Female termites found to clone themselves via asexual reproduction
A distinguished invertebrate reproductive biologist, who gave the discipline of invertebrate reproductive biology a global distinctiveness and identity of its own, Dr. Rita G. The Adiyodis have worked extensively, over the past three decades, on the endocrinology and physiology of growth and reproduction of arthropods, chiefly crustaceans. He holds a B.
His chief field of research is spermatozoal ultrastructure and its relevance to phylogeny but he is also an authority on taxonomy of earthworms and has published on bioluminescence, trematode taxonomy and life cycles, and DNA-based phylogenetics. He has published nearly scientific papers and is the author, coauthor or editor of nine books. Higgins, Thomas C.
Shirley, and Barrie G. Jamieson 2. Mollusca: Relict Taxa John M. Immediately after the rubber bands were placed in the mid-body of the sea cucumbers, they started to constrict slightly in the middle and showed some swelling in the posterior section Plate 3A. After one hour, the constriction became slightly more distinct; giving a heart shape to the posterior half Plate 3B. The anterior and posterior sections slowly rotated in opposite directions resulting in a more distinct construction Plate 3C.
The posterior half of the individual remained stationary while the anterior end continued to move forward.pesicareti.ga
Asexual reproduction - Wikipedia
At this point, the body wall at the fission site started to rupture, and some white tissue started to appear in the constriction area. The two body parts remained connected by only a string of tissue for at least four more hours Plate 3D. The entire process of fission lasted for a whole day. The body wall at the fission site remained a liquid or mucus like consistency for at least six more hours Plate 3E. After two days, the body wall had its normal consistency and the wounds at both ends were healed and nearly entirely closed Plate 3F.
Dissections of the posterior and anterior halves of the individual immediately after fissions revealed that most of the intestines, and the respiratory organs water lungs were separated equally between the two sections. Plate 3. Photographs showing the process of induced transverse fission in A.
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Figure 6. Survival rate of asexual reproduction experiment for two size groups of A. Dissection of the sea cucumber on a monthly interval indicated that large individuals of A. In contrast, small animals average length 12 cm and average weight g were able to regenerate both anterior and posterior parts into whole individuals in around 60 to 80 days. The shortest regeneration time was for the posterior parts of the smallest size class.
This species exhibits traits typical of many aspidochirote holothurian species: annual reproductive cycle, gametogenesis occurring in synchrony among sexes, partial spawning and total gonad resorption after spawning. Size at first maturity was very similar for both sexes. The size of gonadal tubules and oocytes diameters were correlated to gametogenesis and corresponded well to the descriptive maturity stages assigned to this species. This supports previous work on the same species in which the size of gonadal tubules was recommended as adequately reflecting the maturation process Ramofafia et al.
The data on gonad index, tubule morphology and gonad histology indicate that Actinopyga mauritiana has an annual reproductive cycle in the Red Sea and that gametogenesis occurs in synchrony in both sexes.
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In general, the period of peak reproductive activity is between spring and summer. An annual reproductive cycle with a summer spawning season has also been recorded for this species in Solomon Islands Ramofafia et al. Spawning in Actinopyga mauritiana is partial with mature and spawned tubules evident in dissected specimens during the breeding season.
Furthermore, histology revealed that not all gametes were released from spawned tubules and that re-initiation of gametogenesis occurred in these tubules. It is not known whether unspawned tubules will eventually release their gametes. Partial spawning has been documented for the same species Ramofafia et al. This study showed that there was a period during the reproductive cycle in which the gonads were absent. This suggests that total resorption of the gonads may happen. The resorption of gonad in spawned individuals again supports the observations in previous studies on the same species Ramofafia et al.
This process had not been previously observed in Actinopyga mauritiana. Rubber bands placed mid-body of the individuals may provide an effective yet simple technique to induce transverse fission. Asexual reproduction in A. The mechanical properties of the body wall of many holothurians are well described for S. These tissues may contract or expand nearly instantaneously without the action of muscles, probably under the control of the nervous system Wilkie, Actinopyga mauritiana appears to be another good example of a species with these properties.
It appears that in addition to asexual reproduction, another important function of the catch connective tissue is to aide rapid wound healing. The overall trend in the fission study was that higher survival rates were seen in the smaller size group and that the posterior ends had better survival and regeneration rates than the anterior ends. This was observed previously in other holothurians Reichenbach et al. The ability of the posterior parts to obtain oxygen needed for more energy may be a crucial factor in the process.
This may be supported by the presence of the origin of the respiratory trees in the posterior part. On the contrary, the anterior part will obtain its oxygen through diffusion across the body until the respiratory trees are regenerated. Out of the spawning season, asexual reproduction appears as the most practical option for increasing the stock of A. Uthicke suggested that the body size of sea cucumber could have an effect on the likelihood of asexual reproduction taking place. This also agrees with previous studies on temperate water species, in which a sea cucumber takes from 30 to days to regenerate Byrne, This possible application of asexual propagation of A.
At the simplest level, it may offer a good means of increasing the broodstock of cultured animals, thereby reducing the pressure on the natural environment.
However, this will only be applicable if both the anterior and posterior sections are able to regenerate reproductive organs. These have not been observed in the current study. Actinopyga mauritiana is commercially important for the production of beche-de-mer, a dried body wall product. Depletion of wild stocks and interest in aquaculture of this species prompted the current investigation of aspects of their biology essential for artificial culture.
Gametes are spawned from early spring through to summer with increased spawning activity in spring. Spawning coincided with the spring plankton bloom in the Red Sea, increasing day length and seawater temperature. This suggests that food supply, photoperiod and temperature should be tested as triggers for artificial spawning of broodstock in culture. Although, in nature asexual reproduction has not been observed in A.
The overall trend was that the survival rate increased in smaller individuals. The implications of this for the management of A. In the first instance, further research is required on the possible influence of fission on sexual reproductive activities and genetic alterations of culture and wild populations. The research was funded by the UK Darwin Initiative. Battaglene, S. Potential of the tropical Indo-Pacific sea cucumber, Holothuria scabra, for stock enhancement.
Progress in Asexual Reproduction: Vol. 11 Reproductive Biology of Invertebrates
In: Stock Enhancement and Sea Ranching. Howell, B. Blackwell, Oxford. Survival and growth of cultured juvenile sea cucumbers Holothuria scabra. Aquaculture, Byrne, M. Evisceration behaviour and the sesonal incidence of evscration in the Holothurian Eupentacta quinquestemita Selenka.
Ophelia, Chao, S. M, Chen, C. Fission and its effect on population structure of Holothuria atra Echinodermata: Holothuroidea in Taiwan.
Publications in the Blackstone Lab
Marine Biology, Conand, C. Reproductive biology of the holothurians from the major communities for the New Caledonia lagoon. Asexual reproduction by fission in Holothuria atra. Variability of some parameters in populations from the tropical Indo-Pacific. Oceanol Acta. A review of recent developments in the world sea cucumber fisheries. Marine Fisheries Review, Reproduction asexuee per scission chez Holothuria atra Holothuroidea dans des populations de platiers recifamx.
In: Echinoderm researech.