Lizard reproduction

Leopard lizard, Crotaphytus wislizenir, chronic field exposure of 0.04-0.06 Gy daily (4-5 Sv yearly) for 3-6 years No female reproduction in years 3 and 4. In year 5, males were sterile and females had complete regression of ovaries, undeveloped oviductal walls, and hypertrophied fat bodies. In year 6, 75% of females lacked ovaries and 25% had normal ovaries with signs of recent egg deposition males appeared normal 1... 

Much of the behaviour of humans and society as a whole is designed to provide an opportunity for a sperm and an ovum to meet in the uterus. However, sexual reproduction is not the only means of reproduction asexual reproduction occurs frequently in the animal kingdom and in many tissues in order to increase the number of cells during growth or to maintain the number due to cell death. The question arises, therefore, why sexual reproduction has arisen at all since it is very expensive in the use of resources for example, in the process of selecting a suitable mate, and in the requirement for males, whose only function in some species is fertilisation of the females, yet they use resources that could be used by the females and by the offspring. Perhaps because of this, a few species of vertebrates (e.g. some lizards) have retained the option for asexual reproduction. This process is known as parthenogenesis. Mammals, however, have lost this option. This... 

As shown in Fig. 1, poly(ADP-ribose) transferase activity in lizard oviduct nuclei undergoes a marked variation during the reproductive cycle. An increase in poly(ADP-ribose) transferase activity was observed at the begiiming of the recovery phase (die middle of March-April) widi the peak (12 times the activity detected during the reproductive stasis and secretory period) about the first week of May after the oviduct had reached its maximum growth and was ready to be functional. Oviduct growth followed the increase in poly(ADP-ribose) transferase activity. Enzyme activity in... 

Fig. 1. Variation of oviduct and gonado-somatic indexes and poly(ADP-ribose)transferase activity in the oviduct during the reproductive cycle of the lizard Podarcis s.siculaRaf. The poly(ADP-ribose) transferase assay was performed as described in Ciarcia et al. (7). ( ) gonado/somatic index (O) oviduct/somatic index (A) poly(ADP-ribose) transferase activity in nuclear extracts. Arrow indicates when SNP appeared.

Fig. 2. Oeft) SDS-PAGE of histone-rich fractions in oviduct of intact lizards during the reproductive cycle. SDS-PAGE was carried out according to Laemmli (16). Extraction of the histone-rich fractions from nuclei was performed as described in Ciarcia et al, (7). a and e calf thymus b oviduct in toto during the winter stasis c oviduct in toto during the recovery phase d oviduct in toto during the post-ovulatory period f uterine tract during the recovery phase g tubal tract during the recovery phase.

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