Nutrient-dependent expression of insulin-like peptides from neuroendocrine cells in the CNS contributes to growth regulation in Drosophila

BACKGROUND: The insulin/IGF-1 signaling pathway controls cellular and organismal growth in many multicellular organisms. In Drosophila, genetic defects in components of the insulin signaling pathway produce small flies that are delayed in development and possess fewer and smaller cells as well as female sterility, reminiscent of the phenotypes of starved flies. RESULTS: Here we establish a causal link between nutrient availability and insulin-dependent growth. We show that in addition to the Drosophila insulin-like peptide 2 (dilp2) gene, overexpression of dilp1 and dilp3-7 is sufficient to promote growth. Three of the dilp genes are expressed in seven median neurosecretory cells (m-NSCs) in the brain. These m-NSCs possess axon terminals in the larval endocrine gland and on the aorta, from which DILPs may be released into the circulatory system. Although expressed in the same cells, the expression of the three genes is controlled by unrelated cis-regulatory elements. The expression of two of the three genes is regulated by nutrient availability. Genetic ablation of these neurosecretory cells mimics the phenotype of starved or insulin signaling mutant flies. CONCLUSIONS: These results point to a conserved role of the neuroendocrine axis in growth control in multicellular organisms.     

Human ABCC1 interacts and colocalizes with ATP synthase α, revealed by interactive proteomics analysis

Human ABCC1 is a member of the ATP-binding cassette (ABC) transporter superfamily, and its overexpression has been shown to cause multidrug resistance by active efflux of a wide variety of anticancer drugs. ABCC1 has been shown to exist and possibly function as a homodimer. However, a possible heterocomplex involving ABCC1 has been indicated. In this study, we performed an interactive proteomics study to examine proteins that bind to and form heterocomplexes with ABCC1 using coimmunoprecipitation and tandem mass spectrometry (MS/MS) analyses. We found that ATP synthase α binds to ABCC1 in plasma membranes with a ratio of 2:1. The ATP synthase α binding site in ABCC1 is located in the linker domain at the carboxyl core of ABCC1, and phosphorylation of the linker domain at the protein kinase A site enhances ATP synthase α binding. The interaction between ABCC1 and ATP synthase α in a heterocomplex may indicate a novel function of ABCC1 in regulating extracellular ATP level and purinergic signaling cascade.     

A chick model of retinal detachment: cone rich and novel

Background

Development of retinal detachment models in small animals can be difficult and expensive. Here we create and characterize a novel, cone-rich retinal detachment (RD) model in the chick.

Methodology/Principal Findings

Retinal detachments were created in chicks between postnatal days 7 and 21 by subretinal injections of either saline (SA) or hyaluronic acid (HA). Injections were performed through a dilated pupil with observation via surgical microscope, using the fellow eye as a control. Immunohistochemical analyses were performed at days 1, 3, 7, 10 and 14 after retinal detachment to evaluate the cellular responses of photoreceptors, Müller glia, microglia and nonastrocytic inner retinal glia (NIRG). Cell proliferation was detected with bromodeoxyuridine (BrdU)-incorporation and by the expression of proliferating cell nuclear antigen (PCNA). Cell death was detected with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). As in mammalian models of RD, there is shortening of photoreceptor outer segments and mis-trafficking of photoreceptor opsins in areas of RD. Photoreceptor cell death was maximal 1 day after RD, but continued until 14 days after RD. Müller glia up-regulated glial fibriliary acidic protein (GFAP), proliferated, showed interkinetic nuclear migration, and migrated to the subretinal space in areas of detachment. Microglia became reactive; they up-regulated CD45, acquired amoeboid morphology, and migrated toward outer retina in areas of RD. Reactive NIRG cells accumulated in detached areas.

Conclusions/Significance

Subretinal injections of SA or HA in the chick eye successfully produced retinal detachments and cellular responses similar to those seen in standard mammalian models. Given the relatively large eye size, and considering the low cost, the chick model of RD offers advantages for high-throughput studies.     

