Bayou virus detected in non-oryzomyine rodent hosts: an assessment of habitat composition, reservoir community structure, and marsh rice rat social dynamics.

In the United States, Bayou virus (BAYV) ranks second only to Sin Nombre virus (SNV) in terms of hantavirus pulmonary syndrome (HPS) incidents, having been confirmed in cases from Texas and Louisiana since its discovery in 1994. This study on BAYV infection among sympatric, non-oryzomyine rodents ("spillover") in Freeport, TX, is the first to link patterns of hantavirus interspecific spillover with the spatiotemporal ecology of the primary host (marsh rice rat, Oryzomys palustris). Mark-recapture and/or harvest methods were employed from March 2002 through May 2004 in two macrohabitat types. Rodent blood samples were screened for the presence of IgG antibody to BAYV antigen by IFA after which Ab-positive blood, saliva, and urine were analyzed for the presence of viral RNA by nested RT-PCR. From 727 non-oryzomyine captures, five seropositive (but not viral RNA positive) individuals were detected: one each of Baiomys taylori, Peromyscus leucopus, and Reithrodontomys fulvescens; and two Sigmodon hispidus. Spillover hosts were not associated with macrohabitat where O. palustris abundance, density, or seroprevalence was highest. Rather, spillover occurred in the macrohabitat indicative of greater overall disturbance (as indicated by grazing and exotic plant diversity) and overall biodiversity. Spillover occurred during periods of high seroprevalence detected elsewhere within the study region. Spillover locations differed significantly from all other capture locations in terms of percent water, shrub, and grass cover. Although greater habitat and mammal diversity of old-fields may serve to reduce seroprevalence levels by tempering intraspecific contacts between rice rats, greater diversity also may create an ecologically opportunistic setting for BAYV spillover. Impacts of varying levels of disturbance and biodiversity on transmission dynamics represent a vastly uncharacterized component of the evolutionary ecology of hantaviruses.

Seasonal variation of North American form of Gigantolaelaps mattogrossensis (Acari: Laelapidae) on marsh rice rat in southern coastal Texas.

The ectoparasites of a small mammal community within an intertidal zone in the upper Gulf coast region of Texas were studied to assess the seasonal variation in abundances of the mite Gigantolaelaps mattogrossensis (Fonseca) (Acari: Laelapidae) on the marsh rice rat, Oryzomys palustris (Harlan). Further study into the ecology and dynamics of this parasite-host relationship was deemed to be necessary to expand the understanding of these potential participants in the ecology of Bayou Hantavirus, an important causative agent of Hantavirus pulmonary syndrome. The objective of this study was to determine the effects of five predictor variables on mite abundance: prevalences of hosts, relative humidity, precipitation, temperature, and length of daylight. Mite abundance was modeled as a function of the five variables with analyses of variance and multiple regressions; however, because the predictor variables pertain to the sampling period rather than to the individual rodent host, the effective sample size was small and thus the sums of squares and cross products matrix was singular. We therefore developed and used a new method for estimating regression coefficients based on the "noise-addition method" (random residual variation) combined with a bootstrap step converting the reduced rank data to full rank, providing realistic estimates of confidence intervals for the regression statistics. The population abundances of mites fluctuated significantly across collecting periods. Humidity and precipitation were the most influential variables in explaining the variation in abundances of mites. Model interpretation suggests that G. mattogrossensis is a nidicolous parasite. These results provide a baseline understanding of the seasonal interactions between parasite and host.

Transgenic cotton over-producing spinach sucrose phosphate synthase showed enhanced leaf sucrose synthesis and improved fiber quality under controlled environmental conditions.

