The neuropeptide VIP regulates the expression of osteoclastogenic factors in osteoblasts

Osteoclast formation is controlled by stromal cells/osteoblasts expressing macrophage colony-stimulating factor (M-CSF) and receptor activator of NF-κB ligand (RANKL), crucial for osteoclast progenitor cell proliferation, survival and differentiation, and osteoprotegerin (OPG) that inhibits the interaction between RANKL and its receptor RANK. Recent data have strongly indicated that the nervous system plays an important role in bone biology. In the present study, the effects of the neuropeptide vasoactive intestinal peptide (VIP), present in peptidergic skeletal nerve fibers, on the expression of RANKL, OPG, and M-CSF in osteoblasts and stromal cells have been investigated. VIP and pituitary adenylate cyclase-activating polypeptide 38 (PACAP-38), but not secretin, stimulated rankl mRNA expression in mouse calvarial osteoblasts. In contrast, VIP inhibited the mRNA expressions of opg and m-csf, effects shared by PACAP-38, but not by secretin. VIP did not affect rankl, opg, or m-csf mRNA expression in mouse bone marrow stromal cells (BMSCs). The effects by VIP on the mRNA expression of rankl, opg, and m-csf were all potentiated by the cyclic AMP phosphodiesterase inhibitor rolipram. In addition, VIP robustly enhanced the phosphorylation of ERK and the stimulatory effect by VIP on rankl mRNA was inhibited by the MEK1/2 inhibitor PD98059. These observations demonstrate that activation of VPAC(2) receptors in osteoblasts enhances the RANKL/OPG ratio by mechanisms mediated by cyclic AMP and ERK pathways suggesting an important role for VIP in bone remodeling.     

Insights into the composition and assembly of the membrane arm of plant complex I through analysis of subcomplexes in Arabidopsis mutant lines

NADH-ubiquinone oxidoreductase (Complex I, EC 1.6.5.3) is the largest complex of the mitochondrial respiratory chain. In eukaryotes, it is composed of more than 40 subunits that are encoded by both the nuclear and mitochondrial genomes. Plant Complex I differs from the enzyme described in other eukaryotes, most notably due to the large number of plant-specific subunits in the membrane arm of the complex. The elucidation of the assembly pathway of Complex I has been a long-standing research aim in cellular biochemistry. We report the study of Arabidopsis mutants in Complex I subunits using a combination of Blue-Native PAGE and immunodetection to identify stable subcomplexes containing Complex I components, along with mass spectrometry analysis of Complex I components in membrane fractions and two-dimensional diagonal Tricine SDS-PAGE to study the composition of the largest subcomplex. Four subcomplexes of the membrane arm of Complex I with apparent molecular masses of 200, 400, 450, and 650 kDa were observed. We propose a working model for the assembly of the membrane arm of Complex I in plants and assign putative roles during the assembly process for two of the subunits studied.     

Altered motor activity, exploration and anxiety in heterozygous neuregulin 1 mutant mice: implications for understanding schizophrenia

Human genetic studies have shown that neuregulin 1 (NRG1) is a potential susceptibility gene for schizophrenia. Nrg1 influences various neurodevelopmental processes, which are potentially related to schizophrenia. The neurodevelopmental theory of schizophrenia suggests that interactions between genetic and environmental factors are responsible for biochemical alterations leading to schizophrenia. To investigate these interactions and to match experimental design with the pathophysiology of schizophrenia, we applied a comprehensive behavioural phenotyping strategy for motor activity, exploration and anxiety in a heterozygous Nrg1 transmembrane domain mutant mouse model (Nrg1 HET) using different housing conditions and age groups. We observed a locomotion- and exploration-related hyperactive phenotype in Nrg1 HETs. Increased age had a locomotion- and exploration-inhibiting effect, which was significantly attenuated in mutant mice. Environmental enrichment (EE) had a stimulating influence on locomotion and exploration. The impact of EE was more pronounced in Nrg1 hypomorphs. Our study also showed a moderate task-specific anxiolytic-like phenotype for Nrg1 HETs, which was influenced by external factors. The behavioural phenotype detected in heterozygous Nrg1 mutant mice is not specific to schizophrenia per se, but the increased sensitivity of mutant mice to exogenous factors is consistent with the pathophysiology of schizophrenia and the neurodevelopmental theory. Our findings reinforce the importance of carefully controlling experimental designs for external factors and of comprehensive, integrative phenotyping strategies. Thus, Nrg1 HETs may, in combination with other genetic and drug models, help to clarify pathophysiological mechanisms behind schizophrenia.     

Dung Beetle and Terrestrial Mammal Diversity in Forests, Indigenous Agroforestry Systems and Plantain Monocultures in Talamanca, Costa Rica

In order to explore the importance of indigenous agroforestry systems for biodiversity conservation, we compared the abundance, species richness and diversity of dung beetles and terrestrial mammals across a gradient of different land use types from agricultural monocultures (plantains) to agroforestry systems (cocoa and banana) and forests in the BriBri and Cabécar indigenous reserves in Talamanca, Costa Rica. A total of 132,460 dung beetles of 52 species and 913 tracks of 27 terrestrial mammal species were registered. Dung beetle species richness and diversity were greatest in the forests, intermediate in the agroforestry systems and lowest in the plantain monocultures, while dung beetle abundance was greatest in the plantain monocultures. The number of mammal tracks per plot was significantly higher in forests than in plantain monocultures, whereas mammal species richness was higher in forests than in either cocoa agroforestry systems or plantain monocultures. Species composition of both terrestrial mammals and dung beetles also varied across the different land use types. Our study indicates that indigenous cocoa and banana agroforestry systems maintain an intermediate level of biodiversity (which is less than that of the original forest but significantly greater than that of plantain monocultures) and provide suitable habitat for a number of forest-dependent species. Although the agroforestry systems appear to serve as favorable habitats for many terrestrial mammal species, their potential positive contribution to mammal conservation is being offset by heavy hunting pressure in the reserves. As in other agricultural landscapes, the conservation of biodiversity in Talamanca will depend not only on maintaining the existing forest patches and reducing the conversion of traditional agroforestry systems to monocultures, but also on reducing hunting pressure.     

