Process development of itaconic acid production by a natural wild type strain of <Emphasis Type="Italic">Aspergillus terreus</Emphasis> to reach industrially relevant final titers

Itaconic acid is a promising organic acid and is commercially produced by submerged fermentation of Aspergillus terreus. The cultivation process of the sensitive filamentous fungus has been studied intensively since 1932, with respect to fermentation media components, oxygen supply, shearing rate, pH value, or culture method. Whereas increased final titers were achieved over the years, the productivity has so far remained quite low. In this study, the impact of the pH on the itaconic acid production was investigated in detail. The pH during the growth and production phase had a significant influence on the final itaconic acid concentration and pellet diameter. The highest itaconic acid concentration of 160 g/L was achieved at a 1.5-L scale within 6.7 days by raising and controlling the pH value to pH 3.4 in the production phase. An ammonia solution and an increased phosphate concentration were used with an itaconic acid yield of 0.46 (w/w) and an overall productivity of 0.99 g/L/h in a fed-batch mode. A cultivation with a lower phosphate concentration resulted in an equal final concentration with an increased yield of 0.58 (w/w) after 11.8 days and an overall productivity of 0.57 g/L/h. This optimized process was successfully transferred from a 1.5-L scale to a 15-L scale. After 9.7 days, comparable pellet morphology and a final concentration of 150 g/L itaconic acid was reached. This paper provides a process strategy to yield a final titer of itaconic acid from a wild-type strain of A. terreus which is in the same range as the well-known citric acid production.     

CFTR mutations in Turkish and North African cystic fibrosis patients in Europe: implications for screening

AIMS: To obtain more insight into the variability of the CFTR mutations found in immigrant cystic fibrosis (CF) patients who are living in Europe now, and to estimate the test sensitivity of different frequently used methods of DNA analysis to detect CF carriers or patients among these Turkish or North African immigrants. METHODS: A survey among 373 European CF centers asking which CFTR mutations had been found in Turkish and North African CF patients. RESULTS: 31 and 26 different mutations were reported in Turkish and North African patients, identifying 64.2% (113/176) and 87.4% (118/135) alleles, respectively (p < 0.001). The mean sensitivity (detection rate) of three most common CFTR mutation panels to detect these mutations differed between Turkish and North African people, 44.9% (79/176) versus 69.6% (94/135) (p < 0.001), and can be increased to 57.4% (101/176) and 79.3% (107/135) (p < 0.001), respectively, by expanding these panels with 13 mutations which have been found on two or more alleles. CONCLUSION: 35.8% and 12.6%, respectively, of CF alleles in Turkish and North African patients living in Europe now had not been identified. Among these populations, the test sensitivity of common CFTR mutation panels is insufficient for use in screening programs in Europe, even after expansion with frequent Turkish and North African mutations. This raises questions about whether and how to implement CF carrier and neonatal screening in a multiethnic society.     

Metabolic syndrome in children and adolescents--risk for sleep-disordered breathing and obstructive sleep-apnoea syndrome?

The clinical relevance of the term "metabolic syndrome", the definition criteria, and predictive power are being disputed. Inclusion of sleep-disordered breathing and sleep apnoea into a definition of metabolic syndrome is also controversial once children and/or adolescents are affected. Nevertheless, along with the increasing prevalence of childhood obesity, the prevalence of the metabolic syndrome in obese children is reported at 30%, irrespective of the definition applied. Moreover, childhood obesity is associated with sleep-disordered breathing. Adipocytokines, cytokines secreted from adipose tissue, are thought to play a major role in the pathophysiology of metabolic syndrome. Leptin was initially suggested as a promising "anti-obesity" hormone. New concepts indicate that in humans leptin and its soluble receptor may be more important in states of energy deficiency rather than a predictor of the metabolic syndrome. Adiponectin, on the other hand, is not only related to obesity and insulin resistance, but appears to be the strongest predictor for metabolic syndrome, even in children. In newborns and infants, both adipocytokines occur in high concentrations, even though this cannot completely explain the increased risk for ensuing metabolic disease later in life. Finally, low-grade systemic inflammation may underlie the clustering of metabolic risk factors. Overall factors from the adipose tissue may constitute not only markers but also mediators of metabolic sequelae of obesity.     

