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Relevance. Autism spectrum disorder (ASD) is a developmental disorder of the brain with unclear etiology and pathophysiology, characterized by impaired social communication, stereotypic or repetitive behavior, and varying degrees of mental retardation. One of the environmental factors that have an adverse effect on pregnant women and embryo development is propionic acid (PPA), which is a secondary metabolite of the intestinal microbiota and is widely used as a food preservative. Under physiological conditions, PPC modulates cellular signal transduction, neurotransmitter synthesis and release, cellular interactions, gene expression, immune function, and affects mitochondrial and lipid metabolism. Excessive exposure to PPC can have a number of negative consequences on health and behavior, including leading to the development of ASD.The aim of present research was to assess behavioral characteristics in male and female Wistar rats with ASD caused by prenatal administration of sodium salt of propionic acid at the early perinatal and juvenile stages of development.Methods. In a model of ASD induced by prenatal administration of propionic acid at a dose of 500 mg/kg, subcutaneously on days 12–16 of gestation, behavior was assessed in the “nesting” and juvenile periods of life in male and female Wistar rats. Physical and neurological development, social behavior (“Maternal scent”, “Paired test”), repetitive behavior (Y-maze, “Auto-grooming”), motor and exploratory activity (“Mink test”) were assessed.Results. In Wistar rats prenatally treated with propionic acid, there was a slowdown in the formation of a number of reflexes at the stage of early postnatal development, and at a later stage – a decrease in social behavior, increased stereotypy and aggression, hyperlocomotion and low exploratory activity.Conclusion. The ASD model induced by prenatal administration of PPC is adequate and suitable for studying means of pharmacological correction of ASD.

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. [ABSTRACT FROM AUTHOR]

Key message: Studied beech provenances showed different patterns of inter-annual variability in mean vessel area and ring widths, indicating influence of intraspecific variability and diverse environment on hydraulic conductivity and carbon storage potential. International provenance trials of ecologically and economically important tree species are crucial to deciphering the influence of environmental factors and intraspecific variability on tree growth and performance under climate change to guide assisted gene flow and assisted migration of tree provenances and species. In this context, we compared inter-annual trends in tree-ring widths (carbon sequestration potential) and vessel characteristics (conductivity optimisation) of four beech provenances in two international provenance trials, one in Slovenia (Kamenski hrib, a core beech growing site) and one in Hungary (Bucsuta, a marginal beech site) in 2009–2019. We found different patterns of inter-annual variability in mean vessel area and tree-ring widths among provenances and sites, pointing to diverse genetic background and environmental influence on these two wood-anatomical traits. The average values of the vessel area varied less between provenances at Kamenski hrib than at Bucsuta. Weather conditions differently affected tree-ring width and mean vessel area. Furthermore, the length of the period of response of vessel area to the analysed weather conditions differed in summer and winter periods. The differences in the mean vessel area within the tree ring were more pronounced in the weather-wise extreme years, regardless of the provenance. Consistent with previous studies, we confirmed that site conditions affect the climate sensitivity of trees, which is more pronounced at marginal sites or in extreme years. The findings on how different environmental conditions affect the radial growth of young beech trees of different origin are very important for future forest management. [ABSTRACT FROM AUTHOR]

Since studies on the reproductive consequences after the exposure to environmentally relevant doses of Benzo(a)pyrene (BaP) during critical stages of development are scarce, this study evaluated female reproductive parameters of adult rats exposed to a low dose of BaP during the juvenile phase. Female rats (Post-natal 21) were treated with BaP (0 or 0.1 µg/kg/day; gavage) for 21 consecutive days. During the treatment, no clinical signs of toxicity were observed. Nevertheless, the ages of vaginal opening and first estrus were anticipated by the BaP-exposure. At the sexual maturity, the juvenile exposure compromised the sexual behavior, as well as the placental efficiency, follicle stimulating hormone levels, placenta histological analysis, and ovarian follicle count. A decrease in erythrocyte, platelet, and lymphocyte counts also was observed in the exposed-females. Moreover, the dose of BaP used in this study was not able to produce estrogenic activity in vivo. These data showed that juvenile BaP-exposure, at environmentally relevant dose, compromised the female reproductive system, possibly by an endocrine deregulation; however, this requires further investigation. [ABSTRACT FROM AUTHOR]

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.

