<Emphasis Type="Italic">Lupinus albus</Emphasis> Conglutin Gamma Modifies the Gene Expressions of Enzymes Involved in Glucose Hepatic Production <Emphasis Type="Italic">In Vivo</Emphasis>

Lupinus albus seeds contain conglutin gamma (Cγ) protein, which exerts a hypoglycemic effect and positively modifies proteins involved in glucose homeostasis. Cγ could potentially be used to manage patients with impaired glucose metabolism, but there remains a need to evaluate its effects on hepatic glucose production. The present study aimed to analyze G6pc, Fbp1, and Pck1 gene expressions in two experimental animal models of impaired glucose metabolism. We also evaluated hepatic and renal tissue integrity following Cγ treatment. To generate an insulin resistance model, male Wistar rats were provided 30% sucrose solution ad libitum for 20 weeks. To generate a type 2 diabetes model (STZ), five-day-old rats were intraperitoneally injected with streptozotocin (150 mg/kg). Each animal model was randomized into three subgroups that received the following oral treatments daily for one week: 0.9% w/v NaCl (vehicle; IR-Ctrl and STZ-Ctrl); metformin 300 mg/kg (IR-Met and STZ-Met); and Cγ 150 mg/kg (IR-Cγ and STZ-Cγ). Biochemical parameters were assessed pre- and post-treatment using colorimetric or enzymatic methods. We also performed histological analysis of hepatic and renal tissue. G6pc, Fbp1, and Pck1 gene expressions were quantified using real-time PCR. No histological changes were observed in any group. Post-treatment G6pc gene expression was decreased in the IR-Cγ and STZ-Cγ groups. Post-treatment Fbp1 and Pck1 gene expressions were reduced in the IR-Cγ group but increased in STZ-Cγ animals. Overall, these findings suggest that Cγ is involved in reducing hepatic glucose production, mainly through G6pc inhibition in impaired glucose metabolism disorders.     

Assessing seed desiccation responses of native trees in the Caribbean

New Forests - Native trees from the Caribbean were tested for seed desiccation responses, by adapting the “100-seed test” protocol. Ninety-seven seed lots of 91 species were collected...     

Determination of sulfamethazine and trimethoprim in liquid feed premixes by HPLC and diode array detection, with an analysis of the uncertainty of the analytical results.

Sulfamethazine (SMZ) and trimethoprim (TMP) are antibacterials used in veterinary practice. This paper describes a method for their determination in veterinary liquid feed premixes that is based on liquid chromatography with diode array detection. Gradient elution with methanol and ammonium acetate achieved excellent separation of the two analytes within 15 min without any interference from the matrix. Absorbance of the column effluent was monitored at 264 nm for SMZ and at 230 nm for TMP. Detailed analyses of the uncertainties of determinations afford estimated expanded uncertainties of, respectively, 0.2 and 0.1 w/v % for typical SMZ and TMP concentrations of 10.7 and 2.1 w/v %, respectively. At the lower end of the calibrated range of the method, the dominant source of uncertainty is the preparation of standards and the construction of the calibration line.     

Dynamics of chlorinated pesticide residues in long-term storage of canned food

Meat tins denoted as pork in natural juice, beef with bacon, luncheon meat and liver paté, all produced in a food-processing plant, were stored under definite conditions (temperature 21 degrees C, relative humidity 73%) for three years. Before the long-term storage and then in half-year intervals, the contents of the residues of chlorinated pesticides, including HCB (hexachlorobenzene), gamma-HCH (gamma isomer of hexachlorocyclohexane) and pp'DDE (1,1-dichloro-2,2-bis/p-chlorofenyl/-ethylene), were determined in the above-mentioned final products by the method of gas chromatography. As suggested by the records of the changes in the pesticide residue contents in the meat tins during their long-term storage, the average contents of all chlorinated carbohydrates gradually decrease with the length of storage and the "reduction" of residues varies with the kind of final product and with the pesticides. In HCB the reduction ranged from 18.4 to 34.4%, in gamma-HCH from 36.2 to 80.4% and in pp'DDE from 23.9 to 48.9%.     

