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At least 109 records · Page 6Linked to original sources
PubMed1998

Centrifugal pulsing increases the recovery of viable spermatozoa.

PURPOSE: Our purpose was to compare the number and quality of spermatozoa recover following the standard centrifugation method with those after pulsing the relative centrifugal field during centrifugation. METHODS: A prospectively controlled in vitro study using ejaculates from 10 healthy sperm donors was undertaken. Number of sperm and sperm motility at 0, 3, and 24 hr post-incubation at 5 degrees C in TEST-yolk results determined the efficacy of the centrifugation techniques. RESULTS: The number of sperm and sperm motility at 0, 3, and 24 hr post-incubation at 5 degrees C in TEST-yolk were significantly higher for the sperm recovered following pulse centrifugation compared with those after standard centrifugation. CONCLUSIONS: Pulsing the relative centrifugal field during centrifugation yields a higher number of viable spermatozoa.

Adult↗
PubMed2004

[The influence of centrifugation on quality and freezability of stallion semen].

The aim of the present study was to investigate the influence of various centrifugation methods on sperm loss and quality of frozen-thawed semen. From at a total of 8 Warmblood stallions of the National Stud Farm in Avenches, 3 ejaculates each were collected and seminal plasma was removed using 3 different centrifugation regimes. In method I (reference method) centrifugation occurred by a speed of 600 x g during 10 minutes. In method II 1000 x g was used during 2 minutes while in method III centrifugation was performed by 2000 x g during 2 minutes. After centrifugation 90%, of the supernatant was removed and sperm loss calculated. After resuspension of the pellet with freezing medium, functional membrane integrity was evaluated by HOS-test and motility determined. In frozen-thawed semen motility, viability as well as functional membrane integrity (HOS-test) and acrosome status using chlortetracyclinassay (CTA) were assessed. Our results demonstrate that mean sperm loss (I, 1.9%; II, 8.7%; III, 3.7%) was significantly (P < 0.05) different between the three centrifugation regimes. Regarding semen quality of frozen-thawed semen, HOS in method III (52.1%) was significantly lower than in methods I (55.5%) and II (55.3%). Evaluation of the acrosome status by CTA showed that more than 70% of sperm cells were capacitated and 25% capacitated and acrosome reacted. From our results we conclude that sperm loss and functional membrane integrity (HOS-test) in frozen-thawed semen were significantly influenced by the centrifugation regime. Therefore, stallion semen should be centrifuged at 600 x g during 10 minutes before freezing in order to obtain low sperm loss and a good quality of frozen-thawed semen.

Acrosome↗
PubMed1999

Effects of tilt of the gravito-inertial acceleration vector on the angular vestibuloocular reflex during centrifugation.

Effects of tilt of the gravito-inertial acceleration vector on the angular vestibuloocular reflex during centrifugation. Interaction of the horizontal linear and angular vestibuloocular reflexes (lVOR and aVOR) was studied in rhesus and cynomolgus monkeys during centered rotation and off-center rotation at a constant velocity (centrifugation). During centered rotation, the eye velocity vector was aligned with the axis of rotation, which was coincident with the direction of gravity. Facing and back to motion centrifugation tilted the resultant of gravity and linear acceleration, gravito-inertial acceleration (GIA), inducing cross-coupled vertical components of eye velocity. These components were upward when facing motion and downward when back to motion and caused the axis of eye velocity to reorient from alignment with the body yaw axis toward the tilted GIA. A major finding was that horizontal time constants were asymmetric in each monkey, generally being longer when associated with downward than upward cross coupling. Because of these asymmetries, accurate estimates of the contribution of the horizontal lVOR could not be obtained by simply subtracting horizontal eye velocity profiles during facing and back to motion centrifugation. Instead, it was necessary to consider the effects of GIA tilts on velocity storage before attempting to estimate the horizontal lVOR. In each monkey, the horizontal time constant of optokinetic after-nystagmus (OKAN) was reduced as a function of increasing head tilt with respect to gravity. When variations in horizontal time constant as a function of GIA tilt were included in the aVOR model, the rising and falling phases of horizontal eye velocity during facing and back to motion centrifugation were closely predicted, and the estimated contribution of the compensatory lVOR was negligible. Beating fields of horizontal eye position were unaffected by the presence or magnitude of linear acceleration during centrifugation. These conclusions were evaluated in animals in which the low-frequency aVOR was abolished by canal plugging, isolating the contribution of the lVOR. Postoperatively, the animals had normal ocular counterrolling and horizontal eye velocity modulation during off-vertical axis rotation (OVAR), suggesting that the otoliths were intact. No measurable horizontal eye velocity was elicited by centrifugation with angular accelerations </=40 degrees /s2 and angular velocities </=400 degrees /s. We conclude that in rhesus and cynomolgus monkeys, differences between horizontal eye velocities recorded during facing and back to motion constant velocity centrifugation can be explained by orienting effects of the GIA tilt on the time constants of the horizontal aVOR and not by a superposed lVOR.

