Operational Sex Ratio and Individual Mating Frequencies in Two Bushcricket Species (Orthoptera,Tettigonioidea, Poecilimon)

During mating the male bushericket transfers a large spermatophore which is consumed by the female after copulation. Such a ‘nuptial gift' is likely to have strong effects on the mating frequency of both males and females and thus on the operational sex ratio (OSR): For the male a longer time period will be required in which he is prevented from further matings. For the female consumption may be advantageous increasing interest in matings. To quantify these effects field studies were carried out on two species of the genus Poecilimon. Both species differed widely in the mean number of matings observed per day (19% of all females in P. veluchianus compaied to 42% in P. affinis; Fig. 2) and thus in the distribution of female mating intervals (P. veluchianus 2 days, P. affinis 1 day (modes); Fig. 3). Separate experiments on the minimum male mating interval and the spermatophore weight also revealed distinct differences: the mean spermatophore weight was 26% of the male body weight in P. veluchianus and 15% in P. affinis (Fig. 6). Accordingly the refractory period was longer in P. veluchianus; 3 days after a previous mating nearh all males were ready to remate, compared to 2 days in P. affinis (Fig. 5). These differences, however, compensated one another in that the amount of spermatophylax material transferred per day was very similar in both species in relation to female body weight. Using data on female mating frequency per day and male remating ability, an upper estimate for the OSR was calculated. A lower limit for the OSR was given taking into account the most frequent female mating interval (big. 7). In both species the OSR remained relatively constant for large parts of the season. The medians (upper/lower estimate for the ratio males to females ready to mate: 2.95/1.19 in P. veluchianus; 2.22 0.88 in P. affinis) were very low, comparable to that in explosive breeding frog species. Thus in the bushcricket mating system, females may be able to demand large male mating efforts so that the operational sex ratio can come close to unity.     

Exploration of the Arrest Peptide Sequence Space Reveals Arrest-enhanced Variants

Translational arrest peptides (APs) are short stretches of polypeptides that induce translational stalling when synthesized on a ribosome. Mechanical pulling forces acting on the nascent chain can weaken or even abolish stalling. APs can therefore be used as in vivo force sensors, making it possible to measure the forces that act on a nascent chain during translation with single-residue resolution. It is also possible to score the relative strengths of APs by subjecting them to a given pulling force and ranking them according to stalling efficiency. Using the latter approach, we now report an extensive mutagenesis scan of a strong mutant variant of the Mannheimia succiniciproducens SecM AP and identify mutations that further increase the stalling efficiency. Combining three such mutations, we designed an AP that withstands the strongest pulling force we are able to generate at present. We further show that diproline stretches in a nascent protein act as very strong APs when translation is carried out in the absence of elongation factor P. Our findings highlight critical residues in APs, show that certain amino acid sequences induce very strong translational arrest and provide a toolbox of APs of varying strengths that can be used for in vivo force measurements.     

High-Frequency Stimulation of the Subthalamic Nucleus Counteracts Cortical Expression of Major Histocompatibility Complex Genes in a Rat Model of Parkinson’s Disease

High-frequency stimulation of the subthalamic nucleus (STN-HFS) is widely used as therapeutic intervention in patients suffering from advanced Parkinson’s disease. STN-HFS exerts a powerful modulatory effect on cortical motor control by orthodromic modulation of basal ganglia outflow and via antidromic activation of corticofugal fibers. However, STN-HFS-induced changes of the sensorimotor cortex are hitherto unexplored. To address this question at a genomic level, we performed mRNA expression analyses using Affymetrix microarray gene chips and real-time RT-PCR in sensorimotor cortex of parkinsonian and control rats following STN-HFS. Experimental parkinsonism was induced in Brown Norway rats by bilateral nigral injections of 6-hydroxydopamine and was assessed histologically, behaviorally, and electrophysiologically. We applied prolonged (23h) unilateral STN-HFS in awake and freely moving animals, with the non-stimulated hemisphere serving as an internal control for gene expression analyses. Gene enrichment analysis revealed strongest regulation in major histocompatibility complex (MHC) related genes. STN-HFS led to a cortical downregulation of several MHC class II (RT1-Da, Db1, Ba, and Cd74) and MHC class I (RT1CE) encoding genes. The same set of genes showed increased expression levels in a comparison addressing the effect of 6-hydroxydopamine lesioning. Hence, our data suggest the possible association of altered microglial activity and synaptic transmission by STN-HFS within the sensorimotor cortex of 6-hydroxydopamine treated rats.     

Comparative Study on Plant Latex Particles and Latex Coagulation in Ficus benjamina,Campanula glomerata and Three Euphorbia species

Among latex-producing plants, mainly the latex of Hevea brasiliensis has been studied in detail so far, while comprehensive comparative studies of latex coagulation mechanisms among the more than 20,000 latex-bearing plant species are lacking. In order to give new insights into the potential variety of coagulation mechanisms, the untreated natural latices of five latex-bearing plants from the families Euphorbiaceae, Moraceae and Campanulaceae were visualised using Cryo-SEM and their particle size compared using the laser diffraction method. Additionally, the laticifers of these plants species were examined in planta via Cryo-SEM. Similar latex particle sizes and shape were found in Ficus benjamina and Hevea brasiliensis. Hence, and due to other similarities, we hypothesize comparable, mainly chemical, coagulation mechanisms in these two species, whereas a physical coagulation mechanism is proposed for the latex of Euphorbia spp. The latter mechanism is based on the huge amount of densely packed particles that after evaporation of water build a large surface area, which accelerates the coagulation procedure.     

