On the identity ofCeryle rudis syriaca

Ceryle rudis syriaca Roselaar, 1995 was separated from nominaterudis only by its longer wings. As variations in the wing length ofCeryle rudis follow Bergmann's rule, it is suggested thatsyriaca is not recognised as a separate named taxon.

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Zusammenfassung Die Trennung vonCeryle rudis syriaca Roselaar, 1996 als eigene Subspezies basiert ausschließlich auf der etwas größeren Flügellänge. Da gezeigt werden konnte, daß die Flügellänge des Graufischers derBergmannschen Regel folgt, wird vorgeschlagen,syriaca wieder zu eliminieren.

     

The identity and typification of Pimia Seem. (Sterculiaceae)

The unispecific Fijian genus Pimia Seem. (Sterculiaceae) has long been considered to be related to genera that are now included in the Byttneriaceae (also known as Malvaceae-Byttnerioideae). Morphological characters, however, indicate that Pimia is a mixture of Commersonia J. R. Forst. & G. Forst. (Byttneriaceae) and Diospyros L. (Ebenaceae). The name of the sole species, P. rhamnoides Seem., is lectotypified with an element that is determined to be C. bartramia (L.) Merr. and thus Pimia becomes a synonym of Commersonia. An epitype for P. rhamnoides is also selected because the lectotype now lacks flowers, which were an important element of the protologue.     

Polyhomeotic: A gene of Drosophila melanogaster required for correct expression of segmental identity

Summary A new locus in Drosophila melanogaster that is required for the correct expression of segmental identity has been discovered. The new locus, termed polyhomeotic (ph), is X-linked and maps cytologically to bands 2D2-3. Homozygous ph flies have homeotic transformations similar to those of known dominant gain of function mutants in the Antennapedia and bithorax complexes (ANT-C, BX-C), and in addition show loss of the humerus. ph interacts with three other similar mutations: Polycomb (Pc), Polycomblike (Pcl), and extra sex comb (esc), and acts as a dominant enhancer of Pc. The expression of ph depends on the ANT-C and BX-C dosage. ph has no embryonic phenotype, but temperature shift studies on ph² show that the ph⁺ product is required during embryogenesis and larval development. We propose that ph mutants in some way disrupt the normal expression of the ANT-C and BX-C, and, therefore, that ph⁺ is needed for maintenance of segmental identity.     

On the identity of the 640-nm component observed in chlorophyll b absorption spectra in vivo

Mathematical analysis of the results of mild acetone extraction of chloro-plast-fragment preparations from Ulva lactuca demonstrates that the 640-nm shoulder on the short-wave side of the red chlorophyll b absorption band is not due to this chlorophyll.

The analysis furthermore provides rather strong evidence that the 640-nm shoulder is correlated with an absorption band peaking around 682nm. It is suggested that the 640-nm component is due to the reaction center pigment of Photo-system II.     

Direct control of antennal identity by the spineless-aristapedia gene of Drosophila

Summary Loss-of-function mutations in the spineless-aristapedia gene of Drosophila (ss ^a mutants) cause transformations of the distal antenna to distal second leg, deletions or fusions of the tarsi from all three legs, a general reduction in bristle size, and sterility. Because ss ^a mutants are pleiotropic, it has been suggested that ss ⁺ has some rather general function and that the ss ^a antennal transformation is an indirect consequence of perturbations in the expression of other genes that more directly control antennal or second leg identity. Here we test whether the ss ^a transformation results from aberrant expression of Antennapedia (Antp), a homeotic gene thought to specify directly the identity of the second thoracic segment. We find that Antp ^– ss ^a mitotic recombination clones in the distal antenna behave identically to Antp ⁺ ss ^a clones, and are transformed to second leg. This demonstrates that the ss ^a antennal transformation is independent of Antp ⁺, and suggests that ss ⁺ may itself directly define distal antennal identity. The results also reveal that Antp ⁺ is not required for the development of distal second leg structures, as these develop apparently normally in Antp ^– ss ^a antennal clones. Because Antp ^– mutations cause deletions or transformations that are restricted to proximal structures, whereas ss ^a alleles cause similar defects that are distally restricted, we suggest that ss ⁺ and Antp ⁺ may play similar, but complementary, roles in the distal and proximal portions of appendages, respectively.     

