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J J Whyte

Publications and source records attributed to J J Whyte.

At least 19 recordsLinked to original sources
PubMed2007

Fluorescent in situ hybridization for sex chromosome determination before and after fertilization in mice.

In mice, the relative numbers of male and female pups per litter not only can vary but can probably change over the course of pregnancy in response to numerous environmental and physiological factors. As such, a technique is required to determine gender at several developmental stages. Here we describe a robust and accurate fluorescent in situ hybridization (FISH) procedure for determining chromosomal sex that can be applied with minimal modification to sperm, pre-and post-implantation conceptuses and recovered dead post-natal pups. Sperm was prepared for FISH analysis y using a modified microwave decondensation-denaturation technique. Preimplantation conceptuses (0.5dpc) were cultured to the morula stage before sexing. They were then acid-treated to remove the zona pellucida. Tissue homogenates from postimplantational conceptuses (8.5dpc) and stillborn pups were fixed to pre-etched slides. Specimens were hybridized with identical, commercially available DNA probes for the X (FITC) and Y (Cy3) chromosomes. Sperm ratios met the expected value of 0.5 when determined by using XY FISH. Preimplantation conceptuses pre-treated with pepsin yielded distinct fluorescence of X and Y chromosomes in morulae, whereas microwave decondensation resulted in loss of conceptuses from the slide. Both 4.0 and 8.5dpc conceptuses displayed mean sex ratios of 0.5. Post-natal FISH analysis allowed gender identification of pups that could not be sexed due to developmental abnormalities or partial cannibalism. FISH analysis of sperm and of multiple conceptuses or post-natal tissue provided a cost-effective, accurate alternative to PCR-based sex determination.

Animals↗
PubMed2007

Maternal diet composition alters serum steroid and free fatty acid concentrations and vaginal pH in mice.

We examined the effects of three maternal diets (very high fat (VHF), low fat (LF), and control (Purina 5015)) on serum steroids, free fatty acids (FFA), and vaginal pH in National Institutes of Health Swiss mice. Females were fed (VHF, n = 33; LF, n = 33; 5015, n = 48) from 4 to 16 weeks of age. Following breeding, female serum was collected at 0.5 (pre-implantation, early diestrus) or 8.5 (post-implantation, mid-diestrus) days post-coitus (dpc). The serum concentrations of 17beta-estradiol, testosterone, progesterone, and FFA were analyzed at both collection points, and vaginal pH at 0.5 dpc. Striking differences in steroids and FFA were observed at 0.5 dpc among the groups. Estradiol was higher in the VHF (14.1 +/- 3.0 pg/ml), compared with LF mice (5.2 +/- 2.3 pg/ml; P< or = 0.05). In contrast, 0.5 dpc testosterone was lower in the VHF (10.5 +/- 3.0 pg/ml) versus the LF group (32.7 +/- 8.4 pg/ml; P< or = 0.05). At 8.5 dpc, progesterone was higher in the VHF (89.6 +/- 6.7 ng/ml) versus the 5015 group (60.1 +/- 4.9 ng/ml; P< or = 0.05). VHF mice had higher FFA concentrations at 0.5 dpc (1.0 +/- 0.2 mmol/l) than LF and control mice (0.5 +/- 0.1 and 0.6 +/- 0.1 mmol/l respectively; P< or = 0.05). At 8.5 dpc, VHF females had higher serum FFA (0.8 +/- 0.1 mmol/l) than LF and control females (0.4 +/- 0.1 and 0.6 +/- 0.1 mmol/l; P< or = 0.05). Mean vaginal pH of VHF females (6.41 +/- 0.09) was lower than 5015 females (6.76 +/- 0.10; P< or = 0.05). These diet-induced alterations in serum steroid and FFA concentrations might affect several reproductive processes, including preferential fertilization by one class of sperm over the other and sex bias in pre- and post-implantational embryonic development.

Animals↗
PubMed2005

The effect of creosote on vitellogenin production in rainbow trout (Oncorhynchus mykiss).

As part of a broader investigation into the effects of creosote treatments on the aquatic biota in pond microcosms, we examined the possible implications for vitellogenin (Vtg) production in Oncorhynchus mykiss [rainbow trout (RT)]. Vtg is the precursor of egg yolk protein and has emerged as a useful biomarker of exposure to estrogenic substances. Our a priori intent was to assess the ability of the creosote treatments (nominal cresoste concentrations were 0, 3, and 10 microl/L immediately after the last subsurface addition) to induce estrogenic responses in RT. The data showed no evidence of an estrogenic response in the treated fish. During the course of the experiment, however, the fish matured and began to produce Vtg, probably in response to endogenous estrogen. A posteriori analysis of the Vtg data from the maturing fish showed that after 28 days, the plasma Vtg concentrations were about 15-fold lower in fish from the creosote-treated microcosms compared with fish from the reference microcosm. Although the experiment design does not permit mechanistic insights, our observation suggests that exposure of female fish to PAH mixtures such as creosote can impair the production of Vtg with possible health implications for embryos and larvae.

Animals↗
PubMed2001

Effects of creosote exposure on rainbow trout pronephros phagocyte activity and the percentage of lymphoid B cells.

