Biology Commons^™

Estructura Del Condrocráneo Y Esqueleto Visceral De Larvas De Pseudis Minuta (Anura, Pseudidae, E. O. Lavilla, Rafael O. De Sá

Biology Faculty Publications

The chondrocranium and visceral skeleton of Pseudis minuta tadpoles are described, based on a series of five larvae in stages 31 - 35 of Gosner (1960). Among their striking characters are the presence of peculiar articular surfaces between cornua trabeculae and suprarostral cartilage, the incomplete development of the orbital cartilage, the high fenestration of the floor of the cavum cranii, the fusion of posterior foramina, and the fusion of spicules 3 and 4 in the hyobranchial skeleton.

The Timing And Pattern Of Myogenesis In Hymenochirus Boettgeri, Matthew T. Smetanick, Rafael O. De Sá, Gary P. Radice

Biology Faculty Publications

Differences in the relative timing of homologous developmental events among closely related species, known as heterochronies, may provide valuable clues in understanding evolutionary relationships (McKinney, 1988; McNamara, 1995). Examining the timing of myogenic events is a relatively easy and effective method for finding heterochronic events. For example, whether muscle proteins and myofibrils appear before or after multinucleation can be determined through histological techniciques (Kielbowna, 1981). Simple observations of live specimens can pinpoint functional landmarks such as first twitch (spontaneous or due to external stimuli) and first heartbeat.

The Timing And Pattern Of Myogenesis In Hymenochirus Boettgeri, Matthew T. Smetanick, Rafael O. De Sá

Biology Faculty Publications

Differences in the relative timing of homologous developmental events among closely related species, known as heterochronies, may provide valuable clues in understanding evolutionary relationships (McKinney, 1988; McNamara, 1995). Examining the timing of myogenic events is a relatively easy and effective method for finding heterochronic events. For example, whether muscle proteins and myofibrils appear before or after multinucleation can be determined through histological techniques (Kielbowna, 1981). Simple observations of live specimens can pinpoint functional landmarks such as first twitch (spontaneous or due to external stimuli) and first heartbeat.

Transplanting Broodstock Oysters, Crassostrea Virginica, Onto Reconstructed Oyster Reefs To Increase Spat Recruitment In The Piankatank River, Dawn Chentil Sherwood

Master's Theses

Four oyster reefs were recreated from oyster shells to historical proportions in the Piankatank River from 1993-1995. In December 1997, two of the reconstructed reefs were supplemented with large broodstock oysters from Tangier and Pocomoke Sounds. Since total quantity as well as density ofbroodstock were believed to be limiting factors for recruitment in this river, adding stock was expected to raise spat recruitment. Methods included dive surveys on the reefs, and dredge and patent tong surveys on the natural oyster bars. The recruitment of spat to both reefs and bars was significantly higher in 1998 (p<0.001) than in the previous four years and a positive interaction (p<0.005) was seen between the reefs and the year 1998. Based on these dat~ stock enhancement in the Piankatank River successfully improved recruitment and suggest oyster restoration may be facilitated in other areas of the Chesapeake Bay by strategic enhancement of spawning stocks.

Development Of The Suprarostral Plate Of Pipoid Frogs, Rafael O. De Sá, Charles C. Swart

Biology Faculty Publications

The rostral region of nonpipoid tadpoles has two sets of cartilages, the cornua trabeculae and the suprarostral cartilages, whereas the rostral region in pipoid larvae is occupied by a single and continuous cartilage, the suprarostral plate. The homology of this region in pipoid and nonpipoids tadpoles has been controversial. We examined the early formation and development of the suprarostral plate using serially cross-sectioned specimens of Rhinophrynus, Xenopus, and Hymenochirus. We conclude that the cartilaginous structures present in the rostral area of pipoid and nonpipoid larvae are homologous. Furthermore, we found two different developmental patterns among pipoid larvae. The chondrocranium …

Osteological Analysis Of The Killifish Genus Cynolebias (Cyprinodontiformes: Rivulidae), Marcelo Loureiro, Rafael O. De Sá

Biology Faculty Publications

Relationships among the species of the annual fish Cynolebias are unclear. An analysis of the variation and utility of osteological characters for phylogenetic analysis was done using cleared and double-stained specimens representing 21 species of Cynolebias. This analysis showed that some of the characters previously used to diagnose this genus and some of the species are polymorphic. Osteologically, Cynolebias can be diagnosed by the following synapomorphies: (1) triangular-shaped parietal, (2) vomer positioned ventral to the parasphenoid, (3) long ventral process of the dentary, (4) teeth on fourth ceratobranchial, and (5) teeth on first epibranchial. In addition, characters that help …

Method For Identification Of Origins Of Replication And Genes Regulated By Dnaa In Bacteria, Olga G. Troyanskaya

Honors Theses

The study is focused on developing computer programs to identify origin of DNA replication based on analysis of total bacterial genomes, scoring regions for number of DnaA binding sites, AT content, DNA adenine methylase boxes, and integration host factors binding sites. The programs were tested on cyanobacterium Synechocystis, and several potential origins were identified. However, no one definite region could be located. Currently, software is being developed to analyze common motifs around the origins of all bacteria with known origins. Genes whose transcription could be regulated by DnaA were identified by searching for DnaA boxes preceding promoter regions.

