Localization and Characterization of a Novel 20 kDa Polypeptide in the Chloroplast of the Green Alga Dunaliella salina

Recent work with the green alga Dunaliella salina showed thepresence of a {small tilde}20 kDa chloroplast protein that wasrecognized by polyclonal antibodies raised against the isolatedLHC-II [Webb M.R. and Melis A. (1995) Plant Physiol. 107: 885].In this report, a characterization of the {small tilde}20 kDapolypeptide is presented. It is shown that it is localized inthe chloroplast envelope membrane of D. salina. The abundanceof this protein is constant on a per cell basis and independentof the light regime during cell growth. The {small tilde}20kDa polypeptide is easily degraded to a {small tilde}19 kDaproduct during sample preparation. A limited amino acid sequenceof 21 residues from the free N-terminus of the {small tilde}19kDa product was obtained. On the basis of this partial sequence,it was concluded that the {small tilde}20 kDa polypeptide isnot a degradation product of a known LHC-II but rather a novelprotein. The {small tilde}20kDa polypeptide did not cross-reactwith antibodies raised against the Cbr (carotene biosynthesis-related)gene product and showed a different electrophoretic mobilityfrom the latter. Light-shift experiments suggest that the {smalltilde}20 kDa polypeptide is not an ELIP (early light-inducibleprotein). Possible functions of the {small tilde}20 kDa proteinare discussed. ¹Permanent address: Department of Biochemistry, University oflund, PO Box 124, S-221 00 Lund, Sweden     

Telomere length in relation to colour polymorphism across life stages in the tawny owl

Telomere erosion has been proposed to be tightly associated with senescence, environmental stressors and life history trade‐offs. How telomere dynamics vary across life stages and especially in relation to (heritable) phenotypic traits is still unclear. The tawny owl Strix aluco display a highly heritable melanin‐based colour polymorphism, a grey and a brown morph, linked to several fitness traits including morph‐specific telomere dynamics. As adults, brown tawny owls have shorter relative telomere length (RTL) and exhibit faster telomere shortening rate than grey owls. Here we test if these morph‐specific telomere dynamics emerge already during growth, or if they are induced only in adult life through differential physiological costs associated with the life history of the morphs. We analysed RTL from 287 tawny owl offspring and 81 first breeding adults to evaluate at what life stage morph‐specific patterns emerge. We found no differences in RTL between the two morphs during the nestling period nor at the first breeding attempt. Sex, brood size or size rank in the nest did not affect offspring RTL. Among first‐breeders, females had shorter telomeres than males suggesting a sampling‐time dependent difference in reproductive costs between sexes, due to the prominent sex roles in tawny owls in the early nestling period. The probability to return to breed after the first breeding attempt was not affected by RTL, sex or colour morph. The lack of morph‐specific difference in RTL among nestlings and first breeders suggests that previously observed morph‐specific differences in RTL dynamics in adults emerge at the onset of the breeding career and is likely due to different physiological profiles and life‐history strategies adopted by adults. We conclude that different telomere dynamics and senescence patterns among highly heritable phenotypes (colour morphs) are likely to be a result of differential costs of reproduction and self‐maintenance.     

Genetic structure of Hypochaeris uniflora (Asteraceae) suggests vicariance in the Carpathians and rapid post-glacial colonization of the Alps from an eastern Alpine refugium

Aim The range of the subalpine species Hypochaeris uniflora covers the Alps, Carpathians and Sudetes Mountains. Whilst the genetic structure and post‐glacial history of many high‐mountain plant taxa of the Alps is relatively well documented, the Carpathian populations have often been neglected in phylogeographical studies. The aim of the present study is to compare the genetic variation of the species in two major European mountain systems – the Alps and the Carpathians. Location Alps and Carpathians. Methods The genetic variation of 77 populations, each consisting of three plants, was studied using amplified fragment length polymorphism (AFLP). Results Neighbour joining and principal coordinate analyses revealed three well‐supported phylogeographical groups of populations corresponding to three disjunct geographical regions – the Alps and the western and south‐eastern Carpathians. Moreover, two further clusters could be distinguished within the latter mountain range, one consisting of populations from the eastern Carpathians and the second consisting of populations from the southern Carpathians. Populations from the Apuseni Mountains had an intermediate position between the eastern and southern Carpathians. The genetic clustering of populations into four groups was also supported by an analysis of molecular variance, which showed that most genetic variation (almost 46%) was found among these four groups. By far the highest within‐population variation was found in the eastern Carpathians, followed by populations from the southern and western Carpathians. Generally, the populations from the Alps were considerably less variable and displayed substantially fewer region‐diagnostic markers than those from the south‐eastern Carpathians. Although no clear geographical structure was found within the Alps, based on neighbour joining or principal coordinate analyses, some trends were obvious: populations from the easternmost part were genetically more variable and, together with those from the south‐western part, exhibited a higher proportion of rare AFLP fragments than populations in other areas. Moreover, the total number of AFLP fragments per population, the percentage of polymorphic loci and the proportion of rare AFLP fragments significantly decreased from east to west. Main conclusions Deep infraspecific phylogeographical gaps between the populations from the Alps and the western and south‐eastern Carpathians suggest the survival of H. uniflora in three separate refugia during the last glaciation. Our AFLP data provide molecular evidence for a long‐term geographical disjunction between the eastern and western Carpathians, previously suggested from the floristic composition at the end of 19th century. It is likely that Alpine populations survived the Last Glacial in the eastern part of the Alps, from where they rapidly colonized the rest of the Alps after the ice sheet retreated. Multiple founder effects may explain a gradual loss of genetic variation during westward colonization of the Alps.     

