P-084 Novel Single-Step Microfluidic Chamber Outperforms Density Gradient Centrifugation in Post-Selection Motility And DNA Integrity

Study question

Does sperm selection by a novel single-step microfluidic chamber offer effective selection of motile sperm without DNA damage compared with Density Gradient Centrifugation (DGC)?

Summary answer

The novel single-step microfluidic chamber is a good alternative to conventional DGC, increasing DNA integrity and progressive sperm motility in recovered sperm populations.

What is known already

High levels of sperm DNA fragmentation (SDF) can have negative impacts on reproductive outcomes such as clinical pregnancy and miscarriage rates. Microfluidic sperm selection technologies have been developed to select sperm with lower level of SDF and higher levels of motility to improve Assisted Reproductive technology (ART) outcomes. While these methods have achieved variable success, very few have proven clinically relevant and fail to perform selection in a robust and simple methodology that can be adopted in clinics.

Study design, size, duration

A prospective cohort study including 21 donated semen samples processed in 2021. Each sample was split to perform DGC and microfluidic sperm selections side-by-side. Laboratory outcomes were evaluated using semen parameters pre and post processing and included concentration, motility, and DNA fragmentation index (DFI).

Participants/materials, setting, methods

The study was performed using samples donated at the Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia. DGC (10 minutes at 300g and 5 minutes wash at 300g) and microfluidic sperm selection (one-step sperm selection;15-minute incubation for selection) were performed with Sydney IVF 80/40 gradients and gamete buffers, respectively. DFI was assessed by chromatin sperm dispersion assay (SCD). Results were analysed by Friedman’s test and differences were considered significant when p-value < 0.05.

Main results and the role of chance

For the unprocessed raw semen, the starting DFI values varied from 3.0 to 23.3% with an average of 11.38% ± 5.51 and motility varied between 25.3% and 86.7% with an average of 56.42% ± 18.57. The device consistently outperformed DGC in all 21 samples for DFI (0.94% ± 1.12 vs 4.87% ±3.69, P = 0.0012) and in 20 of the 21 samples for motility post-processing DGC (90.88% ± 6.8 vs 73.58% ± 14.97, P = 0.0061). The average concentrations of the raw, DGC, and microfluidic sperm samples were 94.5, 74.12, and 3.55 million sperm/mL, respectively. Thus, both DGC and the microfluidic device showed improvements in SDF, motility, and concentration over the raw sample. However, the microfluidic device significantly outperformed DGC in terms of percentage SDF and motility, indicating its potential for clinical implementation.

Limitations, reasons for caution

This cohort study did not include samples from infertile patients. Furthermore, the effect of each sperm selection methods on reproductive outcomes was not a part of the study. A larger number of samples across a range of clinically infertile samples is required to fully characterise the microfluidic devices efficacy.

Wider implications of the findings

The microfluidic device we report here has the potential to become a new tool to improve the efficacy and consistency of sperm selections. When compared to DGC it offers improved sperm motility and DNA integrity from a platform that is simple to use and less skill-based than conventional methods.

Trial registration number

not applicable

P-237 Non-invasive metabolic live cell imaging of early embryo development using adapted confocal microscopy; a safety study

Study question

Is it safe to use metabolic imaging to measure nicotinamide adenine dinucleotide (NADH) associated auto-fluorescence during embryo development using adapted confocal microscopy?

Summary answer

Non-invasive metabolic imaging is safe as no differences were observed between controls and illuminated embryos in terms of embryo development, blastocyst formation and implantation potential.

What is known already

Developing non-invasive methods that are reliable to assess oocyte and embryo quality has been a significant aim for assisted reproductive technologies. Changes in metabolic activity could lead to cell death or abnormal embryo development and low implantation potential. This could potentially be predicted by incorporating non-invasive measurements of metabolism. Metabolic imaging in embryos has been investigated through complex methodologies, however, scientific evidence for its utility during embryo development using simple technology remains unexplored. Measurements of metabolic activity could be a useful tool as the auto-fluorescence of molecules such as NADH is a straightforward representation of mitochondrial function.

Study design, size, duration

Super-ovulated female mice (n = 30) were subjected to mating with 10 males. In-vivo produced embryos collected at the 2-cell stage were divided in control group (n = 151), sham control group (n = 151) and illuminated group (n = 152). Illuminated embryos were assessed for NADH levels during embryo development every 3 hours using arbitrary units of autofluorescence (AU). Produced blastocysts were assessed for total cell and inner-cell-mass (ICM) number (Oct4 immuno-staining) and implantation potential through outgrowth assays in separate experiments.

