Control over Self‐Doping in High Band Gap Perovskite Films

It is reported how differences in the composition of high bandgap Pb bromide‐based perovskites affect their carrier diffusion length and junction type. Pb‐based, APbX₃, halide perovskite (HaP) films and devices are studied, where A can be a mixture of formamidinium, methylammonium (MA), and Cs, and X a mixture of Br and Cl, using a combination of dark‐ and photoconductivity and steady‐state photocarrier grating. The results show the cation and anion compositions affect both majority and minority carrier diffusion lengths. In particular, using electron beam‐induced current measurements, FTO\dTiO₂mp‐TiO₂HaP\PTAA (poly‐triarylamine)\Au devices are studied. The results enable identifying junction and built‐in voltage formation and track position and size of the space charge region width with changes in the HaP composition. As far as it is known, it is found for the first time that a mixed‐cation HaP forms a junction that has characteristics of a p‐i‐n one, with relatively long and comparable carrier diffusion lengths, while the single cation‐based bromide HaPs form clear p‐n junctions at the interface with the TiO₂ [pure CsPbBr₃ and MAPbBr₃(Cl)] or a buried one (MAPbBr₃) and shorter diffusion lengths. These differences are attributed to lower carrier density in MAPbBr₃, and especially in the mixed cation HaP, which is comparable to iodide‐based HaP films.     

Expression of <Emphasis Type="Italic">MAX2</Emphasis> under <Emphasis Type="Italic">SCARECROW</Emphasis> promoter enhances the strigolactone/MAX2 dependent response of <Emphasis Type="Italic">Arabidopsis</Emphasis> roots to low-phosphate conditions

Main conclusion

MAX2/strigolactone signaling in the endodermis and/or quiescent center of the root is partiallysufficient to exert changes in F-actin density and cellular trafficking in the root epidermis, and alter gene expression during plant response to low Pi conditions.Strigolactones (SLs) are a new group of plant hormones that regulate different developmental processes in the plant via MAX2, an F-box protein that interacts with their receptor. SLs and MAX2 are necessary for the marked increase in root-hair (RH) density in seedlings under conditions of phosphate (Pi) deprivation. This marked elevation was associated with an active reduction in actin-filament density and endosomal movement in root epidermal cells. Also, expression of MAX2 under the SCARECROW (SCR) promoter was sufficient to confer SL sensitivity in roots, suggesting that SL signaling pathways act through a root-specific, yet non-cell-autonomous regulatory mode of action. Here we show evidence for a non-cell autonomous signaling of SL/MAX2, originating from the root endodermis, and necessary for seedling response to conditions of Pi deprivation. SCR-derived expression of MAX2 in max2-1 mutant background promoted the root low Pi response, whereas supplementation of the synthetic SL GR24 to these SCR:MAX2 expressing lines further enhanced this response. Moreover, the SCR:MAX2 expression led to changes in actin density and endosome movement in epidermal cells and in TIR1 and PHO2 gene expression. These results demonstrate that MAX2 signaling in the endodermis and/or quiescent center is partially sufficient to exert changes in F-actin density and cellular trafficking in the epidermis, and alter gene expression under low Pi conditions.

     

Modulation of cellular disulfide-bond formation and the ER redox environment by feedback regulation of Ero1

Introduction of disulfide bonds into proteins entering the secretory pathway is catalyzed by Ero1p, which generates disulfide bonds de novo, and Pdi1p, which transfers disulfides to substrate proteins. A sufficiently oxidizing environment must be maintained in the endoplasmic reticulum (ER) to allow for disulfide formation, but a pool of reduced thiols is needed for isomerization of incorrectly paired disulfides. We have found that hyperoxidation of the ER is prevented by attenuation of Ero1p activity through noncatalytic cysteine pairs. Deregulated Ero1p mutants lacking certain cysteines show increased enzyme activity, a decreased lag phase in kinetic assays, and growth defects in vivo. We hypothesize that noncatalytic cysteine pairs in Ero1p sense the level of potential substrates in the ER and correspondingly modulate Ero1p activity as part of a homeostatic regulatory system governing the thiol-disulfide balance in the ER.     

FASH: A web application for nucleotides sequence search

   

FASH (Fourier Alignment Sequence Heuristics) is a web application, based on the Fast Fourier Transform, for finding remote homologs within a long nucleic acid sequence. Given a query sequence and a long text-sequence (e.g, the human genome), FASH detects subsequences within the text that are remotely-similar to the query. FASH offers an alternative approach to Blast/Fasta for querying long RNA/DNA sequences. FASH differs from these other approaches in that it does not depend on the existence of contiguous seed-sequences in its initial detection phase. The FASH web server is user friendly and very easy to operate.     

Acetohydroxyacid synthase from Mycobacterium avium and its inhibition by sulfonylureas and imidazolinones

Tuberculosis (TB) remains one of the world's leading causes of death from infectious disease. It is caused by infection with Mycobacterium tuberculosis or sometimes, particularly in immune-compromised patients, Mycobacterium avium. The aim of this study was to create a tool that could be used in the search for new anti-TB drugs that inhibit branched-chain amino acid (BCAA) biosynthesis, as these are essential amino acids that are not available to a mycobacterium during growth in an infected organism. To this end, we cloned, overexpressed, purified and characterised for the first time an acetohydroxyacid synthase (AHAS), a key enzyme in the pathway to the biosynthesis of the BCAAs, from the genus Mycobacterium. Nine commercial herbicides of the sulfonylurea and imidazolinone classes were tested for their influence on this enzyme. Four of the sulfonylureas were potent inhibitors of the enzyme. The relative potency of the different inhibitors towards the M. avium enzyme was unlike their potency towards other AHASs whose inhibitor profile has been reported, emphasising the advantage of using a mycobacterial enzyme as a tool in the search for new anti-TB drugs.     

