Effect of Temperature on the Embryogenesis of Three Geographically Distinct Populations of Meloidogyne incognita Is Driven by Intrinsic Thermal Acclimation Reaction.

Research interest in the mechanisms enabling plant-parasitic nematodes to adjust their physiological performance and cope with changing temperatures has intensified in light of global warming. Here, we show that geographically distinct populations of the root-knot nematode Meloidogyne incognita, which is prevalent in the three main pepper-growing regions in Israel-Carmel Valley (Carmel), Jordan Valley (JV), and Arava Rift (Arava)-possess persistent differences in their thermal acclimation capacity, which affect pre- and postembryonic development. The optimal temperature for embryonic growth completion was 25°C for the Carmel population; 25 and 30°C for the JV population; and 30°C for the Arava population. Cumulative hatching percentages showed variations among populations; relative to hatching at 25°C, the Carmel population experienced hatching reduction at the higher studied temperatures 30 and 33°C, while the JV and Arava populations exhibited an increase in hatching at 30 and 33°C, respectively. Juvenile survival indicates that at the lowest temperature (20°C), the Carmel population gained the highest survival rates throughout the experimental duration, while at the same duration at 33°C, the Arava population gained the highest survival rate. Infective juveniles of the Carmel population demonstrated increased penetration of tomato roots at 25°C compared to the JV and Arava populations. Inversely, at 33°C, increased penetration was observed for the Arava compared to the Carmel and JV populations. Altogether, the Arava population's performance at 33°C might incur distinct fitness costs, resulting in consistent attenuation compared to the Carmel population at 25°C. Precisely defining a population's thermal acclimation response might provide essential information for models that predict the impact of future climate change on these populations.

A Successful Pregnancy Outcome Using Laser-Assisted Hatching and Platelet-Rich Plasma Perfusion in Advanced Maternal and Paternal Age: A Case Report.

Infertility affects millions globally, with advanced parental age posing a significant risk. This case report details a couple who experienced secondary infertility for 12 years. Following multiple unsuccessful attempts at assisted reproductive technology (ART), a personalized treatment regimen involving platelet-rich plasma (PRP) perfusion and laser-assisted hatching (LAH) resulted in a successful pregnancy. Diagnostic evaluations identified specific reproductive challenges, leading to tailored interventions. A positive pregnancy outcome was achieved after PRP treatment enhanced endometrial thickness and LAH facilitated embryo implantation. This case highlights the importance of individualized treatment strategies in infertility management and proves the potential efficacy of PRP and LAH in overcoming recurrent implantation failure. Further research is needed to explain the roles of PRP and LAH in improving pregnancy outcomes, especially in older parents and couples with a history of failed in vitro fertilization (IVF) treatments.

Exploring the benefit of different methods to perform assisted hatching in the ART laboratory: A narrative review.

In the last decades, to enhance success rates in assisted reproductive technology (ART) cycles, scientists have continually tried to optimize embryo culture and selection to increase clinical outcomes. In this scenario, the application of laser technology has increased considerably worldwide and is currently applied across ART in several ways: for assisted hatching (AH) or thinning of the zona pellucida (ZP), embryo biopsy, to immobilize and select the sperm during intracytoplasmic sperm injection, as well as to induce artificial blastocyst shrinkage before cryopreservation. Laser-AH has been suggested as a procedure to improve embryo implantation: the concept is that drilling holes through or thinning of the ZP could improve the hatching process and implantation. The artificial disruption of the ZP can be performed by different approaches: mechanically, chemically and with the laser, which is one of the most favourable and easy methods to remove part of the ZP and to augment the possibilities of implantation in patients defined as having a poor prognosis of success, or when the ZP is too thick. However, in the current literature, there is not sufficient evidence about the potential risk or impairment that laser utilization might induce on embryo development; therefore, the main aim of the current review is to provide an overview of the existing knowledge on the ZP and the mechanisms of manipulating it to improve the effectiveness of ART. Also, it emphasizes the positive aspect of laser application as a powerful tool that might increase the chance of pregnancy for infertile couples undergoing ART cycles.

Assessing the Efficacy of Acanthoic Acid Isolated from Acanthopanax koreanum Nakai in Male Infertility: An In Vivo and In Silico Approach.

