Developmental Gradients

To properly evaluate data relating to reserve starch development and composition, cellular development of tissues in which this starch is formed must be appreciated. Enlarging potato tubers,38 cotyledons of developing pea seeds39 and endosperms 

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Endosperm of ae du wx in a sweet corn background has a major developmental gradient typical of normal and a type-II minor gradient characteristic of du.43 Saussy43 reports that starch granule and plastid development in ae du wx is similar to that of du wx. 

The hippocampus is sliced on a 200 pm polyester film of 2 x 3 cm (Pearl Paint) that has been extensively washed with 70% ethanol and air dned in a sterile hood Any plastic film can be used to support the hippocampus The film must be sterile and must resist being sliced by the tissue chopper blade There are consistent differences between cultures of the septal and temporal hippocampus that likely result from developmental gradients in the immature hippocampus (17), At postnatal d 10-11, the temporal end of the hippocampus is more mature than the septal end. Therefore, consistent differences can be observed between slice cultures originating from the temporal end or septal end. In particular, the mossy fiber projection differs between septal and temporal cultures (17) In septal cultures, there is mossy fiber sprouting mossy fiber terminals are found in the inner molecular layer of the dentate gyrus and the CA3 pyramidal cell layer. In temporal cultures, the mossy fiber projection is normal. This likely results in differences in slice culture excitability since epileptiform activity is more readily induced in septal cultures than temporal cultures (17). 

The wheat leaf has a developmental gradient alon its length with a zone of cell division at its base and oldest tissue at its tip. We have used this feature to study the developmental expression of the genes for these enzymes. The mRNA levels for each are highest below the middle of leaf and decrease towards the tip (1,6,7). None was found in the roots or in etiolated tissues. Even a very brief illumination resulted in the accumulation of a detectable amount in the etiolated leaves. In contrast, mRNA for the cytosolic PGK was found in about the same amount in all tissues examined. Accumulation of the FBP follows the same pattern as that of its mRNA but, in contrast, its levels do not decline again in older tissues suggesting that the protein is relatively stable. 

DEVELOPMENTAL GRADIENTS OF GE E EXPRESSION IN THE ENERGING FOUITH LEAF OF LOLIIM TEMULENTUM... 

Developmental Gradients of Gene Expression in the Emerging Fourth Leaf of Loliwn... 

Wernicke, W. Milkovits, L. (1984). Developmental gradients in wheat leaves - Response of leaf seements in different eenotypes cultured in vitro. Journal of Plant Physiology, Vol.115, pp. 49-58, ISSN 0176-1617... 

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