Associations between White Matter Hyperintensities and β Amyloid on Integrity of Projection,Association, and Limbic Fiber Tracts Measured with Diffusion Tensor MRI

The goal of this study was to assess the relationship between Aβ deposition and white matter pathology (i.e., white matter hyperintensities, WMH) on microstructural integrity of the white matter. Fifty-seven participants (mean age: 78±7 years) from an ongoing multi-site research program who spanned the spectrum of normal to mild cognitive impairment (Clinical dementia rating 0–0.5) and low to high risk factors for arteriosclerosis and WMH pathology (defined as WMH volume >0.5% total intracranial volume) were assessed with positron emission tomography (PET) with Pittsburg compound B (PiB) and magnetic resonance and diffusion tensor imaging (DTI). Multivariate analysis of covariance were used to investigate the relationship between Aβ deposition and WMH pathology on fractional anisotropy (FA) from 9 tracts of interest (i.e., corona radiata, internal capsule, cingulum, parahippocampal white matter, corpus callosum, superior longitudinal, superior and inferior front-occipital fasciculi, and fornix). WMH pathology was associated with reduced FA in projection (i.e., internal capsule and corona radiate) and association (i.e., superior longitudinal, superior and inferior fronto-occipital fasciculi) fiber tracts. Aβ deposition (i.e., PiB positivity) was associated with reduced FA in the fornix and splenium of the corpus callosum. There were interactions between PiB and WMH pathology in the internal capsule and parahippocampal white matter, where Aβ deposition reduced FA more among subjects with WMH pathology than those without. However, accounting for apoE ε4 genotype rendered these interactions insignificant. Although this finding suggests that apoE4 may increase amyloid deposition, both in the parenchyma (resulting in PiB positivity) and in blood vessels (resulting in amyloid angiopathy and WMH pathology), and that these two factors together may be associated with compromised white matter microstructural integrity in multiple brain regions, additional studies with a longitudinal design will be necessary to resolve this issue.     

Survival of inoculated Laccaria bicolor in competition with native ectomycorrhizal fungi and effects on the growth of outplanted Douglasfir seedlings

The survival, development and mycorrhizal efficiency of a selected strain of Laccaria bicolor along with naturally occurring ectomycorrhizal fungi in a young plantation of Douglas fir was examined. Symbionts were identified and their respective colonization abilities were determined. Eight species of symbiotic fungi, which may have originated in adjacent coniferous forests, were observed on the root systems. Mycorrhizal diversity differed between inoculated (5 taxa) and control (8 taxa) seedlings. Ectomycorrhizal fungi which occurred naturally in the nursery on control seedlings (Thelephora terrestris and Suillus sp.) did not survive after outplanting. Both inoculated and naturally occurring Laccaria species, as well as Cenococcum geophilum, survived on the old roots and colonized the newly formed roots, limiting the colonization by other naturally occurring fungi. Other fungi, such as Paxillus involutus, Scleroderma citrinum and Hebeloma sp. preferentially colonized the old roots near the seedling's collar. Russulaceae were found mainly in the middle section of the root system. Mycorrhizal colonization by Laccaria species on inoculated seedlings (54%) was significantly greater than on controls (13%) which were consequently dominated by the native fungi. Significant differences (up to 239%) were found in the growth of inoculated seedlings, especially in root and shoot weight, which developed mainly during the second year after outplanting. Seedling growth varied with the species of mycorrhizae and with the degree of root colonization. Competitiveness and effectiveness of the introduced strain on improving growth performances of seedlings are discussed.     

Stability of Bradyrhizobium japonicum Inoculants after Introduction into Soil

Bradyrhizobium japonicum USDA 125-Sp, USDA 138, and USDA 138-Sm had been used as inoculants for soybean (Glycine max (L.) Merr.) in soils previously free of B. japonicum. At 8 to 13 years after their release, these strains were reisolated from soil samples. A total of 115 isolates were obtained through nodules, and seven colonies were obtained directly by a serological method. The stability of the inoculants was confirmed by comparing the reisolated cultures with their respective parental strains which had been preserved by being lyophilized or stored on a yeast extract-mannitol agar slant at 4°C. Comparisons were made on morphological and serological characters, carbon compound utilization (8 tested), intrinsic antibiotic resistance (9 tested), and enzymatic activity (19 tested). Mucous and nonmucous isolates of serogroup 125 were analyzed for symbiotic effectiveness and restriction fragment hybridization with a DNA probe. Our data suggest that the B. japonicum inoculants have survived for up to 13 years in the soils without significant mutation except for two reisolates with a slightly increased kanamycin resistance level.     

