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Full-Text Articles in Biology
Structure And Function Analysis Of Lin-14, A Temporal Regulator Of Postembryonic Developmental Events In Caenorhabditis Elegans, Yang Hong, Rosalind C. Lee, Victor Ambros
Structure And Function Analysis Of Lin-14, A Temporal Regulator Of Postembryonic Developmental Events In Caenorhabditis Elegans, Yang Hong, Rosalind C. Lee, Victor Ambros
Dartmouth Scholarship
During postembryonic development of Caenorhabditis elegans, the heterochronic gene lin-14 controls the timing of developmental events in diverse cell types. Three alternativelin-14 transcripts are predicted to encode isoforms of a novel nuclear protein that differ in their amino-terminal domains. In this paper, we report that the alternative amino-terminal domains of LIN-14 are dispensable and that a carboxy-terminal region within exons 9 to 13 is necessary and sufficient for in vivo LIN-14 function. A transgene capable of expressing only one of the three alternativelin-14 gene products rescues a lin-14 null mutation and is developmentally regulated by lin-4. …
The Kinesin-Related Protein, Hset, Opposes The Activity Of Eg5 And Cross-Links Microtubules In The Mammalian Mitotic Spindle, Vicki Mountain, Calvin Simerly, Louisa Howard, Asako Ando, Gerald Schatten, Duane A. Compton
The Kinesin-Related Protein, Hset, Opposes The Activity Of Eg5 And Cross-Links Microtubules In The Mammalian Mitotic Spindle, Vicki Mountain, Calvin Simerly, Louisa Howard, Asako Ando, Gerald Schatten, Duane A. Compton
Dartmouth Scholarship
We have prepared antibodies specific for HSET, the human homologue of the KAR3 family of minus end-directed motors. Immuno-EM with these antibodies indicates that HSET frequently localizes between microtubules within the mammalian metaphase spindle consistent with a microtubule cross-linking function. Microinjection experiments show that HSET activity is essential for meiotic spindle organization in murine oocytes and taxol-induced aster assembly in cultured cells. However, inhibition of HSET did not affect mitotic spindle architecture or function in cultured cells, indicating that centrosomes mask the role of HSET during mitosis. We also show that (acentrosomal) microtubule asters fail to assemble in vitro without …
Measurement Of Oxygen Partial Pressure, Its Control During Hypoxia And Hyperoxia, And Its Effect Upon Light Emission In A Bioluminescent Elaterid Larva, G. S. Timmins, C. A. A. Penatti, E. J. H. Bechara, H. M. Swartz
Measurement Of Oxygen Partial Pressure, Its Control During Hypoxia And Hyperoxia, And Its Effect Upon Light Emission In A Bioluminescent Elaterid Larva, G. S. Timmins, C. A. A. Penatti, E. J. H. Bechara, H. M. Swartz
Dartmouth Scholarship
This study investigates the respiratory physiology of bioluminescent larvae of Pyrearinus termitilluminans in relation to their tolerance to hypoxia and hyperoxia and to the supply of oxygen for bioluminescence. The partial pressure of oxygen (P(O2)) was measured within the bioluminescent prothorax by in vivo electron paramagnetic resonance (EPR) oximetry following acclimation of larvae to hypoxic, normoxic and hyperoxic (normobaric) atmospheres and during periods of bioluminescence (during normoxia). The P(O2) in the prothorax during exposure to an external P(O2) of 15.2, 160 and 760 mmHg was 10.3+/-2.6, 134+/-0.9 and 725+/-73 mmHg respectively (mean +/- s.d., N=5; 1 mmHg=0.1333 kPa). Oxygen supply …
Host-Driven Population Dynamics In An Herbivorous Insect, Tiina Ylioja, Heikki Roininen, Matthew P. Ayres, Matti Rousi, Peter W. Price
Host-Driven Population Dynamics In An Herbivorous Insect, Tiina Ylioja, Heikki Roininen, Matthew P. Ayres, Matti Rousi, Peter W. Price
Dartmouth Scholarship
Understanding the nature and relative importance of endogenous (density-dependent) and exogenous (density-independent) effects on population dynamics remains a central problem in ecology. Evaluation of these forces has been constrained by the lack of long time series of population densities and largely limited to populations chosen for their unique dynamics (e.g., outbreak insects). Especially in herbivore populations, the relative contributions of bottom-up and top-down effects (resources and natural enemies, respectively) have been difficult to compare because population data have rarely been combined with resource measurements. The feeding scars of a wood-mining herbivorous insect (Phytobia betulae Kangas; Diptera: Agromyzidae) of birch …
Succinate Dehydrogenase (Sdh) From Bradyrhizobium Japonicum Is Closely Related To Mitochondrial Sdh, David J. Westenberg, Mary Lou Guerinot
Succinate Dehydrogenase (Sdh) From Bradyrhizobium Japonicum Is Closely Related To Mitochondrial Sdh, David J. Westenberg, Mary Lou Guerinot
Dartmouth Scholarship
The sdhCDAB operon, encoding succinate dehydrogenase, was cloned from the soybean symbiont Bradyrhizobium japonicum. Sdh from B. japonicum is phylogenetically related to Sdh from mitochondria. This is the first example of a mitochondrion-like Sdh functionally expressed in Escherichia coli.
A Role For The Light-Dependent Phosphorylation Of Visual Arrestin, Paul G. Alloway, Patrick J. Dolph
A Role For The Light-Dependent Phosphorylation Of Visual Arrestin, Paul G. Alloway, Patrick J. Dolph
Dartmouth Scholarship
Arrestins are regulatory proteins that participate in the termination of G protein-mediated signal transduction. The major arrestin in the Drosophila visual system, Arrestin 2 (Arr2), is phosphorylated in a light-dependent manner by a Ca2+/calmodulin-dependent protein kinase and has been shown to be essential for the termination of the visual signaling cascade in vivo. Here, we report the isolation of nine alleles of the Drosophila photoreceptor cell-specific arr2 gene. Flies carrying each of these alleles underwent light-dependent retinal degeneration and displayed electrophysiological defects typical of previously identified arrestin mutants, including an allele encoding a protein that lacks the major Ca2+/calmodulin-dependent protein …
Genetic Control Of Programmed Cell Death In The Caenorhabditis Elegans Hermaphrodite Germline, Tina Gumienny, Eric Lambie, Erika Hartwieg, H. Robert Horvitz, Michael Hengartner
Genetic Control Of Programmed Cell Death In The Caenorhabditis Elegans Hermaphrodite Germline, Tina Gumienny, Eric Lambie, Erika Hartwieg, H. Robert Horvitz, Michael Hengartner
Dartmouth Scholarship
Development of the nematode Caenorhabditis elegans is highly reproducible and the fate of every somatic cell has been reported. We describe here a previously uncharacterized cell fate in C. elegans: we show that germ cells, which in hermaphrodites can differentiate into sperm and oocytes, also undergo apoptotic cell death. In adult hermaphrodites, over 300 germ cells die, using the same apoptotic execution machinery (ced-3, ced-4 and ced-9) as the previously described 131 somatic cell deaths. However, this machinery is activated by a distinct pathway, as loss of egl-1 function, which inhibits somatic cell death, does not affect germ cell apoptosis. …