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1.
The feeding dynamics and oxygen uptake of the bottom-dwelling caridean shrimp Nauticaris marionis were studied during the April/May 1984, 1996 and 1997 cruises to Marion Island (Prince Edward Islands, Southern Ocean). N. marionis is thought to have an opportunistic feeding mode. Prey composition varied considerably between the years and sites investigated.
Overall, benthic (mainly hydrozoans and bottom-dwelling polychaetes) and, at times, pelagic (largely euphausiids and copepods)
prey items dominated in the stomachs of N. marionis both by occurrence and by volume. Generally, pelagic prey contributed more to the diets of smaller shrimps, while benthic
prey was a more important component in the guts of larger specimens. Wet, dry and ash-free dry weight were determined for
specimens used in respiration experiments. The respiration rates of N. marionis females with carapace length 6.6–11.1 mm ranged from 80 to 250 μl O2 individual−1 · h−1, or from 0.588 to 2.756 μl O2 · mg−1 dry weight h−1. Regression analyses showed highly significant correlations between oxygen consumption and carapace length for N. marionis. Daily ingestion rates estimated using an in situ gut content analysis technique (4.4% of body dry weight) and an energy budget approach (average 4.7% of body dry weight,
range 2.0–7.5%) showed good agreement with each other.
Accepted: 29 July 1998 相似文献
2.
The carbon-flux via algal bloom events involves bacteria as an important mediator. The present study, carried out during the
spring inter-monsoon month of April 2008 onboard CRV Sagar Manjusha-06 in the Eastern Arabian Sea, addresses the bloom-specific
flow of carbon to bacteria via chromophoric dissolved organic matter (CDOM). Eleven stations monitored were located in the
coastal, shelf and open-ocean areas off Ratnagiri (16°59′N, 73°17′E), Goa (15°30′N, 73°48′E) and Bhatkal (13°58′N, 74°33′E)
coasts. Visible bloom of “saw-dust” color in the Ratnagiri shelf were microscopically examined and the presence of cyanobacteria
Trichodesmium erythraeum and T. thieabautii with cell concentrations as high as 3.05 × 106 trichomes L−1 was recorded. Total bacterial counts (TBC) varied between 94.09 × 108 cells L−1 in the bloom to 1.34 × 108 cells L−1 in the non-bloom area. Chromophoric dissolved organic matter (CDOM) concentrations averaged 2.27 ± 3.02 m−1 (absorption coefficient 325 nm) in the bloom to 0.28 ± 0.07 m−1 in the non-bloom waters respectively. CDOM composition varied from a higher molecular size with lower aromaticity in the
bloom to lower molecular size and increased aromaticity in the non-bloom areas respectively. Strong positive relationship
of TBC with Chlorophyll a (R
2 = 0.65, p < 0.01) and CDOM concentrations (R
2 = 0.8373, p = 0.01) in the bloom area indicated hydrolysis and/or uptake of CDOM by bacteria. Absorption by mycosporine-like amino acid
palythene (λ
max = 360 nm) was recorded in the filtrate of bloom. Morphotypes of Trichodesmium-associated bacteria revealed a higher frequency of Gram-positive rods. The role of bacteria in relation to changing CDOM
nature and as a factor in affecting oxygen content of the water column is discussed in context of the Arabian Sea. 相似文献
3.
The growth rate, reproductive aspects, and natural mortality of chimaeras and ratfish are poorly known. In this study, life-history
parameters for cockfish Callorhinchus callorhynchus (Holocephali—Callorhinchidae) are estimated, which is an important fish resource exploited in Chile. Specimens were sampled
from the artisanal fishery captures, from November 2006 to November 2007. The standard length (SL) of males fluctuated between
20 and 62 cm, and between 21 and 70 cm for females. Von Bertalanffy growth parameters were estimated through length-frequency
data analysis using MULTIFAN. The length-weight relationship and von Bertalanffy growth parameters were significantly different
for males and females, as well as the length at 50% maturity. For males a model with 5 age-classes was the best, with asymptotic
length L
∞ = 52 cm SL, growth coefficient K = 0.473 yr−1, and age at length zero t
0 = −0.690 yrs. For females the best model was represented by 10 age-classes (L
∞ = 70.3 cm SL, K = 0.193 yr−1, t
0 = −1.158 yrs) in the length-frequency data sets. Length at 50% maturity of males was estimated in 43.7 cm SL, and in 50.2 cm
SL for females. The natural mortality rate fluctuated between 0.42 and 0.82 yr−1 for males and between 0.12 and 0.37 yr−1 for females, depending upon the method used. It is concluded that C. callorhynchus is a species with life-history parameters significantly different between males and females, and such differences should
be taken into account in future population dynamics analysis. 相似文献
4.
