Open Access. Powered by Scholars. Published by Universities.®

Biology Commons™

Open Access. Powered by Scholars. Published by Universities.®

2006

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 91 - 120 of 536

Full-Text Articles in Biology

Macronuclear Genome Sequence Of The Ciliate Tetrahymena Thermophila, A Model Eukaryote, Jonathan A. Eisen, Robert S. Coyne, Martin Wu, Dongying Wu, Mathangi Thiagarajan, Jennifer R. Wortman, Jonathan H. Badger, Qinghu Ren, Paolo Amedeo, Kristie M. Jones, Luke J. Tallon, Arthur L. Delcher, Steven L. Salzberg, Joana C. Silva, Brian J. Haas, William H. Majoros, Maryam Farzad, Jane M. Carlton, Roger K. Smith, Jyoti Garg, Ronald E. Pearlman, Kathleen M. Karrer, Lei Sun, Gerard Manning, Nels C. Elde, Aaron P. Turkewitz, David J. Asai, David E. Wilkes, Yufeng Wang, Hong Cai, Kathleen Collins, B. Andrew Stewart, Suzanne R. Lee, Katarzyna Wilamowska, Zasha Weinberg, Walter L. Ruzzo, Dorota Wloga, Jacek Gaertig, Joseph Frankel, Che-Chia Tsao, Martin A. Gorovsky, Patrick J. Keeling, Ross F. Waller, Nicola J. Patron, J. Michael Cherry, Nicholas A. Stover, Cynthia J. Krieger, Christina Del Toro, Hilary F. Ryder, Sondra C. Williamson, Rebecca A. Barbeau, Eileen P. Hamilton, Eduardo Orias Sep 2006

Macronuclear Genome Sequence Of The Ciliate Tetrahymena Thermophila, A Model Eukaryote, Jonathan A. Eisen, Robert S. Coyne, Martin Wu, Dongying Wu, Mathangi Thiagarajan, Jennifer R. Wortman, Jonathan H. Badger, Qinghu Ren, Paolo Amedeo, Kristie M. Jones, Luke J. Tallon, Arthur L. Delcher, Steven L. Salzberg, Joana C. Silva, Brian J. Haas, William H. Majoros, Maryam Farzad, Jane M. Carlton, Roger K. Smith, Jyoti Garg, Ronald E. Pearlman, Kathleen M. Karrer, Lei Sun, Gerard Manning, Nels C. Elde, Aaron P. Turkewitz, David J. Asai, David E. Wilkes, Yufeng Wang, Hong Cai, Kathleen Collins, B. Andrew Stewart, Suzanne R. Lee, Katarzyna Wilamowska, Zasha Weinberg, Walter L. Ruzzo, Dorota Wloga, Jacek Gaertig, Joseph Frankel, Che-Chia Tsao, Martin A. Gorovsky, Patrick J. Keeling, Ross F. Waller, Nicola J. Patron, J. Michael Cherry, Nicholas A. Stover, Cynthia J. Krieger, Christina Del Toro, Hilary F. Ryder, Sondra C. Williamson, Rebecca A. Barbeau, Eileen P. Hamilton, Eduardo Orias

Biological Sciences Faculty Research and Publications

The ciliate Tetrahymena thermophila is a model organism for molecular and cellular biology. Like other ciliates, this species has separate germline and soma functions that are embodied by distinct nuclei within a single cell. The germline-like micronucleus (MIC) has its genome held in reserve for sexual reproduction. The soma-like macronucleus (MAC), which possesses a genome processed from that of the MIC, is the center of gene expression and does not directly contribute DNA to sexual progeny. We report here the shotgun sequencing, assembly, and analysis of the MAC genome of T. thermophila, which is approximately 104 Mb in length and …

Go to article

Retrotranspositions In Orthologous Regions Of Closely Related Grass Species, Chunguang Du, Zuzana Swigoňová, Joachim Messing Aug 2006

Retrotranspositions In Orthologous Regions Of Closely Related Grass Species, Chunguang Du, Zuzana Swigoňová, Joachim Messing