The consistency of the diet may affect the development and maintenance of the muscular and bony parts of the masticatory apparatus. Therefore, we investigated the effect of chronic intake of liquid nutrition (Fresubin) on the growth and maintenance of the weight and size of the skull, mandible, and teeth in Wistar rats fed with liquid nutrition during different developmental periods: (i) from weaning to adulthood, (ii) only in the juvenile period, or (iii) only in adulthood. We found that in all groups of rats fed with liquid nutrition, the skull and the mandible were significantly lighter in weight than those of control rats fed exclusively with pelleted chow from weaning to adulthood. In addition, in rats fed with liquid nutrition, the length of the mandible was significantly increased, whereas the height of the mandible and the length of the upper incisors were reduced. Our data indicate that food consistency may profoundly affect the growth pattern and the maintenance of the mass and size of skull bones and teeth during different periods of life. The extent of the effect was found to depend on the period during which liquid nutrition is provided and on the duration of its intake. In conclusion, the findings indicate that prolonged intake of liquid nutrition can significantly affect the development of the bone part of the masticatory apparatus. [ABSTRACT FROM AUTHOR]

Edible Macadamia is one of the most important commercial nut trees cultivated in many countries, but its large tree size and long juvenile period pose barriers to commercial cultivation. The short domestication period and well-annotated genome of Macadamia integrifolia create great opportunities to breed commercial varieties with superior traits. Recent studies have shown that members of the phosphatidylethanolamine binding protein (PEBP) family play pivotal roles in regulating plant architecture and flowering time in various plants. In this study, thirteen members of MiPEBP were identified in the genome of M. integrifolia, and they are highly similarity in both motif and gene structure. A phylogenetic analysis divided the MiPEBP genes into three subfamilies: MFT-like, FT-like and TFL1-like. We subsequently identified two TERMINAL FLOWER 1 homologues from the TFL1-like subfamily, MiTFL1 and MiTFL1-like, both of which were highly expressed in stems and vegetative shoots, while MiTFL1-like was highly expressed in young leaves and early flowers. A subcellular location analysis revealed that both MiTFL1 and MiTFL1-like are localized in the cytoplasm and nucleus. The ectopic expression of MiTFL1 can rescue the early-flowering and terminal-flower phenotypes in the tfl1–14 mutant of Arabidopsis thaliana, and it indicates the conserved functions in controlling the inflorescence architecture and flowering time. This study will provide insight into the isolation of PEBP family members and the key targets for breeding M. integrifolia with improved traits in plant architecture and flowering time. [ABSTRACT FROM AUTHOR]

Edible Macadamia is one of the most important commercial nut trees cultivated in many countries, but its large tree size and long juvenile period pose barriers to commercial cultivation. The short domestication period and well-annotated genome of Macadamia integrifolia create great opportunities to breed commercial varieties with superior traits. Recent studies have shown that members of the phosphatidylethanolamine binding protein (PEBP) family play pivotal roles in regulating plant architecture and flowering time in various plants. In this study, thirteen members of MiPEBP were identified in the genome of M. integrifolia, and they are highly similarity in both motif and gene structure. A phylogenetic analysis divided the MiPEBP genes into three subfamilies: MFT-like, FT-like and TFL1-like. We subsequently identified two TERMINAL FLOWER 1 homologues from the TFL1-like subfamily, MiTFL1 and MiTFL1-like, both of which were highly expressed in stems and vegetative shoots, while MiTFL1-like was highly expressed in young leaves and early flowers. A subcellular location analysis revealed that both MiTFL1 and MiTFL1-like are localized in the cytoplasm and nucleus. The ectopic expression of MiTFL1 can rescue the early-flowering and terminal-flower phenotypes in the tfl1–14 mutant of Arabidopsis thaliana, and it indicates the conserved functions in controlling the inflorescence architecture and flowering time. This study will provide insight into the isolation of PEBP family members and the key targets for breeding M. integrifolia with improved traits in plant architecture and flowering time.

