Coyote senses in predation: Environmental influences on their relative use

The purpose of this study was to determine the relative importance of vision, audition, and olfaction to coyotes (Canis latrans) hunting under various environmental conditions. The time durations for four coyotes to locate rabbits within a large outdoor enclosure were determined, with the visual, auditory, and olfactory stimuli emitted by the rabbits blocked individually, in pairs, and altogether. Visual stimuli were eliminated by conducting the tests only during sub-threshold nocturnal conditions. Auditory stimuli were eliminated by killing the rabbits immediately prior to a test. Olfactory stimuli were eliminated by inducing anosmia in each coyote through irrigation of the nasal mucosa with a 10% zinc sulphate solution. The relative importance of these three senses in decreasing order was concluded to be: vision, olfaction, and audition.     

Remote touch prey‐detection by Madagascar crested ibises Lophotibis cristata urschi

Birds that forage by probing must often rely on sensory systems other than vision to detect their buried prey. Such senses may include hearing (e.g. Australian magpies (Atramidae), American robins (Turdidae)) or chemical senses/olfaction (e.g. kiwi (Apterygidae) and some shorebirds (Scolopacidae)). Probe foraging kiwi and shorebirds are also able to use vibrotactile cues to locate prey buried in the substrate at some distance from their bill‐tips (‘remote touch’). These birds possess an organ consisting of a honey‐comb of sensory pits in bone of the bill‐tips, packed with mechanoreceptive nerve ending (Herbst corpuscles). Such a bill‐tip organ has recently also been described in ibises (Threskiornithinae), but its function not elucidated. We designed a foraging experiment presenting mealworm prey to three captive Madagascar crested ibises Lophotibis cristata urschi under a variety of trial conditions to discover whether they were using remote touch, mediated by their bill‐tip organ; chemosense/olfaction; or hearing to locate buried prey. The ibises were reliant on remote touch for prey detection – the first time this sensory system has been demonstrated for this group of birds. They did not appear to use hearing or chemical senses/olfaction to aid in prey detection.     

Passive sound localization of prey by the pallid bat (Antrozous p. pallidus)

Summary The pallid bat (Antrozous p. pallidus) uses passive sound localization to capture terrestrial prey. This study of captive pallid bats examined the roles of echolocation and passive sound localization in prey capture, and focused on their spectral requirements for accurate passive sound localization.Crickets were used as prey throughout these studies. All tests were conducted in dim, red light in an effort to preclude the use of vision. Hunting performance did not differ significantly in red light and total darkness, nor did it differ when visual contrast between the terrestrial prey and the substrate was varied, demonstrating that the bats did not use vision to locate prey.Our bats apparently used echolocation for general orientation, but not to locate prey. They did not increase their pulse emission rate prior to prey capture, suggesting that they were not actively scanning prey. Instead, they required prey-generated sounds for localization. The bats attended to the sound of walking crickets for localization, and also attacked small, inanimate objects dragged across the floor. Stationary and/or anesthetized crickets were ignored, as were crickets walking on substrates that greatly attenuated walking sounds. Cricket communication sounds were not used in prey localization; the bats never captured stationary, calling crickets.The accuracy of their passive sound localization was tested with an open-loop passive sound localization task that required them to land upon an anesthetized cricket tossed on the floor. The impact of a cricket produced a single 10–20 ms duration sound, yet with this information, the bats were able to land within 7.6 cm of the cricket from a maximum distance of 4.9 m. This performance suggests a sound localization accuracy of approximately ±1° in the horizontal and vertical dimensions of auditory space. The lower frequency limit for accurate sound localization was between 3–8 kHz. A physiological survey of frequency representation in the pallid bat inferior colliculus suggests that this lower frequency limit is around 5 kHz.     

Prey capture by the cuttlefish (Sepia officinalis L): An experimental study of two strategies

This study shows that the size of the prey ($\text{Carcinus maenas}$) relative to the predator ($\text{Sepia officinalis}$) is of importance in the choice between two types of attack: either capture by ejection of the two extensible tentacles, or capture by jumping on the prey. Small crabs are preferentially captured by the first method and large crabs by the second. Other factors which may explain the observed variations, include previous experience of the predator and the behaviour of the prey.     

