Effects of supplementation with preferred foods on the reproductive axis of American Goldfinches (Spinus tristis)

2012 ◽  
Vol 90 (2) ◽  
pp. 203-209 ◽  
Author(s):  
A.A. Furlonger ◽  
L. Huynh ◽  
T.W. Luloff ◽  
K.L. Schmidt ◽  
S.A. MacDougall-Shackleton
Keyword(s):  
Late Summer ◽  
Field Studies ◽  
Reproductive Physiology ◽  
Food Type ◽  
Laying Date ◽  
Food Supplementation ◽  
Plasma Testosterone ◽  
Reproductive Axis ◽  
Carduelis Tristis ◽  
Fine Tune

Numerous field studies indicate that food supplementation of birds can advance laying date. In addition, laboratory studies, though less common, suggest that altering the amount of food, the predictability of food, or food type can affect reproductive physiology. American Goldfinches ( Spinus tristis , formerly Carduelis tristis (L., 1758)) breed in late summer when thistle (Cynareae) seeds become abundant, suggesting that specific food types may affect their reproductive physiology. We tested whether supplementation with preferred seeds would affect reproductive physiology of male and female American Goldfinches. Birds were photostimulated and fed a standard pellet diet, or supplemented with a variety of preferred seeds. Supplemented females developed larger ovarian follicles. Supplemented males had higher levels of plasma testosterone, but only if they were also housed with a female. These results suggest that preferred seed types can act as a supplementary cue in this species, and fine-tune photoperiod-driven changes in reproductive physiology.

scholarly journals Sexual maturation in Atlantic salmon male parr may be triggered both in early spring and late summer under standard farming conditions

2021 ◽  
Author(s):  
Elia Ciani ◽  
Kristine von Krogh ◽  
Rasoul Nourizadeh-Lillabadi ◽  
Ian Mayer ◽  
Romain Fontaine ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Sexual Maturation ◽  
Late Summer ◽  
Early Spring ◽  
Plasma Testosterone ◽  
Farmed Salmon ◽  
Early Maturing ◽  
Advanced Stages ◽  
One Year ◽  
Immature Fish

AbstractMale Atlantic salmon (Salmo salar) display different sexual strategies, maturing either as parr during the freshwater phase (as sneaky spawners), or as post smolts following one or several years at sea. First sexual maturation (puberty) occurs at different times depending on environmental and genetic factors. To improve our knowledge on the timing (age and season) of first sexual maturation in Atlantic salmon male parr, we investigated pubertal activation in second generation farmed salmon from the Norwegian river Figgjo, reared under natural conditions of photoperiod and water temperature. Histological analysis, in combination with morphometric measurements, plasma androgen levels and pituitary gonadotropin gene expression analysis revealed that, as previously reported, some male parr initiated early sexual maturation in spring at one year of age. Interestingly, some male parr were observed to initiate sexual maturation already in autumn, six months after hatching (under-yearlings), much earlier than reported in previous studies. One-year old maturing males showed a low induction in gonadotropin levels, while under-yearling maturing males displayed a significant increase in fshb transcripts as compared to immature fish. Plasma testosterone, detectable also in immature males, increased constantly during testes development, while 11-ketotestosterone, undetectable in immature and early maturing males, increased during more advanced stages of maturation. A mild feminization of the testes (ovotestes) was detected in a subset of samples. This study brings new knowledge on the little investigated field of sexually maturing under-yearlings in Atlantic salmon. This is also the first study comparing the physiology of under-yearling vs one-year old maturing male parr, thus bringing new insights to the remarkable plasticity of Atlantic salmon puberty.

Simulation of the Cooking Organic Aerosol Concentration Variability in an Urban Area

2021 ◽  
Author(s):  
Evangelia Siouti ◽  
Ksakousti Skyllakou ◽  
Ioannis Kioutsioukis ◽  
Giancarlo Ciarelli ◽  
Spyros N. Pandis
Keyword(s):  
Urban Area ◽  
Urban Areas ◽  
Temporal Distribution ◽  
Late Summer ◽  
Field Studies ◽  
Organic Aerosol ◽  
Basis Set ◽  
Cooking Times ◽  
The City ◽  
Lunch Time

