Fourteenth Annual Biology Student Colloquium

April 3rd, 2009, Supple Science Building, TBA.

List of presenters and abstracts:

The objective of this research is to determine effect of diurnal variation on melatonin receptor expression in zebrafish eyes using fluorescence in situ hybridization. Our earlier work using microarrays indicated that Arylalkylamine N-acetyltransferase (AANAT) which encodes the rate limiting enzyme in the melatonin biosynthetic pathway, is upregulated 3-fold at mid-night relative to its expression levels in mid-day. We hypothesized that melatonin receptor expression may be similarly regulated. To test this hypothesis, I performed fluorescence in situ hybridization using oligo-nucleotide probes to detect mRNA for the melatonin 1A, 1B, 1C receptors. My results suggest upregulation of all three subtypes in midnight samples. Results will further be confirmed by quantitative PCR.

Auxin resistant Arabidopsis mutant ada1 exhibits severe defects in tropic responses and development.
Sherry Albers
Department of Biology, Texas State University-San Marcos, 601 University Drive, San Marcos, TX 78666

Auxin, a naturally occurring hormone, is indispensable for growth and development of plants. It modulates the expression of many genes by targeting a group of repressor proteins, Aux/IAAs, for ubiquitination and subsequent degradation by 26S proteasome . Auxin promotes the interaction between Aux/IAA and SCFTIR1/AFBs in which the F-box proteins TIR1 and AFBs functions as the auxin-receptors. Degradation of Aux/IAA allows Auxin Response Factors (ARF) to activate gene transcription. While Indole-3-acetic acid (IAA) is the major natural auxin found in plants, there are many synthetic chemicals that exhibit auxinic activity. Previous work in our laboratory has shown that picloram, a synthetic auxin, which is widely used as an herbicide, may function differently from other commonly known auxins such as IAA and 2,4-D. Mutant analysis is a powerful method to identify and understand components of intricate biological processes such as the aforementioned signaling pathway of auxin. In a forward genetic screening using ethyl methanesulfonate (EMS) mutagenized transgenic Arabidopsis thaliana seedlings carrying the auxin inducible reporter gene DR5::GFP, we identified several mutants that show altered auxin distribution patterns. Wild type seedlings exhibit DR5::GFP expression highly increased in the root tips in response to picloram, whereas mutant seedlings demonstrate a range of expression patterns. In particular, one of these mutants, ada1 (altered distribution of auxin 1), showed slightly increased GFP expression in the hypocotyls, but a very low level of GFP in the root tip. ada1 exhibits severe defects in tropic responses as well as in growth and development. In this mutant, GFP expression is restricted to the quiescent center region of the root tip, and the expression is not responsive to either picloram or 2, 4-D, but slightly responsive to IAA. It has also been shown to be resistant to all the aforesaid auxins. ada1 has already been mapped to the north arm of Chromosome I.

Auxin, the first plant hormone to be discovered, is known to influence many physiological processes. To better understand the exact role played by auxin in plant growth and development, it is essential to understand its function at the molecular level. Functional characterization of Arabidopsis mutants with altered response to auxin is a proven way to achieve this objective. Here we describe the characterization of a novel Arabidopsis mutant, pic64, that exhibits altered response to auxin. pic64 was originally isolated from a screening of ethyl methanesufonate (EMS) mutagenized Arabidopsis seeds against a synthetic auxin, picloram. Mutation is inherited as a semi-dominant trait. pic64 is similar in all aspects to the wildtype plants at mature stages of growth. The primary root growth of pic64 is highly resistant to 2,4D and is slightly resistant to indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) and picloram. However, it is sensitive to 1-naphthelene acetic acid (1-NAA). Expression of the auxin inducible transgene DR5::GFP is impaired in pic64 background suggesting that auxin induced gene transcription is affected in this mutant. The mutation has been mapped to the southernmost region of chromosome 3, and work is in progress to identify the mutant gene and to define its role in the auxin signaling pathway.

