Shear thickening of F-actin networks crosslinked with non-muscle myosin IIB

The material properties of cytoskeletal F-actin networks facilitate a broad range of cellular behaviors, whereby in some situations cell shape is preserved in the presence of force and, at other times, force results in irreversible shape change. These behaviors strongly suggest that F-actin networks can variably deform elastically or viscously. While a significant amount is known about the regulation of the elastic stiffness of F-actin networks, our understanding of the regulation of viscous behaviors of F-actin networks is largely lacking. Here, we study the rheological behavior of F-actin networks formed with heavy meromyosin non-muscle IIB (NMMIIB). We show that NMMIIB quenched with ADP crosslinks F-actin into networks that, for sufficient densities, display stress stiffening behavior. By performing a series of creep tests, we show that densely crosslinked actin/NMMIIB-ADP networks undergo viscous deformation over a wide range of stresses, ranging from 0.001 to 10 Pa. At high stresses, networks that stress stiffen are also observed to shear thicken, whereby the effective viscosity increases as a function of stress. Shear thickening results in a reduction in the extent of irreversible, viscous deformation in actin/NMMIIB-ADP networks at high stresses compared to that expected for a linear viscoelastic material. Thus, viscous deformation contributes less to the overall mechanical response at high levels of applied force. Our results indicate mechanisms by which the fluid-like nature of the actomyosin cytoskeleton can be reduced under high load.     

Biosynthesis of the Peptide Antibiotic Feglymycin by a Linear Nonribosomal Peptide Synthetase Mechanism

Feglymycin, a peptide antibiotic produced by Streptomyces sp. DSM 11171, consists mostly of nonproteinogenic phenylglycine‐type amino acids. It possesses antibacterial activity against methicillin‐resistant Staphylococcus aureus strains and antiviral activity against HIV. Inhibition of the early steps of bacterial peptidoglycan synthesis indicated a mode of action different from those of other peptide antibiotics. Here we describe the identification and assignment of the feglymycin (feg) biosynthesis gene cluster, which codes for a 13‐module nonribosomal peptide synthetase (NRPS) system. Inactivation of an NRPS gene and supplementation of a hydroxymandelate oxidase mutant with the amino acid l ‐Hpg proved the identity of the feg cluster. Feeding of Hpg‐related unnatural amino acids was not successful. This characterization of the feg cluster is an important step to understanding the biosynthesis of this potent antibacterial peptide.     

CD74 and CD44 Expression on CTCs in Cancer Patients with Brain Metastasis

Up to 40% of advance lung, melanoma and breast cancer patients suffer from brain metastases (BM) with increasing incidence. Here, we assessed whether circulating tumor cells (CTCs) in peripheral blood can serve as a disease surrogate, focusing on CD44 and CD74 expression as prognostic markers for BM. We show that a size-based microfluidic approach in combination with a semi-automated cell recognition system are well suited for CTC detection in BM patients and allow further characterization of tumor cells potentially derived from BM. CTCs were found in 50% (7/14) of breast cancer, 50% (9/18) of non-small cell lung cancer (NSCLC) and 36% (4/11) of melanoma patients. The next-generation sequencing (NGS) analysis of nine single CTCs from one breast cancer patient revealed three different CNV profile groups as well as a resistance causing ERS1 mutation. CD44 and CD74 were expressed on most CTCs and their expression was strongly correlated, whereas matched breast cancer BM tissues were much less frequently expressing CD44 and CD74 (negative in 46% and 54%, respectively). Thus, plasticity of CD44 and CD74 expression during trafficking of CTCs in the circulation might be the result of adaptation strategies.     

