Characterization and developmental patterns of telomerase expression in plants

Telomerase activity is developmentally regulated in mammals. Here we examine telomerase activity in plants, whose development differs in fundamental ways from that of animals. Using a modified version of the telomere repeat amplification protocol (TRAP) assay, we detected an activity in extracts from carrots, cauliflower, soybean, Arabidopsis, and rice with all the characteristics expected for a telomerase synthesizing the plant telomere repeat sequence TTTAGGG. The activity was dependent on RNA and protein components, required dGTP, dATP, and dTTP, but not dCTP, and generated products with a seven nucleotide periodicity. Telomerase activity was abundant in cauliflower meristematic tissue and undifferentiated cells from Arabidopsis, soybean, and carrot suspension cultures, but was low or not detectable in a sampling of differentiated tissues from mature plants. Telomerase from cauliflower meristematic tissues exhibited relaxed DNA sequence requirements, which might reflect the capacity to form telomeres on broken chromosomes in vivo. The dramatic differences in telomerase expression and their correlation with cellular proliferation capacity mirror changes in human telomerase levels during differentiation and immortalization. Hence, telomerase activation appears to be a conserved mechanism involved in conferring long-term proliferation capacity.

Temporal and Spatial Patterns of Accumulation of the Transcript of Myo-Inositol-1-Phosphate Synthase and Phytin-Containing Particles during Seed Development in Rice1

Myo-inositol-1-phosphate (I[1]P) synthase (EC 5.5.1.4) catalyzes the reaction from glucose 6-phosphate to I(1)P, the first step of myo-inositol biosynthesis. Among the metabolites of I(1)P is inositol hexakisphosphate, which forms a mixed salt called phytin or phytate, a storage form of phosphate and cations in seeds. We have isolated a rice (Oryza sativa L.) cDNA clone, pRINO1, that is highly homologous to the I(1)P synthase from yeast and plants. Northern analysis of total RNA showed that the transcript accumulated to high levels in embryos but was undetectable in shoots, roots, and flowers. In situ hybridization of developing seeds showed that the transcript first appeared in the apical region of globular-stage embryos 2 d after anthesis (DAA). Strong signals were detected in the scutellum and aleurone layer after 4 DAA. The level of the transcript in these cells increased until 7 DAA, after which time it gradually decreased. Phytin-containing particles called globoids appeared 4 DAA in the scutellum and aleurone layer, coinciding with the localization of the RINO1 transcript. The temporal and spatial patterns of accumulation of the RINO1 transcript and globoids suggest that I(1)P synthase directs phytin biosynthesis in rice seeds.

A 20-nucleotide element in the intestinal fatty acid binding protein gene modulates its cell lineage-specific, differentiation-dependent, and cephalocaudal patterns of expression in transgenic mice.

A sequence of epithelial cell proliferation, allocation to four principal lineages, migration-associated differentiation, and cell loss occurs along the crypt-villus axis of the mouse intestine. The sequence is completed in a few days and is recapitulated throughout the life-span of the animal. We have used an intestine-specific fatty acid binding protein gene, Fabpi, as a model for studying regulation of gene expression in this unique developmental system. Promoter mapping studies in transgenic mice identified a 20-bp cis-acting element (5'-AGGTGGAAGCCATCACACTT-3') that binds small intestinal nuclear proteins and participates in the control of Fabpi's cephalocaudal, differentiation-dependent, and cell lineage-specific patterns of expression. Immunocytochemical studies using confocal and electron microscopy indicate that it does so by acting as a suppressor of gene expression in the distal small intestine/colon, as a suppressor of gene activation in proliferating and nonproliferating cells located in the crypts of Lieberkühn, and as a suppressor of expression in the growth factor and defensin-producing Paneth cell lineage. The 20-bp domain has no obvious sequence similarities to known transcription factor binding sites. The three functions modulated by this compact element represent the types of functions required to establish and maintain the intestine's remarkably complex spatial patterns of gene expression. The transgenes described in this report also appear to be useful in characterizing the crypt's stem cell hierarchy.