Acanthoic acid, a diterpene isolated from the root bark of Acanthopanax koreanum Nakai, possesses diverse pharmacological activities, including anti-inflammatory, anti-diabetic, gastrointestinal protection, and cardiovascular protection. This study is the first to investigate the egg-hatching rates of Drosophila melanogaster affected by acanthoic acid. Notably, male flies supplemented with 10 µM acanthoic acid exhibited a strong increase in hatching rates compared with controls under adverse temperature conditions, suggesting a potential protective effect against environmental stressors. Molecular docking simulations revealed the binding affinities and specific interactions between acanthoic acid and proteins related to male infertility, including SHBG, ADAM17, and DNase I, with binding affinity values of -10.2, -6.8, and -5.8 kcal/mol, respectively. Following the docking studies, molecular dynamic simulations were conducted for a duration of 100 ns to examine the stability of these interactions. Additionally, a total binding energy analysis and decomposition analysis offered insights into the underlying energetic components and identified key contributing residues.

Cellular mechanisms of monozygotic twinning: clues from assisted reproduction.

BACKGROUND: Monozygotic (MZ) twins are believed to arise from the fission of a single fertilized embryo at different stages. Monochorionic MZ twins, who share one chorion, originate from the splitting of the inner cell mass (ICM) within a single blastocyst. In the classic model for dichorionic MZ twins, the embryo splits before compaction, developing into two blastocysts. However, there are a growing number of ART cases where a single blastocyst transfer results in dichorionic MZ twins, indicating that embryo splitting may occur even after blastocyst formation. OBJECTIVE AND RATIONALE: For monochorionic MZ twins, we conducted a comprehensive analysis of the cellular mechanisms involved in ICM splitting, drawing from both ART cases and animal experiments. In addition, we critically re-examine the classic early splitting model for dichorionic MZ twins. We explore cellular mechanisms leading to two separated blastocysts in ART, potentially causing dichorionic MZ twins. SEARCH METHODS: Relevant studies including research articles, reviews, and conference papers were searched in the PubMed database. Cases of MZ twins from IVF clinics were found by using combinations of terms including 'monozygotic twins' with 'IVF case report', 'ART', 'single embryo transfer', or 'dichorionic'. The papers retrieved were categorized based on the implicated mechanisms or as those with unexplained mechanisms. Animal experiments relating to MZ twins were found using 'mouse embryo monozygotic twins', 'mouse 8-shaped hatching', 'zebrafish janus mutant', and 'nine-banded armadillo embryo', along with literature collected through day-to-day reading. The search was limited to articles in English, with no restrictions on publication date or species. OUTCOMES: For monochorionic MZ twins, ART cases and mouse experiments demonstrate evidence that a looser ICM in blastocysts has an increased chance of ICM separation. Physical forces facilitated by blastocoel formation or 8-shaped hatching are exerted on the ICM, resulting in monochorionic MZ twins. For dichorionic MZ twins, the classic model resembles artificial cloning of mouse embryos in vitro, requiring strictly controlled splitting forces, re-joining prevention, and proper aggregation, which allows the formation of two separate human blastocysts under physiological circumstances. In contrast, ART procedures involving the transfer of a single blastocysts after atypical hatching or vitrified-warmed cycles might lead to blastocyst separation. Differences in morphology, molecular mechanisms, and timing across various animal model systems for MZ twinning can impede this research field. As discussed in future directions, recent developments of innovative in vitro models of human embryos may offer promising avenues for providing fundamental novel insights into the cellular mechanisms of MZ twinning during human embryogenesis. WIDER IMPLICATIONS: Twin pregnancies pose high risks to both the fetuses and the mother. While single embryo transfer is commonly employed to prevent dizygotic twin pregnancies in ART, it cannot prevent the occurrence of MZ twins. Drawing from our understanding of the cellular mechanisms underlying monochorionic and dichorionic MZ twinning, along with insights into the genetic mechanisms, could enable improved prediction, prevention, and even intervention strategies during ART procedures. REGISTRAITON NUMBER: N/A.

Advanced screening methods for assessing motility and hatching in plant-parasitic nematodes.

