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Biology Faculty Publications

1998

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Articles 1 - 12 of 12

Full-Text Articles in Life Sciences

Drosophila Unpaired Encodes A Secreted Protein That Activates The Jak Signaling Pathway, Douglas A. Harrison, Patricia E. Mccoon, Richard Binari, Michael Gilman, Norbert Perrimon Oct 1998

Drosophila Unpaired Encodes A Secreted Protein That Activates The Jak Signaling Pathway, Douglas A. Harrison, Patricia E. Mccoon, Richard Binari, Michael Gilman, Norbert Perrimon

Biology Faculty Publications

In vertebrates, many cytokines and growth factors have been identified as activators of the JAK/STAT signaling pathway. In Drosophila, JAK and STAT molecules have been isolated, but no ligands or receptors capable of activating the pathway have been described. We have characterized the unpaired (upd) gene, which displays the same distinctive embryonic mutant defects as mutations in the Drosophila JAK (hopscotch) and STAT (stat92E) genes. Upd is a secreted protein, associated with the extracellular matrix, that activates the JAK pathway. We propose that Upd is a ligand that relies on JAK signaling to stimulate transcription of pair-rule genes in a …

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Reproductive Success Of Ospreys At Two Sites In Connecticut, Donna Christine O'Neill, Robert A. Askins Jul 1998

Reproductive Success Of Ospreys At Two Sites In Connecticut, Donna Christine O'Neill, Robert A. Askins

Biology Faculty Publications

Nest success rates and rates of fish delivery to nests were determined for two large Osprey populations in COlmecticut, one at Groton Reservoir, Groton, and one at Great Island, Old Lyme, during 1996 and 1997. Between 1993 and 1996 these Osprey populations had substantially different rates of nest success. Great Island Ospreys fledged few young while Groton Reservoir Ospreys had good nest success. During 1997, however, fledging rates were similar at the two sites. In 1996, low nest success at Great Island 'resuited from high predation rates, probably due to raccoons. The higher nest success rate at this site in …

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A Role For Nima In The Nuclear Localization Of Cyclin B In Aspergillus Nidulans, L. Wu, S. A. Osmani, Peter M. Mirabito Jun 1998

A Role For Nima In The Nuclear Localization Of Cyclin B In Aspergillus Nidulans, L. Wu, S. A. Osmani, Peter M. Mirabito

Biology Faculty Publications

NIMA promotes entry into mitosis in late G2 by some mechanism that is after activation of the Aspergillus nidulans G2 cyclin-dependent kinase, NIMXCDC2/NIMECyclin B. Here we present two independent lines of evidence which indicate that this mechanism involves control of NIMXCDC2/NIMECyclin B localization. First, we found that NIMECyclin B localized to the nucleus and the nucleus-associated organelle, the spindle pole body, in a NIMA-dependent manner. Analysis of cells from asynchronous cultures, synchronous cultures, and cultures arrested in S or G2 showed that NIMECyclin B was predominantly nuclear during interphase, with maximal …

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The Biology Of Xenopus By R. C. Tinsley And H. C. Kobel, Rafael O. De Sá May 1998

The Biology Of Xenopus By R. C. Tinsley And H. C. Kobel, Rafael O. De Sá

Biology Faculty Publications

The Biology of Xenopus presents a summary of current knowledge about a single genus resulting from a symposium held at the Zoological Society of London in September 1992. This approach to summarizing available information has also been taken for other taxa, such as Atelopus (Lotters, 1996). However, the task of compiling data for Xenopus is enormous relative to any other amphibian group, because Xenopus laevis has become a model system for molecular and development research (Cannatella and de Sa, 1993). Unfortunately, most of our knowledge of Xenopus is biased toward this single species. There are about 20 recognized species of …

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The Polarized Sorting Of Membrane Proteins Expressed In Cultured Hippocampal Neurons Using Viral Vectors, Mark Jareb, Gary Banker May 1998