Acceleration↗
PubMed2002

Centrifugation attenuates the fluid shear response of circulating leukocytes.

Human leukocytes retract pseudopods in response to physiological fluid shear, a phenomenon that serves to keep circulating leukocytes in a spherical state. We show here that leukocyte fluid shear response is attenuated irreversibly by centrifugation. Inhibition of shear response depends on duration and magnitude of acceleration during centrifugation and time duration after centrifugation. Even after low-speed centrifugation, leukocytes no longer retract pseudopods during shear application. After centrifugation at higher acceleration, leukocytes project pseudopods instead of retracting during shear application, which can be suppressed by a calcium channel blocker. We examined the role of fluid shear response in vivo by reintroduction of centrifuged cells into the rat circulation. Centrifuged leukocytes have a significantly enhanced tendency to migrate into tissue. These observations indicate that centrifugation may irreversibly damage the fluid shear response of leukocytes. It causes an impaired leukocyte behavior after reintroduction into the circulation, suggesting that shear response is a requirement for normal passage of leukocytes through the microcirculation.

Animals↗
PubMed2003

Effect of 30-min +3 Gz centrifugation on vestibular and autonomic cardiovascular function.

INTRODUCTION: Repeated exposure to increased +Gz enhances human baroreflex responsiveness and improves tolerance to cardiovascular stress. However, it is not known whether such enhancements might also result from a single, more prolonged exposure to increased +Gz. Our study was designed to investigate whether baroreflex function and orthostatic tolerance are acutely improved by a single prolonged exposure to +3 Gz, and moreover, whether changes in autonomic cardiovascular function resulting from exposure to increased +Gz are correlated with changes in otolith function. METHODS: We exposed 15 healthy human subjects to +3 Gz centrifugation for up to 30 min or until symptoms of incipient G-induced loss of consciousness (G-LOC) ensued. Tests of autonomic cardiovascular function both before and after centrifugation included: 1) power spectral determinations of beat-to-beat R-R intervals and arterial pressures; 2) carotid-cardiac baroreflex tests; 3) Valsalva tests; and 4) 30-min head-up tilt tests. Otolith function was assessed during centrifugation by the linear vestibulo-ocular reflex and both before and after centrifugation by measurements of ocular counter-rolling and dynamic posturography. RESULTS: Of the 15 subjects who underwent prolonged +3 Gz, 4 were intolerant to 30 min of head-up tilt before centrifugation but became tolerant to such tilt after centrifugation. The Valsalva-related baroreflex as well as a measure of the carotid-cardiac baroreflex were also enhanced after centrifugation. No significant vestibular-autonomic relationships were detected beyond a vestibular-cerebrovascular interaction reported earlier in a subset of seven participants. CONCLUSIONS: A single prolonged exposure to +3 Gz centrifugation acutely improves baroreflex function and orthostatic tolerance.

Adult↗
PubMed1986

Variations in the density of bone cement after centrifugation.

Barium sulfate added to bone cement to provide radiopacity has a density about four times greater than that of polymerized radiolucent bone cement. Because centrifugation might make a clinically significant change in the distribution of barium sulfate, this process was studied. Radiolucent and radiopaque Simplex-P bone cement (Howmedica, Inc., Rutherford, New Jersey) were mixed with and without cooling and centrifuged for two or four minutes at 2,000 g or 1,000 g (gravity acceleration). The density of sections of the hardened bone cement was measured using the Archimedes principle. Erythromycin and colistin were added to cement batches to test whether or not centrifugation affected the distribution of antibiotics. Direct and radiographic observation and density measurements (cooled specimens, 2,000 g, p less than 0.01) verified that barium sulfate does accumulate at the bottom of the centrifugation tubes. Thin sections of the bone cement revealed that only larger particles (20-100 micron) of barium sulfate were deposited at the bottom. No evidence of redistribution of antibiotics after centrifugation was seen. It is recommended that Simplex-P bone cement be reformulated to eliminate concern about inhomogeneities that arise from centrifugation. Further, it is recommended that cooled, centrifuged antibiotic cement be used for long-stem revision hip surgery, where longer setting times are necessary, and room temperature cement for "fresh" hip surgery. A total centrifuge time of two minutes with a 2,000 g maximum force is recommended.