Polycyclic aromatic hydrocarbon o-quinones inhibit the activity of the catalytic fragment of protein kinase C

Polycyclic aromatic hydrocarbons (PAHs) require metabolic activation to exert their carcinogenic effects. PAH trans-dihydrodiol proximate carcinogens are oxidized by aldo-keto reductases (AKRs) to their corresponding reactive and redox-active o-quinones which may have the properties of initiators and promoters. To determine whether these o-quinones target protein kinase C (PKC), their effects on human recombinant PKCalpha and PKCdelta and the catalytic fragment of rat brain PKC were determined. Naphthalene-1,2-dione (NP-1,2-dione), benzo[a]pyrene-7,8-dione (BP-7,8-dione), and 7,12-dimethylbenz[a]anthracene-3,4-dione (DMBA-3,4-dione) potently inhibited (IC(50) values 3-5 microM) the basal and stimulated activity of the holoenzymes PKCalpha and PKCdelta in a dose-dependent manner. Inhibition of PKC by BP-7,8-dione was observed irrespective of whether PKCalpha activity was stimulated with phorbol 12-myristate 13-acetate (PMA), phosphatidylserine (PS), or Ca(2+) or whether PKCdelta was stimulated with phorbol 12-myristate 13-acetate (PMA) or phosphatidylserine (PS), suggesting that the inhibition was not cofactor-specific. All three quinones inhibited the catalytic fragment of PKC in vitro, yielding identical IC(50) values (3-5 microM), indicating that they interact with the catalytic domain of PKC rather than the cofactor/activator sites. In contrast, no effect on either the holoenzyme or the catalytic fragment was observed with the corresponding PAH trans-dihydrodiols, indicating that inhibition was o-quinone-specific. Irreversible inhibition of the catalytic fragment of PKC was observed since activity could not be restored by dialysis, suggesting that arylation of the fragment had occurred. NP-1,2-dione and BP-7,8-dione also suppressed PKC activity in human breast cancer MCF-7 cell lysates which express PKCalpha, -beta, -delta, -epsilon, -iota, and -lambda isozymes. These data suggest that PAH o-quinones, generated by AKRs, may affect cellular signaling through suppression of the activity of PKC isoforms.     

Demographic and Biomass Production Consequences of Inundative Treatment of Cirsium arvense with Sclerotinia sclerotiorum

The adventitious shoots in three populations of Cirsium arvense in sheep-grazed pastures were treated in October (spring) 1991 with a mycelium/wheat formulation of Sclerotinia sclerotiorum and the fates of mapped shoots were followed over the growing season. In untreated plots, deaths through natural causes were compensated for by births (emergence of new shoots above the soil) throughout the growing season, but, on plots treated with S. sclerotiorum, deaths from the induced disease exceeded births for 35 days following treatment, causing the shoot population to decline markedly. Disease-induced deaths occurred only among shoots present at the time of treatment; there was no evidence of transfer of the pathogen to shoots emerging after the treatment was applied. A life-table analysis showed that only 8% of the adventitious shoots emerging during the growing season survived to seeding on treated plots, compared with 28% on the untreated plots; most mortalities occurred in shoots at the vegetative stage of development. The dry mass of propagative roots in autumn was reduced to 35% of that on the untreated plots by the pathogen and the density of shoots emerging the following spring was reduced to a similar extent. The results of this study indicate that S. sclerotiorum has potential as a mycoherbicide for C. arvense in sheep-grazed pasture in New Zealand.     

Identifying key biodiversity areas as marine conservation priorities in the greater Caribbean

Increasing rates of Anthropocene biodiversity extinctions suggest a possible sixth mass extinction event. Conservation planners are seeking effective ways to protect species, hotspots of biodiversity, and dynamic ecosystems to reduce and eventually eliminate the degradation and loss of diversity at the scale of genes, species, and ecosystems. While well-established, adequately enforced protected areas (PAs) increase the likelihood of preserving species and habitats, traditional placement methods are frequently inadequate in protecting biodiversity most at risk. Consequently, the Key Biodiversity Area (KBA) Partnership developed a set of science-based criteria and thresholds that iteratively identify sites where biodiversity is most in need of protection. KBA methodology has been rarely applied in the marine realm, where data are often extremely limited. We tested the feasibility of KBA population metrics in the Greater Caribbean marine region using occurrence and population data and threat statuses for 1669 marine vertebrates. These data identified areas where site-specific conservation measures can effectively protect biodiversity. Using KBA criteria pertaining to threatened and irreplaceable biodiversity, we identified 90 geographically unique potential KBAs, 34 outside and 56 within existing PAs. These provide starting points for local conservation managers to verify that KBA thresholds are met and to delineate site boundaries. Significant data gaps, such as population sizes, life history characteristics, and extent of habitats, prevent the full application of the KBA criteria to data-poor marine species. Increasing the rate and scope of marine sampling programs and digital availability of occurrence datasets will improve identification and delineation of KBAs in the marine environment.