Conditions for the primary culture of eye imaginal discs from Drosophila melanogaster

We have established a primary culture system for Drosophila eye imaginal discs. With this system, we were able to obtain neurite outgrowth from intact eye discs, eye disc fragments, and dissociated eye imaginal disc cells. Immunoreactivity to antibody 24B10 indicates that these extending neurites are photoreceptor axons. Three culture media were tested for their ability to support the survival of and neurite extension from eye disc fragments in vitro at 23°C. These, with supplements, were: five parts of Schneider's Drosophila medium with four parts of basal Eagle's medium (“4+5”); Leibovitz's L-15 medium (L-15); and Shields and Sang's M3 modified medium (MM3). We obtained the best results with MM3 supplemented with 2% fetal bovine serum (FBS). Eye disc fragments survived in this medium for at least 20 days. Pigmentation in the nonphotoreceptor pigment cells in cultures from the prepupa required the presence of 20-hydroxyecdysone (20-HE) (1 μg/ml), whereas neurite outgrowth was seen in the absence of 20-HE. Donor animals had to fall within a range of ages to obtain appropriate eye disc differentiation in vitro. Eye discs from 5-h pupae (P+5) or older commenced ommachrome synthesis in vitro, in a temporal sequence close to that found in vivo, whereas the in vitro synthesis of this pigment was delayed in eye discs from younger flies. Average neurite length was not affected by age among pupae younger than P+5; but neurite outgrowth from P+24 was scarce, probably because by this time photoreceptor axons had already grown in vivo and were severed and unable to regenerate in vitro. Eye discs taken from third instar larvae or white prepupae continued their mitotic activity in vitro. Together with the advance of the morphogenetic furrow at the leading edge of retinal development, this observation is consistent with the evidence that pattern formation continues in vitro. Morphogenetic changes were manifested in cultures. Viability tests with calcein AM and ethidium bromide revealed few dead cells in living cultures. © 1995 John Wiley & Sons, Inc.     

A human glial hybrid cell line differentially expressing genes subserving oligodendrocyte and astrocyte phenotype

We have developed a series of immortal human-human hybrid cell lines that express phenotypic characteristics of primary oligodendrocytes, by fusing a 6-thioguanine–resistant mutant of the human rhabdomyosarcoma RD with adult human oligodendrocytes by a lectin-enhanced polyethylene glycol procedure. Hybrids were selected in an aminopterin-containing media. In contrast to the tumor parent cells, a hybrid clone M03.13 expressed surface immunoreactivity for galactosyl cerebroside and intracellular immunoreactivity for myelin basic protein (MBP), proteolipid protein (PLP), and glial fibrillary acidic protein (GFAP). Serum deprivation or chronic treatment with a protein kinase C activator 4-β-phorbol 12-myristate 13-acetate (PMA), but not dibutyl cyclic adenosine monophosphate induced coordinate up-regulation or de novo induction of oligodendrocyte phenotypic markers with concomitant down-regulation of GFAP expression. Consistent with immunohistochemical studies, northern blot analysis demonstrated that both MBP and PLP mRNA were up-regulated in MO3.13 cells by PMA treatment. M03.13 cells provide an immortalized clonal model system suitable for study of gene expression subserving oligodendrocyte and astrocyte phenotypes. © 1995 John Wiley & Sons, Inc.     

Spontaneous calcium transients regulate neuronal plasticity in developing neurons

Calcium ions play critical roles in neuronal differentiation. We have recorded transient, repeated elevations of calcium in embryonic Xenopus spinal neurons over periods of 1 h in vitro and in vivo, confocally imaging fluo 3-loaded cells at 5 s intervals. Calcium spikes and calcium waves are found both in neurons in culture and in the intact spinal cord. Spikes rise rapidly to approximately 400% of baseline fluorescence and have a double exponential decay, whereas waves rise slowly to approximately 200% of baseline fluorescence and decay slowly as well. Imaging of fura 2-loaded neurons indicates that intracellular calcium increases from 50 to 500 nM during spikes. Both spikes and waves are abolished by removal of extracellular calcium. Developmentally, the incidence and frequency of spikes decrease, whereas the incidence and frequency of waves are constant. Spikes are generated by spontaneous calcium-dependent action potentials and also utilize intracellular calcium stores. Waves are produced by a mechanism that does not involve classic voltage-dependent calcium channels. Spikes are required for expression of the transmitter GABA and for potassium channel modulation. Waves in growth cones are likely to regulate neurite extension. The results demonstrate the roles of a novel signaling system in regulating neuronal plasticity, that operates on a time scale 10⁴ times slower than that of action potentials. © 1995 John Wiley & Sons, Inc.     

