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Effects Of Microzooplankton Growth And Trophic Interactions On Herbivory In Coastal And Offshore Environments, Matthew R. First, Harlan L. Miller Iii, Peter J. Lavrentyev, James L. Pinckney, Adrian B. Burd Mar 2009

Effects Of Microzooplankton Growth And Trophic Interactions On Herbivory In Coastal And Offshore Environments, Matthew R. First, Harlan L. Miller Iii, Peter J. Lavrentyev, James L. Pinckney, Adrian B. Burd

Biology Faculty Research

We performed serial dilution experiments to estimate rates of gross phytoplankton growth (L) and grazing mortality (m) in both eutrophic (Corpus Christi Bay, Texas, USA) and oligotrophic (offshore Gulf of Mexico) waters. Two parallel experiments were performed in both environments, with seawater pre-screened through 153 or 25 Inn mesh to observe the responses of microzooplankton (MZP) to dilution treatments. MZP biomass changed over the duration of the experimental incubations; in several treatments, MZP net growth rates were >1 d(-1). Patterns of growth varied between dilutions and initial screening size. In the eutrophic system, the ratio of phytoplankton grazing mortality rate …


Avian Incubation Inhibits Growth And Diversification Of Bacterial Assemblages On Eggs, Matthew D. Shawkey, Mary K. Firestone, Eoin L. Brodie, Steven R. Beissinger Feb 2009

Avian Incubation Inhibits Growth And Diversification Of Bacterial Assemblages On Eggs, Matthew D. Shawkey, Mary K. Firestone, Eoin L. Brodie, Steven R. Beissinger

Biology Faculty Research

Microbial infection is a critical source of mortality for early life stages of oviparous vertebrates, but parental defenses against infection are less well known. Avian incubation has been hypothesized to reduce the risk of trans-shell infection by limiting microbial growth of pathogenic bacteria on eggshells, while enhancing growth of commensal or beneficial bacteria that inhibit or competitively exclude pathogens. We tested this hypothesis by comparing bacterial assemblages on naturally incubated and experimentally unincubated eggs at laying and late incubation using a universal 16S rRNA microarray containing probes for over 8000 bacterial taxa. Before treatment, bacterial assemblages on individual eggs from …


Which Sry Locus Is The Hypertensive Y Chromosome Locus?, Monte E. Turner, Joel Farkas, Jeff Dunmire, Daniel Ely, Amy Milsted Feb 2009

Which Sry Locus Is The Hypertensive Y Chromosome Locus?, Monte E. Turner, Joel Farkas, Jeff Dunmire, Daniel Ely, Amy Milsted

Biology Faculty Research

The Y chromosome of the spontaneously hypertensive rat (SHR) contains a genetic component that raises blood pressure compared with the Wistar-Kyoto (WKY) Y chromosome. This research tests the Sry gene complex as the hypertensive component of the SHR Y chromosome. The Sry loci were sequenced in 1 strain with a hypertensive Y chromosome (SHR/Akr) and 2 strains with a normotensive Y chromosome (SHR/Crl and WKY/Akr). Both SHR strains have 7 Sry loci, whereas the WKY strain has 6. The 6 loci in common between SHR and WKY strains were identical in the sequence compared (coding region, 392-bp 5' prime flanking, …


Can Males Successfully Invade Hermaphroditic Populations Of Clam Shrimp (Eulimnadia Texana)?, Stephen C. Weeks Jan 2009

Can Males Successfully Invade Hermaphroditic Populations Of Clam Shrimp (Eulimnadia Texana)?, Stephen C. Weeks

Biology Faculty Research

Androdioecy (mixtures of males and hermaphrodites) is distinguished by its rarity, being found in only similar to 40 animal species. Many of these species are clam shrimp in the genus Eulimnadia. A metapopulation model for the maintenance of androdioecy is tested herein by examining male success in aquaria with a single male-producing hermaphrodite introduced into an otherwise all-hermaphrodite population. This migration experiment did allow males to persist in these populations for seven generations, although at levels below those found in other populations of these shrimp. These results suggest that the maintenance of androdioecy via 'reproductive assurance' is unlikely by way …


