Explaining annual fluctuations in breeding density of fieldfares Turdus pilaris– combined influences of factors operating during breeding, migration and wintering

In a subalpine birch forest in Central Norway, the breeding population of fieldfare Turdus pilaris varied from 3 to 63 pairs per km² during 1966–2000. For the period 1971–1995, the breeding density was negatively related to the number of days with >75% snow covered ground in April, presumably because snow cover reduce the availability of earthworms. In a multiple regression model for the period 1974–1995, snow cover in spring, the number of migrating fieldfares observed at two ornithological stations at the southern coast of Norway in April, the mean temperature in November in the preceding year, winter temperatures, rowanberry production in the previous autumn, and the interaction effect of the two latter variables (high value of one of these variables reduced the negative effect of a low value of the other) explained 80% of the variation in fieldfare breeding density. Autumn and winter temperatures, as well as rowanberry production, contributed through a positive effect, probably because these factors affected the number of fieldfare present in Norway throughout winter, which in some years may constitute a significant proportion of the overall fieldfare population.     

Molecular Evidence that Only Two Opsin Subfamilies,the Blue Light- (SWS2) and Green Light-Sensitive (RH2), Drive Color Vision in Atlantic Cod (Gadus morhua)

Teleosts show a great variety in visual opsin complement, due to both gene duplication and gene loss. The repertoire ranges from one subfamily of visual opsins (scotopic vision) including rod opsin only retinas seen in many deep-sea species to multiple subfamilies of visual opsins in some pelagic species. We have investigated the opsin repertoire of Atlantic cod (Gadus morhua) using information in the recently sequenced cod genome and found that despite cod not being a deep sea species it lacks visual subfamilies sensitive towards the most extreme parts of the light spectra representing UV and red light. Furthermore, we find that Atlantic cod has duplicated paralogs of both blue-sensitive SWS2 and green-sensitive RH2 subfamilies, with members belonging to each subfamily linked in tandem within the genome (two SWS2-, and three RH2A genes, respectively). The presence of multiple cone opsin genes indicates that there have been duplication events in the cod ancestor SWS2 and RH2 opsins producing paralogs that have been retained in Atlantic. Our results are supported by expressional analysis of cone opsins, which further revealed an ontogenetic change in the array of cone opsins expressed. These findings suggest life stage specific programs for opsin regulation which could be linked to habitat changes and available light as the larvae is transformed into an early juvenile. Altogether we provide the first molecular evidence for color vision driven by only two families of cone opsins due to gene loss in a teleost.     

A role for glutamate transporters in the regulation of insulin secretion

In the brain, glutamate is an extracellular transmitter that mediates cell-to-cell communication. Prior to synaptic release it is pumped into vesicles by vesicular glutamate transporters (VGLUTs). To inactivate glutamate receptor responses after release, glutamate is taken up into glial cells or neurons by excitatory amino acid transporters (EAATs). In the pancreatic islets of Langerhans, glutamate is proposed to act as an intracellular messenger, regulating insulin secretion from β-cells, but the mechanisms involved are unknown. By immunogold cytochemistry we show that insulin containing secretory granules express VGLUT3. Despite the fact that they have a VGLUT, the levels of glutamate in these granules are low, indicating the presence of a protein that can transport glutamate out of the granules. Surprisingly, in β-cells the glutamate transporter EAAT2 is located, not in the plasma membrane as it is in brain cells, but exclusively in insulin-containing secretory granules, together with VGLUT3. In EAAT2 knock out mice, the content of glutamate in secretory granules is higher than in wild type mice. These data imply a glutamate cycle in which glutamate is carried into the granules by VGLUT3 and carried out by EAAT2. Perturbing this cycle by knocking down EAAT2 expression with a small interfering RNA, or by over-expressing EAAT2 or a VGLUT in insulin granules, significantly reduced the rate of granule exocytosis. Simulations of granule energetics suggest that VGLUT3 and EAAT2 may regulate the pH and membrane potential of the granules and thereby regulate insulin secretion. These data suggest that insulin secretion from β-cells is modulated by the flux of glutamate through the secretory granules.     