Endosymbioses between bacteria and deep-sea siboglinid tubeworms from an Arctic Cold Seep (Haakon Mosby Mud Volcano, Barents Sea)

Siboglinid tubeworms do not have a mouth or gut and live in obligate associations with bacterial endosymbionts. Little is currently known about the phylogeny of frenulate and moniliferan siboglinids and their symbionts. In this study, we investigated the symbioses of two co-occurring siboglinid species from a methane emitting mud volcano in the Arctic Ocean (Haakon Mosby Mud Volcano, HMMV): Oligobrachia haakonmosbiensis (Frenulata) and Sclerolinum contortum (Monilifera). Comparative sequence analysis of the host-specific 18S and the symbiont-specific 16S rRNA genes of S. contortum showed that the close phylogenetic relationship of this host to vestimentiferan siboglinids was mirrored in the close relationship of its symbionts to the sulfur-oxidizing gammaproteobacterial symbionts of vestimentiferans. A similar congruence between host and symbiont phylogeny was observed in O. haakonmosbiensis: both this host and its symbionts were most closely related to the frenulate siboglinid O. mashikoi and its gammaproteobacterial symbiont. The symbiont sequences from O. haakonmosbiensis and O. mashikoi formed a clade unaffiliated with known methane- or sulfur-oxidizing bacteria. Fluorescence in situ hybridization indicated that the dominant bacterial phylotypes originated from endosymbionts residing inside the host trophosome. In both S. contortum and O. haakonmosbiensis, characteristic genes for autotrophy (cbbLM) and sulfur oxidation (aprA) were present, while genes diagnostic for methanotrophy were not detected. The molecular data suggest that both HMMV tubeworm species harbour chemoautotrophic sulfur-oxidizing symbionts. In S. contortum, average stable carbon isotope values of fatty acids and cholesterol of -43 per thousand were highly negative for a sulfur oxidizing symbiosis, but can be explained by a (13)C-depleted CO(2) source at HMMV. In O. haakonmosbiensis, stable carbon isotope values of fatty acids and cholesterol of -70 per thousand are difficult to reconcile with our current knowledge of isotope signatures for chemoautotrophic processes.     

On the relationship between methane production and oxidation by anaerobic methanotrophic communities from cold seeps of the Gulf of Mexico

The anaerobic oxidation of methane (AOM) in the marine subsurface is a significant sink for methane in the environment, yet our understanding of its regulation and dynamics is still incomplete. Relatively few groups of microorganisms consume methane in subsurface environments – namely the anaerobic methanotrophic archaea (ANME clades 1, 2 and 3), which are phylogenetically related to methanogenic archaea. Anaerobic oxidation of methane presumably proceeds via a 'reversed' methanogenic pathway. The ANME are generally associated with sulfate-reducing bacteria (SRB) and sulfate is the only documented final electron acceptor for AOM in marine sediments. Our comparative study explored the coupling of AOM with sulfate reduction (SR) and methane generation (MOG) in microbial communities from Gulf of Mexico cold seep sediments that were naturally enriched with methane and other hydrocarbons. These sediments harbour a variety of ANME clades and SRB. Following enrichment under an atmosphere of methane, AOM fuelled 50–100% of SR, even in sediment slurries containing petroleum-associated hydrocarbons and organic matter. In the presence of methane and sulfate, the investigated microbial communities produce methane at a small fraction (∼10%) of the AOM rate. Anaerobic oxidation of methane, MOG and SR rates decreased significantly with decreasing concentration of methane, and in the presence of the SR inhibitor molybdate, but reacted differently to the MOG inhibitor 2-bromoethanesulfonate (BES). The addition of acetate, a possible breakdown product of petroleum in situ and a potential intermediate in AOM/SR syntrophy, did not suppress AOM activity; rather acetate stimulated microbial activity in oily sediment slurries.     

