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Mining The Arabidopsis Thaliana Genome For Highly-Divergent Seven Transmembrane Receptors, Etsuko N. Moriyama, Pooja K. Strope, Stephen O. Opiyo, Zhongying Chen, Alan M. Jones

School of Biological Sciences: Faculty Publications

To identify divergent seven-transmembrane receptor (7TMR) candidates from the Arabidopsis thaliana genome, multiple protein classification methods were combined, including both alignmentbased and alignment-free classifiers. This resolved problems in optimally training individual classifiers using limited and divergent samples, and increased stringency for candidate proteins. We identified 394 proteins as 7TMR candidates and highlighted 54 with corresponding expression patterns for further investigation.

Mig-5/Dsh Controls Cell Fate Determination And Cell Migration In C. Elegans, Timothy Walston, Chaobo Guo, Rui Proenca, Mingfu Wu, Michael Herman, Jeff Hardin, Edward Hedgecock

School of Biological Sciences: Faculty Publications

Cell fate determination and cell migration are two essential events in the development of an organism. We identify mig-5, a Dishevelled family member, as a gene that regulates several cell fate decisions and cell migrations that are important during C. elegans embryonic and larval development. In offspring from mig-5 mutants, cell migrations are defective during hypodermal morphogenesis, QL neuroblast migration, and the gonad arm migration led by the distal tip cells (DTCs). In addition to abnormal migration, DTC fate is affected, resulting in either an absent or an extra DTC. The cell fates of the anchor cell in hermaphrodites …

Why Is The Number Of Dna Bases 4?, Bo Deng

Department of Mathematics: Faculty Publications

In this paper we construct a mathematical model for DNA replication based on Shannon’s mathematical theory for communication. We treatDNAreplication as a communication channel. We show that the mean replication rate is maximal with four nucleotide bases under the primary assumption that the pairing time of the G–C bases is between 1.65 and 3 times the pairing time of the A–T bases.

Can Environmental Variation Generate Positive Indirect Effects In A Model Of Shared Predation?, Chad Brassil

School of Biological Sciences: Faculty Publications

Classic models of apparent competition predict negative indirect effects between prey with a shared enemy. If predator per capita growth rates are nonlinear, then endogenously generated periodic cycles are predicted to generate less negative or even positive indirect effects between prey. Here I determine how exogenous mechanisms such as environmental variation could modify indirect effects. I find that exogenous variation can have a broader range of effects on indirect interactions than endogenously generated cycles. Indirect effects are altered by environmental variation even in simple models for which the per capita growth rate of the predator species is a linear function …

Regulation Of Mercury Resistance In The Crenarchaeote Sulfolobus Solfataricus, James Schelert, Melissa Drozda, Vidula Dixit, Amanda Dillman, Paul H. Blum

School of Biological Sciences: Faculty Publications

Mercuric ion, Hg(II), inactivates generalized transcription in the crenarchaeote Sulfolobus solfataricus. Metal

challenge simultaneously derepresses transcription of mercuric reductase (merA) by interacting with the

archaeal transcription factor aMerR. Northern blot and primer extension analyses identified two additional

Hg(II)-inducible S. solfataricus genes, merH and merI (SSO2690), located on either side of merA. Transcription

initiating upstream of merH at promoter merHp was metal inducible and extended through merA and merI,

producing a merHAI transcript. Northern analysis of a merRA double mutant produced by linear DNA

recombination demonstrated merHp promoter activity was dependent on aMerR to overcome Hg(II) …

Nonparametric Estimation Of Natural Selection On A Quantitative Trait Using Mark-Recapture Data, Olivier Gimenez, Rita Covas, Charles R. Brown, Mark D. Anderson, Mary Bomberger Brown, Thomas Lenormand

School of Biological Sciences: Faculty Publications

Assessing natural selection on a phenotypic trait in wild populations is of primary importance for evolutionary ecologists. To cope with the imperfect detection of individuals inherent to monitoring in the wild, we develop a nonparametric method for evaluating the form of natural selection on a quantitative trait using mark-recapture data. Our approach uses penalized splines to achieve flexibility in exploring the form of natural selection by avoiding the need to specify an a priori parametric function. If needed, it can help in suggesting a new parametric model. We employ Markov chain Monte Carlo sampling in a Bayesian framework to estimate …

Glucocorticoid Hormone Levels Increase With Group Size And Parasite Load In Cliff Swallows, Samrrah A. Raouf, Linda C. Smith, Mary Bomberger Brown, John C. Wingfield, Charles R. Brown

School of Biological Sciences: Faculty Publications

Animals often cope with adverse events by releasing glucocorticoid hormones, which in turn promote increased energy assimilation. In captive animals, crowding also leads to increased glucocorticoid activity, probably because of increased levels of social competition. We investigated how group size and ectoparasite infestations affected endogenous levels of the glucocorticoid hormone, corticosterone, in colonial cliff swallows, Petrochelidon pyrrhonota, in southwestern Nebraska, USA. Parasites were removed from some colonies by fumigating nests. Baseline levels of corticosterone in breeding adults varied significantly with whether parasites were present, colony size (measured by total number of active nests at a site), and nesting stage. …

Feather Mites Are Positively Associated With Daily Survival In Cliff Swallows, Charles R. Brown, Kathleen R. Brazeal, Stephanie A. Strickler, Mary Bomberger Brown

School of Biological Sciences: Faculty Publications

Feather mites (Acari: Astigmata) have been reported to be parasitic, commensal, and even mutualis-tic on the birds that serve as their hosts. We investigated whether there was a relationship between number of feather mites (Pteronyssoides obscurus (Berlese, 1885)) on the wing and daily survival of cliff swallows (Petrochelidon pyrrhonota (Vieillot, 1817)) during the breeding season at 12 nesting colonies in Nebraska in 2005. Survival of birds with known mite loads was monitored by mark–recapture, and survival models with and without a linear effect of mites were compared with the program MARK. For adult swallows, mites were positively associated …

Fire Does Not Alter Vegetation In Infertile Prairie, Johannes M.H. Knops

School of Biological Sciences: Faculty Publications

The paradigm in prairie ecology is that fire is one of the key factors deter-mining vegetation composition. fire can impact grassland ecosystems in various ways, including changing plant species composition and inducing nitro-gen loss. I found that 17 years of different burning frequencies in infertile grassland had only a minor impact on the vegetation composition and diversity. The only major impact from increasing the frequency of fires was a decrease of Poa pratensis abundance. However, other plant species did not r-spond to the change in Poa abundance. This result contrasts with previous studies in savannas and more productive grasslands, where …