Linkage of prostate cancer susceptibility loci to chromosome 1

Three prostate cancer susceptibility genes have been reported to be linked to different regions on chromosome 1: HPC1 at 1q24-25, PCAP at 1q42-43, and CAPB at 1p36. Replication studies analyzing each of these regions have yielded inconsistent results. To evaluate linkage across this chromosome systematically, we performed multipoint linkage analyses with 50 microsatellite markers spanning chromosome 1 in 159 hereditary prostate cancer families (HPC), including 79 families analyzed in the original report describing HPC1 linkage. The highest lod scores for the complete dataset of 159 families were observed at 1q24-25 at which the parametric lod score assuming heterogeneity (hlod) was 2.54 (P=0.0006) with an allele sharing lod of 2.34 (P=0.001) at marker D1S413, although only weak evidence was observed in the 80 families not previously analyzed for this region (hlod=0.44, P=0.14, and allele sharing lod=0.67, P=0.08). In the complete data set, the evidence for linkage across this region was very broad, with allele sharing lod scores greater than 0.5 extending approximately 100 cM from 1p13 to 1q32, possibly indicating the presence of multiple susceptibility genes. Elsewhere on chromosome 1, some evidence of linkage was observed at 1q42-43, with a peak allele sharing lod of 0.56 (P=0.11) and hlod of 0.24 (P=0.25) at D1S235. For analysis of the CAPB locus at 1p36, we focused on six HPC families in our collection with a history of primary brain cancer; four of these families had positive linkage results at 1p36, with a peak allele sharing lod of 0.61 (P=0.09) and hlod of 0.39 (P=0.16) at D1S407 in all six families. These results are consistent with the heterogeneous nature of hereditary prostate cancer, and the existence of multiple loci on chromosome 1 for this disease.     

Ubiquinone binding, ubiquinone exclusion, and detailed cofactor conformation in a mutant bacterial reaction center

The X-ray crystal structure of a Rhodobacter sphaeroides reaction center with the mutation Ala M260 to Trp (AM260W) has been determined. Diffraction data were collected that were 97.6% complete between 30.0 and 2.1 A resolution. The electron density maps confirm the conclusions of a previous spectroscopic study, that the Q(A) ubiquinone is absent from the AM260W reaction center (Ridge, J. P., van Brederode, M. E., Goodwin, M. G., van Grondelle, R., and Jones, M. R. (1999) Photosynthesis Res. 59, 9-26). Exclusion of the Q(A) ubiquinone caused by the AM260W mutation is accompanied by a change in the packing of amino acids in the vicinity of the Q(A) site that form part of a loop that connects the DE and E helices of the M subunit. This repacking minimizes the volume of the cavity that results from the exclusion of the Q(A) ubiquinone, and further space is taken up by a feature in the electron density maps that has been modeled as a chloride ion. An unexpected finding is that the occupancy of the Q(B) site by ubiquinone appears to be high in the AM260W crystals, and as a result the position of the Q(B) ubiquinone is well-defined. The high quality of the electron density maps also reveals more precise information on the detailed conformation of the reaction center carotenoid, and we discuss the possibility of a bonding interaction between the methoxy group of the carotenoid and residue Trp M75. The conformation of the 2-acetyl carbonyl group in each of the reaction center bacteriochlorins is also discussed.     

Novel Zn2+ Modulated GPR39 Receptor Agonists Do Not Drive Acute Insulin Secretion in Rodents

Type 2 diabetes (T2D) occurs when there is insufficient insulin release to control blood glucose, due to insulin resistance and impaired β-cell function. The GPR39 receptor is expressed in metabolic tissues including pancreatic β-cells and has been proposed as a T2D target. Specifically, GPR39 agonists might improve β-cell function leading to more adequate and sustained insulin release and glucose control. The present study aimed to test the hypothesis that GPR39 agonism would improve glucose stimulated insulin secretion in vivo. A high throughput screen, followed by a medicinal chemistry program, identified three novel potent Zn²⁺ modulated GPR39 agonists. These agonists were evaluated in acute rodent glucose tolerance tests. The results showed a lack of glucose lowering and insulinotropic effects not only in lean mice, but also in diet-induced obese (DIO) mice and Zucker fatty rats. It is concluded that Zn²⁺ modulated GPR39 agonists do not acutely stimulate insulin release in rodents.     