Department of Biology Faculty Scholarship and Creative Works

Background: Retrotransposons are commonly occurring eukaryotic transposable elements (TEs). Among these, long terminal repeat (LTR) retrotransposons are the most abundant TEs and can comprise 50-90% of the genome in higher plants. By comparing the orthologous chromosomal regions of closely related species, the effects of TEs on the evolution of plant genomes can be studied in detail. Results: Here, we compared the composition and organization of TEs within five orthologous chromosomal regions among three grass species: maize, sorghum, and rice. We identified a total of 132 full or fragmented LTR retrotransposons in these regions. As a percentage of the total cumulative …

Go to article

Interaction Of Ice Storms And Management Practices On Current Carbon Sequestration In Forests With Potential Mitigation Under Future Co2 Atmosphere, Heather R. Mccarthy, Ram Oren, Hyun-Seok Kim, Kurt H. Johnsen, Chris Maier, Seth G. Pritchard, Micheal Davis Aug 2006

Interaction Of Ice Storms And Management Practices On Current Carbon Sequestration In Forests With Potential Mitigation Under Future Co2 Atmosphere, Heather R. Mccarthy, Ram Oren, Hyun-Seok Kim, Kurt H. Johnsen, Chris Maier, Seth G. Pritchard, Micheal Davis

Faculty Publications

[1] Ice storms are disturbance events with potential impacts on carbon sequestration. Common forest management practices, such as fertilization and thinning, can change wood and stand properties and thus may change vulnerability to ice storm damage. At the same time, increasing atmospheric CO2 levels may also influence ice storm vulnerability. Here we show that a nonintensively managed pine plantation experienced a ∼250 g C m−2 reduction in living biomass during a single storm, equivalent to ∼30% of the annual net ecosystem carbon exchange of this ecosystem. Drawing on weather and damage survey data from the entire storm cell, …

Go to article

Integration Of Hybridization-Based Markers (Overgos) Into Physical Maps For Comparative And Evolutionary Explorations In The Genus Oryza And In Sorghum, Barbara L. Hass-Jacobus, Montona Futrell-Griggs, Brian Abernathy, Rick Westerman, Jose-Luis Goicoechea, Joshua Stein, Patricia Klein, Bonnie Hurwitz, Bin Zhou, Fariborz Rakhshan, Abhijit Sanyal, Navdeep Gill, Jer-Young Lin, Jason G. Walling, Mei Zhong Luo, Jetty Siva S Ammiraju, Dave Kudrna, Hye Ran Kim, Doreen Ware, Rod A. Wing, Phillip San Miguel, Scott A. Jackson Aug 2006

Integration Of Hybridization-Based Markers (Overgos) Into Physical Maps For Comparative And Evolutionary Explorations In The Genus Oryza And In Sorghum, Barbara L. Hass-Jacobus, Montona Futrell-Griggs, Brian Abernathy, Rick Westerman, Jose-Luis Goicoechea, Joshua Stein, Patricia Klein, Bonnie Hurwitz, Bin Zhou, Fariborz Rakhshan, Abhijit Sanyal, Navdeep Gill, Jer-Young Lin, Jason G. Walling, Mei Zhong Luo, Jetty Siva S Ammiraju, Dave Kudrna, Hye Ran Kim, Doreen Ware, Rod A. Wing, Phillip San Miguel, Scott A. Jackson

Biology Faculty Articles

Background: With the completion of the genome sequence for rice (Oryza sativa L.), the focus of rice genomics research has shifted to the comparison of the rice genome with genomes of other species for gene cloning, breeding, and evolutionary studies. The genus Oryza includes 23 species that shared a common ancestor 8–10 million years ago making this an ideal model for investigations into the processes underlying domestication, as many of the Oryza species are still undergoing domestication. This study integrates high-throughput, hybridization-based markers with BAC end sequence and fingerprint data to construct physical maps of rice chromosome 1 orthologues in …

Go to article

Population Divergence In Plasticity Of The Avt System And Its Association With Aggressive Behaviors In A Death Valley Pupfish, Sean C. Lema Aug 2006

Population Divergence In Plasticity Of The Avt System And Its Association With Aggressive Behaviors In A Death Valley Pupfish, Sean C. Lema

