The purpose of this project is to produce a complete and thorough notebook that may be used to supplement laboratory coursework. Its intent is to be used primarily by the students to aid them in understanding background information and the proper laboratory procedures involved in various types of experiments. The laboratory notebook is a summation of all the experiments and procedures used in the six-credit hour Advanced Microbial and Molecular Biology (BIOL 5160) course offered during the summer semester at the University of North Texas. This class is a team taught effort by Professors O'Donovan and Kunz. The course is constructed as an intensive practice exercise to teach the student about gene mutations, biosynthetic pathways, preparation and analysis of plasmid DNA, and many other topics included in the notebook.
The study investigated the ability of an extracurricular program to influence environmental responsibility of sixth and seventh graders. The Children's Environmental Attitude and Knowledge Survey (CHEAKS) was evaluated for appropriateness in assessing the worth of this particular environmental education strategy emphasizing water quality fieldwork and technology. CHEAKS is designed with psychometric reliability and validity that may be used in comparing disparate programs. Wilcoxon two sample tests were used to analyze data gathered from two student groups; one participated in an "Enviro-Mentals Club"; the other received no treatment. Analysis showed no significant change in environmental attitudes between groups, but did show significance (p <= 0.05) in environmental knowledge growth. Therefore, the investigated program had marginal success in influencing environmental responsibility.
No apparent repression of pyr gene expression in Pseudomonas aeruginosa is observed upon addition of exogenous pyrimidines to the growth medium. Upon introduction of the subcloned Escherichia coli pyrBI genes for aspartate transcarbamoylase (ATCase) into a P. aeruginosa pyrB mutant strain, repression was observed in response to exogenously fed pyrimidine compounds. The results proved that it is possible to bring about changes in pyrimidine nucleotide pool levels and changes in transcriptional regulation of gene expression as a result. Thus, the lack of regulatory control in P. aeruginosa pyr gene expression is not due to an inability to take up and incorporate pyrimidine compounds into metabolic pools, or to an inability of the RNA polymerase to respond to regulatory sequences in the DNA but is probably due to a lack of specific regulatory signals in the promoter of the genes themselves.
A study of the biology of Tropisternus lateralis, a hydrophilid beetle, was conducted during the flood period of a single playa on the Southern High Plains of Texas from early June 1995 through early September 1995. Mechanism of colonization, tolerance/avoidance to drought, larval density, and secondary production were analyzed. T. lateralis colonized playas from surrounding aquatic habitats and avoided drought through aerial dispersion. Once in the playa, larval density increased over time. Secondary production was 1.31 g/m2/.25 yr. In addition, aquatic Coleoptera diversity was studied in seven playas on the Southern High Plains of Texas. A total of twenty three species were identified from the study region. Nine species not reported in playa literature were identified.
Observed and expected heterozygosity (H) levels for ten electrophoretic blood marker loci and expected H for seven red blood cell (RBC) anitgen/antibody loci were examined for 20 years in American Standardbred and 30 years in American Saddlebred horses. Standardbreds were classed by gait, Trotter and Pacer, and evaluated separately in most analyses. 4,404 Trotters and 12,271 Pacers were found to have statistically highly significant losses of mean total observed H through time for the ten electrophoretic loci (P<0.005), although in Trotters the loss was more extreme (P<<0.001). Loss of H in 5984 Saddlebreds was not significant (P=0.259). Correlations of RBC expected H through time showed decreases in all three groups.
Two measures which indicate statistical serial dependence were evaluated. The n-dimensional Average Stored Information index (ndASI) is a measure of conditional information, which compares the entropies of higher order conditional distributions to estimate average statistical serial dependence. The generalized ranked joint interval histogram (RJIH-o) is a new nonparametric graphical analysis method. It extends the joint interval histogram by depicting longer interval sequences and can be interpereted precisely analagously to the joint interval histogram. The generalized ranked joint interval histogram correctly represents independence in a Poisson process model and statistical serial dependence in a directionally reinforced Markov model. The generalized ranked joint interval histogram correctly depicts the underlying periodic and strange attractors in a standard map model. Both measures can be used to effectively analyze interspike interval sequences from spontaneous neurophsyiological activity effectively.
