Production of Zika Virus Virus-Like Particles

Zika virus (ZIKV) is a mosquito-transmitted virus that has caused major outbreaks of disease around the world over the last few years. The infectious ZIKV consists of a structural protein outer shell surrounding a nucleocapsid. Virus-like particles (VLP) consist of the outer structural protein shell, but without the nucleocapsid, and are hence noninfectious. VLP, however, are structurally equivalent to the native virus and thus present a similar antigenic profile. These properties make them good candidates for vaccine development. ZIKV VLP can be generated on a laboratory scale by cloning the relevant structural proteins into a eukaryotic expression vector and transfecting the construct into mammalian cells. The secreted VLP can be harvested from the culture medium and purified by sucrose cushion ultracentrifugation. Validation of the VLP is achieved through western blotting and electron microscopy.

Recent Progress in Harvest and Recovery Techniques of Mammalian and Algae Cells for Industries

In our modern world, biotechnology products play important roles not only in our health and culture, but also various industries such as food, agriculture, sewage treatment, biofuels, nutraceuticals, and pharmaceuticals. Rapid technological advances in biotechnology over the last few decades have allowed industrial integration of mammalian cells (like the Chinese hamster ovary cells) and algae cells in pharmaceutical and biofuel industries to produce commercial products and valuable biomolecules. However, the cost of cell harvest and recovery can become expensive depending on the harvesting technique, degree of purification, and intended use of the end-products. This has led to numerous research in exploring and developing efficient harvesting techniques. Therefore, in this review, the popular harvesting techniques and their recent applications will be discussed.

A novel method for extraction of polypropylene microplastics in swine manure

With the development of modern industry and agriculture, plentiful microplastics (MPs) were produced as a result of the abuse of plastic. The widespread presence of MPs in soils has caused coastal ecological environment pollution. Previous research has shown that fertilizer is one pathway for the entry of MPs into agricultural soils. Meanwhile, livestock manure is a major fertilizer for crops, and the application of livestock manure compost creates a potential pathway for MPs to enter soils. Thus, MPs may exist in livestock manure from the process of livestock breeding and ultimately contaminate agricultural soils. Based on the increasing attention to MP pollution, manure-born MPs will attract more interest in the future. Thus, the present study compares the extraction effects of centrifugation with fractional distillation, and an improved method is introduced to extract polypropylene (PP) from different types of swine manure. The numbers of particles and fibers were determined using a camera (MS60) connected to a stereomicroscope (Mshot MZ62), and the results showed that the recovery rate of plastic particles in swine manure based on different added numbers ranged from 71.43% ± 8.36 to 96.67% ± 3.33 with the centrifugation method, and only 31.11% ± 10.56 to 43.33% ± 12.56 using fractional distilling. The recovery rate for fibers was generally higher than for particles, especially using centrifugation, and ranged from 95.67% ± 1.58 to 100% ± 0, while the rate of fiber recovery using fractional distillation ranged from 39.44% ± 10.66 to 39.44 ± 10.66. The results of recovery rates using the two methods show that the effect of extraction by centrifugation is superior to the method of fractional distillation, with a recovery rate of approximately 100% for fibers and 90% for particles. The recovery number of microplastics evaluated with a line regression model was acceptable. Graphical abstract.

Switchgrass as oil and water-spill sorbent: Effect of particle size, torrefaction, and regeneration methods

Switchgrass, both raw and torrefied, was tested for its ability to sorb water or oil. The cyclic performance was also examined, utilizing centrifugal extraction as the regeneration method. Both oil and water sorption capacity increase with the decreasing size of raw switchgrass particles. Results indicate that 3 mm raw switchgrass can sorb water at a capacity of about 6 times its mass and can sorb oil at a capacity of about 3 times its mass, which makes it a suitable biodegradable sorbent. Torrefaction at 220 °C for 30 min reduces water sorption capacity by an average of 55% but does not have a statistically significant impact on oil sorption. Sorption of liquid is negatively correlated to particle size. Centrifugation is able to partially desorb either liquid from the sorbent, and subsequent sorption cycles do not display lower sorption capacity than the first cycle when calculated on a dry mass basis.

