Muscle and nerve in muscular dysgenesis in the mouse at birth: Sprouting and multiple innervation

Muscular dysgenesis (mdg) in the mouse is a recessive autosomal mutation affecting the striated musculature: during the whole gestation period, the muscles never show any sign of contractile activity. They are cytologically immature at birth, although the diaphragm is more mature than limb muscles, as confirmed by the levels of creatine phosphokinase. In both limb muscles and diaphragm the cytochemical localization of acetylcholinesterase demonstrates focal accumulations on the entire surface of $\text{mdg}\text{mdg}$ muscles, whereas such foci of acetylcholinesterase activity are restricted to a narrow end plate-rich region in $\text{+}\text{mdg}$? diaphragms. Teased single $\text{mdg}\text{mdg}$ myofiber preparations show that one myofiber can possess several foci of acetylcholinesterase, generally presenting aspects of very immature motor end plates. A study of the motor innervation, after silver nitrate impregnation, provides evidence for a spectacular overgrowth and a generalized sprouting of $\text{mdg}\text{mdg}$ nerves and axons. The $\text{mdg}\text{mdg}$ nerve terminals are generally very immature-looking, with an intense ultraterminal sprouting. Aspects suggesting a denser multiple innervation of $\text{mdg}\text{mdg}$ than $\text{+}\text{mdg}$? myofibers have been observed and choline acetyltransferase activity is increased in $\text{mdg}\text{mdg}$ tissues. Acetylcholinesterase specific activity and the number of α-bungarotoxin binding sites per milligram protein increased in $\text{mdg}\text{mdg}$ compared to $\text{+}\text{mdg}$? diaphragms. The very low amount of 16 S (and 12 S) acetylcholinesterase is probably related to $\text{mdg}\text{mdg}$ muscle inactivity. If the cytological and biochemical data are compared, it seems possible to propose that $\text{mdg}\text{mdg}$ myofibers and axons are in contact in several regions of the same myofiber, in variably mature appositions, and with a very dense multi-innervation.     

Microphotometric measurement of initial maximum reaction rates in quantitative enzyme histochemistryin situ

Summary Final reaction product formation was recorded microphotometrically for succinate dehydrogenase in cross-sectioned muscle fibres at initial rate conditions and during prolonged incubations. Incubations with gel films and aqueous reaction medium both showed a decline of reaction rates. Maximum reaction rates could only be determined at initial rate conditions during the first minute of the incubation. Reaction rates recorded in different areas of the same tissue section were found to change with time to different degrees. From these results it was concluded that quantitative histochemical measurements of enzyme reactionsin situ can only be valid if measured under initial maximum velocity conditions.     

Les otolithes des Téléostéens du Plio-Pleistocène belge

The study of approximately twenty three thousand otoliths from Plio-Pleistocene sites in the harbour region of Antwerp, as well as a critical revision of already published material allowed us to identify a teleostean fauna with fourty seven species (including two subspecies and seven species in open nomenclature). Two of these, Ophidion springeri and Uranoscopus septentrionalis are new to science. The fauna is typical for coastal waters slightly warmer than those of the actual North Sea and caracterized by the predominance of Gadidae. Biostratigraphically this fauna is well individualized with respect to preceeding ones (only seven species in common with the Miocene fauna) and those following twenty-three species in common with the extant fauna). The following biostratigraphical subdivision has been recognized in the Upper Miocene and the Plio-Pleistocene of the Antwerp region: (1) an association with «genus? Macrouridarum labiatus, Trisopterus sculptus, Gadiculus benedeni and Trisopterus luscus spectabilis, in the Sands of Deurne (Upper Miocene); (2) an association with Gadiculus benedeni and Merlangius pseudaeglephinus, in the Formation of Kattendijk (Pliocene); (3) an association with Gadiculus verticalis and Merlangius pseudaeglefinus in the Formation of Lillo (Plio-Pleistocene); (4) an association with Gadus morhua and Merlangius pseudaeglefinus in the so called «Icenian deposits not present in Belgium but found in the Netherlands.     

Observations nouvelles sur les otolithes des Téléostéens du Calcaire Grossier (Eocène du bassin de Paris)

An important new collection of otoliths from theCalcaire Grossier of the Paris Basin, as well as a critical review of already published material is studied and reveals the presence of 56 species. Five of these are new: Muraenesox spatulus, Genus Synodontidarum intermedius, Genus Ophidiidarum spinosus, Chanda bohlkei and Mene sekharani. The assemblage is indicative of tropical to subtropical marine and neritic environment with solid bottom. Biogeographically, it shows affinities with the recent Indo-pacific fauna. The association of the sites at Fercourt and Château-Rouge is clearly different from the one found at the sites of Condé-en-Brie and Damery, as it is less littoral than the second association mentioned.     

Non-random intrachromosomal distribution of chromatid aberrations induced by X-rays,alkylating agents and ethanol in Vicia faba

A reconstructed karyotype of Vicia faba with all chromosomes individually distinguishable was treated with triethylene melamine (TEM), cytostasan (CYT) (a new benzimidazol nitrogen mustard), mitomycin C (MI), ethanol (EA) and X-rays. The distribution within chromosomes of induced chromatid abberations was non-random for all agents. The number of segments involved in aberration clustering corresponded to the number of sites representing constitutive heterochromatin, or the regions immediately adjacent to these, as evidenced by the position of Giemsa marker bands. Which of these potential regions of aberration clustering reacted with preferential involvement in aberrations was, in part at least, dependent upon the inducing agent used. It is argued that this may be due to differences in the base composition and/or molecular conformation of heterochromatic regions. Unexpectedly, the distribution pattern of chromatid aberrations induced by mitomycin C was found to be different from those after treatment with the alkylating agents TEM and cytostasan although mitomycin C is assumed to induce aberrations via alkylation. If mitomycin C-induced aberrations are indeed due to alkylation, this indicates that different alkylating agents do not necessarily result in identical patterns of abberation clustering. The other two alkylating agents and ethanol resulted in similar patterns of preferential distribution of abberations. X-Ray induced chromatid aberrations also showed a non-random intrachromosomal distribution, but the clustering was less pronounced than after treatment with the chemical agents.     

Molecular Co-occupancy Identifies Transcription Factor Binding Cooperativity In Vivo

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Development,characterization, and application of a 2‐Compartment system to investigate the impact of pH inhomogeneities in large‐scale CHO‐based processes

Large‐scale bioreactors for the production of monoclonal antibodies reach volumes of up to 25 000 L. With increasing bioreactor size, mixing is however affected negatively, resulting in the formation of gradients throughout the reactor. These gradients can adversely affect process performance at large scale. Since mammalian cells are sensitive to changes in pH, this study investigated the effects of pH gradients on process performance. A 2‐Compartment System was established for this purpose to expose only a fraction of the cell population to pH excursions and thereby mimicking a large‐scale bioreactor. Cells were exposed to repeated pH amplitudes of 0.4 units (pH 7.3), which resulted in decreased viable cell counts, as well as the inhibition of the lactate metabolic shift. These effects were furthermore accompanied by increased absolute lactate levels. Continuous assessment of molecular attributes of the expressed target protein revealed that subunit assembly or N‐glycosylation patterns were only slightly influenced by the pH excursions. The exposure of more cells to the same pH amplitudes further impaired process performance, indicating this is an important factor, which influences the impact of pH inhomogeneity. This knowledge can aid in the design of pH control strategies to minimize the effects of pH inhomogeneity in large‐scale bioreactors.