Glycerol metabolism in the extremely halophilic bacterium Salinibacter ruber

Growth of Salinibacter ruber, a red, extremely halophilic bacterium phylogenetically affiliated with the Flavobacterium/Cytophaga branch of the domain Bacteria, is stimulated by glycerol. In contrast to glucose consumption, which starts only after more easily degradable substrates present in yeast extract have been depleted, glycerol is consumed during the earliest growth phases. When U-(14)C-labeled glycerol was added to the culture, up to 25% of the radioactivity was incorporated by the cells. Glycerol kinase activity was detected only in cells grown in the presence of glycerol (up to 90 nmol mg protein(-1) min(-1)). This enzyme functioned over salt concentrations from 0.6 to 2.8 M KCl. No significant activity of NAD-dependent glycerol dehydrogenase was found. It is suggested that Salinibacter may use glycerol as one of its principal substrates in its habitat, the saltern crystallizer ponds.     

Modelling the combined effect of temperature,pH and aw on the growth rate of Monascus ruber,a heat-resistant fungus isolated from green table olives

AIMS: Growth modes predicting the effect of pH (3.5-5.0), NaCl (2-10%), i.e. aw (0.937-0.970) and temperature (20-40 degrees C) on the colony growth rate of Monascus ruber, a fungus isolated from thermally-processed olives of the Conservolea variety, were developed on a solid culture medium. METHODS AND RESULTS: Fungal growth was measured as colony diameter on a daily basis. The primary predictive model of Baranyi was used to fit the growth data and estimate the maximum specific growth rates. Combined secondary predictive models were developed and comparatively evaluated based on polynomial, Davey, gamma concept and Rosso equations. The data-set was fitted successfully in all models. However, models with biological interpretable parameters (gamma concept and Rosso equation) were highly rated compared with the polynomial equation and Davey model and gave realistic cardinal pHs, temperatures and aw. CONCLUSIONS: The combined effect of temperature, pH and aw on growth responses of M. ruber could be satisfactorily predicted under the current experimental conditions, and the models examined could serve as tools for this purpose. SIGNIFICANCE AND IMPACT OF THE STUDY: The results can be successfully employed by the industry to predict the extent of fungal growth on table olives.     

Variation in the frequency of the echolocation calls of Hipposideros ruber in the Gulf of Guinea: an exploration of the adaptive meaning of the constant frequency value in rhinolophoid CF bats

This study describes variation patterns in the constant frequency (CF) segment of echolocation calls of the bat Hipposideros ruber within and among populations across the region of the Gulf of Guinea. Correlations of variation in CF with variation in body size, body condition, environmental humidity and presence of ecologically similar species are studied in an attempt to identify the forces driving the evolution of CF. We found that bats may adapt the frequency to humidity, and that CF may evolve under interspecific interactions, either of ecological or of social nature. The results support an adaptive value for the high values of CF, and challenge the ‘Allotonic Frequency Hypothesis’. We found correlation between frequency and a body condition index, which may trigger social selection processes in this species sexually dimorphic in CF. Combined social and environmental selection on CF could trigger diversification of bats along ecotones separating habitats with contrasting air humidity.     

Isolation and Identification of a Thermophilic Strain Producing Trehalose Synthase from Geothermal Water in China

A slightly thermophilic strain, CBS-01, producing trehalose synthase (TreS), was isolated from geothermal water in this study. According to the phenotypic characteristics and phylogenetic analysis of the 16s rRNA gene sequence, it was identified as Meiothermus ruber. The trehalose synthase gene of Meiothermus ruber CBS-01 was cloned by polymerase chain reaction and sequenced. The TreS gene consisted of 2,895 nucleotides, which specified a 964-amino-acid protein. This novel TreS catalyzed reversible interconversion of maltose and trehalose.     

Effects of cyclic AMP on development and secondary metabolites of Monascus ruber M-7

Aim: To study effects of cyclic adenosine monophosphate (cAMP) on development and secondary metabolites of Monascus ruber M‐7. Methods and Results: Plate culture, liquid‐state fermentation (LSF) and solid‐state fermentation (SSF) were used to evaluate effects of cAMP on colonial growth, spore formation and polyketide production of Strain M‐7. The results revealed that the variation trends of colonial sizes, numbers of sexual spores and red pigment contents of M‐7 were in a dose‐dependent manner. And generally they increased and decreased with cAMP concentrations in the ranges of low cAMP concentrations and high cAMP concentrations, respectively. But the variation trends of numbers of asexual spores and citrinin production in both LSF and SSF were opposite to those of colonial sizes, sexual sporulation and red pigment. Conclusions: The regulation of cAMP on development and secondary metabolites in Strain M‐7 was in a dose‐dependent pattern. And red pigment might convert to citrinin under changing cAMP concentrations. Significance and Impact of the Study: The effects of cAMP on Strain M‐7 in SSF give a new clue to enhance beneficial polyketides and reduce citrinin produced by M. ruber.     