Gianantonio Battistuzzi Lodovica Loschi Marco Borsari M. Sola 《Journal of biological inorganic chemistry》1999,4(5):601-607
The effects of the ionic atmosphere on the enthalpic and entropic contributions to the reduction potential of native (state
III) beef heart cytochrome c have been determined through variable-temperature direct electrochemistry experiments. At neutral or slightly alkaline pH
values, from 5 to 50 °C, the reduction enthalpy and entropy become less negative with decreasing ionic strength. The reduction
entropy extrapolated at null ionic strength is approximately zero, indicating that, in the absence of the screening effects
of the salt ions on the network of the electrostatic interactions at the protein-solvent interface, the solvation properties
and the conformational flexibility of the two redox states are comparable. The moderate decrease in E°′ observed with increasing ionic strength [ΔE°′IS =(E°′)
I
=0.1 M–(E°′)
I
=0 M=–0.035 V at 25 °C], once the compensating enthalpic and entropic effects of the salt-induced changes in the hydrogen bonding
within the hydration sphere of the molecule in the two redox states are factorized out, results in being ultimately determined
by the stabilizing enthalpic effect of the negatively charged ionic atmosphere on the ferri form. At pH 9, the ionic strength
dependence of the reduction termodynamics of cytochrome c follows distinctive patterns, possibly as a result of specific binding of the hydroxide ion to the protein. A decrease in
ionic strength at constant pH, as well as a pH increase at constant ionic strength, induces a depression of the temperature
of the transition from the low-T to high-T conformer of cytochrome c, which suggests that a temperature-induced decrease in the pK
a for a residue deprotonation is the key event of this conformational change.
Received: 7 April 1999 / Accepted: 19 July 1999 相似文献
5.
Atsushi Nanami Takeo Kurihara Yutaka Kurita Yoshimasa Aonuma Nobuaki Suzuki Hideaki Yamada 《Ichthyological Research》2010,57(3):240-244
The humpback red snapper Lutjanus gibbus (Lutjanidae) is an important species for fisheries in the Kagoshima and Okinawan region of Japan. The present study estimated
the age, growth and reproduction of this lutjanid species in the waters around Ishigaki Island, southern part of Okinawa.
An opaque zone was formed on the otolith every year, and this formation correlated with their spawning season; these zones
were identified as annual rings. Maximum ages of 21 and 24 years were observed for males and females, respectively. The von
Bertalanffy growth parameters clarifying the age–fork length relationship were as follows: L
∞ = 390.5 mm, K = 0.210 year−1 and t
0 = −1.88 year for males, and L
∞ = 303.4, K = 0.256 year−1 and t
0 = −3.05 year for females. The main spawning season was estimated as between May and October, since greater values of gonadosomatic
index for females as well as maturation oocytes and/or postovulatory follicles were observed during those six months. 相似文献
6.
Schizopygopsis younghusbandi younghusbandi is an endemic species whose distribution is restricted to the middle reaches of the Yarlung Zangbo River, being one of the
most important commercial fishes in this area. Age and growth of 606 specimens captured between October 2002 and April 2005
were studied. The range in standard length (L) was 65.7–387.3 mm and total weight (W) was 3.3–772.0 g. The relationship between
L and W was W = 0.000909L2.2493 for males and W = 0.000259L2.4781 for females. Age, determined from anal scales and lapillus otoliths, ranged from 3 to 18 years. The parameters of von Bertalanffy
growth functions, estimated by back-calculated length, were L¥ = 442.7mm LL_\infty = 442.7mm\;L, k = 0.0738 year−1 and t
0
= −1.4 year for males, and L¥ = 471.4mm LL_\infty = 471.4mm\;L, k = 0.0789 year−1 and t
0 = 0.2 year for females. Males and females exhibited statistically significant differences in growth. χ
2-test indicated that von Bertalanffy growth functions could well describe the growth of S. y. younghusbandi. The longevities were 39.2 and 38.2 years for males and females, respectively. Growth inflexion points were 10.2 and 12.0 years
for males and females, respectively, but 84.8% of the captures were at the smaller ages. So conservation and management schemes
for this population should be considered urgently. In addition, we found that populations from the upstream of the Lhasa River,
the downstream of the Lhasa River and the middle reaches of the Yarlung Zangbo River showed statistically significant differences
in growth patterns. 相似文献
7.
