Rate of reproductive involution following either exposure to short days or daily administration of melatonin is faster in inbred than in random-bred female Syrian hamsters

1989 ◽  
Vol 120 (3) ◽  
pp. 489-496 ◽  
Author(s):  
R. J. Reiter ◽  
I. Sabry ◽  
M. Nordio ◽  
M. K. Vaughan ◽  
S. Migliaccio
Keyword(s):  
Day Treatment ◽  
Plasma Concentrations ◽  
The Other ◽  
Plasma Prolactin ◽  
Hormonal Changes ◽  
Syrian Hamsters ◽  
Short Day ◽  
Melatonin Administration ◽  
Short Days ◽  
Marked Drop

ABSTRACT The onset of cessation of oestrous cyclicity and associated organ and hormonal changes were compared in random-bred (RB) and inbred (IB) female Syrian hamsters kept either under short days (8 h light:16 h darkness; 8L:16D) or long days (14L:10D) and given daily afternoon injections of 25 μg melatonin. In response to short-day treatment, 100% of the IB hamsters exhibited vaginal acyclicity within 35 days; by comparison, none of the RB animals were acyclic at this time. The IB hamsters also exhibited other changes associated with exposure to short days, including increased body weight, enlarged ovaries, regressed uteri, elevated pituitary concentrations of FSH, and depressed pituitary and plasma concentrations of prolactin. At this time, only the pituitary FSH levels were increased in the RB animals kept under the same short-day conditions. In a second experiment, RB and IB female Syrian hamsters were maintained under long days (14L:10D) and the rate of reproductive regression in response to daily afternoon injections of melatonin was compared. After 8 weeks of melatonin injections, 80% of the IB females were anoestrous, while all RB hamsters were still exhibiting 4-day oestrous cycles. Other changes associated with melatonin administration in the IB females included a marked drop in uterine weight and a depression in pituitary and plasma prolactin levels. The RB hamsters, although they were all still cyclic after 8 weeks, had increased body and ovarian weights, increased pituitary concentrations of FSH, and lower pituitary and plasma prolactin levels. The results show that the IB strain of Syrian hamster, compared with the RB strain, responded more quickly with vaginal acyclicity to both exposure to short days and daily injections of melatonin. On the other hand, the IB hamsters responded more slowly in terms of oestrous acyclicity to melatonin injections than to treatment with short photoperiod. Journal of Endocrinology (1989) 120, 489–496

scholarly journals Influence of daylength on vernalization of winter rye. 2. Continued experiments with short-day vernalization in winter rye.

1966 ◽  
Vol 14 (2) ◽  
pp. 89-102
Author(s):  
T.A. Hartman
Keyword(s):  
Day Treatment ◽  
Cold Treatment ◽  
Winter Rye ◽  
Optimum Duration ◽  
Short Day ◽  
Accelerate Development ◽  
Short Days

In vernalization trials with winter rye, short-day treatment prior to cold treatment was capable of inducing accelerated development and early ear emergence even when the temperature during the former treatment was 25 degrees C. Short days imposed during protracted cold treatments could also accelerate development provided that the optimum duration of short-day vernalization (about 14 days) was not exceeded. Results confirmed the assumption that cold vernalization and short-day vernalization were different processes. [See also F.C.A. 18: 1236].-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Managing flowering time in Miscanthus and sugarcane to facilitate intra- and intergeneric crosses

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0240390
Author(s):  
Hongxu Dong ◽  
Lindsay V. Clark ◽  
Xiaoli Jin ◽  
Kossonou Anzoua ◽  
Larisa Bagmet ◽  
...  
Keyword(s):  
Flowering Time ◽  
High Latitude ◽  
Floral Induction ◽  
Day Treatment ◽  
Day Length ◽  
Close Relative ◽  
Short Day ◽  
Culm Length ◽  
Low Latitudes ◽  
Short Days

