The Locust Jump: III. Structural Specializations of the Metathoracic Tibiae

1977 ◽  
Vol 67 (1) ◽  
pp. 29-36
Author(s):  
W. J. HEITLER
Keyword(s):  
Vertical Component ◽  
Distal Region ◽  
Proximal Region ◽  
Flexor Muscle ◽  
Full Extension ◽  
Joint Rotation ◽  
Mechanical Advantage ◽  
Full Flexion

1. The flexor and extensor tibiae muscles of the mesothoracic leg have a constant lever ratio of about 2:1 throughout joint rotation. 2. The mesothoracic tibiae can only flex to 25° about the femora, while the metathoracic tibiae, because of their specialized geometry, can flex almost parallel to the femora. 3. Full metatibial flexion increases the mechanical advantage of the flexor muscle relative to the extensor at full flexion, and increases the vertical component of the thrust produced by tibial extension in a jump. 4. A region in the dorsal proximal cuticle of the metatibia is stiff when stretched but buckles when compressed. The tibia is thus rigid under extensor stress, but bends under flexor stress. 5. Metatibial bending can enable the proximal region of the tibia to become fully flexed even if the distal region is prevented from flexing fully, and may reduce the inertial shock to the femur when the tibia reaches full extension in a kick.

scholarly journals THE POSITION-DEPENDENT NATURE OF POSTURAL RESISTANCE REFLEXES IN THE LOCUST

1994 ◽  
Vol 188 (1) ◽  
pp. 65-88 ◽  
Author(s):  
L Field ◽  
M Coles
Keyword(s):  
Horizontal Plane ◽  
Vertical Plane ◽  
Motor Neurone ◽  
Chordotonal Organ ◽  
Joint Movement ◽  
Flexor Muscle ◽  
Full Extension ◽  
Flexor Muscles ◽  
Full Flexion

The resistance reflexes of tibial extensor and flexor muscles, of all six legs in the locust, show changes in gain at different femur­tibia angles (FTA). In all muscles the gain is high for small angles (near full flexion) and low for large angles (near full extension, approximately 160 °). An exception occurs in the mesothoracic flexor muscle, which shows two modes: one as above and another in which maximum gain occurs at 100­120 ° FTA. The position-dependent character is evident at each stage of the reflex pathway: motor neurone, non-spiking interneurone and femoral chordotonal organ (the afferent source of the reflex). We conclude that position-dependency originates from a decrease in the number of phasic femoral chordotonal organ neurones sensitive to joint movement as larger FTAs are approached. Position-dependency is only roughly correlated with the postural FTAs most commonly observed in the meso- and metathoracic legs of unrestrained resting locusts; no such correlation was evident for prothoracic legs. We propose that the major role of position-dependency is to allow resistance reflexes efficiently to counter torque introduced onto the femur­tibia joint by perturbations in the horizontal plane when the insect rests on a horizontal substratum and in the vertical plane when it rests on a vertical substratum.

scholarly journals Intestinal Apolipoprotein A-IV Gene Transcription Is Controlled by Two Hormone-Responsive Elements: A Role for Hepatic Nuclear Factor-4 Isoforms

2005 ◽  
Vol 19 (9) ◽  
pp. 2320-2334 ◽  
Author(s):  
Amena Archer ◽  
Dominique Sauvaget ◽  
Valérie Chauffeton ◽  
Pierre-Etienne Bouchet ◽  
Jean Chambaz ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transgenic Mice ◽  
Distal Region ◽  
Proximal Region ◽  
Dominant Negative ◽  
Specific Expression ◽  
Nuclear Factors ◽  
Dominant Negative Form ◽  
Responsive Element ◽  
Hormone Responsive Element

