The possibility to distinguish chromosomes of Petunia hybrida by quinacrine fluorescence

A karyotype analysis of a diploid inbred line of Petunia hybrida stained with aceto-orcein is given. Five of the seven pairs of chromosomes can be identified by their relative lengths and arm ratios. The two remaining pairs stained with quinacrine show different fluorescence patterns.     

A sequential screening of the cytogenetic damage induced by triaziquone.

A sequence is described of test procedures for a screening in vivo of the clastogenic potential of the alkylating agent triaziquone (Trenimon). Two intraperitoneal injections of 0.125 mg/kg body weight caused a considerable increase in the number of aberrations in both the micronucleus test and the bone-marrow metaphase test, but not in the spermatocyte translocation test or the spermatogonial metaphase test. With the latter test a severe cell-killing effect was detected. An analysis of whole mounts of seminiferous tubules showed that 0.125 mg/kg was a lethal dose for all B- and intermediate-type spermatogonia and partly killed A-type spermatogonia. A single administration of the same dose caused stable chromosomal rearrangements in spermatids that could be demonstrated with the F1 translocation test, and gave rise to dominant lethality of fetuses originating from post-meiotic sperm. The comparative triaziquone study has provided arguments in favor of the micronucleus test as a reliable screening method for chromosomal aberrations. The analysis of seminiferous tubules is a recommendable method for studying lethal effects of a compound on germ cells, whereas the F1 translocation test gives important information about viable aberrations and their effect on the fertility of the progeny.     

Reduced insulin/IGF-1 signalling and human longevity

Evidence is accumulating that aging is hormonally regulated by an evolutionarily conserved insulin/IGF-1 signalling (IIS) pathway. Mutations in IIS components affect lifespan in Caenorhabditis elegans, Drosophila melanogaster and mice. Most long-lived IIS mutants also show increased resistance to oxidative stress. In D. melanogaster and mice, the long-lived phenotype of several IIS mutants is restricted to females. Here, we analysed the relationship between IIS signalling, body height and longevity in humans in a prospective follow-up study. Based on the expected effects (increased or decreased signalling) of the selected variants in IIS pathway components (GHRHR, GH1, IGF1, INS, IRS1), we calculated composite IIS scores to estimate IIS pathway activity. In addition, we analysed the relative impact on lifespan and body size of the separate variants in multivariate models. In women, lower IIS scores are significantly associated with lower body height and improved old age survival. Multivariate analyses showed that these results were most pronounced for the GH1 SNP, IGF1 CA repeat and IRS1 SNP. In females, for variant allele carriers of the GH1 SNP, body height was 2 cm lower (P = 0.007) and mortality 0.80-fold reduced (P = 0.019) when compared with wild-type allele carriers. Thus, in females, genetic variation causing reduced IIS activation is beneficial for old age survival. This effect was stronger for the GH1 SNP than for variation in the conserved IIS genes that were found to affect longevity in model organisms.     

Modulation of FcgammaRI (CD64) ligand binding by blocking peptides of periplakin

FcgammaRI requires both the intracellular domain of the alpha-chain and associated leukocyte Fc receptor (FcR) gamma-chains for its biological function. We recently found the C terminus of periplakin to selectively interact with the cytoplasmic domain of the FcgammaRI alpha-chain. It thereby enhances the capacity of FcgammaRI to bind, internalize, and present antigens on MHC class II. Here, we characterized the domains involved in FcgammaRI-periplakin interaction using truncated and alanine-substituted FcgammaRI mutants and randomly mutagenized periplakin. This allowed us to design TAT peptides that selectively interfered with endogenous FcgammaRI-periplakin interactions. The addition of these peptides to FcgammaRI-expressing cells modulated FcgammaRI ligand binding, as assessed by erythrocyte-antibody-rosetting. These data support a dominant-negative role of C-terminal periplakin for FcgammaRI biological activity and implicate periplakin as a novel regulator of FcgammaRI in immune cells.     

Computer assisted karyotype analysis of Pyrrhopappus carolinianus

With the help of Computer Aided Karyotyping procedures, Ag-NOR staining and C-banding techniques, the karyotype of Pyrrhopappus carolinianus (Asteraceae, Lactuceae) has been studied. The species has 2n=12 chromosomes. Silver staining reveals that the two shortest pairs of chromosomes possess NOR's. On the basis of chromosome length and centromere position, only the longest chromosome pair and the satellite chromosomes can be identified. Two types of C-banding can be obtained, dependent on the temperature of the hydrochloric acid hydrolysis of the root tips. Hydrolysis at 60°C results exclusively in centromeric bands, whereas a treatment at room temperature reveals a pattern of intercalary bands. A computer assisted analysis of the intercalary banding pattern resulted in the construction of schematic representation of the average C-banding pattern. This banding pattern allows an easy identification of each of the chromosome pairs.     

