Creating landscape patterns by forest cutting: Ecological consequences and principles

Landscape structural characteristics, such as patch size, edge length, and configuration, are altered markedly when management regimes are imposed on primeval landscapes. The ecological consequences of clearcutting patterns were explored by using a model of the dispersed patch or checkerboard system currently practiced on federal forest lands in the western United States. Thresholds in landscape structure were observed on a gradient of percentages of landscape cutover. Probability of disturbance,e.g., wildfire and windthrow, and biotic components,e.g., species diversity and game populations, are highly sensitive to these structural changes. Altering the spatial configuration and size of clearcuts provides an opportunity to create alternative landscapes that differ significantly in their ecological characteristics. Both ecosystem and heterogeneous landscape perspectives are critical in resource management.     

A double-blinded placebo-controlled evaluation of adipose-derived mesenchymal stem cells in treatment of canine atopic dermatitis

Mesenchymal stem cells (MSCs) have emerged as a new therapy for various immune-mediated inflammatory diseases. In this study we perform the first double-blinded, placebo-controlled evaluation of the efficacy of adipose-derived allogenic canine MSCs for the treatment of canine atopic dermatitis (cAD). Enrolled canine patients were randomly divided into placebo (PBS saline), low-dose (5?×?10⁵ cells/kg), and high-dose (5?×?10⁶ cells/kg) treatment groups. Each patient received three subcutaneous MSCs treatments or PBS saline at four-week intervals with injections at five sites. Patients were monitored by physical exams, pruritus visual analog scales (PVAS) signed by the primary caretaker, canine atopic dermatitis extent and severity index-4 (CADESI-4) scores by two veterinarians, and complete blood count and serum chemistry analysis along with laboratory analysis for potential biomarkers. Patients were kept off any immune-modulating drugs during the study period, and oral antibiotics and topicals were used for managing pruritus and secondary infections. The PVAS scores and the serum miR-483 levels were significantly lower in the high dose group compared to the placebo group at day90 post first-treatment. The CADESI-4 scores of the high dose group also showed downward trends. No severe adverse effects were observed in any patient in this study. The high dose MSC treatment is efficacious in alleviating the clinical signs of cAD until 30 days after the last subcutaneous administration of MSCs, and miRNA-483 may be a reliable prognostic biomarker for cAD. The MSCs efficacy and potential biomarkers should be further explored by a larger scale clinical trial.

     

Marinopyrrole Derivatives as Potential Antibiotic Agents against Methicillin-Resistant Staphylococcus aureus (III)

The marine natural product, marinopyrrole A (1), was previously shown to have significant antibiotic activity against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). Although compound (1) exhibits a significant reduction in MRSA activity in the presence of human serum, we have identified key modifications that partially restore activity. We previously reported our discovery of a chloro-derivative of marinopyrrole A (1a) featuring a 2–4 fold improved minimum inhibitory concentration (MIC) against MRSA, significantly less susceptibility to serum inhibition and rapid and concentration-dependent killing of MRSA. Here, we report a novel fluoro-derivative of marinopyrrole A (1e) showing an improved profile of potency, less susceptibility to serum inhibition, as well as rapid and concentration-dependent killing of MRSA.     

The release of methyl chloride from potato tubers

Freshly harvested Norchip and Kennebec tubers release varied amounts of methyl chloride (CH₃Cl) during suberization. Maximum rates of CH₃Cl release, ranging from 98-690 ng CH₃Cl/kg tubers/hr under laboratory and commercial conditions, were attained 2–3 days following harvest. Release rates thereafter decreased 10-40-fold by the 7th day of suberization. The period of rapid decrease in CH₃Cl release corresponds to the reported time required by cut tuber tissue to initiate resistance to water loss. Cutting of newly harvested and suberized Kennebec tubers reestablished the high release rates of CH₃Cl measured during the early stages of suberization. The enhancement of CH₃Cl release by tissue cutting was not demonstrated by two varieties stored for 10 months. Suberization differences between early and late harvested Norchip tubers were better differentiated by their respective rates of CH₃Cl release than by CO₂ generation. These preliminary findings suggest the rate of CH₃Cl release could be applied to assess harvest damage and monitor the suberization process. Methyl chloride has previously been reported as the major nonindustrial chlorocarbon in the atmosphere that is linked to a replenishable, natural source.     

The nonsusceptibility of soil Collembola to insect pathogens and their potential as scavengers of microbial pesticides

Collembola are very abundant soil insects which contribute to the decomposition of organic matter. This paper presents data on the interaction between Collembola and selected microbial agents being tested or used as biological pesticides. The Collembolan, Folsomia candida, was not susceptible to the entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae, Hirsutella spp., and Verticillium lecanii, or to the bacterium, Bacillus thuringiensis, and its endotoxins. F. candida consumed and inactivated the insect pathogens without suffering mortality, reproductive disturbance or any other harmful effects. Consumption of insect pathogens demonstrates the potential of the Collembola as scavengers of biological insecticides artificially introduced into the environment.     