Viral infection of bacterial populations in pure culture results in a temporary reduction of cell density. Bacteriophage resistant cells quickly multiply and re-establish a new population. This emergence of bacterial resistance is a major obstacle for the use of phage in the treatment of bacterial disease. Recently, studies have shown that phage infection of Escherichia coli and Salmonella typhimurium in a mixed planktonic culture will result in the extinction of E. coli. Since biofilms commonly occur in nature and disease, we propose to investigate the effect of phage infection on mixed culture biofilms. E. coli and Pseudomonas aeurogenosa, both common pathogens, were chosen for this study. One and two species planktonic cultures were infected with bacteriophage and serial passaged at 24h intervals. Single and mixed species biofilms were grown for 48h and infected with phage. Cell densities were determined at 24h intervals for five days. Both cell types, in the absence of phage, maintained stable populations in one and two species planktonic and biofilm communities. E. coli or Ps. aeurogenosa planktonic and biofilm monocultures infected with either E. coli phage W60 or Ps. aeurogenosa phage PB1 reached high cell densities. However, mixed planktonic cultures infected with phage W60 resulted in the extinction of E. coli, although, mixed species planktonic cultures infected with phage PB1 reached levels equivalent to uninfected cultures. These results demonstrate that the effect of phage infection on survival in multi-species bacterial communities differ greatly from their single species counterparts. The extinction of E. coli in mixed planktonic culture could result from stress of competition with Pseudomonas. The effect of phage infection on mixed species E. coli and Ps. aeurogenosa biofilms is currently under investigation.

The phyto-hormone auxin is vital for plant growth and development throughout the plant lifecycle. At the molecular level, auxin rapidly modulates the expression of auxin responsive genes by promoting the degradation of a family of negative regulators known as Aux/IAA proteins. Besides the major endogenous auxin indoleacetic acid (IAA), there are several other natural and synthetic auxins. Picloram and 2,4-dichlorophenoxyacetic acid (2,4-D) are two synthetic auxins that are commonly used as herbicides. Our initial work suggests that picloram may function differently from other commonly used auxins such as IAA, 2, 4-D and 1-naphthalene acetic acid (1-NAA). To understand the molecular mechanisms of auxin responses in plants, we isolated a group of mutants that exhibited altered response to picloram.
The mutant pic11 is resistant to both picloram and 2,4-D, and exhibits many growth and developmental defects. It produces fewer shorter root hairs compared to wild type and produces no lateral roots. However, 2,4-D, IAA and IBA stimulate lateral root initiation in pic11 at higher concentrations, suggesting that the pic11 mutation does not affect lateral root development, but may diminish sensitivity to auxin. While picloram induces few lateral roots in pic11, all lateral roots initiate at the same point on the root, just below the hypocotyl. Using map-based cloning, the pic11 mutation was identified as an allele of IAA28 that encodes an Aux/IAA protein, a repressor of auxin-induced gene transcription. pic11/iaa28 represents a gain-of-function mutation in domain II of IAA28 protein. While the wild type IAA28 interacts with the auxin receptor proteins in an auxin-dependent manner, the domain II mutation interferes with this interaction, probably leading to the stabilization of the mutant protein. Results of this study along with previous studies by others suggest that the stabilized mutant pic11/iaa28 protein may directly affect the regulation of other auxin-inducible genes that are important in growth and development.

Eighty-six individuals from 31 species of amphibians were collected from the forest floor (~0 m), the shrub/sub-canopy (0-4 m) and mid- to upper canopy (4-38 m) of a Neotropical lowland rainforest near the Tiputini Biodiversity Station (TBS) - Universidad San Francisco de Quito in the Upper Amazon Basin of eastern Ecuador, and analyzed for Batrachochytrium dendrobatidis using a nested PCR protocol. B. dendrobatidis was detected on 17 of the 86 individuals (20%), with positive samples collected from each of the vertical strata. Infection was found to be significantly higher in the fossorial/floor and canopy groups, showing 25% and 33% of individuals infected, respectively, than in the shrub/sub-canopy group with only one individual (3%) infected. Thus, B. dendrobatidis was non-randomly distributed along the vertical axis, suggesting that microhabitat conditions in the different strata can potentially have an influence in host-pathogen dynamics. To our knowledge this is the first examination of Bd infection in amphibians found in the forest canopy and the first record of a symptomatic anuran infected with Bd in lowland tropical rainforests of the Upper Amazon Basin.