Matthew T. Craig 《Ichthyological Research》2007,54(1):81-84
A preliminary analysis of 175 specimens of the white-streaked grouper, Epinephelus ongus (Serranidae), was undertaken to determine life history characteristics of the species. Sagittal otoliths, stomachs, and a
subsample of gonads were removed to determine age at length, diet, and reproductive strategy. The von Bertalanffy growth equation
was used to describe growth in this species and yielded the growth parameters L∞ = 438.3, K = 0.04334, and t0 = −8.752. Fish ranged in age from 1 to 20 years. Diet was consistent with other serranid species and included crabs, shrimps,
octopi, and fishes. Based on a very limited number of specimens (n = 12), the larger size and older age of males compared to females suggests that E. ongus may be a protogynous hermaphrodite. 相似文献
8.
S. Benini Marco Borsari S. Ciurli Alexander Dikiy M. Lamborghini 《Journal of biological inorganic chemistry》1998,3(4):371-382
Direct cyclic voltammetry and 1H NMR spectroscopy have been combined to investigate the electrochemical and spectroscopic properties of cytochrome c
553 isolated from the alkaliphilic soil bacterium Bacillus pasteurii. A quasi-reversible diffusion-controlled redox process is exhibited by cytochrome c
553 at a pyrolitic graphite edge microelectrode. The temperature dependence of the reduction potential, measured using a non-isothermal
electrochemical cell, revealed a discontinuity at 308 K. The thermodynamic parameters determined in the low-temperature range
(275–308 K;ΔS°′=–162.7±1.2 J mol–1 K–1, ΔH°′=–53.0±0.5 kJ mol–1, ΔG°′=–4.5±0.1 kJ mol–1, E°′=+47.0±0.6 mV) indicate the presence of large enthalpic and entropic effects, leading, respectively, to stabilization and
destabilization of the reduced form of cytochrome c
553. Both effects are more accentuated in the high-temperature range (308–323 K;ΔS°′=–294.1±8.4 J mol–1 K–1, ΔH°′=–93.4±3.1 kJ mol–1, ΔG°′=–5.8±0.6 kJ mol–1, E°′=+60.3±5.8 mV), with the net result being a slight increase of the standard reduction potential. These thermodynamic parameters
are interpreted using the compensation theory of hydration of biopolymers as indicating the extrusion, upon reduction, of
water molecules from the hydration sphere of the cytochrome. The low-T and high-T conformers differ by the number of water molecules in the solvation sphere: in the high-T conformer, the number of water molecules extruded upon reduction increases, as compared to the low-T conformer. The ionic strength dependence of the reduction potential at 298 K, treated within the frame of extended Debye-Hückel
theory, yields values of E
°′
(I=0)
=–25.4±1.4 mV, z
red=–11.3, and z
ox=–10.3. The pH dependence of the reduction potential at 298 K shows a plateau in the pH range 7–10 and an increase at more
acidic pH, allowing the calculation of pK
O=5.5 and pK
R=5.7, together with the estimate of the reduction potentials of completely protonated (+71 mV) and deprotonated (+58 mV) forms
of cytochrome c
553. 1H NMR spectra of the oxidized paramagnetic cytochrome c
553 indicate the presence of a His-Met axial coordination of the low-spin (S=1/2) heme iron, which is maintained in the temperature interval 288–340 K at pH 7 and in the pH range 4.8–10.0 at 298 K.
