Abstract: Melatonin production in the pineal gland is high at night and low during the day. This ... more Abstract: Melatonin production in the pineal gland is high at night and low during the day. This rhythm reflects circadian changes in the activity of serotonin N-acetyltransferase [arylalkylamine N-acetyltransferase (AA-NAT); EC 2.3.1.87], the penultimate enzyme in melatonin synthesis. The rhythm is generated by an endogenous circadian clock. In the chick, a clock is located in the pinealocyte, which also contains two phototransduction systems. One controls melatonin production by adjusting the clock and the other acts distal to the clock, via cyclic AMP mechanisms, to switch melatonin synthesis on and off. Unlike the clock in these cells, cyclic AMP does not appear to regulate activity by altering AA-NAT mRNA levels. The major changes in AA-NAT mRNA levels induced by the clock seemed likely (but not certain) to generate comparable changes in AA-
The recent fire on January 2, 2014 in a chemistry lab at Beacon High School in New York City, alt... more The recent fire on January 2, 2014 in a chemistry lab at Beacon High School in New York City, although horrific, must motivate us to restore science instructional support and oversight; using it to justify further reductions in the frequency and quality of active science instruction will only serve to undermine science education at a time when fewer and fewer of our talented students are choosing to pursue careers in science and engineering.
Most cDNA enrichment techniques involve technically complicated subtractive and hybridization rea... more Most cDNA enrichment techniques involve technically complicated subtractive and hybridization reactions whose kinetics have not been characterized. We describe a control for cDNA enrichment procedures based on commercially available reagents, and we use this control to optimize a commonly used subtractive hybridization reaction. Using this control, we show that high-abundance transcripts can be efficiently removed following very short hybridization reactions. With the addition of unlabeled rat liver cDNA, we develop a system that mimics the reaction kinetics of complex cDNA pools. Because this system enables the measurement of specific vs. nonspecific hybridization and subtraction in the same tube and is an effective control for all steps in the cDNA enrichment procedure, it facilitates the development and optimization of novel cloning techniques for a desired abundance level of differentially expressed cDNAs.
Most cDNA enrichment techniques involve technically complicated subtractive and hybridization rea... more Most cDNA enrichment techniques involve technically complicated subtractive and hybridization reactions whose kinetics have not been characterized. We describe a control for cDNA enrichment procedures based on commercially available reagents, and we use this control to optimize a commonly used subtractive hybridization reaction. Using this control, we show that high-abundance transcripts can be efficiently removed following very short hybridization reactions. With the addition of unlabeled rat liver cDNA, we develop a system that mimics the reaction kinetics of complex cDNA pools. Because this system enables the measurement of specific vs. nonspecific hybridization and subtraction in the same tube and is an effective control for all steps in the cDNA enrichment procedure, it facilitates the development and optimization of novel cloning techniques for a desired abundance level of differentially expressed cDNAs.
Most cDNA enrichment techniques involve technically complicated subtractive and hybridization rea... more Most cDNA enrichment techniques involve technically complicated subtractive and hybridization reactions whose kinetics have not been characterized. We describe a control for cDNA enrichment procedures based on commercially available reagents, and we use this control to optimize a commonly used subtractive hybridization reaction. Using this control, we show that high-abundance transcripts can be efficiently removed following very short hybridization reactions. With the addition of unlabeled rat liver cDNA, we develop a system that mimics the reaction kinetics of complex cDNA pools. Because this system enables the measurement of specific vs. nonspecific hybridization and subtraction in the same tube and is an effective control for all steps in the cDNA enrichment procedure, it facilitates the development and optimization of novel cloning techniques for a desired abundance level of differentially expressed cDNAs.
Regulatory toxicology and pharmacology : RTP, 2001
The proposed existence of dose-response thresholds for nongenotoxic carcinogens has led to a majo... more The proposed existence of dose-response thresholds for nongenotoxic carcinogens has led to a major controversy in the risk extrapolation process. To resolve this debate, there has been a significant investment in mechanism-based risk assessment research. The ability to utilize this mechanistic research for risk assessment procedures is still limited and may not warrant the expense. Alternatively, an approach can be used to identify dose-response thresholds through the utilization of sensitive indicators of biological response. This approach does not rely upon a mechanistic framework for the development of pathology, is solely dependent on already existing technology, and takes into account the possibility of background levels of pathway activation. For this approach, sensitive biochemical responses need to be identified and linked to the introduction of the toxicant through dose response, by time of response, and, when possible, through a proposed biochemical mechanism. The weakness...
The recent fire on January 2, 2014 in a chemistry lab at Beacon High School in New York City, alt... more The recent fire on January 2, 2014 in a chemistry lab at Beacon High School in New York City, although
horrific, must motivate us to restore science instructional support and oversight; using it to justify further
reductions in the frequency and quality of active science instruction will only serve to undermine science
education at a time when fewer and fewer of our talented students are choosing to pursue careers in
science and engineering.
