Biology Commons^™

Neural Defects And Cardiac Arrhythmia In Fish Larvae Following Embryonic Exposure To 2,2',4,4'-Tetrabromodiphenyl Ether (Pbde 47), Sean C. Lema, Irvin R. Schultz, Nathaniel L. Scholz, John P. Incardona, Penny Swanson

Biological Sciences

Polybrominated diphenyl ethers (PBDEs) are added to plastics, polyurethane foam, and textiles as a flame retardant. While PBDEs play a key role in reducing loss of human life and property from fires, these flame retardants have become pervasive organic contaminants in the environment and in the tissues of fish, birds, marine mammals, and humans. Levels of PBDEs in wildlife and humans continue to rise, raising concerns about potential ecological and health risks associated with exposure to these chemicals. Nevertheless, there is little currently known about the toxicological effects of PBDE exposure. Here, we examined the developmental toxicity of the PBDE …

Testing An Ecophysiological Mechanism Of Morphological Plasticity In Pupfish And Its Relevance To Conservation Efforts For Endangered Devils Hole Pupfish, Sean C. Lema, Gabrielle A. Nevitt

Biological Sciences

Imperiled species that have been translocated or established in captivity can show rapid alterations in morphology and behavior, but the proximate mechanisms of such phenotypic changes are rarely known. Devils Hole pupfish (Cyprinodon diabolis) are endemic to a single desert pool and are characterized by a small body, large head and eyes, and lack of pelvic fins. To lessen the risk of extinction, additional populations of C. diabolis were established in artificial refuges. Yet, pupfish in these refuges rapidly shifted to a larger body, smaller head and eyes, and greater body depth. Here we examined how food availability …

Population Divergence In Plasticity Of The Avt System And Its Association With Aggressive Behaviors In A Death Valley Pupfish, Sean C. Lema

Biological Sciences

Behavioral differences can evolve rapidly in allopatry, but little is known about the neural bases of such changes. Allopatric populations of Amargosa pupfish (Cyprinodon nevadensis) vary in aggression and courtship behaviors in the wild. Two of these wild populations were recently found to differ in brain expression of arginine vasotocin (AVT)—a peptide hormone shown previously to modulate aggression in pupfish. These populations have been isolated for less than 4000 years, so it remained unclear whether the differences in behavior and neural AVT phenotype were evolved changes or plastic responses to ecologically dissimilar habitats. Here, I tested whether these …

The Biology Of Canadian Weeds. 133. Cuscuta Campestris Yuncker, C. Gronovii Willd. Ex Schult., C. Umbrosa Beyr. Ex Hook., C. Epithymum (L.) L. And C. Epilinum Weihe, Mihai Costea, François J. Tardif

Biology Faculty Publications

Cuscuta spp. (dodders) are rootless, holoparasitic herbs with filiform stems attached to the host by numerous haustoria. In Canada, Cuscuta gronovii is the most common native species of the genus followed by Cuscuta campestris and C. umbrosa. Cuscuta epithymum and C. epilinum, both introduced species in Canada, occur occasionally. Infestation by Cuscuta spp. can result in serious yield losses and dodders are listed as noxious weeds in British Columbia, Ontario and Québec, and as restricted weeds in Alberta. These plants have evolved special adaptations to ensure their success: germination occurs late in the season when potential hosts are …

Sexually Dimorphic Social Development And Female Intrasexual Chemical Signaling Of African Elephants (Loxodonta Africana), Jordana M. Meyer

College of Graduate Studies: Theses & Dissertations

Author's abstract: African elephants are a polygynous species in which males and females carry out dimorphic lifestyles. Males search and compete for reproductively active females, while females care for offspring and facilitate group cohesion. The objectives of this study was a) to compare the development of sexually dimorphic behaviors and developmental trends between young male and female wild African elephants and b) to determine the ability of captive female African elephants to discern between the follicular and luteal phase of conspecifics through trunk-tip contacts and the investigation of urine, and whether the reproductive phase of the receiver affected the response …

Vocal Development In American Kestrel (Falco Sparverius) Nestlings, John A. Smallwood, Valerie Dudajek, Sivajini Gilchrist, Mary Anne Smallwood

