Juvenile Phase Research Articles

Modeling transport and feeding of juvenile Kemp's ridley sea turtles on the West Florida shelf

Survivorship during the juvenile oceanic phase likely acts as a bottleneck on the growth of sea turtle populations, and starvation mortality through this period is one potential factor influencing year class strength. We combined a simulation of juvenile Kemp's ridley (Lepidochelys kempii) sea turtle dispersal based on an ocean circulation model with an Atlantis ecosystem model to examine the spatial overlap of young sea turtles with their prey resources. We were particularly interested in whether ocean currents facilitated the movement of juveniles from western Gulf nesting beaches to areas in the eastern Gulf along the West Florida Shelf (WFS) with adequate food availability. We found that strong frontal gradients on the WFS may increase the potential for juveniles to remain offshore in areas of high per capita prey availability, allowing for more feeding opportunities during critical early life stages. Additionally, we found that multiple climatological indices are related to Gulf-wide patterns of juvenile dispersal, potentially via effects on the Loop Current. Findings from this study hold implications for continued population viability of protected sea turtle populations in the Gulf of Mexico, as well as other species with early life stages that disperse via ocean currents such as commercially important fishes.

Genotypic influence in the juvenile to adult transition in olive seedlings.

Olive breeding is a long process and any improvement in shortening the juvenile phase is highly desirable. In the present study, the effect of olive tree parents in different agronomic characteristics have been evaluated during four years in 520 olive genotypes generated from three different crosses in three different experimental fields, all located in Andalusia region, Spain. The crosses evaluated are 'Arbosana' x 'Sikitita' and its reciprocal, whose parents are characterized by being early bearers; and 'Frantoio' free pollinated, whose mother variety is characterized by having a long unproductive period. We studied plant height, distance and time to the first flowering, plant vigor and percentage of olive oil in the fruits. The findings reveal that progeny from 'Arbosana' and 'Sikitita' crosses, irrespective of the direction of the cross, exhibited a lower distance to flower, early bearing, reduced vigor and a lower percentage of olive oil in fruit compared to 'Frantoio' seedlings obtained from free pollination. Furthermore, no discernible differences were observed in the evaluated characteristics when comparing reciprocal crosses across the three fields in the four-years assessment period. Therefore, these results highlight the significance of planting height in reducing the evaluation period required in an olive breeding program and support the hypothesis that there is no maternal effect in the inheritance of the evaluated agronomic characteristics in olive trees.

Reduction of the mangosteen tree (Garcinia mangostana L.) production cycle: effect of soil type and fertilisers

BackgroundShortening the vegetative cycle of slow-growing crops is a significant challenge for breeders, agronomists, and growers. This reduction is particularly crucial for the mangosteen (Garcinia mangostana) as it would make it easier for farmers to adopt this crop. The mangosteen tree is notoriously slow-growing, taking between 8 and 15 years to produce its first fruits. The plant's slow growth and late fruiting pose a significant obstacle to its adoption and spread in rural areas. In Côte d'Ivoire, these constraints have limited its cultivation to small farms owned by a few producers. However, it could be an alternative for diversifying agricultural income and contributing to poverty reduction in rural areas. This study aims to evaluate the effects of soil type and fertiliser on the agronomic parameters of mangosteen tree growth. The goal is to contribute to shortening its vegetative phase.ResultsThe study results indicate that soil type and fertiliser have a significant effect on mangosteen growth parameters. Evaluating the agronomic performance of mangosteen, it was found that lowland soil promotes better plant growth. Growth rate and height growth were found to be significantly influenced (p = 0.03). After 36 months of monitoring, the growth rates for mangosteen trees grown on lowland soil were 53.08 ± 7.30%, while those grown on forest soil were 41.51 ± 13.43%. Additionally, the use of foliar and granular N-P-K fertilisers resulted in earlier fruiting, starting from the 5th year of cultivation.ConclusionsThe results showed that fertilisers play a crucial role in managing and shortening the juvenile phase of the mangosteen tree. Foliar and NPK fertilisers performed exceptionally well, resulting in earlier fruiting of mangosteen trees, starting from the 5th year of cultivation.

