Stimulation of c-MYC transcriptional activity and acetylation by recruitment of the cofactor CBP

The c-MYC oncoprotein regulates various aspects of cell behaviour by modulating gene expression. Here, we report the identification of the cAMP-response-element-binding protein (CBP) as a novel c-MYC binding partner. The two proteins interact both in vitro and in cells, and CBP binds to the carboxy-terminal region of c-MYC. Importantly, CBP, as well as p300, is associated with E-box-containing promoter regions of genes that are regulated by c-MYC. Furthermore, c-MYC and CBP/p300 function synergistically in the activation of reporter-gene constructs. Thus, CBP and p300 function as positive cofactors for c-MYC. In addition, c-MYC is acetylated in cells. This modification does not require MYC box II, suggesting that it is independent of TRRAP complexes. Instead, CBP acetylates c-MYC in vitro, and co-expression of CBP with c-MYC stimulates in vivo acetylation. Functionally, this results in a decrease in ubiquitination and stabilization of c-MYC proteins. Thus, CBP and p300 are novel functional binding partners of c-MYC.     

Forestry Influence by Stump Harvest and Site Preparation on Methylmercury, Total Mercury and Other Stream Water Chemistry Parameters Across a Boreal Landscape

Forestry has been reported to cause elevated mercury (Hg) concentrations in runoff water. However, the degree to which forestry operations influence Hg in runoff varies among sites. A synoptic study, covering 54 catchments distributed all over Sweden, subjected to either stump harvest (SH), site preparation (SP) or no treatment (Ref), was undertaken to reveal the degree of forestry impact and causes of eventual variation. All streams were sampled twice, in autumn 2009 and summer 2010. There were no significant differences in total mercury (THg) and methylmercury (MeHg) concentrations between the three treatments in either 2009 or 2010. However, when pooling the treated catchments (that is, SH and SP) and taking catchment properties such as latitude into account, the treatment had a significant influence on the THg and MeHg concentrations. Although the treatment effect on THg and MeHg did not differ between SH and SP, the study did reveal significant forestry effects on potassium (K) and total nitrogen (TN) that were greater in the SH catchments and lower in the SP catchments. Partial least square (PLS) regressions indicated that organic matter was the most important variable influencing both the THg and MeHg concentrations. There were no significant differences between the treatment groups when comparing the ratios of THg/total organic carbon (TOC) and MeHg/TOC, suggesting that the high concentrations of THg and MeHg observed at some of the treated catchments are associated with increased concentrations of TOC rather than new methylation or increased mobilization caused by factors other than TOC.     

How the west was won: genetic reconstruction of rapid wolf recolonization into Germany’s anthropogenic landscapes

Following massive persecution and eradication, strict legal protection facilitated a successful reestablishment of wolf packs in Germany, which has been ongoing since 2000. Here, we describe this recolonization process by mitochondrial DNA control-region sequencing, microsatellite genotyping and sex identification based on 1341 mostly non-invasively collected samples. We reconstructed the genealogy of German wolf packs between 2005 and 2015 to provide information on trends in genetic diversity, dispersal patterns and pack dynamics during the early expansion process. Our results indicate signs of a founder effect at the start of the recolonization. Genetic diversity in German wolves is moderate compared to other European wolf populations. Although dispersal among packs is male-biased in the sense that females are more philopatric, dispersal distances are similar between males and females once only dispersers are accounted for. Breeding with close relatives is regular and none of the six male wolves originating from the Italian/Alpine population reproduced. However, moderate genetic diversity and inbreeding levels of the recolonizing population are preserved by high sociality, dispersal among packs and several immigration events. Our results demonstrate an ongoing, rapid and natural wolf population expansion in an intensively used cultural landscape in Central Europe.Subject terms: Conservation biology, Population genetics     

Xenogeneic transplantation of articular chondrocytes into full-thickness articular cartilage defects in minipigs: fate of cells and the role of macrophages