The temperature dependence of the hyperfine-shifted signals shows both Curie-type and anti-Curie-type behavior, with marked
deviations from linearity, interpreted as indicating the presence of a fast equilibrium between the low-T and high-T conformers, having slightly different heme electronic structures resulting from the T-induced conformational change. Increasing the NaCl concentration in the range 0–0.2 M causes a slight change of the 1H NMR chemical shifts of the hyperfine-shifted signals, with no influence on their linewidth. The calculated lower limit value
of the apparent affinity constant for specific ion binding is estimated as 5.2±1.1 M–1. The pH dependence of the isotropically shifted 1H NMR signals of the oxidized cytochrome displays at least one ionization step with pK
O=5.7. The thermodynamic and spectroscopic data indicate a large solvent-derived entropic effect as the main cause for the
observed low reduction potential of B. pasteurii cytochrome c
553.
Received: 9 January 1998 / Accepted: 8 April 1998 相似文献
9.
Sara Persson Britt-Marie Bäcklin Hans Kindahl Björn Brunström Ulf Magnusson 《European Journal of Wildlife Research》2011,57(5):1057-1063
The objectives of this study on the reproductive system of wild male mink (Neovison vison) were to determine the influence of age, nutritional status and season on reproductive traits and to produce baseline data
that may be used in environmental monitoring programmes. The 117 male mink included in the study were killed by hunters all
over Sweden (from latitude 56° N to 67° N) during August to the end of April from 2005 to 2008. The weights of penis, testes,
and epididymides were lower, the anogenital distance was shorter and the diameter of seminiferous tubules was less in juveniles
compared with adult mink (p < 0.0001–p = 0.0024). There was a positive effect (p < 0.05) of nutritional status on the baculum length and on the anogenital distance, but not on any of the other reproductive
traits. The season of sampling influenced the penis, testes and epididymes weights and the diameter of seminiferous tubules
(p = 0.008–p < 0.0001). During spring, 86% of the mink had sperm in their epididymides, whereas the corresponding figure for autumn was
3%; in addition, when the average diameter of the tubules reached 138 μm, sperm were present in the epididymides. Sperm morphology
was analysed in 29 of the mink, and the percentage of morphologically defect sperm were generally low. Taken together, this
study suggests that when assessing male reproductive data in wild mink populations, season must be taken into account as well
as whether the individuals are juvenile or adult. In contrast, the nutritional status seems not to be of any major significance. 相似文献
10.
Since fishery management regulations have shifted much of the groundfish trawl effort in the northeastern Pacific from the
continental shelf to the slope, fishery impacts on unassessed demersal slope rockfish species like the aurora rockfish (Sebastes aurora) may have increased. Understanding the life history of these species is a critical first step in developing management strategies
to protect them from overharvest. In this study we employ cross-dating methods to validate the annual periodicity of growth
increments and investigate the age, growth and maturity of aurora rockfish, a species for which life history information is
quite limited. Specimens were collected on an opportunistic basis from Oregon commercial landings and from research cruises,
over the years 2003–2006. Age was estimated for 438 individuals using otoliths processed via the break-and-burn method. The
maximum estimated age was 118 years for females (n = 324) and 81 years for males (n = 114). The von Bertalanffy growth function showed that males grow faster and reach a smaller maximum size than females (males:
L
inf = 34, K = 0.09, t
0 = −1.9; females: L
inf = 37, K = 0.06, t
0 = −5.5), though both sexes demonstrate relatively slow growth. Visual assessment of ovaries showed that the aurora rockfish
is a synchronous spawner with parturition occurring in May and June off Oregon. Female age and length at 50% maturity were
calculated at 12.6 years and 26 cm, respectively (n = 307). Maturity and age data provided evidence for a protracted adolescence in this species. 相似文献
11.
Herbert R. L. Drouin 《European biophysics journal : EBJ》1999,28(7):600-604
A new ion-selective liquid membrane microelectrode, based on the neutral carrier 1,1′-bis(2,3-naphtho-18-crown-6), is described
that shows the dependence of EMF on the activity of divalent putrescine cations a
Put, with the linear slope s
Put = 26 ± 3 mV/decade (mean ± SD, N = 18), in the range 10−4–10−1 M at 25 ± 1 °C. Values of potentiometric putrescine cation selectivity coefficients of logK
Pot
Put
j
(mean ± SD, N) are obtained by the separate solution method for the ions K+ (1.0 ± 0.4, 10), Na+ (−1.2 ± 0.4, 8), Ca2+ (−2.3 ± 0.5, 10) and Mg2+ (−2.5 ± 0.5, 7). The microelectrode can be applied for the direct analysis of the activities of free divalent putrescine
cations in the range 5 × 10−4 to 10−1 M in an extracellular ionic environment. Established analytical methods, e.g. high performance liquid chromatography, determine
the total concentration of the derivatives of free and bound putrescine.