Rust resistance of wheat and triticale samples in different plant growing stages

Aim. To study resistance to leaf, yellow and stem rusts of winter and spring wheat and winter triticale samples from the collection of the N. I. Vavilov All‐Russian Institute of Plant Genetic Resources (VIR) and breeding centres of southern Russia in different phases of ontogenesis and to identify new sources with group resistance. Material and Methods. The resistance of 158 wheat and triticale samples from the VIR collection and southern breeding centres to populations of leaf, stem and yellow rusts in different plant growth stages was analysed. In the juvenile phase the samples studied were inoculated with populations of rust fungi in climate chambers of the Federal Research Centre of Biological Plant Protection and the type of plant reaction to lesions was noted. In field conditions the samples were evaluated according to the CIMMYT scale on an artificial infectious background. Results. In the adult plant stage under field conditions 79 wheat and triticale samples with group resistance to leaf, yellow and stem rusts were identified, and in the juvenile stage 26 samples. 22 samples showed resistance to three rusts in both phases of ontogenesis. Of these, 5 samples belong to the VIR collection, 3 winter triticale varieties (Dozor, Knyaz, Svat) and the Kavalerka wheat variety selection of the P.P. Lukyanenko National Grain Centre, 9 lines from the Donskoy Agrarian Research Centre and the Federal Rostov Agrarian Research Centre, and 4 winter triticale varieties (Ataman Platov, Zimogor, Kapral, Legion) of selections of the Federal Rostov Agrarian Research Centre. Conclusion. The samples of wheat and winter triticale with group resistance which have been identified are promising for use in breeding for immunity to rust diseases.

Natural Growth Model of Amorphophallus gigas from Simandiangin Hamlet, Sungai Kanan District, North Sumatra

Amorphophallus gigas is a plant belonging to the Araceae family, including the tallest flower in the world. A. gigas was often found in North Sumatra, grows naturally under agroforestry stands. The aim of this research was to calculate the population of A. gigas and predict the population of A. gigas in the future assuming the habitat is not disturbed. This research was conducted in Simandiangin Hamlet, South Labuhanbatu Regency, North Sumatra Indonesia. The method used is to count the number of A. gigas individuals in 1 hectare by census. From the research results, there were 92 Amorphopallus gigas individuals with various growth phases, 40 seedlings, 28 juveniles and 26 adults. The average seedling height is 7.52 cm, the average seedling diameter is 0.27 cm, the average number of leaves is 7, the average canopy width is 27.27 cm. The average height in the juvenile phase is 56.88 cm, the average diameter is 1.40 cm and the canopy width is 76.2 cm. The average height in the adult phase is 151 cm, diameter 5.36, number of leaves 132 and canopy width 199.08 cm.

Growth performance, reproductive status, and chromosomal instability in triploid Nile tilapias.

Reproductive control is one of the biggest challenges in tilapia production and triploidy was developed as an alternative to sterilization. In general, polyploids present chromosomal instability but for triploid Nile tilapia it has yet to be reported. This study evaluated the chromosomal instability from juveniles to adulthood, growth performance and gonadal status of tilapia hatched from eggs submitted or not to heat shock for triploid induction. Nile tilapia oocytes were fertilized (1,476 oocytes), half of the eggs were subjected to a four-minute shock in 41 °C water four minutes after fertilization and the other half were not (Control group). The eggs were incubated (at 27°C) and 160 larvae from the treated group hatched and survived after yolk sac absorption. The determination of ploidy was performed by flow cytometry at 85th (juveniles) and 301st (adults) days of age post yolk sac absorption. At the time of the first cytometry analysis there were 73 surviving juveniles from the treated group, and only 14 were confirmed triploid. However, at the analysis of adult ploidy, one out of 8 surviving adult tilapias from the 14 confirmed triploid juveniles remained triploid. Gonadal histology showed that the non-remaining triploids continued to produce gametes. The growth performance of triploid tilapia was initially superior to that of diploid tilapia during the juvenile phase, but similar in adults. Once the chromosome sets are lost and the tilapias become diploid again, at least in tissues with a high proliferation rate, such as the hematopoietic tissue that was analyzed (and possibly in gonads), all possible advantages of triploids are probably lost. Thus, our results suggest that, due to genomic instabilities, the triploid generation of tilapia has low efficiency.

