Influence of quantal size and cAMP on the kinetics of quantal catecholamine release from rat chromaffin cells

Using carbon fiber amperometry, we exploited the natural variation in quantal size (Q) among individual granules in rat chromaffin cells to examine the influence of Q on quantal release kinetics. Although it is generally accepted that granules with larger Q have slower kinetics of release, we found that this trend was applicable only to granules with Q(1/3) < 0.6 pC(1/3). Granules with larger Q adapted specific mechanisms to maintain a rapid kinetic of release. The semistable fusion pores in the large-Q granules persisted for a longer duration and could reach a bigger size before the onset of very rapid dilation to allow a longer and larger foot signal. Most importantly, a large proportion of large-Q granules maintained a relatively short half-width in the main spike. This suggests that the most rapid phase of fusion pore dilation in many large-Q granules may be faster than that in small-Q granules. Moreover, cAMP selectively advanced the onset of the rapid dilation of the fusion pore in the large- but not the small-Q granules. Thus, our finding raises the possibility that fusion pore and/or granule matrix in small- and large-Q granules may have different molecular structures.     

光温外界信号、植株状态与成花决定

植物由营养生长状态转向生殖生长状态（成花转变）是发育过程中的重要一步。经过一段时期营养生长的植株,便自动进入成花感受态,在这种状态下植株才能够对外界信号产生应答反应而启动成花过程。本文主要讨论光周期和温度对成花的作用     

Differential display of human marrow stromal cells reveals unique mRNA expression patterns in response to dexamethasone

Human bone marrow stromal cells (hBMSC) are pluripotent cells that have the ability to differentiate into bone, cartilage, hematopoietic‐supportive stroma, and adipocytes in a process modulated by dexamethasone (DEX). To characterize changes in hBMSC in response to DEX, we carried out differential display experiments using hBMSC cultured for 1 week in the presence or absence of 10⁻⁸ M DEX. When RNA from these cells was used for differential display, numerous cDNA bands were identified that were up‐regulated and down‐regulated by DEX. The cDNA bands were reamplified by PCR and directly used to screen an hBMSC cDNA library. Seven clones were isolated and characterized by DNA sequencing and found to encode the following genes: transforming growth factor‐β‐induced gene product (βig‐h3), calphobindin II, cytosolic thyroid‐binding protein, 22‐kDA smooth muscle protein (SM22), and the extracellular matrix proteins osteonectin/SPARC, type III collagen, and fibronectin. To confirm that these genes were regulated by DEX, the cells were treated continuously with this hormone for periods ranging from 2 to 30 days, and steady‐state mRNA levels were measured by Northern blot analysis. All genes showed some level of regulation by DEX. The most profound regulation by DEX was observed in the βig‐h3 gene, which showed a relative 10‐fold decrease in mRNA levels after 6 days of treatment. Interestingly, βig‐h3 expression was not altered by DEX in fibroblasts from other human tissues, including thymus stromal fibroblasts, spleen stromal fibroblasts, and foreskin fibroblasts. In summary, differential display of DEX‐treated hBMSC revealed unique patterns of gene expression and has provided new information about phenotypic changes that accompany the differentiation of hBMSC toward osteogenesis. J. Cell. Biochem. 76:231–243, 1999. Published 1999 Wiley‐Liss, Inc.     

Occurrence of high-diversity metazoan- to microbial-dominated bioconstructions in a shallow Kimmeridgian carbonate ramp (Jabaloyas,Spain)

The horizontal and vertical transitions of a wide range of bioconstructions are documented from the shallow domains of a Kimmeridgian carbonate ramp (Upper Jurassic) in the Jabaloyas area of NE Spain. The bioconstructions include microbial buildups, coral-bearing thrombolite buildups, coral-microbial buildups, branching coral patches, oyster patches, and stromatoporoid carpets. Buildups form stacked pinnacles up to 19 m thick, within a broad spectrum of coeval inter-buildup carbonate facies. Coral-bearing thrombolites are coincident with shallow-marine oolitic sands, indicating development during the initial platform flooding (unit 1). During the continued sea-level rise (units 2 and 3), coral-microbial buildups [encrusted by Crescentiella (Tubiphytes) and serpulids] were established from proximal to distal mid-ramp domains, and these showed an increasing proportion of microbial crust in distal domains. Inter-buildup oolitic facies sharply grade down-dip to hummocky cross-stratified intraclastic, peloidal, and skeletal deposits, mostly sourced from the coral-microbial buildups. The lower part of unit 4 was dominated by microbialites in the proximal areas, related to local fresh-water input causing seawater stratification and oxygen depletion. The upper part of unit 4 indicates an initial recovery of metazoan frame builders, with abundant branching corals. During the late regression (units 5 and 6), Marinella lugeoni red algae, oyster patches, and stromatoporoid boulders developed close to the shoreline in well-oxygenated waters with high nutrient content. The reported data contribute to the discussion of the optimal environmental conditions for each “bioconstruction window” in Jabaloyas, namely sediment and nutrient supply, water depth, water oxygenation, wave energy and light availability.     

