Interaction of cytochrome c L with methanol dehydrogenase from Methylophaga marina 42:

The reaction of methanol dehydrogenase with cytochrome c _L from Methylophaga marina and the reactions of the non-physiological substrates, Wurster's blue and ascorbic acid, with both proteins were studied as a function of temperature (4–32 °C), pressure (1–2000 bar) and ionic strength using the optical high pressure stopped-flow method. The thermodynamic parameters H, S and V were determined for all reactions where electron transfers are involved. These data allowed the determination of the Maxwell relationships which proved the internal thermodynamic consistency of the system under study. A conformational change on the cytochrome c _L level was deduced from both breaks in the Arrhenius plots and the variation of the V with temperature.Abbreviations MOPS 4-morpholinepropanesulfonic acid - CHES 2-(cyclohexylamino)ethanesulfonic acid - MDH methanol dehydrogenase - EDTA ethylenedinitrilotetraacetic acid disodium salt - BTB bromothymol blue (3,3-dibromothymolsulfoneph-thalein) - PQQ 2,7,9-tricarboxy-lH-pyrrolo-[2,3f]quinoline-4,5-dione - cytochrome c _HH mammalian horse heart cytochrome c     

Rhodopsin phosphorylation occurs at metarhodopsin II level

Photolyzed rhodopsin was phosphorylated in bovine rod outer segments incubated at –10 C. In the experiment in which urea-treated outer segments and rhodopsin kinase were incubated with ATP in the presence of 30% glycerol, the extent of phosphate incorporation at –10 C was about 30% of that at 37 C. Separation of phosphorylated rhodopsin by isoelectric focusing indicated that a limited number of sites were phosphorylated at –10 C. The partially phosphorylated pigment incorporated more phosphates when the temperatures was raised to 37 C. This was partly due to decreased inhibition of phosphorylation by glycerol at higher temperature. Since the maximum phosphorylation at –10 C (at which metarhodopsin II is stable) occurred at a pH value (6.0) lower than the pKa for metarhodopsin I-metarhodopsin II transition, metarhodopsin II was suggested to be the preferred substrate for rhodopsin kinase at –10 C. Limited proteolysis with thermolysin of rhodopsin phosphorylated at 37 C released peptides containing about 50% of the total phosphate incorporated. In contrast, proteolytic digestion of rhodopsin phosphorylated at –10 C released negligible amounts of phosphate-containing peptides. The results were taken to suggest that the incorporation of phosphates at metarhodopsin II level under the present condition occurred in the residues other than those removed by thermolysin digestion.Based on material presented at the Fifth International Congress of Eye Research, Eindhoven, October 1982     

Body temperature responses of Savanna Brown goat to the harmattan and hot-dry season

Rectal and vaginal temperature responses of the Savanna Brown goat indigenous to the Nigerian guinea savanna were determined during the harmattan and the hot-dry season. Measurements were made at 06:00h and at 14:00h after 8h exposure to field conditions. At the 06:00h measurements during the harmattan, all animals were observed to shiver. A significant (P<0.01) positive correlation was found between rectal (T_re) and vaginal temperatures. During the harmattan, mean T_re was 38.2C at 06:00h and 39.7C at 14:00h; the mean difference, T_re was 1.5C. During the hot-dry season, T_re at 06:00h was 38.1C, and at 14:00h, 38.7; T_re was 0.6C. It is concluded that the harmattan is thermally more stressful than the hot-dry season and that passive thermolability may not be an important mechanism in the Savanna Brown goat in adaptation to thermal stress.     

Novel prebiotic systems: Nucleotide oligomerization in surfactant entrapped water pools

Summary Oligomerization of 5-TMP in water pools entrapped by dodecyl-ammonium chloride surfactant aggregates in benzene: hexane in the presence of dicyanodiimide at temperatures ranging from 21°–72° resulted in the formation of linear and cyclic oligonucleotides containing up to pentamers. Effects of temperature, time and surfactants have been examined. Rate constants for the formation of oligomers have been determined at five different temperatures. These data afforded values of H = 11.8 ± 1.9 Kcal mole^–1, S=–53 6 e.u. and G = 27.4 4.0 Kcal mole^–1. Prebiotic significance of these results are discussed.     

