Insoluble Collagen Research Articles

Extraction of soluble collagen and its feasibility in the palaeodietary research

In current palaeodietary research, gelatinization is the main method to extract insoluble collagen (ISC) from ancient bones. However, the degradation products of ISC, i.e., soluble collagen (SC), is often neglected and abandoned. In this work, we try to separate the extracts of ancient bones using gel chromatography and compare the contents of carbon and nitrogen, atomic C/N ratio, and stable carbon and nitrogen isotopic values of the extracts from three peaks to determine which peak can be attributed to SC. At last, the potential application of SC in palaeodietary research is discussed based on the comparison of stable isotopic values between ISC and SC. Among the three peaks, the second with the retention time between 17.5 min and 27.5 min had the most broad peak shape, indicating that the molecular weights of proteins collected were most variable. Besides, the contents of carbon and nitrogen and atomic C/N ratio of extracts in this peak were closest to the corresponding ISC. Based on the above, we conclude that the extract in second peak is SC. More important, the delta C-13 and delta N-15 values of ISC and SC are very similar. For ISC and SC with atomic C/N ratios within the normal range (2.9-3.6), the mean difference of delta C-13 value was only (0.3 +/- 0.2)aEuro degrees (n=2) while delta N-15 value was (0.6 +/- 0.1)aEuro degrees (n=2). Although the atomic C/N ratios of some SC are slightly beyond the normal range, the mean differences of delta C-13 and delta N-15 values were still only (0.4 +/- 0.1)aEuro degrees and (0.3 +/- 0)aEuro degrees (n=2) respectively. These isotopic differences are quite below the isotope fractionation in one trophic level (delta C-13 values of 1aEuro degrees aEuro"1.5aEuro degrees and delta N-15 values of 3aEuro degrees aEuro"5aEuro degrees), suggesting that SC had great application potentials in palaeodietary research.

Characterization of a Novel Subtilisin-like Protease Myroicolsin from Deep Sea Bacterium Myroides profundi D25 and Molecular Insight into Its Collagenolytic Mechanism

Collagen is an insoluble protein that widely distributes in the extracellular matrix of marine animals. Collagen degradation is an important step in the marine nitrogen cycle. However, the mechanism of marine collagen degradation is still largely unknown. Here, a novel subtilisin-like collagenolytic protease, myroicolsin, which is secreted by the deep sea bacterium Myroides profundi D25, was purified and characterized, and its collagenolytic mechanism was studied. Myroicolsin displays low identity (<30%) to previously characterized subtilisin-like proteases, and it contains a novel domain structure. Protein truncation indicated that the Pro secretion system C-terminal sorting domain in the precursor protein is involved in the cleavage of the N-propeptide, and the linker is required for protein folding during myroicolsin maturation. The C-terminal β-jelly roll domain did not bind insoluble collagen fiber, suggesting that myroicolsin may degrade collagen without the assistance of a collagen-binding domain. Myroicolsin had broad specificity for various collagens, especially fish-insoluble collagen. The favored residue at the P1 site was basic arginine. Scanning electron microscopy and atomic force microscopy, together with biochemical analyses, confirmed that collagen fiber degradation by myroicolsin begins with the hydrolysis of proteoglycans and telopeptides in collagen fibers and fibrils. Myroicolsin showed strikingly different cleavage patterns between native and denatured collagens. A collagen degradation model of myroicolsin was proposed based on our results. Our study provides molecular insight into the collagen degradation mechanism and structural characterization of a subtilisin-like collagenolytic protease secreted by a deep sea bacterium, shedding light on the degradation mechanism of deep sea sedimentary organic nitrogen.

Bone embrittlement and collagen modifications due to high-dose gamma-irradiation sterilization

