Stress- and Growth Phase-Associated Proteins of Clostridium acetobutylicum

The response of Clostridium acetobutylicum ATCC 4259 to the stresses produced by a temperature upshift from 28°C to 45°C and by exposure of the organisms to 0.1% n-butanol or to air was examined by analysis of pulse-labeled proteins. The stress response was the induction of the synthesis of a number of proteins, some of which were elicited by the three forms of stress. Eleven heat shock proteins were identified by two-dimensional electrophoresis, as were two proteins whose synthesis was heat sensitive. In the absence of applied stress, the synthesis of four proteins was found to be associated with the growth phase in batch culture; three of these proteins had a higher rate of de novo synthesis when the cells entered the solvent production phase. One of the stress-induced proteins, hsp74, was partially purified an found to be immunologically related to Escherichia coli heat shock protein Dnak. The similarities of the proteins induced at the onset of solventogenesis and by stress suggest a relationship between the two processes.     

Some factors affecting root formation onin vitro regenerated pea shoots

The rooting ability of 2 cm long shoots ofPisum sativum L., derived from differentin vitro shoot-tip cultures in two pea cultivars Bohatýr and Kleine Rheinländerin was evaluated. In three mutually independent experiments the full and half-strength Murashige-Skoog medium (containing full or half concentration of macro and microelements), with sucrose concentrations 10–30 g l-¹, and with various NAA and IAA combinations, was tested. The variant with half concentration of macro- and microelements, supplemented with 30 g l¹ sucrose, and with growth regulators in the quantity of 1 μM proved optimum.     

Determination of ribonuclease activity in coloured extracts of citrus leaves

A rapid method is presented for the determination of ribonuclease activity in coloured extracts from citrus leaves. At the same time, the influence exercised by several precipitating reagents and the storage time at 4 °c on the activity of the enzymatic system are studied. In addition the enzyme stability against heat is studied.     

Identification of host range determinants in the Rhizobium species MPIK3030

Summary R. meliloti primarily nodulates Medicago sativa but cannot nodulate Macroptilium atropurpureum. By introducing an 11.4 kb region into R. meliloti from the Symplasmid of Rhizobium strain MPIK3030, the host range of the R. meliloti transconjugants were shown to be extended to M. atropurpureum, one of the hosts of MPIK3030 but not normally nodulated by R. meliloti. The region responsible for host range extension was isolated by mass conjugating a clone bank from MPIK3030 into the R. meliloti wild type, and subsequent screening for nodulation on M. atropurpureum. Using deleted derivatives of a plasmid reisolated from endosymbiotic bacteria, the host range region was further narrowed down to three EcoRI fragments. Tn5 mutagenesis allowed the isolation of three discrete regions on an 11.4 kb section, which are involved in the extension of host range to M. atropurpureum. Finally, complementation experiments performed with R. meliloti common nod and hsn mutants indicated that none of the genes involved in the early steps of nodulation, including host-range functions, can be complemented by genes carried on the 11.4 kb fragment derived from MPIK3030.     

Effect of Insulin-Induced Hypoglycemia on the Concentrations of Glutamate and Related Amino Acids and Energy Metabolites in the Intact and Decorticated Rat Neostriatum

Abstract The glutamate (Glu) terminals in rat neostriatum were removed by a unilateral frontal decortication. One to two weeks later the effects of insulin-induced hypoglycemia on the steady-state levels of amino acids [Glu, glutamine (Gin), aspartate (Asp), γ-aminobutyric acid (GABA), tau-rine] and energy metabolites (glucose, glycogen, α-ketoglu-tarate, pyruvate, lactate, ATP, ADP, AMP, phosphocre-atine) were examined in the intact and decorticated neostriatum from brains frozen in situ. The changes in the metabolite levels were examined during normoglycemia, hypoglycemia with burst-suppression (BS) EEG, after 5 and 30 min of hypoglycemic coma with isoelectric EEG, and 1 h of recovery following 30 min of isoelectric EEG. In normoglycemia Glu decreased and Gin and glycogen increased significantly on the decorticated side. During the BS period no significant differences in the measured compounds were noted between the two sides. After 5 min of isoelectric EEG Glu, Gin, GABA, and ATP levels were significantly lower and Asp higher on the intact than on the decorticated side. No differences between the two sides were found after 30 min of isoelectric EEG. After 1 h of recovery from 30 min of isoelectric EEG Glu, Gin, and glycogen had not reached their control levels. Glu was significantly lower, and Gin and glycogen higher on the decorticated side. The Asp and GABA levels were not significantly different from control levels. The results indicate that the turnover of Glu is higher in the intact than in decorticated neostriatum during profound hypoglycemia.     

