scholarly journals Regional Phenotypic Differences of the Opener Muscle in Procambarus clarkii: Sarcomere Length, Fiber Diameter, and Force Development

Biology ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 118 ◽  
Author(s):  
Rachel C. Holsinger ◽  
Robin L. Cooper
Keyword(s):  
Sarcomere Length ◽  
Procambarus Clarkii ◽  
Fiber Diameter ◽  
Troponin T ◽  
Input Resistance ◽  
The Other ◽  
Phenotypic Differences ◽  
Synaptic Structure ◽  
Frequency Of Stimulation ◽  
40 Hz

The opener muscle in the walking legs of the crayfish (Procambarus clarkii) has three distinct phenotypic regions although innervated by only one excitatory motor neuron. These regions (distal, central, and proximal) have varied biochemistry and physiology, including synaptic structure, troponin-T levels, fiber diameter, input resistance, sarcomere length, and force generation. The force generated by the central fibers when the excitatory neuron was stimulated at 40 Hz was more than the force generated by the other regions. This increase in force was correlated with the central fibers having longer sarcomeres when measured in a relaxed claw. These data support the idea that the central fibers are tonic-like and that the proximal fibers are phasic-like. The addition of serotonin directly on the fibers was hypothesized to increase the force generated by the central fibers more than in the other regions, but this did not occur at 40-Hz stimulation. We hypothesized that the central distal fibers would generate the most force due to the arrangement on the apodeme. This study demonstrates how malleable the motor unit is with modulation and frequency of stimulation.

Physiological effects of two FMRFamide-related peptides from the crayfish Procambarus clarkii

1995 ◽  
Vol 198 (1) ◽  
pp. 109-116
Author(s):  
M Skerrett ◽  
A Peaire ◽  
P Quigley ◽  
A Mercier
Keyword(s):  
Transmitter Release ◽  
Procambarus Clarkii ◽  
Neuromuscular Junctions ◽  
Input Resistance ◽  
Physiological Effects ◽  
Synaptic Current ◽  
Extensor Muscles ◽  
Neuromuscular Systems ◽  
Dose Dependent ◽  
Measurable Change

The present study examined the effects of two recently identified neuropeptides on crayfish hearts and on neuromuscular junctions of the crayfish deep abdominal extensor muscles. The two peptides, referred to as NF1 (Asn-Arg-Asn-Phe-Leu-Arg-Phe-NH2) and DF2 (Asp-Arg-Asn-Phe-Leu-Arg-Phe-NH2), increased the rate and amplitude of spontaneous cardiac contractions and increased the amplitude of excitatory junctional potentials (EJPs) in the deep extensors. Both effects were dose-dependent, but threshold and EC50 values for the cardiac effects were at least 10 times lower than for the deep extensor effects. The heart responded equally well to three sequential applications of peptide in any given preparation, but the responses of the deep extensors appeared to decline with successive peptide applications. The results support the hypothesis that these two neuropeptides act as neurohormones to modulate the cardiac and neuromuscular systems in crayfish. Quantal synaptic current recordings from the deep extensor muscles indicate that both peptides increase the number of quanta of transmitter released from synaptic terminals. Neither peptide elicited a measurable change in the size of quantal synaptic currents. NF1 caused a small increase in muscle cell input resistance, while DF2 did not alter input resistance. These data suggest that DF2 increases EJP amplitudes primarily by increasing transmitter release, while the increase elicited by NF1 appears to involve presynaptic and postsynaptic mechanisms.

scholarly journals Impact of Sampling and Storage Techniques on Beef Muscle Measurements During Aging

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
M. Diss ◽  
W. Keller ◽  
K. Carlin
Keyword(s):  
Phosphate Buffer ◽  
Sarcomere Length ◽  
Troponin T ◽  
Colorimetric Assay ◽  
Thiobarbituric Acid ◽  
Band 3 ◽  
Posterior Portion ◽  
Aging Period ◽  
Storage Type ◽  
Beef Muscle

