Developmental Changes In Response Research Articles

Developmental changes in response to γ-aminobutyric acid, 3-aminopropane sulphonic acid and baclofen in rat duodenum

Developmental changes in response to γ-aminobutyric acid, 3-aminopropane sulphonic acid and baclofen in rat duodenum

Developmental Changes in Response to Overfeeding: Effect on Composition of Gain, Liver Metabolism and Adipocyte Cellularity in Rats

It has been proposed that voluntary food intake limits growth rate. The experiment described here investigated the effects of increased food intake on growth rate. Four age groups of female rats were given either 150 or 100 of ad libitum intake by oral gavage. Animals were tube-fed at these levels of intake for 1 wk. Overfeeding significantly increased carcass weight and fat for all ages examined. Carcass protein was significantly elevated in the overfed animals for the two youngest age groups. Differences between age groups in apparent energetic efficiency were small. Hepatic palmitate oxidation was depressed and esterification increased in all overfed rats. Fat cell size was increased by overfeeding in all age groups. In conclusion, the effects of overfeeding on the four age groups of rats studied were independent of age.

Histamine response in developing chick oesophagus

Developmental changes in response to histamine were investigated in the oesophagus isolated from the chick between 15 days of incubation and 15 days after hatching. The contraction could be already caused by histamine (20 microM) in the chick oesophagus from 15 days of incubation. The pD2 values for histamine and acetylcholine did not change during the period between 17 days of incubation and 5 days after hatching. The response to histamine (20 microM) was extremely resistant to tetrodotoxin (0.78 microM), procaine (0.2 mM) and atropine (1 microM) during the period between 17 days of incubation and 20 days of incubation. The tetrodotoxin-resistant response was replaced by a tetrodotoxin-sensitive response after hatching. On the other hand, the neuronal response induced by transmural electrical stimulation (20 Hz) or dimethylphenylpiperazinium (20 microM) was uniformly sensitive to tetrodotoxin throughout the periods. Mepyramine (2 microM), but not metiamide (20 microM), inhibited the histamine-induced responses in every age tested. These results suggest that the myogenic receptivity of histamine transiently increases during the terminal period of embryonic development and declines after hatching.

Changes in responsiveness to ethylene and gibberellin during corolla expansion ofIpomoea nil

Corolla expansion inIpomoea nil appears to be triggered by changes in gibberellin concentration and ethylene production during development. We investigated the role of responsiveness to GA and ethylene in corolla expansion. The effects of growth regulators applied in vitro were measured as a change in area of corolla segments from younger (15–17 mm) and older (18–20 mm) whole corollas. Applied gibberellic acid (GA3) significantly (p < 0.05) promoted growth in the younger segments but was less effective in the older segments. Moreover, applications of the GA biosynthesis inhibitors, PP333 (paclobutrazol) AMO1618 (2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidinecarboxylate methyl chloride), chlorocholine chloride, and tetcyclasis had little effect on younger segments but inhibited growth of older segments. The older corollas have apparently synthesized and accumulated enough GA-like substances to become less responsive to additional applied GA3. The amount of growth induced by applied or endogenous GA depended on the amount of ethylene simultaneously produced in the tissue. The younger corollas rapidly produced ethylene from endogenous 1-aminocyclopropane-1-carboxylic acid (ACC) and did not respond to applied ACC whereas the older corollas naturally produced much less ethylene and were significantly (p < 0.05) inhibited by applied ACC. When ethylene production was inhibited by applying aminoethoxyvinylglycine (AVG), growth was promoted in all segments. However, only the growth of the younger segments was further stimulated by simultaneously applied AVG and GA3 over the GA3 control. Thus the differential responses of segments from 15- to 20-mm long corollas to applied growth regulators reflect developmental changes in responsiveness of the developing corolla. The change in responsiveness is attributed in part to the changes in production of endogenous growth regulators and to the effect of one endogenous plant growth regulator (PGR) on the responsiveness of the corolla to another PGR.

Developmental changes in responsiveness to vitamin D metabolites

We have demonstrated that epiphyseal chondroblasts contain specific receptors for 24R,25-dihydroxy vitamin D 3(24,25(OH) 2D 3) while diaphyseal osteoblasts contain specific receptors for 1α25-dihydroxy vitamin D 3(1,25(OH) 2D 3). Both metabolites induce DNA synthesis and creatine kinase (CKBB) activity. We have also found that the responsiveness of rat kidney to these metabolites changes during development. In embryonic and early postnatal stages, the kidney responds to 24,25(OH) 2D 3, later to both 24,25(OH) 2D 3 and 1,25(OH) 2D 3, and the mature kidney only to 1,25(OH) 2D 3. These responses correlate with changes in the specific receptors present in the kidney. Furthermore, we have compared developmental changes in skeletal (epiphysis, diaphysis and mandibular condyle) and non-skeletal (kidney, cerebellum, cerebrum, liver and pituitary) tissue in both rat (a postnatal developer) and rabbit (a perinatal developer). Epiphyseal or diaphyseal chondroblasts at any stage of development were predominantly responsive to 24,25(OH) 2D 3, whereas osteoblasts were responsive to 1,25(OH) 2D 3. In contrast, condylar chondroblasts, kidney, cerebellum and pituitary responded to 24,25(OH) 2D 3 during early development and subsequently developed responsiveness to 1,25(OH) 2D 3. Using primary cell cultures from kidneys at different stages of maturation, we showed the same developmental pattern as in vivo. Chronic treatment of the cells with 24,25(OH) 2D 3, but not 1,25(OH) 2D 3, caused precocious development of responsiveness to 1,25(OH) 2D 3 in culture. We suggest that 24,25(OH) 2D 3 acts as a maturation factor, during early development in kidney, and probably in other tissues, possibly by induction of receptor to 1,25(OH) 2D 3, accompanied by down-regulation of its own receptor.

