Purification, characterization and antimicrobial properties of an antibiotic (wassumycin) from Streptomyces species 215

A yellow amorphous compound, wassumycin, was isolated from an unidentified strain of Streptomyces. Wassumycin inhibited the growth of several species of human and animal pathogenic bacteria especially Clostridia. Wassumycin also inhibited the growth of HeLa cells, and showed good antitumour activity against experimental mouse tumours such as L1210, P388 leukaemias, and B16 melanoma. On the basis of the chemical and antimicrobial properties, the antibiotic appeared similar to the chromomycins and olivomycins, but its ultraviolet, infrared, and proton magnetic resonance spectra differed from theirs significantly.     

Plant Life History and Residue Chemistry Influences Emissions of CO2 and N2O From Soil – Perspectives for Genetically Modified Cell Wall Mutants

Vascular plants have lignified tissues that transport water, minerals, and photosynthetic products throughout the plant. They are the dominant primary producers in terrestrial ecosystems and capture significant quantities of atmospheric carbon dioxide (CO₂) through photosynthesis. Some of the fixed CO₂ is respired by the plant directly, with additional CO₂ lost from rhizodeposits metabolized by root-associated soil microorganisms. Microbially-mediated mineralization of organic nitrogen (N) from plant byproducts (rhizodeposits, dead plant residues) followed by nitrification generates another greenhouse gas, nitrous oxide (N₂O). In anaerobic soils, reduction of nitrate by microbial denitrifiers also produces N₂O. The plant-microbial interactions that result in CO₂ and N₂O emissions from soil could be affected by genetic modification. Down-regulation of genes controlling lignin biosynthesis to achieve lower lignin concentration or a lower guaiacyl:syringyl (G:S) ratio in above-ground biomass is anticipated to produce forage crops with greater digestibility, improve short rotation woody crops for the wood-pulping industry and create second generation biofuel crops with low ligno-cellulosic content, but unharvested residues from such crops are expected to decompose quickly, potentially increasing CO₂ and N₂O emissions from soil. The objective of this review are the following: 1) to describe how plants influence CO₂ and N₂O emissions from soil during their life cycle; 2) to explain how plant residue chemistry affects its mineralization, contributing to CO₂ and N₂O emissions from soil; and 3) to show how modification of plant lignin biosynthesis could influence CO₂ and N₂O emissions from soil, based on experimental data from genetically modified cell wall mutants of Arabidopsis thaliana. Conceptual models of plants with modified lignin biosynthesis show how changes in phenology, morphology and biomass production alter the allocation of photosynthetic products and carbon (C) losses through rhizodeposition and respiration during their life cycle, and the chemical composition of plant residues. Feedbacks on the soil environment (mineral N concentration, soil moisture, microbial communities, aggregation) affecting CO₂ and N₂O emissions are described. Down-regulation of the Cinnamoyl CoA Reductase 1 (CCR1) gene is an excellent target for highly digestable forages and biofuel crops, but A. thaliana with this mutation has lower plant biomass and fertility, prolonged vegetative growth and plant residues that are more susceptible to biodegradation, leading to greater CO₂ and N₂O emissions from soil in the short term. The challenge in future crop breeding efforts will be to select tissue-specific genes for lignin biosynthesis that meet commercial demands without compromising soil CO₂ and N₂O emission goals.     

Contrasting Role of Temperature in Structuring Regional Patterns of Invasive and Native Pestilential Stink Bugs

Objectives

Assessment and identification of spatial structures in the distribution and abundance of invasive species is important for unraveling the underlying ecological processes. The invasive agricultural insect pest Halyomorpha halys that causes severe economic losses in the United States is currently expanding both within United States and across Europe. We examined the drivers of H. halys invasion by characterizing the distribution and abundance patterns of H. halys and native stink bugs (Chinavia hilaris and Euschistus servus) across eight different spatial scales. We then quantified the interactive and individual influences of temperature, and measures of resource availability and distance from source populations, and their relevant spatial scales. We used Moran’s Eigenvector Maps based on Gabriel graph framework to quantify spatial relationships among the soybean fields in mid-Atlantic Unites States surveyed for stink bugs.

Findings

Results from the multi-spatial scale, multivariate analyses showed that temperature and its interaction with resource availability and distance from source populations structures the patterns in H. halys at very broad spatial scale. H. halys abundance decreased with increasing average June temperature and distance from source population. H. halys were not recorded at fields with average June temperature higher than 23.5°C. In parts with suitable climate, high H. halys abundance was positively associated with percentage developed open area and percentage deciduous forests at 250m scale. Broad scale patterns in native stink bugs were positively associated with increasing forest cover and, in contrast to the invasive H. halys, increasing mean July temperature. Our results identify the contrasting role of temperature in structuring regional patterns in H. halys and native stink bugs, while demonstrating its interaction with resource availability and distance from source populations for structuring H. halys patterns.

