Effects of age and tinnitus: Limited physiological evidence and no perceptual consequence of cochlear synaptopathy

2020 ◽  
Vol 148 (4) ◽  
pp. 2466-2466
Author(s):  
Chhayakant Patro ◽  
Heather Kreft ◽  
Magdalena Wojtczak
Keyword(s):  
Physiological Evidence ◽  
Perceptual Consequence

Variation in dinosaur skeletochronology indicators: implications for age assessment and physiology

Paleobiology ◽  
1999 ◽  
Vol 25 (3) ◽  
pp. 295-304 ◽  
Author(s):  
John R. Horner ◽  
Armand de Ricqlès ◽  
Kevin Padian
Keyword(s):  
Fundamental System ◽  
External Surface ◽  
Single Element ◽  
Age Assessment ◽  
Holotype Specimen ◽  
Physiological Evidence ◽  
Periosteal Surface ◽  
Single Bone

Twelve different bones from the skeleton of the holotype specimen of the hadrosaurian dinosaur Hypacrosaurus stebingeri were thin-sectioned to evaluate the significance of lines of arrested growth (LAGs) in age assessments. The presence of an external fundamental system (EFS) at the external surface of the cortex and mature epiphyses indicate that the Hypacrosaurus specimen had reached adulthood and growth had slowed considerably from earlier stages. The number of LAGs varied from none in the pedal phalanx to as many as eight in the tibia and femur. Most elements had experienced considerable Haversian reconstruction that had most likely obliterated many LAGs. The tibia was found to have experienced the least amount of reconstruction, but was still not optimal for skeletochronology because the LAGs were difficult to count near the periosteal surface. Additionally, the numbers of LAGs within the EFS vary considerably around the circumference of a single element and among elements. Counting LAGs from a single bone to assess skeletochronology appears to be unreliable, particularly when a fundamental system exists.Because LAGs are plesiomorphic for tetrapods, and because they are present in over a dozen orders of mammals, they have no particular physiological meaning that can be generalized to particular amniote groups without independent physiological evidence. Descriptions of dinosaur physiology as “intermediate” between the physiology of living reptiles and that of living birds and mammals may or may not be valid, but cannot be based reliably on the presence of LAGs.

Behavioral and physiological evidence of sexual climax in the female stump-tailed macaque (Macaca arctoides)

Science ◽  
1980 ◽  
Vol 208 (4451) ◽  
pp. 1477-1479 ◽  
Author(s):  
D. Goldfoot ◽  
H Westerborg-van Loon ◽  
W Groeneveld ◽  
A. Slob
Keyword(s):  
Macaca Arctoides ◽  
Physiological Evidence

scholarly journals THE ORGANIZATION AND INNERVATION OF THE LUMINESCENT ORGAN IN A FIREFLY, PHOTURIS PENNSYLVANICA (COLEOPTERA)

1963 ◽  
Vol 16 (2) ◽  
pp. 323-359 ◽  
Author(s):  
David S. Smith
Keyword(s):  
Electron Microscope ◽  
Synaptic Vesicles ◽  
Light Emission ◽  
Nerve Endings ◽  
Tracheal Epithelium ◽  
Nerve Terminals ◽  
Tracheal System ◽  
Physiological Evidence ◽  
Effector System

The organization of the luminescent organ of an adult firefly has been studied with the electron microscope, and particular attention has been given to the disposition of nerve terminals within the organ. The cytological structure of the cells of the tracheal system, the peripheral and terminal axons, the photocytes and the cells of the dorsal ("reflecting") layer is described. Previous observations on the peripheral course of nerve branches alongside the tracheal trunks at the level of the dorsal layer and photocyte epithelium have been confirmed, and specialised nerve endings containing axoplasmic components structurally identical with "synaptic vesicles" and "neurosecretory droplets" have been identified, not in association with the surface of the photocytes, but lying between the apposed surfaces of two components of the tracheal epithelium: the tracheal end-cell and the tracheolar cell. These cytological findings are discussed in terms of available biochemical and physiological evidence concerning the mechanism of light emission in the firefly, especially with respect to the possible role of chemical "transmitter" action in triggering a response in a luminescent effector system.

scholarly journals Herbivore feeding behavior validates optimal defense theory for specialized metabolites within plants

2021 ◽  
Author(s):  
Pascal Hunziker ◽  
Sophie Konstanze Lambertz ◽  
Konrad Weber ◽  
Christoph Crocoll ◽  
Barbara Ann Halkier ◽  
...  
Keyword(s):  
Feeding Behavior ◽  
Feeding Preference ◽  
Optimal Defense Theory ◽  
Generalist Herbivore ◽  
Optimal Defense ◽  
Specialized Metabolites ◽  
Physiological Evidence ◽  
Young Leaves ◽  
Plant Metabolite ◽  
Defense Theory

Numerous plants protect themselves from attackers using specialized metabolites. The biosynthesis of these deterrent, often toxic metabolites is costly, as their synthesis diverts energy and resources on account of growth and development. How plants diversify investments into growth and defense is explained by the optimal defense theory. The central prediction of the optimal defense theory is that plants maximize growth and defense by concentrating specialized metabolites in tissues that are decisive for fitness. To date, supporting physiological evidence merely relies on the correlation between plant metabolite distribution and animal feeding preference. Here, we use glucosinolates as a model to examine the effect of changes in chemical defense distribution on actual feeding behavior. Taking advantage of the uniform glucosinolate distribution in transporter mutants, we show that high glucosinolate accumulation in tissues important to fitness protects them by guiding larvae of a generalist herbivore to feed on other tissues. Moreover, we show that mature leaves of Arabidopsis thaliana supply young leaves with glucosinolates to optimize defense against herbivores. Our study provides physiological evidence for the central hypothesis of the optimal defense theory and sheds light on the importance of integrating glucosinolate biosynthesis and transport for optimizing plant defense.

Sign in / Sign up

Export Citation Format

Share Document