scholarly journals Intermediate-duration day lengths unmask reproductive responses to nonphotic environmental cues

2009 ◽  
Vol 296 (5) ◽  
pp. R1613-R1619 ◽  
Author(s):  
Matthew J. Paul ◽  
Jerome Galang ◽  
William J. Schwartz ◽  
Brian J. Prendergast
Keyword(s):  
Pubertal Development ◽  
Late Summer ◽  
Early Spring ◽  
Day Length ◽  
Environmental Cues ◽  
Local Conditions ◽  
Siberian Hamsters ◽  
Reproductive Axis ◽  
And Behavior

Many animals time their breeding to the seasons, using the changing day length to forecast those months when environmental conditions favor reproductive success; in Siberian hamsters ( Phodopus sungorus), long summer days stimulate, whereas short winter days inhibit, reproductive physiology and behavior. Nonphotic environmental cues are also thought to influence the timing of breeding, but typically their effects on reproduction are minor and more variable under categorically long and short photoperiods. We hypothesized that the influence of nonphotic cues might be more prominent during intermediate photoperiods (early spring and late summer), when day length is an unreliable predictor of year-to-year fluctuations in food availability. In hamsters housed in an intermediate photoperiod (13.5 h light/day), two nonphotic seasonal cues, mild food restriction and same-sex social housing, induced gonadal regression, amplified photoperiod history-dependent reproductive responses to decreasing day lengths, and prevented pubertal development indefinitely. These cues were entirely without effect in hamsters maintained under a long photoperiod (16 h light/day). Thus intermediate photoperiods reveal a heightened responsiveness of the reproductive axis to nonphotic cues. This photoperiod-dependent efficacy of nonphotic cues may explain how animals integrate long-term photic and short-term nonphotic cues in nature: intermediate day lengths open a seasonal window of increased reproductive responsiveness to nonphotic cues at a time when such cues may be of singular relevance, thereby allowing for precise synchronization of the onset and offset of the breeding season to local conditions.

A plastic interval timer synchronizes pubertal development of summer- and fall-born hamsters

2001 ◽  
Vol 281 (5) ◽  
pp. R1613-R1623 ◽  
Author(s):  
Michael R. Gorman
Keyword(s):  
Pubertal Development ◽  
Late Summer ◽  
Day Length ◽  
Late Winter ◽  
Developmental Patterns ◽  
Somatic Development ◽  
Siberian Hamsters ◽  
Interval Timer ◽  
Early Fall ◽  
Time Of Year

Summer and fall decreases in day length induce reproductive regression in adult hamsters and delay reproductive maturation of their young. The following year pubertal development is triggered by an interval timer (IT) that renders animals refractory to inhibitory short day lengths after ∼25 wk. Timing of gonadal and somatic development was examined among offspring born to Siberian hamsters in early-August vs. late-September day lengths. Pubertal maturation was delayed in both groups until late winter. Gonadal growth occurred at significantly later ages among August- vs. September-born males as did late-winter spurts in ponderal growth of both sexes. Timing of reproductive and somatic development depended on postnatal rather than prenatal photoperiod exposure and was unrelated to the circadian entrainment status of dams. When developmental patterns were assessed in relation to time of year, group differences were largely eliminated. Because the IT triggers these developmental events, its duration must be plastic. This plasticity facilitates a relative synchronization or entrainment of developmental milestones in hamsters born into different late-summer/early-fall photoperiods.

scholarly journals MT1 Melatonin Receptors Mediate Somatic, Behavioral, and Reproductive Neuroendocrine Responses to Photoperiod and Melatonin in Siberian Hamsters (Phodopus sungorus)

Endocrinology ◽  
2010 ◽  
Vol 151 (2) ◽  
pp. 714-721 ◽  
Author(s):  
Brian J. Prendergast
Keyword(s):  
Reproductive Function ◽  
Melatonin Receptors ◽  
Day Length ◽  
Phodopus Sungorus ◽  
Receptor Subtypes ◽  
Gonadotropin Secretion ◽  
Siberian Hamsters ◽  
The Central Nervous System ◽  
Necessary And Sufficient ◽  
And Behavior

Environmental day length drives nocturnal pineal melatonin secretion, which in turn generates or entrains seasonal cycles of physiology, reproduction, and behavior. In mammals, melatonin (MEL) binds to a number of receptor subtypes including high-affinity (MT1 and MT2) and low-affinity (MT3, nuclear orphan receptors) binding sites, which are distributed throughout the central nervous system and periphery. The MEL receptors that mediate photoperiodic reproductive and behavioral responses to MEL have not been identified in a reproductively photoperiodic species. Here I tested the hypothesis that MT1 receptors are necessary and sufficient to engage photoperiodic responses by challenging male Siberian hamsters (Phodopus sungorus), a species that does not express functional MT2 receptors, with ramelteon (RAM), a specific MT1/MT2 receptor agonist. In hamsters housed in a long-day photoperiod, late-afternoon RAM treatment inhibited gonadotropin secretion, induced gonadal regression, and suppressed food intake and body mass, mimicking effects of MEL. In addition, chronic (24 h/d) RAM infusions were sufficient to obscure endogenous MEL signaling, and these treatments attenuated gonadal regression in short days. Together, the outcomes indicate that signaling at the MT1 receptor is sufficient and necessary to mediate the effects of photoperiod-driven changes in MEL on behavior and reproductive function in a reproductively photoperiodic mammal.