Biological Sciences

Behavioral differences can evolve rapidly in allopatry, but little is known about the neural bases of such changes. Allopatric populations of Amargosa pupfish (Cyprinodon nevadensis) vary in aggression and courtship behaviors in the wild. Two of these wild populations were recently found to differ in brain expression of arginine vasotocin (AVT)—a peptide hormone shown previously to modulate aggression in pupfish. These populations have been isolated for less than 4000 years, so it remained unclear whether the differences in behavior and neural AVT phenotype were evolved changes or plastic responses to ecologically dissimilar habitats. Here, I tested whether these …

Go to article

The Effects Of Dispersal And Recruitment Limitation On Community Structure Of Odonates In Artificial Ponds, Shannon J. Mccauley Aug 2006

The Effects Of Dispersal And Recruitment Limitation On Community Structure Of Odonates In Artificial Ponds, Shannon J. Mccauley

Biological Sciences

I examined the effects of isolation on the structure of both adult and larval dragonfly (Odonata: Anisoptera) communities forming at physically identical artificial ponds over two years. Isolation, whether measured by distance to the nearest source habitat or by connectivity to multiple sources, was significantly negatively related to the species richness of dragonflies observed at and collected in these ponds. These results indicate that dispersal and recruitment limitation acted as filters on the richness of communities at these artificial ponds. The richness of larval recruits in artificial ponds was lower than the richness of adult dispersers observed at ponds, and …

Go to article

Analysis Of Treatment Effects On The Microbial Ecology Of The Human Intestine, Anna L. Engelbrektson, Joshua R. Korzenik, Mary Ellen Sanders, Brian G. Clement, Gregory Leyer, Todd R. Klaenhammer, Christopher L. Kitts Aug 2006

Analysis Of Treatment Effects On The Microbial Ecology Of The Human Intestine, Anna L. Engelbrektson, Joshua R. Korzenik, Mary Ellen Sanders, Brian G. Clement, Gregory Leyer, Todd R. Klaenhammer, Christopher L. Kitts

Biological Sciences

A large number of studies have investigated gastrointestinal microbiota and changes in the gastrointestinal community. However, a concern in these studies is how best to assess changes in gastrointestinal community structure. This paper presents two different human trials where the fecal terminal restriction fragment length polymorphism data sets were analyzed to search for treatment effects. Principle components analysis and cluster analysis based on grouped data are compared with analysis of data by subject using distance coefficients. Comparison with baseline within an individual before grouping by treatment provided a clearer indication of treatment effects than did an evaluation of data grouped …

Go to article

Integrated Fisheries Management Draft Allocation Report Roe's Abalone Perth Metropolitan Region., Integrated Fisheries Allocation Advisory Committee Aug 2006

Integrated Fisheries Management Draft Allocation Report Roe's Abalone Perth Metropolitan Region., Integrated Fisheries Allocation Advisory Committee

Fisheries Management Papers

The IFAAC has prepared this report, which documents the committee’s initial position on allocations for the abalone resource, along with the reasons for its conclusions as a basis for widespread community consultation. This report follows the IFAAC’s preliminary investigation of the abalone resourcesharing issues and consultation with stakeholders

Go to article

Molecular Population Genetics And Phenotypic Diversification Of Two Populations Of The Thermophilic Cyanobacterium Mastigocladus Laminosus, Scott R. Miller, Michael D. Purugganan, Stephanie E. Curtis Aug 2006

Molecular Population Genetics And Phenotypic Diversification Of Two Populations Of The Thermophilic Cyanobacterium Mastigocladus Laminosus, Scott R. Miller, Michael D. Purugganan, Stephanie E. Curtis

Biological Sciences Faculty Publications

We investigated the distributions of genetic and phenotypic variation for two Yellowstone National Park populations of the heterocyst-forming cyanobacterium Mastigocladus (Fischerella) laminosus that exhibit dramatic phenotypic differences as a result of environmental differences in nitrogen availability. One population develops heterocysts and fixes nitrogen in situ in response to a deficiency of combined nitrogen in its environment, whereas the other population does neither due to the availability of a preferred nitrogen source. Slowly evolving molecular markers, including the 16S rRNA gene and the downstream internal transcribed spacer, are identical among all laboratory isolates from both populations but belie considerable genetic and …