Collagenous substrata regulate the nature and distribution of glycosaminoglycans produced by differentiated cultures of mouse mammary epithelial cells

We have investigated the influence of culture substrata upon glycosaminoglycans produced in primary cultures of mouse mammary epithelial cells isolated from the glands of late pregnant mice. Three substrata have been used for experiments: tissue culture plastic, collagen (type I) gels attached to culture dishes, and collagen (type I) gels that have been floated in the culture medium after cell attachment. These latter gels contract significantly. Cells cultured on all three substrata produce hyaluronic acid, heparan sulfate, chondroitin sulfates and dermatan sulfate but the relative quantities accumulated and their distribution among cellular and extracellular compartments differ according to the nature of the culture substratum. Notably most of the glycosaminoglycans accumulated by cells on plastic are secreted into the culture medium, while cells on floating gels incorporate almost all their glycosaminoglycans into an extracellular matrix fraction. Cells on attached collagen gels secrete approx. 30% of their glycosaminoglycans and assemble most of the remainder into an extracellular matrix. Hyaluronic acid is produced in significant quantities by cells on plastic and attached gels but in relatively reduced quantity by cells on floating gels. In contrast, iduronyl-rich dermatan sulfate is accumulated by cells on floating gels, where it is primarily associated with the extracellular matrix fraction, but is proportionally reduced in cells on plastic and attached gels. The results are discussed in terms of polarized assembly of a morphologically distinct basal lamina, a process that occurs primarily when cells are on floating gels. In addition, as these cultures secrete certain milk proteins only when cultured on floating gels, we discuss the possibility that cell synthesized glycosaminoglycans and proteoglycans may play a role in the maintenance of a differentiated phenotype.     

Late enzymes of vindoline biosynthesis

From differentiated plants of Catharanthus roseus (L.) G. Don we have isolated a specific enzyme of the vindoline biosynthetic pathway catalysing the S-adenosylmethionine-dependent methylation of 11-O-demethyl-17-O-deacetyl-vindoline. The enzyme we named S-adenosyl-L-methionine : 11-O-demethyl-17-O-deacetylvindoline 11-O-methyltransferase. This transferase exhibits a high substrate specificity. Obviously the O-methylation at C-11 precedes the O-acetylation at the C-17 position during the biosynthesis of vindoline.A second enzyme was detected which hydrolyses the acetyl function of vindoline. The distribution of this acetylesterase in C. roseus plants demonstrates that the enzyme is not specifically associated with the vindoline distribution in the plant material. Most probably this enzyme plays no essential role in the biosynthesis of vindoline.     

Phytosociological characteristics of theRondeletio correifoliae-Andropogonetum multinervosi ass. nova (Sierra de la Siguanea,Isla de la Juventud,Cuba)

The contribution deals with the phytocenological analysis of theRondeletio correifoliae-Andropogonetum multinervosi, an endemic savanna association occuring on the Siguanea Hills (Sierra de la Siguanea) near the Colony Hotel.     

The Electrical Conductivity of Bovine Milk in Mastitis Diagnosis

The electrical conductivity (EC) of milk is mainly a function of the electrolyte concentration in the milk and therefore raised in mastitis. The present investigation was aimed at elaborating, if possible, a diagnostic model for screening purposes based on EC determinations and consistent with the diagnostic procedures and interpretations commonly used in laboratory milk diagnosis in the Nordic countries (Klastrup 1975). According to this diagnosis (here called reference diagnosis) cell numbers above 300,000/ml (cell count or the corresponding CMT-score) in foremilk quarter samples during the main part of the lactation period and significantly above the lowest value on within-udder comparison during late lactation are considered indicative of mastitis and bacteriological examinations are made when called for.