Extended acid digestion for inactivation of fecal coliforms.

The objective of this research was to establish a correlation between inactivation of fecal coliforms caused by organic acids in their unionized form in batch acid digesters and semicontinuously fed acid digesters at both mesophilic (38 degrees C) and low-mesophilic (24 degrees C) temperatures. Batch acid digesters achieved a U.S. Environmental Protection Agency Class A level of fecal coliforms within 6 to 7 days of digestion at both temperatures. Semicontinuously fed, staged, acid-digestion systems achieved Class A standards on average only at mesophilic temperature at a solids retention time of 11 days. Systems operated at low-mesophilic temperatures did not achieve Class A standards.     

Human population intake fractions and environmental fate factors of toxic pollutants in life cycle impact assessment

The present paper outlines an update of the fate and exposure part of the fate, exposure and effects model USES-LCA. The new fate and exposure module of USES-LCA was applied to calculate human population intake fractions and fate factors of the freshwater, marine and terrestrial environment for 3393 substances, including neutral organics, dissociating organics and inorganics, emitted to 7 different emission compartments. The human population intake fraction is on average 10(-5)-10(-8) for organics and 10(-3)-10(-4) for inorganics, depending on the emission compartment considered. Chemical-specific human population intake fractions can be 1-2.7 orders of magnitude higher or lower compared to the typical estimates. For inorganics, the human population intake fractions highly depend on the assumption that exposure via food products can be modelled with constant bioconcentration factors. The environmental fate factor is on average 10(-11)-10(-18) days m(-3) for organics and 10(-10)-10(-12) days m(-3) for inorganics, depending on the receiving environment and the emission compartment considered. Chemical-specific environmental fate factors can be 1-8 orders of magnitude higher or lower compared to the typical estimates. The largest differences between the new and old version of USES-LCA are found for emissions to air and soil. This is caused by a significant change in the structure of the air and soil compartments in the new version of USES-LCA, i.e. the distinction between rural and urban air, including rain-no rain conditions and including soil depth dependent intermedia transport.     

Insect oostatic peptide: absence of effect on mice ovaries

An analogue of insect oostatic peptide, the pentapeptide H-Tyr-Asp-Pro-Ala-Pro-OH (H-YDPAP-OH), was administered to female mice and its effects on reproduction and development of the ovaries were studied. Up to 0.5 mg of the peptide per mice (25 g b.w.) injected intraperitoneally did not change the rate of pregnancy, number of offsprings and histological findings in ovaries and uterus in comparison to saline treated controls.     

Formation of chloroarenes upon gas-phase pyrolysis and slow combustion of benzene-HCl mixtures

Pyrolysis (800–900°C, ca. 5 s) of benzene/HC1 mixtures leads to chlorobenzene (1) even in a reducing environment of H₂ and/or CH₄. With added oxygen, 1 is formed even at 550°C; such slow combustions also yield chlorinated phenols and dibenzofurans.     

A new structure-affinity relationship for TCDD receptor binding

We have investigated the capacity of various indoles to inhibit specific binding of [1,6-³H]2,3,7,8-tetrachlorodibenzo- -dioxin ([³H]TCDD) in rat liver cytosol, as analyzed by electrofocusing in polyacrylamide gels. Of these indoles, indolo[3,2- ]carbazole was the most active. The IC₅₀ value for TCDD receptor binding of indolo[3,2- ]carbazole as well as for 2,3,7,8-tetrachlorodibenzofuran was 3.6 nM. We have also studied the influence on binding exerted by introduction of some substituents on indolo[3,2- ]carbazole. Substitution with methyl groups at the 5 and 11 positions resulted in an increased affinity (IC₅₀ 1.2 nM) for the TCDD receptor as compared to the parent compound. Computer-supported molecular structure studies indicated that if the van der Waals radii of atoms are included, a rectangle of 6.8 × 13.7 Å may account for the binding of high-affinity ligands to the TCDD receptor.     

Differences in context and function of two distinct waving displays in the fiddler crab, <Emphasis Type="Italic">Uca perplexa</Emphasis> (Decapoda: Ocypodidae)

To respond appropriately to communication signals, animals must have the ability to decipher signal meaning. At a basic level, interpreting the difference between territorial and courtship signals can be vital for the survival and reproduction of social animals. Male and female fiddler crabs communicate with claw-waving displays, but the function of these waves remains uncertain. Species differ in the context in which they wave: Some wave during courtship, some during territorial defence and some during both. In this paper, we provide evidence that males of an Australian species of fiddler crab, Uca perplexa, use two different types of claw waving display, lateral and vertical. Lateral waves are employed solely in a courtship context, whilst vertical waves are employed during courtship as well as territorial interactions. Using video recordings, we show that lateral waves were produced spontaneously (broadcast), and their frequency increased only in the presence of female wanderers. Vertical waves were not broadcast but were elicited by male wanderers during agonistic interactions and female wanderers during close range courtship. Male resident U. perplexa were able to discriminate the sex of wandering crabs on the mudflat at distances of 32 cm. During all resident–wanderer interactions, residents attempted to maintain a position directly between the wanderer and the home burrow and orient themselves to face females and to present the major claw towards males. To our knowledge, this is the first demonstration of the multiple use of waving displays in a fiddler crab species.     

