Phylogeographic patterns in Drosophila montana

The Drosophila virilis species group offers valuable opportunities for studying the roles of chromosomal re-arrangements and mating signals in speciation. The 13 species are divided into two subgroups, the montana and virilis 'phylads'. There is greater differentiation among species within the montana phylad in both karyotype and acoustic signals than exists among members of the virilis phylad. Drosophila montana is a divergent species which is included in the montana phylad. Here, we analyse the phylogeography of D. montana to provide a framework for understanding divergence of acoustic signals among populations. We analysed mitochondrial sequences corresponding to the cytochrome oxidase I and cytochrome oxidase II genes, as well as 16 microsatellite loci, from 108 lines of D. montana covering most of the species' range. The species shows a clear genetic differentiation between North American and Scandinavian populations. Microsatellite allele frequencies and mitochondrial DNA haplotypes gave significant FST values between populations from Canada, USA and Finland. A Bayesian analysis of population structure based on the microsatellite frequencies showed four genetically distinct groups, corresponding to these three populations plus a small sample from Japan. A network based on mitochondrial haplotypes showed two Finnish clades of very different shape and variability, and another clade with all sequences from North America and Japan. All D. montana populations showed evidence of demographic expansion but the patterns inferred by coalescent analysis differed between populations. The divergence times between Scandinavian and North American clades were estimated to range from 450,000 to 900,000 years with populations in Canada and the USA possibly representing descendants of different refugial populations. Long-term separation of D. montana populations could have provided the opportunity for differentiation observed in male signal traits, especially carrier frequency of the song, but relaxation of sexual selection during population expansion may have been necessary.     

Comparison of peptidase activities in some fungi pathogenic to arthropods

Peptidases, highly specific toward several synthetic chromogenic peptides, were found in the mycelia of four arthropod pathogenic fungi: Aphanomyces astaci, Beauveria bassiana, Metarrhizium anisopliae, and Paecilomyces farinosus. A. astaci peptidases had high hydrolyzing activities toward most of the peptides, especially those with arginine in the P1 position, while those of B. bassiana and P. farinosus readily hydrolyzed peptides with valine and arginine, as well as proline and tyrosine in the P2 and P1 positions, respectively. The hydrolyzing capacities of M. anisopliae peptidases were similar to A. astaci, but showed lower specific activities. Casein or azocoll was only hydrolyzed by A. astaci peptidases. B. bassiana and M. anisopliae had a very low hydrolyzing capacity toward casein and could not degrade azocoll. P. farinosus had no hydrolyzing activity toward casein or azocoll. Only peptidases from the crayfish pathogen A. astaci could degrade the crayfish cuticle. The peptidase preparations of A. astaci and B. bassiana hydrolyzing MeO-Suc-Arg-Pro-Tyr-pNA or Bz-Phe-Val-Arg-pNA were of the serine type. The possible importance of peptidase activity of arthropod pathogenic fungi in the infection process is discussed.     

Follistatin antagonizes transforming growth factor-beta3-induced epithelial-mesenchymal transition in vitro: implications for murine palatal development supported by microarray analysis

Abstract Epithelial–mesenchymal transition (EMT) is involved in normal embryonic development as well as in tumor progression and invasiveness. This process is also known to be a crucial step in palatogenesis during fusion of the bi-lateral palatal processes. Disruption of this step results in a cleft palate, which is among the most frequent birth defects in humans. A number of genes and encoded proteins have been shown to play a role in this developmental stage. The central role is attributed to the cytokine transforming growth factor-β3 (TGF-β3), which is expressed in the medial edge epithelium (MEE) already before the fusion process. The MEE covers the tips of the growing palatal shelves and eventually undergoes EMT or programmed cell death (apoptosis). TGF-β3 is described to induce EMT in embryonic palates. With regard to the early expression of this molecule before the fusion process, it is not well understood which mechanisms prevent the TGF-β3 producing epithelial cells from undergoing differentiation precociously. We used the murine palatal fusion to study the regulation of EMT. Specifically, we analyzed the MEE for the expression of known antagonists of TGF-β molecules using in situ hybridization and detected the gene coding for Follistatin to be co-expressed with TGF-β3. Further, we could show that Follistatin directly binds to TGF-β3 and that it completely blocks TGF-β3-induced EMT of the normal murine mammary gland (NMuMG) epithelial cell line in vitro . In addition, we analyzed the gene expression profile of NMuMG cells during TGF-β3-induced EMT by microarray hybridization, detecting strong changes in the expression of apoptosis-regulating genes.     

A novel affinity gene fusion system allowing protein A-based recovery of non-immunoglobulin gene products

The capacity to produce large amounts of protein in mammalian cells is important in several contexts, including large-scale generation of biologically useful proteins, gene therapy, and transdominant genetics in cultured cells. For transdominant genetics, retroviral vectors are especially useful for delivery of expression libraries. However, even the potent CMV promoter is often unable to stimulate single-copy production of protein beyond the 1 microM level. We have adapted the HIV2/Tat expression system to retroviral vectors to boost expression above levels attainable with CMV promoters. We show that the system produces protein levels in four cell types tested which exceed levels attained by wild-type CMV or modified CMV promoters. In one cell line, the increase is 10-fold above CMV. Coupled with a stable expressed protein, levels of about 4 microM can be produced from presumptive single-copy retroviral transductants, and 30 microM from multicopy transductants.     

