共查询到20条相似文献,搜索用时 31 毫秒
1.
Mol S 《Biological trace element research》2011,143(2):974-982
Concentrations of selected metals were determined using ICP-MS in canned bonito, sardines and mackerel commercialized in Turkey.
Thirty samples and two different brands were sampled for each fish species. The minimum and maximum concentrations of trace
metals in canned bonito, sardines and mackerel were found as 0.000–34.742, 0.000–89.015, 0.000–28.725 mg/kg for iron, 2.388–26.620,
10.930–41.340, 4.778–29.270 mg/kg for zinc, 0.331–1.548, 0.599–2.242, 0.336–2.884 mg/kg for copper, 0.000–0.065, 0.000–0.113,
0.000–0.115 mg/kg for cadmium, 0.000–0.190, 0.000–0.158, 0.000–0.385 mg/kg for tin, 0.000–0.111, 0.000–0.223, 0.000–0.208 mg/kg
for mercury and 0.000–3.046, 0.000–2.875, 0.000–3.529 mg/kg for lead, respectively. These levels are similar those found in
other studies. Although the samples have concentrations within permissible limits for Zn, Cu, Sn and Hg, some of them contained
Fe, Cd and Pb above these limits. Periodical controls of metals in canned fish are essential both to protect human health
and to provide data on this subject. 相似文献
2.
E. I. Isaeva N. A. Mazurkova R. Ya. Podchernyayeva 《Applied Biochemistry and Microbiology》2011,47(8):723-729
Immunogenic properties of synthetic peptides corresponding to regions 122–133, 136–147, 154–164, and 314–328 of the heavy
chain (HA1) of A/Aichi/2/68 virus hemagglutinin were studied. Peptides 122–133 and 136–147 together form a nearly complete
antigenic determinant A, peptide 154–164 is a part of determinant B, and peptide 314–328 corresponds to the C-terminal HA1
fragment. In a model influenza A/Aichi/2/68 infection in CBA mice, a protective effect of conjugates of BSA with peptides
136–147 and 314–328 was shown. Immunization of animals with conjugates BSA-(136–147) and BSA-(314–328) in combination with
interferon inducers (larifan and ridostin) and a plant immunomodulator (immunomax) intensified the protection of mice against
the influenza infection. 相似文献
3.
Claire R. Quilter Sarah C. Blott Alan J. Mileham Nabeel A. Affara Carole A. Sargent Darren K. Griffin 《Mammalian genome》2002,13(10):588-594
A combination of FISH and RH mapping was used to study the evolution of sex chromosome genes in the pig. In total, 19 genes
were identified, including 3 PAR genes (STS, KAL, PRK). The gene order of the porcine X Chromosome (Chr) closely resembled
the human X Chr (PRK/STS/KAL–AMELX–EIF2s3X/ZFX–USP9X–DBX–SMCX), suggesting that the porcine X has undergone very little rearrangement
during evolution. For the porcine Y Chr, two linkage groups of 10 NRY genes were found, and the following order was established:
Ypter–(AMELY–EIF2S3Y/ZFY–USP9Y–DBY/UTY)–(TSPY–SMCY–UBE1Y–SRY)–CEN. This gene order showed greater conservation with the murine
Y than with the human Y Chr. In addition, all porcine Y Chr genes mapped to Yp, which is similar to the mouse and included
EIF2s3Y and UBE1Y, which are not present in humans. Interestingly, complete conservation of X/Y homologous gene order was
found between the pig X and Y Chrs, indicating that the porcine Y Chr has not undergone extensive reorganisation with respect
to the X. This suggests that the order of the X/Y homologous genes of the porcine X and Y Chrs may closely resemble the ancestral
gene order of the eutherian sex chromosomes. 相似文献
4.
