Proteolysis of skeletal muscle in yellowfin tuna (Thunnus albacares): Evidence of calpain activation

• 1.1. White muscle of yellowfin tuna is subject to a form of deterioration known as “burnt tuna”.
• 2.2. TEM and SDS-PAGE were used to quantify cellular differences in deteriorated white muscle of yellowfin tuna.
• 3.3. Electron micrographs showed a significant loss of Z-disc integrity and an increase in intracellular edema in burnt tuna.
• 4.4. Electrophoresis established that a specific doublet of proteins, 42 kD and 46 kD was lost.
• 5.5. Proteolysis of isolated myofibrils incubated in calpain (EC 3.4.22.17) was greatest at pH 7.5 and was selective for intermediate molecular weight proteins.
• 6.6. This evidence suggests that burnt tuna is a specific and limited proteolysis of myofibrillar structural proteins characteristic of calpain proteolysis.

     

Reduced muscle protein breakdown in septic rats following treatment with interleukin-1 receptor antagonist

• 1.1. The role ofinterleukin-1 (IL-1) in sepsis-induced muscle proteolysis was assessed by treating septic rats with recombinant IL-1 receptor antagonist (rIL-Ira).
• 2.2. In initial experiments, we tested the effectiveness of IL-Ira in preventing muscle proteolysis induced by administration of IL-1.
• 3.3. When normal rats were treated with rIL-α (three intraperitoneal doses of 100 μ g/kg body weight each over 16 hr), total and myofibrillar muscle protein breakdown rates, measured as release oftyrosine and 3-methylhistidine, respectively, by incubated extensor digitorum longus muscles, were significantly increased.
• 4.4. This metabolic response to IL-α was completely abolished by rIL-Ira, administered as three intraperitoneal doses of 3 mg/kg body weight each over 16hr.
• 5.5. In subsequent experiments, sepsis was induced in rats by cecal ligation and puncture (CLP); non-septic rats were sham-operated.
• 6.6. Treatment of septic rats over 16hr with a total dose of 25mg/kg body weight of rIL-Ira reduced, but did not normalize, the increased muscle protein breakdown rates seen during sepsis.
• 7.7. When the dose of rIL-Ira was more than doubled and given as a constant infusion at a rate of 4.2 mg/kg body weight/hr for 16 hr, the increased rate of muscle proteolysis in septic rats was normalized.
• 8.8. The present study offers the first direct evidence that IL-1 is involved in the regulation of muscle proteolysis during sepsis.

     

Bioassay and proteolytic activity of digestive enzymes from octopus saliva

• 1.1. A bioassay for octopus saliva, based on detachment of crab dactylopodite flexor muscle under standard conditions, has been developed.
• 2.2. There is a direct relationship between increasing caseinolytic activity of saliva from Eledone cirrhosa and decreasing muscle detachment time.
• 3.3. Fractionation of saliva, using preparative isoelectric focusing, shows that muscle releasing activity is restricted to fractions containing proteins with high isoelectric points and maximum caseinase activity.
• 4.4. It is concluded that proteolytic enzyme(s) in octopus saliva selectively release crab muscle from attachment to the carapace.

     

Purification and partial characterization of an AMP deaminase from the marine invertebrate Palaemon serratus

• 1.1. AMP deaminase from Palaemon serratus tail muscle was partially purified by chromatography on cellulose phosphate.
• 2.2. Muscle homogenates expressed very low enzyme activities and the presence of ATP was necessary to detect AMP deaminase. The specific activity and substrate affinity of the purified enzyme were also very low.
• 3.3. The purified prawn muscle AMP deaminase was contaminated by contractile proteins, one of the major contaminants being actin.
• 4.4. The enzyme displayed a very high affinity for actomyosin which was only partially abolished by pyrophosphate.

     

Diversity of native myosin and myosin heavy chain in fish skeletal muscles

• 1.1. Polymorphism of native myosin and myosin heavy chain (MHC) of fish skeletal muscles was analysed by pyrophosphate and SDS-gel electrophoreses.
• 2.2. Depending on the species, three or four myosin isoforms were detected in the white muscle, one or two isoforms in the pure red muscle, and four isomyosins were found in the red muscle composed of red and pink (intermediate) fibres.
• 3.3. It is suggested that all main types of fish muscle fibre (red, intermediate and white) differ in myosin isoform content.
• 4.4. Myosin heavy chain of the red muscle is a distinct protein from that of the white muscle. However, structural differences between these proteins vary among species.

     

Decreased Antibiotic Susceptibility Driven by Global Remodeling of the Klebsiella pneumoniae Proteome

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Highlights

• •Global proteomic remodeling alters antibiotic susceptibility in K. pneumoniae.
• •Drug specific transport, sugar utilization, central metabolism, capsule synthesis.
• •Common pathways of reactive oxygen scavenging, turnover of misfolded proteins.
• •Integrated adjustments and unique drug-specific features for drug combinations.