After prey capture, flycatchers either return to the perch of foraging flight initiation or fly to a new perch. Conflicting evidence from previous studies suggests return-to-perch behavior is potentially influenced by several factors, some of which are unknown. We examined the relationship of five predictors and return-to-perch proportion of non-breeding Eastern Phoebes (Sayornis phoebe). Eastern Phoebes were more likely to return to the perch of foraging flight initiation as habitat openness increased, suggesting that the extent of fields of view associated with degrees of habitat openness may aid in explaining the greater propensity to return in more open habitats. Open habitats may require more time to effectively search greater fields of view for prey compared with more heavily vegetated environments, making return potentially worthwhile within a perch-specific time frame based on available viewable space. In addition, the relationship between distances (>, <, or =) of foraging flight components (sally and follow-up flights) did not appear to affect return-to-perch proportion, suggesting distances between flycatchers, prey items, and other potential perches may not regularly influence return decisions.

Abstract
The federally-threatened San Marcos salamander (SMS) is spring-adapted and exhibits a geographic range restricted to the headwaters of the San Marcos River. While the headwaters of the San Marcos River (Spring Lake) and the upper portion of the River have been designated as the habitat of the SMS, there is little quantitative information on specific habitat associations of the SMS within this broader habitat. In addition, there is little information on the SMS’s trophic ecology and potential food preferences in the wild. Thus, understanding habitat preferences and trophic ecology of the SMS is critical for the management and preservation of the SMS population, as well as the ecology of the river. To determine the habitat associations of the SMS, I conducted a study in which the occurrence and densities of SMS were evaluated using quadrat counts in Spring Lake and the portion of the River. Prior to surveys, Spring Lake and the upper River were divided into four morphometrically and ecologically defined zones. Sampling sessions were conducted at night and day from June to November, 2008. In addition to determining the densities of SMS, I estimated a variety of habitat parameters within quadrats including percent macrophyte cover, substrate type, temperature, dissolved oxygen, pH, and macroinvertebrate communities. To examine SMS trophic ecology, gut contents were examined in 150 individuals and prey items were identified to the lowest practical taxon. I will additionally conduct stable isotope analysis on SMS and their potential food items in the lake and river to compliment gut content analyses. Analysis of habitat data indicate that SMS within Spring Lake are strongly associated with cobble substrates, spring openings, and the moss Amblystegium. Initial assessment of gut content data shows that the diet of SMS within the lake consists of mostly crustaceans, specifically amphipods (Hyalella) and seed shrimps (Ostrocada).

In the Garcia laboratory we are interested in pigment granule movement in the eyes of zebrafish. When exposed to light, pigment granules in the retinal pigment epithelium (RPE) disperse into apical projections in an effort to shade photoreceptors and minimize photobleaching of the rod photoreceptors. However, during dark phases the pigment granules aggregate back into RPE cell bodies. Cyclic adenosine monophosphate (cAMP), an intracellular messenger, induces aggregation when introduced to the RPE. Our hypothesis is that multidrug resistant protein 4, an ATP binding cassette nucleoside transporter, exports cAMP from the photoreceptors, making cAMP available to enter the RPE and cause aggregation. Support of this hypothesis could be obtained by using antibodies that recognize MRP4 with immunohistochemistry, in order to find if MRP4 localizes to the photoreceptors. Such antibodies have been obtained and a preliminary dot blot was performed to ensure the goat anti-mrp4 primary antibody recognized zebrafish protein. Additionally, a western blot using eye, brain and heart tissue was performed in order determine that the antibody recognizes bona fide MRP4 and which specific organs express MRP4. The results show faint lines around 75 kDa, indicating the expression of MRP4 by eye and brain, but not heart. Immunolocalization experiments are underway to determine the specific cell type(s) that express MRP4 in the eye. Our results show the existence of MRP4 in the eye, consistent with a role in cAMP exportation during dark-adaptation.

