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Biomedical subjects

K Rudolph

Publications and source records attributed to K Rudolph.

8 recordsLinked to original sources
PubMed1991

Regulatory elements near the Drosophila hsp 22 gene required for ecdysterone and heat shock induction.

A transient expression assay was used to localize cis-acting DNA regulatory elements near the Drosophila heat shock protein (hsp) 22 gene, that are involved in heat shock expression and in ecdysterone-induced expression. The results identify a region between positions -320 and -232 that is essential for ecdysterone control, but not for heat-induced expression, and a sequence between -199 and -156, which, when deleted, leads to the loss of heat shock induction. To investigate the function of these DNA sequences, transfection-competition experiments were carried out. The evidence suggests that the DNA regulatory sequences identified by transient expression studies contain binding sites for transacting transcription factors.

Animals↗
PubMed1991

Ecdysterone regulatory elements function as both transcriptional activators and repressors.

A synthetic, 23-bp ecdysterone regulatory element (EcRE), derived from the upstream region of the Drosophila melanogaster hsp27 gene, was inserted adjacent to the herpes simplex virus thymidine kinase promoter fused to a bacterial gene for chloramphenicol acetyltransferase (CAT). Hybrid constructs were transfected into Drosophila S3 cells and assayed for ecdysterone-inducible CAT expression. In the absence of ecdysterone a tandem pair of EcREs repressed the high constitutive level of CAT activity found after transfection with the parent reporter plasmid alone. After hormone addition very high levels of CAT activity were observed. Insertion of the EcRE pair 3' of the CAT gene also led to high levels of ecdysterone-induced CAT expression, but the repression of high constitutive levels of CAT activity failed to occur. The EcRE-CAT construct was cotransfected with plasmids containing tandem 10-mers or 40-mers of the EcRE but lacking a reporter gene. These additional EcREs led to a reduced level of ecdysterone-induced CAT activity and to an elevation of basal CAT activity in the absence of hormone. The data suggest that the receptor binds to the EcRE in the absence of hormone, blocking basal transcription from a constitutive promoter. In the presence of ecdysterone, receptor-hormone binding to the EcRE leads to greatly enhanced transcription.

Animals↗
PubMed1988

Static magnetic fields decrease nocturnal pineal cAMP in the rat.

Magnetosensitivity of the rat's pineal cyclic adenosine monophosphate (cAMP) system was investigated. During their dark phase, rats were exposed for one hour to a static magnetic field (MF) inverting the horizontal component of the natural MF. MF-exposed animals showed a 38% decrease in pineal cAMP content (1.21 pmol/pineal gland) compared to a non-exposed control group (1.96 pmol/pineal gland).

Animals↗
PubMed1987

The pattern and habituation of the orienting response in man and rats.

Autonomic and central nervous indices of the orienting response (OR) were investigated in awake human subjects and sleeping rats. Ten acoustic stimuli of 60 dB and two stimuli of 80 dB were presented for 10 s each with a constant interstimulus interval of 50 s. Responses were averaged across subjects for each single trial. An exponential fit to scores of each physiological variable was used to compare OR, habituation and dishabituation between samples and variables. An OR to the first stimulus, habituation of response amplitude, and dishabituation in response to the change in stimulus intensity were observed for event-related EEG desynchronization, a negative-positive evoked potential complex in humans and rats, as well as for skin conductance in humans. While heart rate did not show systematic changes across the 60 dB tones in both samples, a deceleration was observed in response to the first 80 dB tone. Results suggest comparable patterns of orienting to acoustic stimuli and habituation of the OR in the awake human and the sleeping rat, suggesting the possibility of OR as a unitary response. Species differed with respect to speed of habituation but not with respect to sensitivity towards stimulus change.

Acoustic Stimulation↗
PubMed1985

Weak 50-Hz electromagnetic fields activate rat open field behavior.

Rats were tested in an open field after previous exposure to a weak, 50-Hz electromagnetic field of the same order of magnitude as the earth's magnetic field. Animals exposed to the artificial field at the beginning of the light phase showed 40% more rearing activity than controls, together with a slight increase in ambulation and a tendency towards less defecation and a shortened rearing latency. A replication experiment yielded the same results. Animals exposed at the beginning of the dark phase manifested no significant changes in open field activity. The results show that weak electromagnetic stimuli can modify some behavioral responses, and that these responses are sensitive to circadian phase.

Animals↗
PubMed1985

Similarities in feeding behavior of chronic methamphetamine treated and withdrawn rats to VMH lesioned rats.

During chronic methamphetamine (M) administration and after drug withdrawal, total daily food intake, water consumption and body weight increase was measured. Additionally, food intake in the early light phase provided an index of normal circadian rhythmicity. A parallel development of tolerance to the anorexic effect of M and increased feeding in the early light phase occurred. A further abnormal behavior of both chronic M-treated and withdrawn rats was the lack of preference reversal when given free access to concentrated vs. diluted glucose solutions. Both disturbed circadian feeding rhythmicity and inhibition of the glucose preference reversal are found in rats with ventromedial hypothalamic (VMH) lesions. Reduced food intake and diminished body weight increase is a characteristic of lateral hypothalamic lesions. By analogy, chronic M-treatment could be considered to induce a functional state similar to lesions of the medial and lateral hypothalamus, each with a different time course.

Animals↗