Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact email@example.com with any questions.
Macroinvertebrate biotic indices are widely used in the assessment of water quality. Brevard College's biology classes utilize an order-level biotic index created in Wisconsin, the Wisconsin Biotic Index (WBI), in part because of its ease of use. The North Carolina Department of Environment and Natural Resources makes water quality assessments using the North Carolina Biotic Index (NCBI), which accounts for the sample's ecoregion and season and assigns each individual species its own pollution tolerance level. Studies have shown that genus and species-level tolerance values provide more accurate water quality assessments than order-level. Because identification to genus and species may be difficult for beginners, assigning a mean order-level tolerance value for each group could make the NCBI more user-friendly (ONCBI). Both indices were compared to the NCBI using samples collected from three distinct locations on the Davidson River in the months of October 2002 through April 2003. Samples were collected using a kicknet technique twenty times at each location. The results of the study indicate that the ONCBI underestimates the quality of streams in the southern Appalachians; however water quality rankings given by the WBI were not significantly different than those produced by the NCBI. It is suggested that the use of order-level identification is an adequate means of monitoring the quality of streams in the southern Appalachians.
Polychlorinated biphenyls (PCBs) are environmental contaminants that cause a variety of health problems in exposed populations, including adverse reproductive effects in females. The present study examined the ability of two PCB congeners, PCB 126 and PCB 52, to disrupt reproductive function at the level of the pituitary gland in females. Specifically, the ability of PCBs 126 and 52 to alter pituitary luteinizing hormone (LH) secretion in response to the hypothalamic releasing factor gonadotropin-releasing hormone (GnRH) was assessed. Subcutaneous oil or PCB injections (PCB 126 or 52 at 200 or 400 μg/kg bodyweight) were administered to ovariectomized female rats at 1000h for 2 days prior to experiments. On the day of experiments, hourly blood samples were drawn from 1100 – 1600h for LH measurements. Pentobarbital was administered at 1130h to block endogenous GnRH release. Exogenous GnRH (50 ng/pulse) or saline pulses were administered once every 30 min from 1200h-1530h. LH measurements revealed dose-dependent effects of PCBs 126 and 52 on GnRH-stimulated LH secretion, with the lower dose of PCBs inhibiting GnRH-stimulated LH secretion, and the two-fold higher dose enhancing GnRH-stimulated LH secretion. These results indicate that PCBs 126 and 52 alter pituitary sensitivity to GnRH, and provide evidence of yet another mechanism whereby PCBs interfere with reproductive function in females.
The role of olfaction in the reproductive behavior of fishes is complex and not well understood. Olfactory signals may be important in communicating species identity, signaling the reproductive state of individuals, and initiating courtship behavior of males. The objective of this research was to study the influence of female visual and olfactory cues on the courtship behavior of male Kenyi Cichlids, Pseudotropheus lombardoi. Individual males were presented with gravid females contained in different types of chambers. Chambers varied in the color of their walls (black or clear) and in the type of their walls (solid or perforated). Clear chambers permitted males to receive visual cues, whereas perforated chambers allowed males to receive olfactory cues. Each male was presented with females contained in clear perforated (CP), clear solid (CS), black perforated (BP), and black solid (BS) chambers. Three-way analyses of variance (ANOVA) revealed that for six of the seven behaviors investigated, wall color had a significant effect on male behavior, with clear chambers eliciting a greater response than black chambers. Wall type did not have a significant effect on any of the behaviors. The interaction between wall color and wall type was non-significant for all behaviors. This study indicates that male P. lombardoi rely on visual cues from females to initiate courtship behavior. Olfactory cues appear to play little if any role in courtship behavior of this species.
Wild type and mutant Arabidopsis thaliana plants were used to investigate the protein expression of plants exposed to elevated concentrations of aluminum. Plants were grown in a growth chamber at 25°C, 16-hour day, and 8-hour dark for eight weeks before subjecting them to different concentrations of AlCl3 solution. Time course experiments showed that Arabidopsis plants respond to aluminum toxicity by altering their protein expression. Our data indicate that aluminum toxicity caused Arabidopsis plants to express a protein in the range of 97 kD, and a medium-molecular weight protein in the range of 45 kD. Our data also indicate that responses by Arabidopsis plants to Al toxicity are not similar to responses to stresses that cause the induction of HSP70.
In this study, the diversity of the haloarchaea found within a crystallizer pond of a solar saltern located in San Diego, California, USA was examined. Both cultured-based and culture-independent polymerase chain reaction (PCR) 16S ribosomal DNA (rDNA) molecular phylogenetic methodology was employed. Of the eighteen defined genera in the family Halobacteriaceae, three different genera were found to be represented in this study, along with two apparent novel lineages containing only uncultivated representatives. These two novel lineages are most closely related to the genera Halogeometricum and Haloferax. Of the three defined genera represented, Haloarcula, Halobacterium, and Halorubrum, we were able to identify both cultured isolates and DNA from uncultivated members from within these groups. Based on culturing and culture-independent sampling, the predominant members of the haloarchaeal crystallizer community in this particular saltern belonged to the genus Halobacterium. It is also noteworthy that no halophilic bacteria were detected as part of the community in these studies.
Many socially monogamous birds have been shown to be genetically polygamous, and such behavior can be enhanced in captivity. We verified the monogamous behavior of pigeons (Columba livia) in a captive population using DNA fingerprinting with multilocus minisatellite (Jeffreys') probes. No extra pair offspring were detected when 25 chicks from unique matings were analyzed. Two potentially extra-pair offspring were detected among 43 chicks from matings of socially established pairs produced during a two-year period. That the social pair bond remained unbroken throughout the two years of our study was confirmed by molecular analysis of offspring from sequential matings.
Fishes from multiple orders produce and recognize chemical alarm signals. In ostariophysan fishes, the alarm substance originates in epidermal cells and is released when their skin is damaged. In fathead minnows (Pimephales promelas) responses to alarm pheromones released from conspecifics include shoaling, seeking cover, foraging less, and remaining motionless. Naïve fathead minnows apparently learn to fear a novel predator's scent by observing the behavior of experienced fish in the presence of the scent. This suggests that fish may be able to perceive a threat using visual cues alone. We asked whether fathead minnows can perceive a threat by simply observing conspecifics that are exposed to alarm substances. We exposed groups of fathead minnows to skin extract containing the alarm pheromone and observed the responses of fish in adjacent aquaria to determine whether this second group of fish perceived that the adjacent fish sensed danger. There was no significant response to the visual stimulus, but this may be because the adjacent fish exposed to the alarm substance did not respond to the alarm substance.