Experiments were performed to assess the suitability of Rhabditis pellio, a nematode found in earthworms, as a challenge organism for use in development of a biomarker assay to determine the potential of chemicals to suppress the immunocompetence of the non-specific immune system. To accomplish this goal, information on the life cycle of R. pellio was determined; including effects of incubation time and temperature on growth rates; along with information on the immune response elicited in the earthworm, Lumbricus terrestris. Immune parameters measured were coelomocyte migration toward and attachment to R. pellio larvae and adults. Preliminary background information showed that R. pellio has potential as a challenge organism for development of a biomarker assay.
The effects of moderate workload exercise at different pedal rates on circulatory and respiratory parameters were studied. Five subjects performed seven discontinuous constant-load cycle ergometer tests of 30 minutes duration at pedal rates of 40, 50, 60, 70, 80, 90 and 100 rpm. Oxygen uptake and carbon dioxide production were determined by standard open circuit spirometry, while heart rate was recorded by electrocardiograph. The CO₂ rebreathing procedure was administered during the exercise bout in order to determine cardiac output. Blood pressure was determined for each test, and total peripheral resistance was calculated. The findings indicate that progressive increases in pedal frequency during discontinuous constant-load cycle ergometry produce progressive increases in cardiovascular, respiratory and metabolic responses and a decrease in gross exercise mechanical efficiency. The results indicate that oxygen uptake, cardiac output, heart rate, ventilation and arterial-venous oxygen difference increases curvilinearly as pedal rate increases, possibly as a result of increases in recruitment of muscle fibers and/or muscle groups. These findings suggest that circulatory and respiratory responses are due to "central command" which sets the basic efferent response pattern. However, this effector pattern is modulated by afferent input originating from the legs during progressive increases in pedal rate.
This study proposes the classification of the toolmark under the heads of zipper teeth as a subclass characteristic as outlined by the Association of Firearm and Toolmark Examiners (AFTE). Two separate cases in which zipper teeth were found at crime scenes prompted this study. Brass zipper teeth manufactured by YKK were taken from 20 pairs of jeans and studied using a Reichert comparison microscope at 4X power. Photographs were taken and over 750 comparisons made. It was found that the toolmarks on each side on the 20 zippers were unique and independent of all other sides. The observations made in this study indicate that classifying zipper teeth toolmarks as a subclass characteristic is valid.
Research estimated toxicity of refuse-derived fuel fly ash (RDF-FA) on two earthworms species, Lumbricus terrestris and Eisenia foetida. Specific objectives were to: (1) Compare their 14-day LC50s under light and dark conditions; (2) separate toxicity due to osmotic, pH and physical factors from that of heavy metal contaminants; (3) compare relative differences of artificial soil and commercial soil as exposure media for evaluating toxicity to earthworms. The 14-d LC50s for L. terrestris in dark and light were 57.0 and 48.34 % RDF-FA, and 59.25 and 41.00 % RDF-FA for E. foetida using artificial soil. All of the toxicity resulted from heavy metals within the RDF-FA. Using L. terrestris, the LC50s for artificial soil and commercial soil were 52.30 and 64.34%.
This research compares LC50 and LD50 of earthworms, Lumbricus terrestris and Eisenia foetida exposed to cadmium nitrate and chlordane using 48-h contact filter paper (FP) and 14-d artificial soil (AS) protocols. Both LC50 and LD50 showed that chlordane was more toxic than cadmium in both species regardless of the exposure. The reference toxicant 2-chloroacetamide using the standardized 48-h FP exposure was used to assess the general response of the earthworm prior to toxicity experiments. A glucose test was developed as an internal standard to assess homogeneity of mixtures among both replicates and dilutions. Accuracy of dilutions is assessed by the slope of a regression line relating nominal dilution to observed internal standard concentration. Precision of replicate preparation is assessed by among replicate variance.
