Life Sciences Commons^™

Elucidation Of The Complete Azorhizobium Nicotinate Catabolism Pathway, Christopher Kitts, Jerome P. Lapointe, Van Thai Lam, Robert A. Ludwig

Biological Sciences

A complete pathway for Azorhizobium caulinodans nicotinate catabolism has been determined from mutant phenotype analyses, isolation of metabolic intermediates, and structural studies. Nicotinate serves as a respiratory electron donor to O₂ via a membrane-bound hydroxylase and a specific c-type cytochrome oxidase. The resulting oxidized product, 6-hydroxynicotinate, is next reduced to 1,4,5,6-tetrahydro-6-oxonicotinate. Hydrolytic ring breakage follows, with release of pyridine N as ammonium. Decarboxylation then releases the nicotinate C-7 carboxyl group as CO₂, and the remaining C skeleton is then oxidized to yield glutarate. Transthioesterification with succinyl coenzyme A (succinyl-CoA) yields glutaryl-CoA, which is then oxidatively decarboxylated to …

The Expression Pattern Of The Tonoplast Intrinsic Protein Γ-Tip In Arabidopsis Thaliana Is Correlated With Cell Enlargement, Edward Himelblau, Herman Hofte, Dolors Ludevid, Maarten J. Chrispeels

Biological Sciences

The vacuolar membrane (tonoplast) contains an abundant intrinsic protein with six membrane-spanning domains that is encoded by a small gene family. Different isoforms of tonoplast intrinsic protein (TIP) are expressed in different tissues or as a result of specific signals. Using promoter-β-glucuronidase (GUS) fusions and in situ hybridization, we have examined the expression of γ-TIP in Arabidopsis thaliana. GUS staining of plants transformed with promoter-GUS fusions showed that γ-TIP gene expression is high in recently formed tissues of young roots. In the shoot, γ-TIP gene expression was highest in the vascular bundles of stems and petioles, as well as …

The Occurrence And Effect Of A Protozoan Parasite, Ophryocystis Elektroscirrha (Neogregarinida: Ophryocystidae) On Overwintering Monarch Butterflies, Danaus Plexippus (Lepidoptera: Danaidae) From Two California Winter Sites, Kingston L. H. Leong, H. K. Kaya, Michael A. Yoshimura, Dennis F. Frey

Biological Sciences

1. Monarch butterflies, Danaus plexippus, from two overwintering populations, were found to have Ophryocystis elektroscirrha spores on their scales at rates between 53% and 68%. The frequency of butterflies with O.elektroscirrhaspores remained about the same between sites and throughout the winter.

2. The spores, recovered from all parts of the body of the butterfly, were most numerous on the abdomen, particularly near the posterior third.

3. Butterflies with spores survived as long as those without detectable spores at 10.1°C ±0.4 SE and 78.3% r.h. ±0.6SE. Insects with spores held at 19.4°C ±0.4SE and 44.9% r.h. ±1.5SE showed a …

Comparative Stress Dynamics Of Brood Stock Striped Bass Morone Saxatilis Associated With Two Capture Techniques, Reginal M. Harrell, Mark A. Moline

Biological Sciences

Mature striped bass (Morone saxatilis) were collected from the spawning reaches of the Choptank River, Maryland for the purpose of evaluating stress effects associated with capture. Two commonly used capture devices were evaluated—gillnetting and electrofishing. Results indicated that stress, as measured by changes in plasma corticosteroid and chloride concentrations, was significantly lower and recovery time quicker in those fish captured by electrofishing compared to gillnetting. By the end of the study period (48 h), those fish captured by electrofishing had recovered from the initial capture shock as evidenced by corticosteroid levels returning to near baseline levels. Conversely, at …

Pleistocene Terrestrial Vertebrates From Near Point San Luis, And Other Localities In San Luis Obispo County, California, George T. Jefferson, Harry L. Fierstine, John R. Wesling, Teh-Lung Ku

Biological Sciences

Terrestrial vertebrate remains were recovered from sediments that lie on remnants of the lowest marine wave-cut platform between Point Buchon and Point San Luis. Uranium series ages of these samples, which range from 83 to about 49 ka suggest a correlation to late Pleistocene climatic and eustatic events associated with marine oxygen isotope substage 5a, and establish a maximum age of ≈80 ka for the occurrence of terrestrial mammal fossils. The Point San Luis area assemblage appears typical of the late Pleistocene regional vertebrate paleofauna fauna from west-central California. Five mammalian taxa are added to the Pleistocene record from San …

Palmer Lter Program: Spatial Variability In Phytoplankton Distribution And Surface Photosynthetic Potential Within The Peninsula Grid, November 1991, Barbara B. Prezelin, Nicholas P. Boucher, Mark A. Moline, Elise Stephens, Keith Seydel, Kai Scheppe

Biological Sciences

No abstract provided.

Palmer Lter: Temporal Variability In Hplc Pigmentation And Inorganic Nutrient Distribution In Surface Waters Adjacent To Palmer Station, December 1991-February 1992, Barbara B. Prezelin, Mark A. Moline, Keith Seydel, Kai Scheppe

Biological Sciences

No abstract provided.

New Combinations In Gnaphalium (Asteraceae: Inuleae), G. Ledyard Stebbins, David J. Keil

Biological Sciences

Because of extensive morphological intermediacy, plants formerly distinguished at the species level as Gnaphalium beneolens, G. microcephalum, G. thermale, and G. wrightii are treated as intergrading races of the widespread G. canescens. The new combinations, G. canescens subsp. beneolens, G. canescens subsp. microcephalum and G. canescens subsp. thermale are made.