Characterization of dog platelet alpha-adrenergic receptor: lack of in vivo down regulation by adrenergic agonist treatments

The dog platelet alpha-adrenergic receptor was characterized using [3H]clonidine and [3H]yohimbine. The binding of both radioligands was rapid and reversible at 25 degrees C; saturation and kinetic experiments revealed a single population of binding sites. The number of [3H]yohimbine sites was 2-3-fold higher than the number of [3H]clonidine sites as reported in other tissues containing alpha2-adrenoceptors. The various alpha-agonists and antagonists displaced [3H]clonidine and [3H]yohimbine with an order of potency indicating alpha2-adrenoceptor specificity. Neither (-)adrenaline nor clonidine infusions (0.5 micrograms/min/kg during 3 hr) modified the number of [3H]yohimbine and [3H]clonidine sites or the affinity of the ligands for the alpha2-sites of the dog platelet. Oral administration of clonidine (3 X 150 micrograms/day) did not alter the binding parameters of either ligand.     

Plasmids in Frankia sp.

A method to achieve cell lysis and isolate Frankia sp. plasmid DNA was developed. A screening of Frankia sp. strains belonging to different host compatibility groups (Alnus sp., Elaeagnus sp., Ceanothus sp.) showed that, of 39 strains tested, 4 (strains Cp11, ARgN22d, ArI3, and EUN1f) possessed plasmids ranging in size from 7.1 to 32.2 kilobase pairs as estimated from agarose gel electrophoresis and electron microscopy. A total of 11 plasmids were detected.     

Genetic and Developmental Analysis of the Locus vnd in DROSOPHILA MELANOGASTER

Genetic and developmental analysis of an X-linked vital locus vnd was undertaken. Embryos hemizygous for the original allele vnd did not hatch and exhibited a disorganized ventral nervous system (VNS). The mutation maps in the region 1B6-7 to 1B9-10, a subregion of an area previously shown to be essential to normal neural development. In this paper, we report isolation of five new alleles at the locus vnd. Genetic complementation analysis of all mutations at the vnd locus, with lethal alleles at adjacent loci, indicates that all lesions at the locus vnd affect only one vital gene function in the region. Four of the five alleles are embryonic lethal; one allele is subvital and behaves like an hypomorphic mutation. Hemizygous embryos for three of the four embryonic lethal alleles were inspected in histological sections; all exhibited disorganized VNS similar to the original allele. The developmental analysis in gynandromorphic genetic mosaics shows that (1) vnd+ gene function is not essential in most imaginal-disc cell derivatives, (2) only about 30% of the mosaic zygotes survive as adults, (3) mosaic zygotes with mutant tissue close to the head cuticle are least likely to survive, and (4) mutant tissue in the thoracic ganglion in the adult is not necessarily lethal. The mosaic data are consistent with the vnd+ gene function being necessary in neural cells derived from the anterioventral region of the blastoderm.     

Cloning and expression of a glucoamylase gene from Lactobacillus amylovorus ATCC 33621 in Escherichia coli

Summary The glucoamylase gene from Lactobacillus amylovorus was cloned and expressed in Escherichia coli. A genomic DNA library from Lactobacillus amylovorus was prepared by partially digesting genomic DNA with EcoRI and ligating random fragments to the EcoRI digested cloning vector, pZErO-1.1. Three E. coli transformants expressing glucoamylase were identified using a probe prepared from the STA2 glucoamylase gene from Saccharomyces cerevisiae var. diastaticus. The physical maps of the recombinant plasmids were constructed. These plasmids contained inserts of about 5.2 Kb, 5.9 Kb and 6.4 Kb respectively. Temperature and pH optima of 45°C and 6.0, respectively, were obtained for both recombinant and purified wild type glucoamylases. Also, the enzymes were found to be thermolabile at temperatures above 50°C.