Two forms of cytochrome P450 cDNA from 3-methylcholanthrene-treated European eel Anguilla anguilla

ABSTRACT:     The cytochrome P450 (CYP) represents a large group of microsomal monooxygenases that catalyze drugs as well as a host of lethal environmental contaminants such as dioxins, leading to either detoxification and excretion from the animal or generation of carcinogenic intermediates. In the present study two forms of cDNA were cloned (Eu MC1 and Eu MC2) for European eel CYP1A genes by polymerase chain reaction (PCR) techniques. The cDNA of Eu MC1 was 3368 bp long coding 521 amino acid residues, and that of Eu MC2 was 2464 bp long coding 517 amino acid residues. Identities of deduced amino acid sequences between Eu MC1 and Japanese eel CYP1A1 and that between Eu MC2 and the second form of Japanese eel CYP1A were 98% and 97%, respectively, showing decisively that Eu MC1 and Eu MC2 are orthologous to Japanese eel CYP1A1 and the second form of CYP1A, respectively. A striking difference between the two eel species was that the Eu MC1 peptide was two amino acid residues longer than that of the Japanese eel CYP1A1. Existence of two loci of CYP1A in Japanese and European eels may suggest that the two forms of CYP1A exist widely among the eel species, because the divergence between the two eel species has been shown to be close to the basal divergence among eels. The identities in CYP1A may help to estimate genetic distance between European and Japanese eels.     

Bactericidal activity of cecropin B and cecropin P1 expressed in fish cells (CHSE-214): application in controlling fish bacterial pathogens

Cecropins are a group of antimicrobial peptides which have bactericidal activity against a broad range of bacteria. To date, the cecropins used in a variety of studies were either purified from their natural source or obtained by chemical synthesis. The present study was conducted to test whether bactericidally active cecropins could be expressed in a fish cell line. For this purpose, Chinook salmon embryo cells (CHSE-214) were transfected with cecropin transgene constructs: Hyalophora cecropia preprocecropin B, procecropin B, cecropin B, and porcine P₁ cecropin. From the transfected cells, single cell clones were selected and screened for the presence of cecropin gene constructs by PCR amplification. The expression of the cecropin transgene in the PCR positive clones was determined by RT-PCR reaction. Southern blot hybridization results showed that the cecropin gene constructs were integrated into the genome in a multiple integration pattern. Bactericidal activity of the cecropins, synthesized from transgene constructs, was detected using inhibition zone assay for fish pathogenic bacteria: Aeromonas hydrophila, Pseudomonas fluorescens, and Vibrio anguillarum. Cecropin antimicrobial peptides produced in CHSE-214 cells possess bactericidal activity against these three fish pathogenic bacteria.     

华山松单萜和倍半萜组分的地理变异

用气相色谱-质谱-计算机联用仪鉴定了华山松皮油树脂中12种成分。对贵州省平坝县华山松良种场华山松种源试验林中13个种源树皮含油树脂样品分析,观察到单萜总量和倍半萜总量,包括α-蒎烯、双戊烯和蛇麻烯等成分的含量与其种源产地纬度有极明显的地理变异规律。云贵高原种源为以双戊烯为主的单萜类型;秦岭—大巴山地种源是以蛇麻烯为主的倍半萜类型。     

高山禾草─嵩草型草地的磷循环

对磷在高山禾草─嵩草型草地土壤─植物─绵羊系统（７～１０月）中的循环进行了研究。结果表明，０～６０ｍ深度土壤全磷贮量４４７５．３～４７９９．８ｋｇ／ｈｍ２（ＣＶ＝３．０９％），速效磷贮量８６．５～１２３．９ｋｇ／ｈｍ２（ＣＶ＝１３．９６％）。磷在土壤─植物转化阶转化率最大值仅０．１２３５％，磷在植物─绵羊各转化阶的转化率均以１０月为分界点，１０月以后锐减。７～９月土壤库磷处于消耗状态，绵羊库磷处于积累状态。从１０月开始，土壤库磷处于积累状态，绵羊库磷处于消耗状态。磷在土壤库、植物库和绵羊库之间的分布极不平衡，土壤库占９９．８６％～９９．９３％，植物库占０．０６４２２％～０．１２８２％，而绵羊库仅占０．００７２２５％～０．０１３６３％。     

