Drowned or Dry: A Cross-Habitat Comparison of Detrital Breakdown Processes

Nutrient cycles in both terrestrial and many freshwater habitats are fueled by terrestrial detritus. However, direct comparisons of decomposition processes in these environments are scarce. Aiming at shedding light on similarities and differences in these processes in different habitats, we studied decomposition of low-quality versus high-quality detritus through the action of shredders versus grazers in aquatic versus terrestrial microcosms under controlled climatic conditions. Decomposition processes were most strongly affected by whether they took place in the terrestrial or the aquatic environment: Leaching resulted in a rapid mass loss of detritus in the aquatic environment, and detritus traits became less pronounced over time. Thus, breakdown was mediated through dissolved organic matter (DOM) in water but through particulate organic matter (POM) on land. Litter mass loss and the promoting effects of detritivores on mass loss also depended on the environment, but shredders always had a greater effect than grazers. Both litter and detritivore diversity were overall of little relevance for litter mass loss, but more so in the aquatic than the terrestrial environment. By contrast, the influence of detritivores on microbes was stronger in water than on land, but effects depended on the litter type. The type of both litter and detritivores, however, was less significant in the aquatic than in the terrestrial environment, possibly due to leaching and abiotic processing of litter during early decomposition, resulting in diminishing differences between litter types. We conclude that the habitat type shapes the dynamics of leaf litter decomposition. Heavy leaching (in the aquatic environment) shortens initial decomposition phases and dislocates the degradation of easily accessible compounds in the form of DOM from the leaves into the water column. Consequently, initial interspecific differences in litter quality diminish, and both functional differences in, and diversity of, both litter and detritivores become less important than in the terrestrial environment.     

Towards automated production and drug sensitivity testing using scaffold-free spherical tumor microtissues

Although the relevance of three-dimensional (3-D) culture has been recognized for years and exploited at an academic level, its translation to industrial applications has been slow. The development of reliable high-throughput technologies is clearly a prerequisite for the industrial implementation of 3-D models. In this study the robustness of spherical microtissue production and drug testing in a 96-well hanging-drop multiwell plate format was assessed on a standard 96-well channel robotic platform. Microtissue models derived from six different cell lines were produced and characterized according to their growth profile and morphology displaying high-density tissue-like reformation and growth over at least 15 days. The colon cancer cell line HCT116 was chosen as a model to assess microtissue-based assay reproducibility. Within three individual production batches the size variations of the produced microtissues were below 5%. Reliability of the microtissue-based assay was tested using two reference compounds, staurosporine and chlorambucil. In four independent drug testings the calculated IC(50) values were benchmarked against 2-D multiwell testings displaying similar consistency. The technology presented here for the automated production of a variety of microtissues for efficacy testing in a standard 96-well format will aid the implementation of more organotypic models at an early time point in the drug discovery process.     

Desferoxamine and ethyl-3,4-dihydroxybenzoate protect myocardium by activating NOS and generating mitochondrial ROS

Protection from a prolyl hydroxylase domain-containing enzyme (PHD) inhibitor, desferoxamine (DFO), was recently reported to be dependent on production of reactive oxygen species (ROS). Ischemic preconditioning triggers the protected state by stimulating nitric oxide (NO) production to open mitochondrial ATP-sensitive K+ (mitoK(ATP)) channels, generating ROS required for protection. We tested whether DFO and a second PHD inhibitor, ethyl-3,4-dihydroxybenzoate (EDHB), might have similar mechanisms. EDHB and DFO increased ROS generation by 50-75% (P < 0.001) in isolated rabbit cardiomyocytes. This increase after EDHB exposure was blocked by N(omega)-nitro-L-arginine methyl ester (L-NAME), an NO synthase (NOS) inhibitor; ODQ, a guanylyl cyclase antagonist; and Rp-8-bromoguanosine-3',5'-cyclic monophosphorothioate Rp isomer, a PKG blocker, thus implicating the NO pathway in EDHB's signaling. Glibenclamide, a nonselective K(ATP) channel blocker, or 5-hydroxydecanoate, a selective mitoK(ATP) channel antagonist, also prevented EDHB's ROS production, as did blockade of mitochondrial electron transport with myxothiazol. NOS is activated by Akt. However, neither wortmannin, an inhibitor of phosphatidylinositol-3-kinase, nor Akt inhibitor blocked EDHB-induced ROS generation, indicating that EDHB initiates signaling downstream of Akt. DFO also increased ROS production, and this effect was blocked by ODQ, 5-hydroxydecanoate, and N-(2-mercaptopropionyl)glycine, an ROS scavenger. DFO increased cardiomyocyte production of nitrite, a metabolite of NO, and this effect was blocked by an inhibitor of NOS. DFO also spared ischemic myocardium in intact hearts. This infarct-sparing effect was blocked by ODQ, L-NAME, and N-(2-mercaptopropionyl)glycine. Hence, DFO and EDHB stimulate NO-dependent activation of PKG to open mitoK(ATP) channels and produce ROS, which act as second messengers to trigger entrance into the preconditioned state.     

