In Vitro Stability of Phytase from Recombinant Bacteria E. Coli BL21 (DE3) EAS1-AMP

The objective of the research was to inquire the Km, Vm, activity, intracellular phytase stability exposed to pH variation, temperature variation and protease (pepsin and pancreas) in vitro. The phytase was produced from recombinant bacteria E. coli BL21(DE3) EAS1-AMP using 1.5 mM IPTG as inducer. Intracellular enzyme was extracted via freeze shock and centrifugation. Pure enzyme was acquired through NI-NTA agarose column. The enzyme was then tested for Km, Vm, phytase activity and stability against pH, temperature and protease. Treatment levels for stability against protease were P0: without protease, P1: addition of pepsin, P2: addition of pepsin and pancreas, and the data were statistically analyzed using analysis of variance of one-way Completely Randomized Design. Crude intracellular phytase had Vm 6.39 υM/sec, Km 34.82 υM, and 277 units activity. Intracellular phytas was stable at pH 4–6 and 0–550 C. Protease level influenced the activity of intracellular phytase (P<0.05). Intracellular phytase was stable against pepsin but not pancreas. Keywords: Km, Vm, activity, intracellular phytase, pH, temperature, protease

PRODUCTION AND CHARACTERIZATION OF CRUDE INTRACELLULER PHYTASE FROM RECOMBINANT BACTERIA pEAS1AMP

This research was aimed at producing a crude intracellular phytase characterized from recombinant bacteria. The recombinant bacteria (pEAS1AMP) was produced by way of transforming pET-22b(+) +pEAS1 into competent E. coli BL21 and E. coli BL21(DE3) cells. Crude intracellular phytase production was induced using 1,5 mM Isopropyl-β-D-thiogalactopyranosid (IPTG). Recombinant bacteria product and enzyme activity test followed the Sajidan method. E. coli BL21(+)pEAS1 and E. coli BL21 (DE3)(+)pEAS1 recombinant bacteria showed growth after 20 hours and 10 hours of transformation. Phytase activity of E. coli BL21 (DE3)(+)+pEAS1 showed higher than those of E. coli BL21(+)+pEAS1. Crude intracellular phytase of pEAS1AMP recombinant bacteria has an optimum activity at pH 5, 40o C, incubation period of 60 minutes, substrate concentration of 2%, molecular weight (MW) of 47.3 kDa, Km = 15.91 υM and Vm = 2.41 υM/second. Mg2+ acts as a cofactor but Fe3+ (10-4 M) acts as an inhibitor. Keywords: bacteria recombinant pEAS1AMP, competent cells, crude intracellular phytas

Photoluminescent diamond nanoparticles for cell labeling: study of the uptake mechanism in mammalian cells

Diamond nanoparticles (nanodiamonds) have been recently proposed as new labels for cellular imaging. For small nanodiamonds (size <40 nm) resonant laser scattering and Raman scattering cross-sections are too small to allow single nanoparticle observation. Nanodiamonds can however be rendered photoluminescent with a perfect photostability at room temperature. Such a remarkable property allows easier single-particle tracking over long time-scales. In this work we use photoluminescent nanodiamonds of size <50 nm for intracellular labeling and investigate the mechanism of their uptake by living cells . By blocking selectively different uptake processes we show that nanodiamonds enter cells mainly by endocytosis and converging data indicate that it is clathrin mediated. We also examine nanodiamonds intracellular localization in endocytic vesicles using immunofluorescence and transmission electron microscopy. We find a high degree of colocalization between vesicles and the biggest nanoparticles or aggregates, while the smallest particles appear free in the cytosol. Our results pave the way for the use of photoluminescent nanodiamonds in targeted intracellular labeling or biomolecule deliver

Transciptome Analysis Illuminates the Nature of the Intracellular Interaction in a Vertebrate-Algal Symbiosis

During embryonic development, cells of the green alga Oophila amblystomatis enter cells of the salamander Ambystoma maculatum forming an endosymbiosis. Here, using de novo dual-RNA seq, we compared the host salamander cells that harbored intracellular algae to those without algae and the algae inside the animal cells to those in the egg capsule. This two-by-two-way analysis revealed that intracellular algae exhibit hallmarks of cellular stress and undergo a striking metabolic shift from oxidative metabolism to fermentation. Culturing experiments with the alga showed that host glutamine may be utilized by the algal endosymbiont as a primary nitrogen source. Transcriptional changes in salamander cells suggest an innate immune response to the alga, with potential attenuation of NF-κB, and metabolic alterations indicative of modulation of insulin sensitivity. In stark contrast to its algal endosymbiont, the salamander cells did not exhibit major stress responses, suggesting that the host cell experience is neutral or beneficial

Origins of choice-related activity in mouse somatosensory cortex.

