Liming induced stimulation of the amino acid metabolism in mycorrhizal roots of Norway spruce (Picea abies [L.] Karst.)

Localization and activity of three enzymes involved in the amino acid metabolism of ectomycorrhizas were investigated within an interdisciplinary experiment performed in a mature Norway spruce stand in Southern Germany (Höglwald). The enzymes NAD-glutamate dehydrogenase and aspartate aminotransferase were present in root cells, whereas aminopeptidase was found in mycorrhizas of Norway spruce such as Piceirhiza nigra and those with the fungi Cenococcum geophilum, Elaphomyces sp., Russula ochroleuca and Tylospora sp. Mycorrhizas growing in the humus layer contained about double the amount of protein found in those taken from the upper mineral soil (0–5 cm).Acid irrigation of the soil had no effect on the activity of any of the investigated enzymes, soluble protein or total N-contents irrespective of whether roots were taken from the organic layer or from the upper mineral soil. Liming, however, stimulated the activity of the three enzymes in mycorrhizas of the organic layer (O_f+O_h) whereas it had no effect on the activity of the investigated enzymes of mycorrhizas in the upper mineral soil. This effect is attributed to increased contents of soluble organic nitrogen compounds in the soil of the limed plots as compared to the unlimed plots.     

Effect of visual deprivation on neurotransmitter receptor development in the rat visual system

The effect of monocular deprivation (covering one eye on the 11th posnatal day) and rearing in darkness (the animals were born, developed, and killed with total exclusion of light) on development of -adrenergic, serotoninergic, muscarinic cholinergic, glutamatergic, and benzodiazepine receptors in primary visual structures (visual cortex, lateral geniculate body, superior colliculus, and retina) was investigated in rats. For quantitative analysis of neurotransmitter receptors, the technique of ligand binding was used. It was shown that monocular deprivation affects the development of -adrenergic, serotoninergic, and glutaminergic receptors mainly in the lateral geniculate body and retina, whereas rearing in darkness affects mainly the development of serotoninergic receptors in the superior colliculus. The development of receptors of the cholinergic neurotransmitter system is disturbed only temporarily by visual deprivation. Changes found in receptor development after visual deprivation indicate altered activity of different neurotransmitter systems in corresponding visual structures.P. Flechsig Brain Research Institute, Leipzig, East Germany. Karl Marx University, Leipzig, East Germany. Translated from Neirofiziologiya, Vol. 16, No. 5, pp. 691–701, September–October, 1984.     

Crypt architecture of tonsilla lingualis in the monkey,Macaca fascicularis

Summary Crypts of the lingual tonsil were investigated in 10 male and female Macaca fascicularis by use of correlated light and scanning-electron microscopy. Counting of crypt openings provided an estimate of the total number of respective crypto-lymphatic units, which were found to range from 20 to 39. Crypt openings appeared in three distinct morphological varieties, i.e. circular, oval or slit-like. Tonsillar units existed individually or were arranged in a rosary fashion below a slit-like mucosal fold serving as a common exit. Although the crypt epithelium was generally non-keratinized, individual cells showing a surface pattern similar to that of the keratinized cells could be encountered. The crypt epithelium was frequently fragmented and showed heavy mononuclear cell infiltration and surface discontinuities, with lymphoid cells coming in contact with luminal contents. The crypt lumen either appeared as a simple epithelial invagination or existed as a complex, cavernous pouch with many blind-ending diverticula. The lumen contained a mixture of exfoliated epithelial cells, leucocytes and bacteria. The secretory ducts of the posterior lingual glands opened occasionally at various levels into the crypt lumina or independently to the exterior.     

Morphological investigations on follicular atresia in canine ovaries

Summary Morphologically, canine ovaries show two types of regression pattern in secondary follicles. In type A necrotic changes of the oocytes and the zona pellucida dominate, whereas in type B degeneration, necrobiosis and necrosis of the granulosa prevail. The atretic course of type B regression results in a pseudoantrum and leads, by pseudogrowth, to a structure imitating tertiary follicles. In both type A and type B regression, four consecutive stages of atresia are distinguished by light- and electron microscopy.True tertiary follicles display only one regression pattern which resembles type B of secondary follicles. Early, advanced, late, and terminal stages of atresia are again described.     

The human MUC2 intestinal mucin has cysteine-rich subdomains located both upstream and downstream of its central repetitive region.

