EVIDENCE FOR THE VERTICAL TRANSMISSION OF AN ENDOCYTOBIOTIC CYANOBACTERIUM IN Pomacea canaliculata (AMPULLARIIDAE)

KOCH, E.; VEGA, I.A.; CASTRO-VAZQUEZ, A.

Huerta Grande - Córdoba

Congreso; I Reunión Conjunta de Sociedades de Biología de la República Argentina; 2007

P. canaliculata hosts a cyanobacterium within the midgut gland’s cells. This is the only known obligate endocytobiosis between an animal and a cyanobacterium, and one of the few known in eukaryotes. In a previous study, all embryos that were aseptically obtained from eggs and that were cultured in a sterile medium over 7 days showed the endocyanobionts in their midgut glands at the end of this period, suggesting a vertical mother-offspring transmission of the symbiont. Since no cyanobacterial cells were morphologically identified within the eggs or embryos, we explored here the existence of sequences of the gene encoding for 16S rRNA, in a DNA extract from newly deposited eggs, using PCR and the generalized probes CYA 106F and CYA 781R. A band of the expected size (~670 bp) was obtained and sequenced, and was found identical to the corresponding sequence of cyanobionts obtained from adult snails. An attempt was made to identify the same sequence in DNA extracted from aseptically obtained juveniles. Also, a band of ~670 bp was obtained after preamplification with the generalized bacterial probes EUB 27F and EUB 1525R, and amplification with the cyanobacterial generalized probes. hosts a cyanobacterium within the midgut gland’s cells. This is the only known obligate endocytobiosis between an animal and a cyanobacterium, and one of the few known in eukaryotes. In a previous study, all embryos that were aseptically obtained from eggs and that were cultured in a sterile medium over 7 days showed the endocyanobionts in their midgut glands at the end of this period, suggesting a vertical mother-offspring transmission of the symbiont. Since no cyanobacterial cells were morphologically identified within the eggs or embryos, we explored here the existence of sequences of the gene encoding for 16S rRNA, in a DNA extract from newly deposited eggs, using PCR and the generalized probes CYA 106F and CYA 781R. A band of the expected size (~670 bp) was obtained and sequenced, and was found identical to the corresponding sequence of cyanobionts obtained from adult snails. An attempt was made to identify the same sequence in DNA extracted from aseptically obtained juveniles. Also, a band of ~670 bp was obtained after preamplification with the generalized bacterial probes EUB 27F and EUB 1525R, and amplification with the cyanobacterial generalized probes.