Search results for "Gonad"
showing 10 items of 240 documents
Seasonal Variations in Biochemical Composition of the ClamDosinia corrugatein Relation to the Reproductive Cycle and Environmental Conditions
2016
ABSTRACT Seasonal variations in biochemical composition of the clam Dosinia corrugate were investigated from August 2013 until July 2014 in Zhuanghe Bay in relation to environmental conditions and reproductive cycle. Separate biochemical analyses of the mantle, adductor muscle, foot, and gonad-visceral mass in each sex were undertaken. Spawning took place once a year from July to August and the massive spawning occurred in August with the highest water temperature and chlorophyll a levels. Utilization of glycogen took place during the spawning period, whereas protein was biosynthesized as the mature gametes formed. The glycogen value increased during the resting stage (autumn—winter). The r…
Pigmentation polymorphism in the invasive amphipod Dikerogammarus villosus : some insights into its maintenance
2004
Dikerogammarus villosus, a freshwater invasive amphipod, exhibits conspicuous pigmentation polymorphism. This polymorphism is documented in two recently colonized areas, the Saand Moselle rivers (north-eastern France), and some of the mechanisms by which pigmentation polymorphism can arise and be maintained are addressed. Body size, reproductive status, fecundity and mate choice are compared among morphs of D. villosus in field samples collected in summer 2001. Body size and female gonad developmental stage were comparable among the different morphs, suggesting that polymorphism is not the result of changes in pigmentation with age or moult- cycle. Fecundity and reproductive status (paired …
Filling gaps: closing the life cycle of the endangered Mediterranean limpet Patella ferruginea Gmelin, 1791 (Gastropoda, Patellidae)
2020
Several reproductive issues and the larval development of the ferruginous limpet, Patella ferruginea Gmelin, 1791, an endangered species endemic from the western Mediterranean Sea, were studied to fill gaps in the knowledge of its life cycle. Average diameter of mature oocytes was 141.83 μm and mean oocyte density in the ovary was 283,800 oocytes/gram. No significant correlations were found between both oocyte diameter or density and female shell length. Female fecundity (number of oocytes per gonad) was significantly correlated with shell length and varied between 189,200 oocytes in a 40.0 mm female and 5,019,200 oocytes in an 86.4 mm female. However, there was considerable variability, in…
Maternal effects in quail and zebra finches: behavior and hormones.
2013
8 pages; International audience; Maternal effects are influences of parents on offspring phenotype occurring through pathways other than inherited DNA. In birds, two important routes for such transmission are parental behavior and non-DNA egg constituents such as yolk hormones. Offspring traits subject to parental effects include behavior and endocrine function. Research from the Adkins-Regan lab has used three avian species to investigate maternal effects related to hormones and behavior. Experiments with chickens and Japanese quail have shown that maternal sex steroids can influence sex determination to produce biased offspring sex ratios. Because all birds have a ZZ/ZW chromosomal sex de…
Reproductive and bloom patterns of Pelagia noctiluca in the Strait of Messina, Italy
2018
Special issue Vectors of change in the marine environment.-- 11 pages, 7 figures, 1 table, supplementary data https://doi.org/10.1016/j.ecss.2016.01.002
Evidence for ontogenetically and morphologically distinct alternative reproductive tactics in the invasive Round Goby Neogobius melanostomus.
2017
Alternative reproductive tactics are characterized by the occurrence of discrete alternative morphs that differ in behavioural, morphological and physiological traits within the same sex. Although much effort has been made to describe the behaviour, morphology and physiology of such alternative morphs, less effort has been invested investigating how much overlap there is in the characteristics of such morphs in natural populations. We studied random population samples of the invasive Round Goby Neogobius melanostomus from five different localities in the river Rhine system in the Netherlands. We found two morphologically and physiologically distinct male morphs which likely represent altern…
Endocrine correlates of the breeding asynchrony between two Corsican populations of Blue tits (Parus caeruleus)
2004
International audience; Analyses of the development of the reproductive system in seasonally breeding birds in the framework of long-term ecological studies are rare. Here, we present the Wrst results of such a study in two Corsican populations of a European passerine bird, the blue tit (Parus caeruleus). The two study populations occupy diVerent oak habitats and are separated by only 25km. Despite their close proximity, they show a one-month diVerence in onset of egg laying, even after controlling for altitude. This micro-geographic diVerence in breeding date appears adaptive because both study populations raise chicks when food is most plentiful. In our study, males reached their maximum …
Chasing phthalates in tissues of marine turtles from the Mediterranean sea
2018
Tissues from thirteen specimens of marine turtles, one Dermochelys coriacea and twelve Caretta caretta, found dead along the Sicilian coasts in 2016 were analyzed for the presence of phthalates. Four phthalates (DEP, DBP, BBP, and DEHP) were found at different significant concentrations in liver and gonads, while only DBP was found in muscle tissues and at a fourfold lower concentration than other phthalates in Dermochelys coriacea. No traces of DEP were detected in C. caretta tissues where DOTP was also revealed. The presence of phthalates in fat tissue in specimens of C. caretta showed a major prevalence of the most lipophilic phthalates DEHP and DOTP. The total concentration of all analy…
Seasonal variability of diet and trophic level of the gelatinous predator Pelagia noctiluca (Scyphozoa)
2018
13 pages, 5 figures, 2 tables, supplementary information https://doi.org/10.1038/s41598-018-30474-x
Seasonal changes in European whitefish muscle and invertebrate prey fatty acid composition in a subarctic lake
2019
Ambient light and temperature show extreme seasonal variation in subarctic lakes due to the midnight sun period in summer and cold polar night period in winter. These changes have clear impacts on fish feeding and reproduction cycles, potentially affecting the fatty acid (FA) composition of muscle. Despite extensive research into fish FA over recent decades, we know little about intra‐annual changes of fish FA profile and content. We studied intra‐annual changes in the FA profile (mol%) and content (mg g‐1 dry weight) of sexually mature European whitefish (Coregonus lavaretus) muscle in a large and deep subarctic lake located in northern Fennoscandia. We collected fish, zooplankton, and ben…