ObjectivesThis objective was to determine if variations in beef sampling techniques utilized by meat researchers have a significant impact on beef muscle measurements during aging.Materials and MethodsTen beef short loins (IMPS 180) were purchased from a commercial packing plant within 48 h of slaughter. Loins were transported to the NDSU Meat Science laboratory where they were mapped into four sections from most anterior (1) to most posterior (4). Within sections, two, 40-g samples were removed; one sample was vacuum packaged (SMALL-VAC) and the other sample was stored in a wire-closure sealed bag (SMALL-BAG). The remaining whole short loin was vacuum packaged. All samples and whole short loins were stored at 4°C for 10 d. At 10 d, the short loins were sampled again where one, 40-g sample was removed from each mapped section (WHOLE-VAC). Purge loss was measured by weighing each sample prior to packaging treatment and at the end of the 10-d aging period; percentage change in weight was calculated. Troponin-T degradation was determined by western blot. Briefly, protein was extracted in an SDS-phosphate buffer, separated by SDS-PAGE under reducing conditions, and transferred to PVDF membranes. Western analysis was done using an anti-troponin-T antibody (clone JLT 12), and immunoreactive bands (Band 1 = doublet ∼42 to 45 kDa; Band 2 = doublet ∼ 36 to 38 kDa, Band 3 = 30 kDa) were analyzed for differences in density. Sarcomere length was determined using HeNe laser diffraction. Thinly sliced samples (∼50 to 100 mg) were placed in a sucrose-phosphate buffer and subjected to beadmill homogenization. A drop of the homogenate was placed on a glass slide, diffraction patterns were measured, and sarcomere length was calculated. Thiobarbituric acid reactive substances (TBARS) were assessed using a colorimetric assay. Analysis was conducted using Proc Mixed procedure of SAS where storage type, section location, and their interaction were used as fixed effects.ResultsThere was a storage type by section interaction (P = 0.017) that occurred with purge loss. SMALL-VAC samples released more purge than SMALL-BAG from the more posterior samples. Troponin-T Band 1 tended to be less (P = 0.07) in WHOLE-VAC samples compared with SMALL-VAC and SMALL-BAG. There was a storage type by section interaction (P = 0.02) where the most posterior SMALL-BAG samples had greater Band 2. There were no differences (P ≥ 0.25) in Band 3 between treatments. There was no difference (P = 0.29) in sarcomere length due storage type. However, there was a difference (P = 0.01) in sarcomere length between sections, where the shortest sarcomeres were in the center of the strip loin and longest sarcomeres on either end. There was a storage type by section interaction (P = 0.02) for TBARS where concentration was greatest in the most posterior portion of SMALL-BAG compared with WHOLE-VAC.ConclusionCollection of smaller samples for aging studies may not be representative of samples aged in a whole primal cut and may influence research outcomes.

scholarly journals A Proposed Mechanism for Texture Property of Woody Breast in Broilers

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
A. Welter ◽  
W. J. Wu ◽  
T. O’Quinn ◽  
T. Houser ◽  
E. Boyle ◽  
...  
Keyword(s):  
Sarcomere Length ◽  
Troponin T ◽  
Chicken Breast ◽  
Free Calcium ◽  
Processing Plant ◽  
Breast Meat ◽  
Collagen Crosslinks ◽  
White Striping ◽  
Chicken Breast Meat ◽  
Early Postmortem

ObjectivesWoody breast is a myopathy observed in chicken breast meat (Pectoralis major) characterized by its tough and rubbery texture. However, the exact causation of woody breast texture is still unknown. We hypothesize that sarcoplasmic reticulum (SR) dysfunctionality early postmortem results in rapid leakage of intracellular calcium may partially contribute to the abnormal meat texture observed in woody breast meat. The objective of this preliminary study was to investigate this hypothesis.Materials and MethodsFourteen Ross line broiler breast fillets (7 severe woody breast and 7 normal) were collected at 3 h postmortem from a commercial processing plant located in the southeast United States. The 7 woody breast samples also exhibited moderate to severe white striping. The 7 normal samples did not exhibit any signs of white striping or woody breast. Each sample was trimmed, weighed, vacuum packaged and frozen at –20°C at approximately 8 h postmortem. One 1.9 cm strip across the cranial end of each fillet was fabricated and pulverized in liquid nitrogen to measure sarcomere length (Laser Scan Confocal Microscope with a 100x/NA 1.4 objective), calpain activity (immunoblotting for µ-calpain autolysis), proteolysis (immunoblotting for troponin-T degradation) and collagen content (hydroxyproline content). Purge was also collected from each sample to evaluate protein (bicinchoninic acid assay) and free calcium concentration (atomic absorption).ResultsWoody breast fillets were heavier than normal chicken breast fillets (522.9 vs. 446.9g; P < 0.05). Woody breast samples tended to have shorter sarcomeres (1.70 vs. 2.02 µm; P = 0.0543) and less intact troponin-T compared to normal breast samples (relative intact troponin-T band density: 49.98 vs. 56.97%; P = 0.0515) at 8 h postmortem. It was interesting to note that no µ-calpain band was detected through immunoblotting for both the woody breast and normal samples at 8 h postmortem. Other studies have found similar results as poultry µ-calpain autolyzed at a much rapid rate than µ-calpain in mammalian species. In addition, the purge from woody breast samples also had higher levels of free calcium compared to normal samples (6.2 vs. 4.2 nmol calcium/mg protein; P < 0.05). Lastly, there was more collagen present in the woody breast samples compared to normal chicken breast samples (3.89 vs. 2.08 mg collagen/g muscle tissue; P < 0.05).ConclusionThe results indicated that the cause of texture abnormality of woody breast may be the combined effects of more calcium being released from the SR early postmortem resulting in shorter sarcomere length and more collagen being deposited in the chicken breast meat. Additional research with the focus on SR integrity and functionality as well as collagen crosslinks are needed to further elucidate the basic mechanism of woody breast texture formation.

