共查询到20条相似文献,搜索用时 718 毫秒
1.
Mycosporine-like amino acids (MAAs), which occur in diverse taxonomic groups, exhibit in vivo absorption maxima between 310 nm
and 360 nm and may play a photoprotective role against ultraviolet (UV) exposure. Using cultures of colonial Phaeocystis antarctica, we examined the relationship between MAA concentration, in vivo UV absorption, photoprotective (carotenoid) and photosynthetic
pigments, and photosynthetically available radiation (PAR, 350–700 nm). UV absorption was high; chlorophyll-specific absorption,
a
*
ph, at 330 nm ranged from 0.06 to 0.41 m2/mg chlorophyll a. Values of a
*
ph (330) were 4–13 times greater than a
*
ph (676). Mycosporine-glycine, shinorine, and mycosporine-glycine valine are responsible for the strong in vivo UV absorption.
The sum of all MAAs increased with irradiance when normalized to chlorophyll a or carbon concentrations, whereas individual MAAs varied independently from each other. Mycosporine-glycine concentrations
showed no statistically significant change over the range of light intensities, whereas mycosporine-glycine and shinorine
concentrations increased at higher irradiances. The relative fluorescence yield for chlorophyll a was low in the UV region compared to the visible region, implying that absorbed UV radiation (<375 nm) is transferred inefficiently
to chlorophyll a in the reaction center. Quantitative estimates of UV screening by MAAs are attributed to elevated MAA concentrations and
increased diameter at high light.
Received: 31 March 1999 / Accepted: 13 July 2000 相似文献
2.
Angela F. McGaffin Stephen Nicol Patti Virtue Yasuo Hirano Tsuyoshi Matsuda Itaru Uchida Steven G. Candy So Kawaguchi 《Marine Biology》2011,158(8):1743-1755
Antarctic krill, Euphausia superba, hatched from eggs and maintained for four years, were sampled periodically for age-pigment analysis. Extractable pigments
from the eye and eyestalk ganglia were quantified using fluorescence intensity and standardised against protein. Three peak
fluorescence intensities were detected at wavelengths of excitation 280 nm, emission 625 nm (pigment 1); excitation 355 nm,
emission 510 nm (pigment 2); and excitation 463 nm, emission 620 nm (pigment 3). There was a positive correlation between
the quantity of pigments 1 and 3 and the age of Antarctic krill. A model was developed to predict age from pigment 3 and to
compare it with other age proxies (carapace length and eyeball diameter). The quantity of pigment 3 was the best predictor
of age. The pigment method can discriminate between similar sized krill aged 12 and 36 months. Age pigments provide an improved
tool for age estimation in Antarctic krill, particularly if used in conjunction with other demographic information. 相似文献
3.
Unai Iriarte-Velasco Jon I. Álvarez-Uriarte Juan R. González-Velasco 《Environmental Chemistry Letters》2006,4(4):243-247
Ultraviolet (UV) spectroscopy is a valid surrogate for monitoring the formation of disinfection by-products (DBPs). Sodium thiosulphate is commonly used to remove disinfectant residual. However, it produces interferences with absorbance in the UV region. Relationship between trihalomethane (THM) formation and differential UV absorbance (−ΔA
λ
) was explored in the presence of sodium thiosulphate. Chlorination of two synthetic and five natural waters was carried out. Sodium thiosulphate showed high UV absorption at 254 nm. This effect can be overcome selecting a higher wavelength. Optimum wavelength varied being about 290 nm for fulvic acid and 300 nm for humic acid type natural organic matter. Correlation between THMs formation and −ΔA
λ
was linear for all the analysed samples. Regression curves do not pass through zero indicating the existence of a threshold absorbance decreasment. Once it is surpassed THM release begins. Chlorination of surface waters showed that the presence of bromide significantly increases THMs vs. −ΔA
λ
slope. Furthermore, slope decreased with the aromaticity–hydrophobicity of organic matter. 相似文献
4.