Department of Biology Faculty Scholarship and Creative Works

We studied the acoustical characteristics of calls made by nestling American Kestrels (Falco sparverius). A total of 563 vocal samples was obtained from 88 chicks (49 males and 39 females) from 20 broods. Thirteen frequency, three numerical, and two temporal characteristics were measured using audio spectrography. Discriminant function analysis failed to distinguish the calls of male and female chicks, but univariate and principal component analyses suggest that vocal ontogeny proceeds more rapidly in males than in females. The acoustical characteristics of call notes changed in a consistent manner as nestlings matured, and by day 16 chicks produced calls similar to …

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 …

Rnai As A Tool For Understanding Germline Development In Caenorhabditis Elegans: Uses And Cautions, Eleanor M. Maine

Biology - All Scholarship

RNA-mediated genetic interference (RNAi) has become a very useful tool for analyzing gene function in development and other processes. RNAi can be used as a complement to traditional genetic studies or as a primary means of determining biological function. However, the efficacy of RNAi depends on a variety of factors that the researcher must take into consideration. This review focuses on germline development in the nematode, Caenorhabditis elegans, and discusses the uses and limitations of RNAi in providing new information about gene function as well as the possible endogenous role RNAi plays in germline physiology.

The Neonatal Chinchilla Cochlea: Morphological And Functional Study, R. V. Harrison, J. R. Cullen, S. Takeno, R. J. Mount

Scanning Microscopy

The developmental time scale of the cochlea varies from species to species. We investigate here the condition of the neonatal cochlea in the chinchilla, a species increasingly used in auditory research. We have examined the morphology of cochlear hair cells using scanning microscopy, and the development of auditory function during the first postnatal month by monitoring auditory brainstem evoked responses (ABR). We find that although there were some outer hair cell kinocilia present in middle and apical areas, the hair cells otherwise were mature at 24 hours after birth. Furthermore, cochlear auditory thresholds are adult-like at birth. However, whilst there …

The Effect Of Thyroid Hormone On The Expression Of A7 Myosin Heavy Chain Mrna In Xenopus Laevis, Bradley Thomas Butkovich

Master's Theses

It has long been known that thyroid hormone (TH) is responsible for metamorphosis in tadpoles. It is also known that A7 MHC, an adult muscle isoform, is expressed in adult Xenopus laevis frogs, but not in larvae. Furthermore, the appearance of A7 corresponds with the onset of metamorphosis. The present study investigated the relationship between TH and the expression of A7 MHC mRNA in Xenopus laevis. Isolated tails in culture and 6-n-propyl 2-thiouracil (PTU) treated tails were treated with TH and the presence of A7 mRNA analyzed with in-situ hybridization, and RT-PCR. It was found that TH caused substantial …

Touch-Plate And Statolith Formation In Graviceptors Of Ephyrae Which Developed While Weightless In Space, Dorothy B. Spangenberg, Elisa Coccaro, Russell Schwarte, Brian Lowe

Scanning Microscopy

Ultrastructural studies of the statocysts and touch-plates of graviceptors (rhopalia) of Aurelia ephyrae revealed that (1) touch-plate hair cells are present; and (2) cytoplasmic strands from the hair cell bases extend from the neurite plexus to touch similar strands from the lithocytes. This close association of hair cell neurites and statocysts may have important implications regarding the transmitting and processing of positional information with respect to the gravity vector.

Graviceptors of ephyrae which developed while weightless in microgravity were compared with controls at the ultrastructural level. We found that hair cells of ephyrae which developed in microgravity had fewer lipid …

Development Of An Enzyme Linked Immunosorbent Assay Capable Of Detecting Antibodies Specific To The Cytomegalovirus, Rachel Bird

