Variability in egg and jelly-coat size and their contribution to target size for spermatozoa: a review for the Echinodermata

2019 ◽  
Vol 70 (7) ◽  
pp. 995 ◽  
Author(s):  
Dione J. Deaker ◽  
Shawna A. Foo ◽  
Maria Byrne

Fertilisation and development in broadcast-spawning marine invertebrates depends on the ability of the egg to attract spermatozoa and provision progeny. Echinoderm eggs have a jelly coat that facilitates sperm–egg collisions. We investigated variation in egg volume and target area for spermatozoa provided by the jelly coat within and between three sea urchin species (Heliocidaris erythrogramma, Heliocidaris tuberculata, Centrostephanus rodgersii), as well as across 22 echinoderm species for which data are available. Egg and jelly-coat size varied within spawns of individual females, between females of a species and between species. The jelly coat increased egg target area by 125–489% for echinoids with planktotrophic development. In general, planktotrophic echinoids (n=16) with larger eggs had thicker jelly coats, as did H. tuberculata females with larger eggs. Variability in egg and jelly-coat size within a species indicates that these traits are prone to maternal effects and may be influenced by factors such as sperm environment and offspring fitness that drive selection on egg investment. The greater variability in jelly-coat size compared with that of the egg has a large potential to affect fertilisation and should be considered in models of fertilisation kinetics. Egg size alone cannot be used as a metric to infer target size for spermatozoa.

2020 ◽  
Vol 8 (9) ◽  
pp. 661
Author(s):  
Davide Asnicar ◽  
Costanza Cappelli ◽  
Ahmad Safuan Sallehuddin ◽  
Nur Atiqah Maznan ◽  
Maria Gabriella Marin

Despite the widespread use of herbicide glyphosate in cultivation, its extensive runoff into rivers and to coastal areas, and the persistence of this chemical and its main degradation product (aminomethylphosphonic acid, AMPA) in the environment, there is still little information on the potential negative effects of glyphosate, its commercial formulation Roundup® and AMPA on marine species. This study was conducted with the aim of providing a comparative evaluation of the effects of glyphosate-based and its derived chemicals on the larval development of the sea urchin Paracentrotus lividus, thus providing new data to describe the potential ecotoxicity of these contaminants. In particular, the effects on larval development, growth and metabolism were assessed during 48 h of exposure from the time of egg fertilization. The results confirm that AMPA and its parent compound, glyphosate have similar toxicity, as observed in other marine invertebrates. However, interestingly, the Roundup® formulation seemed to be less toxic than the glyphosate alone.


1994 ◽  
Vol 269 (36) ◽  
pp. 22712-22718 ◽  
Author(s):  
S. Kitazume ◽  
K. Kitajima ◽  
S. Inoue ◽  
F.A. Troy ◽  
J.W. Cho ◽  
...  

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Lucia Mentesana ◽  
Martin N. Andersson ◽  
Stefania Casagrande ◽  
Wolfgang Goymann ◽  
Caroline Isaksson ◽  
...  

Abstract Background In egg-laying animals, mothers can influence the developmental environment and thus the phenotype of their offspring by secreting various substances into the egg yolk. In birds, recent studies have demonstrated that different yolk substances can interactively affect offspring phenotype, but the implications of such effects for offspring fitness and phenotype in natural populations have remained unclear. We measured natural variation in the content of 31 yolk components known to shape offspring phenotypes including steroid hormones, antioxidants and fatty acids in eggs of free-living great tits (Parus major) during two breeding seasons. We tested for relationships between yolk component groupings and offspring fitness and phenotypes. Results Variation in hatchling and fledgling numbers was primarily explained by yolk fatty acids (including saturated, mono- and polyunsaturated fatty acids) - but not by androgen hormones and carotenoids, components previously considered to be major determinants of offspring phenotype. Fatty acids were also better predictors of variation in nestling oxidative status and size than androgens and carotenoids. Conclusions Our results suggest that fatty acids are important yolk substances that contribute to shaping offspring fitness and phenotype in free-living populations. Since polyunsaturated fatty acids cannot be produced de novo by the mother, but have to be obtained from the diet, these findings highlight potential mechanisms (e.g., weather, habitat quality, foraging ability) through which environmental variation may shape maternal effects and consequences for offspring. Our study represents an important first step towards unraveling interactive effects of multiple yolk substances on offspring fitness and phenotypes in free-living populations. It provides the basis for future experiments that will establish the pathways by which yolk components, singly and/or interactively, mediate maternal effects in natural populations.


1970 ◽  
Vol 52 (2) ◽  
pp. 455-468
Author(s):  
R. PRESLEY ◽  
P. F. BAKER

1. A method is described for the direct counting of male pronuclei in recently fertilized sea-urchin eggs. 2. Using this method, fertilization rate determinations were made to compare 30% artificial sea water (A.S.W.), isotonic KCl, sea water containing lauryl sulphate, calcium-free and magnesium-free A.S.W. containing EDTA, and sea water containing uranyl nitrate, as agents blocking fertilization but permitting further development of previously fertilized eggs. 3. 30% A.S.W. was found to be less satisfactory than the other agents, lacking instant effect, and tending to promote polyspermy. The other agents all gave sigmoid rate curves, that of uranyl nitrate lagging 15-25 sec. behind the others. 4. Evidence was found that uranyl nitrate acts at a later stage in fertilization than the other agents. 5. Sigmoid rate curves were found, except with 30% A.S.W., when eggs with the bulk of the jelly coat removed, and nicotine-treated eggs, were fertilized. 6. Analysis of sperm distribution among eggs from samples fertilized for more than 40 sec. confirmed that re-fertilization takes place at a lower rate than primary fertilization. 7. The processes blocked by KCl and uranyl nitrate were found to precede the cortical responses to fertilization, and the termination of nicotine sensitivity.


2019 ◽  
Vol 37 (2) ◽  
pp. 540-548 ◽  
Author(s):  
Clare J Venney ◽  
Oliver P Love ◽  
Ellen Jane Drown ◽  
Daniel D Heath

Abstract The view of maternal effects (nongenetic maternal environmental influence on offspring phenotype) has changed from one of distracting complications in evolutionary genetics to an important evolutionary mechanism for improving offspring fitness. Recent studies have shown that maternal effects act as an adaptive mechanism to prepare offspring for stressful environments. Although research into the magnitude of maternal effects is abundant, the molecular mechanisms of maternal influences on offspring phenotypic variation are not fully understood. Despite recent work identifying DNA methylation as a potential mechanism of nongenetic inheritance, currently proposed links between DNA methylation and parental effects are indirect and primarily involve genomic imprinting. We combined a factorial breeding design and gene-targeted sequencing methods to assess inheritance of methylation during early life stages at 14 genes involved in growth, development, metabolism, stress response, and immune function of Chinook salmon (Oncorhynchus tshawytscha). We found little evidence for additive or nonadditive genetic effects acting on methylation levels during early development; however, we detected significant maternal effects. Consistent with conventional maternal effect data, maternal effects on methylation declined through development and were replaced with nonadditive effects when offspring began exogenous feeding. We mapped methylation at individual CpG sites across the selected candidate genes to test for variation in site-specific methylation profiles and found significant maternal effects at selected CpG sites that also declined with development stage. While intergenerational inheritance of methylated DNA is controversial, we show that CpG-specific methylation may function as an underlying molecular mechanism for maternal effects, with important implications for offspring fitness.


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