The taxonomic status of the Montastraea annularis species complex is unclear. Much evidence has been accumulated to support the separation into 3 species, but the presence
of intermediate morphotypes and the apparent lack of effective reproductive barriers in some areas are yet unexplained. Several
authors have made a call for the introduction of new traits that can be used to resolve differences among closely related
coral species. We collected skeletal and tissue samples from corals within the M. annularis species complex (15 each of M. annularis, M. faveolata, and M. franksi) and 10 morphological intermediates from several reefs in the Florida Keys. Multivariate analysis of corallite skeletal measurements
supported the separation of the species complex into three taxa. We detected two main fluorescence emission peaks at 480 nm
(turquoise) and 515 nm (green) that were not distributed equally among the three species. Every M. annularis colony had a major turquoise fluorescence peak. Some had a weak green secondary fluorescence peak. Colonies of M. faveolata and M. franksi had either the green or turquoise fluorescence peak, but at significantly different frequencies. The intermediate morphotypes
proved to be highly heterogeneous with respect to both micromorphology and fluorescence, and their nature could not be fully
explained. We were not able to separate the three species using fluorescence characters alone, however this new trait does
increase our understanding of the taxonomic structure within the M. annularis species complex.
Received: 21 January 2000 / Accepted: 1 September 2000 相似文献
5.
At three stations in Bahamas waters, in 1989, 15 to 30% of all the dinoflagellates >20µm diameter observed in near-surface waters fluoresced green under blue excitation light, 55 to 66% fluoresced red, and the remainder did not fluoresce at all. The abundance of these green-fluorescing dinoflagellates ranged from ca 5 to 10 cells l–1 at the study sites. Under UV excitation, however, the dinoflagellates had a blue to blue-green appearance. Almost all the blue-green fluorescing dinoflagellates appeared to be heterotrophic, except for one species,Phalacroma rapa Stein, which also contained red-fluorescing (under blue light) chlorophylla. The emission spectra from all species examined were of three basic types. Type 1 typically had two fluorescence emission peaks (ca 440 and ca 510 nm). Type 2 spectra possessed one sharp peak at 495 nm. Spectra belonging to Type 3 had a broad peak around 470 to 480 nm. The green fluorescence thus is likely caused by different substances in individual species. The attempt to reconstitute observed spectra with nicotinamide adenine dinucleotide (NADH) and riboflavin 5-phosphate (FMN) solutions was unsuccessful. 相似文献
6.
The biochemical composition of vegetative cells and resting spores of Chaetoceros pseudocurvisetus Mangin was compared in cultures under various nutrient and light conditions. The cellular content of major nucleotides such
as AMP, ADP, ATP and UTP decreased in the order: vegetative cells, nutrient-starved (vegetative) cells and resting spores,
indicating that the general metabolism of resting spores is relatively inactive. ADP-glucose was only abundant in nutrient-starved
vegetative cells, suggesting metabolic imbalance in these cells. The chl a–specific fluorescence yield of vegetative cells grown under all culture conditions was low, but very high in resting spores.
The ratios of the cellular contents of diadinoxanthin to chl a and of diatoxanthin to chl a were higher in resting spores and nutrient-starved vegetative cells than in nutrient-replete vegetative cells. The diadinoxanthin–diatoxanthin
xanthophyll cycle was active in resting spores; the xanthophyll cycle was synchronized with a 14 h light:10 h dark photoperiod.
Also, the ratios of cellular content of diadinoxanthin and diatoxanthin to cellular content of chl a in resting spores were relatively high in high irradiance, and decreased gradually in conditions of darkness over long culture
periods. Under conditions of strong light and high temperature, most resting spores survived more than 40 d while nutrient-starved
vegetative cells died within 33 d. These results suggest that resting spore formation is a strategy for enhancing protection
and lowering metabolic rate for survival. These physiological changes accompanying spore formation enable resting spores not
only to overwinter but also to “oversummer” in the coastal euphotic layer.
Received: 23 March 1999 / Accepted: 11 August 1999 相似文献
7.
