We have characterized modulation of
I
Ca
by Ca
2+
at the t-tubules (ie, in control cells) and surface sarcolemma (ie, in detubulated cells) of cardiac ventricular myocytes, using the whole-cell patch ...clamp technique to record
I
Ca
.
I
Ca
inactivation was significantly slower in detubulated cells than in control cells (27.1±7.8 ms, n=22, versus 16.4±7.9 ms, n=22;
P
<0.05). In atrial myocytes, which lack t-tubules,
I
Ca
inactivation was not changed by the treatment used to produce detubulation. In the presence of ryanodine or BAPTA, or when Ba
2+
was used as the charge carrier, the rate of inactivation was not significantly different in control and detubulated cells. Frequency-dependent facilitation occurred in control cells but not in detubulated cells, and was abolished by ryanodine. These results suggest that Ca
2+
released from the SR has a greater effect on
I
Ca
in the t-tubules than at the surface sarcolemma. This does not appear to be due to differences in local Ca
2+
release from the SR, because the gain of Ca
2+
release was not significantly different in control and detubulated cells. These data suggest that the t-tubules are a key site for the regulation of transsarcolemmal Ca
2+
flux by Ca
2+
release from the SR; this could play a role in altered Ca
2+
homeostasis in pathological conditions. The full text of this article is available online at http://circres.ahajournals.org.
One of the rewards of having a Drosophila melanogaster whole-genome sequence will be the potential to understand the molecular bases for structural features of chromosomes that have been a ...long-standing puzzle. Analysis of 2.6 megabases of sequence from the tip of the X chromosome of Drosophila identifies 273 genes. Cloned DNAs from the characteristic bulbous structure at the tip of the X chromosome in the region of the broad complex display an unusual pattern of in situ hybridization. Sequence analysis revealed that this region comprises 154 kilobases of DNA flanked by 1.2-kilobases of inverted repeats, each composed of a 350-base pair satellite related element. Thus, some aspects of chromosome structure appear to be revealed directly within the DNA sequence itself.
Origin of the Foraminifera Wray, Charles G.; Langer, Martin R.; DeSalle, Rob ...
Proceedings of the National Academy of Sciences - PNAS,
01/1995, Letnik:
92, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We report nuclear small-subunit rDNA sequences for two species of the benthic foraminifer Ammonia. Because of their abundance in present and past seas, the foraminifera are a very important group of ...organisms used in a wide range of geologic studies; however, the ancestry of this group was, until now, unknown. Difficulties in purifying foraminiferal DNA and avoiding PCR contamination led us to develop DNA·DNA in situ hybridization techniques to verify our sequence data. Phylogenetic analysis of verified foraminiferal DNA sequence indicates these taxa are a divergent, "alveolate" lineage, within the major eukaryotic radiation. Our findings cast doubt upon the assumption that all foraminifera are derived from an amoeba-like ancestor. Cytological features and the DNA sequences presented herein suggest that the foraminifera were derived from a heterokaryotic flagellated marine protist, probably sometime in the later Proterozoic.
Hybrid Fuzzy Logic Strategy for Soccer Robot Game Maravillas, Elmer A.; Reyes, Napoleon H.; Dadios, Elmer P.
Journal of advanced computational intelligence and intelligent informatics,
01/2004, Letnik:
8, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This paper presents a control strategy for the robot soccer game goalie using hybrid fuzzy logic systems. The strategy adopts the divide and conquer concept by decomposing the goalie’s task of ...defending the goal into four (4) categories. Consequently, each category is characterized by different goalie-ball situations and will be handled by a separate rule-base. The first fuzzy system takes the x-coordinates of the robot and the ball then outputs the category number that determines the rule-base to be used in the second fuzzy system. The second fuzzy system handles the goalie’s movements. It takes the current y-coordinate of the goalie-robot and the ball then outputs the y-coordinate of the goalie’s next position (destination) which is located along its line-of-action (a line with predefined x-coordinate where the goalie moves back and forth just in front of the goal it is defending). Experiment shows that this strategy is feasible, efficient, and robust.
Campylobacter was investigated in cecal droppings, feces, and cloacal swabs of 22 flocks of 3 to 5 week-old broilers. Risk factors and the likelihood of the presence of this agent in these flocks ...were determined. Management practices, such as cleaning and disinfection, feeding, drinkers, and litter treatments, were assessed. Results were evaluated using Odds Ratio (OR) test, and their significance was tested by Fisher's test (p<0.05). A Campylobacter prevalence of 81.8% was found in the broiler flocks (18/22), and within positive flocks, it varied between 85 and 100%. Campylobacter incidence among sample types was homogenous, being 81.8% in cecal droppings, 80.9% in feces, and 80.4% in cloacal swabs (230). Flocks fed by automatic feeding systems presented higher incidence of Campylobacter as compared to those fed by tube feeders. Litter was reused in 63.6% of the farm, and, despite the lack of statistical significance, there was higher likelihood of Campylobacter incidence when litter was reused. Foot bath was not used in 45.5% of the flocks, whereas the use of foot bath associated to deficient lime management increased the number of positive flocks, although with no statiscal significance. The evaluated parameters were not significantly associated with Campylobacter colonization in the assessed broiler flocks.
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