Dasatinib Nanoemulsion and Nanocrystal for Enhanced Oral Drug Delivery

In this work, dasatinib (DAS) nanoemulsion and nanocrystal are produced by high-gravity technology that approaches to practical mass production. The drug nanoformulations were systematically characterized and evaluated. At a low high-gravity level (β) = 47, nanoemulsion droplets were 16.15 ± 0.42 nm with a PDI of 0.122 ± 0.021. The nanoemulsion’s size and active pharmaceutical ingredient (API) content remained stable at long-term (4 months) freeze–thaw and dilution experiments. At a high β = 188, the as-prepared nanocrystal was lamellar with a short diameter of about 200 nm and a long diameter of about 750 nm. In vitro performances demonstrated the nanoemulsion displayed higher cytotoxicity on MDA-MB-231 tumor cells, Caco-2 cell permeability and drug release than that of the nanocrystal, indicating that nanoemulsion should be an ideal alternative for dasatinib oral administration.

Homeopathy and the science of high dilutions: when to believe the unbelievable

In 1988, a Nature Editorial titled “When to believe the unbelievable” noted that the famous high-dilution experiments of the Benveniste group had no physical basis and suggested that “prudent people should, for the time being, suspend judgment.” In point of fact, judgment was not suspended and in the ensuing weeks the authors were resoundingly condemned and ridiculed for the purported lack of replication of their findings. Twenty-four years later, the concept that a solution diluted beyond the Avogadro-Loschmidt constant may show some biological and pharmacological activity is still “unbelievable” from an ordinary common sense perspective, but things are dramatically changing. Several groups of researchers from countries all over the world have been investigating this difficult question, which has weighty implications not just for pharmacology (homeopathy) but also for biology, physics and the environmental sciences. The XXVI meeting of GIRI (International research group on ultra-low dose and high-dilution effects), scheduled to take place in Florence on 20-22 September 2012, will present a growing body of evidence in favor of the “existence” of high-dilution/dynamization effects. Continuing the excellent work of the preceding editions, the meeting features a rich and outstanding program organized into four main tracks: physico-chemical features of high dilutions; studies done in planta and in the field; clinical and veterinary evidence; and laboratory models. ... For two centuries, homeopathy and science have been regarded as two opposing and conflicting fields. Now things are changing, as scientific evidence begins to support many homeopathic tenets, and the homeopathic world increasingly stimulates science to investigate previously under-evaluated and little understood subtle phenomena. For over 26 years from the foundation, the international GIRI group has been stimulating fruitful dialogue in the interest of furthering true science—i.e., that which is free from ideological barriers and pre-judgments. Quite often, scientific “dogmas” have been disrupted by new evidence, or previously dismissed phenomena have gained importance in the light of a new conceptual framework. The unusual properties of high dilutions/dynamizations, which merit further investigation, are potentially relevant not just to homeopathic pharmaceutical science, but also to agriculture (“agrohomeopathy”), environmental sciences and, in general, to the future of mankind.

Evidence for widespread cytoplasmic structuring into mesoscopic condensates

Eukaryotic cytoplasm organizes itself via both membrane-bound organelles and membrane-less biomolecular condensates (BMCs). Known BMCs exhibit liquid-like properties and are typically visualized on the scale of ~1 um. They have been studied mostly by microscopy, examining select individual proteins. Here, we investigate the global organization of native cytoplasm with quantitative proteomics, using differential pressure filtration, size exclusion, and dilution experiments. These assays reveal that BMCs form throughout the cytosplasm, predominantly at the mesoscale of ~100 nm. Our data indicate that at least 18% of the proteome is organized via such mesoscale BMCs, suggesting that cells widely employ dynamic liquid-like clustering to organize their cytoplasm, at surprisingly small length scales.

Mixoplankton interferences in dilution grazing experiments

It remains unclear as to how mixoplankton (coupled phototrophy and phagotrophy in one cell) affects the estimation of grazing rates obtained from the widely used dilution grazing technique. To address this issue, we prepared laboratory-controlled dilution experiments with known mixtures of phyto-, protozoo-, and mixoplankton, operated under different light regimes and species combinations. Our results evidenced that chlorophyll is an inadequate proxy for phytoplankton when mixoplankton are present. Conversely, species-specific cellular counts could assist (although not fully solve) in the integration of mixoplanktonic activity in a dilution experiment. Moreover, cell counts can expose prey selectivity patterns and intraguild interactions among grazers. Our results also demonstrated that whole community approaches mimic reality better than single-species laboratory experiments. We also confirmed that light is required for protozoo- and mixoplankton to correctly express their feeding activity, and that overall diurnal grazing is higher than nocturnal. Thus, we recommend that a detailed examination of initial and final plankton communities should become routine in dilution experiments, and that incubations should preferably be started at the beginning of both day and night periods. Finally, we hypothesize that in silico approaches may help disentangle the contribution of mixoplankton to the community grazing of a given system.

Trade-off between competition ability and invulnerability to predation in marine microbes; protist grazing versus viral lysis effects

Trade-offs between competition ability and invulnerability to predation are important mechanisms explaining how predation promotes bacterial diversity. However, existence of these trade-offs has apparently not been investigated in natural marine bacterial communities. Here, we address this question with growth-based measurements for each marine bacterial taxon by conducting on-board dilution experiments to manipulate predation pressure and using high-throughput sequencing to assess the response of bacterial communities. We determined that bacterial taxa with a higher predation-free growth rate were accompanied with higher predation-caused mortality, supporting existence of competitiveness-invulnerability trade-off. This trade-off was stronger and more consistent under viral lysis than protist grazing. In addition, predation generally flattened out the rank-abundance distribution and increased the evenness and richness of the bacterial community. These findings supported the 'Kill-the-Winner' hypothesis. All experiments supported a significant competitiveness-invulnerability trade-off, but there was substantial variation among bacterial communities in response to predation across experiments conducted in various sites and seasons. Therefore, we inferred that the Kill-the-Winner hypothesis is important but likely not the only deterministic mechanism explaining how predation shapes bacterial assemblages in natural marine systems.

