Cobalt(II) and copper(II) binding of Bacillus cereus trinuclear phospholipase C: a novel 1H NMR spectrum of a 'Tri-Cu(II)' center in protein.

The phosphatidylcholine-preferring phospholipase C from Bacillus cereus (PC-PLC(Bc)) is a tri-Zn enzyme with two 'tight binding' and one 'loose binding' sites. The Zn2+ ions can be replaced with Co2+ and Cu2+ to afford metal-substituted derivatives. Two Cu2+-substituted derivatives are detected by means of 1H NMR spectroscopy, a 'transient' derivative and a 'stable' derivative. The detection of sharp hyperfine-shifted 1H NMR signals in the 'transient' derivative indicates the formation of a magnetically coupled di-Cu2+ center, which concludes that the Zn2+ ions in the dinuclear (Zn1 and Zn3) sites are more easily replaced by Cu2+ than that in the Zn2 site. This might possibly be the case for Co2+ binding. Complete replacement of the three Zn2+ ions can be achieved by extensive dialysis of the enzyme against excess Cu2+ to yield the final 'stable' derivative. This derivative has been determined to have five-coordinated His residues and an overall S'=1/2 spin state with NMR and EPR, consistent with the formation of a tri-Cu2+ center (i.e. a di-Cu2+/mono-Cu2+ center) in this enzyme. The binding of substrate to the inert tri-Cu2+ center to form an enzyme-substrate (ES) complex is clearly seen in the 1H NMR spectrum, which is not obtainable in the case of the native enzyme. The change in the spectral features indicates that the substrate binds directly to the trinuclear metal center. The studies reported here suggest that 1H NMR spectroscopy can be a valuable tool for the characterization of di- and multi-nuclear metalloproteins using the 'NMR friendly' magnetically coupled Cu2+ as a probe.     

Palatability and efficacy to possums and rats of pest control baits containing bird repellents

Repellents used to reduce by-kill of birds during pest control must not compromise acceptance by target species. Two repellents combined, anthraquinone (AQ; 0.4 g kg^?1) and d-pulegone (DP; 1.0) did not reduce the palatability of blue-coloured carrot baits to laboratory rats (Rattus norvegicus); nor did DP (2.0). Green-coloured carrot baits coated with AQ, DP or AQ + DP were taken from bait stations by wild possums (Trichosurus vulpecula) and rats. Toxic (1080) bait coated with AQ (0.4) and peanut oil (0.1) had reduced palatability but was accepted by laboratory rats. However, laboratory rats did not consume enough baits coated with AQ and bacon, peanut butter, cinnamon or DP to be killed. Anthraquinone (0.4 or 0.8) plus cinnamon and DP (0.5) did not affect palatability or lethality to captive ship rats (R. rattus) or possums. Anthraquinone and DP as surface coatings on baits are therefore acceptable to possums and possibly rats, at concentrations that deter some bird species.     

Seasonal liver protein differences in a hibernator revealed by quantitative proteomics using whole animal isotopic labeling

Hibernation is an energy-saving strategy used by diverse species of mammals to survive winter. It is characterized by cycles between multi-day periods of torpor with low body temperature (T(b)), and short periods of rapid, spontaneous rewarming. The ability to retain cellular integrity and function throughout torpor and rewarming is a key attribute of hibernation. Livers from winter hibernators are resistant to cellular damage induced by cold storage followed by warm reperfusion. Identifying proteins that differ between the summer-sensitive and winter-protected phenotypic states is one useful approach that may elucidate the molecular mechanisms that underlie this protection. Here we employ a novel quantitative proteomics screening strategy whereby a newly-weaned 13-lined ground squirrel was metabolically labeled by ingesting heavy-isotope substituted ((15)N) Spirulina. The liver protein extract from this animal provided a common reference for quantitative evaluation of protein differences by its addition to extracts from pooled samples of summer active (SA) or winter entrance (Ent) phase hibernating ground squirrels. We identified 61 significantly different proteins between the two groups and compared them to proteins identified previously in the same samples using 2D gels. Of the 20 proteins common to the two datasets, the direction and magnitude of their differences were perfectly concordant for 18, providing confidence that both sets of altered proteins reflect bona fide differences between the two physiological states. Furthermore, the 41 novel proteins recovered in this study included many new enzymes in pathways identified previously: specifically, additional enzymes belonging to the urea cycle, amino acid and carbohydrate degradation, and lipid biosynthetic pathways were decreased, whereas enzymes involved in ketone body synthesis, fatty acid utilization, protein synthesis and gluconeogenesis were increased in the samples from entrance hibernators compared to summer active animals, providing additional specific evidence for the importance of these pathways in the hibernating phenotype.     

A role for NOX NADPH oxidases in Alzheimer's disease and other types of dementia?

Because of population ageing, dementias are likely to become a major scourge of the 21st century. Causes of dementia include Alzheimer's disease, cerebrovascular disease, and lesser known entities such as frontotemporal dementia or dementia with Lewy bodies. Neuroinflammation is likely to play an important role in the pathogenesis of dementia by the killing of neurons through inflammatory mechanisms. Such a role of neuroinflammation is well documented for Alzheimer's disease, and it is likely to play a role in other types of dementia as well. Reactive oxygen species (ROS) play a key role in inflammatory tissue destruction. The phagocyte NADPH oxidase NOX2 is the best studied ROS-generating system. In the central nervous system, it is expressed in microglia and--to a lesser extent--in neurons. Indeed, there is emerging experimental evidence for a role of NOX2 in Alzheimer's and cerebrovascular disease. Recently, six novel ROS-generating NADPH oxidases with homology to NOX2 have been discovered. Several of them are also expressed in the central nervous system. In this article, we hypothesize a role of NOX-type NADPH oxidases in inflammatory neuronal loss. We review presently available evidence and suggest that NOX-type NADPH oxidases may become promising pharmacological targets for the treatment and prevention of dementia.     