Abstract In the small intestine, the expression of the apolipoprotein (apo) C-III and A-IV genes is restricted to the enterocytes of the villi. We have previously shown that, in transgenic mice, specific expression of the human apo C-III requires a hormone-responsive element (HRE) located in the distal region of the human apoA-IV promoter. This HRE binds the hepatic nuclear factors (HNF)-4α and γ. Here, intraduodenal injections in mice and infections of human enterocytic Caco-2/TC7 cells with an adenovirus expressing a dominant-negative form of HNF-4α repress the expression of the apoA-IV gene, demonstrating that HNF-4 controls the apoA-IV gene expression in enterocytes. We show that HNF-4α and γ functionally interact with a second HRE present in the proximal region of the human apoA-IV promoter. New sets of transgenic mice expressing mutated forms of the promoter, combined with the human apo C-III enhancer, demonstrate that, whereas a single HRE is sufficient to reproduce the physiological cephalo-caudal gradient of apoA-IV gene expression, both HREs are required for expression that is restricted to villi. The combination of multiple HREs may specifically recruit regulatory complexes associating HNF-4 and either coactivators in villi or corepressors in crypts.

scholarly journals A Distal Region Involving Hepatocyte Nuclear Factor 4α and CAAT/Enhancer Binding Protein Markedly Potentiates the Protein Kinase A Stimulation of the Glucose-6-Phosphatase Promoter

2005 ◽  
Vol 19 (1) ◽  
pp. 163-174 ◽  
Author(s):  
Amandine Gautier-Stein ◽  
Gilles Mithieux ◽  
Fabienne Rajas
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Binding Sites ◽  
Binding Protein ◽  
Distal Region ◽  
Proximal Region ◽  
Nuclear Factor ◽  
Hepatocyte Nuclear Factor ◽  
Enhancer Binding Protein ◽  
Kinase A

Abstract Glucose-6-phosphatase (Glc6Pase) is the last enzyme of gluconeogenesis and is only expressed in the liver, kidney, and small intestine. In these tissues, the mRNA and its activity are increased when cAMP levels increased (e.g. in fasting or diabetes). We first report that a proximal region (within −200 bp relative to the transcription start site) and a distal region (−694/−500 bp) are both required for a potent cAMP and a protein kinase A (PKA) responsiveness of the Glc6Pase promoter. Using different molecular approaches, we demonstrate that hepatocyte nuclear factor (HNF4α), CAAT/ enhancer-binding protein-α (C/EBPα), C/EBPβ, and cAMP response element-binding protein (CREB) are involved in the potentiated PKA responsiveness: in the distal region, via one HNF4α- and one C/EBP-binding sites, and in the proximal region, via two HNF4α and two CREB-binding sites. We also show that HNF4α, C/EBPα, and C/EBPβ are constitutively bound to the endogenous Glc6Pase gene, whereas CREB and CREB-binding protein (CBP) will be bound to the gene upon stimulation by cAMP. These data strongly suggest that the cAMP responsiveness of the Glc6Pase promoter requires a tight cooperation between a proximal and a distal region, which depends on the presence of several HNF4α-, C/EBP-, and CREB-binding sites, therefore involving an intricate association of hepatic and ubiquitous transcription factors.

Regulatory elements controlling pituitary-specific expression of the human prolactin gene

1990 ◽  
Vol 10 (9) ◽  
pp. 4690-4700
Author(s):  
B Peers ◽  
M L Voz ◽  
P Monget ◽  
M Mathy-Hartert ◽  
M Berwaer ◽  
...  
Keyword(s):  
Regulatory Elements ◽  
Distal Region ◽  
Dnase I ◽  
Proximal Region ◽  
Base Pairs ◽  
Specific Expression ◽  
Positive Region ◽  
Dnase I Footprinting ◽  
Human Prolactin ◽  
Flanking Sequences

We have performed transfection and DNase I footprinting experiments to investigate pituitary-specific expression of the human prolactin (hPRL) gene. When fused to the chloramphenicol acetyltransferase (CAT) reporter gene, 5,000 base pairs of the 5'-flanking sequences of the hPRL gene were able to drive high cat gene expression in prolactin-expressing GH3B6 cells specifically. Deletion analysis indicated that this pituitary-specific expression was controlled by three main positive regulatory regions. The first was located just upstream from the TATA box between coordinates -40 and -250 (proximal region). We have previously shown that three motifs of this region bind the pituitary-specific Pit-1 factor. The second positive region was located in the vicinity of coordinates -1300 to -1750 (distal region). DNase I footprinting assays revealed that eight DNA motifs of this distal region bound protein Pit-1 and that two other motifs were recognized by ubiquitous factors, one of which seems to belong to the AP-1 (jun) family. The third positive region was located further upstream, between -3500 and -5000 (superdistal region). This region appears to enhance transcription only in the presence of the distal region.