The biology of Harveyella mirabilis (Cryptonemiales, Rhodophyceae). IV. Life history and phenology

1976 ◽  
Vol 54 (3-4) ◽  
pp. 281-292 ◽  
Author(s):  
Lynda J. Goff ◽  
Kathleen Cole
Keyword(s):  
Water Temperature ◽  
Seawater Temperature ◽  
Environmental Parameters ◽  
Late Summer ◽  
Early Spring ◽  
Day Length ◽  
Late Winter ◽  
Temperature Sensitive ◽  
The North ◽  
The North Pacific

A 20-month field study of the reproductive biology of the parasitic red alga Harveyella mirabilis was undertaken to investigate the effects of environmental parameters on the reproductive periodicity of Harveyella in the intertidal habitat. In the northeast Pacific, tetraspores have been observed in the late winter - early spring; apparently they are produced in response to increased available sunlight and water temperature. Gametogenesis appears to be temperature sensitive; it occurs between a narrow temperature range (9–11 °C). Carpospores are produced in the late summer when both water temperature and day length reach a peak. The phenology of H. mirabilis in the North Atlantic differs from that which is observed in the North Pacific in the timing of gametogenesis and carposporogenesis. The significance of this is discussed in relation to the possible effects of differences in seawater temperature on gametogenesis.

scholarly journals Photoperiod and its relationship to sheep reproduction

2021 ◽  
Author(s):  
Anayansi Ivette Ramírez Ramírez ◽  
Tania Arellano Lezama ◽  
Zadi Méndez Roblero1 ◽  
Guadalupe Idilia Delgado Tiburcio ◽  
Jaime Gallegos-Sánchez
Keyword(s):  
Animal Species ◽  
Reproductive Activity ◽  
Early Spring ◽  
Climatic Conditions ◽  
Day Length ◽  
Late Winter ◽  
Environmental Cues ◽  
Factors Affecting ◽  
Common Process ◽  
Almost Continuous

Objective: To describe the seasonal variations throughout the year (day length), as one of the main environmental cues used by ewes to determine the most favorable time for breeding. Design/methodology/approach: A description of the main factors affecting ewe reproduction (photoperiod, suckling, postpartum period, nutrition, sociosexual effects) was assessed by a review of documentary information. Results: The inhibition of reproductive activity during one time of the year is a common process in most animal species to prevent births from occurring at an unfavorable time for the survival of the offspring. The seasonality of reproduction (northern latitude) allows births to occur in late winter or early spring when climatic conditions are the most favorable for the offspring development. Limitations/implications: The duration of the anestrus season (seasonal or postpartum) is influenced by the photoperiod and other factors. In Mexico, a small percentage of Criollo and Pelibuey ewes show a short duration of seasonal anestrus; that is, they show almost continuous annual reproductive activity. Therefore, to improve the reproductive efficiency of ewes, it is important to precisely determine the factors that affect their reproduction to improve management and increase the profits in the production units. Findings/Conclusions: Photoperiod is the main environmental factor regulating the annual reproductive cycle of the ewes, it occurs through very complex and varied mechanisms that communicate the visual system with the gonads through nervous and endocrine pathways.

scholarly journals Peripheral kisspeptin reverses short photoperiod-induced gonadal regression in Syrian hamsters by promoting GNRH release

Reproduction ◽  
2011 ◽  
Vol 142 (3) ◽  
pp. 417-425 ◽  
Author(s):  
L Ansel ◽  
A H Bentsen ◽  
C Ancel ◽  
M Bolborea ◽  
P Klosen ◽  
...  
Keyword(s):  
Marked Reduction ◽  
Day Length ◽  
Strong Increase ◽  
Pituitary Cells ◽  
Reproductive Axis ◽  
Gonadal Atrophy ◽  
Gnrh Neurons ◽  
Gonadotropic Axis ◽  
Gnrh Release

