Discovery of a natural thiamine adenine nucleotide

Several important cofactors are adenine nucleotides with a vitamin as the catalytic moiety. Here, we report the discovery of the first adenine nucleotide containing vitamin B1: adenosine thiamine triphosphate (AThTP, 1), or thiaminylated ATP. We discovered AThTP in Escherichia coli and found that it accumulates specifically in response to carbon starvation, thereby acting as a signal rather than a cofactor. We detected smaller amounts in yeast and in plant and animal tissues.     

An unavoidably short history of inland aquatic animal diversity research in the US Virgin Islands

Aquatic Ecology - The first freshwater species from the US Virgin Islands (USVI) was described 190 years ago, but research on inland aquatic animals, particularly invertebrates, remains...     

Submerged Rootless Macrophytes Sustain a Stable State Against Free-Floating Plants

Ecosystems - Both non-rooted submerged vegetation dominated by coontail (Ceratophyllum demersum) and non-rooted floating duckweed vegetation (Lemna gibba) can maintain their stable dominance in...     

Behavioral patterns of two fiddler crab species Uca rapax and Uca tangeri in a seminatural mangrove system

Zoos increasingly transform their exhibitions from traditional one‐species enclosures to more natural exhibits, that is, environments that capture part of an ecosystem including a selection of animals and plants that occur there. Thus, enhancing the experience of its human visitors while also allowing its residents to possibly show more natural behavior. In 2017 Royal Burger's Zoo (Arnhem, The Netherlands) created and opened a mangrove‐like environment containing fiddler crabs. Fiddler crabs display a broad range of behaviors, and this research examines which wild‐type behavior and behavioral patterns can be observed on a seminatural mudflat. The behavior shown by Uca rapax and Uca tangeri on the mudflat was counted each hour between 07:00 and 17:00. An asymmetric tidal regime was present in the enclosure including two high water periods. Various known fiddler crab behaviors, including waving and combat, were observed but no copulation. A clear pattern in exposed crabs on the mudflat was found, with low numbers visible in the early morning and the highest numbers present in the early afternoon, while number of visitors did not have a significant effect on this pattern. Interestingly, the highest abundances were not observed around the ebbing tide (07:00–09:00), as observed in the wild, but somewhat later, possibly due to the asymmetric tidal scheme or the interaction of tidal and daily rhythms. This study shows that in captivity, fiddler crabs indeed show a range of natural behaviors which is linked to the tidal and possibly daily rhythm as well.     

Defining the risks of mesenchymal stromal cell therapy

We address the issue of the potential for malignant transformation of cultured mesenchymal stromal cells (MSC) commonly used in clinical cell-therapy protocols and describe the culture conditions under which tumorigenesis is likely to be an extremely uncommon event.     

PHYLETIC TRENDS IN SECTIONS EUBLEPHARIS AND CALLIOPSIS OF THE GENUS COREOPSIS (COMPOSITAE)

Artificial hybridization, fertility of interspecific and intersectional hybrids, chromosome numbers, and trends in habit and morphology in taxa of sections Eublepharis and Calliopsis of the genus Coreopsis are used to consider the sectional relationships and to derive a presumed phylogeny for the two sections. The two sections are closely related and show a low level of interfertility, but this level is as high as in some interspecific crosses within sections. The sections differ in base chromosome number and achene winging. The problematic C. rosea evidently should remain in section Eublepharis. Both sections probably arose from x = 13 stock resembling C. integrifolia or C. pubescens. Descending aneuploidy was involved in the derivation of section Calliopsis, while chromosome evolution in section Eublepharis has involved polyploidy.     

Normal development and fertility of knockout mice lacking the tumor suppressor gene LRP1b suggest functional compensation by LRP1

LRP1b and the closely related LRP1 are large members of the low-density lipoprotein receptor family. At the protein level LRP1b is 55% identical to LRP1, a multifunctional and developmentally essential receptor with roles in cargo transport and cellular signaling. Somatic LRP1b mutations frequently occur in non-small cell lung cancer and urothelial cancers, suggesting a role in the modulation of cellular growth. In contrast to LRP1, LRP1b-deficient mice develop normally, most likely due to its restricted expression pattern and functional compensation by LRP1 or other receptors. LRP1b is expressed predominantly in the brain, and a differentially spliced form is present in the adrenal gland and in the testis. Despite the presence of a potential furin cleavage site and in contrast to LRP1, immunoblotting for LRP1b reveals the presence of a single 600-kDa polypeptide species. Using a yeast two-hybrid approach, we have identified two intracellular proteins, the postsynaptic density protein 95 and the aryl hydrocarbon receptor-interacting protein, that bind to the intracellular domain of LRP1b. In addition, we have found several potential ligands that bind to the extracellular domain. Analysis of LRP1b knockout mice may provide further insights into the role of LRP1b as a tumor suppressor and into the mechanisms of cancer development.     

Receptor clustering is involved in Reelin signaling

The Reelin signaling cascade plays a crucial role in the correct positioning of neurons during embryonic brain development. Reelin binding to apolipoprotein E receptor 2 (ApoER2) and very-low-density-lipoprotein receptor (VLDLR) leads to phosphorylation of disabled 1 (Dab1), an adaptor protein which associates with the intracellular domains of both receptors. Coreceptors for Reelin have been postulated to be necessary for Dab1 phosphorylation. We show that bivalent agents specifically binding to ApoER2 or VLDLR are sufficient to mimic the Reelin signal. These agents induce Dab1 phosphorylation, activate members of the Src family of nonreceptor tyrosine kinases, modulate protein kinase B/Akt phosphorylation, and increase long-term potentiation in hippocampal slices. Induced dimerization of Dab1 in HEK293 cells leads to its phosphorylation even in the absence of Reelin receptors. The mechanism for and the sites of these phosphorylations are identical to those effected by Reelin in primary neurons. These results suggest that binding of Reelin, which exists as a homodimer in vivo, to ApoER2 and VLDLR induces clustering of ApoER2 and VLDLR. As a consequence, Dab1 becomes dimerized or oligomerized on the cytosolic side of the plasma membrane, constituting the active substrate for the kinase; this process seems to be sufficient to transmit the signal and does not appear to require any coreceptor.