Red Filter Research Articles

Omics exploration of Tetraselmis chuii adaptations to diverse light regimes.

Microalgae are significantly influenced by light quality and quantity, whether in their natural habitats or under laboratory and industrial culture conditions. The present study examines the adaptive responses of the marine microalga Tetraselmis chuii to different light regimes, using a cost-effective filtering method and a multi-omics approach. Microalgal growth rates were negatively affected by all filtered light regimes. After six days of cultivation, growth rate for cultures exposed to blue and green filtered light was 67%, while for red filter was 83%, compared to control cultures. Transcriptomic analysis revealed that the usage of green filters resulted in upregulation of transcripts involved in ribosome biogenesis or coding for elongation factors, exemplified by a 2.3-fold increase of TEF3. On the other hand, a 2.7-fold downregulation was observed in photosynthesis-related petJ. Exposure to blue filtered light led to the upregulation of transcripts associated with pyruvate metabolism, while photosynthesis was negatively impacted. In contrast, application of red filter induced minor transcriptomic alterations. Regarding metabolomic analysis, sugars, amino acids, and organic acids exhibited significant changes under different light regimes. For instance, under blue filtered light sucrose accumulated over 6-fold, while aspartic acid content decreased by 4.3-fold. Lipidomics analysis showed significant accumulation of heptadecanoic and linoleic acids under green and red light filters. Together, our findings indicate that filter light can be used for targeted metabolic manipulation.

Slit in a Nest Site Influences the Nest Site Selection in Cavity Nesting Ant Colonies.

For ants, nests provide a refuge against predators and protection from environmental factors. Thus, choosing a good nest site is important for an ant colony, but nest sites are limited resources. Ants of the genus Temnothorax inhabit small cavities in, e.g., acorns, twigs and under rocks. Earlier, it was shown that the ants are able to choose a superior site. In this study, using binary choice tests, we studied the nest site selection by Temnothorax crassispinus ant colonies that typically inhabit empty acorns. For this purpose, we used artificial nest sites without and with an additional slit in the nest wall, mimicking the cracks in potential nest sites under natural conditions. We found that the ant colonies preferred artificial nest sites without these slits. However, no difference in the number of colonies inhabited nest sites with a slit vs. those without a slit was found when the slits were closed using transparent food foil, which prevented the air flow while keeping an inflow of light. What is more, additional light through the hole in the red filter covering the artificial nest sites had no influence on the nest site selection. The results of this study suggest that the air flow through a slit in the nest site wall, rather than additional light, influences the nest site selection. The absence of cracks, e.g., in acorns, could be an indication of the durability of potential nest sites. Thus, choosing a cavity without such damage could be beneficial for the ant colonies.

Assessment of stereopsis in unilateral amblyopia subjects using syntonic phototherapy

ABSTRACT Introduction Amblyopia is two Snellen line difference between both eyes. Red filter therapy is a treatment option for amblyopia based on principle of syntonic phototherapy. The purpose of this study is to assess the stereopsis in amblyopic patient using syntonic phototherapy. Methods A Qusai experimental study was conducted from August 2021 to December 2021 at Madina Teaching Hospital Faisalabad. A total 30 subjects of both gender and ages ranging between 8 to 18 years were included through a non-probability purposive sampling technique. The sample was considered of 15 anisometropic amblyopes and 15 strabismic amblyope. Data was collected using a Performa and pre assessments of stereopsis by Titmus fly chart were recorded without red filter. Red filter glasses were prescribed for 4 week, post assessment data was recorded after 4 weeks. Data was analyzed by using Paired sample T test and Independent Sample T test in SPSS 20 software. Results After syntonic phototherapy significant improvement was seen, mean stereopsis was 48.00000 (p = 0.002) in anisometropic amblyopes while mean improvement of stereopsis 1.670.93333 (p = 0.00) in strabismic amblyopes. Anisometropic amblyopic patients showed significantly better improvement in stereopsis (p = 0.00) by syntonic phototherapy as compared to strabismic amblyopes. Conclusion Significant improvement was seen in stereopsis, while improvement was more significant in anisometropic amblyopes as compared to strabismic amblyopes. Children were obsessed with the red filter glasses while their parents found syntonic therapy simple plus facile and gave good results. So, eye care professionals must be aware of this new therapy and they should keep syntonic phototherapy in mind whenever they are dealing with amblyopic patients.

