Staining of sulphatides in metachromatic leukodystrophy with Alcian blue at high salt concentrations.

Alcian blue combines with purified sulphatide in 1.OM magnesium chloride. In tissue sections from patients with metachromatic leukodystrophy, sulphatide is stained by Alcian blue in 0.8 M magnesium chloride, and the staining can be abolished by prior treatment with chloroform and methanol. The simplicity of the technique, its specificity and ease of interpretation recommend Alcian blue staining at high salt concentrations as a routine method in the diagnosis of metachromatic leukodystrophy.     

Appearance of foci of hematopoiesis and hematopoietic stem cells in the liver of mice following a single administration of cyclophosphane]

The nidi of hemopoiesis appeared in the liver and the lymph nodes of DBA/2, C57BL/6j and F1 (C57BL/6j X CBA) strains of mice of the 6th day after a single intraperitoneal injection of cyclophosphamide in a dose of 200 mg/kg. This process was accompanied by the appearance of stem hemopoietic cells in the liver. Their maximum number was observed on the 6th and the 9th days. On the 12th day their level decreased, but it still exceeded the one in the animals which received a suspension of normal liver cells. In myelosan exhaustion the pool of the bone marrow and splenic stem cells, the subsequent cyclophosphamide injection failed to induce the appearance of the nidi of hemopoiesis and stem cells in the liver.     

Use of transformation for studying the nature of formation of stable bacterial L forms]

The authors obtained a stable variant of the L-forms of Bacillus subtilis capable of exponential growth of the minimal and synthetic medium. An electron-microscopic study of different stages of the L-form formation was carried out by the method of ultra-thin sections. A possibility was shown of the transfer of the L-form formation sign by the method of transformation. DNA isolation from the L-forms by soft lysis considerably facilitated and simplified the genetic analysis of the L-form formation by the transformation method.     

Role of the 2-amino group of deoxyguanosine in sequence recognition by EcoRI restriction and modification enzymes.

The dG residues within the EcoRI recognition sequence of ColE1 DNA have been selectively replaced with dI. Methylation of the altered sequence by the EcoRI modification enzyme is extremely slow as compared with methyl transfer to the natural recognition site. Since the affinity of the modification enzyme for the dI-containing sequence is considerably less than that for the natural sequence, we have concluded that the 2-amino group of dG has an important role in DNA site recognition by this enzyme. In contrast, the altered site is subject to cleavage by EcoRI endonuclease at rates essentially identical with those observed with the natural sequence. These results strongly suggest that the two enzymes utilize different contacts within the EcoRI site and are consisted with our conclusion (Rubin, R. A., and Modrich, P. (1977) J. Biol. Chem. 252, 7265-7272) that the two proteins interact with their common recognition sequence in different ways.     

Metabolic activation and toxicity of a DDT-metabolite, 3-methylsulphonyl-DDE, in the adrenal zona fasciculata in mice

Whole-body autoradiography of 14C-labelled 3-methylsulphonyl-DDE (3-MeSO2-DDE) in female C57BL mice revealed a heavy accumulation in the adrenal cortex. Fairly high radioactivity appeared in the nasal mucosa and fat, while the labelling of the liver was intermediate. The adrenal radioactivity remained largely unextracted in tissue-sections treated with organic solvents. In the liver and intestinal contents the radioactivity was partly extracted, whereas in all other tissues almost completely extracted. According to light microscopic autoradiography, the tissue-bound adrenal radioactivity was confined to the zona fasciculata, leaving the other adrenal zones devoid of bound material. Incubation of 3-MeSO2-DDE with adrenal tissue (300 X g supernatant) revealed a dose- and time-dependent covalent binding to protein and formation of water-soluble metabolites. The cytochrome P-450 inhibitors metyrapone and carbon monoxide inhibited both covalent binding and polar metabolite formation. Addition of reduced glutathione decreased binding, while polar metabolite formation was increased. Histopathological examination of adrenals from 3-MeSO2-DDE-treated mice revealed extensive vacuolation and necrosis of the zona fasciculata 1-12 days after single doses down to 25 mg/kg. Degenerative changes were observed at 12.5 mg/kg. In contrast to 3-MeSO2-DDE, 14C-labelled 3,3'-bis(methylsulphonyl)-DDE was not accumulated in the adrenal cortex. 3-MeSO2-DDE is thus a persistent environmental pollutant with a unique ability to produce acute toxicity subsequent to metabolic activation in a mammalian tissue.     

The effect on grain yield of adult plant resistance to mildew in oats

Lines were selected from progeny of the crosses Maldwyn × Milford and Maldwyn × Sun II which consistently exhibited small and large amounts of mildew in similar situations. These are referred to as ‘low’ and ‘high’ mildew lines respectively. In small plot field trials conducted in 1971, 1972 and 1973 the low mildew lines produced substantially more grain each year compared with the high mildew lines in plots where mildew was allowed to develop normally. In plots which were kept comparatively free from infection by spraying with tridemorph, both low and high mildew lines gave similar yield. When the unsprayed plots were compared with the sprayed plots the low mildew lines invariably showed very small losses in grain yield and the high mildew lines usually very large losses. This same trend was evident also in the parent cultivars in 1972. Maldwyn, with only 7·9% mildew cover in the unsprayed plots due to its resistance, suffered a decrease of only 9·2% in grain yield compared with losses of 17·1 and 20·3% in the more susceptible cultivars Milford and Sun II. Certain lines and cultivars sustained heavy levels of mildew without corresponding loss of grain yield, i.e. showed low sensitivity to the disease. The importance of combining low sensitivity (or tolerance) with adult plant resistance to mildew is discussed.     

Optimization of the medium for the yeast synthesis of biotin

In order to increase the yield of biotin produced by the culture Sporobolomyces pararoseus, the medium containing sucrose, asparagine, MgSO4 (NH4)2SO4, KH2PO4, vitamin complex and trace elements was optimized. With the aid of a fractional factor experiment (2(5-1)) and a complete factor experiment (2(4)), the proportion of constituents was chosen in such a way as to double biotin yield, i.e. to increase it to 55.25 micrograms/l. An enrichment of the medium with yeast autolysate, casein hydrolysate and peptone in the presence of adenine increased biotin yield to 105.7 micrograms/l and cell productivity from 6.1 to 8.0 micrograms/l dry biomass.