The endophytic system of mediterranean Cytinus (cytinaceae) developing on five host Cistaceae species

BACKGROUND AND AIMS: One of the most extreme manifestations of parasitism is found in the genus Cytinus, a holoparasite whose vegetative body is reduced to an endophytic system living within its host root. There are two species of Cytinus in the Mediterranean, C. hypocistis and C. ruber, which parasitize various genera of Cistaceae, one of the most characteristic families of the Mediterranean scrublands. The aim of this work is to describe the endophytic systems of C. hypocistis and C. ruber, and their tissue relationships with their host. METHODS: Roots from five different hosts infected with C. hypocistis and C. ruber were harvested, and examined by anatomical techniques under light microscopy to elucidate the characteristics of the endophytic system of Cytinus, and to determine if differences in endophytic systems occur between the two species and in response to different hosts. KEY RESULTS: The endophyte structure is similar in both Cytinus species irrespective of the host species. In the initial stages of the endophyte, rows of parenchymal cells spread through the host pericyclic derivatives and phloem, and begin to generate small nodules in the outermost region of the host xylem. Later the nodules anastomose, and bands of parasitic tissue are formed. The host cambium continues to develop xylem tissue, and consequently the endophyte becomes enclosed within the xylem. The bands of parasitic tissue fuse to form a continuous sheath. This mature endophyte has well-developed vascular system with xylem and phloem, and forms sinkers with transfer cells that grow through the host xylem. CONCLUSIONS: The endophytic system of Cytinus develops in all host root tissues and reaches its most mature stages in the host xylem. It is more complex than previously reported, showing parenchyma, xylem and phloem tissues. This is the first report of well-developed phloem in a holoparasitic endophytic species.     

Biochemical properties of Hsp70 chaperone system from Meiothermus ruber

The guanidine-hydrochloride (Gdn-HCl) and thermally induced unfolding of Hsp70 from Meiothermus ruber (Mru.Hsp70) were analysed using tryptophan fluorescence and 8-anilino-1-naphthalenesulfonic acid (ANS) binding. The ANS binding to Mru.Hsp70 showed both the increase in fluorescence intensity and a shift in emission maximum. Analysis of the unfolding profile of Mru.Hsp70 indicated that Gdn-HCl induced unfolding of Mru.Hsp70 occurred through intermediate species. The tryptophan and ANS fluorescence emission spectra revealed that ATP induced conformational change increased the thermal stability of Mru.Hsp70. The data obtained are similar to those of Escherichia coli DnaK. The ATP-ase activity of chaperones is fundamental for their biological activity. It this paper we demonstrate that, in contrast to Thermus thermophilus, both Mru.Hsp40 and Mru.Hsp22 co-chaperones affect the ATP-ase activity of Mru.Hsp70. The use of truncated Mru.Hsp40 proteins showed that full-length Mru.Hsp40 is required for stimulation of ATP-ase activity of Mru.Hsp70. E. coli GrpE could act as nucleotide exchange factor the in thermophilic Hsp70 ATP hydrolysis reaction. However, the role of E. coli DnaJ in the M. ruber ATP cycle needs further analysis. We selected the new substrate laccA suitable for determination of refolding activity of thermophilic chaperones.     

Ultrastructural study of change from free-nuclear to cellular endosperm in Ipomoea purpurea Roth and Cytinus hypocistis L.

Abstract

The process of cellularization of the endosperm was studied in Ipomoea purpurea Roth and Cytinus hypocistis L. In both the examined species normal cytochinesis, involving the formation of the phragmoplast, characterizes the change from the nuclear to cellular condition. Nevertheless, some ultrastructural aspects of the cell wall initiation seem to indicate that the modality of freely-growing walls cannot be excluded. The hypothesis of a unique method of wall initiation for the endosperm of the nuclear type, formulated by some Authors, is discussed.     

Isolation and characterization of polymorphic microsatellite loci in the scarlet ibis (Eudocimus ruber— Threskiornithidae‐Aves)

Here we presented 10 polymorphic microsatellite loci obtained from scarlet ibis through an enriched genomic library. The analysis of 45 individuals from three Brazilian natural populations showed allelic diversity ranged from three to 17 alleles, observed heterozygosity ranged from 0.03 to 0.92, and expected heterozygosity ranged from 0.06 to 0.92. These highly variable microsatellite loci can provide means for assessing overall genetic variation in its remnant natural populations, which may help the development of effective conservation programs.