ENZYME ADAPTATION TO NUTRITIONAL AND HORMONAL CHANGE

1978 ◽  
pp. 41-52
Author(s):  
John W. Porter
Keyword(s):  
Hormonal Change ◽  
Enzyme Adaptation

P25 gene regulation in Bombyx mori silk gland: two promoter-binding factors have distinct tissue and developmental specificities

1992 ◽  
Vol 12 (12) ◽  
pp. 5768-5777
Author(s):  
B Durand ◽  
J Drevet ◽  
P Couble
Keyword(s):  
Bombyx Mori ◽  
Head Capsule ◽  
Regulatory Elements ◽  
Silk Gland ◽  
Related Factor ◽  
Developmental Studies ◽  
Hormonal Change ◽  
Specific Expression ◽  
Gland Cells ◽  
Gene Status

The gene encoding the silk protein P25 is expressed in the posterior silk gland of Bombyx mori with strict territorial and developmental specificities. The cis-acting regulatory elements previously located within the 441-bp 5' proximal sequence of the gene were examined for protein-binding capacities. We identified two factors, BMFA and SGFB, that lead to prominent band shifts and the target sites for which are included in a region homologous to the fibroin gene enhancer sequence. Analysis of the tissue-specific incidence of both factors showed that BMFA is ubiquitous, whereas SGFB is restricted to the silk gland cells. However, SGFB was found in both posterior and middle silk gland cells and therefore likely directs organ-specific, but not territory-specific, expression. Developmental studies throughout the fourth larval molt, at which the P25 gene status changes from derepressed to repressed, revealed that BMFA is reversibly modified at the transition from intermolt to molt. Indeed, the preexisting BMFA is replaced by a structurally related factor, BMFA', during the 2 h following head capsule apolysis. The exact temporal coincidence of this conversion with the onset of gene repression suggests that BMFA' is involved in transcription inactivation and likely results from a transduction process initiated by the hormonal change at molting.

Regional variation in glycolytic enzyme adaptation to dietary sugars in rat small intestine

1975 ◽  
Vol 28 (5) ◽  
pp. 453-458 ◽  
Author(s):  
J Espinoza ◽  
A Hritz ◽  
R Kaplan ◽  
S B Clark ◽  
N S Rosensweig
Keyword(s):  
Small Intestine ◽  
Regional Variation ◽  
Glycolytic Enzyme ◽  
Rat Small Intestine ◽  
Enzyme Adaptation ◽  
Dietary Sugars

ENZYME ADAPTATION IN MAMMALS

1972 ◽  
pp. 221-273 ◽  
Author(s):  
Hermann Niemeyer ◽  
Tito Ureta
Keyword(s):  
Enzyme Adaptation

RAT INTESTINAL SUCRASE: II. THE EFFECTS OF RAT AGE AND SEX AND OF DIET ON SUCRASE ACTIVITY

1963 ◽  
Vol 41 (1) ◽  
pp. 917-929 ◽  
Author(s):  
D. G. R. Blair ◽  
W. Yakimets ◽  
J. Tuba
Keyword(s):  
Control Diet ◽  
Male Rats ◽  
Normal Male ◽  
Casein Diet ◽  
Sucrase Activity ◽  
Adult Rats ◽  
Sucrose Diet ◽  
Enzyme Adaptation ◽  
Intestinal Sucrase ◽  
Intestinal Sucrase Activity

Intestinal sucrase activity of the rat varies with the age, but not the sex, of the animal. Sucrase activity of rats 23 days of age was approximately two-thirds that of adults.Sucrase activity of adult rats was significantly decreased by several days of fasting. The decrease was rapid during the first 2 to 4 days of the fast, but became negligible thereafter.Diets containing large (70%) amounts of sucrose, galactose, melizitose, or α-methyl-D-glucoside produced highly significant increases in intestinal sucrase levels (compared with a carbohydrate-free, high-casein control diet) when fed ad libitum for 24 hours to adult male rats previously fasted for 3 days. Similar diets containing fructose, fructose plus glucose in equimolar amounts, or maltose significantly increased sucrase activity, but diets containing glucose, mannose, xylose, or lactose were not stimulatory. A 70% raffinose diet significantly decreased sucrase activity. Normal male rats which were fed the 70% sucrose diet for 4 weeks had sucrase activities similar to those of controls fed Purina fox checkers, but animals fed the carbohydrate-free, high-casein diet for 1 day or longer had sucrase activities significantly lower than those of controls. The significance of these observations in regard to enzyme "adaptation" is discussed.

scholarly journals The effects of cortisol, corticotropin and thyroxine on the synthesis of glycerolipids and on the phosphatidate phosphohydrolase activity in rat liver

1978 ◽  
Vol 176 (3) ◽  
pp. 777-784 ◽  
Author(s):  
Helen P. Glenny ◽  
David N. Brindley
Keyword(s):  
Body Weight ◽  
Body Weight Gain ◽  
Relative Rate ◽  
Male Rats ◽  
Very Low Density Lipoproteins ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase ◽  
Ethanol Feeding ◽  
Enzyme Adaptation ◽  
Subtotal Hepatectomy