Crescimento vegetativo de Phalaenopsis sp. híbrido (Moon Orchid) em resposta à intensidade luminosa e concentração de fertilizantes

Abstract Orchid plants are one of the most popular floral decorative plants. Among the several species of orchids, Phalaenopsis sp. or moon orchid is popular because of its distinctive color, shape, and size. However, orchids have a slow growth rate due to their long juvenile phase; thus, culture technique modification is required to boost their growth, i.e., shading and fertilizer application. This research was carried out to obtain the best shade percentage and fertilizer concentration to increase the growth of moon orchid. The experiment was conducted from June to December 2022 at the greenhouse of Bale Tatanan Padjadjaran, Faculty of Agriculture, Universitas Padjadjaran, Jatinangor, Sumedang, Jawa Barat. The experiment used a split-plot design of eight shade and fertilizer treatments. The plants were cultivated in two shading intensities, namely 60% and 70%, then treated with four different complete foliar fertilizer compound concentrations (1, 2, 3, and 4 g L-1). The results showed that 60% shade combined with 2 g L-1 of foliar fertilizer significantly increased the leaf area and root length, whereas 70% shade combined with 4 g L-1 significantly increased the leaf area, root number and CCI of moon orchid.

Neurodevelopment effects of early life bisphenol-A exposure on visual memory: Insights into recovery dynamics

Bisphenol A (BPA), a ubiquitous endocrine disruptor, is implicated in the cognitive deficits observed in both children and animals. Especially, BPA-induced spatial memory deterioration during the whole development phase of rodents has been well delineated. However, whether BPA exposure on the different development phases exerts similar effects on the prefrontal cortex (PFC) dependent visual memory is still elusive. Here, we chose two exposure windows, the whole gestation and lactation phases (E0∼P21) and the whole juvenile and adolescent phases (P22∼P60), for exposing rats to BPA. The visual memory of those rats was accessed by object recognition testing in the open field after BPA exposure and a constant recovery interval. The results revealed a substantial decline of visual memory under both exposure conditions, accompanied by an increase in anxiety-like behavior in BPA-exposed rats. Notably, after a 20-day recovery period, those behavioral changes induced by BPA exposure during P22∼60, not E0∼P21, were reversed compared to the control rats. According to morphological analysis of those rats after recovery, we found that the spine density of pyramidal neurons in the PFC were significant decreased in rats with BPA exposure during E0∼P21 and there was no difference between rats with or without BPA exposure during P22∼P60. Additionally, a similar change trend in excitatory receptors expression was observed under both exposure conditions. After an additional 20 days of recovery, the behavioral changes in rats with perinatal BPA exposure reverted to the normal status. Our present findings illuminate the dynamic effects of BPA on PFC-dependent functions across two crucial early developmental stages of life.

Evidence of the weakly stratified crystalline magma feeding an explosive Plinian eruption: A case study of the Holocene ‘Malalak Tephra’ deposit Tandikat volcano, West Sumatra, Indonesia