Competing Lipid-Protein and Protein-Protein Interactions Determine Clustering and Gating Patterns in the Potassium Channel from Streptomyces lividans (KcsA)

There is increasing evidence to support the notion that membrane proteins, instead of being isolated components floating in a fluid lipid environment, can be assembled into supramolecular complexes that take part in a variety of cooperative cellular functions. The interplay between lipid-protein and protein-protein interactions is expected to be a determinant factor in the assembly and dynamics of such membrane complexes. Here we report on a role of anionic phospholipids in determining the extent of clustering of KcsA, a model potassium channel. Assembly/disassembly of channel clusters occurs, at least partly, as a consequence of competing lipid-protein and protein-protein interactions at nonannular lipid binding sites on the channel surface and brings about profound changes in the gating properties of the channel. Our results suggest that these latter effects of anionic lipids are mediated via the Trp67–Glu71–Asp80 inactivation triad within the channel structure and its bearing on the selectivity filter.

The adaptive response of humans to exercise: Impact of exercise intensity, fibre-type specific responses and molecular patterns of response

In an attempt to improve the current understanding of the adaptive response to exercise in humans, this dissertation performed a series of studies designed to examine the impact of training intensity and mode on aerobic capacity and performance, fibre-type specific adaptations to training, and individual patterns of response across molecular, morphological and genetic factors. Project #1 determined that training intensity, session dose, baseline VO2max and total training volume do not influence the magnitude of change in VO2max by performing a meta-regression, and meta-analysis of 28 different studies. The intensity of training had no effect on the magnitude of increase in maximal oxygen uptake in young healthy participants, but similar adaptations were achieved with lower training doses following high intensity training. Project # 2 determined the acute molecular response, and training-induced adaptations in aerobic performance, aerobic capacity and muscle phenotype following high-intensity interval training (HIT) or endurance exercise (END). The acute molecular response (fibre recruitment and signal activation) and training-induced adaptations in aerobic capacity, aerobic performance, and muscle phenotype were similar following HIT and END. Project # 3 examined the impact of baseline muscle morphology and molecular characteristics on the training response, and if muscle adaptations are coordinated. The muscle phenotype of individuals who experience the largest improvements (high responders) were lower before training for some muscle characteristics and molecular adaptations were coordinated within individual participants. Project # 4 examined the impact of 2 different intensities of HIT on the expression of nuclear and mitochondrial encoded genes targeted by PGC-1α. A systematic upregulation of nuclear and mitochondrial encoded genes was not present in the early recovery period following acute HIT, but the expression of mitochondrial genes were coordinated at an individual level. Collectively, results from the current dissertation contribute to our understanding of the molecular mechanisms influencing skeletal muscle and whole-body adaptive responses to acute exercise and training in humans.

Referential hierarchies: A new look at some historical and typological patterns

This paper proposes a diachronic typology for the various patterns that have been referred to as Hierarchical Alignment or Inverse Alignment. Previous typological studies have tried to explain such patterns as grammatical reflections of a universal Referential Hierarchy, in which first person outranks second person outranks third person and humans outrank other animates outrank inanimates. However, our study shows that most of the formal properties of hierarchy-sensitive constructions are essentially predictable from their historical sources. We have identified three sources for hierarchical person marking, three for direction marking, two for obviative case marking, and one for hierarchical constituent ordering. These sources suggest that there is more than one explanation for hierarchical alignment: one is consistent with Givón’s claim that hierarchical patterns are a grammaticalization of generic topicality; another is consistent with DeLancey’s claim that hierarchies reflect the deictic distinction between present (1/2) and distant (3) participants; another is simply a new manifestation of a common asymmetrical pattern, the use of zero marking for third persons. More importantly, the evolution of hierarchical grammatical patterns does not reflect a consistent universal ranking of participants – at least in those cases where we can see (or infer) historical stages in the evolution of these properties, different historical stages appear to reflect different hierarchical rankings of participants, especially first and second person. This leads us to conclude that the diversity of hierarchical patterns is an artifact of grammatical change, and that in general, the presence of hierarchical patterns in synchronic grammars is not somehow conditioned by some more general universal hierarchy.

Relationships between wholebody vibration and morbidity patterns among interstate truck drivers /

"Contract no. CDC-99-74-22."

Restoring international balance [microform] : Japan's trade and investment patterns : a staff study /

"July 6, 1988."

Daytime roadside survey: a description of daytime driving and drinking patterns. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Causes of spatial and temporal patterns in rocky intertidal communities of central and northern California /

Mode of access: Internet.

The influence of environment physiology and heredity on the morphology and color patterns of migratory locusts.

This is an Ecology term paper.