Anti-Bacterial Agents↗
PubMed1993

Centrifugal enhancement of human immunodeficiency virus type 1 infection and human cytomegalovirus gene expression in human primary monocyte/macrophages in vitro.

In an effort to facilitate the efficiency of human immunodeficiency virus type 1 (HIV-1) and/or human cytomegalovirus (HCMV) infection in primary monocyte/macrophages in vitro, the effect of low-speed centrifugation was studied. The infectivity of three strains (Bal, Ada-M, and IIIB) of HIV-1 tested was significantly enhanced by centrifugal inoculation at a force of 1500g for 60 min. Reverse transcriptase activity and HIV-1 p24 antigen in primary monocyte/macrophages infected by a centrifugal inoculation technique were detectable 3-7 days earlier and were more than 10-fold greater in magnitude (at an early stage of the infection) than those of control cells infected by the conventional inoculation technique. Examination of the cells by indirect immunofluorescence revealed higher expression of HIV-1 p24 protein in the monocyte/macrophages infected by the centrifugal inoculation technique. These differences were directly related to centrifugal inoculation and were evident up to 3 weeks after infection. Enhancement was not observed when centrifugation was carried out before or after HIV-1 infection. Centrifugal inoculation of HCMV also enhanced its immediate-early and early gene expression up to 30- to 50-fold, although neither late nuclear antigens and glycoproteins of HCMV nor infectious virus was detected in HCMV-infected monocyte/macrophage cultures. These results show that centrifugal inoculation is a useful technique for improving the efficiency of HCMV and HIV-1 infection in vitro.

Cells, Cultured↗
PubMed2002

Effect of centrifugation on in vitro survival of fresh diluted canine spermatozoa.

Prostatic fluid is unsuitable for preserving dog semen at 4 degrees C and exerts harmful effects upon the spermatozoa during the freezing process. Centrifugation immediately after sperm collection is a common method to remove prostatic admixture. In the present study, dog semen, diluted to 25 x 10(6)/ml, was exposed for 5 min to four different centrifugation speeds (180 x g, 720 x g, 1620 x g and 2880 x g) to determine subsequent sperm losses in the supernatant and to assess sperm survival over time. Using 180 x g as centrifugation speed, 8.9% of the sperm cells was lost upon supematant removal. Using 720 x g, 1620 x g or 2880 x g, sperm losses were lower, 2.3, 0.4 and 0.006%, respectively. After centrifugation, the sperm pellet was rediluted in egg-yolk-Tris extender, cooled and stored for 3 days at 4 degrees C. Motility, progressive motility, membrane integrity and sperm morphology were assessed daily. Acrosomal status was assessed after 3 days of storage. The only functional parameter which was influenced by centrifugation speed was membrane integrity as evaluated by means of SYBR14-PI staining: significantly more dead and moribund sperm cells were found after centrifugation at 1620 x g and 2880 x g after 48 and 72 h of storage at 4 degrees C. When higher initial sperm concentrations (50 x 10(6), 75 x 10(6) or 100 x 10(6)/ml) were evaluated for sperm losses, less than 2.3% of the initial total sperm cells was lost at lower centrifugation speeds. We conclude that centrifuging dog sperm for 5 min at 720 x g is the best strategy to remove prostatic fluid because the loss of sperm cells is acceptable and the functional parameters of the spermatozoa are well preserved, even after 3 days of storage.

Acrosome↗
PubMed1980

Effects of centrifugation stress on pituitary-gonadal function in male rats.

The effects of centrifugation for various lengths of time were investigated on circulating levels of luteinizing hormone (LH) and testosterone in male rats. In a chronic 52-day experiment, centrifugation at 4.1 G significantly reduced LH and testosterone levels for the entire period. Centrifugation at 2.3 G had less effect inasmuch as LH levels were not significantly decreased and testosterone levels were significantly reduced only during the first few days of centrifugation. In more acute experiments, centrifugation at 4.1 G for 4 h resulted in reduced testosterone levels, whereas centrifugation for 15 min did not significantly alter the hormone levels. These results indicate that centrifugation can decrease circulating LH and testosterone levels if the gravitational force is of sufficient magnitude and is maintained for a period of hours. Chronic centrifugation may also inhibit the acute excitatory response of LH to handling and ether stress.

