Urinary excretion of prostacyclin in a rat model of uteroplacental vasculature occlusion: implications for fetal growth retardation

1996 ◽  
Vol 8 (5) ◽  
pp. 895 ◽  
Author(s):  
M Hophy ◽  
S Harel ◽  
E Yavin
Keyword(s):  
Blood Flow ◽  
Urinary Concentration ◽  
Fetal Blood ◽  
Experimental Conditions ◽  
Pregnant Rat ◽  
Flow Interruption ◽  
Lower Ability ◽  
Wet Weight ◽  
High Concentrations

An experimental model was devised in the pregnant rat to study by a combined high pressure liquid chromatography and radioimmunoassay technique the accumulation of prostanoids (PNs) in the urine after transient-complete or permanent-partial interruption of the maternal-fetal blood flow. After 8 min of complete restriction of the blood flow in the pregnant rat at 18 days of gestation, the urinary concentration of 6-keto-prostaglandin F1 alpha (6k-PGF1 alpha, the stable prostacyclin metabolite) increased from 4.97 +/- 1.27 ng mg-1 creatinine to 8.09 +/- 2.47 ng mg-1 creatinine and 13.02 +/- 4.5 ng mg-1 creatinine after the second and third post-operative day respectively. The urinary concentration of the 2,3-dinor derivative of prostacyclin reached 12.35 +/- 5.44 ng mg-1 creatinine after the second post-operative day and was reduced to 4.71 +/- 1.94 ng mg-1 creatinine after the third post-operative day. The concentration of thromboxane B2 (TxB2, the stable thromboxane A2 metabolite) increased approximately 7-fold and 13-fold over that of the control after the second and third post-operative day respectively. The urinary concentration of the 2,3-dinor derivative of TxB2 (d-TxB2) increased from about 1.42 +/- 0.3 ng mg-1 creatinine to 4.49 +/- 0.9 ng mg-1 creatinine and 7.76 +/- 2.63 ng mg-1 creatinine under the same experimental conditions. Increases in the urinary concentrations of 6k-PGF1 alpha and d-TxB2 to 94 +/- 27.76 ng mg-1 creatinine and 12.05 +/- 2.26 ng mg-1 creatinine, respectively, were observed on the second post-operative day, after the restriction time was increased to 30 min. Permanent-partial occlusion of the maternal fetal circulation resulted in excretion of PNs in the urine to similar levels produced after transient-complete restriction. High concentrations of prostacyclin (range, 0.8 ng min-1 mg-1 wet weight) were produced in vitro by uterine preparations from restricted animals after the second post-operative day. Placenta preparations from restricted animals generally exhibited a lower ability to synthesize PNS (up to 0.006 ng min-1 mg-1 wet weight) compared with uterine tissue but produced more thromboxane than their sham counterparts. The data suggest that the uterus constitutes the main source for urinary PN excretion following short episodes of maternal-fetal blood flow interruption.

264 TESTOSTERONE IN THE OOCYTE CULTURE DOES NOT ALTER SEX-RATIO OF IN VITRO PRODUCED BOVINE EMBRYOS

2009 ◽  
Vol 21 (1) ◽  
pp. 229
Author(s):  
C. Díez ◽  
P. Bermejo-Alvarez ◽  
A. Gutiérrez-Adan ◽  
J. N. Caamaño ◽  
M. Muñoz ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Cumulus Cells ◽  
Basic Medium ◽  
Bovine Embryos ◽  
Experimental Conditions ◽  
Vitro Fertilization ◽  
Grant Support ◽  
High Concentrations

