Embryo Size Research Articles

Scale invariance in early embryonic development

The expression of a few key genes determines the body plan of the fruit fly. We show that the spatial expression patterns for several of these genes scale precisely with embryo size. Discrete positional markers such as the peaks in striped patterns or the boundaries of expression domains have positions along the embryo’s major axis proportional to embryo length, accurate to within 1%. Further, the information (in bits) that graded patterns of expression provide about a cell’s position can be decomposed into information about fractional or scaled position and information about absolute position or embryo length; all information available is about scaled position, with < 2% error. These findings imply that the underlying genetic network’s behavior exhibits scale invariance in a more precise mathematical sense. We argue that models that can explain this scale invariance also have a “zero mode” in the dynamics of gene expression, and this connects to observations on the spatial correlation of fluctuations in expression levels.

CT image segmentation of foxtail millet seeds based on semantic segmentation model VGG16-UNet

Foxtail millet is an important minor cereal crop rich in nutrients. Due to the small size of its seeds, there is little information on the diversity of its seed structure among germplasms, limiting the identification of genes controlling seed development and germination. This paper utilized X-ray computed tomography (CT) scanning technology and deep learning models to reveal the microstructure of foxtail millet seeds, gaining insights into their internal features, distribution, and composition. A total of 100 foxtail millet varieties were scanned with X-ray computed tomography to obtain 3D reconstruction images and slices. Pre-processing steps were adopted to improve image segmentation accuracy, including noise reduction, rotation, contrast enhancement, and brightness enhancement. The experiment revealed that traditional OpenCV image processing methods failed to achieve precise segmentation, whereas deep learning models exhibited outstanding performance in segmenting seed CT slice images. We compared UNet, PSPNet, and DeepLabV3 models, selected different backbones and optimizers based on the dataset, and continuously adjusted learning rates and maximum training epochs to train the models. Results demonstrated that VGG16-UNet achieved an accuracy of 99.19% on the foxtail millet seed CT slice image dataset, outperforming PSPNet and DeepLabV3 models. Compared to ResNet-UNet, VGG16-UNet shows an improvement of approximately 3.18% in accuracy, demonstrating superior performance in accurately segmenting the inner glume, outer glume, embryo, and endosperm under various adhesion conditions. Accurate segmentation of foxtail millet CT images enables analysis of embryo size, endosperm size, and glume thickness, which impact germination, growth, and nutrition. This study fills a gap in small grain structure research, offering insights to optimize agriculture and molecular breeding for improved yield and quality.

Development of a Feasible and Efficient In Vitro Rescue Protocol for Immature Prunus spp. Embryos

The major factors affecting the in vitro immature embryo rescue efficiencies from Prunus persica or P. armeniaca accessions have been identified, along with improving the feasibility. Variations in the woody plant medium (WPM) were used depending on the embryo size. Embryos less than 5 mm long were cultured in WPM supplemented with 1 μM BAP and 1 μM GA3, while embryos bigger than 5 mm long were cultured in hormone-free medium, with or without vermiculite. The environmental in vitro culture conditions consisted of three phases: a (I) stratification at 4 °C during a 3- to 5-month-long period in the dark, followed by (II) growth of germinated embryos at 14 °C for a 4-week-long period, with 12 h light a day, which favors plantlet development, and finally, (III) growth at 24 °C, with 16 h light a day, until the plantlets were acclimatized in the greenhouse. The germination of smaller embryos, at the end of phase I, ranged from 82.2% to 22.1% for apricots and flat peaches, respectively, whereas for bigger embryos, the germination varied from 97.3% to 53.2% for the same species. The embryo germination for peaches and nectarines ranged from 40.1% to 30.3% for smaller embryos, and from 91.9% to 63.0% for bigger embryos. Endo- and epiphytic contamination, affecting from 7.4% to 52.9% of cultured embryos, depending on the fruit type and conservation conditions, and the capacity to acclimate to soil conditions, ranging from 50.4% to 93.2%, were the two most important factors influencing the protocol’s efficiency and feasibility. Considering the overall efficiencies, expressed as hardened plants transferred to field plots over clean uncontaminated embryo, the values ranged from 55.8% for nectarines, 54.0% for peaches, 45.6% for apricots, and 23.3% for flat fruits. The addition of vermiculite to the culture medium significantly improved the plantlet development, avoiding subculture to fresh medium when an extension of phase III was required before acclimatization. Compared to laboratory glassware, the use of food glass containers with air-permeable sealing film, along with vermiculite-containing medium, significantly reduced the costs when handling the large number of embryos required for breeding programs.

