Asymmetric template function of microbial deoxyribonucleic acids: transcription of ribosomal and soluble ribonucleic acids

In Bacillus subtilis and Escherichia coli, 16 and 23S ribosomal ribonucleic acid (rRNA) hybridize exclusively with the heavy (H) strand of methylated albuminkieselguhr (MAK)-fractionated complementary deoxyribonucleic acid (DNA) strands. All the soluble RNA (4S RNA) in B. subtilis and 66 to 75% of the 4S RNA in E. coli also hybridize with the H strand. Interspecific hybridization shows that E. coli 23S rRNA also binds selectively to the DNA H strand of Salmonella typhimurium. The hybridization peak for all three cellular RNA components is specifically located in the late-eluting region of the absorbance profile of the DNA H strand. The early-eluting region of the light (L) strand preferentially inhibits the hybridization between the peak region of the H strand and 23S rRNA. These regions are considered to represent the transcribing sequences and their complements for 23S rRNA in the separated H and L strands of DNA, respectively.     

Effect of different conditions of light on the nucleic acid fractions in cotyledons ofChenopodium rubrutn L.

The nucleic acid fractions in cotyledons of young Chenopodium rubrum plants exposed to continuous light, continuous darkness and short (8 h) day, respectively and labelled with³²P 24 h prior to harvesting were studied by means of chromatography on MAK columns. Some parameters of cotyledon growth (dry weight, cotyledon area, occurrence of mitoses) were also investigated. The changes in the nucleic acid fractions agreed with the dynamics of cotyledon growth. In continuous light the content of all fractions increased. The radioactivity of DNA and s-RNA did not undergo any great changes and only r-RNA increased. The specific activity of r-RNA increased slightly, that of soluble RNA and DNA was reduced. In continuous darkness the content of all the fractions did not undergo any great changes. The radioactivity as well as the specific activity of all fractions decreased. In short day the content of the nucleic acid fractions did not change conspicuously. Only the specific activity of s-RNA increased in a noticeable way while the radioactivity of r-RNA and the specific activity of DNA decreased and this of r-RNA did not change. The changes in nucleic acid metabolism were partially connected with changes in³²P uptake which depended upon light conditions but they were not merely a consequence of this fact. Obviously, there also exists a more direct relationship between nucleic acid synthesis and growth.     

INCORPORATION OF PHOSPHATE INTO RAT BRAIN DURING SLEEP AND WAKEFULNESS

Abstract— Labelled inorganic phosphate (³²P₁) was administered intraventricularly to unrestrained sleeping and waking adult rats. After about 20 min of sleep or a comparable period of wakefulness, as monitored by EEG and EMG, the animals were frozen in liquid nitrogen and the brains were analysed. One group of animals (A) was not previously acclimatized to the apparatus. A second group (B) was acclimatized. The specific radioactivity of a phosphoprotein fraction was elevated during sleep in group A but not in group B. The specific radioactivity of the phosphatides of group B was depressed in sleeping as compared with waking animals. This effect was not observed in group A. No significant difference was detected between the EEG patterns of sleeping animals in groups A and B, as evaluated by standard criteria. These observations suggest that the physiological conditions attributable to environmental, emotional or other determinants can influence shifts in brain metabolism during the sleep-wakefulness cycle.     

The Arabidopsis heavy metal P-type ATPase HMA5 interacts with metallochaperones and functions in copper detoxification of roots

Since copper (Cu) is essential in key physiological oxidation reactions, organisms have developed strategies for handling Cu while avoiding its potentially toxic effects. Among the tools that have evolved to cope with Cu is a network of Cu homeostasis factors such as Cu-transporting P-type ATPases that play a key role in transmembrane Cu transport. In this work we present the functional characterization of an Arabidopsis Cu-transporting P-type ATPase, denoted heavy metal ATPase 5 (HMA5), and its interaction with Arabidopsis metallochaperones. HMA5 is primarily expressed in roots, and is strongly and specifically induced by Cu in whole plants. We have identified and characterized plants carrying two independent T-DNA insertion alleles, hma5-1 and hma5-2. Both mutants are hypersensitive to Cu but not to other metals such as iron, zinc or cadmium. Interestingly, root tips from Cu-treated hma5 mutants exhibit a wave-like phenotype at early stages and later on main root growth completely arrests whereas lateral roots emerge near the crown. Accordingly, these lines accumulate Cu in roots to a greater extent than wild-type plants under Cu excess. Finally, yeast two-hybrid experiments demonstrate that the metal-binding domains of HMA5 interact with Arabidopsis ATX1-like Cu chaperones, and suggest a regulatory role for the plant-specific domain of the CCH Cu chaperone. Based on these findings, we propose a role for HMA5 in Cu compartmentalization and detoxification.     