Eighteen metals were estimated in the scalp hair samples from cancer patients (n = 111) and normal donors (n = 113). Nitric acid–perchloric acid wet digestion procedure was used for the quantification of the selected metals by flame
atomic absorption spectrophotometry. In the scalp hair of cancer patients, highest average levels were found for Ca (861 μg/g),
followed by Na (672 μg/g), Zn (411 μg/g), Mg (348 μg/g), Fe (154 μg/g), Sr (129 μg/g), and K (116 μg/g), whereas in comparison,
the dominant metals in the scalp hair of normal donors were Ca (568 μg/g), Zn (177 μg/g), Mg (154 μg/g), Fe (110 μg/g), and
Na (103 μg/g). The concentrations of Ca, Cd, Co, Cr, Fe, K, Mg, Mn, Na, Ni, Pb, Sb, Sr, and Zn were notably higher in the
hair of cancer patients as compared with normal donors, which may lead to a number of physiological disorders. Strong positive
correlations were found in Mn–Pb (0.83), Cd–Cr (0.82), Cd–Li (0.57), Fe–Pb (0.56), and Fe–Mn (0.55) in the hair of cancer
patients whereas Na–Cd, Li–Cr, Li–Co, Co–Cd, Li–Cd, Na–Co, Na–Li, Ca–Mg and Na–Cr exhibited strong relationships (r > 0.50) in the hair of normal donors. Principal Component Analysis (PCA) of the data revealed seven PCs, both for cancer
patients and normal donors, but with significantly different loadings. Cluster Analysis (CA) was also used to support the
PCA results. The study evidenced significantly different pattern of metal distribution in the hair of cancer patients in comparison
with normal donors. The role of trace metals in carcinogenesis was also discussed. 相似文献
5.
Bottaro Christina S. Kiceniuk Joe W. Chatt Amares 《Biological trace element research》1999,(1):149-166
Extractable organohalogens (EOX) are organic compounds that contain chlorine, bromine and/or iodine, which can be separated
from the matrix by liquid/liquid or liquid/solid extraction. A combination of instrumental neutron activation analysis (INAA)
and solvent extraction methods has been developed for the determination of EOX from the shrimpPandalus borealis. Levels of EOX were evaluated for spatial trends for shrimp caught in several areas off the Labrador coast, off the coast
of Nova Scotia, and off the coast of Maine. Muscle contained 1.09–6.05 Μg EOCl/g tissue and 105–498 Μg extractable organochlorine
(EOCl)/g lipid; 0.0607–0.288 Μg extractable organobromine (EOB)r/g tissue and 4.74-10.5 Μg EOBr/g lipid; and 0.014–0.048 Μg
extractable organoiodine (EOI)/g tissue and 1.03–1.76 Μg EOI/g lipid, respectively. The levels of EOC1 in roe were 1.60–12.34
Μg/g tissue and 39.0-146 Μg/g lipid. In roe, the EOBr levels were 0.707–1.03 Μg/g tissue and 6.96–13.5 Μg/g lipid; and EOI
levels were 0.123–0.349 Μg/g tissue and 1.42–4.11 Μg/g lipid. The EOCl, EOBr, and EOI levels in roe increased noticeably from
north to south along the coast of Labrador. Samples taken from the coast of Maine and from Canso Hole were typically higher
in EOCl levels than those taken from Labrador. The results for EOBr and EOI were in the same range as those from Labrador. 相似文献
6.
Roles of complex gangliosides in the development of experimental autoimmune encephalomyelitis 总被引:1,自引:0,他引:1
We induced experimental autoimmune encephalomyelitis (EAE) inGM2/GD2 synthase knockout mice (GM2/GD2–/–), whichcannot synthesize complex gangliosides, such as GM1, GD1a, GD1b,GT1b, and GQ1b, to investigate the roles of complex gangliosidesin the pathogenesis of this disease. We used myelin-oligodendrocyteglycoprotein (MOG) as an immunogen. In active immunization EAE,the severity of clinical score was not different but the diseaseonset was significantly delayed in GM2/GD2–/– comparedwith those in wild-type mice. When we transferred MOG-reactiveT cells from GM2/GD2–/– or wild-type mice to wild-typemice, no significant differences were observed between the twogroups. In contrast, when we transferred MOG-reactive T cellsfrom wild-type mice to GM2/GD2–/– or to wild-typemice, the onset of EAE in GM2/GD2–/– mice was delayed.The recall response of MOG-specific T cells, the function ofantigen presenting cells, or the expression of several adhesionmolecules in the endothelium were not significantly differentbetween GM2/GD2–/– and wild-type mice. On the otherhand, quantitative analysis of cellular infiltration in thecentral nervous system (CNS) on day 9 of active immunizationEAE showed that the CD4+ cell number in the CNS isolated fromGM2/GD2–/– mice was significantly less than thatfrom wild-type mice. It indicated that the delayed onset ofEAE in GM2/GD2–/– mice was due to the delay of themigration of pathogenic T cells into the CNS. Thus, the complexgangliosides may be involved in the T cell–endothelialcell interaction in the pathogenetic process of EAE. 相似文献
7.
