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At least 19 recordsLinked to original sources
PubMed2026

Systematic differences in protein stability underlie species-specific developmental tempo.

Human embryonic development proceeds more slowly than in mice. The segmentation clock offers a tractable model for studying species-specific developmental tempo, as its oscillation period in human induced presomitic mesoderm (iPSM) cells is approximately twice that of mouse. While the core clock gene HES7 exhibits slower protein degradation in human cells, it remains unclear whether such cross-species differences in protein stability reflect a general principle. Here, we perform a dynamic stable isotope labeling of amino acids in cell culture (SILAC)-based proteomic analysis of ∼5,000 proteins in human and mouse iPSM, and we uncover a broad trend of slower protein degradation in human cells, regardless of subcellular localization or degradation pathways. Moreover, inhibition of glycolysis in mouse iPSM partially phenocopies the human protein stability profile, and modulation of protein stability alters the tempo of both the segmentation clock and cellular differentiation. Our findings establish protein stability, with systematic differences across species, as a key mediator linking metabolism to developmental tempo.

Animals↗
PubMed2004

In boys with abnormal developmental tempo, maturation of the skeleton and the hypothalamic-pituitary-gonadal axis remains synchronous.

The primary mechanism that initiates puberty is unknown. One possible clue is that pubertal maturation often parallels skeletal maturation. Conditions that delay skeletal maturation also tend to delay the onset of puberty, whereas conditions that accelerate skeletal maturation tend to hasten the onset of puberty. To examine this relationship, we studied boys with congenital adrenal hyperplasia (n = 13) and familial male-limited precocious puberty (n = 22), two conditions that accelerate maturational tempo, and boys with idiopathic short stature (n = 18) in which maturational tempo is sometimes delayed. In all three conditions, the onset of central puberty generally occurred at an abnormal chronological age but a normal bone age. Boys with the greatest skeletal advancement began central puberty at the earliest age, whereas boys with the greatest skeletal delay began puberty at the latest age. Furthermore, the magnitude of the skeletal advancement or delay matched the magnitude of the pubertal advancement or delay. This synchrony between skeletal maturation and hypothalamic-pituitary-gonadal axis maturation was observed among patients within each condition and also between conditions. In contrast, the maturation of the hypothalamic-pituitary-gonadal axis did not remain synchronous with other maturational processes including weight, height, or body mass index. We conclude that in boys with abnormal developmental tempo, maturation of the skeleton and the hypothalamic-pituitary-gonadal axis remains synchronous. This synchrony is consistent with the hypothesis that in boys, skeletal maturation influences hypothalamic-pituitary-gonadal axis maturation.

Adolescent↗
PubMed2001

Three sons of fortune: early embryogenesis, evolution and ecology of nematodes.

Comparative analysis of nematode development has revealed considerable variations in how the fates of embryonic cells are specified. Such early variations seem enigmatic as they do not influence the resultant structure or performance of the emerging animal. Three different nematode species are used to consider why alternative ways to reach the same goal may have been established during evolution and why early steps of embryogenesis are particularly variable. A scenario is sketched with a shift from late to early cell specification, along with an increase in maternal contribution and developmental tempo and a decrease in regulative potential expressing different developmental strategies. Future studies of larger numbers of species are needed to assess the extent of such variations and to understand more fully the underlying mechanisms, rules and driving forces.

Animals↗
PubMed2026

A quantitative coordinate system for developmental dynamics.

Quantitative comparison of morphogenesis across individuals remains a fundamental challenge, as developing embryos vary in shape, orientation and developmental tempo. Moreover, real-time three-dimensional imaging generates large, heterogeneous four-dimensional datasets that are difficult to directly align. As a result, developmental variability is typically described qualitatively rather than measured. Here we introduce STERN, a quantitative framework that learns continuous spatiotemporal representations of morphogenesis directly from in vivo 4D imaging data. By embedding embryos into a shared spatiotemporal space, STERN defines a quantitative developmental coordinate system that enables direct comparison of developmental trajectories across individuals without requiring explicit registration or staging. Applied to mouse embryogenesis, STERN reveals that embryos follow conserved developmental trajectories while progressing at distinct temporal rates, providing a quantitative measure of developmental heterochrony. Extending this framework to zebrafish neural crest light-sheet timelapse imaging, we further show that developmental order is preserved across distinct imaging views even with altered anatomical coverage, supporting the generality of the learned representation across vertebrate imaging contexts. Finally, in developing mouse hearts, where morphogenesis proceeds through subtle and continuously evolving structural changes, STERN resolves fine-scale developmental dynamics at minute-scale temporal resolution that are difficult to localize reproducibly using human experts or general-purpose multimodal AI. Together, these results establish a shared quantitative coordinate system for morphogenesis, in which developmental trajectories become directly comparable across individuals and developmental variability becomes a measurable property.