Giant clams form a symbiosis with photosynthetic algae of the genus Symbiodinium that reside in clam mantle tissue. The allometry of symbiont photosynthetic performance was investigated as a mechanism for
the increasing percentage of giant clam carbon respiratory requirements provided by symbionts as clam size increases. Chlorophyll
fluorescence measurements of symbionts of the giant clam Tridacna maxima were measured during experiments conducted in September of 2009 using specimens 0.5–200 g tissue wet weight (3–25 cm long),
collected from waters around southern Taiwan (N 21°36′, E 120°47′) from July to August of 2009. Light-dependent decreases
in effective quantum yield (∆F/F
m′) calculated as the noontime maximum excitation pressure over PSII (Q
m), relative electron transport rates (rETR), and dark-adapted maximum quantum yield (F
v/F
m) all varied as a quadratic function of clam size. Both Q
m and rETR increased as clam size increased up to ~10–50 g then decreased as clam size increased. F
v/F
m decreased as clam size increased up to ~5–50 g then increased as clam size increased. Chlorophyll fluorescence measurements
of rETR were positively correlated with gross primary production measured during chamber incubations. Overall, symbionts of
mid-sized clams ~5–50 g exhibited the highest light-dependent decreases in effective photosynthetic efficiencies, the highest
relative electron transport rates, and the lowest maximum photosynthetic efficiencies, and symbiont photosynthetic performance
is allometric with respect to host clam size. 相似文献
8.
Howard W. Mielke Chris R. Gonzales Elise Cahn Jessica Brumfield Eric T. Powell Paul W. MielkeJr 《Environmental geochemistry and health》2010,32(5):431-440
Arsenic (As) ranks first on the 2005 and 2007 hazardous substances priority lists compiled for the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA). This study describes two New Orleans soil As surveys: (1) a survey of
composite soil samples from 286 census tracts and (2) a field survey of soil As at 38 play areas associated with the presence
of chromated-copper-arsenate (CCA)-treated wood on residential and public properties. The survey of metropolitan New Orleans
soils revealed a median As content of 1.5 mg/kg (range <0.2–16.4) and no distinctive differences between the soils of the
city core and outlying areas. Play area accessible soils associated with CCA-treated wood (N = 32) had a median As of 57 mg/kg and 78% of the samples were ≥12 mg/kg, the Louisiana soil As standard. The field survey
of play areas for CCA-treated wood (N = 132 samples at 38 sites) was conducted with a portable energy-dispersive X-ray fluorescence (XRF) analyzer. Seventy-five
of 132 wood samples (56.8%) were deemed CCA-treated wood. Of the 38 play areas surveyed, 14 (36.8%) had CCA-treated wood.
A significant association (Fisher’s exact p-value = 0.348 × 10−6) was found between CCA-treated wood and soil As (N = 75). At one elementary school CCA-treated woodchips (As range 813–1,654 mg As/kg) covered the playgrounds. The situation
in New Orleans probably exists in play areas across the nation. These findings support a precautionary program for testing
soils and wood for hazardous substances at all play areas intended for children. 相似文献
9.
Chitobiase activity in the epidermis and hepatopancreas of the fiddler crab Uca pugilator during the molting cycle 总被引:5,自引:0,他引:5
The activity of chitobiase, also known as N-acetyl-β-glucosaminidase, in the epidermis and hepatopancreas of the fiddler crab Uca pugilator (Bosc, 1802), during the molting cycle, was investigated. A pH optimum of 5 to 6 was found for the enzymatic activity in
both the epidermis and hepatopancreas. The temperature optimum for epidermal and hepatopancreatic chitobiase activities was
50 to 60 °C. The K
m values for epidermal and hepatopancreatic chitobiase activities at 19 °C were 0.190 ± 0.027 and 0.203 ± 0.016 mM 4-methylumbelliferyl-N-acetyl-β-glucosaminide, respectively. Hepatopancreatic chitobiase activity was significantly higher than epidermal enzymatic
activity in all the molt cycle stages tested except Postmolt Stage A-B. Chitobiase activity varied significantly during the
molting cycle, with the epidermal enzymatic activity in Premolt Stage D3–4 significantly higher than in Stage C (intermolt) and Premolt Stage D0, whereas hepatopancreatic chitobiase activity in Premolt Stage D3–4 was significantly higher than in all other molt stages tested. The patterns of chitobiase activity in the epidermis and hepatopancreas
correlate well with the hemolymph titer of ecdysteroids in U. pugilator during the molting cycle; this suggests that chitobiase activity in both tissues is regulated at least in part by the steroid
molting hormones.
Received: 6 May 1998 / Accepted: 12 September 1998 相似文献
10.
