A Positive GATA Element and a Negative Vitamin D Receptor-Like Element Control Atrial Chamber-Specific Expression of a Slow Myosin Heavy-Chain Gene during Cardiac Morphogenesis

We have used the slow myosin heavy chain (MyHC) 3 gene to study the molecular mechanisms that control atrial chamber-specific gene expression. Initially, slow MyHC 3 is uniformly expressed throughout the tubular heart of the quail embryo. As cardiac development proceeds, an anterior-posterior gradient of slow MyHC 3 expression develops, culminating in atrial chamber-restricted expression of this gene following chamberization. Two cis elements within the slow MyHC 3 gene promoter, a GATA-binding motif and a vitamin D receptor (VDR)-like binding motif, control chamber-specific expression. The GATA element of the slow MyHC 3 is sufficient for expression of a heterologous reporter gene in both atrial and ventricular cardiomyocytes, and expression of GATA-4, but not Nkx2-5 or myocyte enhancer factor 2C, activates reporter gene expression in fibroblasts. Equivalent levels of GATA-binding activity were found in extracts of atrial and ventricular cardiomyocytes from embryonic chamberized hearts. These observations suggest that GATA factors positively regulate slow MyHC 3 gene expression throughout the tubular heart and subsequently in the atria. In contrast, an inhibitory activity, operating through the VDR-like element, increased in ventricular cardiomyocytes during the transition of the heart from a tubular to a chambered structure. Overexpression of the VDR, acting via the VDR-like element, duplicates the inhibitory activity in ventricular but not in atrial cardiomyocytes. These data suggest that atrial chamber-specific expression of the slow MyHC 3 gene is achieved through the VDR-like inhibitory element in ventricular cardiomyocytes at the time distinct atrial and ventricular chambers form.     

Continuous coenzyme dependent stereoselective synthesis of sulcatol by alcohol dehydrogenase

Summary 6-methyl-5-hepten-2-one was reduced to sulcatol ((+)-6-methyl-5-hepten-2-ol) by using alcohol dehydrogenase fromThermoanaerobium brockii in a continuous process. The cofactor NADP(H) was retained by a charged UF-membrane and regenerated by oxidation of isopropanol to acetone. Use of native NADP in a charged UF-membrane reactor proved to be superior to use of PEG coupled NADP in a uncharged UF-membrane reactor.     

A- and B-type lamins are differentially expressed in normal human tissues

 A selection of normal human tissues was investigated for the presence of lamins B1, B2, and A-type lamins, using a panel of antibodies specific for the individual lamin subtypes. By use of immunoprecipitation and two-dimensional immunoblotting techniques we demonstrated that these antibodies do not cross-react with other lamin subtypes and that a range of different phosphorylation isoforms is recognized by each antibody. The lamin B2 antibodies appeared to decorate the nuclear lamina in all tissues examined, except hepatocytes, in which very little lamin B2 expression was observed. In contrast to previous studies, which suggested the ubiquitous expression of lamin B1 in mammalian tissues, we show that lamin B1 is not as universally distributed throughout normal human tissues as was to be expected from previous studies. Muscle and connective tissues are negative, while in epithelial cells lamin B1 seemed to be preferentially detected in proliferating cells. These results correspond well with those obtained for lamin B1 in chicken tissues. The expression of A-type lamins is most prominent in well-differentiated epithelial cells. Relatively undifferentiated and proliferating cells in epithelia showed a clearly reduced expression of A-type lamins. Furthermore, most cells of neuroendocrine origin as well as most hematopoietic cells were negative for A-type lamin antibodies. Accepted: 4 February 1997     

Immunohistological detection of Saruplase (recombinant single-chain urokinase-type plasminogen activator) in normal rat tissue

Summary Saruplase — a recombinant single-chain urokinase-type plasminogen activator was identified immunohistochemically in normal rat tissue after intravenous administration by means of a polyclonal antibody. For this purpose, rat tissues were fixed in various ways (liquid nitrogen, ethanol, formaldehyd solution). Saruplase could be detected by the PAP method, streptavidinbiotin system and indirect immunofluorescence in the kidney (proximal tubule), liver (hepatocytes, Kupffer cells) and spleen (reticular cells). Saruplase was not localized in the rat endothelium. It is discussed that the ratspecific receptors for urokinase-type plasminogen activator on endothelial cells cannot bind Saruplase due to the extreme species specificity.     

Stronger dung removal in forests compared with grassland is driven by trait composition and biomass of dung beetles

1. Ecosystem processes depend on the biomass of the involved organisms, but their functional diversity may play an additional role. In particular, the exclusion of key functional groups through habitat disturbance may lead to the breakdown of ecosystem functions. Dung removal is an important process contributing to nutrient cycling and thus productivity in grazed ecosystems. 2. This study investigated the role of different functional groups of dung beetles in dung removal in different habitats within a wood-pasture in two different seasons. An experimental setting with 12 blocks and 108 dung pads was used to investigate short-term dung removal over 1 week of exposure. 3. Dung removal was most strongly affected by habitat type, with almost 40% lower levels in grassland than in adjacent forest and forest gaps. Of all assemblage characteristics, total biomass of tunneller species was the strongest predictor of dung removal, whereas functional diversity showed no significant effect. In accordance with the dung removal pattern at habitat type level, densities of large tunnellers were suppressed in grassland compared with forest. 4. It is concluded that dung removal is habitat-specific and large tunnellers play a disproportionate role in this important ecosystem function in temperate forests.