Go to article

Role Of The Stable Signal Peptide Of Junín Arenavirus Envelope Glycoprotein In Ph-Dependent Membrane Fusion, Joanne York, Jack H. Nunberg Aug 2006

Role Of The Stable Signal Peptide Of Junín Arenavirus Envelope Glycoprotein In Ph-Dependent Membrane Fusion, Joanne York, Jack H. Nunberg

Biological Sciences Faculty Publications

The envelope glycoprotein of the arenaviruses (GP-C) is unusual in that the mature complex retains the cleaved, 58-amino-acid signal peptide. Association of this stable signal peptide (SSP) has been shown to be essential for intracellular trafficking and proteolytic maturation of the GP-C complex. We identify here a specific and previously unrecognized role of SSP in pH-dependent membrane fusion. Amino acid substitutions that alter the positive charge at lysine K33 in SSP affect the ability of GP-C to mediate cell-cell fusion and the threshold pH at which membrane fusion is triggered. Based on the presumed location of K33 at or near …

Go to article

Anti-Viral Activity Of Quillaja Saponaria Molina Extracts Against Hiv-1 And Hiv-2, Jennifer Lee Sprayberry Aug 2006

Anti-Viral Activity Of Quillaja Saponaria Molina Extracts Against Hiv-1 And Hiv-2, Jennifer Lee Sprayberry

Biology Theses - Archive

It has been well established that extracts from the bark of the South American tree Quillaja saponaria Molina have the capacity to stimulate strong immune responses against exogenous antigen when used as an adjuvant. However, the anti-viral capacity of Q. saponins has not been well established. We document the anti-viral capacity of Quillaja saponaria extracts against HIV-1 and HIV-2. The extract appeared to interact with the gp120 subunit of HIV-1 and HIV-2 to produce a low anti-viral effect by blocking viral attachment. The extract was also observed to coat cells in a time dependent manner and block attachment to CD4 …

Go to article

Population Genetics Of Phanaeus Vindex And P. Difformis And Congruence With Morphology Across A Geographic Zone Of Species Overlap, Aaron Michael Dickey Aug 2006

Population Genetics Of Phanaeus Vindex And P. Difformis And Congruence With Morphology Across A Geographic Zone Of Species Overlap, Aaron Michael Dickey

Biology Theses - Archive

Amplified Fragment Length Polymorphisms (AFLPs) reveal that the rainbow scarabs Phanaeus vindex (MacLeay) and Phanaeus difformis (LeConte) are distinct evolutionary units which occur in sympatry at the Fort Worth Nature Center. The genetic structure at this location is distinctly bimodal with strong segregation of taxa based on soil type. In addition, certain allele frequencies within P. vindex locations exhibited a significant correlation with a precipitation gradient and other allele frequencies within P. vindex locations were significantly different on loam soil than on both sand and clay soils. Phanaeus vindex and P. difformis exhibit continuous morphological character states between two extremes, …

Go to article

Disturbance Facilitates Invasion: The Effects Are Stronger Abroad Than At Home, José L. Hierro, Diego Villarreal, Özkan Eren, Jon M. Graham, Ragan M. Callaway Aug 2006

Disturbance Facilitates Invasion: The Effects Are Stronger Abroad Than At Home, José L. Hierro, Diego Villarreal, Özkan Eren, Jon M. Graham, Ragan M. Callaway

Biological Sciences Faculty Publications

Disturbance is one of the most important factors promoting exotic invasion. However, if disturbance per se is sufficient to explain exotic success, then "invasion" abroad should not differ from "colonization" at home. Comparisons of the effects of disturbance on organisms in their native and introduced ranges are crucial to elucidate whether this is the case; however, such comparisons have not been conducted. We investigated the effects of disturbance on the success of Eurasian native Centaurea solstitialis in two invaded regions, California and Argentina, and one native region, Turkey, by conducting field experiments consisting of simulating different disturbances and adding locally …

Go to article

Use Of Temperature Sensitive Mutants To Map Reovirus Induced Oncolysis, Ka Ian Tam Aug 2006