Journal Article↗
PubMedDate not supplied

The dynamics of growth of width in distance, velocity and acceleration.

In this paper the dynamics and intensity of the growth of bihumeral and biiliac width and of humerus and femur bicondylar diameter are studied and compared, and sex differences are established. The analysis is based on a newly introduced statistical tool, the structural average curve for distance, velocity and acceleration. It accounts for individual developmental tempo and allows pooling data for a sample of subjects. In all four variables studied, a sharp decline in velocity after birth is followed by a more gradual decline in infancy and childhood. A mid-growth spurt (MS) at about age 7 can be found in all variables, of about equal timing and intensity for the two sexes. The pubertal spurt (PS) is earlier for girls, and less intense except for biiliac width. The study shows a characteristic pattern across variables of width regarding the intensity of growth in different periods. The accentuated MS and PS for bihumeral width, contrasting with relatively early and small PS for the bicondylar width of femur, are remarkable.

Adolescent↗
PubMed2004

Differences in maternal supply and early development of closely related nematode species.

Comparative analyses revealed considerable differences in embryonic pattern formation and cell-specification between Caenorhabditis elegans and Acrobeloides nanus, members of two neighboring nematode clades. While C.elegans develops very rapidly, A. nanus needs 4-5 times as long. To investigate whether differences during early embryogenesis could be related to developmental tempo, we studied three more slowly developing representatives of the genus Rhabditis, thus close relatives of C.elegans. Besides differences in body size and mode of reproduction, they differ from C.elegans in the order of cleavages, germline behavior and requirement for early zygotic transcription, showing evident similarities to A. nanus. The distinct variations in cell-cycle rhythms and arrest after inhibition of transcription appear to reflect a species-specific interplay in the timing between exhausting maternal supplies and making available newly transcribed gene products. Looking for the reversal of cleavage polarity in the germline present in C.elegans but not in A. nanus, two of the studied species express this distinct feature only in a later cell generation. We found that a C.elegans mutant in the mes-1 gene shows a similar deviation. Concerning specification of the gut cell lineage and the potential to compensate for lost cells, the three tested Rhabditis species behave less regulatively, like C.elegans; in contrast to A. nanus, the gut precursor EMS requires an inductive signal from the germline cell P2 and an experimentally eliminated EMS cell is not replaced by a neighboring blastomere. In conclusion, embryogenesis of the examined Rhabditis species includes features of both the fast-developing C. elegans and the slow-developing A. nanus.

Animals↗
PubMed2005

Assessment of developmental age: cross-sectional analysis of secondary sexual characteristics.

The developmental age of a growing person does not necessarily correspond to his or her chronological age. The two sexes differ considerably in their developmental tempo, and there are tempo differences also within the same sex. Early developers appear older, late developers appear younger than their chronological age might suggest. Based on a sample of 8675 German boys and 8689 girls of the same ethnicity, aged between 8 and 17 years sex differences of height, weight and secondary sexual characteristics are analyzed. Girls on average, develop faster than boys. Their peak of highest increments of height occurs at 10.2 years and is positioned early within the events of sexual maturity. The peak of highest increments of height in boys occurs at age 11.2 on average and is positioned relatively early within the sequences of secondary sexual characteristics. Maturing development starts with breast-stage 2 in girls at age 10.9 and penis-stage as well as scrotum-stage 2 in boys at age 11.1 on average. The development of pubic hair follows and menarche in girls at age 12.7, respectively spermarche in boys at age 13.8, marks the border to theoretical fertility. There are remarkable differences in the tempo of sexual development between the different types of body shape. In girls the pyknomorphic types are the early developers. Breast stage 2 for instance occurs at age 10.1 in the stocky and corpulent pyknomorphic girls and at age 13.0 in the tall and slender leptomorphic girls. This is different in boys. Here are much less differences between the types of body shape, but generally it is the leptomorphic type, at whom the stages of his secondary sexual characteristics are developed a little earlier.

Adolescent↗
PubMed2004

Infants' perception of rhythm and tempo in unimodal and multimodal stimulation: a developmental test of the intersensory redundancy hypothesis.