How can leadership processes in European bison be used to improve the management of free-roaming herds

For several years, several wild species are experiencing a comeback in Europe, especially large herbivores. Despite the good news, the increased number of wild herbivores also potentially increases human-wildlife conflicts due to crop damages and road traffic accidents where such species have been involved in previously. In this context, studying the movements of animal groups is particularly relevant for managing their use of space and ensure sufficient cohabitation with human populations. We thus studied the European bison (Bison bonasus), a species concerned in several rewilding programs, to understand to what extent individual characteristics and social relationships are involved in the leadership process and how these factors influence the success of group movements. We observed a herd of 14 individuals in Zuid-Kennemerland National Park (the Netherlands) and analysed the initiation phase of spontaneous group movements. We showed that leadership was distributed throughout the group but the two oldest females showed higher propensity to initiate and to be followed. They seemed to have a high social power and a strong capacity to federate probably due to their dominance rank and their knowledge of the areas. The joining process was faster when animals were grouped before departure and when the initiator moved in the direction towards which the majority of individuals was oriented. Individuals joined the movement according to a selective mimetic process, based on kinship. These results, combined with virtual fence device, could be used to manage herd movements in a given territory and thus, might be an innovative tool to decrease human-wildlife conflicts.     

Involvement of propeptides in formation of catalytically active metalloproteinase from Thermoactinomyces sp

The metalloproteinase from Thermoactinomyces sp. 27a (Mpr) represents secretory thermolysin-like metalloproteinases of the M4 family. The Thermoactinomyces enzyme is synthesized as a precursor consisting of a signal peptide, N-terminal propeptide, mature region, and C-terminal propeptide. The functional molecule lacks the signal peptide, N-terminal propeptide, and C-terminal propeptide, which indicates the processing of these regions. Until now, it remained unclear if the N-terminal propeptide is involved in the formation and functioning of Mpr, and the role of the C-terminal propeptide was also unclear. In this work, a Bacillus subtilis AJ73 strain expressing Mpr without the C-terminal propeptide- encoding region being involved has been obtained. The absence of the Mpr C-terminal propeptide had no significant effect on the formation of the functional molecule and did not interfere with the protease secretion in B. subtilis AJ73 cells. Strains producing the N-terminal propeptide, mature region, and mature region covalently bound to the N-terminal propeptide were generated from Escherichia coli BL-21(DE3) cells. Functionally active Mpr forms could be produced only in the presence of the N-terminal propeptide, either covalently bound to the mature region (in cis) or as a separate molecule (in trans). Thus, the Mpr three-dimensional structure is formed according to the propeptide-assisted mechanism with no requirement of a covalent bond between the N-terminal propeptide and mature region. Moreover, Mpr variants generated in cis and in trans differed in their specificity for certain synthetic substrates.     

Breathe in and straighten your back: hypoxia, notch, and scoliosis

In this issue of Cell, Sparrow et?al. propose a new mechanism for sporadically occurring congenital scoliosis in which Notch signaling and hypoxia converge in the embryo on somite patterning via the segmentation clock. This interaction between hypoxia and a predisposed genetic background might underlie other birth defects with incomplete penetrance.     

Induction of a polyubiquitin gene promoter by dehydration stresses in transformed rice cells

The expression of the maize polyubiquitin gene promoter UBI1 in rice cells has been used to study the involvement of ubiquitin in cell protection responses to dehydration caused by osmotic, saline or freezing stress. The effect of these stresses on UBI1 activity was investigated by the use of stably transformed rice calli (UBI1:GUS), as well as by transient expression experiments performed with cell lines with high or low tolerance to each type of stress. The theoretical analysis of the UBI1 promoter shows several putative stress-regulated boxes that could account for the stress-related UBI1 induction pattern described in this work. We suggest that the study of the differential UBI1 promoter-driven expression in rice cell lines with different level of tolerance to stress might be useful to elucidate complex signal transduction pathways in response to dehydration stresses in monocots.