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Diapause is an endocrine-mediated metabolic and growth arrest state in response to unfavorable external environments. The nematode Caenorhabditis elegans can enter diapause/arrest during embryonic, larval, or adult stages when subjected to detrimental external environments. Larval stage 1 (L1) arrest happens when animals hatch without food. Previous work has shown that the insulin pathway plays a prominent role in regulating L1 arrest. However, the downstream signal molecular mechanisms and biomarkers are still missing. In this study, we showed that SaPosin-like Protein family member SPP-5 is significantly upregulated during L1 arrest, suggesting that it could act as an L1 arrest biomarker. Using RNA interference we demonstrated that spp-5  knockdown accelerated larval development, while the overexpression resulted in L1 arrest. Consistently, SPP-5 level was significantly up-regulated in the L1 arrest daf-2(e1370) mutants, and spp-5(RNAi) suppressed the daf-2(e1370) induced L1 arrest. These results suggest that SPP-5 can serve as an L1 arrest biomarker and promote the arrest probably via the insulin signaling pathway., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The diversity of insect eggs is astounding but still largely unexplained. Here, we apply phylogenetic analyses to 208 species of stick and leaf insects, coupled with physiological measurements of metabolic rate and water loss on five species, to evaluate classes of factors that may drive egg morphological diversification: life history constraints, material costs, mechanical constraints, and ecological circumstances. We show support for all three classes, but egg size is primarily influenced by female body size and strongly trades off with egg number. Females that lay relatively fewer but larger eggs, which develop more slowly because of disproportionately low metabolic rates, also tend to bury or glue them in specific locations instead of simply dropping them from the foliage (ancestral state). This form of parental care then directly favors relatively elongated eggs, which may facilitate their placement and allow easier passage through the oviducts in slender species. In addition, flightless females display a higher reproductive output and consequently lay relatively more and larger eggs compared with flight-capable females. Surprisingly, local climatic conditions had only weak effects on egg traits. Overall, our results suggest that morphological diversification of stick insect eggs is driven by a complex web of causal relationships among traits, with dominant effects of resource allocation and oviposition strategies, and of mechanical constraints., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Pronuclear transfer has been successfully used in human-assisted reproduction to suppress the adverse effects of a defective oocyte cytoplasm or to bypass an idiopathic developmental arrest. However, the effects of the initial parental genome remodelling in a defective cytoplasm on the subsequent development after pronucleus transfer have not been systematically studied. By performing pronuclear transfer in pre-replication and post-replication mouse embryos, we show that the timing of the procedure plays a critical role. Although apparently morphologically normal blastocysts were obtained in both pre- and post-replication pronuclear transfer groups, post-replication pronuclear transfer led to a decrease in developmental competence and profound changes in embryonic gene expression. By inhibiting the replication in the abnormal cytoplasm before pronuclear transfer into a healthy cytoplasm, the developmental potential of embryos could be largely restored. This shows that the conditions under which the first embryonic replication occurs strongly influence developmental potential. Although pronuclear transfer is the method of choice for mitigating the impact of a faulty oocyte cytoplasm on early development, our results show that the timing of this intervention should be restricted to the pre-replication phase., (© The Author(s) 2024. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Avian eggs develop outside of the female body, and therefore embryonic development is subject to multiple internal (physiological) and external (ecological) factors. Embryonic developmental rate has important consequences for survival. Within species, embryos that develop too quickly often experience deformities, disorders, or mortality, while embryos that develop slowly risk inviability and increase the time they are exposed to various sources of mortality in the nest. These contrasting forces may lead to interspecific variation in developmental rates. We investigated potential factors affecting embryonic heart rate (EHR), a proxy of development, across 14 passerine species in the field. More specifically, we investigated if nest predation risk, clutch size, seasonality, and egg volume influenced EHR. From previous research, we expected, and found, that EHR was positively associated with embryonic age and egg temperature. Species with greater nest predation risk had higher EHR, shorter incubation periods, and lower nest temperature variance. EHR increased as the season progressed and with egg volume, while EHR declined with clutch size. Bird species exhibit varying strategies to increase nestling and fledgling survival in response to predation risk, and these results suggest that variation in embryonic development may be related to species-specific differences in nest predation risk., Competing Interests: Authors declare no competing interests., (© 2024 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

The best-known effect of the intracellular bacterium Wolbachia is its mostly negative influence on the reproduction of the host. However, there is evidence of a positive influence of Wolbachia on the host's resistance to stress, pathogens, and viruses. Here, we analyzed the effects of two Wolbachia strains belonging to wMel and wMelCS genotypes on D. melanogaster traits, such as fertility, survival under acute heat stress, and developmental rate. We found that D. melanogaster lines under study differ significantly in the above-mentioned characteristics, both when the natural infection was preserved, and when it was eliminated. One of Wolbachia strains, wMel, did not affect any of the studied traits. Another strain, wMelPlus, had a significant effect on the development time. Moreover, this effect is observed not only in the line in which it was discovered but also in the one it was transferred to. When transferred to a new line, wMelPlus also caused changes in survival under heat stress. Thus, it could be concluded that Wolbachia - Drosophila interaction depends on the genotypes of both the host and the symbiont, but some Wolbachia effects could depend not on the genotypes, but on the fact of recent transfer of the symbiont.