In seasonal breeders, reproduction is synchronised by day length via the pineal hormone melatonin. In short winter days (short day, SD), the Syrian hamster displays a complete gonadal atrophy together with a marked reduction in expression of kisspeptins (Kp), a family of potent hypothalamic stimulators of GNRH neurons. Both central and peripheral acute injections of Kp have been reported to activate the gonadotropic axis in mammals. The aim of this study was to determine if and how peripheral administration of Kp54 could restore gonadal function in photo-inhibited hamsters. Testicular activity of hamsters kept in SD was reactivated by two daily i.p. injections of Kp54 but not by chronic subcutaneous delivery of the same peptide via mini-pumps. Acute i.p. injection of Kp54-induced FOS (c-Fos) expression in a large number of GNRH neurons and pituitary gonadotrophs together with a strong increase in circulating testosterone. The activation of pituitary cells by Kp was inhibited by preadministration of the GNRH receptor antagonist acyline. Altogether, our results demonstrate that peripheral Kp54 activates the gonadotropic axis by stimulating GNRH release and indicate that an appropriate protocol of long-term systemic Kp administration can recrudesce a photo-inhibited reproductive axis.

scholarly journals Time budgets of Tibetan eared pheasants during the non-breeding season in an alpine scrub habitat

2009 ◽  
Vol 55 (3) ◽  
pp. 193-199
Author(s):  
Xin Lu ◽  
Guangmei Zheng
Keyword(s):  
Food Supply ◽  
Group Living ◽  
Early Spring ◽  
Day Length ◽  
Term Survival ◽  
Extra Food ◽  
Energetic Constraint ◽  
Breeding Seasons ◽  
Full Day

Abstract Time allocations of the group-living Tibetan eared pheasants Crossoptilon harmani with and without supplementary food were investigated by full-day sampling from winter through spring in an alpine scrub zone, south Tibet. At a flock scale, both the different food-supply flocks displayed similar daily patterns of activity, foraging in the morning and evening, and resting around midday. In terms of individual activity, either foraging or resting was highly synchronous with the flock’s. Non-provisioned birds spent more time feeding and less resting in midwinter than in late autumn. In early spring as climates became warmer and day longer, however, non-provisioned birds did not decrease their feeding efforts significantly but the provisioned birds did. Across the non-breeding seasons, the provisioned birds (relying on nutrition-rich artificial food) devoted less time to feeding and more to resting than did the non-provisioned ones (relying on nutrition-poor plant roots). Multivariate analysis showed increased food supply and ambient temperature resulted in a reduced foraging effort. However, the fact that the non-provisioned birds can save daily time for resting even in the cold short-day length mid-winter indicated that they faced no energetic constraint. Thus, protecting shelter vegetation rather than providing extra food is suggested to be important for long-term survival of the endangered galliform birds.

scholarly journals A partial migrant relies upon a range-wide cue set but uses population-specific weighting for migratory timing

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Nils Linek ◽  
Paweł Brzęk ◽  
Phillip Gienapp ◽  
M. Teague O’Mara ◽  
Ivan Pokrovsky ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Day Length ◽  
Environmental Cues ◽  
Local Conditions ◽  
Ambient Temperatures ◽  
Partial Migrant ◽  
Migratory Timing ◽  
Migratory Strategies ◽  
Departure Decisions ◽  
High Atmospheric Pressure

Abstract Background Many birds species range over vast geographic regions and migrate seasonally between their breeding and overwintering sites. Deciding when to depart for migration is one of the most consequential life-history decisions an individual may make. However, it is still not fully understood which environmental cues are used to time the onset of migration and to what extent their relative importance differs across a range of migratory strategies. We focus on departure decisions of a songbird, the Eurasian blackbird Turdus merula, in which selected Russian and Polish populations are full migrants which travel relatively long-distances, whereas Finnish and German populations exhibit partial migration with shorter migration distances. Methods We used telemetry data from the four populations (610 individuals) to determine which environmental cues individuals from each population use to initiate their autumn migration. Results When departing, individuals in all populations selected nights with high atmospheric pressure and minimal cloud cover. Fully migratory populations departed earlier in autumn, at longer day length, at higher ambient temperatures, and during nights with higher relative atmospheric pressure and more supportive winds than partial migrants; however, they did not depart in higher synchrony. Thus, while all studied populations used the same environmental cues, they used population-specific and locally tuned thresholds to determine the day of departure. Conclusions Our data support the idea that migratory timing is controlled by general, species-wide mechanisms, but fine-tuned thresholds in response to local conditions.