The Malalak Tephra (MT) in West Sumatra, Indonesia, is a thick (up to 5 m within 5 km distance around the vent) pumice fall deposit that consists of one initial ash layer (F-0) and five main lapilli layers (F-1 and F-2 are referred to as the early stage, and F-3, F-4, and F-5 as the late stage). White pumice (microlite-free) and grey pumice (microlite-bearing) occur as the main juvenile phase in the lapilli fall layers, with a tendency of increasing grey pumice content from the early to the late stage (3–4 and 6–12 vol%, respectively). Both pumice types shared identical petrographic and chemical (glass, plagioclase, and amphibole compositions) features, suggesting a similar magmatic origin. However, a slight increase in phenocrysts content (from 30–45 to 33–58 %), modal pyroxene (from 3 to 11 vol%), and anorthite contents (from An70 to An74) was observed from the early toward the late-stage products. Such evidence, coupled with the fact that the white pumice was relatively colder, more hydrous, and shallower than the grey pumice (based on plagioclase and amphibole geothermobarometers) suggests the occurrence of a weakly stratified crystalline magma reservoir. The ‘less silicic’ magma (as the source of grey pumice) experienced extensive microlite crystallization during magma ascent because undercooling can effectively occur under lower viscosity conditions (lower SiO2), forming microlite-bearing juvenile. Whereas the ‘more silicic’ magma did not experience such an extensive syn-eruptive crystallization due to the relatively higher viscosity condition. Finally, the glass compositions of the Malalak pumice were found to be similar to the V-5 deep-marine tephra layer on the west side of Sumatra, suggesting an approximate volume and eruption age of 7.5–16.1 km3 and 4,860 ± 60 cal. BP, respectively.

EXAMINATION OF THE PHYSIOLOGICAL AND BIOCHEMICAL CHANGES AFFECTING NUTRITIONAL REQUIREMENTS THAT OCCUR IN DIFFERENT LIFE STAGES OF FISH

Fish undergo many physiological and biochemical changes throughout life, each demanding distinct nutritional consideration. This study explores the nuanced relationship between physiological and biochemical changes influencing nutritional requirements in different life stages of fish. The research involved an ethical and comprehensive investigation into various fish species' embryonic, larval, juvenile, and adult phases. Results demonstrated significant variations in growth rates, emphasizing rapid larval growth and unique reproductive hormone patterns during adulthood. Enzymatic activities reflected stage-specific digestive and metabolic demands, with larval stages exhibiting elevated digestive enzyme activities. Proximate composition analyses showcased protein, lipid, and carbohydrate content fluctuations, illustrating the evolving nutritional needs.

The Population Structure of Endemic Halmahera Walking Shark (Hemiscyllium halmahera, Allen 2013) in Kao Bay Sea, North Maluku, Indonesia

The Halmahera Walking Shark (Hemiscyllium halmahera) is an endemic fish in the Halmahera Sea. This species is distributed and found in the Kao Bay sea. The International Union for Conservation of Nature (IUCN) data shows that the Halmahera Walking Shark is in the Near Threatened status. Protection is carried out to protect the population, therefore scientific data and information are needed. This study focuses on the biological structure of the Halmahera Walking Shark population in Kao Bay sea. Data collection was carried out exploratively in coral reef, seagrass, mangrove ecosystems and by-catch. Samples were taken for morphometric data, weight and sex. Morphometric data were analyzed to obtain cohorts, separation index, class intervals, length-weight relationships and condition factors of walking shark. The result were found to be 33 individuals (13 male and 20 female). Morphological characteristics based on morphometric variables found no significant differences. Analysis of the cohort of the Halmahera Walking Shark (H.halmahera) found 3 groups namely the juvenile, mature and old age phases. The separation index shows that individuals come from different populations based on length. Growth pattern of the Halmahera Walking Shark (H.halmahera) is negative allometric. The histogram of the frequency distribution between classes found small to large size structures with different relative frequency percentages. The condition factor found that the body proportions of the Halmahera Walking Shark (H.halmahera) were in the plump category. All of this information is important to provide scientific data specifications to population.Keywords : Endemism, Halmahera, Morphology, Island, Semi enclosed

Optimization of the regeneration and Agrobacterium-mediated transformation in pear