<p>Cooking operations can be an important fine PM source for urban areas. Cooking emissions are a source of pollution that has been often ignored and are not included or are seriously underestimated in urban emission inventories. However, several field studies in cities all over Europe suggest that cooking organic aerosol (COA) can be an important component of the total organic PM. In this study we propose and evaluate a methodology for the simulation of the COA concentration and its variability in space and time in an urban area. The city of Patras, the third biggest in Greece is used for this first application for a typical late summer period. The spatial distribution of COA emissions is based on the exact location of restaurants and grills, while the emissions on the meat consumption in Greece. We estimated COA emissions of 150 kg d<sup>-1</sup> that corresponds to 0.6 g d<sup>-1</sup> per person. The temporal distribution of COA was based on the known cooking times and the results of the past field studies in the area. Half of the daily COA is emitted during dinner time (21:00-0:00 LT), while approximately 25% during lunch time (13:00-16:00 LT). The COA is simulated using the Volatility Basis Set with a volatility distribution measured in the laboratory and is treated as semivolatile and reactive. The maximum average COA concentration during the simulation period is predicted to be 1.3 μg m<sup>-3</sup> in a mainly pedestrian area with a high density of restaurants. Peak hourly COA concentrations in this area exceed 10 μg m<sup>-3</sup> during several nights. The local production of secondary COA is predicted to be slow and it represents just a few percent of the total COA.</p><p> </p>

Use of Quinclorac Plus 2,4-D for Controlling Field Bindweed (Convolvulus arvensis) in Fallow

1999 ◽  
Vol 13 (4) ◽  
pp. 731-736 ◽  
Author(s):  
Stephen F. Enloe ◽  
Philip Westra ◽  
Scott J. Nissen ◽  
Stephen D. Miller ◽  
Phillip W. Stahlman
Keyword(s):  
Triticum Aestivum ◽  
Visual Field ◽  
Count Data ◽  
Late Summer ◽  
Field Studies ◽  
Strong Correlations ◽  
Convolvulus Arvensis ◽  
Fallow Period ◽  
Field Bindweed ◽  
Better Than

Field studies were conducted in Colorado, Kansas, and Wyoming to compare the use of quinclorac plus 2,4-D with picloram plus 2,4-D, dicamba plus 2,4-D, a glyphosate plus 2,4-D premix, and 2,4-D alone for control of field bindweed (Convolvulus arvensis) in a winter wheat (Triticum aestivum)-fallow rotation. Treatments were applied in late summer or fall each year for two, three, or four consecutive years at the beginning and end of each fallow period. Evaluations were taken 10 to 12 mo after treatment each year. Quinclorac plus 2,4-D and picloram plus 2,4-D consistently performed as well as or better than 2,4-D, dicamba plus 2,4-D, and glyphosate plus 2,4-D. Wheat yields increased when field bindweed was controlled during the fallow period. Strong correlations (r> −0.85) were obtained among visual field bindweed evaluation, biomass, and stand count data.

scholarly journals Factors affecting individual variation in nest-defense intensity in colonially breeding Black-tailed Gulls (Larus crassirostris)

2011 ◽  
Vol 89 (10) ◽  
pp. 938-944 ◽  
Author(s):  
Kentaro Kazama ◽  
Yasuaki Niizuma ◽  
Kentaro Q. Sakamoto ◽  
Yutaka Watanuki
Keyword(s):  
Individual Variation ◽  
Physiological State ◽  
Breeding Birds ◽  
Egg Laying ◽  
Nest Defense ◽  
Laying Date ◽  
Plasma Testosterone ◽  
Factors Affecting ◽  
Corvus Macrorhynchos ◽  
Males And Females

The physiological state of parent birds combined with the value of their clutch may affect the intensity of their nest defense. In colonially breeding birds, nest-defense intensity may also be affected by the behavior of neighbors. We investigated individual variation in the nest-defense intensity among colonial Black-tailed Gulls ( Larus crassirostris Vieillot, 1818) over 2 years. Only 30%–40% of males attacked a decoy of an egg predator (Large-billed Crow ( Corvus macrorhynchos Wagler, 1827)), and the other males and females rarely attacked. Males attacking the decoy had higher levels of plasma testosterone than males that did not attack. Each male’s, but not female’s, nest-defense intensity was consistent throughout the incubation period and also across years. The intensity was not related to egg-laying date, clutch size, or age of offspring. The intensity was likely to be higher when individuals had one or more neighbors, representing higher nest-defense intensity in the year where gulls had larger number of adjacent neighboring nests (5.23 nests), but this trend was not observed in the year where they had smaller number of the neighboring nests (3.73 nests). Thus, in addition to testosterone levels, behavior of neighbors also influences the nest-defense intensity.

