Myosin light chain patterns of individual fast and slow-twitch fibres of rabbit muscles

Summary Single muscle fibres were isolated by microdissection from freeze-dried samples of rabbit psoas and soleus muscles. The individual fibres were typed according to qualitative histochemical reactions for succinate dehydrogenase or NADH-tetrazolium reductase and for alkaline Ca²⁺-activated myofibrillar myosin ATPase after acid or alkaline preincubation. Methods are described for electrophoretic analysis by means of polyacrylamide disc electrophoresis in the presence of SDS of total myofibrillar proteins in single fibres after pre-extraction of soluble proteins. Fast-twitch white fibres revealed a myosin light chain pattern characteristic of fast-type myosin with three light chains of apparent molecular weights of 22,300 (LC₁), 18,400 (LC₂) and 16,000 (LC₃). Fast-twitch red fibres were indistinguishable in this respect from fast-twitch white fibres and showed an identical pattern of myosin light chains. Slow-twitch fibres could be characterized by a myosin light chain pattern typical of myosin of slow-twitch muscles with peptides of the apparent molecular weights of 23,500 (LC_1Sa), 23,000 (LC_1Sb) and 18,500 (LS_2S). Slow-twitch fibres isolated from soleus as well as from psoas muscle were indistinguishable with regard to their myosin light chain patterns, thus suggesting that fibres of the same histochemical type correspond in their myosin light chain patterns irrespective of their origin from different muscles.Dedicated to the memory of Ernest Gutmann who has contributed so much to our knowledge on differentiation of muscle and who died on August 6, 1977     

Determination of the configurations of lactic and glyceric acids from human serum and urine by capillary gas—liquid chromatography

The separation of the enantiomers of lactic and glyceric acids can be achieved by capillary gas chromatography on SP-1000 using the corresponding O-acetylated menthyl esters. The structures of the derivatives were proved by proton magnetic resonance spectroscopy and mass spectrometry. The method has been used for the determination of the absolute configurations of lactic and glyceric acids isolated from serum and urine from different patients.     

Pulsation of nuclei in insect oocytes is reversibly inhibited by cytochalasin B

Oocyte nuclei of the dipteran insect Heteropeza pygmaea display swift pulsating movements during in vitro follicle formation in the ovaries. Low doses of cytochalasin B (CB) completely inhibit the nuclear movements within a few minutes and cause the nuclei to assume spherical shapes. If the drug is removed, nuclear pulsation is resumed within 5–10 min. Phalloidin and colchicine do not affect the nuclear movements. Actin is shown by indirect immunofluorescence microscopy to be present in considerable amounts all over the cytoplasm of the oocytes. It is concluded that microfilaments are responsible for pulsation of the oocyte nuclei, whereas microtubules are not involved.     

Biotechnological production of unnatural L-amino acids from D,L-5-monosubstituted hydantions. II. L-α- and L-β-naphthylalanine

Summary Resting cells ofArthrobacter sp. (DSM 3745) with the ability to form L-tryptophan from D,L-5-(3-indolylmethy)hydantoin were used for the bioconversion of D,L-5-- and D,L-5--naphthylmethylhydantoin (D,L-5-- and D,L-5--NMH) to the corresponding L-amino acids. Under the optimal reaction conditions of pH 9.7 and 40°C specific productivities of 0.2 (-naphtylalanine) and 0.6 (-naphtylalanine) mM amino acid x g cell dry mass^–1 x h^–1 were obtained in a 0.1 M Na₂CO₃/NaHCO₃-buffer in a strirred bioreactor.     

Purification and characterization of a human recombinant T-cell protein-tyrosine-phosphatase from a baculovirus expression system.

A 48-kDa human T-cell protein-tyrosine-phosphatase (TC.PTPase) and a truncated form missing an 11-kDa C-terminal segment (TC delta C11.PTPase) were expressed by using the baculovirus system and characterized after extensive purification. The full-length PTPase was restricted to the particulate fraction of the cells from which it could be released by a combination of salt and detergent. The enzyme was entirely specific for phosphotyrosine residues. It displayed a low level of activity toward phosphorylated, reduced, carboxamidomethylated, and maleylated lysozyme (RCML), but was 12 times more active toward phosphorylated myelin basic protein (MBP). By contrast, the 37-kDa form localized in the soluble fraction, and its activity toward RCML was 5 times higher than that observed with MBP. The autophosphorylated cytoplasmic domain of the EGF receptor served as substrate for both enzymes. Limited proteolysis of either protein gave rise to a 33-kDa fragment displaying the substrate specificity of the truncated form. These data lend further support to the view that the C-terminal segment of the T-cell PTPase serves a regulatory function, playing an important role in the localization and substrate specificity of the enzyme.     

Antibacterial and antimycotic effect of a newly discovered secretion from larvae of an endoparasitic insect,Pimpla turionellae L. (Hym.)

Three analogues of the peptidyl pheromone, pheromone of Saccharomyces kluyveri, synthesized based on the amino acid sequence proposed by Sato et al. (Agric Biol Chem 45:1531–1533, 1981) were tested for both shmoo-inducing and agglutinability-inducing actions. Purified natural pheromone of the yeast showed the highest activity among the peptides tested. When methionine in the peptides was oxidized, the activity decreased significatly. Pheromone of S. kluyveri induced sexual agglutinability in a cells of Saccharomyces cerevisiae, and shmoo in a cells of S. cerevisiae and S. kluyveri. a Pheromone of S. kluyveri had no agglutinability-inducing action on cells of S. cerevisiae. a Cells of S. kluyveri inactivated only pheromone of the same species, but a cells of S. cerevisiae inactivated pheromones of both S. cerevisiae and S. kluyveri.     

