Only the good die old? Ontogenetic determinants of locomotor performance in Eastern cottontail rabbits (Sylvilagus floridanus)

For many animals, the juvenile stage of life can be particularly perilous. Once independent, immature animals must often complete the same basic survival functions as adults despite smaller body size and other growth-related limits on performance. Because, by definition, juveniles have yet to reproduce, we should expect strong selection for mechanisms to offset these ontogenetic limitations, allowing individuals to reach reproductive adulthood and maintain Darwinian fitness. We use an integrated ontogenetic dataset on morphology, locomotor performance, and longevity in wild cottontail rabbits (Sylvilagus floridanus, Allen 1848) to test the hypothesis that prey animals are under selective pressure to maximize juvenile performance. We predicted that 1) juveniles would accelerate more quickly than adults, allowing them to reach adult-like escape speeds, and 2) juveniles with greater levels of performance should survive for longer durations in the wild, thus increasing their reproductive potential. Using high speed video and force platform measurements, we quantified burst acceleration, escape speed, and mechanical power production in 42 wild-caught S. floridanus (29 juveniles, 13 adults; all rabbits >1kg in body mass were designated to be adults, based on published growth curves and evidence of epiphyseal fusion). A subsample of 22 rabbits (16 juveniles, 6 adults) were fitted with radio-telemetry collars for documenting survivorship in the wild. We found that acceleration and escape speed peaked in the late juvenile period in S. floridanus, at an age range that coincides with a period of pronounced demographic attrition in wild populations. Differences in mass-specific mechanical power production explained ∼75% of the variation in acceleration across the dataset, indicating that juvenile rabbits outpace adults by producing more power per unit body mass. We found a positive, though non-significant, association between peak escape speed and survivorship duration in the wild, suggesting a complex relationship between locomotor performance and fitness in growing S. floridanus.

Evaluation of the meat quality of chickens of the egg-meat direction of productivity, for promising use in organic production

Purpose: studying the features of the formation of signs of meat productivity in chickens of the egg-meat direction in the juvenile period in ontogenesis and fixing the most informative age for early assessment of meat qualities.Materials and methods. Young grew in group cells of a 3-tier cellular battery. The dynamics of growth and the development of exterior and interior indicators, characterizing meat productivity in ontogenesis in the young of the Pushkin breed of chickens, which refers to an egg-meat type on productivity through periodic (every 2 weeks) weighing and taking protections of the physique in 100 heads of young people. On 21 heads, an anatomical cutting was carried out at which the mass of the heart, liver, two parts of the stomach (muscular, iron), the sum of the muscles (femur, crus, metatisium) took into account. The development of meat forms of the physique to determine the age and individual characteristics was determined using exterior articles of industrial (the length of the body, the length of the keel, the gripping of the chest, the length of the leg, hips, plus). Prombs were taken from the entire experienced livestock, together with weighing, every 2 weeks. In order to find the most informative age for an early estimate of meat quality, which would characterize meat productivity at an older age, the correlation was calculated between the industrial over the age periods and the mass of muscles at 16 weeks.Results. The dynamics of the average daily growth of the living mass and the mass of the carved carcass in the roosters was uneven. Until 8-week age, the average daily increase increased, then began to decline until 14 weeks of age, during 16-week aged an average increase increased dramatically. The dynamics of average daily growths in the roosters of individual muscles was similar, namely, from 4 to 8-week age, high rates of average daily growth were noted, and from 8 to 14 months of age there is a decrease, and then again activation of growth. Studies have shown that the growth of the skeleton is slowed down by 14 weeks. The dynamics of the average daily growth of internal organs in the roosters in the juvenile period occurs asynchronously. The greatest intensity of the growth of the heart, liver and stomach was observed on a 8-week age. Studies have shown that the stomach is most intensively developing up to 8 weeks, then development is braked sharply.Conclusion. Based on the data obtained, it can be concluded that for the preliminary selection of chickens of the egg-meat direction of cultivation with the best genetic potential for meat productivity, it is possible at 8 weeks old, but the final rating should be carried out no earlier than 14-week age. The estimation of meat qualities in a 14-week age should be carried out on the basis of live masses and industrial, namely, the oblique length of the body, the girth plus, the length of the leg, the preliminary estimate can be done in such a precursor, as the slanting the length of the body, the length of the leg and girth plus.

Prelimbic proBDNF facilitates memory destabilization by regulation of neuronal function in juveniles

Fear regulation changes as a function of age and adolescence is a key developmental period for the continued maturation of fear neural circuitry. The involvement of prelimbic proBDNF in fear memory extinction and its mediated signaling were reported previously. Given the inherent high level of proBDNF during juvenile period, we tested whether prelimbic proBDNF regulated synaptic and neuronal functions allowing to influencing retrieval-dependent memory processing. By examining freezing behavior of auditory fear conditioned rats, we found high levels of prelimbic proBDNF in juvenile rats enhanced destabilization of the retrieval-dependent weak but not strong fear memory through activating p75NTR-GluN2B signaling. This modification was attributed to the increment in proportion of thin type spine and promotion in synaptic function, as evidence by facilitation of NMDA-mediated EPSCs and GluN2B-dependent synaptic depression. The strong prelimbic theta- and gamma-oscillation coupling predicted the suppressive effect of proBDNF on the recall of post-retrieval memory. Our results critically emphasize the importance of developmental proBDNF for modification of retrieval-dependent memory and provide a potential critical targeting to inhibit threaten memories associated with neurodevelopment disorders.

