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排序方式: 共有228条查询结果,搜索用时 62 毫秒
1.
Phytoplankton community structure and distribution in the nearshore zone of Lake Ontario 总被引:1,自引:1,他引:0
Spatial and temporal distributions of phytoplankton were studied during 1979 in the nearshore zone of Lake Ontario. Genera such as Dinobryon, Oscillatoria, and Gymnodinium tended to be found at discrete depths whereas other genera such as Cryptomonas and Rhodomonas tended to be more uniformly distributed throughout the water column. The discrete depth distribution of some of these genera compared with the weak thermal stabilization of the area suggests depth selection and habitat preference within the algal community.Physical processes probably played a major role in regulating the timing and duration of vertical diatom pulses, and resuspension from the sediment played a major role as to the timing of the autumn growth. Vertical mixing in the nearshore zone was sufficient for some diatom genera such as Tabellaria to maintain populations throughout the summer. These mixing processes, however, affect the stability of community structures and associations that develop within the water column. The role of physical processes and their potential effects on algal production in the Great Lakes is discussed. 相似文献
2.
Reduction of lecithin-cholesterol acyltransferase, apolipoprotein D and the Lp(a) lipoprotein with the anabolic steroid stanozolol 总被引:3,自引:0,他引:3
J J Albers H M Taggart D Applebaum-Bowden S Haffner C H Chesnut W R Hazzard 《Biochimica et biophysica acta》1984,795(2):293-296
The effects of the anabolic steroid stanozolol (17-methyl-2H-5 alpha-androst-2-eno-(3,2-c)pyrazol-17 beta-ol) on lecithin-cholesterol acyltransferase, apolipoproteins B and D and the Lp(a) lipoprotein were determined in a prospective study of ten normolipidemic women with postmenopausal osteoporosis. Lecithin-cholesterol acyltransferase was reduced approx. 30% by 6 weeks of treatment with stanozolol (off treatment 5.1 +/- 1.2, on treatment 3.4 +/- 0.8 muml; P less than 0.02). The Lp(a) lipoprotein was reduced 65 +/- 23% by the steroid treatment (off treatment 5.5 +/- 5.5, on treatment 1.4 +/- 0.7 mg/dl; P less than 0.02). Apolipoprotein D was reduced 23 +/- 9% by the treatment (off treatment 5.9 +/- 0.9, on treatment 4.5 +/- 0.7 mg/dl; P less than 0.02). In contrast, apolipoprotein B increased slightly but insignificantly on steroid therapy (off treatment 90 +/- 21, on treatment 112 +/- 24 mg/dl). By 5 weeks after the drug was discontinued, all four of these proteins were near pretreatment levels. These significant changes in lipoprotein metabolism, combined with our previous report of reductions of HDL and particularly HDL2, suggest the need for caution in the long-term use of anabolic steroids. 相似文献
3.
G. D. Haffner 《Hydrobiologia》1977,54(3):225-231
Seston size distribution was determined with a Coulter Counter to investigate seston interaction and its effects on phytoplankton
production. Spatial distribution patterns of the non-productive component of the seston were as complex as those commonly
associated with algae. Seston might interact influencing production by changes in optical depth, abrasive actions and nutrient
adsorption. 相似文献
4.
Angelina Passeri Michael Schmidt Thomas Haffner Victor Wray Siegmund Lang Fritz Wagner 《Applied microbiology and biotechnology》1992,37(3):281-286
Summary During screening for biosurfactants among marine, n-alkane-utilizing bacteria, low- and high-molecular surface-active substances were detected. The marine bacterial strain MM1 was found to synthesize a novel glycolipid that has not so far been cited in the literature. Both 1H, 13C-nuclear magnetic resonance spectroscopic and positive ion fast atom bombardment mass spectrometer studies led to the identification of a glucose lipid consisting of four 3-OH-decanoic acids, which are linked together by ester bonds. The lipophilic moiety is coupled glycosidically with C-1 of glucose. The glucolipid reduced the surface tension from 72 mN/m to 30 mN/m while the minimum interfacial tension towards n-hexadecane was lowered to values smaller than 5 mN/m.
Correspondence to: S. Lang 相似文献
5.