The potential role played by the host plant or the population in soil in the selection of symbiotic, nitrogen-fixing Frankia strains from soil for root nodule formation was assessed by using molecular techniques. The diversity of Frankia populations in the root nodules of twelve Alnus species grown sympatrically was analyzed using rep-PCR (Repetitive Extragenomic Palindromic polymerase chain reaction). Analysis of 10 root nodules from each plant species revealed three rep- profiles which indicated the presence of three Frankia strains. One profile (further referred to as Type I) was most abundant and was identical within and among the nodules of nine species (A. incana, A. japonica, A.glutinosa, A. tenuifolia, A.rugosa, A. rhombifolia, A. mandsurica, A. maritima and A. serrulata). Type II profile was found in all nodules of two plant species (A. hirsuta and A. glutinosa pyramidalis), whereas type III profile was unique for Frankia populations in nodules of A. rugosa americana. No variation was detected in Frankia populations among the root nodules of a single plant species. Comparative sequence analyses of nifH gene fragments from three Frankia strains representing each rep-profile (Type I: A. tenuifolia; Type II: A. glutinosa pyramidalis; Type III: A. rugosa americana ) revealed differences, with Type I and II clustering with Frankia strains of subgroup A II (represented by strain Ag45/Mut15) and Type III with Frankia of subgroup A I (represented by strain ArI3). Comparative sequence analysis with 80 clones from a nifH gene clone library from frankiae in soil where these 12 alder species were growing, however, revealed that none of these sequences represented frankiae detectable in soil. These results suggest that host plant species have a role in the selection of Frankia strains for root nodule formation and this selection is not a function of the abundance of a Frankia strain in soil.

Predator avoidance is among the most beneficial behaviors exhibited by prey. Despite this, there are costs associated with antipredator behavior such as time allocation trade-offs with foraging and mating. Prey can improve the efficiency of predator avoidance by matching the intensity of avoidance responses to the level of threat posed by a predator. Prey may ascertain information about predatory threat from secondary risk indicators such as chemical cues from a predator’s recent diet. The San Marcos salamander (Eurycea nana) is an aquatic species endemic to the headwaters of the San Marcos River. It is potential prey for a variety of both native and nonnative fish predators and I predicted that predator diet cues might provide information important for predation risk assessment resulting in more efficient predator avoidance.. To test this, I exposed predator-naïve adult E. nana to either a blank control or the chemical stimuli of native (largemouth bass) or nonnative (redbreast sunfish) predators that had been maintained on either a neutral diet or a diet containing conspecific prey. I recorded the activity level of test subjects before and after stimulus exposure and compared changes in activity levels between treatment groups. My results indicate that E. nana exhibited antipredator behavior (decreased activity) to the chemical stimuli of all predatory treatments, but that responses to predators that had recently consumed conspecific prey were more intense than responses to predators that had not recently consumed conspecifics. This study highlights the importance of risk sensitivity for E. nana and provides information essential to understanding the ecology of this predator-prey system.

The Farm Bill conservation programs serve as the primary tools for the creation and improvement of wildlife habitat on working lands. Wildlife conservation would benefit from a working land prioritization system that integrates these programs. We developed a Geographic Information System (GIS)-based system to prioritize land for inclusion in Farm Bill conservation programs. We designed the system to be applicable throughout the United States, to minimize potential conflicts of interest, and to facilitate simple implementation. We designated high conservation value (HCV) lands using habitats of greatest conservation need. We placed priority zones around HCV lands to determine high and low priority working lands. Nationwide implementation of this system would require gathering and manipulating data from multiple sources, as well as creation of a GIS layer denoting locations of working lands currently in conservation programs. This system would allow funding to be maximized through the ability to select participation based on property location and size, and to target landowners for participation. The wide-ranging potential benefits of this system make it well suited for serving as the backbone to conservation on working lands.

Auxin, a major hormone, is involved in regulation of many aspects of plant growth and development. At the molecular level, auxin modulates the expression of many genes through the degradation of a group of repressor proteins called Aux/IAAs. These proteins are degraded through ubiquitin-proteasome pathway involving SCFTIR1/AFBs, in which TIR1 and AFBs are F-box proteins that function as auxin receptors. They are encoded by a family of genes cosisting TIR1, AFB1,AFB2, AFB3, AFB4 and AFB5. All the encoded proteins except AFB4 and AFB5 are known to interact with auxins. Despite their homology with TIR1 and other AFBs, if AFB4 and AFB5 function as auxin receptors is not known. Recent work indicates that Arabidopsis afb5 mutants are resistant to picolinate group of synthetic auxins, suggesting that AFB5 may also function as an auxin receptor. In order to identify other interacting genes in AFB5 mediated pathway, we undertook a genetic screening to identify enhancers and suppressors of afb5 using seeds from the T-DNA insertion line SALK_110643, named as afb5-6. afb5-6 seeds that are resistant to the synthetic auxin picloram were mutagenized using ethyl methanesulfonate (EMS), M1 seedlings were allowed to self-pollinate and M2 seeds were collected as several pools. M2 seeds were then screened on nutrient agar medium containing 10 micromolar picloram. Suppressor and enhancer mutants were isolated depending on the primary root length of the mutants with respect to the afb5-6 mutants. A range of mutants with growth and developmental defects were identified by this screen.

