Fusion of protoplasts in Streptomyces antibioticus

The analysis of Streptomyces antibioticus recombinants isolated under non-selective conditions for stability of inheritance of parental properties demonstrated the existence of non-stable diploids and stable haploid recombinants. Also, genetic analysis of heteroclones isolated on selective medium after plating spores of regenerants was conducted. The results of analysis of haploid recombinant and heteroclones pointed to linkage of genetic loci and the possibility to use the technique of protoplast fusion for establishment of genetic map of S. antibioticus.     

New approach to the genetics of Streptomyces coelicolor

Sermonti, G. (Istituto Superiore di Sanità, Rome, Italy), Milena Bandiera, and Isabella Spada-Sermonti. New approach to the genetics of Streptomyces coelicolor. J. Bacteriol. 91:384-392. 1966.-Mixed cultures of complementary auxotrophic strains of Streptomyces coelicolor A3(2) were preincubated on discs of cellophane on complete medium and were then transferred onto selective media. When one strain was streptomycin-resistant and the other was streptomycin-sensitive, and the transfer medium contained streptomycin, distinct minute tufts of aerial mycelium appeared on the background growth of the mixed culture. They turned out to be heterozygous clones (heteroclones) in which the streptomycin-sensitive allele was, as a rule, missing. The pattern of marker contribution of the streptomycin-sensitive parent to the zygotes was indicative of a continuous structure carrying the hereditary material. A gradual transfer of the donor genome during conjugation was suggested by the progressive completion of the zygotes obtained by increasing preincubation time.     

Intergeneric crosses betweenStreptomyces ambofaciens andSaccharopolyspora erythraea

Upon crossing between auxotrophic mutants ofSaccharopolyspora erythraea andStreptomyces ambofaciens blocked in erythromycin and spiramycin biosynthesis, respectively, two types of recombinant colonies appeared on minimal medium—haploid recombinants and heteroclones. Based on morphological characteristics, the recombinants were grouped into three morphological types. Eight recombinants showed antibiotic activity in different parental combinations. In addition, seven of the recombinants produced a new antibiotic.     

Colonization of a hybrid strain to restore male Anastrepha ludens (Diptera: Tephritidae) mating competitiveness for sterile insect technique programs

To restore male mating competitiveness of Mexican fruit flies, Anastrepha ludens (Loew) (Diptera: Tephritidae), reared for sterile insect releases by the Mexican Fruit fly Eradication Campaign, two strain replacement techniques were evaluated. Field cage male competitiveness tests revealed that laboratory males of the Metapa strain mated 3 times less often with wild females than field-collected wild males. A strain developed from the cross of wild males and laboratory females (hybrid strain) was similar to a strain developed from the cross of laboratory males and females (laboratory strain) in that its females produced similar amounts of eggs and the eggs displayed similar levels of hatch and egg-to-pupa transformation in artificial diet. By contrast, a strain developed from the cross of wild males and females (wild strain), forced into artificial rearing, experienced a series of bottlenecks involving reduced egg laying and extremely poor development in diet. The male F1 progeny of the hybrid strain and field-collected wild males outcompeted Fl laboratory males in field cage tests for matings with field-collected wild females. In conclusion, we found that strains developed from the cross of wild males and laboratory females allowed us to restore male mating competitiveness of F1 Mexican fruit flies without compromising mass-rearing production.     

云南辛德毕斯病毒的生物学性状研究

本文对云南首次分离到的Sindbis病毒进行了滤过试验,耐酸耐醚试验、致细胞病变、动物敏感性试验、血压 凝特性、空斑和毒力等试验研究,结果符合披膜病毒科的病毒特性。交 因抑试验和免疫荧光试验,以及空斑减小中和试验进一步证实为甲病毒属的Sindbis病毒,其空斑纯化株的生物学特性也与原株相符,纯化株的制备为该株病毒分子生物学研究的准确性和一致性提供了条件。云南Sindbis病毒的首次分离具有重要的流行病学意义,其生物学特性研究结果对我省该病的诊断和防治具有重要的指导意义。     

