Functional Analysis of Lysosomes During Mouse Preimplantation Embryo Development

Lysosomes are acidic and highly dynamic organelles that are essential for macromolecule degradation and many other cellular functions. However, little is known about lysosomal function during early embryogenesis. Here, we found that the number of lysosomes increased after fertilization. Lysosomes were abundant during mouse preimplantation development until the morula stage, but their numbers decreased slightly in blastocysts. Consistently, the protein expression level of mature cathepsins B and D was high from the one-cell to morula stages but low in the blastocyst stage. One-cell embryos injected with siRNAs targeted to both lysosome-associated membrane protein 1 and 2 (LAMP1 and LAMP2) were developmentally arrested at the two-cell stage. Pharmacological inhibition of lysosomes also caused developmental retardation, resulting in accumulation of lipofuscin. Our findings highlight the functional changes in lysosomes in mouse preimplantation embryos.     

Physicochemical and morphological properties of termite (Macrotermes bellicosus) mounds and surrounding pedons on a toposequence of an inland valley in the southern Guinea savanna zone of Nigeria

Termites play a significant role in soil-forming processes of the tropics. The influence of termites on pedogenesis as affected by the toposequence, however, has rarely been explored. We investigated the soil physicochemical and morphological characteristics of epigeal mounds constructed by Macrotermes bellicosus (Smethman) compared with those of surrounding pedons along a toposequence (bottom, fringe and upland sites) of an inland valley in central Nigeria. The physicochemical and morphological properties of the mound soils varied according to structural units but were generally different from those of the adjacent pedons. The differences included finer texture, higher electrical conductivity, total N, exchangeable bases (Ca, Mg and K) and effective cation exchange capacity and lower C/N ratio and exchange acidity in the mound than the pedon at each toposequence position. This tendency to modify the soil properties was more prominent in the nest body where the termites actually live, that is, in the hives, royal cell and base-plate, than in the soils below the nest and the other mound parts, that is, the external wall, internal wall and pillars. We found this trend to a greater or lesser degree at all toposequence positions. Our findings suggest that: (1) M. bellicosus can manipulate the mound soils according to functional applications of structure units or environmental requirements for its livelihood, regardless of local soils; (2) M. bellicosus makes ecological patches (hot spots) at all toposequence positions in the same measure; (3) the influence of M. bellicosus on the pedogenesis is reduced in the lowlands compared with the uplands because the number and volume of the mounds were substantially lower in the bottom and fringe sites compared with the upland site.     

Screening of cultivated and wild adzuki bean for resistance to race 3 of <Emphasis Type="Italic">Cadophora gregata</Emphasis> f. sp. <Emphasis Type="Italic">adzukicola</Emphasis>, cause of brown stem rot

Two diseases of adzuki bean, brown stem rot (BSR, caused by Cadophora gregata f. sp. adzukicola) and adzuki bean Fusarium wilt (AFW, caused by Fusarium oxysporum f. sp. adzukicola), are serious problems in Hokkaido and have been controlled using cultivars with multiple resistance. However, because a new race of BSR, designated race 3, was identified, sources of parental adzuki bean for resistance to race 3 were needed. Therefore, we examined 67 cultivars and lines of cultivated and wild adzuki bean maintained at the Tokachi Agricultural Experiment Station using a root-dip inoculation method. Consequently, nine adzuki bean cultivars, one wild adzuki bean accession and 30 lines (including two lines resistant to all the three races of BSR and AFW) were confirmed to be resistant or tolerant to race 3 of BSR, and we found a cultivar Akamame as well as a wild adzuki bean Acc2515 to be a new source for a resistance gene to the race 3. This cultivar also holds promise as a source of resistance against other races of BSR and AFW.     

