PpASCL, a moss ortholog of anther-specific chalcone synthase-like enzymes, is a hydroxyalkylpyrone synthase involved in an evolutionarily conserved sporopollenin biosynthesis pathway

Sporopollenin is the main constituent of the exine layer of spore and pollen walls. Recently, several Arabidopsis genes, including polyketide synthase A (PKSA), which encodes an anther-specific chalcone synthase-like enzyme (ASCL), have been shown to be involved in sporopollenin biosynthesis. The genome of the moss Physcomitrella patens contains putative orthologs of the Arabidopsis sporopollenin biosynthesis genes. We analyzed available P.patens expressed sequence tag (EST) data for putative moss orthologs of the Arabidopsis genes of sporopollenin biosynthesis and studied the enzymatic properties and reaction mechanism of recombinant PpASCL, the P.patens ortholog of Arabidopsis PKSA. We also generated structure models of PpASCL and Arabidopsis PKSA to study their substrate specificity. Physcomitrella patens orthologs of Arabidopsis genes for sporopollenin biosynthesis were found to be expressed in the sporophyte generation. Similarly to Arabidopsis PKSA, PpASCL condenses hydroxy fatty acyl-CoA esters with malonyl-CoA and produces hydroxyalkyl α-pyrones that probably serve as building blocks of sporopollenin. The ASCL-specific set of Gly-Gly-Ala residues predicted by the models to be located at the floor of the putative active site is proposed to serve as the opening of an acyl-binding tunnel in ASCL. These results suggest that ASCL functions together with other sporophyte-specific enzymes to provide polyhydroxylated precursors of sporopollenin in a pathway common to land plants.     

Comparison of a bacteriophage-delivered DNA vaccine and a commercially available recombinant protein vaccine against hepatitis B

A bacteriophage lambda DNA vaccine expressing the small surface antigen (HBsAg) of hepatitis B was compared with Engerix B, a commercially available vaccine based on the homologous recombinant protein (r-HBsAg). Rabbits (five per group) were vaccinated intramuscularly at weeks 0, 5 and 10. Antibody responses against r-HBsAg were measured by indirect enzyme-linked immunosorbent assay, by limiting dilutions and by subtyping. Specific lymphocyte proliferation in vitro was also measured. After one vaccination, three of the five phage-vaccinated rabbits showed a strong antibody response, whereas no r-HBsAg-vaccinated animals responded. Following two vaccinations, all phage-vaccinated animals responded and antibody levels remained high throughout the experiment (220 days total). By 2 weeks after the second vaccination, antibody responses were significantly higher (P<0.05) in the phage-vaccinated group in all tests. After three vaccinations, one out of five r-HBsAg-vaccinated rabbit still failed to respond. The recognized correlate of protection against hepatitis B infection is an antibody response against the HBsAg antigen. When combined with the fact that phage vaccines are potentially cheap to produce and stable at a range of temperatures, the results presented here suggest that further studies into the use of phage vaccination against hepatitis B are warranted.     

Verlust des Sensibilitäts- und Schmerzempfindens

The sensory nervous system detects pressure, touch, stretching, heat, and cold and translates these stimuli into action potentials. To protect the body from tissue damage acute pain is felt when a stimulus gains a critical intensity. The combination of impaired nociception and autonomic dysfunction is the hallmark of hereditary sensory and autonomic neuropathies (HSAN). Sensory loss in HSAN patients results in ulcerations of hands and feet and may necessitate amputations. Congenital onset of HSAN leads to self-mutilating behavior in affected children. Degeneration of motor neurons can complicate the disease. HSAN is divided into five groups according to clinical symptoms. So far, nine genes have been identified as causative for the disorder. The present article reviews the clinical, genetic, and pathophysiological aspects of HSAN.     

Streptococcus pyogenes antigen I/II-family polypeptide AspA shows differential ligand-binding properties and mediates biofilm formation

The streptococcal antigen I/II (AgI/II)-family polypeptides are cell wall-anchored adhesins expressed by most indigenous oral streptococci. Proteins sharing 30-40% overall amino acid sequence similarities with AgI/II-family proteins are also expressed by Streptococcus pyogenes. The S. pyogenes M28_Spy1325 polypeptide (designated AspA) displays an AgI/II primary structure, with alanine-rich (A) and proline-rich (P) repeats flanking a V region that is projected distal from the cell. In this study it is shown that AspA from serotype M28 S. pyogenes, when expressed on surrogate host Lactococcus lactis, confers binding to immobilized salivary agglutinin gp-340. This binding was blocked by antibodies to the AspA-VP region. In contrast, the N-terminal region of AspA was deficient in binding fluid-phase gp-340, and L. lactis cells expressing AspA were not agglutinated by gp-340. Deletion of the aspA gene from two different M28 strains of S. pyogenes abrogated their abilities to form biofilms on saliva-coated surfaces. In each mutant strain, biofilm formation was restored by trans complementation of the aspA deletion. In addition, expression of AspA protein on the surface of L. lactis conferred biofilm-forming ability. Taken collectively, the results provide evidence that AspA is a biofilm-associated adhesin that may function in host colonization by S. pyogenes.     