Enrico Munari Alcides Chaux Ajay M. Vaghasia Diana Taheri Sarah Karram Stephania M. Bezerra Nilda Gonzalez Roibon William G. Nelson Srinivasan Yegnasubramanian George J. Netto Michael C. Haffner 《PloS one》2016,11(1)
Solid tumors are characterized by a plethora of epigenetic changes. In particular, patterns methylation of cytosines at the 5-position (5mC) in the context of CpGs are frequently altered in tumors. Recent evidence suggests that 5mC can get converted to 5-hydroxylmethylcytosine (5hmC) in an enzymatic process involving ten eleven translocation (TET) protein family members, and this process appears to be important in facilitating plasticity of cytosine methylation. Here we evaluated the global levels of 5hmC using a validated immunohistochemical staining method in a large series of clear cell renal cell carcinoma (n = 111), urothelial cell carcinoma (n = 55) and testicular germ cell tumors (n = 84) and matched adjacent benign tissues. Whereas tumor-adjacent benign tissues were mostly characterized by high levels of 5hmC, renal cell carcinoma and urothelial cell carcinoma showed dramatically reduced staining for 5hmC. 5hmC levels were low in both primary tumors and metastases of clear cell renal cell carcinoma and showed no association with disease outcomes. In normal testis, robust 5hmC staining was only observed in stroma and Sertoli cells. Seminoma showed greatly reduced 5hmC immunolabeling, whereas differentiated teratoma, embryonal and yolk sack tumors exhibited high 5hmC levels. The substantial tumor specific loss of 5hmC, particularly in clear cell renal cell carcinoma and urothelial cell carcinoma, suggests that alterations in pathways involved in establishing and maintaining 5hmC levels might be very common in cancer and could potentially be exploited for diagnosis and treatment. 相似文献
6.
Lorenzo C Serrano-Ríos M Martínez-Larrad MT Gonzalez-Villalpando C Williams K Gabriel R Stern MP Haffner SM 《Obesity (Silver Spring, Md.)》2007,15(5):1294-1301
Objective: Obesity drives the diabetes epidemic. However, it is not known which obesity index best explains variations in type 2 diabetes mellitus prevalence across populations. Research Methods and Procedures: We analyzed three cross‐sectional studies from San Antonio, TX, (Mexican‐Americans and non‐Hispanic whites, n = 2839), Mexico City (n = 2233), and Spain (n = 2161) (age range, 35 to 64 years). We used the area under the receiver operating characteristic curve (AUC) to assess performance for identifying diabetic subjects and logistic regression analysis to examine differences in diabetes prevalence. Results: AUCs for waist circumference and BMI were similar in white subjects, but the AUC for waist circumference was greater in Mexican‐origin subjects (Mexican men, 0.594 vs. 0.549, p = 0.008; and women, 0.605 vs. 0.557, p = 0.002; Mexican‐American men, 0.648 vs. 0.600, p < 0.001; and women, 0.744 vs. 0.693, p < 0.001). The AUC for waist‐to‐height ratio tended to be greater than that for waist circumference, but statistical significance was demonstrated only in Mexican women (0.628 vs. 0.613, p = 0.044), Mexican‐American women (0.774 vs. 0.758, p < 0.001), and Spanish women (0.734 vs. 0.715, p = 0.039). No obesity index was consistently superior to the others for explaining differences in diabetes prevalence among populations. Conclusions: In white and Mexican‐origin men, waist circumference may be the preferred marker for identifying diabetic subjects on account of its simplicity; in women, waist‐to‐height ratio may be better. Differences in diabetes prevalence among these populations cannot be attributed to a single measure of obesity. 相似文献
7.