Chondrocranial And Oral Morphology Of Leptodactylid Larvae, William Hagood Turner

Master's Theses

I focused my research on Leptodactylidae in order to determine the usefulness of chondrocranial and internal oral characters in systematic and phylogenetic studies of this anuran family. To achieve this goal, I examined the chondrocrania of eight species of the Leptodactylinae: Adenomera marmorata, Edalorhina perezi, Limnomedusa macroglossa, Physalaemus gracilis, P. henselii, P. pustulosus, Pleurodema brachyops, and P. tucumana. Furthermore, I analyzed and described the internal oral anatomy of Physalaeum us gracilis, P. henselii, and Limnomedusa macroglossa and the skeletogenesis of P. gracilis and P. pustulosus. Subsequently, I integrated these data with all available data on the larval chondrocrania and internal …

The Chondrocranium Of The Mexican Burrowing Toad, Rhinophrynus Dorsalis, Charles C. Swart, Rafael O. De Sá

Biology Faculty Publications

The chondrocranium of Rhinophrynus dorsalis is described and illustrated. Autapomorphies of R. dorsalis are the presence of the symplectic cartilage and a cartilaginous process on the ascending process of the palatoquadrate. Synapomorphies of Rhinophrynus shared with the Pipidae are: (1) early formation of the lower jaw and (2) presence of a suprarostral plate. Alternative developmental pathways for the formation of the suprarostral plate are considered. Histological data indicates that the suprarostral plate forms from: (1) the early fusion of the cornua trabeculae with the suprarostral cartilages, (2) an anterior growth of the ethmold plate, and (3) subsequent fusion …

Unidad De Los Anfibios Modernos Como Grupo Natural, Rafael O. De Sá

Biology Faculty Publications

RESUMEN

La monofilia de la infraclase Lissamphibia ha sido cuestionada. Algunos autores sugieren un origen independiente del Orden Gymnophiona basados en la condición compacta (= estegocrotafía) del cráneo de la cecilias. La presente revisión indica la irrelevancia del estegocrotafismo para establecer las relaciones filogenéticas del grupo. Los datos disponibles sugieren: 1) el estegocrotafismo es secundariamente derivado en cecilias, y 2) Lissamphibia representa un grupo monofilético.

SUMMARY

Unity of modern Amphibians as a natural group

The monophyly of Lissamphibia has been previously questioned. Some authors suggested an independent origin of Gymnophiona based on the solid condition (= stegokrotaphy) of the caecilian …

The Effect Of Different Warm-Downs On Heart Rate Recovery And Muscular Lactic Acid Removal, Alison Jean Perkins

Honors Theses

Competitive swimmers and coaches have had varying ideas about what exercises constitute an appropriate warm-down. However, there is much agreement about what a warm-down should achieve. A good warm-down should do three things. First, a warm-down should be successful in returning the swimmer's elevated heart rate to the resting heart rate level in a relatively short period of time. Second, the warm-down should flush lactic acid out of the muscles as quickly as possible, and restore blood lactate to baseline levels. Finally the warm-down should contribute to improved athletic performances.

In this experiment, it was expected that a decreasing intensity …

Establishing A Link Between Mapk Pathways And Hormones Signal Transduction In Plants, Marc Meulener

Honors Theses

Mitogen Activated Protein Kinase (MAPK) pathways are ubiquitous among eukaryotes, and are involved in the transduction of various extracellular signals. In mammals, three MAPK pathways have been identified, two of these respond to stress, and one can stimulate growth and differentiation. MAPKs have also been found in plants, and it has been suggested that a MAPK pathway may be involved in the signal transduction of auxin and cytokinin, two plant hormones that stimulate growth and differentiation. However, at this time, there is no conclusive evidence supporting this hypothesis. By studying the effect ofMAPKK's of both plant and animal origin in …

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 …

Sustainable Development In The Third World: An Assessment Of The Conservation Actions In South Africa, Brazil, Malaysia, And Madagascar, Carol Rizkalla

Honors Theses

As a library research project, this thesis has gone beyond research in the library, and it could not have been possible without the aid of several people. First I must thank the organizations which responded to my request for information: the Center for Environmental Information, the Rainforest Action Network, the World Wildlife Fund, and Conservation International Specifically, Jill McLaughlin in the Communications Department of CI was· most gracious in sending me management plans for parks in Brazil and Madagascar. Carla Langeveld of the WWF, was very helpful during my visit to their library, and subsequently in my request for the …

Heat Shock Protein Synthesis In The Gorgonian Leptogorgia Virgulata, Evelyn Afif

Honors Theses

No abstract provided.