The Polarized Sorting Of Membrane Proteins Expressed In Cultured Hippocampal Neurons Using Viral Vectors, Mark Jareb, Gary Banker

Biology Faculty Publications

One model of neuronal polarity (Dotti and Simons, 1990) proposes that neurons and polarized epithelia use similar mechanisms to sort membrane proteins. To explore this hypothesis, we used viral vectors to express proteins in cultured neurons and assessed their distribution using quantitative immunofluorescence microscopy. Basolateral epithelial proteins were polarized to dendrites; more significantly, mutations of sequences required for their basolateral targeting in epithelia also disrupted dendritic targeting. Unexpectedly, apical proteins were not polarized to axons but were expressed at roughly equal amounts in dendrites and axons. These data provide strong evidence that targeting of basolateral and dendritic proteins depends on …

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Confocal Microscopy: A Powerful Tool For Biological Research, Amit Singh, K. P. Gopinathan May 1998

Confocal Microscopy: A Powerful Tool For Biological Research, Amit Singh, K. P. Gopinathan

Biology Faculty Publications

Conventional light microscopy allows the observation of living as well as fixed cells and tissues to generate two-dimensional images. The out-of-focus information often obscures the ultrastructural details, especially in thick specimens with overlapping structures. The earliest available light microscopy visualized the objects in hydrated state in two-dimensions during their temporal development. The emergence of electron microscopy (EM) provided superb resolution of ultrastructural details, but it was applicable only for objects in the dehydrated state and thereby potentially introducing handling artifacts. The usefulness of optical methods, however, has been limited by the poor depth discrimination. Often, the fluorescence and reflectance images …

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Chondrocranial Morphology Of Leptodactylus Larvae (Leptodactylidae: Leptodactylinae): Its Utility In Phylogenetic Reconstruction, Peter M. Larson, Rafael O. De Sá Jan 1998

Chondrocranial Morphology Of Leptodactylus Larvae (Leptodactylidae: Leptodactylinae): Its Utility In Phylogenetic Reconstruction, Peter M. Larson, Rafael O. De Sá

Biology Faculty Publications

Chondrocranial morphology of leptodactylid frogs is scarcely known and has not been completely described for any species of Leptodactylus. We describe the diversity of chondrocranial morphology in the genus Leptodactylus based on the analysis of 22 species, representing the four species groups: the fuscus Group, ocellatus Group, melanonotus Group, and pentadactylus Group. Furthermore, 26 characters are identified and used in a phylogenetic analysis. The phylogenetic analysis using Physalaemus, Crossodactylus, and Hylodes as outgroups suggests two monophyletic clades within Leptodactylus: the melanonotus-ocellatus clade and the pentadactylusfuscus clade. However, it does not support the monophyly of the species groups as currently recognized …

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Seedling Development In Species Of Chamaesyce (Euphorbiaceae) With Erect Growth Habits, W. John Hayden, Olga Troyanskaya Jan 1998

Seedling Development In Species Of Chamaesyce (Euphorbiaceae) With Erect Growth Habits, W. John Hayden, Olga Troyanskaya

Biology Faculty Publications

Seedling development is described for Chamaesyce hirta, C. hypericifolia, and C. mesembrianthemifolia as discerned by light microscopy and scanning electron microscopy. Although these species ultimately develop erect to ascending growth habits, epicotyl development is limited to the production of a single pair ofleaves located immediately superjacent to and decussate with the cotyledons. The shoot system develops from one or more buds located in the axils of the cotyledons. In all respects, seedling ontogeny is very similar to that of previously studied prostrate species of Chamaesyce. Evidence from seedling ontogeny thus contradicts a hypothesis concerning homologies of plant …

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Chondrocranial Anatomy And Skeletogenesis In Dendrobates Auratus, Rafael O. De Sá, Shannon Hill Jan 1998