Inbreeding Effects On Sperm Production In Clam Shrimp (Eulimnadia Texana), Stephen C. Weeks, Sadie K. Reed, Donald W. Ott, Franca Scanabissi Jan 2009

Inbreeding Effects On Sperm Production In Clam Shrimp (Eulimnadia Texana), Stephen C. Weeks, Sadie K. Reed, Donald W. Ott, Franca Scanabissi

Biology Faculty Research

Hypothesis: Inbreeding depression is manifest in lower sperm production. Organism: Freshwater crustaceans (clam shrimp - Eulimnadia texana), from the southwestern United States, which have high levels of inbreeding. Methods: Comparisons of semi-thin sections of the male gonad among selfed and outcrossed siblings from four families. Results: There was a twofold reduction in sperm production in inbred relative to outcrossed males. Inbreeding depression in males was higher than previous estimates from hermaphrodites. Conclusions: Inbreeding markedly reduces sperm production. The observed low levels of sperm production can explain both the low average outcrossing rates as well as the variation in these rates …


Estrogen Receptors In The Medial Amygdala Inhibit The Expression Of Male Prosocial Behavior, Bruce S. Cushing, Adam Perry, Sergei Musatov, Sonoko Ogawa Oct 2008

Estrogen Receptors In The Medial Amygdala Inhibit The Expression Of Male Prosocial Behavior, Bruce S. Cushing, Adam Perry, Sergei Musatov, Sonoko Ogawa

Biology Faculty Research

Studies using estrogen receptor alpha(ER) knock-out mice indicate that ER alpha masculinizes male behavior. Recent studies of ER alpha and male prosocial behavior have shown an inverse relationship between ER alpha expression in regions of the brain that regulate social behavior, including the medial amygdala (MeA), and the expression of male prosocial behavior. These studies have lead to the hypothesis that low levels of ER alpha are necessary to "permit" the expression of high levels of male prosocial behavior. To test this, viral vectors were used to enhance ER alpha in male prairie voles (Microtus ochrogaster), which display high levels …


Grazing And Virus-Induced Mortality Of Microbial Populations Before And During The Onset Of Annual Hypoxia In Lake Erie, Christopher J. Gobler, Timothy W. Davis, Sarah N. Deonarine, Matthew A. Saxton, Peter J. Lavrentyev, Frank J. Jochem May 2008

Grazing And Virus-Induced Mortality Of Microbial Populations Before And During The Onset Of Annual Hypoxia In Lake Erie, Christopher J. Gobler, Timothy W. Davis, Sarah N. Deonarine, Matthew A. Saxton, Peter J. Lavrentyev, Frank J. Jochem

Biology Faculty Research

Lake Erie is the most productive of the North American Great Lakes and experiences annual periods of hypolimnetic hypoxia with unknown consequences for the microbial food web. We established the abundances and mortality rates of microbes in Lake Erie during thermal stratification and determined how they varied with changes in bottom-water dissolved oxygen concentrations. The microbial plankton community (heterotrophic bacteria, Cyanobacteria, eukaryotic phytoplankton, nanozooplankton, microzooplankton) was quantified in surface and bottom waters along with measurements of herbivory and bacterivory rates on eukaryotic and prokaryotic picoplankton and rates of viral lysis of bacteria. High rates of grazing mortality of prokaryotic picoplankton …


Sticky Gecko Feet: The Role Of Temperature And Humidity, Peter H. Niewiarowski, Stephanie Lopez, Liehui Ge, Emily Hagan, Ali Dhinojwala May 2008

Sticky Gecko Feet: The Role Of Temperature And Humidity, Peter H. Niewiarowski, Stephanie Lopez, Liehui Ge, Emily Hagan, Ali Dhinojwala

