Binding of pigment epithelium-derived factor (PEDF) to retinoblastoma cells and cerebellar granule neurons. Evidence for a PEDF receptor.

Pigment epithelium-derived factor (PEDF) has neuronal differentiation and survival activity on retinoblastoma and cerebellar granule (CG) cells. Here, we investigated the presence of PEDF receptors on retinoblastoma Y-79 and CG cells. PEDF radiolabeled with (l25)I remained biologically active and was used for radioligand binding analysis. The binding was saturable and specific to a single class of receptors on both cells and with similar affinities (K(d) = 1.7-3.6 nM, B(max) = 0.5-2.7 x 10(5) sites/Y-79 cell; and K(d) = 3.2 nM, B(max) = 1.1 x 10(3) sites/CG cell). A polyclonal antiserum to PEDF, previously shown to block the PEDF neurotrophic activity, prevented the (125)I-PEDF binding. We designed two peptides from a region previously shown to confer the neurotrophic property to human PEDF, synthetic peptides 34-mer (positions 44-77) and 44-mer (positions 78-121). Only peptide 44-mer competed for the binding to Y-79 cell receptors (EC(50) = 5 nM) and exhibited neuronal differentiating activity. PEDF affinity column chromatography of membrane proteins from both cell types revealed a PEDF-binding protein of approximately 80 kDa. These results are the first demonstration of a PEDF-binding protein with characteristics of a PEDF receptor and suggest that the region comprising amino acid positions 78-121 of PEDF might be involved in ligand-receptor interactions.     

Structure of the tail fin in teleosts

The influence of adrenalectomy and administration of hypertonic saline on the amount of vasopressin, oxytocin, and neurophysin contained in the median eminence and the neural lobe of rats was studied by means of the following methods: (i) morphometric and microphotometric analyses of aldehyde fuchsin-stained histological sections of the neurohypophysis; (ii) immunohistochemical demonstration of vasopressin, oxytocin, and neurophysin in the neurohypophysis, and (iii) radioimmunological measurement of vasopressin and oxytocin in extracts of the median eminence and the neural lobe. Adrenalectomy increases the amount of vasopressin and neurophysin in the external layer of the median eminence but does not change the content of oxytocin. It has no influence on the amount of vasopressin, oxytocin, and neurophysin demonstrable in the inner layer of the median eminence and in the neural lobe two weeks after the operation. Hypertonic saline markedly diminishes the vasopressin, oxytocin, and neurophysin content of the inner layer of the median eminence and the neural lobe but reduces only slightly, if at all, the amount of vasopressin and neurophysin in the outer layer of the median eminence. The findings support the concept that osmotic stress reduces only the vasopressin and oxytocin content of the hypothalamus-neural lobe system and has no or only little influence on the vasopressin content of the outer layer of the median eminence.     

Distribution,causal agents,and infection dynamic of emerging ink disease of sweet chestnut in Southern Switzerland

Emerging diseases caused by both native and exotic pathogens represent a main threat to forest ecosystems worldwide. The two invasive soilborne pathogens Phytophthora cinnamomi and Phytophthora × cambivora are the causal agents of ink disease, which has been threatening Castanea sativa in Europe for several centuries and seems to be re-emerging in recent years. Here, we investigated the distribution, causal agents, and infection dynamics of ink disease in southern Switzerland. A total of 25 outbreaks were identified, 19 with only P. cinnamomi, 5 with only P. × cambivora, and 1 with both species. Dendrochronological analyses showed that the disease emerged in the last 20–30 years. Infected trees either died rapidly within 5–15 years post-infection or showed a prolonged state of general decline until death. Based on a generalized linear model, the local risk of occurrence of ink disease was increased by an S-SE aspect of the chestnut stand, the presence of a pure chestnut stand, management activities, the proximity of roads and buildings, and increasing annual mean temperature and precipitation. The genetic structure of the local P. cinnamomi population suggests independent introductions and local spread of the pathogen.     

Recombinant human pigment epithelium-derived factor (PEDF): characterization of PEDF overexpressed and secreted by eukaryotic cells.