褐飞虱抗甲胺磷品系的交互抗性和抗性生化机制

用甲胺磷筛选的褐飞虱Nilaparvata lugens品系（R）,对甲胺磷的抗性达到43.74倍,对马拉硫磷、二嗪磷、异丙威、仲丁威及醚菊酯都表现出一定的交互抗性,而对氰戊菊酯和吡虫啉的交互抗性不显著。为了研究褐飞虱对甲胺磷抗性和对其它药剂交互抗性产生的机制,进行了活体增效试验和离体生化实验。用2 μg/头的增效剂预处理试虫的活体增效实验结果显示,在甲胺磷筛选品系（R）中, TPP(triphenyl phosphate, 磷酸三苯酯)对甲胺磷的增效倍数达到4.54,TPP对马拉硫磷、二嗪磷、仲丁威、异丙威都表现出一定的增效作用,增效比分别为2.76、2.07、2.17和1.64;PBO(piperonyl butoxide,胡椒基丁醚)对甲胺磷、马拉硫磷和醚菊酯有一定的增效作用;DEM(diethyl meteate, 顺丁烯二酸二乙酯)的增效作用不明显。研究离体情况下增效剂对三种解毒酶活性的影响发现,TPP对R品系酯酶活力抑制作用很强（抑制率69.04%）,PBO对多功能氧化酶（MFO）具有一定的抑制作用（抑制率29.30%）,而TPP和PBO在F品系和S品系中对酯酶和MFO的抑制作用都较小;DEM在三个品系中对谷胱甘肽-S-转移酶的抑制作用都很小。由此可见,酯酶在褐飞虱对甲胺磷的抗性中起最主要作用,在马拉硫磷、二嗪磷、异丙威和仲丁威的交互抗性中起很重要作用;MFO可能在甲胺磷抗性和醚菊酯、马拉硫磷的交互抗性中起一定作用。     

棉铃虫对氰戊菊酯-辛硫磷混剂的抗性演化及解毒酶活性变化

用氰戊菊酯-辛硫磷混剂（有效成分1∶10,简称氰-辛混剂）对棉铃虫Helicoverpa armigera室内品系(YS)进行16代的抗性选育,获得棉铃虫对氰-辛混剂的抗性品系（YS-FP）。YS-FP品系与YS品系相比,对氰-辛混剂的抗性为14.7倍,对其中的单剂氰戊菊酯和辛硫磷的抗性分别为2 170倍和3.1倍。随着筛选的进行,氰戊菊酯和辛硫磷之间的共毒系数在F₂代出现短暂的增加,然后逐渐降低,它们之间的互作由增效变为拮抗。交互抗性测定结果表明,YS-FP品系对氯氰菊酯、溴氰菊酯、三氟氯氰菊酯、三唑磷和灭多威产生了明显的交互抗性,对硫丹、多杀菌素和爱玛菌素没有产生交互抗性。YS-FP品系6龄幼虫中肠细胞色素P450氧化酶甲氧基香豆素O-脱甲基活性为YS品系的10倍,3龄幼虫谷胱甘肽S-转移酶和酯酶活性分别是YS品系的1.7倍（CDNB结合作用）和2.4倍（α-NA 酯酶水解作用）。氰-辛混剂的筛选导致了棉铃虫多种解毒酶活性的增加,特别是细胞色素P450氧化酶活性增强最为明显。本研究结果表明氰-辛混剂对棉铃虫的筛选导致了广谱的交互抗性和多种代谢抗性机理,并且两个单剂之间的互作由增效变为拮抗,因此氰 辛混剂在棉铃虫抗性治理中的作用是有限的和暂时的。     

Hybrid Dysgenesis-Induced Quantitative Variation on the X Chromosome of Drosophila Melanogaster

To determine the ability of the P-M hybrid dysgenesis system of Drosophila melanogaster to generate mutations affecting quantitative traits, X chromosome lines were constructed in which replicates of isogenic M and P strain X chromosomes were exposed to a dysgenic cross, a nondysgenic cross, or a control cross, and recovered in common autosomal backgrounds. Mutational heritabilities of abdominal and sternopleural bristle score were in general exceptionally high-of the same magnitude as heritabilities of these traits in natural populations. P strain chromosomes were eight times more mutable than M strain chromosomes, and dysgenic crosses three times more effective than nondysgenic crosses in inducing polygenic variation. However, mutational heritabilities of the bristle traits were appreciable for P strain chromosomes passed through one nondysgenic cross, and for M strain chromosomes backcrossed for seven generations to inbred P strain females, a result consistent with previous observations on mutations affecting quantitative traits arising from nondysgenic crosses. The new variation resulting from one generation of mutagenesis was caused by a few lines with large effects on bristle score, and all mutations reduced bristle number.     