Exploring host‐associated differentiation in the North American native cranberry fruitworm,Acrobasis vaccinii,from blueberries and cranberries

The factors explaining host‐associated differentiation (HAD) have not yet been fully characterized, especially in agricultural systems. It is thought that certain characteristics within a system may increase the probability for HAD to occur. These characteristics include relatively long‐standing evolutionary relationships between insects and their host plants, endophagy, and allochrony in host‐plant phenologies. We assessed the status of these characteristics as well as the presence of HAD in the cranberry fruitworm, Acrobasis vaccinii Riley (Lepidoptera: Pyralidae), a pest associated with blueberry and cranberry in eastern North America. We reveal the occurrence of two distinct populations of A. vaccinii that are allochronically isolated by the phenological stage of their respective host plants (cranberries or blueberries). Laboratory‐reared A. vaccinii adults collected from blueberries emerge at least 1 week earlier than adults from cranberries and the antennal sensitivity of adults to host‐plant volatiles differs between A. vaccinii collected from blueberry and cranberry. Despite finding characteristics indicative of HAD, we did not detect a genetic signature of HAD in A. vaccinii. These findings suggest that HAD may occur through behavioral and phenological mechanisms before there is sufficient genetic variation to be detected.     

Genetic structure of cherry fruit fly (Rhagoletis cingulata) populations across managed,unmanaged, and natural habitats

The cherry fruit fly (CFF), Rhagoletis cingulata Loew (Diptera: Tephritidae: Trypetini), is endemic to eastern North America and Mexico, where its primary native host is black cherry [Prunus serotina Ehrh. (Rosaceae)]. Cherry fruit fly is also a major economic pest of the fruit of cultivated sweet (Prunus avium L.) and tart (Prunus cerasus L.) cherries. Adult CFF that attack wild black cherry and introduced, domesticated cherries in commercial and abandoned orchards are active at different times of the summer, potentially generating allochronic isolation that could genetically differentiate native from sweet and tart CFF populations. Here, we test for host‐related genetic differences among CFF populations in Michigan attacking cherries in managed, unmanaged, and native habitats by scoring flies for 10 microsatellite loci. Little evidence for genetic differentiation was found across the three habitats or between the northern and southern Michigan CFF populations surveyed in the study. Local gene flow between native black cherry, commercial, and abandoned orchards may therefore be sufficient to overcome seasonal differences in adult CFF activity and prevent differentiation for microsatellites not directly associated with (tightly linked to) genes affecting eclosion time. The results do not support the existence of host‐associated races in CFF and imply that flies attacking native, managed, and unmanaged cherries should be considered to represent a single population for pest management purposes.     

The role of ESCRT proteins in fusion events involving lysosomes, endosomes and autophagosomes

ESCRT (endosomal sorting complex required for transport) proteins were originally identified for their role in delivering endocytosed proteins to the intraluminal vesicles of late-endosomal structures termed multivesicular bodies. Multivesicular bodies then fuse with lysosomes, leading to degradation of the internalized proteins. Four ESCRT complexes interact to concentrate cargo on the endosomal membrane, induce membrane curvature to form an intraluminal bud and finally pinch off the bud through a membrane-scission event to produce the intraluminal vesicle. Recent work suggests that ESCRT proteins are also required downstream of these events to enable fusion of multivesicular bodies with lysosomes. Autophagy is a related pathway required for the degradation of organelles, long-lived proteins and protein aggregates which also converges on lysosomes. The proteins or organelle to be degraded are encapsulated by an autophagosome that fuses either directly with a lysosome or with an endosome to form an amphisome, which then fuses with a lysosome. A common machinery is beginning to emerge that regulates fusion events in the multivesicular body and autophagy pathways, and we focus in the present paper on the role of ESCRT proteins. These fusion events have been implicated in diseases including frontotemporal dementia, Alzheimer's disease, lysosomal storage disorders, myopathies and bacterial pathogen invasion, and therefore further examination of the mechanisms involved may lead to new insight into disease pathogenesis and treatments.     