Conclusion

These results help predicting the pest potential of H. halys and vulnerability of agricultural systems at various regions, given the climatic conditions, and its interaction with resource availability and distance from source populations. Monitoring and control efforts within parts of the United States and Europe with more suitable climate could focus in areas of peri-urban developments with deciduous forests and other host plants, along with efforts to reduce propagule pressure.     

Wind turbine noise limits propagation of greater prairie‐chicken boom chorus,but does it matter?

Acoustic signals are often critical elements of mating displays, and lekking male greater prairie‐chickens (Tympanuchus cupido pinnatus) use their boom vocalization for this purpose. We quantified the acoustic characteristics of the boom chorus created by multiple male greater prairie‐chickens vocalizing simultaneously at leks in Brown County, NE, USA, in 2013 and 2014. We used these data to evaluate (a) the role of the boom chorus in prairie‐chicken breeding dynamics and (b) the impact of a wind energy facility on the acoustic signal of the boom chorus. We sampled the chorus using audio recorders placed in transects extending from leks; the chorus exhibited an average peak frequency of 297 ± 13 Hz. The mean chorus signal‐to‐noise ratio declined from 15.7 dB (50 m) to 2.6 dB (800 m), and wind speed and direction, topography, and relative humidity caused variation in signal‐to‐noise ratio at a given distance and location. Chorus recordings from leks within 1,000 m of a wind turbine had lower signal‐to‐noise ratio (β_turbine = ?5.659, SE = 1.289) than leks farther from turbines. The chorus signal‐to‐noise ratio increased slightly with more males present on the lek (~0.1 dB for each additional male; β_males = 0.177; SE = 0.037) and considerably more as more females visited the lek (~1.4 dB for each additional female; β_females = 2.498, SE = 0.235; β_females² = ?0.309, SE = 0.039). Our results provide support for the signal enhancement hypothesis that proposes the boom chorus is influenced notably by male–male competition for females on the lek, rather than functioning solely to advertise the presence of the lek to recruit females. Our results also suggest the choruses emanating from small leks have the greatest potential to be masked by anthropogenic (wind turbine) noise, which may affect the breeding success of male and female prairie‐chickens.     

Tree identity and diversity directly affect soil moisture and temperature but not soil carbon ten years after planting

1. Soil C is the largest C pool in forest ecosystems that contributes to C sequestration and mitigates climate change. Tree diversity enhances forest productivity, so diversifying the tree species composition, notably in managed forests, could increase the quantity of organic matter being transferred to soils and alter other soil properties relevant to the C cycle.
2. A ten‐year‐old tree diversity experiment was used to study the effects of tree identity and diversity (functional and taxonomic) on soils. Surface (0–10 cm) mineral soil was repeatedly measured for soil C concentration, C:N ratio, pH, moisture, and temperature in twenty‐four tree species mixtures and twelve corresponding monocultures (replicated in four blocks).
3. Soil pH, moisture, and temperature responded to tree diversity and identity. Greater productivity in above‐ and below‐ground tree components did not increase soil C concentration. Soil pH increased and soil moisture decreased with functional diversity, more specifically, when species had different growth strategies and shade tolerances. Functional identity affected soil moisture and temperature, such that tree communities with more slow‐growing and shade‐tolerant species had greater soil moisture and temperature. Higher temperature was measured in communities with broadleaf‐deciduous species compared to communities with coniferous‐evergreen species.
4. We conclude that long‐term soil C cycling in forest plantations will likely respond to changes in soil pH, moisture, and temperature that is mediated by tree species composition, since tree species affect these soil properties through their litter quality, water uptake, and physical control of soil microclimates.

     

PKA-mediated phosphorylation of the beta1-adrenergic receptor promotes Gs/Gi switching

Recently, it has been shown that PKA-mediated phosphorylation of the β₂-adrenergic receptor (β₂-AR) by the cyclic AMP-dependent protein kinase (PKA) reduces its affinity for G_s and increases its affinity for G_i. Here we demonstrate that, like the β₂-AR, the β₁-AR is also capable of “switching” its coupling from G_s to G_i in a PKA-dependent manner. The β₁-AR is capable of activating adenylate cyclase via G_s, and can also activate the extracellular-regulated kinases, p44 and p42 (ERK1/2). In transfected CHO cells, the observed β₁-AR-mediated activation of ERK is both sensitive to pertussis toxin (PTX), indicating involvement of G_i/G_o, and to the PKA inhibitor, H-89. β₁-ARs with PKA phosphorylation sites mutated to alanines are unable to activate ERK. Mutating these same residues to aspartic acid, mimicking PKA phosphorylation, leads to a decrease in G_s-stimulated cAMP accumulation and an increase in PTX-sensitive ERK activation. These results strongly support the hypothesis that the β₁-AR, like the β₂-AR, can undergo PKA-dependent “G_s/G_i switching”.