Effect of imposed head vibration on the stability and waveform of flagellar beating in sea urchin spermatozoa

1991 ◽  
Vol 156 (1) ◽  
pp. 63-80 ◽  
Author(s):  
C. Shingyoji ◽  
I. R. Gibbons ◽  
A. Murakami ◽  
K. Takahashi
Keyword(s):  
Sea Urchin ◽  
Beat Frequency ◽  
Distal Region ◽  
Proximal Region ◽  
Bend Angle ◽  
Vibration Frequencies ◽  
Sliding Velocity ◽  
Additional Energy ◽  
The Stability ◽  
Cyclic Changes

The heads of live spermatozoa of the sea urchin Hemicentrotus pulcherrimus were held by suction in the tip of a micropipette mounted on a piezoelectric device and vibrated either laterally or axially with respect to the head axis. Within certain ranges of frequency and amplitude, lateral vibration of the pipette brought about a stable rhythmic beating of the flagella in the plane of vibration, with the beat frequency synchronized to the frequency of vibration [Gibbons et al. (1987), Nature 325, 351–352]. The sperm flagella, with an average natural beat frequency of 48 Hz, showed stable beating synchronized to the pipette vibration over a range of 35–90 Hz when the amplitude of vibration was about 20 microns or greater. Vibration frequencies below this range caused instability of the beat plane, often associated with irregularities in beat frequency. Frequencies above about 90 Hz caused irregular asymmetrical flagellar beating with a marked decrease in amplitude of the propagated bends and a skewing of the flagellar axis towards one side; the flagella often stopped in a cane shape. In flagella that were beating stably under imposed vibration, the wavelength was reduced at higher frequencies and increased at lower frequencies. When the beat frequency was equal to or lower than the natural beat frequency, the apparent time-averaged sliding velocity of axonemal microtubules, obtained as twice the product of frequency and bend angle, decreased with beat frequency in both the proximal and distal regions of the flagella. However, at vibration frequencies above the natural beat frequency, the sliding velocity increased with frequency only in the proximal region of the flagellum and remained essentially unchanged in more distal regions. This apparent limit to the velocity of sliding in the distal region may represent an inherent limit in the intrinsic velocity of active sliding, while the faster sliding observed in the proximal region may be a result of passive sliding or elastic distortion of the microtubules induced by the additional energy supplied by the vibrating pipette. Axial vibration with frequencies either close to or twice the natural beat frequency induced cyclic changes in the waveform, compressing and expanding the bends in the proximal region, but did not affect bends in the distal region or alter the beat frequency.

scholarly journals The Distribution and Severity of Corrosion Damage at Eight Distinct Zones of Metallic Femoral Stem Implants

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 840 ◽  
Author(s):  
Roohollah Milimonfared ◽  
Reza Oskouei ◽  
Mark Taylor ◽  
Lucian Solomon
Keyword(s):  
Spatial Distribution ◽  
Hip Replacement ◽  
Logistic Regression Model ◽  
Statistical Significance ◽  
Femoral Stem ◽  
Corrosion Damage ◽  
Distal Region ◽  
Proximal Region ◽  
Visual Scoring ◽  
Ordinal Logistic Regression Model

Metallic taper junctions of modular total hip replacement implants are analysed for corrosion damage using visual scoring based on different granularity levels that span from analysing the taper holistically to dividing the taper into several distinct zones. This study aims to objectively explore the spatial distribution and the severity of corrosion damage onto the surface of metallic stem tapers. An ordinal logistic regression model was developed to find the odds of receiving a higher score at eight distinct zones of 137 retrieved stem tapers. A method to find the order of damage severity across the eight zones is introduced based on an overall test of statistical significance. The findings show that corrosion at the stem tapers occurred more commonly in the distal region in comparison with the proximal region. Also, the medial distal zone was found to possess the most severe corrosion damage among all the studied eight zones.