Biology Faculty Research

Gecko adhesion is expected to be temperature insensitive over the range of temperatures typically experienced by geckos. Previous work is limited and equivocal on whether this expectation holds. We tested the temperature dependence of adhesion in Tokay and Day geckos and found that clinging ability at 12 degrees C was nearly double the clinging ability at 32 degrees C. However, rather than confirming a simple temperature effect, our data reveal a complex interaction between temperature and humidity that can drive differences in adhesion by as much as two-fold. Our findings have important implications for inferences about the mechanisms underlying the …


Effects Of Population Size And Density On Pollinator Visitation, Pollinator Behavior, And Pollen Tube Abundance In Lupinus Perennis, Christopher E. Bernhardt, Randall J. Mitchell, Helen J. Michaels Jan 2008

Effects Of Population Size And Density On Pollinator Visitation, Pollinator Behavior, And Pollen Tube Abundance In Lupinus Perennis, Christopher E. Bernhardt, Randall J. Mitchell, Helen J. Michaels

Biology Faculty Research

Both the number and the density of flowering plants in a population can be important determinants of pollinator abundance and behavior. We report the joint effects of population size and density on pollinator visitation and pollination success for Lupinus perennis (Fabaceae). Focusing on five pairs of populations, we matched one small population (125-800 flowering plants) with one distinctly larger population (1000-3000 flowering plants). In these pairs, population size did not affect pollinator communities or pollination success. All measures of pollination success increased significantly with density. Only bee behavior (number of flowers probed per inflorescence) exhibited a significant interaction of size …


Nodal Signaling Is Required For Closure Of The Anterior Neural Tube In Zebrafish, Allisan Aquilina-Beck, Kristine Ilagan, Qin Liu, Jennifer O. Liang Nov 2007

Nodal Signaling Is Required For Closure Of The Anterior Neural Tube In Zebrafish, Allisan Aquilina-Beck, Kristine Ilagan, Qin Liu, Jennifer O. Liang

Biology Faculty Research

Background: Nodals are secreted signaling proteins with many roles in vertebrate development. Here, we identify a new role for Nodal signaling in regulating closure of the rostral neural tube of zebrafish.


The Organizational Effects Of Oxytocin On The Central Expression Of Estrogen Receptor Alpha And Oxytocin In Adulthood, Kristin M. Kramer, Shigeto Yoshida, Eros Papademetriou, Bruce S. Cushing Sep 2007

The Organizational Effects Of Oxytocin On The Central Expression Of Estrogen Receptor Alpha And Oxytocin In Adulthood, Kristin M. Kramer, Shigeto Yoshida, Eros Papademetriou, Bruce S. Cushing

Biology Faculty Research

Background: Previous studies have demonstrated that neonatal manipulation of oxytocin (OT) has effects on the expression of estrogen receptor alpha (ER alpha) and the central production of oxytocin observed in juveniles ( at weaning, 21 days of age). The goal of this study was to determine whether the effects of neonatal manipulation of OT last into adulthood, and if the effects differ from those observed during the early postnatal period. On the first day of life, prairie voles ( Microtus ochrogaster) received one of three doses of OT (High, 3 mu g; Med, 0.3 mu g; Low, 0.03 mu g), …


Genomic And Expression Analysis Of Multiple Sry Loci From A Single Rattus Norvegicus Y Chromosome, Monte E. Turner, Carey Martin, Almir S. Martins, Jeffrey Dunmire, Joel Farkas, Daniel L. Ely, Amy Milsted Apr 2007

Genomic And Expression Analysis Of Multiple Sry Loci From A Single Rattus Norvegicus Y Chromosome, Monte E. Turner, Carey Martin, Almir S. Martins, Jeffrey Dunmire, Joel Farkas, Daniel L. Ely, Amy Milsted

