Geographic Variations in the Toxin Profile of the Xanthid Crab Zosimus aeneus in a Single Reef on Ishigaki Island,Okinawa, Japan

Toxic crabs of the family Xanthidae contain saxitoxins (STXs) and/or tetrodotoxin (TTX), but the toxin ratio differs depending on their habitat. In the present study, to clarify within reef variations in the toxin profile of xanthid crabs, we collected specimens of the toxic xanthid crab Zosimus aeneus and their sampling location within a single reef (Yoshihara reef) on Ishigaki Island, Okinawa Prefecture, Japan, in 2018 and 2019. The STXs/TTX content within the appendages and viscera or stomach contents of each specimen was determined by instrumental analyses. Our findings revealed the existence of three zones in Yoshihara reef; one in which many individuals accumulate extremely high concentrations of STXs (northwestern part of the reef; NW zone), another in which individuals generally have small amounts of TTX but little STXs (central part of the reef; CTR zone), and a third in which individuals generally exhibit intermediate characteristics (southeastern part of the reef; SE zone). Furthermore, light microscopic observations of the stomach contents of crab specimens collected from the NW and CTR zones revealed that ascidian spicules of the genus Lissoclinum were dominant in the NW zone, whereas those of the genus Trididemnum were dominant in the CTR zone. Although the toxicity of these ascidians is unknown, Lissoclinum ascidians are considered good candidate source organisms of STXs harbored by toxic xanthid crabs.     

Ultrastructural study on the morphological changes in indigenous bacteria of mucous layer and chyme throughout the rat intestine

Indigenous bacteria in the alimentary tract are exposed to various bactericidal peptides and digestive enzymes, but the viability status and morphological changes of indigenous bacteria are unclear. Therefore, the present study aimed to ultrastructurally clarify the degeneration and viability status of indigenous bacteria in the rat intestine. The majority of indigenous bacteria in the ileal mucous layer possessed intact cytoplasm, but the cytoplasm of a few bacteria contained vacuoles. The vacuoles were more frequently found in bacteria of ileal chyme than in those of ileal mucous layer and were found in a large majority of bacteria in both the mucous layer and chyme throughout the large intestine. In the dividing bacteria of the mucous layer and chyme throughout the intestine, the ratio of area occupied by vacuoles was almost always less than 10%. Lysis or detachment of the cell wall in the indigenous bacteria was more frequently found in the large intestine than in the ileum, whereas bacterial remnants, such as cell walls, were distributed almost evenly throughout the intestine. In an experimental control of long-time-cultured Staphylococcus epidermidis on agar, similar vacuoles were also found, but cell-wall degeneration was never observed. From these findings, indigenous bacteria in the mucous layer were ultrastructurally confirmed to be the source of indigenous bacteria in the chyme. Furthermore, the results suggested that indigenous bacteria were more severely degenerated toward the large intestine and were probably degraded in the intestine.     

Neuropathogenicity of Equine Herpesvirus 9 in Cattle

The pathogenicity of equine herpesvirus 9 (EHV-9), a neurotropic equine herpesvirus isolated from a herd of Gazella thomsoni, was studied in cattle. Seven calves were inoculated intranasally with 10⁵ and 10⁷ plaque-forming units of the EHV-9 P19. Three animals showed brain lesions consisting of glial reactions and perivascular cuffings in the olfactory bulb and the frontal and temporal lobes. Additionally, the animal that was inoculated with 10⁷ plaque-forming units showed neuronal degeneration and loss, as well as nuclear inclusions compatible with herpesvirus. EHV-9 was isolated from the brain of calf 6 and the lungs of calves 1 and 2. The results suggested that cattle are susceptible to experimental infection with EHV-9 and at risk from natural infection from reservoir hosts.     

Detection of Chlamydophila psittaci by using SYBR green real-time PCR

Chlamydophila psittaci is the causative agent of human psittacosis and avian chlamydiosis. This zoonotic pathogen is frequently transmitted from infected birds to humans. Therefore proper and rapid detection of C. psittaci in birds is important to control this disease. We developed a method for detecting C. psittaci by using SYBR Green Real-time PCR based on targeting the cysteine-rich protein gene (envB) of C. psittaci. This one step procedure was highly sensitive and rapid for detection and quantification of C. psittaci from fecal samples. This assay was also able to detect other zoonotic Chlamydophila species such as C. abortus and C. felis. The assay is well suited for use as a routine detection method in veterinary medicine.     

Assay of chitinase and N-acetylglucosaminidase activity in forest soils with 4-methylumbelliferyl derivatives

Chitinase and N-acetylglucosaminidase activities in forest soils were examined by a highly sensitive method using 4-methylumbelliferyl (4MU) derivatives of N-acetyl-D-glucosamine oligomers as substrates. The method involves the fluorometric estimation of the 4-MU released through the activity of the soil enzymes when a soil sample and the substrate are incubated in a buffer. The activities of both enzymes decreased markedly with depth in the 4 forest soil profiles studied (i.e. Andosol, Podzol, 2 Cambisols). The activities of these soil enzymes were highly correlated with the carbon and nitrogen content of the soils.     

Visualizing gas molecules interacting with supported nanoparticulate catalysts at reaction conditions

Understanding how molecules can restructure the surfaces of heterogeneous catalysts under reaction conditions requires methods that can visualize atoms in real space and time. We applied a newly developed aberration-corrected environmental transmission electron microscopy to show that adsorbed carbon monoxide (CO) molecules caused the {100} facets of a gold nanoparticle to reconstruct during CO oxidation at room temperature. The CO molecules adsorbed at the on-top sites of gold atoms in the reconstructed surface, and the energetic favorability of this reconstructed structure was confirmed by ab initio calculations and image simulations. This atomic-scale visualizing method can be applied to help elucidate reaction mechanisms in heterogeneous catalysis.     

Detection of Salmonella invA by isothermal and chimeric primer-initiated amplification of nucleic acids (ICAN) in Zambia

The isothermal and chimeric primer-initiated amplification of nucleic acids (ICAN) is a new isothermal DNA amplification method composed of exo Bca DNA polymerase, RNaseH and DNA–RNA chimeric primers. We detected invA of Salmonella from chicken carcasses, egg yolk and cattle fecal samples. Fifty-three of 59 isolates were invA-positive in ICAN-chromatostrip detection. The result was consistent with those obtained by standard PCR. Salmonella invA was detected in 12 of 14 carcass rinses by ICAN, while in 7 of 14 rinses by standard PCR. These results indicate that ICAN is an efficient, sensitive and simple system to detect invA of Salmonella species in developing countries such as Zambia.