Stimulation of inactivated Metschnikowia bicuspidata promotes the growth, and immunity of Eriocheir sinensis larvae

The Chinese mitten crab (Eriocheir sinensis) is an economically essential crustacean specie in China. The outbreak of disease caused by Metschnikowia bicuspidata has resulted in high mortality and huge economic loss in the E. sinensis aquaculture industry. Immune priming can protect invertebrates against pathogens in the second exposure, which has been reported in adult E. sinensis and provides a novel approach for disease control. This study evaluated the effects of treatment with formalin-killed M. bicuspidata on the growth, development, and immunity of E. sinensis embryos and larvae. Stimulation of E. sinensis embryos with inactivated M. bicuspidata (Mb group) did not significantly affect the mass and size of embryos. While the carapace width, abdominal length, and tail length of larvae in the Mb group were significantly longer than those of control group in most stages. At 120 h and 144 h after embryo hatching, the metamorphosis rate of larvae in the Mb group was 24.59-fold (p < 0.05) and 16.07-fold (p < 0.001) higher than that in the control group. Moreover, after the larvae suffered alive M. bicuspidata challenge, the mortality in the Mb group significantly decreased (0.48-fold, p < 0.05) compared with that in the control group, and the mRNA expression levels of genes related to immunity (MAPK, Toll2, and STAT), growth (ATGL, Chi, Chymotrypsin, and mTOR), and development (Ubx) were significantly increased in the Mb group. These results suggested that stimulation of E. sinensis embryos with inactivated M. bicuspidata significantly promoted the growth and development of larvae and endowed them with stronger resistant capacity to M. bicuspidate. This finding may provide a novel and safe approach for preventing disease and improving larvae quality in E. sinensis aquaculture.

Quantification of elastic modulus variations during zebrafish embryo development using a 3D-printed microfluidic platform

Reliable indicators to assess embryo quality are critical for the in vitro fertilization. Increasing evidence suggests that elasticity is emerging as a potential marker to evaluate the early development of embryos. This paper introduces a 3D-printed microfluidic device to measure the elastic modulus of zebrafish embryos deformed in a circular constriction channel. Firstly, numerical simulation was performed to analyze the impact of inlet pressure, embryo size and constriction channel diameter on the maximum protrusion length of the embryo. Subsequently, the zebrafish embryos were deformed using the device to record the protrusion length which was automatically measured using U-net, before the power-law rheological model was employed to calculate the elastic modulus. Experiments showed the power-law exponent and embryo elasticity were stable as the inlet pressure was not less than 250 mbar. Embryo culturing after squeezes revealed that embryos could maintain normal development even after multiple squeezes at 150 mbar while higher pressure may be fatal. Afterward, the deformation of the yolk was found to increase elasticity by 60.4% compared to cases where only the chorion envelope was deformed. Finally, the elasticity variation of zebrafish embryos was measured for 17hours. It revealed that the elasticity initially increased from hour 1 to hour 7-10 and then returned to approximately the original value during culture from the cleavage to the segmentation stages. The system with the ability of precise and long-term assessment of embryo elasticity may find valuable application potentials in the mechanical evaluation and sorting of embryos.

Dissecting the mystery of embryonic scaling: The Scalers Hypothesis and its confirmation in sea urchin embryos