The effect of the day length on the formation of apical buds in one-year-old containerized seedlings of Scots pine and Norway spruce

2016 ◽  
Author(s):  
А.Н. Федотов ◽  
А.В. Жигунов
Keyword(s):  
Late Summer ◽  
Vegetation Period ◽  
Early Spring ◽  
Day Length ◽  
Practical Significance ◽  
Bud Formation ◽  
Temperature Conditions ◽  
Apical Bud ◽  
Apical Buds ◽  
Containerized Seedlings

При выращивании контейнеризированных сеянцев сосны и ели широко используются многоротационные схемы выращивания. Посев семян производится как ранней весной, так и поздним летом. В связи с этим возникает вопрос устойчивости сеянцев к неблагоприятным факторам среды в условиях зимнего хранения посадочного материала. Цель исследования – изучение особенностей формирования верхушечной почки у сеянцев сосны и ели при летних и позднелетних сроках посева с 18 апреля до 21 сентября. Проводили наблюдение за температурным режимом, сроками формирования верхушечных почек, определяли биометрические параметры и массу сеянцев. Температурный режим в теплице до середины сентября был стабилен и не мог повлиять на морфогенез сеянцев сосны и ели при различных сроках посева. Закладка почки у сеянцев сосны и ели I ротации при посеве в апреле происходит в конце июля при наступлении критической длины дня (15 ч). В посевах II ротации в июне закладка почки сдвигается на более поздние сроки. В посевах III ротации в начале августа у сеянцев ели почка начинает формироваться только в конце сентября, у сеянцев сосны не отмечается закладка почек, хотя рост сеянцев проходил при уменьшении длины дня от критической 15 ч до 10 ч. В посевах в сентябре у сеянцев сосны и ели не наблюдается формирование почек даже в конце октября, когда длина дня составляет менее 10 ч. Контейнеризированные сеянцы сосны и ели при выращивании в режиме I ротации достигают стандартных параметров к концу вегетационного периода и имеют хорошо сформированную верхушечную почку. Сеянцы II ротации необходимо доращивать на открытом полигоне во втором вегетационном сезоне. Сеянцы III ротации не достигнут требуемых стандартом параметров без изменения технологии выращивания. The multi-rotation growth scheme is widely used for growing containerized seedlings of pine and spruce. Sowing is performed both in early spring and late summer. In this connection, resistance of seedlings to adverse environmental factors during winter storage of planting material becomes of practical significance. The purpose of the research is to study the features of apical bud formation in pine and spruce seedlings sown in summer and late-summer periods from April 18 to September 21. With this object in view, observations on temperature conditions and the periods of apical bud formation were made and biometric parameters and mass of seedlings were determined. Temperature conditions in the greenhouse until mid-September were stable; they did not affect the morphogenesis of pine and spruce seedlings sown in different periods. Buds of pine and spruce seedlings of the 1st rotation sown in April are formed in late July at the critical day length (15 hours). In seedlings of the 2nd rotation sown in June, bud formation starts later. In spruce seedlings of the 3rd rotation sown in early August, bud formation starts only at the end of September, whereas pine seedlings do not form buds, though the growth of the seedlings took place when the length of the day was reducing from the critical 15 hours to 10 hours. Pine and spruce seedlings sown in September did not form buds even at the end of October, when the day length was no less than 10 hours. Containerized pine and spruce seedlings of the 1st rotation reach standard parameters by the end of the vegetation period and they have eumorphic apical buds. Seedlings of the 2nd rotation need to be kept in an outdoor field for further growth in the second vegetation season. Seedlings of the 3rd rotation cannot reach the required standards unless the cultivation technology is changed.

Isolation of Stenotrophomonas maltophilia from Clinical Samples in Some Hospitals in Shiraz, Iran

2020 ◽  
pp. 1-3
Author(s):  
Majid Baserisalehi ◽  
Samira Zarezadeh ◽  
Majid Baserisalehi ◽  
Saeed Shoa
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Enterobacter Aerogenes ◽  
Late Summer ◽  
Early Spring ◽  
Clinical Samples ◽  
Bacillus Species ◽  
Microbiological Analysis ◽  
Blood Samples ◽  
Healthcare Facilities ◽  
Phenotypic Methods

Stenotrophomonas maltophilia is an emerging pathogenic non-fermentative Gram-negative Bacillus species. It has caused many nosocomial infections and can be isolated from various hospital wards and healthcare facilities. Research has shown that most of its strains are inherently resistant to many antibiotics and have multidrug resistance. This research intended to determine its occurrence frequency at some Hospitals in shiraz, Iran. The present study was conducted in six months (from early spring to late summer 2019). Clinical samples (Blood, Urine and cerebrospinal fluid (CSF)) collected from 120 patients afflicted with various infections. The samples were transferred to the Laboratory and subjected to microbiological analysis. Identification of the isolates was carried out by phenotypic methods and Stenotrophomonas maltophilia isolates verified using molecular methods. In total, various bacteria were isolated from 84 clinical samples. The isolates were Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Stenotrophomonas maltophilia, Staphylococcus aureus and Pseudomonas aeruginosa. Stenotrophomonas maltophilia was isolated from 17 (20.2%) positive samples and most of them were isolated from blood samples. Our finding indicated that Stenotrophomonas maltophilia isolated more from blood samples follow by CSF sample. In addition, our finding illustrated that Stenotrophomonas maltophilia can be considered as the common nosocomial agent at hospitals in Shiraz, Iran.

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