Plant and arthropod communities in young oak stands: are they determined by site history?

Effect of site history on forest plant and insect communities was studied by comparing afforestations on former agricultural land with reafforestations on ancient woodland sites. Vascular plants, mosses, true bugs, lacewings and saproxylic beetles were surveyed at 18 young broadleaved forest sites dominated by oak (Quercus robur), established between 1986 and 1994 in three different growth regions in Bavaria, Germany. Two strata, near ground level and the canopy, were sampled. Compared to woodland reafforestations greater species density and abundance of plants and true bugs were observed in field layer of afforestation sites. Proportion of forest species among plants and true bugs was however significantly lower in afforestations than on ancient woodland sites. In the canopy, zoo-phytophagous true bugs were significantly better represented in afforestations and zoophagous true bugs in reafforestations. Saproxylic beetles, especially inhabitants of old dead wood, were species-poor in afforestations. Results indicate that site history affects both producer and consumer communities in multiple ways, even 20 years after afforestation of former agricultural land. However, afforestations adjacent to existing forest stands can be regarded as valuable to nature conservation in effectively extending forest habitats. Investment in such afforestation therefore represents more than just an agricultural subsidy. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A nationwide population-based skin cancer screening in Germany: Proceedings of the first meeting of the International Task Force on Skin Cancer Screening and Prevention (September 24 and 25, 2009)

Skin cancer incidence is increasing worldwide in white populations and mortality rates have not declined throughout most of the world. An extraordinarily high proportion of at-risk individuals have yet to be screened for melanoma but guidelines from esteemed bodies do not currently endorse population-based screening. Evidence for the effectiveness of skin cancer screening is imperative. To this end, scientists in Germany have launched a nationwide skin cancer screening campaign. Herein, we review pilot screening data from Schleswig-Holstein, discuss the launch of the major new national initiative, review issues related to evaluation of that program, and propose seven recommendations from the International Task Force on Skin Cancer Screening and Prevention that was held in Hamburg, Germany, on September 24 and 25, 2009.     

Function of the HVCN1 proton channel in airway epithelia and a naturally occurring mutation,M91T

Airways secrete considerable amounts of acid. In this study, we investigated the identity and the pH-dependent function of the apical H⁺ channel in the airway epithelium. In pH stat recordings of confluent JME airway epithelia in Ussing chambers, Zn-sensitive acid secretion was activated at a mucosal threshold pH of ∼7, above which it increased pH-dependently at a rate of 339 ± 34 nmol × h⁻¹ × cm⁻² per pH unit. Similarly, H⁺ currents measured in JME cells in patch clamp recordings were readily blocked by Zn and activated by an alkaline outside pH. Small interfering RNA–mediated knockdown of HVCN1 mRNA expression in JME cells resulted in a loss of H⁺ currents in patch clamp recordings. Cloning of the open reading frame of HVCN1 from primary human airway epithelia resulted in a wild-type clone and a clone characterized by two sequential base exchanges (452T>C and 453G>A) resulting in a novel missense mutation, M91T HVCN1. Out of 95 human genomic DNA samples that were tested, we found one HVCN1 allele that was heterozygous for the M91T mutation. The activation of acid secretion in epithelia that natively expressed M91T HVCN1 required ∼0.5 pH units more alkaline mucosal pH values compared with wild-type epithelia. Similarly, activation of H⁺ currents across recombinantly expressed M91T HVCN1 required significantly larger pH gradients compared with wild-type HVCN1. This study provides both functional and molecular indications that the HVCN1 H⁺ channel mediates pH-regulated acid secretion by the airway epithelium. These data indicate that apical HVCN1 represents a mechanism to acidify an alkaline airway surface liquid.     

Functional Gene Group Analysis Reveals a Role of Synaptic Heterotrimeric G Proteins in Cognitive Ability

Although cognitive ability is a highly heritable complex trait, only a few genes have been identified, explaining relatively low proportions of the observed trait variation. This implies that hundreds of genes of small effect may be of importance for cognitive ability. We applied an innovative method in which we tested for the effect of groups of genes defined according to cellular function (functional gene group analysis). Using an initial sample of 627 subjects, this functional gene group analysis detected that synaptic heterotrimeric guanine nucleotide binding proteins (G proteins) play an important role in cognitive ability (P_EMP = 1.9 × 10⁻⁴). The association with heterotrimeric G proteins was validated in an independent population sample of 1507 subjects. Heterotrimeric G proteins are central relay factors between the activation of plasma membrane receptors by extracellular ligands and the cellular responses that these induce, and they can be considered a point of convergence, or a “signaling bottleneck.” Although alterations in synaptic signaling processes may not be the exclusive explanation for the association of heterotrimeric G proteins with cognitive ability, such alterations may prominently affect the properties of neuronal networks in the brain in such a manner that impaired cognitive ability and lower intelligence are observed. The reported association of synaptic heterotrimeric G proteins with cognitive ability clearly points to a new direction in the study of the genetic basis of cognitive ability.     

