scholarly journals Historical Perspective and Evaluation of the Mechanisms by which Melatonin Mediates Seasonal Reproduction in Mammals

2018 ◽  
Vol 1 (1) ◽  
pp. 59-77 ◽  
Author(s):  
Russel J Reiter ◽  
Dun-Xian Tan ◽  
Ramaswamy Sharma
Keyword(s):  
Pineal Gland ◽  
Reproductive Organs ◽  
Day Length ◽  
Optimal Time ◽  
Seasonal Reproduction ◽  
Pars Tuberalis ◽  
Short Day ◽  
Long Day ◽  
Time Of Year ◽  
Photoperiod Sensitive

The discovery of melatonin and its photoperiod-regulated circadian rhythm were important milestones in defining the events associated with the regulation of seasonal reproduction in both short-day and long-day breeding mammals. By means of the seasonal changes in the duration of the nocturnal melatonin rise, which provides both clock and calendar information, animals adjust their reproductive state to the appropriate time of year. Thus, melatonin dictates the proper season for mating which ensures the optimal time for delivery of offspring. The photoperiodic information is transduced into a chemical messenger, melatonin, in the pineal gland. The initial studies related to the importance of day length and the melatonin message in impelling seasonal reproduction involved the use of photoperiod-sensitive rodents, especially several long-day breeding hamster species. Since then, a large group of interested reproductive biologists have extended these findings to numerous other mammals including short-day breeding ungulates. Moreover, critical information related to the molecular processes at the level of the pars tuberalis of the anterior pituitary and the mediobasal hypothalamus has been provided. In this scheme, the pars tuberalis, until recently an almost ignored portion of the adenohypophysis, has been identified as a critical intermediate between the melatonin signal and the functional state of the reproductive organs. It is somewhat ironic that two organs, the pineal gland and the pars tuberalis, which suffered with the image of vestigiality for so long have now been identified as unequivocally essential for this most basic and important function, i.e., regulating seasonal reproduction.

A method for induction and quantification of diapause entry in the swede midge (Diptera: Cecidomyiidae)

2012 ◽  
Vol 144 (6) ◽  
pp. 792-800 ◽  
Author(s):  
Lauren E. Des Marteaux ◽  
Marc B. Habash ◽  
Jonathan M. Schmidt ◽  
Rebecca H. Hallett
Keyword(s):  
Diapause Induction ◽  
Day Length ◽  
Retrieval Method ◽  
Short Day ◽  
Long Day ◽  
Rearing Conditions ◽  
Swede Midge ◽  
Pupal Mortality ◽  
Contarinia Nasturtii ◽  
Cool Conditions

AbstractInduction of diapause under laboratory conditions is a valuable tool for the study of dormancy in economic pests such as the swede midge, Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae). In the present study, diapause in larval swede midge was achieved via manipulation of rearing photoperiod and temperature. Frequency of diapause was assessed by sieve separation of diapause cocoons from pre-sifted peat substrate following emergence of pupating individuals. Mean diapause frequency for swede midge larvae reared under cool conditions with short day length or cool conditions with decreasing day lengths were 45.2% and 19.5%, respectively. Only 1.2% of swede midge reared under warm, long day length conditions entered diapause. A small percentage of larvae neither pupated nor entered diapause and remained in substrate long after other individuals had emerged as adults. This behaviour was more prevalent under cool and short or decreasing day length rearing conditions. Approximately 76% of the larvae used for diapause induction were recovered with the present larval and cocoon retrieval method, and premature (larval and pupal) mortality averaged 18.2%. Although diapause occurred in the present study, conditions resulting in higher diapause frequencies should be investigated and attempts should be made to improve survival and recovery of individuals.

scholarly journals Responses of earliness and lateness genes for heading to different photoperiods, and specific response of a gene or a pair of genes to short day length in rice