FGF4 regulates blood and muscle specification in Xenopus laevis

BACKGROUND INFORMATION: FGF (fibroblast growth factor) signalling is known to be required for many aspects of mesoderm formation and patterning during Xenopus development and has been implicated in regulating genes required for the specification of both blood and skeletal muscle lineages. RESULTS: In the present study, we have specifically knocked down the expression of FGF4 using AMO (antisense morpholino oligonucleotide)-mediated inhibition and demonstrate that FGF4 acts in the dorsal marginal zone to restrict blood development and promote the development of skeletal muscle. In addition, we used a drug inhibitor of FGF signalling and an inducible form of FGFR1 (FGF receptor 1) to identify a period of competence during late blastula and gastrula stages when FGF signalling acts to regulate blood versus muscle specification. Notably, we found that it is the dorsal activity of FGF that is required to restrict the expression of SCL (stem cell leukaemia) to the ventral blood island. CONCLUSIONS: Our data indicate that FGF4 is a key organizer-derived signal involved in the process of dorsoventral patterning of the mesoderm.     

Molecular characterisation of a candidate gut sucrase in the pea aphid, Acyrthosiphon pisum

The hydrolysis of sucrose, the principal dietary source of carbon for aphids, is catalysed by a gut alpha-glucosidase/transglucosidase activity. An alpha-glucosidase, referred to as APS1, was identified in both a gut-specific cDNA library and a sucrase-enriched membrane preparation from guts of the pea aphid Acyrthosiphon pisum by a combination of genomic and proteomic techniques. APS1 contains a predicted signal peptide, and has a predicted molecular mass of 68 kDa (unprocessed) or 66.4 kDa (mature protein). It has amino acid sequence similarity to alpha-glucosidases (EC 3.2.1.20) of glycoside hydrolase family 13 in other insects. The predicted APS1 protein contains two domains: an N-terminal catalytic domain, and a C-terminal hydrophobic domain. In situ localisation and RT-PCR studies revealed that APS1 mRNA was expressed in the gut distal to the stomach, the same localisation as sucrase activity. When expressed heterologously in Xenopus embryos, APS1 was membrane-bound and had sucrase activity. It is concluded that APS1 is a dominant, and possibly sole, protein mediating sucrase activity in the aphid gut.     

Plasmodesmata‐located protein overexpression negatively impacts the manifestation of systemic acquired resistance and the long‐distance movement of Defective in Induced Resistance1 in Arabidopsis

Systemic acquired resistance (SAR) is a plant defence response that provides immunity to distant uninfected leaves after an initial localised infection. The lipid transfer protein (LTP) Defective in Induced Resistance1 (DIR1) is an essential component of SAR that moves from induced to distant leaves following a SAR‐inducing local infection. To understand how DIR1 is transported to distant leaves during SAR, we analysed DIR1 movement in transgenic Arabidopsis lines with reduced cell‐to‐cell movement caused by the overexpression of Plasmodesmata‐Located Proteins PDLP1 and PDLP5. These PDLP‐overexpressing lines were defective for SAR, and DIR1 antibody signals were not observed in phloem sap‐enriched petiole exudates collected from distant leaves. Our data support the idea that cell‐to‐cell movement of DIR1 through plasmodesmata is important during long‐distance SAR signalling in Arabidopsis.