River ecosystems are often defined by their terrestrial surroundings and evaluated from the landscape perspective. Landscape influences on associated aquatic environments can often vary by scale of observation with relationships between land cover and stream characteristics identifiable from the entire catchment down to the localized stream reach. Results vary indentifying the importance of local versus regional drivers controlling landscape-aquatic interactions between different studies. GIS and multivariate analysis tools were used to evaluate the relationships between landscape characteristics and surface water chemistry in a subtropical karst lotic system. Land use, stream discharge, geology, average and standard deviation terrain slope, distance from spring outfall, and dominant soils were quantified, and redundancy analysis was used to distinguish between natural versus human-induced landscape influences on water chemistry parameters. Landscape characteristics were classified at three spatial scales (sub-catchment above sample site, 100 meter riparian buffer, and a two kilometer stream reach) above 11 sampling points over two seasons (fall/winter, spring/summer). Preliminary results revealed that natural landscape features such as soil type, geology, and slope are strong predictors of stream water chemistry at the sub-catchment scale, while land use is strongly associated with local stream reach variation. Land converted to urban and row crop usage in local riparian corridors were less than 10 %, indicating that karst subtropical systems may be particularly sensitive to land cover change.

Group living in a prey species is commonly considered to benefit individuals by decreasing the risk of predation, but studies seeking associations between grouping behavior and declining predation risk often find little to no relationship. Alternatively, grazing herbivores may benefit from grouping by increasing efficient use of available forage. A general plant-herbivore interaction model assuming a fixed number of grazers and no intraspecific behavioral effects is being developed to assess whether grouping can result solely in response to forage biomass heterogeneity. The model is built as a cellular automaton that divides a large area into a regular grid of spatially discrete cells that are permitted to exist in one of a finite number of predetermined states, and the state of an individual cell at time t may vary in response to the states of the surrounding cells. Cells may thus be considered patches that vary in forage biomass across a larger meadow. Grazers deplete the available resources uniformly and move to an adjacent patch based on the quality of the resources in relation to nearby patches. Preliminary model output indicates that forage biomass does not directly prompt individual grazers to aggregate, but grazers that come together by chance are more likely to remain in close proximity to more efficiently exploit resources. These results suggest that currently observed patterns of grouping may be explained by resource exploitation in systems where traditionally recognized benefits to grouping are not observed. Future projections for this research include quantifying the gains in fitness from group foraging versus anti-predation effects, and examining forage-mediated grouping as an evolutionarily stable strategy.

Digesta load is positively correlated to organ weight in herbivorous rodents but it is unclear whether a correlation exists in ruminants. Fluctuations in digesta load presumably accommodates for changes in the animals energetic needs. We tested whether there was a positive correlation between digesta load (wet weight of rumen-reticulum contents) and organ weight of the rumen-reticulum in white-tailed deer (Odocoileus virginianus). Data were collected in Octobers 2006-2008, at the Mason Mountain Wildlife Management Area, Mason County, Texas. There was a positive correlation between precipitation and quality of forage. Because of this correlation, precipitation was measured throughout the study. Precipitation measurements were below the annual average during 2006 and 2008, and were above average for 2007. White-tailed deer were stocked in a 214 ha enclosure in February-March, 2006-2008, and were sacrificed in October. Body weights, digesta load, empty rumen-reticulum weights, and liver weights were measured. The liver weights were measured since liver weights reflect metabolic workload. Findings suggest that in a year with above average precipitation animals had heavier body weights, lighter liver weights, and lighter empty rumen-reticulum weights than in the two other years of drought. Digesta load progressively increased from the first to the third year. Weight of the rumen-reticulum organ did not coincide with digesta load as found in rodents.