The effect of ambient temperature on diurnal rhythm in heat production and activity in pigs kept in groups

The effect of ambient temperature on diurnal rhythm of metabolic rate and activity was studied in group housed pigs in two trials. Two climate controlled respiration chambers were used, one for each trial. Each chamber contained two groups of 8 pigs. During the experiment of 31 days the mean live weight of the animals increased from 28 to 40 kg. Feeding level was kept constant at 93 kg^–0.75. d^–1. Feed contained 12 kJ of metabolizable energy per g. Temperature treatment started with 20C for two days. After that it was lowered in stepwise fashion by 4K to 16, 12 and 8C. Each temperature treatment lasted two days. After that temperature it was increased in steps to 20C in 8 days. The whole procedure was repeated once. Metabolic rate and activity were measured continuously during the 24 hrs of every second day of the temperature treatment.Metabolic rate increased at temperatures below 16C. Activity was associated with ambient temperature. At low temperature, the total activity related heat production was increased, especially during day time. Variation in metabolic rate within a day was not reduced by low ambient temperature. Thermal requirement, calculated as lower critical temperature, was about 14C as averaged over the day, (16.1C during day time and 13.6C during night time). Extra thermal heat production below thermoneutrality was affected by time of day and activity.     

Genetic characterization of a new splice variant of the β2 subunit of the voltage-dependent calcium channel

This study reports a novel splice variant form of the voltage-dependent calcium channel ₂ subunit (_2g). This variant is composed of the conserved amino-terminal sequences of the _2a subunit, but lacks the -subunit interaction domain (BID), which is thought essential for interactions with the ₁ subunit. Gene structure analysis revealed that this gene was composed of 13 translated exons spread over 107 kb of the genome. The gene structure of the ₂ subunit was similar in exon-intron organization to the murine ₃ and human ₄ subunits. Electrophysiological evaluation revealed that _2a and _2g affected channel properties in different ways. The _2a subunit increased the peak amplitude, but failed to increase channel inactivation, while _2g had no significant effects on either the peak current amplitude or channel inactivation. Other subunits, such as ₃ and ₄, significantly increased the peak current and accelerated current inactivation.     

Estimation of sweat rate and thermal tolerance of pure Creole and of Limousin × Creole crossbred growing bulls in Guadeloupe (French West Indies)

Four out of 8 Limousin × Creole (Li × Cr) and 4 out of 8 Creole growing bulls were exposed to full sunshine in Guadeloupe (French West Indies), the others being kept under shade. Sweating rate (measured on the back with capsules filled with a dessicator), rectal temperature and respiratory rhythm were measured between 11 a.m. and 3 p.m., as well as climatic environmental data. Rectal temperature of Creole bulls (overall mean: 38.8C) remains unaffected by black globe temperature (TG), while, for Li × Cr bulls, it is well related to TG, reaching 39.5C when TG=39C; at this moment, Li × Cr respiratory rhythm reaches 100 breaths/min, compared with only 70 for Creole animals. The shade mean levels of these two parameters for each genotype are consistently the same (38.7C and 39 breaths/min). Under full sunshine, mean sweat rate is almost the same for the 2 genotypes; under shelter, the crossbred bulls sweat more than the Creole bulls, both shade means being significantly lower than means in the sun. Probably, when shaded, the Li × Cr animals must sweat more to balance a greater heat production, but their maximum sweat ability is not very different than the one of Creole bulls.     

Frostbite and the significance of a temperature-sensation scale in field and laboratory conditions

The literature indicates that rapid thawing in water between 42 and 45C provides the best prognosis for frostbitten limbs.A temperature:sensation scale for the normal hand was derived and tested in laboratory and field conditions. The scale permitted the preparation of water suitable for frostbite treatment by the majority of subjects without access to a thermometer. The maximum observed inaccuracy was 1.2C outside the preferred range but was well withing the safe range for treatment.

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Zusammenfassung Die beste Prognose zur Behandlung von Erfrierungen bietet nach den Erfahrungen in der Literatur das schnelle Auftauen von erfrorenen Gliedern bei Wassertemperaturen von 42–45C. Für die gesunde Hand wurde eine Temperatur-Wahrnehmungsskala aufgestellt und unter verschiedenen Bedingungen im Laboratorium und im Freien geprüft. Ohne Zugang zu einem Thermometer gestattete die Skala in der Mehrzahl der FÄlle die ErwÄrmung von Wasser auf Temperaturen, die für die Behandlung von Erfrierungen geeignet sind. Die grösste Ungenauigkeit zwischen SchÄtzwert und Thermometerwert war 1.2C ausserhalb des gewünschten aber noch innerhalb des für die Behandlung zulÄssigen Bereiches.