The Vulnerability of the Developing Brain: Analysis of Highly Expressed Genes in Infant C57BL/6 Mouse Hippocampus in Relation to Phenotypic Annotation Derived From Mutational Studies

The hippocampus has been shown to have a major role in learning and memory, but also to participate in the regulation of emotions. However, its specific role(s) in memory is still unclear. Hippocampal damage or dysfunction mainly results in memory issues, especially in the declarative memory but, in animal studies, has also shown to lead to hyperactivity and difficulty in inhibiting responses previously taught. The brain structure is affected in neuropathological disorders, such as Alzheimer’s, epilepsy, and schizophrenia, and also by depression and stress. The hippocampus structure is far from mature at birth and undergoes substantial development throughout infant and juvenile life. The aim of this study was to survey genes highly expressed throughout the postnatal period in mouse hippocampus and which have also been linked to an abnormal phenotype through mutational studies to achieve a greater understanding about hippocampal functions during postnatal development. Publicly available gene expression data from C57BL/6 mouse hippocampus was analyzed; from a total of 5 time points (at postnatal day 1, 10, 15, 21, and 30), 547 genes highly expressed in all of these time points were selected for analysis. Highly expressed genes are considered to be of potential biological importance and appear to be multifunctional, and hence any dysfunction in such a gene will most likely have a large impact on the development of abilities during the postnatal and juvenile period. Phenotypic annotation data downloaded from Mouse Genomic Informatics database were analyzed for these genes, and the results showed that many of them are important for proper embryo development and infant survival, proper growth, and increase in body size, as well as for voluntary movement functions, motor coordination, and balance. The results also indicated an association with seizures that have primarily been characterized by uncontrolled motor activity and the development of proper grooming abilities. The complete list of genes and their phenotypic annotation data have been compiled in a file for easy access.

EjRAV1/2 Delay Flowering Through Transcriptional Repression of EjFTs and EjSOC1s in Loquat

Most species in Rosaceae usually need to undergo several years of juvenile phase before the initiation of flowering. After 4–6 years’ juvenile phase, cultivated loquat (Eriobotrya japonica), a species in Rosaceae, enters the reproductive phase, blooms in the autumn and sets fruits during the winter. However, the mechanisms of the transition from a seedling to an adult tree remain obscure in loquat. The regulation networks controlling seasonal flowering are also largely unknown. Here, we report two RELATED TO ABI3 AND VP1 (RAV) homologs controlling juvenility and seasonal flowering in loquat. The expressions of EjRAV1/2 were relatively high during the juvenile or vegetative phase and low at the adult or reproductive phase. Overexpression of the two EjRAVs in Arabidopsis prolonged (about threefold) the juvenile period by repressing the expressions of flowering activator genes. Additionally, the transformed plants produced more lateral branches than the wild type plants. Molecular assays revealed that the nucleus localized EjRAVs could bind to the CAACA motif of the promoters of flower signal integrators, EjFT1/2, to repress their expression levels. These findings suggest that EjRAVs play critical roles in maintaining juvenility and repressing flower initiation in the early life cycle of loquat as well as in regulating seasonal flowering. Results from this study not only shed light on the control and maintenance of the juvenile phase, but also provided potential targets for manipulation of flowering time and accelerated breeding in loquat.

A Review on In-vitro Haploid Production in Orchids

The aim of writing this paper is to review production of haploids in orchids in vitro. Haploids possess half number of chromosomes and do not undergo fertilization. In vitro conditions provide necessary nutrients and conditions that are required for growth of haploid plantlets. The natural breeding cycle of orchids is very slow as well as unpredictable. To reduce this time, the technique of in vitro haploid production is used. In vitro conditions can decrease or shorten the time required for juvenile period in Orchids. Haploid plants are produced from in vitro haploid culture. This technique is useful to produce homozygous pure lines and to increase the yield of a plant.

Exercise During Childhood Protects Against Cardiac Dysfunction Later in Life

Cardiovascular disease continues to be a major cause of morbidity and mortality, particularly in aging populations. Exercise is amongst the most cardioprotective interventions identified to date, with early in life exercise such as during the juvenile period potentially imparting even more cardioprotective outcomes due to the plasticity of the developing heart. To test the hypothesis that juvenile exercise would impart later in life cardioprotection, we exercised juvenile male and female mice via voluntary wheel running from 3-5 weeks of age and then exposed them to cardiac stress by isoproterenol (ISO) at 4-6 and 18 months of age in adulthood and older age, respectively. We compared cardiac function and remodeling to sedentary control animals, sedentary animals who received ISO, and adult and aged mice that exercised for two weeks immediately before ISO exposure. Juvenile mice engaged in voluntarily wheel running, with male mice running 1.3 ± 0.8 km and female mice 2.8 ± 1.0 km a day. Echocardiography suggested that these juvenile animals underwent running-induced cardiac remodeling as evidenced by higher ejection fraction and stroke volume compared to sedentary controls. Exercise in the juvenile period attenuated ISO-induced cardiac hypertrophy and remodeling later in life compared to sedentary animals and those that exercised immediately before ISO administration. The mechanisms by which early versus late exercise is protective in adult and aged mice are under investigation. Further ongoing work will identify the adaptations induced by exercise in the juvenile heart that may help improve cardiac aging.