A total-continuous portal vein fistula in gastrointestinal and toxicology research

A method for the total collection of portal vein blood over extended periods has been developed. The method has been applied in gastrointestinal toxicology research involving rats. The method facilitated quantitative recovery of portal vein blood for 120 min for measurement and identification of absorbed radiolabeled components derived from a toxic lipphilic pesticide placed in the lumen of the small intestine. The method can be applied to any substance—nutrient, anutrient, xenobiotic chemical, or endocrine factor—absorbed into the portal vein from the gastrointestinal tract. The method (a) provides for collection of compounds absorbed from the gastrointestinal tract before distribution to nondigestive tissues (i.e., liver), (b) allows measurement of the compounds absorbed without the need to monitor flow rate, and (c) facilitates accumulation of sufficient material from the total portal circulation for analyses when submicrogram quantities are absorbed. The latter two features are important but impossible to attain with small samples of portal blood and are crucial in research with minute quantities of substrate. These features become requirements in metabolism and toxicology research. The method involves replacement of the portal blood with a suspension of perfluorohydrocarbons to substitute for the major functions of natural blood. The total-continuous portal vein fistula makes it possible to investigate metabolic and transport phenomena in live animals which previously could be explored only by in vitro methods. The method may be applied to conscious animals with further refinements.     

Influence of phenamiphos on the vesicular-arbuscular mycorrhizal symbiosis in Leucaena leucocephala

Summary Concentrations of phenamiphos ranging from 0 to 40 rg/g soil were established in a typical Oxisol (Tropeptic Eutrustox), inoculated or uninoculated with Glomus aggregatum. The effect of the nematicide on the development of vesicular-arbuscular mycorrhizal (VAM) symbiosis was evaluated in the greenhouse using Leucaena leucocephala as an indicator host plant. Treatment of soil with phenamiphos did not have a significant influence on the development of mycorrhizal activity measured in terms of subleaflet phosphorus concentrations. Similarly, the nematicide did not have an adverse effect on the level of mycorrhizal colonization or on the P content of shoots, as determined at the time of harvest. However, shoot dry weight was adversely influenced by phenamiphos when the chemical was applied to the uninoculated soil at 20 g/g soil or higher, and when it was applied to the inoculated soil at 40 g/g soil. It is concluded that phenamiphos is not likely to influence the growth of Leucaena or its symbiotic association with VAM fungi if the concentrations applied do not exceed levels known to suppress nematodes.Hawaii Institute of Tropical Agriculture and Human Resources Journal series No. 3146     

Landowner Perceptions of Legal Liability for Using Prescribed Fire in the Southern Plains,United States

Suppression of fire in the Southern Plains has led to proliferation of woody plants and fuel load accumulation that spurs wildfires. These effects have led to calls for widespread application of prescribed fire to reduce fuel loads, but there is substantial landowner resistance to the use of this land management tool. Here we explore factors that affect perceptions of landowners in the Southern Plains about prescribed fire liability and their willingness to apply this land management tool. This region was selected for the study because of the preponderance of private landholdings and widespread woody plant encroachment. The study used a mail survey of 1 853 landowners in 16 counties in Texas and Oklahoma, resulting in a data set from 680 respondents (37% useable response rate). Logistic regression models were developed to test three hypotheses relating to the likelihood that a landowner will apply prescribed fire. The study corroborated that landowners who perceived higher levels of fire-related legal liability were less likely to apply prescribed fire on their land or assist with its application on other properties. In addition, burn bans were found to inhibit landowner willingness to apply fire during periods that result in higher woody plant mortality. Oklahoma respondents, landowners who believed prescribed fire to be an affordable woody plant management tool, and members of prescribed burning associations (PBAs) were more likely to use prescribed fire. These results have important implications for policies aimed at overcoming resistance to the use of prescribed fire to curb woody plant encroachment and reduce fuel load accumulation. Specifically, language in state statutes pertaining to prescribed fire should be modified to reduce landowner concerns over legal liability; PBAs should be established more widely; and public cost-sharing funds for woody plant management should prioritize prescribed fire.     