Undergraduate Honors Capstone Projects

The cytomegalovirus (CMV) is capable of causing serious illness and death in immunocompromised individuals. The objective of this research is to develop a method of detecting antibodies against CMV. This has lead to the development of an Enzyme linked Immunosorbent Assay (ELISA) that is capable of detecting CMV or anti-CMV antibodies. The process in the development of such an assay involves; 1) the purification of Hyperimmune Rabbit Serum containing anti-CMV antibodies, 2) determination of the appropriate concentrations necessary to provide a clear and concise response to the test, and 3) testing of monoclonal antibodies to determine their specificity towards the …

The Effects Of Thyroid Hormone On Myosin Heavy Chain A-7 Production In Xenopus Laevis Tail And Leg Muscles, Andrew R. Noble

Honors Theses

The present research examines the expression of myosin heavy chain genes in muscle fibers in Xenopus laevis. Characteristically different muscle fibers are expressed before and after metamorphosis. The embryonic myosin proteins that are synthesized during the tadpole stages are replaced with adult myosin heavy chains at metamorphosis. At least one of the adult myosin genes, called A-7, is expressed only in the adult animals, not in tadpoles. The controlling factor or trigger for the expression of this adult gene still remains unknown. There are a number of possible explanations for the A-7 regulation at metamorphosis, including changes in particular hormone …

Scanning Electron Microscopic Study Of The Postnatal Development Of The Rabbit Cochlea, With An Emphasis On Innervation, Hirofumi Morita, Tomoyuki Hoshino, Kunihiro Mizuta, Satoshi Iwasaki

Scanning Microscopy

The development of nerve fiber arrangements of the organ of Corti was studied in rabbits 1, 3, 5, 7 and 12-days-old using thick sections from celloidin-embedded cochleas which were examined under a scanning electron microscope. The arrangements of nerve fibers varied with developmental age. The tunnel spiral bundle was thick and loosely collected in the immature cochlea. The outer spiral fibers were recognized even in the narrow space of Nuel in the one-day-old cochlea. As Nuel's space is extending, the fibers course along the medial side of Deiters' cells. The arrangement of the outer spiral fibers was irregular and sparse …

Enhancers Of Gzp1, A Gene Required For Cell-Signaling In Caenorhabditis Elegans, Define A Set Of Genes Required For Germline Development, Li Qiao, James L. Lissemore, Pei Shu, Anne Smardon, Melanie B. Gelber, Eleanor M. Maine

Biology - All Scholarship

The distal tip cell (DTC) regulates the proliferation or differentiation choice in the Cmorhabditis ekgans germline by an inductive mechanism. Cell signaling requires a putative receptor in the germline, encoded by the glp-1 gene, and a putative signal from the DTC, encoded by the lag-2 gene. Both glp-1 and lag-2 belong to multigene gene families whose members are essential for cell signaling during development of various tissues in insects and vertebrates as well as C. elegans. Relatively little is known about how these pathways regulate cell fate choice. To identify additional genes involved in the glp-1 signaling pathway, we carried …

Technical Improvements In Corrosion Casting Of Small Specimens: A Study On Mesonephric Tubules And Vessels Of Chicken Embryos, A. Carretero, H. Ditrich, M. Navarro, H. Splechtna, J. Ruberte

Scanning Microscopy

The injection technique for corrosion casting of small, embryonic material can be improved by using a "chemical ligature" (cyanocrylate). With this simple method, leakage of the resin at the injection site is prevented and the mechanical stability of the cannula-vessel coupling is improved.

The blood vascular system of chicken embryos as small as Hamburger-Hamilton stage 24 (approximately 4.5 days of incubation) has successfully been injected using this procedure. Corrosion casts of the mesonephric tubular system have been made in a similar manner. Additionally, a simple way for secure transport of the fragile casts by immersion in 10% gelatin is suggested.