The role of the genesnrf EFG andccmFH in cytochromec biosynthesis inEscherichia coli

It has been suggested that two groups ofEscherichia coli genes, theccm genes located in the 47-min region and thenrfEFG genes in the 92-min region of the chromosome, are involved in cytochromec biosynthesis during anaerobic growth. The involvement of the products of these genes in cytochromec synthesis, assembly and secretion has now been investigated. Despite their similarity to other bacterial cytochromec assembly proteins, NrfE, F and G were found not to be required for the biosynthesis of any of thec-type cytochromes inE. coli. Furthermore, these proteins were not required for the secretion of the periplasmic cytochromes, cytochromec ₅₅₀ and cytochromec ₅₅₂, or for the correct targeting of the NapC and NrfB cytochromes to the cytoplasmic membrane. NrfE and NrfG are required for formate-dependent nitrite reduction (the Nrf pathway), which involves at least twoc-type cytochromes, cytochromec ₅₅₂ and NrfB, but NrfF is not essential for this pathway. Genes similar tonrfE, nrfF andnrfG are present in theE. coli nap-ccm locus at minute 47. CcmF is similar to NrfE, the N-terminal region of CcmH is similar to NrfF and the C-terminal portion of CcmH is similar to NrfG. In contrast to NrfF, the N-terminal, NrfF-like portion of CcmH is essential for the synthesis of allc-type cytochromes. Conversely, the NrfG-like C-terminal region of CcmH is not essential for cytochromec biosynthesis. The data are consistent with proposals from this and other laboratories that CcmF and CcmH form part of a haem lyase complex required to attach haemc to C-X-X-C-H haem-binding domains. In contrast, NrfE and NrfG are proposed to fulfill a more specialised role in the assembly of the formate-dependent nitrite reductase.     

The relation of the genes envA and ftsA in Escherichia coli

Summary The sequence of three genes involved in cell division in E. coli has been determined to be ftsA-envA-azi by three-point transduction experiments. An ftsA envA double mutant strain forms filaments at the restrictive temperature of 42° C, and not chains, but, like the chain forming envA parent strain, is hypersensitive to rifampicin.     

The phylogenetic placement of Ostropales within Lecanoromycetes (Ascomycota) revisited

Results of molecular studies regarding the phylogenetic placement of the order Ostropales and related taxa within Lecanoromycetes were thus far inconclusive. Some analyses placed the order as sister to the rest of Lecanoromycetes, while others inferred a position nested within Lecanoromycetes. We assembled a data set of 101 species including sequences from nuLSU rDNA, mtSSU rDNA, and the nuclear protein-coding RPB1 for each species to examine the cause of incongruencies in previously published phylogenies. MP, minimum evolution, and Bayesian analyses were performed using the combined three-region data set and the single-gene data sets. The position of Ostropales nested in Lecanoromycetes is confirmed in all single-gene and concatenated analyses, and a placement as sister to the rest of Lecanoromycetes is significantly rejected using two independent methods of alternative topology testing. Acarosporales and related taxa (Acarosporaceae group) are basal in Lecanoromycetes. However, if the these basal taxa are excluded from the analyses, Ostropales appear to be sister to the rest of Lecanoromycetes, suggesting different ingroup rooting as the cause for deviating topologies in previously published phylogenies.     

Probing the Drosophila retinal determination gene network in Tribolium (II): The Pax6 genes eyeless and twin of eyeless

The Pax6 genes eyeless (ey) and twin of eyeless (toy) are upstream regulators in the retinal determination gene network (RDGN), which instructs the formation of the adult eye primordium in Drosophila. Most animals possess a singleton Pax6 ortholog, but the dependence of eye development on Pax6 is widely conserved. A rare exception is given by the larval eyes of Drosophila, which develop independently of ey and toy. To obtain insight into the origin of differential larval and adult eye regulation, we studied the function of toy and ey in the red flour beetle Tribolium castaneum. We find that single and combinatorial knockdown of toy and ey affect larval eye development strongly but adult eye development only mildly in this primitive hemimetabolous species. Compound eye-loss, however, was provoked when ey and toy were RNAi-silenced in combination with the early retinal gene dachshund (dac). We propose that these data reflect a role of Pax6 during regional specification in the developing head and that the subsequent maintenance and growth of the adult eye primordium is regulated partly by redundant and partly by specific functions of toy, ey and dac in Tribolium. The results from embryonic knockdown and comparative protein sequence analysis lead us further to conclude that Tribolium represents an ancestral state of redundant control by ey and toy.     

The cloning of the rorB gene of Escherichia coli

Summary A segment of the Escherichia coli genome which complements the ionising radiation sensitivity of the rorB mutation was cloned into pBR322. This DNA segment also complements the mitomycin C sensitivity of the rorB mutation. The gene was subcloned until defined in a fragment of 1.05 kb. Only one gene product, a protein of approximately 16.5 kDa, was found on maxicell analysis of the various subclones. Iso-electric focusing of this gene product suggests it may function in a complex.     

