Muskoxen in the high Arctic-temporal and spatial differences in body size

The life history of ungulates is affected by factors such as climate, population density and resource availability. With focus on the muskoxen Ovibos moschatus living in Kangerlussuaq in western Greenland, Jameson Land in north-eastern Greenland and on Banks and Victoria Islands in northern Canada, we tested spatial variation in life-history traits measured by mandibular growth. In accordance with expectations, we found that muskoxen in the southernmost and low Arctic area (Kangerlussuaq) grew faster, matured earlier, reproduced earlier, reached larger adult size and additionally had a higher reproduction than muskoxen living in the more northern areas. In the Kangerlussuaq population, mandible lengths in adult males changed temporally with density, with significant smaller adult males present in high population densities in western Greenland. It was especially the male mandible lengths that responded to environmental factors. In females, spatial differences were less pronounced than in males and is probably explained by females facing a trade-off between investment in own growth and reproduction, whereas a large body size is more important for the males, which are exposed to sexual selection. This explanation was, furthermore, supported by the fact that the calf percentage was higher in western Greenland than in any of the other studied areas in spite of the density-dependent effects detected within the male gender.     

Evolution of sperm structure and energetics in passerine birds

Spermatozoa exhibit considerable interspecific variability in size and shape. Our understanding of the adaptive significance of this diversity, however, remains limited. Determining how variation in sperm structure translates into variation in sperm performance will contribute to our understanding of the evolutionary diversification of sperm form. Here, using data from passerine birds, we test the hypothesis that longer sperm swim faster because they have more available energy. We found that sperm with longer midpieces have higher levels of intracellular adenosine triphosphate (ATP), but that greater energy reserves do not translate into faster-swimming sperm. Additionally, we found that interspecific variation in sperm ATP concentration is not associated with the level of sperm competition faced by males. Finally, using Bayesian methods, we compared the evolutionary trajectories of sperm morphology and ATP content, and show that both traits have undergone directional evolutionary change. However, in contrast to recent suggestions in other taxa, we show that changes in ATP are unlikely to have preceded changes in morphology in passerine sperm. These results suggest that variable selective pressures are likely to have driven the evolution of sperm traits in different taxa, and highlight fundamental biological differences between taxa with internal and external fertilization, as well as those with and without sperm storage.     

Chemotaxonomic discrimination among the fungal genera Tolypocladium, beauveria and Paecilomyces

Fungi of the genera Beauveria and Paecilomyces were found to produce cyclotetradepsipeptides, beauverolides. Production of beauverolides was not detected at the genus Tolypocladium. Analysis of beauverolides therefore provides a very simple chemotaxonomic test which seems to be suitable for fast discrimination between the genera Beauveria vs Tolypocladium and complementing morphological examination. A GC-MS study of β-hydroxy acid distribution in the beauverolide hydrolyzates revealed that all strains prdouce γ-methyl-β-hydroxy acids only. Their occurrence thus cannot be used as a taxonomic marker of different species within the genera Beauveria and Paecilomyces.     

Endophytic Colonisation of Opium Poppy, Papaver somniferum, by an Entomopathogenic Beauveria bassiana Strain

Beauveria bassiana strain EABb 04/01-Tip isolated from stem-borer larvae of Timaspis papaveris (Hymenoptera: Cynipidae), a serious pest of opium poppy in Spain, was shown to be able to become established endophytically in this pharmaceutical crop. Microbiological, molecular and light and electron microscopic methods were used to study fungal colonisation and to describe its mode of penetration. After inoculation with a foliar spray of conidia, microbiological methods showed 100% of plants examined 24, 48, 72 and 144 h after treatment to be colonised endophytically by the fungus, although the percentage of previously surface sterilised leaf pieces showing fungal growth was 100% at 24 and 48 h, and 80 and 75% at 72 and 144 h after treatment, respectively. The fungus was also observed in leaf pieces obtained from newly formed leaves, indicating that it could spread from treated leaves to leaves formed after fungal application. For molecular studies, a polymerase chain reaction (PCR) protocol was used to amplify the ITS1-5.8S-ITS2 regions of the rDNA of the plant and the fungus. This procedure allowed the detection of the fungus on the surface of the leaves and also endophytically, but only at 72 h after treatment. A nucleotide BLAST search revealed that the ITS1-5.8S-ITS2 sequence of strain EABb 04/01-Tip showed 100% homology with a similar sequence from Cordyceps bassiana. SEM images revealed that although numerous conidia were observed on the leaf surface, few germinated and penetrated. Intracellular colonisation by B. bassiana was not observed, but hyphae were detected growing into the xylem vessels. The fungus was found to colonise 40.5 ± 4.3% of seedlings (with two cotyledons and the two first real leaves) from seeds dressed with a fungal spore suspension. These results may have implications in the biological control of T. papaveris, including the possible systemic protection of the plant against this cynipid.     