Near-Physiological Cell Cycle Synchronization with Countercurrent Centrifugal Elutriation

The bioreactor conditions and cell diversity in mammalian cell cultures are often regarded as homogeneous. Recently, the influence of various kinds of heterogeneities on production rates receives increasing attention. Besides spatial gradients within the cultivation system, the variation between cell populations and the progress of the cells through the cell cycle can affect the dynamics of the cultivation process. Strong metabolic up- and down-regulations leading to variable productivities, even in exponentially growing cell cultures, have been identified in CHO cell cultivations. Consequently, scientific studies of cell cycle-related effects and metabolic regulations require experiments utilizing cell cycle-enriched subpopulations. Importantly, the enrichment procedure itself must not strongly interfere with the cell culture under investigation. Such subpopulations can be generated by near-physiological countercurrent centrifugal elutriation, which is described in the following chapter. At first, a brief overview regarding the cell cycle, currently identified effects and commonly used methods, and their applicability is outlined. Then, the experimental setup and the synchronization itself are explained.

Biochemical Methods to Analyze the Subcellular Localization of NF-κB Proteins Using Cell Fractionation

Cell fractionation is a method used to study different cellular events like protein translocation and sequestration by disrupting cells and fractionating their contents, thus allowing an enrichment of the protein of interest. Using different concentrations of sucrose or detergent buffer formulations in combination with centrifugations, the cell fractions are separated based on their density and size.

The impact of Sample Handling Time on metformin serum concentration

This is an informative article which can help research providers to arrange and conduct studies dedicated to the assessment of metformin serum concentrations. If there is a problem with coordination of sample preparation and it is necessary to measure metformin concentration, two hours gap between blood drain and centrifugation has no impact on the results.

Exploration of cell-free DNA (cfDNA) recovery for touch deposits

Although touch deposit DNA is widely used in forensic casework, its cellular and acellular contents and their biological origins are poorly understood. There is evidence that the cell-free component of DNA deposited by handling may contribute substantial genetic information; however, most research into touch DNA recovery does not separate cellular and cell-free fractions or seek to characterize their contents. This work is an important early step in developing methods to isolate the cfDNA from biological material deposited by handling. Size-filtration as a separation technique was determined to be prone to DNA loss, even on optimized control samples of pure ladder DNA. Centrifugal separation was optimized to determine minimum speed and time required to reliably remove all cellular debris from the material collected by rinsing donor hands. To determine if the centrifugal force risked rupturing shed corneocyte cells and releasing cellular DNA into the supernatant, DNA levels were measured, and cells were visualized microscopically before and after centrifugation of hand rinses. Heated buccal cells were used as a positive control to demonstrate cell rupture would be detected with these methods. Following the determination of a suitable separation technique, an investigation into purification methods for cfDNA was conducted. DNA recovery using three kits for plasma cfDNA, one for PCR clean-up and one for genomic DNA were assessed on both ladder DNA to simulate cfDNA fragments and on collected hand deposit supernatants from both unwashed and washed hands. Purification methods designed for recovery of short DNA fragments from plasma yielded the highest recovery percentage across sample types, with BioChain cfPure performing the best. Donors' hands were shown to shed high levels of cfDNA, which were better recovered with a method for short fragments than with a traditional genomic technique often used on touch DNA samples.

