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Biomedical subjects

A H Meier

Publications and source records attributed to A H Meier.

86 records · Page 5Linked to original sources
PubMed1971

Temporal synergism of corticosterone and prolactin controlling gonadal growth in sparrows.

Gonadal growth was controlled in two avian species by corticosterone and prolactin injected daily at various times. Testicular growth was induced in photorefractory house sparrows (Passer domesticus) kept in continuous light by prolactin injected 4 or 8 hours after administration of corticosterone. Other temporal patterns were ineffective. Gonadal growth was also stimulated in photosensitive white-throated sparrows (Zonotrichia albicollis) kept in continuous light by prolactin injected 12 hours after administration of corticosterone. Daily injections of prolactin 8 hours after injection of corticosterone inhibited gonadal growth. The seasonal cycle of reproductive photorefractoriness and photosensitivity is controlled by a changing relation between the daily rhythms of plasma concentrations of corticosterone and prolactin.

Adipose Tissue↗
PubMedDate not supplied

A day-night rhythm of immune activity during scale allograft rejection in the gulf killifish, Fundulus grandis.

The circadian variation of scale allograft rejection was studied in teleost fish maintained on 12-h daily photoperiods (LD 12:12). Immune activity, measured by melanophore breakdown, was two to three times greater during the dark than during the light whether scale allografts were transplanted at light onset or light offset. Because rejection occurred predominantly at night, survival times of both primary and secondary allografts were about 0.4 days longer when the transplants were made at light onset. Immune activity undergoes a robust daily variation in a teleost fish.

Animals↗
PubMedDate not supplied

Nonphotic stimuli alter a day-night rhythm of allograft rejection in gulf killifish.

The influence of environmental stimuli on a daily rhythm of immune activity during scale allograft rejection was investigated in gulf killifish, Fundulus grandis. Although melanophore destruction in the grafts is largely restricted to the scotophases in killifish held on 12 h daily photoperiods (LD 12:12), timed daily netting (tank-transfer "stress"), thermoperiods (from 20 degrees to 30 degrees C for 4 or 12 h), and feeding altered the expression of this rhythm. Melanophore breakdown peaked 0-12 h after netting or thermoperiod onset and 12-24 h after feeding, whether the fish were exposed to these nonphotic daily stimuli at the onset or offset of 12-h photoperiods. In fish held under continuous light and pretreated with these daily stimuli, 24-h immune activity rhythms persisted in the altered phases for several days after the daily treatments were stopped. These findings suggest that a daily rhythm of immune activity may have adaptive significance in fish.

Animals↗