Nitrogen Fixation by Paenibacillus Polymyxa WLY78 is Responsible for Cucumber Growth Promotion

Aims To study nitrogen contribution to cucumber derived from nitrogen fixation of Paenibacillus polymyxa WLY78.Methods The nif gene cluster deletion mutant (ΔnifB-V) of P. polymyxa WLY78 is constructed by a homologous recombination method. The GFP-labeled ΔnifB-V mutant was used to inoculate cucumber and to study colonization by confocal laser scanning microscope. The effects of plant-growth promotion were investigated by greenhouse experiments. The nitrogen fixation contribution was estimated by 15N isotope dilution experiments. Results Deletion of nif gene cluster of P. polymyxa WLY78 resulted in complete loss of nitrogenase activity. Observation by laser confocal microscopy revealed ΔnifB-V mutant can effectively colonize cucumber root, stem and leaf tissues, like wild-type P. polymyxa WLY78. Greenhouse experiments showed that inoculation with P. polymyxa WLY78 can significantly enhance the lengths and dry weights of cucumber roots and shoots, but inoculation with ΔnifB-V mutant can not. 15N isotope dilution experiments showed that cucumber plants derive 25.93% nitrogen from nitrogen fixation performed by P. polymyxa WLY78, but the ΔnifB-V mutant nearly can not provide nitrogen for plant growth. Conclusions This present study demonstrates that nitrogen fixation performed by P. polymyxa WLY78 is responsible for cucumber growth promotion.

Comparison of Paenibacillus polymyxa wild-type and Nif− mutant in colonization, plant-growth promotion and nitrogen fixation contribution

Aims This study aimed to compare the effect on colonization, plant-growth promotion and nitrogen fixation contribution by inoculation with Paenibacillus polymyxa wild-type and Nif−mutant. Methods Paenibacillus polymyxa wild-type and Nif− mutant was labeled with GFP and then the GFP-labeled bacteria were used to inoculate cucumber. The colonization patterns of P. polymyxa WLY78 in these plants were observed under the confocal laser scanning microscope. The effects of plant-growth promotion were investigated by greenhouse experiments. The nitrogen fixation contribution was estimated by 15N isotope dilution experiments. Results Observation by laser confocal microscopy revealed that both P. polymyxa WLY78 and ΔnifB-V mutant can effectively colonize cucumber root, stem and leaf tissues. Greenhouse experiments showed that inoculation with P. polymyxa WLY78 can significantly enhance the lengths and fresh wights of cucumber roots and shoots, but inoculation with ΔnifB-V mutant can not. 15N isotope dilution experiments showed that cucumber plants derive 25.93% nitrogen from nitrogen fixation performed by P. polymyxa WLY78, but the ΔnifB-V mutant nearly can not provide nitrogen for plant. Conclusions This present study demonstrates that nitrogen fixation plays an import role in promoting plant growth.

Coastal Bacterial Community Response to Glacier Melting in the Western Antarctic Peninsula

Current warming in the Western Antarctic Peninsula (WAP) has multiple effects on the marine ecosystem, modifying the trophic web and the nutrient regime. In this study, the effect of decreased surface salinity on the marine microbial community as a consequence of freshening from nearby glaciers was investigated in Chile Bay, Greenwich Island, WAP. In the summer of 2016, samples were collected from glacier ice and transects along the bay for 16S rRNA gene sequencing, while in situ dilution experiments were conducted and analyzed using 16S rRNA gene sequencing and metatranscriptomic analysis. The results reveal that certain common seawater genera, such as Polaribacter, Pseudoalteromonas and HTCC2207, responded positively to decreased salinity in both the bay transect and experiments. The relative abundance of these bacteria slightly decreased, but their functional activity was maintained and increased the over time in the dilution experiments. However, while ice bacteria, such as Flavobacterium and Polaromonas, tolerated the increased salinity after mixing with seawater, their gene expression decreased considerably. We suggest that these bacterial taxa could be defined as sentinels of freshening events in the Antarctic coastal system. Furthermore, these results suggest that a significant portion of the microbial community is resilient and can adapt to disturbances, such as freshening due to the warming effect of climate change in Antarctica.

Phytoplankton growth and consumption by microzooplankton stimulated by turbulent nitrate flux suggest rapid trophic transfer in the oligotrophic Kuroshio

The Kuroshio Current has been thought to be biologically unproductive because of its oligotrophic conditions and low plankton standing stocks. Even though vulnerable life stages of major foraging fishes risk being entrapped by frontal eddies and meanders and encountering low food availability, they have life cycle strategies that include growing and recruiting around the Kuroshio Current. Here we report that phytoplankton growth and consumption by microzooplankton are stimulated by turbulent nitrate flux amplified by the Kuroshio Current. Oceanographic observations demonstrate that the Kuroshio Current topographically enhances significant turbulent mixing and nitrate influx to the euphotic zone. Graduated nutrient enrichment experiments show that growth rates of phytoplankton and microheterotroph communities were stimulated within the range of the turbulent nitrate flux. Results of dilution experiments imply significant microzooplankton grazing on phytoplankton. We propose that these rapid and systematic trophodynamics enhance biological productivity in the Kuroshio.