Wie wachsen Tropenbäume? Jahrringe als Ausdruck von Klimabedingungen und Lebensform

Growth of tropical trees is largely depending on the seasonality of the local climate. In many trees growing in areas with a distinct dry season, cambial activity ceases resulting in the formation of annual rings. In very humid mountain rainforests, trees stop to grow already after short rainless periods. By a combination of increment measurements and wood anatomical analyses, the climatic control of wood formation can be assessed. Intra‐annual wood density variations and content of various stable isotopes enable the climatological interpretation of the “wood signals”.     

Risikofaktoren für Krebs und MS in Kuhmilch und Rindfleisch?

Dairy cattle meat and milk factors contributing to the risk of cancers and multiple sclerosis A global epidemiological analysis of the incidence of colon and breast cancers suggests that consumption of meat and milk products of Eurasian dairy cattle contributes to the risk for these malignancies. Our group isolated a number of novel single‐stranded DNAs from serum and milk of dairy cattle. These are circular molecules (～1000–3000 nucleotides) of putative viral origin. Apparently this DNA does not integrate into chromosomal DNA of the animal hosts, but persists in a non‐integrated (episomal) state. Following transmission into human cells, this DNA is genetically active. Related isolates have been obtained from two lesions of patients with multiple sclerosis. Concepts have been developed to explain the potential etiological role of such agents for specific human diseases. Their involvement in human cancers and neurological diseases is presently subject of intensive investigations.     

Können Tiere zählen?

The “magical” number four We know already since more than 140 years that humans have the inborn ability to recognize only up to four objects correctly if counting is strictly inhibited. Many vertebrates and the honeybee workers can remember up to four objects albeit they are unable to count. This inborn numerical competence common to humans and animals raises interesting questions concerning the purpose and the evolution of this ability. The “magical” number four is obviously a neurological, historical and mythological enigma.     

Wo lebten die ersten Zellen – und wovon?

How, and where, did the first cells on Earth grow? The last universal common ancestor of all cells (Luca) was long considered as the common ancestor of bacteria, archaea and eukaryotes. New trees of life have a host for the origin of mitochondria (of eukaryotes) branching within the archaea, making Luca the common ancestor of bacteria and archaea. New comparative genomic investigations have reconstructed Luca's microbial ecology. The 355 protein families that trace back to Luca by phylogenetic criteria describe Luca as anaerobic, CO₂ ‐ and N₂ ‐fixing, H₂ ‐dependent and thermophilic. Luca's biochemistry was replete with FeS clusters and radical reaction mechanisms, its cofactors reveal an essential role for transition metals in its metabolism. Luca lived in an anaerobic geochemical active environment rich in H₂ , CO₂ and iron. This lifestyle is similar to modern acetogens (bacteria) and methanogens (archaea), the physiologically most ancient microbes.     

Biodiversitätsforschung – wohin geht die Reise?

Biodiversity and biodiversity politics Extrapolations for a range of indicators suggest that based on current trends, pressures on biodiversity will continue to increase (Global Biodiversity Outlook 4, 2014). Since services of nature, like fertile soil, clear water and clean air are achieved by consortia of organisms rather than by individual species, they are already endangered. This holds, in spite of the fact, that only 10% of the earth's organisms are known to science and that therefore the loss caused by global change cannot be reliably quantified. Today, science develops new methods for recording consortia of coexisting organisms in a habitat. With the Convention on Biological Diversity, biodiversity has become a matter of politics which is welcome with respect to species and habitat conservation, but the concern of biopiracy creates bureaucratic hurdles hindering research. The most recent achievement is IPBES (Intergovernmental Platform on Biodiversity and Ecosystem Services, Bonn), which strives to bring more science into biodiversity politics.     