Miscanthus is a close relative of Saccharum and a potentially valuable genetic resource for improving sugarcane. Differences in flowering time within and between Miscanthus and Saccharum hinders intra- and interspecific hybridizations. A series of greenhouse experiments were conducted over three years to determine how to synchronize flowering time of Saccharum and Miscanthus genotypes. We found that day length was an important factor influencing when Miscanthus and Saccharum flowered. Sugarcane could be induced to flower in a central Illinois greenhouse using supplemental lighting to reduce the rate at which days shortened during the autumn and winter to 1 min d-1, which allowed us to synchronize the flowering of some sugarcane genotypes with Miscanthus genotypes primarily from low latitudes. In a complementary growth chamber experiment, we evaluated 33 Miscanthus genotypes, including 28 M. sinensis, 2 M. floridulus, and 3 M. ×giganteus collected from 20.9° S to 44.9° N for response to three day lengths (10 h, 12.5 h, and 15 h). High latitude-adapted M. sinensis flowered mainly under 15 h days, but unexpectedly, short days resulted in short, stocky plants that did not flower; in some cases, flag leaves developed under short days but heading did not occur. In contrast, for M. sinensis and M. floridulus from low latitudes, shorter day lengths typically resulted in earlier flowering, and for some low latitude genotypes, 15 h days resulted in no flowering. However, the highest ratio of reproductive shoots to total number of culms was typically observed for 12.5 h or 15 h days. Latitude of origin was significantly associated with culm length, and the shorter the days, the stronger the relationship. Nearly all entries achieved maximal culm length under the 15 h treatment, but the nearer to the equator an accession originated, the less of a difference in culm length between the short-day treatments and the 15 h day treatment. Under short days, short culms for high-latitude accessions was achieved by different physiological mechanisms for M. sinensis genetic groups from the mainland in comparison to those from Japan; for mainland accessions, the mechanism was reduced internode length, whereas for Japanese accessions the phyllochron under short days was greater than under long days. Thus, for M. sinensis, short days typically hastened floral induction, consistent with the expectations for a facultative short-day plant. However, for high latitude accessions of M. sinensis, days less than 12.5 h also signaled that plants should prepare for winter by producing many short culms with limited elongation and development; moreover, this response was also epistatic to flowering. Thus, to flower M. sinensis that originates from high latitudes synchronously with sugarcane, the former needs day lengths >12.5 h (perhaps as high as 15 h), whereas that the latter needs day lengths <12.5 h.

scholarly journals Photoperiodic Response of Peanut Species1

1983 ◽  
Vol 10 (2) ◽  
pp. 59-62 ◽  
Author(s):  
H. T. Stalker ◽  
J. C. Wynne
Keyword(s):  
North Carolina ◽  
Day Treatment ◽  
Photoperiodic Response ◽  
Reproductive Capacity ◽  
Arachis Species ◽  
Short Day ◽  
The North ◽  
Long Day ◽  
Wild Peanut ◽  
Short Days

Abstract Many Arachis species collections do not produce pegs in North Carolina even though they flower profusely. To investigate reasons for the failure of fruiting, nine wild peanut species of section Arachis and three A. hypogaea cultivars representing spanish, valencia and virginia types were evaluated for response to short and long-day treatments in the North Carolina State Phytotron Unit of the Southeastern Environmental Laboratories. The objective of this investigation was to determine the flowering and fruiting responses of Arachis species to short and long-day photoperiods. Plant collections grown under a 9-hour short-day treatment were generally less vigorous, but produced more pegs than corresponding plants grown in long-day treatments which were produced by 9 hours of light plus a 3-hour interruption of the dark period. Annual species produced significantly more flowers and pegs than perennial species during both long and short days. The total number of flowers produced ranged from 0 during short days for A. correntina to more than 300 for A. cardenasii in long-day treatments. Only one plant of each species A. chacoense and A. villosa, and no plants of A. correntina, flowered in short days. Total numbers of pegs produced in short-day treatments were generally greater than in long-day treatments and the ratio of total number of pegs/total number of flowers was consistently greater during short-day treatments. A general trend was observed for more flowers produced in long-day treatments, but more pegs produced in short days. This study indicated that photoperiod can be manipulated to increase the seed set of some species and the success rate of obtaining certain interspecific hybrids. Furthermore, introgression from wild to cultivated species may possibly alter the reproductive capacity of A. hypogaea to photoperiod.

