Motor innervation of the cat muscle spindle studied by the cholinesterase technique

Summary Muscle spindles were traced in serial transverse sections of cat tenuissimus muscles. Myofibrillar adenosine triphosphatase staining reaction was used to identify nuclear bag₁, nuclear bag₂ and nuclear chain intrafusal muscle fibers. Typical chain fibers and long chain fibers were distinguished, the latter extending for more than 1,000 m beyond the termination of the spindle capsule. Simple rim and more elaborate plate deposits were demonstrated histochemically along the poles of the typical chain fibers in staining for cholinesterases. They were considered to correspond, respectively, to the trail and plate motor nerve terminals. Most long chain fibers and the majority of nuclear bag fibers had their motor innervation limited to plate-type endings. In addition, faint diffuse cholinesterase staining occurred along the spindle capsule and the surface of some intrafusal fibers. These histochemical observations are discussed with regard to the current concepts concerning the morphological and functional organization of the motor innervation of the cat muscle spindle.     

Solution conformations of proline rings in proteins studied by NMR spectroscopy

Summary Three different conformations of proline rings in a protein in solution, Up, Down and Twist, have been distinguished, and stereospecific assignments of the pyrrolidine -, - and -hydrogens have been made on the basis of ¹H-¹H vicinal coupling constant patterns and intraresidue NOEs. For all three conformations, interhydrogen distances in the pairs -³, ³-³, ²-², ²-², and ³-³ (2.3 Å) are shorter than those in the pairs -², ²-³, ³-², ²-³, and ³-² (2.7–3.0 Å), resulting in stronger NOESY cross peaks. For the Up conformation, the ³-² and ²-³ spin-spin coupling constants are small (<3 Hz), and weak cross peaks are obtained in a short-mixing-time (10 ms) TOCSY spectrum; all other vicinal coupling constants are in the range 5–12 Hz, and result in medium to strong TOCSY cross peaks. For the Down form, the -², ²-³, and ³-² vicinal coupling constants are small, leading to weak TOCSY cross peaks; all other couplings again are in the range 5–12 Hz, and result in medium to strong TOCSY cross peaks. In the case of a Twist conformation, dynamically averaged coupling constants are anticipated. The procedure has been applied to bovine pancreatic trypsin inhibitor and Cucurbita maxima trypsin inhibitor-V, and ring conformations of all prolines in the two proteins have been determined.     

Mg2+ Induces Conformational Changes in the Catalytic Subunit of Phosphorylase Kinase, Whether by Itself or as Part of the Holoenzyme Complex

Phosphorylase kinase (PhK) from skeletal muscle is a structurally complex, highly regulated, hexadecameric enzyme of subunit composition ()₄. Previous studies have revealed that the activity of its catalytic subunit is controlled by alterations in quaternary structure initiated at allosteric and covalent modification sites on PhK's three regulatory subunits; however, changes in the conformation of the holoenzyme initiated by the catalytic subunit have been more difficult to document. In this study a monoclonal antibody (mAb 79) has been generated against isolated subunit and used as a conformational probe of that subunit. The epitope recognized by this antibody is within the catalytic core of the subunit, between residues 100 and 240, and monovalent fragments of the antibody inhibit the catalytic activity of the holoenzyme, the -calmodulin binary complex, and the free subunit. Activation of PhK by a variety of mechanisms known or thought to act through its regulatory subunits (phosphorylation, ADP binding, or alkaline pH) increased the binding of the holoenzyme to immobilized mAb 79, indicating that activation by any of these distinct mechanisms involves repositioning of the portion of the catalytic domain of the subunit containing the epitope for mAb 79. The activating ligand Mg²⁺ also stimulated the binding of the PhK holoenzyme to immobilized mAb 79, as well as the binding of mAb 79 to immobilized subunit. Thus, Mg²⁺ increases the accessibility of the mAb 79 epitope in both the isolated subunit and in the holoenzyme. Our results suggest that previously reported influences of Mg²⁺ on the quaternary structure of the PhK holoenzyme are directly mediated by the subunit.     

Meiotic studies ofElymus nutans andE. jacquemontii (Poaceae,Triticeae) and their hybrids withPseudoroegneria spicata and seventeenElymus species

Hybridizations ofElymus nutans andE. jacquemontii were carried out with one species ofPseudoroegneria (S genome), and 20Elymus species, each containing either of the SH, SY, SYH, or SYW genomes. Chromosome configurations were analysed at metaphase I of the two target taxa and their interspecific hybrids. It is concluded that (i)E. nutans is an allohexaploid containing the SYH genomes, andE. jacquemontii is an allotetraploid having the SY genomes; (ii) the genomic affinity is associated with the geographic distance between the species studied; (iii) minor genomic structural rearrangements have occurred within the hexaploid taxon ofE. nutans.     

