Ashley Jane Orr

RNA splicing is generally considered an essential part of transcription, however, it may have been found that spliced genes do not so much dictate the level of gene activity but rather the origin of the tissue sample.

In this study, major players of the plastid genome (atpF, petB, petD, and rpl16) both spliced and unspliced were accounted for in leaf, meristematic, and root tissue of a maize inbred B73. The results were interesting. As expected, spliced genes were commonly found in new formation of leaf tissue and meristematic and root tissue had a largely unspliced plastid genome in comparison. However, while tissue origin showed a significant difference in spliced to unspliced genome ratios, there was not a significant difference between normal maize and those in mutants blocking photosynthetic electron transport. Both seedlings grown in the dark and mutants blocking chlorophyll accumulation also yielded similar RNA ratios. This shows that photosynthetic competency, chlorophyll content, and exposure to light do not have a direct effect on the ratio of spliced to unspliced plastid genome and that it seems to rely solely on the differentiation of plant tissue.

Reference:

Barkan, Alice. January 4, 1989. Tissue-Dependent Plastid RNA Splicing in Maize: Transcripts from Four Plastid Genes Are Predominantly Unspliced in Leaf Meristems and Roots. The Plant Cell, Vol 1., 437-445.
http://www.plantcell.org/content/1/4/437.full.pdf

*post edited 12/12/2011

http://www.ruthsorchids.com/speciespage4a.html

Stereochilus dalatensis (Guillaumin) Garay is one of 7 valid species in genus Stereochilus and belongs to the family Orchidaceae. It’s flowers grow to be about .75cm and bloom in spring. Their flowers are usually fragrant and a pale pink color. The floral arrangement is inflorescence, meaning the flowers grow in clusters on a main branch or an arrangement of branches. (The specific arrangement of the flowers may depend on the species of plant.) These plants are entomophilous, a form of pollination performed by insects. This orchid is an epiphyte and it will grow to approximately 10cm. It is found Vietnam and China in cool to warm climates.