scholarly journals The Impacts of Feeding Natursafe (an Immune Support Product) on Beef Quality

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
M. Henriott ◽  
K. Hart ◽  
N. Herrera ◽  
F. Ribeiro ◽  
N. Bland ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Beef Cattle ◽  
Meat Quality ◽  
Shear Force ◽  
Sarcomere Length ◽  
Troponin T ◽  
Quality Characteristics ◽  
Insoluble Collagen ◽  
Plate Counts ◽  
Retail Display

ObjectivesNaturSafe® (Diamond V, USA) is a Saccharomyces cerevisiae fermentation product developed as an animal feed supplement for the further manufacture of nutritionally balanced feeds for beef cattle. This immune support product (Association of American Feed Control Officials number 96.8, 73.046 and International Feed Name number 7–05–520, 8–08–034) has been specifically formulated to optimize beef cattle health and performance, antibiotic stewardship, and food safety. Research has shown that NaturSafe supports optimal rumen and liver health, overall health and immune function, consistency of feed intake, daily gain, feed conversion, and antibiotic effectiveness. As no research previously has assessed the impacts of this feed ingredient on the quality of meat, the objective of this research was to characterize the effects of feeding NaturSafe on meat quality characteristics in beef.Materials and MethodsCrossbred steers (N = 60, n = 12 per treatment; mean hot carcass weight = 421 kg), through an antibiotic free production system, were individually fed diets containing 12, 15, or 18 g/d of NaturSafe or a control diet without (–AB) antibiotics or a control with antibiotics (+AB; 330 mg monensin + 110 mg tylosin·steer–1·d–1) for 112 d. Strip loins were collected and aged for 13 or 29 d postmortem prior to fabrication. Steaks (m. Longissimus) were then evaluated for Warner-Bratzler shear force, pH, sarcoplasmic calcium concentration, troponin-T degradation, fatty acid profile, proximate composition, sarcomere length, total collagen and insoluble collagen. After each aging period, steaks were evaluated for lipid oxidation, and color characteristics (L*, a*, b*, discoloration percentage, and percentage surface oxymyoglobin, metmyoglobin and deoxymyoglobin), during and/or after a 7 d simulated retail display period. A subset of samples at various aging and retail display periods were analyzed for lactic acid bacteria (LAB), psychotrophic plate counts (PPC), and aerobic plate counts (APC). Animal was considered the experimental unit and hot carcass weight and marbling score were used as covariates in the analysis.ResultsTreatment had no effect on pH, sarcomere length, troponin-T degradation, fatty acid profile, proximate composition, total collagen, insoluble collagen, LAB, PPC, APC, lipid oxidation, oxymyoglobin percentage, or metmyoglobin percentage. Meat from cattle fed 18 g/d of NaturSafe was (1) equal to–AB controls and had higher shear force values compared to all other treatments (P < 0.01), (2) had higher (P < 0.05) sarcoplasmic calcium levels than +AB controls and cattle fed 12 g of NaturSafe/d, (3) was redder (higher a* values, P < 0.05) than all other treatments, and (4) was yellower (higher b* values, P < 0.01) than the 12 or 15 g dose and the–AB control. There were no differences among treatments fed NaturSafe for lightness (L*) at either aging time. There were no differences for meat from animals fed 12 or 15 g NatureSafe/d, except deoxymyoglobin percent and discoloration, which were both minimal. Discoloration values were low for all treatments (< 10%).ConclusionThese data indicate that feeding NaturSafe had few discernible effects on meat quality characteristics.