The production of sex-known offspring is a main objective in reproductive biotechnology. It has been reported that bovine ova developed in follicles with high concentrations of testosterone in vivo yielded significantly more male embryos in vitro (Grant V et al. 2008 Biol. Reprod. 78, 812–815). In this work we aimed to test the effects of testosterone on sex ratio of bovine embryos produced in fully in vitro conditions. Immature bovine cumulus–oocyte complexes (COCs; n = 750) from slaughterhouse ovaries were cultured in 199 HNaCO3 with polyvinyl alcohol (PVA) 0.1 mg mL–1 as a basic medium. Culture was made in two steps, a 24 h meiotic arrest (roscovitine 25 μm), and a subsequent in vitro maturation period with FSH-LH for 24 h. Testosterone (T-86500, Sigma-Aldrich, St. Louis, MO, USA) was added throughout the entire oocyte culture at 0, 30, 300, and 1500 nm. After in vitro fertilization (Day 0), zygotes were freed of cumulus cells by pipetting, and subsequently cultured in SOF + 6 g L–1 BSA up to Day 3. At this time, embryo development was recorded, and all embryos having 3 or more cells were treated with pronase to remove the zona pellucida. Zona-free embryos were washed in PBS containing PVA 0.1 mg mL–1 and individually frozen at –80°C until sex analysis by PCR (Bermejo-Alvarez P et al. 2008 Biol. Reprod. doi:10.1095/biolreprod.108.070169). A total of 252 embryos from 5 replicates were sexed. Data for development and sex-ratio are presented as % LSM ± SD. There were no interactions between testosterone treatment, embryonic sex, and embryonic stage analyzed. Testosterone did not affect development rates (P > 0.05) at any stage: cleavage (47.8 ± 6.8, 56.5 ± 6.8; 50.9 ± 6.8; 62.2 ± 6.8), 3 to 4 cells (40.6 ± 5.2, 45.8 ± 5.2; 37.8 ± 5.2; 47.7 ± 5.2) and >5 cells rates (24.5 ± 4; 27.3 ± 4; 21.3 ± 4; 25.3 ± 4) for 0, 30, 300, and 1500 nm testosterone, respectively. Cumulative percentages of male embryos were as follows: 53 ± 8 (n = 56), 42.6 ± 8 (n = 52), 53.6 ± 6 (n = 81) and 57.6 ± 8 (n = 63) for 0, 30, 300, and 1500 nm groups respectively (P > 0.05). These results show that the testosterone effects on oocyte ability to select Y-chromosome bearing spermatozoa are not reproducible in vitro under the present experimental conditions. Grant support: MEC, project AGL2008-01530; RTA2008-0082; M. Muoz is supported by FICYT.

Effects of hypoxia and ischemia on autoregulation in postnatal intestine

1991 ◽  
Vol 261 (1) ◽  
pp. G152-G157 ◽  
Author(s):  
P. T. Nowicki ◽  
C. E. Miller ◽  
R. C. Edwards
Keyword(s):  
Blood Flow ◽  
Pressure Reduction ◽  
Experimental Conditions ◽  
Hypoxic Conditions ◽  
Significant Relationships ◽  
Norepinephrine Infusion ◽  
Before And After ◽  
Age Appropriate ◽  
Arterial Po2

Pressure-flow autoregulation was quantified within in vitro intestine from 3- and 35-day-old swine before and after lowering arterial PO2 (hypoxia) or lowering baseline blood flow by means of norepinephrine infusion (ischemia). Autoregulation was elicited by reducing arterial pressure approximately 33% from an age-appropriate baseline pressure. In 3-day-old intestine, autoregulation was unaffected by hypoxia or ischemia: vascular resistance was unchanged after pressure reduction, while Gf averaged -0.33 +/- 0.15 vs. -0.26 +/- 0.05 under control vs. hypoxic conditions, and -0.48 +/- 0.15 vs. -0.46 +/- 0.11 under control vs. ischemic conditions, respectively. In 35-day-old intestine, autoregulation was enhanced by hypoxia and ischemia. Under both experimental conditions, vasodilation was noted in response to pressure reduction: Gf averaged -0.04 +/- 0.14 vs. 0.38 +/- 0.08 under control vs. hypoxic conditions, and -0.12 +/- 0.10 vs. 0.28 +/- 0.08 under control vs. ischemic conditions, respectively. Regression analysis revealed a significant inverse linear correlation between Gf and venous PO2 in older, but not younger, subjects. Significant relationships between Gf and blood flow were not demonstrated in either group under any experimental condition. We conclude that autoregulation is enhanced within in vitro intestine from 35-, but not 3-day-old, swine during hypoxia or ischemia, and that reduction of venous PO2 is the principal factor responsible for the effect noted in older subjects.

