Lipid characterization and 14C-acetate metabolism in catfish taste epithelium

The catfish, Ictalurus punctatus is an important model system for the study of the biochemical mechanisms of taste reception. A detailed lipid analysis of epithelial tissue from the taste organ (barbel) of the catfish has been performed. Polar lipids account for 62 +/- 1% of the total, neutrals for 38 +/- 1%. Phosphatidyl-cholines, serines and ethanolamines are the major constituents of the polar fraction. Plasmalogen concentration is high relative to that of non-neural tissues. [14C]-Acetate is incorporated into cell lipid fractions after incubation of barbel tissue at 37 degrees C for 60 min. Percentage amounts of most lipids change with time during this in vitro incubation. The phospholipids are the most metabolically active fractions. This work yields information for continuing reconstitution experiments and indicates that the taste epithelium of this important model system is a metabolically active tissue capable of supporting lipid turnover/synthesis.     

Computer-Aided Detection System on Tangled Roller

Introduction Intheposttreatmentofchoppedfibreproduction,the thirddraftingrollerandtensionheat settingrolleroftenwere tangledbybrokentowforthereasonofhighspeed,hightemperatureofrollersurface,orotheradditionalforeign factors.While,thetworollerswerekeysegmentinthewhole technology.Itwouldleadtooneormoredrumcavedin,and eventobediscardediftheequipmenthadnotbeenstoppedintime.Usually,suchaccidentwouldbringgreatloss,what wouldnotbegotback.Sothetotalsetofequipmentrequiredthatdetectormusthavegoodperfo…     

Assembly of microtubules from nucleotide-depleted tubulin

In vitro assembly of microtubules from tubulin is considered to have an absolute requirement for added GTP (or a non-hydrolysable GTP-analogue) involving binding at the E(exchangeable)-site located on the beta-subunit of the tubulin dimer. By contrast, GDP inhibits assembly. Nucleotide hydrolysis has been implicated in the dynamic properties of microtubules, treadmilling and mechanical coupling. Here we demonstrate that assembly is not necessarily dependent on the presence of GTP at the E-site; microtubules can be formed efficiently in the absence of GTP in the presence of pyrophosphate. These microtubules, which have normal morphology and lability at cold temperatures, contain N(non-exchangeable)-site GTP and a significant proportion of E-site GDP. This demonstrates the possibility of direct incorporation of GDP-containing tubulin dimer during assembly which probably derives from microtubule-associated protein (MAP)-containing oligomers. This finding has important implications for the mechanism of microtubule elongation. The effects of pyrophosphate suggest that charge neutralization by the bidentate ligand is an essential step in promoting microtubule assembly, and that this interaction involves only a minimal conformational change in the protein.     

计算机辅助鉴定技术在海洋浮游植物分类鉴定中的应用

本文对计算机辅助鉴定技术在海洋浮游植物分类鉴定中的应用进行了探讨,总结了不同技术的特点,并在总结计算机辅助鉴定技术在海洋浮游植物分类鉴定方面应用现状的基础上,对其发展前景做出了展望。     

A mirror-symmetric cell division that orchestrates neuroepithelial morphogenesis

The development of cell polarity is an essential prerequisite for tissue morphogenesis during embryogenesis, particularly in the development of epithelia. In addition, oriented cell division can have a powerful influence on tissue morphogenesis. Here we identify a novel mode of polarized cell division that generates pairs of neural progenitors with mirror-symmetric polarity in the developing zebrafish neural tube and has dramatic consequences for the organization of embryonic tissue. We show that during neural rod formation the polarity protein Pard3 is localized to the cleavage furrow of dividing progenitors, and then mirror-symmetrically inherited by the two daughter cells. This allows the daughter cells to integrate into opposite sides of the developing neural tube. Furthermore, these mirror-symmetric divisions have powerful morphogenetic influence: when forced to occur in ectopic locations during neurulation, they orchestrate the development of mirror-image pattern formation and the consequent generation of ectopic neural tubes.     

Lipid characterization and14C-acetate metabolism in catfish taste epithelium

Summary The catfish,Ictalurus punctatus is an important model system for the study of the biochemical mechanisms of taste reception. A detailed lipid analysis of epithelial tissue from the taste organ (barbel) of the catfish has been performed. Polar lipids account for 62±1% of the total, neutrals for 38±1%. Phosphatidyl-cholines, serines and ethanolamines are the major constitutents of the polar fraction. Plasmalogen concentration is high relative to that of non-neural tissues. [¹⁴C]-Acetate is incorporated into cell lipid fractions after incubation of barbel tissue at 37°C for 60 min. Percentage amounts of most lipids change with time during this in vitro incubation. The phospholipids are the most metabolically active fractions. This work yields information for continuing reconstitution experiments and indicates that the taste epithelium of this important model system is a metabolically active tissue capable of supporting lipid turnover/synthesis.This work was supported in part by NIH Research Grant No. NS-23622, NS-22620, and by the Veterans Administration.