Cytochrome P4501A induction and testosterone hydroxylation in cultured hepatocytes of four fish species

Primary hepatocytes of the rainbow trout (Oncorhynchus mykiss), flounder (Platychthis flesus), dab (Limanda limanda) and lemon sole (Microstomus kitt) were exposed to 3,3'4,4'5 pentachlorobiphenyl (PCB 126) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for two days. This resulted in a dose-dependent induction of cytochrome P4501A (CYP1A) activity, measured as ethoxyresorufin O-deethylase (EROD), or methoxyresorufin O-deethylase (MROD) activity. In all species, a linear relationship was observed between EROD and MROD activities, suggesting that the same CYP1A enzyme metabolizes the two alkoxy-resorufin substrates. Exposures of hepatocytes of flounder or dab to TCDD, resulted in a 59-fold and 8.2-fold induction of EROD activity, respectively. This did not concur with a change in the in vitro testosterone hydroxylation profiles of both species. These and other in vitro data indicate that TCDD exposure does not influence monooxygenase activities involved in testosterone hydroxylation. Furthermore, CYP1A is of minor importance for testosterone hydroxylation in these fish species.     

Mating strategies of a nocturnal,desert rodent (Dipodomys spectabilis)

Summary The mating system of a nocturnal, desert rodent, the banner-tailed kangaroo rat (Dipodomys spectabilis) was studied through direct observation, live-trapping, and radiotelemetry over a 13-month period from August 1986 to August 1987. Mating behavior varied from exclusive matings between male and female neighbors to competitive mate searching and direct male competition. In summer matings and early in a November to May breeding season, males located receptive females and mated exclusively with them without disturbance from other males. As the operational sex ratio changed in favor of males, multiple males converged on an estrous female's territory and competed for access to her. However, an older, experienced male usually monopolized the matings of the same one to two close female neighbors for the entire breeding period, and females mated with the same male neighbor over several estrous cycles. Monopolization of females by neighbor males was facilitated by female relaxation of individual territorial defense. Dominant males spent considerable time in the territories of the females they monopolized before and during mating. This relaxation in territorial defense was seen in dyadic encounters in which females tolerated all males but allowed significantly more contact by neighbor than stranger males. Neighbor recognition, therefore, seems important in coordinating the mating interactions of this solitary rodent.     

Footdrumming and other anti-predator responses in the bannertail kangaroo rat (Dipodomys spectabilis)

Summary Anti-predator behaviors of the bannertail kangaroo rat (Dipodomys spectabilis) toward snake predators were investigated. We induced responses by presenting a live (tethered) snake and an inflatable snake decoy to rats of known ages and sex in their territories. Comparisons of behaviors during spontaneous activity (baseline), naturally occurring snake-rat interactions, and experimental procedures further clarified anti-predator behaviors. The tethered snake immediately induced high rates of footdrumming (the repeated striking of the hind feet on the ground) in all rats (n=24) (Table 2), and individuals of both sexes and all ages footdrummed significantly more at the tethered snake than at the decoy. Other antipredator behaviors included alert postures, jumpback, kicking sand and avoidance. Juvenile rats exhibited more avoidance behavior and alert postures than adults and footdrummed at the decoy only if they experienced the snake first. We conclude that footdrumming functions as an individual alarm signal against predation by snakes in D. spectabilis. The drumming probably informs a snake that it has been detected and may cause it to leave. Because rats did not footdrum in response to aerial predators (owls), we suggest that kangaroo rats use different anti-predator strategies that depend on the kind of threat and the type of predator.     

Male tail streamer length predicts fertilization success in the North American barn swallow (Hirundo rustica erythrogaster)

In socially monogamous species, extra-pair paternity has the potential to increase the variance in male reproductive success, thereby affecting the opportunity for sexual selection on male extravagant ornamentation. In the European barn swallow (Hirundo rustica rustica), the tail streamer length is a sexually selected male ornament and an honest indicator of viability. The North American barn swallow (Hirundo rustica erythrogaster) also shows sexual dimorphism in tail streamer length, but whether this trait holds the same signalling function in this subspecies is a controversial issue, and the available literature is presently scarce. Here, we present data on paternity in the North American barn swallow, including a complete sampling of extra-pair sires in four colonies. We analysed how extra-pair paternity affected the variance in male fertilization success and examined whether male tail streamer (i.e. the outermost tail feather) length correlated with fertilization success (n=86 males). Extra-pair paternity constituted 31% of all offspring and significantly increased the variance in male fertilization success. The number of offspring sired by extra-pair males accounted for almost half of the total variance in male fertilization success. Males with naturally long tail streamers had a higher fertilization success than males with shorter tail streamers, and this pattern was mainly caused by a higher extra-pair success for males with long tail streamers. Males with long tail streamers also paired with early breeding females in prime body condition. These results are consistent with the idea that there is directional sexual selection on male tail streamer length, possibly mediated through male extra-pair mating success or the timing of breeding onset.