Stereocontrolled routes to cis-hydroxyamino sugars, part VII: synthesis of daunosamine and ristosamine

The nitrogen of an allylic amine can serve as the fulcrum for stereocontrolled delivery of oxygen to an adjacent trigonal site, and cis-hydroxyamino sugars can thus be prepared. Methods for achieving the complementary procedure, namely, control of the delivery of nitrogen to an adjacent site by an allylic oxygen, are described. For example, treatment of methyl 2,3,6-trideoxy-- -erythro-hex-2-enopyranoside with trichloroacetonitrile gave an imidate ester which reacted with iodonium dicollidine perchlorate to give 2-trichloromethyl-(methyl 2,3,4,6-tetradeoxy-2-iodo-- -altropyranoside)-[3,4-d]-2-oxazoline. Exhaustive reductive dehalogenation of this product followed by hydrolysis led to methyl N-acetyl-- -ristosaminide. An analogous series of reactions was used to prepare the corresponding daunosaminide.     

Essential role for IKKβ in production of type 1 interferons by plasmacytoid dendritic cells

Plasmacytoid dendritic cells (pDCs) are characterized by their ability to produce high levels of type 1 interferons in response to ligands that activate TLR7 and TLR9, but the signaling pathways required for IFN production are incompletely understood. Here we exploit the human pDC cell line Gen2.2 and improved pharmacological inhibitors of protein kinases to address this issue. We demonstrate that ligands that activate TLR7 and TLR9 require the TAK1-IKKβ signaling pathway to induce the production of IFNβ via a pathway that is independent of the degradation of IκBα. We also show that IKKβ activity, as well as the subsequent IFNβ-stimulated activation of the JAK-STAT1/2 signaling pathway, are essential for the production of IFNα by TLR9 ligands. We further show that TLR7 ligands CL097 and R848 fail to produce significant amounts of IFNα because the activation of IKKβ is not sustained for a sufficient length of time. The TLR7/9-stimulated production of type 1 IFNs is inhibited by much lower concentrations of IKKβ inhibitors than those needed to suppress the production of NFκB-dependent proinflammatory cytokines, such as IL-6, suggesting that drugs that inhibit IKKβ may have a potential for the treatment of forms of lupus that are driven by self-RNA and self-DNA-induced activation of TLR7 and TLR9, respectively.     

The larva of Rhyacophila ferox Graf, 2006 (Trichoptera: Rhyacophilidae) from the Eastern Alps (Carinthia,Austria)

The hitherto unknown larva of Rhyacophila ferox Graf, 2006, is described and discussed in the context of contemporary Rhyacophilidae keys. In addition, zoogeographical and ecological notes are included.     

The impact of global climate change on genetic diversity within populations and species

Genetic diversity provides the basic substrate for evolution, yet few studies assess the impacts of global climate change (GCC) on intraspecific genetic variation. In this review, we highlight the importance of incorporating neutral and non‐neutral genetic diversity when assessing the impacts of GCC, for example, in studies that aim to predict the future distribution and fate of a species or ecological community. Specifically, we address the following questions: Why study the effects of GCC on intraspecific genetic diversity? How does GCC affect genetic diversity? How is the effect of GCC on genetic diversity currently studied? Where is potential for future research? For each of these questions, we provide a general background and highlight case studies across the animal, plant and microbial kingdoms. We further discuss how cryptic diversity can affect GCC assessments, how genetic diversity can be integrated into studies that aim to predict species' responses on GCC and how conservation efforts related to GCC can incorporate and profit from inclusion of genetic diversity assessments. We argue that studying the fate of intraspecifc genetic diversity is an indispensable and logical venture if we are to fully understand the consequences of GCC on biodiversity on all levels.     

Environmental and spatial characterisation of an unknown fauna using DNA sequencing – an example with Himalayan Hydropsychidae (Insecta: Trichoptera)

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Candidate Gene Identification with SNP Marker-Based Fine Mapping of Anthracnose Resistance Gene Co-4 in Common Bean

Anthracnose, caused by Colletotrichum lindemuthianum, is an important fungal disease of common bean (Phaseolus vulgaris). Alleles at the Co–4 locus confer resistance to a number of races of C. lindemuthianum. A population of 94 F_4:5 recombinant inbred lines of a cross between resistant black bean genotype B09197 and susceptible navy bean cultivar Nautica was used to identify markers associated with resistance in bean chromosome 8 (Pv08) where Co–4 is localized. Three SCAR markers with known linkage to Co–4 and a panel of single nucleotide markers were used for genotyping. A refined physical region on Pv08 with significant association with anthracnose resistance identified by markers was used in BLAST searches with the genomic sequence of common bean accession G19833. Thirty two unique annotated candidate genes were identified that spanned a physical region of 936.46 kb. A majority of the annotated genes identified had functional similarity to leucine rich repeats/receptor like kinase domains. Three annotated genes had similarity to 1, 3-β-glucanase domains. There were sequence similarities between some of the annotated genes found in the study and the genes associated with phosphoinositide-specific phosphilipases C associated with Co-x and the COK–4 loci found in previous studies. It is possible that the Co–4 locus is structured as a group of genes with functional domains dominated by protein tyrosine kinase along with leucine rich repeats/nucleotide binding site, phosphilipases C as well as β-glucanases.     