Performance evaluation of coloured filters on PV panels in an outdoor environment

AbstractThis study aims to investigate the effects of colour filters and tilt angles on the electrical output characteristics of solar photovoltaic modules. The experimental set‐up allowed for the evaluation of various combinations of colour filters and tilt angles by using a realistic simulation of solar panel installations. The various light spectrum wavelengths and energy levels were taken into account, keeping in mind any potential impacts on the solar cells' conversion efficiency. The results showed that compared to other filter combinations, the use of red colour filters with a 10% blockage rate and an optimal tilt angle led to a noticeable increase in electrical output. This result emphasises the value of colour filtering and tilt angle selection in raising solar photovoltaic systems' overall performance. When compared to the other filters, the red, orange, and yellow filters stand out due to their outstanding efficiency of around 84.98%, 84.08%, and 83.69%. However, the teal, green, and blue filters exhibit relatively low levels of efficiency of about 69.62%, 67.06%, and 58.52%, respectively. The distinct reaction shown by purple and pink filters, when subjected to tilt angle of 30 degrees, offers a potentially productive direction of enhancing the efficiency of PV panel.

Single-Frame Lagrangian Tracking Of 3-D Acoustic Streaming Flows Using Digital Defocusing Micro Particle Streak Velocimetry

In this study, a single-frame particle streak velocimetry technique is applied to the classic DDPIV(Digital Defocusing Particle Image Velocimetry) concept to achieve a single-frame 3-D Lagrangian tracking of particles in microscopic flows. The shortcoming of images suffering low signal to noise ratio due to pinholes can be avoided. With the streak resolving algorithm, it allows extended exposure time when streak images are taken, and the single-frame approach also eliminates the need for high-cost and complicated synchronization hardware for double-pulse frame-straddling light sources. For each long-exposure, color-coded images received from each pinhole equipped with red, green or blue color filters, the streak-resolving algorithm is applied first to find each streak on the separate color channel, followed by an one-time triplet-matching process to group the red, green and blue streak projections. From the streak triplets, 3-D reconstruction can be done on all the resolved points on the streak, and trajectory fitting can then be applied to resolve the tracer particle trajectories in the field of view with temporal history. This procedure was applied for visualizing a microscale 3-D acoustic streaming flow pattern induced by a longitudinal spine-shaped fin oscillating at 12kHz. The height of the channel is 1mm with the spine of 0.3mm height and a 30 。 tip angle. Resolved flow fields show that the particle streak images can be resolved with the same level of accuracy to the particle tracking method, while the throughput of velocity vectors can be significantly higher due to multiple velocity vectors can be resolved from each streak triplet. The methodology has the potential to be applied to various applications that can capture long-exposure images and possible to resolve higher-order information such as acceleration and forces applied on the particles or the flow.

Vision-related quality of life, photoaversion, and optical rehabilitation in achromatopsia.

