Biology Commons^™

Review Of Survival, Reproduction, And Behavior By J.R. Krebs And N.B. Davies, Marlene Zuk, Torgeir S. Johnsen, Gita R. Kolluru, Kurt A. Mckean, Bradd Schulke

Biological Sciences

No abstract provided.

The Role Of Enzyme Activation State In Limiting Carbon Assimilation Under Variable Light Conditions, Gretchen F. Sassenrath-Cole, Robert W. Pearcy, Scott J. Steinmaus

Biological Sciences

The mechanisms regulating transient photosynthesis by soybean (Glycine max) leaves were examined by comparing photosynthetic rates and carbon reduction cycle enzyme activities under flashing (saturating 1 s lightflecks separated by low photon flux density (PFD) periods of different durations) and continuous PFD. At the same mean PFD, the mean photosynthetic rates were reduced under flashing as compared to continuous light. However, as the duration of the low PFD period lengthened, the CO₂ assimilation attributable to a lightfleck increased. This enhanced lightfleck CO₂ assimilation was accounted for by a greater postillumination CO₂ fixation occurring after the …

Disparate Rates Of Molecular Evolution In Cospeciating Hosts And Parasites, M. S. Hafner, P. D. Sudman, F. X. Villablanca, T. A. Spradling, J. W. Demastes, S. A. Nadler

Biological Sciences

DNA sequences for the gene encoding mitochondrial cytochrome oxidase I in a group of rodents (pocket gophers) and their ectoparasites (chewing lice) provide evidence for cospeciation and reveal different rates of molecular evolution in the hosts and their parasites. The overall rate of nucleotide substitution (both silent and replacement changes) is approximately three times higher in lice, and the rate of synonymous substitution (based on analysis of fourfold degenerate sites) is approximately an order of magnitude greater in lice. The difference in synonymous substitution rate between lice and gophers correlates with a difference of similar magnitude in generation times.

Azorhizobium Caulinodans Respires With At Least Four Terminal Oxidases, Christopher Kitts, Robert A. Ludwig

Biological Sciences

In culture, Azorhizobium caulinodans used at least four terminal oxidases, cytochrome aa₃ (cytaa₃), cytd, cyto, and a second a-type cytochrome, which together mediated general, respiratory electron (e^-) transport to O₂. To genetically dissect physiological roles for these various terminal oxidases, corresponding Azorhizobium apocytochrome genes were cloned, and three cytaa₃ mutants, a cytd mutant, and a cytaa₃, cytd double mutant were constructed by reverse genetics. These cytochrome oxidase mutants were tested for growth, oxidase activities, and N₂ fixation properties both …

Palmer Lter: Impact Of A Large Diatom Bloom On Macronutrient Distribution In Arthur Harbor During Austral Summer 1991-1992, Mark A. Moline, Barbara B. Prezelin

Biological Sciences

No abstract provided.

Impalement Of Marine Turtles (Reptilia, Chelonia: Cheloniidae And Dermochelyidae) By Billfishes (Osteichthyes, Perciformes: Istiophoridae And Xiphiidae), John G. Frazier, Harry L. Fierstine, Sallie C. Beavers, Federico Achaval, Hiroyuki Suganuma, Robert L. Pitman, Yuichiro Yamaguchi, Carlos Ma. Prigioni

Biological Sciences

Billfishes have long been known to impale a great variety of objects, but there are only two brief, obscure records of marine turtles being speared. Details are presented on these two, as well as on two other confirmed records; data from two additional unconfirmed records are also presented. In total, three species of marine turtles are known to have been impaled by three species of billfishes; a fourth species of fish and a fourth species turtle are listed in an unconfirmed case. Records come from the eastern and western Pacific as well as the eastern Atlantic. Of the four confirmed …

Icecolors '93: Biological Weighting Function For The Ultraviolet Inhibition Of Carbon Fixation In A Natural Antarctic Phytoplankton Community, Nicholas Boucher, Barbara B. Prezelin, T. Evens, R. Jovine, B. Kroon, Mark A. Moline, Oscar Schofield

Biological Sciences

No abstract provided.

Palmer Lter: Photoadaptation In A Coastal Phytoplankton Bloom And Impact On The Radiation Utilization Efficiency For Carbon Fixation, Oscar Schofield, Barbara B. Prezelin, Mark A. Moline

Biological Sciences

No abstract provided.