Produktion von Ochratoxin A und B durch<Emphasis Type="Italic">Penicillium verrucosum</Emphasis> auf Gerste in Abhängigkeit der Parameter Wasseraktivität,Wassergehalt und Temperatur

The ochratoxin A and B (OTA, OTB) production by a toxigenic isolate ofPenicillium verrucosum grown on brewing barley up to six weeks was studied at a storage temperature of 25 °C and different moisture and water activity conditions. Sorption isothermes for barley were prepared at temperatures of 10°C, 15°C and 25°C. OTA was produced after 2 weeks of storage at moisture contents of ≥19%, which is equivalent to water activities (a_w) of 0.83 (adsorptive) and 0.82 (desorptive) at 25 °C. Increased OTA concentrations (5.8-fold and 16.1-fold) were noticed when the moisture contents were adjusted to 20% (a_{w [ads]} 25 °C=0.86) and 21% (a_{w [ads]} [ 25 °C=0.88), respectively. An increase was also shown during storage of 4 and 6 weeks (1.2-fold and 2.4-fold, respectively). Production of OTB was shown to occur at moisture contents ≥18% (a_{w [ads]} 25 °C=0.81). The findings document that OTA and OTB are not produced byP. verrucosum grown on barley stored below 18% moisture content.     

Die<Emphasis Type="Italic">Pseudotextularia</Emphasis>-Zone der Bohrung Maasbüll I und ihre Foraminiferen-Fauna

The Foraminifera of thePseudotextularia-Zone from a borehole-section at Maasbüll (Schleswig), w. Germany, are described and figured. Between them are 9 new species of the generaHeterostomella, Gaudryina, Neoftabellina, Nodogenerina, Bolivina, Gavelinopsis, Globigerina — and 1 subspecies ofGavelinella pertusa.Faunas of two localities from Danmark, same horizon, are treated also. Comparisons are given with other faunas of same age, particularly from Egypt and Israel.     

Studien an WasserschildkrÖten; Beziehungen Zwischen KÖrperbau und Bewegungsweise

Zusammenfassung 1. An 350 Exemplaren aus verschiedenen Familien wird die relative Höhe des Rückenpanzers festgestellt. Wie zu erwarten, sind flache Panzer im allgemeinen bezeichnend für Schildkröten, die im Wasser leben und sich hier geschickt bewegen.2. An fast 200 Exemplaren aus verschiedenen Familien werden die relativen Längen der Beinabschnitte festgestellt. Es wird versucht, eine Beziehung zwischen dem Bewegungsvermögen im Wasser und der Länge bestimmter Beinabschnitte zu finden. Am deutlichsten ist diese Beziehung bei den distalen Beinteilen: je besser die Schwimmfähigkeit, je ausgesprochener die Anpassung an das Wasserleben auch sonst, desto langer sind im allgemeinen Hand und Fuß.3. Auf die Bedeutung der Beinhaltung für die Schwimmbewegungen wird hingewiesen.4. Die Abflachung der distalen Beinabsohnitte bei guten Schwimmern, die Vergrößerung der Ruderfläche durch Spreizfähigkeit der Zehen, durch Ausbildung von Schwimmhäuten, Haut- und Schuppensäumen wird an einer Reihe von Beispielen aufgezeigt.     

Functional Foods — Lebensmittel der Zukunft?: Maßgeschneiderte Ernährung

Functional foods might be helpful in improving the nutritional status and preventing certain diseases. In order to inform the consumer about the benefit of a product it will be necessary to enable scientifically proved health claims. These health claims have to be supported by studies and should make clear how a product can influence health. Only if there are proven facts, functional foods could establish on the market as foods of the future in the longer term beside the naturally healthful products. It will be of no use neither to the consumer nor to the food industry to promote these product group with exaggerated promises as a kind of miracle cure which can help against all diseases. The acceptance of the consumer will depend on credible product concepts. Another important precondition for functional foods is that there are absolutely no health risks associated with the consumption of these products. Recommendations regarding fortification and intake of functional foods must consider this aspect. Side effects by excessive doses or imbalances are to be avoided. The consumer should know that the point is not to take as much as possible of potentially healthful single substances but to show clearly that physiological dosages, which can also be attained by a higher intake of traditional food are associated with the best benefit‐risk relation, i.e. show the greatest benefit and minimal risk. In general functional foods do not resolve any nutritional problem. The effects are limited, especially if the nutrition is imbalanced (e.g. hyperenergetic, high fat). In these cases the addition of functional foods offers no or only small corrective effects. Functional foods represent no substitute for a fully balanced nourishment with a high amount of naturally healthy foods such as vegetables, fruits, whole grain products as well as milk and milk products.     