Participants/materials, setting, methods

F1 (CBA/C57Bl6) mouse strain was used. NADH auto-fluorescence levels were measured during embryo development using adapted confocal microcopy (Olympus FV1200). A confocal Z-stacking function was used to record 15 focal planes using a 20x/0.95NA air objective of entire embryos, opening the confocal pinhole system completely. Then, images were collected and analysed using FIJI software (version: 2.0.0-rc-69/1.52n;ImageJ). Blastocyst cell number, formation rates and outgrowth rates for 4 days post blastocyst formation were compared between study groups.

Main results and the role of chance

Embryo culture experiments showed no significant differences in blastocyst formation rates between study groups (Control: 71.7%; Sham: 64.9%; Illuminated 71.7%; p > 0.05). Similarly, the total number of cells (Control: 82.9±5.6; Sham: 76.5±3.3; Illuminated: 77.1±4.2; ± Standard error of mean [SEM]) and ICM cells (Control: 10.8±1.3; Sham: 9.4±0.7; Illuminated: 11.9±0.8; ± SEM) did not differ between groups (p > 0.05). Outgrowth assays presented similar outgrowth areas during day5 to day8 post-blastocyst development between study groups (p > 0.05). Illuminated embryos presented significantly different NADH activity levels during embryo development, particularly between the 2-cell stage (987.1±36.2AU), morulae stage (1226±31.5AU) and blastocyst stage (649±42.9AU; ± SEM; p < 0.05). Embryos that did not reach the blastocyst stage presented a significantly different NADH activity profile during embryo development compared to those that did(p < 0.05). Additionally, abnormal embryos also presented significantly decreased NADH activity levels at the 2-cell stage (Normal: 987.1±36.2; abnormal: 726.9±121.7AU; p < 0.05) to the morulae stage (Normal: 1226±31.5; Abnormal:893.3±189AU; p < 0.05). Our study indicates that measuring NADH activity levels during early embryo development present no negative effects in embryo developmental rates, blastocyst formation and implantation potential. Thus, non-invasive measurements of NADH could be applied to determine embryo metabolic activity during embryo development using simple technology and imaging techniques.

Limitations, reasons for caution

The study was conducted using a mouse model focused in early embryo development and implantation potential. Thus, studies on live birth are required to fully assess safety to further validate potential wider applications. Validation in ageing models is also required to assess potential applications for embryo selection.

Wider implications of the findings

Non-invasive measurements of metabolic activity could be applied to determine embryo metabolic activity using simple and safe technology. Further applications could link the use of simple non-invasive metabolic imaging with the latest time-lapse technology and artificial intelligence applications.

Trial registration number

N/A

P-094 Fundamental understanding of sperm motion in viscoelastic media

Study question

How does viscosity influence the flagellar beating behaviour of free-swimming bull, mouse, and human sperm?

Summary answer

Sperm flagellar beating behaviour exhibits a transition from an irregular three-dimensional (3D) beating at 5 mPa·s to an organized two-dimensional (2D) waveform at 20 mPa·s.

What is known already

Sperm migrate in a complex viscoelastic environment through the female reproductive tract. The viscoelastic properties of the oviductal fluid significantly influence the progressive motility of sperm, acting as one of the key guidance mechanisms in vivo. However, the biomechanics of sperm flagellar activity in response to varying viscosity of the oviductal fluid is poorly understood. Understanding sperm flagellar behaviour in physiologically relevant environments is crucial to understanding reproduction and may help to describe unknown causes of infertility. Lack of high-speed high-resolution imaging techniques and automated image-analysis capabilities have been the main barriers to fully describe the flagellar beating behaviour.

Study design, size, duration

We used a custom-built high-speed high-resolution dark-field microscopy platform to resolve the flagellar dynamics of human, bull, and mouse sperm near surfaces in viscoelastic media ranging in viscosity from 1 to 250 mPa·s. The imaging system includes an automated image analysis algorithm to quantify sperm flagellar waveform and motility characteristics by extracting the flagellar centreline, reconstructing the waveform and calculating tangent-angle profiles. 20 sperm from 3 different bull, mice and humans were analyzed.