Lanthanum penetration in crayfish nervous system: observations on intact and ‘desheathed’ preparations

1977 ◽  
Vol 23 (1) ◽  
pp. 315-324
Author(s):  
N.J. Lane ◽  
L.S. Swales ◽  
N.J. Abbott
Keyword(s):  
Nervous System ◽  
Glial Cells ◽  
Peripheral Nerves ◽  
Procambarus Clarkii ◽  
Physiological Saline ◽  
The Other ◽  
Major Site ◽  
Electrophysiological Studies ◽  
Cell Processes ◽  
Tubular Lattice

Central neural connectives and peripheral nerves from the crayfish Procambarus clarkii were incubated in 5 mM lanthanum solutions in physiological saline, for periods from 15 min to 2 h. The tracer only rarely reaches the axon surfaces in the perineurium-ensheathed connectives, penetrating the elaborate perineurial layer slowly. In peripheral nerves, on the other hand, where the perineurium is extermely attenuated and interrupted by open extracellular clefts, inward movement of lanthanum to the axon surfaces occurs readily. When the perineurial layer of the neural connectives is removed by ‘desheathing’, penetration of the tracer to the level of the axolemma occurs rapidly, implicating the perineurium as the major site of restriction of entry of large ions and exogenous molecules. This conclusion is discussed in relation to recent electrophysiological studies on K+ movements. In both peripheral nerves and desheathed connectives, the transcellular tubular lattice system present in crustacean glial cells appears to serve as a route for the entry of tracer to the axon surfaces, and is more direct than the long and complex extracellular pathway formed by the interdigitations of the extensive glial cell processes.

scholarly journals Hypertrophic cardiomyopathy mutation in cardiac troponin T (R95H) attenuates length-dependent activation in guinea pig cardiac muscle fibers

2017 ◽  
Vol 313 (6) ◽  
pp. H1180-H1189 ◽  
Author(s):  
Alexis V. Mickelson ◽  
Murali Chandra
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Guinea Pig ◽  
Central Region ◽  
Cardiac Troponin ◽  
Sarcomere Length ◽  
Troponin T ◽  
Cardiac Troponin T ◽  
Cross Bridge ◽  
Cardiac Muscle Fibers ◽  
Length Dependent Activation

The central region of cardiac troponin T (TnT) is important for modulating the dynamics of muscle length-mediated cross-bridge recruitment. Therefore, hypertrophic cardiomyopathy mutations in the central region may affect cross-bridge recruitment dynamics to alter myofilament Ca2+ sensitivity and length-dependent activation of cardiac myofilaments. Given the importance of the central region of TnT for cardiac contractile dynamics, we studied if hypertrophic cardiomyopathy-linked mutation (TnTR94H)-induced effects on contractile function would be differently modulated by sarcomere length (SL). Recombinant wild-type TnT (TnTWT) and the guinea pig analog of the human R94H mutation (TnTR95H) were reconstituted into detergent-skinned cardiac muscle fibers from guinea pigs. Steady-state and dynamic contractile measurements were made at short and long SLs (1.9 and 2.3 µm, respectively). Our results demonstrated that TnTR95H increased pCa50 (−log of free Ca2+ concentration) to a greater extent at short SL; TnTR95H increased pCa50 by 0.11 pCa units at short SL and 0.07 pCa units at long SL. The increase in pCa50 associated with an increase in SL from 1.9 to 2.3 µm (ΔpCa50) was attenuated nearly twofold in TnTR95H fibers; ΔpCa50 was 0.09 pCa units for TnTWT fibers but only 0.05 pCa units for TnTR95H fibers. The SL dependency of rate constants of cross-bridge distortion dynamics and tension redevelopment was also blunted by TnTR95H. Collectively, our observations on the SL dependency of pCa50 and rate constants of cross-bridge distortion dynamics and tension redevelopment suggest that mechanisms underlying the length-dependent activation cardiac myofilaments are attenuated by TnTR95H. NEW & NOTEWORTHY Mutant cardiac troponin T (TnTR95H) differently affects myofilament Ca2+ sensitivity at short and long sarcomere length, indicating that mechanisms underlying length-dependent activation are altered by TnTR95H. TnTR95H enhances myofilament Ca2+ sensitivity to a greater extent at short sarcomere length, thus attenuating the length-dependent increase in myofilament Ca2+ sensitivity.

