A new strategy for the detection of subtelomeric rearrangements

We present a new strategy for the detection of subtelomeric rearrangements. This approach is based on two hybridizations with different probe sets. The first set consists of microdissected subtelomeric probes (each 5-10 megabases in size) labeled combinatorially employing 7 different fluorochromes. With this set, subtelomeric interchromosomal exchanges can be detected in a 24-color experiment. The second set comprises a second generation of subtelomeric PAC-, P1- and BAC-clones. Probes for p- and q-arms are labeled with two different colors. This second set detects small deletions; in addition it provides regional information, so that translocated material identified by the first probe set can be assigned to the p- or q-arm of a chromosome. The test has been evaluated in a blind study on a series of subtle translocations and deletions.     

Enhancement of the steady-state magnetization in TROSY experiments

Under the condition that the longitudinal relaxation time of spin I is shorter than the longitudinal relaxation time of spin S the steady-state magnetization in [S,I]-TROSY-type experiments can be enhanced by intermediate storage of a part of the steady-state magnetization of spin I on spin S with a pulse sequence element during the relaxation delay. It is demonstrated with samples ranging in size from the 1 kDa cyclosporin to the 110 kDa ¹⁵N,²H-labeled dihydroneopterin Aldolase that intermediate storage of steady-state magnetization in a [¹⁵N,¹H]-TROSY experiment yields a signal gain of 10–25%. The method proposed here for intermediate storage of steady-state magnetization can be implemented in any [¹⁵N,¹H]-TROSY-type experiments.     

Serratia marcescens forms a new type of cytolysin

Most Serratia marcescens strains produce a new type of cytolysin (hemolysin) which is also found in other Serratia species. The hemolytic polypeptide ShlA (M(r) 162 101) is secreted across the outer membrane through the help of the ShlB protein which also involves conversion of an inactive precursor in an hemolytically active form. Both proteins are synthesized with signal sequences which are released during export across the cytoplasmic membrane. Mutants expressing inactive ShlB derivatives are impaired in activation and secretion suggesting a tight coupling between both processes. The region of ShlA for activation and secretion is confined to the N-terminal 16% of the polypeptide which contains the sequence NPNG which is also found in the Proteus hemolysin, the Bordetella pertussis filamentous hemagglutinin and two highly expressed outer membrane proteins of Haemophilus influenzae. Substitution of the first asparagine (N) residue by isoleucine converts the Serratia hemolysin into an inactive secretion incompetent form. It is concluded that this region is recognized by ShlB for activation and secretion of ShlA. The Serratia hemolysin forms defined pores in erythrocyte membranes.     

Chromosomal studies of leukemic and preleukemic Fanconi's anemia patients

Summary Cytogenetic studies of three Fanconi's anemia patients are reported, one of the patients having erythroleukemia, the other two preleukemia. Clonal abnormalities were present in all three cases. Partial chromosomal duplication uncommon in other leukemias was observed. Partial duplication of the long arm of chromosome 3 has been observed in the present case of erythroleukemia examined as well as in a previously reported one.     

Site of synthesis of geranylgeraniol derivatives in intact spinach chloroplasts

Chloroplasts isolated from fully developed spinach leaves and incubated in the presence of isopentenyl pyrophosphate were able to synthesize rapidly geranylgeranyl chlorophyll a and geranylgeraniol.The biosynthesis of the geranylgeraniol derivatives from isopentenyl pyrophosphate is a compartimentalized process. The membrane fractions (thylakoid and envelope membranes) were essentially unable to synthesize geranylgeraniol, geranylgeranyl pyrophosphate and geranylgeranyl chlorophyll a. When stromal and thylakoid fractions were combined the capacity to synthesize geranylgeranyl chlorophyll a and geranylgeraniol was restored. When stromal and envelope membrane fractions were combined the capacity to synthesize geranylgeranyl pyrophosphate and geranylgeraniol was restored. The products of the reaction were discharged inside the lipid phase of the membranes.     

Future Climate Change Will Favour Non-Specialist Mammals in the (Sub)Arctics

Arctic and subarctic (i.e., [sub]arctic) ecosystems are predicted to be particularly susceptible to climate change. The area of tundra is expected to decrease and temperate climates will extend further north, affecting species inhabiting northern environments. Consequently, species at high latitudes should be especially susceptible to climate change, likely experiencing significant range contractions. Contrary to these expectations, our modelling of species distributions suggests that predicted climate change up to 2080 will favour most mammals presently inhabiting (sub)arctic Europe. Assuming full dispersal ability, most species will benefit from climate change, except for a few cold-climate specialists. However, most resident species will contract their ranges if they are not able to track their climatic niches, but no species is predicted to go extinct. If climate would change far beyond current predictions, however, species might disappear. The reason for the relative stability of mammalian presence might be that arctic regions have experienced large climatic shifts in the past, filtering out sensitive and range-restricted taxa. We also provide evidence that for most (sub)arctic mammals it is not climate change per se that will threaten them, but possible constraints on their dispersal ability and changes in community composition. Such impacts of future changes in species communities should receive more attention in literature.     

Parametric and Parametrically Smoothed Distribution-Free Proportional Hazard Models with Discrete Data

This paper discusses discrete time proportional hazard models and suggests a new class of flexible hazard functions. Explicitly modeling the discreteness of data is important since standard continuous models are biased; allowing for flexibility in the hazard estimation is desirable since strong parametric restrictions are likely to be similarly misleading. Simulation compare continuous and discrete models when data are generated by grouping and demonstrate that simple approximations recover underlying hazards well and outperform nonparametric maximum likelihood estimates in term of mean squared error.