Participants/materials, setting, methods

Bull, mouse, and human sperm were used in this study. In each experiment, a diluted sperm sample in a buffer supplemented with methylcellulose was used and free-swimming sperm were imaged using dark-field microscopy at 200 frames per second. An automated image analysis algorithm was used to extract sperm flagellar centreline and Proper Orthogonal Decomposition (POD) was then used to study sperm flagellar waveform. Statistical analysis was performed using one-way ANOVA.

Main results and the role of chance

The reconstructed flagellar beating pattern was different for sperm swimming in low and high-viscosity media. Bull sperm exhibited a lower flagellar beating amplitude along the end piece when swimming in a high-viscosity media, a potential energy-efficient strategy to navigate a high viscosity fluid. The first two dominant POD modes (shape modes) describe more than 90% of the beating pattern for all species. Bull sperm exhibited a transition mode with irregular loops in 5 mPa·s buffer, but the flagellar shape cycle created an organised repetitive circular cycle in 1 mPa.s (3D beating) buffer and at viscosities higher than 5 mPa·s (2D beating). Human sperm also indicated a similar behaviour but with the transition happening at higher viscosities. Mouse sperm in high-viscosity media had a lower flagellar beating amplitude across the principal piece and higher beating amplitude across the end piece. The flagellar shape cycle in mouse sperm showed a periodic flagellar beating behaviour at high-viscosities (>20 mPa·s), but a shape cycle with distorted loops at lower viscosities. Our results showed in quantitative detail that increasing viscosity alters sperm flagellar beating pattern, and how sperm migration behaviour in low viscosity media can be distinct from their swimming behaviour in vivo.

Limitations, reasons for caution

A more comprehensive study of sperm motility parameters such as curvilinear velocity, average path velocity and straight line velocity with a larger sample size is required to fully characterise sperm swimming behaviour as a function of viscosity.

Wider implications of the findings

The increasing viscosity of the oviductal fluid regulates the sperm flagellar beating behaviour to switch from a 3D swimming behaviour with irregular shape cycles at lower viscosities to a 2D slithering mode with repetitive circular shape cycles at higher viscosities to achieve a more energy-efficient beating pattern for navigation.

Trial registration number

Not applicable

Feasibility of using a single MRI acquisition for fiducial marker localization and synthetic CT generation towards MRI-only prostate radiation therapy treatment planning

Purpose.To investigate the feasibility of using a single MRI acquisition for fiducial marker identification and synthetic CT (sCT) generation towards MRI-only treatment planning for prostate external beam radiation therapy (EBRT).Methods.Seven prostate cancer patients undergoing EBRT, each with three implanted gold fiducial markers, participated in this study. In addition to the planning CT scan, all patients were scanned on a 3 T MR scanner with a 3D double-echo gradient echo (GRE) sequence. Quantitative susceptibility mapping (QSM) was performed for marker localization. QSM-derived marker positions were compared to those from CT. The bulk density assignment technique for sCT generation was adopted. The magnitude GRE images were segmented into muscle, bone, fat, and air using a combination of unsupervised intensity-based classification of soft tissue and convolutional neural networks (CNN) for bone segmentation.Results.All implanted markers were visualized and accurately identified (average error: 0.7 ± 0.5 mm). QSM generated distinctive contrast for hemorrhage, calcifications, and gold fiducial markers. The estimated susceptibility/HU values on QSM/CT for gold and calcifications were 31.5 ± 2.9 ppm/1220 ± 100 HU and 14.6 ± 0.9 ppm/440 ± 100 HU, respectively. The intensity-based soft tissue classification resulted in an average Dice score of 0.97 ± 0.02; bone segmentation using CNN resulted in an average Dice score of 0.93 ± 0.03.Conclusion.This work indicates the feasibility of simultaneous fiducial marker identification and sCT generation using a single MRI acquisition. Future works includes evaluation of the proposed method in a large cohort of patients with optimized acquisition parameters as well as dosimetric evaluations.

