Characterization of thraustochytrid-specific sterol O-acyltransferase: modification of DGAT2-like enzyme to increase the sterol production in Aurantiochytrium limacinum mh0186

IMPORTANCE

Since the global market for sterols and vitamin D are grown with a high compound annual growth rate, a sustainable source of these compounds is required to keep up with the increasing demand. Thraustochytrid is a marine oleaginous microorganism that can synthesize several sterols, which are stored as SE in lipid droplets. DGAT2C is an unconventional SE synthase specific to thraustochytrids. Although the primary structure of DGAT2C shows high similarities with that of DGAT, DGAT2C utilizes sterol as an acceptor substrate instead of diacylglycerol. In this study, we examined more detailed enzymatic properties, intracellular localization, and structure-activity relationship of DGAT2C. Furthermore, we successfully developed a method to increase sterol and provitamin D3 productivity of thraustochytrid by more than threefold in the process of elucidating the function of the DGAT2C-specific N-terminal region. Our findings could lead to sustainable sterol and vitamin D production using thraustochytrid.

MODIFIED GUTH–GOLD EQUATION FOR CARBON BLACK–FILLED RUBBERS

The modulus increase in rubbers filled with solid particles is investigated in detail here using an approach known widely as the Guth–Gold equation. The Guth–Gold equation for the modulus increase at small strains was reexamined using six different species of carbon black (Printex, super abrasion furnace, intermediate SAF, high abrasion furnace, fine thermal, and medium thermal carbon blacks) together with model experiments using steel rods and carbon nanotubes. The Guth–Gold equation is only applicable to such systems where the mutual interaction between particles is very weak and thus they behave independently of each other. In real carbon black–filled rubbers, however, carbon particles or aggregates are connected to each other to form network structures, which can even conduct electricity when the filler volume fraction exceeds the percolation threshold. In the real systems, the modulus increase due to the rigid filler deviates from the Guth–Gold equation even at a small volume fraction of the filler of 0.05–0.1, the deviation being significantly greater at higher volume fractions. The authors propose a modified Guth–Gold equation for carbon black–filled rubbers by adding a third power of the volume fraction of the blacks to the equation, which shows a good agreement with the experimental modulus increase (G/G0) for six species of carbon black–filled rubbers, where G and G0 are the modulus of the filled and unfilled rubbers, respectively; ϕeff is the effective volume fraction; and S is the Brunauer, Emmett, Teller surface area of the blacks. The modified Guth–Gold equation indicates that the specific surface volume ()3 closely relates to the bound rubber surrounding the carbon particles, and therefore this governs the reinforcing structures and the level of the reinforcement in carbon black–filled rubbers.

FEA MODELING OF SCHALLAMACH WAVES

The term Schallamach wave is used to describe a wave of detachment that sometimes arises during the frictional sliding of a smooth rubber surface against a smooth rigid surface. Extensive experimental investigations have been made since Schallamach first observed the waves in 1971; however, no successful finite element analysis (FEA) modeling of the behavior has been reported yet. This work uses an explicit dynamics FEA approach to model both the initiation and progression of waves of detachment for the first time. The use of the finite element method allows for the detailed stress and strain analysis at the interface to be examined. Here, the limitations of using a purely elastic solution in plane-strain are explored. To validate the explicit dynamics approach for modeling the Schallamach waves, another biaxial compressive buckling mode has also been modeled.

Recycled Rubber: The Rubber Granulate - Virgin Rubber Interface

Reusing granulates derived from old tire stock and other sources in high tech engineering applications is still considered a high risk option. In addition to ensuring that the granulates are correctly identified, it is important to know how the incorporation of these materials alters the intrinsic flaw size of a finished product and to see how much the strength of the interface between these materials and the virgin materials compares to the basic strength of the virgin stock and the granulates. This paper explores possible techniques that can examine both properties so that an informed evaluation of the effect of reincorporating granulates can be established in practice.

Anatomic considerations of the peroneal nerve for division of the fibula during high tibial osteotomy

Twenty legs in 10 cadavers were dissected to determine the course of the deep peroneal nerve from its origin to its termination. Particular attention was paid to defining: (1) its relationship to palpable landmarks, (2) the angle of the course of its proximal portion against the long axis of the fibula, (3) distribution of the proximal branch to the extensor hallucis longus muscle, and (4) safe areas of osteotomy in the proximal fibula during high tibial osteotomy. The extensor hallucis longus was often supplied by only one branch from the deep peroneal nerve at 99.8 mm (31.7%) distally from the apex of the fibula; this seems to explain why osteotomy of the fibula at its proximal one third often causes paralysis of this muscle. The findings suggest that safe areas for osteotomy in the proximal fibula during high tibial osteotomy are located up to 20.5 mm (6.5%) distal to the tip of the fibular head and that the safe angle of a periosteal incision against the fibular neck area is 64.1 degrees.

[Serological evaluation of human T lymphotropic virus type-I infection in routine hospital samples, especially using serodia.HTLV-I]

Particle agglutination (PA; Serodia-ATLA) and ELISA (Ei-test ATL) assays have been used as routine anti-HTLV-I antibody detection in Japan. However, inconsistent results were obtained by the above methods. We wished to develop criteria for serological confirmation of HTLV-I infection in Hospital samples. Sera obtained in our Hospital from October, 1988 to September, 1989 were tested by five methods of PA (Serodia-ATLA), new PA (improved on the PA; Serodia.HTLV-I), ELISA-I (coated by HTLV-I infected cell lysates as antigens; Ei-test ATL), ELISA-II (coated by recombinant gag-env hybrid proteins as antigens) and IF. The HTLV-I seropositive rates using five methods were not different, ranged from 29.7 to 32.3% in 155 sera. However, PA assays appeared more false positive and rare false negative in some high titer sera. 13 sera as demonstrated negative for ELISA-I and positive for PA (ELISA-I(-)/PA(+] were reevaluated. As results, the antibody were confirmed in only 3 by new PA, 1 by ELISA-II and 2 cases by IF, respectively. On the other hand, 2 by new PA, 4 by ELISA-II and 2 by IF in 18 sera with ELISA-I(+)/PA(-) were interpreted as positive. Therefore, new PA is a remarkable improvement on the PA current model.