Spatial And Temporal Aspects Of Populations Revealed By Mitochondrial Dna, Francis X. Villablanca

Biological Sciences

The evolutionary analysis of DNA sequences bridges phylogenetics and population genetics. Ancient DNA (aDNA) alJows the study of extinct genotypes, populations, and species, as well as dichronic comparisons of extant populations and species. Thus a DNA forges an empirical link between history and two inherently historical fields of research. Fortunately, the conceptual frameworks of phylogenetics and population genetics can easily be extended to encompass advances being made in the study of aDNA.

Can Microhabitat Selection Or Differences In 'Catchability' Explain Male-Biased Sex Ratios In Overwintering Populations Of Monarch Butterflies?, Dennis F. Frey, Kingston L.H. Leong

Biological Sciences

No abstract provided.

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 …

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 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.

Review Of Pacific Marlins: Anatomy And Physiology, By Peter S. Davie, Harry L. Fierstine

Biological Sciences

No abstract provided.

Spatial And Temporal Continuity Of Kangaroo Rat Populations Shown By Sequencing Mitochondrial Dna From Museum Specimens, W. Kelley Thomas, Svante Pääbo, Francis X. Villablanca, Allan C. Wilson

Biological Sciences

The advent of direct sequencing via the polymerase chain reaction (PCR) has opened up the possibility of molecular studies on museum specimens. Here we analyze genetic variation in populations over time by applying PCR to DNA extracted from museum specimens sampled from populations of one species over the last 78 years. Included in this study were 43 museum specimens of the Panamint kangaroo ratDipodomys panamintinus from localities representing each of three geographically distinct subspecies. These specimens were originally collected and prepared as dried skins in 1911, 1917, or 1937. For each specimen, a 225-bp segment of the mitochondrial genome …

A Paleontological Review Of Three Billfish Families (Istiophoridae, Xiphiidae, And Xiphiorhynchidae), Harry L. Fierstine

Biological Sciences

No abstract provided.

Documented Chromosome Numbers 1990: 1. Miscellaneous North American Vascular Plants, Bruce D. Parfitt, Donald J. Pinkava, Debbie Rickel, Dan Fillipi, Beth Eggers, David J. Keil

Biological Sciences

The following meiotic chromosome counts are documented by specimens deposited in Herbarium of Arizona State University (ASU). Previously uncounted taxa are represented by an asterisk (*). A double asterisk (**) indicates a new number for the species.

Porophyllum Pygmaeum (Asteraceae), A Distinctive New Species From Southern Nevada, David J. Keil, James D. Morefield

Biological Sciences

Porophyllum pygmaeum is a new species from coarse calcareous soils of the Desert National Wildlife Range in Clark Co., Nevada. It has subterete leaves that contain a continuous double layer of palisade mesophyll surrounding a central area of larger, achlorophyllous, polyhedral parenchyma cells and veins. The hollow foliar oil glands lie just below the abaxial epidermis and are deeply invaginated within the parenchyma layers. Porophyllum pygmaeum is a tetraploid (n = 24) perennial herb that apparently is most closely related to P. greggii a hexaploid herbaceous species of western Texas with much longer and narrower leaves. In its fleshy subterete …

Dynamics Of Mitochondrial Dna Evolution In Animals: Amplification And Sequencing With Conserved Primers, T. D. Kocher, W. K. Thomas, A. Meyer, S. V. Edwards, S. Pääbo, F. X. Villablanca, A. C. Wilson

Biological Sciences

With a standard set of primers directed toward conserved regions, we have used the polymerase chain reaction to amplify homologous segments of mtDNA from more than 100 animal species, including mammals, birds, amphibians, fishes, and some invertebrates. Amplification and direct sequencing were possible using unpurified mtDNA from nanogram samples of fresh specimens and microgram amounts of tissues preserved for months in alcohol or decades in the dry state. The bird and fish sequences evolve with the same strong bias toward transitions that holds for mammals. However, because the light strand of birds is deficient in thymine, thymine to cytosine transitions …

Identification Of Cyclic Intermediates In Azorhizobium Caulinodans Nicotinate Catabolism, Christopher Kitts, Lisa E. Schaechter, Ross S. Rabin, Robert A. Ludwig