Patterns of Root Colonization in Epacridaceous Plants Collected from Different Sites 总被引:2,自引:0,他引:2
Root colonization was studied in ten species of the Epacridaceaeat three sites in Victoria by morphological and cross-inoculationexperiments. The sites and genera chosen were Cranbourne [Epacrisimpressa Labill. andLeucopogon ericoides(Smith) R. Br.] andRye [L. parviflorus(Andrews) Lindley] on the Mornington Peninsula,and the Grampians[Astroloma conostephioides(Sond.) Benth.,A.humifusum(Cav.) R. Br.,A pinifolium(R. Br.) Benth,Brachylomadaphnoides(Smith) Benth.,E. impressa, E. impressavar.grandifloraBenth.andStyphelia adscendensR. Br.] in western Victoria. For morphologicalstudies, samples of roots from each species at each site werecleared and stained and examined microscopically. For cross-inoculationstudies, cuttings from each site were struck in potting mediuminoculated with soil from the same and other sites. The ericoidmycorrhizae in the roots of plants found at or grown in Cranbourneand Rye soils were similar. Both were significantly differentfrom the internal hyphae found in the roots of plants foundat or grown in Grampians soils, which were three times largerin diameter and formed dense coils which filled the host celland invaded adjacent epidermal cells. This suggests that morethan one fungus is involved in the relationships, that the MorningtonPeninsula sites had a different fungus from the Grampians siteand that host specificity is low. Vesicular structures werealso found commonly on plants at the Grampians site, in contrastwith other sites. Epacridaceae; root; fungus; mycorrhiza; morphology; inoculation 相似文献
8.
Haffner C Frauli M Topp S Irmler M Hofmann K Regula JT Bally-Cuif L Haass C 《The EMBO journal》2004,23(15):3041-3050
Nodals are signaling factors of the transforming growth factor-beta (TGFbeta) superfamily with a key role in vertebrate development. They control a variety of cell fate decisions required for the establishment of the embryonic body plan. We have identified two highly conserved transmembrane proteins, Nicalin and Nomo (Nodal modulator, previously known as pM5), as novel antagonists of Nodal signaling. Nicalin is distantly related to Nicastrin, a component of the Alzheimer's disease-associated gamma-secretase, and forms a complex with Nomo. Ectopic expression of both proteins in zebrafish embryos causes cyclopia, a phenotype that can arise from a defect in mesendoderm patterning mediated by the Nodal signaling pathway. Accordingly, downregulation of Nomo resulted in an increase in anterior axial mesendoderm and the development of an enlarged hatching gland. Inhibition of Nodal signaling by ectopic expression of Lefty was rescued by reducing Nomo levels. Furthermore, Nodal- as well as Activin-induced signaling was inhibited by Nicalin and Nomo in a cell-based reporter assay. Our data demonstrate that the Nicalin/Nomo complex antagonizes Nodal signaling during mesendodermal patterning in zebrafish. 相似文献
9.
Haffner CD Thomson SA Guo Y Petrov K Larkin A Banker P Schaaf G Dickerson S Gobel J Gillie D Condreay JP Poole C Carpenter T Ulrich J 《Bioorganic & medicinal chemistry letters》2010,20(23):6989-6992
We report the synthesis and in vitro activity of a series of novel substituted N-{3-[(1,1-dioxido-1,2-benzothiazol-3-yl)(phenyl)amino]propyl}benzamide analogs. These analogs showed potent inhibitory activity against Kv1.3. Several demonstrated similar potency to the known Kv1.3 inhibitor PAP-1 when tested under the IonWorks patch clamp assay conditions. Two compounds 13i and 13rr were advanced further as potential tool compounds for in vivo validation studies. 相似文献
10.
Denis Saulnier Sophie De Decker Philippe Haffner Laetitia Cobret Maeva Robert Céline Garcia 《Microbial ecology》2010,59(4):787-798
A 4-year bacteriological survey (2003-2007) of four molluscs cultivated in France and faced with mortality episodes was performed by the French shellfish pathology network. The more abundant bacteria isolated during 92 mortality episodes, occurring mainly in Pacific oyster Crassostrea gigas, were identified by genotyping methods. It allowed us both to confirm the representativeness of Vibrio splendidus and Vibrio aestuarianus bacterial strains and to identify both a large number of Vibrio harveyi-related strains mainly detected during 2007 oyster mortality outbreaks and to a lesser extent bacterial strains identified as Shewanella colwelliana. Because metalloprotease has been reported to constitute a virulence factor in a few Vibrio strains pathogenic for C. gigas, several bacterial strains isolated in this study were screened to evaluate their pathogenicity in C. gigas spat by experimental infection and their ability to produce metalloprotease-like activity in the culture supernatant fluids. A high level (84%) of concordant results between azocaseinase activities and virulence of strains was obtained in this study. Because bacterial metalloprotease activities appeared as a common feature of pathogenic bacteria strains associated with mortality events of C. gigas reared in France, this phenotypic test could be useful for the evaluation of virulence in bacterial strains associated with such mortality episodes. 相似文献