Prior data indicated that enhanced availability of sucrose, a major product of photosynthesis in source leaves and the carbon source for secondary wall cellulose synthesis in fiber sinks, might improve fiber quality under abiotic stress conditions. To test this hypothesis, a family of transgenic cotton plants (Gossypium hirsutum cv. Coker 312 elite) was produced that over-expressed spinach sucrose-phosphate synthase (SPS) because of its role in regulation of sucrose synthesis in photosynthetic and heterotrophic tissues. A family of 12 independent transgenic lines was characterized in terms of foreign gene insertion, expression of spinach SPS, production of spinach SPS protein, and development of enhanced extractable V (max) SPS activity in leaf and fiber. Lines with the highest V (max) SPS activity were further characterized in terms of carbon partitioning and fiber quality compared to wild-type and transgenic null controls. Leaves of transgenic SPS over-expressing lines showed higher sucrose:starch ratio and partitioning of (14)C to sucrose in preference to starch. In two growth chamber experiments with cool nights, ambient CO(2) concentration, and limited light below the canopy, the transgenic line with the highest SPS activity in leaf and fiber had higher fiber micronaire and maturity ratio associated with greater thickness of the cellulosic secondary wall.

Molecular Evidence For High Levels of Intrapopulation Genetic Diversity in Woodrats (Neotoma Micropus).

Nucleotide sequences from the mitochondrial control region and genotypes from 5 nuclear microsatellite loci were used to examine genetic structure and infer recent (within approximately the last 3,000 years) evolutionary history of a population (549 individuals) of the southern plains woodrat (Neotoma micropus). Observed heterozygosity values ranged from 0.61 to 0.89 across microsatellite loci and systematically were lower than expected heterozygosity values (0.66-0.95). Probability of unique identity using microsatellite data was high (1 individual in 66,005,424). Fifty-three mitochondrial haplotypes were obtained from 150 individuals. F(ST) values estimated from sequence and microsatellite data were 0.061 and 0.011, respectively, and the R(ST) for microsatellite data was 0.007. Within-group genetic variation ranged from 93.90% to 99.99% depending on whether sequence or microsatellite data were examined. Analyses of microsatellite data suggested that all sampled individuals belonged to a single population, albeit genetically diverse. However, combined data analyses suggested the presence of low levels of substructure attributable to maternal lineages within the population. Low nucleotide-diversity values (0.007-0.010) in addition to high haplotype-diversity values (0.915-0.933) indicate a high number of closely related haplotypes, and suggest that this population may have undergone a recent expansion. However, Fu's F(S) statistic did not fully support this finding, because it did not reveal a significant excess of recent mutations. A phylogenetic approach using the haplotype sequence data and a combined set including both haplotype and genotype data was used to test for evolutionary patterns and history.

Northern pocket gophers (Thomomys talpoides) as biomonitors of environmental metal contamination.

We live-trapped 40 northern pocket gophers across two years from the Anaconda Smelter Superfund Site, Anaconda, Montana, USA, to determine their exposure to five metal contaminants and effects of exposure on selected measurements. Soil, gopher blood, liver, kidney, and carcass samples were analyzed for arsenic, cadmium, lead, copper, and zinc. Hematological parameters, kidney and liver porphyrins, and red blood cell delta-aminolevulinic acid dehydratase (ALAD) activity were also measured. Micronutrients Cu and Zn were detected in all tissues analyzed, and Cd, Pb, and As were detected less frequently. We report differences in metal distribution among different tissues and differences in bioaccumulation for different metals within the same tissue. No significant differences were observed in concentrations of Zn or Cu in any tissue across the study site, but relationships between lead in soil and lead in carcass proved especially strong (r2 = 0.80; p < 0.001; n = 18). Among biomarker data, we observed a negative relationship between concentration of lead in the soil and ALAD activity in gophers with detectable concentrations of lead in their blood (r2 = 0.45; p = 0.006; n = 15). Results of this study suggest that northern pocket gophers are useful biomonitors of environmental Pb, Cd, and As contamination, and their broad geographic range across North America could allow them to be an important component of site-specific metals assessments.