The thermal sensitivity of early life stages can play a fundamental role in constraining species distributions. For egg-laying ectotherms, cool temperatures often extend development time and exacerbate developmental energy cost. Despite these costs, egg laying is still observed at high latitudes and altitudes. How embryos overcome the developmental constraints posed by cool climates is crucial knowledge for explaining the persistence of oviparous species in such environments and for understanding thermal adaptation more broadly. Here, we studied maternal investment and embryo energy use and allocation in wall lizards spanning altitudinal regions, as potential mechanisms that enable successful development to hatching in cool climates. Specifically, we compared population-level differences in (1) investment from mothers (egg mass, embryo retention and thyroid yolk hormone concentration), (2) embryo energy expenditure during development, and (3) embryo energy allocation from yolk towards tissue. We found evidence that energy expenditure was greater under cool compared with warm incubation temperatures. Females from relatively cool regions did not compensate for this energetic cost of development by producing larger eggs or increasing thyroid hormone concentration in yolk. Instead, embryos from the high-altitude region used less energy to complete development, that is, they developed faster without a concomitant increase in metabolic rate, compared with those from the low-altitude region. Embryos from high altitudes also allocated relatively more energy towards tissue production, hatching with lower residual yolk: tissue ratios than low-altitude region embryos. These results are consistent with local adaptation to cool climate and suggest that this is underpinned by mechanisms that regulate embryonic utilisation of yolk reserves and its allocation towards tissue, rather than shifts in maternal investment of yolk content or composition., (© 2023 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.)

Mitochondrial functions are intimately reliant on proteins and RNAs encoded in both the nuclear and mitochondrial genomes, leading to inter-genomic coevolution within taxa. Hybridization can break apart coevolved mitonuclear genotypes, resulting in decreased mitochondrial performance and reduced fitness. This hybrid breakdown is an important component of outbreeding depression and early-stage reproductive isolation. However, the mechanisms contributing to mitonuclear interactions remain poorly resolved. Here, we scored variation in developmental rate (a proxy for fitness) among reciprocal F 2 interpopulation hybrids of the intertidal copepod Tigriopus californicus and used RNA sequencing to assess differences in gene expression between fast- and slow-developing hybrids. In total, differences in expression associated with developmental rate were detected for 2925 genes, whereas only 135 genes were differentially expressed as a result of differences in mitochondrial genotype. Upregulated expression in fast developers was enriched for genes involved in chitin-based cuticle development, oxidation-reduction processes, hydrogen peroxide catabolic processes and mitochondrial respiratory chain complex I. In contrast, upregulation in slow developers was enriched for DNA replication, cell division, DNA damage and DNA repair. Eighty-four nuclear-encoded mitochondrial genes were differentially expressed between fast- and slow-developing copepods, including 12 subunits of the electron transport system (ETS) which all had higher expression in fast developers than in slow developers. Nine of these genes were subunits of ETS complex I. Our results emphasize the major roles that mitonuclear interactions within the ETS, particularly in complex I, play in hybrid breakdown, and resolve strong candidate genes for involvement in mitonuclear interactions., (© 2023 John Wiley & Sons Ltd.)

Early development is highly susceptible to environmental influence. We evaluated the role of larval visual environment on brain morphology plasticity in late larval and juvenile stages of Bombina orientalis, an anuran amphibian changing from an aquatic to a terrestrial habitat after metamorphosis. Manipulation of the visual environment was achieved by rearing larvae in normal and darkened water. The juveniles were exposed to normal lighting conditions after metamorphosis, allowing to assess if plastic effects persisted or emerged after metamorphosis. The darkness treatment accelerated development before slowing it down substantially, allowing controls to metamorphose earlier. Although larvae reared in darkened water had the same relative brain size as controls by the end of the larval period, juveniles that had been reared in darkened water as larvae had brains that were 14.4% smaller than juveniles that had been reared under control conditions. Conversely, relative telencephalon size was 6.7% larger in juveniles previously reared in darkened water compared with controls, again with no effect of darkened water seen by the end of the larval period. Unlike the latent effects seen on whole brain and telencephalon size, relative size of the optic tectum was significantly smaller in both larvae and juveniles exposed to the darkened water treatment. Therefore, the effects of visual restriction on juvenile brain form were a combination of latent (whole brain and telencephalon) and carry-over (optic tectum) developmental effects., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

Background: After embryonic development, Caenorhabditis elegans progress through for larval stages, each of them finishing with molting. The repetitive nature of C. elegans postembryonic development is considered an oscillatory process, a concept that has gained traction from regulation by a circadian clock gene homologue. Nevertheless, each larval stage has a defined duration and entails specific events. Since the overall duration of development is controlled by numerous factors, we have asked whether different rate-limiting interventions impact all stages equally., Results: We have measured the duration of each stage of development for over 2500 larvae, under varied environmental conditions known to alter overall developmental rate. We applied changes in temperature and in the quantity and quality of nutrition and analysed the effect of genetically reduced insulin signalling. Our results show that the distinct developmental stages respond differently to these perturbations. The changes in the duration of specific larval stages seem to depend on stage-specific events. Furthermore, our high-resolution measurement of the effect of temperature on the stage-specific duration of development has unveiled novel features of temperature dependence in C. elegans postembryonic development., Conclusions: Altogether, our results show that multiple factors fine tune developmental timing, impacting larval stages independently. Further understanding of the regulation of this process will allow modelling the mechanisms that control developmental timing., (© 2022. The Author(s).)

