In Favor of Establishment: Regulation of Chromatid Cohesion in Plants.

In eukaryotic organisms, the correct regulation of sister chromatid cohesion, whereby sister chromatids are paired and held together, is essential for accurate segregation of the sister chromatids and homologous chromosomes into daughter cells during mitosis and meiosis, respectively. Sister chromatid cohesion requires a cohesin complex comprised of structural maintenance of chromosome adenosine triphosphatases and accessory proteins that regulate the association of the complex with chromosomes or that are involved in the establishment or release of cohesion. The cohesin complex also plays important roles in the repair of DNA double-strand breaks, regulation of gene expression and chromosome condensation. In this review, we summarize progress in understanding cohesion dynamics in plants, with the aim of uncovering differences at specific stages. We also highlight dissimilarities between plants and other eukaryotes with respect to the key players involved in the achievement of cohesion, pointing out areas that require further study.

Reduced activity of Arabidopsis chromosome-cohesion regulator gene CTF7/ECO1 alters cytosine methylation status and retrotransposon expression.

Multicellular organisms such as higher plants require timely regulation of DNA replication and cell division to grow and develop. Recent work in Arabidopsis has shown that chromosome segregation during meiosis and mitosis depends on the activity of several genes that in yeast are involved in the establishment of chromosomal cohesion. In this process, proteins of the structural maintenance of chromosomes (SMC) family tether chromosomes and establish inter- and intrachromosomal connections. In Arabidopsis, recruitment of SMC proteins and establishment of cohesion during key stages of the cell cycle depend on the activity of chromosome transmission fidelity 7/establishment of cohesion 1 (CTF7/ECO1). Here we show that loss of CTF7/ECO1 activity alters the status of cytosine methylation in both intergenic regions and transposon loci. An increase in expression was also observed for transposon copia28, which suggests a link between CTF7/ECO1 activity, DNA methylation and gene silencing. More work is needed to determine the mechanistic relationships that intervene in this process.

Delayed dendritic development in newly generated dentate granule cells by cell-autonomous expression of the amyloid precursor protein.

Neuronal connectivity and synaptic remodeling are fundamental substrates for higher brain functions. Understanding their dynamics in the mammalian allocortex emerges as a critical step to tackle the cellular basis of cognitive decline that occurs during normal aging and in neurodegenerative disorders. In this work we have designed a novel approach to assess alterations in the dynamics of functional and structural connectivity elicited by chronic cell-autonomous overexpression of the human amyloid precursor protein (hAPP). We have taken advantage of the fact that the hippocampus continuously generates new dentate granule cells (GCs) to probe morphofunctional development of GCs expressing different variants of hAPP in a healthy background. hAPP was expressed together with a fluorescent reporter in neural progenitor cells of the dentate gyrus of juvenile mice by retroviral delivery. Neuronal progeny was analyzed several days post infection (dpi). Amyloidogenic cleavage products of hAPP such as the ß-C terminal fragment (ß-CTF) induced a substantial reduction in glutamatergic connectivity at 21 dpi, at which time new GCs undergo active growth and synaptogenesis. Interestingly, this effect was transient, since the strength of glutamatergic inputs was normal by 35 dpi. This delay in glutamatergic synaptogenesis was paralleled by a decrease in dendritic length with no changes in spine density, consistent with a protracted dendritic development without alterations in synapse formation. Finally, similar defects in newborn GC development were observed by overexpression of α-CTF, a non-amyloidogenic cleavage product of hAPP. These results indicate that hAPP can elicit protracted dendritic development independently of the amyloidogenic processing pathway.

Identification, isolation and optimization of antifungal metabolites from the Streptomyces Malachitofuscus ctf9

An indigenous Streptomyces isolate CTF9, exhibiting promising antifungal activity against Mucor miehei and Candida albicans in pre-screening studies, was investigated by cultivation in a 50-L fermenter and by subsequent isolation, purification, and structure elucidation of the active metabolites. Based on the morphological, biochemical, and physiological characterization, as well as the 16S rRNA gene sequence, the isolate CTF9 was identified as Streptomyces malachitofuscus. Using a series of chromatographic techniques, two pure compounds were isolated from the obtained extracts after the fermentation of the isolate CTF9. The isolated compounds were identified as phenylacetic acid and indolyl-3-lactic acid by mass spectrometry (MS) and NMR analysis. The culture optimization studies revealed that the isolate CTF9 can use a variety of low-cost carbon and nitrogen sources to generate the maximum quantity of industrially important metabolites at an elevated temperature of 35°C and at a pH 7.8.

Identification, isolation and optimization of antifungal metabolites from the Streptomyces Malachitofuscus ctf9.

An indigenous Streptomyces isolate CTF9, exhibiting promising antifungal activity against Mucor miehei and Candida albicans in pre-screening studies, was investigated by cultivation in a 50-L fermenter and by subsequent isolation, purification, and structure elucidation of the active metabolites. Based on the morphological, biochemical, and physiological characterization, as well as the 16S rRNA gene sequence, the isolate CTF9 was identified as Streptomyces malachitofuscus. Using a series of chromatographic techniques, two pure compounds were isolated from the obtained extracts after the fermentation of the isolate CTF9. The isolated compounds were identified as phenylacetic acid and indolyl-3-lactic acid by mass spectrometry (MS) and NMR analysis. The culture optimization studies revealed that the isolate CTF9 can use a variety of low-cost carbon and nitrogen sources to generate the maximum quantity of industrially important metabolites at an elevated temperature of 35°C and at a pH 7.8.

Identification, isolation and optimization of antifungal metabolites from the Streptomyces Malachitofuscus ctf9

An indigenous Streptomyces isolate CTF9, exhibiting promising antifungal activity against Mucor miehei and Candida albicans in pre-screening studies, was investigated by cultivation in a 50-L fermenter and by subsequent isolation, purification, and structure elucidation of the active metabolites. Based on the morphological, biochemical, and physiological characterization, as well as the 16S rRNA gene sequence, the isolate CTF9 was identified as Streptomyces malachitofuscus. Using a series of chromatographic techniques, two pure compounds were isolated from the obtained extracts after the fermentation of the isolate CTF9. The isolated compounds were identified as phenylacetic acid and indolyl-3-lactic acid by mass spectrometry (MS) and NMR analysis. The culture optimization studies revealed that the isolate CTF9 can use a variety of low-cost carbon and nitrogen sources to generate the maximum quantity of industrially important metabolites at an elevated temperature of 35°C and at a pH 7.8.