Cryptosporidium Oocyst Purification Using Discontinuous Gradient Centrifugation

Many laboratory studies in cryptosporidial research require a source of purified oocysts. Sources can include experimentally infected laboratory animals or from samples collected from naturally infected animals and from clinical cases of human cryptosporidiosis. Purification of oocysts can be accomplished with readily available laboratory equipment including tabletop centrifuges and microcentrifuges. Following purification, oocysts can be stored in antibiotic-supplemented buffers or in 2.5% aqueous potassium dichromate for over 6 months. Ultimately, oocyst viability and infectivity decline to less than 10% after 1 year, so if isolates are expected to be maintained, serial passage in a suitable host at ≤6-month intervals is recommended. Oocysts purified as described in this chapter are suitable for animal infection studies, cell culture studies, and a wide range of molecular biological studies, environmental studies, drug testing, and disinfection studies.

Effect of Times to Blood Processing on the Stability of Blood Proteins Associated with Dementia

BACKGROUND

The stability of proteins in the collecting tubes after blood draw is critical to the measured concentrations of the proteins. Although the guidelines issued by the Clinical and Laboratory Standards Institute (CLSI) suggest centrifugation should take place within 2 h of drawing blood, it is very difficult to follow these guidelines in hospitals or clinics. It is necessary to study the effect of times to blood processing on the stability of the proteins of interest.

METHODS

In this work, the plasma proteins of interest were those relevant to dementia, such as amyloid β 1-40 (Aβ1-40), Aβ1-42, Tau protein (Tau), and α-synuclein. The times to blood processing after blood draw ranged from 0.5 to 8 h. The storage temperatures of blood were room temperature (approx. 25°C) and 30°C. After storage, blood samples were centrifuged at room temperature to obtain plasma samples. Ultrasensitive immunomagnetic reduction was applied to assay these proteins in the plasma.

RESULTS

The levels of plasma Aβ1-40, Tau, and α-synuclein did not significantly change until 8 h after blood draw when stored at room temperature. Plasma Aβ1-42 levels did not change significantly after 8 h of storage at room temperature before blood processing. Higher storage temperatures, such as 30°C, for blood samples accelerated the significant variations in the measured concentrations of Aβ1-40, Tau, and α-synuclein in plasma.

CONCLUSION

According to these results, for clinical practice, it is suggested that blood samples be stored at room temperature for no longer than 4.5 h after blood draw until centrifugation for the assay of dementia biomarkers in plasma.

Lipofectamine enhances Chlamydia infectivity in cell culture

Cultivation of Chlamydia species in cell lines requires centrifugation of the inoculum onto diethylaminoethyl-dextran-pretreated cell monolayers to improve the infection efficiency. Here we report that the addition of DNA transfection reagent Lipofectamine in the inoculum significantly enhances the infectivity of Chlamydia abortus in mouse fibroblast McCoy cells, with an infection efficiency equivalent to that of the centrifugation method. Similar enhancement effects of Lipofectamine on the infectivity of C. psittaci and C. trachomatis were also observed. This study provides an alternative and convenient method for the cultivation of Chlamydia species in vitro in the absence of centrifugation.

Evaluation of floc-harvesting technologies in biofloc technology (BFT) system for aquaculture

This study was conducted to examine floc-harvesting performance by three separation technologies, namely sedimentation, centrifugation, and membrane filtration, for biofloc generated from a BFT system in aquaculture. According to the experimental results, sedimentation demonstrated the poorest harvesting performance with the lowest energy consumption; centrifugation showed the highest harvesting performance with the highest energy burden; membrane filtration achieved better harvesting performance than sedimentation and better energy efficiency than centrifugation. In terms of large-scale floc recovery, a two-step harvesting process utilizing centrifugation with membrane filtration was found to be a reliable way to overcome the limitation of sedimentation and obtain moderate energy-efficiency. Overall, the energy-consuming aspects of the floc-recovery process on an industrial scale should be concerned, even though the use of biofloc as an aquaculture feed would be a positive in terms of an environment-friendly approach to recycling of aquaculture wastewater.