Effect of removing the zona pellucida on development of hamster and bovine embryos invitro and invivo

Uterine stage embryos collected from the hamster (8-cell) and cow (morula, early blastocyst) were monitored for development $\text{in}$$\text{vitro}$ (embryo culture) and $\text{in}$$\text{vivo}$ (embryo transfer) following premature removal of the zona pellucida.Removal of the zona pellucida did not significantly affect $\text{in}$$\text{vitro}$ development to the blastocyst stage of (1) 8-cell hamster embryos (zonae removed by a combined enzymic-mechanical procedure), (2) bovine morulae (zonae removed by mechanical means only) (3) early bovine blastocysts (zonae removed by the enzymic-mechanical technique).Zona-free hamster embryos formed significantly fewer viable fetuses than did zona-intact embryos. The lower incidence of fetal development observed following transfer of zona-free 8-cell hamster embryos may have resulted in part from the formation of chimeras by fusion of these embryos $\text{in}$$\text{utero}$. Such fusion was observed to occur $\text{in}$$\text{vitro}$ between zona-free embryos placed in close proximity. The proportion of pregnancies resulting from transfer of bovine blastocysts cultured from zona-free morulae was similar to that of zona-intact embryos.In this study we have demonstrated that (1) enzymic and mechanical procedures used to remove zonae pellucidae from uterine-stage hamster and bovine embryos do not adversely affect subsequent development of these embryos $\text{in}$$\text{vitro}$ and $\text{in}$$\text{vivo}$ and (2) zonae pellucidae are not required for normal development of these embryos. These findings have implications for microsurgery of mammalian embryos and for embryo transfer.     

Optimal strategies for predator avoidance: the relative importance of speed and manoeuvrability

The relative importance of speed and manoeuvrability in predator-prey chases was assessed by investigating whether or not a pursuing predator could catch its prey in a simple turning gambit initiated by the prey animal. The turning radius and velocity of the prey were normalized by dividing them by those of the predator. With the use of numerical methods to solve implicit equations it was determined for what values of relative radii and velocity the prey could escape. When escape was possible the optimal time of initiation of the prey's turn and the minimum closure distance of the predator were computed. It was found initially by numerical and subsequently by analytic techniques that, in order for the prey to escape the predator in the turning gambit, its normalized velocity must be related to its normalized radius by the inequality: $\text{v>r}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ over the interval 0 ? r ? 1. Situations in which the results of the turning gambit may be expected to give realistic predictions of capture or escape are discussed together with physical factors governing the relationship between turning radius and velocity, and the conditions under which the prey might profitably trade higher velocity for a smaller turning radius. Lastly, a number of specific predator-prey combinations are treated with a view towards illustrating the application of the theory and promoting the collection of simultaneous turning radii and velocity data.     

Progesterone-induced inactivation of nuclear estrogen receptor in the hamster uterus is mediated by acid phosphatase

Inactivation of hamster uterine estrogen receptor was assayed in nuclear KCl extracts (30 min, 37°C, pH 7.5) after progesterone treatment $\text{in}\text{vivo}$ for 2h. At very low concentrations ($\text{>}$0.05 mM), molybdate and vanadate blocked the progesterone-induced increase in receptor inactivation. In contrast, only high concentrations ($\text{>}$10 mM) of the inhibitors blocked receptor inactivation in extracts from untreated hamsters. Gel electrophoresis and inhibition curves for phosphatases in nuclear extract demonstrated that acid, rather than alkaline, phosphatase activity is most likely responsible for these effects. These data suggest that progesterone antagonizes estrogen action in the hamster uterus by promoting estrogen receptor dephosphorylation leading to inactivation.     

Partial characterization of prostaglandin synthetase in the reproductive tract of the male house cricket, acheta domesticus

An active prostaglandin (PG) synthetase was found in the 12100 g pellet of reproductive tract homogenates of the male house cricket, $\text{Acheta domesticus}$. Comparatively, the 12100 g supernatant and the microsomal fractions were inactive. The PG synthetase in the pellet fraction was characterized in terms of cofactor, temperature, pH, and incubation time requirements. Indomethacin, a known inhibitor of mammalian PG synthetase, was not inhibitory to the cricket synthetase. The procedure and findings are relevant to PG synthetase studies of any organism or tissue.     

Social play behaviours and insect predation in northern grasshopper mice (Onychomys leucogaster)

Play behaviours of northern grasshopper mice, $\text{Onychomys leucogaster}$, were observed from 27 to 61 days of age and after a brief period of social isolation. The mice were also observed during a simple test of cricket predation. With the exception of an active play-soliciting response, the play behaviours were quite similar to those described for other rodents. Play declined with increasing age and was strongly potentiated by social isolation. There was no discernable relationship between any of the play measures and efficiency of cricket predation. There were no detectable sex differences in either play or predation.     

