A linkage map for CRINKLED PETAL: a homeotic gene of Clarkia tembloriensis (Onagraceae)

Homeotic mutations in flowers lead to the development of floral organs in abnormal locations. In most laboratory-induced examples of this type of mutation, two adjacent whorls of organs are affected, resulting in two whorls of abnormal organ formation. However, the crinkled petal mutant of Clarkia tembloriensis is interesting because it is a naturally occurring mutation and it affects only the second whorl of organs, producing sepaloid petals. In this study one wild-type population (Cantua Creek-2) and one crinkled petal mutant population (Red Rocks) were compared using 181 different primers in random amplified polymorphic DNA (RAPD) analysis. Bulk DNA from each parent population and their subsequent crosses were used to compare the genetic differences between the two populations and to search for molecular markers linked with the CRINKLED PETAL locus. A linkage map was developed for the CRINKLED PETAL gene, and markers were discovered which flanked both sides of the locus.     

A comparison of venation pattern development in wild type and a homeotic sepaloid petal mutant of Clarkia tembloriensis (Onagraceae)

Vascular system development in sepals, petals, and sepaloid petals was compared in wild-type and crinkled petal mutant plants of Clarkia tembloriensis. Patterns of vascularization in cleared whole mounts were visualized and traced under both brightfield and polarizing illumination. Wild-type sepals exhibited a basipetal pattern of maturation, with tracheary elements maturing relatively rapidly. Mature sepals had three primary veins with numerous secondary veins. In contrast, wild-type petals exhibited an acropetal pattern of maturation, with tracheary elements maturing relatively slowly. The mature petals had only one primary vein with numerous secondary veins. Sepaloid (crinkled) petals combined characteristics of both wild-type sepals and wild-type petals. They exhibited a basipetal pattern of development and a relatively rapid maturation of the tracheary elements characteristic of wild-type sepals. Venation architecture in crinkled petal mutants showed a single primary vein with numerous secondary veins, similar to wild-type petals. The crinkled petal mutant fits the definition of a homeotic mutant in that the petal has assumed characteristics of the sepal. However, homeotic transformation from petal to sepal is incomplete since the crinkled petal still retains many of the characteristics of wild-type petals.     

Adverse effects of tempol on hidrosaline balance in rats with acute sodium overload

We studied the effects of tempol, an oxygen radical scavenger, on hydrosaline balance in rats with acute sodium overload. Male rats with free access to water were injected with isotonic (control group) or hypertonic saline solution (0.80 mol/l NaCl) either alone (Na group) or with tempol (Na-T group). Hydrosaline balance was determined during a 90 min experimental period. Protein expressions of aquaporin 1 (AQP1), aquaporin 2 (AQP2), angiotensin II (Ang II) and endothelial nitric oxide synthase (eNOS) were measured in renal tissue. Water intake, creatinine clearance, diuresis and natriuresis increased in the Na group. Under conditions of sodium overload, tempol increased plasma sodium and protein levels and increased diuresis, natriuresis and sodium excretion. Tempol also decreased water intake without affecting creatinine clearance. AQP1 and eNOS were increased and Ang II decreased in the renal cortex of the Na group, whereas AQP2 was increased in the renal medulla. Nonglycosylated AQP1 and eNOS were increased further in the renal cortex of the Na-T group, whereas AQP2 was decreased in the renal medulla and was localized mainly in the cell membrane. Moreover, p47-phox immunostaining was increased in the hypothalamus of Na group, and this increase was prevented by tempol. Our findings suggest that tempol causes hypernatremia after acute sodium overload by inhibiting the thirst mechanism and facilitating diuresis, despite increasing renal eNOS expression and natriuresis.     

Bacterial species and evolution: Theoretical and practical perspectives

A discussion of the species problem in modern evolutionary biology serves as the point of departure for an exploration of how the basic science aspects of this problem relate to efforts to map bacterial diversity for practical pursuits—for prospecting among the bacteria for useful genes and gene-products. Out of a confusing array of species concepts, the Cohesion Species Concept seems the most appropriate and useful for analyzing bacterial diversity. Techniques of allozyme analysis and DNA fingerprinting can be used to put this concept into practice to map bacterial genetic diversity, though the concept requires minor modification to encompass cases of complete asexuality. Examples from studies of phenetically definedBacillus species provide very partial maps of genetic population structure. A major conclusion is that such maps frequently reveal deep genetic subdivision within the phenetically defined specles; divisions that in some cases are clearly distinct genetic species. Knowledge of such subdivisions is bound to make prospecting within bacterial diversity more effective. Under the general concept of genetic cohesion a hypothetical framework for thinking about the full range of species conditions that might exist among bacteria is developed and the consequences of each such model for species delineation, and species identification are discussed. Modes of bacterial evolution, and a theory of bacterial speciation with and without genetic recombination, are examined. The essay concludes with thoughts about prospects for very extensive mapping of bacterial diversity in the service of future efforts to find useful products. In this context, evolutionary biology becomes the handmaiden of important industrial activities. A few examples of past success in commercializing bacterial gene-products from species ofBacillus and a few other bacteria are reviewed.     

A COMPARISON OF FLORAL DEVELOPMENT IN WILD TYPE AND A HOMEOTIC SEPALOID PETAL MUTANT OF CLARKIA TEMBLORIENSIS (ONAGRACEAE)

The mature wild type petals of Clarkia tembloriensis consist of a long slender claw and an expanded deltoid-shaped limb. They are pink, with a maroon spot at the base of the limb. Their surface texture is smooth. A variant of petal form, crinkled petal, occurs commonly in several natural populations of C. tembloriensis. The mature crinkled petals are elongated, greenish pink, and possess trichomes. They resemble the mature sepals of C. tembloriensis in general shape, color, and surface texture. Organ initiation and subsequent patterns of development of wild type petals, wild type sepals, and crinkled petals were examined and compared using scanning electron microscopy and allometric growth analysis. Crinkled petals are similar to wild type petals in time and position of primordia initiation, and in size and shape at inception. Crinkled petals are similar to wild type sepals in pattern of allometric growth. The crinkled petal mutant fits the broad definition of a homeotic mutant in that the petal has assumed characteristics of the sepal.