Conventional breeding in pears is inefficient due to a long juvenile phase and self-incompatibility. Genetic transformation offers a promise to expedite the breeding process. However, the frequencies of regeneration and genetic transformation in most Pyrus spp. are relatively low. This study investigated various factors influencing regeneration and genetic transformation using leaves from Pyrus ussuriensis Maxim “Shanli” and P. communis L. “Conference” as explants. The optimum regeneration medium for “Shanli” and “Conference” was NN69 containing 3.0 mg L−1 thidiazuron (TDZ) and 0.3 mg L−1 indolybutyric acid (IBA) for the former or 1.0 mg L−1 TDZ and 0.5 mg L−1 naphthalene acetic acid (NAA) for the latter. Sectioning the leaves from 30-day-old plantlets transversely and placing them with their abaxial side facing downward could significantly improve the regeneration ratio in both accessions. Moreover, a two- or four-week culture under the dark was beneficial for the regeneration of “Shanli” and “Conference” respectively. The optimal infection time was 12 and 8 min, while the time of the delayed screening test was two and one day for “Shanli” and “Conference” respectively. Moreover, a coculture of two days was recommended for both accessions. Post-transformation, the optimal concentrations of antibiotics were 16 mg L−1 kanamycin (Kan), 150 mg L−1 timentin (Tim), and 300 mg L−1 cefotaxime (Cef). The optimized regeneration and transformation system can be an effective alternative for either gene function analysis or genetic improvement in pear.

RNA/DNA Ratio Performance of Blue Swimming Crab (Portunus pelagicus) Fed with Natural Food Phronima sp. and Artemia salina in Juvenile Phase

The availability and quality of fry is a major problem in blue swimming crab aquaculture, with the high mortality at the larval stage. RNA/DNA ratio is one of the parameters that can be used to evaluate the quality of crab fry, including health, nutrition, and growth conditions. This study aims to analyze the effect of Phronima sp. as a substitute feed for Artemia salina on the RNA/DNA ratio performance of blue swimming crab in juvenile phase (crablet 5) during rearing before cultivation in aquaculture ponds. This research was conducted at the Crab Hatchery Unit of the Brackish Water Aquaculture Fisheries Center (BPBAP) Takalar in February 2023. The study used a quantitative experimental completely randomized design (CRD) with five treatments and three repetitions. The ratio of Phronima sp. and Artemia sp. used were: Treatment A 100% Phronima sp; Treatment B 100% Artemia sp; Treatment C 75% Phronima sp and 25% Artemia sp; Treatment D 25% Phronima sp and 75% Artemia sp.; and E: Phronima 75%+Artemia salina 25%. The results showed that Artemia salina combined with Phronima sp. increased the RNA/DNA ratio of the crab compared to a single feed (100% Phronima sp. or Artemia salina 100%). The feed combination with the highest RNA/DNA ratio was shown in treatment E (Phronima sp. 25% + Artemia salina 75%) with an RNA/DNA ratio of 2.02 +0.032 ng/µL.

Are juveniles full-scale replicas of adults? Evaluation of anuran special locomotion and digging adaptations during and after metamorphosis

Many species of anurans display special mechanical abilities, such as excavation and climbing. The aim of this study is to investigate the development of traits that are associated with these special mechanical abilities, under the hypothesis that these structures attain their configuration during the juvenile stages of development. We examined specimens from four different species of Leptodactylidae and six species of Hylidae. For the digging behavior, we evaluated the progress of calcification in the anterior region of the skulls, as well as the development of the snout-ridge. To assess climbing ability, we examined the ossification rate, the variation in the shape of the phalanx, the progress of the offset angle, and the distance between the terminal phalanx and the penultimate phalange of finger IV. The ossification of the skull and phalanges, along with the development of the snout-ridge, progresses and reaches completion during the juvenile phase of ontogeny, suggesting that at the time of metamorphosis, individuals are not yet full-scale replicas of the adults. The shape and the mechanical characteristics of terminal phalanges are already established by the conclusion of metamorphosis, revealing intriguing distinctions among arboreal species with walking and jumping locomotion.