The Drosophila genome

The past year has been a spectacular one for Drosophila research. The sequencing and annotation of the Drosophila melanogaster genome has allowed a comprehensive analysis of the first three eukaryotes to be sequenced—yeast, worm and fly—including an analysis of the fly's influences as a model for the study of human disease. This year has also seen the initiation of a full-length cDNA sequencing project and the first analysis of Drosophila development using high-density DNA microarrays containing several thousand Drosophila genes. For the first time homologous recombination has been demonstrated in flies and targeted gene disruptions may not be far off.     

The oral apparatus of tadpoles of Rana dalmatina, Bombina variegata, Bufo bufo, and Bufo viridis (Anura)

The morphology and development of the larval oral apparatus of Rana dalmatina, Bombina variegata, Bufo bufo, and Bufo viridis are described and compared using scanning electron microscopy. The species show different arrangements of the mouthparts. The small oral apparatus of R. dalmatina larvae has three labial tooth rows on the upper labium, while there are four tooth rows on the lower labium with a medial gap in row proximal to the mouth. The margins of the oral apparatus are defined by papillae that encircle the lower labium. B. variegata tadpoles have two upper labial tooth rows and three lower labial tooth rows that are uninterrupted, unlike the ones of R. dalmatina. The mouth is encircled by papillae that are larger than those of R. dalmatina. The oral discs of tadpoles of both B. bufo and B. viridis are similar. They are defined by two upper labial tooth rows (the second of which is interrupted by a medial gap) and by three lower tooth rows that differ in lengths in the two Bufo species. Both species develop papillae on the mouth angles and in two rows on the upper labium. Some morphological differences among the oral discs of R. dalmatina, B. variegata, B. bufo, and B. viridis tadpoles can be attributed to phylogenetic differences, but most can be related to their varying feeding habits and/or to their dietary specializations.     

The effect of seasonality on oxidative metabolism in Nacella (Patinigera) magellanica

We studied the seasonal variation on aerobic metabolism and the response of oxidative stress parameters in the digestive glands of the subpolar limpet Nacella (P.) magellanica. Sampling was carried out from July (winter) 2002 to July 2003 in Beagle Channel, Tierra del Fuego, Argentina. Whole animal respiration rates increased in early spring as the animals spawned and remained elevated throughout summer and fall (winter: 0.09 ± 0.02 μmol O₂ h^− 1 g^− 1; summer: 0.31 ± 0.06 μmol O₂ h^− 1 g^− 1). Oxidative stress was assessed at the hydrophilic level as the ascorbyl radical content / ascorbate content ratio (A / AH⁻). The A / AH⁻ ratio showed minimum values in winter (3.7 ± 0.2 10^− 5 AU) and increased in summer (18 ± 5 10^− 5 AU). A similar pattern was observed for lipid radical content (122 ± 29 pmol mg^− 1 fresh mass [FW] in winter and 314 ± 45 pmol mg^− 1 FW in summer), iron content (0.99 ± 0.07 and 2.7 ± 0.6 nmol mg^− 1 FW in winter and summer, respectively) and catalase activity (2.9 ± 0.2 and 7 ± 1 U mg^− 1 FW in winter and summer, respectively). Since nitrogen derived radicals are thought to be critically involved in oxidative metabolism in cells, nitric oxide content was measured and a significant difference in the content of the Fe–MGD–NO adduct in digestive glands from winter and summer animals was observed. Together, the data indicate that both oxygen and nitrogen radical generation rates in N. (P.) magellanica are strongly dependent on season.     

The selective inactivation of thiol proteasesin vitro andin vivo

Peptidyl diazomethyl ketone derivatives inactivate thiol proteases by affinity labeling. The peptide sequence permits the reagents to be targeted to individual proteases according to their specificity. Alkylation of the active center thiol group takes place. The reagents are not reactive to simple thiols such as mercaptoethanol and appear to inactivate thiol proteases by acting as suicide substrates. Other classes of proteases are not affected. Initial results indicate that peptidyl diazomethyl ketones can also be used to inactivate thiol proteases in vivo.Dedicated to Robert Feeney on the occasion of his 70th birthday.     

The flavonoids of Margaranthus

Four flavonols based on either quercetin or kaempferol are found in Margaranthus. The compounds are uniform throughout the populations examined and no evidence is present for the recognition of more than one species. The flavonols are similar to those found in related in genera, and do not provide a basis for the exclusion of Margaranthus from the subtribe Solaninae.     

The ribosomes of Drosophila

Summary One- and two-dimensional gel electrophoresis was employed to characterize and compare ribosomal subunit proteins from wild-type D. melanogaster and several mutants, including suppressor-offorked and four X-linked cold sensitive lethals. The sibling species D. simulans was also studied. We found the electropherogram patterns indistinguishable in all cases.This work was supported by grants from the National Institutes of Health (GM 18910, GM 22866) and the National Science Foundation (BM S75-11890) to Edward Berger