Biofilms are the communities of bacteria encased within extracellular matrix which helps them to survive during adverse environmental situations. In the present study, we demonstrated that bacterial biofilms can act as a potential reservoir for largemouth bass virus (LMBV), a model eukaryotic virus which has no obligation to be associated with biofilms. LMBV, a member of family Iridoviridae is one of the naturally occurring fish viruses which cause fatal disease of largemouth bass (Micropterus salmoides) without any definite source of origin. Glass fibers were incubated with a mixture of different dilutions of LMBV stock of known titer and broth culture of Pseudomonas fluorescens ATCC13525, a naturally abundant bacterial strain. Using LMBV288F (5’-GCGGCCAACCAGTTTAACGCAA-3) and LMBV535R (5’-AGGACCCTAGCTCCTGCTTGAT-3’) primers, LMBV was detected in lab grown biofilms. Real Time PCR was able to quantify a maximum 6.22% of total LMBV in the adjacent bulk environment incorporated within biofilms following the SYBR Green method. The results also indicated that LMBV associated with lab grown biofilms is directly correlated to the LMBV concentration in the adjacent micro-environment. Real Time PCR could detect 100 fold less LMBV copy number than conventional PCR. Epifluorescent microscopy of biofilms grown in presence and absence of LMBV did not show any structural differences. The LMBV recovered from biofilms were further observed under transmission electron microscope (TEM) followed by negative staining by phosphotungstinic acid (PTA) and undergone a series of infectivity test following the TCID50 method. The later indicates that the LMBV isolated from biofilms are still infective. In a separate experiment, natural biofilm samples were collected from 4 different ponds of A. E. Wood Fish Hatchery, San Marcos, Texas; all of which were screened negative for LMBV by PCR. However, biofilm samples were positive when incubated with corresponding pond water spiked with LMBV stock. This study demonstrates the importance of examining microbial and ecological niches as potential reservoirs in the control of viral diseases. Similar experiments with other target viruses and host bacterial strains would determine if biofilms are reservoir for pathogenic viruses.

Although attending college may be viewed as a rite of passage to a majority of students, some students face unique challenges in their pursuit of a college degree in science. This study is an attempt to a gain better understanding of student performance and success in entry-level undergraduate science courses. Six variables-gender, ethnicity, high school GPA, high school science, school choice, and work hours were used as independent variables and course final performance as a dependent variable. The study attempted to explore two research questions: 1) What were the variables of performance in entry-level biology, chemistry, and physics? and 2) What were the predictors of success in entry-level biology, chemistry, and physics? Multiple regression models and logistic regression models were used to address the above two research questions. The results suggested that high school GPA had a strong association with students’ performance in entry-level science courses. Additionally, high school GPA and high school chemistry were the predictor variables for students’ success in entry-level biology and chemistry courses. Similarly, students’ performance and success in entry-level physics courses were influenced by high school GPA and high school physics course respectively. A further study with a longitudinal and quasi-experimental research design is recommended to assess students’ performance and success entry-level science courses.

Auxin, an essential plant hormone, plays a major role in plant growth and development. While Indole-3-acetic acid (IAA) is the major natural auxin found in plants, there are many synthetic chemicals with auxinic activity. While both natural and synthetic chemicals exhibit similar effects on plants, these chemicals are structurally different. Whether these structurally different chemicals function through similar molecular mechanisms is not known. Initial work in our laboratory indicates that picloram may function differently from other commonly known auxins. To identify genes that are associated with picloram response, we used a forward genetics approach to isolate Ethyl methanesulfonate (EMS) mutagenized Arabidopsis mutants that were resistant to picloram.

The objective of the current research is to characterize the Arabidopsis mutants, pic59 and pic115. The primary root growth of pic59 and pic115 exhibits differential responses to different auxins. While pic59 is highly resistant to picloram and indole butyric acid (IBA), and slightly resistant to 2, 4-D, it is sensitive to IAA. pic115 is highly resistant to 2, 4-D, slightly resistant to picloram and IBA, and sensitive to IAA. When tested with other phyto-hormones, primary root growth of pic59 and pic115 were resistant to the plant stress hormone abscisic acid (ABA).Expression of DR5::GFP transgene in response to auxin is impaired in pic59 and pic115 background suggesting that auxin-dependant gene transcription is affected in the mutants. Additionally, the degradation of AXR3NT-GUS recombinant protein is drastically altered in pic59 background. pic59 was mapped to a region of seventeen genes in chromosome V. As there are no currently known auxin-related genes in this genetic window, pic59 represents a novel gene associated with both auxin and ABA responses. pic115 was mapped to the north arm of chromosome II. Using candidate gene approach, mutation was identified recently. Results so far indicate the involvement of a novel regulatory mechanism in auxin signaling.