Role of Photorespiration and Cyclic Electron Transport in C<Subscript>4</Subscript> Photosynthesis Evolution in the C<Subscript>3</Subscript>–C<Subscript>4</Subscript> Intermediate Species <Emphasis Type="Italic">Sedobassia sedoides</Emphasis>

Plants from two Sedobassia sedoides (Pall.) Aschers populations (Makan and Valitovo) (Chenopodiaceae) with C₂ photosynthesis (precursor of C₄ photosynthesis in phylogenesis) and photorespiratory CO₂-concentrating mechanism were studied. Genetic polymorphism and isotope discrimination (δ¹³С) levels of the plants were determined under natural conditions, and their morpho-physiological parameters such as fresh and dry biomass of the above ground parts of plants, functioning of photosystem I (PSI) and photosystem II (PSII), intensity of net photosynthesis (A), transpiration (E), photorespiration and water use efficiency (WUE) of plants were calculated under control and salinine conditions (0 and 200 mM NaCl). Results of the population-genetic analysis showed that the Makan population is polymorphic (plastic) and the Valitovo population is monomorphic (narrowly specialized). There were no significant differences between the populations based on δ¹³С values or growth parameters, PSII, A, E and WUE under control conditions. Under saline conditions, dry biomass accumulation decreased in the Makan population by 15% and by more than 2- fold in the Valitovo population. Population differences were revealed in terms of photorespiration intensity and P700 oxidation kinetics under control and saline conditions. Under control conditions, Makan plants were characterized by a higher photorespiration intensity, which decreased by 2-fold under saline conditions to the photorespiration level of Valitovo plants. Cyclic electron transport activity was minimal in the control Makan plants, and it increased by almost 2-fold under saline conditions to the level of that in Valitovo plants under control and saline conditions. Under control conditions, photosynthesis in Makan plants can be specified as the proto-Kranz type (transitional type from C₃ to C₂) and that in Valitovo plants can be specified as the C₂ type (C₄ photosynthesis with photorespiratory CO₂-concentrating mechanism), based on their photorespiration level and cyclic electron transport activity. Under saline conditions, Makan plants exhibited features of C₂ photosynthesis. Intraspecific functional differences of photosynthesis were revealed in different populations of intermediate C₃–C₄ plant species S. sedoides which reflect the initial stages of formation of a photorespiratory CO₂-concentrating mechanism during C₄ photosynthesis evolution, accompanied by decrease in salt tolerance.     

Distinct contributions of β4GalNAcTA and β4GalNAcTB to <Emphasis Type="Italic">Drosophila</Emphasis> glycosphingolipid biosynthesis

Drosophila melanogaster has two β4-N-acetylgalactosaminyltransferases, β4GalNAcTA and β4GalNAcTB, that are able to catalyse the formation of lacdiNAc (GalNAcβ,4GlcNAc). LacdiNAc is found as a structural element of Drosophila glycosphingolipids (GSLs) suggesting that β4GalNAcTs contribute to the generation of GSL structures in vivo. Mutations in Egghead and Brainaic, enzymes that generate the β4GalNAcT trisaccharide acceptor structure GlcNAcβ,3Manβ,4GlcβCer, are lethal. In contrast, flies doubly mutant for the β4GalNAcTs are viable and fertile. Here, we describe the structural analysis of the GSLs in β4GalNAcT mutants and find that in double mutant flies no lacdiNAc structure is generated and the trisaccharide GlcNAcβ,3Manβ,4GlcβCer accumulates. We also find that phosphoethanolamine transfer to GlcNAc in the trisaccharide does not occur, demonstrating that this step is dependent on prior or simultaneous transfer of GalNAc. By comparing GSL structures generated in the β4GalNAcT single mutants we show that β4GalNAcTB is the major enzyme for the overall GSL biosynthesis in adult flies. In β4GalNAcTA mutants, composition of GSL structures is indistinguishable from wild-type animals. However, in β4GalNAcTB mutants precursor structures are accumulating in different steps of GSL biosynthesis, without the complete loss of lacdiNAc, indicating that β4GalNAcTA plays a minor role in generating GSL structures. Together our results demonstrate that both β4GalNAcTs are able to generate lacdiNAc structures in Drosophila GSL, although with different contributions in vivo, and that the trisaccharide GlcNAcβ,3Manβ,4GlcβCer is sufficient to avoid the major phenotypic consequences associated with the GSL biosynthetic defects in Brainiac or Egghead.     