Biology Faculty Research

Background: Sry is a gene known to be essential for testis determination but is also transcribed in adult male tissues. The laboratory rat, Rattus norvegicus, has multiple Y chromosome copies of Sry while most mammals have only a single copy. DNA sequence comparisons with other rodents with multiple Sry copies are inconsistent in divergence patterns and functionality of the multiple copies. To address hypotheses of divergence, gene conversion and functional constraints, we sequenced Sry loci from a single R. norvegicus Y chromosome from the Spontaneously Hypertensive Rat strain (SHR) and analyzed DNA sequences for homology among copies. Next, to determine …


Anatomy Of The Recurrent Coastal Sediment Plume In Lake Michigan And Its Impacts On Light Climate, Nutrients, And Plankton, Henry Vanderploeg, Thomas Johengen, Peter J. Lavrentyev, Changsheng Chen, G. A. Lang, M. A. Agy, M. H. Bundy, J. F. Cavaletto, B. J. Eadie, J. R. Liebig, G. S. Miller, S. A. Ruberg, M. J. Mccormick Mar 2007

Anatomy Of The Recurrent Coastal Sediment Plume In Lake Michigan And Its Impacts On Light Climate, Nutrients, And Plankton, Henry Vanderploeg, Thomas Johengen, Peter J. Lavrentyev, Changsheng Chen, G. A. Lang, M. A. Agy, M. H. Bundy, J. F. Cavaletto, B. J. Eadie, J. R. Liebig, G. S. Miller, S. A. Ruberg, M. J. Mccormick

Biology Faculty Research

As part of the Episodic Events Great Lakes Experiment, we sampled total suspended matter (TSM), light climate, nutrients, and plankton along cross-margin transects in southern Lake Michigan during February, March, and April 1998-2000 to capture conditions before, during, and after the occurrence of storm-driven recurrent coastal sediment plumes to define the anatomy of the resuspension events and get insights into their interactions with nutrients and plankton. Variability in timing and strength of winter storms among years led to different timing, intensity, and extent of plumes among years. TSM concentrations in the core of plumes varied between 15 and 30 mg …


Cadherin2 (N-Cadherin) Plays An Essential Role In Zebrafish Cardiovascular Development, Brian Bagatto, Jessie Francl, Bei Liu, Qin Liu May 2006

Cadherin2 (N-Cadherin) Plays An Essential Role In Zebrafish Cardiovascular Development, Brian Bagatto, Jessie Francl, Bei Liu, Qin Liu

Biology Faculty Research

Background: Cadherins are cell surface adhesion molecules that play important roles in development of vertebrate tissues and organs. We studied cadherin2 expression in developing zebrafish heart using in situ hybridization and immunocytochemical methods, and we found that cadherin2 was strongly expressed by the myocardium of the embryonic zebrafish. To gain insight into cadherin2 role in the formation and function of the heart, we analyzed cardiac differentiation and performance in a cadherin2 mutant, glass onion (glo).


A Three-Dimensional Functional Assessment Of Heart And Vessel Development In The Larva Of The Zebrafish (Danio Rerio), Brian Bagatto, Warren Burggren Feb 2006

A Three-Dimensional Functional Assessment Of Heart And Vessel Development In The Larva Of The Zebrafish (Danio Rerio), Brian Bagatto, Warren Burggren

Biology Faculty Research

There has been considerable recent interest in the development of the circulation in the zebrafish. Optical techniques typically used to visualize changes in heart size allow measurement of stroke volume during early vertebrate development, but this approach is complicated in zebrafish larvae because of the heart's irregular shape and its significant change in morphology during the first 6 d of development. By use of a three-dimensional integration of the early zebrafish heart and vessels, we have greatly reduced measurement error of stroke volume and cardiac output and have determined the cross-sectional growth of major vessels in the developing zebrafish larvae. …


Interspecific Competition For Pollination Lowers Seed Production And Outcrossing In Mimulus Ringens, John M. Bell, Jeffrey D. Karron, Randall J. Mitchell Jan 2005