Bone allografts are often used in orthopedic reconstruction of skeletal defects resulting from trauma, bone cancer or revision of joint arthroplasty. γ-Irradiation sterilization is a widely-used biological safety measure; however it is known to embrittle bone. Irradiation has been shown to affect the post-yield properties, which are attributed to the collagen component of bone. In order to find a solution to the loss of toughness in irradiated bone allografts, it is important to fully understand the effects of irradiation on bone collagen. The objective of this study was to evaluate changes in the structure and integrity of bone collagen as a result of γ-irradiation, with the hypothesis that irradiation fragments collagen molecules leading to a loss of collagen network connectivity and therefore loss of toughness.Using cortical bone from bovine tibiae, sample beams irradiated at 33kGy on dry ice were compared to native bone beams (paired controls). All beams were subjected to three-point bend testing to failure followed by characterization of the decalcified bone collagen, using differential scanning calorimetry (DSC), hydrothermal isometric tension testing (HIT), high performance liquid chromatography (HPLC) and gel electrophoresis (SDS-PAGE). The carbonyl content of demineralized bone collagen was also measured chemically to assess oxidative damage. Barium sulfate staining after single edge notch bending (SEN(B)) fracture testing was also performed on bovine tibia bone beams with a machined and sharpened notch to evaluate the fracture toughness and ability of irradiated bone to form micro-damage during fracture.Irradiation resulted in a 62% loss of work-to-fracture (p≤0.001). There was significantly less micro-damage formed during fracture propagation in the irradiated bone. HPLC showed no significant effect on pentosidine, pyridinoline, or hydroxypyridinoline levels suggesting that the loss of toughness is not due to changes in these stable crosslinks. For DSC, there was a 20% decrease in thermal stability (p<0.001) with a 100% increase (p<0.001) in enthalpy of denaturation (melting). HIT testing also showed a decrease in thermal stability (20% lower denaturation temperature, p<0.001) and greatly reduced measures of collagen network connectivity (p<0.001). Interestingly, the increase in enthalpy of denaturation suggests that irradiated collagen requires more energy to denature (melt), perhaps a result of alterations in the hydrogen bonding sites (increased carbonyl content detected in the insoluble collagen) on the irradiated bone collagen.Altogether, this new data strongly indicates that a large loss of overall collagen connectivity due to collagen fragmentation resulting from γ-irradiation sterilization leads to inferior cortical bone toughness. In addition, notable changes in the thermal denaturation of the bone collagen along with chemical indicators of oxidative modification of the bone collagen indicate that the embrittlement may be a function not only of collagen fragmentation but also of changes in bonding.

Hypertension and cardiovascular remodelling in rats exposed to continuous light: protection by ACE-inhibition and melatonin.

Exposure of rats to continuous light attenuates melatonin production and results in hypertension development. This study investigated whether hypertension induced by continuous light (24 hours/day) exposure induces heart and aorta remodelling and if these alterations are prevented by melatonin or angiotensin converting enzyme inhibitor captopril. Four groups of 3-month-old male Wistar rats (10 per group) were treated as follows for six weeks: untreated controls, exposed to continuous light, light-exposed, and treated with either captopril (100 mg/kg/day) or melatonin (10 mg/kg/day). Exposure to continuous light led to hypertension, left ventricular (LV) hypertrophy and fibrosis, and enhancement of the oxidative load in the LV and aorta. Increase in systolic blood pressure by continuous light exposure was prevented completely by captopril and partially by melatonin. Both captopril and melatonin reduced the wall thickness and cross-sectional area of the aorta and reduced the level of oxidative stress. However, only captopril reduced LV hypertrophy development and only melatonin reduced LV hydroxyproline concentration in insoluble and total collagen in rats exposed to continuous light. In conclusion, captopril prevented LV hypertrophy development in the continuous light-induced hypertension model, while only melatonin significantly reduced fibrosis. This antifibrotic action of melatonin may be protective in hypertensive heart disease.

Combined anticalcification treatment of bovine pericardium with decellularization and hyaluronic acid derivative

The objective of this work was to evaluate the effect of decellularization and hyaluronic acid derivative on the improvement of anticalcification of glutaraldehyde fixed bovine pericardium (GFBP) using a rat subcutaneous implantation model A cell extraction process was employed to remove the cells and cellular components from bovine pericardium (BP), leaving a framework of largely insoluble collagen. Then acellular BP was cross-linked by glutaraldehyde solution and treated with hyaluronic acid derivative (HA-ADH) which was obtained by coupling adipic dihydrazide (ADH) on-COOH of hyaluronic acid (HA). The results of in vivo calcification tests showed that the calcium content was decreased dramatically by decellularization alone (from 28.07 ± 18.87 to 2.44 ± 0.55 μg Ca/mg dry tissue after 8 weeks' implantation), and even less concentration was shown by the combination of HA derivative treatment and decellularization (GFaBP-HA group) (0.25 ± 0.08 μg Ca/mg dry tissue after 8 weeks' implantation). In addition, GFaBP-HA group not only presented a lower degree of calcification, but also showed lower ratios of Ca/P molar, which corresponded to amorphous calcium phosphates. The obtained results indicated that GFaBP-HA was a potential candidate for the manufacture of anticalcification bioprostheses.