A neuroendocrine model for prolactin as the key mediator of seasonal breeding in birds under long- and short-day photoperiods

2003 ◽  
Vol 81 (4) ◽  
pp. 350-358 ◽  
Author(s):  
Peter J Sharp ◽  
Dominique Blache
Keyword(s):  
Breeding Season ◽  
Plasma Concentrations ◽  
Prolactin Secretion ◽  
Gonadotropin Releasing Hormone ◽  
Critical Threshold ◽  
Plasma Prolactin ◽  
Seasonal Breeding ◽  
Releasing Hormone ◽  
Short Day ◽  
Long Day

Seasonal breeding is associated with sequential increases in plasma luteinizing hormone (LH) and prolactin in the short-day breeding emu, and in long-day breeding birds that terminate breeding by the development of reproductive photorefractoriness. A model of the avian neuroendocrine photoperiodic reproductive response is proposed, incorporating a role for prolactin, to account for neuroendocrine mechanisms controlling both long- and short-day breeding. The breeding season terminates after circulating concentrations of prolactin increase above a critical threshold to depress gonadotropin releasing hormone (GnRH) neuronal and gonadotrope (LH) activity. Subsequently, photorefractoriness develops for prolactin secretion and for LH secretion, independently of high plasma prolactin. The breeding season in the emu is advanced compared with long-day breeders, because after photorefractiness for both LH and prolactin secretion is dissipated, plasma concentrations of both hormones increase to maximum values while days are still short.Key words: seasonal breeding, prolactin, gonadotropin releasing hormone, photorefactoriness.

scholarly journals Chrysanthemum Cultivars Differ in Response to Photoperiod when Grown under Far-red Absorbing Filters

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 437A-437
Author(s):  
M.J. McMahon
Keyword(s):  
Acetic Acid ◽  
Ethyl Alcohol ◽  
The Other ◽  
Short Day ◽  
Long Day ◽  
Floral Primordia ◽  
Lateral Branches ◽  
And Control ◽  
Short Days

Two chrysanthemum [Dendranthema × grandiflorum (Ramat) Kitamura] cultivars, Bright Golden Anne and Spears, were grown in unfiltered sunlight (control) or under filters that removed far-red (FR) light under long- or short-day photoperiods for a total of four treatments. Eight plants from each cultivar were exposed to each treatment. Tips of lateral branches were harvested every 3 days and preserved in formalin, acetic acid, 70% ethyl alcohol (5:5:90 by volume), then observed and photographed under a dissecting microscope. In `Spears', all short-day treatments developed floral primoridia at the same time and rate and the development was normal. Under long days and under FR-absorbing filters, floral primordia initiated and developed normally, but was delayed several days compared to short days. Plants under long days and control filters also developed normal primoridia, but at a slower rate than any of the other treatments. In `Bright Golden Anne', only short-day treatments developed normal floral primordia. Development was the same regardless of filter. Under long days, plants under FR-absorbing filters eventually initiated floral primordia, but development was abnormal. No floral primordia developed under long-day and control filter conditions. In all cases, `Spears' primoridia development was much more rapid than `Bright Golden Anne'.

Adrenal, thyroid, and testicular hormone rhythms in male golden hamsters on long and short days

1987 ◽  
Vol 253 (2) ◽  
pp. R321-R328 ◽  
Author(s):  
J. E. Ottenweller ◽  
W. N. Tapp ◽  
D. L. Pitman ◽  
B. H. Natelson
Keyword(s):  
Plasma Levels ◽  
Plasma Concentrations ◽  
Plasma Corticosterone ◽  
Major Effect ◽  
Primary Effect ◽  
Dark Cycle ◽  
Short Day ◽  
The Many ◽  
Male Golden Hamsters ◽  
Short Days