Use Of Temperature Sensitive Mutants To Map Reovirus Induced Oncolysis, Ka Ian Tam

Biology Theses - Archive

Reovirus is known to establish persistent infections in normal cells while selectively destroying transformed cells. Individual viruses from each of the ten groups of Reovirus is known to establish persistent infections in normal cells while selectively destroying transformed cells. Individual viruses from each of the ten groups of Reovirus temperature sensitive mutants were used to examine the gene or genes involved in the differential lysis activity. Temperature sensitive mutants were generated by chemical mutagenesis and have one of the ten genes impaired when growing at the non-permissive temperature, while they behave like wild type when growing at the permissive temperature. …

Go to article

Chironomid Hemoglobin Genetic Diversity As An Indicator Of The New Jersey Hackensack Meadowlands Wetland Health, Lene Marie De Coursin Jacobs Aug 2006

Chironomid Hemoglobin Genetic Diversity As An Indicator Of The New Jersey Hackensack Meadowlands Wetland Health, Lene Marie De Coursin Jacobs

Seton Hall University Dissertations and Theses (ETDs)

Kearny Marsh located within the Hackensack Meadowlands is a freshwater wetland impacted by multiple environmental stressors from human activity. The marsh is located in the northeastern New Jersey metropolitan area. Chironomid larvae, aquatic larvae of midge fly, were analyzed from two Kearny Marsh sample sites, W9 and W22. A previous sediment analysis and toxicity study characterized heavy metal contaminants the marsh. The data results were applied in this thesis study to determine the correlation between environmental stressors and chironomid genetic diversity. Site W9 sediment was impacted by severe levels of total heavy metal contamination, whereas site W22 had just below …

Go to article

Characterization Of Membrane Potentials In Vascular Smooth Muscle Of Hagfish, Lamprey And Trout, Prentiss Jones Jr. Aug 2006

Characterization Of Membrane Potentials In Vascular Smooth Muscle Of Hagfish, Lamprey And Trout, Prentiss Jones Jr.

Dissertations

The objective of this study was to characterize membrane potentials in systemic arteries of Pacific hagfish, Eptatretus stouti, Rainbow trout, Onchorhyncus mykiss, and Sea lamprey Petromyzon marinus. Previous studies have characterized membrane potentials in piscine tissue. However, these studies utilized non-vascular tissues such as cardiac muscle and skeletal muscle (69, 161). Characterization of membrane potentials in fish vasculature is without precedent in the literature. The hypothesis of this study was that membrane potentials in fish vascular smooth muscle differ little between species when comparable vasculature is evaluated.

Go to article

Identification And Characterization Of Cellular Targets Of The Bacterial Cytotoxin Yopt In Saccharomyces Cerevisiae, Paul David Caccamo Aug 2006

Identification And Characterization Of Cellular Targets Of The Bacterial Cytotoxin Yopt In Saccharomyces Cerevisiae, Paul David Caccamo

Masters Theses

Human pathogenic Yersinia spp. utilize Type III Secretion to deliver six effector proteins into host cells. The injected proteins resemble eukaryotic signal transduction molecules and are capable of disrupting signaling pathways in order to subvert the functions of the targeted cell or disrupt communication with surrounding cells. As a result, bacterial invaders are not only able to survive the threat of a host immune response, but can thrive despite it. YopT is a cysteine protease that cleaves RhoGTPases, releasing them from the membrane and thus from their role as initiators of signaling pathways, including the nucleation of actin and …

Go to article

Changes In Microbial Community Structure Of Petroleum Contaminated Sediments Are Reflected In Subsurface Geophysical Signatures, Jonathan P. Allen Aug 2006

Changes In Microbial Community Structure Of Petroleum Contaminated Sediments Are Reflected In Subsurface Geophysical Signatures, Jonathan P. Allen

Masters Theses

Petroleum contamination of sediments leads to dynamic changes in the subsurface. These include changes in the microbiota as well as in the subsurface geophysical and geochemical properties. Anomalously high conductivity values observed in subsurface zones contaminated with light non aqueous phase liquids (LNAPLs) have been suggested to be the result of microbial activity. Therefore, we investigated the interdependence between geoelectrical signatures and microbial community structure in petroleum contaminated field sediments and laboratory column experiments. Spatial and temporal changes in electrical conductivity of the subsurface paralleled changes in microbial community composition, with the highest conductivity values concomitant with specific anaerobic hydrocarbon-degrading …