Poroviscoelastic finite element model including continuous fiber distribution for the simulation of nanoindentation tests on articular cartilage

Articular cartilage is a soft hydrated tissue that facilitates proper load transfer in diarthroidal joints. The mechanical properties of articular cartilage derive from its structural and hierarchical organization that, at the micrometric length scale, encompasses three main components: a network of insoluble collagen fibrils, negatively charged macromolecules and a porous extracellular matrix. In this work, a constituent-based constitutive model for the simulation of nanoindentation tests on articular cartilage is presented: it accounts for the multi-constituent, non-linear, porous, and viscous aspects of articular cartilage mechanics. In order to reproduce the articular cartilage response under different loading conditions, the model considers a continuous distribution of collagen fibril orientation, swelling, and depth-dependent mechanical properties. The model's parameters are obtained by fitting published experimental data for the time-dependent response in a stress relaxation unconfined compression test on adult bovine articular cartilage. Then, model validation is obtained by simulating three independent experimental tests: (i) the time-dependent response in a stress relaxation confined compression test, (ii) the drained response of a flat punch indentation test and (iii) the depth-dependence of effective Poisson's ratio in a unconfined compression test.Finally, the validated constitutive model has been used to simulate multiload spherical nanoindentation creep tests. Upon accounting for strain-dependent tissue permeability and intrinsic viscoelastic properties of the collagen network, the model accurately fits the drained and undrained curves and time-dependent creep response. The results show that depth-dependent tissue properties and glycosaminoglycan-induced tissue swelling should be accounted for when simulating indentation experiments.

Comparison of some physicochemical properties and toughness of camel meat and beef

The objective of this study was to identify factors influencing the toughness of longissimus dorsi (LD) and psoas major (PM) muscles of camel and to compare it with that of beef. Total collagen content was slightly higher, whereas insoluble collagen content was significantly higher in muscles of older animals. The Warner-Bartzler shear force (WBSF) value was significantly (P<0.05) higher for camel meat than beef, and this value increased with age in camel meat. Significant correlations between insoluble collagen content and WBSF were found in camel meat (r=0.850; P<0.01) and beef (r=0.643; P <0.05). Sarcomere length was numerically higher in muscles of younger than older animals. Camel meat had significantly higher pH values than beef at 6 and 24 h post-slaughter and the LD and PM muscles of younger animals had a significant higher pH values than older ones.

Effects of High Pressure/High Temperature Processing on the Recovery and Characteristics of Porcine Placenta Hydrolysates

This study was performed to investigate the effects of high pressure/high temperature (HPHT) treatment on the recovery efficiency and characteristics of porcine placenta hydrolysates. The placenta hydrolysates were characterized by solubility, free amino acid contents, gel electrophoresis, gel permeation chromatography (GPC) and amino acid composition. Placenta was treated at 37.5 MPa of pressure combined with various temperatures (150, 170, and <TEX>$200^{\circ}C$</TEX>) or various holding times (0, 30, and 60 min at <TEX>$170^{\circ}C$</TEX>). Insoluble raw placenta collagen was partially solubilized (> 60% solubility) by the HPHT treatment. Free amino group content of placenta collagen was increased from 0.1 mM/g collagen to > 0.3 mM/g collagen after HPHT treatment, reflecting partial hydrolysis of collagen. The molecular weight (<TEX>$M_w$</TEX>) distribution showed evidence of collagen hydrolysis by shifting of <TEX>$M_w$</TEX> peaks toward low molecular weight when treated temperature or holding time was increased. Alanine (Ala), glycine (Gly), hydroxyproline (Hyp), and proline (Pro) contents increased after the HPHT treatments compared to a decrease in the others. In particular, the increase in Gly was obvious, followed by Hyp and Pro, reflecting that placenta hydrolysates were mainly composed of these amino acids. However, increasing temperature or holding time hardly affected the amino acid compositions. These results indicate that the HPHT treatment is advantageous to hydrolyze collagen derived from animal by-products.