Application of size-free canonical discriminant analysis to studies of geographic differentiation

A análise discriminante canônica (ADC) é um procedimento empregado em estudos de variaçäo geográfica, diferenciaçäo interespecífica e macroevoluçäo. Todavia, o emprego desta técnica, com organismos nos quais o tamanho dos indivíduos possa variar em funçäo da amostragem, pode originar resultados espúrios, pois a discriminaçäo entre as amostras será um artefato de amostragem. Apresentamos estatisticamente o efeito da variaçäo no tamanho dos indivíduos dentro das amostras. Neste procedimento, o efeito do tamanho é removido calculando a regressäo de cada caráter sobre uma estimativa multidimensional de tamanho, o primeiro componente principal. A análise discriminante canônica é entäo efetuada sobre os resíduos da análise de regressäo. A aplicacäo deste método é ilustrada em uma análise de diferenciaçäo geográfica no roedor Proechimys dimidiatus (Echimydiae). Uma lista de comandos do programa estatístico SAS-PC, necessários para a implementaçäo do método é também fornecida

HETEROCHRONIC VARIATION IN THE DEVELOPMENTAL TIMING OF CRANIAL OSSIFICATIONS IN POECILIID FISHES (CYPRINODONTIFORMES).

The quantitative description of ossification sequences and other developmental events with respect to body size provides a basis for assessing the ontogenetic patterns underlying differences in morphological structure. To the extent that such sequences are evolutionarily conservative, they may also provide a basis for phylogenetic inference. Ossification profiles were examined in five species of poeciliid fishes of the genera Poecilia, Xiphophorus, and Poeciliopsis, selected to represent three lineages of varying evolutionary distinctiveness. Although ossification sequences are highly correlated among species, numerous small timing differences and reversals are evident, differences that are accentuated more among than within genera. The timing profiles by themselves, when used to construct hypothetical phylogenetic trees, contain sufficient historical information to recover evolutionary relationships consistent with conventional systematic criteria based primarily on adult osteology and external morphology. Character-state changes mapped onto the resulting trees can be interpreted directly as heterochronic accelerations and retardations of ossification.

PATTERNS OF QUANTITATIVE VARIATION IN LEPIDOPTERAN WING MORPHOLOGY: THE CONVERGENT GROUPS HELICONIINAE AND ITHOMIINAE (PAPILIONOIDEA: NYMPHALIDAE).

Wing morphology has historically been a major focus in taxonomic and evolutionary studies of lepidopterans. However, general patterns of quantitative variation and diversification in wing sizes and shapes and the factors underlying them have been unexplored. A morphometric study of wing variation in the convergent heliconine and ithomine butterflies reveals remarkable similarities, both in their morphologies at a given size and in their patterns of allometry and variability. The groups differ primarily in the relative lengths of inner and outer forewing margins, with larger species being more similar across groups than smaller ones. Allometric size-scaling variation accounts for more than 90% of the total morphological variation in the two groups and thus seems to be the major determinant of wing shape. Forewings and hind wings are isometric in size (area) with respect to one another; however, wing shape within and among groups is significantly allometric, resulting in considerable shape differences between small and large species. A strong trend of increasing variability from anterior to posterior along the wings is consistent with hypotheses of aerodynamic constraint. Wings and bodies represent classical morphological "character suites" in that size and shape variation are more tightly correlated within suites than among them. Such complexes argue against the overriding importance of aerodynamic factors, such as wing load and muscle development, in constraining gross morphology.

COMPARATIVE PATTERNS OF GROWTH AND DEVELOPMENT IN CRICETINE RODENTS AND THE EVOLUTION OF ONTOGENY.

The quantitative description of growth curves for morphometric traits provides a basis for assessing the ontogenetic patterns underlying differences in morphological structure, as demonstrated with comparisons among neotomine-peromyscine rodents. Morphometric differences among contemporary rodent species are shown to result from relatively simple changes in relative growth rates and timing. Quantitative ontogenetic studies add a dynamic component to the assessment of morphological similarity, thus providing a more robust procedure for detecting homoplasy than static comparison of adult morphology. Applying the principles of phylogenetic systematics to studies of developmental timing among closely related taxa may be a useful and informative complement to studies based on molecular similarity or static comparison of adult morphology. Interspecific and intraspecific differences in allometric scaling of anatomical structures may reflect differences in growth patterns among the taxa compared; caution is warranted in inferring patterns of genetic correlation from data on phenotypic scaling.