Movement of Drosophila melanogaster transposable elements other than P elements in a P-M hybrid dysgenic cross

Summary The Drosophila melanogaster mobile DNA sequences P factors and P elements transpose at elevated rates when P strain males are mated to M strain females in a hybrid dysgenic cross (Engels 1983). Isofemale lines derived from such a cross were analysed by in situ hybridisation using cloned copies of the transposable elements copia, 412 and F. It was found that lines derived from dysgenic crosses showed a statistically significant number of new sites for these elements when compared to a non-dysgenic control cross. This result suggests a functional coupling of copia, 412 and F transposition and some component present in the P-M dysgenic system.     

Inheritance of resistance in water yam (Dioscorea alata) to anthracnose (Colletotrichum gloeosporioides)

Colletotrichum gloeosporioides causes anthracnose, the most severe foliar disease of field-grown water yam (Dioscorea alata). The inheritance of resistance to a moderately virulent (FGS) strain of the pathogen was investigated in crosses between tetraploid D. alata genotypes: TDa 95/00328 (resistant)×TDa 95–310 (susceptible) (cross A), and TDa 85/00257 (resistant)×TDa 92–2 (susceptible) (cross B). Segregation of F₁ progeny fitted genetic ratios of 3:1, 5:1 (crosses A and B) and 7:1 (cross A) resistant:susceptible when inoculated with the FGS strain, indicating that resistance is dominantly inherited and suggesting that more than one gene controls the inheritance of resistance to this strain in the accessions studied. When parental and progeny lines of cross A were inoculated with an aggressive (SGG) strain of the pathogen, all plants expressed a susceptible phenotype, indicating strain-specific resistance in TDa 95/00328. Screening of 20 cultivars/landraces confirmed the high susceptibility of D. alata accessions to the SGG strain and revealed the presence of apparent strain non-specific resistance in TDa 85/00257. TDa 85/00257 and TDa 87/01091 which were resistant to the SGG strain, will be useful both as sources of resistance and in the development of a host differential series for D. alata. Received: 15 May 2000 / Accepted: 18 October 2000     

Abamectin resistance in strains of vegetable leafminer,Liriomyza sativae (Diptera: Agromyzidae) is linked to elevated glutathione S‐transferase activity

Abamectin resistance was selected in the vegetable leafminer, Liriomyza sativae (Blanchard) (Diptera: Agromyzidae) under laboratory conditions, and cross‐resistance patterns and possible resistance mechanisms in the abamectin‐resistant strains (AL‐R, AF‐R) were investigated. Compared with the susceptible strain (SS), strain AL‐R displayed 39‐fold resistance to abamectin after 20 selection cycles during 25 generations, and strain AF‐R exhibited 59‐fold resistance to abamectin after 16 selection cycles during 22 generations. No cross‐resistance to cyromazine was found in both abamectin‐resistant strains. However, we failed to select for cyromazine resistance in L. sativae under laboratory conditions by conducting 17 selection cycles during 22 generations. However, moderate levels of cross‐resistance to abamectin (6–9 fold) were observed in strains which received cyromazine treatments. Biochemical analysis showed that glutathione S‐transferase (GST) activity in both abamectin‐resistant strains (AL‐R, AF‐R) was significantly higher than in the susceptible strain (SS), suggesting metabolically driven resistance to abamectinin L. sativae. Recommendations of mixtures or rotation of cyromazine and abamectin should be considered carefully, as consecutive cyromazine treatments may select for low‐level cross‐resistance to abamectin.     

Biochemical and genetic characterization of esterase-27 (ES-27), the major plasma cholinesterase of the house mouse (Mus musculus)

Esterase-27A (ES-27A) was characterized in strain A/WySnA by a cascade of seven bands seen after disc electrophoresis of serum and subsequent staining for esterase. ES-27A catalyses the hydrolysis of thiocholine butyrate and is strongly inhibited by 100 microM tetraisopropyl pyrophosphamide (isoOMPA). Hence, the enzyme was concluded to be a cholinesterase EC 3.1.1.8. A heat-labile form termed ES-27B was represented by strain AKR/Han. From a three-point cross (AKR/Han, A/Wy) and a five-point cross (AKR/Han, SEG/1), the gene order on chromosome 3 was concluded to be centromere-Car-2-Es-26-Es-27-Amy-1-Adh-1.     

Radiation and transposon-induced genetic damage in Drosophila melanogaster: X-ray dose-response and synergism with DNA-repair deficiency.