Ostreobium sp. (Chlorophyta: Siphonales) can be found as green bands within the skeletal material of a number of stony corals in the Indo-Pacific and Caribbean regions. Many of these corals also contain symbiotic dinoflagellates in the overlaying coral polyps that effectively screen out all the typical photosynthetically active radiation from the algae in the green bands below. Ostreobium sp., nevertheless, grows photosynthetically. Its action spectrum and absorption spectrum have been shown to extend much further into the near infra-red compared to other green algae. In the present study, carried out in 1987, fluorescence excitation and emission spectra were measured in Ostreobium sp. and compared to spectra obtained from the green alga Ulva sp. and the brown alga Endarachne sp. Xanthophylls, probably siphonein and an unidentified xanthophyll probably related to siphonaxanthin, are photosynthetically active in Ostreobium sp., and can sensitize Photosystem II fluorescence at 688 nm and Photosystem I (PS I) fluorescence at 718 nm. The fluorescence emission spectra of Ostreobium sp. measured at 25° C and 77 K were not remarkably different from those of the green alga Ulva sp. Absorbance changes induced by light were measured in Ostreobium sp. from 670 to 750 nm and were like those normally seen in green plants except that, in addition to the minimum expected for the reaction-center chlorophyll of PS I (P700) at 703 nm, another minimum was seen at 730 nm. It is possible that this spectrumreflects the functioning of a reaction center of Photosystem I that has adapted to function in light highly enriched in far-red wavelengths.CIW-DPB Publication No. 1021 相似文献
11.
Experiments were performed to determine how ultraviolet radiation (UVR) in the environmentally relevant range affects development
of the sea urchin Strongylocentrotus droebachiensis (Müller) and whether mycosporine-like amino acids (MAAs), present in the early life stages, reduce UV-induced damage. Eggs,
embryos, and larvae contained five MAAs having absorption maxima ranging from 320 to 334 nm. Eggs contained principally shinorine
and porphyra-334, which absorb maximally at 334 nm and half-maximally at 312 and 348 nm, spanning much of the environmental
range of biologically effective UVR. Concentrations of MAAs remained constant in unirradiated embryos through the gastrula
stage, but decreased significantly in two-armed pluteus larvae. Daily exposure to combined photosynthetically active radiation
(PAR, 400–700 nm) and UVR did not affect the concentration of MAAs in these embryos up to the two-armed pluteus stage. Prism
larvae of sea urchins and the sand dollar Echinarachnius parma (Lamarck) did not accumulate shinorine from the surrounding seawater. Daily exposure of embryos to UVA (320–400 nm) and UVB
(295–320 nm) radiation in the presence of PAR induced delays and abnormalities during development, and removing UVB eliminated
this effect. Abnormalities in embryos included thickening of the blastoderm wall, filling of the blastocoel by abnormal cells,
exogastrulation, and formation of abnormal spicules. The percentage of embryos that developed normally was lower in batches
of embryos exposed to PAR + UVA + UVB, except in embryos from urchins maintained on MAA-rich diets. In all cases, the percentage
of PAR + UVA + UVB-exposed embryos that developed normally was positively related to the concentration of MAAs in eggs from
which the embryos developed. Thus, the MAAs found in S. droebachiensis embryos protect them against UVB-induced abnormalities during their development to at least the four-armed pluteus larval
stage.
Received: 8 May 2000 / Accepted: 29 September 2000 相似文献
12.
Spatial variations in the N2O emissions and denitrification potential of riparian buffer strips (RBS) in a polluted river were examined. The river received large pollutant inputs from urban runoff and wastewater discharge, resulting in impaired water quality in the river and downstream reservoir. The potential for nitrogen removal by RBS was evaluated by measuring in situ N2O emission fluxes in static closed chambers and sediment denitrification potentials with acetylene inhibition techniques. The results showed that N2O emission fluxes decreased from the upstream (16.39 μg/(m2·h)) to downstream (0.30 μg/(m2·h)) sites and from the water body to upland sites. The trend in decreasing N2O emission fluxes in the downstream direction was mainly associated with sediment/soil textures (clay loam→sandy soil) and sediment/soil water contents and was also related to the vegetation along the RBS and nutrients in the sediments/soils. The correlation coefficient was highest (r=0.769) between the N2O emission flux and sediment/soil water content. Sediment/soil denitrification potentials under N-amended and ambient conditions were higher (highest 32.86 mg/(kg·h)) for the upstream sites, which were consistent with in situ N2O flux rates. 相似文献
13.
