Effect of hinoki (Chamaecyparis obtusa) wood-wool in tatami mat on the activity of house dust mite Dermatophagoides pteronyssinus

To suppress the activity of house dust mites in tatami mats, where they tend to breed, a tatami mat consisting of hinoki (Chamaecyparis obtuse) wood-wool was prepared. The suppressive effect of hinoki wood-wool on house dust mites (Dermatophagoides pteronyssinus) was then measured. To investigate the effective period of the wood-wool on the mites, 5-day exposure tests were conducted every few weeks for a total of 52 weeks. In the tests of the first and sixth weeks, the activity of the mites was strongly suppressed, and no walking or moving mite was found after 5 days of exposure. The suppressive effect on mites was maintained for 52 weeks. It was concluded that using hinoki wood-wool to produce tatami mats is an effective method of suppressing the activity of mites for about 1 year.     

Mortality of Northern Bluefin Tuna Thunnus thynnus Due to Trauma Caused by Collision During Growout Culture

Abstract.— Indoor and outdoor experiments were conducted to improve the rearing techniques for artificially hatched northern bluefin tuna Thunnus thynnus during growout culture. Collisions with the walls of tanks or nets caused mass mortality that occurs during growout. The period when collisions frequently occur and the types of injury caused by collision were examined in this study. Juveniles were reared in indoor tanks from 30 to 120 d after hatching, and in an open sea net cage from 42 to 150 d after hatching. Dead fish were collected and counted daily in both of the experiments. In the indoor experiment, the sampled fish were preserved in 10% formalin solution, and each of 10 specimens of about 30, 50, 70, 85, 100, 130, 160 and 225 mm in body length (BL) were examined using x‐rays to detect injury of the bones. Juvenile and young adult bluefin tuna showed a reduction in numbers caused by collision with the tank or the net wall during the experiments. In the indoor tank, there were 1,200 fish on day 30 but only eight on day 120. The daily mortality increased from day 30 after hatching, when juveniles reached 50‐mm BL and remained over 4%/d until day 60 when juveniles grew to 300‐mm BL. The proportion of dead fish with injuries of bone, especially of the vertebral column and the parasphenoid, increased after fish reached 50‐mm BL, and exceeded 60% in fish with BL 85 mm or greater. In the open sea net cage, there were 3,841 fish at the start of the experiment on day 42 and only 65 on day 150. In this experiment, the reduction was greatest from the start of the experiment until day 80, when fish grew to approximately 25 cm in total length. Significant bacterial, viral or parasitic diseases were not observed in these fish; the only findings were dislocations of the vertebral column and injuries to the upper and lower jaws. These results show that the loss of juvenile and young adult bluefin tuna was caused by collision with the tank or net wall that fatally damaged the bones of the vertebral columns and the parasphenoid.     

Host cholesterol synthesis contributes to growth of intracellular Toxoplasma gondii in macrophages

The intracellular protozoan Toxoplasma gondii lacks the ability to synthesize sterol and scavenges cholesterol from the low-density lipoprotein receptor (LDLR) pathway of its host to facilitate replication. Sterol biosynthesis inhibitors, however, have a demonstrated anti-Toxoplasma effect. In this study, we examined the host mevalonate pathway as a novel source of cholesterol for T. gondii and its effects on parasite growth in macrophages. Parasite growth did not significantly change in the absence of LDLR or when LDL was exogenously supplemented. Lovastatin and compactin, both inhibitors of hydroxymethylglutaryl-CoA (HMG-CoA) reductase in the mevalonate pathway, significantly inhibited T. gondii growth in both wild-type and LDLR-knockout macrophages. Parasite growth was also suppressed by squalestatin, an inhibitor of squalene synthase, despite mevalonate producing isoprenoid intermediates in host cells. The present study demonstrates that lovastatin, compactin and squalestatin have anti-Toxoplasma activities and that the host cholesterol synthesis may contribute to parasite growth in macrophages.     

Malignant glomus tumour in a German shepherd dog

A solitary mass, 2.5 cm × 2.5 cm × 2.0 cm in size, was found in the subcutis adjacent to the ischial tuberosity of an 8-year-old male German shepherd dog. The excised mass was not encapsulated and the cut surface was solid, grey–white and had multiple red areas suggestive of haemorrhage. Microscopically, the neoplasm was composed of epithelioid cells interspersed with venous vessels of various sizes and irregular bundles of spindle-shaped tumour cells with mucinous stroma. The nuclei showed anisokaryosis and many mitotic figures were noted. Immunohistochemically, the majority of tumour cells were positive for alpha smooth-muscle actin and vimentin, but negative for cytokeratin, desmin, S-100 and factor VIII-related antigen. Ultrastructurally, the tumour cells contained irregular nuclei, few mitochondria, few rough endoplasmic reticulum, cytoplasmic myofilaments of intermediate density, pinocytotic vesicles and distinct basal lamina. Based on these pathological findings, the diagnosis was malignant glomus tumour.     