Application of antibodies to intermediate filament proteins as tissue-specific probes in the flow cytometric analysis of complex tumors

The flow cytometric (FCM) analysis of carcinomas is often hampered by the presence of stromal and inflammatory cells in the cell suspensions obtained from such neoplasms. Therefore, an FCM method was developed to distinguish epithelial from nonepithelial cells by using polyclonal and monoclonal antibodies to (cyto)keratins, the epithelial type of intermediate filament proteins. Using a model system of cultured bladder carcinoma (T24) and leukemia (MOLT-4) cells, we tested our hypothesis and procedures by labeling cell mixtures with these antibodies. After incubation with an appropriate intermediate filament antibody and propidium iodide staining, the DNA content and distribution of T24 cells could be analyzed separately from MOLT-4 cells. When applied to cell suspensions of endometrial carcinomas, bladder carcinomas and Grawitz tumors, only the epithelial (primarily carcinoma) cells were stained for cytokeratin; these cells could thus be analyzed separately from stromal, inflammatory and other nonepithelial cells. In this way, a more accurate FCM analysis of the malignant fraction within a tumor can be achieved.     

High-Sensitivity Cardiac Troponin Concentrations in Patients with Chest Discomfort: Is It the Heart or the Kidneys As Well?

BackgroundHigh-sensitivity cardiac troponins (hs-cTn) are the preferred biomarkers to detect myocardial injury, making them promising risk-stratifying tools for patients with symptoms of chest pain. However, circulating hs-cTn are also elevated in other conditions like renal dysfunction, complicating appropriate interpretation of low-level hs-cTn concentrations.MethodsA cross-sectional analysis was performed in 1864 patients with symptoms of chest discomfort from the cardiology outpatient department who underwent cardiac computed tomographic angiography (CCTA). Serum samples were analyzed using hs-cTnT and hs-cTnI assays. Renal function was measured by the estimated glomerular filtration rate (eGFR), established from serum creatinine and cystatin C. On follow-up, the incidence of adverse events was assessed.ResultsMedian hs-cTnT and hs-cTnI concentrations were 7.2(5.8–9.2) ng/L and 2.6(1.8–4.1) ng/L, respectively. Multivariable regression analysis revealed that both assay results were more strongly associated with eGFR (hs-cTnT:stβ:-0.290;hs-cTnI:stβ:-0.222) than with cardiac imaging parameters, such as coronary calcium score, CCTA plaque severity score and left ventricular mass (all p<0.01). Furthermore, survival analysis indicated lower relative risks in patients with normal compared to reduced renal function for hs-cTnT [HR(95%CI), 1.02(1.00–1.03) compared to 1.07(1.05–1.09)] and hs-cTnI [1.01(1.00–1.01) compared to 1.02(1.01–1.02)] (all p<0.001).ConclusionIn patients with chest discomfort, we identified an independent influence of renal function on hs-cTn concentrations besides CAD, that affected the association of hs-cTn concentrations with adverse events. Estimating renal function is therefore warranted when interpreting baseline hs-cTn concentrations.     

Glutamate as chemotactic fuel for diffuse glioma cells: Are they glutamate suckers?

Diffuse gliomas comprise a group of primary brain tumors that originate from glial (precursor) cells and present as a variety of malignancy grades which have in common that they grow by diffuse infiltration. This phenotype complicates treatment enormously as it precludes curative surgery and radiotherapy. Furthermore, diffusely infiltrating glioma cells often hide behind a functional blood–brain barrier, hampering delivery of systemically administered therapeutic and diagnostic compounds to the tumor cells. The present review addresses the biological mechanisms that underlie the diffuse infiltrative phenotype, knowledge of which may improve treatment strategies for this disastrous tumor type. The invasive phenotype is specific for glioma: most other brain tumor types, both primary and metastatic, grow as delineated lesions. Differences between the genetic make-up of glioma and that of other tumor types may therefore help to unravel molecular pathways, involved in diffuse infiltrative growth. One such difference concerns mutations in the NADP⁺-dependent isocitrate dehydrogenase (IDH1 and IDH2) genes, which occur in > 80% of cases of low grade glioma and secondary glioblastoma. In this review we present a novel hypothesis which links IDH1 and IDH2 mutations to glutamate metabolism, possibly explaining the specific biological behavior of diffuse glioma.     

Reverse breeding: a novel breeding approach based on engineered meiosis

Reverse breeding (RB) is a novel plant breeding technique designed to directly produce parental lines for any heterozygous plant, one of the most sought after goals in plant breeding. RB generates perfectly complementing homozygous parental lines through engineered meiosis. The method is based on reducing genetic recombination in the selected heterozygote by eliminating meiotic crossing over. Male or female spores obtained from such plants contain combinations of non-recombinant parental chromosomes which can be cultured in vitro to generate homozygous doubled haploid plants (DHs). From these DHs, complementary parents can be selected and used to reconstitute the heterozygote in perpetuity . Since the fixation of unknown heterozygous genotypes is impossible in traditional plant breeding, RB could fundamentally change future plant breeding. In this review, we discuss various other applications of RB, including breeding per chromosome.