Received: 20 December 1998 / Revised version: 7 May 1999 / Accepted: 27 May 1999 相似文献
12.
Nelusetta ayraudi (the ocean leatherjacket) is an endemic Australian monacanthid species distributed from North West Cape (Western Australia)
south to southern Queensland. The commercial and recreational fisheries targeting Nelusetta ayraudi have expanded substantially along the coast of New South Wales (NSW) in recent years but there exists little biological information
on which to base effective management of this growing fishery. World-wide, only a few studies have aged monacanthids. Of these,
researchers have interpreted periodic increments in bony structures such as vertebrae and anterior dorsal spines in preference
to those found in otoliths. In this study we estimated age of N. ayraudi by counting growth increments in sectioned otoliths. The periodicity of increment formation was validated using a vital stain,
(oxy-tetracycline), injected into young-of-the-year fish. Growth was rapid especially as juveniles with N. ayraudi attaining approximately 220 mm after 1 year and 340 mm after 2 years. No differences in growth rates were detected between
sexes or between fish captured at different latitudes (zones). The largest male (605 mm, Total Length—TL) and female (656 mm,
TL) were both recorded from northern NSW, with both sexes attaining the maximum age of 6+ years from northern and southern
NSW. The von Bertalanffy parameters describing growth for N. ayraudi were L¥ {L_\infty } = 591 mm (TL), k = 0.377 year−1 and t
o = −0.247 years. 相似文献
13.
Life history parameters associated with reproductive biology, age, and growth of the convict cichlid (also known as the zebra
cichlid) Amatitlania nigrofasciata, which was introduced into the Haebaru Reservoir on Okinawa-jima Island, were estimated using 437 specimens that ranged from
13.7 to 82.9 mm standard length (SL). Lengths of females at first maturity (SL) and 50% maturity (L
50) were estimated to be 32.2 and 37.3 mm SL, respectively. The spawning period continued throughout the year, with a peak spawning
cycle from March to May 2006–2007. Observations of postovulatory follicles and tertiary yolk stage oocytes indicate that convict
cichlids spawn multiple times within a year. Female cichlids that hatched during the peak spawning seasons matured after October
of the same year. Batch fecundity of females (32.2–61.2 mm SL) ranged from 65 to 345 (mean ± SD = 155 ± 63). Opaque zones
along the outer margins of otoliths formed annually. The maximum age of male and female cichlids was 3 years. The von Bertalanffy
growth formulae (VBGF) were expressed as Lt = 57.4( 1 - e - 0.78( t + 0.91 ) ) {{\hbox{L}}_{\rm{t}}}{ = 57}{.4}\left( {1 - {e^{ - 0.78\left( {t + 0.91} \right)}}} \right) for females and Lt = 69.5( 1 - e - 1.07( t + 0.24 ) ) {{\hbox{L}}_{\rm{t}}}{ = 69}{.5}\left( {1 - {e^{ - 1.07\left( {t + 0.24} \right)}}} \right) for males. Males grew larger than females beginning from the first year. Certain life history characteristics, such as year-round
spawning and early maturation, probably contributed to the successful establishment of the convict cichlid, and this species
in particular is thought to adapt and become established quickly upon introduction to freshwater systems on Okinawa-jima Island. 相似文献
14.
The seasonal variations in biomass, abundance and species composition of zooplankton in relation to hydrography and chlorophyll
a were studied in the subarctic waters north of Iceland. The sampling was carried out at approximately monthly intervals from
February 1993 to February 1994 at eight stations arranged along a transect extending from 66°16′N–18°50′W to 68°00′N–18°50′W.