Plasma concentrations of adrenal, thyroid, and testicular hormones were measured at 4-h intervals around the clock in male hamsters on long (14:10-h light-dark cycle) and short (10:14-h light-dark cycle) days. Plasma corticosterone, cortisol, thyroxine (T4), triiodothyronine (T3), and testosterone rhythms were present on long days. The only one of these hormones to have a significant rhythm on short days was cortisol, but even its amplitude was suppressed compared with the cortisol rhythm on long days. Short days also lowered mean plasma levels of cortisol, T4, T3, and testosterone. Finally, short days raised the ratio of corticosterone to cortisol and lowered the ratio of T4 to T3. Both ratios had significant rhythms on long days but not on short days. Because of the many interactions among adrenal, thyroid, and testicular hormone axes, it is unclear whether the primary effect of short days is on one of these endocrine systems or on another factor that has separate effects on each of the hormone rhythms that was measured. Nonetheless, it is clear that a major effect of short day lengths in hamsters is to suppress hormone rhythms. Explanations of photoperiodic effects that depend on endocrine mediation should take this into account.

Inhibitory effect of increased photoperiod on wool follicle growth

1996 ◽  
Vol 148 (1) ◽  
pp. 157-166 ◽  
Author(s):  
A J Pearson ◽  
A L Parry ◽  
M G Ashby ◽  
V J Choy ◽  
J E Wildermoth ◽  
...  
Keyword(s):  
Day Treatment ◽  
Inhibitory Effect ◽  
Plasma Prolactin ◽  
Follicle Growth ◽  
Primary Follicle ◽  
Winter Solstice ◽  
Natural Photoperiod ◽  
Wool Follicle ◽  
Plasma Prl ◽  
Short Days

Abstract The relationships between circulating prolactin (PRL), wool follicle growth and daylength were investigated in 24 New Zealand Wiltshire ewes housed indoors from September 1989 to May 1991. Twelve control (C) ewes were maintained under natural photoperiod. Two other groups were held in short days (SD; 8 h light:16 h darkness) commencing from the winter solstice (22 June 1990) for either three (group SD3, n=7) or six (group SD6, n=5) months before reversion to natural daylength. Skin was sampled at one- to four-week intervals for histological determination of percentages of growing primary and secondary follicles. Hourly blood samples over 24 h were collected via jugular cannulae from C sheep in March and July and then monthly from all animals until December 1990 for estimation of mean monthly PRL concentrations for each treatment group. Between autumn (March 1990) and winter (July) primary follicle activity (PFA) and secondary follicle activity (SFA) declined in C ewes (PFA: 97 to 43%, SFA: 100 to 57%). Follicle regrowth during July and August in eight C ewes preceded the initial rise in plasma PRL from the winter minimum (1·6 ng/ml). Across the three groups, four instances of decreased follicle activity were observed, closely following or concurrent with increases in plasma PRL concentrations. The resumption of spring growth in four C sheep was temporarily checked by falls in follicle activities during September and October as PRL concentrations began to increase (3·4 to 8·9 ng/ml). Follicle activity also declined in November and December in eight C sheep, coincident with the rapid rise in PRL to a seasonal maximum in late November (165·4 ng/ml). The increase in SD3 follicle activity over spring was not delayed by short days but during October, after release from treatment, PRL concentrations rose (1·8 to 12·0 ng/ml) and follicle activity declined (PFA: 65 to 38%, SFA: 68 to 43%). In SD6 ewes, PRL concentrations were suppressed (2·1 ng/ml) and relatively constant levels of follicle activity (PFA: 73%, SFA: 95%) were maintained throughout short-day treatment. Release of SD6 ewes into summer photoperiod in January 1991 temporarily interrupted follicle growth (PFA: 68 to 17%, SFA: 96 to 19%) and caused out-ofseason shedding in March and April. Contemporary C follicle activities were high (PFA: 95%, SFA: 98%). These data suggest that natural and experimental increases in daylength have a short-term inhibitory effect on growing wool follicles which could be mediated through rising concentrations of plasma prolactin. Journal of Endocrinology (1996) 148, 157–166

Temperature dependence of gonadal regression in Syrian hamsters exposed to short day lengths