Survey data collected to describe characteristics of animal assemblages are important in developing management plans. Mammal, reptile, and amphibian sampling began in January 2008 at Palmetto State Park and the adjacent Ottine wetlands, Gonzales County, Texas to produce a current species inventory and estimates of species diversity. We compared the current data to results of a survey performed in 1958. A total of 486 animals (217 rodents, 207 amphibians, 62 reptiles) have been captured or observed representing 41 species (10 mammals, 7 amphibians, 24 reptiles). Data suggest that community composition has changed over the past 50 years shifting to a greater abundance of species that are suited to urbanization and heavy agricultural use. There appears to be substantial loss of amphibian richness with only 7 species detected compared to 15 species detected as recently as the 1950s. Reasons for changes in herpetile and mammalian assemblages, including extirpation and rarity of a number of species, historically present in the area can most likely be attributed to: heavy agricultural use, increased ground water use, invasive exotic species, and a series of severe droughts.

The Amazon molly, Poecilia formosa, is a gynogenetic fish of hybrid origin. Amazon mollies must mate with males of their parental species to initiate egg development, but inheritance is strictly maternal. Determining the nature of mate preferences of gynogens can help elucidate the evolution, maintenance, and inheritance of mating preferences via comparisons with parental species. To determine whether Amazon mollies show mating preferences based on direct benefits or sensory biases we measured the repeatability and consistency of mate preferences of Amazon mollies for males of one of their sexual hosts, sailfin mollies, P. latipinna. We found that Amazon mollies preferred larger males and this preference was maintained across three days of testing. Repeatability of the preference was low but females were consistent in their preference for larger males. These results support the hypothesis that Amazon molly mating preference is a result of a sensory bias for larger individuals in non-mating contexts.

Long-term studies are lacking on the response of rodent populations to drought in semi-arid environments. Stochastic rainfall in semi-arid ecosystems leads to fluctuations in rodent populations. A boom-bust phenomenon has been observed in hispid cotton rat (Sigmodon hispidus) populations, a significant prey item of the bobcat (Lynx rufus) in Texas. Studies in Texas suggest rodent populations begin to recover from drought within 3-months after a significant rainfall event. Bobcats are wide-ranging and abundant in Texas and have the potential to be used in scientific research as a model for wild cat response to environmental variation. Few studies have detailed the response of wild cats to declining prey populations as a result of drought. Understanding this relationship may provide insight on the response of sympatric felids (i.e., ocelot [Leopardus pardalis]). We compared rodent population data from local research and scientific literature to Modified Palmer Drought Index and bobcat hunter harvest in Texas. We propose a bobcat-prey-drought model where drought induced decline in prey availability causes reciprocal bobcat decline.

Astrocytes in the central nervous system (CNS) have numerous roles including wound healing. Upon injury to the CNS, astrocytes exhibit hypertrophy marked by an increased production of the intermediate filament (IF) protein GFAP, and hyperplasia (cell division) which is preceded by phosphorylation of the nuclear IFs, lamins. Previous studies have shown monoclonal antibody (mAB) J1-31 recognizes a phosphoepitope found on lamin in astrocytes, making mAB J1-31 an appropriate marker for astrocytes entering the reactive state. To test the hypothesis that a cAMP-mediated intracellular pathway is involved in the conversion of astrocytes from the quiescent to reactive state, forskolin, a stimulator of adenylyl cyclase, and inhibitors of cAMP downstream targets, were added to confluent cultures of F98 cells (rat astrocytes). The cells were fixed and immuno-labeled with mAB J1-31. Measurements of lamin labeling intensity due to mAB J1-31 were determined and compared among the control and treated groups, and also to lamin labeling by ABs not specific for phosphoepitopes. Induction of cAMP production caused a 2-fold increase in mAB J1-31 labeling but not an increased labeling with the non-phospho anti-lamin AB – thus implicating cAMP in driving lamin phosphorylation as a precursor to mitosis (hyperplasia). Inhibition of the known cAMP downstream target, protein kinase A did not abolish the forskolin effect, but blocking l-type Ca+2 channels did. To test for the presence of cAMP-gated calcium channels in F98 cells, a calcium-sensitive fluorescent probe (BAPTA-Oregon Green) was loaded into live F98 cells which were then imaged in real time before and after addition of forskolin using confocal microscopy. The results showed that Ca+2 induced “flashes” occur in the cytoplasm near the plasma membrane of F98 cells in response to forskolin. Confirmation of this result and inhibitor studies are in progress.