Short fire intervals potentially drive declines in plant populations through immaturity risk—when the interval between two fires is too short to allow a plant population to develop the capacity to persist through the second fire. Through quantifying the period of time after fire for obligate-seeding species to become reproductively mature (the juvenile period), the risk of population decline under specific fire intervals can be delineated. Juvenile periods vary across space and time. We developed a model to estimate juvenile period based on environmental productivity that is applicable at a regional scale and over time with changes in climate. We compiled juvenile period data of serotinous obligate-seeder taxa across the breadth of the Southwest Australian Floristic Region (SWAFR). Environmental productivity models explained up to 76% of the variation in maximum juvenile period length. Juvenile period increased with lower precipitation, lower mean annual temperature and lower gross primary productivity, allowing spatial predictions of minimum tolerable fire intervals to conserve slow-maturing serotinous obligate-seeders across an entire floristic region. Applying juvenile period-productivity relationships to future climate scenarios indicated that for much of the SWAFR, juvenile period length is predicted to increase substantially, indicating high risk of short fire interval impacts with continuation of historic fire intervals. Using a case study of the Stirling Range National Park, we use historic fire interval data to identify locations having experienced short fire interval risk. [ABSTRACT FROM AUTHOR]

The long juvenile period in olive (Olea europaea L.) delays the evaluation of characters of interest and prolongs the selection of new cultivars in the breeding programs. Therefore, it is important to use accurate selection criteria and appropriate selection pressure to make an effective identification of the superior genotypes and to identify which parents transmit lower juvenile periods to their descendants. In this study, the juvenile period, vigor, fruit fresh weight, and oil content of fruit on a dry weight basis were evaluated in 1568 genotypes from two independent open-pollinated populations; G07, that included 520 genotypes from 25 cultivars and 1 breeding selection and G14, with 1048 genotypes from 13 cultivars. This evaluation was used to test different selection criteria and define optimal selection pressure at the initial stage of an olive breeding program. Wide ranges of variation were obtained for all the characters measured, with higher variability within progenies than between progenies. "Askal" and "Barnea" seem to be the cultivars transmitting the shorter juvenile period to the descendants. In the case of fruit fresh weight and oil content, transgression of variability limits of the parents was observed. Significant correlation was found between mean values of fruit fresh weight of progenies and their parents for G07 (0.59) and G14 (0.95). Selection was made using two selection index formulas (SI1 and SI2). A high coincidence was found between the individuals selected by both formulas and the correspondent selection pressures applied; 15% for SI1, and 14% for SI2. A wide variability in the percentage of selected genotypes was found, from no individuals selected from some progenies to more than 20% of genotypes selected in some others. These results underline the need to explore the wide genetic variability currently hosted in germplasm collections for an optimal choice of parents in olive breeding works. [ABSTRACT FROM AUTHOR]

Immature indivuduals influence the formation and maintenance of social relationships within groups in diverse ways. Because of the increased interest of group members toward newborns, lactating females may use infants as social tools to temporally gain rank positions in matrilineal societies, and differential support received by the mothers may bias the network of immatures born to females of different ranks. In this study, we investigated the changes in proximity, grooming, play, and agonism networks of lactating females and immatures of different developmental periods, sex, and mothers' dominance rank. A semi-free-ranging group of 22 capuchin monkeys (Sapajus spp) was monitored for 12 months, totaling over 300 hours of observation. During this period, the age changes of 13 immatures were monitored and recorded. Best regression models showed that an increased number of grooming partners while lactating did not translate into changes in the proximity or agonistic network positions for females. Age was the main predictor of social network changes, while sex had a minor influence on the play network and no influence on the grooming or agonistic networks. Finally, mothers' rank predicted differences in the affiliative but not the agonistic social network. This pattern points to a more affiliative and individual-based rather than agonistic and nepotism-based strategy for social network insertion, which can be explained by the decreased competition faced by the focal group and by the behavioral flexibility of the clade. [ABSTRACT FROM AUTHOR]