Embryonic scaling, the ability of embryos to regulate their spatial structure in proportion to size, remains a fascinating yet poorly studied problem in developmental biology. First described in sea urchin embryos by Hans Driesch, this phenomenon is now recognized as a striking example of how living organisms use non-equilibrium self-organization, based on reaction-diffusion (RD) systems, to generate pattern-determining morphogen concentration gradients that scale with size. Although specific molecular mechanisms for scaling such gradients have been described in some cases, a general approach for the targeted identification of such mechanisms had not been developed until recently. In search of a solution, we hypothesized the obligatory participation in scaling mechanisms of special genes, which we named “scalers.” We supposed that these genes share two critical features: their expression is sensitive to embryo size, and their protein products determine the scale of morphogen concentration gradients. As proof of principle, we recently identified scalers by detecting differentially expressed genes in wild-type and half-size Xenopus laevis gastrula embryos. Furthermore, we described a mechanism by which one of the identified scalers, the gene encoding Metalloproteinase 3 (Mmp3), regulates the scaling of gradients of the morphogenic protein Bmp and its antagonists, Chordin and Noggin1/2. In the present work, we have made an important theoretical generalization of the Scalers Hypothesis by proving a statement regarding the obligatory presence of scalers in closed RD systems generating morphogen concentration gradients. Furthermore, through a systematic analysis of all known types of embryonic scaling models based on RD systems, we demonstrate that scalers are present in all known types of such models, either explicitly or implicitly. Finally, to test the universality of the Scalers Hypothesis, we applied our method to identify scalers that adjust Bmp/Chordin gradients to the size of the sea urchin embryo, Strongylocentrotus droebachiensis. Our results show that at least two members of the gene cluster encoding astacin metalloproteinases of the Span family, namely bp10 and Span, exhibit properties characteristic of scalers. Namely, their expression levels increase significantly in half-size embryos, and their protein products specifically degrade Chordin. Additionally, we found that the loss of function of bp10 and span leads to a narrowing of the dorsal domain of the Bmp signaling nuclear effector, pSmad1/5. These findings not only validate the Scalers Hypothesis but also uncover a novel mechanism by which Span proteinases fine-tune Chordin and Bmp morphogen concentration gradients in sea urchins. Thus, the Scalers Hypothesis and the approach to targeted search for such genes developed on its basis open up promising avenues for future research into scaling mechanisms in various biological systems.

Oenothera biennis improves pregnancy outcomes by suppressing inflammation and fibrosis in an intra-uterine adhesion rat model

Intrauterine adhesion (IUA), also referred to as Asherman’s syndrome, is characterized by fibrosis, inflammation, and can cause amenorrhea and infertility due to abnormal endometrial healing. Histological and Molecular methods were used to evaluate the efficacy of EPO, which is traditionally known for its anti-inflammatory and fibrinolytic properties, in preventing the formation of IUA. Oral administration of EPO reduced the formation of adhesion bands and promoted endometrial regeneration. EPO administration decreased extracellular matrix accumulation, evidenced by the down-regulation of tissue COL1A1 and COL3A1 expression. The anti-inflammatory effect of EPO was confirmed by a reduction in oxidants and down-regulation of pro-inflammatory cytokines including TNF-α, IL-6, IFN-γ, and IL-1β. Furthermore, EPO improved embryonic development parameters, including size and weight of embryo, as well as increased embryo count and live embryo percentage in the rat IUA model. EPO also positively enhanced implantation markers, particularly enlargement and mass gain in the placenta of the treated group, consequently improving pregnancy outcomes such as the number of babies, percent of live babies, baby weight and gestation time. Histopathological investigation provides evidence that oral administration of EPO showed no toxicity on the main three organs including liver, kidney and heart. These results showed that EPO can be considered as a safe and natural product with potent anti-inflammatory and fibrinolytic properties without any observed side effects for the treatment of IUA.

Natural variation of CT2 affects the embryo/kernel weight ratio in maize

Embryo size is a critical trait determining not only grain yield but also the nutrition of the maize kernel. Up to present, only a few genes have been characterized affecting the maize embryo/kernel ratio. Here, we identify 63 genes significantly associated with maize embryo/kernel weight ratio using a genome-wide association study (GWAS). The peak GWAS signal shows that the natural variation in Zea mays COMPACT PLANT2 (CT2), encoding the heterotrimeric G protein α subunit, is significantly associated with the Embryo/Kernel Weight Ratio (EKWR), Further analyses show that a missense mutation of CT2 decreases its enzyme activity and associates with EKWR. The function of CT2 on affecting embryo/kernel weight ratio is further validated by characterization of two ct2 mutants, for which EKWR is significantly decreased. Subsequently, the key downstream genes of CT2 are identified by combining the differential expression analysis (DEG) of the ct2 mutant and quantitative trait transcript analysis in the GWAS population. In addition, the allele frequency spectrum shows that CT2 was under selective pressure during maize domestication. This study provides important genetic insights into the natural variation of maize embryo/kernel weight ratio, which could be applied in future maize breeding programs to improve grain yield and nutritional content.