The enzyme that catalyzes the committed step in pyrimidine biosynthesis, aspartate transcarbamoylase, has been compared in selected endospore-forming organisms and in morphologically similar control organisms. The ATCases and pyrimidine salvage from Sporosarcina ureae, Sporolactobacillus inulinus, Lactobacillus fermentum, and Micrococcus luteus were compared to those of Bacillus subtilis. While the ATCases from Sporosarcina ureae, Sporolactobacillus inulinus, and L. fermentum were found to exhibit characteristics to that of Bacillus with respect to molecular weight and kinetics, M. luteus ATCase was larger at approximately 480 kDa. Furthermore, pyrimidine salvage in Sporosarcina ureae and M. luteus was identical to those of B. subtilis, while pyrimidine salvage of Sporolactobacillus inulinus and L. fermentum resembled that of the pseudomonads.
Two years before impoundment, the trophic status of Lake Ray Roberts was predicted by applying the total phosphorus input into the Organization for Economic Cooperation and Development (OECD) eutrophication model. Predicted mean summer epilimnetic (MSE) chlorophyll a of Elm Fork arm, Isle duBois arm and Main Body were in the eutrophic category of the OECD model. Observed MSE chlorophyll a two years after impoundment of Elm Fork arm, Isle duBois and Main Body had not reached their predicted means and were at the mesotrophic-eutrophic boundary of the OECD model. Six years after impoundment, observed MSE chlorophyll a for Main Body, was closer to its predicted mean and in the eutrophic category of the OECD model. Six years after impoundment, Elm Fork arm was the most productive area of Lake Ray Roberts. Observed means of chlorophyll a, total phosphates, suspended solids and turbidity were often highest in the Elm Fork arm. Wastewater effluent from Gainesville and Valley View, TX, had an impact on productivity in Elm Fork arm.
A contaminant fate and transport computer model, Bioplume II, which allows simulation of bioremediation in ground water systems, was used to compare the effects of 11 remediation scenarios on a benzene plume. The plume was created in three different hydrogeologic settings from the simulation of an underground gasoline storage tank leak.
In order to gain a better understanding of this microorganismand its role in human pathogenesis, a physical map of Moraxella catarrhalis type strain ATCC25238 was constructed using pulsed field gel electrophoresis (PFGE) in combination with Southern hybridization techniques. Restriction endonucleases Not I, Rsr II, and Sma I were used to digest the chromosomal DNA. An overlapping circular map was generated by cross-hybridization of isolated radiolabeled fragments of Moraxella catarrhalis genomic DNA to dried PFGE gels. The number and location of the 16S and 23S ribosomal RNA genes were determined by digestion with l-Ceul enzyme and by Southern hybridization. Virulence-associated genes, the gene for β-lactamase, and housekeeping genes were also placed onto the physical map.
Larval, pupal and adult samples of Culoptila cantha, from a large riffle of the Brazos River in north-central Texas from January, 1995 to March, 1997, indicated a predominately trivoltine cycle during both years; the over-wintering generation spanned 6-7 months and warm-season generations spanned 2-3 months. Eggs, larvae of all instars, larval cases, case reconstruction progression and behavior, pupae, and adults are described.
With numerous bioassessment methodologies available, a regional protocol needs to be developed to ensure that results are comparable. A regional assessment protocol was developed that includes collecting five benthic macroinvertebrate samples, identifying organisms to genus, and calculating the following metrics: Number of Taxa, Total Number of Individuals, Simpson's Diversity Index, Shannon's Diversity Index, Percent Contribution of Dominant Taxa, Hilsenhoffs Biotic Index, and Percent Contribution of Dipterans. Once the protocol was developed, it was used to assess the Bayou Chico tributaries and watershed. All three tributaries had been significantly impacted by human activity as had the watershed as a whole. This study indicates that a regional protocol could be developed and is appropriate for biomonitoring at the watershed scale.
