REGULATION OF AMYLASE,CELLULASE AND CHITINASE SECRETION IN THE DIGESTIVE TRACT OF THE TWO‐SPOTTED FIELD CRICKET,Gryllus bimaculatus

The secretion of amylase and cellulase in Gryllus bimaculatus is determined by increased food intake, whereby shortly after molting food consumption increases. About half of the standing amylase concentration (activity) in the endothelial cells can be secreted within 30 min. The peak of amylase and cellulase secretion that occurs in the photophase is related to the feeding peak in the previous scotophase. The secretion of chitinase on the other hand is primarily controlled by the molting cycle. Only amylase secretion was affected by calcium in the incubation medium, suggesting an apocrine release mechanism. Refeeding experiments (after 5 days without food) suggest that the release of amylase in response to a nutrient in the lumen (glucose) is not due to simple stimulation of exocytosis, but rather a stimulation of synthesis.     

Molecular weight distribution and functional group profiles of TEMPO-oxidized lyocell fibers

The effects of TEMPO-mediated oxidation, performed with NaClO, a catalytic amount of NaBr, and 2,2′,6,6′-tetramethylpiperidine-1-oxy radical (TEMPO), were studied on lyocell fibers by means of GPC using multiple detection and group-selective fluorescence labeling according to the CCOA and FDAM methodology. The applied method determines functional group content as a sum parameter, as well as functional group profiles in relation to the molecular weight of the cellulose fibers. Both the CHO and COOH profiles, as well as molecular weight alterations, were analyzed. A significant decrease in the average molecular weight was obtained during the first hour of TEMPO-mediated oxidation, but prolonged oxidation time resulted in no strong additional chain scission. Significant amounts of COOH groups were introduced in the high molecular weight fractions by the oxidation with higher concentrations of NaClO (2.42–9.67 mmol NaClO/g fiber) after modification times of 1 h or longer.     

Switching the Clientele: A LYSINE RESIDING IN THE C TERMINUS OF THE SEROTONIN TRANSPORTER SPECIFIES ITS PREFERENCE FOR THE COAT PROTEIN COMPLEX II COMPONENT SEC24C*

The serotonin transporter (SERT) maintains serotonergic neurotransmission via rapid reuptake of serotonin from the synaptic cleft. SERT relies exclusively on the coat protein complex II component SEC24C for endoplasmic reticulum (ER) export. The closely related transporters for noradrenaline and dopamine depend on SEC24D. Here, we show that discrimination between SEC24C and SEC24D is specified by the residue at position +2 downstream from the ER export motif (⁶⁰⁷RI⁶⁰⁸ in SERT). Substituting Lys⁶¹⁰ with tyrosine, the corresponding residue found in the noradrenaline and dopamine transporters, switched the SEC24 isoform preference: SERT-K610Y relied solely on SEC24D to reach the cell surface. This analysis was extended to other SLC6 (solute carrier 6) transporter family members: siRNA-dependent depletion of SEC24C, but not of SEC24D, reduced surface levels of the glycine transporter-1a, the betaine/GABA transporter and the GABA transporter-4. Experiments with dominant negative versions of SEC24C and SEC24D recapitulated these findings. We also verified that the presence of two ER export motifs (in concatemers of SERT and GABA transporter-1) supported recruitment of both SEC24C and SEC24D. To the best of our knowledge, this is the first report to document a change in SEC24 specificity by mutation of a single residue in the client protein. Our observations allowed for deducing a rule for SLC6 family members: a hydrophobic residue (Tyr or Val) in the +2 position specifies interaction with SEC24D, and a hydrophilic residue (Lys, Asn, or Gln) recruits SEC24C. Variations in SEC24C are linked to neuropsychiatric disorders. The present findings provide a mechanistic explanation. Variations in SEC24C may translate into distinct surface levels of neurotransmitter transporters.     

Characterization of the Interaction between the Chlamydial Adhesin OmcB and the Human Host Cell

In a previous study, we reported that the OmcB protein from Chlamydia pneumoniae mediates adhesion of the infectious elementary body to human HEp-2 cells by interacting with heparin/heparan sulfate-like glycosaminoglycans (GAGs) via basic amino acids located in the first of a pair of XBBXBX heparin-binding motifs (K. Moelleken and J. H. Hegemann, Mol. Microbiol. 67:403–419, 2008). In the present study, we show that the basic amino acid at position 57 (arginine) in the first XBBXBX motif, the basic amino acid at position 61 (arginine) in the second motif, and another amino acid (lysine 69) C terminal to it play key roles in the interaction. In addition, we show that discrimination between heparin-dependent and -independent adhesion by C. trachomatis OmcBs is entirely dependent on three variable amino acids in the so-called variable domain C terminal to the conserved XBBXBX motif. Here, the predicted conformational change in the secondary structure induced by the proline at position 66 seems to be crucial for heparin recognition. Finally, we performed neutralization experiments using different anti-heparan sulfate antibodies to gain insight into the nature of the GAGs recognized by OmcB. The results suggest that C. trachomatis serovar L2 OmcB interacts with 6-O-sulfated domains of heparan sulfate, while C. pneumoniae OmcB apparently interacts with domains of heparan sulfate harboring a diverse subset of O-sulfations.     

Diversionary feeding and nestling diet of Hen Harriers Circus cyaneus

Capsule: Diversionary feeding reduced Hen Harrier Circus cyaneus nestlings’ natural food intake by half. Red Grouse Lagopus lagopus scotica chicks constituted 0–4% of all nestling food items. Annually, this reduced annual grouse chick production by 0–6%.

Aim: To quantify proportions of diversionary and natural food (including grouse) delivered to Hen Harrier nestlings in relation to brood size, male status and natural prey abundance.

