The expression of a hunchback ortholog in the polychaete annelid Platynereis dumerilii suggests an ancestral role in mesoderm development and neurogenesis

Orthologs of the Drosophila gap gene hunchback have been isolated so far only in protostomes. Phylogenetic analysis of recently available genomic data allowed us to confirm that hunchback genes are widely found in protostomes (both lophotrochozoans and ecdysozoans). In contrast, no unequivocal hunchback gene can be found in the genomes of deuterostomes and non-bilaterians. We cloned hunchback in the marine polychaete annelid Platynereis dumerilii and analysed its expression during development. In this species, hunchback displays an expression pattern indicative of a role in mesoderm formation and neurogenesis, and similar to the expression found for hunchback genes in arthropods. These data suggest altogether that these functions are ancestral to protostomes.Pierre Kerner and Fabiola Zelada González contributed equally to this work.     

Preferential oxidative dehalogenation upon conversion of 2-halophenols by Rhodococcus opacus 1G

The regiospecificity of hydroxylation of C2-halogenated phenols by Rhodococcus opacus 1G was investigated. Oxidative defluorination at the C2 position ortho with respect to the hydroxyl moiety was preferred over hydroxylation at the non-fluorinated C6 position for all 2-fluorophenol compounds studied. Initial hydroxylation of 2,3, 5-trichlorophenol resulted in the exclusive formation of 3, 5-dichlorocatechol. These results indicate that, in contrast to all other phenol ortho-hydroxylases studied so far, phenol hydroxylase from R. opacus 1G is capable of catalyzing preferential oxidative defluorination but also oxidative dechlorination.     

The angiotensin converting enzyme inhibitory tripeptides Ile-Pro-Pro and Val-Pro-Pro show increasing permeabilities with increasing physiological relevance of absorption models

Transepithelial transport of the ACE inhibitory peptides Ile-Pro-Pro and Val-Pro-Pro was studied in different models of absorption. Apparent permeability (P(app)) values for absorptive transport across Caco-2 monolayers were 1.0+/-0.9 x 10(-8) (Ile-Pro-Pro) and 0.5+/-0.1 x 10(-8)cms(-1) (Val-Pro-Pro). Ex vivo transport across jejunal segments in the Ussing chamber was 5-times (Ile-Pro-Pro) to 10-times (Val-Pro-Pro) higher with no significant differences (p>0.05) observed between both peptides. The peptidase inhibitor bestatin increased permeability for the absorptive direction for Ile-Pro-Pro by twofold. Neither a transepithelial pH gradient nor increased apical tripeptide concentration nor longitudinal localization of the intestinal segment influenced P(app) in the ex vivo experiments. Val-Pro-Pro transport across Peyer's patches, however, was 4-times higher (P(app)=21.0+/-9.3 x10(-8)cms(-1)) as compared to duodenum (P(app)=4.8+/-1.4 x 10(-8)cms(-1)). In the in situ perfusion experiments P(app) values varied greatly among different animals ranging from 0.5 to 24.0 x10(-8)cms(-1) (Ile-Pro-Pro) and from 1.0 to 15.6 x 10(-8)cms(-1) (Val-Pro-Pro). In summary, Caco-2 and ex vivo absorption models differ considerably regarding their peptide permeability. The in situ model seems to be less appropriate because of the observed large variability in peptide permeability. The results of this study demonstrate that the ACE inhibitory peptides Ile-Pro-Pro and Val-Pro-Pro are absorbed partially undegraded.     

Two new species of Staurotheca Allman, 1888 (Cnidaria, Hydrozoa, Sertulariidae) from the Scotia Sea (Antarctica)

Two new species of the genus Staurotheca Allman, 1888 have been studied (Staurotheca cornuta sp. nov. and Staurotheca multifurcata sp. nov). The material, from the Scotia Ridge area (Antarctica), was collected in 1986/1987 by the Spanish Antarctic expedition “Antártida 8611”. Each species is described and figured, and its systematic position among allied species is noted. Data concerning autecology and geographical distribution for each species are given. A comparative table listing the main features of the known species of the genus is included. Finally, a general survey of the geographical and bathymetrical distribution of the known species of the genus is presented. Accepted: 1 September 1998     

Possible role of a short extra loop of the long-chain flavodoxin from Azotobacter chroococcum in electron transfer to nitrogenase: Complete 1H, 15N and 13C backbone assignments and secondary solution structure of the flavodoxin

Summary The ¹H, ¹⁵N and ¹³C backbone and ¹H and ¹³C beta resonance assignments of the long-chain flavodoxin from Azotobacter chroococcum (the 20-kDa nifF product, flavodoxin-2) in its oxidized form were made at pH 6.5 and 30°C using heteronuclear multidimensional NMR spectroscopy. Analysis of the NOE connectivities, together with amide exchange rates, ³J_Hn_H coupling constants and secondary chemical shifts, provided extensive solution secondary structure information. The secondary structure consists of a five-stranded parallel -sheet and five -helices. One of the outer regions of the -sheet shows no regular extended conformation, whereas the outer strand 4/6 is interrupted by a loop, which is typically observed in long-chain flavodoxins. Two of the five -helices are nonregular at the N-terminus of the helix. Loop regions close to the FMN are identified. Negatively charged amino acid residues are found to be mainly clustered around the FMN, whereas a cluster of positively charged residues is located in one of the -helices. Titration of the flavodoxin with the Fe protein of the A. chroococcum nitrogenase enzyme complex revealed that residues Asn¹¹, Ser⁶⁸ and Asn⁷² are involved in complex formation between the flavodoxin and Fe protein. The interaction between the flavodoxin and the Fe protein is influenced by MgADP and is of electrostatic nature.Abbreviations SQ semiquinone - FMN riboflavin 5-monophosphate; nif, nitrogen fixation - TSP 3-(trimethylsilyl)propionate sodium salt - DSS 2,2-dimethyl-2-silapentane-5-sulfonate sodium salt Supplementary Material is available on request, comprising a Materials and Methods section for the expression and purification of the A. chroococcum flavodoxin, a Table S1 containing the parameters of the titration of A. chroococcum flavodoxin with the Fe protein, and a Table S2 containing the ¹⁵N, H^N, ¹³C, ¹H, ¹³C, ¹H and ¹³CO chemical shifts.To whom correspondence should be addressed.     

Evaluating Swiss pollen productivity estimates using a simulation approach

We simulated pollen assemblages for 11 sites on the Swiss Plateau (Schweizer Mittelland) based on a low resolution land cover map and pollen productivity estimates (PPE) from this region. A comparison between observed and simulated pollen data demonstrated that the majority of the simulated pollen proportions were within a range of 5% of over- or underestimation, and that at eight of the 11 sites the dominant taxon was correctly estimated. The modelled sum of arboreal pollen was correct within ±11% at nine sites. Our results indicate that the PPE established for the Swiss Plateau can be used to simulate pollen assemblages with reasonable accuracy. Moreover, our results justify the use of the POLLSCAPE simulation using the Prentice-Sugita model and its variations of pollen dispersal and deposition in more complex topographic landscapes than those to which they have hitherto been applied.