Intragenic Dominant Suppressors Of Glp-1, A Gene Essential For Cell-Signaling In Caenorhabditis Elegans, Support A Role For Cdcl O/Swz6/Ankyrin Motifs In Glp-1 Function, James L. Lissemore, Peter D. Currie, Christine M. Turk, Eleanor M. Maine

Biology - All Scholarship

The glp-1 gene product mediates cell-cell interactions required for cell fate specification during development in Caenorhabditis elegans. To identify genes that interact with glp-1, we screened for dominant suppressors of two temperature-sensitive glp-1 alleles and recovered 18 mutations that suppress both germline and embryonic glp-1 phenotypes. These dominant suppressors are tightly linked to glp-1 and do not bypass the requirement for a distal tip cell, which is thought to be the source of a signal that is received and transduced by the GLP-1 protein. Using single-strand conformation polymorphism (SSCP) analysis and DNA sequencing, we found that at least 17 suppressors …

Scanning Electron Microscope Observations Of Brine Shrimp Larvae From Space Shuttle Experiments, Lynnette Debell, Avelina Paulsen, Brian Spooner

Scanning Microscopy

Brine shrimp are encysted as gastrula stage embryos, and may remain dehydrated and encysted for years without compromising their viability. This aspect of brine shrimp biology is desirable for studying development of animals during space shuttle flight, as cysts placed aboard a spacecraft may be rehydrated at the convenience of an astronaut, guaranteeing that subsequent brine shrimp development occurs only on orbit and not on the pad during launch delays.

Brine shrimp cysts placed in 5 ml syringes were rehydrated with salt water and hatched during a 9 day space shuttle mission. Subsequent larvae developed to the 8th larval stage …

Morphological Correlates Of Mechanotransduction In Acousticolateral Hair Cells, J. O. Pickles, G. W. Rouse, M. Von Perger

Scanning Microscopy

The development of ideas on mechanotransduction in acousticolateral hair cells is described, leading to the current idea that transduction depends on deflection of the bundle of stereocilia by a force parallel to the plane of the sensory epithelium. Electrophysiological experiments are summarised, suggesting that transduction depends on a shear between the different rows of stereocilia, and that the transducer channels are situated towards the tips of the stereocilia. Analysis of the ways that shear between the rows of stereocilia could be detected suggests that tip links are the structures which are most likely to transmit the stimulus-induced forces to the …

Cell Rearrangement And Directional Migration In Pronephric Duct Development, T. J. Poole

Scanning Microscopy

The morphology of the directed migration of the pronephric duct rudiment of three vertebrates, the salamander, chick and sturgeon, has been examined by scanning electron microscopy. Of particular interest in this paper are the morphology of the duct tip, the role of cell rearrangement, and the relation of duct extension to somite segmentation. The duct rudiments of all three species have motile cell processes (lamellipodia and filopodia) largely confined to their posterior tips. The salamander and sturgeon embryos extend their duct rudiments by extensive cell rearrangements. A short, wide rudiment is elongated to form a long, thin one. The chick …

Security Of Infantile Attachment As Assessed In The Strange Situation: Its Study And Biological Intrepretation, Michael E. Lamb, Ross A. Thompson, William P. Gardner, Eric Charnov, David Estes

Biology Faculty & Staff Publications

We study the Ainsworth 'Strange Situation' procedure to assess attachment between infant and parent, and intrepret individual variation in terms of modern human behavioral ecology ( sociobiology)

Some Factors Involved In Growth And Sporulation Of Pilobolus Crystallinus Tode And Pilobolus Umbonatus Buller, Kenneth L. Poff

Master's Theses

Pilobolus umbonatus Buller and P. crystallinus Tode grew normally in a nitrogen atmosphere but their sporagnia were non-pigmented. When palced in anaerobic jars along with obligately anaerobic and obligately aerobic bacteria, the fungi grew in the range of oxygen concentrations too low for growth of the aerobic bacterium, but high enough to prevent growth of the anaerobe. The fungi did not grow when the oxygen was depleted to the point that allowed growth of the anaerobic bacterium. Catalase was not produced by the hyphae and trophocysts which normally grow beneath the surface of the medium, but was present in the …

Embryology And Evolution, Malo Marius Amunson

Manuscript Thesis Collection

The proofs of evolution must be sought in the entire field of science. Direct proof is found in the study of Morphology, whose bases are comparative anatomy; embryology; in the study of paleontology, of geology, of geographical distribution, in the study of nature and experiments of today. In this vast field of direct proofs of evolution it is our purpose to present some of the evidences of evolution as furnished by one of these, namely, Comparative Embryology.