Production of ethanol and biomass from thin stillage by Neurospora intermedia: A pilot study for process diversification

Dry mill ethanol processes produce ethanol and animal feed from whole grains, where the wastewater after the distillation and separation of solid materials is called “thin stillage.” In this work, similar production of ethanol (3.5 g/L) and biomass (5 g/L) from thin stillage was obtained during batch cultivation of the edible fungus Neurospora intermedia in a 2‐m high airlift reactor and bubble column. The fungal biomass, containing 50% w/w protein and 12% w/w lipids, was rich in essential amino acids and omega‐3 and ‐6 fatty acids. In a continuous mode of fermentation, dilution rates of up to 0.2 h^?1 could be applied without cell washout in the bubble column at 0.5 vvm. At 0.1 h^?1, around 5 g/L of ethanol and 4 g/L of biomass containing ca. 50% w/w protein were produced. The fungus was able to assimilate saccharides in the liquid fraction as well as sugar backbones such as xylan and arabinan in the solid fraction. The inclusion of the current process could potentially lead to the production of 11 000 m³ of ethanol (5.5% improvement vs. normal industrial process) and around 6300 tons of high‐quality biomass for animal feed at a typical facility producing 200 000 m³ ethanol per year.     

Revealing Different Roles of the mTOR-Targets S6K1 and S6K2 in Breast Cancer by Expression Profiling and Structural Analysis

Background

The AKT/mTORC1/S6K pathway is frequently overstimulated in breast cancer, constituting a promising therapeutic target. The benefit from mTOR inhibitors varies, likely as a consequence of tumour heterogeneity, and upregulation of several compensatory feed-back mechanisms. The mTORC1 downstream effectors S6K1, S6K2, and 4EBP1 are amplified and overexpressed in breast cancer, associated with a poor outcome and divergent endocrine treatment benefit. S6K1 and S6K2 share high sequence homology, but evidence of partly distinct biological functions is emerging. The aim of this work was to explore possible different roles and treatment target potentials of S6K1 and S6K2 in breast cancer.

Materials and methods

Whole-genome expression profiles were compared for breast tumours expressing high levels of S6K1, S6K2 or 4EBP1, using public datasets, as well as after in vitro siRNA downregulation of S6K1 and/or S6K2 in ZR751 breast cancer cells. In silico homology modelling of the S6K2 kinase domain was used to evaluate its possible structural divergences to S6K1.

Results

Genome expression profiles were highly different in S6K1 and S6K2 high tumours, whereas S6K2 and 4EBP1 profiles showed significant overlaps, both correlated to genes involved in cell cycle progression, among these the master regulator E2F1. S6K2 and 4EBP1 were inversely associated with IGF1 levels, and their prognostic value was shown to be restricted to tumours positive for IGFR and/or HER2. In vitro, S6K1 and S6K2 silencing resulted in upregulation of genes in the mTORC1 and mTORC2 complexes. Isoform-specific silencing also showed distinct patterns, e.g. S6K2 downregulation lead to upregulation of several cell cycle associated genes. Structural analyses of the S6K2 kinase domain showed unique structure patterns, deviating from those of S6K1, facilitating the development of isoform-specific inhibitors. Our data support emerging proposals of distinct biological features of S6K1 and S6K2, suggesting their importance as separate oncogenes and clinical markers, where specific targeting in different breast cancer subtypes could facilitate further individualised therapies.     