Animals↗
PubMed2006

A methodology for centrifuge selection for the separation of high solids density cell broths by visualisation of performance using windows of operation.

Expression systems capable of growing to high cell densities are now readily available and are popular due to the benefits of increased product concentration. However, such high solids density cultures pose a major challenge for bioprocess engineers as choosing the right separation equipment and operating it at optimal conditions is crucial for efficient recovery. This study proposes a methodology for the rapid determination of suitable operating conditions for the centrifugal recovery of high cell density fermentation broths. An ultra scale-down (USD) approach for the prediction of clarification and dewatering levels achieved in a range of typical high-speed centrifuges is presented. Together with a visualisation tool, a Window of Operation, this provides for the rapid analysis of separation performance and evaluation of the available operating conditions, as an aid in the selection of the centrifuge equipment most appropriate for a given process duty. A case study examining centrifuge selection for the processing of a high cell density Pichia pastoris culture demonstrates the method. The study examines semi-continuous disc-stack centrifuges and batch-operated machines such as multi-chamber bowls and Carr Powerfuges. Performance is assessed based on the variables of clarification, dewatering and product yield. Inclusion of limits imposed by the centrifuge type and design, and operation itself, serve to constrain the process and to define the Windows of Operation. The insight gained from the case study provides a useful indication of the utility of the methodology presented and illustrates the challenges of centrifuge selection for the demanding case of high solids concentration feed streams.

Biotechnology↗
PubMed2003

Detection of circulating tumor cells in blood using an optimized density gradient centrifugation.

The aim of the study was to compare the new density gradient centrifugation system OncoQuick with the standard density gradient centrifugation system Ficoll for improved tumor cell enrichment in blood of tumor patients. Evaluation of OncoQuick and Ficoll density gradient centrifugation was performed by flow-cytometry and immunocytochemistry using 10 ml unspiked and tumor cell-spiked blood samples of tumor-free probands. From 10 ml blood, OncoQuick density gradient centrifugation separated a cell fraction which consisted of a mean cell number of 9.5x10(4) mononuclear cells compared to 1.8x10(7) cells by Ficoll. Density gradient centrifugation of tumor cell-spiked blood samples with OncoQuick and Ficoll led to similar tumor cell recovery rates, between 70% and 90% for both methods. The improved depletion of mononuclear blood cells by OncoQuick simplified further immunocytochemical evaluation of the enriched cell fraction, which could be spun onto 1-2 glass slides by cytocentrifugation. In comparison, the mononuclear cells separated by Ficoll had to be spun onto more than 50 glass slides for complete immunocytochemical evaluation. Consequently, tumor cell density on each cytospin was higher after OncoQuick preparation compared to Ficoll. Density gradient centrifugation with OncoQuick results in higher relative tumor cell enrichment than Ficoll density gradient centrifugation. This simplifies further immunocytochemical tumor cell detection and is a promising tool for the detection of circulating tumor cells in blood of tumor patients.

Centrifugation, Density Gradient↗
PubMed1995

Centrifugal enhancement of retroviral mediated gene transfer.

Centrifugation has been used for many years to enhance infection of cultured cells with a variety of different types of viruses, but it has only recently been demonstrated to be effective for retroviruses (Ho et al. (1993) J. Leukocyte Biol. 53, 208-212; Kotani et al. (1994) Hum. Gene Ther. 5, 19-28). Centrifugation was investigated as a means of increasing the transduction of a retroviral vector for gene transfer into cells with the potential for transplantation and engraftment in human patients suffering from genetic disease, i.e., gene therapy. It was found that centrifugation significantly increased the rate of transduction into adherent murine fibroblasts and into non-adherent human hematopoietic cells, including primary CD34+ enriched cells. The latter samples include cells capable of reconstitution of hematopoiesis in myeloablated patients. As a step toward optimization of this method, it was shown that effective transduction is: (1) achieved at room temperature; (2) directly related to time of centrifugation and to relative centrifugal force up to 10,000 g; (3) independent of volume of supernatant for volumes > or = 0.5 ml using non-adherent cell targets in test tubes, but dependent upon volume for coverage of adherent cell targets in flat bottom plates; and (4) inversely related to cell numbers per tube using non-adherent cells. The results support the proposal that centrifugation increases the reversible binding of virus to the cells, and together with results reported by Hodgkin et al. (Hodgkin et al. (1988) J. Virol. Methods 22, 215-230), these data support a model in which the centrifugal field counteracts forces of diffusion which lead to dissociation during the reversible phase of binding.