Mnemiopsis leidyi: larvae depend on microplankton (<200 µm) prey duringthe first few days following hatching until larvae are >0.5mm in length and can successfully capture and consume mesozooplanktonprey. Feeding and growth rates of newly hatched M. leidyi larvaewere measured in controlled laboratory experiments. When fednatural microplankton assemblages, newly hatched larvae consumedsignificant quantities of both autotrophic and heterotrophicprey, including diatoms, phototrophic, heterotrophic and mixotrophicdinoflagellates, euglenoid flagellates, aloricate and tintinnidciliates, and rotifers. Average per capita clearance rates were1.99–7.59 mL individual–1 h–1 ( = 4.01 mL individual–1 h–1; SD = 1.95)and total per capita ingestion was 0.01–4.70 µgC individual–1 day–1 x 102 ( = 0.83 µg C individual–1 day–1 x 102; SD =1.89). Larval growth rates were –0.13 to 0.56 mm individual–1day–1 (equivalent to –1.72 to 4.33 µg C individual–1day–1) over a range of larval sizes from 0.5 (<0.5µg C) to 5 mm (85 µg C). A diet consisting entirelyof microplankton prey supported larval growth for >2 weeks,and growth rate decreased when larvae reached 4–5 mm inlength, corresponding to the beginning of their morphologicaltransition from tentaculate to lobate feeding mode. The grossgrowth efficiency of larvae fed natural microplankton assemblageswas 3%. 相似文献
8.
Jelena Arsenijević Slavica Ražić Zoran Maksimović Svetlana Đogo 《Central European Journal of Biology》2011,6(4):616-623
This paper brings out the results of the study on the levels of selected trace elements (Cu, Fe, Mn, Zn and Cr) in aerial
parts of Thymus pannonicus All. (Lamiaceae) and rhizosphere soil from twelve locations in Serbia. Prior to assays by flame and flameless atomic absorption
spectrometry, samples were subjected to microwave-assisted acid digestion. Real and potential acidity of soil samples were
also measured. Obtained results for soil samples, although slightly higher for some elements (Cu: 12.38–45.18 mg/kg; Fe: 22102–46193
mg/kg; Mn: 776.95–4901.27 mg/kg; Zn: 62.27–214.02 mg/kg; Cr: 48.86–69.13 mg/kg), were found to fit into biogeochemical background.
Element contents in plant samples differed depending on collecting site (Cu: 5.26–14.07 mg/kg; Fe: 25.92–1454.07 mg/kg; Mn:
89.29–278.25 mg/kg; Zn: 1.81–10.64 mg/kg; Cr: 1.11–3.51 mg/kg), which can be partly explainable by different nutrient availability
influenced by soil acidity. Zinc levels in T. pannonicus were below expected and seem to be strongly influenced by plant physiological properties. 相似文献
9.
We have determined the trace element composition of three mushrooms of Basidiomycetes, used in traditional Chinese medicine
using atomic absorption spectrophotometer (AAS). Metal concentrations in mushrooms were 203–401 mg/kg for iron, 22–51 mg/kg
for manganese, 84–116 mg/kg for zinc, 24.1–41.3 mg/kg for copper, 1.6–5.6 mg/kg for lead, 3.3–4.4 mg/kg for chromium, 9.3–11.5 mg/kg
for nickel, 0 mg/kg for vanadium, and 55.3–71 mg/kg for magnesium. The trace metal concentrations in mushrooms are hardly
affected by the ecosystem and soil where they grew, as well as by the mushroom species and trace metal species. The results
can be used to set new standards to control the quality of the three mushrooms of Basidiomycetes—Ganoderma lucidum, Coprinus comatus, and Grifola frondosa. 相似文献
10.
In this study, we performed a molecular docking and dynamics simulation for a benzoxazinone–human oxytocin receptor system to determine the possible hydrophobic and electrostatic interaction points in the dynamic complex. After the homology modeling, the ligand was docked into the putative active using AutoDock 3.05. After the application of energetic and structural filters, the complexes obtained were further refined with a simulated annealing protocol (AMBER8) to remove steric clashes. Three complexes were selected for subjection to the molecular dynamics simulation (5 ns), and the results on the occurrence of average anchor points showed a stable complex between the benzoxazinone derivative and the receptor. The complex could be used as a good starting point for further analysis with site-directed mutagenesis, or further computational research.
