The wing base of the palaeodictyopteran genus Dunbaria Tillyard: Where are we now?

The structure of insect wing articulation is considered as reliable source of high level characters for phylogenetic analyses. However, the correct identification of homologous structures among the main groups of Pterygota is a hotly debated issue. Therefore, the reconstruction of the wing bases in Paleozoic extinct relatives is of great interest, but at the same time it should be treated with extreme caution due to distortions caused by taphonomic effects. The present study is focused on the wing base in Dunbaria (Spilapteridae). The articulation in Dunbaria quinquefasciata is mainly formed by a prominent upright axillary plate while the humeral plate is markedly reduced. Due to unique preservation of surface relief of the axillary plate, its composition shows a detailed pattern of three fused axillary sclerites and presumable position of the sclerite 3Ax. The obtained structures were compared among Spilapteridae and to other palaeodictyopterans Ostrava nigra (Homoiopteridae) and Namuroningxia elegans (Namuroningxiidae). The comparative study uncovered two patterns of 3Ax in Dunbaria and Namuroningxia, which correspond to their different suprafamilial classification. In contrast to previous studies these new results reveal the homologous structural elements in the wing base between Paleozoic Palaeodictyoptera and their extant relatives of Ephemeroptera, Odonata and Neoptera.     

Protein tyrosine phosphatase gene expression analysis in Swiss 3T3 fibroblasts

The aim of this study was to identify protein tyrosine phosphatases (PTPs) expressed in Swiss 3T3 fibroblasts and to examine their expression levels as well as to characterize quantitative aspects of RT-PCR based on degenerate deoxyoligonucleotides. By using an RT-PCR assay based on degenerate deoxyoligonucleotide primers, expression of mRNAs for two cytoplasmic- and six transmembrane-type PTPs in Swiss 3T3 cells was detected. The sequences of two of them are new. Among nine analyzed PTPs expressed to widely varied extends, only three have mRNA levels high enough to be seen on Northern blots with 10 µg of total RNA per lane. The frequencies with which the examined PTPs are represented among the PCR amplification products, correlate stronger with the primer fidelity, defined as the number of mismatches between the primer- and the cDNA target-sequences, rather than with the PTP expression levels. In conclusion, an RT-PCR assay based on degenerate primers can be successfully used to sample the expressed PTPs and to identify new members of this gene family. However, reliable quantification of their mRNA levels can only be achieved using the classical approaches, like Northern, RNase protection assay or non-degenerate quantitative RT-PCR.     

Timber stacks: potential ecological traps for an endangered saproxylic beetle,the Rosalia longicorn <Emphasis Type="Italic">Rosalia alpina</Emphasis>

Ecological traps are serious, anthropogenic threats to animal populations. However, in certain cases it is difficult to determine whether they really act in the expected manner. This applies to the harmful effects of beech timber stacked in forests on the endangered saproxylic beetle Rosalia longicorn Rosalia alpina, which have been mentioned in numerous scientific articles, conservation action plans and similar publications. The aim of this paper is to determine whether beech timber stacks meet the criteria of an ecological trap for the Rosalia longicorn. Two basic criteria of such a trap are analysed: the attractiveness of timber stacks and the impossibility of complete larval development. The results show that beech timber stacks are highly attractive to Rosalia longicorn imagines. Moreover, the time during which the timber is stacked is shown to be significantly shorter than the species’ larval development period. These results suggest that timber stacks can be treated as operative ecological traps for the Rosalia longicorn, even though the extent of their influence on the demographic parameters of this beetle’s population has not been estimated. Forest management practices, i.e. increasing amounts and shifts in timing of wood storage, could intensify this threat.     

Residues Phe342-Asn346 of activated coagulation factor IX contribute to the interaction with low density lipoprotein receptor-related protein