Objective: The aim of this study was to investigate whether blastocyst morphology and developmental rate are associated with euploidy and live birth rates (LBRs) in single euploid frozen-thawed embryo transfer (FET) cycles., Design: Retrospective cohort study., Methods: This study included 431 preimplantation genetic testing for aneuploidy (PGT-A) cycles followed by 393 FET cycles performed at our center from June 2017 to March 2021. All cycles were analyzed for euploidy based on blastocyst morphology (good, average and poor), developmental stage (day 5 and 6) and maternal age (< 35 and ≥ 35 years old). Multivariate logistic analysis models were used to identify the independent effects of conventional blastocyst morphology, developmental rate and morphological parameters (degree of blastocoele expansion, and grade of inner cell mass and trophectoderm (TE)) on LBRs., Results: In the group of women aged < 35 years, compared with poor-quality blastocysts, good-quality blastocysts (62.90% vs. 32.46%; odds ratio (OR) 3.163, 95% confidence interval (CI) 2.247-4.451; P < 0.001) and average-quality blastocysts (46.70% vs. 32.46%; OR 1.665, 95% CI 1.287-2.154; P < 0.001) had significantly higher euploidy rates. Additionally, day 5 blastocysts were associated with higher euploidy rates than day 6 blastocysts (49.28% vs. 35.02%; OR 1.506, 95% CI 1.191-1.903; P = 0.001). In the group of women aged ≥ 35 years, euploidy rates were also associated with blastocyst morphology, with 41.86%, 45.65% and 24.39% of good, average and poor-quality embryos, respectively, exhibiting euploidy. However, no relationship was seen between euploidy and blastocyst developmental rate. Multiple logistic regression analysis show that overall blastocyst morphology of euploid embryos was not associated with LBR, only embryos with A-grade TE had significantly higher LBRs than those with C-grade TE (62.71% vs. 45.40%; OR 2.189, 95% CI 1.166-4.109; P =0.015). Similarly, LBRs were significantly higher when day 5 blastocysts were transferred than when day 6 blastocysts were transferred (57.75% vs. 41.67%; OR 2.132, 95% CI 1.370-3.318; P = 0.001)., Conclusion: Poor-quality embryos have reduced rates of euploidy. However, blastocyst developmental rate only significantly associates with euploidy rates in women aged younger than 35. Furthermore, only TE grade and blastocyst developmental rate are significantly associated with LBRs following FET cycles., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Li, Guan, Ren, Zhang, Du, Kong, Zhang and Lou.)

Developmental time of the predatory mite Neoseiulus cucumeris (Oudemans) fed on cattail and almond pollen was determined under laboratory conditions at nine constant temperatures: 10, 15, 20, 25, 27, 30, 32, 35 and 38°C. No development was observed at 10°C. The lower temperature threshold (T0) was estimated to be 10. 97 and 10. 29°C for the almond and cattail pollen, respectively, using the Ikemoto linear model. Thermal constant (K) for pre-adult development of N. cucumeris was 112.8 and 123.5 DD fed on almond and cattail pollen, respectively, using the Ikemoto linear model. The interaction between diet and temperature had a significant effect on the developmental rate of N. cucumeris. The nonlinear Pradhan-Taylor, Janisch/Kontodimas, Briere-1, and Janisch/Rochat models best described the developmental rate of pre-adult stages of N. cucumeris. The estimated Tfast by Pradhan-Taylor model was 31.9 and 33.9°C when fed on almond and cattail pollen, respectively, which was similar to the observed shortest developmental time at 32°C. Our results revealed that N. cucumeris could develop over a wide temperature range (15-35°C), which is a desirable characteristic for a biocontrol agent in biological control programs., (© The Author(s) 2021. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Modeling the impact of temperature on each life stage of a beetle population represents a continuing challenge. This study evaluates the effects of five temperature treatments (20, 23, 26, 29 and 32 °C) on population abundance and timing of a colony of ambrosia beetles Xyleborus affinis reared under laboratory conditions and use this data to develop demographic and phenological models. Abundances at each life stage (eggs, larvae, pupae and adult) were examined through periodic destructive sampling; given that it was not possible to track individuals. To assess the effects of temperature on oviposition, development and survival rates we developed a novel estimation strategy based on cohorts, which does not require individual developmental data. Since oviposition was entirely unwitnessed, we assessed competing empirical ovipositional models. Rates of development were computed using a modal rate curve for each life stage, and rates were projected to cohorts in life stages assuming log-normal developmental variance. Temperature-driven survival rates were assumed to be logistic with a quadratic exponent to capture modal temperature dependence. Parameters were estimated simultaneously using minimum negative log posterior likelihood, assuming Poisson distribution of observations and using priors to inform unobserved developmental rates and enforce mechanistic constraints on oviposition models. A parabolic function best described oviposition rate. Optimal developmental temperatures were 30.5 °C, 29 °C and 27.5 °C, with maximum developmental rates of 0.26/day, 0.12/day and 0.23/day for eggs, larvae and pupae, respectively. The survival rates in the range 20-29 °C were equal to 1 in the eggs-to-larvae transition, from 0.72 to 0.35 in larvae-to-pupae transition, and from 0.2 to 0.89 in pupae-to-adults transition. This procedure effectively characterized the direct thermal effects on development and survival of each life stage in the X. affinis under laboratory conditions and would be suitable for estimating temperature dependence for other species in which individual observations are not possible., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The postmortem interval (PMI) estimation, in cases where the body was discovered in an advanced stage of decomposition, is predominantly based on entomological evidence. However, very few forensically important species are sufficiently known in detail to allow a practical application. One of them is the carrion beetle, Necrophila (Calosilpha) brunnicollis (Kraatz, 1877). Its development from egg to adulthood was studied under a range of ecologically relevant constant temperatures to find parameters of thermal summation models. Developmental sexual dimorphism and the presence of developmental rate isomorphy were investigated. Herein we present the lower developmental thresholds and sum of effective temperatures for all developmental stages of N. brunnicollis (egg, first-third larval instar, postfeeding stage, and pupae). We did not find any evidence of developmental sexual dimorphism nor was the presence of developmental rate isomorphy confirmed. Our results present the first thermal summation model of the East Asian carrion beetle that can be used for the PMI estimation., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: It is demonstrated that optimal preincubation time improves oocyte quality, fertilization potential and developmental rate. This study aimed to evaluate the effect of preincubation time in the simple and myo-inositol supplemented medium on the oocyte quality regarding oxidative stress and mitochondrial alteration., Methods: Cumulus oocyte complexes (COCs) retrieved from superovulated NMRI mice were divided in groups of 0, 4 and 8 hr preincubation time in the simple and 20 mmol/L myo-inositol supplemented media. Intracellular reactive oxygen species (H 2 O 2 ), glutathione (GSH), mitochondrial membrane potential (MMP), ATP content, and mitochondrial amount were measured and analyzed in experimental groups. One-way ANOVA and Kruskal-Wallis were respectively used for parametric and nonparametric variables. Statistical significance was defined as p<0.05., Results: In comparison to control group, variables including ROS, GSH, mitochondrial amount, fertilization and developmental rates were significantly changed after 4 hr of preincubation in the simple medium, while MMP decreased following 8 hr of preincubation in the simple medium (p˂0.001). Preincubation of oocytes up to 8 hr in the simple medium could not decrease ATP content. For both 4 and 8 hr preincubation times, myo-inositole could decrease H 2 O 2 and increase GSH and MMP levels and consequently could improve fertilization rate compared to oocytes preincubated in the simple culture., Conclusion: It seems that 4 hr or more preincubation time can decrease the oocyte quality and lead to reduced oocyte fertilization and developmental potential. Howevere, myo-inositol may prevent oocyte quality reduction and improve fertilization potential in comparision to the equivalent simple groups., Competing Interests: Conflict of Interest There is no conflict of interest in this paper., (Copyright© 2020, Avicenna Research Institute.)