2002 ◽  
Vol 282 (3) ◽  
pp. R744-R752 ◽  
Author(s):  
Jennie E. Larkin ◽  
Jennifer Jones ◽  
Irving Zucker
Keyword(s):  
Locomotor Activity ◽  
Gonadal Function ◽  
Melatonin Secretion ◽  
Syrian Hamsters ◽  
Short Day ◽  
Testicular Regression ◽  
Testis Volume ◽  
To Receive ◽  
Short Days ◽  
Do So

We sought to determine whether ambient temperature (Ta) affects gonadal function by altering the rate at which circadian rhythms entrain to short day lengths. Syrian hamsters were housed in cages where they received 14 h of light per day (“long days,” 14L) at 22°C. Hamsters were then transferred to cages to receive 10 h of light per day (“short days,” 10L) and kept at 5, 22, or 28°C or were maintained in 14L at 22°C. Body mass and estimated testis volume as well as duration of nocturnal locomotor activity (α), previously established as a reliable indicator of the duration of nocturnal melatonin secretion, were determined over the course of 24 wk. Testicular regression in short days was accelerated by 4 wk at 5°C and delayed by 3 wk at 28°C relative to 22°C. The interval between α-expansion and initiation of testicular regression was markedly affected by Ta with delays of 0, 3, and 6 wk at 5, 22, and 28°C, respectively. All hamsters held at 5 and 22°C underwent testicular regression, but 25% of those maintained at 28°C failed to do so. We suggest that Ta modulates testicular regression primarily by affecting responsiveness of neuroendocrine target tissues to long melatonin signals.

EFFECT OF PHOTOPERIOD ON DROUGHT RESISTANCE OF WHITE SPRUCE SEEDLINGS

1960 ◽  
Vol 38 (4) ◽  
pp. 597-599 ◽  
Author(s):  
O. Vaartaja
Keyword(s):  
Drought Resistance ◽  
Picea Glauca ◽  
Day Treatment ◽  
White Spruce ◽  
The Other ◽  
Severe Drought ◽  
Drought Treatment ◽  
Short Day ◽  
Long Day ◽  
Other Hand

Seedlings of Picea glauca were grown for 2 months under three photoperiodic treatments. Short day treatment induced early terminal dormancy and resistance to severe drought treatment. Long day treatments, on the other hand, allowed prolonged growth of most seedlings and made them susceptible to drought.

Role of prolactin in the photoperiodic control of moulting in the mink (Mustela vison)

1984 ◽  
Vol 103 (1) ◽  
pp. 9-15 ◽  
Author(s):  
L. Martinet ◽  
D. Allain ◽  
C. Weiner
Keyword(s):  
Physiological Role ◽  
Plasma Prolactin ◽  
Summer Solstice ◽  
Natural Lighting ◽  
Short Day ◽  
Lighting Conditions ◽  
Natural Photoperiod ◽  
Moulting Cycle ◽  
Short Days

ABSTRACT Beginning at the summer solstice adult female mink were maintained in long- or short-day photoperiods and treated with bromocriptine or prolactin. In control females kept under natural lighting conditions the moult coincided with the seasonal decrease in prolactin and resulted in the growth of a dense winter coat which was completed by the end of November. Long days, which slowed the decrease in plasma prolactin relative to animals in the natural photoperiod, induced a more or less complete moult followed by growth of a thin summer coat. On the contrary we observed an accelerated decrease in plasma prolactin concentrations followed by an early and brief moult in females kept under long days but treated with bromocriptine and in females under short days. The growth of a dense winter coat was completed by the end of September in all the females of the short-day group and in six of eleven females treated with bromocriptine. In the other five females, moult was followed by the growth of a summer coat. These results may suggest that the decline of prolactin after the summer solstice is responsible for the onset of the autumn moult, but the early, abbreviated moult and the growth of a winter coat observed in females kept under short days and treated with prolactin do not seem to support this hypothesis. However, the huge non-physiological levels of prolactin measured in the plasma of these females and the appearance of abnormal white under-hairs might suggest that the hormonal balance in this group was completely disturbed by the treatment. The physiological role of prolactin in the seasonal moulting cycle in mink is discussed. J. Endocr. (1984) 103,9–15

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