中国水稻三化螟防治研究的进展

在中国为害水稻較重的螟虫已知有6种,以三化螟 Tryporyza incertulas (Wlk.)最为重要,分布于我国中南部稻区。本文阐述了气候、食料、水稻栽培制度和生物等因素对三化螟种群数量变动的影响,并指出作为螟虫食料的水稻及其栽培制度的作用更为明显。研究証明,三化螟的产卵、侵入、成活、繁殖和为害都与水稻的生育期有密切关系,水稻的分蘖期及孕穗期,都是水稻最易受害的生育期,在这两个时期被害,会造成枯心或白穗;而秧田期、移植至回青期、圓稈期和成熟期都对螟虫不利。螟虫的发生基数和生活环境条件,密切影响种群数量的变动,而这些都受水稻栽培制度的影响。发生基数决定于春季螟虫的有效虫源,其数量的大小对当年的螟虫,尤其对第一、二代的发生量有密切关系。螟害程度主要决定于:(1)种群数量和(2)水稻最易受害的生育期与螟虫盛发期配合程度的综合作用。为了加強防治,各地区必须因地制宜,利用耕作栽培措施,一方面尽可能消灭虫源、压低发生基数、控制以后各代螟虫的发生;另一方面力求改进栽培技术、調节水稻生育期,恶化螟虫的生活条件,避免或減輕螟害。化学防治也是治螟的一項重要措施。目前广泛应用的药剂是6％丙体六六六,每亩用量在防治枯心时为1.5斤,防治白穗为2斤。主要的施药方法为泼浇和撒毒土,两者对防治枯心的效果都很好;撒毒土防治白穗的效果虽稍差,但操作簡便易行。在螟虫发生期內,适值分蘖和孕穗的水稻田一般都要施药;但預测螟害低于1％的田块,可不防治。防治枯心的施药适期一般在孵化高峯前1—2天天开始,如虫量很大,要提前到盛孵始期用药。防治白穗的施药适期是:在蚁螟盛孵前孕穗的水稻,普通在盛孵始期开始施药;蚁螟盛孵后孕穗的水稻,在孕穗始期开始用药。稻螟是我国长期以来的一种严重害虫,解放前因螟害常年損失稻谷10％以上。解放后,在党和政府的領导下,科学技术有了显著的进展,治螟工作貫彻了“防治并举、以防为主”的方針,“以农业防治为基础,重点使用药剂綜合防治”的策略;采用了准确的預测預报;开展了群众性的防治活动,基本上控制了螟虫的危害,1663年的螟害率已压低到2％左右,不少地区已降低到1％以下。这都是在总路线、大跃进、人民公社三面紅旗光輝照耀下,領导、技术人員、群众三結合所取得的成果的     

北京地区春玉米螟害产量损失估计方法及防治指标的商榷

根据1962—1964年北京地区12块春播玉米地心叶期卵和卵虫(第一代)成活率資料,并参考国内对螟害与玉米产量損失关系的研究成果,提出了春玉米上因玉米螟为害而造成的产量損夫估計方法和药剂防治的参考指标。心叶期卵的平均成活率及其标准誤为57.4±2.9％,卵块的脫落是死亡的主要原因。幼虫期的平均成活率及其标准誤为5.64±0.89％。这两个平均成活率的变異系数都比较小,相关分析表明,百株着卵量与成长幼虫数是相关的。故可职利用卵和幼虫的平均成活率由着卵密度来估計成长幼虫密度。心叶期卵和幼虫的合計平均成活率及其标准誤为3.4±0.51％。在95％可靠性时的置信区間为3.4±1.173％,卵块的平均粒数为31.7粒。若职单株平均一虫所造成的产量損失率为5％計,可用丁式来估計产量損失: 产量損失％=[(心叶期百株累計卵块数×31.7)×(0.034±0.012)]×0.05 在經济核算士,作者初步認为职損失率1.5％作为防治标准比較合适。以此推算,欲达到这一損失率,心叶期百株累計卵块应为28块(用平均成活率計算)至21块(用成活率上界計算)。一般可定为24块。根据心叶期百株累計卵块数与累計着卵株百分率或百株高峯卵块数之間存在的相关,百株累計24块卵,相当于累計着卵株率28％,或百株高峯卵块6块。在实践上就可以用它們作为心叶期的防治指标。     

