Chironomid egg masses and Vibrio cholerae

Abstract

regions of Israel and were able to isolate V. cholerae from all of these samples.We inoculated fresh egg masses in a saltsolution medium with 1 ǂ10 3 V. cholerae per ml. Two controls were run concurrently: egg masses incubated alone under the same conditions, and medium without egg masses inoculated with 1 ǂ10 3 per ml V. cholerae. We determined growth of V. cholerae after 24 h by plating samples on thiosulphate-citrate-bile salt substrate.The number of bacterial colony-forming units (CFUs) that developed in the first control was always less than 0.1% of that recovered in the treated samples; CFUs recovered in the second control did not change. In the medium containing egg masses as the sole carbon source, V. cholerae reached 2 ǂ10 6 CFU ml ǁ1 . Similar results were obtained when sterilized egg masses were provided as a carbon source. These findings show that egg masses can provide a carbon source to support the development and multiplication of V. cholerae.Although the V. cholerae biotypes isolated here are non-pathogenic, it is likely that chironomid egg masses would also be a suitable (and abundant) substrate for the pathogenic V. cholerae O1 and O139, assuming that the microhabitat of the pathogenic biotypes is similar 4 .An association has been noted between both viable and 'viable but non-culturable' V. cholerae and zooplankton, and copepods have been implicated in the spread of cholera 5,6 . Propagules may be carried by marine zooplankton along the continental seashore, aided by climatic events such as the El Niño Southern Oscillation 7-9 . These results are relevant to the dispersion of pandemics and to the autochthonous existence of V. cholerae in endemic locales during periods between epidemics -when there is local build-up of the bacterium but no outbreak of disease. Our findings indicate that chironomid egg masses may serve as an intermediate 'host' reservoir for V. cholerae, facilitating its survival and multiplication in freshwater bodies.

Vibrio cholerae Strain Typing and Phylogeny Study Based on Simple Sequence Repeats

“…The same alleles were observed in both multiplex and separate amplifications, supporting the use of the multiplex assay for high-throughput typing. The consistency of L-SSR markers was verified in a stability experiment of 4-day colony transfers ("generations") of two representative V. cholerae strains, O1 In-1 (ϩ) and O1 Og ET-109 (Ϫ), each tested for the stability of two loci, VCA0283-(6) 14 and VC0147-(6) 9 . In order to examine the stability of these markers each day, two single colonies were picked from an overnight grown plate and streaked onto a fresh LB plate.…”

“…2a), since three strains (O140-20, O140-21, and O49-128) gave no product at the VC0929-(G) 8 locus (see Table SA3 in the supplemental material). Information from those eight loci enabled the partition- L-SSR VC0147-(6) 9 (AACAGA) 9 Coding (cell division protein FtsY) 10 0.85 VC0437- (7) 7 (GACCCTA) 7 Noncoding (GTP1/Obg family protein) 7 0.78 VC0500- (7) 4 (TTGTCGA) 4 Coding (transposase OrfAB, subunit A, authentic frameshift)…”

“…2). Although clustered together with the environmental strains, the O139 ctxA (Ϫ) isolate presented a unique allele in one SSR locus [VC0147- (6) 9 ] and unique ST in two MNR loci [VC0929-(G) 8 and VC1833-(T) 9 ]. Accordingly, this strain also presented a unique PFGE type, and its serology clearly belonged to the O139 serogroup.…”

“…The GenBank accession numbers for the nucleotide sequence of the 32 strains at eight MNR loci determined in the present study were as follows: EF176922 to EF176953 for VC0332(A) 9 , EF176954 to EF176982 for VC0929(G) 8 , EF176983 to EF177014 for VC1132(A) 9 , EF177015 to EF177046 VC1490(A) 9 , EF177047 to EF177078 for VC1833(T) 9 , EF177079 to EF177110 for VCA0107(T) 8 , EF177111 to EF177142 for VCA0196(A) 8 , and EF177143 to EF177174 for VCA1063(T) 8 .…”

Insights from chironomid oviposition is useful to visual pest control

“…Biological control includes introducing a new organism to the ecosystem which feeds on the infesting pest, infects or otherwise limits or competes with it over resources. Although this method is widely in use, it still has its down to host Vibrio cholerae (Broza & Halpern, 2001;Halpern et al 2004;Broza et al 2008), an important pathogen of the Cholera disease. Although the epidemic strain of the pathogen has not been found on any chironomid species yet (the lethal nonepidemic strains were found), it is likely that it will be in the near future (Malka Halpern, pers.…”