Methods: We recorded diversionary food provisioned to 25 Hen Harrier broods (2008–15) and studied the diet of 15 broods using observations from hides, nest cameras and regurgitated pellet analysis. Variation in nestling diet was analysed using compositional analysis.

Results: Hen Harriers took 76% of diversionary food provided. Depending on assessment method, average nestling diet was 44–53% diversionary food, 39–55% natural prey (including 24–45% passerines, 4–15% small mammals, 0–4% grouse chicks) and 0–9% unknown items. The amount of diversionary food consumed was not influenced by male status, brood size or natural prey abundance. The number of Red Grouse chicks delivered annually was 34–100% lower than expected under unfed conditions, however, the confidence intervals associated with these estimates were large.

Conclusion: Diversionary food influenced Hen Harrier nestling diet and reduced the number of Red Grouse chicks taken relative to modelled predictions. It may help reduce conflict between Hen Harrier conservation and Red Grouse shooting, but only if overall grouse productivity is thereby maintained or increased.     

Meta-analysis of Gene-Level Associations for Rare Variants Based on Single-Variant Statistics

Meta-analysis of genome-wide association studies (GWASs) has led to the discoveries of many common variants associated with complex human diseases. There is a growing recognition that identifying “causal” rare variants also requires large-scale meta-analysis. The fact that association tests with rare variants are performed at the gene level rather than at the variant level poses unprecedented challenges in the meta-analysis. First, different studies may adopt different gene-level tests, so the results are not compatible. Second, gene-level tests require multivariate statistics (i.e., components of the test statistic and their covariance matrix), which are difficult to obtain. To overcome these challenges, we propose to perform gene-level tests for rare variants by combining the results of single-variant analysis (i.e., p values of association tests and effect estimates) from participating studies. This simple strategy is possible because of an insight that multivariate statistics can be recovered from single-variant statistics, together with the correlation matrix of the single-variant test statistics, which can be estimated from one of the participating studies or from a publicly available database. We show both theoretically and numerically that the proposed meta-analysis approach provides accurate control of the type I error and is as powerful as joint analysis of individual participant data. This approach accommodates any disease phenotype and any study design and produces all commonly used gene-level tests. An application to the GWAS summary results of the Genetic Investigation of ANthropometric Traits (GIANT) consortium reveals rare and low-frequency variants associated with human height. The relevant software is freely available.     

Great tits provided with ad libitum food lay larger eggs when exposed to colder temperatures

The amount of nutrients deposited into a bird egg varies both between and within clutches of the same female. Larger eggs enhance offspring traits, but as a tradeoff, laying large eggs also infers energetic costs to the female. Income breeders usually lay larger eggs later in the season, when temperatures and food availability are higher. Egg size is thus affected by the daily amount of energy available to produce an egg under cold conditions, but it is less well known in how far temperature exerts direct effects on egg size. We show that great tit females Parus major with access to ad libitum food and breeding in climate‐controlled aviaries varied their egg investments. The size of an individual egg was best predicted by mean temperatures one week pre‐laying, with females laying larger, rather than smaller, eggs under colder conditions. Eggs increased in size over the season, but not significantly over the laying sequence. The degree of daily temperature fluctuation did not influence egg size. In addition to a substantial between‐female variation, sisters were more similar to each other than unrelated females, showing that egg size does also reflect heritable intrinsic female properties. Natural variation in egg size is thus not only determined by energy‐limitation, but also due to females allocating more resources to eggs laid in colder environments, thus increasing early survival of the chicks. That the positive correlation between temperature and egg investments that is found in a natural population is reversed under ad libitum food conditions demonstrates that wild great tits tradeoff own condition with survival prospects of their chicks as a function of available food, not ambient temperature.     

Germline Mutations in the Polyposis-Associated Genes BMPR1A,SMAD4, PTEN,MUTYH and GREM1 Are Not Common in Individuals with Serrated Polyposis Syndrome

Background

Recent reports have observed that individuals with serrated polyps, some of whom meet the clinical diagnostic criteria for Serrated Polyposis Syndrome (SPS), are among those who carry germline mutations in genes associated with polyposis syndromes including; (1) genes known to underlie hamartomatous polyposes (SMAD4, BMPR1A, and PTEN), (2) MUTYH-associated polyposis and (3) GREM1 in Hereditary Mixed Polyposis Syndrome (HMPS). The aim of this study was to characterise individuals fulfilling the current WHO criteria for SPS for germline mutations in these polyposis-associated genes.

Methods

A total of 65 individuals with SPS (fulfilling WHO criteria 1 or 3), were recruited to the Genetics of Serrated Neoplasia study between 2000 and 2012, through multiple Genetics or Family Cancer Clinics within Australia, or from the New Zealand Familial Gastrointestinal Cancer Service. Individuals with SPS were tested for coding mutations and large deletions in the PTEN, SMAD4, and BMPR1A genes, for the MUTYH variants in exons 7 (Y179C) and 13 (G396D), and for the duplication upstream of GREM1.

Results

We found no variants that were likely to be deleterious germline mutations in the SPS cases in the PTEN, SMAD4, and BMPR1A genes. A novel variant in intron 2 (c.164+223T>C) of PTEN was identified in one individual and was predicted by in silico analysis to have no functional consequences. One further individual with SPS was found to be mono-allelic for the MUTYH G396D mutation. No individuals carried the recently reported duplication within GREM1.

Conclusions

Genes involved in the gastrointestinal hamartomatous polyposis, Hereditary Mixed Polyposis Syndrome and MUTYH-associated polyposis syndromes are not commonly altered in individuals with SPS.