ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Feeding and associated electrical behavior of the Pacific electric ray Torpedo californica in the field (1994)

Lowe, C. G. ; Bray, R. N. ; Nelson, D. R.

Springer

Marine biology 120 (1994), S. 161-169

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ISSN: 1432-1793

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The predatory behavior of 74 Pacific electric rays (Torpedo californica), studied between August and December during 1988 through 1991 in situ off the Palos Verdes Peninsula, southern California, consisted of two feeding modes: an ambush from the substratum during the day and a more vigorous attack from the water column at night. Predatory motor patterns and electric organ discharges (EODs) were recorded on the video and audio channels of a housed camcorder. Predatory motor patterns included four phases: (1) jump (simultaneous with EOD initiation), (2) pectoral-fin cupping, (3) orientation to prey, and (4) ingestion. The initial electrical activity of the rays was a train of 46 to 414 5-ms monophasic EODs that lasted 0.45 to 7.06 s; the maximum number of EODs produced during an attack was 〉1200. Maximum output, measured on only one ray, was 45 V. Fifty-five rays were presented one of four types of prey stimuli: live fish (LF), freshly-speared fish (FSF), frozen fish (FF), or a simulated bioelectric field (SBF). The percent frequency of attacks for the LF, FSF, and FF treatments ranged from 70 to 〉90%, but was 〈30% for the SBF. The interval between prey presentation and attack was ≃30 s for the LF, FSF, and FF and over five times longer for the SBF; intervals averaged 〈4 s for the three rays tested at night. Attacks by rays on energized electrodes provide the first evidence that electric rays use electroreceptors to detect their prey. However, the lack of clear differences among the four prey treatments in five characteristics of the initial pulse train suggests that a suite of sensory stimuli cooperate in triggering an attack and regulating the electrical output during the attack.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00381951

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2

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Movements of tiger sharks (Galeocerdo cuvier) in coastal Hawaiian waters (1999)

Holland, K. N. ; Wetherbee, B. M. ; Lowe, C. G. ; [et al.]

Springer

Marine biology 134 (1999), S. 665-673

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ISSN: 1432-1793

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Externally and internally implanted sonic transmitters were used to track the movements of eight tiger sharks (Galeocerdo cuvier) ranging between 200 and 417 cm total length (TL), captured by hook-and-line on the south coast of Oahu, Hawaii, between 1993 and 1997. Attachment of the transmitters was facilitated by the fact that captured sharks exhibited tonic immobility when restrained and inverted at the side of the tagging vessel. Three common themes emerged from the horizontal movements of the tracked sharks: (1) offshore movements away from the island, (2) extended periods of directed, “straight-line” swimming, (3) orientation to the Penguin Banks – a shallow bank located ≃35 km from the release point. In shallow water (〈300 m) the sharks swam predominantly close to the bottom, in open water (〉300 m) they swam within the mixed layer at depths of ∼80 m. One shark dove briefly to 335 m. The average estimated swimming speed of sharks traversing open water was 0.29 body length (BL) s−1. Two sharks were recaptured after termination of the tracks; one of these sharks was recaptured twice, with a total time at liberty of 377 d. The data suggest that Hawaiian tiger sharks move within large home ranges and that they can efficiently navigate between distant parts of their range, even when this requires crossing open ocean waters.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002270050582

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3

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Serum blocks the osteolytic effect of cortisol in neonatal mouse calvaria (1992)

Lowe, C. ; Gray, D. H. ; Reid, I. R.

