The enhancement of Th1 immune response by anti-PD-L1 antibody in cattle infected with Mycobacterium avium subsp. paratuberculosis

Johne’s disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP), is a chronic enteritis of ruminants. Previous studies have shown that programmed death-ligand 1 (PD-L1) is associated with the disease progression, and PD-L1 blockade activates MAP-specific Th1 responses in vitro. Here, we performed anti-PD-L1 antibody administration using 2 MAP-infected cattle at the late subclinical stage of infection. After administration, bacterial shedding was reduced or maintained at a low level. Additionally, MAP-specific Th1 cytokine production was upregulated, and CD69 expression was increased in T cells. Collectively, the treatment has a potential as a novel control method against Johne’s disease.     

Near-infrared imaging spectroscopy based on sugar absorption band for melons.

A method for visualizing the sugar content in the flesh of melons was developed. This method was based on the sugar absorption band in the near-infrared (NIR) region to avoid bias caused by the color information of a sample. NIR spectroscopic analysis revealed that each of the two second-derivative absorbances at 874 and 902 nm had a high correlation with the sugar content of melons. A high-resolution cooled charged couple device camera with band-pass filters, which included the above two wavelengths, was used to capture the spectral absorption image of a half-cut melon. A color distribution map of the sugar content on the surface of the melon was constructed by applying the NIR spectroscopy theory to each pixel of the acquired images.     

Lignification in developing culms of bamboo <Emphasis Type="Italic">Sinobambusa tootsik</Emphasis>

Bamboos are among the largest woody grasses and grow very rapidly. Although lignin is a crucial factor for the utilization of bamboo biomass, the lignification mechanism of bamboo shoots is poorly understood. We studied lignification in the bamboo Sinobambusa tootsik during culm development. Elongation growth began in May and ended in late-June, when the lignin content was approximately half that in mature culms. Thioacidolysis analysis indicated that p-hydroxyphenyl units in lignin formed even at late stages of lignification. The syringyl/guaiacyl ratio varied during culm development. Various lignin precursors were detected in developing culms by liquid chromatography–mass spectrometry. The ferulic acid content decreased from May to June, indicating that ferulic acid was utilized in early stages of cell wall formation. Monolignol glucosides were detected at early stages of lignification, whereas the contents of monolignols, coniferaldehyde, sinapaldehyde, p-coumaric acid, and ferulic acid peaked at later stages of lignification. Therefore, lignin precursors may be supplied differentially during the lignification process. In August, the rate of lignification decreased, although the contents of various lignin precursors peaked, implying that the rate-limiting step in the cessation of lignification in bamboo is transport or polymerization of lignin precursors, rather than their biosynthesis.     

Estimation of heritability of vertebral number in chum salmon <Emphasis Type="Italic">Oncorhynchus keta</Emphasis>

Hereditary causes of variation in the vertebral number of chum salmon were analyzed to estimate heritability for populations in the Chitose and Shikiu Rivers, Hokkaido Island, northern Japan. A total of 70 families were produced by diallel cross mating and then heritability was estimated using two statistical tests: a two-way ANOVA and a parent-offspring regression. Heritability estimates ranged from 0.26 to 1.91 and showed a strong correlation between the values from the two different tests. Estimates from female components were substantially higher than those from male components, which can be attributed to the maternal effect. Heritability in the Shikiu River population was shown to be higher than that in the Chitose River population. These results indicate that the heritability of vertebral number in chum salmon is generally high, and also that vertebral number is controlled by hereditary causes.     

Mercury levels of small fishes: influence of size and catch area

In the present study, we assessed small fishes as potential feed fishes with the lowest mercury levels. The mercury levels of four small pelagic fishes and a benthic fish from the Pacific Ocean and the Sea of Japan, i.e., spotted chub mackerel Scomber australasicus, chub mackerel Scomber japonicus, horse mackerel Trachurus trachurus, round scad Decapterus punctatus, and bastard halibut Paralichthys olivaceus, were determined. Total mercury levels in fish muscle were measured using a reduction vaporizing atomic absorption method. There were no significant correlations between body weight and mercury levels for these species. However, significant differences were observed in the mercury levels of these species between the two catch locations, with fish caught in the Pacific Ocean having higher mercury levels. This difference may be due to the Pacific Ring of Fire, a highly seismically and volcanically active zone, which is located in the Pacific Ocean. Preference for these fishes for use in aquaculture should refer to the area where they are caught in addition to the species.     

The synthetic antioxidant, ethoxyquin, adversely affects immunity in tilapia (Oreochromis niloticus)

Ethoxyquin (EQ) has been used as an antioxidant in livestock, aquaculture and pet foods. Animal food safety law has established the upper limit of EQ in animal feed at 150 mg kg⁻¹. However, the risk of EQ at the approved level for aquaculture feed (150 mg kg⁻¹) to fish health is unknown. Here, we examine the effect of EQ on the immunity of tilapia ( Oreochromis niloticus ). EQ concentration in the blood reached 0.16 mg L⁻¹ in fish fed EQ at the approved level. This level of EQ inhibited phagocytic activity of leucocytes in vitro and antibacterial activity of whole blood in vivo . Furthermore, pyknosis in the liver was observed throughout the duration of feeding. However, after 30 days of experimental challenge with feed containing 150 mg kg⁻¹ of EQ, no significant difference was observed in mortality. Although EQ at the approved level in feed causes immunosuppression in fish, the severity of immunosuppression does not lead to a lowering of disease resistance for short feeding periods.     

Seroprevalence of antibodies against severe acute respiratory coronavirus 2 (SARS-CoV-2) in household dogs in Japan

We investigated the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among dogs in the Tokyo area via enzyme-linked immunosorbent assay (ELISA) using the spike protein as the target antigen. Plasma samples from 494 household dogs and blood-donor dogs were tested from July 2020 to January 2021. Of these samples, three showed optical densities that were higher than the mean plus two standard deviations of the mean of the negative-control optical densities (ODs). Of these three samples, only the sample with the highest OD by ELISA was confirmed positive by virus neutralization testing. The positive dog presented no SARS-CoV-2-related symptoms. The positivity rate of SARS-CoV-2 infections among dogs in the Tokyo area was approximately 0.2%.