Biological Sciences

In wild-type Azorhizobium caulinodans ORS571, nicotinate served both as anabolic substrate for NAD⁺ production and as catabolic substrate for use as the N source. Catabolic enzyme activities were greatest from cultures grown with nicotinate as the N source and least when cultures were grown with ammonium as the N source. Vector insertion mutants unable to catabolize nicotinate (nic::Vi mutants) still required micromolar quantities of this compound for growth. Therefore, A. caulinodans wild type is NAD⁺ auxotrophic. As the first two intermediates in A. caulinodans nicotinate catabolism, two cyclic compounds, 6-hydroxynicotinate and 1,4,5,6-tetrahydro-6-oxonicotinate, were identified. These compounds …

Annual Variation Of Estuarine And Oceanic Oyster Crassostrea Virginica Gmelin Hemocyte Capacity, William S. Fisher, Marnita M. Chintala, Mark A. Moline

Biological Sciences

Defense-related hemocyte activities of American oysters Crassostrea virginica Gmelin from an oceanic and an estuarine habitat were monitored from spring to winter of 1987 at a constant temperature (15 °C). The ability of cells to spread to an ameboid shape in vitro at ambient salinity and after an acute change in salinity was much reduced from late spring to early fall. This summer-stress period was also indicated by laboratory experiments. Stress may have been due to high water temperatures but spawning efforts may have also contributed. Reduced hemocyte activity occurred at a time when infections by two major oyster parasites …

Plant Photosensitizers: A Survey Of Their Occurrence In Arid And Semiarid Plants From North America, Kelsey R. Downum, Sergio Villegas, Eloy Rodriguez, David J. Keil

Biological Sciences

No abstract provided.

Chromosome Studies In Asteraceae From The United States, Mexico, The West Indies, And South America, David J. Keil, Melissa A. Luckow, Donald J. Pinkava

Biological Sciences

Chromosome counts of Asteraceae are reported from Mexico, the United States, the West Indies, Peru, and Bolivia. First counts are reported for 27 species, eight infraspecific taxa, and three interspecific hybrids in Brickellia , Chrysanthellum, Cirsium, Egletes, Erigeron, Flaveria, Gnaphalium, Heterotheca, Hieracium, Hymenothrix, Koanophyllon, Layia, Lessingia, Pectis, Sclerocarpus, Stuessya, Tagetes and Wedelia. Counts are also reported for 196 taxa or hybrids for which chromosome numbers have been published previously. Of these, nine are new numbers. Taxonomic implications of certain counts are discussed.

Makaira Sp., Cf. M. Nigricans Lacepede, 1802 (Teleostei: Perciformes: Istiophoridae) From The Eastover Formation, Late Miocene, Virginia, And A Reexamination Of Istiophorus Calvertensis Berry, 1917, Harry L. Fierstine

Biological Sciences

An incomplete, disarticulated skull (USNM 375733) is described and referred to Makaira sp., d. M. nigricalls, and a rostrum, tIstiophonls call'ertensis Berry. 1917 (USNM 9344. holotype). is re-identified as IstiopllOrus sp., cf. I. platypterus. Both specimens are from the Eastover Formation (early late Miocene, Virginia) and are the oldest records in. deposits bordering the western North Atlantic Ocean. Istioplwrus sp.. cf. I. p/atvpterus (= tlstiophorus ca/vertensls ) IS the oldest record of the specIes. Based on ecological requirements of Recent species. the prescnce of Istiophorus sp., cL I. p/arypterus and Makaira sp., cf. M. nigricans in the Eastover Formation indicates …

A Late Miocene Marlin, Makaira Sp. (Perciformes, Osteichthyes) From San Diego County, California, U.S.A., Harry L. Fierstine, Bruce J. Welton

Biological Sciences

Fossil bones collected in the latest Miocene (= either late Clarendonian or early Hemphillian North American Land IvIammal Age), San Mateo Formation, near Oceanside, San Diego County, California, C. S.A., belong to a single specimen of the genus Makaira, species undetermined, and is part of the San Luis Rey River Local Fauna. For the genus, this represents the fifth discovery in fossil deposits bordering or within the Pacific Ocean region, and the third discovery in southern California, The specimen is within the known geochronological distribution of the genus (Late Miocene to Recent), provides further evidence that the coastal palaeoclimate of …