O-203 Comparing viable and non-viable IVF early pregnancy measurements: does knowledge of gestational age using date of ET potentially change miscarriage diagnosis guidelines in IVF patients

Abstract Study question In IVF pregnancies with known embryo transfer (ET) dates, can gestational age as well as ultrasound measurements be used to diagnose miscarriage? Summary answer Early pregnancy measurements vary at fixed gestational ages based on ET. However, there is a specific time cut-off where an empty gestational sac indicates miscarriage. What is known already Current guidelines state that when ultrasound findings show a pregnancy of unknown viability, a repeat scan must be performed either 7 or 14 days later (depending on the presence of an embryo or gestation sac size) to confirm viability, irrespective of the LMP based gestational age. This definition only considers ultrasound measurements, and even when the pregnancy dates thought to be certain and based on day of ET date, there are no exceptions to this guidance. Study design, size, duration This was a retrospective cohort study within a London tertiary unit, Wolfson Clinic, Hammersmith Hospital, Imperial College Healthcare NHS Trust over a 36-month time period. We collated data from both fresh and frozen cycle IVF pregnancies over four years: Jan 1st 2019 to December 31st 2021. Participants/materials, setting, methods In this unit, patients undergoing fresh or frozen IVF cycles, have an embryo transfer at Day3-6 of development. We included any patient with a confirmed intrauterine pregnancy at first scan (5-8 weeks gestation) for analysis of pregnancy outcomes. The data collected included date of embryo transfer (ET), embryo age at transfer, and early pregnancy measurements using ultrasound. The endpoint was viability at the 11-14 week dating scan. Main results and the role of chance 1161 IVF embryo transfers were included in the study, 677 (58.3%) frozen and 484 (41.7%) fresh cycles. 892 (76.8%) remained viable at 11-14 weeks and 269 (23.2%) were non-viable. Pregnancies resulting in viable pregnancies had a range of CRL (≤16mm) and empty mean gestation sac diameter (MSD) (≤11mm) measurements at each expected age by ET date (≤8 weeks gestation). At 49 days CRL varied from 1mm to 17mm, and at 42 days empty MSD measurements varied from 7 to 18mm. This shows that a range in embryo and gestation sac sizes will be seen in subsequently shown to be viable pregnancies despite the apparent exact gestation being known based on ET. This may relate to both differing embryo growth rates and timing of implantation. A Kolmogorov-Smirnov test was applied to compare the viable and miscarriage cohort CRL measurements in relation to expected age by ET. The result: 0.610, p-value=1.33 x10-15, demonstrated a significant difference in embryo size between viable and non-viable pregnancies with known ET dates. All pregnancies where the scan showed an empty gestational sac (n = 157) at 47 days gestation by ET date, had a 100% positive predictive value with a 100% specificity (CI:90.1-100.0) for miscarriage. Limitations, reasons for caution The sample was powered to 0.9, significance level 0.05. Analysis demonstrated 100% positive predictive value with 100% specificity (CI:90.1-100.0), to confirm miscarriage with an empty gestation sac ≥47days age by ET date. A larger cohort size from different centres is needed to reduce the confidence interval and confirm the findings. Wider implications of the findings There is significant variation in CRL and MSD size between viable pregnancies of the same gestational age by ET. However, we found &amp;gt;47 days gestation an empty gestation sac resulted in miscarriage. If confirmed in larger studies this may permit women to be given an earlier definitive diagnosis of miscarriage. Trial registration number Audit registration GRM_104 Imperial Healthcare NHS Trust

P-144 Utilizing artificial intelligence to uncover Day 5 morphokinetic features associated with single blastocyst transfer implantation outcome