Loop migration in adult marsh harriers Circus aeruginosus,as revealed by satellite telemetry

Loop migration among birds is characterized by the spring route lying consistently west or east of the autumn route. The existence of loops has been explained by general wind conditions or seasonal differences in habitat distribution. Loop migration has predominantly been studied at the population level, for example by analysing ring recoveries. Here we study loop migration of individual marsh harriers Circus aeruginosus tracked by satellite telemetry. We show that despite a generally narrow migration corridor the harriers travelled in a distinct clockwise loop through Africa and southern Europe, following more westerly routes in spring than in autumn. We used the Normalized Difference Vegetation Index (NDVI) to identify potential feeding habitat in Africa. Suitable habitat seemed always more abundant along the western route, both in spring and autumn, and no important stopover site was found along the eastern route. Observed routes did thus not coincide with seasonal variation in habitat availability. However, favourable habitat might be more important during spring migration, when the crossing of the Sahara seems more challenging, and thus habitat availability might play an indirect role in the harriers’ route choice. Grid‐based wind data were used to reconstruct general wind patterns, and in qualitative agreement with the observed loop marsh harriers predominantly encountered westerly winds in Europe and easterly winds in Africa, both in autumn and in spring. By correlating tail‐ and crosswinds with forward and perpendicular movement rates, respectively, we show that marsh harriers are partially drifted by wind. Thus, we tentatively conclude that wind rather than habitat seems to have an overriding effect on the shape of the migration routes of marsh harriers. General wind conditions seem to play an important role also in the evolution of narrow migratory loops as demonstrated for individual marsh harriers.     

The effect of inbreeding on fluctuating asymmetry in Scabiosa canescens (Dipsacaceae)

Developmental instability and fluctuating asymmetry (FA) describe the inability of organisms to correct for random accidents under development and has become a major but controversial topic in evolutionary biology. Theoretical models predict that the level of FA should increase as a result of inbreeding, but empirical results are ambiguous. Moreover, the relationship between fitness and FA is still debated. In the current study, plants from a population of Scabiosa canescens, a locally rare species in southern Sweden, were raised under uniform growth conditions to examine the effects of one-generation of selfing and outcrossing on FA in flower morphology. The level of flower FA was significantly higher (p = 0.038) for inbred progeny than for offspring derived from outcross pollinations. Given that earlier studies of this species have found no negative relation between heterozygosity and FA, the results support the conclusion that expression of deleterious recessive alleles are responsible for the increase of FA. There was no correlation between FA and estimates of five fitness-related traits when estimated at the individual level. However, a companion study found significant inbreeding depression for all fitness traits, and a negative association between FA and fitness could therefore be asserted at the treatment level (inbred/outbred progeny). Hence, FA seems to be useful to predict inbreeding depression in S. canescens, but specific individuals with high fitness cannot be identified based on their FA levels.     

Geographic differences in genetic susceptibility to IgA nephropathy: GWAS replication study and geospatial risk analysis

IgA nephropathy (IgAN), major cause of kidney failure worldwide, is common in Asians, moderately prevalent in Europeans, and rare in Africans. It is not known if these differences represent variation in genes, environment, or ascertainment. In a recent GWAS, we localized five IgAN susceptibility loci on Chr.6p21 (HLA-DQB1/DRB1, PSMB9/TAP1, and DPA1/DPB2 loci), Chr.1q32 (CFHR3/R1 locus), and Chr.22q12 (HORMAD2 locus). These IgAN loci are associated with risk of other immune-mediated disorders such as type I diabetes, multiple sclerosis, or inflammatory bowel disease. We tested association of these loci in eight new independent cohorts of Asian, European, and African-American ancestry (N = 4,789), followed by meta-analysis with risk-score modeling in 12 cohorts (N = 10,755) and geospatial analysis in 85 world populations. Four susceptibility loci robustly replicated and all five loci were genome-wide significant in the combined cohort (P = 5×10⁻³²–3×10⁻¹⁰), with heterogeneity detected only at the PSMB9/TAP1 locus (I² = 0.60). Conditional analyses identified two new independent risk alleles within the HLA-DQB1/DRB1 locus, defining multiple risk and protective haplotypes within this interval. We also detected a significant genetic interaction, whereby the odds ratio for the HORMAD2 protective allele was reversed in homozygotes for a CFHR3/R1 deletion (P = 2.5×10⁻⁴). A seven–SNP genetic risk score, which explained 4.7% of overall IgAN risk, increased sharply with Eastward and Northward distance from Africa (r = 0.30, P = 3×10⁻¹²⁸). This model paralleled the known East–West gradient in disease risk. Moreover, the prediction of a South–North axis was confirmed by registry data showing that the prevalence of IgAN–attributable kidney failure is increased in Northern Europe, similar to multiple sclerosis and type I diabetes. Variation at IgAN susceptibility loci correlates with differences in disease prevalence among world populations. These findings inform genetic, biological, and epidemiological investigations of IgAN and permit cross-comparison with other complex traits that share genetic risk loci and geographic patterns with IgAN.