Improving environmental protection of waterborne polyurethane coating by adding TiO2/polyaniline/HNT/CNT nanocomposite

Nanostructures of titanium dioxide, polyaniline, halloysite, and carbon nanotubes have an excellent effect to improve environmental protection and surface properties of coatings like anticorrosion and self-cleaning attributes. In this research, we studied the individual effect of adding each nanostructure within the polyurethane matrix and also all nanostructure combinations with each other on the mentioned properties. To reach this aim, the polyurethane nanocomposites were prepared; then, anticorrosion and self-cleaning tests were carried out on the samples. FTIR spectroscopy and FESEM images were used to characterize the nanocomposite additives and coating influence. According to the obtained results, the polyurethane coating modified with titanium dioxide/polyaniline/halloysite nanotube/carbon nanotube nanocomposite showed very higher corrosion potential and resistance and lower corrosion current in the comparison with other coatings. Also, the mentioned polyurethane nanocomposite coating showed good hydrophilicity and it decolorized a dye contaminant with high efficiency which makes them appropriate candidate for the protection of the substrate against environmental destructive factors.

Correlation between nitrogen fixation rate and alginate productivity of an indigenous Azotobacter vinelandii from Iran

BACKGROUND AND OBJECTIVES

Azotobacter vinelandii, a gamma-proteobacterium, is an obligate aerobic free-living gram-negative soil bacterium capable of fixing nitrogen. Oxygen transfer rate into the cell is reduced by the increase of alginate concentrations during the course of A. vinelandii cultivation. This phenomenon provides a low intracellular oxygen concentration needed for nitrogenase activity. The aim of this study was to design a simple strategy to explain the alginate production, cell growth and nitrogenase activity correlation in A. vinelandii under aerobic conditions.

MATERIAL AND METHODS

Thirty-five different soil samples were taken from the rhizosphere of agricultural crops of Iran. Enrichment and isolation strategies were employed for microbial isolation. Physiological and biochemical characteristics were determined. Molecular identification was performed using selective nifH-g1 primers. Alginate production and nitrogenase activity assay by each isolate of Azotobacter were carried out. Bacterial growth, alginate production and Nitrogenase activity were conducted by time-coursed quantitative measurements.

RESULTS

Total of 26 isolates were selected after enrichment, isolation, and screening. The isolate was identified by molecular tests as A. vinelandii. The highest alginate productions of 1.02 g/l and 0.91g/l were noted after 4 days in 8 isolates, cell biomass of which were estimated 4.88-5.26 g/l. Six of 8 isolates were able to fix atmospheric N(2) on nitrogen-free medium. Rates obtained in isolates were in the range of 12.1 to 326.4 nmol C(2)H(4) h(-1) vial(-1).

CONCLUSIONS

Nitrogen fixation and alginate production yielded significant and positive Pearson's correlation coefficient of R(2) = 0.760, p ∼ 0.02. Finally association between bacterial growth, alginate production and nitrogenase activity almost noticeable yielded significant and positive Pearson's correlation coefficient R2= 0.723, p ∼ 0.04.

Degradation of ampicillin antibiotic in aqueous solution by ZnO/polyaniline nanocomposite as photocatalyst under sunlight irradiation

PURPOSE AND METHOD

ZnO/polyaniline nanocomposite in core-shell structure was prepared by the synthesis and adsorption of polyaniline chains on the structure of ZnO nanoparticles. Fourier transform infrared and ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction patterns, field emission scanning electron microscopy, and transmission electron microscopy were used to characterize the composition and structure of the nanocomposite. The nanocomposite was used as an active photocatalyst for photodegradation and removal of ampicillin in aqueous solution.

RESULTS

UV-Vis spectroscopy studies showed that ZnO/polyaniline nanocomposite absorbs visible light irradiation as well as ultraviolet spectrum, and therefore, it can be photoactivated under visible and ultraviolet lights. The photocatalytic activity of ZnO/polyaniline nanocomposite in degradation of ampicillin molecules in aqueous solution under natural sunlight irradiation was evaluated and compared with that of ZnO nanoparticles and pristine polyaniline. The ZnO/polyaniline core-shell nanocomposite exhibited higher photocatalytic activity compared to ZnO nanoparticles and pristine polyaniline. The effect of operating conditions (pH, ZnO/polyaniline nanocomposite dosage, and ampicillin concentration) in the photocatalytic degradation of ampicillin using ZnO/polyaniline nanocomposite was investigated. The optimum conditions for maximum efficiency of ampicillin degradation under 120 min sunlight irradiation were found as 10 mg L(-1) dosage of ZnO/polyaniline nanocomposite, ampicillin concentration of 4.5 mg L(-1), and solution pH = 5. Under optimum operating conditions, degradation efficiency was reached to 41% after 120 min of exposure to the sunlight irradiation.