Go to article

Genetic Considerations For The Conservation And Management Of Yellowstone Cutthroat Trout (Oncorhynchus Clarkii Bouvieri) In Yellowstone National Park, David J. Janetski Aug 2006

Genetic Considerations For The Conservation And Management Of Yellowstone Cutthroat Trout (Oncorhynchus Clarkii Bouvieri) In Yellowstone National Park, David J. Janetski

Theses and Dissertations

A key component to conservation is an accurate understanding of genetic subdivision within a species. Despite their ecological and economic importance, relatively little is understood about the genetic structuring of Yellowstone cutthroat trout in Yellowstone National Park. Here, we use traditional (Fst, Rst, Nm, and AMOVA) and modern (Bayesian assignment tests, coalescent theory, and nested clade analysis) analytical approaches to describe the population genetic subdivision of cutthroat trout spawning populations in Yellowstone Lake and to identify genetically distinct population segments throughout Yellowstone National Park. Evidence for restricted gene flow between spawning populations within Yellowstone Lake was detected using nested clade …

Go to article

The Influence Of Low Humidity, Pseudacteon Flies, And Competition By Solenopsis Xyloni On Solenopsis Invicta, Ricardo A. Ramirez, D C. Thompson, M D. Remmenga Aug 2006

The Influence Of Low Humidity, Pseudacteon Flies, And Competition By Solenopsis Xyloni On Solenopsis Invicta, Ricardo A. Ramirez, D C. Thompson, M D. Remmenga

Biology Faculty Publications

Red imported fire ant, Solenopsis invicta Buren, is a serious pest in the southeastern United States. It has caused economic losses in agricultural products, stings can cause anaphylactic shock, and it has reduced biodiversity. S. invicta has displaced native ant species throughout its range, presumably by competitive exclusion. In 1998, S. invicta populations were confirmed in southern New Mexico, resulting in a quarantine of Doña Ana County. Although large populations of the native southern fire ant, S. xyloniMcCook, are common in the Mesilla Valley, only two small populations of S. invicta have been found since the initial quarantine. It is …

Go to article

Notes On Invasive Plants In The Rio Grande Delta Of Cameron County, Texas., Robert I. Lonard, Frank W. Judd Aug 2006

Notes On Invasive Plants In The Rio Grande Delta Of Cameron County, Texas., Robert I. Lonard, Frank W. Judd

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

No abstract provided.

Go to article

Oxidase-Coupled Amperometric Glucose And Lactate Sensors With Integrated Electrochemical Actuation System, Jongwon Park, Chang-Soo Kim, Minsu Choi Aug 2006

Oxidase-Coupled Amperometric Glucose And Lactate Sensors With Integrated Electrochemical Actuation System, Jongwon Park, Chang-Soo Kim, Minsu Choi

Electrical and Computer Engineering Faculty Research & Creative Works

Unpredictable baseline drift and sensitivity degradation during continuous use are two of the most significant problems of biosensors including the amperometric glucose and lactate sensors. Therefore, the capability of on-demand in situ calibration/diagnosis of biochemical sensors is indispensable for reliable long-term monitoring with minimum attendance. Another limitation of oxidase enzyme-based biosensors is the dependence of enzyme activity on the background oxygen concentration in sample solution. In order to address these issues, the electrolytic generation of oxygen and hydrogen bubbles were utilized 1) to overcome the background oxygen dependence of glucose and lactate sensors and 2) to demonstrate the feasibility of …

Go to article

Mbet3p Is Required For Homotypic Copii Vesicle Tethering In Mammalian Cells, Sidney Yu, Ayano Satoh, Marc Pypaert, Karl Mullen, Jesse C. Hay, Susan Ferro-Novick Jul 2006

Mbet3p Is Required For Homotypic Copii Vesicle Tethering In Mammalian Cells, Sidney Yu, Ayano Satoh, Marc Pypaert, Karl Mullen, Jesse C. Hay, Susan Ferro-Novick