Nutritional investigations and management of captive moose

Historically, moose have been difficult to maintain in captivity when on diets of grass or legume hays and grain due to enteritis that frequently leads to chronic diarrhea/wasting disease. The development of wood-fiber diets has increased the lifespan of moose in captivity, but these diets do not completely prevent chronic wasting. Purina Mills (St. Louis, MO) hypothesized that captive moose are unable to digest starch that escapes the rumen, and therefore abnormal bacterial fermentation in the hindgut causes chronic diarrhea. An earlier study found no evidence of a digestive problem, so we tested the hypothesis that moose have difficulty metabolizing excess propionate produced from the fermentation of starch found in traditional cervid rations and high-grain wood-fiber diets. When challenged with an i.v. propionate load, moose metabolized propionate similar to healthy mule deer and domestic livestock. We then tested the hypothesis that grass forage is an initiating factor to chronic diarrhea/wasting and further hypothesized that grass, alfalfa, and other agriculture-based forages in association with an anaerobic bacteria produce inflammatory bowel disease (IBD) in moose. Captive moose that had ad libitum access to a wood-fiber pelleted moose diet and grazed in grass pastures developed chronic wasting symptoms at 2–4 years of age and died at 4.7 ± 0.3 years unless restricted from grass before the development of advanced symptoms. We isolated Bacteroides vulgatus in the feces and successfully treated a moose with chronic diarrhea/wasting disease with long-term metronidazole therapy, suggesting that the chronic enteritis causing wasting disease arises from a bacteria-associated defective immunosuppressive response similar to IBD in other species. Further support for the IBD cause of wasting in moose is that this animal will relapse within hours if the metronidazole treatment is discontinued even after many months. We developed a highly palatable high-fiber, low-starch moose ration that can be fed as the sole source of nourishment, although additional research and dietary improvements are required. Zoo Biol 16:479–494, 1997. © 1997 Wiley-Liss, Inc.     

Nutrition and behavioral management of bottle-raised moose calves

The exceedingly high mortality rates generally associated with artificially raising neonatal moose frequently can be attributed to improper nutritional management and poor husbandry techniques. Dietary-induced diarrhea caused by inappropriate milk replacers is common in moose calves raised in captivity. To avoid diarrhea, calves are often purposefully underfed, resulting in poor growth rates during the first 4 weeks when maternally raised calves rely on milk as their sole energy source. We developed a milk formula and feeding protocol modeled after milk composition and neonatal intake rates measured in maternally raised moose calves. Growth rates for bottle-raised calves during the first 30 days (752 g/day) were similar to maternally raised calves and at least twice that of most previously published bottle-raising efforts. No diet-induced gastrointestinal disorders were encountered, and all calves were successfully weaned and survived their first year. Zoo Biol 16:495–503, 1997. © 1997 Wiley-Liss, Inc.     

Modelling catheter–vein biomechanical interactions during an intravenous procedure

A reliable intravenous (IV) access into the upper extremity veins requires the insertion of a temporary short peripheral catheter (SPC). This so common procedure is, however, associated with a risk of developing short peripheral catheter thrombophlebitis (SPCT) which causes distress and potentially prolongs patient hospitalization. We have developed and studied a biomechanical SPC–vein computational model during an IV procedure, and explored the biomechanical effects of repeated IV episodes on onset and reoccurrences of SPCT. The model was used to determine the effects of different insertion techniques as well as inter-patient biological variability on the catheter–vein wall contact pressures and wall deformations. We found that the maximal pressure exerted upon the vein wall was inhomogeneously distributed, and that the bending region was exposed to significantly greater pressures and deformations. The maximal exerted contact pressure on the inner vein's wall was 2938 Pa. The maximal extent of the SPC penetration into the vein wall reached 3.6 μm, which corresponds to approximately 100% of the average height of the inner layer, suggesting local squashing of endothelial cells at the contact site. The modelling describes a potential biomechanical damage pathway that can explain the reoccurrence of SPCT.     

Complement C4 is protective for lupus disease independent of C3.

The role of complement C3 in mediating systemic lupus erythematosus (SLE) was examined using a double-knockout C3(null)C4(null) Fas (CD95)-deficient mouse model. Results from this study reveal significant lymphadenopathy, splenomegaly, elevated titers of anti-nuclear Abs and anti-dsDNA Abs, an increased number of anti-dsDNA-producing cells in ELISPOT assay, as well as severe glomerulonephritis in the double-deficient mice. Based on these clinical, serological, and histological parameters, we find that autoimmune disease in the double-knockout group is similar in severity to that in C4(null) lpr mice, but not to that in C3(null) lpr mice. The development of severe SLE in the absence of both classical and alternative complement pathways suggests that it is the absence of C4, and not the presence of C3, that is critical in SLE pathogenesis. Thus, complement C4 provides an important protective role against the development of SLE.