Resistance to Striga hermonthica in a maize inbred line derived from Zea diploperennis

Breeding for resistance to Striga in maize (Zea mays), with paucity of donor source and known mechanisms of resistance, has been challenging. Here, post-attachment development of S. hermonthica was monitored on two maize inbreds selected for field resistance and susceptibility reactions to Striga at the International Institute of Tropical Agriculture. Haustorial invasion of the parasite into roots of these inbreds was examined histologically. Morphological differences were observed between roots of the susceptible and the resistant inbreds. The resistant maize had fewer Striga attachments, delayed parasitic development and higher mortality of attached parasites compared with the susceptible inbred. Striga on the susceptible inbred usually penetrated the xylem and showed substantial internal haustorial development. Haustorial ingress on the resistant inbred was often stopped at the endodermis. Parasites able to reach resistant host xylem vessels showed diminished haustorial development relative to those invading susceptible roots. These results suggest that the resistant inbred expresses a developmental barrier and incompatible response against Striga parasitism.     

Effects of taurine on the reactivity of aortas from diabetic rats

The effects of the semi-essential amino acid-like nutrient, taurine, on alterations in the reactivities of aortas from male rats with chronic streptozotocin-induced diabetes were examined under in vitro conditions. In the absence of taurine, the contractile responsiveness of endothelium-denuded aortic rings from diabetic rats to norepinephrine, but not KCl, was enhanced compared to controls. This effect of norepinephrine on the diabetic rat aorta appeared to be associated with increased release of intracellular calcium, influx of extracellular calcium and protein kinase C-mediated responses. Incubation of endothelium-denuded aortic rings with 10 mM, but not 5 mM, taurine for 2 h reduced the augmented contractile responses of the tissues from diabetic rats to norepinephrine close to control levels, and this was associated with inhibition of responses linked to the release and influx of calcium, and protein kinase C activation. Endothelium-dependent relaxation of aortas from diabetic rats to acetylcholine was depressed relative to controls. This effect of diabetes was ameliorated close to control levels by incubating the tissues with 10 mM, but not 5 mM, taurine for 2 h. Incubation of nondiabetic rat aortic rings with 45 mM glucose for 3 h caused enhancement of contraction of the vascular smooth muscle to phenylephrine and impairment of endothelium-mediated vasorelaxation to acetylcholine, as compared to control responses. Co-incubation of the tissues with 5-10 mM taurine concentration-dependently reduced the alterations in both contractile and relaxant responses caused by high glucose. Overall, the data suggest that taurine ameliorates or prevents vascular reactivity alterations in diabetes. Such an observation provides preliminary evidence for taurine's potential as a therapeutic agent for the prevention or amelioration of vascular disorders in diabetes.     

Lung-stage protein profile and antigenic relationship between Ascaris lumbricoides and Ascaris suum

The protein profile and antigenic properties of lung-stage larvae of Ascaris lumbricoides and A. suum were studied using 2-dimensional electrophoresis and immunoblot analysis, respectively. The protein profiles of the 2 parasites were identical except for the presence of only 1 major protein spot specific for each. There was a complete cross-reactivity between the 2 parasites at the immunological level, and no specific antigen was recognized using specific antibody raised against the 2 parasites in rabbits.     

Molecular barcodes for soil nematode identification

Using a molecular barcode, derived from single-specimen polymerase chain reaction (PCR) and sequencing of the 5' segment of the small subunit ribosomal RNA (SSU) gene, we have developed a molecular operational taxonomic unit (MOTU) scheme for soil nematodes. Individual specimens were considered to belong to the same MOTU when the sequenced segment of 450 bases was > 99.5% identical. A Scottish upland Agrostis-Festuca grassland soil was sampled, using both culture-based and random selection methods. One hundred and sixty-six cultured isolates were sequenced, and clustered into five MOTU. From 74 randomly sampled individuals across the study site, 19 MOTU were defined. A subsequent sample of 18 individuals from a single subplot contained eight MOTU, four of which were unique to the single subplot sample. Interestingly, seven of these MOTU were not present in the culture-independent sampling. Overall, a total of 23 MOTU were defined from only 240 sequences. Many MOTU could readily be assigned to classical, morphologically defined taxonomic units using a database of SSU sequences from named nematode species. The MOTU technique allows a rapid assessment of nematode taxon diversity in soils. Correlation with a database of sequences from known species offers a route to application of the technique in ecological surveys addressing biological as well as genetic diversity.     

