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Background Recently, the Japan Society of Obstetrics and Gynecology initiated a clinical study of preimplantation genetic test for aneuploidy. There will be a great need for a standardized embryo biopsy technique in Japan. However, the gold standard trophectoderm (TE) biopsy procedure has not been established, and this review outlines the clinical use of TE biopsy. Methods Based on literature, the method and associated techniques for TE biopsy, a dissection method of TE cells from blastocysts, were investigated. Main findings Two TE biopsy methods are used, namely assisted hatching (herniating) and non‐assisted hatching (direct suction); however, it is not clear which of these methods is superior. It is critical to understand whether the flicking or pulling method is beneficial. Conclusion Non‐assisted hatching biopsy method may cause blastocyst collapse with a higher probability, and it may extend the biopsy time. The biopsy procedure should be performed within 3 minutes, and thus direct TE suction may have greater disadvantages. It is a fact that pulling method of TE dissection with laser pulse is simple; however, excess laser shots may induce a higher frequency of mosaicism. It is important to understand that each technique of TE biopsy has benefits and disadvantages.

One of the major challenges in potato farming across the globe is potato cyst nematodes (PCN). Aeroponic root leachate (ARL ) ,collected from aeroponically grown potato plants, was evaluated for its potential to stimulate Globodera rostochiensis hatching in the absence of a host plant. In vitro assays showed that ARL collected from 30-day-old potato plants induced the highest number of juveniles (J2s) hatching (369 J2s; 48%), far exceeding that induced by root exudate (RE) (105 J2s; 12.6%). Among the tested dilutions, ARL diluted to 50% was most effective (940 J2s; 74.5%), while controls showed no hatching. Pot assays revealed that ARL diluted to 50% and 75% reduced viable eggs by 28.9% and 27.8%, respectively, compared with minimal reductions in controls (tap water; 4.7% and nutrient solution; 6.2%). Field assays (2018–2021) confirmed strong declines in cyst counts across all treatments, with the greatest reduction observed in T 3 (ARL diluted to 50%). Initial viable egg populations (235–287 per cyst) declined markedly by 2021, with T 3 (ARL diluted to 50%) and T 2 (ARL diluted to 75%) showing 46.5% and 44.1% reductions, compared with controls (13.1% in tap water and 11.2% in nutrient solution). In dose-response assays, ARL triggered higher hatching (284 J2s) than α-chaconine (228 J2s at 100 µg/ml) and α-solanine (186 J2s at 1 µg/ml). Further, ARL-assisted potato farming (ARL-APF) showed lower cultivation costs (643.4 USD/ha), energy inputs (34.5 GJ/ha), carbon inputs (1023.2 kg CE/ha), and GHG emissions (3745.9 CO 2 -e kg/ha) over the conventional potato farming (CPF).

The soundscape experienced by animals early in life can affect their behaviour later in life. For birds, sounds experienced in the egg can influence how individuals learn to respond to specific calls post-hatching. However, how early acoustic experiences affect subsequent social behaviour remains unknown. Here, we investigate how exposure to maternal ‘cluck’ calls pre-hatching affects the behaviour of domestic chickens ( Gallus gallus domesticus ) at 3–5 days and 17–21 days old. We incubated eggs and played cluck calls to half of them. After hatching, we raised chicks in small groups occupying different enclosures. At 3–5 days old, we tested chicks’ responses to three stimuli: (i) background sound, (ii) chick calls and (iii) cluck calls. We found that the pre-hatching experience of cluck calls reduced the likelihood of moving in response to all three stimuli. At 17–21 days old, some chicks explored beyond their own enclosure and ‘visited’ other groups. Chicks exposed to cluck calls before hatching were three times more likely to enter another group’s enclosure than control chicks, and this was unaffected by the chicks’ social connectedness. Our results indicate age- and context-dependent responses of chicks to pre-hatching cluck-call playbacks, with potential long-term effects on individual social behaviour.