Previously, Whipp et. al. (J. Appl. Physiol.: Respirat. Environ. Exerc. Physiol. 50(1):217-221, 1981) demonstrated the feasibility of determining four parameters of aerobic function, identified as maximum oxygen uptake (μVO_2), VO_2 at anaerobic threshold (θan), the time constant for oxygen uptake kinetics (rVO_2) and work efficiency (η), using a short duration ramped bicycle ergometer exercise test. Because of the importance of being able to measure these parameters on a variety of measurement instruments a short duration ramping treadmill protocol has been developed. The ability of this protocol to determine the four aerobic parameters has been validated against conventional methods. The results of this investigation indicate that μVO_2, θan, rVO_2 and, η may be obtained from a single, short-duration ramping treadmill test.
An in vitro system of generating protoplasts from their callus cultures was established. The friable callus was more productive in terms of producing protoplasts than the green compact callus. The concentration of the various cell wall degrading enzymes had an effect on the viability of the protoplasts in the medium. The protoplast system developed from the experiments was stable and could be used for the transformation experiments of Albizia lebek and for other plant improvement practices.
A novel Gram negative, capsule-forming bacterium was previously isolated in Dr. G. Roland Vela's laboratory. The distribution of this bacterium in soils from various locations was investigated. Soil samples from 188 locations around the world were examined. Isolates of the bacterium were obtained from 50 of these soils, with 48 of the isolates found in soils from the southwestern United States and northern Mexico. This suggests that this region is the natural habitat of the bacterium. The other two isolates were obtained from Madrid, Spain and Taipei, Taiwan. None were found in soils from South America or Australia. A lack of variation in morphology and physiological properties in the isolates suggests that a homogeneous population exists, even from widespread geographical locations.
In the United States, biodiversity impact assessment has historically received little attention. Responding in 1993, the Council on Environmental Quality (CEQ) released guidelines on incorporating biodiversity into environmental impact assessment under the National Environmental Policy Act of 1969. The objectives of the study here were to identify the level of documentation of biodiversity impact assessment in sample Environmental Impact Statements (EISs); identify whether in the years following the release of 1993 CEQ guidelines any significant changes have taken place in assessment of biodiversity; identify deficiencies, and if the need exists, formulate appropriate recommendations and approaches for addressing biodiversity in EISs. The study involved a systematic review of 30 EISs published since the release of CEQ guidelines, and five EISs published prior to it. The review involved answering a series of standard questions, which attempted to ascertain the level of biodiversity impacts included in each impact statement. Trends in approaches to biodiversity impact assessment were investigated and deficiencies summarized. The analysis resulted in a series of recommendations for improving the manner in which biodiversity impact assessment can be approached.
Since the introduction of management practices by the Forest Service to stabilize red-cockaded woodpecker (RCW) populations, the number of cavity trees killed by southern pine beetles (SPB) has increased. A model of the landscape ecology of RCW and SPB in the Homochitto National Forest was created using data collected from the Forest Service and Global Atmospherics. The conclusions of the study were that the RCW and SPB utilize the same type of habitat and the stand hazard maps are an accurate means of determining the locations of SPB infestations. The functional heterogeneity maps created for the SPB and RCW would be useful predictors of future occurrences of either species if complete data were obtained.
Culture health of Ceriodaphnia dubia was evaluated for organisms cultured using all combinations of three foods and three waters. Criteria used to assess health of cultures included adult and neonate weights, time required to produce first broods, neonate production, adult survival, and resistance to hexavalent chromium. Diet/water combinations which produced the most neonates were not found to produce adults which were more resistant to chromium than those which produced fewer neonates. Of those evaluated, a diet of Selenastrum capricornutum and a yeast-trout chow-cereal leaf mixture was best for culturing and testing Ceriodaphnia. The best synthetic water tested was a mixture of nine parts reconstituted hard water and one part bottled mineral water.