Interaction of the regulator proteins RcsA and RcsB with the promoter of the operon for amylovoran biosynthesis in Erwinia amylovora

The RcsA and RcsB proteins of Erwinia amylovora and Escherichia coli were expressed in E. coli and purified. Their DNA-binding activity was examined using a 1-kb DNA region containing the putative promoter of the ams operon of Ew. amylovora, which is responsible for the biosynthesis of the exopolysaccharide amylovoran. Mobility shift assays indicated specific binding of RcsA and RcsB to a region of 78?bp spanning nucleotide positions ?578 to ?501 relative to the translational start of the first open reading frame of the operon. This region includes stretches of homology to E. coliσ ⁷⁰ promoter consensus sequences and to the E. coli cps promoter region. Binding of the Rcs proteins was not found at a JUMPstart consensus, typical for various promoters of polysaccharide gene clusters. DNA-binding activity was not detected for RcsA alone and only high concentrations of RcsB were able to interact with the ams promoter in our assay. The two proteins bind cooperatively at the indicated region of the ams promoter and further evidence is provided showing that the DNA-protein complex formed involves a heterodimer of RcsA and RcsB. The specific activity of RcsA, but not of RcsB, was enhanced when the protein was expressed in E. coli at 28°?C, relative to expression at 37°?C. In addition, DNA-protein complex formation is affected by temperature. The E. coli RcsA/RcsB proteins bind to the same region of the ams promoter and are able to interact with the Rcs proteins from Ew. amylovora.     

NOMENCLATURAL NOTE ON A THECADINIUM SPECIES (DINOPHYCEAE,GONYAULACALES), WHICH WAS DESCRIBED AS NEW INDEPENDENTLY THREE TIMES WITHIN TWO MONTHS1

Three Thecadinium species, independently described as new in three separate publications, are actually regarded as conspecific. The combined plate formula is Po 3′ 1a 6″ 5‐7/8c 5s 6″′ 2″″. The size range of the species is 38–65 l m in length and 23–42 lm in depth. It has one or two strongly lobed chloroplasts. The correct name of the species is Thecadinium yashimaense Yoshimatsu, Toriumi et Dodge 2004. Thecadinium mucosum Hoppenrath et Taylor 2004 and Thecadinium foveolatum Bolch 2004 are taxonomical synonyms. This note clarifies the plate tabulation and other features of the species.     

Otto Kleinschmidt und Ernst Hartert

Ohne ZusammenfassungMit einer Einführung     

Assumption 2: opaque to intuition?

Aim The aim of this paper was to revise the historical biogeographical method for resolving complicated distribution patterns through a technique that has come to be called assumption 2. Assumption 2 was used to resolve multiple areas on a single terminal branch (masts) as well as paralogous and missing areas in two or more areagrams. Recent examples, however, have shown that assumption 2 may be using rather than resolving paralogy. The paper attempts to resolve this problem by formulating a separate procedure to avoid using paralogous (redundant) area data in area cladistic analyses. Method The revision results in a new derivative method, the transparent method, to replace assumptions 1 and 2. It separates the procedures for resolving paralogy and for solving distribution patterns that occur in more than one area (masts). Results Several hypothetical examples show how the transparent method reduces paralogy and masts. The results show that paralogy can be reduced if the paralogy subtree method is applied after uncovering all possible relationships as single components on the terminals of areagrams. Conclusion The transparent method is a significant step forward in cladistic biogeography as it utilizes area relationships rather than generating general areagrams based on paralogous data.