极低频磁场的生物学效应

极低频磁场的生物学效应是当前国际上关注的研究热点 .本文介绍了极低频磁场生物学效应的物理原理及实验研究 ,并综述了极低频磁场对中枢神经的影响以及在临床上的应用 .     

福田红树林桐花树和秋茄的生长过程研究

对深圳福田红树林群落两个优势种桐花树（Ａｅｇｉｃｅｒａｓｃｏｒｎｉｃｕｌａｔｕｍ）和秋茄（Ｋａｎｄｅｌｉ－ａｃａｎｄｅｌ）进行横剖树干解析，研究这两个树种的胸径、地径、树高、材积生长量的年变化规律及形数年变化规律，结果为：胸径、地径、树高、材积生长量呈镊合状曲线态；其年生长量一般在其最大值的５０％～９８％之间；各种平均生长量随年龄的增加而平缓地增加，近峰值而未及，可见两树种有相当长的成熟及衰老期，它们的现存年龄为２０ａ左右；两树种的基部形数不随年龄的增加而呈规律性的变化，很难确定其经验形数值     

Immunoactive TSH in the amniotic fluid of the rat

Summary Amniotic fluid was obtained from 19-day-old rat fetuses by aspiration. Pooled samples measured at 4 different dilutions demonstrated parallelism with standard rat TSH. It is concluded that rat amniotic fluid has TSH immunoactivity.This work was supported by Hong Kong University Research Grant No. 335/034/5727.The authors wish to acknowledge with thanks the gift of rat TSH RIA kit from Dr A. F. Parlow and the Rat Pituitary Programme of NIAMDD.     

A single population of olfactory sensory neurons mediates an innate avoidance behaviour in Drosophila

All animals exhibit innate behaviours in response to specific sensory stimuli that are likely to result from the activation of developmentally programmed neural circuits. Here we observe that Drosophila exhibit robust avoidance to odours released by stressed flies. Gas chromatography and mass spectrometry identifies one component of this 'Drosophila stress odorant (dSO)' as CO2. CO2 elicits avoidance behaviour, at levels as low as 0.1%. We used two-photon imaging with the Ca2+-sensitive fluorescent protein G-CaMP to map the primary sensory neurons governing avoidance to CO2. CO2 activates only a single glomerulus in the antennal lobe, the V glomerulus; moreover, this glomerulus is not activated by any of 26 other odorants tested. Inhibition of synaptic transmission in sensory neurons that innervate the V glomerulus, using a temperature-sensitive Shibire gene (Shi(ts)), blocks the avoidance response to CO2. Inhibition of synaptic release in the vast majority of other olfactory receptor neurons has no effect on this behaviour. These data demonstrate that the activation of a single population of sensory neurons innervating one glomerulus is responsible for an innate avoidance behaviour in Drosophila.     

A specific requirement for PDGF-C in palate formation and PDGFR-alpha signaling

PDGF-C is a member of the platelet-derived growth factor (PDGF) family, which signals through PDGF receptor (PDGFR) alphaalpha and alphabeta dimers. Here we show that Pdgfc(-/-) mice die in the perinatal period owing to feeding and respiratory difficulties associated with a complete cleft of the secondary palate. This phenotype was less severe than that of Pdgfra(-/-) embryos. Pdgfc(-/-) Pdgfa(-/-) embryos developed a cleft face, subepidermal blistering, deficiency of renal cortex mesenchyme, spina bifida and skeletal and vascular defects. Complete loss of function of both ligands, therefore, phenocopied the loss of PDGFR-alpha function, suggesting that both PDGF-A and PDGF-C signal through PDGFR-alpha to regulate the development of craniofacial structures, the neural tube and mesodermal organs. Our results also show that PDGF-C signaling is a new pathway in palatogenesis, different from, and independent of, those previously implicated.     

Transmitter-evoked local calcium release stabilizes developing dendrites

In the central nervous system, dendritic arborizations of neurons undergo dynamic structural remodelling during development. Processes are elaborated, maintained or eliminated to attain the adult pattern of synaptic connections. Although neuronal activity influences this remodelling, it is not known how activity exerts its effects. Here we show that neurotransmission-evoked calcium (Ca(2+)) release from intracellular stores stabilizes dendrites during the period of synapse formation. Using a ballistic labelling method to load cells with Ca(2+) indicator dyes, we simultaneously monitored dendritic activity and structure in the intact retina. Two distinct patterns of spontaneous Ca(2+) increases occurred in developing retinal ganglion cells--global increases throughout the arborization, and local 'flashes' of activity restricted to small dendritic segments. Blockade of local, but not global, activity caused rapid retraction of dendrites. This retraction was prevented locally by focal uncaging of caged Ca(2+) that triggered Ca(2+) release from internal stores. Thus, local Ca(2+) release is a mechanism by which afferent activity can selectively and differentially regulate dendritic structure across the developing arborization.     

Marine iguanas die from trace oil pollution

An oil tanker ran aground on the Galapagos island of San Cristóbal on 17 January 2001, spilling roughly three million litres of diesel and bunker oil. The slick started to spread westwards and was dispersed by strong currents, so only a few marine animals were killed immediately as a result. Here we draw on the long-term data sets gathered before the spill to show that a population of marine iguanas (Amblyrhychus cristatus) on Sante Fe island suffered a massive 62% mortality in the year after the accident, due to a small amount of residual oil contamination in the sea. Another population on the more remote island of Genovesa was unaffected.     

A 5-bp deletion in ELOVL4 is associated with two related forms of autosomal dominant macular dystrophy

Stargardt-like macular dystrophy (STGD3, MIM 600110) and autosomal dominant macular dystrophy (adMD) are inherited forms of macular degeneration characterized by decreased visual acuity, macular atrophy and extensive fundus flecks. Genetic mapping data suggest that mutations in a single gene may be responsible for both conditions, already known to bear clinical resemblance. Here we limit the minimum genetic region for STGD3 and adMD to a 0.6-cM interval by recombination breakpoint mapping and identify a single 5-bp deletion within the protein-coding region of a new retinal photoreceptor-specific gene, ELOVL4, in all affected members of STGD3 and adMD families. Bioinformatic analysis of ELOVL4 revealed that it has homology to a group of yeast proteins that function in the biosynthesis of very long chain fatty acids. Our results are therefore the first to implicate the biosynthesis of fatty acids in the pathogenesis of inherited macular degeneration.