Receptor-Mediated Inhibition of Reproductive Activity in a Schistosome-Infected Freshwater Snail

Author(s):  
P. L. Hordijk ◽  
R. H. M. Ebberink ◽  
M. de Jong-Brink ◽  
J. Joosse
Reproduction ◽  
1972 ◽  
Vol 29 (1) ◽  
pp. 150-151 ◽  
Author(s):  
A. Gilbert

2019 ◽  
Vol 14 (1) ◽  
pp. 58
Author(s):  
Luis Eduardo Gualdrón-Durán ◽  
María Fernanda Calvo-Castellanos ◽  
Martha Patricia Ramírez-Pinilla

1994 ◽  
Vol 29 (3) ◽  
pp. 281-288 ◽  
Author(s):  
A. Siepe

The floodplain of the Upper Rhine and its biocoenoses have, through different river-regulatory activities over the last 175 years, undergone large scale degradation. At the same time flood protection for the downstream inhabitants has been greatly reduced. For reasons of flood protection, the “Polder Altenheim” in Baden-Württemberg, Germany southwest of Strasbourg, France, with so called retention flooding, was put into operation in 1987. The original floodplain had been diked for the previous 17 years, during which no flooding occurred. Since 1989 “ecological flooding” also is carried out. This has assisted in the regeneration of floodplain biotopes and promoted the floodplain biotic communities and the readaption of the bioceonosis to a regular flooding regime. The creation of new floodplain biotopes of early succession stages, particularly through geomorphodynamic processes, has followed the more than ten flood ocassions and typical biotic communities have colonised these sites. This will be presented together with selected examples of terrestrial and limnical species and communities. The following species and communities will be discussed: kingfisher Alcedo atthis, carabid communities (Coleoptera), the red alga Hildenbrandia rivularis (Rhodophyceae), the freshwater snail Theodoxus fluviatilis (Neritacea) and the freshwater bug Aphelocheirus aestivalis (Hydrocorisae).


1984 ◽  
Vol 32 (6) ◽  
pp. 721 ◽  
Author(s):  
H Marsh ◽  
GE Heinsohn ◽  
TD Glover

The anatomy and histology of the male reproductive tract of the dugong (Dugong dugon) is described. Each testis and its adjacent epididymis lie immediately caudal to the corresponding kidney. The seminal vesicles are large but there is no discrete prostate gland and the bulbo-urethral glands are also diffuse. Both qualitative and quantitative examination of the testes and epididymides of 59 males whose ages have been estimated from tusk dentinal growth layer counts indicate that the male dugong does not produce spermatozoa continuously, despite the absence of a distinct breeding season. Individual dugongs were observed with testes at all stages between complete quiescence and full spermatogenesis, and only 10 of the 40 mature males had fully spermatogenic testes and epididymides packed with spermatozoa. Androgenic and spermatogenic activity of the testes appeared to be in phase, but the testicular histology of some old males suggested that they may have been sterile for long periods.


Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1149
Author(s):  
Mi-Jung Bae ◽  
Eui-Jin Kim ◽  
Young-Seuk Park

Pomacea canaliculata (known as invasive apple snail) is a freshwater snail native to South America that was introduced into many countries (including Asia and North America) as a food source or for organic farming systems. However, it has invaded freshwater ecosystems and become a serious agricultural pest in paddy fields. Water temperature is an important factor determining behavior and successful establishment in new areas. We examined the behavioral responses of P. canaliculata with water temperature changes from 25 °C to 30 °C, 20 °C, and 15 °C by quantifying changes in nine behaviors. At the acclimated temperature (25 °C), the mobility of P. canaliculata was low during the day, but high at night. Clinging behavior increased as the water temperature decreased from 25 °C to 20 °C or 15 °C. Conversely, ventilation and food consumption increased when the water temperature increased from 25 °C to 30 °C. A self-organizing map (an unsupervised artificial neural network) was used to classify the behavioral patterns into seven clusters at different water temperatures. These results suggest that the activity levels or certain behaviors of P. canaliculata vary with the water temperature conditions. Understanding the thermal biology of P. canaliculata may be crucial for managing this invasive snail.


Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1874
Author(s):  
Alberto Elmi ◽  
Nadia Govoni ◽  
Augusta Zannoni ◽  
Martina Bertocchi ◽  
Chiara Bernardini ◽  
...  

Roe deer are seasonal breeders with a complete yearly testicular cycle. The peak in reproductive activity is recorded during summer, the rutting period, with the highest levels of androgens and testicular weight. Melatonin plays a pivotal role in seasonal breeders by stimulating the hypothalamus–pituitary–gonads axis and acting locally; in different species, its synthesis within testes has been reported. The aim of this study was to evaluate the physiological melatonin pattern within roe deer testes by comparing data obtained from animals sampled during pre- and post-rut periods. Melatonin was quantified in testicular parenchyma, along with the genetic expression of enzymes involved in its local synthesis (AANAT and ASMT) and function (UCP1). Melatonin receptors, MT1-2, were quantified both at protein and gene expression levels. Finally, to assess changes in reproductive hormonal profiles, testicular dehydroepiandrosterone (DHEA) was quantified and used for a correlation analysis. Melatonin and AANAT were detected in all samples, without significant differences between pre- and post-rut periods. Despite DHEA levels confirming testicular involution during the post-rut period, no correlations appeared between such involution and melatonin pathways. This study represents the first report regarding melatonin synthesis in roe deer testes, opening the way for future prospective studies in the physiology of this species.


Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 361
Author(s):  
Nicky M. M. D’Fonseca ◽  
Charlotte M. E. Gibson ◽  
Iris Hummel ◽  
David A. van Doorn ◽  
Ellen Roelfsema ◽  
...  

Obesity has been associated with altered reproductive activity in mares, and may negatively affect fertility. To examine the influence of long-term high-energy (HE) feeding on fertility, Shetland pony mares were fed a diet containing 200% of net energy (NE) requirements during a three-year study. The incidence of hemorrhagic anovulatory follicles (HAF) and annual duration of cyclicity were compared to those in control mares receiving a maintenance diet. Day-7 embryos were flushed and transferred between donor and recipient mares from both groups; the resulting conceptuses were collected 21 days after transfer to assess conceptus development. HE mares became obese, and embryos recovered from HE mares were more likely to succumb to early embryonic death. The period of annual cyclicity was extended in HE compared to control mares in all years. The incidence of HAFs did not consistently differ between HE and control mares. No differences in embryo morphometric parameters were apparent. In conclusion, consuming a HE diet extended the duration of cyclicity, and appeared to increase the likelihood of embryos undergoing early embryonic death following embryo transfer.


Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 660
Author(s):  
Edoardo Bardi ◽  
Martina Manfredi ◽  
Raffaella Capitelli ◽  
Emanuele Lubian ◽  
Alessandro Vetere ◽  
...  

The use of long-acting gonadotropin-releasing hormone (GnRH) agonists to suppress fertility has been poorly investigated in reptiles, and the few available studies show inconsistent results. The efficacy of single and double intramuscular 4.7 mg deslorelin acetate implants in captive pond sliders (Trachemys scripta) was investigated, with 20 animals divided into three groups: a single-implant group (6 animals), a double-implant group (6 animals), and a control group (no implant). During one reproductive season (March to October), plasmatic concentration of sexual hormones (estradiol, progesterone, and testosterone) and ovarian morphometric activity via computed tomography were monitored about every 30 days. A significative decrease in the number of phase II ovarian follicles was detected in the double-implant group compared with the control group, but no significant difference was noted in the number of phase III and phase IV follicles, egg production, and plasmatic concentration of sexual hormones. Results show that neither a single nor a double deslorelin acetate implant can successfully inhibit reproduction in female pond sliders during the ongoing season, but the lower number of phase II follicles in the double-implant group can possibly be associated with reduced fertility in the following seasons.


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