Regional differences in catecholamine concentrations in bovine ovaries analysed by high-performance liquid chromatography

1991 ◽  
Vol 129 (2) ◽  
pp. 221-226 ◽  
Author(s):  
P. A. Denning-Kendall ◽  
M. L. Wild ◽  
Wathes D. C.
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Molar Ratio ◽  
Corpora Lutea ◽  
Wet Weight ◽  
High Concentrations ◽  
Highly Correlated ◽  
Very High

ABSTRACT Bovine corpora lutea and ovarian stroma were analysed by high-performance liquid chromatography for catecholamine content. High concentrations (up to 102 nmol/g wet weight) were found in both 'central' stroma, containing many blood vessels, and 'peripheral' stroma. Central stroma contained noradrenaline and some dopamine, whereas peripheral stroma contained a higher proportion of dopamine and also significant amounts of 3,4-dihydroxyphenylacetic acid (DOPAC). Occasional samples of stroma had very high amounts of dopamine, suggesting that it is stored in specific regions. Corpora lutea, although devoid of direct innervation, contained dopamine (up to 5·3 nmol/g) and noradrenaline (up to 1·2 nmol/g). The average dopamine: noradrenaline molar ratio was 1·19 : 1 and the concentrations of dopamine and noradrenaline were highly correlated (P < 0·002). The concentration of dopamine was significantly higher in the early luteal phase of the oestrous cycle than during the rest of the cycle or in pregnancy. The levels of noradrenaline and dopamine present in corpora lutea are sufficient to modulate the production of both oxytocin and progesterone by luteal cells in vitro. Journal of Endocrinology (1991) 129, 221–226

scholarly journals Gonadotropin Dependent Neuregulin1 Signaling Regulates Luteal Cell Survival

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A766-A767
Author(s):  
Jennifer Jones ◽  
Saswati Banerjee ◽  
Winston E Thompson ◽  
Indrajit Chowdhury
Keyword(s):  
Signaling Pathway ◽  
First Trimester ◽  
Immunoblot Analysis ◽  
National Institutes Of Health ◽  
Luteal Cell ◽  
Dependent Manner ◽  
Experimental Conditions ◽  
Pregnant Rat ◽  
Factor Α

Abstract The formation of a functional corpus luteum (CL) is an absolute requirement for reproductive success and is induced by the mid-cycle surge of luteinizing hormone (LH). The CL is a transient ovarian endocrine structure that maintains pregnancy in primate during the first trimester and in rodents during the entire pregnancy by producing steroid hormone progesterone (P4). CL growth and differentiation are tightly regulated by both survival and cell death signals, including endocrine (LH), intra-ovarian regulators, and cell-cell interactions. Neuregulin-1 (NRG1) is a member of the epidermal growth factor-like factor family that mediates it’s effect through the erythroblastoma (ErbB) family. However, the detailed mechanisms associated with the interplay of NRG1 and its receptors in CL function is not known. Therefore, we examined the role and action of NRG1 and its receptors in the gonadotropin signaling pathway that impacts CL functions. Immunocolocalization of NRG1 and ErbB2/3 in pregnant rat CL on day 14 and 21 suggest that both NRG1 and ErbB2/3 are differentially expressed in CL. Moreover, both NRG1 and ErbB2/3 are highly expressed in rat CL on day 14 compared to day 21. Furthermore, in vitro studies revealed that rat luteal cells (LCs) treated with exogenous tumor necrosis factor-α (TNFα, an inflammatory cytokine) promoted apoptosis in LCs in a dose and time-dependent manner. However, the effects of TNFα was attenuated in presence of exogenous NRG1. Under these experimental conditions, immunoblot analysis indicated that exogenous TNFα treatment in the presence of NRG1 inhibits apoptosis through increased levels of the anti-apoptotic proteins Bcl2 and Bclxl, and activation of ErbB2-ErbB3-PI3K-Akt signaling pathway. Collectively, these studies provide new insights on the NRG1-mediated anti-apoptotic mechanism in LCs through ErbB3-ErbB2-PI3K-Akt→Bcl/Bcl-xL pathway and may have important clinical implications. Acknowledgements: This study was supported in part by National Institutes of Health Grants 1 SC1 GM130544-01A1, 1SC3GM113751 and G12RR03034. This research was conducted in a facility constructed with support from the Research Facilities Improvement Grant C06RR018386 from the National Institutes of Health National Center for Research Resources.

