Cellular Localization of Transforming Growth Factor-α mRNA in Rat Forebrain

Abstract: The cellular localization of transforming growth factor-α (TGFa) mRNA in juvenile and adult rat forebrain was examined using in situ hybridization with a ³⁵S-labeled cRNA probe. TGFα cRNA-labeled neuronal perikarya were distributed across many forebrain regions including the olfactory bulb, caudate-putamen, nucleus accumbens, olfactory tubercle, ventral pallidum, amygdala, hippocam-pal stratum granulosum and CA3 stratum pyramidale, and piriform, entorhinal, and retrosplenial cortices. TGFα cRNA-hybridizing cells were also localized to several thalamic nuclei and to the suprachiasmatic, dorsomedial, and ventromedial nuclei of the hypothalamus. In addition, labeled cells were present in regions of white matter including the corpus callosum, anterior commissure, internal and external capsules, optic tract, and lateral olfactory tract. Thus, both neurons and glia appear to synthesize TGFα in normal brain. Hybridization densities were greater in neuronal fields at 2 weeks of age compared with the adult, suggesting a role for TGFα in the development of several forebrain systems. Our results demonstrating the prominent and widespread expression of TGFα mRNA in forebrain, combined with the extremely low abundance of epidermal growth factor mRNA in brain, support the argument that TGFα is the principal endogenous ligand for the epidermal growth factor receptor in normal brain.     

Depression of Neuronal Protein Synthesis Initiation by Protein Tyrosine Kinase Inhibitors

Abstract— Growth factors stimulate cellular protein synthesis, but the intracellular signaling mechanisms that regulate initiation of mRNA translation in neurons have not been clarified. A rate-limiting step in the initiation of protein synthesis is the formation of the ternary complex among GTP, eukaryotic initiation factor 2 (elF-2), and the initiator tRNA. Here we report that genistein, a specific tyrosine kinase inhibitor, decreases tyrosine kinase activity and the content of phosphotyrosine proteins in cultured primary cortical neurons. Genistein inhibits protein synthesis by >80% in a dose-dependent manner (10–80 μg/ml) and concurrently decreases ternary complex formation by 60%. At the doses investigated, genistein depresses tyrosine kinase activity and concomitantly stimulates PKC activity. We propose that a protein tyrosine kinase participates in the initiation of protein synthesis in neurons, by affecting the activity of elF-2 directly or through a protein kinase cascade.     

Factor in urinary extracts from pregnant women that inhibit mouse oocyte maturation in vitro

Mouse oocyte maturation inhibitory factors, on the basis of inhibitory activity of spontaneous germinal vesicle breakdown (GVBD) of denuded mouse oocytes in culture, were extracted and partially purified by reversed-phase resin adsorption and Sephadex G-100 and G-50 column chromatographies from the urine of pregnant women. Denuded oocytes obtained from ovaries of ICR mice underwent spontaneous GVBD by cultivation for 3 h in modified Krebs–Ringer's buffered solution, while this spontaneous GVBD was found to be inhibited by adding the final preparation (U-D-4) of urine. The inhibition was dose dependent, ranging from 0.6 to 10 μg protein/ml medium. Oocytes treated with U-D-4 and resuspended in control medium resumed GVBD. The molecular mass of U-D-4 was estimated to be less than 2,000 Da with gel filtration. Ether treatment failed to extract inhibitory factor(s) from U-D-4 and pepsin treatment inactivated U-D-4, indicating that inhibitory factor(s) in U-D-4 are peptide-like substances. The inhibitory effect of U-D-4 on spontaneous GVBD was partially reversed in the presence of naloxone, a potent opioid antagonist. U-D-4s obtained from urine samples of pregnant women, nonpregnant women, and men showed the inhibitory effect on spontaneous GVBD; however, the activity of U-D-4 obtained from pregnancy urine was significantly more potent than those of the other urine samples. © 1993 Wiley-Liss, Inc.     

了哥王叶功能性状特征及其对土壤因子的响应

为探究了哥王Wikstroemiaindica的叶功能性状特征及其影响因素,在海岛植被调查的基础上对了哥王叶片进行取样并测定其功能性状指标,利用变异系数法和Pearson相关性分析探讨叶功能性状之间的差异与联系,运用冗余分析研究了哥王叶功能性状对土壤因子的响应。结果表明,了哥王的叶功能性状变异系数介于9.76%～23.73%,其中叶体积变异幅度最大(23.73%),叶干物质含量变异幅度最小(9.76%),整体上了哥王叶功能性状保持相对稳定。了哥王各项叶功能性状之间具有一定的相关性,联系较密切。了哥王叶功能性状主要受土壤中有机质、全氮、碱解氮的影响,土壤中有机质、全氮、碱解氮的含量与比叶面积呈正比,与叶厚度、叶体积成反比。了哥王的叶片可以通过一定的性状变异和组合来适应外部环境的变化,以较好地适应海岛恶劣的环境。该研究结果可为了哥王野生种质资源的保护、利用以及人工栽培提供参考。     

