Sialyl-transferase mitochondriale

A sialyl transferase activity is found in purified mitochondria. It is not due to residual contamination and this enzymatic system is located in the outer mitochondrial membrane. This proves mitochondrial autonomy in regard to glycoconjugate sialylation.     

Electron microscopic study of the mandibular glands of Kalotermes flavicollis Fabr. (Isoptera; Calotermitidae)

Summary The mandibular glands of Kalotermes were examined in different castes. They showed sexual dimorphism in the soldiers and primary reproductives. Moreover, in female soldiers and queens, mandibular gland cells contained numerous crystalline structures of mitochondrial origin. The role of these glands (secretion of saliva or pheromone) is discussed.

---

Résumé Les glandes mandibulaires de Calotermes sont étudiées dans les différentes castes. Elles présentent un dimorphisme sexuel chez les soldats et les sexués. Après la mue imaginale, les cellules glandulaires ont toujours une activité sécrétrice. De plus, chez les soldats femelles et les reines, elles contiennent de nombreuses formations cristallines d'origine mitochondriale. Le rôle de ces glandes (sécrétion de salive ou de phéromone) est discuté.

     

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.     

Iodine intakes assessed by urinary iodine concentrations in healthy children aged ten months,two years,and four years

Urinary iodine excretion was assessed in 642 healthy children aged 10 mo (n=243), 2 yr (n=183), and 4 yr (n=216) living in the Paris area and originating from continental France (60.3%), North Africa (13.8%), the West Indies (9.1%), West Africa (8.3%), Southeast Asia (4.8%), and southern Europe (3.8%). Mild impairment of neurological (reflexes, tone, audiometry) and intellectual development (Brunet-Lézine scale) was assessed in relation to iodine status. Iodine excretions (median values) were 18.4, 11.9, and 10.9 μg/100 mL at 10 mo, 2 yr, and 4 yr, respectively, and risk of mild iodine deficiency (5–10 μg/100 mL) was 18.1%, 34.8%, and 38.3% for the same age groups. No relationship was found between anthropometry, global development quotient, and iodine status. High hearing thresholds were more commonly associated with lower iodine excretion, suggesting mild hearing defects. In spite of iodine prophylaxis, the risk of mild to moderate iodine deficiency still exists in France and in a number of European countries. Evaluation of neurological sequels of borderline iodine status is a major public health problem in European communities.     

Morphology and morphodynamics of the stenotele nematocyst of Hydra attenuata Pall. (Hydrozoa,Cnidaria)

This light- and electron-microscopic study has investigated the structure, the morphodynamics of discharge, and the impact of the stenotele cyst of Hydra attenuata (Hydrozoa, Cnidaria) on the prey's integument. The triggered capsule, which is ejected from the cell, discharges its tubular content (shaft, stylets and tubule) by a process of evagination. In doing so the three joined stylets punch a hole into the cuticle of the prey through which the long evaginating tubule penetrates into the interior of the target. The behaviour of the tubule is described in detail and the functional significances of the various parts of the capsule are discussed.     

Effect of the natural ATPase inhibitor on the binding of adenine nucleotides and inorganic phosphate to mitochondrial F1-ATPase

(1) Incubation of the beef heart mitochondrial ATPase, F₁ with Mg-ATP was required for the binding of the natural inhibitor, IF₁, to F₁ to form the inactive F₁-IF₁ complex. When F₁ was incubated in the presence of [¹⁴C]ATP and MgCl₂, about 2 mol ¹⁴C-labeled adenine nucleotides were found to bind per mol of F₁; the bound ¹⁴C-labeled nucleotides consisted of [¹⁴C]ADP arising from [¹⁴C]ATP hydrolysis and [¹⁴C]ATP. The ¹⁴C-labeled nucleotide binding was not prevented by IF₁. These data are in agreement with the idea that the formation of the F₁-IF₁ complex requires an appropriate conformation of F₁. (2) The ¹⁴C-labeled adenine nucleotides bound to F₁ following preincubation of F₁ with Mg-[¹⁴C]ATP could be exchanged with added [³H]ADP or [³H]ATP. No exchange occurred between added [³H]ADP or [³H]ATP and the ¹⁴C-labeled adenine nucleotides bound to the F₁-IF₁ complex. These data suggest that the conformation of F₁ in the isolated F₁-IF₁ complex is further modified in such a way that the bound ¹⁴C-labeled nucleotides are no longer available for exchange. (3) ³²P_i was able to bind to isolated F₁ with a stoichiometry of about 1 mol of P_i per mol of F₁ (Penefsky, H.S. (1977) J. Biol. Chem. 252, 2891–2899). There was no binding of ³²P_i to the F₁-IF₁ complex. Thus, not only the nucleotides sites, but also the P_i site, are masked from interaction with external ligands in the isolated F₁-IF₁ complex.     

Cell-free synthesis of glial fibrillary acidic protein

Glial fibrillary acidic (GFA) protein has been synthesized in an RNA-dependent cell-free system derived from rabbit reticulocytes. The cell-free synthesized product appears to have the same size as GFA protein isolated from bovine spinal cord, thus showing that GFA protein does not undergo detectable proteolytic processing.