scholarly journals Hydrodynamic modelling of aquatic suction performance and intra-oral pressures: limitations for comparative studies

2006 ◽  
Vol 3 (9) ◽  
pp. 507-514 ◽  
Author(s):  
Sam Van Wassenbergh ◽  
Peter Aerts ◽  
Anthony Herrel
Keyword(s):  
Hydrodynamic Force ◽  
Ambient Pressure ◽  
Simple Relationship ◽  
Suction Feeding ◽  
Aquatic Animals ◽  
Future Studies ◽  
Pharyngeal Cavity ◽  
Oral Pressure ◽  
Direct Indication ◽  
Suction Performance

The magnitude of sub-ambient pressure inside the bucco-pharyngeal cavity of aquatic animals is generally considered a valuable metric of suction feeding performance. However, these pressures do not provide a direct indication of the effect of the suction act on the movement of the prey item. Especially when comparing suction performance of animals with differences in the shape of the expanding bucco-pharyngeal cavity, the link between speed of expansion, water velocity, force exerted on the prey and intra-oral pressure remains obscure. By using mathematical models of the heads of catfishes, a morphologically diverse group of aquatic suction feeders, these relationships were tested. The kinematics of these models were fine-tuned to transport a given prey towards the mouth in the same way. Next, the calculated pressures inside these models were compared. The results show that no simple relationship exists between the amount of generated sub-ambient pressure and the force exerted on the prey during suction feeding, unless animals of the same species are compared. Therefore, for evaluating suction performance in aquatic animals in future studies, the focus should be on the flow velocities in front of the mouth, for which a direct relationship exists with the hydrodynamic force exerted on prey.

scholarly journals Fishes can use axial muscles as anchors or motors for powerful suction feeding

2020 ◽  
Vol 223 (18) ◽  
pp. jeb225649 ◽  
Author(s):  
Ariel L. Camp ◽  
Aaron M. Olsen ◽  
L. Patricia Hernandez ◽  
Elizabeth L. Brainerd
Keyword(s):  
Ictalurus Punctatus ◽  
Micropterus Salmoides ◽  
The Body ◽  
Pectoral Girdle ◽  
Suction Feeding ◽  
Axial Muscles ◽  
X Ray Imaging ◽  
Oral Pressure ◽  
Volume Measurements ◽  
Epaxial Muscles

ABSTRACTSome fishes rely on large regions of the dorsal (epaxial) and ventral (hypaxial) body muscles to power suction feeding. Epaxial and hypaxial muscles are known to act as motors, powering rapid mouth expansion by shortening to elevate the neurocranium and retract the pectoral girdle, respectively. However, some species, like catfishes, use little cranial elevation. Are these fishes instead using the epaxial muscles to forcefully anchor the head, and if so, are they limited to lower-power strikes? We used X-ray imaging to measure epaxial and hypaxial length dynamics (fluoromicrometry) and associated skeletal motions (XROMM) during 24 suction feeding strikes from three channel catfish (Ictalurus punctatus). We also estimated the power required for suction feeding from oral pressure and dynamic endocast volume measurements. Cranial elevation relative to the body was small (<5 deg) and the epaxial muscles did not shorten during peak expansion power. In contrast, the hypaxial muscles consistently shortened by 4–8% to rotate the pectoral girdle 6–11 deg relative to the body. Despite only the hypaxial muscles generating power, catfish strikes were similar in power to those of other species, such as largemouth bass (Micropterus salmoides), that use epaxial and hypaxial muscles to power mouth expansion. These results show that the epaxial muscles are not used as motors in catfish, but suggest they position and stabilize the cranium while the hypaxial muscles power mouth expansion ventrally. Thus, axial muscles can serve fundamentally different mechanical roles in generating and controlling cranial motion during suction feeding in fishes.