Area-Species Curve Applies To Gaps In A Canada Hemlock (Tsuga Canadensis (L.) Carr.) Forest In The Shenandoah National Park, Joseph John Lacroix

Master's Theses

A typical area-species curve shows that species richness (number of species) and island size are positively correlated. I tested whether the area-species concept, which was developed using islands, could be applied to herbaceous plants in canopy gaps in a hemlock community.

I conducted studies in Limberlost, Shenandoah National Park. I measured the species richness of herbaceous plants in six gaps during the summer and fall of 1995 and eight gaps and one non-gap site in the spring of 1996. The two additional gaps in 1996 extended the upper range of gap sizes. I calculated the correlation between species richness and …

Chondrocranial And Oral Morphology Of Pipoid Frogs, Charles Christopher Swart

Master's Theses

The Pipoidea are a diverse group of frogs. Their diversity is demonstrated in their morphology, ecology, and behavior. One pipoid species, Xenopus laevis, has been used as a model system of developmental, physiological, and molecular studies of vertebrates. My work has focused on the developmental morphology of the chondrocranium and oral morphology of four pipoid taxa: Hymenochirus boettgeri, Rhinophrynus dorsalis, Pipa carvalhoi, and Xenopus laevis. Previous studies have suggested that the Anura may be diphyletic based on the unique characteristics of the chondrocanial morphology of pipoids. The chondrocranial and internal oral morphology of the pipoids indicates that as a group …

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 …

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.

A Profile Of Antibiotic Resistant Bacteria In The James River, Keith Allen Boisvert

Master's Theses

Spatial and temporal variability in the antibiotic resistance of bacterial assemblages in the lower portion of the James River was examined. The antibiotic resistance of culturable coliforms was compared to the resistance in the microbial community. Antibiotic resistance was determined via colony formation on media containing antibiotics. The antibiotics ampicillin, chloramphenicol, streptomycin and tetracycline were used at concentrations ranging from 10 to 500 ug/ml. Statistically significant differences in the mean number of antibiotic resistant isolates were observed among both sample sites and dates. The sampling site at river mile 99 just below Richmond showed both increased antibiotic resistance and bacterial …

Semipermeable Membrane Devices Are Effective Surrogates Of Fish In Concentrating Polychlorinated Biphenyls, Christopher Gardner Collins

Master's Theses

This study examined the effectiveness of Semipermeable Membrane Devices (SPMDs) as surrogates for fish in concentrating polychlorinated biphenyls. Golden shiners (Notemigonus crysolucas) and SPMDs were exposed to three different concentrations (0.5, 1.5, and 3.0ppm) of Aroclor 1254 for 1, 3, and 5 days under laboratory conditions. Concentrations of Aroclor 1254 were measured in the SPMDs and fish tissue using extraction techniques and gas chromatography. The concentrations of PCB in SPMDs and N. crysolucas were positively correlated. This relationship compared favorably with data from other studies. The relationship between the concentration of PCB in SPMDs and tissue offish and …

The Tadpole Of Pseudis Minuta (Anura: Pseudidae), An Apparent Case Of Heterochrony, Rafael O. De Sá, Esteban O. Lavilla

Biology Faculty Publications

The external morphology, oral disc, and coloration pattern of the larva of Pseudis minuta are described. Tadpoles are mostly bottom dwellers that have a small, terminal oral disc with a labial tooth row formula 1(1-1)/(1-1)2. Internal oral anatomy is characterized using scanning electron microscopy, representing the only description available for the family Pseudidae. The coloration pattern of P. minuta tadpoles is compared with that of other pseudids. Pseudis minuta larvae do not exhibit the ontogenetic coloration change reported for P. paradoxa. Considering larval coloration, larval size, and reports of adult size, acceleration or hypermorphosis are suggested as possible heterochronic mechanisms …

The Stabilizing Efects Of Disulfide Bonds On Limulus And Octopus Hemocyanin, Danielle Mercatante

Honors Theses

Hemocyanin is a large molecular weight, oxygen carrying protein that is present in the hemolymph of mollusks and arthropods . Limulus, horseshoe crab, hemocyanin is made up of 48 hexamer subunits ( consisting of seven different repeating subunits) each of which have oxygen binding dinuclear copper active centers. Octopus hemocyanin is composed of a single kind of polypeptide chain that has seven functional units, or oxygen binding domains.