     

Interrelationship between metabolism of tritiated water, 22sodium and dry matter intake by beef cattle consuming wheat straw and poultry litter in free choice

• 1.1. Metabolism of tritiated water and ²²sodium was studied in six beef cows under Mediterranean summer conditions in order to find whether the turnover of these tracers can be used to evaluate pasture intake.
• 2.2. The diet of the cows included ad libitum access to two components which were given separately in different troughs: one was poultry litter and the other was wheat straw, to simulate the dry pasture.
• 3.3. Voluntary daily dry matter intake (111 g/kg^0.75) was unexpectedly high considering the low digestibility of the feed.
• 4.4. The assumptions of constant ratios of water intake to water turnover and of dry matter intake to water intake were confirmed. Consequently, dry matter intake was determined accurately from water turnover measurements.
• 5.5. Sodium intake was practically equal to sodium turnover and most of the sodium secreted in feces was of endogenous origin.
• 6.6. Pasture intake can be predicted from sodium turnover once the concentration in feed and water consumed is known.

     

Tritiated water measurements of water flux in nestling and adult zebra finches (Poephila guttata)

• 1.1. Total body water volume (TBWV) and daily water turnover rates (WTR) were measured in nestling and adult zebra finches using tritiated water (TOH).
• 2.2. TBWV and daily WTR increased with age up to 13 days post hatching.
• 3.3. TBWV and WTR approached adult levels after 13 days of age. WTR varied among ages and nest mates. All nestlings turned over at least 50% of their body water pool per day.
• 4.4. The WTR data for adult birds are consistent with natural history data suggesting zebra finches are dependent on water for breeding and survival.

     

Identification of a glycoprotein complex containing a glycogen synthase isozyme in Ascaris Suum obliquely-striated muscle

• 1.1. A glycogen/protein complex which contains the major portion of glycogen synthase activity in Ascaris suum muscle has been purified.
• 2.2. The complex contains two proteins which can be dissociated from a glycoprotein component.
• 3.3. The glycoprotein contains glycogen-like domains and is resistant to trypsin digestion.
• 4.4. The glycogen synthase activity in the purified complex catalyzes glycogen synthesis in the absence of exogenous glycogen, but demonstrates an absolute glucose 6-phosphate requirement for activity.
• 5.5. The data support the hypothesis that this isozyme of glycogen synthase is significantly different from the cyclic AMP-regulated enzyme.

     

Comparative aspects of iodine conservation in mammals

• 1.1. Comparative aspects of iodine conservation in mammals were studied on the basis of published data on kidney and thyroid weights and function.
• 2.2. Very small mammals possessed an efficient reabsorption of iodide to compensate for the high glomerular nitration rate (GFR).
• 3.3. Humans and mammals of a similar and larger size had “lost” the ability to reabsorb iodide efficiently.
• 4.4. Very large mammals are protected against renal loss of iodide due to the relatively low GFR.
• 5.5. Thyroid weights in relation to body weight were highest in humans suggesting that humans and other mammals of a similar size are especially susceptible to iodine deficiency.

     

In situ phosphorylation of contractile proteins of a molluscan Mytilus edulis catch muscle in different functional states

• 1.1. The incorporation of ³²P into the contractile proteins of the anterior byssus retractor muscle of Mytilus edilus L. was analyzed during the different stages of a contraction-catch-relaxatin cycle.
• 2.2. The experiments were performed with saponin-skinned fibers preincubated with γ-³²P-ATP.
• 3.3. The total amount of ³²P incorporated into the fiber proteins was anlyzed by measuring the label of TCA-insoluble protein in a scintillation counter.
• 4.4. The dose incorporated was about twice as high during Ca²⁺ induced contraction and serotonin induced accelerated relaxation as during test and catch.
• 5.5. The molecular mass of the phosphorylated proteins was analyzed by autoradiography of the proteins separated by SDS-PAGE.
• 6.6. Up to 26 protein spots of different molecular masses were labelled, including such well characterized protein spe+cies as myosin heavy and light chains, paramyosin and tropomyosin.

     

The metabolic output of avian (Sturnus vulgaris,Calidris alpina) adipose tissue liver and skeletal muscle: Implications for BMR/body mass relationships

• 1.1. The oxygen uptake rate of avian adipose tissue, liver and skeletal muscle slices were measured.
• 2.2. The energy consumption of fat was less than one tenth that of liver and muscle.
• 3.3. Thus, interspecific allometric equations for the prediction of basal metabolic rate from body mass will not be accurate throughout the avian annual cycle unless changes in body composition are taken into account.

     

The high intracellular ph buffering of hagfish (Eptatretus cirrhatus) dental plate retractor muscle cannot be attributed to the known histidine-related compounds present in other vertebrates

• 1.1. Intracellular pH buffering capacity of hagfish (Eplatretus cirrhatus) dental plate retractor muscles is among the highest reported for any vertebrate muscle.
• 2.2. Over 80% of the pH buffering capacity of hagfish retractor and myotome muscle is due to components other than proteins and phosphate.
• 3.3. The muscles have less than 0.5 μmol/g wet weight of l-histidine, and lack l-l-methyl histidine, l-3-methyl histidine and the histidine-containing dipeptides anserine, carnosine and ophidine.
• 4.4. Instead, they contain an unidentified low molecular weight acid-soluble compound to which the high pH buffering capacity can be attributed.