The purpose of this investigation was to study the effect of acute γ-irradiation of parent adults on the endoreduplication of giant chromosomes in F 1 generation of Drosophila melanogaster Meig. A wild-type Oregon-R strain was used as the material. Virgin females and males of Drosophila adults at the age of 3 days were irradiated with doses of 8, 16 and 25 Gy. Giant chromosomes were studied by cytomorphometry on squashed preparations of Drosophila salivary glands stained with acetoorsein. The preparations were obtained at late third instar larvae. The mean values of the polyteny degree of chromosomes (PDC) in males increased after 8 Gy by 10.6%, after 25 Gy by 7.4%, and did not change after the dose of 16 Gy. In females, the PDC did not differ from the control irrespective of the irradiation dose. An increase in endoreduplication was also evidenced by the accelerated development of offsprings of both sexes after irradiation of parents with 25 Gy, and in males also at a dose of 16 Gy. The statistical impact of power of radiation on polyteny was 26.8%, while the impact of sex was 4.9%. The impact of power of radiation on the developmental rate of offspring was 4.4% in males and 7.5% in females. The enhancement of endoreduplication is considered as a consequence of increasing selection pressure after irradiation. The possible involvement of epigenetic effects in the effect of ionizing radiation on endoreduplication is discussed.

In response to nutrient limitation, many animals, including Caenorhabditis elegans, slow or arrest their development. This process requires mechanisms that sense essential nutrients and induce appropriate responses. When faced with nutrient limitation, C. elegans can induce both short and long-term survival strategies, including larval arrest, decreased developmental rate, and dauer formation. To select the most advantageous strategy, information from many different sensors must be integrated into signaling pathways, including target of rapamycin (TOR) and insulin, that regulate developmental progression. Here, how nutrient information is sensed and integrated into developmental decisions that determine developmental rate and progression in C. elegans is reviewed., (© 2020 WILEY Periodicals, Inc.)

Amphibians are highly vulnerable and diverse vertebrates for which we still have modest genomic resources. Amphibian larvae are key components of continental wetlands, where they have strong influences on energy fluxes, nutrient cycling, and community structure. Amphibian larvae are highly sensitive to environmental conditions and can often alter their physiology, behavior and even morphology in response to the local conditions experienced, although we still know relatively little about the transcriptomic changes that enable such plasticity. Here we contribute the larval transcriptomes of two spadefoot toad species with divergent developmental rates and degree of developmental plasticity in response to pond drying., (Copyright © 2019 Liedtke et al.)

Complete development of Orius majusculus Reuter (Heteroptera: Anthocoridae) at nine constant temperatures, between 12 and 34°C, was evaluated under laboratory conditions. The maximum developmental period of 90.75 d occurred at 12°C, whereas the minimum of 11.34 d occurred at 30°C. From 30 to 34°C, the developmental period increased to 13.50 d. Between 21 and 33°C the survival rate was more than 80%. The optimal temperature when considering developmental rate and survival was between 24 and 30°C. At constant temperatures, four models were developed, one of which was linear and three nonlinear (Logan type III, Lactin, and Brière). All models were validated under field conditions and diel temperature variations. The values of the adjusted determination coefficients of the linear (>0.77) and nonlinear models (>0.93) were high. The thermal requirement for complete development, from egg to adult, was 284.5 degree-days (DD). In all nonlinear models, elevated levels of accuracy (≥90.31%) in field validation were also obtained, especially in the Brière model. With the results obtained herein, the optimization of O. majusculus mass rearing, its ideal use, and field management in biological control strategies can be improved., (© The Author(s) 2018. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

This retrospective cohort analysis compared the developmental competence of cryopreserved day-4 and 5 blastocysts, and investigated the effect of progesterone administration duration on the success of artificial frozen embryo transfers. Between October 2015 and March 2016, 868 intracytoplasmic sperm injection blastocyst cryo-all cycles were carried out, with 586 subsequently undergoing frozen embryo transfer. Of these, 243 were day-5 single blastocyst transfers (SBT) and 152 were day-4 SBT. Day-4 blastocysts were transferred on day-5 progesterone (day-4 group) and day-5 blastocysts were transferred on day-5 (short-protocol day-5 sub-group, n = 104) or day-6 (standard-protocol day-5 sub-group, n = 139) progesterone. Although more blastocysts were transferred in the standard-protocol day-5 sub-group (P = 0.009), pregnancy, clinical pregnancy and live birth rates were similar to those of the day-4 group, but were significantly lower in the short-protocol day-5 sub-group (P = 0.004, P = 0.008 and P = 0.02 respectively). For optimal outcomes, day-4 blastulating embryos should be prioritized for transfer on day 5 of progesterone and for day-5 blastocysts, transfer should be delayed by 1 day. The retrospective analysis and lack of adjustment for all known confounding variables limit the study., (Copyright © 2018 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.)