The goals of research conducted by Gregory Cole and Danielle Mercatante during the fall of 1996 and spring of 1997 were to gain a biochemical understanding of the structure of Limulus and …

Description Of The Tadpole Of Atelopus Tricolor, E. O. Lavilla, Rafael O. De Sá, Ignacio De La Riva

Biology Faculty Publications

Tadpoles of Atelopus belong to the gastromyzophorous guild of exotrophic larvae (Altig and Johnston, 1989), and are characterized by the presence of a conspicuous abdominal sucker and an expanded oral disc. The larvae of several Atelopus species have been described previously: A. varius (Starrett, 1967); A. certus, A. ignescens, and A. spumarius (Duellman and Lynch, 1969); A. cruciger (Mebs, 1980); A. flavescens (Lescure, 1981); A. peruensis (Gray and Cannatella, 1985); and A. subornatus (Lynch, 1986). These represent about 15% of the known species in the genus (Frost, 1985; Duellman, 1993). Although Atelopus tricolor was originally described at the beginning of …

Description Of Tadpoles Of Three Species Of Scinax (Anura: Hylidae), Rafael O. De Sá, Rocjard Wassersig, Arturo I. Kehr

Biology Faculty Publications

Larval morphological characteristics have been used to cluster species of Scinax in seven species groups and to support the monophyly of some of these groups. However, our present knowledge of Scinax tadpoles is incomplete; currently, tadpoles of only 21 of the approximately 80 recognized species have been described. Herein, we describe and illustrate the external morphology and oral disc characteristics of larval Scinax berthae, S. nebulosa, and S. boesemani. The presence of a "labial arm" supporting the P3 tooth row in S. boesemani, and its absence from S. nebulosa, is discussed in the light of our limited knowledge of tadpoles …

Internal Oral Anatomy: A Comparative Analysis Of The Phyllomedusinae (Anura:Hylidae), Erin B. Hines

Honors Theses

The internal oral anatomy of phyllomedusines has only been described for Agalychnis callydrias using light microscopy. Herein, we compare the internal oral anatomy of the genera Phyllomedusa, Agalychnis, Pachymedusa, and Phasmahyla, using SEM methodology. Tadpoles of ten species were prepared using standard SEM techniques; these larvae ranged from Gosner stages 34-39. Phasmahyla has a unique prenarial arena with three well developed pre-narial arena papillae, whereas the other genera possess the prenarial arena papillae in a semicircular arrangement with the opening directed posteriorly. Pachymedusa differs from Phyllomedusa and Agalychnis by having a low, straight-edge, median ridge; also, its buccal floor arena …

Ubiquitin-Mediated Proteolysis During Gametogenis In Chlamydomonas Reinhardtii, Hall Thomas Mcgee

Honors Theses

Scientists in the field of cell biology have focused considerable attention on a unicellular species of green algae known as Chlamydomonas reinhardtii. This organism is relatively common in bodies of fresh water and some types of soil, but most of the attention is due to its value as a model for biochemical studies. This laboratory has undertaken a broad study of the species including exploration into a special class of proteins, called heat shock proteins, and certain biochemical processes of the organism. The work herein described is a part of this latter study, and also a preliminary step in a …

The Effects Of 2,4-Dichlorophenoxyacetic Acid On The Diazotrophic Soil Microbial Community, Denise M. Brown

Master's Theses

This study measures the effects of 2,4- dichlorophenoxyacetic acid (2,4-D) on growth and nitrogen fixation capabilities of the native microbial soil community during eight field trials conducted over an eight month period. After application of 2,4-D, soil samples were analyzed for enumeration of diazotrophic and general microbial communities, and for nitrogenase activity as measured by the acetylene reduction assay (ARA). Statistical analyses were conducted using Minitab. Results show that 2,4-D significantly stimulated growth of diazotrophic microbes in 87.5% of the trials and was found to have a stimulatory growth effect on the general microbes in 62.5% of the trials. A …

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 …

Osteology, Morphology, And Female Choice In Species Of The Genus Cynolebias (Cyprinodontiformes: Rivulidae), Marcelo Loureiro Barrella

Master's Theses

Relationships among the species of the annual fish Cynolebias are unclear. An analysis of the utility of different osteological and morphological characters for phylogenetic analyses was done using clear and double stained specimens and measurements of morphometric parameters respectively. Scanning electron microscopy was used to study the morphology of the egg chorion. Female choice tests were also conducted to test male traits that may be preferred by females. The osteological analysis showed that some characters previously unreported may be phylogenetically useful. Head scalation patterns were found to be intraspecifically variable, making them inappropriate to use in systematics. Each morphometric parameter …