Abstract Study question Can AI aid in studing embryos’ continuous development in Day5 and identifying morphokinetic features (blastocyst growth and spontaneous collapse etc.), to improve implantation potential prediction? Summary answer The AI system utilized time-lapse images to measure newly identified morphokinetic features, establishing a significant correlation with clinical pregnancy outcomes. What is known already In Single Blastocyst Transfer (SBT), the conventional Gardner evaluation system may inadequately differentiate between embryos of comparable morphology scores in specific cases. To address this, integrating new morphokinetic features is essential for enhanced blastocyst evaluation. Spontaneous collapse (SC) during blastocyst expansion is a phenomenon that was revealed relatively recently following the clinical application of time-lapse monitoring in IVF laboratories. Previous studies link embryo size and SC to quality, yet these correlations require further validation. In the critical selection process utilizing time-lapse imaging (TLI) systems, AI technology is indispensable for developing automated and interpretable tools to ensure precise quantitative measurements. Study design, size, duration 255 patients underwent IVF with Day5 single blastocyst transfer in fresh cycles at the Center for Reproductive Medicine, Nanjing Drum Tower Hospital, from April 2021 to August 2022, and were analyzed in this retrospective study. Embryos were cultured in time-lapse incubators (CCM-iBIS, ASTEC). On Day 3 embryos were transferred to sequential media (G2, Vitrolife, Sweden) and cultured in the same incubator until Day5. In this cohort, there were 167 clinical pregnancies and 88 non-pregnant cases. Participants/materials, setting, methods An AI system was developed to calculate the development curves of areas in each part of the embryo (ZP,blastocel, ICM and TE) based on TLI images from 92 to 116 phi(±2). T-test and correlation analysis were used to select effective features. The dataset was divided into training and testing subset in an 80:20 ratio. The performance of different prediction models were compared by Delong test. Main results and the role of chance In this study, an AI system automatically generated blastocyst development curves, from which 35 morphokinetic features were extracted. These features were carefully defined to comprehensively capture the dynamics of embryo size development and spontaneous collapse (SC). Six parameters, including maximum size, max/min ratio of blastocyst area (with and without ZP region), speed of expansion after tSB, and number of minor SC, exhibited statistical correlation with clinical pregnancy outcomes. Using these parameters, an XGBoost model achieved an AUC of 0.71 for pregnancy prediction, surpassing (p = 0.0307, p &amp;lt; 0.05) the AUC of 0.48 from the model trained with manual Gardner evaluation. These findings underscore the potential of AI-generated morphokinetic features of D5 in enhancing blastocyst evaluation systems. Limitations, reasons for caution The limited sample size used in this retrospective experiment may lead to an underrepresentation of certain significant features. Wider implications of the findings In contrast to prior findings, most SC-based features in our study did not significantly correlate with clinical pregnancy outcome. Further research is needed to understand their causes and implications. Integrating AI with TLI offers promise for improving single blastocyst transfer outcomes, emphasizing quantifiability and interpretability in approach. Trial registration number NA

P-244 Which embryo selection model should be prioritized for transfer of a single euploid blastocyst?

Abstract Study question Which embryo selection model would be given high priority for single euploid blastocyst transfer, iDAScore® v2.0, KIDScoreTM D5 v3.2 or conventional morphological grading system? Summary answer Prioritize morphological grading over embryo score for single euploid blastocyst transfers, and reverse the priority for single non-PGT-A blastocyst transfers. What is known already The use of effective tools, such as AI, morphokinetic data and the Gardner criteria, for embryo selection within in vitro fertilization (IVF) has the potential to increase the possibility of pregnancy. Nevertheless, previous studies indicated that the best embryo these tools prioritize may be inconsistent and controversial. Therefore, this study demonstrates integrated reference tables of FHB+ rates for selecting of single embryo transfer (SET) clinically, and assess the association between iDAScore®, KIDScoreTM, traditional morphological grading and embryonic ploidy status. Study design, size, duration Retrospective study from November 2022 to October 2023 with morphokinetic parameters of time-lapse monitoring analysis involving embryos from 264 patients who underwent day-5 single vitrified-warmed blastocyst transfer with or without preimplantation genetic testing for aneuploidies (PGT-A) (total SET=264; euploid=158; non-biopsied=106) using Embryocope® Plus incubators. After SET, the rates of FHB+ of each group were analyzed. Mean female age was 35.2 years. Participants/materials, setting, methods Blastocyst morphology was scored in 3 groups: good (AA, AB, BA), average (BB), poor-quality embryos (BC, CB, CC). Blastocysts were ranked established on the scores caused by iDAScore or KIDScore. All cycles were stratified into 4 score groups (8.1-9.9, 6.1-8.0, 3.7-6.0, 1.0-3.6). Assisted hatching was conducted on day 3. Trophectoderm biopsies were performed on day 5, and examine the embryonic ploidy status using a next-generation sequencing-based PGT-A platform (Thermo/Ion GeneStudio™ S5 Prime). Main results and the role of chance In D5 non-PGT-A SET group, the FHB+ rates of good-quality embryos were higher than those of average and poor-quality embryos (49% vs. 40% vs. 0%). According to the embryo score group, the group with higher scores showed better FHB+ rates (KIDScore: 56.9% vs. 47.2% vs. 16.7% vs. 0%; iDAScore: 59.1% vs. 49.6% vs. 14.9% vs. 0%). The non-PGT-A results indicated that embryo score should be given high priority. In D5 euploidy SET group, the FHB+ rates of good-quality embryos were higher than those of average-quality embryos (78.12% vs. 56.00% vs. 44.44%). According to the embryo score group, the group with higher scores did not show distinct better FHB+ rates (KIDScore: 65% vs. 69.51% vs. 47.6% vs. 0%; iDAScore: 64.1% vs. 67.7% vs. 38.8% vs. 0%). The PGT-A results indicated that morphological grading could be given high priority. Based on the data, we hypothesized that assisted hatching might lead to distortion in embryo scores. Limitations, reasons for caution The study is limited by its retrospective single center study with small sample size of single embryo transferred even some of the groups have no embryo transfer. Therefore, a prospective multicenter validation is necessary. Wider implications of the findings This study provides distinct tables for clinical embryo selection with or without PGT-A. Our findings support the potential application of the integration of AI, morphokinetic data and embryo quality prediction systems, and indicate the possibility of making appropriate decisions in different age groups clinically. Trial registration number Not Applicable