Aluminum toxicity and high bulk density: Role in limiting shoot and root growth of selected aluminum indicator plants and eastern gamagrass in an acid soil

Abstract

Shallow rooting and susceptibility to drought are believed to be caused, at least in part, by strongly acidic (pH <5.5, 1:1 soil‐water), aluminum (Al)‐toxic subsoils. However, this hypothesis has not been clearly confirmed under field conditions. The Al toxicity hypothesis was tested on a map unit of Matawan‐Hammonton loam (0–2% slope) on unlimed and limed field plots (pH range 5.1 to 5.8) at Beltsville, MD, during 1994 to 1998. Aluminum‐tolerant and sensitive pairs of barley (Hordeum vulgare L.), wheat [Triticum aestivum (L.)], snap bean (Phaseolus vulgaris L.), and soybean [Glycine max (L.) Merr.] cultivars were used as indicator plants. Eastern gamagrass [Tripsacum dactyloides (L.) L.], cultivar ‘Pete’, reported to tolerate both chemical and physical stress factors in soils, was grown for comparison. Shoots of Al‐sensitive ‘Romano’ snap beans showed a significant response to liming of the 0–15 cm surface layer, but those of Al‐tolerant ‘Dade’ did not, indicating that Al toxicity was a growth limiting factor in this acid soil at pH 5.1. Lime response of the Al‐tolerant and sensitive cultivars of barley, wheat, and soybean were in the same direction but not significant at the 5% level. Aluminum‐tolerant and sensitive cultivars did not differ in abilities to root in the 15–30 cm soil depth. Only 9 to 25% of total roots were in this layer, and 75 to 91% were in the 0–15 cm zone. No roots were found in the 30–45 cm zone which had a pH of 4.9. Soil bulk density values of 1.44 and 1.50 g cm^?3 in the 15–30 and 30–45 cm zones, respectively, indicated that mechanical impedance was a primary root barrier. Results indicated that restricted shoot growth and shallow rooting of the Al‐indicator plants studied in this acid soil were due to a combination of Al toxicity and high soil bulk density. Confounding of the two factors may have masked the expected response of indicator plants to Al. These two growth restricting factors likely occur in many, if not most acid, problem subsoils. Studies are needed to separate these factors and to develop plant genotypes that have tolerance to multiple abiotic stresses. Unlike the Al indicator cultivars, eastern gamagrass showed high tolerance to acid, compact soils in the field and did not respond to lime applications (pH 5.1–5.8).     

A hybrid swarm population of Pinus densiflora × P. sylvestris inferred from sequence analysis of chloroplast DNA and morphological characters

To confirm a hybrid swarm population of Pinus densiflora × P. sylvestris in Jilin, China, we used needles and seeds from P. densiflora, P. sylvestris, and P. densiflora × P. sylvestris collected from natural stands or experimental stations to study whether shoot apex morphology of 4- year old seedlings can be correlated with the sequence of a chloroplast DNA simple sequence repeat marker (cpDNA SSRs). Total genomic DNA was extracted and subjected to sequence analysis of the pine cpDNA SSR marker Pt15169. Results show that morphological characters from 4-year old seedlings did not correlate with sequence variants of this marker. Marker haplotypes from all P. sylvestris trees had a CTAT element that was absent from all sampled P. densiflora trees. However, both haplotype classes involving this insertion/deletion element were found in a P. densiflora × P. sylvestris population and its seedling progeny. It was concluded that the P. densiflora × P. sylvestris accessions sampled from Jilin, China resulted from bi-directional crosses, as evidenced by both species’ cpDNA haplotypes within the hybrid swarm population.     

Identification and mapping of adult‐plant stripe rust resistance in soft red winter wheat cultivar ‘USG 3555’

Little is known about the extent or diversity of resistance in soft red winter wheat (Triticum aestivum L.) to stripe rust, caused by the fungal pathogen Puccinia striiformis f.sp. tritici. The soft red winter (SRW) wheat cultivar ‘USG 3555’ has effective adult‐plant resistance to stripe rust, which was characterized in a population derived from ‘USG 3555’/‘Neuse’. The mapping population consisted of 99 recombinant inbred lines, which were evaluated for stripe rust infection type (IT) and severity to race PST‐100 in field trials in North Carolina in 2010 and 2011. Genome‐wide molecular‐marker screenings with 119 simple sequence repeats and 560 Diversity Arrays Technology (DArT) markers were employed to identify quantitative trait loci (QTL) for stripe rust resistance. QTL on chromosomes 1AS, 4BL and 7D of ‘USG 3555’ explained 12.8, 73.0 and 13.6% of the variation in stripe rust IT, and 13.5, 72.3 and 10.5% of the variation in stripe rust severity, respectively. Use of these and additional diagnostic markers for these QTL will facilitate the introgression of this source of stripe rust resistance into SRW wheat lines via marker‐assisted selection.