The human MUC2 mucin is a large secretory glycoconjugate that coats the epithelia of the intestines, airways, and other mucus membrane-containing organs. Previous work has shown that this mucin contains an extended tandem repeat-containing domain rich in Thr and Pro. In the present work we describe two additional regions of this mucin located both upstream and downstream of the tandem repeat array. The carboxyl-terminal domain contains 984 residues and can be divided into mucin-like (139 residues) and cysteine-rich (845 residues) subdomains. This latter subdomain exhibits varying degrees of sequence similarity to a wide range of mucins and mucin-like proteins including those isolated from rats, pigs, cows, and frogs. We also report here the sequence of 1270 residues lying immediately upstream of the tandem repeats. This region contains a repetitive, mucin-like subdomain and a second cysteine-rich stretch of more than 700 residues. Both cysteine-rich subdomains of this mucin have sequence similarity with von Willebrand factor, a serum protein that exists as a disulfide-linked polymer. This suggests that these cysteine-rich subdomains are important in the catenation of mucin monomers into oligomers, the structures that confer viscoelasticity upon mucus.     

Conformation and formation tendency of the cyclotetrapeptide cyclo (D-Pro-D-Pro-L-Pro-L-Pro): experimental results and molecular modeling studies

The title compound represents the smallest member of cyclic proline peptides corresponding to the general formula c(DDLL-Pro4)n with a strictly D,D,L,L double-alternating sequence of the chiral amino acid residues. The cyclopeptides with n greater than or equal to 2 could be synthesized from both DDLL-Pro4 (1) and DLLD-Pro4 (2). The cyclic monomer (n = 1) resulted only from 2, whereas not even a trace could be found by cyclization of 1. The peptide exists in a strongly strained Ci symmetrical conformation (x-ray analysis) with alternating cis and trans peptide bonds (ctct form I). The cis peptide bonds deviate from planarity (omega = 22 degrees); two of the pyrrolidine rings show a "South" conformation (phi = -94 degrees), whereas the other residues exhibit C alpha-endo puckering (phi = -124 degrees). Two of the psi angles surprisingly occur at +41 degrees (anti-cis'), the others are located in the trans' region. A quantitative ring opening occurs with trifluoroacetic acid at room temperature. In solution the existence of an isomeric ctcc sequence (form Ia) is indicated. Dreiding model studies also suggested a favorable conformation with a tctc sequence (form II). Consequently, we performed molecular mechanics calculations, based on the CHARMM force field and semiempirical quantum mechanical AM1 calculations (MOPAC program). Pronounced differences in the backbone parameters were found using these two methods. However, the theoretical studies evidenced the experimentally obtained differences in the cyclization tendencies of the linear precursors.     

Reflex control of vascular capacitance during hypoxia, hypercapnia, or hypoxic hypercapnia

We tested the hypothesis that the changes in venous tone induced by changes in arterial blood oxygen or carbon dioxide require intact cardiovascular reflexes. Mongrel dogs were anesthetized with sodium pentobarbital and paralyzed with veruronium bromide. Cardiac output and central blood volume were measured by indocyanine green dilution. Mean circulatory filling pressure, an index of venous tone at constant blood volume, was estimated from the central venous pressure during transient electrical fibrillation of the heart. With intact reflexes, hypoxia (arterial PaO2 = 38 mmHg), hypercapnia (PaCO2 = 72 mmHg), or hypoxic hypercapnia (PaO2 = 41; PaCO2 = 69 mmHg) (1 mmHg = 133.32 Pa) significantly increased the mean circulatory filling pressure and cardiac output. Hypoxia, but not normoxic hypercapnia, increased the mean systemic arterial pressure and maintained the control level of total peripheral resistance. With reflexes blocked with hexamethonium and atropine, systemic arterial pressure supported with a constant infusion of norepinephrine, and the mean circulatory filling pressure restored toward control with 5 mL/kg blood, each experimental gas mixture caused a decrease in total peripheral resistance and arterial pressure, while the mean circulatory filling pressure and cardiac output were unchanged or increased slightly. We conclude that hypoxia, hypercapnia, and hypoxic hypercapnia have little direct influence on vascular capacitance, but with reflexes intact, there is a significant reflex increase in mean circulatory filling pressure.     

Effect of cold environment on skeletal muscle mitochondria in growing rats

Summary Growing rats (4 weeks old) were kept for 3 weeks at 11° C and 24° C respectively. The cold-adapted animals showed a significantly higher oxygen consumption (64%). Volume density of subsarcolemmal and interfibrillar mitochondria as well as volume density of fat droplets were estimated in M. soleus and the diaphragm of both groups. In cold-adapted animals, the total volume of mitochondria was significantly increased by 24% in diaphragm and 37% in M. soleus. The volume of subsarcolemmal mitochondria was almost doubled in each muscle, but the volume of interfibrillar mitochondria did not change significantly. The surface of the inner mitochondrial membranes per unit volume of mitochondrion in M. soleus was significantly increased both in interfibrillar and subsarcolemmal mitochondria, whereas the surface of the outer mitochondrial membranes per unit volume of mitochondrion was increased only in the subsarcolemmal mitochondria. The volume of fat droplets in the diaphragm and M. soleus of cold adapted animals increased significantly by 62% and 150% respectively.