Plant–pollinator networks in semi‐natural grasslands are resistant to the loss of pollinators during blooming of mass‐flowering crops

Mass‐flowering crops lead to spatial redistributions of pollinators and to transient shortages within nearby semi‐natural grasslands, but the impacts on plant–pollinator interactions remain largely unexplored. Here, we characterised which pollinator species are attracted by oilseed rape and how this affected the structure of plant–pollinator networks in nearby grasslands. We surveyed 177 networks from three countries (Germany, Sweden and United Kingdom) in 24 landscapes with high crop cover, and compared them to 24 landscapes with low or no oilseed rape during and after crop blooming. On average 55% of grassland pollinator species were found on the crop, which attracted 8–35% of individuals away from grasslands. However, networks in the grasslands were resistant to these reductions, since mainly abundant and highly mobile species were attracted. Nonetheless, simulations indicated that network structural changes could be triggered if > 50% of individuals were attracted to the crop (a value well‐above that found in our study system), which could affect community stability and resilience to further disturbance.     

Facilitation of nerve stimulation evoked noradrenaline overflow by isoprenaline but not by circulating adrenaline in the dog in vivo

The influence of isoprenaline and adrenaline on the overflow of endogenous noradrenaline evoked by sympathetic nerve stimulation was studied in canine blood perfused gracilis muscle in situ. Neuronal uptake was inhibited by desipramine. Local i.a. infusions of isoprenaline enhanced stimulation evoked noradrenaline overflow by 32 +/- 10% (P less than 0.05), indicating the existence of prejunctional facilitatory beta-adrenoceptors. This effect of isoprenaline was not antagonized by beta 1-adrenoceptor blockade and does not seem to be related to the vasodilatation caused by isoprenaline. In a second series of experiments circulating adrenaline levels were raised by i.v. infusions from basal levels of 0.4 +/- 0.2 nM to 1.7 +/- 0.2 and 6.3 +/- 0.6 nM, respectively, in arterial plasma. Adrenaline elicited vasodilatation in the gracilis muscle (19 +/- 3 and 28 +/- 5% increases in vascular conductance, respectively), indicating activation of postjunctional beta 2-adrenoceptors, without influencing nerve stimulation evoked noradrenaline overflow. Thus, our results support the existence of a prejunctional beta 2-adrenoceptor mediated mechanism facilitating noradrenaline release in vivo, but provide no evidence to support the idea that physiologically relevant increases in circulating adrenaline levels enhance noradrenergic neurotransmission in skeletal muscle.     

Raman spectroscopic study on the conformation of 11 S form acetylcholinesterase from Torpedo californica

Vibrational Raman spectroscopy has been used to study the conformation of the 11 S form of acetylcholinesterase from Torpedo californica. Secondary structure analysis by the method of Williams [(1983) J. Mol. Biol. 166, 581-603] shows 49% alpha-helical structure, 23% beta-sheets, 11% turns and 15% undefined structure. Secondary structure estimates obtained for this enzyme by Raman spectroscopy and circular dichroism have been analyzed.     

PARP1 proximity proteomics reveals interaction partners at stressed replication forks

PARP1 mediates poly-ADP-ribosylation of proteins on chromatin in response to different types of DNA lesions. PARP inhibitors are used for the treatment of BRCA1/2-deficient breast, ovarian, and prostate cancer. Loss of DNA replication fork protection is proposed as one mechanism that contributes to the vulnerability of BRCA1/2-deficient cells to PARP inhibitors. However, the mechanisms that regulate PARP1 activity at stressed replication forks remain poorly understood. Here, we performed proximity proteomics of PARP1 and isolation of proteins on stressed replication forks to map putative PARP1 regulators. We identified TPX2 as a direct PARP1-binding protein that regulates the auto-ADP-ribosylation activity of PARP1. TPX2 interacts with DNA damage response proteins and promotes homology-directed repair of DNA double-strand breaks. Moreover, TPX2 mRNA levels are increased in BRCA1/2-mutated breast and prostate cancers, and high TPX2 expression levels correlate with the sensitivity of cancer cells to PARP-trapping inhibitors. We propose that TPX2 confers a mitosis-independent function in the cellular response to replication stress by interacting with PARP1.     

Effect of graduated embolization of the coronary vessels using microspheres on the pumping function and contractility of the left ventricle in rats

Left ventricle (LV) function and systemic hemodynamic changes after coronary artery embolization by 15 microns radioactive microspheres were studied in anesthetized rats. Selective coronary embolization was produced by microsphere injection during ascending aorta occlusion in closed chest animal by using "L"-shaped wire. Maximal pressure (Pmax) developed was evaluated during ascending aorta occlusion. Coronary embolization evoked dose-dependent reduction in Pmax and dP/dtmax and then decrease in basal LV systolic pressure. dP/dt/P, with parallel increase in end diastolic LV pressure. Changes of cardiac output were bidirectional: after administration of relatively small amount of microspheres cardiac output increased. This method can be used for producing quantitative myocardial ischemia and we suggest that it may be a suitable model of the chronic heart failure.     

Genetic diversity is retained in a bottlenecked Cinereous Vulture population in Turkey

Vulture populations worldwide have suffered precipitous declines in recent decades. The Cinereous Vulture Aegypius monachus, a highly philopatric scavenger distributed across southern Europe and the central Asian plateau, is threatened in many parts of its range. Turkey holds the second largest population of this species in the Western Palaearctic, but there has been no research on its genetic structure and the possible implications of this structure for the future of the species. Here we report nuclear diversity and relatedness determined by short tandem repeat genotyping of 81 individuals from the four largest colonies. Our results demonstrated no significant genetic structuring, suggesting a single panmictic metapopulation connected by frequent dispersal. Furthermore, we show that the study population has retained moderate levels of genetic diversity, despite passing through a recent demographic bottleneck. We estimated the effective population size to be 112 individuals (95% confidence interval 74–201). Our results imply that the observed lack of increase in population size since the 1990s has not been caused by lowered fitness due to genetic inbreeding but rather by increased mortality via demographic processes. In the short term, we suggest that conservation efforts should treat the Turkish subpopulations as a single management unit and aim to increase population size through effective protection, especially during the breeding season.