An outdoor microcosm study was conducted in order to evaluate the kinetics of immunomodulation in rainbow trout (Oncorhynchus mykiss) exposed to liquid creosote. Fish were sampled on d 7, 14, 21, and 28 from microcosms dosed initially with 0, 3, and 10 microl/L of creosote. Pronephros leukocytes were monitored for phagocytic activity, oxidative burst, and surface immunoglobulin-positive (Slg+) B-cell counts. Oxidative burst was inhibited by creosote exposure; however, by sampling d 28, the burst response returned to near control levels. Phagocytic activity, on the other hand, was stimulated, peaking on sampling d 7, then returning to near control levels by d 28. Although control Slg+ B-cell counts were quite variable across sampling days, Slg+ B-cell counts were also elevated in creosote-exposed fish after seven days of exposure. Slg+ B-cell numbers decreased significantly to near control levels during the remainder of the study. The overall results from this study confirm that creosote has the potential to alter certain immune parameters, and emphasize the importance of monitoring changes in the immune system during exposure. Polycyclic aromatic hydrocarbons (PAHs), a major constituent of liquid creosote, are the suspected immune-altering agents.

Animals↗
PubMed2000

Effect of maintaining rainbow trout in creosote microcosms on lens optical properties and liver 7-ethoxyresorufin-O-deethylase (EROD) activity.

Previously, exposure of fish to polycyclic aromatic hydrocarbons (PAHs) in both field and laboratory settings has been associated with eye damage, but this has only been expressed qualitatively. In this study, an automated scanning laser system has been employed to quantitatively evaluate changes in lens optical quality in rainbow trout (Oncorhynchus mykiss) following their in vivo exposure to creosote, which is a complex mixture with many PAHs. Rainbow trout were placed in 12,000-L outdoor microcosms dosed with 0, 3, or 10 microl/L liquid creosote for a 28-day period. Collected fish were examined for changes in focal length variability (FLV), lens size, and weight. These measurements were compared with induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity and hepatic and water concentrations of priority pollutant PAHs. The optical quality of rainbow trout lenses was significantly reduced following creosote exposure, as indicated by increased FLV. Lens damage was significantly related to hepatic EROD activity, and both effects rose with creosote dose. Analytical measurements of microcosm water indicated elevated concentrations of PAHs in creosote-dosed ponds, including compounds capable of inducing rainbow trout EROD activity in vitro. Hepatic concentrations of PAHs were low and not related to creosote dose, likely due to rapid metabolism and elimination. This study demonstrates for the first time employment of a highly sensitive and quantitative technique to measure lens damage in fish exposed to contaminants in situ. The relationship between this effect and hepatic CYP1A activity may suggest a mechanistic linkage, which could lead to the use of EROD activity as an indicator of toxic effect rather than just chemical exposure.

Animals↗
PubMed2000

Ethoxyresorufin-O-deethylase (EROD) activity in fish as a biomarker of chemical exposure.

This review compiles and evaluates existing scientific information on the use, limitations, and procedural considerations for EROD activity (a catalytic measurement of cytochrome P4501A induction) as a biomarker in fish. A multitude of chemicals induce EROD activity in a variety of fish species, the most potent inducers being structural analogs of 2,3,7,8-tetracholordibenzo-p-dioxin. Although certain chemicals may inhibit EROD induction/activity, this interference is generally not a drawback to the use of EROD induction as a biomarker. The various methods of EROD analysis currently in use yield comparable results, particularly when data are expressed as relative rates of EROD activity. EROD induction in fish is well characterized, the most important modifying factors being fish species, reproductive status and age, all of which can be controlled through proper study design. Good candidate species for biomonitoring should have a wide range between basal and induced EROD activity (e.g., common carp, channel catfish, and mummichog). EROD activity has proven value as a biomarker in a number of field investigations of bleached kraft mill and industrial effluents, contaminated sediments, and chemical spills. Research on mechanisms of CYP1A-induced toxicity suggests that EROD activity may not only indicate chemical exposure, but also may also precede effects at various levels of biological organization. A current research need is the development of chemical exposure-response relationships for EROD activity in fish. In addition, routine reporting in the literature of EROD activity in standard positive and negative control material will enhance confidence in comparing results from different studies using this biomarker.

Animals↗
PubMed1999

Ability of polycyclic aromatic hydrocarbons to induce 7-ethoxyresorufin-o-deethylase activity in a trout liver cell line.

Along with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 24 unsubstituted polycyclic aromatic hydrocarbons (PAHs) were evaluated for their ability to induce 7-ethoxyresorufin-o-deethylase (EROD) activity in the rainbow trout liver cell line RTL-W1. When the duration and cell density of exposure were increased, the EC(50) for EROD induction was relatively constant for TCDD, but increased for PAHs. Regardless of exposure conditions, EROD activity was not induced by 9 PAHs: naphthalene, phenanthrene, anthracene, pyrene, perylene, acenaphthylene, acenaphthene, fluorene, and fluoranthene. Two PAHs, benzo[g,h,i]perylene and coronene, induced EROD activity inconsistently. The remaining 13 PAHs consistently induced EROD activity. The EC(50)s for induction exhibited approximately a 110-fold range. The order of potency, from most to least potent, was benzo[k]fluoranthene, dibenzo[a,i]pyrene, dibenzo [a,h]anthracene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, benzo [b]fluoranthene, pentacene, benzo[b]anthracene, benzo[b] fluorene, chrysene, benzo[a]anthracene, benzo[e]pyrene, and triphenylene. When the induction potency was expressed relative to TCDD, the toxic equivalency factors (TEFs) ranged from 0.001 to 0.000 01. When expressed relative to benzo[a]pyrene, the TEFs ranged from 3.44 to 0. 03.

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