Antibody-Targeted HRP Associated with Indole-3-Acetic Acid Induces in Vitro Apoptosis in Hematological Tumors.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1270-1270
Author(s):  
Leandro Felipe Figueiredo Dalmazzo ◽  
Barbara Amelia Aparecida Santana-Lemos ◽  
Rafael Henriques Jacomo ◽  
Aglair Bergamo Garcia ◽  
Eduardo Magalhaes Rego ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Conflicts Of Interest ◽  
Lymphocytic Leukemia ◽  
Cell Group ◽  
Control Groups ◽  
Experimental Conditions ◽  
High Concentrations ◽  
Hematological Tumors ◽  
Set Up

Abstract Abstract 1270 Poster Board I-292 3-Indole-acetic acid (IAA) is a growth hormone found in plants that may be oxidized by horseradish peroxidase (HRP) generating cytotoxic molecules capable of inducing injury in mammal cells, including a variety of human tumors. The aim of this study was to establish an assay based on targeting HRP to hematopoietic tumor cells using antibodies and induce apoptosis by incubation with IAA. To set up the best experimental conditions, we used two human lineages of hematologic tumors: NB4, derived from acute promyelocytic leukemia (APL) and Granta 519, from Mantle Cell Lymphoma (MCL). The targeting of HRP was performed with anti-CD33 or anti-CD19 antibodies (depending on the origin of the cell), followed by incubation with goat anti-mouse antibody conjugated with the enzyme. Eight groups of cells were incubated for 2, 8, 18, 24 and 48 hours: control, HRP targeted, HRP targeted with IAA at 1, 5 and 10 mM, cells not targeted with IAA at 1, 5 and 10 mM. Apoptosis was analyzed by flow cytometry, with anexin V-FITC and propidium iodide. The best experimental conditions for both NB4 and Granta 519 cells were achieved with incubation for 24 h with 10 mM IAA. For NB4, the group targeted with HRP and treated with 10 mM IAA for 24 hours presented 44.1% of apoptosis, whereas the control groups achieved 18.2 to 24.6% (P<0.05). In Granta 519, these results demonstrated higher values of cell death (64.1% versus 15.5 to 20.6% in control groups, P<0.05). Next, we tested cells from 12 patients with acute myeloid leukemia (AML) (six with APL and six with AML others than APL) and from 10 patients with chronic lymphocytic leukemia (CLL). In AML patients others than APL, cells targeted with HRP and treated for 24 h with 10 mM IAA presented 78.8% of apoptosis, while the results with control groups varied from 18.5 to 27.8% (P<0.05). These group of cells in APL patients presented 75.9% of apoptosis, while the controls varied from 18.1 to 44.8% (P<0.05). Interestingly, in APL patients, the cell group treated with 10 mM IAA and not targeted with HRP also had higher apoptosis (44.8%) when compared to the others controls (18.1 to 26.8%) (P<0.05), suggesting that the high concentrations of myeloperoxidase of these cells were capable of activating IAA, in the absence of HRP. In CLL, cells incubated for 24 hours, targeted with HRP and treated 10 mM IAA showed mean apoptosis value of 93.3%. In the control cells, these values varied from 35.7 to 53.7% (P<0.05). Interestingly, cells from patients with CLL presented higher apoptosis than AML cells (P<0.05). Our results demonstrated that the IAA/HRP association was capable of inducing apoptosis in hematopoietic tumors, which was dependant on the IAA dose, the time of IAA exposure and the lineage of the tumor. It is also suggested that the endogenous myeloperoxidase found in APL blasts was capable of activating HRP in the absence of IAA, leading to death of these cells. Disclosures No relevant conflicts of interest to declare.

Influence of steroid hormones on the incorporation of amino acids in uterine and cervical tissue of pregnant women

1987 ◽  
Vol 115 (4) ◽  
pp. 537-543
Author(s):  
Ingrid Wiqvist ◽  
Anders Linde
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Pregnant Women ◽  
Tissue Concentration ◽  
Uterine Tissue ◽  
Protein Synthesis Inhibitors ◽  
Experimental Conditions ◽  
Pregnant Uterus ◽  
High Concentrations