Delayed rooting hormone application and stem cutting collection time improved Flacourtia indica rooting ability and root growth

Flacourtia indica (Burm.f.) Merr. is an important fruit and medicinal tree in Southern Africa. Efforts to achieve early fruiting have failed with juvenile propagules (planting materials) such as seed. Assessing rooting ability of mature (fruit bearing) F. indica stem cuttings is vital to attaining early fruiting, or precocious fruiting, which reduces the long juvenile phase experienced by many woody fruit trees when propagated from seeds (juvenile planting materials). The objectives of this study were to assess responses of mature stem cuttings to different application times of rooting hormone (Seradix® No. 2) and collection times of stem cuttings, and also to identify important pheno-phases in the yearly tree growth cycle of F. indica. A significantly higher rooting percentage (p < 0.001) was obtained with delayed Seradix® No. 2 application than with immediate application. Stem cuttings collected at flowering and leaf fall seasons were responsive to Seradix® No. 2 application, but all stem cuttings collected at fruiting time failed to produce roots. For stem cuttings collected during flowering time, immediate Seradix® application resulted in significantly (p = 0.0482) more roots than in stem cuttings subjected to delayed Seradix® application. The failure to produce roots of cuttings collected at fruiting time could be due to low sugars (carbohydrates) in the stem cuttings. The study concluded that the best time to collect stem cuttings from mature F. indica trees for rooting is either at flowering or leaf fall stages and that delayed Seradix® No. 2 application improves rooting of stem cuttings from mature F. indica trees.

Functional trait divergence associated with heteromorphic leaves in a climbing fig.

Plants that display heteroblasty possess conspicuous variations in leaf morphology between their juvenile and adult phases, with certain species retaining juvenile-like leaves even in adulthood. Nevertheless, the ecological advantages of maintaining two or more distinct leaf types in heteroblastic plants at the adult stage remain unclear. The aim of this study is to examine the adaptive significance of heteroblastic leaves sampled from branches with divergent functions (sterile and fertile branches) of mature Ficus pumila individuals by comparing their morphological, anatomical, and physiological characteristics. Leaves on sterile branches (LSs) exhibited a significantly larger specific leaf area, thinner palisade and spongy tissues, lower chlorophyll contents, and lower light saturation points than leaves on fertile branches (LFs). These results demonstrate that LSs are better adapted to low light environments, while LFs are well equipped to take advantages of high light conditions. However, both LFs and LSs have a low light compensation point with no significant difference between them, indicating that they start to accumulate photosynthetic products under similar light conditions. Interestingly, significant higher net photosynthetic rate was detected in LFs, showing they have higher photosynthetic capacity. Furthermore, LFs produced significant more nutrients compared to LSs, which may associate to their ability of accumulating more photosynthetic products under full light conditions and higher photosynthetic capacity. Overall, we observed a pattern of divergence in morphological features of leaves on two functional branches. Anatomical and physiological features indicate that LFs have an advantage in varied light conditions, providing amounts of photosynthetic products to support the sexual reproduction, while LSs adapt to low light environments. Our findings provide evidence that heteroblasty facilitates F. pumila to utilize varying light environments, likely associated with its growth form as a climbing plant. This strategy allows the plant to allocate resources more effectively and optimize its overall fitness.

The effect of vertical skeletal proportions on overbite changes in untreated adolescents: a longitudinal evaluation.

To evaluate the change in overbite within an untreated cohort from 9 to 18 years of age and to compare age-related changes in overbite depth based on vertical skeletal proportion. Lateral cephalograms were obtained from the American Association of Orthodontists Foundation (AAOF) Craniofacial Growth Legacy Collection Project. All cephalometric outcome measures were assessed at ages 9-11 (T1), 13-15 (T2), and 17-19 (T3) years. Generalized estimating equation (GEE) regression models were fit to examine the effect of MP-SN on overbite adjusted for age and gender. A total of 130 subjects from the Denver, Bolton Brush, and Oregon Growth Studies were included. Overbite was relatively constant from T1 to T3 irrespective of facial type, with a minor decrease (0.15 mm) being observed overall. There was a transient increase between T1 and T2 (0.31 mm) that was canceled out by changes during later adolescence. Based on the GEE regression model adjusted for time and gender, a minor but statistically significantly greater reduction in overbite arose as MP-SN increased (coefficient = -0.080; 95% confidence interval -0.12, -0.04; P < .01). In hyperdivergent subjects, a marginal decrease in overbite was observed from 9 to 18 years of age, with a transient increase from the period spanning 9-11 years to 13-15 years, which was negated in later adolescence. There are limited data to suggest that observation of vertical growth is required in most patients with marginally increased vertical facial proportions in the juvenile and pubertal phases.