We report on photoaversion and patient-reported quality of life in Danish patients with achromatopsia and evaluate the best optical rehabilitation. Our results contribute to the evaluation of outcome measures in therapy trials and aid in providing the best optical rehabilitation for patients with this and clinically similar conditions. This study aimed to investigate the vision-related quality of life, the impact of photoaversion on daily living, and the best optical rehabilitation in a cohort of achromatopsia patients, including testing the hypothesis that red light-attenuating filters are generally preferred. Patients with genetically verified achromatopsia were recruited. Investigations included the 25-item Visual Function Questionnaire and supplementary questions regarding photoaversion and visual aids. Patients were evaluated by a low vision optometrist and given the choice between different light-attenuating filters. First, two specially designed red and gray filters both transmitting 6% light, and then a pre-defined broader selection of filters. Best-corrected visual acuity and contrast sensitivity were measured without filters and with the two trial filters. Twenty-seven patients participated. Median 25-item Visual Function Questionnaire composite score was 73, with the lowest median score in the subscale near vision (58) and the highest in ocular pain (100). The majority of patients (88%) reported that light caused them discomfort, and 92% used aid(s) to reduce light. Ninety-six percent (26 of 27) preferred the gray filter to the red indoors; 74% (20 of 27) preferred the gray filter. Contrast sensitivity was significantly better with the gray filter compared with no filter (p=0.003) and the red filter (p=0.002). Our cohort has a relatively high vision-related quality of life compared with other inherited retinal diseases, but photoaversion has a large impact on visual function. Despite what could be expected from a theoretical point of view, red filters are not generally preferred.

Phobos photometric properties from Mars Express HRSC observations

Aims. This study aims to analyze Phobos’ photometric properties using Mars Express mission observations to support the Martian Moons exploration mission (MMX) devoted to the investigation of the Martian system and to the return of Phobos samples. Methods. We analyzed resolved images of Phobos acquired between 2004 and 2022 by the High Resolution Stereo Camera (HRSC) on board the Mars Express spacecraft at a resolution ranging from ~30 m px−1 to 330 m px−1. We used data acquired with the blue, green, red, and IR filters of HRSC and the panchromatic data of the Super Resolution Channel (SRC). The SRC data are unique because they cover small phase angles (0.2–10°), permitting the investigation of the Phobos opposition effect. We simulated illumination and geometric conditions for the different observations using the Marx Express and the camera spice kernels provided by the HRSC team. We performed photometric analysis using the Hapke model for both integrated and disk-resolved data. Results. The Phobos phase function is characterized by a strong opposition effect due to shadow hiding, with an amplitude and a half-width of the opposition surge of 2.28±0.03 and 0.0573±0.0001, respectively. Overall, the surface of Phobos is dark, with a geometric albedo of 6.8% in the green filter and backscattering. Its single-scattering albedo (SSA) value (7.2% in the green filter) is much higher than what has been found for primitive asteroids and cometary nuclei and is close to the values reported in the literature for Ceres. We also found a surface porosity of 87%, indicating the presence of a thick dust mantle or of fractal aggregates on the top surface. The SSA maps revealed high reflectance variability, with the blue unit area in the northeast Stickney rim being up to 65% brighter than average, while the Stickney floor is among the darkest regions, with reflectance 10 to 20% lower than average. Photometric modeling of the regions of interest selected in the red and blue units indicates that red unit terrains have a stronger opposition effect and a smaller SSA value than the blue ones, but they have similar porosity and backscattering properties. Conclusions. The HRSC data provide a unique investigation of the Phobos phase function and opposition surge, which is valuable information for the MMX observational planning. The Phobos opposition surge, surface porosity, phase integral, and spectral slope are very similar to the values observed for the comet 67P and for Jupiter family comets in general. Based on these similarities, we formulate a hypothesis that the Mars satellites might be the results of a binary or bilobated comet captured by Mars.

Design and Synthesis of ESIPT-Based Imidazole Derivatives for Cell Imaging.

Excited-state intramolecular proton transfer (ESIPT)-based fluorescent molecules offer several exciting applications and are utilized most frequently as a cell imaging agent. Because of this, four distinct imidazole derivatives with ESIPT emission have been synthesized, and their fluorescence characteristics have been assessed in a variety of settings. Measurements using fluorescence spectroscopy have shown a promising candidate for cell staining, and potential candidate was specifically investigated for cell imaging uses in HT-29, MDA-MB-231, and HaCaT. Cytotoxicity of candidate molecule (1d) was analyzed using HT-29 and HaCaT cell lines, and at a dosage of 160 μM, HT-29 and HaCaT cell lines showed no signs of important cell toxicity. When spectroscopically measured, compound 1d showed no fluorescence ability in phosphate-buffered saline (PBS) solution. However, after 8 h of incubation in several cell lines, excellent fluorescence characteristics were seen in the green and red filters.