Biological Sciences Faculty Publications

TRAPPI is a large complex that mediates the tethering of COPII vesicles to the Golgi (heterotypic tethering) in the yeast Saccharomyces cerevisiae. In mammalian cells, COPII vesicles derived from the transitional endoplasmic reticulum (tER) do not tether directly to the Golgi, instead, they appear to tether to each other ( homotypic tethering) to form vesicular tubular clusters (VTCs). We show that mammalian Bet3p (mBet3p), which is the most highly conserved TRAPP subunit, resides on the tER and adjacent VTCs. The inactivation of mBet3p results in the accumulation of cargo in membranes that colocalize with the COPII coat. Furthermore, using an …

Go to article

Genetics And Inheritance Of Seed Dormancy Inflicted By Seed- Coat Factors In Rice (Oryza Sativa L.), Z. L. Kanyeka Jul 2006

Genetics And Inheritance Of Seed Dormancy Inflicted By Seed- Coat Factors In Rice (Oryza Sativa L.), Z. L. Kanyeka

Tanzania Journal of Science

The study was undertaken to investigate the genetic mode of inheritance of dormancy imposed by the hull (seed coat) in rice seeds. Freshly harvested seeds of parents, F1 and F2 populations of a cross between a dormant cultivar Kisegese and non-dormant strain K2004 were used. Germination test of the de-hulled (without seed coat) and un-dehulled (whole or with seed coat) seeds were conducted at 10 days intervals starting at 15 days after harvesting (15DAH) for 65 days. The seeds were sown in petri dishes. Numbers of germinated and un-germinated seeds were recorded at 7 days after sowing. Germination of seeds …

Go to article

Pathogenecity Of Two Strains Of Rice Yellow Mottle Virus On Aromatic Rice Cultivars, Z. L. Kanyeka Jul 2006

Pathogenecity Of Two Strains Of Rice Yellow Mottle Virus On Aromatic Rice Cultivars, Z. L. Kanyeka

Tanzania Journal of Science

Development of rice cultivars with resistance to rice yellow mottle virus (RYMV) requires characterization of pathogenecity of existing strains against susceptible cultivars. The pathogenecity of two RYMV strains; S4 and S“New” identified in Tanzania were assessed against seven local and introduced rice genotypes including cultivars Zambia, ITA173 and TXD 88. The two virus strains showed similar effects on the rice cultivar Zambia killing all the plants at 25d after inoculation. The strains significantly reduced the plant height, panicle length, and number of tillers per pot and total dry matter of all the two cultivars. In another trial, the pathogenecity of …

Go to article

Occurrence Of Metacercariae Of Diplostomum And Tylodelphys Species (Diplostomidae) In Clarias Species (Clariidae) Fishes From Lake Victoria, M. J. Musiba, G. Nkwengulila Jul 2006

Occurrence Of Metacercariae Of Diplostomum And Tylodelphys Species (Diplostomidae) In Clarias Species (Clariidae) Fishes From Lake Victoria, M. J. Musiba, G. Nkwengulila

Tanzania Journal of Science

The localisation and abundance of the metacercariae of Diplostomum and Tylodelphys species among the clariids of Lake Victoria were investigated between April and December 2001. Four species viz. Clarias gariepinus (271), C. alluaudi (65), C. werneri (50) and C. liocephalus (47) were examined, but only C. gariepinus was infected in the brain case and along the nasal cavity. Prevalence of metacercariae was high (>70%). Prevalence and mean intensity were similar between male and female fish. Mean intensity increased with fish size and declined in larger fish for D. mashonense; but declined with the increase in fish size for Tylodelphys …

Go to article

Diversity And Abundance Of Small Mammals In The Serengeti Kopjes, Tanzania, C. D. Timbuka, J. D. Kabigumila Jul 2006

Diversity And Abundance Of Small Mammals In The Serengeti Kopjes, Tanzania, C. D. Timbuka, J. D. Kabigumila

