Embryological character states are mapped on the diagrams of dicotyledons (G. Dahlgren 1989). The often well-defined pattern of distribution forms a basis for discussing and clarifying phylogenetic relations. It is shown how numerous embryological characters, alone or in combinations, support certain systematic constellations, even if the character states may have arisen independently within a ...

Mutations in the QUARTET loci in Arabidopsis result in failure of microspore separation during pollen development due to a defect in degradation of the pollen mother cell wall during late stages of pollen development. Mutations in a new locus required for microspore separation, QRT3, were isolated, and the corresponding gene was cloned by T-DNA tagging. QRT3 encodes a protein that is approximat...

As a core regulatory gene of the anther development, DYSFUNCTIONAL TAPETUM1 (DYT1) was expressed in tapetum preferentially. Previous study had confirmed that a "CTCC" sequence within DYT1 promoter was indispensable for correct DYT1 expression. However, precise analysis on the function of each nucleotide of this sequence still lacks. Here we employed site mutation assay to identify the function ...

We propose a new theory to explain developmental aberrations in plant hybrids. In our theory, hybrid incompatibilities arise from imbalances in the mechanisms that cause male sterility in hermaphroditic plants. Mitochondria often cause male sterility by killing the tapetal tissue that nurtures pollen mother cells. Recent evidence suggests that mitochondria destroy the tapetum by triggering stan...

Simultaneous coupling methods for detection of acid phosphatase and non-specific esterase produce a coloured reaction product that is quantitatively related to enzyme content in freeze-sectioned Brassica pollen and tapetal cells. The intine-located acid phosphatase has 2 periods of synthesis: the first in late vacuolate period, associated with the completion of deposition of the intine polysacc...

We report the unexpected findings of bilateral retinal astrocytic hamartomas in a giant panda. The eyes of Hsing-Hsing, a giant panda that had renal failure, chronic hypertension, degenerative joint disease, and progressive ulcerative keratitis, were examined grossly and histologically. Most of the findings were related to Hsing-Hsing’s debilitated condition or to normal anatomic variations bet...

The aim of this work was to carry out the reproductive studies on Brazilian accessions of ipecac, Psychotria ipecacuanha. It presented heterostyly, with brevistylous and longistylous flowers. The pollen development was observed from the sections of the anthers embedded in resin. Anther development was normal as usually observed in dicotyledones, displaying four layers: outer epidermis, endothec...

We report the unexpected findings of bilateral retinal astrocytic hamartomas in a giant panda. The eyes of Hsing-Hsing, a giant panda that had renal failure, chronic hypertension, degenerative joint disease, and progressive ulcerative keratitis, were examined grossly and histologically. Most of the findings were related to Hsing-Hsing’s debilitated condition or to normal anatomic variations bet...

The presence of fat-laden cells in the cerebrospinal fluid is usually associated with a fatty change found particularly in the area of the tapetum in the postnatal infant. In a series of 307 child deaths the presence of fatty change in this area of the brain was age-related, decreased with age, and was rarely present over the age of 4 years. It was particularly common in stillborns and in child...