scholarly journals Filter feeding, deviations from bilateral symmetry, developmental noise, and heterochrony of hemichordate and cephalochordate gills

2020 ◽  
Vol 10 (23) ◽  
pp. 13544-13554
Author(s):  
Charles Larouche‐Bilodeau ◽  
Xavier Guilbeault‐Mayers ◽  
Christopher B. Cameron
Keyword(s):  
Bilateral Symmetry ◽  
Filter Feeding ◽  
Developmental Noise

Developmental stability in perch (Perca fluviatilis) in acidic aluminium-rich lakes

1997 ◽  
Vol 75 (6) ◽  
pp. 919-928 ◽  
Author(s):  
Kjartan Østbye ◽  
Sigurd A. Øxnevad ◽  
Leif Asbjørn Vøllestad
Keyword(s):  
Fluctuating Asymmetry ◽  
Age Groups ◽  
Perca Fluviatilis ◽  
Bilateral Symmetry ◽  
Developmental Instability ◽  
Management Tool ◽  
Meristic Characters ◽  
Morphometric Characters ◽  
Perch Perca Fluviatilis ◽  
Developmental Noise

Fluctuating asymmetry is defined as random deviation from perfect bilateral symmetry resulting from environmental or genetic disturbances (termed developmental noise) during early embryonic development. Developmental instability is defined as the inability of an organism to follow the a priori defined growth trajectory that results in perfect bilateral symmetry, owing to insufficient buffering of the disruptive effects of developmental noise during development. Fluctuating asymmetry has been proposed for use as a measure of developmental instability. In this study we tested whether fluctuating asymmetry can be an early indication of acidification stress. Samples were taken from 10 perch (Perca fluviatilis) populations exposed to varying pH levels and aluminium concentrations. We scored 13 bilateral meristic and morphometric characters to assess fluctuating asymmetry. The level of fluctuating asymmetry in the mandibular pores and one index summarizing three of the meristic characters were significantly correlated with the acidification level. When the lakes were split into two groups, "acidified" and "control," each consisting of five lakes, the same pattern emerged. The variance of fluctuating asymmetry estimates was larger in the acidified lakes than in the control lakes. These findings imply that perch in acidic environments experience developmental perturbations during early embryogenesis, resulting in deviating bilateral morphology. The variation in fluctuating asymmetry among lakes was at the same level as previously found among age groups within one acidified lake. Based on these findings, the use of fluctuating asymmetry as a management tool to evaluate the viability of fish populations in acidified waters is of limited value unless a more comprehensive approach is used.

scholarly journals Dilp8 controls a time window for tissue size adjustment in Drosophila

2020 ◽  
Author(s):  
L. Boulan ◽  
D. Blanco-Obregon ◽  
K. El Marzkioui ◽  
F. Brutscher ◽  
D.S. Andersen ◽  
...  
Keyword(s):  
Fluctuating Asymmetry ◽  
Time Window ◽  
Bilateral Symmetry ◽  
Organ Size ◽  
Fine Tuning ◽  
Downstream Target ◽  
Systemic Mechanism ◽  
Tissue Size ◽  
Developmental Noise ◽  
Size Adjustment

ABSTRACTThe control of organ size mainly relies on precise autonomous growth programs. However, organ development is subject to random variations, called developmental noise, best revealed by the fluctuating asymmetry observed between bilateral organs. The developmental mechanisms ensuring bilateral symmetry in organ size are mostly unknown. In Drosophila, null mutations for the relaxin-like hormone Dilp8 increase wing fluctuating asymmetry, suggesting that Dilp8 plays a role in buffering developmental noise. Here we show that size adjustment of the wing primordia involves a peak of Dilp8 expression that takes place sharply at the end of juvenile growth. Wing size adjustment relies on a crossorgan communication involving the epidermis as the source of Dilp8. We identify ecdysone signaling as both the trigger for epidermal dilp8 expression and its downstream target in the wing primordia, thereby establishing reciprocal feedback between the two hormones as a systemic mechanism controlling organ size precision. Our results reveal a hormone-based time window ensuring fine-tuning of organ size and bilateral symmetry.