Research has demonstrated that young infants can detect a change in the tempo and the rhythm of an event when they experience the event bimodally (audiovisually), but not when they experience it unimodally (acoustically or visually). According to Bahrick and Lickliter (2000, 2002), intersensory redundancy available in bimodal, but not in unimodal, stimulation directs attention to the amodal properties of events in early development. Later in development, as infants become more experienced perceivers, attention becomes more flexible and can be directed toward amodal properties in unimodal and bimodal stimulation. The present study tested this developmental hypothesis by assessing the ability of older, more perceptually experienced infants to discriminate the tempo or rhythm of an event, using procedures identical to those in prior studies. The results indicated that older infants can detect a change in the rhythm and the tempo of an event following both bimodal (audiovisual) and unimodal (visual) stimulation. These results provide further support for the intersensory redundancy hypothesis and are consistent with a pattern of increasing specificity in perceptual development.

Acoustic Stimulation↗
PubMed2001

A developmental study of the affective value of tempo and mode in music.

Do children use the same properties as adults in determining whether music sounds happy or sad? We addressed this question with a set of 32 excerpts (16 happy and 16 sad) taken from pre-existing music. The tempo (i.e. the number of beats per minute) and the mode (i.e. the specific subset of pitches used to write a given musical excerpt) of these excerpts were modified independently and jointly in order to measure their effects on happy-sad judgments. Adults and children from 3 to 8 years old were required to judge whether the excerpts were happy or sad. The results show that as adults, 6--8-year-old children are affected by mode and tempo manipulations. In contrast, 5-year-olds' responses are only affected by a change of tempo. The youngest children (3--4-year-olds) failed to distinguish the happy from the sad tone of the music above chance. The results indicate that tempo is mastered earlier than mode to infer the emotional tone conveyed by music.

Adult↗
PubMed1989

Insects as test systems for assessing the potential role of microgravity in biological development and evolution.

Gravity and radiation are undoubtedly the two major environmental factors altered in space. Gravity is a weak force, which creates a permanent potential field acting on the mass of biological systems and their cellular components, strongly reduced in space flights. Developmental systems, particularly at very early stages, provide the larger cellular compartments known, where the effects of alterations in the size of the gravity vector on living organisms can be more effectively tested. The insects, one of the more highly evolved classes of animals in which early development occurs in a syncytial embryo, are systems particularly well suited to test these effects and the specific developmental mechanisms affected. Furthermore, they share some basic features such as small size, short life cycles, relatively high radio-resistance, etc. and show a diversity of developmental strategies and tempos advantageous in experiments of this type in space. Drosophila melanogaster, the current biological paradigm to study development, with so much genetic and evolutionary background available, is clearly the reference organism for these studies. The current evidence on the effects of the physical parameters altered in space flights on insect development indicate a surprising correlation between effects seen on the fast developing and relatively small Drosophila embryo and the more slowly developing and large Carausius morosus system. In relation to the issue of the importance of developmental and environmental constraints in biological evolution, still the missing link in current evolutionary thinking, insects and space facilities for long-term experiments could provide useful experimental settings where to critically assess how development and evolution may be interconnected. Finally, it has to be pointed out that since there are experimental data indicating a possible synergism between microgravity and space radiation, possible effects of space radiation should be taken into account in the planning and evaluation of experiments designed to test the potential role of microgravity on biological developmental and evolution.

Animals↗
PubMed2000

The development of rhythmic attending in auditory sequences: attunement, referent period, focal attending.

This paper is divided into three sections. The first section is theoretical; it extends Dynamic Attending Theory (Jones, M. R. Psychological Review 83 (1976) 323; Jones, M. R. Perception and Psychophysics 41(6) (1987) 631; Jones, M. R. Psychomusicology 9(2) (1990) 193; Jones, M. R., & Boltz, M. Psychological Review 96(3) (1989) 459) to developmental questions concerning tempo and time hierarchies. Generally Dynamic Attending Theory proposes that, when listening to a complex auditory sequence, listeners spontaneously focus on events occurring at an intermediate rate (the referent level), and they then may shift attention to events occurring over longer or shorter time spans, that is at lower (faster) or higher (slower) hierarchical levels (focal attending). The second section of the paper is experimental. It examines maturational changes of three dynamic attending activities involving referent period and level, attunement, and focal attending. Tasks involve both motor tapping (including spontaneous motor tempo and synchronization with simple sequences and music) and tempo discrimination. We compare performances by 4-, 6-, 8-, and 10-year-old children and adults, with or without musical training. Results indicate three changes with increased age and musical training: (1) a slowing of the mean spontaneous tapping rate (a reflection of the referent period) and mean synchronization rate (a reflection of the referent level), (2) enhanced ability to synchronize tapping and discriminate tempo (improved attunement), and (3) an enlarged range of tapping rates towards slower rates and higher hierarchical levels (improved focal attending). A final section considers results in light of the theory proposed here. It is suggested that growth trends can be expressed in terms of listeners' engagement of slower attending oscillators with age and experience, accompanied by the passage from the initial use of a single oscillator towards the coupling of multiple oscillators.