Transcription templated assembly of the nucleolus in the C. elegans embryo.

The nucleolus is a multicomponent structure made of RNA and proteins that serves as the site of ribosome biogenesis within the nucleus. It has been extensively studied as a prototype of a biomolecular condensate whose assembly is driven by phase separation. While the steady-state size of the nucleolus is quantitatively accounted for by the thermodynamics of phase separation, we show that experimental measurements of the assembly dynamics are inconsistent with a simple model of a phase-separating system relaxing to its equilibrium state. Instead, we show that the dynamics are well described by a model in which the transcription of ribosomal RNA actively drives nucleolar assembly. We find that our model of active transcription-templated assembly quantitatively accounts for the rapid kinetics observed in early embryos at different developmental stages, and for different RNAi perturbations of embryo size. Our model predicts a scaling of the time to assembly with the volume of the nucleus to the one-third power, which is confirmed by experimental data. Our study highlights the role of active processes such as transcription in controlling the placement and timing of assembly of membraneless organelles.

Rapid response of fly populations to gene dosage across development and generations

Although the effects of genetic and environmental perturbations on multicellular organisms are rarely restricted to single phenotypic layers, our current understanding of how developmental programs react to these challenges remains limited. Here, we have examined the phenotypic consequences of disturbing the bicoid regulatory network in early Drosophila embryos. We generated flies with two extra copies of bicoid, which causes a posterior shift of the network’s regulatory outputs and a decrease in fitness. We subjected these flies to EMS mutagenesis, followed by experimental evolution. After only 8–15 generations, experimental populations have normalized patterns of gene expression and increased survival. Using a phenomics approach, we find that populations were normalized through rapid increases in embryo size driven by maternal changes in metabolism and ovariole development. We extend our results to additional populations of flies, demonstrating predictability. Together, our results necessitate a broader view of regulatory network evolution at the systems level.

Different narcotic gases and concentrations for immobilization of ostrich embryos for in-ovo imaging

In-ovo imaging using avian eggs has been described as a potential alternative to animal testing using rodents. However, imaging studies are hampered by embryonal motion producing artifacts. This study aims at systematically comparing isoflurane, desflurane and sevoflurane in three different concentrations in ostrich embryos. Biomagnetic signals of ostrich embryos were recorded analyzing cardiac action and motion. Ten groups comprising eight ostrich embryos each were investigated: Control, isoflurane (2%, 4%, and 6%), desflurane (6%, 12%, and 18%) and sevoflurane (3%, 5%, and 8%). Each ostrich egg was exposed to the same narcotic gas and concentration on development day (DD) 31 and 34. Narcotic gas exposure was upheld for 90 min and embryos were monitored for additional 75 min. Toxicity was evaluated by verifying embryo viability 24 h after the experiments. Initial heart rate of mean 148 beats/min (DD 31) and 136 beats/min (DD 34) decreased over time by 44–48 beats/minute. No significant differences were observed between groups. All narcotic gases led to distinct movement reduction after mean 8 min. Embryos exposed to desflurane 6% showed residual movements. Isoflurane 6% and sevoflurane 8% produced motion-free time intervals of mean 70 min after discontinuation of narcotic gas exposure. Only one embryo death occurred after narcotic gas exposure with desflurane 6%. This study shows that isoflurane, desflurane and sevoflurane are suitable for ostrich embryo immobilization, which is a prerequisite for motion-artifact free imaging. Application of isoflurane 6% and sevoflurane 8% is a) safe as no embryonal deaths occurred after exposure and b) effective as immobilization was observed for approx. 70 min after the end of narcotic gas exposure. These results should be interpreted with caution regarding transferability to other avian species as differences in embryo size and incubation duration exist.