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Résumé D'après les indications de plusieurs auteurs, le meilleur traitement de membres gelés consiste à les dégeler dans de l'eau à une temperature entre 42 et 45C. Une échelle température-sensation pour la main normale a été mise au point et vérifiée au laboratoire ainsi qu'en plain air.Cette méthode a permis la préparation d'eau en vue d'un traitement de gelures sans faire usage d'un thermomètre dans la plupart des cas. L'erreur maximum observée était de 1,2 C sans que les limites de l'intervalle propice à un traitement ne soient jamais dépassées.

     

Variations in mental performance under moderate cold stress

Effects of moderate cold stress on reasoning ability, associative learning and critical flicker frequncy of Indian subjects were studied by exposing them to 25C,. 20C, 15C and 10C for three hours. A second set of experiments was also conducted to confirm the conclusions of the first by using the same temperatures and duration of exposure. However, not only the sample used in the second case was larger and different but also the mental functions tested were numerical ability, running memory and mental alertness. It has been concluded that there is a significant impairment of simple cognitive functions at 15C which is 10C lower than their most comfortable temperature of 25C.     

The relative influence of urban climates on outdoor human energy budgets and skin temperature II. Man in an urban environment

Four typical urban neighborhoods or street canyon settings (including street parks) were simulated. These urban morphologies were exposed to typical summer and winter climatic scenarios for latitudes 10, 34, and 50N. The changes induced in the components of the human energy budget were examined. Resultant skin temperatures were compared with non-urban, unobstructed environments.     

Identification and DNA sequence analysis of a γ-type gliadin cDNA plasmid from winter wheat

Summary Recombinant cDNA plasmids possessing the coding sequences for the -type gliadins were isolated from a cDNA library prepared from wheat seed poly (A⁺) RNA. One of these plasmids, pGliB48, specifically hybridizes to poly (A⁺) RNA molecules 1 400–1 500 bases in length that direct the synthesis of polypeptides at 38 Kd and 46 Kd, the latter size characteristic of the -type gliadins. The cDNA sequence of pGliB48 was determined and encompasses the 3 untranslated region as well as 245 amino acids from the C-terminus of the -type gliadin polypeptide. The 5-end of the DNA coding sequence consists of a tandem repeat unit composed of eight amino acids. Localized regions of homology are observed for the /-type and -type gliadin cDNA sequences.     

Nuclear Overhauser effect investigation on GM1 ganglioside containingN-glycolyl-neuraminic acid (II3Neu5GcGgOse4Cer)

The conformational properties of the oligosaccharide chain of GM1 ganglioside containingN-glycolyl-neuraminic acid, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer, were studied through NMR nuclear Overhauser effect investigations on the monomeric ganglioside in dimethylsulfoxide, and on mixed micelles of ganglioside and dodecylphosphocholine in water. Several interresidual contacts for the trisaccharide core--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-were found to fix the relative orientitation of the three saccharides, while the glycosidic linkage of the terminal -Gal-was found to be quite mobile as the -Gal-(1-3)--GalNAc-disaccharide exists in different conformations. These results are similar to those found for two GM1 gangliosides containingN-acetyl-neuraminic acid and neuraminic acid [1].Abbreviations Ganglioside nomenclature is in accordance with Svennerholm [23] and the IUPAC-IUB Recommendations [24] GM3(Neu5Ac) II³Neu5AcLacCer, -Neu5Ac-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer - GM3(Neu5Gc) II³Neu5GcLacCer, -Neu5Gc-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu5Ac) II³Neu5AcGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu5Gc) II³Neu5GcGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu) II³NeuGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu-(2-3)]--Glc-(1-1)-Cer - GD1a IV³Neu5AcII³Neu5AcGgOse₄Cer, -Neu5Ac-(2-3)--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GalNAc-GD1a IV⁴GalNAcIV³Neu5AcII³Neu5AcGgOse₄Cer, -GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - Neu neuraminic acid - Neu5Ac N-acetyl-neuraminic acid - Neu5Gc N-glycolyl-neuraminic acid - Cer ceramide     