BACKGROUND: Plant-parasitic nematodes are economically important pests responsible for substantial losses in agriculture. Researchers focusing on plant-parasitic nematodes, especially on finding new ways of their control, often need to assess basic parameters such as their motility, viability, and reproduction. Traditionally, these assays involve visually counting juveniles and eggs under a dissecting microscope, making this investigation time-consuming and laborious. RESULTS: In this study, we established a procedure to efficiently determine the motility of two plant-parasitic nematode species, Heterodera schachtii and Ditylenchus destructor, using the WMicrotracker ONE platform. Additionally, we demonstrated that hatching of the cyst nematode H. schachtii can be evaluated using both the WMicrotracker ONE and by assessing the enzymatic activity of chitinase produced during hatching. CONCLUSIONS: We present fast and straightforward protocols for studying nematode motility and hatching that allow us to draw conclusions about viability and survival. Thus, these methods are useful tools for facilitating fast and efficient evaluation in various fields of research focused on plant-parasitic nematodes.

Biocontrol potential of endophytic fungi against phytopathogenic nematodes on potato (Solanum tuberosum L.).

Root-knot nematodes (RKNs) are a vital pest that causes significant yield losses and economic damage to potato plants. The use of chemical pesticides to control these nematodes has led to environmental concerns and the development of resistance in the nematode populations. Endophytic fungi offer an eco-friendly alternative to control these pests and produce secondary metabolites that have nematicidal activity against RKNs. The objective of this study is to assess the efficacy of Aspergillus flavus (ON146363), an entophyte fungus isolated from Trigonella foenum-graecum seeds, against Meloidogyne incognita in filtered culture broth using GC-MS analysis. Among them, various nematicidal secondary metabolites were produced: Gadoleic acid, Oleic acid di-ethanolamide, Oleic acid, and Palmitic acid. In addition, biochemical compounds such as Gallic acid, Catechin, Protocatechuic acid, Esculatin, Vanillic acid, Pyrocatechol, Coumarine, Cinnamic acid, 4, 3-indol butyl acetic acid and Naphthyl acetic acid by HPLC. The fungus was identified through morphological and molecular analysis, including ITS 1-4 regions of ribosomal DNA. In vitro experiments showed that culture filtrate of A. flavus had a variable effect on reducing the number of egg hatchings and larval mortality, with higher concentrations showing greater efficacy than Abamectin. The fungus inhibited the development and multiplication of M. incognita in potato plants, reducing the number of galls and eggs by 90% and 89%, respectively. A. flavus increased the activity of defense-related enzymes Chitinas, Catalyse, and Peroxidase after 15, 45, and 60 days. Leaching of the concentrated culture significantly reduced the second juveniles' stage to 97% /250 g soil and decreased the penetration of nematodes into the roots. A. flavus cultural filtrates via soil spraying improved seedling growth and reduced nematode propagation, resulting in systemic resistance to nematode infection. Therefore, A. flavus can be an effective biological control agent for root-knot nematodes in potato plants. This approach provides a sustainable solution for farmers and minimizes the environmental impact.

Research Note: Effects of different light-emitting diode lights during egg incubation on hatching performance and embryo development in White King pigeons.

The light provide during incubation can influence hatching characteristics (hatching time, hatchability, etc.) and embryo development in chickens, geese, and turkeys. However, relevant studies on this factor in pigeons are lacking. This study investigated the effects of in ovo photostimulation during embryogenesis on hatching performance, squab quality, and embryo development in pigeons. 400 eggs from paired- bred pigeons were randomly distributed into 4 incubation lighting treatments, with 2 replicates per treatment. The treatments included dark as a control (NL), 12-h light, and 12-h dark photoperiods of white light (WL), red light (RL), and green light (GL) (100 lx at egg level) during the first 15 d of incubation. A total of 1,600 eggs in 4 batches from White King pigeons were used. The results showed that hatching time of the WL group was significantly shorter than that of the dark light group (P < 0.05). The hatchability of fertile eggs in the WL group was significantly higher (P < 0.05), whereas the hatchability of fertile eggs in the RL group was significantly lower (P < 0.05) than that of in the control group. Light stimulation had no effect on time to 90% hatching or average hatching time (P > 0.05). In addition, the hatch window was not extended by light stimulation (P > 0.05). The group incubated under GL showed an increase in embryo weight and relative leg muscle on embryonic d 14 and the hatching day compared to the dark incubation (P < 0.05). Green light stimulated the heart and liver development during the early and middle stages of embryogenesis. It was concluded that white light stimulation during embryogenesis accelerated the hatching process, whereas monochromatic green light had a positive effect on embryo development. Our findings provide important guidance for developing light protocols for pigeon egg incubation.

A conventional hatchery vs "on-farm" hatching of broiler chickens in terms of microbiological and microclimatic conditions.