Abstract. The influence of steroids on protein synthesis in cervical and uterine tissue obtained from early and term pregnant women was studied by measuring the incorporation of labelled amino acids into total protein. It was found that oestradiol-17β and progesterone significantly reduced the incorporation of [3H]proline. Androstenedione and cortisol had no significant effect on the incorporation of [3H]proline even at high concentrations. The protein synthesis inhibitors puromycin and cycloheximide blocked the incorporation of [3H]proline to 80–85%. However, there was no further reduction in the incorporation in the presence of oestradiol. Oestradiol was found to reduce the incorporation of [14C]glycine but not that of [3H]serine. The results indicate that oestradiol and progesterone reduce protein synthesis in human cervical and uterine tissue and that this reduction, at least partially, involves collagen synthesis. Oestradiol and progesterone were equipotent under in vitro experimental conditions. The tissue concentration of progesterone in the pregnant uterus is, however, much higher than that of oestradiol. It seems therefore probable that progesterone rather than oestradiol restricts unopposed synthesis of proteins, presumably mainly collagen.

Is Zoledronate Toxic to Human Periodontal Fibroblasts?

2009 ◽  
Vol 89 (1) ◽  
pp. 40-45 ◽  
Author(s):  
H. Agis ◽  
J. Blei ◽  
G. Watzek ◽  
R. Gruber
Keyword(s):  
Soft Tissue ◽  
Tissue Damage ◽  
Alveolar Bone ◽  
Cell Activity ◽  
Osteonecrosis Of The Jaw ◽  
Soft Tissue Damage ◽  
Experimental Conditions ◽  
High Concentrations ◽  
Apoptosis And Necrosis

Exposed necrotic alveolar bone is a hallmark of bisphosphonate-related osteonecrosis of the jaw. However, it is unknown whether zoledronate causes soft-tissue damage via adverse actions toward periodontal fibroblasts. We therefore examined whether zoledronate causes a cytotoxic response in fibroblasts isolated from the gingiva and the periodontal ligament. We report that micromolar concentrations of zoledronate and serum-free conditions decreased cell activity, as measured by assays for formazan formation, proliferation, and protein synthesis. Under these conditions, periodontal fibroblasts underwent apoptosis and necrosis, as indicated by cleavage of PARP and membrane disruption, respectively. However, these adverse effects of zoledronate were mitigated by the presence of serum. Moreover, zoledronate bound to calcium phosphate failed to reduce cell activity. Analysis of these data suggests that the cytotoxic responses of periodontal fibroblasts require high concentrations of zoledronate and depend on the in vitro experimental conditions. Whether these findings translate into soft-tissue damage will require further investigation.

20 EFFECT OF PENICILLAMINE, HYPOTAURINE, AND EPINEPHRINE TREATMENT ON MOTILITY, HYPERACTIVITY AND ACROSOME REACTION OF RAM SPERMATOZOA

2017 ◽  
Vol 29 (1) ◽  
pp. 117
Author(s):  
K. El-Shahat ◽  
T. Ismail ◽  
M. Badr ◽  
K. Zaki
Keyword(s):  
Phase Contrast ◽  
Acrosome Reaction ◽  
Experimental Conditions ◽  
Maximum Value ◽  
Contrast Microscope ◽  
High Concentrations ◽  
Ram Sperm ◽  
In Vitro Induction ◽  
In Vitro Treatment

The aim of this study was to determine the effects of in vitro treatment of freshly ejaculated ram spermatozoa with different concentrations of penicillamine, hypotaurine, and epinephrine (PHE) at different incubation times on motility, hyperactivity (HA) and acrosome reaction (AR). Freshly ejaculated spermatozoa collected from three rams were pooled and then subjected to swim up technique in modified sperm Tyrode’s albumin lactate pyruvate (S-TALP) medium supplemented with different concentrations of PHE (0, 10, 20, 30, 40, 50, 75, and 100 mM). Following incubation (0, 1, 2, 3 and 4 h), sperm motility and hyperactivity were examined under the phase contrast microscope and acrosome reaction was detected by staining of the spermatozoa with silver nitrate. Results showed that treatment of spermatozoa with high concentrations of PHE (30, 40, 50, 75, and 100 mM) significantly increased the motility when compared with the control immediately after dilution (82.0, 82.0, 81.0, 82.0, 82.0 v.76.0%, respectively).This increase existed for the first and second hours of incubation. However, when the incubation time was increased for more than 2 h total motility significantly decreased (P < 0.05, ANOVA) as compared with the control. The same trend was observed in hyperactive motility. Treatment of spermatozoa with 50 and 75 mM of PHE for 1 h significantly increased the percentage of sperm with incomplete AR (20.0 and 27.0% respectively). At 4 h incubation, (49.0%) of spermatozoa treated with 75 mM PHE had undergone complete AR. Furthermore, the maximum value of total acrosome reaction (73.0%) was achieved at 4 h post incubation after addition of 75 mM PHE to ram sperm. In conclusion, under our experimental conditions, 75 mM PHE for 4 h was considered the best concentration of PHE for treatment of ejaculated ram spermatozoa for in vitro induction of acrosome reaction.