Growth and yields of dechlorinators, acetogens, and methanogens during reductive dechlorination of chlorinated ethenes and dihaloelimination of 1 ,2-dichloroethane

The population dynamics of a mixed microbial culture dechlorinating trichloroethene (TCE), cis-1,2-dichloroethene (cDCE), 1,2-dichloroethane (1,2-DCA), and vinyl chloride (VC) to ethene were studied. Quantitative PCR revealed that Dehalococcoides, Geobacter, Sporomusa, Spirochaetes, and Methanomicrobiales phylotypes grew in short-term experiments. Both Geobacter and Dehalococcoides populations grew during TCE dechlorination to cDCE, but only Dehalococcoides populations grew during further dechlorination to ethene. The cell yields for Dehalococcoides determined in this study were similar on an electron equivalent basis regardless of the chlorinated compound transformed: (0.9+/-0.3) x 10(8)16S rRNA gene copies/microelectron equivalent (microeeq) ethene produced during cDCE dechlorination, (1.5 +/-0.3) x 10(8) copies/microeeq ethene produced during VC dechlorination, and (1.6+/-0.8) x 10(8) copies/ u,eeq ethene produced during 1,2-DCA dihaloelimination. The yield for the Geobacter population on TCE was estimated to be (1+/-0.5) x 10(8) copies/microeeq cDCE produced. Calculations showed that the Geobacter population was likely responsible for approximately 80% of the TCE dechlorinated to cDCE in this experiment. Acetogenesis by a Sporomusa population was the main competition to dechlorination for reducing equivalents. Sporomusa did not transform any chlorinated substrates tested, but was capable of converting methanol to acetate and hydrogen for dechlorination. Understanding the functions of various populations in mixed communities may explain why Dehalococcoides spp. are active at some sites and not others, and may also assist in optimizing the growth of bioaugmentation cultures, both in the laboratory and in the field.     

Novel LOX Variants in Five Families with Aortic/Arterial Aneurysm and Dissection with Variable Connective Tissue Findings

Thoracic aortic aneurysm and dissection (TAAD) is a major cause of cardiovascular morbidity and mortality. Loss-of-function variants in LOX, encoding the extracellular matrix crosslinking enzyme lysyl oxidase, have been reported to cause familial TAAD. Using a next-generation TAAD gene panel, we identified five additional probands carrying LOX variants, including two missense variants affecting highly conserved amino acids in the LOX catalytic domain and three truncating variants. Connective tissue manifestations are apparent in a substantial fraction of the variant carriers. Some LOX variant carriers presented with TAAD early in life, while others had normal aortic diameters at an advanced age. Finally, we identified the first patient with spontaneous coronary artery dissection carrying a LOX variant. In conclusion, our data demonstrate that loss-of-function LOX variants cause a spectrum of aortic and arterial aneurysmal disease, often combined with connective tissue findings.     

Characterization of nitrogen,phosphorus, and potassium mass balances of dairy farms in New York State

A whole-farm nutrient mass balance (NMB) is a useful measure of the nutrient status of a dairy farm. Research is needed to define and determine a feasible NMB range for dairy farm systems in New York State (NY). The objectives of this study were to (1) document the distribution of N, P, and K mass balances of 102 NY dairy farms (including 75 small, 15 medium, and 12 large farms); (2) establish initial NMB benchmarks based on what 75% of the farms achieved; (3) determine the maximum animal density that allows an example NY dairy farm to balance cow P excretions and crop P removal without exporting crops or manure; and (4) identify opportunities to improve NMB over time. Nutrient mass balances of the 102 farms ranged from −39 to 237 kg of N/ha for N without including N₂ fixation (N1), from −14 to 259 kg of N/ha when N₂ fixation was included (N2), from −7 to 51 kg of P/ha, and from −46 to 148 kg of K/ha. Seventy-five percent of the farms were operating at NMB less than 118 kg of N/ha for N1, 146 kg of N/ha for N2, 13 kg of P/ha, and 41 kg of K/ha (75% benchmarks). Farms with the highest nutrient use efficiencies (lowest NMB per unit of milk produced) operated with less than 8.8 kg of N/Mg of milk for N1, 11.8 kg of N/Mg of milk for N2, 1.1 kg of P/Mg of milk, and 3.0 kg of K/Mg of milk. The biggest contributor to the NMB was the amount of imported nutrients, primarily feed purchases. The example farm assessment (assuming no export of crops or manure) suggested that, when 70% of the feed is produced on the farm and P in feed rations does not exceed 4 g of P/kg of DM, cow P excretion and crop P removal were balanced at a maximum animal density of 2.4 animal units (AU)/ha (~0.97 AU/acre). Dairy farms operating with animal densities <2.4 AU/ha typically had NMB below the 75% benchmark, whereas most dairies with more than 2.4 AU/ha needed to export manure or crops to meet the 75% benchmark. Opportunities to reduce NMB on many farms, independent of size and without changes in animal density, are possible by more tightly managing fertilizer and feed imports, increasing the percentage of farm-produced nutrients, implementing precision feeding, and exporting crops or manure.     

