Glucuronidation and sulfation of p-nitrophenol in isolated rat hepatocyte subpopulations. Effects of phenobarbital and 3-methylcholanthrene pretreatment

Parenchymal cells, isolated from untreated (control), phenobarbital(PB)-or 3-methylcholanthrene(3-MC)-treated rats, were separated into four subpopulations according to cell density, and glucuronidation and sulfation of p-nitrophenol (PNP) in the hepatocyte subpopulations were investigated. PB enhanced the glucuronidation almost 2-fold but not the sulfation, while 3-MC enhanced both glucuronidation (3-fold) and sulfation (2-fold) in the original cell suspensions. Some gradation trends were found in the conjugation activities among the hepatocyte subpopulations: In the control experiment, the extent of glucuronidation in four subpopulations was virtually the same but sulfation in high-density hepatocytes was slightly higher than in low-density ones. Both glucuronidation and sulfation were higher in low-density hepatocytes from PB-treated rats, though the gradation was very modest. Glucuronidation and sulfation tended to be slightly higher in middle-density hepatocytes in the 3-MC experiment. However, no definite correlation in conjugation activities vs. cell density, like those seen in cytochrome P-450s vs. cell density in the hepatocytes isolated from PB-treated rats, were found in the subpopulations from control or inducer-treated rats. Simultaneous studies on acetylation of p-aminobenzoic acid (PABA) revealed that the activities in the subpopulations were virtually the same and the inducers had little influence on the activity.     

Choleretic effects of yarrow (Achillea millefolium s.l.) in the isolated perfused rat liver

Different species from the Achillea millefolium aggregate are used against gastrointestinal and hepato-biliary disorders in traditional European medicine. In this work, a fraction enriched in dicaffeoylquinic acids (DCCAs) and luteolin-7-O-β-d-glucuronide was investigated on its choleretic effect in the isolated perfused rat liver (IPRL) compared to cynarin (1,3-DCCA), the main choleretic compound of Cynara scolymus L. A fraction containing 3,4-, 3,5- and 4,5-DCCA and luteolin-7-O-β-d-glucuronide was prepared by solid phase extraction from a 20% methanolic extract of yarrow. A total amount of 48.8% DCCAs and 3.4% luteolin-7-O-β-d-glucuronide was determined by HPLC analysis with cynarin as internal standard. IPRL experiments revealed a dose-dependant increase in bile flow (23–44–47%) by the Achillea fraction. Choleresis was two- to three-fold higher than that of cynarin. The combined effect of DCCAs and luteolin-7-O-β-d-glucuronide stimulated bile flow more effectively than the single compound cynarin. Due to their polar structure, these compounds are quantitatively extracted into teas and tinctures; hence, they seem to be the choleretic active principles in the traditional application forms of yarrow.     

The adrenomedullin receptor acts as clearance receptor in pulmonary circulation

Adrenomedullin (AM) is a powerful pulmonary vasodilator with antimitogenic properties. We investigated the role of the AM receptor (AMR) and the calcitonin gene-related peptide type-1 receptor (CGRP1R) in regulating pulmonary vascular AM levels. The AMR antagonist hAM(22-52) (120 nmol/L) significantly elevated AM release compared with controls to 250% after 2 h in isolated rat lungs and to 830% after 4 h in pulmonary artery endothelial cells (PAEC). CGRP1R blockade had no effect. AMR blockade did not influence prepro-AM mRNA levels nor did inhibition of protein synthesis by cycloheximide (0.01 mg/mL) abolish the effect of the AMR antagonist. Radioligand-binding studies with PAEC membranes revealed a decrease by 44% of the AMR density in response to AMR antagonism. Altogether, the pulmonary vascular AMR represents not only a functionally active, but also a clearance receptor; its expression is constitutively stimulated by basal AM. This identifies a novel mechanism for controlling pulmonary AM levels.     

