卤虫去壳卵在河蟹育苗中应用的研究

本文比较了卤虫去壳卵、无节幼体和人工合成饵料在河蟹育苗中■Ⅲ～■Ⅴ期的饵料效果,探讨了卤虫去壳卵替代无节幼体在河蟹育苗中应用的可能性。     

Low expression of mitofusin 1 is associated with mitochondrial dysfunction and apoptosis in porcine somatic cell nuclear transfer embryos

Mitochondria are necessary for the transition from oocyte to embryo and for early embryonic development. Mitofusin 1 is the main mediator of mitochondrial fusion and homeostasis. We investigated Mitofusin 1 expression levels in porcine somatic cell nuclear transfer (SCNT) embryos. The rate of blastocyst formation in SCNT embryos was reduced significantly compared with that of parthenogenetic activation embryos. SCNT embryos showed significantly decreased Mitofusin 1 expression and mitochondrial membrane potential, while exhibiting increased reactive oxygen species and apoptosis. Mitochondrial functional changes were observed in the SCNT embryos and may be correlated with low levels of Mitofusin 1 to negatively affect development.     

Effects of media,carbon sources and cytokinins on shoot organogenesis in the Christmas tree Scots pine (Pinus sylvestris L.)

Summary

Significant effects of seven basal media and three carbon sources (sucrose, glucose and fructose) on the induction of adventitious buds from embryos of Pinus sylvestris L. were observed. Moreover, hyperhydricity of expiants and shoot regenerants was observed on basal media containing fructose, especially with half-strength Murashige and Skoog (MS), MS, and woody plant medium (WPM). Expiants grown on a Gresshoff and Doy (GD) medium with sucrose produced the highest frequency of regeneration (81%) and with no hyperhydricity observed of developing adventitious shoots. Among three cytokinins tested including BA, BPA, and TDZ (at four concentrations each), 5 μM BA resulted in the highest regeneration frequency and mean number of adventitious shoots per embryo. Shoot régénérants were elongated after transfer to a GD medium containing 2 g-l_–1 activated charcoal and no growth regulators. After one month, rooting was induced on 10% of expiants.     

Introduction of normal preserving force into garment drape simulation for stable sewing process

A new force term for the particle based cloth drape simulation has been defined in this study. In the sewing process which is the starting point of a cloth drape simulation, usually large constraint forces are assigned along the sewing edges and this may generate a very stiff linear system which tends to diverge easily. Therefore, especially for a dynamic cloth simulation with a large time step, additional large damping should be introduced to stabilize the sewing process which slows down the process significantly. The new force term defined in this study was proved to be able to stabilize the sewing process without such a large damping by preserving the surface normal directions of mesh elements.     

Astrocytic purinergic signaling coordinates synaptic networks

To investigate the role of astrocytes in regulating synaptic transmission, we generated inducible transgenic mice that express a dominant-negative SNARE domain selectively in astrocytes to block the release of transmitters from these glial cells. By releasing adenosine triphosphate, which accumulates as adenosine, astrocytes tonically suppressed synaptic transmission, thereby enhancing the dynamic range for long-term potentiation and mediated activity-dependent, heterosynaptic depression. These results indicate that astrocytes are intricately linked in the regulation of synaptic strength and plasticity and provide a pathway for synaptic cross-talk.     

Determination of 2-6-diaminopimelic acid in samples of bacteria isolated from the rumen of sheep using an automatic amino acid analyzer

The method of the use of the HD 1200-E automatic amino acid analyzer for the separation of amino acids was modified for the determination of 2-6-diaminopimelic acid (DAPA) as a bacterial marker, besides the other amino acids in the acid hydrolyzates of samples of bacteria isolated from the rumen of sheep. The reproducibility of the determination of DAPA in a standard amino acid mixture found in the tests corresponded with the reproducibility of the determination of the other amino acids as indicated by the manufacturer of the apparatus. The lower limit of DAPA determination sensitivity is between 2 and 5 nmol. In samples of bacteria isolated from rumen wall, from feed particles of rumen contents and from rumen fluid, different contents of nitrogen and DAPA were obtained; this is ascribed to the different proportions of bacterial species in the bacterial populations having different functions.     

Crystallization of poly(vinylidene fluoride)-SiO2 hybrid composites prepared by a Sol-gel process

Organic-inorganic hybrid composites consisting of poly(vinylidene fluoride) (PVDF) and SiO₂ were prepared through a sol-gel process and the crystallization behavior of PVDF in the presence of SiO₂ networks was investigated by spectroscopic, thermal and x-ray diffraction measurements. The hybrid composites obtained were relatively transparent, and brittleness increased with increasing content of tetraethoxysilane (TEOS). It was regarded from FT-IR and DSC thermal analyses that at least a certain interaction existed between PVDF molecules and the SiO₂ networks. X-ray diffraction measurements showed that all of the hybrid samples had a crystal structure of PVDFγ-phase. Fresh gel prepared from the sol-gel reaction showed a very weak x-ray diffraction peak near 2θ=21° due to PVDF crystallization, and intensity increased gradually with time after gelation. The crystallization behavior of PVDF was strongly affected by the amount of SiO₂ networks. That is, SiO₂ content directly influenced preference and disturbance for crystallization. In polymer-rich hybrids, SiO₂ networks had a favorable effect on the extent of PVDF crystallization. In particular, the maximum percent crystallinity of PVDF occurred at the content of 3.7 wt% SiO₂ and was higher than that of pure PVDF. However, beyond about 10 wt% SiO₂, the crystallization of PVDF was strongly confined.