Pollution toxicity to the transmission of larval digeneans through their molluscan hosts

Parasitology ◽  
2003 ◽  
Vol 126 (7) ◽  
pp. S5-S26 ◽  
Author(s):  
N. J. MORLEY ◽  
S. W. B. IRWIN ◽  
J. W. LEWIS
Keyword(s):  
Environmental Health ◽  
Disease Transmission ◽  
Field Studies ◽  
Economic Importance ◽  
Aquatic Animals ◽  
Future Studies ◽  
Area Of Concern

The increased occurrence of pollutants in ecosystems is a continuing area of concern. It is known that numerous diseases of wild aquatic animals can occur with decreased or increased prevalences in areas associated with high or chronic levels of pollution. This may have serious implications for environmental health. There has consequently been an increasing number of laboratory and field studies on disease transmission under polluted conditions, especially focusing on digeneans of medical or economic importance. The effect of pollutants to the transmission of larval digeneans (miracidia, cercariae, metacercariae) and snail-digenean interactions is therefore considered. An overview and interpretation of the published literature on laboratory and field studies is provided. It is apparent from these studies that the influence of pollutants on digenean transmission is highly complex with much of the observed effects in the laboratory often masked by a complexity of other factors in the field. Future studies would benefit from a standardisation of experimental procedures, increasing the number of combined laboratory and field studies, and increasing the complexity of the experiments undertaken.

scholarly journals Do aquatic ectotherms perform better under hypoxia after warm acclimation?

2021 ◽  
Vol 224 (3) ◽  
pp. jeb232512
Author(s):  
Michael Collins ◽  
Manuela Truebano ◽  
Wilco C. E. P. Verberk ◽  
John I. Spicer
Keyword(s):  
Thermal Effects ◽  
Thermal Acclimation ◽  
Aquatic Animals ◽  
Future Studies ◽  
Environmental Hypoxia ◽  
Different Temperatures ◽  
Warm Acclimation ◽  
Underlying Mechanisms ◽  
Multigenerational Effects

ABSTRACTAquatic animals increasingly encounter environmental hypoxia due to climate-related warming and/or eutrophication. Although acute warming typically reduces performance under hypoxia, the ability of organisms to modulate hypoxic performance via thermal acclimation is less understood. Here, we review the literature and ask whether hypoxic performance of aquatic ectotherms improves following warm acclimation. Interpretation of thermal acclimation effects is limited by reliance on data from experiments that are not designed to directly test for beneficial or detrimental effects on hypoxic performance. Most studies have tested hypoxic responses exclusively at test temperatures matching organisms' acclimation temperatures, precluding the possibility of distinguishing between acclimation and acute thermal effects. Only a few studies have applied appropriate methodology to identify beneficial thermal acclimation effects on hypoxic performance, i.e. acclimation to different temperatures prior to determining hypoxic responses at standardised test temperatures. These studies reveal that acute warming predominantly impairs hypoxic performance, whereas warm acclimation tends to be either beneficial or have no effect. If this generalises, we predict that warm-acclimated individuals in some species should outperform non-acclimated individuals under hypoxia. However, acclimation seems to only partially offset acute warming effects; therefore, aquatic ectotherms will probably display overall reduced hypoxic performance in the long term. Drawing on the appropriate methodology, future studies can quantify the ability of organisms to modulate hypoxic performance via (reversible) thermal acclimation and unravel the underlying mechanisms. Testing whether developmental acclimation and multigenerational effects allow for a more complete compensation is essential to allow us to predict species' resilience to chronically warmer, hypoxic environments.

Suction disk performance of echeneid fishes

2006 ◽  
Vol 84 (1) ◽  
pp. 42-50 ◽  
Author(s):  
B A Fulcher ◽  
P J Motta
Keyword(s):  
Ambient Pressure ◽  
Pressure Differential ◽  
Suction Pressure ◽  
Textured Surfaces ◽  
Caudal Peduncle ◽  
Shark Skin ◽  
Significant Difference ◽  
Resting Pressure ◽  
Suction Performance