Pigment epithelium-derived factor (PEDF) is a serpin found in the interphotoreceptor matrix of the eye, which, although not a proteinase inhibitor, possesses a number of important biological properties, including promotion of neurite outgrowth and differential expression in quiescent versus senescent states of certain cell types. The low amounts present in the eye, together with the impracticality of using the eye as a source for isolation of the human protein, make it important to establish a system for overexpression of the recombinant protein for biochemical and biological studies. We describe here the expression and secretion of full-length glycosylated human recombinant PEDF at high levels (> 20 micrograms/ mL) into the growth medium of baby hamster kidney cells and characterization of the purified rPEDF by circular dichroism and fluorescence spectroscopies and neurite outgrowth assay. By these assays, the recombinant protein behaves as expected for a correctly folded full-length human PEDF. The availability of milligram amounts of PEDF has permitted quantitation of its heparin binding properties and of the effect of reactive center cleavage on the stability of PEDF towards thermal and guanidine hydrochloride denaturation.     

Insertion mutations at the maizeOpaque2 locus induced by transposable element familiesAc, En/Spm andBg

Eight independently isolated unstable alleles of theOpaque2 (O2) locus were analysed genetically and at the DNA level. The whole series of mutations was isolated from a maize strain carrying a wild-typeO2 allele and the transposable elementActivator (Ac) at thewx-m7 allele. Previous work with another unstable allele of the same series has shown that it was indeed caused by the insertion of anAc element. Unexpectedly, the remaining eight mutations were not caused by the designatedAc element, but by other insertions that are structurally similar or identical to one of two different autonomous transposable elements. Six mutations were caused by the insertion of a transposable element of theEnhancer/Suppressor-Mutator (En/Spm) family. Two mutations were the result of the insertion of a transposable element of theBergamo (Bg) family. Genetic tests carried out with plants carrying the unstable mutations demonstrated that all were caused by the insertion of an autonomous transposable element.     

The origin of a novel gene through overprinting in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Background  

Overlapped genes originate by a) loss of a stop codon among contiguous genes coded in different frames; b) shift to an upstream initiation codon of one of the contiguous genes; or c) by overprinting, whereby a novel open reading frame originates through point mutation inside an existing gene. Although overlapped genes are common in viruses, it is not clear whether overprinting has led to new genes in prokaryotes.     

Diverging patterns of host use by phytophagous insects in relation to leaf pubescence in Arbutus xalapensis (Ericaceae)

Summary Foliar pubescence in the mexican madrone (Arbutus xalapensis H.B.K.) is an extremely variable character. Leaf specimens of pilose and glabrous madrones showed a similar composition of major secondary compounds. On the other hand, sympatric pilose and glabrous individuals were found to support significantly different insect guilds. Insect preference was strongly associated to mouthpart anatomy. Chewing and gall-forming insects were significantly more abundant on glabrous trees while sucking insects were more common on pilose trees. Additionally, parasitation of sucking insects was lower on pilose trees, possibly because the plant trichomes provide protection against parasitoids.     

Comparison of biodiversity and ground cover between a commercial rotationally grazed property and an adjacent nature reserve in semi‐arid rangeland

Continuous livestock grazing can have negative effects on biodiversity and landscape function in arid and semi‐arid rangelands. Alternative grazing management practices, such as rotational grazing, may be a viable option for broad‐scale biodiversity conservation and sustainable pastoral management. This study compared ground cover, plant species composition and floristic and functional diversity along gradients of grazing intensity between a pastoral property rotationally grazed by goats and an adjacent nature reserve (ungrazed by commercial livestock) in semi‐arid south‐eastern Australia. Understorey plant species composition differed significantly between the rotationally grazed property and the nature reserve, with a greater proportion and frequency of palatable species recorded in the nature reserve. Understorey plant species richness, diversity, functional biodiversity measures and ground cover declined with increasing grazing pressure close to water points under commercial rotational grazing management. However, at a whole‐paddock scale, there were few differences in plant biodiversity and ground cover between the rotationally grazed property and the nature reserve, despite differences in overall plant species composition. Flexible, adaptive, rotational grazing should be investigated further for its potential to achieve both socio‐economic and biodiversity conservation outcomes in semi‐arid rangelands to complement existing conservation reserves.