Isolation of collagen from tiger pufferfish parts and its solubility in dilute acetic acid

Collagen was extracted from several tissues (muscle, skin, bone, alimentary tract, gill, fin, hepatopancreas, and air bladder) of the tiger pufferfish Takifugu rubripes, and the content and solubility of the collagen extracted from each tissue were examined. Collagen content in ordinary muscle was 0.95 ± 0.07 % of wet tissue, which is lower than that reported for other fish species even though tiger pufferfish meat has a tough texture. The solubility of collagen extracted from the muscle and skin was relatively high, and collagen accounted for 47.2 ± 7.8 and 70.8 ± 8.1 % of wet tissue, respectively. In contrast, the solubility of the collagen extracted from bone was the lowest of all the tissues examined, being only 5.7 ± 0.8 % of total wet tissue. The extent of hydroxylation of proline and lysine residues was also examined. In most tissues, the extent of hydroxylation of the lysine residue in insoluble collagen was higher than that of acid-soluble collagen, indicating that hydroxylysine contributes to the stability of collagen. This is the first report of collagen contents, solubility, and extent of hydroxylation of proline and lysine residues in collagen extracted from different tissues of one organism. It is possible that hydroxylysine-derived collagen cross-links play a critical role in the stability of collagen in dilute acetic acid.

SB216763, a selective small molecule inhibitor of glycogen synthase kinase-3, improves bleomycin-induced pulmonary fibrosis via activating autophagy

An excessive accumulation of extracellular matrix composed by insoluble collagen is the core pathogenic change of fibroproliferative diseases including pulmonary fibrosis. We recently found that autophagy, a self-catabolic process that maintains intracellular homeostasis, participates critically in the regulation of collagen degradation in the fibrotic tissues. Here we report that treatment of mice with SB216763, a potent and selective inhibitor of glycogen synthase kinase-3 (GSK3), significantly decreased the bleomycin (BLM)-induced acute inflammation, attenuated pulmonary fibrosis, improved the lung function and increased animal survival through activating autophagy. Indeed, we found that treatment of mice or cultured cells with SB216763 restored the autophagy in vivo and in vitro through increasing the expression of autophagy related proteins and decreasing the physical interaction of Bcl-2 and Beclin-1. Additionally, SB216763 stimulated the binding of Bcl-2 and GSK3, which reduces the interaction of Bcl-2 and Beclin-1. We conclude that the GSK3 inhibitor SB216763 improves the BLM-induced pulmonary fibrosis through stimulating autophagy core complex to restore the activity of autophagy in fibrotic lung tissue. Our work suggests that using a moderate autophagic agonist, such as SB216763, is a promising therapeutic strategy for the treatment of devastating fibroproliferative diseases such as idiopathic pulmonary fibrosis.

Comparison of quality traits of meat from korean native chickens and broilers used in two different traditional korean cuisines.

With the aim of investigating the differences in the quality traits between Korean native chicken (Hanhyup, KNC) and broilers commonly used in two different traditional Korean cuisines, the chemical composition and sensory properties of breast and thigh meat from the two chicken strains were assessed. KNC for baeksuk (chicken meat braised in soup with various Oriental medicinal plants; KNL), KNC for samgyetang (similar to baeksuk but young chickens and ginseng are used; KNS), broiler for baeksuk (BL), and broiler for samgyetang (BS) were used as treatments in this study. KNL and KNS contained higher protein but lower fat content than BL and BS. The L* values of breast and thigh meat, but not the a* values, were significantly different between KNS and BS, whereas significant differences in both values were observed between KNL and BL. Compared to the other three types of chickens, KNS contained the highest total and insoluble collagen content, and KNL and BL showed higher inosine-5’-monophosphate content in their meat. Overall, KNL and KNS contributed darker, less tender meat with higher protein and less fat content together with more n-3 fatty acids, as opposed to their counterparts used for the same cuisines. Based on the results of the sensory analysis, even though there are some differences in physiochemical traits, different chicken sources do not differ in overall sensory quality. This information can help consumers to understand better the meat available for their preferred traditional cuisines.