Implication of HMGR in homeostasis of sequestered and de novo produced precursors of the iridoid biosynthesis in leaf beetle larvae

Insects employ iridoids to deter predatory attacks. Larvae of some Chrysomelina species are capable to produce those cyclopentanoid monoterpenes de novo. The iridoid biosynthesis proceeds via the mevalonate pathway to geranyl diphospate (GDP) subsequently converted into 8-hydroxygeraniol-8-O-beta-D-glucoside followed by the transformation into the defensive compounds. We tested whether the glucoside, its aglycon or geraniol has an impact on the activity of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), the key regulatory enzyme of the mevalonate pathway and also the iridoid biosynthesis. To address the inhibition site of the enzyme, initially a complete cDNA encoding full length HMGR was cloned from Phaedon cochleariae. Its catalytic portion was then heterologously expressed in Escherichia coli. Purification and characterization of the recombinant protein revealed attenuated activity in enzyme assays by 8-hydroxygeraniol whereas no effect has been observed by addition of the glucoside or geraniol. Thus, the catalytic domain is the target for the inhibitor. Homology modeling of the catalytic domain and docking experiments demonstrated binding of 8-hydroxygeraniol to the active site and indicated a competitive inhibition mechanism. Iridoid producing larvae are potentially able to sequester glucosidically bound 8-hydroxygeraniol whose cleavage of the sugar moiety results in 8-hydroxygeraniol. Therefore, HMGR may represent a regulator in maintenance of homeostasis between de novo produced and sequestered intermediates of iridoid metabolism. Furthermore, we demonstrated that HMGR activity is not only diminished in iridoid producers but most likely prevalent within the Chrysomelina subtribe and also within the insecta.     

The human formin FHOD1 contains a bipartite structure of FH3 and GTPase-binding domains required for activation

Formins induce the nucleation and polymerization of unbranched actin filaments. They share three homology domains required for profilin binding, actin polymerization, and regulation. Diaphanous-related formins (DRFs) are activated by GTPases of the Rho/Rac family, whose interaction with the N-terminal formin domain is thought to displace a C-terminal Diaphanous-autoregulatory domain (DAD). We have determined the structure of the N-terminal domains of FHOD1 consisting of a GTPase-binding domain (GBD) and the DAD-recognition domain FH3. In contrast to the formin mDia1, the FHOD1-GBD reveals a ubiquitin superfold as found similarly in c-Raf1 or PI3 kinase. This GBD is recruited by Rac and Ras GTPases in cells and plays an essential role for FHOD1-mediated actin remodeling. The FHOD1-FH3 domain is composed of five armadillo repeats, similarly to other formins. Mutation of one residue in the predicted DAD-interaction surface efficiently activates FHOD1 in cells. These results demonstrate that DRFs have evolved different molecular solutions to govern their autoregulation and GTPase specificity.     

Structure and function of Rho-type molecular switches in plants.

Molecular switches of the Rho family, in concert with their associated regulators and effectors are well known as important control elements of vital signaling pathways in eucaryotic organisms. Yet, this knowledge has so far been established mainly from animal and fungal studies. However, during the recent years, the Rho switch has gone increasingly green as well, and it turned out that the homologous system in plants holds some distinctive features regarding structures, functions and molecular mechanisms for signal transduction. In this review, we give an overview about the structural characteristics of the Rho proteins of plants, termed ROP, highlighting some exciting differences to their animal and fungal counterparts. We further address the unique regulators and effectors of the ROPs and discuss the structural basis for the function and interaction of those proteins in ROP controlled reaction cascades. We finally intend to stimulate the demand for future three-dimensional structures that advance our understanding of the ROP switch in plants.     

Daytime birth of a baby crested black macaque (Macaca nigra) in the wild

In mammals, which give birth to more or less dependent offspring, parturition usually takes place during the animals' resting period and in a secure environment. We report here the first direct and documented observation of a daytime birth of a wild baby crested black macaque, Macaca nigra, in the Tangkoko Batuangus Nature Reserve, North Sulawesi, Indonesia. We further consider the parturition time as a female reproductive strategy in a broader evolutionary framework.