The mean temperature at 50 m depth showed a clear seasonal pattern, with lowest water temperatures in February (∼1.1°C) and
the highest in July (∼5.4°C). The spring growth of the phytoplankton began in late March and culminated during mid-April (∼7.0 mg
Chl a m−3). Both the biomass and the abundance of total zooplankton were low during the winter and peaked once during the summer in
late May (∼4 g m−2 and ∼38,000 individuals m−2). A total of 42 species and taxonomic groups were identified in the samples. Eight taxa contributed ∼90% of the total zooplankton
number. Of these Calanus finmarchicus was by far the most abundant species (∼60% of the total zooplankton). Less important groups were ophiuroid larvae (∼9%),
Pseudocalanus spp. (∼8%), Metridia longa (∼4%), C. hyperboreus (∼3%), Acartia longiremis (∼2%), chaetognaths (∼2%) and euphausiid larvae (∼2%). The dominant copepods showed two main patterns in seasonal abundance:
C. finmarchicus, C. hyperboreus and C. glacialis had one annual peak in numbers in late May, while Pseudocalanus spp., M. longa and A. longiremis showed two maxima during the summer (July) and autumn (October/November). Ophiuroid larvae and chaetognaths (mainly Sagitta elegans) peaked during the middle of July, while the number of euphausiid eggs and larvae was greatest from May to July. The succession
in population structure of C. finmarchicus indicated its main spawning to be in April and May, coincident with the phytoplankton spring bloom. A minor spawning was
also observed sometime between August and October. However, the offspring from this second spawning contributed only insignificantly
to the overwintering stock of C. finmarchicus.
Received: 12 September 1997 / Accepted: 1 March 1998 相似文献
15.
16.
C. Immoos Michael G. Hill Donita Sanders James A. Fee Claire E. Slutter John H. Richards Harry B. Gray 《Journal of biological inorganic chemistry》1996,1(6):529-531
The electrochemistry of a water-soluble fragment from the CuA domain of Thermus thermophilus cytochrome ba
3
has been investigated. At 25 °C, CuA exhibits a reversible reduction at a pyridine-4-aldehydesemicarbazone-modified gold electrode (0.1 M Tris, pH 8) with E° = 0.24 V vs NHE. Thermodynamic parameters for the [Cu(Cys)2Cu]+/0 electrode reaction were determined by variable-temperature electrochemistry (ΔS°rc = –5.4(12) eu, ΔS° = –21.0(12) eu, ΔH° = –11.9(4) kcal/mol;ΔG° = –5.6 (11) kcal/mol). The relatively small reaction entropy is consistent with a low reorganization energy for [Cu(Cys)2Cu]+/0 electron transfer. An irreversible oxidation of [Cu(Cys)2Cu]+ at 1 V vs NHE confirms that the CuII:CuII state of CuA is significantly destabilized relative to the CuII state of analogous blue-copper proteins.
Received: 3 June 1996 / Accepted: 26 August 1996 相似文献
17.
Choi JH Niketić SR Djordjević I Clegg W Harrington RW 《Journal of molecular modeling》2012,18(5):2135-2146
The crystal structure of [Cr(edda)(acac)] (edda = ethylediamine-N,N′-diacetate; acac = acetylacetonato) has been determined
by a single crystal X-ray diffraction study at 150 K. The chromium ion is in a distorted octahedral environment coordinated
by two N and two O atoms of chelating edda and two O atoms of acac, resulting in s-cis configuration. The complex crystallizes in the space group P21/c of the monoclinic system in a cell of dimensions a = 10.2588(9), b = 15.801(3), c = 8.7015(11) ?, β =101.201(9)° and Z = 4.
The mean Cr-N(edda), Cr-O(edda) and Cr-O(acac) bond distances are 2.0829(14), 1.9678(11) and 1.9477(11) ? while the angles
O-Cr-O of edda and O-Cr-O of acac are 171.47(5) and 92.72(5)°, respectively. The crystal structure is stabilized by N–H⋯O
hydrogen bonds linking [Cr(edda)(acac)] molecules in distinct linear strands. The visible electronic and IR spectroscopic
properties are also discussed. An improved, physically more realistic force field, Vibrationally Optimized Force Field (VOFF),
capable of reproducing structural and vibrational properties of [Cr(edda)(acac)] was developed and its transferability demonstrated
on selected chromium(III) complexes with similar ligands. 相似文献
18.