The anatomy of the suction disk of two species of echeneid fishes, Echeneis naucrates L., 1758 and E. neucratoides Zuiew, 1786, is described, and measurements of their suction performance on both smooth and textured surfaces are given. Disk muscles erect or depress the numerous paired laminae, or toothed plates, which bear two to four rows of posteriorly directed spinules. The erect laminae create a sub-ambient chamber, allowing these fishes to adhere to other fish and inanimate objects. Resting sub-ambient suction pressure differentials were recorded, as were the greatest sub-ambient pressure differentials as the fish were pulled posteriorly to simulate drag induced by a swimming host. The resting pressure differential averaged –0.5 kPa, with no significant difference between Plexiglas® and shark skin surfaces. With a force applied to their caudal peduncle, the echeneids generated suction pressure differentials averaging –92.7 kPa within the disk cavity while attached to Plexiglas. On shark skin, the use of spinules increased friction and reduced the maximum sub-ambient suction pressure differential to –46.6 kPa; considerably more force (17.4 N) was required to dislodge the echeneids from the shark skin than from the smooth Plexiglas (11.2 N).

An Early Developmental Marker for Radial Glia in Rat Spinal Cord

1996 ◽  
Vol 54 ◽  
pp. 36-37
Author(s):  
V. Kriho ◽  
H.-Y. Yang ◽  
C.-M. Lue ◽  
N. Lieska ◽  
G. D. Pappas
Keyword(s):  
Spinal Cord ◽  
Intermediate Filament ◽  
Radial Glia ◽  
Rat Spinal Cord ◽  
Future Studies ◽  
Spinal Cord Development ◽  
Median Septum ◽  
Differentiation Marker ◽  
Early Developmental ◽  
Developing Rat

Radial glia have been classically defined as those early glial cells that radially span their thin processes from the ventricular to the pial surfaces in the developing central nervous system. These radial glia constitute a transient cell population, disappearing, for the most part, by the end of the period of neuronal migration. Traditionally, it has been difficult to definitively identify these cells because the principal criteria available were morphologic only.Using immunofluorescence microscopy, we have previously defined a phenotype for radial glia in rat spinal cord based upon the sequential expression of vimentin, glial fibrillary acidic protein and an intermediate filament-associated protein, IFAP-70/280kD. We report here the application of another intermediate filament-associated protein, IFAP-300kD, originally identified in BHK-21 cells, to the immunofluorescence study of radial glia in the developing rat spinal cord.Results showed that IFAP-300kD appeared very early in rat spinal cord development. In fact by embryonic day 13, IFAP-300kD immunoreactivity was already at its peak and was observed in most of the radial glia which span the spinal cord from the ventricular to the subpial surfaces (Fig. 1). Interestingly, from this time, IFAP-300kD immunoreactivity diminished rapidly in a dorsal to ventral manner, so that by embryonic day 16 it was detectable only in the maturing macroglial cells in the marginal zone of the spinal cord and the dorsal median septum (Fig. 2). By birth, the spinal cord was essentially immuno-negative for this IFAP. Thus, IFAP-300kD appears to be another differentiation marker available for future studies of gliogenesis, especially for the early stages of radial glia differentiation.

Environmental microscopy of capillary stress-induced strain behavior in ambient-pressure aerogels

1996 ◽  
Vol 54 ◽  
pp. 850-851
Author(s):  
Sudeep M. Rao ◽  
Joshua Samuel ◽  
Sai S. Prakash ◽  
C. Jeffrey Brinker
Keyword(s):  
Silica Aerogel ◽  
Ambient Pressure ◽  
Drying Shrinkage ◽  
Pore Filling ◽  
Silica Network ◽  
Strain Behavior ◽  
Partially Saturated ◽  
Capillary Stress ◽  
Wetting Liquid ◽  
Aerogel Films

Ambient pressure silica aerogel thin films have recently been prepared by exploiting reversible drying shrinkage caused by derivatization of the internal gel surface. Aerogels have porosities of upto 99.9% and due to the small size of the pores (few nanometers), large capillary stresses are produced in gels that are partially saturated with a wetting liquid. As a result of these capillary stresses, the flexible silica network undergoes strain which has been observed using environmental microscopy. This technique allows variation of the equilibrium vapor pressure and temperature, and a simultaneous monitoring of the deformation of the unconstrained film thickness. We have observed >600% deformation during the pore-filling and pore-emptying cycles. In this presentation, we discuss the unique stress-strain behavior of these films.Ref.: Sai S. Prakash, C. Jeffrey Brinker, Alan J. Hurd & Sudeep M. Rao, "Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage", Nature. Vol. 374, 30 March, 1995, 439-443.