Variation in life-history strategies is central to our understanding of population dynamics and how organisms adapt to their environments. Yet we lack consensus regarding the ecological processes that drive variation in traits related to reproduction and survival. For example, we still do not understand the cause of two widespread inter- and intraspecific patterns: (1) the ubiquitous positive association between avian clutch size and latitude; and (2) variation in the extent of asynchronous hatching of eggs within a single clutch. Well-known hypotheses to explain each pattern have largely focused on biotic processes related to food availability and predation risk. However, local adaptation to maintain egg viability could explain both patterns with a single abiotic mechanism. The egg viability hypothesis was initially proposed to explain the cause of asynchronous hatching and suggests that asynchronous hatching results from early incubation onset in response to unfavorable nest microclimatic conditions, which otherwise reduce egg viability. However, allocation of resources to early incubation, prior to clutch completion, may energetically constrain clutch size and help explain the positive association between clutch size and latitude. We measured intraspecific variation in five functionally linked life-history traits of burrowing owls at five study sites spanning a 1,400-km latitudinal transect in western North America: clutch size, the timing of incubation onset, the degree of hatching asynchrony, the probability of hatching failure, and nestling survival. We found that most traits varied clinally with latitude, but all the traits were more strongly associated with individual nest microclimates than with latitude, and all varied with nest microclimate in the directions predicted by the egg viability hypothesis. Furthermore, incubation began earlier, hatching asynchrony increased, and clutch size declined across the breeding season. These results suggest that nest microclimate drives an important life-history trade-off and that thermal gradients are often sufficient to account for observed biogeographic and seasonal patterns in life-history strategies. Furthermore, our results reveal a potentially important indirect mechanism by which reproductive success and recruitment could be affected by climate change.

This study was conducted in the poultry farm, College of Agriculture, Al-Muthanna University, from January 29, 2024 to March 3, 2024, To know the effect of in ovo injecting of hatching eggs with local aloe vera extracts on hatching egg and chicks traits of Ross308 broiler. 600 eggs weighing 55±1 gm were used in the experiment, distributed into six treatments, 100 eggs per treatment, placed in incubator dishes, injected with Aloe vera extracts after 18 days of incubation, after hatching, 270 were selected, distributed with 45 chicks per treatment, with three replicates for each treatment (15 chicks/replicate). The treatments were as follows: T1: Negative control treatment (without injection). T2: Positive control (Injection with sterile distilled water only). T3: Injection of hatching eggs with a concentration of 0.01 ml of the aqueous extract, T4: Injection of hatching eggs with a concentration of 0.02 ml of the aqueous extract, T5: Injection of hatching eggs with a concentration of 0.01 ml of the alcoholic extract, T6: Injection of hatching eggs with a concentration of 0.02 ml of alcoholic extract. The results of the experiment showed that the combination treatment of injection with a concentration of 0.02 ml of the alcoholic extract of aloe vera leaves at an incubation period of 18 days was superior to the hatching rate of fertilized eggs, the weight of hatched chicks, and the vital rate of hatched chicks, while the same treatment significantly reduced the embryonic mortality rate, the percentage of pipped eggs, the percentage of deformed chicks, and the total embryonic mortality rate. We conclude from this experiment that the process of injecting hatching eggs at an incubation period of 18 days with a concentration of 0.02 ml of the alcoholic extract of aloe vera leaves, contributed to improving the standards of hatching eggs and hatched chicks of broiler birds.

Background Chicken embryos emerge from their shell by the piercing movement of the hatching muscle. Although considered a key player during hatching, with activity that imposes a substantial metabolic demand, data are still limited. The study provides a bioenergetic and transcriptomic analyses during the pre-post-hatching period. Methods Weight and morphology alongside content determination of creatine and glycogen were analysed. Transcriptome identified differentially expressed genes and enriched biological processes associated with hatching muscle development, catabolism, and energy provision. Using gene set enrichment, we followed the dynamics of gene-sets involved in energy pathways of oxidative phosphorylation, protein catabolism, glycolysis/gluconeogenesis, and glycogen metabolism. Results Results show several significant findings: (A) Creatine plays a crucial role in the energy metabolism of the hatching muscle, with its concentration remaining stable while glycogen concentration is depleted at hatch and placement. (B) The hatching muscle has the capacity for de-novo creatine synthesis, as indicated by the expression of related genes (AGAT, GAMT). (C) Transcriptome provided insights into genes related to energy pathways under conditions of pre-hatch oxygen and post-hatch glucose limitations (oxidative phosphorylation: NDUF, MT-ND, SDH, UQCR, COX, MT-CO, ATP5, MT-ATP; glycolysis/gluconeogenesis: FBP,G6PC, PFKM; glycogen metabolism: PPP1, PYGL, GYG1). (D) The post-hatch upregulation of protein catabolic processes genes (PSMA, RNF, UBE, FBX), which align with the muscle's weight dynamics, indicates a functional shift from movement during hatching to lifting the head during feeding. Conclusions There is a dynamic metabolic switch in the hatching muscle during embryo-to-hatchling transition. When glycogen concentration depletes, energy supply is maintained by creatine and its de-novo synthesis. Understanding the hatching muscle's energy dynamics is crucial, for reducing hatching failures in endangered avian species, and in domesticated chickens.