Dehydrodieugenol isolated from Ocotea cymbarum induces cell death in human breast cancer cell lines by dysregulation of intracellular copper concentration

In this work, two neolignans – dehydrodieugenol (1) and dehydrodieugenol B (2) – were isolated from leaves of Ocotea cymbarum (H. B. K.) Ness. (Lauraceae). When tested against two human breast cancer cell lines (MCF7 and MDA-MB-231), compound 1 was inactive (IC50 > 500 μM) whereas compound 2 displayed IC50 values of 169 and 174 μM, respectively. To evaluate, for the first time in the literature, the synergic cytotoxic effects of compounds 1 and 2 with ion Cu2+, both cell lines were incubated with equimolar solutions of these neolignans and Cu(ClO4)2·6H2O. Obtained results revealed no differences in cytotoxicity upon the co-administration of compound 2 and Cu2+. However, the combination of compound 1 and Cu2+ increases the cytotoxicity against MCF7 and MDA-MB-231 cells, with IC50 values of 165 and 204 μM, respectively. The activity of compound 1 and Cu2+ in MCF7 spheroids regarding the causes/effects considering the tumoral microenvironment were accessed using fluorescence staining and imaging by fluorescence microscopy. This analysis enabled the observation of a higher red filter fluorescence intensity in the quiescence zone and the necrotic core, indicating a greater presence of dead cells, suggesting that the combination permeates the spheroid. Finally, using ICP-MS analysis, the intracellular copper disbalance caused by mixing compound 1 and Cu2+ was determined quantitatively. The findings showcased a 50-fold surge in the concentration of Cu2+ compared with untreated cells (p > 0.0001) – 18.7 ng of Cu2+/mg of proteins and 0.37 ng of Cu2+/mg of protein, respectively. Conversely, the concentration of Cu2+ in cells treated with compound 1 was similar to values of the negative control group (0.29 ng of Cu2+/mg of protein). This alteration allowed us to infer that compound 1 combined with Cu2+ induces cell death through copper homeostasis dysregulation.

Evaluation of the Efficacy of Enchroma Filters for Correcting Color Vision Impairment

Objective: This study examined the effectiveness of Enchroma Cx-14 filters on individuals with Red-Green color vision deficiency (CVD). Methods: ColorDx and the Farnsworth-Munsell (FM) 100-Hue test were used to assess subjective reactions to Enchroma. The ColorDx and FM, 100 Hue test error scores were computed and contrasted using Placebo (untinted glasses) and Enchroma CX-14, red, and green filters. Results: The findings demonstrated that while enchroma filters improved the mistake score in only two patients, they had no discernible impact on any CVD subject's performance. In one protan participant and all deutan individuals, colour discrimination was greatly enhanced by the red filter. Green filters and Enchroma did not raise mean error scores. Conclusion: Enchroma filters had limited effectiveness in improving color perception for individuals with Red-Green CVD.

Red filter meibography by smartphones in patients with meibomian gland dysfunction: a validity and reliability study

ObjectiveThe objective of this study is to determine the validity and reliability of the red filter meibography by smartphone compared with infrared in assessing meibomian gland drop-out.Methods and analysisAn analytical...

