Novel p-coumaric acid esters from Pinus densiflora pollen

Solvent-extractable lipids in Pinus densiflora pollen were investigated. The cis- and trans-isomers of 1,16-dioxo-, 1-hydroxy-16-oxo- and 1, 16-dihydroxyhexadecan-7-yl p-coumarates were identified.     

Trichoclin,a new furocoumarin from trichocline incana

The structure for trichoclin, (E)-8-(3-methyl-4-hydroxy-2-butenyloxy)-psoralen, a new furocoumarin isolated from Trichocline incana, has been established. Phellopterin and isopimpinellin were also obtained. The new side chain of trichoclin was confirmed by synthesis.     

Evolution of the nucleotide sequence of influenza virus RNA segment 7 during drift of the H3N2 subtype

The complete genetic information contained in the influenza virus RNA segment 7 of the A/Bangkok/ $\text{1}\text{79}$ (H3N2) strain has been cloned by in vitro synthesis of the complementary dsDNA and its insertion into plasmid pBR322. The nucleotide sequence of the viral RNA segment has been determined from the cDNA insert. It is 1027 nucleotides long, and contains two open reading frames, as shown for other influenza virus strains. When compared with the previously published sequence for the A/Udorn/72 (H3N2) strain, 15 nucleotide exchanges are observed, most of them silent mutations, and only two causing amino acid changes in each of the M1 and M2 protein sequences.     

Early events in calcium-induced liposome fusion

Calcium-induced interaction of liposomes composed of pure phosphatidylserine (PS) has been studied using a rapid-mixing, rapid-freeze device. Freeze-fracture electron microscopy of this material revealed that liposomes react very rapidly after addition of calcium ions. After only 10 ms (the resolution of the technique) vesicle fusion was apparent. At the same time, however, vesicles also collapsed, and appeared as aggregates of flattened membranes. This may explain controversies which have arisen over vesicle fusion studied with more indirect methods.     

土牛膝碱（abidenine）的分离及结构测定

从土牛膝(Achyraanthes bidentata Bl.)的根中分离到一种新的生物碱——土牛膝碱(ubidenine),通过波谱方法测定出土牛膝碱的化学结构为5,6—二氢化—2,3,10,11—四甲氧基—二苯并[a,g]—喹嗪盐(1)。     

Fast sampling,rapid filtration apparatus: Principal characteristics and validation from studies ofd-glucose transport in human jejunal brush-border membrane vesicles

Summary Kinetic data in (brush-border) membrane vesicles which rely on the validity of the initial rate assumption for their interpretation and depend on tracer flux studies using the rapid filtration technique for their experimental measurement have been limited to some extent by the absence of techniques that would allow for real-time data analysis. In this paper, we report on our successful design of a fast sampling, rapid filtration apparatus (FSRFA) which seems to fill up this technical gap since showing the following characteristics: (i) rapid injection (5 msec) and mixing (less than 100 msec) of small amounts of vesicles (10–40 l) with an incubation medium (0.2–1.0 ml); (ii) fast (20 to 80 msec depending on the sample volume) and multiple (up to 18 samples at a maximal rate of 4/sec) sampling of the uptake mixture followed by rapid quenching in the stop solution (approximately 5 msec) according to a predetermined time schedule (any time combination from 0.25 to 9999 sec); and (iii) fast, automated, and sampling-synchronized filtration and washings of the quenched uptake medium (only 15–20 sec are necessary for the first filtration followed by two washings and extra filtrations). As demonstrated using adult human jejunal brush-border membrane vesicles and Na⁺-d-glucose cotransport as models, the FSRFA accurately reproduces the manual aspects of the rapid filtration technique while allowing for very precise initial rate determinations. Moreover, the FSRFA has also been designed to provide as much versatility as possible and, in its present version, allows for a very precise control of the incubation temperature and also permits a few efflux protocols to be performed. Finally, its modular design, which separates the fast sampling unit from the rapid filtration device, should help in extending its use to fields other than transport measurement.     

The molecular evolution of ZFY-related genes in birds and mammals

Summary We report the isolation and nucleotide sequence determination of clones derived from five ZFY-related zinc-finger genes from birds and mammals. These sequences are analyzed with reference to the previously published human genes, ZFX and ZFY, and mouse genes, Zfx, Zfa, Zfy-1, and Zfy-2. The analysis indicates that ZFY-related genes are highly conserved in birds and mammals, and that the rate of nucleotide substitution in the Y-linked genes is not as high as predicted. However, the mouse Zfy-1 and Zfy-2 genes are markedly divergent members of the ZFY gene family; we suggest this relates to X-inactivation of the mouse gene Zfx.     

Sex Determination in Caenorhabditis elegans

In Caenorhabditis elegans, the decision to develop as a hermaphrodite or male is controlled by a cascade of regulatory genes. These genes and other tissue-specific regulatory genes also control sexual fate in the hermaphrodite germline, which makes sperm first and then oocytes. In this review, we summarize the genetic and molecular characterization of these genes and speculate how they mutually interact to specify sexual fate.     

Seasonality and the scheduling of life history at different latitudes

For many ectotherms, the annual cycle is partitioned into 'growing' (summer) and 'non-growing' (winter) seasons, and the lengths of these seasons are inversely related across a latitudinal gradient. This pattern of variation has the potential to affect diverse life-history traits profoundly. A key selective agent is size-dependent winter mortality which, with increasing latitude, places an increasing premium on attainment of large body size before the first winter of life. Winter body size is determined primarily by two factors: (1) birth date, which defines the beginning of the first growing season and (2) somatic growth rate within the first season. Using examples drawn from the Atlantic silverside, Menidia menidia (L.), and other fishes, I show how latitudinal variation in the scheduling of the spawning season, countergradient variation in the capacity for growth and reproduction, and mode of sex determination (environmental v. genetic) represent adaptations to seasonality.     

Rapid determination of plasmid-carrying yeast cells by using an imaging sensor system

A novel imaging sensor system for the determination of plasmid carrying yeast cells was developed. The sensor system consisted of an Silicon Intensifier Target (SIT) video camera, a fluorescent microscope, and a personal computer system equipped with an image memory board. This system was based on the fact that the membrane integrity of only plasmid-carrying cells is lost following cell growth in 5-fluoro-orotic acid (5-FOA) containing medium, and consequently these target cell can be stained with fluorescent probes and detected. In this study, plasmid-carrying cells were detected and their fraction determined in a mixture of both plasmid-carring and plasmid-free cells. A good correlation was observed between the values determined by this sensor system and the conventional method in the 30%-80% range, and one assay was possible within 4 h. This sensor system could be used for the monitoring of plasmid-carrying fraction in recombinant yeast cells during cultivation.