Hereditas ◽  
2019 ◽  
Vol 156 (1) ◽  
Author(s):  
Birendra Bahadur Rana ◽  
Misa Kamimukai ◽  
Mukunda Bhattarai ◽  
Yohei Koide ◽  
Masayuki Murai
Keyword(s):  
Genetic Factors ◽  
Day Length ◽  
Specific Response ◽  
Near Isogenic Lines ◽  
Heading Time ◽  
Short Day ◽  
Long Day ◽  
Days To Heading ◽  
Important Trait ◽  
Spring Sowing

Abstract Background Heading time is an important trait for regional and seasonal adaptabilities in rice, and is controlled by genetic factors in relation with environmental factors, mainly day length and temperature. The following genes controlling heading were examined for their responses to six different environmental conditions involving different day lengths using five early near-isogenic lines (NILs) of T65-R and three late NILs of T65wx: two earliness genes, Ef1 and Efx controlling basic vegetative phase (BVG), and m-Ef1, the enhancer to the former gene; and two lateness genes, Se1-pat(t) and se-pat controlling photo-sensitivity and BVG, respectively. T65-R and T65-T were different accessions of Taichung 65. T65wx is a NIL of T65-T carrying wx. Results The five early NILs of T65-R were in the order of ER50 (Ef1, Efx, m-Ef1) < ER40 (Ef1, m-Ef1) ≤ ER20 (Ef1, Efx) < ER1 (Ef1) ≤ ER21 (Efx) < T65-R regarding days to heading (DTH) under two spring-sowing and one summer-sowing paddy field (PF) conditions. The three late NILs of T65wx were in the order of LF3 (Se1-pat(t)) ≤ LF2 (Se1-pat(t), se-pat) ≤ T65wx < LF1 (se-pat) under two short-day conditions (10-h photoperiod condition with artificial-light and natural short-day condition from autumn to winter). The NILs and T65wx were in the order of T65wx < LF3 < LF1 < LF2 under the two spring-sowing PF (long day) conditions. T65-R (Ac-ef1) was 2.8 or 5.1 days earlier in DTH than T65-T (ac-ef1) under the two spring-sowing PF conditions. However, T65-R was 19 and 10 days earlier than T65-T under the two short-day conditions. Conclusions Earliness gene(s) and their combinations reduced DTH regardless of photoperiod lengths. Se1-pat(t) increased DTH under long-day conditions but decreased it under short-day conditions, while se-pat elongated DTH under both short-day and long-day conditions indicating that se-pat is responsible for BVG. The se-pat increased DTH by adding its effect over that of Se1-pat(t) under long-day conditions. However, this increasing effect of DTH by se-pat was almost completely masked when it coexisted with Se1-pat(t) under the short-day conditions. Notably, the response of Ac-ef1 to day length was found to delay heading under the short-day conditions.

scholarly journals Four Hour Temporal Relation of 5-HTP and L-DOPA Induces Inhibitory Responses in Recrudescing Gonad of Indian Palm Squirrel (Funambulus pennantii)

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Ranjana Jaiwal ◽  
C. M. Chaturvedi
Keyword(s):  
Environmental Factors ◽  
Basic Mechanism ◽  
Inhibitory Effect ◽  
Temporal Relation ◽  
Day Length ◽  
Short Day ◽  
Long Day ◽  
Testicular Recrudescence ◽  
Neurotransmitter Activity ◽  
Seasonally Breeding