P48-Triggered transmembrane signaling transduction of human monocytes:mobilization of calcium ion and activation of protein kinase C(PKC)

INTRODUCTI0NThedifferentiati0nofcelIsalongthemonocyte-macr0phagepathwayandthesig-nalsinvo1vedinthesecel1sacquiringtheabilitytokilltum0rcellsarenotfllllyundersto0d.Wehavebeenstudingamoleculewhichappearst0beanimportantmemberofthecytokinenetworkinvo1vedintheregulati0nmonocyteactivation.ThiscytokinetermedP48wasisolatedfr0mthehllmannullcellleukemiacell1ineReh.IthasbeenpurifiedtohomogeneityandfOundtobedistinctfrominterferongamma,col0nystimulatingfactors(CSFs)andTNFalphaalldbeta[1,2].Func-ti…     

家鸡和原鸡的线粒体DNA多态性比较

本文运用１１种限制性内切酶分析了家鸡（茶花鸡、尼西鸡、大理漾濞黄鸡）和原鸡共１０只个体的线粒体ＤＮＡ限制性片段长度多态性（ＲＦＬＰ）,平均每个个检测到的片段为４０条左右。但仅发现３种变异的限制性片制性格局,即ＳｔｕＩ－Ｂ,Ｅｃａ－Ｉ－ｂ和ＲＩ－Ｂ．其中ＳｔｕＩ－Ｂ和ＳｃａＩ－Ｂ为首次报道,而且均为原鸡所物有,ＥｃｏＲＩ－Ｂ则为大理漾濞黄鸡所特有。茶花鸡和尼西鸡拥有完全相同的限制性格局。经过计算,原     

Changes in S-type lectin localization in neuroblastoma cells (N1E115) upon differentiation

The distribution of a 14.4 kDa S-type lectin was examined in murine neuroblastoma cells, either undifferentiated or after differentiation induced by dibutyryl-cyclic adenosine monophosphate. In undifferentiated cells the immunoreactivity was detected extracellularly, associated with the plasma membrane and in bulges released into the extracellular milieu. Important modifications of the lectin localization were associated with the differentiation process that induced an increased cytosolic expression and a decreased externalization. Possible functions for the lectin expressed intracellularly in the differentiated cells are also considered.     

A POPULATION MEMETICS APPROACH TO CULTURAL EVOLUTION IN CHAFFINCH SONG: DIFFERENTIATION AMONG POPULATIONS

We investigated cultural evolution in populations of common chaffinches (Fringilla coelebs) in the Atlantic islands (Azores, Madeira, and Canaries) and neighboring continental regions (Morocco and Iberia) by employing a population-memetic approach. To quantify differentiation, we used the concept of a song meme, defined as a single syllable or a series of linked syllables capable of being transmitted. The levels of cultural differentiation are higher among the Canaries populations than among the Azorean ones, even though the islands are on average closer to each other geographically. This is likely the result of reduced levels of migration, lower population sizes, and bottlenecks (possibly during the colonization of these populations) in the Canaries; all these factors produce a smaller effective population size and therefore accentuate the effects of differentiation by random drift. Significant levels of among-population differentiation in the Azores, in spite of substantial levels of migration, attest to the differentiating effects of high mutation rates of memes, which allow the accumulation of new mutants in different populations before migration can disperse them throughout the entire region.     

Allozyme differentiation within and between red drum (Sciaenops ocellatus) from the Gulf of Mexico and Atlantic Ocean

Nine polymorphic nuclear-gene (allozyme) loci were surveyed among 491 red drum ( Sciaenops ocellatus ) sampled in 1988 and 1989 from nearshore localities in the northern Gulf of Mexico (Gulf) and the Atlantic coast of the southeastern United States (Atlantic). Data were combined with those from a previous study to generate a data set of 762 individuals representing 11 sample localities in the Gulf and 175 individuals representing five sample localities in the Atlantic. The combined data set included individuals from the 1986 and 1987 year classes and permitted rigorous testing of both temporal and spatial genetic heterogeneity. Average heterozygosity-per-locus values (estimated using 33 assumed monomorphic loci) were 0·048 (Gulf red drum) and 0·046 (Atlantic red drum). Tests of heterogeneity in allele frequencies between year classes at individual localities and across regions (Gulf and Atlantic) were non-significant. Tests of spatial (geographic) heterogeneity indicated that red drum are weakly subdivided: genetically-differentiated subpopulations occur in the northern Gulf and along the south-eastern Atlantic coast. Genetic data were consistent with the hypothesis that red drum within the Gulf and along the Atlantic coast comprise singie subpopulalions. Genetic differences between Gulf and Atlantic red drum seem likeiy to stem from historical or recent interactions between dispersal and impediments to gene flow.     

Growth of Ectopic Dendrites on Cortical Pyramidal Neurons in Neuronal Storage Diseases Correlates with Abnormal Accumulation of GM2 Ganglioside

Abstract: Ganglioside analysis and quantitative Golgi studies of the cerebral cortex of cats with ganglioside and nonganglioside lysosomal storage diseases reveal a correlation between the amount of accumulated GM2 ganglioside and the extent of ectopic dendrite growth on cortical pyramidal neurons. This correlation was not observed with any of the other gangliosides assayed for, including GM1 ganglioside. These results suggest a specific role for GM2 ganglioside in the initiation of ectopic neurites on pyramidal cells in vivo and are consistent with the developing hypothesis that different gangliosides have specific roles in different cell types dependent upon the receptor or other effector molecules with which they may interact.     

A simple derivation of the partitioning of genetic differentiation within subdivided populations

The genetic differentiation within a subdivided population can be partitioned into two proportions, one due to differentiation within sub-populations and the other due to differentiation among subpopulations. A simple mathematical derivation of this procedure, known as Nei's G _ST -statistics, is presented. The significance of considering the differing relative sizes of subpopulations is stressed. Possible fields of applications for breeders and conservationists who are concerned with the establishment of genetically diverse populations are mentioned.