Adult↗
PubMed1989

Effects of growth hormone on the tempo of sexual maturation in female rhesus monkeys.

The signal that initiates and maintains the developmental change in LHRH and, consequently, LH secretion in primates, thus regulating the tempo of puberty, is not known. Given the close association between reproductive development and bone maturation, we examined the hypothesis that GH was involved in developmental increases in LH release, specifically by augmenting the decrease in estradiol (E2) negative feedback inhibition of LH that characterizes late puberty in primates. Recombinant human GH (rhGH; 250 micrograms/kg) was given (sc) three times weekly to immature female rhesus monkeys to determine if developmental increases in basal serum LH would occur at an earlier age, and if menarche and first ovulation also would be advanced. The study groups included intact females receiving rhGH (INT + GH; n = 5), intact control animals (INT; n = 6), ovariectomized females receiving E2 plus rhGH (E2OVX + GH; n = 5), and E2-treated ovariectomized control monkeys (E2OVX; n = 4). The females were studied from 20 months of age until their serum LH levels increased (E2OVX groups) or until the occurrence of first ovulation (intact groups). After 12 months of rhGH treatment, the crown-rump lengths were significantly increased, regardless of ovarian status, an effect maintained in the intact females through 21 months of treatment. The mean age at the time of the initial rise in serum LH was advanced by rhGH treatment in intact females (29.6 +/- 0.4 vs. 31.3 +/- 0.3 months), but not E2OVX females. Subsequent maturational elevations in LH secretion were similar in the E2OVS + GH and E2OVX animals even after an incremental increase in E2. Ages at menarche were similar in the INT + GH and INT groups, whereas first ovulation was significantly advanced in three of five INT + GH females (31.5 +/- 0.7 months) compared to that in INT females (43.5 +/- 0.3 months). The remaining INT + GH females ovulated at an age (42.4 +/- 0.4 months) similar to that of INT females. Those females that ovulated by 32 months had higher skeletal maturity scores than the later ovulating INT females, with the other INT + GH females being intermediate. Furthermore, rhGH resulted in a significant increase in serum E2 levels within 12 h of injection, which remained elevated through 24 h. This effect of rhGH on ovarian E2 secretion did not occur until females had shown elevations in basal serum LH.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
PubMed1982

The time of genesis, embryonic origin and differentiation of the brain stem monoamine neurons in the rhesus monkey.

Neurogenesis of the locus coeruleus (LC), substantia nigra (SN) and raphe nuclei (RN) was analyzed in autoradiograms prepared from postnatal rhesus monkeys that had been exposed to a pulse of [3H]thymidine on selected embryonic (E) days of the 165-day gestational period. Heavily labeled monoamine (MA) neurons were present only in monkeys exposed to the isotope between E27 and E36 with the peak around E30-E33. The majority of neurons generated on E30 eventually become situated in the medial part of the LC, whereas most cells of the lateral portion are generated on E32 and E33, indicating the existence of a mediolateral spatiotemporal gradient. Proliferation of neurons destined for the compact portion of the LC peaks around E32, whereas production of subcoeruleus cells proceeds more evenly throughout the E30-E33 period. SN neurons are generated between E36 and E43, with peak labeling around E38-E40, and no appreciable spatiotemporal gradients. Neurons of the ventral tegmental area are also generated between E38 and E43. Neurogenesis of the RN occurs between E28 and E43 with only a moderate rostrocaudal spatiotemporal gradient. Neurons of raphe dorsalis and centralis superior undergo final mitosis between E28 and E35, with the peak on E30, whereas cells of raphe magnus, pontis, obscurus and pallidus are produced between E35 and E43, with the peak between E38 and E40. In general, MA neurons that project to different targets may be produced simultaneously within each nucleus irrespective of any spatiotemporal gradients. Examination of another series of fetuses sacrificed at various short intervals after exposure to [3H]TdR revealed that all MA neurons arise in the ventricular zone with each MA nucleus being generated at a specific level of the brain stem. Postmitotic MA cells migrate to their final location along specific pathways, and settle in patterns corresponding to the sequence of their genesis. Morphometric analysis indicated that after reaching their final destinations, the somas and nuclei of all MA neurons grow according to the same tempo and sequence irrespective of the developmental schedules of their synaptic targets.