     

Carbonic anhydrase III content in various equine muscles

• 1.1. In this study, carbonic anhydrase III (CA-III) content in 18 equine muscles was determined by enzyme immunoassay.
• 2.2. It was found to differ in several muscles.
• 3.3. That in external intercostal muscle, rectus abdominis muscle and splenius muscle from four horses was very high.
• 4.4. Although the masseter muscle had only type I fibers, CA-III content was similar to that in mixed-fiber type muscles such as the biceps femoris muscle.
• 5.5. It thus appear that equine type I fibers can be further subgrouped.

     

Identification of the major annexins in Ehrlich ascites tumor cells

• 1.1. Three calcium-binding proteins have been purified from Ehrlich ascites tumor cells.
• 2.2. They were identified by amino acid sequence analysis on selected fragments obtained by tryptic digestion.
• 3.3. The proteins belong to the annexin family and were identified as annexins II, III and V.
• 4.4. Antibodies raised against the proteins were used to examine for their presence in a number of murine tissues.
• 5.5. The occurrence was found to be in reasonable accordance with earlier reports.

     

Detection of 180 kDa proteins in electroplax sodium channel preparations

• 1.1. Co-isolating proteins (M_r 170,000–220,000) from sodium channel preparations made from the electric organ of the electric eel (Electrophorus electricus) were detected on Western blots using monoclonal a antibodies.
• 2.2. Similar protein patterns were seen on immunoblots containing immunoprecipitated protein from eel muscle and brain tissues but not heart.
• 3.3. These co-isolating proteins could be separated from the mature TTX-sensitive channel protein (M_r 280,000) using a lentil lectin-Sepharose column.
• 4.4. The 180 kDa proteins do not appear to be channel-related and can be detected as contaminants in electroplax sodium channel preparations using the monoclonal antibodies described here.

     

Metabolism in malleefowl (Leipoa ocellata)

• 1.1. Malleefowl Leipoa ocellata have a lower than predicted metabolic rate, a finding common to many arid adapted avian species.
• 2.2. Evaporative water loss was as expected by allometric analysis. However, in the wild this species probably reduces its evaporative water loss because their water turnover rate is extremely low.
• 3.3. Malleefowl coped with temperatures up to 40°C well, but above this temperature they become highly agitated.

     

Sex differences in vascular reactivity to adrenergic agents in the rat

• 1.1.The study was designed to determine if there are sex-dependent differences in vascular reactivity to adrenergic agents.
• 2.2.Vascular reactivity of both aortic and tail artery smooth muscle from male and female rats to various vasoactive agents was assessed. 3.li]The vascular response of aortic smooth muscle to both phenylephrine and isoproterenol were significantly greater in male rats as compared to females.
• 3.4.There were apparent sex differences in responsiveness to the KCl-induced, non-receptor mediated contraction of aortic smooth muscle in that the sensitivity to KCl was enhanced in male rats.
• 4.5.No sex differences were observed in tail artery preparations.
• 5.6.Phentolamine reduced the maximal tension induced by KCl in the tail artery but not aortic artery preparations. This effect was not sex dependent.
• 6.7.No differences in the vascular smooth muscle responsiveness to acetylcholine or sodium nitrate was observed between groups or within different vascular beds.
• 7.8.The increased sensitivity of males to adrenergic challenge could explain in part some of the existing sex differences in cardiovascular disease and hypertension.

     

Role of the visceral nerve in heart rate variations during different behavioral patterns in Megalobulimus sanctipauli (mollusca,gastropoda, pulmonata)

• 1.1. The role of the visceral nerve in mediating the changes in heart rate associated with different behavioral patterns was investigated in Megalobulimus sanctipauli.
• 2.2. The results of acute and chronic denervation experiments indicate that the visceral nerve has no excitatory or inhibitory tonic action on the heart of snails retracted into the shell, nor does it account for the increase in heart rate associated with the locomotion and feeding behaviors.
• 3.3. These changes in heart rate are, probably, indirect effects of increased activity such as an increase in venous return.
• 4.4. The visceral nerve is responsible for approximately 3/4 of the increase in heart rate associated with the first minute of extrusion.
• 5.5. The small increase in heart rate observed in denervated animals is probably caused by an increase in venous return generated by muscle activity that forces the head and food out of the shell.

     

Electrophoretic characterization of a hybrid between Eretmochelys imbricata and Caretta caretta (Cheloniidae)

• 1.1. An intermediate morphotype between Eretmochelys imbricata and Caretta caretta was studied in Praia do Forte, Bahia, Brazil.
• 2.2. Three enzymatic systems were successfully analyzed: SOD, lactate dehydrogenase (LDH) and esterase (EST). Isoelectric focusing of total soluble proteins of muscle and transferrin were shown.
• 3.3. Esterase exhibited nine phenotype patterns, seven in C. caretta and one in the others morphotypes. SOD phenotypes were identical in the three morphotypes. Lactate dehydrogenase and transferrins were characteristic for each species.
• 4.4. Jaccard's measure of similarity was calculated and a phenogram with the three morphotypes were constructed using isoelectric focusing of total soluble proteins.