3T3 Cells↗
PubMed2006

Apparent bias in river water inoculum following centrifugation.

We collected four measures of viable bacterial concentration (heterotrophic plate count, total coliform, fecal coliform, and Escherichia coli) and three measures of well color development in Biolog GN2 microtiter plates from water samples that were collected on two or three separate occasions from a fixed site on 19 different streams throughout Oregon. Our goal was to determine whether concentrating the water sample with centrifugation prior to analysis would change the in situ composition of the culturable bacterial assemblage. Each sample was split and one subsample was centrifuged while the other subsample served as a control. A shift in the proportion of each group of culturable bacteria toward more fecal coliform bacteria was observed following centrifugation. In samples with the lowest initial heterotrophic bacterial densities (under 50CFU/100ml), the observed concentration following centrifugation was much lower than expected. However, samples that had high initial heterotrophic bacterial densities (over 1000CFU/100ml) had concentrations at or above expected values following centrifugation, but were biased toward a higher proportion of coliform bacteria. Bacteria in centrifuged subsamples utilized more sole-carbon substrates on Biolog GN2 microtiter plates and showed a shorter lag time prior to tetrazolium color development than their uncentrifuged counterparts. Future research that focuses on characterizing and accounting for the bias associated with centrifugation of water samples held for less than 24h is recommended.

Centrifugation↗
PubMed2006

Efficient centrifugal recovery of Bacillus thuringiensis biopesticides from fermented wastewater and wastewater sludge.

Studies were conducted on harvesting of Bacillus thuringiensis (Bt)-based biopesticides from fermented broths of starch industry wastewater (SIW), wastewater sludge (raw and hydrolyzed-NH and TH, respectively) and semi-synthetic soyameal to enhance entomotoxicity (Tx) by centrifugation. Pertinent factors influencing Tx, solids concentration, pH, temperature and centrifugal force were investigated. The centrifugate solids concentration beyond 100 g/l did not enhance Tx, instead caused pellet formation. Centrifugation efficiency (Tx recovery) was higher at pH 4, and temperature 20 degrees C for starch wastewater (98%), wastewater sludge (98% and 97.8% for non-hydrolyzed and hydrolyzed, respectively) and soya broth (83%). For maximum Tx recovery (SIW-95%; NH-90%; TH-98% and soya-78%), the centrifugal force and time required was 48,000 g and 30 min, respectively. Losses in recovery efficiency were lower for SIW and wastewater sludge in comparison to soya on adopting commercially recommended centrifugal force of 9000 g. The settling velocity computations for different fermented broths enabled calculation of Sigma factor for continuous commercial centrifuge of a given capacity and hence simulation of power requirements. It was established that power requirements for a given Tx recovery efficiency were highest for conventional medium (soya) in comparison to other waste-based fermented broths.

Bacillus thuringiensis↗
PubMed1975

Effect of centrifugation and seminal plasma on motility and fertility of stallion and bull spermatozoa.

The effect of centrifugation of diluted and undiluted semen on equine and bovine spermatozoan motility and fertility was examined, as was the effect of seminal plasma and dilution on stallion spermatozoa during incubation before and after freezing. Centrifugation at 370 g or 829 g was not detrimental (P greater than 0.05) to prefreeze or postfreeze motility if a final concentration of 10% seminal plasma was present. A reduction of seminal plasma from 10% to 2% significantly (P smaller than 0.05) reduced motility. A centrifugal force of 956 g significantly reduced prefreeze but not postfreeze motility of spermatozoa in undiluted semen, regardless of seminal plasma concentration. With a dried skim milk extender, prefreeze and postfreeze motility was greater in samples containing 20% seminal plasma. Motility was depressed by high and low concentrations of seminal plasma. The fertility of frozen or unfrozen stallion spermatozoa was not depressed (P greater than 0.05) by centrifugation at 310 g for 3.5 minutes. In contrast, the fertility of bull semen was significantly (P smaller than 0.05) lowered by centrifugation at 270 g for three minutes. Further, the fertility of centrifuged, diluted bovine semen was lower (P smaller than 0.05) than centrifuged, undiluted semen.