We compared dove presence and/or absence of white-winged (Zenaida asiatica) and mourning doves (Z. macroura) in south Texas to the 2001 National Land Classification Database (NLCD) categories. Our objective was to determine which, if any, category (or categories) from the NLCD classification schemes could be used to predict species occurrence. Our study was conducted between 15 May and 15 August of 2007 and 2008. We used point transect methodology and Program DISTANCE to determine density estimates of white-winged and mourning doves at 236 points encompassing 744 observations. Land classification categories were quantified using geographic information systems (GIS). Each point and a 300 m buffer were projected on NLCD maps. We then used GIS to determine proportions of each land classification type within the buffer area. Randomization tests were used to compare proportions of land cover types present at points with and without doves. Our results indicate that white-winged dove occurrence in south Texas is strongly influenced by areas categorized as urban, while mourning dove showed a strong relationship to crop and rangeland habitat types.

The ability of birds to adapt to extreme weather events can influence survival of species at high latitudes. An unusually cold and wet weather event occurred in San Marcos, Texas in January 2007. This cold spell resulted in large numbers of dead Cave Swallows that were collected, weighed and measured. Measurements of these birds indicated swallows roosting along Interstate underpasses during the cold spell had smaller frames yet were heavier than those found in a parking garage. Thermometers placed at the two roosting site types revealed that the underpasses were approximately 5 C degrees colder than the parking garage site during the coldest part of the day. Precipitation and cold temperatures can limit food supply and foraging opportunities for swallows causing starvation. However, extreme temperatures may have acted more vigorously on Cave Swallows at the colder underpasses. Higher post-mortem body condition (weight/size) may suggest death before starvation. Successive generations of survivors exhibited larger body size, but shorter wing chords and tail lengths as Bergman’s rule and Allen’s rule would predict.

Estimating the size of a population, or abundance, can be expensive and labor intensive. A less expensive option is estimating occupancy, or the percent of an area in which a species is present. A drawback to estimating occupancy is that information about population abundance is lacking, and that is important to many management objectives. We studied whether the relationship between occupancy and abundance is linear, because then it should be possible to estimate abundance from estimates of occupancy. An issue with estimating occupancy and abundance is accounting for imperfect detection. We conducted songbird point counts on Camp Swift, a Texas Army National Guard training site, in fall 2007 and winter 2008, to estimate occupancy and abundance using estimators that also accounted for imperfect detection. We had 100 points established 200 meters apart that were sampled 3 - 4 times per season. We estimated occupancy and abundance (using binomial mixture models) with program PRESENCE. We modeled the parameters to account for various sources of error, and models were chosen based on their Akaike Information Criterion values. Contrary to expectation we detected a positive nonlinear threshold relationship between occupancy and abundance estimates in both seasons. Although there is a predictable relationship between occupancy and abundance, that it was nonlinear precluded straightforward estimation of abundance from occupancy.

Variation in traits related to resource use, such as host plant use in phytophagous insects, may provide the circumstances under which disruptive selection takes place. Herbivorous insect populations which undergo a host shift to a different plant resource may experience new selective pressures that, if overcome, can lead to adaptation on the new host and host race formation. These host races have been described as the beginning stages of speciation. The current study investigates the role of ecological factors to the process of reproductive isolation among populations of the juniper hairstreak butterfly, Mitoura gryneus in Texas. Mitoura are closely associated with their particular host plants (Cupressaceae) and exhibit host plant fidelity: males lek and mating occurs on host trees, and females oviposit and larvae develop exclusively on the hosts. Evidence of specialization to the host plants, in the form of female oviposition preference and larval performance, is experimentally evaluated. In addition, population genetic analyses which will examine patterns of geographic genetic variation are conducted. If host plant fidelity and assortative mating leads to reproductive isolation according to host plant, Mitoura populations using alternate hosts will have significantly greater genetic differentiation than populations using the same host. The Mitoura system, in which host-associated populations occur both allopatrically and sympatrically, provides a powerful opportunity to examine the role of ecological factors as drivers of reproductive isolation and population differentiation.