Phenolic compounds in some apple (Malus domestica Borkh) cultivars of organic and integrated production

Eleven organically grown apple cultivars and 11 apple cultivars of integrated production from Austria and Slovenia were analyzed by HPLC for the content of phenolic compounds in peel and pulp. We identified chlorogenic acid, p‐coumaric acid, procyanidin B3, protocatechuic acid, (?)‐epicatechin, phloridzin, rutin and quercetin‐3‐rhamnoside in apple peel. In apple pulp, (+)‐catechin was also identified in all the cultivars. Some other phenols (procyanidin B3, rutin and quercetin‐3‐rhamnoside) could not be identified or were not properly separated. With regard to the phenolic content in the apple peel, there were no differences between organically grown apple cultivars and apple cultivars of integrated production. Organically grown apples, however, exhibited a higher content of phenolic substances in the apple pulp compared with the apple cultivars of integrated production. This may be due either to the different genotype source or to the growing technology. Higher concentrations of phenolic compounds in organically grown cultivars could be a result of plant response to stress. The apple peel contained higher concentrations of identified phenols than the pulp. The apple peel represents up to 10% of the whole fruit; therefore the phenolsic compounds in the pulp are of greater importance to the consumer than the phenolic compounds in the peel. Copyright © 2005 Society of Chemical Industry     

The effect of carbon nanotube properties on the degree of dispersion and reinforcement of high density polyethylene

The efficacy with which a range of nanotubes could reinforce a high density polyethylene (HDPE) matrix was investigated, in relation to nanotube diameter, purity, functionalization, alignment and nanotube bulk density. Composites were prepared by melt blending multiwall carbon nanotubes (MWNTs) with high density polyethylene (HDPE), followed by the injection molding of tensile specimens. At a 5 wt% loading, the most effective nanotubes were those of large diameter, received in an aligned form with low bulk density, producing a 66% increase in elastic modulus and a 69% improvement in yield stress. This was contradictory to theoretical mechanics calculations that predicted an increasing degree of reinforcement for nanotubes of reduced diameter. This difference was explained by the higher degree of dispersion observed in the composites with MWNTs of greater diameter.     

Disinfection of swine wastewater using chlorine, ultraviolet light and ozone

Veterinary antibiotics are widely used at concentrated animal feeding operations (CAFOs) to prevent disease and promote growth of livestock. However, the majority of antibiotics are excreted from animals in urine, feces, and manure. Consequently, the lagoons used to store these wastes can act as reservoirs of antibiotics and antibiotic-resistant bacteria. There is currently no regulation or control of these systems to prevent the spread of these bacteria and their genes for antibiotic resistance into other environments. This study was conducted to determine the disinfection potential of chlorine, ultraviolet light and ozone against swine lagoon bacteria. Results indicate that a chlorine dose of 30 mg/L could achieve a 2.2-3.4 log bacteria reduction in lagoon samples. However, increasing the dose of chlorine did not significantly enhance the disinfection activity due to the presence of chlorine-resistant bacteria. The chlorine resistant bacteria were identified to be closely related to Bacillus subtilis and Bacillus licheniformis. A significant percentage of lagoon bacteria were not susceptible to the four selected antibiotics: chlortetracycline, lincomycin, sulfamethazine and tetracycline (TET). However, the presence of both chlorine and TET could inactivate all bacteria in one lagoon sample. The disinfection potential of UV irradiation and ozone was also examined. Ultraviolet light was an effective bacterial disinfectant, but was unlikely to be economically viable due to its high energy requirements. At an ozone dose of 100 mg/L, the bacteria inactivation efficiency could reach 3.3-3.9 log.