NT-proBNP independently predicts long term mortality after acute exacerbation of COPD – a prospective cohort study

Background

Cardiovascular disease is prevalent and frequently unrecognized in patients with chronic obstructive pulmonary disease (COPD). NT-proBNP is an established risk factor in patients with heart failure. NT-proBNP may also be released from the right ventricle. Thus serum NT-proBNP may be elevated during acute exacerbations of COPD (AECOPD). The prognostic value of NT-proBNP in patients hospitalized with AECOPD is sparsely studied. Our objective was to test the hypothesis that NT-proBNP independently predicts long term mortality following AECOPD.

Methods

A prospective cohort study of 99 patients with 217 admissions with AECOPD. Clinical, electrocardiographic, radiological and biochemical data were collected at index and repeat admissions and analyzed in an extended survival analysis with time-dependent covariables.

Results

Median follow-up time was 1.9 years, and 57 patients died during follow-up. NT-proBNP tertile limits were 264.4 and 909 pg/mL, and NT-proBNP in tertiles 1 through 3 was associated with mortality rates of 8.6, 35 and 62 per 100 patient-years, respectively (age-adjusted log-rank p<0.0001). After adjustment for age, gender, peripheral edema, cephalization and cTnT in a multivariable survival model, the corresponding hazard ratios for dying were 2.4 (0.95-6.0) and 3.2 (1.3-8.1) (with 95% confidence intervals in parentheses, p-value for trend 0.013).

Conclusions

NT-proBNP is a strong and independent determinant of mortality after AECOPD.     

Gene-based analysis of regionally enriched cortical genes in GWAS data sets of cognitive traits and psychiatric disorders

Background

Despite its estimated high heritability, the genetic architecture leading to differences in cognitive performance remains poorly understood. Different cortical regions play important roles in normal cognitive functioning and impairment. Recently, we reported on sets of regionally enriched genes in three different cortical areas (frontomedial, temporal and occipital cortices) of the adult rat brain. It has been suggested that genes preferentially, or specifically, expressed in one region or organ reflect functional specialisation. Employing a gene-based approach to the analysis, we used the regionally enriched cortical genes to mine a genome-wide association study (GWAS) of the Norwegian Cognitive NeuroGenetics (NCNG) sample of healthy adults for association to nine psychometric tests measures. In addition, we explored GWAS data sets for the serious psychiatric disorders schizophrenia (SCZ) (n = 3 samples) and bipolar affective disorder (BP) (n = 3 samples), to which cognitive impairment is linked.

Principal Findings

At the single gene level, the temporal cortex enriched gene RAR-related orphan receptor B (RORB) showed the strongest overall association, namely to a test of verbal intelligence (Vocabulary, P = 7.7E-04). We also applied gene set enrichment analysis (GSEA) to test the candidate genes, as gene sets, for enrichment of association signal in the NCNG GWAS and in GWASs of BP and of SCZ. We found that genes differentially expressed in the temporal cortex showed a significant enrichment of association signal in a test measure of non-verbal intelligence (Reasoning) in the NCNG sample.

Conclusion

Our gene-based approach suggests that RORB could be involved in verbal intelligence differences, while the genes enriched in the temporal cortex might be important to intellectual functions as measured by a test of reasoning in the healthy population. These findings warrant further replication in independent samples on cognitive traits.     

Moth outbreaks in relation to oak masting and population levels of small mammals: an alternative explanation to the mammal-predation hypothesis

The relationship between population outbreaks of the gypsy moth (Lymantria dispar) and oak masting in North America has been interpreted as an effect of reduced predation on moth pupae from small mammals after years of acorn failure. However, moth defoliation could be a consequence of high acorn production rather than of acorn failure, as all moth outbreaks in two time series presented by Liebhold et al. [Popul Ecol (2000) 42:257–266] were reported shortly after mast years. A similar pattern has been found for the green oak leaf roller moth (Tortrix viridana) in southern Norway. Because predation from small mammals should be less important for the latter species, I argue that the acorn-moth relationships are most likely caused by mast-induced changes in the chemical composition of oak leaves. Given the high number of eggs laid by each moth female, there is a huge potential for population growth in or shortly after a mast year if larval survival is no longer limited by low food quality.     