Cluster Maintenance in Mobile Ad-hoc Networks

The main contribution of this paper is to propose a new cluster maintenance algorithm and a companion cluster initialization algorithm based on a number of interesting and novel properties of diameter-2 graphs. The initialization algorithm naturally blends into cluster maintenance, showing the unity between these two operations. We refer to our algorithms as tree-based since they depend on a spanning tree maintained at various nodes. Unlike the vast majority of published clustering algorithms, our algorithms are cluster-centric, as opposed to node-centric, and work in the presence of node mobility. Extensive simulation results have shown the effectiveness of our algorithms when compared to other clustering schemes proposed in the literature.Lan Wang received his B.S. and M.S. degrees in computer science from Harbin Engineering University, China in 1992 and 1995, respectively. From 1995 to 1999, he worked as a software engineer at the System Engineering Research Institute of CSSC, Beijing, China. He is currently a PhD student at the Computer Science Department of Old Dominion University.Stephan Olariu received the M.Sc. and Ph.D. degrees in computer science from McGill University, Montreal, Canada in 1983 and 1986, respectively. In 1986 he joined the Computer Science Department at Old Dominion University where he is now a full professor. He has published extensively in various journals, book chapters, and conference proceedings. His research interests include wireless networks and mobile computing, parallel and distributed systems, performance evaluation, and medical image processing. Prof. Olariu serves on the editorial board of several archival journals including IEEE Transactions on Parallel and Distributed Systems, Journal of Parallel and Distributed Computing, International Journal of Foundations of Computer Science, Journal of Supercomputing, International Journal of Computer Mathematics, VLSI Design, and Parallel Algorithms and Applications.     

Defective remethylation of homocysteine is related to decreased synthesis of coenzymes B2 in thyroidectomized rats

Summary. We investigated the influence of hypothyroidism on homocysteine metabolism in rats, focusing on a hypothetical deficient synthesis of FAD by riboflavin kinases. Animals were allocated in control group (n=7), thyroidectomized rats (n=6), rats with diet deficient in vitamin B2, B9, B12, choline and methionine (n=7), thyroidectomized rats with deficient diet (n=9). Homocysteine was decreased in operated rats (2.6±1.01 vs. 4.05±1.0mol/L, P=0.02) and increased in deficient diet rats (29.56±4.52 vs. 4.05±1.0mol/L, P=0.001), when compared to control group. Erythrocyte-Glutathione-Reductase-Activation-Coefficient (index of FAD deficiency) was increased in thyroidectomized or deficient diet rats (P=0.004 for both). Methylenetetrahydrofolate-reductase and methionine-synthase activities were decreased in thyroidectomized rats but not in those subjected to deficient diet. Cystathionine--synthase was increased only in operated rats. Taken together, these results showed a defective re-methylation in surgical hypothyroidism, which was due in part to a defective synthesis of vitamin B2 coenzymes. This defective pathway was overcompensated by the increased Cystathionine--synthase activity.     

Growth temperature acclimation byAmoeba proteus: Effects on cytoplasmic organelle morphology

Summary The effects on subcellular morphology of maintaining amoebae at temperatures other than 20 C (the routine culture temperature) were assessed. Estimations of cycling potential at each temperature confirmed that acclimation had affected gross cell functioning. Generation times ranged from no division at 6 C, to an optimal minimum of 2 days at 22 C.Organelle morphology changes were studied after 5 days of growth at the new temperatures; alterations were most evident at the extremes of 6 and 28 C. The main mitochondrial alteration resulted in changes to the ratio of Type I: Type II organelles; with a decrease in Type I forms away from the optimal range of 20–22 C. Extended culturing at 6 C generated mitochondrial matrical inclusions. Ribosomal attachment to the endoplasmic reticulum, a common feature of 20 C-grown cells, decreased at the temperature extremes, where an increase in free ribosomes occurred. Upon extended culture at 6 C helical structures, usually observed in groups only within the nucleus, were also present in the cytoplasm. Golgi complexes were less common in cells maintained at extreme temperatures and often showed differences in shape. These changes were all reversible on a return to culturing at 20 C.The possible functional significance of these findings is discussed.     