DRI Triton SS-OCT applied to detect choroidal nodules in paediatric patients affected by NF1

PurposeTo examine whether image processing of non-mydriatic DRI Triton SS-OCT (Topcon Corporation, Tokyo, Japan) using the red free filter could assess the presence of choroidal nodules and thus include their detection as a diagnostic criterion in neurofibromatosis type 1 (NF1). Material and methodsWe included 417 eyes from 210 patients, 377 - from 190 patients diagnosed with NF1 according to the criteria established by the National Institutes of Health Consensus Development Conference (NIH) and 40 from 20 healthy patients as a control group. The mean age was 9.4 years (range 2 years–18 years). All patients had their visual acuity measured by a test according to age, were examined for the presence of lisch nodules and an Optical Coherence Tomography (OCT) of the macular area was performed. All the OCT images were analysed to check if visible nodules could be identified. ResultsAges 14 (95% CI=(9.7,18.3)) and 12 years (95% CI=(9.1,14)) are the cut-off points that best separate those with choroidal nodules with Triton OCT and lisch with slit lamp, respectively, from those without. lisch nodules were detected in 50% of cases of NF1 patients. The presence of choroidal nodules did not present a statistically significant correlation with the occurrence of optic pathway glioma (p = 0.96) nor with the patient's visual worsening (p = 0.072). A statistically significant correlation was observed between the presence of choroidal nodules and the presence of lisch nodules (p < 0.05). ConclusionThe Topcon Triton OCT red free tool would not be a good tool to detect choroidal nodules in patients with NF1 because of its low sensitivity. If the presence of choroidal nodules were to be included in the diagnostic criteria for NF1, it would be convenient to use a device with red and infrared radiations.

Label-free 3D tracking of biological micro-objects using RGB pinholes

Defocusing digital particle image velocimetry is a method developed within the field of fluidics to measure the velocities of particles within a volume through image analysis. For three-dimensional (3D) tracking, approaches utilizing defocusing techniques have been proposed to enable depthwise positional measurements. Recently, there have been suggestions to simplify this approach by employing a triple pinhole mask and to further enhance it with color filters that allow distinguish particles, even under dense conditions. This paper presents an attempt to apply the defocusing method using a triple pinhole mask with red, green, and blue (RGB) color-coding filters, demonstrating the successful label-free 3D tracking of biological micro-objects at multiple positions within a volume. The application of this method in fluidics and its potential for biological analysis are highlighted through successful examples of 3D tracking involving micro-particles influenced by motor proteins, dividing cells, and swimming microorganisms.

Diversity, Encounter Rate and Detection of Non-Volant Nocturnal Mammals on Two Malaysian Islands.

Nocturnal mammals constitute a crucial component of tropical faunal diversity, but not much is known about the effects of anthropogenic disturbance on the habitat use and detectability of these species. We investigated which habitat and environmental variables impact the detectability of non-volant nocturnal arboreal mammals across varying habitat types at two tropical islands with different levels of anthropogenic development in Malaysia. We conducted night transect line and point count surveys following pre-existing paths in Penang Island and Langkawi Island between 2019 and 2020. We used a head torch with red filter and a thermal imaging device (FLIR) to enhance animal detection success. We calculated the encounter rates (individual km-1) for each species as a proxy for abundance. Overall, we detected 17 species, but did not find higher species diversity in intact forested environments compared to disturbed areas. Encounter rates of the most observed species were influenced by 'time after sunset' on the highly developed island of Penang, whereas on the rural island of Langkawi, detection was higher in sites with better canopy connectivity. Different species of non-volant nocturnal arboreal mammals use their respective habitats differently and thus, are differently impacted by varying levels of anthropogenic activities. Our results provided baseline data on the diversity, encounter rate, and detectability of these highly elusive species, which can also help to further improve methodologies for the detection of nocturnal wildlife.

Visibility of inflicted bruises by alternate light: Results of a randomized controlled trial.