The objective of this study was to classify spindle and first polar body (PB1) chromosome images in ovulated mouse oocytes over time to predict the developmental competence of metaphase II (MII) oocytes. Oocytes were collected at 12, 15, 20, and 25 h after human chorionic gonadotropin (hCG) injection, and stained for spindle tubulin, chromosomes, and PB1 chromosomes. MII spindle morphology was classified as tapered type or barrel type and PB1 chromosomes were categorized as aggregated, separated, dot, or collapsed. To determine whether differences in spindle and PB1 images in MII oocytes are associated with fertilization success, we performed in vitro fertilization (IVF) at various times after hCG injection. Barrel-type spindles and aggregate-type PB1 were dominant at 12 h after hCG injection. Oocyte spindles collected 1 h after injection were tapered, and PB1 chromosomes were separated. At 20 and 25 h after treatment, spindle and PB1 images were classified as collapsed. The rate of development to 2-cell embryos after IVF did not differ between the 12 h and 15 h treatments; however, it was significantly lower for the 25 h treatment than for other treatments. The rates of development to blastocysts at 12, 15, 20, and 25 h after hCG injection were 61, 46, 42, and 9%, respectively. MII oocytes with barrel-type spindles and aggregate-type PB1 had high rates of fertilization and blastocyst development, and spindle and PB1 characteristics were correlated with the outcomes of IVF and embryo culture. These results suggested that images of spindles combined with those of PB1 chromosomes enable the prediction of oocytic and/or embryonic quality.

One of the leitmotifs of the ecophysiological research on ectotherms is the variation and evolution of thermal reaction norms for biological rates. This long-standing issue is crucial both for our understanding of life-history diversification and for predicting the phenology of economically important species. A number of properties of the organism's thermal phenotype have been identified as potential constraints on the evolution of the rate-temperature relationship. This comparative study addresses several such constraints by testing whether the actual interspecific variation of thermal reaction norms across nearly hundred leaf beetle species agrees with the expected patterns. The results show that developmental rate and its temperature-dependent parameters are similar in closely related species and that the variation pattern depends on the taxonomic scale, the thermal reaction norms being mostly parallel for the representatives of distant subclades but intersecting more often farther down the phylogenetic tree. The parallel shift disagrees with the putative ubiquity of a positive slope-threshold relationship, whereby thermal reaction norms should normally intersect, and even more contradicts with the common-intersection hypothesis. The ability to develop in cooler conditions is not traded off at higher temperatures, which is an exception to the "warmer is better" principle. A comparison of high- and low-quality data indicates that some of these discrepancies with earlier findings may stem from a likely presence of noise in previous analyses, which may have affected the variation patterns observed. Overall, the failure to support the universality of the predicted patterns suggests that the evolution of thermal reaction norms in leaf beetles has largely overcome the hypothesized constraints.

For optimal application of Nesidiocoris tenuis as a biological control agent, adequate field management and programmed mass rearing are essential. Mathematical models are useful tools for predicting the temperature-dependent developmental rate of the predator. In this study, the linear model and nonlinear models Logan type III, Lactin and Brière were estimated at constant temperatures and validated at alternating temperatures and under field conditions. N. tenuis achieved complete development from egg to adult at constant temperatures between 15 and 35°C with high survivorship (>80%) in the range 18-32°C. The total developmental time decreased from a maximum at 15°C (76.74 d) to a minimum at 33°C (12.67 d) and after that, increased to 35°C (13.98 d). Linear and nonlinear developmental models all had high accuracy (R a 2 >0.86). The maximum developmental rate was obtained between 31.9°C (Logan type III and Brière model for N1) and 35.6°C (for the egg stage in the Brière model). Optimal survival and the highest developmental rate fell within the range 27-30°C. The field validation revealed that the Logan type III and Lactin models offered the best predictions (95.0 and 94.5%, respectively). The data obtained on developmental time and mortality at different temperatures are useful for mass rearing this predator, and the developmental models are valuable for using N. tenuis as a biological control agent.

We investigated the effects of seven temperatures (22.5, 25.0, 27.5, 30.0, 32.5, 35.0, and 37.5°C) and four relative humidities (43, 55, 63, and 75%) on population growth and development of the psocid Liposcelis fusciceps Badonnel (Psocoptera: Liposcelididae). Results demonstrated that L. fusciceps did not survive at 43% RH, at all temperatures tested. At 55% RH, L. fusciceps did not survive at the highest three temperatures and no psocids survived at 37.5°C and 63% RH. The highest population growth was recorded at 30.0°C and 75% RH where populations increased 16-fold from an initial population of five females. L. fusciceps males have two to four nymphal instars, and the percentages of males with two, three, and four instars were 28, 70, and 2%, respectively. Female L. fusciceps have two to five instars, and the percentages of females with two, three, four, and five instars were 2, 33, 63, and 2%, respectively. The total developmental time for males was shorter than females. We developed temperature-dependent development equations for male and female eggs, individual nymphal, combined nymphal, and combined immature stages. Based on 30-d population growth, L. fusciceps can survive and multiply at a relative humidity of 55% at 22.5-30.0°C, but does better at 27.5-32.5°C and a higher relative humidity of 75%. Relative humidities of ≤ 63% and temperatures of ≥ 32.5°C are detrimental to L. fusciceps. These data provide a better understanding of L. fusciceps population dynamics and can be used to develop effective management strategies for this psocid., (© The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