The Stranding Anomaly as Population Indicator: The Case of Harbour Porpoise Phocoena phocoena in North-Western Europe

Ecological indicators for monitoring strategies are expected to combine three major characteristics: ecological significance, statistical credibility, and cost-effectiveness. Strategies based on stranding networks rank highly in cost-effectiveness, but their ecological significance and statistical credibility are disputed. Our present goal is to improve the value of stranding data as population indicator as part of monitoring strategies by constructing the spatial and temporal null hypothesis for strandings. The null hypothesis is defined as: small cetacean distribution and mortality are uniform in space and constant in time. We used a drift model to map stranding probabilities and predict stranding patterns of cetacean carcasses under H₀ across the North Sea, the Channel and the Bay of Biscay, for the period 1990–2009. As the most common cetacean occurring in this area, we chose the harbour porpoise Phocoena phocoena for our modelling. The difference between these strandings expected under H₀ and observed strandings is defined as the stranding anomaly. It constituted the stranding data series corrected for drift conditions. Seasonal decomposition of stranding anomaly suggested that drift conditions did not explain observed seasonal variations of porpoise strandings. Long-term stranding anomalies increased first in the southern North Sea, the Channel and Bay of Biscay coasts, and finally the eastern North Sea. The hypothesis of changes in porpoise distribution was consistent with local visual surveys, mostly SCANS surveys (1994 and 2005). This new indicator could be applied to cetacean populations across the world and more widely to marine megafauna.     

Mosaike bei monogenen Erkrankungen

Mosaicism is defined as the simultaneous presence of cells with different genotypes that originate from a common zygote. Mutations can either be present in germline or somatic cells. Monogenic disorders apparently caused by a de novo mutation may show a recurrence risk due to germline mosaicism in a parent. Duchenne muscular dystrophy is a well investigated example with a high frequency of germline mosaicism and the estimation for the risk of recurrence is based on theoretical models and empirical data. Recently, somatic mutations have been uncovered in various syndromic disorders, such as Proteus syndrome or hemimegalencephaly and respective mutations often show gain-of-function properties. Genetic testing is mainly based on next generation sequencing technologies but still remains challenging; however, detection of somatic mosaicism is expected to be of increasing relevance in the diagnosis of monogenic disorders. Somatic mosaicism may also play a hitherto underestimated role in common disorders.     

Occurrence of killer whale Orcinus orca rake marks on Eastern Canada-West Greenland bowhead whales Balaena mysticetus

Killer whales (Orcinus orca) are increasing in occurrence and residence time in the eastern Canadian Arctic (ECA) in part due to a decrease in sea ice associated with global climate change. Killer whales prey on bowhead whales (Balaena mysticetus) of the Eastern Canada-West Greenland (EC-WG) population, but their patterns of predation pressure and effect on the EC-WG population’s ability to recover from historical whaling remain unknown. We analyzed photographs of individual bowhead whale flukes from five regions within the EC-WG population’s geographic range (Cumberland Sound, Foxe Basin, Isabella Bay, Repulse Bay and Disko Bay), taken during 1986 and from 2007 to 2012, to estimate the occurrence of rake marks (parallel scars caused by killer whale teeth). Of 598 identified whales, 10.2 % bore rake marks from killer whales. A higher occurrence of rake marks was found in Repulse and Disko Bays, where primarily adult bowhead whales occur seasonally, than in Foxe Basin, where juveniles and females with calves occur. Older bowheads, which have had greater exposure time to killer whales due to their age, had higher occurrences of rake marks than juveniles and calves, which may indicate that younger whales do not survive killer whale attacks. A high proportion of adult females also had rake marks, perhaps due to protecting their calves from killer whale predation. In order to quantify the effect of killer whales on EC-WG population recovery, further research is needed on the relationship between the occurrence of rake marks and bowhead adult, calf, and juvenile mortality in the ECA, as well as more information about Arctic killer whale ecology.     

Structure and function of clostridial phospholipases C

A range of clostridial species produce phospholipases C. The zinc metallo phospholipases C have related sequences but different properties. All of these enzymes may be arranged, like alpha-toxin as two-domain proteins. Differences in enzymatic, haemolytic and toxic properties may be explained by differences in amino acids at key positions.     

Functional proteomics approach to investigate the biological activities of cDNAs implicated in breast cancer

Functional proteomics approaches that comprehensively evaluate the biological activities of human cDNAs may provide novel insights into disease pathogenesis. To systematically investigate the functional activity of cDNAs that have been implicated in breast carcinogenesis, we generated a collection of cDNAs relevant to breast cancer, the Breast Cancer 1000 (BC1000), and conducted screens to identify proteins that induce phenotypic changes that resemble events which occur during tumor initiation and progression. Genes were selected for this set using bioinformatics and data mining tools that identify genes associated with breast cancer. Greater than 1000 cDNAs were assembled and sequence verified with high-throughput recombination-based cloning. To our knowledge, the BC1000 represents the first publicly available sequence-validated human disease gene collection. The functional activity of a subset of the BC1000 collection was evaluated in cell-based assays that monitor changes in cell proliferation, migration, and morphogenesis in MCF-10A mammary epithelial cells expressing a variant of ErbB2 that can be inducibly activated through dimerization. Using this approach, we identified many cDNAs, encoding diverse classes of cellular proteins, that displayed activity in one or more of the assays, thus providing insights into a large set of cellular proteins capable of inducing functional alterations associated with breast cancer development.