Molecular integration of hypothalamo-pituitary-adrenal axis-related neurohormones on the GnRH neuron

2000 ◽  
Vol 78 (3) ◽  
pp. 205-216 ◽  
Author(s):  
David J Tellam ◽  
Yasmin N Mohammad ◽  
David A Lovejoy
Keyword(s):  
Hpa Axis ◽  
Prolactin Receptor ◽  
Gonadotropin Releasing Hormone ◽  
Reproductive Physiology ◽  
Corticotropin Releasing Factor ◽  
Gnrh Neuron ◽  
Reproductive Axis ◽  
Pituitary Adrenal Axis ◽  
Periods Of Stress

Gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus is pivotal to the regulation of reproductive physiology in vertebrates. GnRH and the reproductive axis, in general, can be inhibited during periods of stress or injury. Stress, in the form of mechanical, psychological or immunological insult to an organism results in the activation of the hypothalamo-pituitary-adrenal (HPA) axis initiated by the hypothalamic release of corticotropin-releasing factor (CRF). Recent studies indicate that CRF may act either directly on the GnRH neuron to down-regulate GnRH synthesis, or indirectly via a β-endorphin-mediated pathway. Moreover, in vitro studies suggest that CRF-related peptides can increase the sensitivity of the GnRH neuron to prolactin by increasing the synthesis of the prolactin receptor.

Variation in laying date, clutch size, egg size, and egg composition of yellow-headed blackbirds (Xanthocephalus xanthocephalus): a supplemental feeding experiment

1992 ◽  
Vol 70 (10) ◽  
pp. 1904-1911 ◽  
Author(s):  
Todd W. Arnold
Keyword(s):  
Food Availability ◽  
Egg Production ◽  
Egg Size ◽  
Energy Content ◽  
Laying Date ◽  
Food Supplementation ◽  
Supplemental Feeding ◽  
Xanthocephalus Xanthocephalus ◽  
Egg Composition ◽  
Nest Initiation

I studied the effects of food availability, habitat quality, and timing of breeding on egg production in yellow-headed blackbirds (Xanthocephalus xanthocephalus). Food availability was experimentally manipulated by providing females on six wetlands with supplemental food; six additional wetlands served as unsupplemented controls. Mean nest initiation dates varied by up to 6 d among wetlands, and supplementally fed blackbirds initiated nests 2 d earlier than controls, on average (although this latter difference was not quite significant; P = 0.07). Clutch size declined with laying date, but was unaffected by wetland location, food supplementation, or interactions between these two factors and laying date. Although egg size did not vary among wetlands or in relation to supplemental feeding, egg composition varied with both of these factors. All egg components except wet and dry shell and dry albumen varied among wetlands, whereas total water, wet yolk, and lean yolk were the only components that varied with food supplementation. Large blackbird eggs contained proportionately more water and albumen, but proportionately less yolk and shell. These patterns were somewhat compensatory, such that proportional protein and energy content did not vary with egg size; however, large eggs contained proportionately less fat than did small eggs. Proportional egg composition varied among wetlands (yolk and energy content), but was not affected by supplemental feeding. In general, egg production by yellow-headed blackbirds was not greatly affected by food availability. This may have been due to any of the following four factors: (1) inaccessibility of food supplements owing to competition between male and female blackbirds, (2) insufficient time for females to respond to food supplements, owing to rapid settlement and nest initiation, (3) a nutritionally inappropriate food supplement (i.e., protein availability may not have been enhanced among fed birds), or (4) superabundance of natural foods such that food availability was not limiting egg production.

Food shortage for breeding Black-billed Magpies (Pica pica): an experiment using supplemental food

1987 ◽  
Vol 65 (5) ◽  
pp. 1270-1274 ◽  
Author(s):  
Wesley M. Hochachka ◽  
David A. Boag
Keyword(s):  
Breeding Population ◽  
Egg Laying ◽  
Food Shortage ◽  
Laying Date ◽  
Food Supplementation ◽  
Natural Food ◽  
Supplemental Feeding ◽  
Pica Pica ◽  
Supplemental Food ◽  
Before And After

Supplemental food was provided to a breeding population of Black-billed Magpies (Pica pica), starting before and after eggs were laid, to determine if and when natural food was limited. The production of fledgling magpies was increased only when supplemental feeding was begun before laying. Laying date was also advanced when supplemental feeding began before laying, but clutch and egg size were not significantly changed. Because the two feeding treatments were conducted in different years, we cannot conclude whether natural food was limiting before or after egg laying. However, out data suggest that the former may have been the case. An improved design for food supplementation experiments, which can be used to determine the time of food shortage, is suggested.