CFD-DEM simulation of the hydrodynamic filtration performance in balaenid whale filter feeding

2021 ◽  
pp. 147696
Author(s):  
Ya-Wei Zhu ◽  
De-An Hu ◽  
Chang-Ran Li ◽  
Chen Zhuang ◽  
Gang Yang
Keyword(s):  
Filter Feeding ◽  
Dem Simulation ◽  
Filtration Performance ◽  
Hydrodynamic Filtration

scholarly journals Nature, Nurture, and Noise: Developmental Instability, Fluctuating Asymmetry, and the Causes of Phenotypic Variation

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1204
Author(s):  
John H. Graham
Keyword(s):  
Fluctuating Asymmetry ◽  
Phenotypic Variation ◽  
Deterministic Chaos ◽  
Monozygotic Twins ◽  
Developmental Instability ◽  
Nonlinear Feedback ◽  
Developmental Variation ◽  
Sewall Wright ◽  
Developmental Noise ◽  
And Behavior

Phenotypic variation arises from genetic and environmental variation, as well as random aspects of development. The genetic (nature) and environmental (nurture) components of this variation have been appreciated since at least 1900. The random developmental component (noise) has taken longer for quantitative geneticists to appreciate. Here, I sketch the historical development of the concepts of random developmental noise and developmental instability, and its quantification via fluctuating asymmetry. The unsung pioneers in this story are Hugo DeVries (fluctuating variation, 1909), C. H. Danforth (random variation between monozygotic twins, 1919), and Sewall Wright (random developmental variation in piebald guinea pigs, 1920). The first pioneering study of fluctuating asymmetry, by Sumner and Huestis in 1921, is seldom mentioned, possibly because it failed to connect the observed random asymmetry with random developmental variation. This early work was then synthesized by Boris Astaurov in 1930 and Wilhelm Ludwig in 1932, and then popularized by Drosophila geneticists beginning with Kenneth Mather in 1953. Population phenogeneticists are still trying to understand the origins and behavior of random developmental variation. Some of the developmental noise represents true stochastic behavior of molecules and cells, while some represents deterministic chaos, nonlinear feedback, and symmetry breaking.

scholarly journals Effects of Tendon Release Surgery on Inter-Limb Leg Stiffness Control in Children with Spastic Diplegic Cerebral Palsy during Gait

2021 ◽  
Vol 11 (10) ◽  
pp. 4562
Author(s):  
Chien-Chung Kuo ◽  
Hsing-Po Huang ◽  
Hsuan-Yu Lu ◽  
Tsan-Yang Chen ◽  
Ting-Ming Wang ◽  
...  
Keyword(s):  
Cerebral Palsy ◽  
Stance Phase ◽  
Reaction Force ◽  
Bilateral Symmetry ◽  
Healthy Controls ◽  
Leg Stiffness ◽  
Characteristic Features ◽  
Total Leg ◽  
Analysis System ◽  
Single Limb Support

Impaired motor control and musculotendon tightness in the lower extremities are characteristic features of patients with diplegic cerebral palsy (CP). Tendon release surgery (TRS) helps improve joint and leg stiffness, but the effects of TRS on inter-limb coordination in terms of the total leg stiffness, and the bilateral symmetry in leg stiffness during gait, remain unknown. Ten children with spastic diplegic CP scheduled for TRS and ten healthy controls participated in this study. The inter-limb sharing of total leg stiffness during double-limb support phase and bilateral leg stiffness symmetry during stance phase of gait were calculated using the kinematic and ground reaction force data measured by a motion analysis system. Before TRS, the patients with diplegic CP walked with a decreased share of total leg stiffness during weight-acceptance (p < 0.05) and with increased bilateral leg stiffness asymmetry during single-limb support and weight-transfer during gait (p < 0.05) when compared to healthy controls. After TRS, the bilateral leg stiffness asymmetry was significantly reduced in the CP group, especially in the terminal stance phase, with inter-limb sharing of total leg stiffness becoming similar to that in controls (p > 0.05). The surgery seemed to improve the lower limb control and increased the bilateral limb symmetry during gait.

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