Data on chloroquine/hydroxychloroquine content in compounded oral suspension after filtration and centrifugation

The COVID-19 outbreak is spreading worldwide pushing the national healthcare systems to find effective protocols to prevent contagion and to reduce the patients' mortality and the severity of long-term effects. In the absence of authorised pharmacological treatments, chloroquine, and hydroxychloroquine, which are known as anti-malaria drugs, had been widely used off-label until concerns about their efficacy/safety limited their use to hospitalized patients affected by severe COVID-19. Regardless of their clinical use, their manipulation is necessary since the pure drug substance is not always promptly available and most of the drug products available on the market are tablets designed to be ingested; no liquid dosage forms are available. These are needed for children and the enteral nutrition of inpatients of intensive care units. Considering that both chloroquine and hydroxychloroquine are BCS class I, proper procedures for purifying the preparation from the insoluble excipients may be adopted to avoid clogging of a nasogastric tube and to reduce the drug content variability in the administered doses. The data in this article indicate that compounded oral suspensions containing chloroquine and hydroxychloroquine can be filtered and/or centrifuged without altering the drug assay of the preparation.

Purification of sarcoplasmic reticulum vesicles from horse gluteal muscle

We have analyzed protein expression and enzyme activity of the sarcoplasmic reticulum Ca²⁺-transporting ATPase (SERCA) in horse gluteal muscle. Horses exhibit a high incidence of recurrent exertional rhabdomyolysis, with myosolic Ca²⁺ proposed, but yet to be established, as the underlying cause. To better assess Ca²⁺ regulatory mechanisms, we developed an improved protocol for isolating sarcoplasmic reticulum (SR) vesicles from horse skeletal muscle, based on mechanical homogenization and optimized parameters for differential centrifugation. Immunoblotting identified the peak subcellular fraction containing the SERCA1 protein (fast-twitch isoform). Gel analysis using the Stains-all dye demonstrated that calsequestrin (CASQ) and phospholipids are highly enriched in the SERCA-containing subcellular fraction isolated from horse gluteus. Immunoblotting also demonstrated that these horse SR vesicles show low content of glycogen phosphorylase (GP), which is likely an abundant contaminating protein of traditional horse SR preps. The maximal Ca²⁺-activated ATPase activity (V_max) of SERCA in horse SR vesicles isolated using this protocol is 5‒25-fold greater than previously-reported SERCA activity in SR preps from horse skeletal muscle. We propose that this new protocol for isolating SR vesicles will be useful for determining enzymatic parameters of horse SERCA with high fidelity, plus assessing regulatory effect of SERCA peptide subunit(s) expressed in horse muscle.

Therapeutic Plasma Exchange Using Membrane Plasma Separation

Therapeutic plasma exchange is a blood purification technique designed for the removal of large molecular weight toxins such as pathogenic antibodies and lipoproteins. Plasma exchange can be performed either by membrane separation or centrifugation. Centrifugal plasma exchange is more common in the United States, while membrane separation is more popular in Germany and Japan. The membrane separation technique is similar to the ultrafiltration procedures performed with a standard dialysis machine but in which the membrane's pores are large enough to allow removal of all circulating molecules while retaining the cellular components. The current availability of plasma separation membranes compatible with CRRT systems has dramatically increased the potential for almost all nephrologists to perform these treatments. This review describes the membrane separation techniques available in the United States, the practical aspects of ordering and operating a membrane separation plasma exchange procedure, and its possible complications.