When blood coagulation factor IX is converted to activated factor IX (factor IXa), it develops enzymatic activity and exposes the binding sites for both activated factor VIII and the endocytic receptor low density lipoprotein receptor-related protein (LRP). In the present study we investigated the interaction between factor IXa and LRP in more detail, using an affinity-purified soluble form of LRP (sLRP). Purified sLRP and full-length LRP displayed similar binding to factor IXa. An anti-factor IX monoclonal antibody CLB-FIX 13 inhibited factor IXa.sLRP complex formation. Both the antibody and a soluble recombinant fragment of LRP (i.e. cluster IV) interfered with factor IXa amidolytic activity, suggesting that the antibody and LRP share similar binding regions near the active site of factor IXa. Next, a panel of recombinant factor IXa variants with amino acid replacements in the surface loops bordering the active site was tested for binding to antibody CLB-FIX 13 and sLRP in a solid phase binding assay. Factor IXa variants with mutations in the region Phe(342)-Asn(346), located between the active site of factor IXa and factor VIII binding helix, showed reduced binding to both antibody CLB-FIX 13 and sLRP. Surface plasmon resonance analysis revealed that the variant with Asn(346) replaced by Asp displayed slower association to sLRP, whereas the variant with residues Phe(342)-Tyr(345) replaced by the corresponding residues of thrombin showed faster dissociation. Recombinant soluble LRP fragment cluster IV inhibited factor IXa-mediated activation of factor X with IC(50) values of 5 and 40 nm in the presence and absence of factor VIII, respectively. This inhibition thus seems to occur via two mechanisms: by interference with factor IXa.factor VIIIa complex assembly and by direct inhibition of factor IXa enzymatic activity. Accordingly, we propose that LRP may function as a regulator of blood coagulation.     

Genetic variability of body weight in two goose strains under long-term selection

Body weight is one of the most important traits in any genetic improvement program in geese for at least 2 reasons. First, measurements of the trait are very easy. Second, body weight is correlated with a number of other meat performance traits. However, the genetic background of body weight shows considerable complexity. Three genetic models (with direct, maternal genetic and permanent maternal environmental effects) were employed in this study. Records of 3076 individuals of maternal strain W11 and 2656 individuals of paternal strain W33 over 6 consecutive generations, kept in the pedigree farm of Ko?uda Wielka, were analysed. Body weight (in kilograms) was measured in weeks 8 (BW8) and 11 (BW11). The inbreeding levels in both populations were relatively low (0.14% and 0.02% for W11 and W33, respectively), therefore these effects were not included in the linear models to estimate genetic parameters. Three fixed effects (hatch period, sex and year) were included in each linear model. Two criteria (AIC, BIC) were used to check the goodness of fit of the models. The computations were performed by WOMBAT software. In general, the genetic parameter estimates varied across the traits, models and strains studied. Direct additive heritability estimates ranged from 0.0001 (for BW11 of W33) to 0.55 (for BW11 of W33). Maternal and total heritabilities were also variable. Estimates of ratios of direct-maternal effect covariance in phenotypic variance were both positive and negative, but they were negligible, whereas ratios of the permanent environmental maternal variance to phenotypic variance were close to zero. Both of the applied criteria of model adequacy indicate that the model with maternal genetic and environmental effects should be considered as optimal. Genetic trends were close to zero. It seems that they were influenced by long-term selection. Similar tendencies have been observed for phenotypic trends, as well.     

When a key innovation becomes redundant: Patterns,drivers and consequences of elytral reduction in Coleoptera

The transformation of the fore wings into strongly sclerotized protective covers (elytra) is considered a fundamental evolutionary innovation of the megadiverse order Coleoptera. Surprisingly, these multifunctional structures have been reduced in many distantly related groups of beetles. Patterns, drivers and the evolutionary implications of this modification have never been comprehensively discussed. In the present study, we surveyed the entire order Coleoptera to analyse the patterns of elytral shortening and loss, with a special focus on prevalence, forms, degree of reduction and the functional background of this significant deviation from the coleopteran ground plan. Our analysis revealed that about 20% of all extant species (roughly 88,000 out of 442,275 spp.), distributed across all four suborders, have shortened or even absent elytra. The elytral loss was more frequent within the polyphagan series Elateriformia and Staphyliniformia. Moreover, we found that elytral reduction has independently occurred multiple times in the evolutionary history of Coleoptera and that it has been driven by a wide array of selective drivers. One of the main drivers is the improved flexibility of the uncovered abdomen and the correlated increased manoeuvrability in narrow spaces, as well as the option of using the flexible abdomen as a steering organ or to facilitate mating. Another common driver is mimicry, where exposed metathoracic wings potentially improve the overall similarity to hymenopteran models. Exposure of the abdomen can facilitate the targeted release of defensive abdominal gland secretions and was most likely a crucial step towards establishing relations with social insects enhanced by chemical communication. In the Elateriformia, and rarely in other lineages, elytral loss is a consequence of paedomorphosis, related to a specific resource-allocation strategy. In many groups of beetles with reduced elytra, alternative defensive strategies can be found. This includes, for instance, aposematic coloration, chemical defence, mimicry or bioluminescence. Direct drivers of elytral loss in many groups remain unclear, and more studies are needed to understand the evolutionary background and implications of this significant morphological modification in Coleoptera.