Ultrastructural localization of the high molecular weight proteins associated with in vitro-assembled brain microtubules

Microtubules isolated from brain extracts by in vitro assembly (1, 19, 23) are composed principally of two tubulins and two high molecular weight proteins (microtubule-associated proteins [MAPS] 1 and 2) (2,5,7,20). Recently, it was demonstrated that in vitro-assembled brain microtubules (neurotubules) are coated with filaments (5, 7) which are similar to the filaments attached to neurotubules in situ (4, 15, 21, 24, 25), and it was suggested that the filaments are composed of the higher molecular weight MAPs (5, 7, 12). In this study, microtubules were assembled in the presence and absence of the MAPs, and thin sections of the microtubules were examined by electron microscopy. The results show that the filaments only occur on microtubules assembled in the presence of the MAPs and it is therefore concluded that the filaments are composed of the high molecular weight MAP's.     

Magnetic Resonance of Isotope Hybrid Flavoprotein <Superscript>2</Superscript>H-Flavoprotein (<Superscript>1</Superscript>-Flavin Mononucleotide)

FLAVOPROTEINS lend themselves particularly well to study by the combined techniques of magnetic resonance and isotope substitution^1–3. Recent electron spin resonance (ESR) and electron-nuclear double resonance (ENDOR) investigations have already indicated the utility of this approach to the study of the structure and function of flavin and flavoproteins^4–8. We have now prepared an unusual isotope hybrid flavoprotein that gives promise of great value for magnetic resonance studies. This substance is obtained by the introduction (by exchange) of an ¹H-flavin mononucleotide (¹H-FMN) prosthetic group into (fully deuterated) ²H-flavoprotein that can be isolated from the blue-green thermophilic alga Synechococcus lividus. This isotope hybrid protein makes it possible to apply in a unique way proton magnetic resonance (PMR) and ESR to the chemistry of protein-bound FMN.     

OBSERVATIONS ON THE CONTROL OF MITE INFESTATIONS IN STORED WHEAT BY CHEYLETUS SPP. (ACARINA, CHEYLETIDAE)

An account is given of the control of the grain mite Acarus siro L. (= Tyroglyphus farinae L.) by the predatory mite Cheyletus sp. in imported wheat stored in bags or in bulk. After 12–18 months of storage Cheyletus sp. had developed in 75% of the parcels of wheat and in 67% of these it became dominant over other mites. This usually occurred in late summer for bagged wheat. Control of A. siro by Cheyletus sp. compared favourably with that achieved by fumigation with methyl bromide and on occasion was superior. Both development and dominance of Cheyletus sp. were adversely affected by earlier fumigation but there was some evidence that spraying wheat with γ-BHC favoured the development of this species and, in some circumstances, its dominance. Dominance by Cheyletus sp. in bulk grain often occurred in the winter months when the surface moisture content of the wheat was at its highest.
The development of Cheyletus eruditus Schr. is described in a bulk grain store where dense populations of A. siro and Glycyphagus destructor Schr. were eliminated by the predator. The numbers of C. eruditus in wheat tended to increase faster when the surface layers were disturbed than when the grain was undisturbed. Nevertheless, dominance over the other mites tended to occur first in undisturbed grain.     

Interet diagnostique d’une injection intracaverneuse de 20 μg de Prostaglandine E1 dans l’impuissance

Intracavernous injection of 20 μg of prostaglandin E1 (PGE1) was carried out in 130 impotent patients. The erectile response was compared to the results of arteriological investigations including nocturnal penile tumescence and rigidity monitoring (NPTR) in 59 patients. The response of 60 patients positively categorized as exclusively psychogenic or vasculogenic was also compared to the pattern of the response to 80 mg of papaverine observed in a previous study by the same authors. The PGE1 test may not discriminate psychogenic from wholly organic patients since its results are not correlated to those of NPTR. It helps for the screening of vasculogenic impotence. Lack of response or a partly rigid response is consistent with this actiology but is not specific for it. A fully response makes it unlikely. Compared to papaverine, PGE1 induces less non rigid responses in psychogenic patients (15% versus 35% with papaverine) and more fully rigid responses in vasculogenic patients (respectively 12% and 5 %). Consequently the specificity of the PGE1 test is higher but its sensitivity lower than that of papaverine so that there is no clear difference in the effectiveness of the tests. Nevertheless the PGE1 test should be preferred, because it is safer. Prolonged erections occured in only 5 patients, and all ceased spontaneously. However 4 presented severely painful erections.     

Flowering of contrasting white clover varieties in relation to daylength in controlled environments and in the field

The effect of 12 , 14 and 16 h photoperiods, given consecutively, on flower production in 10 varieties of white clover (Trifolium repens) in controlled environments, is described. The effect of natural daylengths from September to July on the same plants in the field was also studied in the following year. Relationships between morphological and physiological traits and flowering were examined. In controlled environments most plants flowered under the longest days, three times as many in the 16 h daylength as in the 12 h. Larger leaved types had a higher proportion of reproductive plants than did smaller leaved types. Floral initiation was not observed in the field until daylengths were in excess of 15 h. Increasing daylength increased flower production, floret and ovule numbers but did not appear to increase nectar production significantly.