Optimization of cryopreservation protocols for cooled-transported stallion semen

Freezing cooled-transported semen allows veterinarians and breeders to collect and process the semen of stallions on farm, and then ship the semen to a semen freezing center. There, however, is a lack of standardization of shipping and freezing protocols. The objectives were to optimize and simplify protocols to freeze cooled-shipped semen. In Experiment 1, cooled-transported semen was centrifuged at room temperature or 5 °C before freezing. Sperm variables (motility, membrane integrity, acrosome integrity, membrane fluidity) were evaluated before and after freezing. Centrifugation temperature had no effect on post-thaw semen quality. In Experiment 2, cooled-transported semen was centrifuged at room temperature and cryopreserved in three semen freezing extenders. With use of the improved modified French formula, there was less post-thaw total and progressive motility compared with use of Botucrio or the improved lactose-EDTA formula (P<0.0001). Semen cryopreserved in the improved modified French formula also had a lesser percentage of sperm with intact membranes compared with lactose-EDTA, and a greater percentage of sperm with capacitation-like changes compared with Botucrio (P<0.0001). In Experiment 3, semen diluted in each extender was frozen conventionally or placed directly in a -80 °C ultra-freezer. Freezing in the ultra-freezer resulted in a lesser post-thaw sperm motility, but not membrane and acrosome integrity and capacitation-like changes. In conclusion, centrifugation and addition of freezing extender to cooled transported semen can be performed at room temperature or 5 °C. The Botucrio and lactose-EDTA formula are recommended for conventional cryopreservation of cooled-transported stallion semen as compared with the modified French formula.

Mitigating the formation of monochloropropanediol diesters in vegetable oils by removing their residual sediments

This study investigates whether the formation of monochloropropane diol fatty acid esters (MCPDE) can be mitigated by removing the residual sediments from vegetable oils. Settling and centrifugation were conducted in crude sunflower and palm oil and the purified oils and their sediment-rich fractions were heated and analyzed for their MCPDE content. Increased MCPDE levels by factors of x2 to x6 were found in the sediment-rich fractions of settled sunflower oils compared to the sediment-free oil. The sediment-containing fraction could be however purified by ultracentrifugation resulting in the mitigation of MCPDE levels by a factor of 10. The effect of residual sediment on the MCPDE formation was also confirmed in the case of palm oil showing x2 to x10 more MCPDE formation in the sediment containing fractions compared to the purified oil. These results confirm that the mechanical removal of the trace sediments from crude vegetable oils results in reduced MCPDE levels.

Optimization of a rapid one-step platelet-rich plasma preparation method using syringe centrifugation with and without carprofen

Background

Carprofen and platelet-rich plasma (PRP) are widely used in small animal clinical practice. Separation layers have been used during blood centrifugation to increase platelet yield. The objectives of this study were to (1) identify the optimal centrifugation force for the one-step PRP preparation, (2) determine whether there is an advantage to using carprofen in one-step PRP preparation, and (3) compare platelet morphology from one-step PRP preparation with and without carprofen. We hypothesized that injectable carprofen (emulsion formula) could be used successfully as the separation layer in PRP preparation.

Results

Samples from 14 healthy dogs were used to determine the optimal centrifugation force using one-step PRP preparation in a disposable syringe without carprofen, with forces set at 300, 500, 700, 900, 1100, 1300, and 1500 xg for 5 min. Optimum centrifugation force, plasma volume, and platelet concentrations of one-step PRP preparation were found and recovered at 900 xg, 1.9 ± 0.28 ml, and 260.50 ± 58.39 X 10³ cell/μl, respectively. Samples from 12 healthy dogs were used to determine the optimal force (with forces set at 300, 500, 700, and 900 xg) for 5 min using one-step PRP preparation with carprofen. Optimum centrifugation force, plasma volume, and platelet concentrations for one-step PRP preparation with carprofen were found and recovered at 500 xg, 0.62 ± 0.16 ml and 948.50 ± 261.40 X 10³ cell/μl, respectively. One-step PRP preparation with carprofen increased the platelet yield from baseline by 1.76 and 4.95 fold, respectively. Samples from 3 healthy dogs were used to observe platelet morphologies after centrifugation by scanning electron microscopy. Images of platelets on glass slides from both preparation methods revealed pseudopods emerging from the margins of the discoid platelets.

Conclusions

One-step PRP centrifugation both with and without carprofen increased the platelet yield, but using carprofen (emulsion formula) as a separation layer resulted in a higher platelet yield. The clinical usefulness of PRP products from these methods should be further investigated.