The interaction of X-ray-induced and transposon-induced damage was investigated in P-M hybrid dysgenesis in Drosophila melanogaster. The X-ray dose-response of 330-1320 rad was monitored for sterility, fecundity and partial X/Y chromosome loss among F2 progeny derived from the dysgenic cross of M strain females xP strain males (cross A) and its reciprocal (cross B), using a weaker and the standard Harwich P strain subline. The synergistic effect of P element activity and X-rays on sterility was observed only in cross A hybrids and the dose-response was nonlinear in hybrids derived from the strong standard reference Harwich subline, Hw. This finding suggests that the lesions induced by both mutator systems which produce the synergistic effect are two-break events. The effect of increasing dose on the decline of fecundity was synergistic, but linear, in hybrids of either subline. There was no interaction evident and thus no synergism in X/Y nondisjunction and in partial Y chromosome loss measured by the loss of the Bs marker alone or together with the y+ marker. Interaction was detected in the loss of the y+ marker alone from the X and Y chromosomes. The possible three-way interaction of X-rays (660 rad), post-replication repair deficiency and P element mobility was assessed by measuring transmission distortion in dysgenic males derived from the II2 P strain. X-Irradiation of spermatids significantly increased the preferential elimination of the P-element-bearing second chromosome in mei-41, DNA-repair-deficient dysgenic males, but had no effect in their DNA-repair-proficient brothers. These findings indicate that the post-replication repair pathway is required for processing lesions induced by the combined effect of P element mobility and X-rays, and that the unrepaired lesions ultimately lead to chromosome loss.     

中国和日本分离的几株流行性出血热病毒的抗原性比较

采用间接免疫荧光法(IFA)和ELISA法比较了几株中国和日本流行性出血热病毒(EHFV)的抗原性,IFA法不能区分大鼠属和姬鼠属来源的病毒,ELISA竞争试验表明,大鼠型病毒(R22、SR-11和TR-352株)与姬鼠型病毒(A 9株)存在弱单向交叉反应,交叉ELISA证实,A 9株与R22株、SR-11株和TR-352株均有较显著的抗原性差异,但R22,SR-11和TR-352株彼此间抗原性相近,本文讨论了有关EHFV抗原性比较中的一些问题。     

用溴氰菊酯选育抗敌百虫淡色库蚊的研究

将室内选育成功的抗敌百虫淡色库蚊Culex pipiens pallens Coq.品系(RD)分为二个分系,一个不再用敌百虫处理,称之为RD衰退品系(RD_139-x),34代后对敌百虫的敏感度增加了10倍,对溴氰菊酯的敏感度无显著变化.另一分系改用溴氰菊酯选育,命名为Rde品系,53代后对溴氰菊酯抗性达200倍左右,对敌百虫敏感度上升约10倍,对DDT的交互抗性高达118倍,对马拉硫磷、杀螟硫磷的敏感度与敏感品系(SEN,上海昆虫所保存)比较也有上升,呈负交互抗性现象.用高剂量溴氰菊酯处理幼虫、也证明Rde在20分钟内麻痹率比敏感品系低,可见抗性机制主要是抗击倒因子(Kdr).但增效醚(Pb)对溴氰菊酯明显增效,可见mfo酶也起重要作用,推测抗性为多因子遗传.     

Genetic analysis of autoimmune sialadenitis in nonobese diabetic mice: a major susceptibility region on chromosome 1

The nonobese diabetic (NOD) mouse strain provides a good study model for Sj?gren's syndrome (SS). The genetic control of SS was investigated in this model using different matings, including a (NOD x C57BL/6 (B6))F(2) cross, a (NOD x NZW)F(2) cross, and ((NOD x B6) x NOD) backcross. Multiple and different loci were detected depending on parent strain combination and sex. Despite significant complexity, two main features were prominent. First, the middle region of chromosome 1 (chr.1) was detected in all crosses. Its effect was most visible in the (NOD x B6)F(2) cross and dominated over that of other loci, including those mapping on chr.8, 9, 10, and 16; the effect of these minor loci was observed only in the absence of the NOD haplotype on chr.1. Most critically, the chr.1 region was sufficient to trigger an SS-like inflammatory infiltrate of salivary glands as shown by the study of a new C57BL/6 congenic strain carrying a restricted segment derived from NOD chr.1. Second, several chromosomal regions were previously associated with NOD autoimmune phenotypes, including Iddm (chr.1, 2, 3, 9, and 17, corresponding to Idd5, Idd13, Idd3, Idd2, and Idd1, respectively), accounting for the strong linkage previously reported between insulitis and sialitis, and autoantibody production (chr.10 and 16, corresponding to Bana2 and Bah2, respectively). Interestingly, only two loci were detected in the (NOD x NZW)F(2) cross, on chr.1 in females and on chr.7 in males, probably because of the latent autoimmune predisposition of the NZW strain. Altogether these findings reflect the complexity and heterogeneity of human SS.     