Characterization of the β-adrenergic receptors of hamster white fat cells: Evidence against an important role for the α2-receptor subtype in the adrenergic control of lipolysis

The binding characteristics of the β-adrenergic antagonist, [³H]dihydroalprenolol, to hamster white adipocyte membranes were studied. This binding occurred at two classes of sites, one having high affinity ($\text{K}{}_{\mathrm{<mtext>d</mtext>}}\text{= 1.6±1.3}\text{nM}$) but low capacity ($\text{32±17}\text{fmol/mg}$ membrane protein) and one having low affinity but high binding capacity. While the binding at the high-affinity sites was competitively and stereoselectively displaced by both β-antagonists and β-agonists, competition at the low-affinity sites occurred only with β-antagonists and was non-stereoselective. Thus, the β-agonist (?)-isoproterenol was further used to define nonspecific binding. Under these conditions, saturation studies showed a single class of high-affinity ($\text{K}{}_{\mathrm{<mtext>d</mtext>}}\text{= 1.6±0.5}\text{nM}$) binding sites with a binding capacity of $\text{53 ± 13}\text{fmol/mg}$ membrane protein (corresponding to $\text{4000 ± 980}$ sites per cell), and independent kinetic analysis provided a $\text{K}{}_{\mathrm{<mtext>d</mtext>}}$ value of 1.9 nM. Competition experiments showed that these binding sites had the characteristics of a $\text{β}{}_1\text{-}\text{receptor}$ subtype, yielding $\text{K}{}_{\mathrm{<mtext>d</mtext>}}$ values in good agreement with the $\text{K}{}_{\mathrm{<mtext>act</mtext>}}$ and the $\text{K}{}_{\mathrm{<mtext>i</mtext>}}$ values found for agonist-stimulation and for antagonist-inhibition of adenylate cyclase in membranes and of cyclic AMP accumulation and lipolysis in intact cells. Furthermore, the ability of β-agonists to compete with this binding was severely depressed by p[NH]ppG. These results thus support the contention that the specific [³H]dihydroalprenolol binding sites defined as the binding displaceable by (?)-isoproterenol represent the physiologically relevant β-adrenergic receptors of hamster white adipocytes. Finally, studies of the lipolytic response of these cells to (?)-norepinephrine showed that the inhibitory effect of the $\text{α}{}_2\text{-}\text{component}$ of this catecholamine was apparent only when the effects of endogenous adenosine were suppressed, a result which argues against an important regulatory role for the $\text{α}{}_2\text{-}\text{receptors}$ in the adrenergic control of lipolysis in hamster white adipocytes.     

Versuche zum Nachweis eines Riechvermögens von Anolis l. lineatopus (Rept., Iguanidae)

Various experiments with 56 captive-born lizards, Anolis lineatopus, involving up to four replicates strongly suggest that the species is capable of olfaction. The readiness to attack four diverse prey species (cricket, Mediterranean flour moth, German cockroach, wood ant) was neither influenced by odour cues nor by the degree of novelty of the prey item; odour cues were those of the prey offered in a trial and four pure non-prey odourous compounds. Approximately 80 % of the total variance of the two attack measures employed could be accounted for by the individuality of Ss and by fluctuations of attack readiness.     

Queuine hypomodification of tRNA induced by 7-methylguanine

Transfer RNA isolated from Chinese hamster cells transformed by 7-methylguanine is hypomodified for queuine. 7-Methylguanine rapidly induces queuine hypomodification of tRNA in normal Chinese hamster embryo cells under conditions leading to transformation, and the enzyme catalyzing the queuine modification reaction, tRNA: guanine transglycosylase, is inhibited by 7-methylguanine $\text{in}\text{vitro}$.     

Modification of hepatic microsomal oxidative drug metabolism in rats by the opiate maintenance drugs acetylmethadol, propoxyphene, and methadone.

The formation of cytochrome P-450 “metabolic intermediate” complexes $\text{in}$$\text{vivo}$ occurred with acetylmethadol and propoxyphene, but not methadone in both naive and phenobarbital-induced animals. The $\text{in}$$\text{vivo}$ formation correlated with the relative ability of these three compounds to form metabolic intermediate complexes and inhibit mixed-function oxidation reactions $\text{in vitro}$.     

Drug-induced changes in lipid composition of E. coli and of mammalian cells in culture: ethanol, pentobarbital, and chlorpromazine.