Citrus Genetic Transformation: An Overview of the Current Strategies and Insights on the New Emerging Technologies

Citrus are among the most prevailing fruit crops produced worldwide. The implementation of effective and reliable breeding programs is essential for coping with the increasing demands of satisfactory yield and quality of the fruit as well as to deal with the negative impact of fast-spreading diseases. Conventional methods are time-consuming and of difficult application because of inherent factors of citrus biology, such as their prolonged juvenile period and a complex reproductive stage, sometimes presenting infertility, self-incompatibility, parthenocarpy, or polyembryony. Moreover, certain desirable traits are absent from cultivated or wild citrus genotypes. All these features are challenging for the incorporation of the desirable traits. In this regard, genetic engineering technologies offer a series of alternative approaches that allow overcoming the difficulties of conventional breeding programs. This review gives a detailed overview of the currently used strategies for the development of genetically modified citrus. We describe different aspects regarding genotype varieties used, including elite cultivars or extensively used scions and rootstocks. Furthermore, we discuss technical aspects of citrus genetic transformation procedures via Agrobacterium, regular physical methods, and magnetofection. Finally, we describe the selection of explants considering young and mature tissues, protoplast isolation, etc. We also address current protocols and novel approaches for improving the in vitro regeneration process, which is an important bottleneck for citrus genetic transformation. This review also explores alternative emerging transformation strategies applied to citrus species such as transient and tissue localized transformation. New breeding technologies, including cisgenesis, intragenesis, and genome editing by clustered regularly interspaced short palindromic repeats (CRISPR), are also discussed. Other relevant aspects comprising new promoters and reporter genes, marker-free systems, and strategies for induction of early flowering, are also addressed. We provided a future perspective on the use of current and new technologies in citrus and its potential impact on regulatory processes.

Transcriptome dynamics in developing testes of domestic cats and impact of age on tissue resilience to cryopreservation

Background Fundamental knowledge of cellular and molecular mechanisms in developing testicular tissues is critical to better understand gonadal biology and responses to non-physiological conditions. The objective of our study was to (1) analyze transcriptome dynamics in developing testis of the domestic cat and (2) characterize age effects on the initial response of the tissue to vitrification. Tissues from adult and juvenile cats were processed for histology, DNA integrity, and RNA sequencing analyses before and after vitrification. Results Transcriptomic findings enabled to further characterize juvenile period, distinguishing between early and late juvenile tissues. Changes in gene expression and functional pathways were extensive from early to late juvenile to adult development stages. Additionally, tissues from juvenile animals were more resilient to vitrification compared to adult counterparts, with early juvenile sample responding the least to vitrification and late juvenile sample response being closest to adult tissues. Conclusions This is the first study reporting comprehensive datasets on transcriptomic dynamic coupled with structural analysis of the cat testis according to the age and exposure to cryopreservation. It provides a comprehensive network of functional terms and pathways that are affected by age in the domestic cat and are either enriched in adult or juvenile testicular tissues.

Recovery of Haemal Lordosis in European Sea Bass Dicentrarchus labrax (Linnaeus 1758)

The lordosis of the haemal part of the vertebral column is a frequent abnormality in reared fish. Haemal lordosis develops during the late larval and early juvenile period, mainly due to the high swimming activity of the fish in the rearing tanks. In the present study we examined whether haemal lordosis recovers during the growth of European sea bass. Furthermore, we aimed to develop simple morphometric indices (PrAn1 and PrAn2) that could link the severity of lordosis at the juvenile stage with fish morphological quality at harvesting. At 111 days post-hatching (dph, 53±4 mm standard length, SL), 600 seabass juveniles with lordotic (L, 200 fish) or normal (N, 400 fish) external morphology were selected and introduced in a common tank. At 150 dph (75±7 mm SL), 350 fish were randomly selected, pit-tagged and transferred in a sea cage for on-growing up to 502 dph (234±16 mm SL). The morphological examination of the fish at 150 and 502 dph revealed that the 60% (46 out of 77) of L juveniles turned into normal phenotype by the end of on-growing period. Interestingly, 56% of the fish with recovered external morphology (N-Rec) presented either a completely normal vertebral column (31%) or minor abnormalities of individual vertebrae (25%). Following the results of geometric morphometric analysis, the differences in the body shape between N-Rec and N fish were not significant (p>0.05, canonical variate analysis). The examined morphometric indices were effective in discriminating the normal fish from the 58% (PrAn1) to 65% (PrAn2) of lordotic juveniles. Results are discussed with respect to the mechanism of lordosis recovery, as well as to their application for the quality control and cull out of the abnormal fish in the commercial hatcheries.