Tyrphostin-induced differentiation of mouse erythroleukemia cells

Inhibitors of protein-tyrosine kinases (TPKs) from the tyrphostins family induce terminal erythroid differentiation of mouse erythroleukemia (MEL) cells. The most potent tyrphostin was found to be AG-568 which was therefore investigated in more detail. Just prior to differentiation the inhibition of tyrosine phosphorylation of a pp⁹⁷ protein band was noted. We also found that AG-568 treatment induces the appearance of a putative differentiation factor which could induce tyrphostin-independent differentiation in untreated cells. Our study suggests that the inhibition of tyrosine phosphorylation by AG-568 leads to the production of differentiating factor(s) which induce the MEL cells to differentiate.     

Fungal Biodegradation and Biotransformation of Soluble Lignocarbohydrate Complexes from Straw

Aspergillus japonicus is an efficient degrader of phenolics and carbohydrates present in a mixture of soluble lignocarbohydrate complexes extracted from wheat straw. Trichoderma sp. attacked part of the carbohydrate but hardly affected the aromatic portion of this solution. Polyporus versicolor had a complex effect; polymerization of low-molecular-size phenolics accompanied the degradation of aromatic and carbohydrate polymers. The addition of xylose to the medium facilitated depolymerization of lignin by the fungi tested and prevented the polymerization of low-molecular-size fractions of lignocarbohydrate complexes by P. versicolor. P. versicolor, in contrast to A. japonicus and Trichoderma sp., also excreted into the medium considerable amounts of laccase, but only in the absence of endogenous or exogenous carbohydrates. Apparently, laccase is involved in polymerization rather than degradation of lignin in this organism. A number of extracellular glycanases were also secreted by these fungi.     

Field evaluation of cotton near-isogenic lines introgressed with QTLs for productivity and drought related traits

Quantitative trait loci (QTLs) for yield and drought related physiological traits, osmotic potential (OP), carbon isotope ratio (δ¹³C, an indicator of water use efficiency), and leaf chlorophyll content (Chl), were exchanged via marker-assisted selection (MAS) between elite cultivars of the two cotton species Gossypium barbadense cv. F-177 and G. hirsutum cv. Siv’on. The resulting near isogenic lines (NILs) were examined in two field trials, each with two irrigation regimes, in order to (1) evaluate the potential to improve cotton drought resistance by MAS and (2) test the role of physiological traits in plant productivity. NILs introgressed with QTLs for high yield rarely exhibited an advantage in yield relative to the recipient parent, whereas a considerable number of NILs exhibited the expected phenotype in terms of lower OP (5 out of 9), higher δ¹³C (4 out of 6) or high Chl (2 out of 3). Several NILs exhibited considerable modifications in non-targeted traits including leaf morphology, stomatal conductance and specific leaf weight (SLW). In G. barbadense genotypes, yield was correlated negatively with δ¹³C and OP and positively with stomatal conductance, SLW and Chl, whereas in G. hirsutum yield was negatively correlated with δ¹³C, SLW and Chl. This dissimilarity suggests that each of the respective species has evolved different mechanisms underlying plant productivity. We conclude that the improvement of drought related traits in cotton NILs may lead to improved drought resistance via MAS, but that conventional breeding may be necessary to combine the introduced QTL(s) with high yield potential.     

Structural consensus among antibodies defines the antigen binding site

The Complementarity Determining Regions (CDRs) of antibodies are assumed to account for the antigen recognition and binding and thus to contain also the antigen binding site. CDRs are typically discerned by searching for regions that are most different, in sequence or in structure, between different antibodies. Here, we show that ~20% of the antibody residues that actually bind the antigen fall outside the CDRs. However, virtually all antigen binding residues lie in regions of structural consensus across antibodies. Furthermore, we show that these regions of structural consensus which cover the antigen binding site are identifiable from the sequence of the antibody. Analyzing the predicted contribution of antigen binding residues to the stability of the antibody-antigen complex, we show that residues that fall outside of the traditionally defined CDRs are at least as important to antigen binding as residues within the CDRs, and in some cases, they are even more important energetically. Furthermore, antigen binding residues that fall outside of the structural consensus regions but within traditionally defined CDRs show a marginal energetic contribution to antigen binding. These findings allow for systematic and comprehensive identification of antigen binding sites, which can improve the understanding of antigenic interactions and may be useful in antibody engineering and B-cell epitope identification.     

Spatial patterns of sterile Mediterranean fruit fly dispersal

The success of the sterile insect technique (SIT) for the control of the Mediterranean fruit fly or medfly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), depends largely on the ability of sterile flies to spread in the target area and compete with the wild males for wild females. Our objectives in the present study were three‐fold: (1) to evaluate the dispersal ability of sterile male medflies and compare their spatial dispersion patterns with that of wild males, (2) to evaluate how different release methods affect subsequent spatial dispersal, and (3) to determine whether manipulating the pre‐release diet of sterile males affects their dispersal. To achieve these objectives, we conducted three experiments in the field where we quantified and analyzed the spatial and temporal dispersal patterns of sterile medflies and the dispersion of resident wild males. Overall, ca. 5% of the released sterile flies were recaptured 100 m from the release point, and ca. 2% were recaptured 200 m from the release point. The released flies rarely survived longer than 5–7 days. We repeatedly found that the spatial dispersion patterns of sterile males significantly correlated with those of wild males. Release methods strongly affected subsequent fly dispersal in the field as significantly more flies were recaptured following a scattered release vs. a central one. Finally, we show that enriching sterile fly pre‐release diet with protein did not affect subsequent dispersal in the field. We conclude that sterile males are able to match the dispersion patterns of wild males, an outcome that is highly important for SIT success. Large releases from central points distant from each other may leave many areas uncovered. Accordingly, scattered releases, repeated twice a week, will provide better coverage of all available aggregations sites. The spatial performance of protein‐fed males suggests that pre‐release diet amendments may be used without detriment as a sexual stimulant in SIT programs.     