During perceptual decisions about faint or ambiguous sensory stimuli, even identical stimuli can produce different choices. Spike trains from sensory cortex neurons can predict trial-to-trial variability in choice. Choice-related spiking is widely studied as a way to link cortical activity to perception, but its origins remain unclear. Using imaging and electrophysiology, we found that mouse primary somatosensory cortex neurons showed robust choice-related activity during a tactile detection task. Spike trains from primary mechanoreceptive neurons did not predict choices about identical stimuli. Spike trains from thalamic relay neurons showed highly transient, weak choice-related activity. Intracellular recordings in cortex revealed a prolonged choice-related depolarization in most neurons that was not accounted for by feed-forward thalamic input. Top-down axons projecting from secondary to primary somatosensory cortex signaled choice. An intracellular measure of stimulus sensitivity determined which neurons converted choice-related depolarization into spiking. Our results reveal how choice-related spiking emerges across neural circuits and within single neurons

Characterization of a Second Bovine Rotavirus Serotype

Bovine rotavirus (BRV) V 1005 was characterized by two-way cross-neutralization tests as a second serotype of BRV. Virions and inner shell particles of 65 nm and 55 nm diameter respectively, and empty capsids of 65 nm and 55 nm diameter were separated by density gradient centrifugation. Three polypeptides of molecular weight 60,000, 36,000 and 28,000 (minor protein) could be identified in the outer shell of virions and in the larger empty capsids. Inner shell particles contained three polypeptides of molecular weight 105,000, 83,000 and 43,000. Both sizes of empty capsids showed two polypeptides of molecular weight 75,000 and 55,000 not found in virions. Pulse-labelling of infected cells revealed eight major and three minor intracellular viral polypeptides. Viral polypeptide synthesis started at about 6 hours p.i. and correlated in time with double-stranded RNA synthesis. As soon as viral polypeptide synthesis was detectable, newly synthesized viral polypeptides were incorporated into intracellular viral particles. Radioactive viral polypeptides appeared without a longer lag period in extracellular viruses from 6 hours p.i. onward

Bioengineering bacterial outer membrane vesicles as delivery system for RNA therapeutics targeted to lung epithelial cytosols

Intact epithelia lining the airways and alveoli in the lung are essential to maintain lung function. Structural or functional damage of epithelial cells leads in severe diseases, including COPD/emphysema, ibrosis or ALI/ARDS. This central role of epithelia in pulmonary diseases identifies these cells as primary candidates for targeted therapy. With the exception of surface-expressed molecules, however, targeting intracellular components is severely restricted due to poor delivery. We aim to overcome this obstacle using topically administered, bioengineered, biocompatible bacterial outer membrane vesicles (OMVs) as recombinant drug delivery systems for novel biopharmaceuticals. Engineering recombinant surface expression of eukaryotic receptor ligands in ClearColi®, a commercial E.coli BL21 (DE3) strain deficient in lipopolysaccharide production, we have used red fluorescent protein reporters to track OMV loading, transgene expression, and eukaryotic cell trafficking. We demonstrate statistically significant differences in the levels of over 700 proteins between differentially engineered and purified OMV preps with additional differences in transcriptome and lipidome consistency. We also characterised visual and particle size differences observed by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). Here we report early bioadhesion and culture of re-differentiated lung epithelia. This project aims to bridge the biotechnological gap in the intracellular biopharmaceutics drug delivery challenge for respiratory epithelia through highly controlled, and scalable bio-nanotechnology process. If successful, our work will unlock intracellular imaging and therapeutics research for respiratory diseases with a significant epithelial component, paving the way for other targeting ligands and potentially non-respiratory indications. cellular uptake results in A549 culture as well as air-liquid interface

Wave nucleation rate in excitable systems in the low noise limit

Motivated by recent experiments on intracellular calcium dynamics, we study the general issue of fluctuation-induced nucleation of waves in excitable media. We utilize a stochastic Fitzhugh-Nagumo model for this study, a spatially-extended non-potential pair of equations driven by thermal (i.e. white) noise. The nucleation rate is determined by finding the most probable escape path via minimization of an action related to the deviation of the fields from their deterministic trajectories. Our results pave the way both for studies of more realistic models of calcium dynamics as well as of nucleation phenomena in other non-equilibrium pattern-forming processes