We tested the rarely considered hypothesis that the ultraviolet portion (UVR, 280–400 nm) of the light spectrum affects patterns
of recruitment in reef-building corals. The premise for this hypothesis rests in the fact that biologically relevant intensities
of UVR penetrate to considerable depths (>24 m) in the clear waters surrounding many coral reefs, and that reef organisms
allocate substantial resources to prevent and repair UVR damage. The ability of larvae spawned by the brown morph of the Caribbean
coral, Porites astreoides, to detect and avoid UVR was assessed in petri dishes where one-half of the dish was shielded from UVR and the other exposed.
Observations made every 30 min between 10:30 and 13:30 h showed significantly higher densities of larvae swimming in regions
shielded from UVR. To determine how this behavior affects settlement patterns, larvae collected from P. astreoides adults at 18 m depth were released into chambers deployed at 17 m depth where they were given a choice of three different
light regions in which to settle: PAR (PAR=400–700 nm), PAR+UVAR (UVAR=320–400 nm), and PAR+UVAR+UVBR (UVBR=280–320 nm). At
the end of the experiment, greater numbers of P. astreoides larvae had settled in the region of the tube where UVR was reduced than would be expected if dispersion were random. To our
knowledge, this is the first demonstration in any reef-building coral species that planula larvae can detect UVR and that
it affects their choice of a settlement site. These results indicate that the capacity to detect and avoid habitats with biologically
damaging levels of UVR may be one factor contributing to the successful recruitment of coral larvae. 相似文献
14.
Genetic differentiation among populations of a broadcast spawning soft coral, Sinularia flexibilis, on the Great Barrier Reef 总被引:2,自引:0,他引:2
The genetic structure of 12 reef populations of the soft coral Sinularia flexibilis (Octocorallia, Alcyoniidae) was studied along the Great Barrier Reef (GBR) at a maximum separation of 1,300 km to investigate
the relative importance of sexual and asexual reproduction, genetic differentiation and gene flow among these populations.
S. flexibilis is a widely distributed Indo-Pacific species and a gamete broadcaster that can form large aggregations of colonies on near-shore
reefs of the GBR. Up to 60 individuals per reef were collected at a minimum sampling scale of 5 m at two sites per reef, from
December 1998 to February 2000. Electrophoretic analyses of nine polymorphic allozymes indicated that genotypic frequencies
in most populations and loci did not differ significantly from those expected from Hardy–Weinberg predictions. Analysis of
multi-locus genotypes indicated a high number of unique genotypes (N
go) relative to the number of individuals sampled (N) in each reef population (range of 0.69–0.95). The maximum number of individuals likely to have been produced sexually (N*) was similar to the number of individuals sampled (i.e. N*:N ˜ 1), suggesting that even repeated genotypes may have been produced sexually. These results demonstrated a dominant role
of sexual reproduction in these populations at the scale sampled. Significant genetic differentiation between some populations
indicated that gene flow is restricted between some reefs (F
ST=0.026, 95% CI= 0.011 − 0.045) and even between sites within reefs (F
ST=0.041, 95% CI=0.027 − 0.055). Nevertheless, there was no relationship between geographic separation and genetic differentiation.
Analyses comparing groups of populations showed no significant differentiation on a north-south gradient in the GBR. The pattern
in the number of significant differences in gene frequencies in pairwise population comparisons, however, suggested that gene
flow may be more restricted among inner-shelf reef populations near to the coast than among mid/outer-shelf populations further
from the coast.
Received: 10 July 2000 / Accepted: 5 October 2000 相似文献
15.
Glenn Lurman Till Blaser Miles Lamare Koh-Siang Tan Hans Poertner Lloyd S. Peck Simon A. Morley 《Marine Biology》2010,157(8):1705-1712
Temperature and mitochondrial plasticity are well studied in fishes, but little is known about this relationship in invertebrates.