The humus layer determines SO<Subscript>4</Subscript><Superscript>2−</Superscript> isotope values in the mineral soil

Biocycling of sulfur (S) has been proposed to play an important role in the recovery of ecosystems following anthropogenic S deposition. Here, we investigated the importance of the humus layer in the biocycling of S in three forested catchments in the Gårdsjön area of southwestern Sweden with differing S inputs and S isotope signature values. These experimental sites consisted of two reference catchments and the Gårdsjön roof experiment catchment (G1), where anthropogenic deposition was intercepted from 1991 until May 2002 by a roof placed over the entire catchment area. Under the roof, controlled levels of deposition were applied, using a sprinkler system, and the only form of S added was marine SO₄²⁻ with a δ of +19.5‰.We installed ion exchange resin bags at the interface between the humus layer and mineral soil at each of the catchments to collect SO₄²⁻ passing through the humus. The resin bags were installed on four occasions, in 1999 and 2000, covering two summer and two winter periods. The ions collected by each bag during these sampling periods were then eluted and their δ values and SO₄²⁻ concentrations determined. The most striking result is that the average δ value in the resin bags was more than 12‰ lower compared to that of the sprinkler water in the G1 roof catchment. There was no increasing trend in the isotope value in the resin bag SO₄²⁻ despite that the roof treatment has been on-going for almost 10 years; the average value for all resin bags was +7.1‰. The highest δ values found in the G1 roof catchment were between +11‰ and +12‰. However, these values were all obtained from resin bags installed at a single sampling location. Throughfall and resin bag δ values were more similar in the two reference catchments: about +7.5‰ in both cases. There was, however, an increase in resin bag δ values during the first winter period, from about +7‰ to +9‰. The resin bag δ value was linearly and positively related (r² = 0.26, p < 0.001) to the amount of SO₄²⁻ extracted from the resin bags, if relatively high amounts (>50 mmol m⁻²) were excluded. High amounts of resin bag SO₄²⁻ seemed to be related to groundwater inputs, as indicated by the δ value. Our results suggest that rapid immobilization of SO₄²⁻ into a large organic S pool may alter the S isotope value and affect the δ values measured in the mineral soil and runoff.     

A theoretical study on the reaction mechanism of O<Subscript>2</Subscript> with C<Subscript>4</Subscript>H<Subscript>9</Subscript>• radical

Ab initio calculations have been performed using the complete basis set model (CBS-QB3) to study the reaction mechanism of butane radical (C₄H₉•) with oxygen (O₂). On the calculated potential energy surface, the addition of O₂ to C₄H₉• forms three intermediates barrierlessly, which can undergo subsequent isomerization or decomposition reaction leading to various products: HOO• + C₄H₈, C₂H₅• + CH₂CHOOH, OH• + C₃H₇CHO, OH• + cycle-C₄H₈O, CH₃• + CH₃CHCHOOH, CH₂OOH• + C₃H₆. Five pathways are supposed in this study. After taking into account the reaction barrier and enthalpy, the most possible reaction pathway is C₄H₉• + O₂ → IM1 → TS5 → IM3 → TS6 → IM4 → TS7 → OH• + cycle-C₄H₈O.     

Lässt sich altersbedingter Muskelschwund stoppen?

Molecular mechanisms of age‐related muscle wasting Sarcopenia is the age‐related loss of muscle mass and contractile force and characterized by the severely reduced regenerative capacity of aged muscle fibres and excitation‐contraction uncoupling between motor neuron and muscle. The application of comparative proteomics to study muscle aging has revealed interesting new pathobiochemical insights. Aging associated muscle weakness is characterized by secondary fast‐to‐slow transitions in the contractile apparatus and glycolytic‐to‐oxidative changes in energy metabolism. The identification of new protein biomarkers of muscle aging represents a substantial advance in the establishment of new diagnostic methods and therapeutic approaches for the lessening of the effects of the fragility syndrome.     