1. Male rats were injected daily for 5 days with 0.15m-NaCl, corticotropin, cortisol or l-thyroxine and the rates of glycerolipid synthesis were measured in the livers after intraportal injection of [14C]palmitate and [3H]glycerol. 2. Injection of all three hormones decreased the rates of body-weight gain. 3. Cortisol treatment increased the weight of the liver relative to body weight. 4. Thyroxine treatment increased the relative rate of triacylglycerol synthesis from [3H]glycerol and decreased the relative accumulation of 3H and 14C in diacylglycerol. It did not significantly alter the accumulation of these isotopes in phosphatidate nor the activity of the soluble phosphatidate phosphohydrolase in the total liver. However, this activity increased by 1.5-fold when expressed relative to the soluble protein of the liver. The increased triacylglycerol synthesis appears to be related to a general increase in the turnover of fatty acids in the liver. 5. Treatment with cortisol and corticotropin increased the relative rate of triacylglycerol synthesis from [3H]glycerol, decreased the accumulation of 3H in phosphatidate and increased the flux of both isotopes from phosphatidate to diacylglycerol. This appeared to be caused by the increased activity of the soluble phosphatidate phosphohydrolase that was observed in the livers of the cortisol-treated rats. 6. It is proposed that cortisol could be directly or indirectly involved in increasing the activity of hepatic phosphatidate phosphohydrolase in starvation, diabetes, laparotomy, subtotal hepatectomy, liver damage, ethanol feeding and in obesity. This enzyme adaptation could contribute to the potential of the liver to increase its synthesis and accumulation of triacylglycerols or to secrete very-low-density lipoproteins.

Evaluation of hormonal change, biochemical parameters, and histopathological status of uterus in rats exposed to 50-Hz electromagnetic field

2009 ◽  
Vol 25 (3) ◽  
pp. 153-158 ◽  
Author(s):  
M Aydin ◽  
A Cevik ◽  
FM Kandemir ◽  
M Yuksel ◽  
AM Apaydin
Keyword(s):  
Electromagnetic Field ◽  
Biochemical Parameters ◽  
Reproductive Organ ◽  
Female Rats ◽  
Hormonal Change ◽  
Average Value ◽  
Group 4 ◽  
High Voltage Power Lines ◽  
And Control ◽  
Experimental Group

This study investigates the effects of the electromagnetic field (EMF) resulting from the 170 kV high-voltage power lines on hormonal status, on progesterone and 17-β estradiol levels, and on morphology of the uterus and ovaries associated with biochemical parameters of adult Wistar female rats. The rats were assigned to experimental (21) and control groups (7). The rats in the experimental group were housed in a wooden barn with 7.5 m vertical distance to the power line. Groups 1, 2, and 3 were exposed continuously (24 h) to electric-electromagnetic fields (ELF-EMFs) (48.21 ± 1.58 mG) for 1, 2, and 3 months, respectively. The rats of group 4 served as the control and were placed in laboratory conditions (The average value of the ELF was 0.75 ± 0.05 V/m. The value of the EMF was calculated to be 0.48 ± 0.05 mG.). Significant ( P < 0.05) decreases were determined among the groups in terms of reproductive organ weights (uterus and ovaries) and progesterone and estrogen levels in relation to the varying periods of the estrous cycle. Although marked reductions ( P < 0.05) were observed among the groups in relation to plasma catalase activity, depending on exposure time, no significant differences were found in terms of glutathione and malondialdehyde levels. It is concluded that exposure to the ELF-EMFs for different time periods produced significant decreases in plasma catalase activities in the 3-month exposure groups but no effects on progesterone level, on 17-β estradiol level, or on the morphology and weight of uterus and ovaries.

Structure and Function of the Singing Voice

2015 ◽  
pp. 2-30
Author(s):  
Gillyanne Kayes
Keyword(s):  
Developmental Stages ◽  
Vocal Tract ◽  
Singing Voice ◽  
Hormonal Change ◽  
Research Knowledge ◽  
Vocal Function ◽  
And Function ◽  
The Impact ◽  
The Voice ◽  
Structural Aspects

Key structural aspects of the vocal mechanism and the physiology of vocal function are presented and discussed in relation to the singing voice. Details of anatomical structure and physiological function are given for the regions of the vocal tract and respiratory system under the broad headings of respiration, phonation (the larynx), and resonation. Use of voice in singing is examined in terms of breath use, control of pitch, and loudness, and shaping of resonance for change of timbre. Key developmental stages during the lifecycle are given, including infancy, childhood, voice mutation in adolescence, and the impact of hormonal change on the voice. Differences between the genders in adulthood are discussed in the light of current research knowledge of voice.

Dissociation of ammoniagenic enzyme adaptation in rat S1 proximal tubules and ammonium excretion response

1994 ◽  
Vol 267 (3) ◽  
pp. F407-F414 ◽  
Author(s):  
S. R. DiGiovanni ◽  
K. M. Madsen ◽  
A. D. Luther ◽  
M. A. Knepper
Keyword(s):  
Fold Increase ◽  
Proximal Tubules ◽  
Ammonium Excretion ◽  
Production Rates ◽  
Ammonium Production ◽  
Enzyme Adaptation ◽  
Acid Loading ◽  
Microdissected Tubules

We measured ammonium production rates, phosphate-dependent glutaminase (PDG) activity, and glutamate dehydrogenase (GDH) activity in microdissected S1 proximal tubules of rats to investigate the role of adaptations of PDG activity and GDH activity in response to a step increase in acid intake. In vivo ammonium excretion increased much more rapidly than did single-tubule ammonium production in vitro or ammoniagenic enzyme activities measured in microdissected tubules, manifesting an 85-fold increase in the first 24 h. In vitro ammonium production rates in microdissected tubules rose only twofold in the first 24 h, fourfold by day 2, and fivefold by day 4 of acid loading. The adaptation of PDG activity paralleled the increase in single-tubule ammoniagenic capacity measured in vitro. GDH activity, on the other hand, did not change significantly even after 4 days of acid loading. From these observations, we conclude that 1) the adaptation of in vitro ammoniagenic capacity in S1 proximal tubules is temporally associated with an adaptation in PDG activity and not GDH activity, and 2) a major portion of the increased ammonium excretion seen in the first 24 h is due to factors other than an adaptive increase in ammoniagenic enzyme activity.

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