Effects of fasting on maximum thermogenesis in temperature-acclimated rats

To further investigate the limiting effect of substrates on maximum thermogenesis in acute cold exposure, the present study examined the prevalence of this effect at different thermogenic capabilities consequent to cold- or warm-acclimation. Male Sprague-Dawley rats (n=11) were acclimated to 6, 16 and 26C, in succession, their thermogenic capabilities after each acclimation temperature were measured under helium-oxygen (21% oxygen, balance helium) at –10C after overnight fasting or feeding. Regardless of feeding conditions, both maximum and total heat production were significantly greater in 6>16>26C-acclimated conditions. In the fed state, the total heat production was significantly greater than that in the fasted state at all acclimating temperatures but the maximum thermogenesis was significant greater only in the 6 and 16C-acclimated states. The results indicate that the limiting effect of substrates on maximum and total thermogenesis is independent of the magnitude of thermogenic capability, suggesting a substrate-dependent component in restricting the effective expression of existing aerobic metabolic capability even under severe stress.     

β2-Adrenoceptor activation by zinterol causes protein phosphorylation,contractile effects and relaxant effects through a cAMP pathway in human atrium

Evidence from ventricular preparations of cat, sheep, rat and dog suggests that both ₁-adrenoceptors (₁AR) and ₂-adrenoceptors (₂AR) mediate positive inotropic effects but that only ₁AR do it through activation of a cAMP pathway. On the other hand, our evidence has shown that both ₁ AR and ₂ AR hasten relaxation of isolated human myocardium consistent with a common cAMP pathway. We have now investigated in the isolated human right atrial appendage, a tissue whose -AR comprise around 2/3 of ₁AR and 1/3 of ₂AR, whether or not ₂AR-mediated effects occur via activation of a cAMP pathway. We carried out experiments on atria obtained from patients without advanced heart failure undergoing open heart surgery. To activate ₂AR, we used the ₂AR-selective ligand zinterol. Experiments were carried out on paced atrial strips (1 Hz) and tissue homogenates and membrane particles. Zinterol caused positive inotropic and lusitropic (i.e. reduction of t_1:2 of relaxation) effects with EC₅₀ values of 3 and 2 nM, respectively. The zinterol-evoked effects were unaffected by the AR-selective antagonist CGP 20712A (300 nM) but blocked surmountably by the ₂AR-selective antagonist ICI 118551 (50 nM) which reduced both EC₅₀ values to 1 M. Zinterol stimulated adenylyl cyclase activity with an EC₅₀ of 30 nM and intrinsic activity of 0.75 with respect to (–)-isoprenaline (600 M); the effects were resistant to blockade by CGP 20712A (300 nM) but antagonised surmountably by ICI 118551 (50 nM). Zinterol bound to membrane PAR labelled with (–)-[¹²⁵I] cyanopindolol with higher affinity for ₂AR than for - 1 AR; the binding to ₂AR but not to - BAR was reduced by GTPyS (10 M). In the presence of CGP 20712A (300 nM) (–)-isoprenaline (400 M); (to activate both ₁AR and ₂AR maximally) and zinterol (10 M); increased contractile force 3.4-fold and 2.5-fold respectively and reduced relaxation tut by 32% and 18% respectively. These effects of (–)-isoprenaline and zinterol were associated (5 min incubation) with phosphorylation (pmol P/mg supernatant protein) of troponin I and C-protein to values of 8.4 ± 2.0 vs 12.4 ± 2.3 and 10.1 ± 2.5 vs 8.6 ± 1.6 respectively. (–)-Isoprenaline and zinterol also caused phosphorylation of phospholamban (1.8 ± 0.3 vs 0.4 ± 0.1 pmol P/mg respectively) specifically at serine residues. We conclude that in human atrial myocardium activation of both ₁AR and ₂AR leads to cAMP-dependent phosphorylation of proteins involved in augmenting both contractility and relaxation.     

