Effects of 17α-ethynylestradiol in a partial life-cycle test with zebrafish (Danio rerio): effects on growth, gonads and female reproductive success

2003 ◽  
Vol 309 (1-3) ◽  
pp. 127-137 ◽  
Author(s):  
K VANDENBELT ◽  
R VERHEYEN ◽  
H WITTERS
1993 ◽  
Vol 71 (3) ◽  
pp. 469-474 ◽  
Author(s):  
Lisa M. Hiruki ◽  
Ian Stirling ◽  
William G. Gilmartin ◽  
Thea C. Johanos ◽  
Brenda L. Becker

We studied reproductive rate, length of lactation period, pup survival, and mortality of injured and uninjured female Hawaiian monk seals (Monachus schauinslandi) on Laysan Island, northwestern Hawaiian Islands, in 1983 – 1989. The severity and timing of nonfatal injuries were influential in determining their effect on female reproductive success. There was a tendency towards a shorter mean lactation period and lower survival rate of pups for females with major injuries than for uninjured females. Females with minor injuries were similar to uninjured females in terms of reproductive rate, length of lactation, and pup survival. For females injured shortly before the birth of their pup or during lactation, pup survival was lower than for uninjured females, whereas for females injured during the year prior to pupping, measures of reproductive success were not significantly different from those for uninjured females. Immature (aged 4 – 8 years) females entering the reproductive population were injured by adult male seals significantly more often than females aged 0 – 3 years, but at a similar rate to adult females. The major effect of injuries on female reproductive success is an increase in female mortality: 87.5 % of the adult females (n = 16) that died on Laysan Island in 1983 – 1989 sustained injuries from adult male seals.


2004 ◽  
Vol 68 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Markus Diekmann ◽  
Petra Waldmann ◽  
Andreas Schnurstein ◽  
Tamara Grummt ◽  
Thomas Braunbeck ◽  
...  

2016 ◽  
Vol 11 (6) ◽  
pp. 433-446 ◽  
Author(s):  
Dorien DE VRIES ◽  
Andreas KOENIG ◽  
Carola BORRIES

2014 ◽  
Vol 111 (11) ◽  
pp. 1918-1931 ◽  
Author(s):  
Sam Penglase ◽  
Kristin Hamre ◽  
Josef D. Rasinger ◽  
Staale Ellingsen

Se is an essential trace element, and is incorporated into selenoproteins which play important roles in human health. Mammalian selenoprotein-coding genes are often present as paralogues in teleost fish, and it is unclear whether the expression patterns or functions of these fish paralogues reflect their mammalian orthologues. Using the model species zebrafish (Danio rerio; ZF), we aimed to assess how dietary Se affects key parameters in Se metabolism and utilisation including glutathione peroxidase (GPX) activity, the mRNA expression of key Se-dependent proteins (gpx1a, gpx1b, sepp1a and sepp1b), oxidative status, reproductive success and F1 generation locomotor activity. From 27 d until 254 d post-fertilisation, ZF were fed diets with graded levels of Se ranging from deficient ( < 0·10 mg/kg) to toxic (30 mg/kg). The mRNA expression of gpx1a and gpx1b and GPX activity responded in a similar manner to changes in Se status. GPX activity and mRNA levels were lowest when dietary Se levels (0·3 mg/kg) resulted in the maximum growth of ZF, and a proposed bimodal mechanism in response to Se status below and above this dietary Se level was identified. The expression of the sepp1 paralogues differed, with only sepp1a responding to Se status. High dietary Se supplementation (30 mg/kg) decreased reproductive success, while the offspring of ZF fed above 0·3 mg Se/kg diet had lower locomotor activity than the other groups. Overall, the novel finding of low selenoprotein expression and activity coinciding with maximum body growth suggests that even small Se-induced variations in redox status may influence cellular growth rates.


Parasitology ◽  
1983 ◽  
Vol 86 (2) ◽  
pp. 335-344 ◽  
Author(s):  
D. J. Minchella ◽  
P. T. Loverde

SUMMARYA method of interrupting the life-cycle of the human blood fluke Schistosoma by increasing the proportion of genetically insusceptible intermediate host snails in natural populations was first proposed nearly 25 years ago. The method assumes that insusceptible snails will be at a selective advantage over susceptible snails when the schistosome parasite is present, and therefore natural selection will act to increase the proportion of alleles for insusceptibility. A major objection to the proposed technique is ‘If insusceptible snails are at a selective advantage, then why are they not predominant in natural populations that transmit disease?’ One explanation of this paradox is that insusceptibility may be associated with a disadvantageous character or a physiological defect. This study tests this hypothesis by measuring the relative reproductive success of susceptible and insusceptible snails under controlled conditions. Results indicate that insusceptible (unsuitable) snails are negatively affected in the presence of either susceptible snails or schistosome parasites. Furthermore, in the presence of both susceptible snails and schistosome parasites, insusceptible snails are selectively disadvantaged compared to susceptible snails. These results obtained under laboratory-controlled conditions suggest a plausible answer as to why insusceptible snails are not predominant in natural populations that transmit disease.


2015 ◽  
Vol 39 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Edyta Jermakowicz ◽  
Beata Ostrowiecka ◽  
Izabela Tałałaj ◽  
Artur Pliszko ◽  
Agata Kostro-Ambroziak

Abstract In the presented study, male and female reproductive success was analyzed in relation to the population size, floral display and pollinators’ availability in natural and anthropogenic populations of the orchid Malaxis monophyllos (L.) Sw. Our results indicated significant differences between all investigated populations in parameters of floral display, including heights and number of flowers per inflorescence, as well the number of flowering individuals and their spatial structure. Additionally, populations differed both in male (pollinia removal) and female (fruit set) reproductive success, but only the fruit set clearly differentiated anthropogenic and natural populations. Despite the average flower number per plant being significantly higher in two of the anthropogenic populations, it was not related to the fruits set, which was significantly lower there. Moreover, our preliminary study concerning the potential pollinators of M. monophyllos showed a higher contribution of flies in natural habitats than in anthropogenic ones. Thus, we can suspect that the main factors influencing the level of female reproductive success in M. monophyllos populations are abundance of effective pollinators, as well as flower visitors, which may have resulted in a different level of pollen discounting in populations. Therefore, further studies concerning breeding system and pollination as important forces that shape demographic processes in M. monophyllos populations are necessary. Our results also indicate that suitable conservation methods in M. monophyllos should always include the preservation of potential pollinators, especially in these new, secondary habitats.


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