Interspecific Competition For Pollination Lowers Seed Production And Outcrossing In Mimulus Ringens, John M. Bell, Jeffrey D. Karron, Randall J. Mitchell

Biology Faculty Research

Sympatric plant species with similar flowering phenologies and floral morphologies may compete for pollination, and as a consequence potentially influence each other's reproductive success and mating system. Two likely competitors are Mimulus ringens and Lobelia siphilitica, which co-occur in wet meadows of central and eastern North America, produce blue zygomorphic flowers, and share several species of bumble bee pollinators. To test for effects of competition for pollination, we planted experimental arrays of Mimulus ringens, each consisting of genets with unique combinations of homozygous marker genotypes. In two arrays we planted mixtures of Mimulus and Lobelia. and in two additional arrays …


Bergmann's Clines In Ectotherms: Illustrating A Life-History Perspective With Sceloporine Lizards, Michael J. Angilletta Jr., Peter H. Niewiarowski, Arthur E. Dunham, Adam D. Leache, Warren P. Porter Dec 2004

Bergmann's Clines In Ectotherms: Illustrating A Life-History Perspective With Sceloporine Lizards, Michael J. Angilletta Jr., Peter H. Niewiarowski, Arthur E. Dunham, Adam D. Leache, Warren P. Porter

Biology Faculty Research

The generality and causes of Bergmann's rule have been debated vigorously in the last few years, but Bergmann's clines are rarely explained in the context of life-history theory. We used both traditional and phylogenetic comparative analyses to explore the causes of latitudinal and thermal clines in the body size of the eastern fence lizard (Sceloporus undulatus). The proximate mechanism for larger body sizes in colder environments is delayed maturation, which results in a greater fecundity but a lower survival to maturity. Life-history theory predicts that a higher survivorship of juveniles in colder environments can favor the evolution of a Bergmann's …


A Modeling Study Of Benthic Detritus Flux's Impacts On Heterotrophic Processes In Lake Michigan, Changsheng Chen, Lixia Wang, Jianhua Qi, Hedong Liu, Judith Wells Budd, David J. Schwab, Dmitry Beletsky, Henry Vanderploeg, Brian Eadie, Thomas Johengen, James Cotner, Peter J. Lavrentyev Jul 2004

A Modeling Study Of Benthic Detritus Flux's Impacts On Heterotrophic Processes In Lake Michigan, Changsheng Chen, Lixia Wang, Jianhua Qi, Hedong Liu, Judith Wells Budd, David J. Schwab, Dmitry Beletsky, Henry Vanderploeg, Brian Eadie, Thomas Johengen, James Cotner, Peter J. Lavrentyev

Biology Faculty Research

Effects of sediment resuspension-induced benthic detrital flux on the heterotrophic part of the microbial food web in Lake Michigan were examined using a three-dimensional (3-D) coupled biological and physical model. The model was driven by the realistic meteorological forcing observed in March 1999. Wind-induced surface wave dynamics were incorporated into the physical model to generate the bottom flux. The model-generated benthic detrital flux was assumed to be proportional to the difference between model-calculated and critical stresses at the bottom. The model results indicate that detrital flux at the bottom was a key factor causing a significant increase of phosphorus and …


Heritability Of Nectar Traits: Why Do We Know So Little?, Randall J. Mitchell Jun 2004

Heritability Of Nectar Traits: Why Do We Know So Little?, Randall J. Mitchell

Biology Faculty Research

Although floral and extrafloral nectar traits are important for plant reproduction and defense, we know little about their genetic basis. Only a handful of studies have quantified heritable variation for nectar traits, primarily in controlled environments that minimize environmental variation. Most such studies have reported strong genetic influences, with heritabilities often >0.35. However, because nectar traits are often very responsive to environmental variation, even substantial amounts of genetic variation may be swamped out in the,field. Environmental variation deserves to be studied in its own right, including exploration of genotype X environment interaction for nectar traits . Most genetic studies of …