Animals↗
PubMed2006

Evo-devo and constraints on selection.

Developmental bias, or genetic channeling, can influence the tempo and direction of evolution and, thus, become reflected in patterns of biodiversity. Twenty years ago, this notion rested on armchair descriptions of potential constraints on evolution. Now, a broad evo-devo approach involving both evolutionary and developmental genetics provides experimental analysis of such bias, revealing how shared genetic or developmental pathways among morphological traits contribute to the evolution of complexity and diversity, and that developmental bias itself evolves, generating variation in evolvability. As I discuss here, it is now possible to determine the relative importance of natural selection and of genetical and developmental architecture as determinants of organic diversity, particularly for examples of adaptive radiations and parallel evolution.

Animals↗
PubMed2004

Thomas Henry Huxley (1825-1895) puts us in our place.

Thomas Huxley was one of the 19th century's most active defenders of Darwin's idea that life has evolved through natural processes. An anatomist and paleontologist, he extended his energies to science and education policy, the democratization of science, and the broad societal implications of evolution. Since his time the fossil record has greatly improved and the genetic 'revolution' has occurred, deepening our understanding of primate and human evolution in ways that would please Huxley: improved systematics relies heavily on genetic data, and molecular technologies are opening our understanding of the genetic basis of complex traits of traditional anthropological interest-but in ways that are thoroughly dependent on the fact of evolution. A more unified biological synthesis is forming that unites genes, developmental process, structure, and inheritance. But the tempo and mode of evolution remain unresolved. Huxley was one of many who have had trouble accepting Darwin's gradual natural selection as the central evolutionary mechanism, and views spanning the antipodes of gradualism and saltation find advocates even in our genetic era.

Biological Evolution↗
PubMed1986

Classifying multidimensional stimuli: stimulus, task, and observer factors.

When observers decide how to classify stimuli, they often employ one of two types of information: identity along one particular dimension or overall similarity. The present studies examined interrelations among the factors which determine the use of these types of information. Participants' classifications of certain types of materials (e.g., size and brightness, length and density) revealed strong individual differences, were related to the individual's response tempo and selective processing ability, and were influenced by task demands. Classifications of other materials (e.g., saturation and brightness) did not reveal individual differences, were not affected by response tempo and selective processing ability, and were unaffected by changes in task demands. The former, but not the latter, types of materials have also been found to be influenced by developmental differences. The results are consistent with the idea that differences in response tempo and selective processing ability underlie observer differences (both individual and developmental) and that certain types of stimuli which are not susceptible to such influences set boundary conditions for observer differences. The results are discussed within an integral-to-separable model of processing.

Adult↗
PubMed1995

Tempo of neurogenesis and synaptogenesis in the primate cingulate mesocortex: comparison with the neocortex.

In the neocortex, the onset of the rapid phase (phase 3) of synaptogenesis occurs after the end of neurogenesis. However, we still do not know whether or not these two developmental events are causally related. The present study compares the time-course and tempo of neurogenesis and synaptogenesis in the anterior cingulate cortex (area 24 of Brodmann) and in the primary visual cortex (area 17) in a series of pre- and postnatal rhesus monkeys. Autoradiographic analysis of animals fetally injected with 3H-thymidine showed that all neurons destined for area 24 are generated by embryonic day 70, which is 30 days earlier than in area 17. The rapid phase of synaptogenesis in area 24 starts during the third embryonic month and continues at the same rate through the remainder of gestation and the first 2 months after birth, as has been seen in neocortical areas examined previously. Statistical analysis of the linear portions of the rapid phase indicates that, although neurogenesis in area 24 is completed 1 month earlier than in area 17, the rapid phase of synaptogenesis occurs 41 days later. Moreover, the tempo of synaptic accretion was remarkably similar to that in motor, somatosensory, visual, or associational areas. All were grouped within the same time window of about 40 days, centered at birth. After the second postnatal month, synaptic density in area 24 remains at a high level until sexual maturity. This work shows that the rapid phase of synaptogenesis in the cingulate mesocortex is not linked temporally to the end of neurogenesis. We suggest that it is regulated by the same genetic or humoral factors that control synaptogenesis in the phylogenetically newer neocortical areas.

Animals↗