Testing heterogeneous base composition as potential cause for conflicting phylogenetic signal between mitochondrial and nuclear DNA in the land snail genus <Emphasis Type="Italic">Theba</Emphasis> Risso 1826 (Gastropoda: Stylommatophora: Helicoidea)

Several pitfalls can mislead phylogenetic analyses based on molecular data, including heterogeneous base composition. Previous work has revealed conflicting topologies in analyses of the land snail genus Theba Risso 1826 based on mitochondrial cytochrome oxidase subunit I (COI) and nuclear AFLP data, respectively. However, the third codon positions of COI had heterogeneous base composition, prompting the present investigation asking specifically if this was the cause for the mito-nuclear discordance. For a potentially better resolution of the mitochondrial data, we also sequenced a fragment of 16S rRNA, the loop sections of which proved to have inhomogeneous base frequencies as well. In partitioned phylogenetic analyses, we compared topologies generated from the original data to those based on alignments in which the heterogeneous partitions were RY-coded and to a LogDet transformed distance analysis. In addition, we tested whether conventional Bayesian analyses would reconstruct the original topology from inhomogeneous data simulated based on this original topology. All our analyses, regardless of whether we accounted for heterogeneous base frequencies or not, revealed very similar topologies, confirming previous findings. Thus, the phylogenetic signal of mtDNA in the land snail genus Theba appeared to be robust despite considerable inhomogeneity of base composition. Therefore, the discordance of mitochondrial and nuclear topologies is probably real and most likely a consequence of incomplete lineage sorting.     

Secondary structure and phylogenetic analysis of the internal transcribed spacers 1 and 2 of bush crickets (Orthoptera: Tettigoniidae: Barbitistini)

We inferred secondary structure models of the internal transcribed spacers (ITS) 1 and 2 of bush crickets using a combined comparative and thermodynamic approach. The inferred secondary structure models were used to account for interdependency of interacting nucleotides in a phylogenetic analysis of the bush cricket genus Poecilimon. Our analysis indicates that the two previously reported conformational structures (i.e., hairpin and ring) of ITS2 are likely to fold in bush crickets as well and that both predicted structures are similar to those proposed for other eukaryotes. Comparing predicted ITS1 secondary structure models proved to be difficult because of substantial variation in their nucleotide sequence length. Our study revealed that the phylogenetic signal of ITS1 and ITS2 is largely congruent with that preserved in the mitochondrial genes 16S rRNA, tRNA‐Val and 12S rRNA. The phylogenetic signal in both the nuclear and the mitochondrial genome question the monophyly of the genus Poecilimon: species of the genera Poecilimonella, Parapoecilimon, Polysarcus and Phonochorion consistently cluster within Poecilimon.     

How can a character be developmentally constrained despite variation in developmental pathways?

A fundamental riddle of evolutionary developmental biology is the conservation of adult morphological patterns (Hall, 1992). Conservative patterns are either called body plans if they concern overall body design, or homologues if they concern parts of the body (Riedl, 1978; Roth, 1982; Sattler, 1984; Van Valen, 1982; Wagner, 1989a, 1989b). An adult pattern is considered conservative if it remains unchanged in spite of changes in function, as indicated by the original definition of homology by Owen, as a similarity of organs regardless of form and function (Owen, 1848). Conservation of anatomical features despite different adaptive pressures is naturally explained by developmental constraints (Wagner, 1986). However, this approach to explain the biological basis of homology is plagued by the fact that developmental pathways are often more variable than the characters that they produce (see Tab. 1) (Hall, 1992; Roth, 1988, 1991; Spemann, 1915; Wagner, 1989b). This is also true for any other application of the concept of developmental constraints. The widely held opinion that early stages of development are conservative because any early perturbation is likely to interfere with later development, is far from absolute, since a vast amount of data in comparative developmental biology speaks to developmental variation (see e.g. the examples in Tab. 1). The question then is, how can developmental constraints on adult variation be reconciled with the fact of developmental variation?     

Application of stains in clinical microbiology

Stains have been used for diagnosing infectious diseases since the late 1800s. The Gram stain remains the most commonly used stain because it detects and differentiates a wide range of pathogens. The next most commonly used diagnostic technique is acid-fast staining that is used primarily to detect Mycobacterium tuberculosis and other severe infections. Many infectious agents grow slowly on culture media or may not grow at all; stains may be the only method to detect these organisms in clinical specimens. In the hands of experienced clinical microscopists, stains provide rapid and cost-effective information for preliminary diagnosis of infectious diseases. A review of the most common staining methods used in the clinical microbiology laboratory is presented here.     

Characterization of microsatellite loci in Amphitmetus transversus (Kolbe, 1897) (Coleoptera,Curculionidae)

We developed six microsatellite markers for Amphitmetus transversus (Kolbe, 1897) (Coleoptera, Curculionidae), a beetle widely distributed in the guineo‐congolian rainforests of east Africa. The numbers of alleles per locus range from three to eight, with a mean number of 4.6. They will be used for population genetic analysis. The ongoing study concentrates on the genetic differentiation and variability of isolated populations in the Kakamega Forest, a highly degraded and fragmented rainforest remnant in western Kenya.     

The head anatomy of Epiophlebia superstes (Odonata: Epiophlebiidae)

The relic dragonfly family Epiophlebiidae is recovered as sistergroup of Anisoptera (= Epiprocta) by most molecular and morphological analyses. However, in a recent study it was placed within Anisoptera as sister group of Cordulegastridae. In another study, several affinities to Zygoptera in the morphology of the ovipositor and the egg-laying behaviour were pointed out. Here, we present a detailed study of the outer, as well as the inner, head morphology of Epiophlebia superstes. Compared with the last detailed literature account, three additional mandibular muscles were discovered, as well as additional buccal and pharyngeal muscles. The results are compared with the anatomic features of Zygoptera and Anisoptera. A formal character evaluation focused on head characters confirms the sistergroup relationship of Epiophlebiidae and Anisoptera.