Programmed cell death during floral nectary senescence in Ipomoea purpurea

The nectaries of Ipomoea purpurea wilt in the late flowering period. The senescence process of nectaries is frequently associated with cell lysis. In this paper, various techniques were used to investigate whether programmed cell death (PCD) was involved in the senescence process of nectaries in I. purpurea. Ultrastructural studies showed that nectary cells began to undergo structural distortion, chromatin condensation, mitochondrial membrane degradation, and vacuolar-membrane dissolution and rupture after bloom. 4′,6-Diamidino-2-phenylindole (DAPI) and terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine-5′-triphosphate (dUTP) nick end-labeling (TUNEL) assay showed that nectary cell nuclear DNA began to degrade during the budding stage, and disappeared in the fruiting stage. DNA gel electrophoresis showed that degradation of DNA was random. Together, these results suggest that PCD participate in the senescence of the nectary in I. purpurea. PCD began during the budding period, followed by significant changes in nectary morphology and structure during the flowering period. During the fruiting stage, the PCD process is complete and the nectary degrades.     

水稻蜡质基因5＇上游区缺失对基因表达的影响

为研究水稻蜡质基因（ｗａｘｙ）５＇上游调控区中存在的顺式作用元件,我们将水稻ｗａｘｙ基因翻译起始声、（ＡＴＧ）５＇上游３．４ｋｂ（－２１１８～＋１２９１ｂＰ）片段经外切核酸酶ＥｘｏⅢ部分酶解,得到一系列５＇端缺失的片段。将这些缺失片段分别与ｇｕｓ基因编码区连接,构建成融合质粒,经ＰＥＧ介导引入水稻原生质体,２６℃培养４８ｈ后,定量测定ＧＵＳ酶活力,并以同时导入的由３５Ｓ启动子指导的荧光素酶（ＬＵＣ）基因表达的酶活力作为内对照。结果表明,ＧＵＳ酶活性随５’上游调控区长度的减少而逐渐减弱。由─８６１ｂｐ缺失至─６４０ｂＰ时,ｇｕｓ基因表达水平有较明显的降低,推测在该区域中可能存在一个顺式作用元件区。     

Diploid hybrid origin of Hippophaë gyantsensis (Elaeagnaceae) in the western Qinghai–Tibet Plateau

Homoploid hybrid speciation, the origin of a hybrid species without change in chromosome number, is currently considered to be a rare form of speciation. In the present study, we examined the phylogenetic origin of Hippophaë gyantsensis, a diploid species occurring in the western Qinghai–Tibet Plateau. Some of its morphological and molecular traits suggest a close relationship to H. rhamnoides ssp. yunnanensis while others indicate H. neurocarpa. We conducted phylogenetic analyses of sequence data of two maternally inherited chloroplast (cp) DNA fragments and the bi‐parentally inherited nuclear ribosomal internal transcribed spacer (ITS) from 17 populations of H. gyantsensis, 15 populations of H. rhamnoides ssp. yunnanensis and 27 populations of H. neurocarpa across their distributional ranges, and modelled the niche differentiation of the three taxa. Multiple lines of evidence suggested that H. gyantsensis is a morphologically stable, genetically independent and ecologically distinct species. The inconsistent phylogenetic placements of the H. gyantsensis clade that comprised the dominant cpDNA haplotypes and ITS ribotypes suggested a probable diploid hybrid origin from multiple crosses between H. rhamnoides ssp. yunnanensis and H. neurocarpa. This tentative hypothesis is more parsimonious than alternative explanations according to the data available, although more evidence based on further testing is needed.     

Implementing Extended Producer Responsibility Legislation

The goal of this article is to contribute to the understanding of how the multiple, and sometimes conflicting, stakeholder perspectives and prevailing conditions (economic, geographic, etc.) in the implementation locality shape extended producer responsibility (EPR) “on the ground.” We provide an in‐depth examination of the implementation dimension of EPR in a specific case study by examining concrete activities at the operational front of the collection and recycling system, and probing the varying stakeholder preferences that have driven a specific system to its status quo. To this end, we conduct a detailed case study of the Washington State EPR implementation for electronic waste. We provide an overview of various stakeholder perspectives and their implications for the attainment of EPR policy objectives in practice. These findings shed light on the intrinsic complexity of EPR implementation. We conclude with recommendations on how to achieve effective and efficient EPR implementation, including improving design incentives, incorporating reuse and refurbishing, expanding product scope, managing downstream material flows, and promoting operational efficiency via fair cost allocation design.     

Stress-Derived Corticotropin Releasing Factor Breaches Epithelial Endotoxin Tolerance

Background and aims

Loss of the endotoxin tolerance of intestinal epithelium contributes to a number of intestinal diseases. The etiology is not clear. Psychological stress is proposed to compromise the intestinal barrier function. The present study aims to elucidate the role of the stress-derived corticotropin releasing factor (CRF) in breaching the established intestinal epithelial endotoxin tolerance.

Methods

Epithelial cells of HT-29, T84 and MDCK were exposed to lipopolysaccharide to induce the endotoxin tolerance; the cells were then stimulated with CRF. The epithelial barrier function was determined using as indicators of the endotoxin tolerant status. A water-avoid stress mouse model was employed to test the role of CRF in breaching the established endotoxin tolerance in the intestine.

Results

The established endotoxin tolerance in the epithelial cell monolayers was broken down by a sequent exposure to CRF and LPS manifesting a marked drop of the transepithelial resistance (TER) and an increase in the permeability to a macromolecular tracer, horseradish peroxidase (HRP). The exposure to CRF also increased the expression of Cldn2 in the epithelial cells, which could be mimicked by over expression of TLR4 in epithelial cells. Over expression of Cldn2 resulted in low TER in epithelial monolayers and high permeability to HRP. After treating mice with the 10-day chronic stress, the intestinal epithelial barrier function was markedly compromised, which could be prevented by blocking either CRF, or TLR4, or Cldn2.

Conclusions

Psychological stress-derived CRF can breach the established endotoxin tolerance in the intestinal mucosa.     

锯缘青蟹精巢发育的组织学观察

组织学观察表明,锯缘青蟹（Scylla serrata)精巢发育周期可以分为精原细胞期,精母细胞期,精子细胞期,精子期和休止期5个时期。在划分精巢发育期的基础上,结合生精小管直径的成熟节段比例这2个指标,可以较准确地反映锯缘青解精巢的发育状况。而成熟节段比例可以作为锯缘青蟹精巢发育的表征指标。     

Differential gene expression in fully-grown oocytes between gynogenetic and gonochoristic crucian carps.

Silver crucian carp (Carassius auratus gibelio) is a unique triploid bisexual species that can reproduce by gynogenesis. As all other gynogenetic animals, it keeps its chromosome integrity by inhibiting the first meiosis division (no extrusion of the first pole body). To understand the molecular events governing this reproduction mode, suppression subtractive hybridization was used to identify the genes differentially expressed in fully-grown oocytes of the gynogenetic and gonochoristic crucian carp (gyno-carp and gono-carp). From two specific subtractive cDNA libraries, the clones screened out by dot blots and virtual Northern blots were chosen to clone full-length cDNA by RACE. Four differentially expressed genes were obtained. Two are novel genes and are expressed specifically in the oocytes. The gyno-carp stores much more mRNA of cyclin A2, a new member of the fish A-type cyclin gene, in its fully-grown oocyte than in the gono-carp. The last gene is histone H2A. The histone H2As of these two closely related crucian carps are quite different in the C-terminus. Preliminary characterization of the four genes has been analyzed by nucleotide and deduced amino acid sequence and Northern analysis.