Difficulty visualizing bruises resulting from interpersonal violence, especially in individuals with dark skin, contributes to disparities in access to justice. The purpose of this analysis was to compare bruise visibility of detected injuries using white light versus alternate light sources (ALS). Visibility was assessed using the 5-point Bruise Visibility Scale (BVS) for white light and the ALS Visibility Scale (AVS) for ALS. Bruises were induced using controlled application of a paintball to the upper arm on 157 healthy adults across six skin color categories. Using a crossover design, the light source used first to assess the bruise (white light or ALS) was randomized. Each bruise was examined up to 21 times over 4 weeks using white light and 10 combinations of wavelengths (350 nanometer [nm] - 535 nm) and colored filters (yellow, orange, and red). Multilevel modeling was used to analyze the repeated measures data with a total 20,103 bruise assessments. Results revealed 415 nm with yellow filter resulted in an almost 0.5-point increase in BVS/AVS score across all skin colors (Estimate = 0.46; 95% CI: 0.43, 0.49; p < 0.001), a clinically significant improvement in ability to visualize bruises. Conversely, 515 nm (Estimate = -0.80; 95% CI: -0.84, -0.76; p < 0.001) and 535 nm (Estimate = -0.64, 95% CI: -0.67, -0.60; p < 0.001) with red filter resulted in more than 0.5-point decrease in BVS/AVS score. The use of ALS is supported by the data and results in improved bruise visibility during medical forensic examinations.

Multi-Colour Photometric Observations of Transiting Exoplanets to Verify Binary Star Systems

Within this paper, we report the observation of transiting exoplanets, K2-29b, TrES-3b, WASP-36b, and HAT-P54b, with a focused comparison of the well defined binary system K2-29b to the proposed binary WASP-36b. Performing multicolour photometry, debayering images to three distinct colour channels, a comparison of the detrended light curves of each target is used to define parameters to identify the presence of any discrepancy between the observation, defined system models or past observations. The exoplanet system K2-29b, observed in separate red and blue filters, produced minimal deviation from expected RP /R∗ values with RP /R∗ = 0.1404 +0.0040/-0.0042 and RP /R∗ = 0.1468 +0.0082/-0.0088 respectively. In contrast to this, we observe a significant deviation in the blue debayered value of RP /R∗ for WASP-36b, with the expected radius ratio defined to be ±RP /R∗ = 0.1368±0.0006. Initial airmass detrending model fitting for the blue debayered channel produced a value of RP /R∗ = 0.1162+0.0098/ -0.0102, with RP /R∗ Drift = 3.01σ, this later being reduced through a quadratic detrending scheme to RP /R∗ Drift = 2.11σ. Despite this model being an improved representation, this measure of RP /R∗ drift is significantly beyond the tolerance of ±1σ and as such motivates further study as this effect has been denoted in concordant research to suggest presence of a secondary star in this system.

Inhibiting myopia development by the digital chromatic filters

We had previously found that simulated chromatic defocus, imposed by spatially filtering the RGB channels of the computer screen, induces significant changes in choroidal thickness already after 45 min (Swiatczak and Schaeffel, 2022). In emmetropes, the “red in focus” filter, which blurs the image in the blue channel and simulates myopic chromatic defocus, induced thickening of the choroid and eye shortening, while the “blue in focus” filter, which blurs the image in the red channel and simulates hyperopic chromatic defocus, induced thinning of the choroid and eye elongation. Strikingly, eyes that were already myopic were not responsive to these filters, suggesting that (1) they may no longer detect longitudinal chromatic aberration (LCA), (2) the imposed signal was too weak to induce significant changes in choroidal thickness, or (3) the signal was detected by the retina, but it was not transmitted to the choroidal tissue. To gain a better understanding of the underlying mechanisms and their roles in emmetropization, we measured in emmetropic and myopic subjects (1) the long‐term effect of repetitive exposure to the “red in focus” filter over 12 days of treatment, followed by 2 days of recovery, (2) the accommodation responses to visual targets with simulated myopic and hyperopic LCA, and (3) visual acuity and contrast sensitivity in red and blue light.Our results showed that as previously found for choroidal changes, simulated hyperopic or myopic LCA also affected accommodation. The “blue in focus” filter induced more accommodation than the “red in focus” filter (difference in emmetropes: 0.13D, p &lt; 0.05). Strikingly, accommodation in myopic eyes was not responsive to simulated LCA. Moreover, visual acuity was severely reduced when subjects were looking through a short‐pass blue filter (cut‐off at 490 nm) compared to visual acuity in red light (long‐pass red filter, cut‐off at 610 nm) which was observed in both emmetropic and myopic subjects. Furthermore, emmetropes displayed higher contrast sensitivity in red than in blue light, but this difference was not found in myopes.Our findings confirm that there is a difference in retinal processing between emmetropes and myopes which includes lower sensitivity to LCA in myopes. Furthermore, we showed that these differences show up in both, changes in choroidal thickness as well as accommodation.