Dissolved oxygen dynamics in the Mid‐Passaic River: Late summer/early fall 1983–4 field studies

1988 ◽  
Vol 23 (6) ◽  
pp. 525-542 ◽  
Author(s):  
Christopher G. Uchrin ◽  
William K. Ahlert ◽  
Arthur P. Cryan ◽  
Janis V. Giga ◽  
Shing‐Fu Hsueh ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Late Summer ◽  
Field Studies ◽  
Passaic River ◽  
Early Fall ◽  
Oxygen Dynamics

scholarly journals Estradiol modulates Kiss1 neuronal response to ghrelin

2014 ◽  
Vol 306 (6) ◽  
pp. E606-E614 ◽  
Author(s):  
Renata Frazao ◽  
Heather M. Dungan Lemko ◽  
Regina P. da Silva ◽  
Dhirender V. Ratra ◽  
Charlotte E. Lee ◽  
...  
Keyword(s):  
Energy Homeostasis ◽  
Neuronal Response ◽  
Estrogen Receptor Α ◽  
Negative Energy ◽  
Reproductive Physiology ◽  
Gonadotropin Secretion ◽  
Ghrelin Receptor ◽  
Reproductive Axis ◽  
Metabolic Signal ◽  
Hypothalamic Level

Ghrelin is a metabolic signal regulating energy homeostasis. Circulating ghrelin levels rise during starvation and fall after a meal, and therefore, ghrelin may function as a signal of negative energy balance. Ghrelin may also act as a modulator of reproductive physiology, as acute ghrelin administration suppresses gonadotropin secretion and inhibits the neuroendocrine reproductive axis. Interestingly, ghrelin's effect in female metabolism varies according to the estrogen milieu predicting an interaction between ghrelin and estrogens, likely at the hypothalamic level. Here, we show that ghrelin receptor (GHSR) and estrogen receptor-α (ERα) are coexpressed in several hypothalamic sites. Higher levels of circulating estradiol increased the expression of GHSR mRNA and the co-xpression of GHSR mRNA and ERα selectively in the arcuate nucleus (ARC). Subsets of preoptic and ARC Kiss1 neurons coexpressed GHSR. Increased colocalization was observed in ARC Kiss1 neurons of ovariectomized estradiol-treated (OVX + E2; 80%) compared with ovariectomized oil-treated (OVX; 25%) mice. Acute actions of ghrelin on ARC Kiss1 neurons were also modulated by estradiol; 75 and 22% of Kiss1 neurons of OVX + E2 and OVX mice, respectively, depolarized in response to ghrelin. Our findings indicate that ghrelin and estradiol may interact in several hypothalamic sites. In the ARC, high levels of E2 increase GHSR mRNA expression, modifying the colocalization rate with ERα and Kiss1 and the proportion of Kiss1 neurons acutely responding to ghrelin. Our findings indicate that E2 alters the responsiveness of kisspeptin neurons to metabolic signals, potentially acting as a critical player in the metabolic control of the reproductive physiology.

A two-level unreplicated factorial experiment to determine the effect of organic and inorganic fertilizers on dry matter yield of permanent pasture

2006 ◽  
Vol 21 (2) ◽  
pp. 106-113 ◽  
Author(s):  
T. Astatkie ◽  
A.A. Joseph ◽  
R.C. Martin
Keyword(s):  
Dry Matter ◽  
Dairy Farm ◽  
Late Summer ◽  
Field Studies ◽  
Forage Yield ◽  
Seaweed Extract ◽  
Dry Matter Yield ◽  
Agricultural Field ◽  
Pasture Management ◽  
Permanent Pasture

In organic pasture systems, the balance of soil fertility is maintained by maximizing the cycling of on-farm nutrients. In this study, the effect of fertility management on dry matter yield in organic pasture systems was examined using an unreplicated 25 factorial design. The factors were nitrogen (N), phosphorus (P), potassium (K), compost and seaweed extract, each at two levels (with [+] and without [−]). The trials were conducted in 2000 and 2001 at two fields on an organic dairy farm in Nova Scotia, Canada. The pasture mix is predominantly perennial ryegrass, orchardgrass and white clover. The fertility treatments were applied in spring, and forage yield was collected from early-, mid- and late-summer harvests. The analysis revealed the significance of several interaction effects, which varied considerably from harvest to harvest. Both +N and +Compost treatments were associated with increased yield. High levels of P and K already present in the soil either diminished or varied the effects of P and K treatments. Seaweed extract enhanced the effectiveness of N and compost, but reduced yield when used alone. The results suggest that the commonly recommended use of seaweed extract for organic pasture management can be detrimental to biomass production unless sufficient nitrogen is provided. Despite the unusually dry weather in the 2 years, the study demonstrated the applicability of unreplicated two-level factorial experiments in agricultural field studies.

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