Evidence for a Light Compensation of the Inhibitionof Reproduction by Low Temperatures in the Snail Helix Asperse. Ovotestis and Albumen Gland Responsiveness to Different Conditions of Photoperiods and Temperatures

Abstract

Four combinations of photoperiods and temperatures have been tested on the reproduction and on the activity of the genital apparatus of the snail Helix aspersa. The results show some interaction between photoperiod and temperature and reveal a predominant effect of photoperiod that compensates for the negative effect of low temperatures. A combination of long day (LD, 18L:6D) and a temperature of 20 degrees C is the most favorable condition for egg-laying as well as for the effective functioning of the ovotestis and albumen gland. In contrast, during a short day (SD, 8L:16D), egg-laying is completely inhibited at 15 degrees C and partly inhibited at 20 degrees C; the differentiation of gametes can be observed in the ovotestis, but the mature oocytes are not released and thus they degenerate. In the albumen gland, an important synthetic activity is noticed, but cellular multiplication and the release of the secretory products decrease. These results suggest that short photoperiods induce inhibition of the (neuro)endocrine centers responsible for the control of both ovulation and egg-laying.

Lipids analysis in hemolymph of African giant Achatina fulica (Bowdich, 1822) exposed to different photoperiods

“…Due to the great biomass of A. fulica, this period was increased to analyse the possible alterations in this snail (Gomot et al, 1989;Gomot, 1990).…”

Nitric oxide synthesis is blocked in the enteral nervous system during dormant periods of the snail Helix lucorum

“…Metabolic rate depression is the common adaptive strategy of the long-term dormant periods of the terrestrial Helix genus. Summer dormancy or estivation occurs in dry periods of the summer, whereas winter dormancy or hibernation is triggered by a declining photoperiod in late October, which in Europe is interrupted in April (Gomot et al 1989;Ansart et al 2001). In snails preparing for entry into dormancy, the pallial glands build an epiphragm which closes the ostium of the cochlear domus.…”

Efeito do fotoperíodo sobre o ciclo de vida e a morfometria da concha de Dysopeas muibum (Mollusca, Subulinidae) em condições de laboratório

“…As pesquisas sobre influência do fotoperíodo no ciclo de vida de gastrópodes terrestres foram feitos, na maior parte, com Helix aspersa Müller, 1774 (Helicidae), provavelmente por ser essa uma espécie de interesse econômico (BaiLey, 1981;enée et al, 1982;Bonnefoy-cLauDet et al, 1983;Le guhennec & Daguzan, 1983;Laurent et al, 1984;gomot & gomot, 1985;griffonD & vincent, 1985;Bonnefoy-cLauDet & Deray, 1987;Deray & Laurent, 1987;gomot et al, 1989). Tais estudos também foram conduzidos com Bradybaena similaris (Férussac, 1821) (Xanthonychidae) (garcia & Pinheiro, 2007), Achatina achatina (Linnaeus, 1758) (Achatinidae) (hoDasi, 1982), Deroceras reticulatum (Müller, 1774) (Agriolimacidae) (henDerson & PeLLuet, 1960), Limax maximus Linnaeus, 1758 (Limacidae) (sokoLove & mccrone, 1978;mccrone et al, 1981;meLrose et al, 1983), Helix pomatia Linnaeus, 1758 e Cepaea nemoralis (Linnaeus, 1758) (Helicidae) (hunter & stone, 1986; gomot, 1990).…”

“…O ciclo de vida e a morfologia dos moluscos terrestres são fortemente influenciados por alterações nos fatores abióticos, como temperatura, pluviosidade, umidade, substrato e fotoperíodo (Lüsis, 1966;Dimitrieva, 1975;Wareing & BaiLey, 1985;gomot et al, 1989;gomot, 1990;south, 1992;asami, 1999;D'ÁviLa et al, 2004;D'ÁviLa & Bessa, 2005a,b,c;hausDorf, 2006;anDerson et al, 2007;uDaka et al, 2007). Mudanças sazonais em alguns destes fatores podem regular as taxas de crescimento, o desenvolvimento, a sobrevivência e o ciclo reprodutivo de gastrópodes terrestres, incluindo a gametogênese, a corte e a cópula, principalmente pelas mesmas atuarem no controle hormonal e na conversão de reservas energéticas (Wayne, 2001;garcia & Pinheiro, 2007;uDaka et al, 2007).…”