Play behavior is widespread in juvenile mammals and may be a mechanism for practicing skills needed in adulthood. In mammals characterized by strong adult male competition over females, juvenile males perform more social play than do females, and such play may assist in later mating competition. This study examined whether social play behavior is sexually dimorphic in a polygamous neotropical primate, the squirrel monkey (Saimiri collinsi), through a six-week field study of two groups of wild monkeys in Eastern Amazonia, Brazil. We hypothesized that males would conduct more rough-and-tumble play than females and that any sex-based play differences would be more evident in older juveniles. We video recorded juvenile play bouts and scored: age category (younger or older juvenile) and sex of players (male or female); and rough-and-tumble play behaviors (i.e., bite, grab, and wrestle). Juvenile males initiated more play bouts than did females. Most players were older juvenile males, while older juvenile females were the least represented. Older juvenile play bouts occurred mostly among males, while younger juvenile bouts consisted of a more even sex distribution. While younger juveniles did not significantly affect the number of rough-and-tumble behaviors in bouts, the number of behaviors was significantly affected by the sex of older individuals. These results indicate that social play is sexually dimorphic in juvenile S. collinsi; specifically, males play more than females and sex differences are more pronounced in older cohorts. [ABSTRACT FROM AUTHOR]

During play fighting, rats attack and defend the nape, which if contacted is nuzzled with the snout. While all strains of rats can use all defensive tactics to protect the nape, there are strain-typical preferences for using particular tactics This study tests two hypotheses for this strain difference: (1) that each strain has strain-specific thresholds for each tactic, or (2) that each strain attacks differently which leads to strain differences in which defense tactics are used. Juvenile Long-Evans and Sprague-Dawley males were tested with both unfamiliar (experiment 1) and familiar (experiment 2) same-strain and different-strain partners. Experiment two was conducted to determine if familiarity with a different strain might allow rats to modify their strain-typical pattern of play. If hypothesis (1) were true, they would maintain strain-typical defense patterns irrespective of partner strain, whereas for (2) it would vary with partner strain. Hypothesis (1) was supported in the first experiment; all the rats maintained their strain-typical patterns regardless of the partner’s strain. However, the second experiment supported neither hypothesis, as each animal displayed strain-divergent behavior when playing with partners of a different strain as well as with partners of the same strain. Given that in the second experiment subjects were reared in mixed-strain groups, it is possible that, during the early juvenile period, animals are susceptible to discordant social experiences

Abstract Background Observations of precocious (early bearing) genotypes of walnut (Juglans regia L.) under natural conditions encouraged us to study the origin and genetic control of these fascinating traits. Results In this study, the self-fertility, progeny performance, and simple sequence repeat (SSR) locus variation of iron walnut (Juglans sigillata Dode), an ecotype of J. regia, were investigated. The average self-pollinated fruit set rate of J. sigillata cv. ‘Dapao’ (DP) was 7.0% annually from 1979 to 1982. The average germination rate of self-pollinated seeds was 45.2% during the 4-year period. Most progeny had inbreeding depression. Nine representative self-pollinated progeny (SP1–SP9), with special or typical traits of DP, were selected. SP1–SP4 were precocious because they initiated flowers as early as 2 years after germination, compared to the 7–10-yr period that is typical of DP. SP9 had not flowered since 1980. Twelve SSR markers were used to analyze the SP and DP. The genome of SP had a tendency toward high levels of homozygosity. The high levels of homozygosity reported in 18 additional precocious walnut genotypes complemented the results of this study. Conclusions These results provide evidence of precocious phenotypes and genomes with high levels of homozygosity that might be generated from self-pollinating walnut. This suggests that self-pollination might facilitate the generation of unique homozygous parents for subsequent use in walnut-breeding programs. The results also indicate that more attention should be focused on adequate management of precocious walnut to avoid early depression in the production of nuts.