Spatial Autocorrelation Analysis of the Distribution of Genotypes within Populations of Lodgepole Pine

Spatial autocorrelation analyses of point samples within two populations of lodgepole pine (Pinus contorta ssp. latifolia) indicate that single-locus mature tree and pollen genotypes are distributed in a nearly random fashion for most of the allozyme loci assayed. This lack of structure in the distributions of most genotypes is consistent with outcrossing rates that are very nearly 1.0 and with estimates indicating that both pollen and seed are dispersed over long distances in lodgepole pine. However, spatial autocorrelation of genotypes for a few loci suggests that genotypes at these loci may be under natural selection.     

Choline acetyltransferase activity of spinal cord cell cultures increased by co-culture with muscle and by muscle-conditioned medium

Activity of the enzyme choline acetyltransferase (CAT), which mediates the synthesis of the neurotransmitter, acetylcholine, was increased up to 20- fold in spinal cord (SC) cells grown in culture with muscle cells for 2 wk. This increase was directly related to the duration of co-culture as well as to the cell density of both the SC and muscle involved and was not affected by the presence of the acetylcholine receptor blocking agent, α-bungarotoxin. Glutamic acid decarboxylase (GAD) activity was often markedly decreased in SC-muscle cultures while the activities of acetylcholinesterase and several other enzymes were little changed. Increased CAT activity was also observed when SC cultures were maintained in medium which had been conditioned by muscle cells or by undifferentiated cells from embryonic muscle. Muscle-conditioned medium (CM) did not affect the activities of SC cell GAD or acetylcholinesterase. Dilution or concentration of the CM directly affected its ability to increase SC CAT activity , as did the duration and timing of exposure of the SC cells to the CM. The medium could be conditioned by muscle cells in the presence or absence of serum, and remained effective after dialysis or heating to 58 degrees C. Membrane filtration data were consistent with the conclusion that the active material(s) in CM had a molecular weight in excess of 50,000 daltons. We conclude that large molecular weight material that is released by muscle cells is capable of producing a specific increase in CAT activity of SC cells.     

Temporal aspects of the fine-scale genetic structure in a population of Cinnamomum insularimontanum (Lauraceae)

Cinnamomum insularimontanum Hayata (Lauraceae) is an insect-pollinated, broad-leaved evergreen tree with bird-dispersed seeds. We used allozyme loci, Wright's fixation index, spatial autocorrelation statistics (Moran's I), and coancestry measures to examine changes in genetic structure among four age-classes within a recently founded study population (60 x 100 m area) in southern Korea. There were no significant differences in expected heterozygosity among age classes. However, significant genetic differentiation among age classes was detected (P<0.0001). Fixation indices within age classes showed significant deficits of observed heterozygosity, which may be caused by partial selfing. The homogeneity of genetic structure among four age-classes may reflect similar spatial patterns of seed immigration from surrounding populations occurring year after year. Finally, the average Moran's I and coancestry estimates indicated essentially random spatial distributions of alleles for each of the four age-classes and between seedlings and 2-4 year juveniles vs adult trees. These findings are very similar to those observed in the same study area for another member of the Lauraceae, Neolitsea sericea, which has a very similar life history and ecological characteristics (ie, bird-dispersed fruits, insect pollination, and a similar age structure). Together, these results suggest that the fleshy drupes of lauraceous species represent an adaptation to aid in the independent dispersal of seed by birds, which in turn may increase the genetic diversity of founders colonizing new habitats.     

Spatial genetic structure of two sympatric neotropical palms with contrasting life histories

The spatial genetic structure within sympatric populations of two neotropical dioecious palm species with contrasting life histories was characterized to evaluate the influence of life history traits on the extent of genetic isolation by distance. Chamaedorea tepejilote is a common wind-pollinated arboreal understory palm. Chamaedorea elatior is an uncommon climbing subcanopy palm with entomophilous pollination syndrome. A total of 59 allozyme alleles for C. tepejilote and 53 alleles for C. elatior was analyzed using both unweighted (Iu) and weighted (Iw) Moran's I spatial autocorrelation statistics. The spatial genetic structure detected within these populations is consistent with those reported for highly dispersed plants. A significance test for differences between mean Moran's I-coefficients revealed less spatial genetic structure within the C. tepejilote population than that in the C. elatior population. Adjacent individuals of C. elatior exhibited significant spatial genetic autocorrelation (Iu=0.039, Iw=0.034), indicating a Wright's neighborhood size of about 100 individuals. For C. tepejilote, nonrandom genetic distribution among nearest neighbors was detected, even from small spatial autocorrelation values (Iu=0.008, Iw=0.009), consistent with a neighborhood size of about 300 individuals. For both species, seed dispersal, mortality among life cycle stages, overlapping generations, and contrasting traits of mating and reproduction influence the standing spatial genetic structure within populations.     

Conformationally restricted homotryptamines. Part 6: Indole-5-cycloalkyl methylamines as selective serotonin reuptake inhibitors

Racemic 5-(trans-2-aminomethylcyclopropyl)indoles, 5-(trans-2-aminomethylcyclopentyl) indoles, and 5-(cis-2-aminomethylcyclopentyl)indoles were synthesized and evaluated as selective serotonin reuptake inhibitors. These analogs followed SAR trends similar to those previously reported for 3-cycloalkyl substituted indoles. The most potent analogs exhibited single digit nanomolar inhibition at the human serotonin transporter but were 10-fold less active than the previously reported compounds.