Copper exposures of 400 μg/L for 5,10 and 15 days resulted in no significant differences in antibody titers of largemouth bass, Micropterus salmoides injected with Aeromonas hydrophila compared to control-injected bass. Twenty days of exposure did significantly increase titers. The control group had significantly lower antibody titers than either control-injected or copper-exposed.
Acute effects of a pulsed external electric field (PEEF) at 20 V/cm and a d.c. EEF at 90 V/cm on light transmittance in an isolated compound crayfish nerve was measured. In a third series, the nerve was pre-treated with the Na+ channel blocker tetrodotoxin (TTX). A PEEF produced an irreversible increase in the variation of light transmittance in normal nerves but a reversible increase in TTX treated nerves. This data was statistically insignificant. The d.c. EEFs produced a reversible and statistically significant enhancement of variation in light transmittance in both untreated and TTX-treated nerves. The findings may be due to either (1) an alteration in the ion/fluid flux within the nerve or (2) a physical alteration of protein molecules in the membranes.
Using a rat model, the effects of a single dose or six to twelve months of daily oral administration of ethanol on the immune system were determined. The rats were challenged with sheep red blood cells after the various dosing periods to elicit an immune response. Immune system responsiveness was determined by means of white blood cell counts and differentials, antibody titers, and T-cell numbers. No deleterious effects of the ethanol on the immune response were seen, while the female alcohol-fed rats showed a significant increase in T-Cell numbers, white blood cell counts, and lymphocytes over the sham group.
The effects of single injections and daily oral administration of ethanol on plasma levels of ACTH, beta endorphin, and corticosterone in response to cold stress were examined. The long-term experimental animals were given 0.25 ml of 28% ethanol or water orally once a day, five days a week, for fourteen months. Plasma levels of ACTH, beta endorphin, and corticosterone were lower in alcohol-treated rats as compared with water-treated rats when exposed to cold stress. The effects of a single injection of ethanol significantly elevated plasma levels of all three hormones. Mortality in sham-treated males was higher than ethanol-treated.
This study was designed to determine if impingement and entrainment by cooling water intake at the Comanche Peak Steam Electric Station have an adverse impact upon the Squaw Creek Reservoir fish population. The yearly impingement of fish was estimated to be 262,994 of 14 species. The threadfin shad (Dorosoma petenense) accounted for 96% of this total. Entrainment of eggs and larvae for a five month period was estimated to be 15,989,987 and 42,448,794 respectively. Two fish population studies were performed on Squaw Creek Reservoir to help assess impact. It was determined that the losses due to impingement and entrainment have no adverse impact upon the fish population of Squaw Creek Reservoir.
The City of Denton Pecan Creek Wastewater Treatment Facility has periodically failed effluent toxicity testing. A Toxicity Identification Evaluation has determined that Diazinon in the effluent is contributing to the observed toxicity. Chlorpyrifos is also implicated as a factor. The City of Denton constructed a half acre experimental wetland to remove Diazinon related toxicity. Results from spiking and microcosm experiments indicate that the wetland can reduce the Diazinon.
Six reagent waters, eleven diets, and two culture sizes were evaluated for culturing C. dubia. Different filtration techniques were used to prepare the reagent waters. The eleven diets were comprised of two algae augmented with eight supplements. Reproduction and growth were assessed to discern differences among C. dubia raised in mass cultures and cultured in individual cups, during which, bacterial population densities, lipid, protein, and carbohydrate concentrations of the diets were measured. Results showed that a glass-distilled, carbon filtered, deionized reagent water and a Selenastrum capricornutum- Cerophyl® diet were optimum for culturing. Mass culturing supported the highest reproduction and growth, while no correlation was found between nutritional measurements and production.
There is a transition nationwide on the analysis of forensic evidentiary stains containing biological material from traditional serology to Polymerase Chain Reaction (PCR) methodologies. The increased sensitivity of PCR, the limited number of alleles at each locus, and the necessity of producing unambiguous data for entry into the FBI's Combined DNA Index System make this study of extraction procedures of utmost importance. A "single tube" extraction procedure for blood stains collected onto FTA™ paper and a modified differential nonorganic extraction method from spermatozoa containing mixed stains were analyzed and compared. The extraction success was evaluated by amplification and typing of the amplified fragment length polymorphism, D1S80. These modifications of the nonorganic method utilized gave an improved separation of the spermatozoa-containing mixed stains.