Figure The location of the ligands (complex B – blue; complex E – red; and complex F –
green) in the transmembrane regions (TM1 – red; TM2 – blue; TM3 – yellow; TM4
– purple; TM5 – orange; TM6 – cyan; TM7 – pink) of the hOTR. For clarity, the EC
and IC loops are not shown
Electronic Supplementary Material Supplementary material is available at 相似文献
11.
Progression age enhanced backward bifurcation in an epidemic model with super-infection 总被引:10,自引:0,他引:10
We consider a model for a disease with a progressing and a quiescent exposed class and variable susceptibility to super-infection.
The model exhibits backward bifurcations under certain conditions, which allow for both stable and unstable endemic states
when the basic reproduction number is smaller than one.
Received: 11 October 2001 / Revised version: 17 September 2002 /
Published online: 17 January 2003
Present address: Department of Biological Statistics and Computational Biology, 434 Warren Hall, Cornell University, Ithaca, NY 14853-7801
This author was visiting Arizona State University when most of the research was done.
Research partially supported by NSF grant DMS-0137687.
This author's research was partially supported by NSF grant DMS-9706787.
Key words or phrases: Backward bifurcation – Multiple endemic equilibria – Alternating stability – Break-point density – Super-infection – Dose-dependent
latent period – Progressive and quiescent latent stages – Progression age structure – Threshold type disease activation –
Operator semigroups – Hille-Yosida operators – Dynamical systems – Persistence – Global compact attractor 相似文献
12.
The structures of ZnO graphene–like nanosheets (ZnOGLNS), i.e., ZnO aromatic–like (AL–ZnONS), naphthalene–like (NLL–ZnONS),
pyrene–like (PRL–ZnONS), coronene–like (CNL–ZnONS) and circumcoronene–like (CCL–ZnONS) and their oxygen adsorptions were obtained
using the B3LYP/LanL2DZ method. Adsorption energies of O2 on AL–ZnONS, NLL–ZnONS, PRL–ZnONS, CNL–ZnONS and CCL–ZnONS are reported. The bond strengths of the most inner Zn–O bonds
of ZnOGLNSs are in order: CCL–ZnONS > CNL–ZnONS > PRL–ZnONS. It was found that chemisorptions of O2 occur on the hydride atoms of zinc–hydride in the ZnOGLNSs. Physisorptions of O2 only occurring over the plane of ZnOGLNS were found. All the ZnOGLNSs are oxygen sensitive materials and would be developed
to be oxygen sensor based on electrical conductivity. 相似文献
13.
A pioneering limnological investigation was carried out in Bhutan in a small peat bog in the Trashiyangtse district (1950 m
above sea level) from February 2000 to January 2002. The sampled pond water had low transparency (55.0–95.0 cm), was typically
acidic (pH 5.69–6.58) with soft water (alkalinity, 11.0–36.0 mg/l; total hardness, 10.0–34.0 mg/l), and had low to moderate
specific conductivity (17.0–62.0 μS/cm). Further, moderate Na (2.0–6.8 mg/l), K (1.8–13.5 mg/l), sulphate (0.85–2.99 mg/l),
and silicate (2.5–15.0 mg/l) concentrations as well as low nutrient levels such as phosphate (0.006–0.170 mg/l) and nitrate
(0.003–0.180 mg/l) characterize the water in the peat bog. The recorded net plankton comprised 27 species of phytoplankton
and 49 species of zooplankton, with the latter indicating greater homogeneity and breaking down into Rotifera (23 species)
> Cladocera (13 species) > Rhizopoda (8 species) > Copepoda (3 species) > Ostracoda = Nematoda (1 species each). On the other
hand, the net plankton density ranged between 93 and 692 number/l (n/l) with numerical dominance by phytoplankton (68.5% ±
12%), of which Chlorophyceae were predominant (90 ± 63 n/l). Zooplankton showed moderately high diversity (2.745 ± 0.293)
and evenness (0.925 ± 0.049) and exhibited almost equal abundance of four recorded groups, namely Cladocera (20 ± 15 n/l)
> Rotifera (15 ± 6 n/l) > Copepoda (14 ± 7 n/l) > Rhizopoda (14 ± 4 n/l). While no significant impact of abiotic factors was
recorded on zooplankton density, rainfall alone was the most important factor that influenced net plankton and various groups
of phytoplankton. Comments on some comparative limnological attributes are also made with similar as well as different habitats
in the nearby Himalayan countries. 相似文献
14.