Identification and quantification of histidine-rich glycoprotein (HRG) in the blood plasma of six marine bivalves

Histidine-rich Glycoprotein (HRG) is a metal-binding protein described from the blood plasma of a pteriomorph bivalve, the marine mussel Mytilus edulis L. We demonstrate here, using Cd-Immobilized Metal Affinity Chromatography (IMAC), SDS-PAGE, Western Blotting, and ELISA, that HRG is present in three additional pteriomorphs and two heterodont bivalves. ELISA indicates that HRG is the predominant blood plasma protein in all six species (41 to 61% of total plasma proteins by weight). Thus, HRG appears to be a widespread metal-binding protein in the plasma of bivalves.     

Allergenic and mutagenic characterization of 14 <Emphasis Type="Italic">Penicillium</Emphasis> species

Extracts of 14 Penicillium species, P. aurantiogriseum, P. brevicompactum, P. citrinum, P. chrysogenum, P. expansum, P. glabrum, P. hirsutum, P. italicum, P. janthinellum, P. melini, P. oxalicum, P. purpurescens, P. simplicissimum, and P. viridicatum were investigated by total protein, specific enzyme determinations, isoelectric focusing (IEF), sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting using pooled human atopic IgE. Considerable variation was observed between the Penicillium species with respect to protein yield and the number of distinct protein bands resolved in IEF. Using the Api-Zym system, the most common activities observed among the extracts included acid and alkaline phosphatase, phosphodiamidase and β-glucosaminidase. The number of discrete atopic IgE-reactive bands in immunoblots of Penicillium extracts ranged from 1 (P. chrysogenum) to 9 (P. viridicatum). Certain allergens showed potential for cross-reactivity between species, including 52 and 54 kDa proteins in P. citrinum, P. purpurescens, P. viridicatum and 40 kDa proteins in several species. The extracts were also nonmutagenic when tested with the Ames assay using Salmonella strains TA98 and TA100. The results tend to indicate that P. viridicatum, P. janthinellum, P. oxalicum, P. brevicompactum and P. italicum, which are highly immunogenic as well as allergenic, could possibly be good candidates for allergen cloning studies through the construction of cDNA libraries. The extracts were non-mutagenic and can be used safely for skin testing.*Presented in part at the 7th International meeting of Aerobiology, Montebello, August, 2002.     

Phenotypic and genotypic comparisons of CCR5- and CXCR4-tropic human immunodeficiency virus type 1 biological clones isolated from subtype C-infected individuals

Individuals infected with human immunodeficiency virus type 1 (HIV-1) subtype C infrequently harbour X4 viruses. We studied R5 and X4 biological clones generated from HIV-1 subtype C-infected individuals. All subtype C R5 viruses demonstrated slower profiles of replication on CD4⁺ lymphocytes in comparison to subtype B viruses, whereas subtype C X4 viruses replicated with comparable efficiency to subtype B X4 viruses. No differences were identified in CC or CXC chemokine inhibitions (RANTES and SDF-1α, respectively) between subtype C and subtype B viruses. Immature dendritic cells were shown in coculture experiments to similarly enhance the infection of subtype C and subtype B R5 as well as X4 viruses. By amino acid sequence analysis, we showed that the R5 and X4 subtype C gp120 envelope gene alterations were similar to those for a switching subtype B virus, specifically with respect to the V3 charge and envelope N-linked glycosylation patterns. By phylogenetic analysis, we showed that one patient was infected with HIV-1 C′ and the other was infected with HIV-1 C" and that one of the patients harbored a virus that was a recombinant in the gp120 env gene between an R5 and an X4 virus, with the resultant virus being R5. No differences were identified between the long terminal repeat regions of the subtype C R5 and X4 biological clones. These results indicate that even though R5 subtype C viruses are restrictive for virus replication, the R5-to-X4 phenotype switch can occur and does so in a manner similar to that of subtype B viruses.     