Kinetics of Mucosal Influx of Glycylsarcosine, Glycine and Leucine into Hamster Jejunum and Ileum in Vitro

1979 ◽  
Vol 56 (1) ◽  
pp. 25-31 ◽  
Author(s):  
H. P. Schedl ◽  
D. Burston ◽  
E. Taylor ◽  
D. M. Matthews
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Substrate Concentration ◽  
Experimental Conditions ◽  
Simple Diffusion ◽  
Distal Small Intestine ◽  
Diffusion Component ◽  
Wet Weight ◽  
Kinetics Of

1. This paper describes an investigation of the kinetics of influx of the dipeptide glycylsarcosine and the amino acids glycine and l-leucine into rings of everted hamster small intestine in vitro, in proximal and distal small intestine (jejunum and ileum). Results were expressed per unit wet weight of intestine. 2. At all concentrations studied (0·1–100 mmol/l), influx of glycylsarcosine was more rapid in the jejunum than in the ileum. In contrast, at all concentrations studied, influx of glycine and leucine was more rapid in the ileum than the jejunum. 3. Estimates of the simple diffusion component in total influx were made. This component became increasingly large as the substrate concentration was raised. After correction for simple diffusion, transport of all three substrates conformed to Michaelis-Menten kinetics in both jejunum and ileum. Values for simple diffusion, apparent Kt and Vmax. are reported. 4. Possibly physiological implications of the results are discussed, and it is pointed out that under experimental conditions similar to our own, simple diffusion is too large a component in total influx to be ignored.

Observations of Frozen-Hydrated Microtubules

1990 ◽  
Vol 48 (1) ◽  
pp. 504-505
Author(s):  
D. Chrétien ◽  
D. Job ◽  
R.H. Wade
Keyword(s):  
Fourier Transforms ◽  
Structural Complexity ◽  
Image Contrast ◽  
Phase Behaviour ◽  
Experimental Conditions ◽  
Thin Sections ◽  
Surface Lattice ◽  
Cilia And Flagella ◽  
Outstanding Question

Microtubules are filamentary structures found in the cytoplasm of eukaryotic cells, where, together with actin and intermediate filaments, they form the components of the cytoskeleton. They have many functions and show various levels of structural complexity as witnessed by the singlet, doublet and triplet structures involved in the architecture of centrioles, basal bodies, cilia and flagella. The accepted microtubule model consists of a 25 nm diameter hollow tube with a wall made up of 13 paraxial protofilaments (pf). Each pf is a string of aligned tubulin dimers. Some results have suggested that the pfs follow a superhelix. To understand how microtubules function in the cell an accurate model of the surface lattice is one of the requirements. For example the 9x2 architecture of the axoneme will depend on the organisation of its component microtubules. We should also note that microtubules with different numbers of pfs have been observed in thin sections of cellular and of in-vitro material. An outstanding question is how does the surface lattice adjust to these different pf numbers?We have been using cryo-electron microscopy of frozen-hydrated samples to study in-vitro assembled microtubules. The experimental conditions are described in detail in this reference. The results obtained in conjunction with thin sections of similar specimens and with axoneme outer doublet fragments have already allowed us to characterise the image contrast of 13, 14 and 15 pf microtubules on the basis of the measured image widths, of the the image contrast symmetry and of the amplitude and phase behaviour along the equator in the computed Fourier transforms. The contrast variations along individual microtubule images can be interpreted in terms of the geometry of the microtubule surface lattice. We can extend these results and make some reasonable predictions about the probable surface lattices in the case of other pf numbers, see Table 1. Figure 1 shows observed images with which these predictions can be compared.

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