M. Zouhair Atassi Behzod Z. Dolimbek Lance E. Steward K. Roger Aoki 《The protein journal》2010,29(5):320-327
In previous studies, we showed that certain peptides of the HN and HC domains of the H-chain of BoNT/A bind to mouse brain synaptosomes (snps). There was either complete correspondence or overlap
between peptides that bind snps and those that bind human or mouse blocking antibodies (Abs). An equimolar mixture of the
overlapping peptides N5/N6/N7/N8 (residues 505–523/519–537/533–551/547–565) extended the survival time of the mice to 74 h
(20%) relative to controls, which had a 50% survival time of 60 h. On the other hand, peptide N26 (residues 799–817) provided
no protection (50% survival time, 58 h), but the overlapping peptide N25 (785–803) almost doubled the 50% survival time to
119 h. A mixture of the overlap N25/N26 provided an unexpected level of protection permitting 40% of the mice to survive a
lethal BoNT/A dose. In the HC domain, the overlap C23/C24 (1163–1181/1177–1195) provided no protection. Peptide C31 (1275–1296) also provided no significant
protection. But an equimolar mixture of peptides C15/C16 (1051–1069/1065–1083) or peptides C18/C19/C20 (1093–1111/1107–1125/1121–1139)
extended the 50% survival time by 41% (to 85 h) over controls (60 h) and was able to fully protect 20% of the mice which eventually
recovered. Surprisingly, the mixture of the peptides C15/C16 and C18/C19/C20, which gave a 50% survival time of 75 h, was
less protective than either peptides C15/C16 or peptides C18/C19/C20. The in vivo inhibitory activity of these peptides is
discussed in relation to their location in the 3-dimensional structure of the toxin molecule and their membrane receptor binding. 相似文献
15.
Distribution of dissolved organic carbon and dissolved fulvic acid in mesotrophic Lake Biwa, Japan 总被引:1,自引:0,他引:1
The dissolved organic carbon (DOC) concentrations in mesotrophic Lake Biwa were determined by a total organic carbon (TOC)
analyzer, and DOC molecular size distributions were determined by size exclusion chromatography (SEC) using a fluorescence
detector at excitation/emission (Ex/Em) levels of 300/425 nm with the eluent at pH 9.7. The fluorescence wavelengths for detection
were chosen from the result of excitation–emission matrix spectrometry (EEM) analysis for dissolved fulvic acid (DFA) extracted
from Ado River (peak A, Ex/Em = 260–270/430–440 nm; peak B, Ex/Em = 300–310/420–430 nm). Ado River DFA was eluted with a retention
time (RT) of 7.4–8.9 min and the apparent molecular weight was estimated at 22–87 kDa based on the elution curve for the spherical
protein molecular weight standard. A DFA peak eluted at the same retention time as Ado River DFA also appeared in all the
samples of Lake Biwa water. From the linear relationship between the peak areas with an RT of 7.4–8.9 min by SEC analysis
and DOC values of DFA by TOC analysis of a series of DFA samples (r2 = 0.9995), the concentrations of DFA in the lake water were roughly calculated. DFA was distributed within the range 0.25–0.43 mg C l−1 and accounted for 15%–41% of DOC, with the highest ratios observed at a depth of 70 m in August and the lowest at 2.5 m in
May. 相似文献
16.