Background Eggs of anopheline mosquitoes hatch within a few days of laying and require high levels of humidity to survive. Assessing natural variation in egg hatching and its environmental and genetic determinants in sibling species of the malaria vector Anopheles gambiae s.l. is important for understanding their adaptation to variable aquatic habitats. Crucially, it can also inform insectary rearing practices toward the optimization of mosquito production for genetic vector control strategies. Methods Hatching rates and timing of egg hatching in long-established and recently colonized strains of An. gambiae s.s, Anopheles arabiensis , and Anopheles coluzzii , were compared under still water conditions (26 ℃) and with cold (4 ℃) and (15 ℃) water agitation regimes. Next, early and late hatching strains of the recently colonized An. coluzzii VK colony were generated through bidirectional selection for 18–23 generations to detect a genetic component for this trait. Results Hatching rates differed significantly between species and treatments. The older An. arabiensis Senn and An. gambiae s.s. Kisumu strains had the highest proportion of hatching and preferred the nonagitation treatment at 26 °C. In contrast, the more recently colonized An. coluzzii VK and An. arabiensis Rufisque strains had lower overall hatching success but responded strongly to agitation at 4 °C, while the An. coluzzii Mopti strain did not significantly respond to water agitation. In all strains, eggs hatching started at day 2 and continued till day 5 in the older strains, whilst it was more staggered and extended up to day 6 in the younger strains. Bidirectional selection for early and late hatching over many generations resulted in early hatching selected strains with eggs hatching 2–3 days earlier than in late hatching ones indicating a significant heritable component for these traits. Conclusions Water agitation and temperature and age of colonization are likely important determinants of egg hatching in natural An. gambiae s.l. populations. Current rearing protocols systematically select for fast hatching and result in the progressive loss of staggered egg hatching in older laboratory strains. The selection of novel slow-hatching strains may prove instrumental to enable the mass production, shipping, and release of Anopheles mosquitoes across Africa as part of genetic vector control programs. Graphical Abstract

Birds face strong selective pressures to complete individual nesting attempts as quickly as possible to minimize exposure of nests to predators and weather, maximize renesting potential, and maximize hatching success. As a result, the duration of developmental periods and of overall nest periods are often relatively constant within species. However, birds may sometimes be subject to acute energetic constraints that may preclude them from initiating incubation at the optimal time. We report an extraordinary case of delayed incubation by a female Burrowing Owl (Athene cunicularia) in Oregon, USA, which contrasted sharply with a large sample of nests monitored by motion-activated video cameras in western North America from 2015 to 2018. The focal female delayed incubation by 11 d following clutch completion and subsequently experienced near total hatching failure of her clutch. This observation corroborates previous experimental studies regarding the limits to egg viability and trade-offs between the timing of incubation onset and hatching success. These findings illustrate the acute trade-offs faced by nesting birds, and the cost of delayed incubation that we observed in this owl could help explain the cause of asynchronous hatching. Las aves enfrentan fuertes presiones selectivas para completar sus intentos de anidamiento individuales tan rápido como sea posible, para minimizar la exposición del nido a depredadores y al tiempo, maximizar potencial de reanidamiento y maximizar éxito de eclosión. Como resultado, la duración de los periodos de desarrollo y los periodos de anidamiento generales son a menudo relativamente constantes dentro de las especies. Sin embargo, las aves pueden a veces estar sometidas a limitaciones energéticas agudas que pueden impedirles iniciar la incubación en un tiempo óptimo. Reportamos un caso extraordinario de retraso de incubación de una hembra de búho Athene cunicularia en Oregon, Estados Unidos, que contrastó fuertemente con una muestra grande de nidos monitoreados por video cámaras activadas por movimiento en el oeste de Norteamérica de 2015 a 2018. La hembra focal postergó la incubación 11 días después de la puesta y a continuación experimentó una pérdida casi total de la puesta. Esta observación corrobora estudios experimentales previos acerca del límite de viabilidad de los huevos y la compensación entre el tiempo de incubación y el éxito de eclosión. Estos hallazgos ilustran las fuertes compensaciones que enfrentan las aves ponedoras y el costo del retraso de la incubación que observamos en este búho podría ayudar a explicar la causa de su eclosión asincrónica. Palabras clave: asincronía de eclosión, fallo en eclosión, limitaciones energéticas, tamaño de puesta, viabilidad de huevos.