Two distinct inhibitory responses of cultured, mammalian spinal neurones to ibotenic acid

1980 ◽  
Vol 58 (9) ◽  
pp. 1135-1137 ◽  
Author(s):  
John Ferguson MacDonald ◽  
Jeffery L. Barker
Keyword(s):  
Amino Acid ◽  
Input Resistance ◽  
Ibotenic Acid ◽  
The Other ◽  
Aminobutyric Acid ◽  
Ionic Mechanism ◽  
Structural Analogue ◽  
Membrane Hyperpolarization ◽  
Excitatory Response ◽  
Spinal Neurones

Ibotenic acid, a structural analogue of glutamic acid, was applied to mouse spinal neurones grown in dissociated cultures. This amino acid evoked two inhibitory responses in addition to an excitatory response. Both inhibitory responses were manifested by membrane hyperpolarization and decreased input resistance. However, one was long-lasting (in excess of periods of 1 h) in comparison with the other. The latter response was likely a consequence of an increased chloride conductance and was sensitive to the γ-aminobutyric acid antagonists bicuculline and picrotoxin whereas the former response was insensitive to these drugs. The ionic mechanism of this long-lasting response has yet to be elucidated.

scholarly journals Insulin-Like Growth Factor I (IGF-I) Receptor Overexpression Abolishes the IGF Requirement for Differentiation and Induces a Ligand-Dependent Transformed Phenotype in C2 Inducible Myoblasts*

Endocrinology ◽  
1997 ◽  
Vol 138 (12) ◽  
pp. 5210-5219 ◽  
Author(s):  
Magali Navarro ◽  
Bruno Barenton ◽  
Veronique Garandel ◽  
Juergen Schnekenburger ◽  
Henri Bernardi
Keyword(s):  
Growth Factors ◽  
Troponin T ◽  
Soft Agar ◽  
Specific Protein ◽  
Eukaryotic Expression ◽  
Type I ◽  
Phenotypic Differences ◽  
Human Type ◽  
Type I Igf Receptor ◽  
Igf I

Abstract Insulin-like growth factors (IGFs) stimulate both proliferation and differentiation of myogenic cell lines, and these actions are mostly mediated through the type I IGF receptor (type I IGF-R). To further investigate the role of this receptor in phenotypic characteristics of C2 murine myoblasts, we overexpressed the human type I IGF-R in the inducible clone of C2 cells, which requires IGFs in the differentiation medium to undergo terminal differentiation. Inducible myoblasts were transfected with either the eukaryotic expression vector pNTK or pNTK containing the human type I IGF-R complementary DNA, and we isolated two clones named Ind-Neo and Ind-R, respectively. Binding and autophosphorylation experiments indicate that Ind-R cells express about 10 times as much type I IGF-R compared with Ind-Neo control cells and that the transfected type I IGF-R is functional in Ind-R cells. We show that overexpression of the human type I IGF-R makes inducible myoblasts able to differentiate spontaneously, as assessed by expression of the myogenic transcription factors MyoD and myogenin, detection of the muscle-specific protein troponin T, and myotube formation. Moreover, when exposed to IGF-I, Ind-R cells lose contact inhibition, grow in the presence of a low level of growth factors and form colonies in soft agar, which is characteristic of a ligand-dependent transformed phenotype. It emerges from this study that 1) the type I IGF-R is strongly involved in the phenotypic differences between inducible and permissive cells with respect to the differentiation program; and 2) overexpression causes this receptor to act as a ligand-dependent transforming protein in muscle cells. We suggest that type I IGF-R abundance and level of activation may determine the efficiency of the autocrine mode of action of IGFs and discriminate their biological functions.

Experimental Study of Melt Electrospinning in Parallel Electrical Field

2011 ◽  
Vol 221 ◽  
pp. 111-116 ◽  
Author(s):  
Ming Feng Hao ◽  
Yong Liu ◽  
Xue Tao He ◽  
Peng Cheng Xie ◽  
Wei Min Yang
Keyword(s):  
Experimental Study ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Melt Spinning ◽  
Fiber Diameter ◽  
The Other ◽  
Electrical Field ◽  
Melt Electrospinning ◽  
Plate Area

In this paper, self-designed electrospinning equipment was used to make a series of electrospinning experiments with materials of polypropylene. The influences of the receiver area, the upper plate area, and the overlapping area between the receiver and the upper plate, on the melt spinning electric field, the spinning efficiency, and the fiber diameter, were investigated respectively. The results showed that when the other parameters were kept unchanged, with the increase of the receiver’s diameter, the electric field strength and spinning efficiency increased, and the fiber diameter increased at first and then decreased; the bigger the overlapping area between the receiver and the upper plate, the more stable the vertical spinning path.

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