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Meryem Beklioglu Ayse Gul Gozen Feriha Yıldırım Pelin Zorlu Sertac Onde 《Hydrobiologia》2008,614(1):321-327
Vertical migration of Daphnia represents the best-studied predator-avoidance behaviour known; yet the mechanisms underlying the choice to migrate require
further investigation to understand the role of environmental context. To investigate the optimal habitat choice of Daphnia under fish predation pressure, first, we selected the individuals exhibiting strong migration behaviour. The animals collected
from the hypolimnion during the daytime were significantly larger, being more conspicuous, and in turn performed stronger
diel vertical migration (DVM) when exposed to fish cue. We called them strong migrants. Second, we provided the strong migrant
D. pulex with food at high and intermediate (1 and 0.4 mg C l−1, respectively) levels, which were well above the incipient limiting level and of high quality. They traded the benefits of
staying in the warm water layer and moved down to the cold water in response to fish cue indicating fish predation. The availability
of food allowed the animals to stay in the cold hypolimnion. However, at the low food level (0.1 mg C l−1), which is an additional constraint on fitness, Daphnia moved away from the cold hypolimnion. Poor food condition resulted in strong migrant Daphnia to cease migration and remain in the upper warmer water layer. Although temperature is known to be a more important cost
factor of DVM than food, our results clearly show that this is only true as long as food is available. It becomes clear that
food availability is controlling the direction of vertical positioning when daphnids experience a dilemma between optimising
temperature and food condition while being exposed to fish cue. Then they overlook the predation risk. Thus, the optimal habitat
choice of Daphnia appears to be a function of several variables including temperature, food levels and fish predation.
Handling editor: S. I. Dodson 相似文献
2.
Rapid analysis of an osmotic stress responsive promoter by transient expression in intact wheat embryos 总被引:1,自引:0,他引:1
Expression of the wheat Em genes in embryos isstrongly induced both by abscisic acid and by subjection toosmotic stress. We have examined the basis of this inductionin an homologous system by con structing fusions between thepromoter sequences of a cloned Em gene and theGUS reporter gene. The ABA-and stress-mediated expression ofthese constructs has been assayed following delivery to intactwheat embryos by particle bombardment. Staining of bombardedembryos with the chromogenic substrate X-gluc enabled a simpleand rapid visual identification of promoter activity by scoringthe numbers of stained spots. Although not rigorously quantitative,a general correspondence between number of expression events(spots) and promoter activity could be inferred when the resultsobtained with bombarded embryos were compared with those obtainedby the fluorlmetnc measurement of GUS activity in cereal aleuroneprotoplasts transfected with the same constructs. Analysis ofa series of 5'-deletions of the Em promoters indicatedthat the stress-responsive cis-acting regulatory elements comprisethe same sequences as those responsible for ABA-mediated geneexpression. Key words: Abscisic acid, osmotic stress, Em genes, wheat embryos, transient expression 相似文献
3.
Plasma soluble intercellular adhesion molecule 1 levels are increased in type 2 diabetic patients with nephropathy 总被引:12,自引:0,他引:12
Güler S Cakir B Demirbas B Yönem A Odabasi E Onde U Aykut O Gürsoy G 《Hormone research》2002,58(2):67-70
BACKGROUND/AIM: Intercellular adhesion molecule 1 (ICAM-1) is a mediator in the recruitment of leukocytes in the glomerular cells. The role of ICAM-1 in diabetic complications is still a matter of debate. This study was performed to investigate the relation of plasma soluble ICAM-1 (sICAM-1) to nephropathy in patients with type 2 diabetes mellitus. METHODS: Ninety-three patients (24 males and 69 females) with type 2 diabetes mellitus were included into the study. Fifty patients had nephropathy, and 43 were free from nephropathy. Fifty healthy subjects (14 males and 36 females) served as the control group (group 1). Twenty-five of the diabetic patients had microalbuminuria (group 2), 25 had macroalbuminuria (group 3), and 43 had neither micro- nor macroalbuminuria (group 4). The plasma sICAM-1 levels were measured in blood samples drawn after fasting. RESULTS: The mean plasma sICAM-1 levels were not different in the 93 diabetic patients as compared with the healthy controls (392.7 +/- 119.5 vs. 350.1 +/- 90.2 ng/ml, p > 0.05). The mean sICAM-1 level was significantly higher in the diabetic patients with nephropathy than in those without nephropathy (430.3 +/- 78.2 vs. 368.2 +/- 122.5 ng/ml, p = 0.03) and in the controls (430.3 +/- 78.2 vs. 350.1 +/- 90.2 ng/ml, p = 0.016). The difference in sICAM-1 levels between groups 2 and 3 was not significant (p > 0.05). The plasma sICAM-1 levels were significantly higher in both groups 2 and 3 than in both groups 1 and 4 (434.5 +/- 129.2 vs. 427.2 +/- 113.7 ng/ml and 368.2 +/- 122.5 vs. 350.1 +/- 90.2 ng/ml, respectively). CONCLUSIONS: The plasma sICAM-1 levels in patients with type 2 diabetes mellitus are not significantly different from those in nondiabetic subjects. High levels of sICAM-1 suggest that sICAM-1 may play a role in the development of nephropathy in patients with type 2 diabetes mellitus. 相似文献
4.
T. Simon Futers Sertac Onde Muge Turet Andrew C. Cuming 《Plant molecular biology》1993,23(5):1067-1072
DNA sequences are presented for two members of the wheat Em gene family. The sequences correspond to the two linked genes at the Xem-1AL locus. Comparisons of these sequences with that of another wheat Em gene and two Em cDNA clones reveals substantial homology within the protein-coding regions, and the presence in the 5-flanking regions of the genomic sequences of motifs characteristic of ABA-responsive cis-acting elements. 相似文献
5.
Metin Ozata Ismail Kurt Muhittin A. Serdar M. Emin Onde Ahmet Aydin Ahmet Corakci M. Ali Gundogan 《Biological trace element research》1997,57(1):9-17
Although the availability of thyroid cyst fluid is easy by fineneedle aspiration, less is known about the biochemical composition
of thyroid cyst fluid. The authors have, therefore, determined the biochemical composition of 18 benign thyroid cyst fluid
specimens. They found that the activities of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and the concentrations
of total protein, total bilirubin, and uric acid were highly increased in thyroid cyst fluid specimens when compared with
normal human serum specimens. The concentrations of glucose, cholesterol, and triglycerides in cyst fluid were within normal
serum limits. Selenium (Se) concentrations in most cyst fluids were low. Moreover, there was no correlation between Se and
other biochemical parameters. Protein electrophoresis of cyst fluid specimens yielded high concentrations of α1 and especially α2 globulin fractions indicating an inflammation. The concentrations or activities of biochemical analytes were not significantly
different in pure and mixed cysts. Those parameters were also not significantly different between cyst fluids of different
colors. The gross appearance of the fluid and the presence of certain biochemical analytes were consistent with a hemorrhagic
origin of most of the cyst fluid specimens. However, some biochemical markers indicate that autolysis or necrosis of thyroid
tissue may also contribute the composition of thyroid cyst fluid. The reason for lower Se concentration in the thyroid cyst
fluid may be the lower Se concentration in the Turkish population. These results also suggest that the fluid color or nature
of cyst, e.g., pure or mixed cyst, is not a main determinant of biochemical composition of benign thyroid cyst fluid. 相似文献
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