Observations on the fine structure of the cercaria of Notocotylus attenuatus and formation of the cyst wall of the metacercaria

Summary The dorsal tegument of the mature cercaria of Notocotylus attenuatus is a syncytial, cytoplasmic layer, containing two types of secretory granule which are identifiable ultrastructurally. The type 1 secretory bodies are electron lucid, whereas most type 2 granules have a banded appearance. The ventral tegument contains granules which are secreted from the type 3 cells; the type 3 granules are membrane bound, electron dense, and consist of both an amorphous and a finely striated zone. The type 4 cells mainly contain cigar-shaped granules consisting of an amorphous core surrounded by concentric striations. The granules exhibit structural variability in shape and content. The type 4 cells undergo a cellular migration to the tegument during encystment. The structure of the posterior-lateral glands and mode of secretion of the granules are described. Possible functions of microtubules are discussed for each cell type. Details of some secretory processes involved in the formation of the hemispherical cyst wall are described. The layers of the cyst wall may be related to the granular contents of the various parenchymal cells of the cercaria. The tegument of the metacercaria originates primarily from the cytoplasm of the type 1, type 2, type 3 and type 4 cells.     

A new enzymatic route to the synthesis of 12-ketoursodeoxycholic acid

Summary Cholic acid (3,7,12-trihydroxy-5-cholanoic acid) was completely and selectively transformed into 12-ketoursodeoxycholic acid (3,7-dihydroxy-12-oxo-5-cholanoic acid) by means of two consecutive enzymatic steps catalyzed, the first, by 7- and 12-hydroxysteroid dehydrogenase and, the second, by 7-hydroxysteroid dehydrogenase. Coenzyme regeneration was carried out with -ketoglutarate-glutamate dehydrogenase and glucose-glucose dehydrogenase, respectively.     

Increase of catalytic activity of α-chymotrypsin in organic solvent by co-lyophilization with cyclodextrins

-Chymotrypsin was lyophilized in the presence of 2,3,6-tri-O-methyl -cyclodextrin, and it displayed activity 40 fold higher than free -chymotrypsin for transesterification in acetonitrile. -Chymotrypsin which was co-lyophilized with hydroxypropylated - or -cyclodextrins retained more than 98% of its initial activity after 6 h incubation in acetonitrile.     

Polygonal inequalities as a key to neuronic equations

Neuronic or decision equations, first proposed as a mathematical model of neural activity, have shown, after their exact, compact solution was found, typical behaviours that make them natural tools for General Systems studies. It is shown here that their mathematical investigation is remarkably furthered by generalizing the triangular inequality to polygonal ones. These permit the immediate computation of the tensorial expansion of linearly separable boolean functions, and exhibit clearly the connection between their continuous and discontinuous aspects.     

A frequent Aγ-persistence of fetal hemoglobin in northern Sardinia: its molecular basis and hematologic phenotype in heterozygotes and compound heterozygotes with β-thalassemia

Summary A survey of hemoglobinopathies in northern Sardinia revealed a high frequency (0.3%) of carriers of a hematologic condition characterized by increased expression of fetal hemoglobin during adult life (hereditary persistence of fetal hemoglobin or HPFH). In spite of a normal hematologic phenotype, the heterozygous carriers for this condition display about 12% HbF, almost exclusively of the ^A type; compound heterozygotes with -thalassemia have 20%–26% HbF and run a very mild clinical course. The sequence analysis of the cloned ^A gene linked to the HPFH determinant revealed the presence of a GA substitution at position-117 of the ^A- gene promoter; the same mutation occurs also in Greek HPFH, although associated with different restriction polymorphisms. Another hereditary condition characterized by increased HbF (₂ ^A₂) level and a mild thalassemic phenotype in Sardinia is associated with the-196 CT substitution in the ^A-globin gene promoter (Sardinian -thalassemia). Population studies using oligonucleotides complementary both to the-117 GA and-196 CT mutations and the corresponding normal sequences confirm the presence of these mutations only in HPFH and -thalassemia chromosomes and exclude these changes being common DNA polymorphisms.     

Pancreatic glucagon cells contain endorphin-like immunoreactivity

Summary On the basis of the histochemical activity of succinic dehydrogenase, only two fibre-types are distinguished in pigeon pectoralis major muscle. These are narrow Red and broad White. The histochemical activity of myofibrillar ATPase was studied in these two distinct fibre-types. Both fibre-types showed high activity for the ATPase. Red fibres of pigeon pectoralis were not alkali-labile, at incubation pH 9.4, as were the Type I fibres of both avian and mammalian muscles. Again unlike Type I fibres, the Red fibres of pigeon pectoralis lacked the characteristic activation of acid-preincubated ATPase reaction. Pigeon pectoralis Red fibres are known to posses some characteristics of fast-twitch fibres (e.g. high fat, considerable phosphorylase, fibrillenstruktur myofibrillar arrangement, focal en plaque pattern of nerve endings). It is emphasized, therefore, that the pigeon pectoralis Red fibres are not equivalent to Type I or slow-twitch, muscle fibres, but they are possibly fast-twitch fatigue resistent or Type II Red muscle fibres.     