Development of blood-based biomarker tests for early detection of colorectal neoplasia: Influence of blood collection timing and handling procedures

INTRODUCTION

Blood-based, cancer-associated biomarkers are susceptible to a variety of well-known preanalytical factors. The influence of bowel preparation before a diagnostic colonoscopy on biomarker levels is, however, poorly investigated. The present study assessed the influence of bowel preparation on colorectal cancer-associated biomarkers. In addition, the effect of single versus double centrifugation of plasma biomarkers was assessed.

METHODS

Blood samples were collected pre- and post-bowel preparation from 125 subjects scheduled for first time diagnostic colonoscopy due to symptoms attributable to CRC. The samples were separated into serum and EDTA plasma, and analyzed by four independent collaborators for: 1) the proteins AFP, CA19-9, CEA, hs-CRP, CyFra21-1, Ferritin, Galectin-3 and TIMP-1, 2) the proteins BAG4, IL6ST, vWF, CD44 and EGFR, 3) the glycoprotein Galectin-3 ligand, and 4) cell-free DNA (cfDNA). Statistical analysis of biomarker data has been performed using mixed modelling, including repeated measures.

RESULTS

The biomarkers generally showed negligible variation between pre- and post-bowel preparation except for CyFra21-1, Ferritin, BAG4 and cfDNA. CyFra21-1 levels were systematically reduced with 29% (95% CI 21-36%) by bowel preparation (p ≤ 0.0001). Ferritin was not significantly different between pre- and post-bowel preparation (p = 0.07), however the estimated difference (increase) was 18%. BAG4 was systematically reduced by 12% (95% CI 1-22%, p = 0.04), while cfDNA showed a significant increase of 28% (95% CI 17-39%, p < 0.0001). Double centrifugation compared to single centrifugation showed reduced vWF (ratio 0.86, p ≤ 0.0001) and CD44 (ratio 0.85, p = 0.016), but increased IL6ST levels (ratio 1.18, p = 0.014).

CONCLUSIONS

Results of the present study demonstrated systematic, statistically significant differences between pre-bowel and post-bowel preparation levels for three independent blood-based biomarkers (BAG4, CyFra21-1, cfDNA), illustrating the importance of timing of sample collection for biomarker analyses.

How the distribution coefficient of 238U in natural soils is affected by the method used to obtain the soil solution and its dependency on structural characteristics

A systematic study on desorption of uranium in a natural soil has been carried out to reduce the level of uncertainty associated with the method employed to determine the values of the distribution coefficient (K_d). Generally, the operating method used to extract and analyze the soil solution determines the K_d values. Here, the centrifugation method has been used to obtain soil solution extracts. Several procedural parameters have been considered such as incubation time, the level of soil moisture relative to saturation (saturation degree) and centrifugation speed (equivalent to effective suction). In order to analyze the influence of soil structural characteristics, this study considers three grain-size fractions of soil: loamy coarse sand, loamy fine sand, and loam, all of which are obtained from a natural soil collected in a uranium mineralized area. Our results indicate that neither incubation time nor centrifugation speed influence the determination of K_d for uranium. The results also indicate that the level of soil moisture is the most important factor for determining ²³⁸U-K_d. It has been shown that the influence of moisture on K_d also depends on the structural characteristic of the soil. For the loamy coarse sand subsample, the moisture level during the incubation period showed a significant influence on the K_d. In addition, through the use of regression analysis, the pH was identified as the cofactor with the greatest influence on K_d of uranium.