小麦丛矮病研究之三:灰飞虱同发病的关系

1976—1977年河北晋县贺家寨大队小麦春季灰飞虱的传带病毒率为31—52%,不同地块同代灰飞虱的带毒率异差较大:而秋苗期则为12—35.4%,其中不同地块上同代(四代成虫)灰飞虱的带毒率的差异从33.3%至35.4%则不太大。灰飞虱的有效传毒指数(即虫口数×自然带毒率)同田间小麦发病率的相关性是非常显著的,其r=0.9769。1975—1976两年调查及计算分析结果,其直线回归公式如y=4.12x-2.577。在有效传毒指数0.7—20.9之间用于予测发病率有效。人工分期侵染试验证明小麦在生长发育过程中受侵愈早,病情愈重,其中死株率也愈大。秋季侵染的死株率达95.6%,病指为99.6;夏季侵染的死株率为0,病指为57.6。秋季小麦出苗前后的大量虫口形成小麦10月中下旬的一个发病高峰,第二年春季4月中旬的虫口高峰形成5月上旬的一个发病高峰。3月下旬的一个发病高峰是越冬前受侵的。病毒在小麦植株中的潜育期的长短随小麦的生长速度而异。温度不过其中因素之一,最短5—8天,最长30—40天。侵染后如小麦进入越冬期,即不表现症状,一直要到返青以后。介体灰飞虱在河北晋县以第五代3—4龄若虫在冬麦地及草荒中越冬。夏季在玉米上可以产卵并孵化,但不能长期存活,主要在地头沟边及夏作物荫蔽下的禾草上越夏。冬麦治虫防病的重点应在秋季麦苗出土前,春季则应在3月中旬左右。冬麦适当推迟播种有利于减少发病率。棉间作麦比平作的病情重六倍而粮麦间作的病情比平作的重九倍。     

Precocene II metabolism: Comparative in vivo studies among several species of insects,and structure elucidation of two major metabolites

Several species of insects, exhibiting varying responsiveness to the juvenile hormone antagonist precocene II (6,7-dimethoxy-2,2-dimethylchromene), were challenged topically with a tritiated preparation of the title compound. Metabolism of [³H]precocene II was subsequently examined by withdrawing hemolymph samples from treated animals at appropriate time intervals and characterizing the extractable radiolabel chromatographically. Quantitative (or qualitative) differences observed between the respective metabolic profiles were found not correlative with specimen sensitivity to precocene. Production of two heretofore unreported metabolites, identified by spectral and chemical means as O-β-glucosides of 6- and 7-monodemethylated precocene II, was demonstrated in both sensitive and insensitive species. No evidence for the presence of a hemolymphborne, biologically effective “activated metabolite” produced in vivo by precocene-susceptible insects could be found. The latter finding may well argue for in situ bioactivation of precocene at the target tissue(s) by these sensitive insects.     

Identification ofTomato Mottle Taino Begomovirus strains in Cuban potato fields

The presence of a begomovirus in potato plants with yellow mottle symptoms was determined for the first time in Cuba. The incidence of typical begomovirus-like symptoms in potato plants in some regions of Havana province (Güira de Melena, San José de las Lajas, Güines and Boyeros) during the growing seasons from 1992 to 1998 was in general low. However, in some cultivars belonging to the National Program for Potato Genetic Improvement, the incidence reached 100%. Yield losses, determined in 1992 and 1994, ranged as high as 19% to 56.33% depending on the cultivar. Characterization of the causal agent was done by light microscopy, host range (graft and mechanical transmission), DNA hybridizations, polymerase chain reaction, and restriction fragment length polymorphism analysis. Nucleotide sequence of the amplified fragments revealed the presence ofTomato mottle Taino virus. The virus was transmittedvia tubers and has been detected in mixed infections withPotato virus X and withPotato leaf roll virus. http://www.phytoparasitica.org posting Oct. 20, 2003. The first two authors contributed equally to this work.