Distribution And Dynamics Of Nitrogen And Microbial Plankton In Southern Lake Michigan During Spring Transition 1999-2000, Wayne S. Gardner, Peter J. Lavrentyev, Joann F. Cavaletto, Mark J. Mccarthy, B. J. Eadie, Thomas Johengen, James Cotner Mar 2004

Distribution And Dynamics Of Nitrogen And Microbial Plankton In Southern Lake Michigan During Spring Transition 1999-2000, Wayne S. Gardner, Peter J. Lavrentyev, Joann F. Cavaletto, Mark J. Mccarthy, B. J. Eadie, Thomas Johengen, James Cotner

Biology Faculty Research

[ 1] Ammonium and amino acid fluxes were examined as indicators of N and microbial food web dynamics in southern Lake Michigan during spring. Either (NH4+)-N-15 or a mixture of N-15-labelled amino acids (both at 4 muM N final concentration) was added to Lake Michigan water. Net fluxes were measured over 24 h under natural light and dark conditions using deck-top incubators and compared to microbial food web characteristics. Isotope dilution experiments showed similar light and dark NH4+ regeneration rates at lake ( 6 versus 5 nM N h(-1)) and river-influenced ( 20 versus 24 nM N h(-1)) sites. Ammonium …


Maintenance Of Androdioecy In The Freshwater Shrimp, Eulimnadia Texana: Field Estimates Of Inbreeding Depression And Relative Male Survival, Stephen C. Weeks, Richard L. Bernhardt Feb 2004

Maintenance Of Androdioecy In The Freshwater Shrimp, Eulimnadia Texana: Field Estimates Of Inbreeding Depression And Relative Male Survival, Stephen C. Weeks, Richard L. Bernhardt

Biology Faculty Research

Androdioecy is a rare form of reproduction, only found in a few plant and animal species, wherein males co-exist with hermaphrodites. This particular form of mixed mating (mixtures of outcrossing and self-fertilization) is predicted to be evolutionarily unstable, with most androdioecious populations thought to be in a transition from hermaphroditism to dioecy, or vice versa. One well-studied androdioecious species is the freshwater clam shrimp Eulimnadia texana. A model by Otto et al. (1993), exploring the stability of this androdioecious system, predicts that males can co-exist with hermaphrodites when males fertilize an average of over twice the number of offspring that …


Cold Acclimation Strategy Is Highly Variable Among The Sunfishes (Centrarchidae), Peter J. Lavrentyev, Deidra R. Tschantz, Elizabeth L. Crockett Dec 2002

Cold Acclimation Strategy Is Highly Variable Among The Sunfishes (Centrarchidae), Peter J. Lavrentyev, Deidra R. Tschantz, Elizabeth L. Crockett

Biology Faculty Research

We tested the hypothesis that the physiological strategy for acclimating to low body temperature is similar among closely related fish. Largemouth bass (Micropterus salmoides), green sunfish (Lepomis cyanellus), bluegill sunfish (Lepomis macrochirus), black crappie (Pomonix nigromaculatus), and white crappie (Pomonix annularis), all members of the family Centrarchidae, were acclimated to 5° and 25°C. Morphometric variables (total mass, total length, organ masses) and enzyme activities (hexokinase; lactate dehydrogenase; and cytochrome oxidase in heart, liver, and muscle) were measured in 5°C- and 25°C-acclimated fish at 5° and 25°C assay temperatures. Each species displayed a distinct physiological response to cold acclimation that differed …


Competition For Pollination Between An Invasive Species (Purple Loosestrife) And A Native Congener, Beverly J. Brown, Randall J. Mitchell, Shirley A. Graham Aug 2002

Competition For Pollination Between An Invasive Species (Purple Loosestrife) And A Native Congener, Beverly J. Brown, Randall J. Mitchell, Shirley A. Graham