New insights into the reproduction and migration of the porbeagle shark Lamna nasus (Bonnaterre 1788) in the Southwest Atlantic Ocean.

The objective of this study was to estimate the reproductive parameters of porbeagle shark in the Southwest Atlantic Ocean and thus characterize the adult fraction of this population. Therefore, 1012 specimens were measured by scientific observers on board the commercial trawl fleet operating south of 50° S. The size range of the specimens was from 77 to 292 cm fork length (LF). The mean size at maturity was estimated to be 153 cm LF for males and 172 cm LF for females. Porbeagle shark catches were recorded throughout the year, with the highest frequency occurring between November and June. The presence of pregnant females was observed from December to July, along with an increase in the average size of embryos in each litter. The information presented in this study improves the knowledge of the reproductive biology and allows to propose a migratory pattern of adult porbeagle females in the Southwest Atlantic Ocean. The likely seasonal increase in vulnerability of this shark to austral trawl fishery, despite all conservation management measures established in Argentina, underscores the importance of promoting its proper management and conservation given the need to improve understanding of porbeagle population dynamics in the Southern Hemisphere.

The Wnt-dependent master regulator NKX1-2 controls mouse pre-implantation development

Embryo size, specification, and homeostasis are regulated by a complex gene regulatory and signaling network. Here we used gene expression signatures of Wnt-activated mouse embryonic stem cell (mESC) clones to reverse engineer an mESC regulatory network. We identify NKX1-2 as a novel master regulator of preimplantation embryo development. We find that Nkx1-2 inhibition reduces nascent RNA synthesis, downregulates genes controlling ribosome biogenesis, RNA translation, and transport, and induces severe alteration of nucleolus structure, resulting in the exclusion of RNA polymerase I from nucleoli. In turn, NKX1-2 loss of function leads to chromosome missegregation in the 2- to 4-cell embryo stages, severe decrease in blastomere numbers, alterations of tight junctions (TJs), and impairment of microlumen coarsening. Overall, these changes impair the blastocoel expansion-collapse cycle and embryo cavitation, leading to altered lineage specification and developmental arrest.

The Influence of Maturity, Storage, and Embryo Size on Coconut Callus Induction Success

Coconut palms (Cocos nucifera L.) are globally significant palms with both economic and cultural value. Despite the increasing demand for coconut products, production is decreasing globally due to palm senility, pests, and diseases. It has been estimated that over half of the world’s coconut palms need to be replaced immediately. The coconut industry has acknowledged that conventional propagation methods are unlikely to yield sufficient high-quality planting material. Therefore, coconut tissue culture is considered a potential solution to this problem. By using coconut tissue culture, a large number of plantlets can be obtained in a short period of time. In this study, the quality of explants and the development stage (visible shoot/non-visible shoot) of coconut used for micropropagation were examined. To our knowledge, little research has been undertaken on this aspect of coconut micropropagation. Our results indicated that tender coconut fruit exhibited an advantage over mature fruits. In addition, coconut plumule explants subjected to an extended storage of 15 days demonstrated enhanced development compared to those without storage. Notably, smaller embryos utilized as explants displayed superior callus formation compared to their larger counterparts. Finally, embryos possessing shoots exhibited improved callus initiation, albeit accompanied by a more pronounced browning effect. Further investigations are required to obtain more knowledge about the most suitable conditions for plumule explants that lead to optimal callus initiation.