"On-farm hatching" is one of the proposed alternatives to conventional hatchery-hatching. This solution reduces distress and improves the welfare of the chicks around the hatching period. Therefore, it seemed interesting to compare conventional hatchery and "on-farm" hatching in terms of microbiological and microclimatic conditions. Hatching eggs (Ross 308) were incubated in a commercial hatchery. The control group (HH, 683 eggs) hatched in a conventional hatcher, while the other eggs were transported into the experimental chicken-hall for on-farm hatching, and set in pens directly on litter (OL, 667 eggs) or plastic trays (OT, 678 eggs). One-day-old chicks were also placed in the experimental hall. Microclimatic parameters were controlled every 12 h. The microbiological status of the surface of the eggshells and the litter was assessed based on the total number of aerobic mesophilic microorganisms and also the selected individual genus/species of bacteria. The hatchability of HH was 96.4% in comparison to 93.9% and 95.8% for OL and OT, respectively (P > 0.05). On the other hand, 2.1% of the HH chicks were found injured/dead, while only 0.2-0.3% of the on-farm groups were. The total number of aerobic mesophilic microflora on the surface of as-hatched shells was 4.93 ± 0.629 log CFU/g in HH, while only 1.14 ± 0.995 and 1.93 ± 1.709 log CFU/g in OL and OT, respectively (P < 0.001). Similarly, the total count of bacteria in the litter in the on-farm hatched pens was 1.9-fold lower than in pens set with HH chicks (P < 0.001). In summary, on-farm hatching results in hatchability that is no worse than in a conventional hatcher, while the microbiological status of as-hatched eggshells and litter is significantly better. Therefore, on-farm hatching seems to provide appropriate environmental conditions for newly hatched chicks and poses no epizootic risk.

Fish (eggs) out of water: evolutionary divergence in terrestrial embryonic plasticity in Trinidadian killifish.

Externally laid eggs are often responsive to environmental cues; however, it is unclear how such plasticity evolves. In Trinidad, the killifish (Anablepsoides hartii) is found in communities with and without predators. Here, killifish inhabit shallower, ephemeral habitats in sites with predators. Such shifts may increase the exposure of eggs to air and lead to possible desiccation. We compared egg-hatching plasticity between communities by rearing eggs terrestrially on peat moss or in water. The timing of hatching did not differ between communities when eggs were reared in water. Eggs from sites with predators responded to terrestrial incubation by hatching significantly earlier compared with water-reared eggs. These responses were weaker in sites with no predators. Such divergent trends show that the presence of predators is associated with evolutionary shifts in hatching plasticity. Our results provide evidence for local adaptation in embryonic plasticity at the population scale.

Unlocking the Potential of Assisted Hatching in Assisted Reproductive Technology: A Narrative Review.

The present study is set in the broad field of assisted reproductive technologies (ARTs) and examines various procedures under assisted hatching (AH). It also reviews their effects on implantation success rates. The primary emphasis is on explaining who has benefited and how many have benefited from these interventions. The most important factor determining the success rate of ART is implantation. To increase these rates, we use AH in our clinics to enhance each embryo's chances at life and substantially improve overall results. This comprehensive review includes various approaches, such as chemical-based measures (such as applying Tyrode's solution) and mechanical techniques (such as zona drilling and partial zona dissection). The individual techniques are carefully scrutinized, considering their mechanical detailing, methods of applying therapeutic effects, and the appropriateness of matching present social circumstances. The review begins by analyzing the basic nature of AH as a medium for embryo implantation and then focuses on how this detailed view reveals the advantages and drawbacks of various methods. Moreover, the articles discuss improvements in AH technology and many of the most modern technological developments that can help fine-tune ART issues. A major problem with these methodologies is that they involve serious risks and legal complications. However, a broad assessment of these topics allows us to understand their impact on fertility treatments. This review is written as a guidebook for physicians and researchers working in reproductive medicine. It compiles all current knowledge, providing literature to build on successes that will make breakthroughs possible in ART. Indeed, this is a valuable reference for guiding us in navigating complex AH procedures. It advances ARTs step by step toward perfection.

Leucocytozoon Infection Does Not Influence the Survival of Boreal Owl Aegolius funereus Nestlings.