Increased 5-Lipoxygenase Immunoreactivity in the Hippocampus of Patients With Alzheimer's Disease

The proinflammatory enzyme 5-lipoxygenase (5-LOX) is upregulated in Alzheimer''s disease (AD), but its localization and association with the hallmark lesions of the disease, β-amyloid (Aβ) plaques and neurofibrillary tangles (NFTs), is unknown. This study examined the distribution and cellular localization of 5-LOX in the medial temporal lobe from AD and control subjects. The spatial relationship between 5-LOX immunoreactive structures and AD lesions was also examined. We report that, in AD subjects, 5-LOX immunoreactivity is elevated relative to controls, and its localization is dependent on the antibody-targeted portion of the 5-LOX amino acid sequence. Carboxy terminus–directed antibodies detected 5-LOX in glial cells and neurons, but less frequently in neurons with dystrophic (NFT) morphology. In contrast, immunoreactivity observed using 5-LOX amino terminus–directed antibodies was virtually absent in neurons and abundant in NFTs, neuritic plaques, and glia. Double-labeling studies showed a close association of 5-LOX–immunoreactive processes and glial cells with Aβ immunoreactive plaques and vasculature and also detected 5-LOX in tau immunoreactive and amyloid containing NFTs. Different immunolabeling patterns with antibodies against carboxy vs amino terminus of 5-LOX may be caused by post-translational modifications of 5-LOX protein in Aβ plaques and NFTs. The relationship between elevated intracellular 5-LOX and hallmark AD pathological lesions provides further evidence that neuroinflammatory pathways contribute to the pathogenesis of AD. (J Histochem Cytochem 56:1065–1073, 2008)     

Culture and PCR analysis of joint fluid in the diagnosis of prosthetic joint infection

This prospective study compared PCR and culture techniques in the diagnosis of prosthetic joint infection (PJI). We obtained joint fluid samples (JFS; n=115) from patients who had failed total joint arthroplasty between January 2003 and June 2005; 49 were positive for PJI according to established strict criteria. JFS were analyzed by PCR (n=35; control n=66) or culture (n=46, control n=48). PCR was positive in 71% of PJI cases, resulting in sensitivity, specificity, accuracy, positive predictive value, negative predictive value, and likelihood ratio for positive results as follows: 0.71; 0.97; 0.88; 0.93; 0.87 and 23.6, respectively. Culture was positive in 44% of PJI samples. Corresponding statistics were 0.44; 0.94; 0.69; 0.87; 0.63 and 7.0, respectively. Significantly higher sensitivity, accuracy and negative predictive values were calculated for PCR versus culture, and there was 83% concordance between the results of intraoperative culture and PCR detection of causative bacteria. Therefore, we conclude that PCR analysis of synovial fluid increases the utility of pre-operative aspiration for patients who require revision total joint surgery.     

Assessment of microbial carcass contamination of hunted wild boars

To investigate the microbiological conditions of hunted wild boar carcasses and factors that contribute to the microbial carcass contamination, skin and carcass meat swab samples from 210 hunted wild boars were collected from freshly shot animals. The mean aerobic colony counts (ACCs) and Enterobacteriaceae counts on the skin were 5.2 and 3.6 log₁₀ CFU/cm², with 1.4% of animals’ skin tested positive for Salmonella spp. Slightly higher mean ACC and Enterobacteriaceae counts of 5.4 and 3.8 log₁₀ CFU/cm² were obtained from carcass meat with Salmonella spp. prevalence of 1.9%. Inadequate hygiene practices in handling and dressing wild boar carcasses, such as evisceration in the laying position on the ground and practice of skin and interior carcass surface washing after evisceration, were found to have the most significant influence on the microbiological conditions of final carcasses. Therefore, these findings indicate the need for the implementation and strict adherence to good hygiene practice in hunting estates and game handling establishments.