Structural changes of Escherichia coli ferric uptake regulator during metal-dependent dimerization and activation explored by NMR and X-ray crystallography

Ferric uptake regulator (Fur) is a global bacterial regulator that uses iron as a cofactor to bind to specific DNA sequences. Escherichia coli Fur is usually isolated as a homodimer with two metal sites per subunit. Metal binding to the iron site induces protein activation; however the exact role of the structural zinc site is still unknown. Structural studies of three different forms of the Escherichia coli Fur protein (nonactivated dimer, monomer, and truncated Fur-(1-82)) were performed. Dimerization of the oxidized monomer was followed by NMR in the presence of a reductant (dithiothreitol) and Zn(II). Reduction of the disulfide bridges causes only local structure variations, whereas zinc addition to reduced Fur induces protein dimerization. This demonstrates for the first time the essential role of zinc in the stabilization of the quaternary structure. The secondary structures of the mono- and dimeric forms are almost conserved in the N-terminal DNA-binding domain, except for the first helix, which is not present in the nonactivated dimer. In contrast, the C-terminal dimerization domain is well structured in the dimer but appears flexible in the monomer. This is also confirmed by heteronuclear Overhauser effect data. The crystal structure at 1.8A resolution of a truncated protein (Fur-(1-82)) is described and found to be identical to the N-terminal domain in the monomeric and in the metal-activated state. Altogether, these data allow us to propose an activation mechanism for E. coli Fur involving the folding/unfolding of the N-terminal helix.     

TLR7 ligands induce higher IFN-alpha production in females

IFN-alpha exercises multiple immune modulatory and antiviral activities and has been suggested to play a critical role in the pathogenesis of systemic lupus erythematosus (SLE). Plasmacytoid dendritic cells (pDCs) release IFN-alpha upon TLR7 and TLR9 ligation. With respect to the nine times higher incidence of SLE in women and the clinical use of synthetic TLR ligands as novel immune adjuvants, we analyzed IFN-alpha and TNF-alpha production in healthy human individuals. Blood samples were incubated with synthetic TLR7 and TLR9 ligands. In three independent groups (n(1) = 120, n(2) = 101, and n(3) = 123), analysis revealed a capacity of female PBLs to produce significantly higher IFN-alpha levels after TLR7 stimulation (p(1) < 0.0000001, p(2) < 0.0000001, and p(3) < 0.0001) compared with male PBLs. In contrast, no sex differences were evident after TLR9 stimulation. TNF-alpha production after TLR7 stimulation and also total pDC numbers were not different between females and males. X-inactivation escape of the TLR7 gene was investigated in monoclonal B cell lines and, independently, in pDCs after cell sorting and single-cell picking, indicating regular silencing of one TLR7 allele in females. Additionally, exogenous 17beta-estrogen and estrogen receptor antagonism did not indicate a significant role on TLR7-induced IFN-alpha production. Our data reveal for the first time a profound sex-dependent pathway of TLR7-induced IFN-alpha with higher production in females. These findings may explain the higher prevalence of SLE in females and the reported decreased therapeutic efficacy of synthetic TLR7 ligands in male individuals.     

Missense mutations in the catalase-peroxidase gene, katG, are associated with isoniazid resistance in Mycobacterium tuberculosis

The toxicity of the powerful anti-tuberculosis drug isoniazid (INH) is believed to be mediated by the haem-containing enzyme catalase-peroxidase, encoded by the katG gene of Mycobacterium tuberculosis. Compelling evidence for this was obtained by studying a panel of INH-resistant clinical isolates using a novel strategy based on the polymerase chain reaction and single-strand-conformation polymorphism analysis (PCR-SSCP) to detect mutations in katG. In most cases INH resistance was associated with missense mutations while in a small number of strains the gene had been completely, or partially, deleted. The missense mutations fell into two groups, the larger of which contained several independent mutations that affected the N-terminal peroxidase domain of the protein, resulting in the production of a catalase peroxidase with strongly reduced enzyme activity and increased heat lability. The effects of these substitutions could be interpreted by means of molecular modelling using the crystal structure of the related enzyme cytochrome c peroxidase from yeast as a template. The second group comprises a frequently occurring amino acid substitution and a single mutation that are both located in the C-terminal domain but do not noticeably alter either enzyme activity or heat stability.     

Thidiazuron-induced high frequency of shoot induction and plant regeneration in protoplast derived pea callus

Protoplasts isolated from lateral shoot buds of cotyledon-free pea embryo axes were regenerated to callus. Protoplast derived calluses with a diameter of about 1cm were transferred to shoot induction media, containing different concentrations (1–50µM) of thidiazuron. Shoot formation was observed after 16 weeks up to 12% efficiency. Thidiazuron (10µM) was the most effective concentration in all experiments. Shoot buds elongated in medium supplemented with N-isopentenyl adenine and indole-3-butyric acid. Since rooting was almost impossible in these thidiazuron-induced shoots, shoots were grafted onto young pea seedlings and regenerated to fertile plants.Abbreviations 2ip N-isopentenyl adenine - IAA indole-3-acetic acid - IBA indole-3-butyric acid - MES 2-(Nmorpholino)ethane acid - NAA naphthaleneacetic acid - TDZ thidiazuron - BAP 6-benzylaminopurine - PEG polyethylene glycol