Morphometric analysis of the isolated calcium-tolerant cardiac myocyte

Summary Using morphometric analysis of thin sections and freeze-fracture replicas, the ultrastructure of isolated rat myocytes prepared by collagenase digestion (Powell et al. 1980) was compared with that of myocytes fixed by perfusion of intact myocardium. The volumes of myofibrils, mitochondria, nuclei, sarcoplasmic reticulum and lipid droplets in the isolated myocytes did not differ from those of their counterparts in the intact heart, but the volume occupied by transverse tubules was apparently reduced. The isolated cells had significantly shorter sarcomeres than did cells in the intact tissue, and this was associated with an altered topography of plasma membrane surface folds at the level of the Z-lines. Plasma membrane intramembrane particles were randomly distributed and showed the same numerical density on the E-faces of both isolated and intactheart myocytes. However, P-face particle density was slightly reduced in the isolated cells. It is concluded that the few differences detected in the isolated cells do not reflect any fundamental derangement of their properties.     

Optimization of maize microspore isolation and culture conditions for reliable plant regeneration

Summary The effects of different factors were investigated in the process of isolated microspore culture of Zea mays L., Using donor plants grown in standard conditions and an efficient isolation technology, homogeneous populations of viable microspores at specific developmental stages were obtained and tested in culture. The cytological evolution of the microspores during the first week of culture was monitored using a DNA-specific fluorochrome. It was found that developmental stages of microspores, number of days of pretreatment at 7°C of the tassel, and culture density greatly influenced the number of microspore-derived embryos. Optimal conditions required for embryo and plant production are described.Abbreviations ISO isolation medium - MS Murashige and Skoog - Na2EDTA ethylene diaminetetraacetic aciddisodium salt - AS androgenic structures - CFA correspondence factorial analysis - FDA fluorescein diacetate - IM induced microspores     

An extralimital population in a warm climatic outpost: the case of the mothIdaea dilutaria in Scandinavia

The mothIdaea dilutaria Hübn. (Geometridae) has an isolated population on the Kullaberg peninsula in southern Sweden. Investigations of the local and micro-climate on the peninsula showed that the local distribution range of the moth coincided with the areas of warmest climate, supporting the hypothesis that the Kullaberg poppulation is dependent for its survival on the warm climate of this area and that the species here is a thermal relict from a previously warmer climatic period.     

Aloe-emodin-induced DNA fragmentation in the mouse in vivo comet assay

Aloe-emodin (AE) and derivatives may be present as undesired components co-extracted during extraction of plants containing anthraquinonic derivatives for preparation of diacetylrhein. AE is a well-known in vitro mutagen, but up to now it failed to induce any clear in vivo genotoxic activity in the chromosome aberration assay in rat bone marrow or the in vivo/in vitro UDS test in liver. However, the two target organs noted during rodent carcinogenicity studies with danthron and emodin, two other well-known anthraquinone derivatives, are the colon and the kidney. Therefore, the choice of the organs for testing the genotoxicity of AE, i.e. bone marrow and liver, may be considered inadequate to demonstrate a possible in vivo genotoxic activity. In this context, the in vivo mouse comet assay was performed on both isolated kidney and colon cells in order to demonstrate a possible organospecific genotoxicity after oral administration of AE. Concurrently, the Ames test and the in vitro micronucleus assay with TK6 human lymphoblastoid cells were performed in their microscale version both with S9 from Aroclor 1254-induced liver or kidney, and without S9.AE induced primary DNA damage in the liver and in the kidney as observed between 3 and 6 h after two oral administrations at 500, 1000 and 2000 mg/kg bw, underlining an in vivo genotoxic mechanism of action. Furthermore, AE induced a clear genotoxic activity both in the Salmonella typhimurium strains TA1537 and TA98 and in the in vitro micronucleus assay in the absence as well as in the presence of metabolic activation. As no significant variation in the genotoxic activity of AE was noted when using either liver or kidney S9-mix, it seems that no quantitatively and/or qualitatively specific renal metabolism occurs. The kidney may be a target organ of AE as it is the major route of excretion. Under such conditions the separation of AE components should take place and the residual content of undesired AE derivatives should be made as low as reasonably achievable. AE present in plant extracts should be considered as an in vivo genotoxin and this property should be taken into account in the risk assessment for human exposure.     

