Specific PCR assays for the identification of common anisakid nematodes with zoonotic potential

Based on the sequences of the internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal DNA (rDNA) for six taxa of anisakids, namely, Anisakis simplex (s.s.), Anisakis typica, Anisakis pegreffii, Hysterothylacium aduncum, Hysterothylacium sp, and Contracaccum osculatum C, specific primers were designed in the ITS-1 and/or ITS-2 for each of the six anisakid taxa. These specific primers were used to develop polymerase chain reaction (PCR) tools for the identification of these anisakid taxa of sea fish by amplifying partial ITS-1 and/or ITS-2 of rDNA from anisakid nematodes. This approach allowed their specific identification, with no amplicons being amplified from heterogeneous DNA samples, and sequencing confirmed the identity of the DNA fragments amplified. The minimum amounts of DNA detectable using the PCR assays were 0.5-1 ng. These PCR tools were then applied to ascertain the specific identity of 143 anisakid larval samples collected from fish in China, Canada, Thailand, and Indonesia, and these anisakid samples were identified to represent one of the six anisakid taxa. These PCR assays based on ITS sequences should provide useful molecular tools for the accurate identification and molecular epidemiological investigations of anisakid infections in humans and fish.

Endogenous hydrogen sulfide is involved in regulation of respiration in medullary slice of neonatal rats

The purpose of the present study was to verify our assumption that rhythmic respiratory activity may be regulated by endogenous hydrogen sulfide (H(2)S) in the medullary slices of neonatal rats. We found that a moderate concentration of donor of H(2)S, NaHS, mainly induced diphasic respiratory responses indicated by changes of discharge frequency (DF) of hypoglossal rootlets, an initial inhibitory stage followed by a later excitatory one. Cystathionine beta-synthase (CBS) substrate, cysteine (CYS), exerted similar effects. CBS inhibitor, NH(2)OH, could eliminate both inhibitory and excitatory effects in the two stages induced by CYS. K(ATP) channel blocker, glibenclamide (Gl), could eliminate the decrease in DF in the initial stage, but not the increase in the later one. On the other hand, adenyl cyclase (AC) inhibitor, SQ-22536 (SQ) could eliminate the increase in DF in the later stage, but not the decrease in the initial one, of the rootlets caused by NaHS. Co-application of Gl and SQ eliminated both inhibitory and excitatory effect induced by NaHS. The cAMP level was increased in the later stage but not in the initial one by NaHS, and the increase in the cAMP level could be eliminated by SQ. It can be concluded that the endogenous H(2)S could be produced through the CBS-H(2)S pathway and could be involved in the control of the central rhythmic respiration in the in vitro medullary slices of neonatal rats by opening K(ATP) channels and activating AC-cAMP pathway of the neurons.

Statistical comparison of residential soil concentrations of PCDDs, PCDFs, and PCBs from two communities in Michigan

The University of Michigan dioxin exposure study was undertaken to address concerns that the industrial discharge of dioxin-like compounds in the Midland, MI area had resulted in contamination of soils in the Tittabawassee River floodplain and downwind of the incinerator. The study was designed in a rigorously statistical manner comprising soil measurements of 29 polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) from 766 residential properties, selected probabilistically, in the Midland area and in Jackson and Calhoun Counties (Michigan) as a background comparison. A statistical comparison determined that the geometric mean toxic equivalent (TEQ) levels in samples from the target populations were statistically significantly above background. In addition, the probabilities of being above the 75th and 95th percentiles of background were also greater. Congener contributions to the TEQ were dominated by 2,3,4,7,8-PeCDF and 2,3,7,8-TCDF in the floodplain and by 2,3,7,8-TCDD in the incinerator plume. However, PCB 126 was the top congener contributing to the background TEQ. On the basis of statistical inference to the total population, it was estimated that about 36% of the properties in the floodplain and incinerator plume have at least one soil sample over the Michigan Department of Environmental Quality's soil direct contact criterion of 90 pg/g TEQ.