Functional morphology of the mouthparts and proventriculus of the rock crab Nectocarcinus tuberculosus (Decapoda: Portunidae)

2003 ◽  
Vol 83 (4) ◽  
pp. 821-834 ◽  
Author(s):  
Indra Raymond Salindeho ◽  
Danielle Jane Johnston
Keyword(s):  
Content Analysis ◽  
Stomach Content ◽  
Stomach Content Analysis ◽  
Distal Region ◽  
Proximal Region ◽  
Rocky Shores ◽  
Brachyuran Crab ◽  
Cardiac Stomach ◽  
Dietary Preferences ◽  
Sea Grass

Mouthpart and proventriculus structure of the brachyuran crab Nectocarcinus tuberculosus was described by scanning electron microscopy and histology and characteristics indicative of dietary preferences were identified. A qualitative stomach content analysis was conducted to verify structural interpretations with respect to diet. The mouthparts and proventriculus of N. tuberculosus have features that are typical of macrophagous crabs and are consistent with a carnivorous diet of hard items. However, the mandibular arrangement indicates that N. tuberculosus is also adapted to ingest soft plant material and fleshy items, revealing that this crab is omnivorous which is consistent with its habitat of rocky shores and sea grass beds. Carnivorous features of the feeding apparatus include large crista dentata on the third maxillipeds that grip food items during ingestion and cuspidate setae on the second maxillipeds and first maxillae. Nectocarcinus tuberculosus has a complex arrangement of proventricular ossicles, 5-denticulated accessory teeth, and a spiny cardio-pyloric valve with rough, calcified protuberances. It has a robust, strongly calcified gastric mill with a prominent anterior cusp and 11 roughly surfaced vertical ridges on each lateral tooth specialized for crushing and grinding. In contrast to true carnivorous crabs, the mandibles in this species are symmetrically arranged, with two sharp cutting edges and no teeth, an arrangement adapted to cut softer plant-like materials and flesh. Structural interpretations with respect to diet were confirmed by stomach content analysis where items identified included gastropods, bivalves and the sea grass Posidonia australis. Functionally, the filtering system in the proventriculus of N. tuberculosus is complex. The cardiac stomach has a well developed ventral filtration system or ‘cardiac filter’ which comprises coarse and fine filters. Different modifications of setation between the distal and proximal regions of the inner valve of the pyloric filter are unique to this crab species, with an intersetule width 600 nm in the distal region and 80–100 nm in the proximal region. This suggests that some differentiation in filtration occurs between regions within the pyloric filter.

Injury to the Anterior Cruciate Ligament during Alpine Skiing

2002 ◽  
Vol 30 (4) ◽  
pp. 537-540 ◽  
Author(s):  
Sharon L. Hame ◽  
Daniel A. Oakes ◽  
Keith L. Markolf
Keyword(s):  
Anterior Cruciate Ligament ◽  
Cruciate Ligament ◽  
Alpine Skiing ◽  
Full Extension ◽  
Flexion Extension ◽  
Fresh Frozen ◽  
Full Flexion ◽  
The Mean ◽  
Anterior Cruciate ◽  
Knee Flexion Position

Background The anterior cruciate ligament has been shown to be particularly susceptible to injury during alpine skiing. Tibial torque is an important injury mechanism, especially when applied to a fully extended or fully flexed knee. Purpose We wanted to record the forces generated in the anterior cruciate ligament with application of tibial torque to cadaveric knees in different positions. Study Design Controlled laboratory study. Methods Thirty-seven fresh-frozen cadaveric knees were instrumented with a tibial load cell that measured resultant force in the anterior cruciate ligament while internal and external tibial torques were applied to the tibia at full extension, 90° of flexion, full flexion, and forced hyperflexion. Results At each knee flexion position, mean force generated by 10 N·m of internal tibial torque was significantly higher than the mean generated by 10 N·m of external tibial torque. Mean forces generated by tibial torque at 90° of flexion were relatively low. During flexion-extension without tibial torque applied mean forces were highest (193 N) when the knee was hyperflexed. Conclusions Application of internal tibial torque to a fully extended or fully flexed knee represents the most dangerous loading condition for injury from twisting falls during skiing. Clinical Relevance Understanding of the mechanisms of falls can be used to design better equipment and to better prevent or treat injury.