Both Chinese hamster ovary cells in culture and $\text{E.}$$\text{coli}$ cells change their lipid composition when grown in the presence of ethanol, pentobarbital, and chlorpromazine. The effects of ethanol and the cross-tolerant drug, pentobarbital, are similar. Both cause a shift from 18:0 fatty acid to 16:0 fatty acids in CHO cells and a decrease in the proportion of saturated fatty acids in $\text{E.}$$\text{coli}$. Chlorpromazine, a non-cross-tolerant drug, causes the opposite effect in $\text{E.}$$\text{coli}$, a decrease in the proportion of unsaturated fatty acids. Chlorpromazine has little effect on the fatty acid composition of CHO cells. These changes in lipid composition are proposed as an adaptive response and a part of the mechanism for the development of drug tolerance.     

High mutagenicity and toxicity of a diol epoxide derived from benzo[a]pyrene

(±)-7β,8α-Dihydroxy-9β,10β-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BP 7,8-diol-9,10-epoxide) is a suspected metabolite of benzo[a]pyrene that is highly mutagenic and toxic in several strains of $\text{Salmonella}\text{typhimurium}$ and in cultured Chinese hamster V79 cells. BP 7,8-diol-9,10-epoxide was approximately 5, 10 and 40 times more mutagenic than benzo[a]pyrene 4,5-oxide (BP 4,5-oxide) in strains TA 98 and TA 100 of $\text{S.}\text{typhimurium}$ and in V79 cells, respectively. Both compounds were equally mutagenic to strain TA 1538 and non-mutagenic to strain TA 1535 of $\text{S.}\text{typhimurium}$. The diol epoxide was toxic to the four bacterial strains at 0.5–2.0 nmole/plate, whereas BP 4,5-oxide was nontoxic at these concentrations. In V79 cells, the diol epoxide was about 60-fold more cytotoxic than BP 4,5-oxide.     

On the dual localization of lipoprotein lipase in rat heart. Studies with a modified perfusion technique

Rat hearts were perfused $\text{in vitro}$ using a modified $\text{Langendorff}$ technique, allowing the separate collection of coronary- and interstitial effluents. When heparin was added to the perfusion medium lipoprotein lipase was found in the coronary, as well as in the interstitial effluents. The relative amounts of lipase activity in both effluents varied with the feeding conditions of the animals, being high in the coronary effluent during fasting and high in the interstitial effluent during feeding. When glucagon (2.10^?7 M) was included in the perfusion medium, no differences between fasted and fed animals were obtained. The apparent K_m of the interstitial lipase was lower than that of the lipase found in the coronary effluent. The results are discussed in the light of the localization of lipoprotein lipase in rat hearts $\text{in situ}$.     

Coenzyme dissociation, a possible determinant of short half-life of inducible enzymes in mammalian liver

Corticosteroid inducible, rapidly turning-over ($\text{t}\text{1}\text{2}\text{= 12}$ min to 3 hrs) enzymes of rat liver cytosol are complex enzymes with dissociable coenzymes. Enzymatic activity can be used to measure the relative rate of coenzyme dissociation. A comparison of rapidly inducible compared to relatively uninducible complex enzymes shows that the relative rate of coenzyme dissociation aligns with the shortness of the $\text{t}\text{1}\text{2}$ of the enzyme suggesting that coenzyme dissociation may be a limiting step in the degradation process of these enzymes.     

Increased synthesis of a low molecular weight protein in vincristine-resistant cells

A 19,000-dalton peptide (pI = 5.7) that is synthesized in increased amounts in vincristine-resistant Chinese hamster cells ($\text{DC-3F}\text{VCRd-5}$) has been identified by two-dimensional gel electrophoresis. Reduced amounts of the protein were present in a revertant line of $\text{DC-3F}\text{VCRd-5}$, and only trace amounts were detected in control DC-3F cells. A similar protein (M_r = 19,000; pI = 5.7) was also found in a vincristine-resistant mouse line. Two vincristine-resistant human neuroblastoma cell lines likewise contained elevated levels of a low molecular weight acidic protein. Increased biosynthesis of the 19,000-dalton polypeptide in $\text{DC-3F}\text{VCRd-5}$ cells coincides with the presence of a homogeneously staining region, HSR, on a metaphase chromosome.     

Olfactory responses of Phycomyces blakesleeanus.

Upon exposure to low levels of various volatile compounds such as n-heptanol, methanol, CHCl₃, mercaptoheptane, etc., the sporangiophore of $\text{Phycomyces}\text{blakesleeanus}$ responds with a transient and reproducible decrease in its elongation rate. All 22 volatile substances tested (except H₂O) elicited negative responses. The amplitude of the responses depends on the compound and its concentration. A characteristic concentration, required for 50% inhibition, correlates remarkable well with the human olfactory threshold (coefficient of correlation r = 0.89 (P < 0.001)). Perhaps some process in olfaction is common to this fungus and higher systems.