Xenogeneic or allogeneic chondrocytes hold great potential to build up new cartilage in vivo. However, immune rejection is a major concern for the utility of universal donor-derived cells. In order to verify the reported immune privilege of chondrocytes in vivo, the aim of this study was to assess engraftment of human articular chondrocytes (HAC) in minipig knee cartilage defects and their contribution to cartilage regeneration. HAC were transplanted matrix-assisted within two hydrogels into full-thickness cartilage defects of minipigs or implanted ectopically into immune deficient mice to assess redifferentiation capacity. At 2 and 4 weeks after surgery, cell-persistence and host cell invasion were monitored by species-specific in situ hybridization and RT-PCR. Early tissue regeneration was evaluated by histomorphometry and a modified O’Driscoll score. HAC capable of successful in vivo chondrogenic redifferentiation persisted at ectopic sites for 4 weeks in both carrier materials. Early defect regeneration involved extensive host cell invasion and a decline of HAC to less than 5 % of initial cell numbers in 6/12 defects within 2 weeks. Few clusters of persisting HAC within collagen type II-rich tissue were surrounded by porcine macrophages. Four weeks after cell transplantation, most of the defects contained well-integrated cell-rich tissue free of human cells with no apparent difference between hydrogel carriers. In summary, HAC failed to engraft in porcine articular cartilage defects despite their ability for successful in vivo redifferentiation. The co-localization of macrophages to hydrogel-implanted HAC suggests active graft rejection without evidence for an immune-privileged status of xenogeneic chondrocytes in a large animal joint.     

Haplosyllis xeniaecola,ein neuer Polychaet (Syllidae) von den Molukken (Indonesien)

Haplosyllis xeniaecola sp. n. is described. It was collected by W. Kükenthal fromXenia viridis (Octocorallia) at Ternate, Molukken Islands.

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Mitglied der Taxonomischen Arbeitsgruppe an der Biologischen Anstalt Helgoland     

Secondary sensory cells in the gravity receptor system of the statocyst of Octopus vulgaris

Summary The presence of secondary sensory cells in the Octopus gravity receptor system has been demonstrated. In serial thin sections of the receptor cells (hair cells) no axons were found leaving the cells. Instead, synapses were observed with synaptic vesicles lying inside the receptor cells. Both data clearly indicate that the receptor hair cells represent secondary sensory cells. In addition, efferent contacts to the receptor cells could be confirmed.This work was supported in part by grant Wo 160/5 of the Deutsche Forschungsgemeinschaft to Prof. Dr. H.G. WolffThe experimental work was done in part at the Zoological Station in Naples and at the Sechenov Institute of Evolutionary Physiology and Biochemistry of the USSR Academy of Sciences (Laboratory of Prof. Dr. Ya.A. Vinnikov), Leningrad, USSR. The authors thank Prof. Vinnikov and Dr. Tsirulis for stimulating discussions     

Changes in physiological and neuroendocrine properties during thermal adaptation of golden hamsters (Mesocricetus auratus)

Summary Golden hamsters raised at 22°C were adapted in the early summer for 3 weeks to either 28°C or 5°C. To achieve profound changes the photoperiod was also shortened from 14 h to 11 h during adaptation to cold. During the investigation body weight, food consumption, water intake, urine production, and osmolality, as well as secreted amounts of noradrenaline (NA) and dopamine (DA), were recorded in each animal before, during, and after the adaptation period. In another group of golden hamsters the brains were processed for immunocytochemical detection of arginine-vasopressin (AVP) and corticotropin releasing factor (CRF) in the third week of adaptation to a cold or warm environment. In warm-adapted animals food and water consumption and urine production remained unchanged or were only slightly reduced. NA and DA secretion were reduced by 50%. The AVP-immunoreactivity reflected an antidiuretic state in these animals. In fibers influencing the adrenal axis, AVP-immunoreactivity was weak compared to CRF fibers. Food and water consumption, urine production, and DA secretion increased two-fold during cold adaptation. Daily secreted amounts of NA increased nine-fold. AVP-immunoreactivity was weak in projections to the neurohypophysis. Fibers influencing the adrenal axis, however, displayed strong AVP-immunoreactivity in comparison to that of CRF. The immunocytochemically determined patterns of AVP and CRF distribution indicated an activation of the osmoregulative axis in the warm-adapted animals and of the adrenal axis in the cold-adapted golden hamsters.Abbreviations NA noradrenaline - DA dopamine - AVP argininevasopressin - CRF corticotropin releasing factor - SON supraoptic nucleus     

ROS Dynamics Delineate Functional States of Hippocampal Neural Stem Cells and Link to Their Activity-Dependent Exit from Quiescence

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