ABSTRACT
The species Brassica oleracea includes several agricultural varieties characterized by the proliferation of different types of meristems. Using a combination of subtractive hybridization and PCR (polymerase chain reaction) techniques we have identified several genes which are expressed in the reproductive meristems of the cauliflower curd (B. oleracea var. botrytis) but not in the vegetative meristems of Brussels sprouts (B. oleracea var. gemmifera) axillary buds. One of the cloned genes, termed CCE1 (CAULIFLOWER CURD EXPRESSION 1) shows specific expression in the botrytis variety. Preferential expression takes place in this variety in the meristems of the curd and in the stem throughout the vegetative and reproductive stages of plant growth. CCE1 transcripts are not detected in any of the organs of other B. oleracea varieties analyzed. Based on the nucleotide sequence of a cDNA encompassing the complete coding region, we predict that this gene encodes a transmembrane protein, with three transmembrane domains. The deduced amino acid sequence includes motifs conserved in G-protein-coupled receptors (GPCRs) from yeast and animal species. Our results suggest that the cloned gene encodes a protein belonging to a new, so far unidentified, family of transmembrane receptors in plants. The expression pattern of the gene suggests that the receptor may be involved in the control of meristem development/arrest that takes place in cauliflower.
Subject(s)
Brassica/genetics , Endodeoxyribonucleases/genetics , Gene Expression Regulation, Plant , Receptors, Cell Surface/genetics , Amino Acid Sequence , Base Sequence , Brassica/classification , Cloning, Molecular , DNA Primers , DNA, Complementary/genetics , Endodeoxyribonucleases/chemistry , Holliday Junction Resolvases , Molecular Sequence Data , Plant Proteins , Plant Stems/physiology , Polymerase Chain Reaction , Protein Structure, Secondary , Recombinant Proteins/chemistry , Restriction Mapping , Sequence Alignment , Sequence Homology, Amino Acid , Species Specificity , Transcription, GeneticABSTRACT
We developed a device for monitoring instantaneous left ventricular (LV) volume using an alternating-current excitation two-electrode conductance catheter. Instantaneous conductance between a pair of electrodes was amplified by a non-inverting circuit. The level of conductance was linearly related to changes in blood volume from 0.8 to 2.0 ml in a latex balloon (r2 = 0.95), and to changes in blood volume from 0.4 to 2.2 ml in a post-mortem rabbit left ventricle (r2 = 0.99). The difference between the maximal and minimal conductance of the LV in situ during a cardiac cycle was closely correlated with changes in stroke volume, measured by an electromagnetic flow probe (r2 = 0.97). The endsystolic pressure-conductance relation (ESPCR) was highly linear (r2 = 0.92). Changes of the slope (Ees) of the ESPCR correlated directionally with changes of the time derivative of LV pressure (LVdP/dt) during intravenous infusions of dobutamine and propranolol. Accordingly, the two-electrode conductance catheter was useful in vivo in rabbits for continuously assessing changes in the LV volume.