There have been no studies analyzing the effect of large aggregates of tubular smooth endoplasmic reticulum (aSERT) after conventional in vitro fertilization (cIVF). The aim of this study was to investigate whether aSERT can be identified after cIVF and the association between the embryological outcomes of oocytes in cycles with aSERT. This is a retrospective study examining embryological data from cIVF cycles showing the presence of aSERT in oocytes 5-6 h after cIVF. To evaluate embryo quality, cIVF cycles with at least one aSERT-metaphase II (MII) oocyte observed (cycles with aSERT) were compared to cycles with normal-MII oocytes (control cycles). Among the 4098 MII oocytes observed in 579 cycles, aSERT was detected in 100 MII oocytes in 51 cycles (8.8%). The fertilization rate, the rate of embryo development on day 3 and day 5-6 did not significantly differ between cycles with aSERT and control group. However, aSERT-MII oocytes had lower rates for both blastocysts and good quality blastocysts (p < 0.05). aSERT can be detected in the cytoplasm by removing the cumulus cell 5 h after cIVF. However, aSERT-MII oocytes do not affect other normal-MII oocytes in cycles with aSERT.

Background: Oocyte cryopreservation is an important part of modern fertility treatment. The effect of vitrification on the fertilization and developmental rates of embryo is still a matter of debate., Objectives: This study aimed to investigate the effect of vitrification on the success of mouse oocyte maturation, fertilization, and preimplantation development in vitro., Materials and Methods: In this experimental study, a total of 200 germinal vesicle (GV) and 200 metaphase II (MII) oocytes were obtained from ovaries and fallopian tubes of NMRI mice, respectively and divided into two control and experimental (vitrified) groups. Oocytes in the experimental group were vitrified by Cryotop using vitrification medium (Origio, Denmark) and kept in liquid nitrogen for one month. Then, they were cultured in maturation medium for 24 hours. In vitro maturated metaphase 2 (IVM-MII) and ovulated metaphase 2 (OV-MII) oocytes were inseminated and the fertilized embryos assessed until the hatching blastocyst stage. Outcomes were assessed for statistical significance by Chi-square test using SPSS software., Results: Vitrification caused a significant reduction in the maturation rate of oocytes. Of those that matured, the fertilization rate of vitrified IVM-MII (44.1%) and OV-MII oocytes (50%) was not significantly different from each other but both were significantly lower than the control group (P < 0.05). There was no significant difference in developmental rates of both vitrified groups and the control group., Conclusions: The present study showed that vitrification using Cryotop and freezing medium can damage oocytes by reducing the maturation and fertilization rates in both developmental stages.

Few teleost fishes incubate embryos out of water, but the oxygen-rich terrestrial environment could provide advantages for early growth and development. We tested the hypothesis that embryonic oxygen uptake is limited in aquatic environments relative to air using the self-fertilizing amphibious mangrove rivulus, Kryptolebias marmoratus, which typically inhabits hypoxic, water-filled crab burrows. We found that adult mangrove rivulus released twice as many embryos in terrestrial versus aquatic environments and that air-reared embryos had accelerated developmental rates. Surprisingly, air-reared embryos consumed 44% less oxygen and possessed larger yolk reserves, but attained the same mass, length and chorion thickness. Water-reared embryos moved their opercula ∼2.5 more times per minute compared with air-reared embryos at 7 days post-release, which probably contributed to the higher rates of oxygen uptake and yolk utilization we observed. Genetically identical air- and water-reared embryos from the same parent were raised to maturity, but the embryonic environment did not affect growth, reproduction or emersion ability in adults. Therefore, although aspects of early development were plastic, these early differences were not sustained into adulthood. Kryptolebias marmoratus embryos hatched out of water when exposed to aerial hypoxia. We conclude that exposure to a terrestrial environment reduces the energetic costs of development partly by reducing the necessity of embryonic movements to dispel stagnant boundary layers. Terrestrial incubation of young would be especially beneficial to amphibious fishes that occupy aquatic habitats of poor water quality, assuming low terrestrial predation and desiccation risks., (© 2015. Published by The Company of Biologists Ltd.)

Aedes albopictus (Skuse) is an invasive mosquito species that has spread to many countries in temperate regions bordering the Mediterranean basin, where it is becoming a major public health concern. A good knowledge of the thermal features of the most productive breeding sites for Ae. albopictus is crucial for a better estimation of the mosquitoes' life cycle and developmental rates. In this article, we address the problem of predicting air temperature in three microhabitats common in urban and suburban areas and the air and water temperature inside an ordinary catch basin, which is considered the most productive breeding site for Ae. albopictus in Italy. Temperature differences were statistically proven between the three microhabitats and between the catch basin external and internal temperature. The impacts on the developmental rates for each life stage of Ae. albopictus were tested through a parametric function of the temperature, and the aquatic stages resulted as being the most affected using the specific temperature inside a typical catch basin instead of a generic air temperature. The impact of snow cover on the catch basin internal temperature, and consequently on the mortality of diapausing eggs, was also evaluated. These data can be useful to improve epidemiological models for a better prediction of Ae. albopictus seasonal and population dynamics in central-northern Italian urban areas., (© The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