The long juvenile period in olive (Olea europaea L.) delays the evaluation of characters of interest and prolongs the selection of new cultivars in the breeding programs. Therefore, it is important to use accurate selection criteria and appropriate selection pressure to make an effective identification of the superior genotypes and to identify which parents transmit lower juvenile periods to their descendants. In this study, the juvenile period, vigor, fruit fresh weight, and oil content of fruit on a dry weight basis were evaluated in 1568 genotypes from two independent open-pollinated populations; G07, that included 520 genotypes from 25 cultivars and 1 breeding selection and G14, with 1048 genotypes from 13 cultivars. This evaluation was used to test different selection criteria and define optimal selection pressure at the initial stage of an olive breeding program. Wide ranges of variation were obtained for all the characters measured, with higher variability within progenies than between progenies. “Askal” and “Barnea” seem to be the cultivars transmitting the shorter juvenile period to the descendants. In the case of fruit fresh weight and oil content, transgression of variability limits of the parents was observed. Significant correlation was found between mean values of fruit fresh weight of progenies and their parents for G07 (0.59) and G14 (0.95). Selection was made using two selection index formulas (SI1 and SI2). A high coincidence was found between the individuals selected by both formulas and the correspondent selection pressures applied; 15% for SI1, and 14% for SI2. A wide variability in the percentage of selected genotypes was found, from no individuals selected from some progenies to more than 20% of genotypes selected in some others. These results underline the need to explore the wide genetic variability currently hosted in germplasm collections for an optimal choice of parents in olive breeding works.

The development of the adrenal cortex varies considerably across primates, being most conspicuous in humans, where a functional zona reticularis–the site of dehydroepiandrosterone‐sulfate (DHEA/S) production–does not develop until middle childhood (5–8 years). Prior reports suggest that a human‐like adrenarche, associated with a sharp prepubertal increase in DHEA/S, may only occur in the genus Pan. However, the timing and variability in adrenarche in chimpanzees remain poorly described, owing to the lack of longitudinal data, or data from wild populations. Here, we use urine samples from East African chimpanzees (Pan troglodytes schweinfurthii) collected over 20 years at Kanyawara in Kibale National Park, Uganda, to trace the developmental trajectories of DHEAS (n = 1,385 samples, 53 individuals) and cortisol (n = 12,726 samples, 68 individuals). We used generalized additive models (GAM) to investigate the relationship between age, sex, and hormone levels. Adrenarche began earlier in chimpanzees (~2–3 years) compared with what has been reported in humans (6–8 years) and, unlike humans, male and female chimpanzees did not differ significantly in the timing of adrenarche nor in DHEAS concentrations overall. Similar to what has been reported in humans, cortisol production decreased through early life, reaching a nadir around puberty (8–11 years), and a sex difference emerged with males exhibiting higher urinary cortisol levels compared with females by early adulthood (15–16 years). Our study establishes that wild chimpanzees exhibit a human‐like pattern of cortisol production during development and corroborates prior reports from captive chimpanzees of a human‐like adrenarche, accompanied by significant developmental increases in DHEAS. While the role of these developmental hormone shifts are as yet unclear, they have been implicated in stages of rapid behavioral development once thought unique to humans, especially in regard to explaining the divergence of female and male social behavior before pubertal increases in gonadal hormones. Research Highlights: Adrenal hormones may contribute to prepubertally emerging behavioral sex differences.Developmental shifts in wild chimpanzees' urinary dehydroepiandrosterone‐sulfate (DHEAS) parallel humans' and differ from monkeys'.Wild chimpanzees experience adrenarche and increasing DHEAS levels around 2–3 years.Urinary cortisol generally followed a mammalian developmental pattern but exhibited a human‐like sex difference.Cortisol decreased until a mid‐juvenile nadir, then levels increased, especially among males. [ABSTRACT FROM AUTHOR]

Flowering is an important stage in the life cycle of plants and also a turning point from vegetative growth to reproductive growth. This process is affected by many exogenous and endogenous factors. Some examples of the latter are endogenous hormones, plant growth status, nutrient composition, and flowering regulatory genes. Many gymnosperms have a long juvenile period. Previous studies attempted to shorten this period using traditional asexual propagation methods, but significant results have not been achieved. In recent years, molecular biology is used to study the flowering regulatory gene to obtain transgenic plants with early flowering trait. Thus, the production of gymnosperms is hastened, and economic efficiency is improved. Studies have shown that the flowering genes of plants act synergistically to form a complex network. In this paper, we reviewed the recent development in the study of the regulation of the flowering genes of gymnosperms, that is, from the floral meristemspecific gene, floral organ-specific gene, genes that inhibit plant flowering, and microRNA regulation of flowering. We provide a reference for the in-depth study on the genetic improvement of the flowering gene. [ABSTRACT FROM AUTHOR]

