Simple, Robust Invertebrate DNA Barcoding: Chelex-Based DNA Extraction and Optimized COI Amplification

Chelex-based DNA extractions are well suited for student DNA barcoding research because they are simple, safe, and inexpensive and can be performed without specialized laboratory equipment, allowing them to be performed in classrooms or at home. Extracted DNA is stable in Chelex solution for at least a week at ambient temperature, allowing collection of DNA samples from remote students. These extractions provide quality DNA for many taxa and are optimal for barcoding invertebrates, especially in combination with novel cytochrome c oxidase I (COI) primer cocktails and PCR cycling conditions.

Genetic and epigenetic regulation of stem cell homeostasis in plants

Plants generate new organs through the activity of small populations of stem cells present in specialized niches called meristems. Stem cell homeostasis is attained by dynamic regulatory networks involving transcriptional regulators, hormones, and other intercellular signals that specify cell fate and convey positional information to the apical stem cells and the organizing center located immediately below. The balance between stem cell maintenance within the shoot apical meristem (SAM) and differentiation of cells that are displaced from the niche to form new organs involves the epigenetic silencing of stem cell regulatory genes. Recent advances have identified highly conserved chromatin remodeling factors as epigenetic regulators of stem cell fate that confer plasticity in plant development and ensure the stable inheritance of repressed expression states during organogenesis. These advances reveal that common mechanisms contribute to stem cell homeostasis in plants and animals.

Genetic diversity of a natural population of Cucurbit yellow stunting disorder virus

An analysis of nucleotide sequences in five coding and one non-coding genomic regions of 35Cucurbit yellow stunting disorder virus(CYSDV) isolates collected on a local scale over an 8 year period is reported here. In total, 2277 nt were sequenced for each isolate, representing about 13 % of the complete virus genome. Mean nucleotide diversity for the whole population in synonymous positions in the coding regions was 0·00068, whilst in the 5′ untranslated region (5′ UTR) of genomic RNA2, it was 0·00074; both of these values are very small, compared with estimates of nucleotide diversity for populations of other plant viruses. Nucleotide diversity was also determined independently for each of the ORFs and for the 5′ UTR of RNA2; the data showed that variability is not distributed evenly among the different regions of the viral genome, with the coat protein gene showing more diversity than the other four coding regions that were analysed. However, the low variability found precluded any inference of selection differences among gene regions. On the other hand, no evidence of selection associated with host adaptation was found. In contrast, at least a single amino acid change in the coat protein appears to have been selected with time.