Chondrocranial Anatomy And Skeletogenesis In Dendrobates Auratus, Rafael O. De Sá, Shannon Hill

Biology Faculty Publications

The larval chondrocranium and visceral skeleton of Dendrobates auratus ls described and compared with those of other dendrobatids. Four characters, i.e. lack of fusion between orbital cartilages and otic capsules, wide processus muscularis palatoquadrati, lack of processus pseudopterygoideus, and lack of processus anterolateralis hyalis, represent derived conditions for Dendrobates within Dendrobatidae. Cranial and postcranial ossification sequences are reported for D. auratus and Epipedobates tricolor. Skeletogenesis is earlier in E. tricolor, but the overall pattern of ossification is similar in the two species.

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Host Plant Alters The Shape Of The Functional Response Of An Aphid Predator (Coleoptera: Coccinellidae), Frank J. Messina, J. B. Hanks Jan 1998

Host Plant Alters The Shape Of The Functional Response Of An Aphid Predator (Coleoptera: Coccinellidae), Frank J. Messina, J. B. Hanks

Biology Faculty Publications

The response of the lady beetle Propylea quatuordecimpunctata (L.) to the density of the Russian wheat aphid, Diuraphis noxia (Mordvilko), was measured in petri dish arenas as well as on plants with divergent leaf architectures. Logistic regression was used to distinguish the shape of the functional response (type II or III), and nonlinear least-squares regression was used to estimate attack coefficients (a) and handling times (Th). In dishes, the behavior of both beetle larvae and adults closely conformed to a type II response. Estimates of a and Th on whole plants were considerably different from those obtained from dishes, and …

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Assembly Of The Herpes Simplex Virus Capsid: Preformed Triplexes Bind To The Nascent Capsid, Juliet V. Spencer, William W. Newcomb, Darrell R. Thomsen, Fred L. Homa, Jay C. Brown Jan 1998

Assembly Of The Herpes Simplex Virus Capsid: Preformed Triplexes Bind To The Nascent Capsid, Juliet V. Spencer, William W. Newcomb, Darrell R. Thomsen, Fred L. Homa, Jay C. Brown

Biology Faculty Publications

The herpes simplex virus type 1 (HSV-1) capsid is a T=16 icosahedral shell that forms in the nuclei of infected cells. Capsid assembly also occurs in vitro in reaction mixtures created from insect cell extracts containing recombinant baculovirus-expressed HSV-1 capsid proteins. During capsid formation, the major capsid protein, VP5, and the scaffolding protein, pre-VP22a, condense to form structures that are extended into procapsids by addition of the triplex proteins, VP19C and VP23. We investigated whether triplex proteins bind to the major capsid-scaffold protein complexes as separate polypeptides or as preformed triplexes. Assembly products from reactions lacking one triplex protein were …

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Multiple Members Of A Third Subfamily Of P-Type Atpases Identified By Genomic Sequences And Ests, Margaret S. Halleck, Deepti Pradhan, Christie Blackman, Charlotte A. Berkes, Partrick Williamson, Robert A. Schlegel Jan 1998

Multiple Members Of A Third Subfamily Of P-Type Atpases Identified By Genomic Sequences And Ests, Margaret S. Halleck, Deepti Pradhan, Christie Blackman, Charlotte A. Berkes, Partrick Williamson, Robert A. Schlegel

Biology Faculty Publications

The Saccharomyces cerevisiae genome contains five P-type ATPases divergent from both of the well-known subfamilies of these membrane ion transporters. This newly recognized third subfamily can be further divided into four classes of genes with nearly equal relatedness to each other. Genes of this new subfamily are also present and expressed in multicellular organisms such as Caenorhabditis elegans and mammals; some, but not all, can be assigned to the classes identified in yeast. Different classes of genes and different genes within a class are expressed differentially in tissues of the mouse. The recently cloned gene for the mammalian aminophospholipid translocase …

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