Background: Observations of precocious (early bearing) genotypes of walnut (Juglans regia L.) under natural conditions encouraged us to study the origin and genetic control of these fascinating traits. Results: In this study, the self-fertility, progeny performance, and simple sequence repeat (SSR) locus variation of iron walnut (Juglans sigillata Dode), an ecotype of J. regia, were investigated. The average self-pollinated fruit set rate of J. sigillata cv. 'Dapao' (DP) was 7.0% annually from 1979 to 1982. The average germination rate of self-pollinated seeds was 45.2% during the 4-year period. Most progeny had inbreeding depression. Nine representative self-pollinated progeny (SP1–SP9), with special or typical traits of DP, were selected. SP1–SP4 were precocious because they initiated flowers as early as 2 years after germination, compared to the 7–10-yr period that is typical of DP. SP9 had not flowered since 1980. Twelve SSR markers were used to analyze the SP and DP. The genome of SP had a tendency toward high levels of homozygosity. The high levels of homozygosity reported in 18 additional precocious walnut genotypes complemented the results of this study. Conclusions: These results provide evidence of precocious phenotypes and genomes with high levels of homozygosity that might be generated from self-pollinating walnut. This suggests that self-pollination might facilitate the generation of unique homozygous parents for subsequent use in walnut-breeding programs. The results also indicate that more attention should be focused on adequate management of precocious walnut to avoid early depression in the production of nuts. [ABSTRACT FROM AUTHOR]

The aim of the study was to monitor the seasonal dynamics of radial growth in one to two-year old saplings of European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.) under three different temperature regimes: greenhouse (G), cooling chamber (C) and outdoors (K). The research was conducted over two growing seasons, 2010 and 2011, in order to compare the effect of different environmental conditions on the radial growth of saplings in the first and second year of the treatment. The results showed that the patterns of the radial growth of beech saplings exposed to different temperature conditions were similar, especially in 2010. An increase in radial diameter was observed generally one month later in 2010 than in 2011, probably due to transplant shock in 2010. In pines, on the other hand, such delays were not recorded; however, the growth ring patterns of saplings exposed to different treatments differed in the studied growing seasons. In both years, the wood increment of beech was narrowest in G and widest in C. In 2010, xylem growth rings of pines were widest in Gand and narrowest in C, whereas in 2011 they were widest in K. Two-year xylem increments of beech saplings were lowest in G, but similar in C and K. In the case of pine, the two-year xylem increment was widest in K and narrowest in C. Comparison of xylem growth ring widths of pine and beech saplings in 2010 and 2011 under different regimes showed that widths in 2010 were wider in pines under all three regimes, whereas in 2011 increments of pines were narrower than those of beech only in C. Our fi ndings indicate different phenotypic plasticity of pine and beech saplings under different temperature regimes, in terms of radial growth. It is also clear that a continuation of such experiments over many growing seasons is necessary to capture the short- and long-term growth response of trees in changing environmental conditions.

The existence of play, a form of behaviour without obvious benefits to survival or reproduction, is a long-standing ethological mystery. Experiments in which socially deprived juvenile male mammals develop into sexually incompetent adults, along with widespread sexual dimorphism in rough-and-tumble play (R&T), suggest that R&T may prepare juvenile males for adult sexual behaviour. To test this hypothesis, we conducted a longitudinal study of American mink, Neovison vison , on two farms, with two cohorts each. For males ( N = 121), we predicted that individuals with the highest frequencies of rough-and-tumble play as juveniles (10–20 weeks old) would, as adults, show shorter latencies to bite females' necks and to begin copulating, and copulate for longer durations. On one farm, we conducted a pilot study of females ( N = 10) as a preliminary test of the hypothesis that R&T also prepares females for adult sexual behaviour. Here, our predictions were the opposite of those for males, since abilities to limit the number or duration of copulations could allow females to exercise pre- or postcopulatory mate choice. In total, we observed 1669 male–female encounters and 1004 separate copulations. As predicted, frequent juvenile R&T predicted long-lasting copulations in adult males and longer latencies to copulate in adult females. This was true specifically of rough-and-tumble play itself, independently of general activity levels and, among a subset of 32 males reared in environmentally enriched housing, also independently of solitary object play. To our knowledge, this is the first demonstration that juvenile rough-and-tumble play predicts adult sexual behaviour in any species. Further research is required to test whether our results for females can be replicated, and, importantly, to determine whether play truly has a causal role in either of these correlational relationships. [ABSTRACT FROM AUTHOR]