Induction of human cytotoxic T lymphocytes that preferentially recognise tumour cells bearing a conformational p53 mutant 总被引:1,自引:0,他引:1
McArdle SE Rees RC Mulcahy KA Saba J McIntyre CA Murray AK 《Cancer immunology, immunotherapy : CII》2000,49(8):417-425
The tumour-suppressor gene p53 is pivotal in the regulation of apoptosis, and point mutations within p53 are the commonest genetic alterations in human cancers. Cytotoxic T lymphocytes (CTL) recognise peptide-MHC complexes on
the surface of tumour cells and bring about lysis. Therefore, p53-derived peptides are potential candidates for immunisation
strategies designed to induce antitumour CTL in patients. Conformational changes in the p53 protein, generated as a result
of point mutations, frequently expose the 240 epitope, RHSVV (amino acids 212–217), which may be processed differently from
the wild-type protein resulting in an altered MHC-associated peptide repertoire recognised by tumour-specific CTL. In this
study 42 peptides (37 overlapping nonameric peptides, from amino acids 193–237 and peptides 186–194, 187–197, 188–197, 263–272,
264–272, possessing binding motifs for HLA-A2) derived from the wild-type p53 protein sequence were assayed for their ability
to stabilise HLA-A2 molecules in MHC class I stabilisation assays. Of the peptides tested, 24 stabilised HLA-A2 molecules
with high affinity (fluorescence ratio>1.5) at 26 °C, and five (187–197, 193–200, 217–224, 263–272 and 264–272) also stabilised
the complexes at 37 °C. Peptides 188–197, 196–203 and 217–225 have not previously been identified as binders of HLA-A2 molecules
and, of these, peptide 217–225 stabilised HLA-A2 molecules with the highest fluorescence ratio. Peptide 217–225 was chosen
to generate HLA-A2-restricted CTL in vitro; peptide 264–272 was used as a positive control. The two primary CTL thus generated
(CTL-217 using peptide 217–225; and CTL-264 using peptide 264–272) were capable of specifically killing peptide-pulsed T2
or JY cells. In order to determine whether these peptides were endogenously processed and to test the hypothesis that mutants
expressing different protein conformations would generate an alternative peptide repertoire at the cell surface, a panel of
target cells was generated. HLA-A2+ SaOs-2 cells were transfected with p53 cDNA containing point mutations at either position 175 (R → H) or 273 (R → H) (SaOs-2/175
and SaOs-2/273). Two HLA-A2-negative cell lines, A431 and SKBr3, naturally expressing p53 mutations at positions 273 and 175
respectively, were transfected with a cDNA encoding HLA-A2. The results showed that primary CTL generated in response to both
peptides were capable of killing SaOs-2/175 and SKBr3-A2 cells, which possess the same mutation, but not SaOs-2/273, A431-A2
or SKBr3 cells transfected with control vector. This suggests that these peptides are presented on the surface of SaOs-2/175
and SKBr3-A2 cells in a conformation-dependent manner and represent potentially useful target peptides for immunotherapy.
Received: 23 March 2000 / Accepted: 22 June 2000 相似文献
17.
Yukio Iwatsuki Seishi Kimura Hirokazu Kishimoto Tetsuo Yoshino 《Ichthyological Research》1996,43(4):417-429
Gerres macracanthus Bleeker, 1854, for many years having been explicitly or tentatively synonymized withG. filamentosus Cuvier, 1829, is redescribed as a valid species.Gerres macracanthus differs fromG. filamentosus in lacking vertical rows of dark ovoid spots on the body, having instead only indistinct vertical bands in both subadult
and adult stages, in addition to shorter second and third anal fin spines (9.1–13.9% and 10.4–14.4% of standard length [SL]
vs. 12.3–19.6% and 11.9–17.3% of SL), fewer ored lateral line scales (41–44 vs. 43–46) and fewer scales between the base of
the 5th dorsal fin spine and the lateral line (4–5 vs. 4 1/2–5 1/2), and above and below the lateral line (5 1/2–6 1/2/9 1/2–10
1/2 vs. 6 1/2–7 1/2/10 1/2–11 1/2). AlthoughG. filamentosus has similarly, indistinct vertical bands on the body up to ca. 100 mm SL, specimens over ca. 100 mm SL develop diffuse ovoid
spots in each vertical band. Furthermore,G. macracanthus is generally a smaller species, apparently attaining a maximum size of ca. 170 mm SL, compared with ca. 250 mm SL forG. filamentosus. Formerly known from the Philippines, Indonesia, New guinea, India and the Arabian Gulf,G. macracanthus is newly-recorded from Japan, China, the Gulf of Thailand, the Red Sea and South Africa. A lectotype and three paralectotypes
are designated forG. macracanthus Bleeker, 1854, in addition to a neotype forG. filamentosus Cuvier, 1829. 相似文献
18.