Leucocytozoon infection has been observed to impact the reproductive ecology and physiology of avian hosts, but its influence on nestling survival remains unclear. We investigated the effect of Leucocytozoon infection intensity, determined through triplicate PCR sample analyses, on the survival of 256 boreal owl (Aegolius funereus) nestlings during an 8-yr study. Contrary to our expectations, the survival probability of boreal owl nestlings was not influenced by their Leucocytozoon infection intensity. Nestling age and Leucocytozoon infection intensity in male and female parents also did not impact nestling survival. Instead, food abundance and hatching order were the key factors influencing nestling survival. Additionally, we observed a significantly higher Leucocytozoon infection intensity in male parents compared to female parents and nestlings. We suggest a distinct division of parental roles may lead females and nestlings staying within the nest boxes (cavities) to experience lower exposure to potential vectors transmitting blood parasites than their male counterparts. Our study shows that Leucocytozoon disease may not be lethal for boreal owl chicks, exhibiting a below-average infection intensity compared to their male parents.

La infección por Leucocytozoon no influye en la supervivencia de los polluelos de mochuelo boreal Aegolius funereus. Se ha observado que la infección por Leucocytozoon afecta la ecología y fisiología reproductiva de las aves hospedadoras, pero su influencia en la supervivencia de los polluelos aún no está completamente determinada. Se investigó el efecto de la intensidad de la infección por Leucocytozoon, determinada mediante análisis de muestras de PCR por triplicado, sobre la supervivencia de 256 polluelos de mochuelo boreal (Aegolius funereus) durante un estudio de ocho años. Contrariamente a nuestras expectativas, la probabilidad de supervivencia de los polluelos de mochuelo boreal no se vio influenciada por la intensidad de la infección por Leucocytozoon. La edad de los polluelos y la intensidad de la infección por Leucocytozoon en los padres machos y hembras tampoco afectaron la supervivencia de los polluelos. En cambio, la abundancia de alimento y el orden de eclosión fueron los principales factores que influyeron en la supervivencia de los polluelos. Además, se observó una intensidad de infección por Leucocytozoon significativamente mayor en los padres machos en comparación con las hembras y los polluelos. Se sugiere que una clara división de los roles parentales puede llevar a que las hembras y los polluelos que permanecen dentro de las cajas nido (cavidades) experimenten una menor exposición a vectores potenciales que transmitan parásitos sanguíneos en comparación con los individuos adultos masculinos. Nuestro estudio muestra que la enfermedad de Leucocytozoon puede no ser letal para los polluelos de mochuelo boreal, ya que exhiben una intensidad de infección por debajo del promedio en comparación con sus padres machos.

Shark critical life stage vulnerability to monthly temperature variations under climate change.

In a 10-month experimental study, we assessed the combined impact of warming and acidification on critical life stages of small-spotted catshark (Scyliorhinus canicula). Using recently developed frameworks, we disentangled individual and group responses to two climate scenarios projected for 2100 (SSP2-4.5: Middle of the road and SSP5-8.5: Fossil-fueled Development). Seasonal temperature fluctuations revealed the acute vulnerability of embryos to summer temperatures, with hatching success ranging from 82% for the control and SSP2-4.5 treatments to only 11% for the SSP5-8.5 treatment. The death of embryos was preceded by distinct individual growth trajectories between the treatments, and also revealed inter-individual variations within treatments. Embryos with the lowest hatching success had lower yolk consumption rates, and growth rates associated with a lower energy assimilation, and almost all of them failed to transition to internal gills. Within 6 months after hatching, no additional mortality was observed due to cooler temperatures.

Evaluating anthelmintic activity through Caenorhabditis elegans egg hatching assay.

The Caenorhabditis elegans egg hatching methodology is a valuable tool for assessing the anthelmintic activity of drugs and compounds and evaluating anthelmintic drug efficacy. Isolated eggs from gravid adults are exposed to different concentrations of selected drugs and the percentage of egg hatching is determined with respect to the control condition. The assay allows the construction of concentration-response curves and determination of EC50 or EC90 values for egg hatching inhibition. Also, it allows measurements of inhibition as a function of time of exposure. This approach addresses the urgent need for new anthelmintics, as resistance to current treatments poses a significant challenge in parasitic nematode infection. This resistance not only affects humans but also animals and plants, causing significant economic losses in livestock farming and agriculture. By using the free-living nematode C. elegans as a parasitic model organism, researchers can efficiently screen for potential treatments and assess drug combinations for synergistic effects. Importantly, this assay offers a cost-effective and accessible alternative to traditional methods, eliminating the need for specialized infrastructure, hosts, and trained animal maintenance personnel. Additionally, the methodology closely mimics natural conditions, providing insights into egg development and potential therapeutic targets. This method allows for evaluating the direct negative impact of drugs on egg hatching, which correlates with long-term anthelmintic effects, offering advantages in preventing or reducing the transmission and spread of worm infections by eggs. Overall, this approach represents a significant advancement for anthelmintic discovery, offering both practical applications and avenues for further scientific research. •The C. elegans egg hatching assay is a robust and effective method for assessing the anthelmintic potential of various drugs and compounds, allowing the generation of concentration-response curves.•By leveraging the free-living nematode C. elegans as a parasitic model organism, this method facilitates efficient screening of potential treatments and evaluation of drug combinations.•The method addresses the urgent need for new anthelmintics, offering a cost-effective and accessible alternative to traditional approaches.