The GABAergic system in adult sensory cortex is affected by sensory deprivation, but little is known about how this predominant inhibitory system is affected during ontogeny. The present study investigates developmental effects of whisker trimming on GABAa receptors in rat barrel cortex. Rats trimmed for 6 wk beginning at birth and adulthood showed similar decreases in [3H]muscimol binding in deprived relative to non-deprived barrels, suggesting absence of a critical period.
The following is a complete syllabus for a college level genetics course. The syllabus contains lecture outlines and notes for each chapter, along with a list of transparencies needed. The quizzes and exams are prepared and placed at the beginning of the syllabus. The beginning of the course will consist of a lecture to introduce the students to the basics of genetics, followed by many applications of genetics. The process of cell division will be mastered by the students, as well as Mendelian genetics, quantitative genetics, chromosome mapping, and inheritance. The replication, synthesis, and organization of DNA are also discussed within the lectures. The final topics that will be covered using this syllabus are genetics of cancer and immunology and population genetics. These topics are essential for a detailed genetics course. The syllabus is written in great detail, and will require a full semester to be completed. The book used in association with this syllabus is Essentials of Genetics by William S. Klug and Michael R. Cummings.
Ascaris suum were exposed to a number of stressors, including heavy metals and both high (40°C) and low (18°C) temperatures. The 70kD and 90kD heat shock proteins (HSPs) in the different A. suum tissues were analyzed by Western blot and quantitated by Macintosh Image Program.
To further understand the ATCase/DHOase bifunctional complex formed in Streptomyces, the genes encoding these and other pyrimidine enzymes were identified and characterized. Polymerase chain reaction (PCR) was utilized in this effort. Primers were constructed by selecting conserved regions of pyrimidine genes from known gene and protein sequences of a wide variety of organisms. These sequences were then optimized to Streptomyces codon usage. PCR products were obtained from internal sites within pyrimidine genes and also from primer combinations of different genes. The size, orientation, and partial sequence of the resulting products shows that Streptomyces has a gene organization of pyrR followed by pyrB, pyrC, carA, carB, and pyrF in an operon similar to that found in other Gram-positive bacteria.
Objective was to assess the toxicity of chromium (Cr) contaminated soil (CS) using the earthworm Lumbricus terrestris. Specific aims were to determine: (1) survival (LC50); .(2) immunotoxicity as indicated by lysozyme activity, coelomocyte counts, secretory (SR) and erythrocyte rosette (ER) formation, and phagocytosis; and (3) compare effects of CS exposure with those of Cr spiked artificial soil (AS) . CS Cr concentration was 8.78 mg/g with 98.2% being Cr^3+ and 1.8% being Cr^6+. Using 14 d AS protocol the LC50 was 6.49% CS: AS mixture. CS concentrations of 0.5, 1.0, 2.5 and 5.0% were sublethal, whereas 6.25, 12.5, 25, 50 and 100% CS were lethal. Sublethal exposure caused no immuno- modulation. Exposure to 50% CS: AS mixture for 5 d caused reduced SR and ER formation. Exposure to AS spiked with 0.27% Cr for 5 d resulted in immunomodulation equivalent to 50% CS: AS mixtures. Results indicated the CS to be acutely toxic.
The 96-hr LC50 of cyfluthrin in Pimephales promelas ata temperature of 23*C and a pH of 8 was 1.08 g/L. The toxicity of cyfluthrin was inversely related to temperature and pH. A temperature of 10*C and a pH of 6 significantly decreased the 96-hr LC50 to 0.009 gg/L. Likewise, sublethal exposures to cyfluthrin significantly affected the fathead minnow's ability to tolerate high and low temperatures. Cyfluthrin compromised the fathead minnow's lower temperature tolerance (CTMin) by 60C and the upper temperature tolerance (CTMax) by 20C. Although cyfluthrin may not be present in the environment in large amounts due to its physical and chemical properties, small concentrations ( g/L) may adversely affect fish populations.
