Regolith migration and sorting on asteroid Itokawa

High-resolution images of the surface of asteroid Itokawa from the Hayabusa mission reveal it to be covered with unconsolidated millimeter-sized and larger gravels. Locations and morphologic characteristics of this gravel indicate that Itokawa has experienced considerable vibrations, which have triggered global-scale granular processes in its dry, vacuum, microgravity environment. These processes likely include granular convection, landslide-like granular migrations, and particle sorting, resulting in the segregation of the fine gravels into areas of potential lows. Granular processes become major resurfacing processes because of Itokawa's small size, implying that they can occur on other small asteroids should those have regolith.     

Detailed images of asteroid 25143 Itokawa from Hayabusa

Rendezvous of the Japanese spacecraft Hayabusa with the near-Earth asteroid 25143 Itokawa took place during the interval September through November 2005. The onboard camera imaged the solid surface of this tiny asteroid (535 meters by 294 meters by 209 meters) with a spatial resolution of 70 centimeters per pixel, revealing diverse surface morphologies. Unlike previously explored asteroids, the surface of Itokawa reveals both rough and smooth terrains. Craters generally show unclear morphologies. Numerous boulders on Itokawa's surface suggest a rubble-pile structure.     

A client/server architecture remote fish finder system for a set net fishery

In order to monitor the fish volume entrapped over time in a set net in real time, a new remote fish finder system based on a mobile network was developed and tested. This system was designed with a client/server architecture including an echo sounder terminal, a web server, and some end user display terminals, which allowed fishermen to monitor the fishing state of a set net via any display device. In addition, in order to transfer the echo data smoothly via a mobile network, a fish echo extraction method based on image processing and a data organization structure were proposed, which can significantly reduce the data volume for transmission, supply sufficient information to reconstruct the high resolution echogram at the user terminals, and calculate the positional and morphometric parameters of fish echoes. Furthermore, a semiautomatic data recording method for use with a database was proposed to manage the extracted fish echo data and the fishing records. The functions and capabilities of the new system were demonstrated by a sea trial.     

Quantitative analysis of <Emphasis Type="Italic">Ichthyobodo salmonis</Emphasis> an ectoparasitic flagellate infecting juvenile chum salmon <Emphasis Type="Italic">Oncorhynchus keta</Emphasis> in hatcheries

Ichthyobodosis caused by the ectoparasitic flagellate Ichthyobodo salmonis is a significant cause of mortality in juvenile chum salmon Oncorhynchus keta reared in hatcheries of northern Japan. The present study established a real-time quantitative polymerase chain reaction assay (qPCR) of I. salmonis ribosomal DNA (rDNA) using SYBR Green. This assay allows monitoring of parasite infections for the epidemiological study and control of ichthyobodosis in hatcheries. qPCR showed high reproducibility for measurements between 1.0 and 1.0 × 10⁸ rDNA copy/μl. There was a significant positive correlation between the number of parasites and the amount of I. salmonis rDNA. A survey using the qPCR assay indicated that infection by I. salmonis was present in 23 of 87 hatcheries; parasite loads were estimated to be between 50 and 750 parasites/g juvenile body weight. These results demonstrate that our qPCR assay enables the surveying of juvenile chum salmon reared in hatcheries for infection by I. salmonis.     

Comparison of biomass estimates from multiple stratification approaches in a swept area method for Pacific saury Cololabis saira in the western North Pacific

Fishery-independent surveys using sea surface trawl nets for Pacific saury Cololabis saira in the western North Pacific since 2003 have enabled the investigation of their annual distribution patterns and total biomass during June and July, prior to the main fishing season in Japan. We compared biomass estimates and their associated variances derived based on five different post-stratification approaches in a swept area method, and then observed that these approaches have little effect on biomass estimates and their precision, owing to well-organized survey designs and homogeneously allocated sampling stations. We were able to utilize decreasing biomass estimates for 15 years as an essential abundance index in the ongoing stock assessment. Notably, examination based on stratification along with longitudinal survey lines indicated that the estimated biomass had decreased in the western survey area, resulting in an eastward shift in the gravity center of Pacific saury distribution after 2010. We recommend biomass estimation in an east–west direction based on longitudinal stratification as an effective measure to develop population dynamics models which reflect westward migration into the fishing grounds around Japanese coastal waters, and to forecast the expected catch during the subsequent fishing period.

     

A cooperative action of endothelin-1 with prostaglandin F(2alpha) on luteal function in the cow