Daily injections of L-dihydroxyphenylalanine (L-DOPA, dopamine precursor) given 4 h after 5-hydroxytryptophan (5-HTP, serotonin precursor) induced inhibitory responses in recrudescing gonad (in the first week of December) of Indian palm squirrel, a seasonally breeding subtropical animal. Other temporal relations (L-DOPA given at 0, 8, 12, 16, and 20 h after 5-HTP administration) did not show any effect on the recrudescing gonad. This inhibitory effect of 4 h was evident under short day length (6 : 18) group but was masked by the increasing day length of nature (NDL, late December onwards) and increased photoperiod of long day group (16 : 8). It is apparent that seasonal testicular recrudescence of Indian palm squirrel during short day length by 4 h relation of 5-HTP and L-DOPA is not a pharmacological effect but actually is an alteration of seasonality in this annually breeding mammal. It seems that endogenous mechanism controlling seasonal testicular recrudescence of Indian palm squirrel is reset by timed daily injections of these neurotransmitter drugs. It is suggested that in spite of different environmental factors (photoperiod, humidity, etc.) used by different species to time their annual reproduction, basic mechanism of seasonality appears to be the same, that is, the temporal synergism of neurotransmitter activity.

Effects of shortened day length upon translocation and starch accumulation by maize, wheat, and pangola grass leaves

1982 ◽  
Vol 60 (8) ◽  
pp. 1304-1309 ◽  
Author(s):  
Richard C. Sicher ◽  
William G. Harris ◽  
Diane F. Kremer ◽  
N. Jerry Chatterton
Keyword(s):  
Carbon Assimilation ◽  
Pool Size ◽  
Day Length ◽  
Starch Accumulation ◽  
Leaf Extracts ◽  
Sucrose Transport ◽  
Chase Period ◽  
Short Day ◽  
Long Day ◽  
Total Pool

Rates of leaf starch accumulation in maize, wheat, and pangola grass were approximately doubled when plants were shifted from long to short day lengths, 4 days prior to measurement. There were only small changes in carbon assimilation rates and specific leaf weights. After a brief exposure to 14CO2 and after a 2-h-chase period, total label was higher in leaves of long to short day length than in long day length plants. Most of the increased 14C radioactivity in leaf extracts of long to short day length plants was recovered in the starch, protein, and neutral fractions. The translocation of 14C-labeled assimilates to roots was less in long to short day length then in long day length plants. Sucrose was increased in leaves and decreased in roots following a shift from long to short day lengths. The above findings indicated that the accumulation of assimilates in leaves of long to short day length plants was due in part to a lowered rate of sucrose transport. The rate of sucrose movement was not directly proportional to its total pool size in source leaves.

INFLUENCE OF BREED, BIRTH DATE, AGE AND BODY WEIGHT ON TESTICULAR MEASUREMENTS OF GROWING RAMS MAINTAINED IN A CONTROLLED ENVIRONMENT

1983 ◽  
Vol 63 (4) ◽  
pp. 835-847 ◽  
Author(s):  
J. N. B. SHRESTHA ◽  
P. S. FISER ◽  
G. A. LANGFORD ◽  
D. P. HEANEY
Keyword(s):  
Body Weight ◽  
Continuous Light ◽  
Skinfold Thickness ◽  
Day Length ◽  
Birth Date ◽  
Short Day ◽  
Scrotal Circumference ◽  
Long Day ◽  
Expanded Metal ◽  
Time Of Breeding

Testicular measurements, including scrotal circumference (SC), testis length (TL), testis width (TW), scrotal skinfold thickness (ST) and tonometer score (TS), and body weight (BW) were collected from 233 rams of three synthetic strains, Suffolk and Finnish Landrace breeds, at 6, 8 and 10 mo of age, at the time of first breeding in September 1981 (11–13 mo) and second breeding in April 1982 (18–21 mo). Rams were exposed to continuous light from birth to weaning (21 ± 3 days of age), to a long day-length (16 h light: 8 h darkness) from weaning to 6 mo and then to a short day-length (9 h light: 15 h darkness) to the time of breeding. Subsequently, the rams were exposed to 4 mo of long day-length followed by a 4 mo of short day-length. All rams were hysterectomy derived, housed indoors year-round on expanded metal floors in windowless barns and reared artificially. Breed, birth date, age of ram and body weight were found to have important effects (P < 0.05) on testicular measurements of growing rams, whereas, age of dam and litter size effects were absent (P > 0.05). In general, meat-type sire breeds (Strain 1 and Suffolk) had larger SC, TL, TW and BW when compared to the fecund sheep breeds (Finnish Landrace, Strains 2 and 3). Testicular measurements and BW of Finnsheep rams were smaller when compared to all other rams examined. The significance of breed and birth date effects varied as the ram progressed in age. Testicular measurements and BW increased with age of ram from 6 to 8 mo but TS showed no change. SC and BW increased substantially at 18–21 mo (April) compared to 11–13 mo (September), whereas TL, TW, ST and TS declined. SC, TL and TW were significantly correlated with each other at all ages. ST and TS were independent traits with no significant relationship to SC, TL, TW and BW. Key words: Sheep, testicular measurements, breed, birth date, age of ram, body weight