Chlorophyll fluorescence imaging can reflect development of vascular connection in grafting union in some Solanaceae species

Graft union development in plants has been studied mainly by destructive methods such as histological studies. The aim of this work was to evaluate whether the chlorophyll fluorescence imaging (CFI) technique is sensitive enough to reflect changes at the cellular level in different Solanaceae grafted plants 30 d after grafting, when both grafted partners were well fused and strong enough in all plant combinations. The pepper cultivar ‘Adige’ was grafted onto different Capsicum spp. accessions typified with different compatibility degrees; eggplant was grafted on Solanum torvum and pepper homografts as compatible unions; pepper was grafted on S. torvum and on tomato as incompatible unions. ‘Adige’/’Adige’ and ‘Adige’/pepper A25 showed a higher maximum quantum efficiency of PSII associated with higher values of actual quantum efficiency of PSII and photochemical quenching as well as with vascular regeneration across the graft interface. Our results highlighted that CFI changes reflected histological observations in grafted Solanaceae plants.     

Detection of Southern tomato virus by molecular hybridisation

Southern tomato virus (STV) is a double‐stranded RNA (dsRNA) virus belonging to the genus Amalgavirus from the family Amalgamaviridae. STV has been detected in tomato plants showing symptoms of stunting, fruit discoloration and size reduction, although its role on symptom development is unclear. Also, little is known about the incidence and epidemiology of this virus and how it spreads in tomato crops. In this work, we developed a molecular hybridisation method by using a digoxigenin‐labelled RNA probe based on the nucleotide sequence of the STV putative coat protein which was tested with different procedures for preparation of plant material. This technique was sensitive enough to detect STV from sap extracts (obtained just by grinding in buffer) from different plant tissues such as leaves, fruits, roots and seeds. This procedure is suitable for field surveys since it allows a cheap and quick processing of a high number of samples. Surveys performed in three important tomato production areas (Peninsular Spain, the Canary Islands and Sicily) showed that STV is widely spread, with incidences ranging from 18% to 74% in different local and commercial tomato varieties.     

Geographic patterns of genetic variation in nuclear and chloroplast genomes of two related oaks (<Emphasis Type="Italic">Quercus aliena</Emphasis> and <Emphasis Type="Italic">Q. serrata</Emphasis>) in Japan: implications for seed and seedling transfer

In this study, we assessed geographic patterns of genetic variations in nuclear and chloroplast genomes of two related native oaks in Japan, Quercus aliena and Q. serrata, in order to facilitate development of genetic guidelines for transfer of planting stocks for each species. A total of 12 populations of Q. aliena and 44 populations of Q. serrata were analyzed in this study. Genotyping of nuclear microsatellites in Q. aliena was done with only nine populations (n = 212) due to limited numbers of individuals in two populations, while all 12 populations (n = 89) were used in sequencing chloroplast DNA (cpDNA). In Q. serrata, 43 populations (n = 1032) were genotyped by nuclear microsatellite markers, while cpDNA of 44 populations (n = 350) was sequenced. As anticipated, geographic patterns detected in the variations of Q. aliena’s nuclear genome and its chloroplast haplotype distribution clearly distinguished northern and southern groups of populations. However, those of Q. serrata were inconsistent. The geographic distribution of its chloroplast haplotypes tends to show the predicted differentiation between northern and southern lineages, but geographic signals in the genetic structure of its nuclear microsatellites are weak. Therefore, treating northern and southern regions of Japan as genetically distinct transferrable zones for planting stocks is highly warranted for Q. aliena. For Q. serrata, the strong NE-SW geographic structure of cpDNA should be considered.     

Import of Rift Valley fever to China: a potential new threat?

正Several recent studies in Virologica Sinica and other journals have highlighted the enormous international challenge of emerging arboviral diseases,such as Zika virus disease,dengue,and chikungunya(Islam et al.,2015;Maurice et al.,2015;Dai et al.,2016;Deng et al.,2016;Song et al.,2016;Wang et al.,2016;Xu et al.,2016;Zhang et al.,2016;Zhou et