Upstream migrant sea lamprey (Petromyzon marinus) show signs of increasing oxidative stress but maintain aerobic capacity with age

Following the parasitic juvenile phase of their life cycle, sea lamprey (Petromyzon marinus) mature into a reproductive but rapidly aging and deteriorating adult, and typically die shortly after spawning in May or June. However, pre-spawning upstream migrant sea lamprey can be maintained for several months beyond their natural lifespan when held in cold water (∼4-8 °C) under laboratory conditions. We exploited this feature to investigate the interactions between senescence, oxidative stress, and metabolic function in this phylogenetically ancient fish. We investigated how life history traits and mitochondria condition, as indicated by markers of oxidative stress (catalase activity, lipid peroxidation) and aerobic capacity (citrate synthase activity), changed in adult sea lamprey from June to December after capture during their upstream spawning migration. Body mass but not liver mass declined with age, resulting in an increase in hepatosomatic index. Both effects were most pronounced in males, which also tended to have larger livers than females. Lamprey experienced greater oxidative stress with age, as reflected by increasing activity of the antioxidant enzyme catalase and increasing levels of lipid peroxidation in liver mitochondrial isolates over time. Surprisingly, the activity of citrate synthase also increased with age in both sexes. These observations implicate mitochondrial dysfunction and oxidative stress in the senescence of sea lamprey. Due to their unique evolutionary position and the technical advantage of easily delaying the onset of senescence in lampreys using cold water, these animals could represent an evolutionary unique and tractable model to investigate senescence in vertebrates.

Vegetative phase change causes age-dependent changes in phenotypic plasticity.

Phenotypic plasticity allows organisms to optimize traits for their environment. As organisms age, they experience diverse environments that benefit from varying degrees of phenotypic plasticity. Developmental transitions can control these age-dependent changes in plasticity, and as such, the timing of these transitions can determine when plasticity changes in an organism. Here, we investigate how the transition from juvenile-to adult-vegetative development known as vegetative phase change (VPC) contributes to age-dependent changes in phenotypic plasticity and how the timing of this transition responds to environment using both natural accessions and mutant lines in the model plant Arabidopsis thaliana. We found that the adult phase of vegetative development has greater plasticity in leaf morphology than the juvenile phase and confirmed that this difference in plasticity is caused by VPC using mutant lines. Furthermore, we found that the timing of VPC, and therefore thetime when increased plasticity is acquired, varies significantly across genotypes and environments. The consistent age-dependent changes in plasticity caused by VPC suggest that VPC may be adaptive. This genetic and environmental variation in the timing of VPC indicates the potential for population-level adaptive evolution of VPC.

Insights into the molecular mechanisms underlying responses of apple trees to abiotic stresses.

Apple (Malus[Formula: see text]domestica) is a popular temperate fruit crop worldwide. However, its growth, productivity, and quality are often adversely affected by abiotic stresses such as drought, extreme temperature, and high salinity. Due to the long juvenile phase and highly heterozygous genome, the conventional breeding approaches for stress-tolerant cultivars are time-consuming and resource-intensive. These issues may be resolved by feasible molecular breeding techniques for apples, such as gene editing and marker-assisted selection. Therefore, it is necessary to acquire a more comprehensive comprehension of the molecular mechanisms underpinning apples' response to abiotic stress. In this review, we summarize the latest research progress in the molecular response of apples to abiotic stressors, including the gene expression regulation, protein modifications, and epigenetic modifications. We also provide updates on new approaches for improving apple abiotic stress tolerance, while discussing current challenges and future perspectives for apple molecular breeding.