Involvement of cytochrome P‐450 enzyme activity in the selectivity and safening action of pyrazosulfuron‐ethyl

To investigate the selectivity and safening action of the sulfonylurea herbicide pyrazosulfuron‐ethyl (PSE), pyrazosulfuron‐ethyl O‐demethylase (PSEOD) activity involving oxidative metabolism by cytochrome P‐450 was studied in rice (Oryza sativa L cv Nipponbare) and Cyperus serotinus Rottb. Cytochrome P‐450‐dependent activity was demonstrated by the use of the inducers 1,8‐naphthalic anhydride and ethanol, the herbicides PSE, bensulfuron‐methyl, dimepiperate and dymron, or the inhibitor piperonyl butoxide (PBO). Growth inhibition in C serotinus seedlings was more severe than that in rice seedlings. O‐Dealkylation activities of PSE were induced differently in rice and in C serotinus, with distinctly higher activity in rice seedlings. The induced PSEOD activities were slightly inhibited by PBO in rice seedlings, whereas they were strongly inhibited in C serotinus seedlings. Dimepiperate and dymron were effective safeners of rice against PSE treatment. Treatments with herbicide alone resulted in less induction of PSEOD activity compared with combined treatments of the herbicide and safener. PSEOD activity in rice seedlings induced with herbicide alone was strongly inhibited by PBO, whereas it was weakly inhibited in rice seedlings induced with combinations of PSE and two safeners. These results suggest that O‐demethylation by cytochrome P‐450 enzymes may be involved in the metabolism of PSE and may contribute to its selectivity and safening action. Furthermore, these results suggest the existence of a multiple form of cytochrome P‐450 in plants. © 2001 Society of Chemical Industry     

Responses of Adenohypophyseal Hormones to Substance P Administration in Geldings: Comparison to Responses After Brief Exercise and Sulpiride Administration

Nine adult geldings were used in three experiments to study the possible role of substance P in the prolactin responses to nondopaminergic stimuli. Experiment 1 was performed as an incomplete Latin square design to determine the secretory responses of prolactin, growth hormone (GH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) to IV administration of substance P. Doses tested and compared to no peptide (0 dose, control) were 62, 125, 250, and 500 μg of substance P. The three highest doses of peptide caused an immediate rise in heart rate, sweating, salivation, rhinorrhea, stretching of hind legs, and defecation. The lowest dose (62 μg) caused minor sweating, some rhinorrhea, and a rise in heart rate. Recovery from these physical responses was complete in approximately 30 minutes. All doses of substance P caused an immediate rise (P < .01) in plasma prolactin concentrations, with the three highest doses producing similar responses, and the 62 μg dose producing a minimal response (P < .05). Concentrations of ACTH (P < .01) and GH (P = .05) also increased after substance P administration; concentrations of LH, FSH, and TSH were unaffected. Experiment 2 compared the effects of brief exercise on hormonal characteristics. Two minutes of trotting increased (P < .01) plasma concentrations of GH, ACTH, and prolactin, as well as LH (P = .055). Experiment 3 determined the relative responses of prolactin to a fixed dose of sulpiride (0.1 mg/kg of body weight). In general, the prolactin responses to substance P were similar to those after exercise, which were both generally less than after sulpiride. These data are consistent with a possible role of substance P in the prolactin response to stressful stimuli.