We present a general and flexible mathematical model (called SANDY) that can be used to describe many biological phenomena, including the phenology of arthropods. In this paper, we demonstrate how the model can be fitted to vital rates (i.e., rates associated with development, survival, hatching, and oviposition) of the two-spotted spider mite (Tetranychus urticae (Koch)) exposed to different constant temperatures ranging from 15°C to 37.5°C. SANDY was incorporated into an age-, stage- and sex-structured dynamic model, which was fitted to cohort life-tables of T. urticae conducted at five constant temperatures (15, 20, 25, 30, and 35°C). Age- and temperature-dependent vital rates for the three main stages (eggs, immatures, and adults) constituting the life-cycle of mites were adequately described by the SANDY model. The modeling approach allows for simulating the growth of a population in a variable environment. We compared the predicted net reproductive rate (R0) and intrinsic rate of natural increase (rm) at fluctuating temperatures with empirical values obtained from life-table experiments conducted at temperatures that changed with a daily amplitude (±0, ±3, ±6, ±9, and ±12°C) around an average of 22°C. Results show that R0 decreases with increasing amplitude, while rm is more robust to variable temperatures. An advantage of SANDY is that the same simple mathematical expression can be applied to describe all the vital rates. Besides, the approach is not confined to modeling the influence of a single factor on population growth but allows for incorporating the combined effect of several limiting factors, provided that the combined effect of the factors is multiplicative., (© The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The larvae of Orthopygia glaucinalis (L.) (Lepidoptera: Pyralidae) are used to produce insect tea in Guizhou, China. We investigated the development and survival of O. glaucinalis reared on dried leaves of Platycarya strobilacea under laboratory conditions at 19, 22, 25, 28, 31, 34, and 37°C. The duration of development from egg deposition to adult emergence decreased significantly with increasing temperature from 19 to 31°C, whereas the duration of egg and overall development significantly increased at 34°C. Based on the extreme-value distribution function, the optimal temperature for survival of overall development was 24.89°C, and the larval stage was most susceptible to temperature extremes. The common linear model and the Ikemoto and Takai linear model were used to determine the relationship between temperature and the developmental rate, and estimated the low-temperature threshold (11.44 and 11.62°C, respectively) and the threshold constant (1220.70 and 1203.58 degree-days, respectively) of O. glaucinalis. Nonlinear models were used to assess in fitting the experiment data and to estimate the high temperature thresholds (34.00 to 39.08°C) and optimal temperatures (31.61 to 33.45°C). An intrinsic optimal temperature of 24.18°C was estimated for overall development using the Sharpe-Schoolfield-Ikemoto (SSI) model. Model-averaged parameter estimates and the unconditional standard error were also estimated for the temperature thresholds. Based on the biological parameters and model selection, we concluded that common linear, Lactin-1, and SSI models performed better for predicting the temperature-dependent development of O. glaucinalis. Our findings enable breeders to optimize the developmental rate of O. glaucinalis and improve the yield of insect tea., (© The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Climate-change models predict that tropical ocean temperatures will increase by 2-3°C this century and affect plankton communities that are food for marine fish larvae. Both temperature and food supply can influence development time, growth, and metabolism of marine fishes, particularly during larval stages. However, little is known of the relative importance and potential interacting effects of ocean warming and changes to food supply on the performance of larval fishes. We tested this for larvae of the coral reef anemonefish, Amphiprion percula, in an orthogonal experiment comprising three temperatures and three feeding schedules. Temperatures were chosen to represent present-day summer averages (29.2°C) and end-of-century climate change projections of +1.5°C (30.7°C) and +3°C (32.2°C). Feeding schedules were chosen to represent a reduction in access to food (fed daily, every 2 days, or every 3 days). Overall, larvae took longer to settle at higher temperatures and with less frequent feeding, and there was a significant interaction between these factors. Time to metamorphosis was fastest in the 30.7(o)C and high food availability treatment (10.5 ± 0.2 days) and slowest in the 32.2(o)C and low food availability treatment (15.6 ± 0.5 days; i.e. 50% faster). Fish from the lower feeding regimens had a lower body condition and decreased survivorship to metamorphosis. Routine oxygen consumption rates were highest for fish raised at 32.2°C and fed every third day (162 ± 107 mg O2  kg(-1) h(-1)) and lowest for fish raised at 29.2°C and fed daily (122 ± 101 mg O2 kg(-1) h(-1); i.e. 35% lower). The elevated routine oxygen consumption rate, and therefore greater energy use at higher temperatures, may leave less energy available for growth and development, resulting in the longer time to metamorphosis. Overall, these results suggest that larval fishes will be severely impacted by climate-change scenarios that predict both elevated temperatures and reduced food supply.

Amphibian larvae vary tremendously in size at metamorphosis and length of larval period. We raised pond-dwelling four-toed salamander (Hemidactylium scutatum) larvae to test two models that predict a larva's age and size at metamorphosis. The Wilbur-Collins model proposes that the developmental rate of a larva responds to changes in growth rate in an adaptive manner throughout the larval period, and that metamorphosis can be initiated after a minimum size has been reached. The Leips-Travis or fixed-rate model states that developmental rate is set early in the larval period, perhaps by early growth rate or food availability and their positive correlation with developmental rate, and that changes in growth rate during the larval period affect size at metamorphosis, but have no effect on the age of an individual at metamorphosis. A modified version of the Wilbur-Collins model suggests that a larva's developmental rate becomes fixed about two-thirds of the way through the larval period, with changes in growth rate after that point only affecting size at metamorphosis. Larvae were raised on eight different feeding regimes which created two constant and six variable growth histories. Growth history did significantly affect size at metamorphosis. However, an a posteriori statistical test revealed a group of seven and an overlapping group of six treatments with indistinguishable lengths of larval period, indicating a general picture of a fixed developmental rate regardless of growth history. This result is unique among similar studies on invertebrates, fish, and frogs. There was no association between early growth or food level and development rates. Neither the Wilbur-Collins nor the Leips-Travis fixed-rate models were supported. The invariable developmental rate of Hemidactylium and recent osteological evidence from the literature suggest that larvae begin the process of metamorphosis as soon as they hatch, probably a trait selected for by strong predation pressure in the aquatic environment. A variety of different approaches (ecological, developmental, phylogenetic) are necessary to fully evaluate the adaptive nature of the timing of transitions between life cycle stages.