Susceptibility to klebsiella pneumonaie infection in collaborative cross mice is a complex trait controlled by at least three loci acting at different time points

Background

Klebsiella pneumoniae (Kp) is a bacterium causing severe pneumonia in immunocompromised hosts and is often associated with sepsis. With the rise of antibiotic resistant bacteria, there is a need for new effective and affordable control methods; understanding the genetic architecture of susceptibility to Kp will help in their development. We performed the first quantitative trait locus (QTL) mapping study of host susceptibility to Kp infection in immunocompetent Collaborative Cross mice (CC). We challenged 328 mice from 73 CC lines intraperitoneally with 10⁴ colony forming units of Kp strain K2. Survival and body weight were monitored for 15 days post challenge. 48 of the CC lines were genotyped with 170,000 SNPs, with which we mapped QTLs.

Results

CC lines differed significantly (P < 0.05) in mean survival time, between 1 to 15 days post infection, and broad sense heritability was 0.45. Distinct QTL were mapped at specific time points during the challenge. A QTL on chromosome 4 was found only on day 2 post infection, and QTL on chromosomes 8 and 18, only on day 8. By using the sequence variations of the eight inbred strain founders of the CC to refine QTL localization we identify several candidate genes.

Conclusion

Host susceptibility to Kp is a complex trait, controlled by multiple genetic factors that act sequentially during the course of infection.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-865) contains supplementary material, which is available to authorized users.     

Association of a nonsense mutation (W1282X), the most common mutation in the Ashkenazi Jewish cystic fibrosis patients in Israel, with presentation of severe disease

Only about 30% of the cystic fibrosis chromosomes in the Israeli cystic fibrosis patient populations carry the major CF mutation (delta F508). Since different Jewish ethnic groups tended to live as closed isolates until recent times, high frequencies of specific mutations are expected among the remainder cystic fibrosis chromosomes of these ethnic groups. Genetic factors appear to influence the severity of the disease. It is therefore expected that different mutations will be associated with either severe or mild phenotype. Direct genomic sequencing of exons included in the two nucleotide-binding folds of the putative CFTR protein was performed on 119 Israeli cystic fibrosis patients from 97 families. One sequence alteration which is expected to create a termination at residue 1282 (W1282X) was found in 63 chromosomes. Of 95 chromosomes, 57 (60%) are of Ashkenazi origin. Together with the delta F508 (23% in this group), G542X, N1303K, and 1717-1G----A mutations, the identification of 92% of cystic fibrosis chromosomes of Ashkenazi origin becomes possible. Patients homozygous for the W1282X mutation (n = 16) and patients heterozygous for the delta F508 and W1282X mutations (n = 22) had similarly severe disease, reflected by pancreatic insufficiency, high incidence of meconium ileus (37% and 27%, respectively), early age at diagnosis, poor nutritional status, and variable pulmonary function. In conclusion, the W1282X mutation is the most common cystic fibrosis mutation in the Ashkenazi Jewish patient population in Israel. This nonsense mutation is associated with presentation of severe disease.     

Endemic occurrence of infections by multidrug-resistant Escherichia coli of four unique serotypes in the elderly population of Israel

During a period of four years, multidrug-resistant Escherichia coli of particular serotypes have been isolated from 255 elderly (>65 years) patients from four hospitals in central Israel. 83% of the isolates belonged to one of four predominant serotypes (O153:H31, O101:H-, O2:H42, and O102:H6). All isolates were producers of extended spectrum beta-lactamases and resistant to ciprofloxacin. To our knowledge, the involved serotypes have hitherto not been reported as etiological agents of extraintestinal human infections (MEDLINE). Pulsed-field gel electrophoresis of isolates from one of the most frequent serotypes indicated a clonal relationship between them. Further investigation of these strains and analysis of their virulence factors may help to confine their spread.     

Somatic embryos from culture ovules of polyembryonic Mangifera indica L.

Ovules were aseptically removed from 2 month old fruits of 9 naturally polyembryonic cultivars and 1 monoembryonic cultivar of mango (Mangifera indica L.). Ovules were placed into culture on solid Murashige and Skoog medium that had been modified by the addition of half strength major salts and chelated iron, 6% sucrose, 400 mg/l glutamine, 100 mg/l ascorbic acid with or without the following growth regulators: 20% (v/v) CW, 1 or 2 mg/1 BA. Somatic embryogenesis occurred from the nucellus excised from the ovules of 5 of the naturally polyembryonic cultivars after 1–2 months in culture. Somatic embryogenesis was not apparently affected by the growth regulator composition of the media; however, efficient somatic embryogenesis only occurred in liquid containing 20% CW.Abbreviations CW coconut water - BA benzyladenine