Assessing the phylogeographic history of the montane caddisfly Thremma gallicum using mitochondrial and restriction‐site‐associated DNA (RAD) markers

Repeated Quaternary glaciations have significantly shaped the present distribution and diversity of several European species in aquatic and terrestrial habitats. To study the phylogeography of freshwater invertebrates, patterns of intraspecific variation have been examined primarily using mitochondrial DNA markers that may yield results unrepresentative of the true species history. Here, population genetic parameters were inferred for a montane aquatic caddisfly, Thremma gallicum, by sequencing a 658‐bp fragment of the mitochondrial CO1 gene, and 12,514 nuclear RAD loci. T. gallicum has a highly disjunct distribution in southern and central Europe, with known populations in the Cantabrian Mountains, Pyrenees, Massif Central, and Black Forest. Both datasets represented rangewide sampling of T. gallicum. For the CO1 dataset, this included 352 specimens from 26 populations, and for the RAD dataset, 17 specimens from eight populations. We tested 20 competing phylogeographic scenarios using approximate Bayesian computation (ABC) and estimated genetic diversity patterns. Support for phylogeographic scenarios and diversity estimates differed between datasets with the RAD data favouring a southern origin of extant populations and indicating the Cantabrian Mountains and Massif Central populations to represent highly diverse populations as compared with the Pyrenees and Black Forest populations. The CO1 data supported a vicariance scenario (north–south) and yielded inconsistent diversity estimates. Permutation tests suggest that a few hundred polymorphic RAD SNPs are necessary for reliable parameter estimates. Our results highlight the potential of RAD and ABC‐based hypothesis testing to complement phylogeographic studies on non‐model species.     

Effects of chilling on the biochemical and functional properties of thylakoid membranes

The mechanism of chilling resistance was investigated in 4-week-old plants of the chilling-sensitive cultivated tomato, Lycopersicon esculentum Mill. cv H722, and rooted cuttings of its chilling-resistant wild relative, L. hirsutum Humb. and Bonpl., which were chilled for 3 days at 2°C with a 14-hour photoperiod and light intensity of 250 micromoles per square meter per second. This chilling stress reduced the chlorophyll fluorescence ratio, stomatal conductance, and dry matter accumulation more in the sensitive L. esculentum than in the resistant L. hirsutum. Photosynthetic CO₂ uptake at the end of the chilling treatment was reduced more in the resistant L. hirsutum than in L. esculentum, but recovered at a faster rate when the plants were returned to 25°C. The reduction of the spin trap, Tiron, by isolated thylakoids at 750 micromoles per square meter per second light intensity was taken as a relative indication of the tendency for the thylakoids to produce activated oxygen. Thylakoids isolated from the resistant L. hirsutum with or without chilling treatment were essentially similar, whereas those from chilled leaves of L. esculentum reduced more Tiron than the nonchilled controls. Whole chain photosynthetic electron transport was measured on thylakoids isolated from chilled and control leaves of the two species at a range of assay temperatures from 5 to 25°C. In both species, electron transport of the thylakoids from chilled leaves was lower than the controls when measured at 25°C, and electron transport declined as the assay temperature was reduced. However, the temperature sensitivity of thylakoids from chilled L. esculentum was altered such that at all temperatures below 20°C, the rate of electron transport exceeded the control values. In contrast, the thylakoids from chilled L. hirsutum maintained their temperature sensitivity, and the electron transport rates were proportionately reduced at all temperatures. This sublethal chilling stress caused no significant changes in thylakoid galactolipid, phospholipid, or protein levels in either species. Nonchilled thylakoid membranes from L. hirsutum had fourfold higher levels of the fatty acid 16:1, than those from L. esculentum. Chilling caused retailoring of the acyl chains in L. hirsutum but not in L. esculentum. The chilling resistance of L. hirsutum may be related to an ability to reduce the potential for free radical production by close regulation of electron transport within the chloroplast.     

A comparison of anther and microspore culture as a breeding tool in Brassica napus

Summary A direct comparison of microspore culture and anther culture was made in Brassica napus using F₁ crosses of Regent (canola) by Golden (rapeseed), and their reciprocals, as well as a hybrid between Reston and a highly embryogenic, canola-quality breeding line (G231) as donor plants. The study confirmed that microspore culture can be ten times more efficient than anther culture for embryo production. Embryo yields from cultures initiated from the Reston x G231 were four-fold greater than those initiated from the Regent x Golden crosses, and significant differences were also detected among cultures initiated from the different Regent x Golden crosses. These results illustrate the influence that donor plant genotype has on embryo production. However, superior embryogenic potential among donor material was not always coincident with superior plant production. The average haploid-todiploid ratio in microspore-derived regenerates was 21 for the population obtained from the Regent x Golden crosses but 11 for the Reston x G231 cross. For both types of material, the frequency of diploids increased upon repeated cycles of explanting. A field study showed that there were no differences between the populations of anther-derived and microspore-derived spontaneous diploid and doubled haploid lines, with respect to the days required for them to flower or to mature. The information is valuable for canola breeding programs considering the use of haploidy.