Sexual maturity involves the differentiation of the reproductive system, the maturation of germ cells, and the development of secondary sexual characteristics. Even though this topic has received much attention, little is known about the sequence of events that encompass reproductive maturation in anurans and what it could reveal about the developmental basis of life cycle evolution. The discovery of froglets of Pseudis minuta with incipient vocal sacs calling in breeding pools alongside several larger adult specimens with fully developed vocal sacs raised the question of the timing of sexual maturity in this species. Here we describe the sequence and timing of differentiation, development and maturation of the vocal sac apparatus and the testes in P. minuta (Anura, Hylidae), in order to establish a timeline of events leading to sexual maturity. Differentiation of the vocal sac apparatus begins at the final metamorphic stages, earlier than reported for other species, and the vocal sac acquires its final shape during the early postmetamorphic period. These modifications occur after gonadal differentiation, which begins early during the larval period and proceeds with a highly accelerated rate of development (e.g., secondary spermatids appear well before metamorphic climax), a situation reported previously for other anuran species only in the genus Pseudis . These results, together with a skeletochronological analysis showing that some calling specimens presented no lines of arrested growth, indicate acceleration in the timing of sexual maturity in Pseudis , and raise questions about the interdependence/decoupling during the development of the different components involved in reaching the adult stage. [ABSTRACT FROM AUTHOR]

Mink are potentially ideal for investigating the functions of play: deleterious effects of early social isolation suggest a crucial developmental role for play; and huge numbers of highly playful juvenile subjects can be studied on farms. We collected descriptive data on 186 pairs from 93 litters, half provided with play-eliciting environmental enrichment objects in their home cages, to test three hypotheses: (1) play frequency is subject to litter effects; (2) relative playfulness is stable over time; (3) play sub-types share a single, common motivational basis. We found weak litter effects that were driven by stronger litter effects on general activity, and weakly stable individual differences in both total and rough-and-tumble play. Experimentally increasing object play did not inhibit rough-and-tumble play, showing these sub-types are not motivational substitutes. Frequencies of these sub-types were also uncorrelated, and changed differently with time of day and age, further supporting this conclusion. [ABSTRACT FROM AUTHOR]

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Interspecific hybridizations represent one of the apple breeding methods by which a wide variability can be achieved, useful for creating new cultivars. The study of 2190 interspecific hybrids, obtained from 25 combinations among crab apple species (Malus coronaria, M. floribunda, M. niedzwetzkyana, M. zumi, M. prunifolia) and different apple cultivars, points out a large variability of the F1 seedlings for several traits, with significant importance in apple breeding programs. The first year of fructification, as mean per hybrid combination, varied from 6 (M. zumi x 'Jonathan') to 9.3 years; the average hybrid's age for fructification was 7.4 years. The size of fruits among families varied from 1.5 ('Starkrimson' x M. prunifolia) to 4.0 ('Reinette Baumann' x M. zumi), the mean being settled at 2.8 (therefore below mark 3, meaning 'small fruits'). The lowest infection rate both for apple scab and powdery mildew attack was noticed at hybrids from M. coronaria x 'Reinette Baumann'. On the whole, the hybrids with genitors of 'species x cultivars' type have had an early fruiting and a better resistance to scab and powdery mildew, compared to the ones from 'cultivars x species' combinations. The large variability of the studied traits gave the possibility to identify offsprings with desirable characteristics on nine hybrid combinations. Among these, 53 elite plants were selected, with a strength of selection of 2.42%, therefore a relative low value, correlated with the peculiarities of the interspecific population and the selection criteria for dessert apple. [ABSTRACT FROM AUTHOR]