A comparison of male and female recombination frequency in wheat using RFLP maps of homoeologous group 6 and 7 chromosomes

A novel approach was used to compare male and female recombination rates in wheat. Doubled haploid lines were developed from an F₁ using two distinct approaches: the anther-culture technique and the Hordeum bulbosum system, from which sets of lines were developed from male and female meioses, respectively. The genotype of the lines was established at RFLP and isozyme markers polymorphic on chromosomes of homoeologous groups 6 and 7, and male and female linkage maps were calculated using this information. The markers in one segment of chromosome 6B exhibited disturbed segregation frequencies in the anther-culture population. The male and female maps differed significantly in recombination frequency between some markers on two chromosomes, and these were consistent in direction within chromosomes and inconsistent in direction between chromosomes. In two of the four chromosomes studied the male map was much longer than the female map. These results suggest that significant differences may exist in male and female recombination frequencies in bread wheat which are specific to certain chromosomal segments but are inconsistent in direction between chromosomes. Other factors, such as environmental influences, may also be important in creating differences.     

Effect of cooling on spike trains from skin receptors

Quantitative characteristics of the afferent flow in a cutaneous nerve during cooling of the skin in cats were determined by the cross-correlation method. Lowering the skin temperature by 10°C with different gradients of cooling led to the appearance of activity in A-, A-, and C-fibers. The first fibers to become excited were C-fibers, followed in turn by A-fibers, a group of slowly-conducting A-fibers, and a group of fast-conducting A-fibers. The latent period of excitation of the C-fibers remained unchanged whatever the rate of skin cooling, whereas in A-fibers it increased with slowing of the rate of fall of temperature. The level of maximal activity neither in A- nor in C-fibers depended on the gradient of skin cooling, but in all the groups of fibers mentioned the time taken to reach the maximum of activity decreased with an increase in the rate of cooling.Research Institute of Applied Mathematics and Cybernetics, N. I. Lobachevskii State University, Gor'kii. Translated from Neirofiziologiya, Vol. 12, No. 4, pp. 405–412, July–August, 1980.     

Ultrastructure of motor nerve terminals on different types of muscle fibers in the atlantic hagfish (Myxine glutinosa,L.)

Summary White and intermediate parietal muscle fibers of Myxine are innervated focally at one end. Most synaptic vesicles are empty. These terminals also contain 1–2% large 800–1.100 Å dense-core vesicles. Red fibers of parietal and craniovelar muscle are innervated in a distributed fashion, and the presynaptic profiles contain a higher number of large dense-core vesicles (averaging 9% and 15%, respectively; up to 37%). For all terminals the synaptic gap is 450–600 Å wide, and postsynaptic folds are absent.Empty synaptic vesicles exist as round or elongated profiles. The proportion of elongated profiles increases by formation from round ones when increasing the molarity of the buffer in the aldehyde fixative. Furthermore, the proportion of elongated vesicle profiles in terminals on Myxine white fibers at different buffer molarities, is identical with that in mammalian motor terminals at similar molarities. On this basis the significance and mode of formation of elongated vesicle profiles is discussed. The conclusion is made that the susceptibility of flattening depends on the osmotic pressure of the vesicle contents once the aldehyde has influenced the vesicle membrane.The different vesicle populations in terminals on different types of muscle fibers are significant. Terminals on red fibers probably contain serotonin (5-HT) either as sole transmitter or in addition to acetylcholine.The author is indebted to Dr. Finn Walvig, Biological Station, University of Oslo, Drøbak, for supply of hagfishes, and to Mrs. Jorunn Line Vaaland for expert technical assistance.     

Morphology and structural organization of spiracles in femaleArgas (Persicargas) walkerae (Acari: Argasidae)

Scanning electron microscopical investigations of fractures and corrosion casts of the spiracles from femaleA. walkerae ticks revealed a four-part structure, consisting of spiracular plate, ostium and macula forming the external closure, followed by the subostial space and the vestibulum of regulable volume, as well as the atrial chamber as the innermost part from which the main tracheal trunks originate. On the average, the spiracular plate was 158 m long and 188 m at the broadest width. It consisted of a thin, highly perforated external and a thick internal layer, which enclosed the interpedicellar space with numerous stout pedicels. In its posterior region, the spiracular plate was covered by the macula, which was up to 80 m in length and 110 m in width. The interpedicellar cavity opened into the subostial space measuring 95.5 m in length and 159.6m in width, which proceeded into the 112-m long vestibulum. The roof of the vestibulum was flexible and could be everted and inverted. Inverted, the roof formed a quadratic bulge with numerous deep cuticular folds, which confined the lumen of the vestibulum either partially or completely. In corrosion casts, the roof was everted to a length of up to 89.3 m. In the posterior part of the vestibulum, as well as in the initial fourth of the artrial chamber, numerous anvil-, cone-or drop-like cuticular projections were arranged in wedge-like fashion. The atrial chamber was almost spherical with a diameter of 138.4 m. Five main tracheal trunks of different luminal diameter as well as numerous channels opened into the atrial chamber.     