Biology Faculty Research

Invasive species are frequently regarded as Superlative competitors that can vegetatively crowd Out natives, but little is known about whether invasives call compete for pollination services with native plants. We hypothesized that, when the showy invasive species Lythrum salicaria (purple loosestrife) was present, pollinator visitation and seed set would be reduced in a native congener, L. alatum (winged loosestrife). To test this hypothesis, we constructed mixed and monospecific plots of the two species. Over two years of study, we found that L. salicaria significantly reduced both pollinator visitation and seed set in L. alatum. Furthermore, pollinators moved frequently between the …


Cold Acclimation Strategy Is Highly Variable Among The Sunfishes (Centrarchidae), Deidra R. Tschantz, Elizabeth L. Crockett, Peter H. Niewiarowski, Richard L. Londraville Jan 2002

Cold Acclimation Strategy Is Highly Variable Among The Sunfishes (Centrarchidae), Deidra R. Tschantz, Elizabeth L. Crockett, Peter H. Niewiarowski, Richard L. Londraville

Biology Faculty Research

We tested the hypothesis that the physiological strategy for acclimating to low body temperature is similar among closely related fish. Largemouth bass (Micropterus salmoides), green sunfish (Lepomis cyanellus), bluegill sunfish (Lepomis macrochirus), black crappie (Pomonix nigromaculatus), and white crappie (Pomonix annularis), all members of the family Centrarchidae, were acclimated to 5degrees and 25degreesC. Morphometric variables (total mass, total length, organ masses) and enzyme activities (hexokinase; lactate dehydrogenase; and cytochrome oxidase in heart, liver, and muscle) were measured in 5degreesC- and 25degreesC- acclimated fish at 5degrees and 25degreesC assay temperatures. Each species displayed a distinct physiological response to cold acclimation that …


Differential Expression Of Cadherin-2 And Cadherin-4 In The Developing And Adult Zebrafish Visual System, Qin Liu, S. G. Babb, Z. M. Novince, A. L. Doedens, J. Marrs, P. A. Raymond Nov 2001

Differential Expression Of Cadherin-2 And Cadherin-4 In The Developing And Adult Zebrafish Visual System, Qin Liu, S. G. Babb, Z. M. Novince, A. L. Doedens, J. Marrs, P. A. Raymond

Biology Faculty Research

Cadherins are homophilic cell adhesion molecules that control development of a variety of tissues and maintenance of adult structures. Although cadherins have been implicated in the development of the brain, including the visual system, in several vertebrate species, little is known of their role in zebrafish. In this study, we examined distribution of cadherin-2 (Cdh2, N-cadherin) in the visual system of developing and adult zebrafish using both immunocytochemical and in situ hybridization methods, and we compared Cdh2 distribution to that of the previously reported and closely related cadherin-4 (Cdh4, R-cadherin). As in other vertebrates, in zebrafish embryos Cdh2 was widely …


Energy Budgets, Growth Rates, And The Rmal Constraints: Toward An Integrative Approach To The Study Of Life-History Variation, Peter H. Niewiarowski Apr 2001

Energy Budgets, Growth Rates, And The Rmal Constraints: Toward An Integrative Approach To The Study Of Life-History Variation, Peter H. Niewiarowski

Biology Faculty Research

Variation in thermal constraints on activity has been hypothesized to be an important ecological source of geographic variation in growth rates of juvenile eastern fence lizards Sceloporus undulatus. However, most of the evidence to support this hypothesis is either inferential or indirect. In this study, I quantitatively compared thermal constraints on activity and their relationship to growth rates of free-ranging juvenile fence lizards from two extremes of the range of variation in growth rate (Nebraska and New Jersey) used in a reciprocal transplant experiment. I also examined energy allocation made to growth and storage by yearling lizards. Reduced growth rates …


Effects Of The Zebra Mussel On Nitrogen Dynamics And The Microbial Community At The Sediment-Water Interface, Peter J. Lavrentyev, Wayne S. Gardner, Longyuan Yang Mar 2000