As an individual matures from birth to adulthood, many factors may influence the positional repertoire. The biological and behavioral changes that accompany a growing individual are expected to influence foraging strategy, social status and interaction, diet, predator avoidance strategies, and ultimately positional behavior as a behavioral link between anatomy and the environment. In this work, positional behavior is considered as an important feature of life history in juvenile and adult white-faced capuchins (Cebus capucinus) and mantled howling monkeys (Alouatta palliata) inhabiting the same tropical forest in Costa Rica. During growth and development ontogenetic changes in body size, limb proportions, and motor skills are likely to influence locomotion and posture through the arboreal canopy. I collected data on positional behavior, activity, branch size, branch angle, and crown location during a 12-month period at Estación Biológica La Suerte in northeastern Costa Rica. Life history timing and differences in rates of growth did not predictably influence the development of adultlike positional behaviors in Cebus and Alouatta. Young Cebus resembled the adult pattern of positional behavior by 6 months of age while howlers exhibited significant differences in several positional behavior categories through 24 months of age. The positional repertoire of both species revealed similarities in the types of modes used during feed/forage and travel in juveniles and adults. Data presented here suggest that the environment exerts different pressures on growing Cebus and Alouatta that may relate to diet, energy expenditure, foraging skill, and/or social learning. [ABSTRACT FROM AUTHOR]

1. Rees & Venable (2007 ; Journal of Ecology, 95, 926–936) critically evaluated ideas of Moles et al. to explain the cross-species positive correlation between offspring size and adult size, arguing that they had misinterpreted the theoretical literature, and used cross-species patterns to constrain the evolution of life-histories. 2. In a reply to Rees & Venable, Westoby et al. (2009 ; Journal of Ecology, 97, 23–26) claimed we had misrepresented their views. Here we try to clarify the arguments indicating points of agreement and disagreement. 3. Using simple models we then extend the current theory to allow (i) the time during which seedling survival is influenced by seed mass to scale with the duration of the juvenile period and (ii) the intensity of stress experienced by seedlings to scale with adult size. These new models predict that species with long juvenile periods or large adult size will have larger seeds. 4. We synthesize the new theoretical ideas with our current understanding of the evolution of seed mass, and suggest that much of the observed increase in seed mass with adult body size may be due to constraints correlated with adult body size. [ABSTRACT FROM AUTHOR]

Juvenile female rats show maternal-like behavior toward pups. The purpose of the following experiment was to investigate whether the HPA axis, through the use of early separation manipulations that alter HPA functioning in rats, plays a role in the juvenile response to foster pups. Female rats were early deprived or maternally separated for 5 hours daily from PND 2 to 14 and compared to animal facility-reared rats. Deprivation or separation increased CRH-R1 IR in the juvenile PVN, but had no other effects on other HPA measures or on maternal behavior. Pup-exposure during the juvenile period blunted corticosterone levels after acute and repeated pup-exposures when compared to exposure to novelty and conspecifics respectively. Repeated exposures to pups also increased CRH-R1 IR relative to isolation during the juvenile period. Overall, the data suggest that although pup-exposure affects corticosterone levels, the HPA axis does not relate to juvenile maternal behavior in the present experiments. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 315–321, 2008. [ABSTRACT FROM AUTHOR]

Rationale. Despite the increasing use of cannabis among adolescents, there is scarce information about the long-term effects of cannabinoid receptor agonists in appropriate animal models. Objectives. We aimed to investigate the behavioural features of adult male and female Wistar rats that had been exposed to a chronic treatment with the cannabinoid receptor agonist CP 55,940 (CP) during the juvenile period. Methods. CP (0.4 mg/kg i.p.) or its corresponding vehicle was administered once daily, from day 35 to day 45. In adulthood, the animals were tested in the holeboard, the open field and the elevated plus-maze, under different stress (illumination) conditions. After a resting period, the serum corticosterone levels (radioimmunoassay) of the animals were measured. The effects of CP on food intake and somatic growth were monitored throughout the experimental period. Results. The CP treatment induced significant sex-dependent effects on holeboard activity, as well as a decrease in the level of emotionality/anxiety in the open field and in the plus-maze. The animals receiving CP also showed diminished food intake and body weights during the treatment period, but both parameters recovered normal values during the period after treatment. No significant effect of the CP treatment on corticosterone levels was found. Conclusions. The results demonstrate that chronic administration of CP during the peri-adolescent period resulted in marked behavioural effects in adulthood. The nature of these effects depended on the sex of the animals and on the specific behavioural test. The possible neurobiological substrates underlying the effects of CP are discussed. [ABSTRACT FROM AUTHOR]