Effect of dietary vitamin E supplement on the reproductive performance and gene expression profiling in Ompok bimaculatus during breeding period.

This study aimed to evaluate the effect of vitamin E on the reproductive responses and the expression of reproductive genes in butter catfish (Ompok bimaculatus). Diets with different levels of vitamin E supplementation (0, 100, and 150 mg/kg) were provided to groups of fish for 60 days. After rearing for 60 days fish were induced with synthetic hormone, that is, Ovatide to study the breeding performance. Ovatide was administrated intramuscularly at the rate of 0.5 and 0.25 mL/kg of body weight for females and males, respectively, in all the treatments. Breeding performance result shows that supplements of vitamin E positively influenced the GSI%, fertilization rate, fecundity, and hatching rate. To understand the relationship between vitamin E and the breeding performance of the fish at the molecular level, a gene expression study was conducted. This study employed real-time PCR for the selected genes critical for reproductive function. In the brain, testis, and ovary dietary vitamin E supplementation of 100 mg/kg significantly enhanced the mRNA transcription of FSHR, Brdt, ESR1, 17beta2, and LHR. Hence, it can be said that 100 mg/kg of vitamin E supplementation in the diet during the reproductive period of O. bimaculatus could improve breeding performance and the mRNA expression of reproductive hormone receptor genes in both males and females of O. bimaculatus.

In vitro Fertilization Outcomes of Frozen-thawed Embryo Transfer with Hatched Blastocysts versus with Hatching Blastocysts.

This study aimed to elucidate the effect of hatching status on in vitro fertilization (IVF) outcomes in frozen-thawed blastocyst transfer cycles. Frozen-thawed embryo transfer (FET) cycles performed at a single fertility center between 2016 and 2021 were retrospectively assessed. Analyses were restricted to 6,821 frozen-thawed blastocyst transfers in women aged 24-47 years. For optimal comparability, double embryo transfer (ET) cycles consisting of one hatching and one hatched blastocyst were excluded. The implantation and pregnancy rates were evaluated and compared between the hatching and hatched blastocyst transfer groups based on patients' age (<38 vs. ≥38 years), blastocyst grade (good vs. bad grade), and the number of transferred embryos (single ET vs. double ET). Hatched blastocyst transfer was associated with higher implantation and clinical pregnancy rates in the single ET group (15.7% and 15.6%, respectively; p<0.001). The transfer of two hatched blastocysts had higher implantation and clinical pregnancy rates compared to the transfer of two hatching blastocysts (19.5% and 20.4%, respectively; p<0.001) in the double ET group. In the hatched blastocyst transfer group, the clinical pregnancy and implantation rates were higher, regardless of each woman's age and embryo quality. The IVF treatment outcomes were improved when the blastocysts were hatched during FET cycles. Hence, hatched blastocyst transfer in FET cycles could be considered a superior method in IVF practice.

Elevated ammonia cues hatching in red-eyed treefrogs: A mechanism for escape from drying eggs.