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     

Integrins: cell adhesives and modulators of cell function

Summary Integrins encompass a family of cell-surface molecules which play a crucial role in cell-cell and cell-extracellular matrix interaction. Of these heterodimeric transmembrane glycoproteins (consisting of an and chain) as yet at least 20 different types have been described, all with a different pattern of reactivity with extracellular matrix components. In this review the cell and tissue distribution of the integrins is discussed, with special emphasis on immunohistochemical localization of the ₁ integrins and the ₆₄ integrin. The ₁ integrins comprise a subfamily in which eight chains combine with one (the ₁) chain. The ₂₁, ₃₁ and ₆₁ and the ₆₄ integrins are expressed on a wide variety of epithelia on the basolateral surface or exclusively on the basal surface facing the basement membrane (e.g. ₆₁ and ₆₄). Leucocyte integrins, which share a common ₂ chain, occur almost exclusively on white blood cells and their precursors. The vitronectin receptors, which share a common _v chain, occur in a wide variety of cell types. Integrins play a major role in the interaction of the cell with the extracellular matrix in order to create and maintain tissue architecture. It has become clear, however, that through integrin-ligand interaction cell function is also modulated. Furthermore, in pathological conditions integrins play a role of some significance. Integrins mediate leucocyte traffic in developing inflammatory processes and function in neoplastic growth when it comes to invasion and metastasis.     

Ultrastructure of four types of striated muscle fibers in the atlantic hagfish (Myxine glutinosa,L.)

Summary Four types of striated muscle fibers with distinctive ultrastructure were defined in the Atlantic hagfish (Myxine glutinosa, L.): white, intermediate, and red fibers of m. parietalis, and red fibers of m. craniovelaris.White fibers are thick, contain very few mitochondria and fat vacuoles, and possess distinct and separate myofibrils with thin Z-disks and distinct M-lines. Intermediate fibers are thinner, possess largely similar myofibrils that often are even better separated due to a higher content of fat vacuoles and especially mitochondria and glycogen granules. Red fibers of m. parietalis contain large amounts of mitochondria, fat vacuoles, and glycogen granules. Their myofibrils possess M-lines, and although branching more, the myofibrils of red fibers conform with a Fibrillenstruktur pattern like those of white and intermediate fibers. Red fibers of m. craniovelaris are very thin, possess many smaller fat vacuoles, and large amounts of mitochondria and glycogen granules. The myofibrils are significantly thinner than in m. parietalis fibers, run as quite independent well separated units, possess thicker Z-disks, and lack M-lines. Large amounts of myosatellite cells are associated with these red fibers.Triads are located near A/I-junctions in all four fiber types and occur irregularly, the density of triads being different in the various fiber types.We are indebted to Dr. Finn Walvig, Biological Station, University of Oslo, Drøbak, for supply of hagfishes, and we also wish to thank Dr. Jan K. S. Jansen, Institute of Physiology, University of Oslo, for valuable suggestions during this study.     

Characterization of maltose biosynthesis from α-d-glucose-1-phosphate in Spinacia oleracea. L.

The de novo synthesis of maltose in spinach (Spinacia oleracea L.) was shown to be catalyzed by a maltose synthase, which converts two molecules of -d-glucose-1-phosphate (-G1P) (K_m 1.5 mmol l^-1) to maltose and 2 orthophosphate (Pi). This enzyme was purified 203-fold by fractionated ammonium sulfate precipitation and by column chromatography on Sepharose 6B. The addition of -G1P (15 mmol l^-1) to the isolation buffer is required to stabilize the enzyme activity during the extraction and purification procedure. Molecular weight determination by gel filtration yielded a value of 95,000. -Gluconolactone, ATP and Pi are competitive inhibitors toward the substrate -G1P. The maltose synthase catalyzes an exchange of the phosphate group of -G1P with [³²P] orthophosphate; this transfer reaction suggests that the synthesis of maltose occurs via a glucose-enzyme in a double displacement reaction. The physiological role of this enzyme as a starch initiator system is discussed.Abbreviations Fru fructose - Glc glucose - -G1P -d-glucose-1-phosphate - -G1P -d-glucose-1-phosphate - G6P d-glucose-6-phosphate This enzyme is tentatively called maltose synthase in this publication