Priming effect as determined by adding 14C-glucose to modified controlled composting test

The development of new biodegradable packaging materials, especially biodegradable plastics, has created a need for biodegradability testing. The European standard for controlled composting test was used in this study for assessing if the addition of a test material results in excess CO₂ production in compost. This effect, designated as the priming effect, would give an erroneous result for biodegradation, which is based on CO₂ formation from the test material. Glucose was selected as a test substrate because it is the degradation product of starch and cellulose, which are major compounds of many packaging materials. Both ¹⁴C-glucose and non-labelled glucose was applied to nine compost samples of variable stability and agefrom two weeks to 1.5 years. CO₂ and ¹⁴CO₂ evolution were measured during the incubation. Biodegradation of glucose in unstable composts (age leq6 months) was negative and ¹⁴CO₂ evolution was poor, although the respective composts without glucose produced relatively high amounts of CO₂. It was concluded that a negative priming effect was observed in unstable composts, in which glucose remained mostly non-degraded and apparently inhibited the mineralization of native organic matter in the compost. In stable composts (age 6 months), biodegradation of glucose was high and approximately equal to ¹⁴C-glucose mineralization, i.e., the composts showed no priming effect. Young composts were unsuitable for controlled composting test due to lack of stability. It is important to ensure that the compost inoculum used for the test is sufficiently stable.     

Pisolithus tinctorius promotes germination and forms mycorrhizal structures in Scots pine somatic embryos in vitro

The results of the present study show that inoculation with the ectomycorrhizal fungus Pisolithus tinctorius (Pers.) Coker and Couch potentially enhances the germination of Scots pine (Pinus sylvestris L.) somatic embryos in vitro. Stimulation by Pisolithus tinctorius was only observed in the absence of direct contact between the symbionts; mature embryos were not sufficiently robust for balanced interaction with the fungus on half-strength DCR medium. Subsequently, on MMN medium with a reduced sugar concentration, direct contact between somatic embryo-derived plants and the fungus resulted in in vitro formation of mycorrhiza. Ex vitro inoculation also improved adaptation of the somatic embryo-derived plants, even though mycorrhizal structures were not observed. The reactions to Pisolithus tinctorius varied between different Scots pine cell lines both in vitro and ex vitro.     

Characterizing genic and nongenic molecular markers: comparison of microsatellites and SNPs

The implications of transitioning to single nucleotide polymorphism (SNPs) from microsatellite markers (MSs) have been investigated in a number of population genetics studies, but the effect of genomic location on the amount of information each type of marker reveals has not been explored in detail. We developed novel SNP markers flanking 1 kb regions of 13 genic (within gene or <1 kb away from gene) and 13 nongenic (>10 kb from annotated gene) MSs in the threespine stickleback genome to obtain comparable data for both types of markers. We analysed patterns of genetic diversity and divergence on various geographic scales after converting the SNP loci within each genomic region into haplotypes. Marker type (SNP haplotype or MS) and location (genic or nongenic) significantly affected most estimates of population diversity and divergence. Between‐lineage divergence was significantly higher in SNP haplotypes (genic and nongenic), however, within‐lineage divergence was similar between marker types. Most divergence and diversity measures were uncorrelated between markers, except for population differentiation which was correlated between MSs and SNP haplotypes (both genic and nongenic). Broad‐scale population structure and assignment were similarly resolved by both marker types, however, only the MSs were able to delimit fine‐scale population structuring, particularly when genic and nongenic markers were combined. These results demonstrate that estimates of genetic variability and differentiation among populations can be strongly influenced by marker type, their genomic location in relation to genes and by the interaction of these two factors. This highlights the importance of having an awareness of the inherent strengths and limitations associated with different molecular tools to select the most appropriate methods for accurately addressing various ecological and evolutionary questions.     

A Shared Neural Substrate for Mentalizing and the Affective Component of Sentence Comprehension

Using event-related fMRI in a sample of 42 healthy participants, we compared the cerebral activity maps obtained when classifying spoken sentences based on the mental content of the main character (belief, deception or empathy) or on the emotional tonality of the sentence (happiness, anger or sadness). To control for the effects of different syntactic constructions (such as embedded clauses in belief sentences), we subtracted from each map the BOLD activations obtained during plausibility judgments on structurally matching sentences, devoid of emotions or ToM. The obtained theory of mind (ToM) and emotional speech comprehension networks overlapped in the bilateral temporo-parietal junction, posterior cingulate cortex, right anterior temporal lobe, dorsomedial prefrontal cortex and in the left inferior frontal sulcus. These regions form a ToM network, which contributes to the emotional component of spoken sentence comprehension. Compared with the ToM task, in which the sentences were enounced on a neutral tone, the emotional sentence classification task, in which the sentences were play-acted, was associated with a greater activity in the bilateral superior temporal sulcus, in line with the presence of emotional prosody. Besides, the ventromedial prefrontal cortex was more active during emotional than ToM sentence processing. This region may link mental state representations with verbal and prosodic emotional cues. Compared with emotional sentence classification, ToM was associated with greater activity in the caudate nucleus, paracingulate cortex, and superior frontal and parietal regions, in line with behavioral data showing that ToM sentence comprehension was a more demanding task.