Egg dehydration can kill terrestrial frog embryos, and this threat is increasing with climate change and deforestation. In several lineages that independently evolved terrestrial eggs, and retained aquatic tadpoles, embryos accelerate hatching to escape from drying eggs, entering the water earlier and less developed. However, the cues that stimulate drying-induced early hatching are unknown. Ammonia is a toxic, water-soluble metabolic waste that accumulates within eggs as embryos develop and concentrates as eggs dehydrate. Thus, increasing ammonia concentration may be a direct threat to embryos in drying eggs. We hypothesized that it could serve as a cue, stimulating embryos to hatch and escape. The embryos of red-eyed treefrogs, Agalychnis callidryas, hatch early to escape from many threats, including dehydration, and are known to use mechanosensory, hypoxia, and light cues. To test if they also use high ammonia as a cue to hatch, we exposed stage-matched pairs of hatching-competent, well-hydrated sibling embryos to ammonia and control solutions in shallow water baths and recorded their behavior. Control embryos remained unhatched while ammonia-exposed embryos showed a rapid, strong hatching response; 95% hatched, on average in under 15 min. This demonstrates that elevated ammonia can serve as a hatching cue for A. callidryas embryos. This finding is a key step in understanding the mechanisms that enable terrestrial frog embryos to escape from egg drying, opening new possibilities for integrative and comparative studies on this growing threat.

Growth of brown trout in the wild predicted by embryo stress reaction in the laboratory.

Laboratory studies on embryos of salmonids, such as the brown trout (Salmo trutta), have been extensively used to study environmental stress and how responses vary within and between natural populations. These studies are based on the implicit assumption that early life-history traits are relevant for stress tolerance in the wild. Here we test this assumption by combining two data sets from studies on the same 60 families. These families had been experimentally produced from wild breeders to determine, in separate samples, (1) stress tolerances of singly kept embryos in the laboratory and (2) growth of juveniles during 6 months in the wild. We found that growth in the wild was well predicted by the larval size of their full sibs in the laboratory, especially if these siblings had been experimentally exposed to a pathogen. Exposure to the pathogen had not caused elevated mortality among the embryos but induced early hatching. The strength of this stress-induced change of life history was a significant predictor of juvenile growth in the wild: the stronger the response in the laboratory, the slower the growth in the wild. We conclude that embryo performance in controlled environments can be a useful predictor of juvenile performance in the wild.

Influence of temperature on hatching success of skipjack tuna (Katsuwonus pelamis): Implications for spawning availability of warm habitats.

Exploring the effects of water temperature on egg development in skipjack tuna (Katsuwonus pelamis) has substantial implications for evaluations of wild spawning habitats. In the present study, we examined the hatching success and duration as a function of temperature from 21 to 33°C under captive environments. A high hatching rate of over 50% between 23 and 31°C was observed, with the shortest hatching duration at 31°C. Because the egg period is vulnerable to predators, a shortened hatching duration with warming water would be ecologically advantageous for K. pelamis, as its main spawning grounds are located in tropical areas.

Effects of in ovo injection of organic selenium on the hatchability of broiler breeder hen eggs and resulting chick physiology and performance.

BACKGROUND: Selenium is an essential mineral for poultry. The conflicting reports about its in ovo injection are the justification for the more detailed investigation. OBJECTIVES: The aim of this study was to investigate the effects of in ovo injection of organic selenium on the hatching traits of broiler chickens and their performance. METHODS: Three hundred and twenty eggs of Ross 308 strain with an average weight of 65 g and 160 chicks were randomly divided into 4 treatment groups (each with 8 replicates of 10 eggs each for hatching parameters and 4 replicates of 10 chicks for broiler farming parameters): negative control (no injection), positive control (in ovo injection of 0.272 mL of normal saline solution) and 2 selenium treatments (in ovo injection of 2.72 or 5.44 µg of organic selenium). Injection was into the amniotic sac on the 10th day of incubation. Effects of in ovo injection on hatching and performance traits, blood parameters, immune responses, carcass characteristics, meat fatty acid profile, cecal microbial population and selenium consternation in the tibia were measured. RESULTS: Fewer chicks from the injected treatments hatched than from the negative control group (p < 0.01). However, the injection of selenium increased feed intake and the final weight of the birds (p < 0.01). Blood parameters were also affected. Glucose and cholesterol in experimental treatment chicks was lower than those of the controls (p < 0.01), whereas blood lipoproteins (VLDL, LDL and HDL) and the ratio of cholesterol to HDL was significantly increased in the treatments injected with selenium (p < 0.01). There was no significant difference in the immune response or microbial population between the experimental groups, but carcass components, such as thigh, breast, wing and abdominal fat weight, were significantly greater in the selenium treatments. CONCLUSIONS: Intra-egg injection of organic selenium produced favourable effects on performance of broiler chickens, although it had no effect on immune response or microbial population. However, the negative effect on hatching of chickens needs to be prevented to result in an acceptable economic return for the producer.