中国云南省滇池盆地东南区由于土地利用方式的变化（从水田变为旱地或温室土壤）导致土壤理化性质的变化研究

Paddy fields in the southeastern basin of Dianchi Lake have rapidly changed to greenhouses since 1999. A total of 61 surface soil samples, including 43 greenhouse soils, 12 upland soils, and 6 paddy soils, were collected from a flat lowland area mainly used for agricultural production fields in the southeastern basin of Dianchi Lake. Analyses of the soil samples indicated that the greenhouse soils were characterized by a lower organic matter content, lower pH, and higher soluble nutrients than the paddy soils in the area. The lower organic matter content of the greenhouse soils was ascribed to environmental or management factors rather than the clay content of the soil. Accumulation of soluble nutrients, especially inorganic N, was due to over-application of fertilizers, which also caused soil acidification. The average amount of readily available N, P, and K accumulated in the greenhouse soils was estimated to be equal to or higher than the annual input of these nutrients as a fertilizer, indicating that a reduction in fertilizer application was possible and recommended. In contrast, a very low available Si content was observed in the paddy soils, suggesting the need for Si application for rice production.     

Hypoxic conditions induce centrum defects in red sea bream Pagrus major (Temminck and Schlegel)

A previous study elucidated that an extreme hypoxia during somitogenesis induced the most frequent skeletal malformation centrum defects in red sea bream (RSB), Pagrus major. In this study, details of the hypoxic conditions to induce them in RSB, dissolved oxygen (DO) concentration and exposure time to hypoxia, were investigated. Fertilized eggs were exposed to seawater of six DO concentrations (0%, 10%, 25%, 50%, 75% and 100% of saturation) for seven different periods (5, 10, 30, 60, 120, 240 and 360 min) during somitogenesis. Somitic disturbances in newly hatched larvae were induced by exposure to 0% and 10% DO concentration for 10 and 120 min and longer respectively. Rearing eggs exposed to hypoxic condition of 10% DO for 240 min for 40 days post‐hatch showed that the location and the frequency of somitic disturbances in larvae and centrum defects in juveniles were significantly correlated (P<0.01). Dissolved oxygen concentration of the interstitial water in the egg high density layer formed at the water surface in a stationary state abruptly decreased to 3.7% within 7 min. Centrum defect induction by exposure of eggs to extreme low DO concentrations for a short period, which is the probable situation in the practical juvenile production, suggests that careful maintenance of DO concentration is important in the incubating water of fertilized eggs during egg sorting and transportation, where eggs are made into a pile and undergo hypoxia, for the prevention of centrum defects.     

Changes in the scotopic vision of juvenile Pacific bluefin tuna (Thunnus orientalis) with growth

In cultured juvenile Pacific bluefin tuna (Thunnus orientalis), reducing the mass deaths caused by collision or contact with tank or net walls at night is a priority for seedling production. Pacific bluefin tuna is a visually dependant species, although its scotopic vision is poor. We recorded electroretinograms to investigate the visual function with growth in the dark-adapted eyes of juvenile Pacific bluefin tuna. Peak wavelengths of spectral sensitivity [38–62 days posthatch (dph), 77–167 mm standard length (SL)] were observed between 474 and 494 nm. Visual light sensitivity has a tendency to increase slightly with growth at 28–64 dph in individuals that measured 29–175 mm SL. However, visual temporal resolution did not significantly increase with growth at 38–62 days dph in individuals that measured 77–167 mm SL. These results suggest that the mass death continues between 28 and 64 dph because of low visual function and increasing swimming speed with growth.     

Oxygen deficiency during somitogenesis causes centrum defects in red sea bream, Pagrus major (Temminck et Schlegel)

Vertebral deformities in red sea bream, Pagrus major, remain serious obstacles to the improvement of seedling quality for its aquaculture. However, the causalities of the deformities remain unclear and prevention methods have not yet been established. In this paper, oxygen deficiency during somitogenesis was demonstrated to cause centrum defects (formerly called fused vertebrae in many cases), which are the major vertebral deformity in cultured red sea bream. An induction experiment of centrum defects was conducted by placing fertilized red sea bream eggs under low dissolved oxygen conditions (10.3–16.6%). The low oxygen treatment was carried out for five different developmental stages of embryo: two‐cell stage to blastula stage; gastrula stage; three to 10 somites stage; 11–17 somites stage and 18–24 somites stage. Oxygen deficiency during somitogenesis induced a high incidence of centrum defects. In contrast, it hardly induced centrum defects during the other stages. The dissolved oxygen concentration in the rearing water should be carefully regulated for fertilized eggs, especially during somitogenesis to reduce the incidence of vertebral deformities in the red sea bream.