Identifying the wavelength that generates the most voltage and current in a solar panel

Solar power is a potential solution for addressing climate change. There is limited research on how different wavelengths of light affect solar cells, and researchers have come to conflicting conclusions. Determining the most efficient wavelength of light would allow us to improve solar panel efficiency and make panels more cost-effective and desirable for adoption by the general public. A color filter is relatively inexpensive, and it can enhance the efficiency of a solar panel. Ultimately, it can help save the environment by (1) making solar panels as efficient as possible, (2) making society less dependent on fossil fuels, and (3) speeding up adoption of solar power. Therefore, this study focused on determining which wavelength of light generates the most voltage and current from a solar panel as measured by a Raspberry Pi coded to function as a multimeter. We measured the voltage and current that the solar panel generated in the absence or presence of different filters, which produce different wavelengths of light. Learning which, if any, color filter generates the most voltage and current can improve and promote solar power use. We determined that the yellow filter produced the greatest voltage and current compared to using a solar panel without a filter or a red, orange, green, blue, and purple color filter. Our results suggest that yellow color filters can enhance the voltage and current capabilities of solar panels. The findings offer a relatively low-cost solution to increasing the efficiency of solar panels.

Clinical Benefits of Decreased Photo-Oxidative Stress on Human Embryo Development

Objective: Early embryonic development is characterized by rapid cell division and gene activation, making the embryo extremely sensitive to environmental influences. Light exposure can affect embryonic development through a direct toxic effect on the embryo via the generation of reactive oxygen species. In a previous study, we demonstrated the positive effect of improved light-protected embryo culture conditions implemented in our laboratory. This study aimed to investigate the changes in human embryo development under light protection during the conventional in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). Materials and Methods: We tested the potential beneficial effect of light filters to reduce the risk of toxic effects of light. IVF outcomes were compared between two experimental conditions, light protection with red light filters versus no light protection as a control. Results: Blastocyst development rate in IVF was significantly higher in the light-protected group than in the group treated under conventional conditions (46.6 vs. 26.7%). In the case of ICSI, we obtained a similar result (44.5 vs. 31.6%). The rate of cryopreservation with at least one embryo was higher in the light-protected phase (32.8%) than in the conventionally manipulated phase (26.8%). The abortion rate was also significantly lower during the light-protected period in IVF, resulting in a higher live birth rate. Conclusions: The implementation of light protection to reduce the embryotoxic wavelengths of light in IVF centers may improve the blastocyst development rate and embryo quality while maintaining embryo safety.

Isolation of Mouse Germ Cells by FACS Using Hoechst 33342 and SYTO16 Double Staining.

In the adult mouse testis, germ cells of various developmental cell states co-exist. FACS isolation of cells stained with the DNA dye Hoechst 33342 has been used for many years to sub-divide these cells based on their DNA content. This approach provides an efficient way to obtain broad categories of male germ cells: pre-meiotic spermatogonia, meiotic spermatocytes and post-meiotic spermatids. The addition of a red filter for Hoechst staining enables further sub-division of spermatocytes depending on sub-stages of meiotic prophase. However, separation of different stage spermatids using Hoechst staining alone is not possible. We recently reported a methodology, combining Hoechst staining with a second DNA dye (SYTO16) that enables the further separation of these cells into three sub-populations: round, early elongating, and late elongating spermatids (Gill et al., Cytometry A 101:529-536, 2022). This method makes it possible to obtain rapidly and simply pure fractions of male germ cells from multiple developental stages from the same animal.