Population characteristics predict responses in moose body mass to temporal variation in the environment

1. A general problem in population ecology is to predict under which conditions stochastic variation in the environment has the stronger effect on ecological processes. By analysing temporal variation in a fitness-related trait, body mass, in 21 Norwegian moose Alces alces (L.) populations, we examined whether the influence of temporal variation in different environmental variables were related to different parameters that were assumed to reflect important characteristics of the fundamental niche space of the moose. 2. Body mass during autumn was positively related to early access to fresh vegetation in spring, and to variables reflecting slow phenological development (low June temperature, a long spring with a slow plant progression during spring). In contrast, variables related to food quantity and winter conditions had only a minor influence on temporal variation in body mass. 3. The magnitude of the effects of environmental variation on body mass was larger in populations with small mean body mass or living at higher densities than in populations with large-sized individuals or living at lower densities. 4. These results indicate that the strongest influence of environmental stochasticity on moose body mass occurs towards the borders of the fundamental niche space, and suggests that populations living under good environmental conditions are partly buffered against fluctuations in environmental conditions.     

Phylogenetic footprinting of non-coding RNA: hammerhead ribozyme sequences in a satellite DNA family of <Emphasis Type="Italic">Dolichopoda</Emphasis>cave crickets (Orthoptera,Rhaphidophoridae)

Background  

The great variety in sequence, length, complexity, and abundance of satellite DNA has made it difficult to ascribe any function to this genome component. Recent studies have shown that satellite DNA can be transcribed and be involved in regulation of chromatin structure and gene expression. Some satellite DNAs, such as the pDo500 sequence family in Dolichopoda cave crickets, have a catalytic hammerhead (HH) ribozyme structure and activity embedded within each repeat.     

DNA sequence profiles of the colorectal cancer critical gene set KRAS-BRAF-PIK3CA-PTEN-TP53 related to age at disease onset

The incidence of colorectal cancer (CRC) increases with age and early onset indicates an increased likelihood for genetic predisposition for this disease. The somatic genetics of tumor development in relation to patient age remains mostly unknown. We have examined the mutation status of five known cancer critical genes in relation to age at diagnosis, and compared the genomic complexity of tumors from young patients without known CRC syndromes with those from elderly patients. Among 181 CRC patients, stratified by microsatellite instability status, DNA sequence changes were identified in KRAS (32%), BRAF (16%), PIK3CA (4%), PTEN (14%) and TP53 (51%). In patients younger than 50 years (n = 45), PIK3CA mutations were not observed and TP53 mutations were more frequent than in the older age groups. The total gene mutation index was lowest in tumors from the youngest patients. In contrast, the genome complexity, assessed as copy number aberrations, was highest in tumors from the youngest patients. A comparable number of tumors from young (<50 years) and old patients (>70 years) was quadruple negative for the four predictive gene markers (KRAS-BRAF-PIK3CA-PTEN); however, 16% of young versus only 1% of the old patients had tumor mutations in PTEN/PIK3CA exclusively. This implies that mutation testing for prediction of EGFR treatment response may be restricted to KRAS and BRAF in elderly (>70 years) patients. Distinct genetic differences found in tumors from young and elderly patients, whom are comparable for known clinical and pathological variables, indicate that young patients have a different genetic risk profile for CRC development than older patients.