Effect of aging on the morphology and function of the thyroid gland of the cream hamster

Summary The effect of aging on the morphology and function of the thyroid gland of the cream hamster was studied by light and electron microscopy coupled with autoradiography or histochemistry.Morphologically, aging induces an accumulation of lysosomal dense bodies and a loss of the phagocytosis of colloid droplets after stimulation with TSH. Iodine uptake and organification occur normally and thyroglobulin synthesis, estimated by autoradiography with ³H-leucine, is not different from that observed in young animals. The basal T₄ and T₃ plasma levels are lower in the old animals. A low iodine diet administered for several months prevents the age related accumulation of lysosomal dense bodies. Hormone secretion seems to proceed by two different mechanisms; phagocytosis of colloid droplets, the classical mechanism that decreases with age, and an additional mechanism, probably micropinocytosis, that is maintained during the whole lifespan.Presented at the First French Congress of Endocrinology, Montpellier, September 1980Work was performed under contracts n 3.4523.79 and n 3.4512.80 of the Fonds de la Recherche Scientifique Médicale, thanks to a grant of the Ministère Belge de la Politique Scientifique (Action concertée) and with the help of the Fondation Interuniversitaire pour la Recherche du Processus du Vieillissement, Belgium     

The Ostrich (Struthio camelus) egg-white lysozyme

Summary The purification of Ostrich (Struthio camelus) egg-white lysozyme is reported. The quantitative amino acid composition, the molecular weight, the N-terminal sequence (34 amino acids) as well as kinetic studies allow to range this enzyme among the goose type lysozymes.106th communication on lysozymes.     

Produits neutres et alcaloides de Myrtopsis macrocarpa,M. myrtoidea,M. novae-caledoniae et M. sellingii

Stems and leaves of Myrtopsis macrocarpa, M. myrtoidea, M. novae-caledoniae and M. sellingii yielded terpenes, sterols, coumarins, alkaloids (furoquinolines and quinolones) and amides. A new quinolone (8-methoxy flindersine) occurs in Myrtopsis macrocarpa, a new amide (N-benzoyltryptamine) in M. myrtoidea, two new coumarins (myrsellin and myrsellinol) and a new dihydrofuroquinoline (myrtopsine) in M. sellingii. Structures of the new compounds are proposed from chemical and spectroscopic evidence.     

The structure of immunoglobulin variable regions in the horned shark,Heterodontus francisci

The heavy and light chains of pooled antibodies of the hybodont shark,Heterodontus francisci (horned shark), were subjected to amino acid sequence analysis. Yield determinations showed that more than 90% of the available polypeptides in the respective pools were sequenced. The heavy chains were homogeneous in the initial framework segment and showed a sequence homology of approximately 70% with the corresponding region of the more recently evolved nurse shark and a 45% homology with a human myeloma heavy chain. The light chains were less homogeneous and not identifiable as either kappa or lambda chains as known in higher species. The first half-cystine characteristics of the variable domain intrachain disulfide bridge of immunoglobulins was present in the same position (22 for heavy chains; 23 for light chains) in the horned shark as in mammalian species. The sequence analysis also suggested the presence of a hypervariable region in the horned shark light chains. The combined data imply that the antigen-binding function of immunoglobulins is mediated in much the same manner in this primitive shark as in more recently evolved species, including mammals.     

Non-Linear Patterns of Complex Ramification Schemes in Higher Plants (Proposition for an Insight)

Die Seitenzweige von Cupressus sempervirens L. sind auf vier Orthostichen in scheinbar mehr oder weniger zufälligen, voneinander unabhängigen Mustern angeordnet. Eine auf L-Systeme sich berufende mathematische Konstruktion gestattet die Definition eines Morphismus. Acht Parameter, Periodizität der absoluten Wachstumsrate der zugrundeliegenden theoretischen Serien, die Väriation dieser Raten in komplementaren Unterserien und eine Schwellenreaktion sind die Hauptargumente.     

Aquatic ecology in The Netherlands: What is being done by whom?

Summary About one third of the Dutch environmental research is concentrated on aquatic problems. The largest number of these projects is physicochemical (65%) and 47% of the aquatic projects contains an ecological component. The aquatic research projects are executed in a large number of different research institutes. Many institutes just formulated one project (43.2%) and about 10% of the institutes formulated 10 projects. The institutes with 10 or more projects account for almost 50% of the total number of projects. However, the size of the research projects with respect to the average total personnel per year may differ considerably. The largest number of aquatic research projects is carried out in governmental institutes. This relative high share of governmental institutes has proportionally increased during the period of 1975–1982. During this period the relative shares of all the aquatic research projects with an ecological component, of the strictly ecological projects and of the ecological/physicochemical projects have also proportionally inclined. However, in absolute numbers there seems to be a decline of both ecological and non-ecological projects on aquatic problems.     

Spontaneous insertion of plant plasma membrane (H+)ATPase into a preformed bilayer

Summary The purified (H⁺ATPase from corn roots plasma membrane inserted spontaneously into preformed bilayer from soybean lipids. The yield of the protein insertion, as measured from its H⁺-pumping activity, increased as a function of lipids and protein concentrations. In optimum conditions, all the (H⁺)ATPase molecules were closely associated with liposomes, exhibiting a high H⁺-pumping activity (150,000% quenching· min^–1·mg^–1 protein of the probe 9-amino-6-chloro-2-methoxyacridine). The insertion was achieved within a few seconds. No latency of the (H⁺)ATPase hydrolytic activity was revealed when lysophosphatidylcholine was added to permeabilize the vesicles. This indicated that the (H⁺)ATPase molecules inserted unidirectionally, the catalytic sites being exposed outside the vesicles (inside-out orientation), and thus freely accessible to Mg-ATP. The nondelipidated (H⁺)ATPase could also functionally insert into bilayer from PCPEPG or PCPEPI, due to the presence of both hydrophobic defects promoted by PE, and negative phospholipids specifically required by the (H⁺)ATPase from corn roots. The detergent octylglucoside facilitated the delipidated (H⁺)ATPase reinsertion probably by promoting both a proper protein conformation and hydrophobic defects in the bilayer. Lysophosphatidylcholine facilitated the delipidated protein insertion only when hydrophobic defects were already present, and thus seemed only capable to ensure a proper protein conformation