Meta-analysis of the relationships between beef tenderness and muscle characteristics

Beef tenderness is characterised by a high and uncontrolled variability which depends, at least in part, on differences in muscle characteristics. The aim of this work was to identify general relationships between beef tenderness and muscle characteristics across experiments, using a large set of data available in the BIF-Beef (Integrated and Functional Biology of Beef) database. Tenderness was evaluated by sensory methods with trained panellists and by shear force measurements. Total and insoluble collagen contents, intramuscular fat content (IMF), mean cross sectional fibre area, isocitrate dehydrogenase (ICDH) and lactate dehydrogenase (LDH) activities and the proportion of slow oxidative (SO), fast oxido-glycolytic (FOG) and fast glycolytic (FG) muscle fibres were measured in both Longissimus thoracis (LT) and Semitendinosus (ST) muscles. Total collagen content, IMF content, mean muscle fibre area, LDH and ICDH activities explained respectively, 2%, 0.3%, 1.8%, 1.6% and 1.7% maximum of the variability (r²) in the sensory tenderness score. The total and insoluble collagen contents, the LDH activity and the FG proportion explained, respectively, 6%, 6%, 4% and 5% of the variability in the shear force, essentially in the ST muscle but not in LT muscle. The relationships between different muscle characteristics were confirmed. It was demonstrated that the determinism of tenderness was complex and mainly muscle dependant. The large data set used allowed the statement of general laws and contributed to explain the divergent results in the literature from smaller sets of data originating from specific experiments.

Osteopontin-mediated myocardial fibrosis in heart failure: a role for lysyl oxidase?

We investigated whether the pro-fibrotic matricellular protein osteopontin (OPN) is associated with the enzymes involved in the extracellular synthesis of fibril-forming collagen type I (i.e. procollagen C-proteinase, PCP) and its cross-linking to form insoluble fibrils (i.e. lysyl oxidase, LOX) in heart failure (HF) of hypertensive origin. OPN, PCP, and LOX were assessed by histochemical and molecular methods in the myocardium of 21 patients with hypertensive heart disease (HHD) and HF. Whereas the myocardial expression of OPN was very scarce in control hearts (n = 10), it was highly expressed in HF patients (P < 0.0001). OPN was directly correlated with LOX (r = 0.460, P = 0.041), insoluble collagen (r = 0.534, P = 0.015), pulmonary capillary wedge pressure (r = 0.558; P = 0.009), and left-ventricular (LV) chamber stiffness (r = 0.458, P = 0.037), and inversely correlated with LV ejection fraction (r = -0.513, P = 0.017) in all patients. OPN did not correlate with PCP and other parameters assessing collagen synthesis by fibroblasts or degradation by matrix metalloproteinases. In vitro studies showed that OPN significantly (P < 0.05) increases the expression and activity of LOX in human cardiac and dermal fibroblasts. An excess of OPN is associated with increased LOX and insoluble collagen, as well as with LV stiffness and systolic dysfunction in patients with HHD and HF. In addition, OPN up-regulates LOX in human fibroblasts. It is suggested that the OPN-LOX axis might facilitate the formation of insoluble collagen (i.e. stiff and resistant to degradation) and the subsequent alteration in LV mechanical properties and function in patients with HHD and HF.

Biomechanical Properties and Correlation With Collagen Solubility Profile in the Posterior Sclera of Canine Eyes With anADAMTS10Mutation

We examined the biomechanical properties and correlation with the collagen solubility profile of the posterior sclera in a canine model of primary open-angle glaucoma caused by the G661R missense mutation in the ADAMTS10 gene. Scleral strips from ADAMTS10-mutant (affected) dogs and age-matched controls were collected. Viscoelastic properties (i.e., complex modulus and tan[δ]) were measured using dynamic mechanical analysis (DMA) with a 0.15% sinusoidal strain at different frequencies superimposed upon different preloads. A tensile ramp was performed following DMA. The collagen solubility profile was examined using a colorimetric hydroxyproline assay to determine the amount of soluble and insoluble collagen. The viscoelastic properties were compared between groups using linear mixed models for repeated measures at different preloads and frequencies. The correlation between the biomechanical properties and collagen content were evaluated using Pearson correlations. Complex modulus and tan(δ) were significantly lower in the affected group (P < 0.001), and the differences were consistent at different preloads and frequencies. The B value from the tensile ramp test also was significantly lower in the affected group (P = 0.02). The insoluble collagen was significantly lower in the affected group (P < 0.05) and correlated positively with the complex modulus (R = 0.88, P < 0.005). An inherently weaker and biochemically distinct posterior sclera was observed in dogs with the G661R missense mutation in ADAMTS10 before clinical indications of optic nerve damage. It remains to be shown whether and how the altered scleral biomechanics may affect the rate of glaucoma progression following intraocular pressure elevation.