Two beaked whales identified as Sowerby's beaked whale (Mesoplodon bidens) were observed in sea state 0–1 on 16 July 1995 at 71°30′N 04°00′E in the Norwegian Sea. A number of morphological features,
such as dentition, were clearly seen during the encounter. The Sowerby's beaked whale's core distribution is in the North
Sea and the previous northernmost sighting was made at 63°06′N 00°41′E. According to the literature, the species has never
been recorded in the polar zone. The sighting in the Norwegian Sea suggests that the current data on the species distribution
is uncertain, and that its range may include the polar waters of the Norwegian Sea.
Received: 24 April 1996 / Accepted: 25 August 1996 相似文献
19.
N. J. Adams B. Pinshow L. Z. Gannes H. Biebach 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(3):195-199
We examined the relationship between body temperature (Tb) of free flying pigeons and ambient water vapor pressure and temperature. Core or near core Tb of pigeons were measured using thermistors inserted into the cloaca and connected to small transmitters mounted on the tail
feathers of free flying tippler pigeons (Columba livia). Wet and dry bulb temperatures were measured using modified transmitters mounted onto free-flying pigeons. These allowed
calculation of relative humidity and hence water vapor pressure at flight altitudes. Mean Tb during flight was 42.0 ± 1.3 °C (n = 16). Paired comparisons of a subset of this data indicated that average in-flight Tb increased significantly by 1.2 ± 0.7 °C (n = 7) over that of birds at rest (t = −4.22, P < 0.05, n = 7) within the first 15 min of takeoff. In addition, there was a small but significant increase in Tb with increasing ambient air (Ta) when individuals on replicate flights (n = 35) were considered. Inclusion of water vapor pressure into the regression model did not improve the correlation between
body temperature and ambient conditions. Flight Tb also increased a small (0.5 °C) but significant amount (t = 2.827, P < 0.05, n = 8) from the beginning to the end of a flight. The small response of Tb to changing flight conditions presumably reflects the efficiency of convection as a heat loss mechanism during sustained
regular flight. The increase in Tb on landing that occurred in some birds was a probable consequence of a sudden reduction in convective heat loss.
Accepted: 2 February 1999 相似文献
20.
DNA binding by trans-[(H2O)(Pyr)(NH3)4RuII]2+ (Pyr=py, 3-phpy, 4-phpy, 3-bnpy, 4-bnpy) is highly selective for G7 with K
G=1.1×104 to 2.8×104, with the more hydrophobic Pyr ligands exhibiting slightly higher binding. A strong dependence on ionic strength indicates
that ion-pairing with DNA occurs prior to binding. At μ=0.05, d[RuII-DNA]/dt=k[RuII][DNA], where k=0.17–0.21 M–1 s–1 with the various Pyr ligands. The air oxidation of [(py)(NH3)4RuII]
n
-DNA to [(py)(NH3)4RuIII]
n
-DNA at pH 6 occurs with a pseudo-first-order rate constant of k
obs=5.6×10–4 s–1 at μ=0.1, T=25 °C. Strand cleavage of plasmid DNA appears to occur by both Fenton/Haber-Weiss chemistry and by base-catalyzed routes,
some of which are independent of oxygen. Base-catalyzed cleavage is more efficient than O2 activation at neutral pH and involves the disproportionation of covalently bound RuIII and, in the presence of O2, Ru-facilitated autoxidation to 8-oxoguanine. Disproportionation of [py(NH3)4RuIII]
n
-DNA occurs according to the rate law: d[RuII–GDNA]/dt=k
0[RuIII–GDNA]+k
1[RuIII–GDNA][OH–], where k
0=5.4×10–4 s–1 and k
1=8.8 M–1 s–1 at 25 °C, μ=0.1. The appearance of [(Gua)(py)(NH3)4RuIII] under argon, which occurs according to the rate law: d[RuIII–G]/dt=k
0[RuIII–GDNA]+k
1[OH–][RuIII–GDNA] (k
0=5.74×10–5 s–1, k
1=1.93×10–2 M–1 s–1 at T=25 °C, μ=0.1), is consistent with lysis of the N-glycosidic bond by RuIV-induced general acid hydrolysis. In air, the ratio of [Ru-8-OG]/[Ru-G] and their net rates of appearance are 1.7 at pH 11,
25 °C. Small amounts of phosphate glycolate indicate a minor oxidative pathway involving C4′ of the sugar. In air, a dynamic
steady-state system arises in which reduction of RuIV produces additional RuII.
Received: 11 November 1998 / Accepted: 3 March 1999 相似文献