EGG ACTIVATION AND PARTHENOGENETIC REPRODUCTION IN INSECTS

1. Many insects reproduce by parthenogenesis. In one of the largest orders of the animal kingdom, the Hymenoptera, most of its members reproduce by arrhenotokous parthenogenesis. Egg activation in parthenogenetic animals obviously cannot be caused by fertilization of the egg. The question of what initiates egg development in parthenogenetically reproducing animals has been studied for a few insect species and is discussed in this article. 2. The grasshopper Melanoplus differentialis is one of several Orthoptera displaying accidental parthenogenesis. In this species, egg laying provides the stimulus to the completion of meiosis and start of embryonic development in unfertilized and probably also in fertilized eggs. The same holds true for the dipteran insect Drosophila melanogaster which exhibits rudimentary parthenogenesis, and for D. mercatorum showing accidental parthenogenesis. The precise way in which oviposition affects the egg is unknown. 3. The stick insect Carausius morosus reproduces by obligatory thelytoky. The triggering factor for removal of the meiotic block and initiation of embryonic development is oxygen from the air which penetrates to the egg through the micropyle immediately after oviposition. The oviposition act itself is not necessary for activation of the egg. 4. Comparative studies of the different types of oogenesis in the dipteran insect Heteropeza pygmaea show that in paedogenetically developing follicles meiotic arrest in prophase is of very short duration and a meiotic block at the end of oogenesis is absent. It is suggested that in this case triggering events for egg development are dispensable. On the other hand, under certain experimental conditions a meiotic block can be established in some of these follicles. 5. Investigations on the Ichneumonid wasp Pimpla turionellae have shown that unfertilized, male-determined eggs - and most likely also fertilized, femaledetermined eggs - are activated by mechanical stress exerted on the eggs during natural or imitated oviposition. This mechanical stress, in addition, activates a streaming system which is independent of meiotic completion and nuclear multiplication. Egg activation by egg distortion is also found in the Pteromalid species Nasonia vitripennis and occurs presumably in many other Hymenoptera. 6. Carausius morosus, Pimpla turionellae and Nasonia vitripennis are species with parthenogenetic reproduction for which the natural factors responsible for the initiation of egg development have been identified. The cases of Pimpla turionellae and Nasonia vitripennis are of particular interest because of the feasibility of artificially imitating the natural activating mechanism. 7. It is concluded that apart from fertilization various events at oviposition may trigger egg development. In addition, the occurrence of rudimentary parthenogenesis in many sexually reproducing animal species suggests that sperm entry and fertilization may frequently be necessary for the continuation of egg development rather than for its initiation.     

CHLOROPHYLL-SPECIFIC PHOTOSYNTHESIS AND QUANTUM EFFICIENCY AT SUBSATURATING LIGHT INTENSITIES12

Light-limited rates of photosynthesis normalized for chlorophyll a, (α), and actual photon absorption (quantum efficiency, Ф) were determined for six eponentially growing algal species grown under identical conditions. The same parameters, α and Ф, were also monitored for a single diatom species, Thalassiosira pseudonana Hasle & Heimdal, through its growth cycle in batch culture. Statistical differences in α could be demonstrated among the six different exponentially growing species while no differences could be shown for Ф. Statistical differences among the six species were minimized when photosynthetic rates were normalized for in vivo fluorescence rather than extracted chlorophyll a. Both α and Ф were constant while T. pseudonana was in the exponential phase of growth, but both declined as the culture entered stationary phase. While cells were in exponential growth, differences in a were attributed to varying rates of in vivo light absorption per chlorophyll a, thus providing experimental evidence that the in vivo chlorophyll a extinction coefficient, k_c (m²· mg Chl a^?1), cannot be assumed constant.     

Revertants of Adenovirus Type 12-Transformed Hamster Cell Line T637 as Tools in the Analysis of Integration Patterns

Spontaneously arising morphological revertants of the adenovirus type 12 (Ad12)-transformed hamster cell line T637 had been previously isolated, and it had been demonstrated that in these revertants varying amounts of the integrated Ad12 genome were eliminated from the host genome. In this report, the patterns of persistence of the viral genome in the revertants were analyzed in detail. In some of the revertant cell lines, F10, TR3, and TR7, all copies of Ad12 DNA integrated in line T637 were lost. In lines TR1, -2, -4 to -6, -8 to -10, and -13 to -16, only the right-hand portion of one Ad12 genome was preserved; it consisted of the intact right segment of Ad12 DNA and was integrated at the same site as in line T637. In revertant lines G12, TR11, and TR12, one Ad12 DNA and varying parts of a second viral DNA molecule persisted in the host genome. These patterns of persistence of Ad12 DNA molecules in different revertants supported a model for a mode of integration of Ad12 DNA in T637 hamster cells in which multiple (20 to 22) copies of the entire Ad12 DNA were serially arranged, separated from each other by stretches of cellular DNA. The occurrence of such revertants demonstrated that foreign DNA sequences could not only be acquired but could also be lost from eucaryotic genomes. There was very little, if any, expression of Ad12-specific DNA sequences in the revertant lines TR7 and TR12. Moreover, Ad12 DNA sequences which were found to be undermethylated in line T637 were completely methylated in the revertant cell lines G12, TR11, TR12, and TR2. These findings were consistent with the absence of T antigen from the revertant lines reported earlier. Hence it was conceivable that the expression of integrated viral DNA sequences was somehow dependent on their positions in the cellular genome. In cell line TR637, the early segments of Ad12 DNA were expressed and undermethylated; conversely, in the revertant lines G12, TR11, TR12, and TR2, the same segments appeared to be expressed to a limited extent and were strongly methylated.