Autophagy and ageing: implications for age-related neurodegenerative diseases

2013 ◽  
Vol 55 ◽  
pp. 119-131 ◽  
Author(s):  
Bernadette Carroll ◽  
Graeme Hewitt ◽  
Viktor I. Korolchuk
Keyword(s):  
Neurodegenerative Diseases ◽  
Energy Availability ◽  
Future Studies ◽  
Intracellular Degradation ◽  
Age Related ◽  
Autophagy Induction ◽  
Social Importance ◽  
Cellular Dysfunction ◽  
Autophagy Activity ◽  
Intense Research

Autophagy is a process of lysosome-dependent intracellular degradation that participates in the liberation of resources including amino acids and energy to maintain homoeostasis. Autophagy is particularly important in stress conditions such as nutrient starvation and any perturbation in the ability of the cell to activate or regulate autophagy can lead to cellular dysfunction and disease. An area of intense research interest is the role and indeed the fate of autophagy during cellular and organismal ageing. Age-related disorders are associated with increased cellular stress and assault including DNA damage, reduced energy availability, protein aggregation and accumulation of damaged organelles. A reduction in autophagy activity has been observed in a number of ageing models and its up-regulation via pharmacological and genetic methods can alleviate age-related pathologies. In particular, autophagy induction can enhance clearance of toxic intracellular waste associated with neurodegenerative diseases and has been comprehensively demonstrated to improve lifespan in yeast, worms, flies, rodents and primates. The situation, however, has been complicated by the identification that autophagy up-regulation can also occur during ageing. Indeed, in certain situations, reduced autophagosome induction may actually provide benefits to ageing cells. Future studies will undoubtedly improve our understanding of exactly how the multiple signals that are integrated to control appropriate autophagy activity change during ageing, what affect this has on autophagy and to what extent autophagy contributes to age-associated pathologies. Identification of mechanisms that influence a healthy lifespan is of economic, medical and social importance in our ‘ageing’ world.

Mesophyll conductance: the leaf corridors for photosynthesis

2020 ◽  
Vol 48 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Jorge Gago ◽  
Danilo M. Daloso ◽  
Marc Carriquí ◽  
Miquel Nadal ◽  
Melanie Morales ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Main Role ◽  
Mesophyll Conductance ◽  
Future Studies ◽  
Cell Structures ◽  
Leaf Tissues ◽  
Change Framework ◽  
Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

Special Considerations for Evaluation and Treatment of Spanish-Speaking Patients with Cleft Palate

2016 ◽  
Vol 1 (5) ◽  
pp. 41-49
Author(s):  
Ellen Moore
Keyword(s):  
Cleft Palate ◽  
The United States ◽  
Culturally Competent ◽  
Speech Language Pathology ◽  
Spanish Speaking ◽  
Appropriate Treatment ◽  
Oral Pressure ◽  
Language Pathology ◽  
History Of ◽  
Spanish Speaking Population

As the Spanish-speaking population in the United States continues to grow, there is increasing need for culturally competent and linguistically appropriate treatment across the field of speech-language pathology. This paper reviews information relevant to the evaluation and treatment of Spanish-speaking and Spanish-English bilingual children with a history of cleft palate. The phonetics and phonology of Spanish are reviewed and contrasted with English, with a focus on oral pressure consonants. Cultural factors and bilingualism are discussed briefly. Finally, practical strategies for evaluation and treatment are presented. Information is presented for monolingual and bilingual speech-language pathologists, both in the community and on cleft palate teams.

The Importance of Oral Pressure

1999 ◽  
Vol 9 (1) ◽  
pp. 16-16
Author(s):  
John E Riski
Keyword(s):  
Oral Pressure
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