Developmental changes in decoding discrepant and nondiscrepant nonverbal cues.

In this study we examined developmental changes in responses to consistent and discrepant video and audio nonverbal cues. A videotaped Nonverbal Discrepancy Test was administered to children aged 9-15 years. The discrepancy test measures (a) decoding accuracy—the extent to which subjects are able to identify affects (positivity and dominance) from visual (facial and body) cues and audio (content-filtered and random-spliced) cues—and (b) video primacy—the extent to which subjects are more influenced by video (face or body) than by audio cues. It was found that older children were more accurate at decoding affects than were younger children, particularly dominance-submission cues. Video primacy increased with age for facial cues (but not for body cues) and for cues of positivity (but not for cues of dominance). Relative to males younger female subjects showed more video primacy and older female subjects showed less video primacy, particularly for cues of dominance-submission. Relative to younger children older children showed less video primacy in decoding extremely discrepant audio and video cues than in decoding moderately discrepant audio and video cues. The development of nonverbal sensitivity to video and audio cues is discussed.

Developmental Changes in Response to Frustration Among Physically Handicapped Children

Click to increase image sizeClick to decrease image size Additional informationNotes on contributorsDenis J. LynchDenis J. Lynch and Charles Arndt are at The University of Toledo, Toledo, Ohio. Condensed from Journal of Personality Assessment, 1973, 37, 130–135.Charles ArndtDenis J. Lynch and Charles Arndt are at The University of Toledo, Toledo, Ohio. Condensed from Journal of Personality Assessment, 1973, 37, 130–135.

Developmental changes in response to frustration among physically handicapped children.

Summary Methods of coping with frustration were examined in handicapped and nonhandicapped children at three different age levels, by means of the Rosenzweig P-F Study. While an extrapunitive approach was predominant in both groups and did not differ between the groups, significant differences were found in the use of secondary coping strategies. When compared with nonhandicapped counterparts, handicapped six year olds were more likely to minimize or deny frustration. At 10 years, handicapped Ss were more likely than nonhandicapped Ss to be intropunitive or self-blaming. There was a developmental tendency for handicapped Ss to make greater use of intropunitive responses with increasing age.

Developmental Changes in Responsiveness in the Great Tit (Parus Major)

[Experiment I was carried out to test the hypothesis that the capacity to refrain from responding when reinforcement is withdrawn (behaviour dependent on internal inhibition) is weak in very young birds, develops as a result of age and also as a result of variety of experience during the juvenile stage and later weakens slightly. Two groups of birds were given the task of differentiating between a dish containing food and covered with a white lid and an empty dish covered with a black lid. All were wild birds, but Group I were taken as nestlings, reared by hand and kept indoors. Group II were taken as juveniles or as adults, tested indoors and then released. They were tested at ages ranging from 4½ weeks onwards. The results as they stand are consistent with the hypothesis stated, but some difficulties of interpretation are discussed. In Experiment II an attempt was made to measure changes in level of activity or positive responsiveness in a single brood of hand-reared great tits during a period of time comparable with Experiment I. In two experiments where (1) a previously reinforced and (2) a completely unfamiliar object was introduced into the birds' cages for a limited period of time, the length of time spent by birds pecking and pulling at this object appeared to increase until about 12-15 weeks after fledging, and later decreased again. In the discussion the relation between results from Experiments I and II are considered: it is suggested that changes observed in internal inhibition and positive responsiveness may in fact be changes in different aspects of excitability. This would suggest that excitability increases up to a certain age, and then falls off again., Experiment I was carried out to test the hypothesis that the capacity to refrain from responding when reinforcement is withdrawn (behaviour dependent on internal inhibition) is weak in very young birds, develops as a result of age and also as a result of variety of experience during the juvenile stage and later weakens slightly. Two groups of birds were given the task of differentiating between a dish containing food and covered with a white lid and an empty dish covered with a black lid. All were wild birds, but Group I were taken as nestlings, reared by hand and kept indoors. Group II were taken as juveniles or as adults, tested indoors and then released. They were tested at ages ranging from 4½ weeks onwards. The results as they stand are consistent with the hypothesis stated, but some difficulties of interpretation are discussed. In Experiment II an attempt was made to measure changes in level of activity or positive responsiveness in a single brood of hand-reared great tits during a period of time comparable with Experiment I. In two experiments where (1) a previously reinforced and (2) a completely unfamiliar object was introduced into the birds' cages for a limited period of time, the length of time spent by birds pecking and pulling at this object appeared to increase until about 12-15 weeks after fledging, and later decreased again. In the discussion the relation between results from Experiments I and II are considered: it is suggested that changes observed in internal inhibition and positive responsiveness may in fact be changes in different aspects of excitability. This would suggest that excitability increases up to a certain age, and then falls off again.]