The phylogeny of orthoretroviral long terminal repeats (LTRs)

LTRs are sequence elements in retroviruses and retrotransposons which are difficult to align due to their variability. One way of handling such cases is to use Hidden Markov Models (HMMs). In this work HMMs of LTRs were constructed for three groups of orthoretroviruses: the betaretroviruslike human MMTV-like (HML) endogenous retroviruses, the lentiviruses, including HIV, and gammaretroviruslike human endogenous retroviruses (HERVs). The HMM-generated LTR alignments and the phylogenetic trees constructed from them were compared with trees based on alignments of the pol gene at the nucleic acid level. The majority of branches in the LTR and pol based trees had the same order for the three retroviral genera, showing that HMM methods are successful in aligning and constructing phylogenies of LTRs. The HML LTR tree deviated somewhat from the pol tree for the groups HML3, HML7 and HML6. Among the gammaretroviruslike proviruses, the exogenous Mouse Leukemia Virus (MLV) was highly related to HERV-T in the pol based tree, but not in the LTR based tree. Aside from these differences, the similarity between the trees indicates that LTRs and pol coevolved in a largely monophyletic way.     

Female turnover rate differs between two Northern Goshawk Accipiter gentilis nesting areas,as revealed by DNA analysis of moulted feathers

The turnover rate of breeding Northern Goshawk Accipiter gentilis females in two study areas in southern Norway, which are assumed to experience different levels of illegal human persecution, was estimated using DNA extracted from moulted feathers, along with other characteristics. Female turnover rate over a 4‐year period for each nesting territory during 1990–2015 was significantly higher in Aust‐Agder County (31.9%; 23 territories), where hunters have long shown antipathy to Goshawks, than in Telemark County (17.3%; 25 territories). Turnover rate was not related to territory quality. The proportion of successful nesting attempts was lower in Aust‐Agder (70–75%) than in Telemark (82–84%), but for newly built nests, which are less likely to be known by hunters, the difference was not significant (77.4 vs 79.6%). The proportion of juvenile female Goshawks among recruits and in the total breeding population also did not differ between the two areas. Our findings support the notion that Goshawk persecution was higher in Aust‐Agder than in Telemark. We found that the use of phenotypic characteristics for individual recognition was successful in 96.2% of 130 comparisons of female Goshawks from two consecutive nesting attempts, when assessed using genetic markers.     

Immunogold quantification of amino acids and proteins in complex subcellular compartments

An increasing number of imaging techniques are in use to study the localization of molecules involved in cell-to-cell signaling. Here we describe the use of immunogold procedures to detect and quantify molecules on electron micrographs. To measure the areas of the subcellular compartments under investigation, the protocol uses an overlay screen with an array of regularly spaced points. On the basis of this, the densities of the gold-labeled molecules can be calculated. Despite the limited lateral resolution of the immunogold method as used by many investigators ( approximately 30 nm), it is possible to measure the content of molecules associated with tiny tissue compartments, e.g., synaptic vesicles and different types of membrane, such as plasma membranes and vesicle membranes. The quantification protocol can be carried out without using computer programs. The entire protocol can be completed in approximately 15 d.     

Microsatellite Variation in Populations of Atlantic Salmon from North Europe

Our aim was to investigate the level of genetic differentiation in northern European populations of Atlantic salmon, to establish the genetic relationship among major salmon populations in Russia and North Norway, and to compare these to populations from the western Atlantic lineage. Samples were collected along an east—west axis, from Pechora River in Russia to Restigouche River in Quebec, Canada. A total of 439 individual salmon were collected from seven rivers (sample sizes from 50 to 84 individuals). The samples were analysed for variation at four microsatellite loci; Ssa13.37, Ssa14, Ssa171 and Ssa171. Significant differences were found between most of the European populations, and the populations from the Tana and Pechora Rivers were most distinct. The samples from the Rivers Mezenskaya Pizhma and Emtsa in Arkhangelsk oblast in Russia were not significantly different from each other in an exact test of population differences. All other river pairs were significantly different. These results confirmed the deep genetic divergence between American and European salmon populations demonstrated in earlier studies, with alleles specific to continent found in three of the microsatellites.