CHATTAWAYA (STERCULIACEAE): A NEW GENUS OF WOOD FROM THE EOCENE OF OREGON AND ITS IMPLICATIONS FOR XYLEM EVOLUTION OF THE EXTANT GENUS PTEROSPERMUM

A new sterculiaceous wood, Chattawaya paliformis gen. et sp. n., was collected from a Middle Eocene locality in the type area of the Clamo Formation of north central Oregon. The wood differs from all known extant woods in having very large and irregularly shaped tile cells. However, other features of the xylem indicate a close natural relationship between Chattawaya and the extant paleotropical genus, Pterospermum. It is suggested that the xylem organization of the Eocene fossil represents a more primitive condition than that observed in Pterospermum. Comparative xylotomy indicates three evolutionary trends within the complex to which Chattawaya and Pterospermum belong: development of storied structure, increased uniformity in shape and size of tile cells and loss of multiseriate rays. Chattawaya is part of a growing body of paleobotanical evidence indicating that the Sterculiaceae was well differentiated by the early Tertiary, but that the lineages leading to extant genera have undergone an appreciable amount of evolutionary change since the Eocene.     

Decreased placental monooxygenase activities associated with birth defects

We have measured monooxygenase activities in placentas from 82 women who smoked throughout their pregnancies and correlated these with the presence or absence of major somatic anomalies. Monooxygenase activities toward benzo(a)pyrene and ethoxyresorufin in placentas from 18 abnormal infants were compared with activities in placentas from 64 concurrently studied normal infants. Placentas from normal infants were found to have high levels of monooxygenase activities and low apparent Kms toward ethoxyresorufin (10(-7) M), reflecting induction of cytochrome P-450 enzymes usually associated with maternal cigarette smoking. Placentas from the abnormal infants, however, had significantly lower monooxygenase activities and higher apparent Kms toward ethoxyresorufin (10(-5) M), indicating that induction of specific cytochrome P-450 systems occurred less frequently among placentas from abnormal infants. The reasons for this association are unclear. Apparent lack of induction of monooxygenase activity occurred most frequently in placentas from anencephalic infants but was neither exclusively nor consistently found with this defect. No specific maternal condition or environmental exposure associated with lack of monooxygenase induction was identified.     

Analysis of rate constants governing the exchange of guanine nucleotides bound to EF-Tu catalysed by EF-Ts.

The kinetics of the heterologous exchange of GDP bound to EF-Tu by free GTP catalysed by EF-Ts have been analysed with a view to correlating results obtainable with different computational procedures. The affinity of EF-Ts for EF-Tu.GTP was found to be somewhat less than previously proposed by Romero et al. (Biochemistry 260, 6167:1985) though still greater than for EF-Tu.GDP. There is a close interrelationship between the constants for the binding of GTP to EF-Tu.EF-Ts and of EF-Ts to EF-Tu.GTP. The declining fractional rate of exchange observed by Romero et al. during displacement of GDP by GTP appears to be dependent on the ratio of the rate constants (k-1 + k-2)k4/k1k-2 as defined in the text, not on that of K4/K1 as they proposed.     

Exploring the gene with X-rays

X-rays were discovered 100 years ago. Their effects on living cells and on mutation were quickly recognized. This article discusses a classic paper that sought to use X-rays to estimate the size of the gene and quantum mechanics to explain its impressive stability.     

Phytoremediative Capacity of Plants Enriched with Melatonin

Melatonin is an environmentally friendly-molecule with broad spectrum antioxidant capacity. Melatonin is widely present in the plant kingdom. High levels of melatonin exist in an aquatic plant, the water hyacinth, which is highly tolerant of environmental pollutants. Elevated levels of melatonin probably help plants to protect against environmental stress caused by water and soil pollutants. To investigate the potential relationships between melatonin supplementation and environmental tolerance in plants, pea plants were treated with high levels of copper in the soil. The results show that copper contamination kills pea plants; however, melatonin added to the soil significantly enhanced their tolerance to the copper contamination and, therefore, increased their survival. Based on the theory and these preliminary data, we speculate that melatonin could be used to improve the phytoremediative efficiency of plants against different pollutants. Since melatonin is safe to animals and humans as well as being inexpensive, it may be a feasible and cost-effective approach to clean environmental contaminations.Key Words: phytoremediation, plants, melatonin, antioxidant     

Chemically modified viruses: principles and applications

The search for novel molecular materials has focused on viruses as natural nanomaterials. Historically studied for their effects as pathogens, recent advances have incorporated viruses as substrates for chemical modification, materials development, and therapeutic design. Here we will discuss recent advances in chemical strategies for modifying viruses, and the applications of these technologies.