Flower structure and developmental stages of the capitulum of Smallanthus sonchifolius (Asteraceae): reproductive implications

Journal of Plant Research - Yacon (Smallanthus sonchifolius, Asteraceae) is an ancient andean crop that has numerous dietary and medicinal properties. Morphological and anatomical features and...     

Chromatid segregation analysis in native human lymphocyte anaphases using sequential fluorescence in situ hybridization

A sequential multiprobe fluorescence in situ hybridization technique was developed to study the 13, 18, 21, X and Y chromatid segregation in human lymphocytes anaphases cultures without antimitotic treatment. This method was used to know if exist any different chromosomes segregation in lymphocytes from Down syndrome patients and compared it with controls. The results show that the prevalent sequence of centromere separation was X, 13, 21, Y and 18 in Down syndrome patients and Y, 13, X, 21 and 18 in controls. Chromatid segregation in early anaphase was asynchronic for all chromosome pairs studied. Late anaphase showed a frequency of non-disjunction of 4.5% in the controls, affecting only chromosomes 18 and Y; in the Down syndrome patients, the frequency was higher (20.3%) and affected all chromosomes studied. This technique could be applicated to know the incidence of non disjunction in couples with repetitive abortions or in cases with different aneuploidies in the offspring. This revised version was published online in September 2006 with corrections to the Cover Date.     

Qualitative screening of C-reactive protein by latex in microtiter trays

A microtiter-latex anti-C reactive protein method is described for screening large number of samples. The high percentage of false positives found with the slide-latex anti-C reactive protein method was reduced about 6 fold by the use of the described method. The use of microtiter trays, dilution of serum in one step and decreasing time of assay make this method simple, specific, rapid and easy to perform without sophisticated equipment.     

Conversion of polycyclic aromatic hydrocarbons,methyl naphthalenes and dibenzofuran by two fungal peroxygenases

The aim of this work has been to study the substrate specificity of two aromatic peroxygenases concerning polyaromatic compounds of different size and structure as well as to identify the key metabolites of their oxidation. Thus, we report here on new pathways and reactions for 2-methylnaphthalene, 1-methylnaphthalene, dibenzofuran, fluorene, phenanthrene, anthracene and pyrene catalyzed by peroxygenases from Agrocybe aegerita and Coprinellus radians (abbreviated as AaP and CrP). AaP hydroxylated the aromatic rings of all substrates tested at different positions, whereas CrP showed a limited capacity for aromatic ring-hydroxylation and did not hydroxylate phenanthrene but preferably oxygenated fluorene at the non-aromatic C₉-carbon and methylnaphthalenes at the side chain. The results demonstrate for the first time the broad substrate specificity of fungal peroxygenases for polyaromatic compounds, and they are discussed in terms of their biocatalytic and environmental implications.     

Fluoride binding to the calcium ATPase of sarcoplasmic reticulum converts its transport sites to a low affinity, lumen-facing form.

The sarcoplasmic reticulum CaATPase forms an inactive complex with fluoride (CaATPase-F), which in the absence of calcium reactivates very slowly (t1/2 approximately 40 h at 25 degrees C). Reactivation is greatly accelerated (greater than 10(3)) by calcium in the millimolar range provided it has access to luminal sites of the enzyme. Measurement of the calcium concentration dependence of the reactivation rate constant revealed a saturable effect with a midpoint of about 12 mM calcium. These results show that an effect other than phosphorylation can produce a greater than 10(3)-fold affinity decrease and reorientation of the calcium transport sites. At a fixed calcium concentration, reactivation became faster with increasing pH (pKa greater than 8), suggesting competition between Ca2+ and H+ for transport sites. CaATPase-F lacked the ability to bind calcium with high affinity or to form phosphorylated enzyme intermediate from Pi; it bound adenyl-5'-yl methylenediphosphonate more than 10-fold less strongly than control CaATPase, had numerous sulfhydryl groups with significantly different reactivity, and was notably less susceptible (more than 10-fold) to thermal inactivation compared with control Ca-ATPase. These results suggest that formation of Ca-ATPase-F involves significant structural changes.     

Effects of structural analogs of brassinosteroids on the recovery of growth inhibition by a specific brassinosteriod biosynthesis inhibitor

A brassinosteroid inhibitor (Brz2001) was used to block the growth of roots, hypocotyls, and epicotyls of soybean seedlings, producing a dwarf phenotype. The application of 24-epibrassinolide completely reversed the inhibitory effects of Brz2001. Two other growth-promoting brassinosteroid analogs, MH5 and BB6, partially overcame the Brz2001-induced growth defects. The growth inhibition of Brz2001-treated seedlings was more effectively reversed by MH5 than by BB6, which may be due to the structural differences between the two compounds. These results indicate that the studied analogs may show brassinosteroid-like activity and therefore may have some practical use instead of brassinolide or its analogues.     

Cell proliferation and cooperation of v-mil and v-myc oncogenes

Retroviruses which possess the property to recombine with genetic material from the cell, have cloned and activated some oncogenes and hence are a privileged source for the study of these genes. Cellular oncogene activation can occur following two non mutually exclusive ways: (i) by over-expression of their products; (ii) by modifications of their products through mutations. Retroviruses can combine these two ways of activation leading to the over-expression of a modified product. In this paper, we present results obtained in the study of MH2, a retrovirus containing two oncogenes. We have shown that the two oncogenes of MH2 (v-mil and v-myc) cooperate in vitro to transform neuroretina cells from chicken embryos. These cells which normally do not grow in a defined medium, are induced to proliferate and become transformed upon infection by MH2. Our data enabled us to show that in MH2 v-mil was responsible for the induction of proliferation and v-myc for the transformation of the proliferating cells. Using in vitro constructs we located two regions in the protein encoded by v-mil which are important for its mitogenic property. We have also cloned the cellular counterpart of v-mil and the study of its biological activity on neuroretina cells enabled us to propose a mechanism of activation of the cellular gene by truncation of its 5' part.