Sesquiterpenes from Warburgia ugandensis and their antimycobacterial activity

The dichloromethane extract of the stem bark of Warburgia ugandensis afforded three new coloratane sesquiterpenes, namely: 6alpha,9alpha-dihydroxy-4(13),7-coloratadien-11,12-dial (1), 4(13),7-coloratadien-12,11-olide (2), and 7beta-hydroxy-4(13),8-coloratadien-11,12-olide (3), together with nine known sesquiterpenes, i.e., cinnamolide-3beta-acetate (4), muzigadial (5), muzigadiolide (6), 11alpha-hydroxymuzigadiolide (7), cinnamolide (8), 7alpha-hydroxy-8-drimen-11,12-olide (9), ugandensolide (10), mukaadial (11), ugandensidial (12), and linoleic acid (13). Their structures were assigned on the basis of 1D and 2D-NMR spectroscopic and GC-MS analysis. The compounds were examined for their antimycobacterial activity against Mycobacterium aurum, M. fortuitum, M. phlei and M. smegmatis; and the active constituents showed MIC values ranged from 4 to 128 microg/ml compared to the antibiotic drugs ethambutol (MIC ranged from 0.5 to 8 microg/ml) and isoniazid (MIC ranged from 1 to 4 microg/ml).     

A proximal upstream sequence controls tissue-specific expression of <Emphasis Type="Italic">Lem2</Emphasis>, a salicylate-inducible barley lectin-like gene

The lemma and palea (lemma/palea), which form the husk of barley (Hordeum vulgare L.) seeds, constitutively express high levels of defense-related genes, relative to leaves [Abebe et al. (2004) Crop Sci 44:942–950]. One of these genes, Lem2, is expressed mainly in the lemma/palea and coleoptile and is strongly upregulated by salicylic acid (SA) and its functional analog 2,6-dichloroisonicotinic acid . Induction by SA was rapid, occurring within 4 h of treatment. However, Lem2 is not responsive to methyl jasmonate (MeJA) or wounding and is downregulated by drought, dehydration, and abscisic acid. These results suggest that Lem2 is involved in systemic acquired resistance. Sequence analysis showed that LEM2 is a jacalin-related lectin (JRL)-like protein with two domains. Consistent with northern and western blot data, transient expression analyses using Lem2::gfp constructs showed strong expression in lemmas and a trace expression in leaves. Successive 5 deletions of the 1,414 bp upstream region gradually weakened promoter strength, as measured by real-time PCR. Promoter deletion studies also revealed that the –75/+70 region (containing the TATA box, 5 UTR, and a SA-response element) determines tissue specificity and that the distal promoter region simply enhances expression. Southern analysis indicated that Morex barley has at least three copies of the Lem2 gene arranged in tandem on chromosome 5(1H) Bin 02, near the short arm telomere. Lem2 is not present in the barley cultivars Steptoe, Harrington, Golden Promise, and Q21861.Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U. S. Department of Agriculture     

Bradyrhizobium japonicum Serocluster 123 and Diversity among Member Isolates

Diversity was examined within a group of 79 isolates of Bradyrhizobium japonicum reactive to fluorescent antibodies (FAs) prepared against B. japonicum USDA 123. Analyses were by means of cross-adsorbed FAs, bacteriophage typing, and endonuclease restriction digest patterns. Serogroups 127 and 129 shared antigenic determinants with serogroup 123 but not with each other. Bacteriophage and DNA digest patterns reflected more common features between serogroups 123 and 127 than between 123 and 129. Serogroups 129 and 122 showed FA cross-reactivity. The term serocluster was proposed to reflect interrelationships observed among the serogroups.