Age and size at metamorphosis are two important fitness components in species with complex life cycles. In anurans, metamorphic traits show remarkable phenotypic plasticity, especially in response to changes in growth conditions. It is also possible that the perception of risk directly determines changes in larval period and the size of metamorphs. This study examines how the perception of predation risk affects the timing of and size at metamorphosis in common frogs (Rana temporaria). I raised tadpoles at two risk levels (fish-conditioned water or unconditioned water) crossed with the availability or lack of food at night (all tadpoles had food available in the day). Tadpoles reacted to chemical cues from predatory fish by decreasing activity. A novel behavioural result was a predation×food interaction effect on refuge use, which also accounted for most of the predator main effect: predation risk only caused increased refuge use in the night-starved treatment. Despite these behavioural modifications, the perception of predation risk did not affect growth rate and mass at metamorphosis in a simple way: the effects of food regime on growth and size at metamorphosis were dependent on the level of predation risk as revealed by significant predation×food interaction effects. Tadpoles who had food withheld at night metamorphosed at the smallest size, suggesting a negative relationship between size at metamorphosis and refuge use. Tadpoles raised in fish-conditioned water had longer larval periods than those in unconditioned water, but these differences were significant only if food was available at night. These results conflict with the hypotheses that tadpoles should reduce their larval period or growth rates (and hence metamorphose at a smaller size) as the risk of predation increases. In contrast to predation risk, food availability strongly affected the length of the larval period: night-starved tadpoles metamorphosed relatively early with or without fish stimulus. Thus, early metamorphosis resulted from periods of low food availability, but not from a heightened "perceived risk" of predation. This example counters the hypothesis of acceleration of the developmental rate (which shortens the time to metamorphosis) as a mechanism to escape a risky environment.

The role of development in the evolution of postponed senescence is poorly understood despite the existence of a major gerontological theory connecting developmental rate to aging. We investigate the role of developmental rate in the laboratory evolution of aging using 24 distinct populations of Drosophila melanogaster. We have found a significant difference between the larval developmental rates of our Drosophila stocks selected for early (B) and late-life (O) fertility. This larval developmental time difference of approximately 12% (O > B) has been stable for at least 5 yr, occurs under a wide variety of rearing conditions, responds to reverse selection, and is shown for two other O-like selection treatments. Emerging adults from lines with different larval developmental rates show no significant differences in weight at emergence, thorax length, or starvation resistance. Long-developing lines (O, CO, and CB) have greater survivorship from egg to pupa and from pupa to adult, with and without strong larval competition. Crosses between slower developing populations, and a variety of other lines of evidence, indicate that neither mutation accumulation nor inbreeding depression are responsible for the extended development of our late-reproduced selection treatments. These results stand in striking contrast to other recent studies. We argue that inbreeding depression and inadvertent direct selection in other laboratories' culture regimes explain their results. We demonstrate antagonistic pleiotropy between developmental rate and preadult viability. The absence of any correlation between longevity and developmental time in our stocks refutes the developmental theory of aging., (© 1994 The Society for the Study of Evolution.)

In some reptiles, gravid females bask more, and/or maintain higher body temperatures than do males or non-gravid females. This phenomenon is usually explained in terms of the female or her offspring benefitting from accelerated embryogenesis and early birth, but the effect of increased basking on gestation period has not been studied. In a laboratory experiment, gestation periods of gravid female skinks (Eulamprus tympanum) decreased with the duration of access to radiant heat. Embryonic development was more rapid in the laboratory than in the field, and there were no apparent adverse effects of this accelerated gestation on females or offspring. Number and mass of offspring, survival rates of embryos, relative clutch mass and female mass before and after parturition were not influenced by the decrease in gestation period caused by increased basking. Females selected similar temperatures in the laboratory and field (32° C), despite the availability of higher temperatures in the laboratory. Thus, gestation in the laboratory was accelerated by spending longer periods at usual basking temperatures, rather than by selecting higher temperatures. In the field, mean and modal body temperatures of active animals were similar in gravid females, males and non-gravid females, but gravid females appear to bask more of the time, even in cloudy weather when other members of the population do not bask. Hence, an apparent similarity in thermal regimes of gravid and non-gravid animals may mask significant underlying differences in thermoregulatory strategies.

Developmental rate and adult weight were studied at constant temperatures from 9.8 to 27.9°C for 18 clones from each of five populations of the pea aphid, Acyrthosiphon pisum (Harris), from locations between 39 and 53°N latitude in central North America. The response of developmental rate to temperature for each clone was accurately described by a three parameter non-linear equation. Adult weight usually decreased with increasing rearing temperature, but the shape of the response to temperature varied among clones. Variation in the developmental parameters was greater among clones within populations than among populations. No consistent trends were observed in the developmental parameters or adult weights either with latitude or the long term average temperatures at the locations. We conclude that previously reported geographic variation in the developmental threshold of this species, which was attributed to local adaptation, occurred either because the clones tested were not representative of the populations or because rearing methods differed among studies. The results are discussed in relation to the hypothesis that life history traits which are temperature sensitive are adapted to local thermal environments.