Cardiac fibrosis and diastolic dysfunction are highly correlated in a mouse chronic pressure‐overload model

The purpose of this study was to determine which measurements of diastolic dysfunction are most correlated with cardiac fibrosis. Mice were subjected to Sham (n=7) or transverse aortic constriction (TAC, n=6) for 10 weeks, examined by speckle‐tracking echocardiography and left ventricle (LV) pressure catheter, and portions of the LV were processed for biomarkers and histological analysis. In TAC mice as compared to Sham, Masson's Trichrome staining revealed an increase in fibrosis by 800% (P&lt;0.01); with the majority of the collagen located in the mid‐wall of the myocardium. LV insoluble collagen hydroxyproline (HDXP) increased by 99% (P&lt;0.01); and the collagen cross‐linker pyridinoline (PYD) increased by 100% (P&lt;0.001). Tau was increased by 46% (P&lt;0.01) and diastolic radial and circumferential strain rates were decreased by 41% and 44%, respectively (both P&lt;0.01). The correlations between PYD and diastolic dysfunction were: r = 0.79, 0.76, and 0.85 for Tau, radial and circumferential strain rates, respectively. Similar correlations were observed for HDXP and diastolic dysfunction. In summary, cardiac fibrosis and diastolic dysfunction are highly correlated in the mouse TAC model with diastolic circumferential strain rate better correlated with cardiac fibrosis, possibly due to the majority of the fibrosis being located in the mid‐wall, where myofibers are aligned circumferentially.

Chemical and Thermal Properties of Freshwater Prawn (Macrobrachium rosenbergii) Meat

Chemical compositions and thermal properties of cultured freshwater prawn meat (FPM) were studied. FPM contained 83.2% protein (dry basis), 62.7% of which was myofibrillar protein. Pepsin-soluble collagen (PSC) and insoluble collagen (ISC) contents were 0.63 and 0.32%, respectively. Both collagens were similar to type V collagen from porcine placenta. Glutamic acid/glutamine, arginine, aspartic acid/ asparagine, and lysine were abundant amino acids in FPM. Glycine, proline, hydroxyproline, and aspartic acid/ asparagine were predominant in both collagens. FPM exhibited thermal transition temperatures (Tmax) of 48.3 and 64.7°C, whereas Tmax of PSC and ISC were 43.0 and 46.0°C, respectively. Textural changes in FPM during post-mortem storage on ice are plausibly dependent upon its compositional and thermal properties.

Impact of animal and management factors on collagen characteristics in beef: a meta-analysis approach

The aim of this paper was to identify pre-slaughter factors that modify total and insoluble collagen contents in bovine muscle to construct a model of collagen dynamics. The meta-analyses were performed with primary data of total (n = 1165) and insoluble (n = 1145) collagen contents from INRA experiments obtained from different muscles in young bulls, cows and steers. According to both the bibliography and meta-analyses, total collagen content and solubility were greatly affected by the muscle (type). Moreover, the pattern of the evolution of collagen characteristics was similar among Longissimus, Semitendinosus and Triceps brachii muscles in young bulls. In cows, collagen contents in the Triceps brachii muscle had delayed dynamics compared with the other muscles. Collagen characteristics differed among breeds because of variation in the maturity of the breed. Similarly, according to the meta-analyses, total and insoluble collagen content evolutions with the degree of maturity (DOM; proportion of adult weight reached at slaughter) were different in dairy and rustic breeds from those of beef breeds, especially in bulls. Although the relationships between collagen content and DOM were quantified in different muscles and sexes, the precision of the fitted equations was not sufficient for prediction. Consequently, relying on the hypotheses raised by the meta-analysis and the literature, an approach to further develop a dynamic mechanistic model of soluble and insoluble collagen content is proposed.