Prostaglandin F(2alpha) (PGF(2alpha)) is the primary luteolysin in the cow, and luteal endothelin-1 (ET-1) interacts with PGF(2alpha) during the process of luteolysis. In contrast, a developing corpus luteum (CL) is refractory to exogenous administration of PGF(2alpha). Thus, the present study was aimed to investigate the functional relationship between ET-1 and PGF(2alpha) in the mid-CL (PGF(2alpha)-sensitive) and early-CL (PGF(2alpha)-refractory). In the mid-CL model, cows (n = 6/treatment) were assigned to receive one of five types of treatments on day 10 of the estrous cycle: (1) an injection of saline; control, (2) a 500 microg of PGF(2alpha) analogue (sufficient dose to induce luteolytis); full-PG, (3) an intraluteal injection of 0.25 mg ET-1; ET-1, (4) a 125 micro g of PGF(2alpha) (insufficient dose to induce luteolytis); 1/4PG or (5) an intraluteal injection of 0.25 mg ET-1 after administration of a insufficient dose of PGF(2alpha) analogue; 1/4PG/ET. In the early-CL model, cows were assigned to receive one of two types of treatments on day 5 of the estrous cycle: (1) a sufficient dose of PGF(2alpha) analogue; PG (n = 5) or (2) an intraluteal injection ET-1 after a sufficient dose of PGF(2alpha); PG/ET (n = 7). In the mid-CL model, 1/4PG/ET resulted in a rapid reduction of progesterone (P) concentrations similar to that in full-PG from the next day. However, the levels of P in 1/4PG/ET (1.5-2.5 ng/ml) kept significantly higher than that in full-PG (< 0.5 ng/ml). ET-1 or 1/4PG did not decrease plasma P concentrations (4-6 ng/ml). The plasma ET-1 levels increased with the full-PG administration. In the early-CL model, both treatments had no effect on plasma P increase and ET-1 levels. The overall results indicate that the intraluteal ET-1 injection after administration of insufficient dose of PGF(2alpha) induces the depression of P secretion in vivo during the mid luteal phase in the cow, supporting the concept that ET-1 is one of a local mediator of functional luteolysis in the cow. The result further indicates that the early-CL is not only PG-refractory but also ET-1-refractory.     

Lymphography of the thoracic duct by percutaneous injection of iohexol into the popliteal lymph node of dogs: experimental study and clinical application

OBJECTIVE: To evaluate the efficacy of percutaneous administration of iohexol into the popliteal lymph node as a non-invasive technique for thoracic duct lymphangiography in dogs. STUDY DESIGN: Experimental study and clinical report. ANIMALS: Normal adult dogs (n=4) and 1 dog with recurrent chylothorax. METHODS: For the experimental study, 4 dogs (weight, 8.4-12.3 kg) had 5-10 mL iohexol injected percutaneously into 1 popliteal lymph node and then thoracic radiographs were taken. Popliteal lymph nodes were examined by histopathology 8 days later. One 25-kg dog with recurrent chylothorax had 25 mL iohexol injected into the right popliteal lymph node followed by thoracic radiography. RESULTS: In experimental dogs, the thoracic duct was best visualized on thoracic radiographs after administration of 10 mL iohexol. Clinically, no abnormalities were identified in the injected limb and except for 1 dog that had large numbers of siderocytes and erythrophagocytic macrophages in the injected lymph node, the histopathologic findings in the other injected popliteal lymph nodes were not different from contralateral nodes. In the clinical case, the thoracic duct was visualized, but there was leakage of iohexol around the node. CONCLUSION: The thoracic duct in dogs can be visualized by lymphography after percutaneous injection of iohexol (1 mL/kg at 2 mL/min) into the popliteal lymph node. CLINICAL RELEVANCE: Percutaneous popliteal lymph node administration of iohexol should be considered as an alternative to mesenteric lymph node injection for radiographic identification of the thoracic duct in dogs.     

Determination of Bovine Serum Low-density Lipoprotein Cholesterol using the N-geneous Method

The N-geneous method is a recently developed method for determination of low-density lipoprotein cholesterol (LDL-C) in human serum. In the present study, we attempted to adapt this method to bovine serum. The values of LDL-C obtained using the N-geneous method were highly correlated with those from the method using ultracentrifugation and heparin sepharose affinity chromatography (r = 0.934, p < 0.001). The reproducibility of this method was acceptable (intra-assay CV 4.2%, inter-assay CV 7.6%) for clinical use. Using the N-geneous method, serum LDL-C was evaluated in cows around parturition, and in cows with fatty liver induced by fasting. The concentration of LDL-C decreased significantly in cows close to parturition. A reduced concentration of LDL-C was also observed in cows with fatty liver. In both cases, the changes of LDL-C were similar to those of apolipoprotein B (apoB)-100, and the values of LDL-C were highly correlated (r = 0.876, p < 0.001) with those of apoB-100. These results suggest that the concentration of LDL-C reflects the level of apoB-100. The N-geneous method is simple and rapid, and might to be a useful tool to elucidate the clinical significance of LDL-C in bovine serum.     

Expression of mRNA for the angiopoietin-tie system in granulosa cells during follicular development in cows

Recent findings indicate that the changing profile of angiopoietins (ANPT) and their receptor Tie2 are closely associated with development and regression of the vascular network in the cyclic ovary. We previously reported that mRNA expression for the ANPT-Tie system in theca interna changes during bovine follicular development and atresia, and both ANPTs affect steroidogenesis in the preovulatory follicle. The aim of this study was to investigate mRNA expression for ANPT1, ANPT-2 and Tie2 in granulosa cells (GC) during follicular development in the cow. Bovine follicles were classified according to the estradiol-17beta (E(2)) concentration in follicular fluid (FF) as follows: (1) E(2)<0.5, (2) 0.5180 ng/ml FF. Semi-quantitative RT-PCR analysis revealed that the expression of ANPT-1 mRNA was not detected in most of the follicle with E(2)<5 ng/ml (diameter of 5-10 mm), but clearly detected in all follicles with E(2)>5 ng/ml (diameter of >10 mm). The mRNA expression for ANPT-2 was drastically decreased in the follicles with E(2)>5 ng/ml. Tie2 mRNA expression remained unchanged at the different stages of follicular development. The present data show that ANPT-1 becomes predominant in the follicle producing high levels of E(2), indicating the possible switch-over from ANPT-2 (antagonist) to ANPT-1 (agonist). Thus, the result suggests that the ANPT-Tie system in bovine GC may stimulate E(2) secretion rather than angiogenesis in the late stages of follicular development.