Effects Of The Zebra Mussel On Nitrogen Dynamics And The Microbial Community At The Sediment-Water Interface, Peter J. Lavrentyev, Wayne S. Gardner, Longyuan Yang

Biology Faculty Research

A flow-through experiment was conducted on intact cores of sediments from Saginaw Bay, Lake Huron, to examine how trophic interactions between filter-feeding bivalve mussels and microbial populations could affect nitrogen dynamics at the sediment-water interface. The zebra mussels used in this experiment removed a large proportion of protozoa and phytoplankton from the overlying water, particularly heterotrophic nanoplankton (up to 82%), while bacterial populations showed less change. A 3-fold decrease in the protozoan to bacterial carbon ratio corresponded to a 2.5-fold increase in relative ammonium removal rates as estimated from the dark loss of N-15-ammonium. Excretion by the bivalves also increased …


Contribution Of Autosomal Loci And The Y Chromosome To The Stress Response In Rats, Pierre Dumas, Zdenka Pausova, Vladimir Kren, Drahomira Krenova, Michal Pravenec, Marc Dumont, Daniel Ely, Monte E. Turner, Yulin Sun, Johanne Tremblay, Pavel Hamet Feb 2000

Contribution Of Autosomal Loci And The Y Chromosome To The Stress Response In Rats, Pierre Dumas, Zdenka Pausova, Vladimir Kren, Drahomira Krenova, Michal Pravenec, Marc Dumont, Daniel Ely, Monte E. Turner, Yulin Sun, Johanne Tremblay, Pavel Hamet

Biology Faculty Research

Stress is a critical contributor to cardiovascular diseases through its impact on blood pressure variability and cardiac function. Familial clustering of reactivity to stress has been demonstrated in human subjects, and some rodent models of hypertension are hyperresponsive to stress. Therefore, the present study was designed to uncover the genetic determinants of the stress response. We performed a total genome linkage search to identify the loci of the body temperature response to immobilization stress in a set of recombinant inbred strains (RIS) originating from reciprocal crosses of spontaneously hypertensive rats (SHR) with a normotensive Brown Norway Lx strain. Two quantitative …


Phenotypic Effects Of Leptin In An Ectotherm: A New Tool To Study The Evolution Of Life Histories And Endothermy?, Peter H. Niewiarowski Jan 2000

Phenotypic Effects Of Leptin In An Ectotherm: A New Tool To Study The Evolution Of Life Histories And Endothermy?, Peter H. Niewiarowski

Biology Faculty Research

Leptin is a hormone that regulates energy expenditure and body mass in mammals, and it has attracted considerable attention because of its potential in treating human obesity. Comprehensive data from both pathological and non-pathological systems strongly support a role for leptin in regulating energy metabolism, in thermoregulation and in regulating the onset of puberty. We report here that daily injections of recombinant murine leptin in fence lizards (Sceloporus undulatus) produce phenotypic effects similar to those observed when leptin injections are given to mice, Lizards injected with leptin had body temperatures 0.6 degrees C higher, ate 30 % less food and …


Testosterone Effects On Renal Norepinephrine Content And Release In Rats With Different Y Chromosomes, Thomas J. Jones, Gail Dunphy, Amy Milsted, Daniel Ely Nov 1998

Testosterone Effects On Renal Norepinephrine Content And Release In Rats With Different Y Chromosomes, Thomas J. Jones, Gail Dunphy, Amy Milsted, Daniel Ely

Biology Faculty Research

The Y chromosome in spontaneously hypertensive rats (SHR) and stroke-prone rats has been shown to contain a locus that contributes to the hypertensive effect; both the sympathetic nervous system and testosterone may be involved. The objective of this study was to look at the effects of testosterone on renal norepinephrine (NE) release and content in the isolated perfused kidney in different Y chromosome backgrounds. The study involved male SHR, Wistar-Kyoto rats (WKY), and 2 consomic strains with different Y chromosomes (n=5 to 8 per group). Adult animals were castrated, and implants containing testosterone propionate were placed at the base of …