Ecophysiology of cuticular transpiration: comparative investigation of cuticular water permeability of plant species from different habitats

Water permeabilities of astomatous, isolated cuticular membranes (CM) of 24 different plants species were measured. Permeances varied from 1.7×10^–11 m·s^–1 (Vanilla planifolia leaf) up to 2.1×10^–9 m·s^–1 (Malus cf. domestica fruit) among different plant species, thus covering a range of over 2 orders of magnitude. Ranking of species according to permeances resulted in four distinct groups. The first group, of species with the lowest cuticular transpiration rates, included evergreen species growing in warm dry tropical climates (e.g. Vanilla planifolia and Monstera deliciosa leaves). The second class, with slightly higher water permeabilities, included evergreen species with typical scleromorphic leaf properties, adapted to a typical mediterranean type of climate with a dry period during the year (e.g. Citrus limon and Olea europaea leaves). The third group of species, where the highest leaf cuticular transpiration rates were observed, included deciduous species normally growing in a tempeate climate (e.g. Juglans regia and Forsythia suspensa leaves). Fruit cuticular membranes (CM) made up the fourth group (e.g. Capsicum annuum and Malus cf. domestica fruits), with even higher permeances than leaves of species from group 3. Thus, it appears that the plant species investigated show ecophysiological adaptations to the climatic demands of their natural habitats in cuticular water permeability.     

丁酸钠对大鼠离体灌流心脏细胞核组蛋白乙酰化的影响

本文用离体心脏灌流技术研究了丁酸钠对~3H-乙酰基参入大鼠心脏细胞核纽蛋白的影响。用蔗糖梯度离心将大鼠离体灌流心脏的细胞核分为心肌的和非心肌的,分别提取组蛋白。尿素-丙烯酰胺凝胶电泳将组蛋白分为五个组分。其比放射性测定的结果表明,~3H-乙酰基只参入核心组蛋白,程度为H_3>H_(2b)>H_4>H_(2a)。Triton-尿素-丙烯酰胺凝胶电泳图放射自显影结果显示,无论心肌细胞核还是非心肌细胞核,在丁酸钠为1m mol/L情况下,组蛋白H_3又可见三个亚组分(H_(3_1)、H_(3_2)及H_(3_3)),H_4可分出四个亚组分(H_(4_1)、H_(4_2)、H_(4_3)及H_(4_4));其总组蛋白乙酰化程度减低至对照组数值的60％。“冷追击”实验的结果提示,丁酸钠引起高乙酰化组蛋白的积蓄,确是通过其对组蛋白脱乙酰基过程的抑制作用而实现的。     

New judgement on the source of soil water in extremely dry zone

There is always a relatively high moisture content in the shallow soil layer in Gobi area on the top of the Mogao Grottoes in the extremely dry zone. This paper gives out a new judgement on soil water source through field experiments using the isolated water method, simulated rainfall method and greenhouse method. Under the condition of typical hyper-arid climate far away from rainfall effect and after cutting off the connection of soil and groundwater the simulated rainfall experiment was conducted, through putting up a plastic greenhouse to obtain a relatively closed space and extracting the condensed water on the film surface, the soil water output from the greenhouse was monitored. The experimental results show that generally the rainfall can be completely evaporated in about 20 days under the isolated condition. In the relatively closed space sheltered by arched greenhouse in the Gobi area water can be continuously transferred outward from subsoil and condensed on the roof film, with a daily output quantity of 3–5 g/m²d. After prolonged output soil water content remains significantly higher than that of the control and before covering by arched shed. Comprehensively judging from this, groundwater is an important source of soil water in addition to precipitation. The new judgement has a very important practical significance to the water research of the groundwater–soil–plant-atmosphere circle (GSPAC) and the recovery of the desertified environment.