The in vitro Resistance to Antibiotics of Mycoplasma mycoides var. capri

S ummary . Resistance to dihydrostreptomycin, chloramphenicol and oleandomcin has been induced in vitro in a strain of Mycoplasma mycoides var. capri. The chloramphenicol resistant strain showed high resistance to oleandomycin, but the converse was not observed. The same cross resistance was also found, but to only a very small extent, in Staphylococcus aureus and Streptococcus faecalis. No cross resistance was found in three other species of bacteria examined. The osmotic lysis of the normal and the chloramphenicol resistant strains of M. mycoides var. capri were similar.     

Electromechanical feedback with reduced cellular connectivity alters electrical activity in an infarct injured left ventricle: a finite element model study

Myocardial infarction (MI) significantly alters the structure and function of the heart. As abnormal strain may drive heart failure and the generation of arrhythmias, we used computational methods to simulate a left ventricle with an MI over the course of a heartbeat to investigate strains and their potential implications to electrophysiology. We created a fully coupled finite element model of myocardial electromechanics consisting of a cellular physiological model, a bidomain electrical diffusion solver, and a nonlinear mechanics solver. A geometric mesh built from magnetic resonance imaging (MRI) measurements of an ovine left ventricle suffering from a surgically induced anteroapical infarct was used in the model, cycled through the cardiac loop of inflation, isovolumic contraction, ejection, and isovolumic relaxation. Stretch-activated currents were added as a mechanism of mechanoelectric feedback. Elevated fiber and cross fiber strains were observed in the area immediately adjacent to the aneurysm throughout the cardiac cycle, with a more dramatic increase in cross fiber strain than fiber strain. Stretch-activated channels decreased action potential (AP) dispersion in the remote myocardium while increasing it in the border zone. Decreases in electrical connectivity dramatically increased the changes in AP dispersion. The role of cross fiber strain in MI-injured hearts should be investigated more closely, since results indicate that these are more highly elevated than fiber strain in the border of the infarct. Decreases in connectivity may play an important role in the development of altered electrophysiology in the high-stretch regions of the heart.     

Outbreak of systemic Candida albicans in intensive care unit caused by cross infection.

The first documented outbreak of systemic candidosis shown to be due to cross infection with a particular strain of Candida albicans is reported. Over nine months in an intensive care unit 13 patients developed definite and one probable systemic candidosis. Twenty five further patients had superficial candidal infections. The strain that caused the outbreak (serotype A, morphotype A1, biotype 0/(1)5 5/7) was responsible for all the cases of systemic candidosis acquired in the intensive care unit, 11 (44%) of the superficial candidal infections in the unit, and 17% of candidal infections outside the unit but in the same hospital. The strain was also isolated from oral swabs taken from four nurses working in the unit and the hands of one of these nurses. Two out of 17 nurses were shown to have acquired the strain on their hands when examined immediately after nursing systemically infected patients. No environmental source could be identified. The strain also showed enhanced survival in handwashing experiments and was relatively resistant to Hibiscrub. Management of patients with systemic candidosis might include measures to prevent cross infection and handwashing with disinfectants that are active against candida.     

Maternally transmitted resistance to lymphoma development in mice of reciprocal crosses of the RF/J and AKR/J strains

Females but not males of the low-lymphoma RF/J strain transmit a non-Mendelian factor which suppresses the development of lymphoma in F1 crosses with mice of the high-lymphoma AKR/J strain. Suppression of lymphoma was also evident in the first backcross generation to the parental AKR strain, but only when (RF female x AKR male)F1 mice had been the female parent. This "maternal resistance factor" was transmitted independently of the dominant, lymphoma-suppressing Fv-1n allele transmitted by both males and females of the RF strain, but the suppressive capacities of the two factors appeared to be additive. In this cross, F1 progeny of RF females also showed marked suppression of ecotropic murine leukemia virus expression by comparison with mice of the reciprocal F1 cross, but this suppression of virus expression was not detected in the lymphoma-suppressed AKR backcross population. The observation of lymphoma suppression in the absence of ectropic virus suppression in mice of the (RF X AKR)F1 female x AKR male backross generation indicates a qualitative or quantitative difference in the determination of these two effects.