Chemical synthesis of 4-azido-β-galactosamine derivatives for inhibitors of <Emphasis Type="Italic">N</Emphasis>-acetylgalactosamine 4-sulfate 6-<Emphasis Type="Italic">O</Emphasis>-sulfotransferase

Chondroitin sulfate E (CS-E) plays a crucial role in diverse processes ranging from viral infection to neuroregeneration. Its regiospecific sulfation pattern, generated by N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST), is the main structural determinant of its biological activity. Inhibitors of GalNAc4S-6ST can serve as powerful tools for understanding physiological functions of CS-E and its potential therapeutic leads for human diseases. A family of new 4-acylamino-β-GalNAc derivatives and 4-azido-β-GalNAc derivatives were synthesized for their potential application as inhibitors of GalNAc4S-6ST. The target compounds were evaluated for their inhibitory activities against GalNAc4S-6ST. The results revealed that 4-pivaloylamino- and 4-azido-β-GalNAc derivatives displayed evident activities against GalNAc4S-6ST with IC₅₀ value ranging from 0.800 to 0.828 mM. They showed higher activities than benzyl D-GalNAc4S that was used as control.     

Zecken als Krankheitsüberträger: Was tun bei einem Stich?

Because of its wide host‐range and capacity for transmission of multiple pathogens, Ixodes icinus poses a constant threat of human infection. Borrelia burgdorferi is the most prevalent tick‐borne pathogen affecting humans (Lyme Borreliosis), tick‐borne‐encephalitis (TBE) the most important viral tick‐borne disease in Europe. In natural foci the pathogens circulate between infected small mammals and ticks. Knowing the lifecycle of I.ricinus, their multistrategies for host finding, attachment and blood ingestion, we may understand, what makes the tick such an excellent vector. Instructions for individual behaviour in tick areas to avoid tick contact are given. Since transmission is closely related to the feeding period it is helpful to remove an attached tick as soon as possible. Protection against tick‐borne encephalitis by vaccination is possible.     

Transformation competence and type-4 pilus biogenesis in Neisseria gonorrhoeae – a review

In Neisseria gonorrhoea (Ngo), the processes of type-4 pilus biogenesis and DNA transformation are functionally linked and play a pivotal role in the life style of this strictly human pathogen. The assembly of pili from its main subunit pilin (PilE) is a prerequisite for gonococcal infection since it allows the first contact to epithelial cells in conjunction with the pilus tip-associated PilC protein. While the components of the pilus and its assembly machinery are either directly or indirectly involved in the transport of DNA across the outer membrane, other factors unrelated to pilus biogenesis appear to facilitate further DNA transfer across the murein layer (ComL, Tpc) and the inner membrane (ComA) before the transforming DNA is rescued in the recipient bacterial chromosome in a RecA-dependent manner. Interestingly, PilE is essential for the first step of transformation, i.e., DNA uptake, and is itself also subject to transformation-mediated phase and antigenic variation. This short-term adaptive mechanism allows Ngo to cope with changing micro-environments in the host as well as to escape the immune response during the course of infection. Given the fact that Ngo has no ecological niche other than man, horizontal genetic exchange is essential for a successful co-evolution with the host. Horizontal exchange gives rise to heterogeneous populations harboring clones which better withstand selective forces within the host. Such extended horizontal exchange is reflected by a high genome plasticity, the existence of mosaic genes and a low linkage disequilibrium of genetic loci within the neisserial population. This led to the concept that rather than regarding individual Neisseria species as independent traits, they comprise a collective of species interconnected via horizontal exchange and relying on a common gene pool.     

Spezifität beim „Attachment” von Agrobacterium an Wundrandzellen von Kalanchoe?

Specificity of the Attachment of Agrobacterium to Wound Cells of Kalanchoe? Tumor induction by A. tumefaciens on leaves of Kalanchoe is severely inhibited by cell wall preparations from young and mature tissucs of monocotyledons and dicoryledons and from tumor cells and also by filter paper homogenates and living or dead Pseudomonas cells. The inhibition a demonstrable if the cell wall preparations or Pseudomonas cells are inoculated into the plant wounds at the same time with A tumefaciens or before A. tumefaciens a. Postinoculation does affect tumor These results demonstrate site binding as an important step of tumor induction without any doubt but at the same time they question the specificity of this process.