scholarly journals cDNA structure, tissue-specific expression, and chromosomal localization of the murine band 7.2b gene

Blood ◽  
1995 ◽  
Vol 86 (1) ◽  
pp. 359-365 ◽  
Author(s):  
PG Gallagher ◽  
M Romana ◽  
JH Lieman ◽  
DC Ward
Keyword(s):  
Alpha Helix ◽  
Distal Region ◽  
Proximal Region ◽  
Erythrocyte Membranes ◽  
Chromosome 2 ◽  
Specific Expression ◽  
Tissue Specific ◽  
Reading Frame ◽  
Tissue Specific Expression ◽  
Membrane Spanning

Band 7.2b is an integral phosphoprotein absent from the erythrocyte membranes of patients with hydrocytosis, an autosomal, dominantly inherited, hemolytic anemia characterized by stomatocytic red blood cells with abnormal permeability to Na+ and K+. The role of this protein in the erythrocyte membrane is not well understood. To gain additional insight into the structure and function of this protein, we have cloned the murine band 7.2b cDNA and studied its tissue-specific expression. 2,873 bp of cDNA with an open reading frame of 852 bp were isolated. This fragment encodes a protein of 284 amino acids with a predicted molecular weight of 31 kD. The band 7.2b gene had a wide pattern of expression, with high levels of mRNA in heart, liver, skeletal muscle, and testis and low levels in lung, brain, and spleen. Using fluorescent in situ hybridization, the murine band 7.2b gene was mapped to chromosome 2, at the border of the distal region of 2B and proximal region of C1, syntenic to 9q33-q34, the location of the human homologue. Models of the predicted protein structure showed a short NH2- terminal head, a strongly hydrophobic 28-amino acid stretch presumably encoding a single membrane-spanning domain, and a large domain composed of beta sheet and alpha helix. Database searching showed no significant homology of other known proteins to murine or human band 7.2b.

scholarly journals Quantification of vibrissal mechanical properties across the rat mystacial pad

2019 ◽  
Vol 121 (5) ◽  
pp. 1879-1895 ◽  
Author(s):  
Anne En-Tzu Yang ◽  
Hayley M. Belli ◽  
Mitra J. Z. Hartmann
Keyword(s):  
Mechanical Properties ◽  
Center Of Mass ◽  
Distal Region ◽  
Density Variation ◽  
Average Density ◽  
Proximal Region ◽  
Moment Of Inertia ◽  
Radius Of Gyration ◽  
Mass Moment ◽  
Mass Moment Of Inertia

Recent work has quantified the geometric parameters of individual rat vibrissae (whiskers) and developed equations that describe how these parameters vary as a function of row and column position across the array. This characterization included a detailed quantification of whisker base diameter and arc length as well as the geometry of the whisker medulla. The present study now uses these equations for whisker geometry to quantify several properties of the whisker that govern its mechanical behavior. We first show that the average density of a whisker is lower in its proximal region than in its distal region. This density variation appears to be largely attributable to the presence of the whisker cuticle rather than the medulla. The density variation has very little effect on the center of mass of the whisker. We next show that the presence of the medulla decreases the deflection of the whisker under its own weight and also decreases its mass moment of inertia while sacrificing <1% stiffness at the whisker base compared with a solid whisker. Finally, we quantify two dimensionless parameters across the array. First, the deflection-to-length ratio decreases from caudal to rostral: caudal whiskers are longer but deflect more under their own weight. Second, the nondimensionalized radius of gyration is approximately constant across the array, which may simplify control of whisking by the intrinsic muscles. We anticipate that future work will exploit the mechanical properties computed in the present study to improve simulations of the mechanosensory signals associated with vibrissotactile exploratory behavior. NEW & NOTEWORTHY The mechanical signals transmitted by a whisker depend critically on its geometry. We used measurements of whisker geometry and mass to quantify the center of mass, mass moment of inertia, radius of gyration, and deflection under gravity of the whisker. We describe how variations in these quantities across the array could enhance sensing behaviors while reducing energy costs and simplifying whisking control. Most importantly, we provide derivations for these quantities for use in future simulation work.

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