Hilde Eggermont James M. Russell Georg Schettler Kay Van Damme Ilse Bessems Dirk Verschuren 《Hydrobiologia》2007,592(1):151-173
This study describes the physical and chemical properties of 17 Afroalpine lakes (>2 m deep) and 11 pools (<2 m deep) in the
Rwenzori mountains, Uganda-DR Congo, with the aim to establish the baseline conditions against which to evaluate future environmental
and biological changes in these unique tropical ecosystems, and to provide the foundation for lake-based paleoenvironmental
studies. Most Rwenzori lakes are located above 3,500 m elevation, and dilute (5–52 μS/cm specific conductance at 25°C) open
systems with surface in- and outflow. Multivariate ordination and pairwise correlations between environmental variables mainly
differentiate between (1) lakes located near or above 4,000 m (3,890–4,487 m), with at least some direct input of glacial
meltwater and surrounded by rocky catchments or alpine vegetation; and (2) lakes located mostly below 4,000 m (2,990–4,054
m), remote from glaciers and surrounded by Ericaceous vegetation and/or bogs. The former group are mildly acidic to neutral
clear-water lakes (surface pH: 5.80–7.82; Secchi depth: 120–280 cm) with often above-average dissolved ion concentrations
(18–52 μS/cm). These lakes are (ultra-) oligotrophic to mesotrophic (TP: 3.1–12.4 μg/l; Chl-a: 0.3–10.9 μg/l) and phosphorus-limited (mass TN/TP: 22.9–81.4). The latter group are mildly to strongly acidic (pH: 4.30–6.69)
waters stained by dissolved organic carbon (DOC: 6.8–13.6 mg/l) and more modest transparency (Secchi-disk depth: 60–132 cm).
Ratios of particulate carbon, particulate nitrogen and chlorophyll a in these lakes indicate that organic matter in suspension is primarily derived from the lakes’ catchments rather than aquatic
primary productivity. Since key features in the Rwenzori lakes’ abiotic environment are strongly tied to temperature and catchment
hydrology, these Afroalpine lake ecosystems can be expected to respond sensitively to climate change and glacier melting.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
19.
Earthworm secondary production and N flux in agroecosystems: a comparison of two approaches 总被引:1,自引:0,他引:1
Production was estimated for Aporrectodea spp. and Lumbricus spp. populations in corn agroecosystems with a 5-year history of manure or inorganic fertilizer applications during 1994–1995
and 1995–1996. Earthworm biomass and production were greater in manure than inorganic fertilizer plots, although biomass and
production declined by about 50% between 1994–1995 and 1995–1996 due to unfavorable climatic conditions. Production was highest
during the spring and autumn when soil temperatures were between 4 and 22°C. Production was higher in Lumbricus spp. than Aporrectodea spp. populations due to greater Lumbricus spp. biomass. Aporrectodea spp. production was 3.47–16.14 g ash-free dry weight (AFDW) m–2 year–1, while Lumbricus spp. production was 6.09–18.11 g AFDW m–2 year–1, depending on the fertilizer treatment and the method used to estimate production. However, production estimates from the
instantaneous growth rate method were within 27% of the values calculated using the size-frequency method. Nitrogen flux through
earthworms was used to estimate efficiency quotients. Net production efficiency (P/A) ranged from 0.64 to 0.76, assimilation efficiency (A/C) ranged from 0.1 to 0.3, and gross production efficiency (P/C) ranged from 0.06 to 0.22. Annual N flux through earthworm populations was higher in manure than inorganic fertilizer plots,
and ranged from 2.95 to 5.47 g N m–2 year–1 in 1994–1995 and 1.76 to 2.92 g N m–2 year–1 in 1995–1996. The N flux through earthworms represented an amount equivalent to 16–30% of crop N uptake during 1994–1995
and 11–18% of crop N uptake during 1995–1996. We concluded that the effects of earthworms on N cycling in corn agroecosystems
were substantial, and that N flux through earthworms was influenced significantly by fertilizer amendments.
Received: 20 September 1999 / Accepted: 24 March 2000 相似文献
20.
Atsushi Fukui Miyuki Suzuki Yachiyo Suzuki Itsuro Uotani 《Ichthyological Research》2002,49(2):159-164
The early ontogeny of Lophonectes gallus (Bothidae) is described based on 83 specimens (1.9–17.5 mm BL), collected from the Tasman Sea off southeastern Australia.
The larvae are diagnosed by the following array of characters: vertebrae 10 + 30–31 = 40–41; one elongated dorsal fin ray
and several melanophores present on gut in preflexion stage (1.9–4.7 mm BL); and spines on posterior basipterygial process,
and urohyal, cleithrum, and epiotic without spines after postflexion stage (8.0–17.5 mm BL). The larvae are relatively small
at metamorphosis (15–18 mm BL) compared with other bothid larvae.
Received: March 22, 2001 / Revised: December 12, 2001 / Accepted: December 26, 2001 相似文献