Single-Layer Colloid Centrifugation as a Method to Process Urine-Contaminated Stallion Semen After Freezing-Thawing

Urospermia is a major ejaculatory dysfunction affecting stallions. It has been thought that urine-contaminated semen should not be cryopreserved; however, on select cases, urine contamination of semen cannot be avoided. A recent study suggested that urospermic semen can be cryopreserved after cushion centrifugation and extension. Thus, this study aimed to assess the use of single-layer colloid centrifugation (SLC) to process frozen-thawed urine-contaminated stallion semen. Raw ejaculates (n = 55) from eight stallions were split into three groups: no urine, low (20%), or high (50%) urine contamination. Semen was extended 1:1, cushion-centrifuged, and resuspended at 200 million sperm/mL in BotuCrio. Resuspended semen was loaded in 0.5 mL straws and cryopreserved in liquid nitrogen. Samples were thawed (37°C for 30 seconds) and processed by SLC (400 g/30 minutes). Percentages of total motility (TM) and progressive motility (PM) were assessed with computer-assisted semen analyzer. Sperm viability (%VIAB) and yield were assessed with a NucleoCounter before and after gradient centrifugation. Data were analyzed with two-way ANOVA and Tukey's test. The motility parameters TM before SLC (control: 35 ± 2; low: 33 ± 0.7; high: 22 ± 1.8) after SLC (control: 51 ± 3.6; low: 42 ± 2.2; high: 25 ± 2.8) and PM before SLC (control: 24 ± 1.8; low: 21 ± 1.14; high: 12 ± 1.5) and after SLC (control: 40.3 ± 3.2; low: 31 ± 3.9; high: 14 ± 2) significantly decreased with increasing urine contamination. Urine contamination marginally reduced (P < .05) sperm viability after cryopreservation before SLC (control: 45 ± 0.7; low: 27 ± 0.2; high: 27 ± 0.3) and after SLC (control: 54 ± 0.5; low: 49 ± 0.7; high: 38 ± 0.6). Recovery rates of sperm after centrifugation were not significantly different between groups. In conclusion, urine contamination affects sperm motility parameters in a dose-dependent manner. Post-thaw SLC selected sperm with higher motility and viability in control and low groups but only selected sperm with higher viability in the high group.

Determination of Protein Phase Diagrams by Centrifugation

Liquid-liquid phase separation (LLPS) underlies the formation of biomolecular condensates, i.e., membrane-less compartments in cells that carry out functions related to RNA metabolism, stress adaptation, transport, or signaling. Examples of such biomolecular condensates are the nucleolus, nuclear speckles, promyelocytic leukemia protein (PML) bodies and paraspeckles in the nucleus, and stress granules and P bodies in the cytoplasm. Other structures in cells that are not typically viewed as bona fide compartments also seem to be formed via LLPS as recently elucidated, including heterochromatin, super-enhancers, and membrane receptor clusters. Key protein and/or RNA components of these biomolecular condensates form a scaffold via LLPS. Other constituents incorporate into this scaffold as clients. To understand the sequence features and interactions that mediate biomolecular condensate formation in cells, it is useful to quantify phase separation of pure components in vitro. Microscopy and turbidity measurements can be used to determine the concentration of a protein above which it phase separates, the so-called saturation concentration. Here, we describe experiments for the determination of full coexistence lines of phase-separating proteins by centrifugation. Coexistence lines are reconstructed from coexisting light and dense phase concentrations of the protein, and we present them as so-called phase diagrams. Phase diagrams allow the quantitative comparison of phase separation for proteins and their mutants under different conditions. They are thus important for our nuanced understanding of the driving forces underlying liquid-liquid phase separation in vitro. Such results have direct applicability for understanding phase separation-driven compartmentalization of cells.