Tanzania Journal of Science

Diversity and abundance of small mammals in the Serengeti kopjes were studied between November 2000 and February 2002. From 22,500 trap-nights and 3,300 bucket-nights, 4,903 small mammals in 18 species, 14 genera, 6 families and 3 orders were recorded. Muridae was the most dominant family with nine species. The highest number of species was recorded in the Maasai (14), Mbuzi Mawe (13) and Seronera (12) kopjes. The least number of species recorded in the Simba, Barafu and Wogakuria kopjes, with eight species each. Species diversity was highest in the Maasai kopjes (H'=2.337) and lowest in the Wogakuria kopjes (H'=1.794), with …

Go to article

Biogeography Of Buarremon Brush-Finches (Aves, Emberizinae): Integrating Ecology, Evolution, And Systematics, Carlos Daniel Cadena Jul 2006

Biogeography Of Buarremon Brush-Finches (Aves, Emberizinae): Integrating Ecology, Evolution, And Systematics, Carlos Daniel Cadena

Dissertations

Ecological and historical approaches to studying species¿ geographic ranges have yet to be unified. Ideal scenarios for integrating ecology with evolutionary biology in biogeography are those where contemporary ecological interactions may have influenced species¿ distributions historically, driving the evolution of ecological niches. I focused on understanding the origin of elevational distributions of species, and specifically on the role of interspecific competition in the origin of complementary elevational ranges. To test hypotheses about the origin of elevational distributions, I followed a combined approach involving molecular phylogenetics, phylogeography, population genetics, and ecological niche modeling. I focused on Buarremon torquatus and B. brunneinucha …

Go to article

A Subset Of Arabidopsis Ap2 Transcription Factors Mediates Cytokinin Responses In Concert With A Two-Component Pathway, Aaron M. Rashotte, Michael G. Mason, Claire E. Hutchison, Fernando J. Ferreira, G. Eric Schaller, Joseph J. Kieber Jul 2006

A Subset Of Arabidopsis Ap2 Transcription Factors Mediates Cytokinin Responses In Concert With A Two-Component Pathway, Aaron M. Rashotte, Michael G. Mason, Claire E. Hutchison, Fernando J. Ferreira, G. Eric Schaller, Joseph J. Kieber

Dartmouth Scholarship

The plant hormone cytokinin regulates numerous growth and developmental processes. A signal transduction pathway for cytokinin has been elucidated that is similar to bacterial two-component phosphorelays. In Arabidopsis, this pathway is comprised of receptors that are similar to sensor histidine kinases, histidine-containing phosphotransfer proteins, and response regulators (ARRs). There are two classes of response regulators, the type-A ARRs, which act as negative regulators of cytokinin responses, and the type-B ARRs, which are transcription factors that play a positive role in mediating cytokinin-regulated gene expression. Here we show that several closely related members of the Arabidopsis AP2 gene family of …

Go to article

Progeny Of Germ Line Knockouts Of Asi2, A Gene Encoding A Putative Signal Transduction Receptor In Tetrahymena Thermophila, Fail To Make The Transition From Sexual Reproduction To Vegetative Growth, Shuqiang Li, Lihui Yin, Eric S. Cole, Rupa A. Udani, Kathleen M. Karrer Jul 2006

Progeny Of Germ Line Knockouts Of Asi2, A Gene Encoding A Putative Signal Transduction Receptor In Tetrahymena Thermophila, Fail To Make The Transition From Sexual Reproduction To Vegetative Growth, Shuqiang Li, Lihui Yin, Eric S. Cole, Rupa A. Udani, Kathleen M. Karrer

Biological Sciences Faculty Research and Publications

The ciliated protozoan Tetrahymena has two nuclei: a germ line micronucleus and a somatic macronucleus. The transcriptionally active macronucleus has about 50 copies of each chromosome. At sexual reproduction (conjugation), the parental macronucleus is degraded and new macronucleus develops from a mitotic product of the zygotic micronucleus. Development of the macronucleus involves massive genome remodeling, including deletion of about 6000 specific internal eliminated sequences (IES) and multiple rounds of DNA replication. A gene encoding a putative signal transduction receptor, ASI2, (anlagen stage induced 2) is up-regulated during development of the new macronuclei (anlagen). Macronuclear ASI2 is nonessential for vegetative …

Go to article

First Prev Next Last