The effects of habitat temperature on mitochondrial ultrastructure were examined in three con-familial limpets from the Antarctic
(Nacella concinna), New Zealand (Cellana ornata), and Singapore (Cellana radiata). The effects of seasonal changes in temperature were also examined in winter and summer C. ornata. Stereological methods showed that limpet pedal myocytes were 1–2 orders of magnitude smaller in diameter (≈3.5 μm) than
in vertebrates, and that the diameter did not vary as a function of temperature. Mitochondrial volume density (Vv(mt,f)) was approximately 2–4 times higher in N. concinna (0.024) than in the other species (0.01 and 0.006), which were not significantly different from each other. Mitochondrial
cristae surface density (Sv(im,mt)) was significantly lower in summer C. ornata (24.1 ± 0.50 μm2 μm−3) than both winter C. ornata (32.3 ± 0.95 μm2 μm−3) and N. concinna (34.3 ± 4.43 μm2 μm−3). The surface area of mitochondrial cristae per unit fibre volume was significantly higher in N. concinna, due largely to the greater mitochondrial volume density. These results and previous studies indicate that mitochondrial
proliferation in the cold is a common, but not universal response by different species from different thermal habitats. Seasonal
temperature decreases on the other hand, leading preferentially to an increase in cristae surface density. Stereological measures
also showed that energetic reserves, i.e. lipid droplets and glycogen in the pedal muscle changed greatly with season and
species. This was most likely related to gametogenesis and spawning. 相似文献
16.
Genetic variation in 15 Holothuria (Microthele) nobilis (Selenka, 1867) populations on the Great Barrier Reef was studied at seven polymorphic allozyme loci. Although populations
were separated by distances up to 1300 km, there were no apparent restrictions to gene flow (F
ST
values were not significantly different from 0) and the maximum Nei's unbiased genetic distance was 0.003. Populations were
in Hardy–Weinberg equilibrium at all loci. The estimated maximum sexual input [this is the ratio of the number of sexually
produced individuals (N*) to the sample size (N
i
)] and the minimum sexual input [this is the ratio of the number of genotypes (N
go
) over the sample size (N
i
)] were used as estimators for the amount of asexual reproduction. Both parameters suggested that H. nobilis reproduces solely by sexual means (N*:N
i
: = 1; N
go
:N
i
= 0.74 to 1). The allozyme data indicated high gene flow between populations, but the possibility that allozyme frequencies
may not be at equilibrium means that it was not possible to distinguish whether the patterns reflect present-day dispersal
or dispersal that occurred in the past.
Received: 27 March 2000 / Accepted: 29 June 2000 相似文献
17.
Effects of diurnal variation in phytoplankton photosynthesis on estimating daily primary production (DPP) were examined using field data from Sagami Bay, Japan. DPP at 5 m depth was calculated from the continuous data of chlorophyll a (Chl a) and light intensity monitored by a natural fluorescence sensor with and without considering time-dependent changes in the photosynthesis–irradiance (P–E) relationship. Chl a could be estimated from natural fluorescence examining the variations in the quantum yield of fluorescence (φ
f) and Chl a-specific light absorption coefficient (a*ph), and relating them to Chl a. The P–E relationship was determined by water sampling three times daily. A distinct diurnal pattern was observed for the maximum photosynthetic rate (P*max), being maximal at noon, while periodicity of the maximum light utilization coefficient (α*) was less obvious. The actual DPP was calculated by interpolating the P–E parameters from those obtained at dawn, noon, and dusk. For comparison, DPP was calculated by fixing the P–E parameters as the constants measured at dawn, noon or dusk for a day. The difference from the actual DPP was small when the P–E parameters measured at dawn (3% on average) and noon (5%) were used as the constants for a day. The difference was largest when the values at dusk were used (−43%). The medium values of P*max at dawn, its low values at dusk, and the fact that a major part of the DPP was produced around noon were responsible for these results. The present study demonstrates that measurement of the P–E parameters at dawn or noon can give a good estimation of DPP from natural fluorescence. 相似文献
18.
Joana Figueiredo Gil Penha-Lopes Justin Anto Luís Narciso Junda Lin 《Marine Biology》2008,154(2):287-294
The present work is a comprehensive study of reproduction and embryonic development of Armases cinereum. Ovigerous A. cinereum (Bosc, 1802) females from Sebastian Inlet, Florida (9.88–19.4 mm CW) lay 2,000–12,000 eggs per brood, depending on their
CW (mm): fecundity = 24.662 CW1.9432. A. cinereum displayed significant brood loss through development (ca. 500 eggs per brood) independently from their CW (no senescence).