Die Hypokotylfarbe als Markierungsfaktor von Genomstufen der Zuckerrübe

Zusammenfassung In zunehmendem Maße werden anisoploideBeta-Rübensorten angebaut, deren zytologische Kontrolle zwecks Feststellung der Genomstufenprozentanteile recht arbeitszeitaufwendig ist. Übereinstimmend mit polnischen Autoren wurde festgestellt, daß die Hypokotylfarbe ein geeigneter Markierungsfaktor für die einzelnen Genomstufen darstellt. Kreuzt man tetraploide Pflanzen, die ein grünes Hypokotyl besitzen, mit diploiden Pflanzen, die ein rosa Hypokotyl aufweisen, so erhält man von dem tetraploiden Partner tetraploide grüne und triploide hellbraune, von dem diploiden Partner diploide rosa und triploide hellbraune Nachkommenschaften. Die in bezug auf die Hypokotylfarbe heterozygoten Pflanzen kann man demnach von den homozygot grünen und homozygot rosa Individuen unterscheiden. Die Kreuzung diploid grünxtetraploid rosa ist für diese Zwecke nicht brauchbar, da sich die triploiden Heterozygoten mit einem grünen und zwei rosa Allelen in der Hypokotylfarbe nicht deutlich von den homozygoten rosa Pflanzen abheben. Auf die Bedeutung dieser Markierungsmöglichkeit für bestimmte Forschungsprobleme, die Züchtung und die Saatgutkontrolle wird hingewiesen.     

Thermoregulation in the hippopotamus

Measurements of the sub-lingual temperature and of the skin temperature of the nose, ears, neck, dewlap, sides and back of two hippopotami (HIPPOPOTAMUS AMPHIBIUS L.) in the Zoological Park at Wroclaw have been made. The mean sub-lingual temperature was 36.1C but a diurnal rhythm of sub-lingual temperature was evident, which was not related to changes in the environmental temperature. The skin temperatures varied with the environmental temperature. When the animals were immersed in water at 9C the sub-lingual temperature dropped to 24.5C but it had returned to its pre-immersion value within one hour of leaving the water.

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Zusammenfassung Es wurden Messungen der Sublingualtemperatur und der Temperatur der Haut an Nase, Ohren, Nacken, Wamme, Seiten und Rücken von 2 Hippopotamus (HIPPOPOTAMUS AMPHIBUUS L.) im Zoologischen Garten in Warschau vorgenommen. Die mittl. Sublingualtemperatur war 36.1C. Ein diurnaler Rhythmus ohne Beziehung zu den Änderungen der Umwelttemperatur konnte nachgewiesen werden. Die Hauttemperatur Änderte sichmit der Umwelttemperatur. Wenn die Tiere im Wasserbecken (9C) standen,fiel die Sublingualtemperatur auf 24,5C. Sie stieg nach Verlassen des Wassers innerhalb einer Stunde auf den Ausgangswert.

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Resume La température sublinguale ainsi que les températures cutanées du nez,de l'oreille, de la nuque, du ventre, des flancs et du dos ont été relevées chez deux hippopotamus (HIPPOPOTAMUS AMPHIBIUS L.) du Jardin Zoologique de Varsovie. La température sublinguale moyenne a été de 36,1C. L'existence d'un rythme nycthéméral indépendant des variations de la température ambiante a été observée.La température cutanée varie en fonction de la température ambiante.Quand les animaux se tenaient debout dans leur bassin d'eau froide à 9C, la température sublinguale tombait à 24,5C.Lorsque les animaux quittaient ce bassin, cette température remontait au bout d'environ b heure à sa valeur de départ.

     

Histoenzymatic characterization of sub-types of Type I fibres in fast muscles of rats

Summary The histochemical activities of succinic dehydrogenase (SDH), myofibrillar Adenosine triphosphatase (ATPase) and alpha glycerophosphate dehydrogenase were studied in serial sections of rat vastus lateralis (red) (RVL), gastrocnemius and diaphragm muscles. Three main fibre-types were distinguished. The Type I fibres of RVL and gastrocnemius muscles fell into two distinct groups: one category-Type IA showed very low ATPase activity. The second category of Type IB fibres displayed moderate ATPase reaction. The Type IA fibres were divisible into two sub-groups when tested for SDH reaction. Type IA₁ fibres possessed a homogenous distribution of diformazan·granules throughout the fibre: Type IA₂ fibres displayed characteristic moth-eaten pattern of diformazan localization. The diaphragm muscle did not show either Type IB or Type IA₂ varieties. The great majority of Type I fibres were sub-type IA₁ in the three fast muscles studied. It is also demonstrated here that an inherent heterogeneity exists between Type I fibres of diaphragm and leg muscles in regard to -GPD localization. This histochemical data emphasizes the fact that subdivision of Type I striated muscle fibres of mammalian animals into two sub-types is only approximate and that a further subcategorization is possible.