Ancient peoples did not distinguish between philosophy, religion, and science. Scientific truth did not exist apart from divine truth. Any new idea, finding, or theory was assimilated into a monolithic mythological structure. This is one of the causes of the underestimation of ancient science: it is always packaged in a myth - the method of preserving information in an oral culture. The mythological medium allowed the preservation and dissemination of hard-won, empirical, scientific knowledge through generations of preliterate peoples. The context for mythological memorization, or simply tradition, needed to be easily and naturally acquired. The ideal context was the anthropomorphic context, the ontogenic context. This is the Grand Allegory - the anthropomorphization of information. Biomyths are essentially biological texts allegorized in esoteric language.
The effects of the inhibitory neurotransmitters gammaamino butyric acid (GABA) and glycine were characterized on spontaneous activity recorded from mouse spinal cord cultures. The GABA concentration which completely inhibited burst activity was chosen as a quantifiable measure of culture drug response and was used to 1) assess interculture and intraculture variability, 2) determine the influence of culture age and initial activity on GABA responses, and 3) compare the GABA responses between networks obtained from whole spinal cord and ventral half spinal cord. Results showed that 1) no significant variability existed either within or among cultures, 2) the initial culture activity directly affected GABA responses, 3) the culture age had no effect on GABA responses, and 4) there was no significant difference in GABA responses between the two spinal cord tissues.
The life history and ontogenetic microhabitat change of Mayatrichia ponta Ross were investigated in Honey Creek, Turner Falls Park, Murray Co., Oklahoma, U.S.A. from August 1994 to August 1995. The shape of larval cases changed from a small cone to a cylinder. M. ponta had an asynchronous multivoltine life history with considerable cohort and generation overlap; five generations were estimated. The development rate was reduced in winter. The winter generations of M. ponta had wider head capsule widths (136-165 μm) than summer generations (121-145 μm). The sex ratio of adults was 1.43 ♂ : 1 ♀. Fecundity ranged from 46 to 150 eggs/female. Fifth instar larvae and pupae aggregated on the bottom side of substrates. Early instars were distributed evenly on all sides of substrates. General patterns of ontogenetic microhabitat shift in aquatic insects are categorized as flow mediated, flow independent, and population interactions and other resources mediated.
Spontaneously active primary cultures obtained from dissociated embryonic medial medulla tissue were grown on microelectrode arrays for investigating burst patterns and pharmacological responses of respiratory-related neurons. Multichannel burst rates and spike production were used as primary variables for analysis. Pacemaker-like neurons were identified by continued spiking under low Ca++/high Mg++conditions. The number of pacemakers increased with time under synaptic blocking medium. Sensitivity to CO2 levels was found in some neurons. Acetylcholine changed activity in a complex fashion. Curare, atropine and gallamine modified ACh effects. Eserine alone was ineffective, but potentiated ACh-induced responses. Norepinephrine caused channel-specific increases or decreases, whereas dopamine and serotonin had little effect at 30 μM. GABA and glycine stopped most spiking at 70 μM. Developmental changes in glycine sensitivity (increasing with age) were also observed. It is concluded that pacemaker and chemosensitive neurons develop in medial medulla cultures, and that these cultures are pharmacologically histiotypic.
The phylogenetics of eight species of the Peromyscus truei and P. boylii species groups from 15 populations were analyzed based on mitochondrial DNA sequence differentiation, using 13 hexanucleotide specific restriction enzymes. P. difficilis, P. nasutus, and P. attwateri were found to be members of the same clade. P. leucopus was not found to be closely related to any of the species of the boylii or truei species groups. Phylogenetic interpretations for the remaining species differed based on Wagner and Dollo parsimony analyses. P. true appears to be most closely related to P. gratus based on Wagner parsimony and the phenetic analysis, while the relationship of P. gratus to other species could not be resolved based on Dollo parsimony.