An Individual Patient Data Meta-Analysis on Characteristics and Outcome of Patients with Papillary Glioneuronal Tumor,Rosette Glioneuronal Tumor with Neuropil-Like Islands and Rosette Forming Glioneuronal Tumor of the Fourth Ventricle

Background and Purpose

In 2007, the WHO classification of brain tumors was extended by three new entities of glioneuronal tumors: papillary glioneuronal tumor (PGNT), rosette-forming glioneuronal tumor of the fourth ventricle (RGNT) and glioneuronal tumor with neuropil-like islands (GNTNI). Focusing on clinical characteristics and outcome, the authors performed a comprehensive individual patient data (IPD) meta-analysis of the cases reported in literature until December 2012.

Methods

PubMed, Embase and Web of Science were searched for peer-reviewed articles reporting on PGNT, RGNT, and GNTNI using predefined keywords.

Results

95 publications reported on 182 patients (PGNT, 71; GNTNI, 26; RGNT, 85). Median age at diagnosis was 23 years (range 4–75) for PGNT, 27 years (range 6–79) for RGNT, and 40 years (range 2–65) for GNTNI. Ninety-seven percent of PGNT and 69% of GNTNI were located in the supratentorial region, 23% of GNTNI were in the spinal cord, and 80% of RGNT were localized in the posterior fossa. Complete resection was reported in 52 PGNT (73%), 36 RGNT (42%), and 7 GNTNI (27%) patients. Eight PGNT, 3 RGNT, and 12 GNTNI patients were treated with chemo- and/or radiotherapy as the primary postoperative treatment. Follow-up data were available for 132 cases. After a median follow-up time of 1.5 years (range 0.2–25) across all patients, 1.5-year progression-free survival rates were 52±12% for GNTNI, 86±5% for PGNT, and 100% for RGNT. The 1.5-year overall-survival were 95±5%, 98±2%, and 100%, respectively.

Conclusions

The clinical understanding of the three new entities of glioneuronal tumors, PGNT, RGNT and GNTNI, is currently emerging. The present meta-analysis will hopefully contribute to a delineation of their diagnostic, therapeutic, and prognostic profiles. However, the available data do not provide a solid basis to define the optimum treatment approach. Hence, a central register should be established.     

A phosphorylation-regulated brake mechanism controls the initial endocytosis of opioid receptors but is not required for post-endocytic sorting to lysosomes.

The delta-opioid receptor (DOR) can undergo proteolytic down-regulation by endocytosis of receptors followed by sorting of internalized receptors to lysosomes. Although phosphorylation of the receptor is thought to play an important role in controlling receptor down-regulation, previous studies disagree on whether phosphorylation is actually required for the agonist-induced endocytosis of opioid receptors. Furthermore, no previous studies have determined whether phosphorylation is required for subsequent sorting of internalized receptors to lysosomes. We have addressed these questions by examining the endocytic trafficking of a series of mutant versions of DOR expressed in stably transfected HEK 293 cells. Our results confirm that phosphorylation is not required for agonist-induced endocytosis of truncated mutant receptors that lack the distal carboxyl-terminal cytoplasmic domain containing sites of regulatory phosphorylation. However, phosphorylation is required for endocytosis of full-length receptors. Mutation of all serine/threonine residues located in the distal carboxyl-terminal tail domain of the full-length receptor to alanine creates functional mutant receptors that exhibit no detectable agonist-induced endocytosis. Substitution of these residues with aspartate restores the ability of mutant receptors to undergo agonist-induced endocytosis. Studies using green fluorescent protein-tagged versions of arrestin-3 suggest that the distal tail domain, when not phosphorylated, inhibits receptor-mediated recruitment of beta-arrestins to the plasma membrane. Biochemical and radioligand binding studies indicate that, after endocytosis occurs, phosphorylation-defective mutant receptors traffic to lysosomes with similar kinetics as wild type receptors. We conclude that phosphorylation controls endocytic trafficking of opioid receptors primarily by regulating a "brake" mechanism that prevents endocytosis of full-length receptors in the absence of phosphorylation. After endocytosis occurs, subsequent steps of membrane trafficking mediating sorting and transport to lysosomes do not require receptor phosphorylation.     

Life-cycle modification in open oceans accounts for genome variability in a cosmopolitan phytoplankton

Emiliania huxleyi is the most abundant calcifying plankton in modern oceans with substantial intraspecific genome variability and a biphasic life cycle involving sexual alternation between calcified 2N and flagellated 1N cells. We show that high genome content variability in Emiliania relates to erosion of 1N-specific genes and loss of the ability to form flagellated cells. Analysis of 185 E. huxleyi strains isolated from world oceans suggests that loss of flagella occurred independently in lineages inhabiting oligotrophic open oceans over short evolutionary timescales. This environmentally linked physiogenomic change suggests life cycling is not advantageous in very large/diluted populations experiencing low biotic pressure and low ecological variability. Gene loss did not appear to reflect pressure for genome streamlining in oligotrophic oceans as previously observed in picoplankton. Life-cycle modifications might be common in plankton and cause major functional variability to be hidden from traditional taxonomic or molecular markers.