Genetic population structure of the Pacific bluefin tuna Thunnus orientalis and the yellowfin tuna Thunnus albacares in the North Pacific Ocean

The genetic population structure of the Pacific bluefin tuna (PBF) Thunnus orientalis and the yellowfin tuna (YFT) T. albacares in the North Pacific Ocean was investigated. The polymorphism of microsatellite (SSR) loci and sequences of mitochondrial DNA control region (mtCR) were analyzed for 71 samples of PBF from Japan and Mexico and 45 samples of YFT from Japan and Panama. In the SSR analyses, both single-locus (?0.010 to 0.008 in PBF and ?0.023 to 0.020 in YFT) and global multilocus (0.003 in PBF and ?0.002 in YFT) F _ST values among the geographic populations were low and not significant in these species. In the mtCR analyses, neither the neighbor-joining tree nor the minimum spanning network showed genetic differentiation among the geographic populations in each species. The pairwise F _ST values among the geographic populations of them (?0.005 in PBF and ?0.020 to ?0.014 in YFT) were low and not significant. Our SSR and mtCR data suggested that genetic differentiations were not evident among the eastern and western populations in the North Pacific Ocean either in PBF or in YFT. Mismatch distributions, demographic parameters, and neutrality tests suggested that sudden population expansion of PBF and YFT in the North Pacific Ocean occurred 628,000–731,000 and 450,000–525,000 years ago, respectively.     

Effects of dietary heme iron and exercise training on abdominal fat accumulation and lipid metabolism in high‐fat diet‐fed mice

Animal by‐products can be recycled and used as sources of essential nutrients. Water‐soluble heme iron (WSHI), a functional food additive for supplementing iron, is produced by processing animal blood. In this study, we investigated the effects of dietary supplementation of 3% WSHI and exercise training for 4 weeks on the accumulation of abdominal fat and lipid metabolism in mice fed high‐fat diet. Exercise‐trained mice had significantly less perirenal adipose tissue, whereas WSHI‐fed mice tended to have less epididymal adipose tissue. In addition, total weight of abdominal adipose tissues was significantly decreased in the Exercise + WSHI group. Dietary WSHI significantly increased the messenger RNA (mRNA) levels of lipoprotein lipase and hormone‐sensitive lipase. WSHI‐fed mice also tended to show increased mRNA levels of adipose triglyceride lipase in their epididymal adipose tissue. Dietary WSHI also significantly decreased the mRNA levels of fatty acid oxidation‐related enzymes in the liver, but did not influence levels in the Gastrocnemius muscle. Exercise training did not influence the mRNA levels of lipid metabolism‐related enzymes in the epididymal adipose tissue, liver or the Gastrocnemius muscle. These findings suggest that the accumulation of abdominal fat can be efficiently decreased by the combination of dietary WSHI and exercise training in mice fed high‐fat diet.     

Transmission of <Emphasis Type="Italic">Tomato chlorotic dwarf viroid</Emphasis> by bumblebees (<Emphasis Type="Italic">Bombus ignitus</Emphasis>) in tomato plants

Quantitative PCR revealed that Tomato chlorotic dwarf viroid (TCDVd) was present in substantial amounts in viroid-infected tomato flowers. Healthy tomato plants were arranged in two different glasshouses, and plants were mechanically inoculated with TCDVd. Bumblebees (Bombus ignitus) were then introduced into the glasshouses to reveal whether the viroid was transmitted from infected source plants to neighbouring healthy plants. TCDVd infection was found in neighbouring tomato plants more than 1 month after the introduction of the bees, some of which expressed symptoms, in both glasshouses. Thus, bumblebees transmitted TCDVd from tomato to tomato by pollination activities.     

Genetic characterization of chicken anemia viruses newly isolated from diseased chicks in Japan in 2020

In this study, a total of nine chicken samples obtained from two broiler flocks in Oita and Tottori prefectures in 2020 were examined for Chicken anemia virus (CAV) infection. The samples were collected from clinically suspected flocks and diseased chickens. The CAV genome was detected in all nine samples tested by real-time PCR. Phylogenetic analyses and sequence comparisons of the full-length VP1 gene sequences indicated that all the Japanese CAV strains obtained in this study formed a similar cluster of genotype III and shared high nucleotide (99.62–100%) identity. The current Japanese CAV strains were closely related to Chinese CAV strains but not related to vaccine strains. One positive selection site of VP1 was detected among the Japanese CAV strains.