Local and global stressors as major drivers of the drastic regression of brown macroalgae forests in an oceanic island

Similar to other coastal regions worldwide, forests created by brown macroalgae have severely declined in recent decades across the Macaronesian oceanic archipelagos (northeastern Atlantic), eroding the provision of ecosystem services. However, the putative effects of natural and anthropogenic stressors (both local and global) on such declines across spatial and temporal scales remain unresolved. Our research endeavored to investigate the connection between local and global stressors and the distribution and extent of the brown macroalgae Gongolaria abies-marina in the rocky intertidal and adjacent subtidal zones of Gran Canaria over the past four decades. We also quantified the presence of populations at small scales, according to local micro-habitat topography (“open rock” versus “refuge”). Through herbarium records, we additionally analyzed the historical variation in the thallus size of the species. Finally, we experimentally assessed the thermotolerance of embryonic stages to warming. The main environmental drivers explaining the regression of G.abies-marina were the increasing number of marine heatwaves, while the number of local human impacts (quantified through the HAPI index) also accounted for further regression in the extent of marine forests. Warming experimentally reduced the survival and size of macroalgal embryos. A progressive miniaturization of the species, currently restricted to micro-habitat refuges as a survival strategy, seems likely to be the final stage in the progressive disappearance of this macroalgae from the island’s rocky shores.

Hyperspectral imaging combined with GA-SVM for maize variety identification.

The demand for identification of maize varieties has increased dramatically due to the phenomenon of mixed seeds and inferior varieties pretending to be high-quality varieties continuing to occur. It is urgent to solve the problem of efficient and accurate identification of maize varieties. A hyperspectral image acquisition system was used to acquire images of maize seeds. Regions of interest (ROI) with an embryo size of 10 × 10 pixel were extracted, and the average spectral information in the range of 949.43-1709.49 nm was intercepted for the subsequent study in order to eliminate random noise at both ends. Savitzky-Golay (SG) smoothing algorithm and multiple scattering correction (MSC) were used to pretreat the full-band spectrum. The feature wavelengths were screened by successive projection algorithms (SPA), competitive adaptive reweighted sampling (CARS) single screening, and two combinations of CARS-SPA and CARS + SPA, respectively. Support vector machines (SVMs) and models optimized based on genetic algorithm (GA), particle swarm optimization (PSO) were established by using full bands (FB) and feature bands as the model input. The results showed that the MSC-(CARS-SPA)-GA-SVM model had the best performance with 93.00% of the test set accuracy, 8 feature variables, and a running time of 24.45 s. MSC pretreatment can effectively eliminate the scattering effect of spectral data, and the feature wavelengths extracted by CARS-SPA can represent all wavelength information. The study proved that hyperspectral imaging combined with GA-SVM can realize the identification of maize varieties, which provided a theoretical basis for maize variety classification and authenticity identification.

The significance of light chronodestruction in the development of the embryotoxic effect in the experiment

Objective. To assess the significance of light chronodestruction in the development of the embryotoxic effect in the experiment. Materials and methods. The experiment was conducted on 60 female rats of the Wistar line. To assess the significance of chronodestruction in the development of embryotoxic effect, the uterus was isolated in the experiment, in which the number of implantation sites, the total number of embryos, the number of live and dead embryos, and the number of resorptions were estimated. The number of corpus luteum in the harvested ovaries was estimated. In addition, the mean embryo weight (g) and mean craniocaudal size (mm) were recorded. Indicators of embryotoxic effects of light deprivation were determined by pre- and post-implantation death, which was calculated in accordance with methodological recommendations. Results. Exposure to light deprivation reduces the number of implantation sites as of 7th, 14th and 21st days by 1,5-1,8 times, the total number of embryos by 1,6-1,8 times, the number of living embryos by 2,2-9 times and increases the number of dead embryos as of 14th and 21st days by 4-5,5 times, the number of resorptions – 1,6-11 times. The average craniocaudal size (mm) of embryos in experimental animals was recorded below control values by 1,5 times, 1,3 and 3,7 times by 7th, 14th, 21st days respectively. In females exposed to light deprivation, there was a significant increase in pre-implantation mortality by 35-41,8 times and post-implantation mortality by 7,2-20,4 times compared to the control. Conclusion. Light deprivation may have a negative effect on pregnancy and fetal development in female rats, which is confirmed by an increase in pre- and post-implantation mortality.