慈竹无性系种群能值特点及其影响能值计测因素的研究

 本文引用Harper(1977)的构件结构理论,从构件结构单位、无性系分株和无性系三个层次,对四川南充市郊慈竹无性系种群的能值特点及其影响能值的计测因素进行了定量研究。研究结果表明：慈竹无性系种群中,各构件单位的去灰分热值(AFCV)分别为：根15349.42J／g、根茎16372.92J／g、秆17106.06J／g、枝18111.99J／g和叶19451.90J／g;慈竹无性系分株的AFCV(J／g)随龄级增大而递增;慈竹无性系水平上的AFCV为：Ⅰ龄占16.47%、Ⅱ龄占25.76%、Ⅲ龄占36.32%、Ⅳ龄为13.08%及Ⅴ龄为8.37%。用恒容燃烧法测定热值时,其能值变化与氧分压密切相关。用经验公式计算的能值较作图法高;用AFCV表示能值较总干重热值(GCV)准确。     

Neoplastic progression of rat tracheal epithelial cells is associated with a reduction in the number of growth factors required for clonal proliferation in culture

Summary Factors regulating the proliferation of normal, preneoplastic, and neoplastic rat tracheal epithelial (RTE) cells were investigated to identify changes taking place during the progression of RTE cells to neoplasia. Normal RTE cells exhibit clonal proliferation in a serum-free medium containing pituitary extract, serum albumin, cholera toxin, epidermal growth factor, hydrocortisone, and insulin. All combinations of these six factors were examined for their abilities to support clonal proliferation of normal, preneoplastic, and neoplastic RTE cells. In general, preneoplastic RTE cells required fewer factors for proliferation than normal RTE cells, and neoplastic cells required fewer factors than preneoplastic cells. A common pattern of reductions has been identified in the growth factors required for the clonal proliferation of preneoplastic vs. normal RTE cells and for neoplastic vs. preneoplastic and normal RTE cells. Normal RTE cells exhibit clonal proliferation in a serum-free medium supplemented with a minimum of six factors: bovine serum albumin, bovine pituitary extract, cholera toxin, epidermal growth factor, hydrocortisone, and insulin. Preneoplastic RTE cells exhibit clonal proliferation in a serum-free medium supplemented with four factors: bovine serum albumin, bovine pituitary extract, hydrocortisone, and insulin. Finally, neoplastic RTE cells exhibit clonal proliferation in a serum-free medium supplemented with two factors: bovine serum albumin and bovine pituitary extract. These results suggest that the progression of RTE cells to neoplasia is associated with a series of changes in regulatory pathways that control cell proliferation.     

Selected factors limiting the microbial degradation of recalcitrant compounds

Summary The focus of this review is to examine some of the reasons biodegradation may not take place in the environment even though its occurrence in the laboratory has been demonstrated. Some approaches for dealing with chemical persistence will be discussed. In addition, the potential of bioremediation as an in situ clean-up technology will be considered.     

The distribution of coastal fish eDNA sequences in the Anthropocene

Aim

Coastal fishes have a fundamental role in marine ecosystem functioning and contributions to people, but face increasing threats due to climate change, habitat degradation and overexploitation. The extent to which human pressures are impacting coastal fish biodiversity in comparison with geographic and environmental factors at large spatial scale is still under scrutiny. Here, we took advantage of environmental DNA (eDNA) metabarcoding to investigate the relationship between fish biodiversity, including taxonomic and genetic components, and environmental but also socio-economic factors.

Location

Tropical, temperate and polar coastal areas.

Time period

Present day.

Major taxa studied

Marine fishes.

Methods

We analysed fish eDNA in 263 stations (samples) in 68 sites distributed across polar, temperate and tropical regions. We modelled the effect of environmental, geographic and socio-economic factors on α- and β-diversity. We then computed the partial effect of each factor on several fish biodiversity components using taxonomic molecular units (MOTU) and genetic sequences. We also investigated the relationship between fish genetic α- and β-diversity measured from our barcodes, and phylogenetic but also functional diversity.

Results

We show that fish eDNA MOTU and sequence α- and β-diversity have the strongest correlation with environmental factors on coastal ecosystems worldwide. However, our models also reveal a negative correlation between biodiversity and human dependence on marine ecosystems. In areas with high dependence, diversity of all fish, cryptobenthic fish and large fish MOTUs declined steeply. Finally, we show that a sequence diversity index, accounting for genetic distance between pairs of MOTUs, within and between communities, is a reliable proxy of phylogenetic and functional diversity.

Main conclusions

Together, our results demonstrate that short eDNA sequences can be used to assess climate and direct human impacts on marine biodiversity at large scale in the Anthropocene and can further be extended to investigate biodiversity in its phylogenetic and functional dimensions.