Translocation of a 17.1 kilobase region of the OCT plasmid encoding mercury resistance (mer) in Pseudomonas putida was shown to occur in a recombination-deficient host with plasmid PP1 serving as a recipient replicon. The frequency of transposition in Pseudomonas was estimated at 10^3 -10 -^2, but undetectable in Escherichia soli. ' DNA comprising all of mr as well as subregions there of were cloned and subjected to DNA sequence analysis. Like other transposons, mer was found to contain inverted repeat sequences at its termini. These were similar to, but not identical to the inverted repeat structures found in the prototypical mercury resistance transposon Tn501 from E. aeruginosa.
Traditional methods of teaching the laboratory course for Comparative Anatomy of the Vertebrates could be improved by applying current computer technology to construct an interactive, multimedial atlas of dissection. Five specimens used in comparative anatomy courses at most institutions were chosen as representative members of the Phylum Chordata: amphioxus, lamprey, dogfish shark, mud puppy, and cat. Specimens were dissected according to the modified method of Wischnitzer, 1993, and each stage was photographed with a Kodak DC120 digital zoom camera. These images were processed on a Power Macintosh 7600 computer with Adobe Photoshop v. 5.0. The atlas was constructed from these images using Macromedia Authorware v. 4.0.3. Each image contains a series of interactive objects that display a highlight and descriptive text as the cursor passes over each object.
Tetramethylthiuram disulfide (42-S Thiram), a carbamate fungicide was studied for its mutagenic potential on the germ cell stages of wild-type male Drosophila melanogaster. The mutagenicity was tested using the sex-linked recessive lethal assay (SLRL). Any lethals induced in the F2 generation were evidenced by the absence of wild-type males. Although there was an increase in mutation rates in the 42-S Thiram treated wild-type males over the control wild-type males, it was not significantly higher. According to the laboratory conditions in this preliminary study, tetramethylthiuram disulfide failed to produce mutagenic effect.
In situ hybridization was used to examine effects of monocular enucleation on nicotinic acetylcholine receptor subunit cc3 mRNA in the rat dLGNand visual cortex. After 28 days postoperative, there were no significant differences in α3 mRNA density between the contralateral (deprived) and ipsilateral (non-deprived) sides. The lack of obvious effects of visual deprivation on α3 mRNA density suggests that other factors, possibly intrinsic to dLGNand visual cortex, govern the postnatal expression of α3 mRNA.
A single plaque-pure lambda clone designated λBA84 that hybridized to a ˆ32P-labeled bovine arginine tRNA was isolated from a bovine genomic library harbored in a lambda bacteriophage vector. A 2.3-kilobase segment of this clone was found to contain an arginine transfer RNAccg gene by Southern blot hybridization analysis and dideoxyribonucleotide DNA sequencing. This gene contains the characteristic RNA polymerase III split promoter sequence found in all eukaryotic tRNAs and a potential RNA polymerase III termination site, consisting of four consecutive thymine residues, in the 3'-flanking region. Several possible cis-acting promoter elements were found within the 5'-flanking region of the sequenced gene. The function of these elements, if any, is unknown.
Concurrent outdoor aquatic 1950 L microcosm and 0.04 ha mesocosm experiments with bluegill sunfish evaluated the ecological impact of cyfluthrin. Cyfluthrin effects were not observed on mesocosm bluegill; a slight decrease in growth was observed in the microcosm bluegill. Otolith weight to length relationships between bluegill size-classes from microcosms, local streams, and a fish hatchery revealed no differences. Our results indicated bluegill predation impacts were slight on benthic invertebrates. Extensive predation on emerging insects was observed. Microcosm bluegill impacts on zooplankton populations followed expected predation effects, resulting in larger populations of smaller taxa. Bluegill functioned as "keystone" predators for microcosm taxa and improved taxa richness for benthic colonizing invertebrates and zooplankton.
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