Comparative Ultrastructural and Biochemical Studies of Four Demosponges from Gulf of Mannar, India

Marine sponge explorations at Gulf of Mannar (GoM), India in the past few years (2003-2009) revealed around forty sponge species that lead to various comprehensive studies on chemicobiological molecules including collagens and their applications. Basing on the preliminary evaluations on collagen content, four marine sponges Hyattella cribriformis , Fasciospongia cavernosa , Callyspongia fibrosa and Dysidea fragilis belong to the families Spongiidae, Thorectidae, Callyspongiidae and Dysideidae of the class Demospongiae, were chosen for macromolecular and micro-anatomical comparison. Microscopic examinations were performed to understand the form and arrangement of skeletal components in each sponge, where unique skeletal composition and spongin distribution is typical for all the sponges except D. fragilis , which is highly embedded with diversified oxeae. Biochemical analyses were performed to resolve the macromolecular content for each sponge species. Sponge D. fragilis was found to possess less protein content (57.26±3.36 mg/g freeze-dried sponge wt) when compared to other sponges and significantly, C. fibrosa possess high protein (209.55±9.53 mg/g) and other macromolecular contents, except pentose (24.12±1.21 mg/g). Different forms of collagens viz ., Acid soluble (AS), salt soluble (SS) and insoluble (Ins) collagens are estimated to understand the variation in collagen make up in their respective tissues. The higher collagen content in C. fibrosa could propose to use this species as a potential model for targeting collagenous molecules towards human health benefits.

Disruption of elastic lamellae in the aorta by D-penicillamine and its effect on vaso-regulation in rats

We assessed the effects of D-penicillamine (D-PA) on cross-linkages in elastin and vaso-regulatory function in rats. After administration of D-PA at a dose of 100 mg/kg/day for 7 weeks to adult and young rats, the thoracic aortas were isolated. The elastic lamellae in the aorta were disrupted histopathologically in all the treated groups. The content of cross-linkages in elastin, i.e. desmosine and isodesmosine, which gives elasticity to the aortic wall, was significantly reduced in the D-PA treated groups versus the control groups. On the other hand, the content of pyridinoline as a marker of insoluble collagen was significantly reduced in the D-PA treated groups, even though the total collagen content was not changed. In addition, after 7 weeks of treatment with D-PA, the change between systolic blood pressure before and after sympathetic stimulation (Δ-SBP) by L-epinephrine was about 2.5-fold larger than that in the control group. Similar results were obtained using angiotensin II or ouabain instead of L-epinephrine. These findings demonstrated that D-PA disrupted elastic lamellae of the rat aorta by reduction of the cross-linkages in elastin and collagen, which caused dysfunction of vaso-regulation. Also, they suggested the possibility that long-term treatment with D-PA in patients could cause a decrease in vaso-regulatory function and could increase the risk of cardiovascular events.

Cluster analysis application identifies muscle characteristics of importance for beef tenderness.

BackgroundAn important controversy in the relationship between beef tenderness and muscle characteristics including biochemical traits exists among meat researchers. The aim of this study is to explain variability in meat tenderness using muscle characteristics and biochemical traits available in the Integrated and Functional Biology of Beef (BIF-Beef) database. The BIF-Beef data warehouse contains characteristic measurements from animal, muscle, carcass, and meat quality derived from numerous experiments. We created three classes for tenderness (high, medium, and low) based on trained taste panel tenderness scores of all meat samples consumed (4,366 observations from 40 different experiments). For each tenderness class, the corresponding means for the mechanical characteristics, muscle fibre type, collagen content, and biochemical traits which may influence tenderness of the muscles were calculated.ResultsOur results indicated that lower shear force values were associated with more tender meat. In addition, muscles in the highest tenderness cluster had the lowest total and insoluble collagen contents, the highest mitochondrial enzyme activity (isocitrate dehydrogenase), the highest proportion of slow oxidative muscle fibres, the lowest proportion of fast-glycolytic muscle fibres, and the lowest average muscle fibre cross-sectional area. Results were confirmed by correlation analyses, and differences between muscle types in terms of biochemical characteristics and tenderness score were evidenced by Principal Component Analysis (PCA). When the cluster analysis was repeated using only muscle samples from m. Longissimus thoracis (LT), the results were similar; only contrasting previous results by maintaining a relatively constant fibre-type composition between all three tenderness classes.ConclusionOur results show that increased meat tenderness is related to lower shear forces, lower insoluble collagen and total collagen content, lower cross-sectional area of fibres, and an overall fibre type composition displaying more oxidative fibres than glycolytic fibres.