However, since smaller females lay fewer eggs than larger ones, the percentage of eggs lost during embryonic development is
greater in smaller females. The number of eggs carried on a later stage of development (potential fertility = 5.5593 CW2.4417) is a more accurate estimate of the reproductive output and subsequent recruitment. Egg volume increased during development
(64%, 0.025–0.041 mm3 or 0.36–0.43 mm of diameter, N = 270) and was strongly correlated with egg water content increase (19.21%, r = 0.89). Lipids, particularly fatty acids, seem to be the major energy source for embryonic development, decreasing 56.31
and 37.08% (respectively) during embryonic development; both are negatively correlated with egg volume (r = −0.90). The utilization of fatty acids through the different developmental stages of A. cinereum is presented. The most consumed fatty acids are the monounsatured (43.33 μg mg−1 dw), followed by the saturated (29.91 μg mg−1 dw) and polyunsaturated (24.03 μg mg−1). Palmitic (16:0) and linoleic (18:2n-6) acids are preferentially consumed (19.5 and 17.9 μg mg−1 dw, respectively). The high proportion of essential polyunsaturated fatty acids of C18 and C20 reflects the consumption of primary producers such as mangrove leaves. EPA/DHA ratio (2.85–3.84) and low DHA content indicated
that this species appears in a medium-low level of the trophic chain. The low ratio of 18:1n-7/18:1n-9 and high percentage of 18:1n-9 (marker of carnivory) may be a sign of the consumption of juvenile invertebrates. The high
percentage of odd-numbered FA indicated the occurrence of detritivores/scavenger behaviours. The fatty acid composition of
the eggs reflects adult feeding ecology (omnivorous) and habitat. 相似文献
19.
Ivo H. Machatschke Barbara E. Bauer Cornelia Schrauf John Dittami Bernard Wallner 《Behavioral ecology and sociobiology》2008,62(8):1341-1350
Polygynous mating systems can inflict considerable costs on males, often causing the emergence of alternative mating strategies
to ensure reproductive success. These strategies can lead to different morphs of color, size, or behavior. The present work
was done on guinea pigs, a polygynous rodent species. Some males can show a reduced readiness for conflict, perhaps employing
an alternative mating strategy. To test this hypothesis, a two-stage experiment was set up, with males (N = 16) and females (N = 16) initially living in isosexual groups. Visual and olfactory contact was possible through a wire mesh. Male agonistic
behavior was observed for 15 days, confirming the existence of less-conflict-involved (LCI, N = 7) and more-conflict-involved males (MCI, N = 9). Significant differences were found for a conditional parameter, body mass, and a morphometric one, testis width: LCI
consistently surpassed MCI. Hormonally, cortisol was comparable, while testosterone was distinctly higher in MCI. Next, males
and females were joined and observed for further 24 days. Males initially lost weight but reached original mass towards the
end of the experiment. Testis width patterns were similar. Again, LCI had higher body mass. Cortisol was comparable, but testosterone
release 3 days after merging was significantly higher in LCI. Behaviorally, LCI exhibited significantly less male–male aggression
and more socio-sexual behavior than MCI. The former were more successful, with 57% capable of accessing females, in contrast
to 11% of MCI. The existence of two distinct behavioral phenotypes in guinea pig males suggests that different reproductive
strategies may exist in this species. 相似文献
20.
Sherry L. Krayesky Janna L. Mahoney Katherine M. Kinler Stacey Peltier Warnesha Calais Kate Allaire Glen M. Watson 《Marine Biology》2010,157(5):1041-1047
Test probes were touched to tentacles to investigate whether discharge of spirocysts likely is regulated by hair bundle mechanoreceptors.
Significantly more spirocysts discharge onto test probes in the presence of vibrations at 11–15 Hz as compared to 0 Hz. Adding
N-acetylneuraminic acid, NANA, shifts maximal discharge of spirocysts upwards to 36–40 Hz, and possibly to 21–25 Hz. In contrast,
NANA shifts maximal discharge of basitrichous isorhiza nematocysts downwards to 1–20 Hz. Thus, discharge of cnidae (‘stinging
capsules’) is differentially regulated according to the type of cnida. Furthermore, it appears that chemodetection of N-acetylated sugars is not a prerequisite to capturing prey because, in seawater alone, maximal discharge of cnidae occurs
at frequencies overlapping movements of calmly swimming prey. Nevertheless, chemodetection of N-acetylated sugars broadens the range of frequencies stimulating maximal discharge of cnidae and, therefore, likely enhances
prey capture. 相似文献