Stallion Sperm Integrity After Centrifugation to Reduce Seminal Plasma Concentration and Cool Storage for 4 days

The objective of the study was to investigate if reducing the seminal plasma of stallion extended semen by centrifugation once will suffice to maintain acceptable semen quality for insemination after 4 days of cool storage. Collected semen was extended to 25 × 10⁶ sperm/mL and subjected to one of the following treatments: noncentrifuged (control), centrifuged for 10 minutes at 900 × g and 1800 × g. The supernatant was partially removed, and the sperm pellet, reconstituted and re-extended. It was then placed in a passive cooling device overnight and then transferred to a refrigerator for the remainder of the cooling period. At day 0, 2, and 4, total motility (TM), progressive motility (PM), and plasma (PLM) and acrosomal membrane integrity were assessed. Centrifuged groups had higher TM and PM at day 4 than the control group (P < .05). Likewise, centrifuged groups had higher intact PLM in day 4 (P < .05). A single centrifugation cycle to reduce seminal plasma concentration will suffice to preserve sperm integrity acceptable for an artificial insemination dose up to 4 days of cool storage.

The Impact of Duration and Force of Centrifugation on Platelet Content and Mass in the Preparation of Platelet-Rich Plasma

PURPOSE

Platelet-rich plasma (PRP) is an autologous prepared plasma enriched with platelets and obtained after a centrifugal separation and aggregation procedure. However, the optimized preparation protocol for PRP is still controversial and there are no standardized preparation protocols. The aim of this study is to show the effect of time and force of the centrifugation on the concentrations of platelets and to optimize the effective PRP preparation protocol.

METHODS

For the study, whole blood was drawn into 24 different 6-ml standard tubes containing 0.6 ml anticoagulant citrate dextrose solution-formula A. The samples were centrifuged separately at forces of 45×g, 180×g, 400×g, 725×g, 1130×g and 1630×g for 5, 10, 15 and 20 min. Every sample was analyzed, and a comparison was made between all groups.

RESULTS

No significant difference was observed in terms of platelet concentration, mean platelet volume or platelet mass between all groups (p > 0.05). The mean ± SD of platelet mass in baseline is 1890 ± 134 × 10³ fL/μL. The mean ± SD of platelet mass in the high centrifugal force of 1630×g was 3395 ± 564 × 10³ fL/μL, 2638 ± 425 × 10³ fL/μL, 2355 ± 449 × 10³ fL/μL and 2109 ± 41 × 10³ fL/μL over times of 5, 10, 15 and 20 min, respectively. The mean ± SD of platelet mass in the low centrifugal force of 45×g was 2002 ± 1623 × 10³ fL/μL, 2491 ± 1591 × 10³ fL/μL, 2611 ± 876 × 10³ fL/μL and 3003 ± 511 × 10³/μL over times of 5, 10, 15 and 20 min, respectively.

CONCLUSIONS

Platelets should be evaluated with platelet mass not including platelet concentrations alone, but also with mean platelet volume, which symbolizes the size of platelets while comparing platelet-rich plasma preparation protocols and kits. This could be a new starting point for comparison of PRP for all applications in the literature. All centrifugation forces and times could produce biologically reactive PRP. It may be only suggested that if high acceleration force is used, low durations should be selected, or if low acceleration force is used, long time of centrifugation should be selected.

NO LEVEL ASSIGNED

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Microalgae harvest influences the energy recovery: A case study on chemical flocculation of Scenedesmus obliquus for biodiesel and crude bio-oil production

In the present study, centrifugation was used as a standard harvest method, while chemical flocculation was comparatively used as a cost-effective harvest method for microalgae. Lipid recovery from the centrifuged cells was 17.4%, which significantly increased by flocculation to 20.7%. Although both harvest methods showed similar thermal decomposition patterns, flocculated biomass showed 15.7% higher bio-char formation than the centrifuged cells, which resulted in significant reduction in the bio-oil yield by 18.5%. The estimated energy output of bio-oil using centrifugation and flocculation were 0.87 and 0.68 GJ per ton, respectively. For biodiesel production, the energy output using centrifugation and flocculation were 0.177 and 0.211 GJ per ton, respectively. Due to the higher biodiesel yield, better bio-oil quality and lower energy consumption, flocculation was suggested by the present study as a superior method over centrifugation for microalgae harvest from the economic point of view.