subsufficiens CCY 38-4-2 showed exceptional activity against the wine contaminants, Zygosaccharomyces bailii, as well as against pathogenic Candida species within a broad range of pH 2.9–5.1. Their potential biotechnological application is discussed.     

Reutericyclin: biological activity,mode of action,and potential applications

Reutericyclin is an inhibitory compound produced by sourdough isolates of Lactobacillus reuteri that is structurally but not functionally related to naturally occurring tetramic acids. It is bacteriostatic or bactericidal to gram-positive bacteria based on its activity as a proton-ionophore, and a broad range of food-related spoilage organisms and pathogens is inhibited by reutericyclin. Gram-negative bacteria are resistant to reutericyclin because of the barrier properties of their outer membrane, and resistance of beer-spoiling lactobacilli towards hop bitter acids provides cross-protection to reutericyclin. Remarkably, reutericyclin-producing strains were shown to persist for a period of 10 years in an industrial sourdough fermentation, and reutericyclin was shown to be produced in concentrations active against competitors during growth of L. reuteri in sourdough. Based on the known properties of reutericyclin and L. reuteri, reutericyclin-producing strains may have applications in the biopreservation of foods. Furthermore, these strains were shown to colonize reconstituted lactobacilli-free mice at high levels. Therefore, they could serve as a suitable model system to evaluate a possible impact of antimicrobial compounds on the intestinal microflora of humans and animals.     

“Unconventional” neutralizing activity of antibodies against HIV

Neutralizing antibodies are recognized to be one of the essential elements of the adaptive immune response that must be induced by an effective vaccine against HIV. However, only a limited number of antibodies have been identified to neutralize a broad range of primary isolates of HIV-1 and attempts to induce such antibodies by immunization were unsuccessful. The difficulties to generate such antibodies are mainly due to intrinsic properties of HIV-1 envelope spikes, such as high sequence diversity, heavy glycosylation, and inducible and transient nature of certain epitopes. In vitro neutralizing antibodies are identified using “conventional” neutralization assay which uses phytohe-magglutinin (PHA)-stimulated human PBMCs as target cells. Thus, in essence the assay evaluates HIV-1 replication in CD4⁺ T cells. Recently, several laboratories including us demonstrated that some monoclonal antibodies and HIV-1-specific polyclonal IgG purified from patient sera, although they do not have neutralizing activity when tested by the “conventional” neutralization assay, do exhibit potent and broad neutralizing activity in “unconventional” ways. The neutralizing activity of these antibodies and IgG fractions is acquired through post-translational modifications, through opsonization of virus particles into macrophages and immature dendritic cells (iDCs), or through expression of antibodies on the surface of HIV-1-susceptible cells. This review will focus on recent findings of this area and point out their potential applications in the development of preventive strategies against HIV. Foundation item: Chinese Ministry of Science and Technology 973 program grant awarded to Paul Zhou (2006CB504308).     

Characterization of induced Staphylococcus aureus bacteriophage SAP-26 and its anti-biofilm activity with rifampicin

Lytic bacteriophages (phages) have been investigated as treatments for bacterial infectious diseases. An induced phage, SAP-26, was isolated from a clinical isolate of Staphylococcus aureus. It belongs to the family Siphoviridae and its genome consists of double-stranded 41,207 bp DNA coding for 63 open reading frames. The phage SAP-26 showed a wide spectrum of lytic activity against both methicillin-resistant S. aureus and methicillin-susceptible S.aureus. Furthermore, combined treatment with a phage and antimicrobial agents showed a strong biofilm removal effect which induced structural changes in the biofilm matrix and a substantial decrease in the number of bacteria. Such a broad host range in S. aureus and biofilm removal activity of the phage SAP-26 suggests the possibility of its use as a therapeutic phage in combination with appropriate antimicrobial agent(s). Among the three antimicrobial agents combined with phage, the combination of rifampicin showed the best biofilm removal effect. To the authors' knowledge, this study showed for the first time that S. aureus biofilm could be efficiently eradicated with the mixture of phage and an antimicrobial agent, especially rifampicin.     

Effects of blockade of noradrenergic and serotonergic transmission in theCM-Pf complex on neuronal activity in the motor thalamus in cats

Effects of injections of blockers of the monoaminergic receptor structures into thecentrum medianum-nucl. parafascicularis (CM-Pf) on the activity of neurons in the motor thalamic nuclei (VA-VL) were studied in chronic experiments on awake cats. The animals were trained to perform an operant placing reflex by the forelimb. Injection of a-adrenoblocker, anapriline, into theCM-Pf resulted in enhancement of background activity of neurons of the motor thalamus and facilitation of their spike responses related to conditioned and unconditioned reflex movements. Application of a blocker of serotonin receptors, lysergoamide, evoked opposite changes in the neuronal activity in theVA-VL nuclei: depression of background activity, facilitation of inhibitory processes, and suppression of evoked activity related to conditioned and unconditioned movements. It is supposed that the monoaminergic system of thelocus coeruleus exerts a suppressing influence on the motor thalamus via theCM-Pf complex, while the system of the raphe nuclei facilitates motor thalamic structures.Neirofiziologiya/Neurophysiology, Vol. 28, No. 6, pp. 305–311, November–December, 1996.     

Stress-induced depression of motor activity correlates with regional changes in brain norepinephrine but not in dopamine

This experiment examined how inescapable tail shock alters the level of dopamine and norepinephrine within various brain regions of the rat and the relationship of these changes to the depression of motor activity produced by the shock. Following exposure to tail shock that is known to interfere with acquisition of active behavioral tasks, animals were briefly tested for spontaneous motor activity and then sacrificed for neurochemical measures. Norepinephrine and dopamine levels in the frontal cortex, brain stem, striatum, olfactory tubercle, hypothalamus, hippocampus, septum, and amygdala were measured by a sensitive radicenzymatic technique. Exposure to 45 min of tail shock did not alter motor activity significantly, but shock sessions of 60 and 75 min duration produced a marked decrease in motor activity. Levels of dopamine were found to be very little changed in all brain regions studied except for the hypothalamus, in which a substantial rise in dopamine level was observed. Norepinephrine levels, in contrast, fell in many brain regions in response to shock. The fall in norepinephrine levels observed in twi brain regions was significantly correlated with the decline in motor activity (brain stemr=+0.70, hypothalamusr=+0.60) These data suggest that deficits in active motor behavior produced by shock parameters similar to those used in this study may reflect concomitant disturbances of noradrenergic function in specific brain regions.