Time resolved spectroscopy of the tryptophyl fluorescence of the E. coli LAC repressor.

A new crystal form of a mitogenic lectin from pea seeds ($\text{Pisum sativum}$) has been obtained which is suitable for high resolution structural work. The crystals are orthorhombic, space group P2₁2₁2₁, with unit cell dimensions: $\text{a}$ = 64.2Å, $\text{b}$ = 72. 7Å, $\text{c}$ = 108. 3Å. The asymmetric unit contains one protein molecule.     

Cellular thorn-like projections in human endocervical epithelium. Preliminary scanning electron-microscopic study.

By means of scanning electron-microscopic investigations, thorn-like projections (TLP) were observed in the cilio-secretory epithelium of the ventral surface of the human endocervix. These projections, which seem to be characteristic of a new cell type, were seen at different stages of the menstrual cycle (days 8, 14 and 21) in 4 apparently healthy fertile women. Striking differences in length, with a maximum size at midcycle, suggest an evolutive process throughout the menstrual cycle. The origin and possible physiological role of TLP in the reproductive process are discussed.     

Ultrastructural changes in adrenergic neurons following chemical sympathectomy

The paper describes the ultrastructural changes of the sympathetic neurons following guanethidine administration in mice. The main characteristics changes, after prolonged administration (1-10 weeks) of guanethidine (Ismelin, Ciba-Geigy, Basel, Switzerland) at doses of 30-50 mg/kg/day i.p. and i.m. were: (1) Mitochondrial damages: swelling and deformation of the mitochondria, with disruption and dispersion of the cristae and condensation or dissolution of the matrix. Membranolysis of the outer and inner mitochondrial membranes. (2) Neural processes: swelling and disorganization of the internal architecture in the postganglionic axonal and dendritic synaptic varicosities. (3) Adrenergic vesicles: disappearance of the granular vesicles in the early stage of the experiment, increase of the coated vesicles in the later stage of treatment. The effect of guanethidine is specific for the postganglionic adrenergic neurons, but the observed destruction is not caused solely by guanethidine; other chemical substances induce the same or similar degeneration in the sympathetic ganglion.     

An altered heart-labile enterotoxin (LT') produced by Escherichia coli serogroup O55 strain.

An Escherichia coli serogroup O55 strain produced heat-labile enterotoxin only, which exerted unusual effects on cell cultures; it caused elongation of CHO and HeLa cells but no changes in Y-1 cells. Injection of this substance, designated LT', into mouse foot pad and rabbit skin caused a well-expressed necrotic effect beside the LT-like activity. LT' showed no cytotoxic effect and failed to produce mouse lung oedema. The strain was not haemolytic. According to Sephadex G-100 fractionation, the LT' had a high molecular weight. The LT' and the necrotic activities could not be separated by fractionation. Neutralization experiments suggested an antigenic relationship between LT and LT'. The antigenic deficiency of LT' was closely related to the common antigenic component of LT and choleragen. The necrotic effect caused by crude LT' was neutralized only by the homologous serum.     

Effects of nitrogen deficiency and light of high intensity onCryptomonas rufescens (Cryptophyceae)

Summary C.rufescens excystment, experimentally induced, corresponds to a general metabolism recovery of the cell, previously in a resting phase. The cytoplasm changes without any polarity, and organelles like gullet and flagella redifferentiate. The thylakoids develop mainly from the stored lipidic compounds which then disappear. Phycoerythrin immediately fills the intrathylakoidal lumen. Pigment synthesis seems closely associated with the development of membranes. The activated cell divides and the cyst wall breaks down. The destruction of the wall begins in the median layer and is followed by a mechanical rupture of the external and internal layers. Each germinative cyst releases two or four fully differentiated cells. There is an exact symmetry between excystment and encystment, all the transformations of theC. rufescens cell being reversible.     

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.     

Effect of a tryptophan lead on the swine adrenal cortex reactivity and behavioral response to stress]

Behaviour and plasma corticosteroid levels were investigated in pigs preloaded with 50 to 200 mg/kg 1-tryptophan. The treatment did not influence reactions to frustation and had no effect on continuous avoidance responding. However the adrenal response to the stress of new environment concomitant with delivery of unavoidable shocks was decreased (fig. 1), as well as the behavioural response to a fear signal superimposed on a continuous avoidance paradigm (fig. 2). These results point out relatively specific psychotropic effects of a tryptophan load in pigs.