Abstract: Melatonin production in the pineal gland is high at night and low during the day. This ... more Abstract: Melatonin production in the pineal gland is high at night and low during the day. This rhythm reflects circadian changes in the activity of serotonin N-acetyltransferase [arylalkylamine N-acetyltransferase (AA-NAT); EC 2.3.1.87], the penultimate enzyme in melatonin synthesis. The rhythm is generated by an endogenous circadian clock. In the chick, a clock is located in the pinealocyte, which also contains two phototransduction systems. One controls melatonin production by adjusting the clock and the other acts distal to the clock, via cyclic AMP mechanisms, to switch melatonin synthesis on and off. Unlike the clock in these cells, cyclic AMP does not appear to regulate activity by altering AA-NAT mRNA levels. The major changes in AA-NAT mRNA levels induced by the clock seemed likely (but not certain) to generate comparable changes in AA-
The recent fire on January 2, 2014 in a chemistry lab at Beacon High School in New York City, alt... more The recent fire on January 2, 2014 in a chemistry lab at Beacon High School in New York City, although horrific, must motivate us to restore science instructional support and oversight; using it to justify further reductions in the frequency and quality of active science instruction will only serve to undermine science education at a time when fewer and fewer of our talented students are choosing to pursue careers in science and engineering.
Most cDNA enrichment techniques involve technically complicated subtractive and hybridization rea... more Most cDNA enrichment techniques involve technically complicated subtractive and hybridization reactions whose kinetics have not been characterized. We describe a control for cDNA enrichment procedures based on commercially available reagents, and we use this control to optimize a commonly used subtractive hybridization reaction. Using this control, we show that high-abundance transcripts can be efficiently removed following very short hybridization reactions. With the addition of unlabeled rat liver cDNA, we develop a system that mimics the reaction kinetics of complex cDNA pools. Because this system enables the measurement of specific vs. nonspecific hybridization and subtraction in the same tube and is an effective control for all steps in the cDNA enrichment procedure, it facilitates the development and optimization of novel cloning techniques for a desired abundance level of differentially expressed cDNAs.
Most cDNA enrichment techniques involve technically complicated subtractive and hybridization rea... more Most cDNA enrichment techniques involve technically complicated subtractive and hybridization reactions whose kinetics have not been characterized. We describe a control for cDNA enrichment procedures based on commercially available reagents, and we use this control to optimize a commonly used subtractive hybridization reaction. Using this control, we show that high-abundance transcripts can be efficiently removed following very short hybridization reactions. With the addition of unlabeled rat liver cDNA, we develop a system that mimics the reaction kinetics of complex cDNA pools. Because this system enables the measurement of specific vs. nonspecific hybridization and subtraction in the same tube and is an effective control for all steps in the cDNA enrichment procedure, it facilitates the development and optimization of novel cloning techniques for a desired abundance level of differentially expressed cDNAs.
Most cDNA enrichment techniques involve technically complicated subtractive and hybridization rea... more Most cDNA enrichment techniques involve technically complicated subtractive and hybridization reactions whose kinetics have not been characterized. We describe a control for cDNA enrichment procedures based on commercially available reagents, and we use this control to optimize a commonly used subtractive hybridization reaction. Using this control, we show that high-abundance transcripts can be efficiently removed following very short hybridization reactions. With the addition of unlabeled rat liver cDNA, we develop a system that mimics the reaction kinetics of complex cDNA pools. Because this system enables the measurement of specific vs. nonspecific hybridization and subtraction in the same tube and is an effective control for all steps in the cDNA enrichment procedure, it facilitates the development and optimization of novel cloning techniques for a desired abundance level of differentially expressed cDNAs.
Regulatory toxicology and pharmacology : RTP, 2001
The proposed existence of dose-response thresholds for nongenotoxic carcinogens has led to a majo... more The proposed existence of dose-response thresholds for nongenotoxic carcinogens has led to a major controversy in the risk extrapolation process. To resolve this debate, there has been a significant investment in mechanism-based risk assessment research. The ability to utilize this mechanistic research for risk assessment procedures is still limited and may not warrant the expense. Alternatively, an approach can be used to identify dose-response thresholds through the utilization of sensitive indicators of biological response. This approach does not rely upon a mechanistic framework for the development of pathology, is solely dependent on already existing technology, and takes into account the possibility of background levels of pathway activation. For this approach, sensitive biochemical responses need to be identified and linked to the introduction of the toxicant through dose response, by time of response, and, when possible, through a proposed biochemical mechanism. The weakness...
The recent fire on January 2, 2014 in a chemistry lab at Beacon High School in New York City, alt... more The recent fire on January 2, 2014 in a chemistry lab at Beacon High School in New York City, although
horrific, must motivate us to restore science instructional support and oversight; using it to justify further
reductions in the frequency and quality of active science instruction will only serve to undermine science
education at a time when fewer and fewer of our talented students are choosing to pursue careers in
science and engineering.
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Papers by Jonathan Gastel
horrific, must motivate us to restore science instructional support and oversight; using it to justify further
reductions in the frequency and quality of active science instruction will only serve to undermine science
education at a time when fewer and fewer of our talented students are choosing to pursue careers in
science and engineering.
horrific, must motivate us to restore science instructional support and oversight; using it to justify further
reductions in the frequency and quality of active science instruction will only serve to undermine science
education at a time when fewer and fewer of our talented students are choosing to pursue careers in
science and engineering.