Animals↗
PubMed2001

Novel centrifugal method for simple and highly efficient adenovirus-mediated green fluorescence protein gene transduction into human monocyte-derived dendritic cells.

Dendritic cells (DC) are professional antigen-presenting cells in the immune system. Gene transduction of DC with tumor-associated antigen (TAA) or other genes that enhance the immune reaction has been considered theoretically useful for DC-based immunotherapy. However, gene transduction of DC generated from human peripheral blood monocytes has been difficult due to its low efficiency, even when adenoviral vector was used at high multiplicity of infection (MOI). In the present study, we examined the effect of centrifugal force to enhance efficiency of adenovirus-mediated gene transduction into human monocyte-derived DC at various rotor speeds at various temperatures for various times. We judged the transduction efficiency using enhanced green fluorescence protein (EGFP)-expressing adenoviral vector, and the best condition for centrifugal transduction was determined as 2000 x g at 37 degrees C for 2 h at an MOI of 10 or greater. At an MOI of 50 without centrifugation, the gene transduction efficiency was about 66% and mean fluorescence intensity (MFI) of EGFP expression was about 150 (at 37 degrees C for 2 h). With centrifugal transduction (2000 x g at an MOI of 50 at 37 degrees C for 2 h), 86% or more DC were gene-modified, and especially, MFI of EGFP expression was highly enhanced (MFI: about 3100 or greater). Centrifugally gene-transduced DC were not damaged and were thoroughly functional as measured by mixed lymphocyte reaction (MLR). The centrifugal method was also applicable to human monocytes and K562 cells. The centrifugal transduction method with adenoviral vector might be helpful for the generation of gene-modified DC.

Adenoviridae↗
PubMed1989

Comparison and optimization of three centrifugation systems for reducing porosity of Simplex P bone cement.

Simplex P bone cement was spun for 30, 60, and 120 seconds in three different centrifugation systems (I.E.C. HN-S II, I.E.C. clinical, and Johnson & Johnson) to determine whether differences among the three systems also produce differences in the improvement of the fatigue strength of the cement. The fatigue properties of the cement after centrifugation were also assessed when it was mixed with monomer that had been chilled to 0 degrees C. There were important and statistically significant differences in the fatigue life of Simplex P spun for the same duration in the different centrifuges. Simplex P prepared as recommended by the manufacturer had an average fatigue life of 15,143 cycles in the test system used. Optimum centrifugation among the techniques studied increased the fatigue life nearly fivefold, to the range of 71,000 cycles. Taking into account both the fatigue strength and the viscosity of the cement, the optimum centrifugation system for improving the fatigue life of Simplex P bone cement is the Miller cartridge containing two packs of cement spun in the IEC-HN-S II centrifuge. The authors recommend 30 seconds of centrifugation if the monomer is not chilled prior to mixing and 60 seconds if the monomer is chilled.

Bone Cements↗
PubMed2004

Gravitropism in Phycomyces: threshold determination on a clinostat centrifuge.

The absolute sensitivity of sporangiophores of Phycomyces blakesleeanus to centrifugal acceleration was determined on a clinostat centrifuge. The centrifuge provides centrifugal accelerations ranging from 10(-4) to 6 x g. The rotor of the centrifuge, which accommodates 96 culture vials with single sporangiophores, is clinostatted, that is, turning "head over", at slow speed (1 rev min(-1)) while it is running. The negative gravitropism of sporangiophores is characterized by two components: a polar angle, which is measured in the plane of bending, and an aiming-error angle, which indicates the deviation of the plane of bending from the vector of the centrifugal acceleration. Dose-response curves were generated for both angles with centrifugations lasting 3, 5, and 8 h. The threshold for the polar angle depends on the presence of statoliths, so-called octahedral protein crystals in the vacuoles. The albino strain C171 carAcarR (with crystals) has a threshold near 10(-2) x g while the albino strain C2 carAgeo-3 (without crystals) has a threshold of about 2 x 10(-1) x g. The threshold for the aiming error angle is ill defined and is between 10(-2) and 10(-1) x g. The threshold for the polar angle of the wild type NRRL 1555 (with crystals) is near 8 x 10(-2) x g.

Centrifugation↗