Latitude affects photoperiod-induced changes in immune response in meadow voles (Microtus pennsylvanicus)

2005 ◽  
Vol 83 (10) ◽  
pp. 1271-1278 ◽  
Author(s):  
L M Pyter ◽  
Z M Weil ◽  
R J Nelson
Keyword(s):  
Immune Responses ◽  
Microtus Pennsylvanicus ◽  
Day Length ◽  
Delayed Type Hypersensitivity ◽  
Deer Mice ◽  
Meadow Voles ◽  
Short Day ◽  
Long Day ◽  
Induced Changes ◽  
Short Days

Animals use day length (photoperiod) to time seasonal adaptations to annual changes in their environment. Reproductive adjustments in deer mice (Peromyscus maniculatus (Wagner, 1845)) from high latitudes are more extensive in response to short days than in deer mice from low latitudes. These adjustments may permit individuals to survive the severe seasonal changes (e.g., temperature and food abundance) in high-latitude environments. Immune function is also affected by photoperiod. Short days were predicted to result in elevated immune and reproductive responses in meadow voles (Microtus pennsylvanicus (Ord, 1815)) from the Northwest Territories (NWT), Canada (~62°N), compared with voles from Ohio (OH), USA (~39°N). Male voles from both latitudes were maintained in long or short days for 10 weeks prior to a delayed-type hypersensitivity (DTH) immune challenge. Both populations displayed similar testicular regression and reduction of testosterone concentrations in short days. DTH immune responses, however, diverged between the two populations. DTH immune responses were enhanced in long-day NWT voles and short-day OH voles, but decreased in short-day NWT voles and long-day OH voles. Total and free corticosterone concentrations did not explain the latitudinal differences in immune responses. These results suggest that photoperiod affects reproductive and immune systems differently and that immune responses may reflect other environmental factors.

scholarly journals Reversion of the photoperiod dependence of flowering in rice with synthetic Hd1-microProteins

2018 ◽  
Author(s):  
Tenai Eguen ◽  
Jorge Gomez Ariza ◽  
Kaushal Kumar Bhati ◽  
Bin Sun ◽  
Fabio Fornara ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Heading Date ◽  
Day Length ◽  
Dependent Manner ◽  
Yield Analysis ◽  
Rice Plants ◽  
Short Day ◽  
Long Day ◽  
Long Day Plants

SUMMARYRice (Oryza sativa) is a facultative short-day plant that flowers very late when grown in non-inductive long day conditions. Photoperiod-dependent flowering in rice is regulated by heading date (Hd1) which acts as both an activator and repressor of flowering in a day length-dependent manner. In order to regulate flowering of rice in long days (LD), overexpression of a synthetic Hd1miP, which is capable of interacting with Hd1, was employed. Transgenic Hd1miP rice plants flowered significantly earlier when grown in LD compared to SD, showing that synthetic microProteins can be used to revert short-day plants to long-day plants. Yield analysis revealed that although the OX-Hd1miP grains are comparable to WT in terms of the size of the grains produced, OX-Hd1miP plants like hd1 knockout plants, are compromised in the number of grains produced and the grain maturity rate, suggesting an additional unrecognized role of Hd1 in grain maturity.

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