Springer

Calcified tissue international 50 (1992), S. 189-192

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ISSN: 1432-0827

Keywords: Bone resorption ; Glucocorticoid

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine , Physics

Notes: Summary Chronic glucocorticoid excess is associated with the development of osteoporosis and, in human subjects, there is histomorphometric evidence of increased bone resorption. Paradoxically, most in vitro studies have suggested that glucocorticoids inhibit bone resorption but recently two groups have demonstrated increased osteolysis in glucocorticoid-treated bone organ cultures. The present study reexamines the effect of cortisol on basal bone resorption in neonatal mouse calvaria with particular emphasis on the effect of serum supplementation of the media. In the absence of serum, 45Ca release was significantly stimulated by 10-7 M cortisol (treatment/control 1.37+-0.06, P〈0.005) and by 10-6 M cortisol (treatment/control 1.27+-0.08, P〈0.005). The stimulation of resorption by 10-7 M hydrocortisone was progressive from 24 to 96 hours of incubation. In contrast, when calvaria were incubated in the presence of 5% serum, bone resorption was not increased by cortisol (10-8 M-10-6 M). In the presence of 5% charcoal-stripped, heat-inactivated serum, there was a small stimulation of 45Ca release at 10-6 M hydrocortisone only (treatment/control 1.19 +-0.06, P〈0.01). Incubation of bones with indomethacin did not modify the effect of cortisol in either the presence or absence of serum. In serum-free conditions, cortisol 10-8 M significantly inhibited the rate of thymidine incorporation, though at higher concentrations this effect was not seen. Cortisol produced a dose-related inhibition of serumstimulated thymidine incorporation. It is concluded that the presence of serum substantially modifies the effect of cortisol on basal bone resorption. The cortisol-induced stimulation of bone resorption which is seen in serum-free conditions is sustained over time and is not mediated by alterations in prostaglandin synthesis.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00298799

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4

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Artificial redox coenzymes: biomimetic analogues of NAD+ (1999)

Ansell, R. J. ; Lowe, C. R.

Springer

Applied microbiology and biotechnology 51 (1999), S. 703-710

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ISSN: 1432-0614

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology

Notes: Abstract A range of biomimetic analogues of the nicotinamide nucleotide coenzymes NAD(P)(H) have been developed based on the structure of a triazine dye template. These biomimetic redox coenzymes are relatively straightforward and inexpensive to synthesise and display NAD+-like activity with different dehydrogenases, despite their apparently minimal structural similarity to the native coenzyme NAD+. Horse liver alcohol dehydrogenase oxidises butan-1-ol, using the most active biomimetic coenzyme (Nap 1), with a k cat value an order of magnitude lower and a K m for the coenzyme two orders of magnitude higher than those using native NAD+. The enzymatically reduced biomimetic coenzymes may be reoxidised by phenazine methosulfate. We believe that these coenzymes may find applications in biotransformations and biosensors, and in the development of biomimetic catalysts where the redox enzyme itself is replaced by a synthetic binding site.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002530051455

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5

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Deviations from Fick's law in Lorentz gases (1997)

Lowe, C. P. ; Frenkel, D. ; Hoef, M. A.

Springer

Journal of statistical physics 87 (1997), S. 1229-1244

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ISSN: 1572-9613

Keywords: Lorentz models ; random media ; Burnett coefficients ; selfdynamic structure factor ; long-time tails ; computer simulation

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract We have calculated the self-dynamic structure factorF(k,t) for tagged particle motion in “hopping” Lorentz gases. We find evidence that, even at long times, the probability distribution function for the displacement of the particles is highly non-Gaussian. At very small values of the wave vector this manifests itself as the divergence of the Burnett coefficient (the fourth moment of the distribution never approaching a value characteristic of a Gaussian). At somewhat larger wave vectors we find thatF(k,t) decays algebraically, rather than exponentially as one would expect for a Gaussian. The precise form of this power-law decay depends on the nature of the scatterers making up the Lorentz gas. We find different power-law exponents for scatterers which exclude certain sites and scatterers which do not.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02181281

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6

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Resting metabolism of helodermatid lizards: allometric and ecological relationships (1994)

Beck, D. D. ; Lowe, C. H.

Springer

Journal of comparative physiology 164 (1994), S. 124-129

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ISSN: 1432-136X

Keywords: Metabolic rate ; Oxygen consumption ; Gilamonster ; Beaded lizard ; Heloderma

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract We measured metabolic rates at 15 and 25°C in 42 helodermatid lizards ranging in mass from 26 to 1616 g. No consistent repeatable daily rhythms of metabolism were detected. There were no significant differences in metabolic rates between the two species of Heloderma. The temperature coefficient for metabolism (Q 10) was 3.0 between 15 and 25°C. The mass exponent for helodermatids (0.69) differed significantly from the among-species mass exponent of 0.80 for all squamates combined. However, adult Heloderma had a mass exponent of 0.80. Rates of metabolism of adult helodermatids were lower than those of other squamate reptiles, and at 15°C periods of apnea contributed to a further reduction in metabolic rate. Our finding that helodermatids have low SMRs supports the hypothesis that ecology is important in influencing metabolic rate, and that “reclusive” squamates have lower rates of metabolism than do nonreclusive species.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00301653

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